WORK VEHICLE

Abstract

A hybrid transmission includes an electric transmission including a motor generator, and a gear transmission including a gear driver without a motor generator. A transmission case includes an electric transmission chamber in which the electric transmission is accommodated, and a gear transmission chamber in which the gear transmission is accommodated, the electric transmission chamber and the gear transmission chamber being adjacent to each other. The transmission case includes a partition wall separating the electric transmission chamber from the gear transmission chamber in a non-communication manner.

Claims

1. A hybrid work vehicle, comprising: an engine; a hybrid transmission including: an electric transmission and a gear transmission; the electric transmission and the gear transmission positioned along a vehicle-body front-rear direction, the electric transmission including a motor generator, the gear transmission including a gear driver without a motor generator, the hybrid transmission being operable to vary power from the engine and output the power to a travel device; and a transmission case in which the hybrid transmission is accommodated, the transmission case being provided in a vehicle body in a state where the transmission case is side by side with the engine along the vehicle-body front-rear direction; wherein the transmission case includes: an electric transmission chamber in which the electric transmission is accommodated; and a gear transmission chamber in which the gear transmission is accommodated; the electric transmission chamber and the gear transmission chamber being adjacent to each other; and the transmission case includes a partition wall separating the electric transmission chamber from the gear transmission chamber in a non-communication manner.

2. The hybrid work vehicle according to claim 1, wherein the motor generator includes two motor generators.

3. The hybrid work vehicle according to claim 1, wherein the electric transmission is between the engine and the gear transmission.

4. The hybrid work vehicle according to claim 1, wherein respective lubricants are accumulated in the electric transmission chamber and in the gear transmission chamber; and the lubricant in the electric transmission chamber has a level different from a level of the lubricant in the gear transmission chamber.

5. The hybrid work vehicle according to claim 4, wherein the level of the lubricant in the electric transmission chamber is lower than the level of the lubricant in the gear transmission chamber.

6. The hybrid work vehicle according to claim 1, wherein respective lubricants are accumulated in the electric transmission chamber and in the gear transmission chamber; and the lubricant accumulated in the electric transmission chamber and the lubricant accumulated in the gear transmission chamber are different in oil quality.

7. The hybrid work vehicle according to claim 1, further comprising: a first oil supplier to supply a lubricant to the motor generator and including: a first hydraulic pump; and a first oil supply passage connecting the first hydraulic pump to the electric transmission chamber; and a second oil supplier to supply a lubricant to the gear driver and including: a second hydraulic pump; and a second oil supply passage connecting the second hydraulic pump to the gear transmission chamber.

8. The hybrid work vehicle according to claim 1, wherein the engine is in a front portion of the vehicle body; and the transmission case is behind the engine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a side view illustrating the entire structure of a tractor.

[0027] FIG. 2 is a schematic view of a traveling power transmission device.

[0028] FIG. 3 is an explanatory view in a case where a transmission case has an inclined posture in which its front portion is lowered.

[0029] FIG. 4 is a circuit diagram of a first oil supply mechanism.

[0030] FIG. 5 is a circuit diagram of a second oil supply mechanism.

[0031] FIG. 6 is a circuit diagram of an oil supply mechanism according to a different preferred embodiment of the present invention.

[0032] FIG. 7 is a schematic view illustrating a traveling power transmission device according to a first different preferred embodiment of the present invention.

[0033] FIG. 8 is a front view illustrating the arrangement of motor generators in the traveling power transmission device according to the first different preferred embodiment of the present invention.

[0034] FIG. 9 is a schematic view illustrating a traveling power transmission device according to a second different preferred embodiment of the present invention.

[0035] FIG. 10 is a schematic view illustrating a traveling power transmission device according to a third different preferred embodiment of the present invention.

[0036] FIG. 11 is a schematic view illustrating a traveling power transmission device according to a fourth different preferred embodiment of the present invention.

[0037] FIG. 12 is a schematic view illustrating a traveling power transmission device according to a fifth different preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Preferred embodiments as examples of the present invention will be described below with reference to the drawings.

[0039] Note that, in the following description, in terms of a traveling vehicle body of a tractor (an example of a “hybrid work vehicle”), a direction of an arrow F illustrated in FIG. 1 and so on is referred to as a “vehicle-body front side,” a direction of an arrow B is referred to as a “vehicle-body rear side,” a direction of an arrow U is referred to as a “vehicle-body upper side,” a direction of an arrow D is referred to as a “vehicle-body lower side,” a direction of an arrow L is referred to as a “vehicle-body left side,” and a direction of an arrow R is referred to as a “vehicle-body right side.”

[0040] As illustrated in FIG. 1, a tractor includes a traveling vehicle body 4 including a vehicle body frame 1, a pair of right and left front wheels 2 provided in a steerable and drivable manner in a front portion of the vehicle body frame 1, and a pair of right and left rear wheels 3 provided in a drivable manner in a rear portion of the vehicle body frame 1. The traveling vehicle body 4 includes a front portion in which a motor portion 6 including an engine 5 is provided. The traveling vehicle body 4 includes a rear portion in which a driving portion 9 is provided, the driving portion 9 including a driver seat 7 and a steering wheel 8 by which the front wheels 2 are steered. The driving portion 9 includes a cabin 10 covering a cabin space. The rear portion of the traveling vehicle body 4 includes a link mechanism (not illustrated) via which a work device such as a rotary cultivating device (not illustrated) is connected in a vertically operable manner, and a power take-off shaft 12 configured to extract power from the engine 5 and transmit the power to the work device thus connected. The vehicle body frame 1 includes the engine 5, a transmission case 13 adjacently provided behind the engine 5, and a front frame 14 connected to a lower part of the engine 5. In the present preferred embodiment, the front wheels 2 and the rear wheels 3 are provided, but as the travel devices, a crawler travel device or a device in combination with wheels and a mini crawler can be used.

[0041] A traveling power transmission device 15 configured to transmit power from the engine 5 to the front wheels 2 and the rear wheels 3 includes the transmission case 13 adjacently provided behind the engine 5, as illustrated in FIGS. 1 and 2. The transmission case 13 is side by side with the engine 5 in a direction along a vehicle-body front-rear direction and extends along the vehicle-body front-rear direction. The engine 5 is provided in the front portion of the vehicle body, and the transmission case 13 is connected to a rear portion of the engine 5. As illustrated in FIG. 1, the transmission case 13 is connected to the engine 5 such that a flywheel housing portion 13F is provided in a front portion of the transmission case 13, and a front end of the flywheel housing portion 13F is connected to a rear end of the engine 5. The flywheel housing portion 13F is configured to cover a flywheel 5a (see FIG. 2) provided in the rear portion of the engine 5. The outside diameter of a largest diameter portion of the flywheel housing portion 13F is made larger than the outside diameter of a portion 13R of the transmission case 13, the portion 13R being rearward of the flywheel housing portion 13F.

[0042] As illustrated in FIG. 2, in the transmission case 13, a hybrid transmission 16 is accommodated, the hybrid transmission 16 being configured to vary the power from the engine 5 and output the power to the front wheels 2 and the rear wheels 3.

[0043] As illustrated in FIG. 2, the hybrid transmission 16 includes an input shaft 23 into which power from an output shaft 5b of the engine 5 is input, the input shaft 23 being provided in a front portion of the transmission case 13, an electric transmission portion 16A adjacently positioned behind the engine 5, and a gear transmission portion 16B positioned rearward of the electric transmission portion 16A. The axial center of the input shaft 23 and the axial center of the output shaft 5b are positioned on the same axial center.

[0044] As illustrated in FIG. 2, the electric transmission portion 16A is accommodated in an electric transmission chamber 28 in the front portion of the transmission case 13. The gear transmission portion 16B is accommodated in a gear transmission chamber 29 in a rear portion of the transmission case 13. The electric transmission chamber 28 is defined by a peripheral wall portion of the transmission case 13, a front wall portion 13a provided inside a front end of the transmission case 13, and a partition wall 13b provided inside an intermediate portion of the transmission case 13. The gear transmission chamber 29 is defined by the peripheral wall portion of the transmission case 13, a rear wall portion 13c positioned in a rear end of the transmission case 13, and the partition wall 13b. The electric transmission chamber 28 and the gear transmission chamber 29 are adjacent to each other across the partition wall 13b. The electric transmission chamber 28 and the gear transmission chamber 29 are separated from each other by the partition wall 13b such that the electric transmission chamber 28 and the gear transmission chamber 29 do not communicate with each other. The partition wall 13b includes a peripheral edge on an outer peripheral side, the peripheral edge being connected to the inside of the peripheral wall portion of the transmission case 13. The partition wall 13b includes a sealing member (not illustrated) closing a gap between the partition wall 13b and a rotating shaft 61 in a through-hole provided in the partition wall 13b such that the rotating shaft 61 is passed through the through-hole. Thus, the electric transmission chamber 28 and the gear transmission chamber 29 can be separated from each other by the partition wall 13b.

[0045] As illustrated in FIG. 2, the electric transmission portion 16A is provided between the engine 5 and the gear transmission portion 16B. The electric transmission portion 16A is adjacently positioned behind the engine 5. The electric transmission portion 16A can be accommodated in a portion of the transmission case 13 in which portion the flywheel housing portion 13F having a large outside diameter is positioned.

[0046] As illustrated in FIG. 2, the electric transmission portion 16A includes a motor generator portion 24. The motor generator portion 24 includes two motor generators 17, 18. The two motor generators 17, 18 are connected to an inverter device 21, and the inverter device 21 is connected to a battery 22.

[0047] As illustrated in FIG. 2, the two motor generators 17, 18 are positioned in the direction along the vehicle-body front-rear direction. The motor generator 17 on the front side out of the two motor generators 17, 18 is referred to as a first motor generator 17, and the motor generator 18 on the rear side out of the two motor generators 17, 18 is referred to as a second motor generator 18. A first rotation axial center of the first motor generator 17, a second rotation axial center of the second motor generator 18, and the axial center of the input shaft 23 of the transmission case 13 are positioned on the same axial center.

[0048] As illustrated in FIG. 2, the first motor generator 17 includes a rotor 17a connected to the input shaft 23. The rotor 17a is connected to the input shaft 23 such that a connecting portion provided in a central portion of the rotor 17a is connected to the input shaft 23.

[0049] As illustrated in FIG. 2, the gear transmission portion 16B is provided on a side opposite to a side where the engine 5 is positioned, across the electric transmission portion 16A. The gear transmission portion 16B is adjacently positioned behind the electric transmission portion 16A.

[0050] As illustrated in FIG. 2, the gear transmission portion 16B includes a gear driving mechanism 30 (gear driver) without a motor generator. The gear driving mechanism 30 includes a planetary device 60 positioned in a front portion of the gear transmission portion 16B, a forward-reverse switching device 25 positioned rearward of the planetary device 60, a sub-transmission 26 positioned rearward of the forward-reverse switching device 25, a rear-wheel differential mechanism 19 positioned rearward of the sub-transmission 26, a front-wheel transmission 20 positioned forward of the rear-wheel differential mechanism 19, and a gear linkage mechanism 27 configured to transmit an output from the sub-transmission 26 to the front-wheel transmission 20.

[0051] As illustrated in FIG. 2, the planetary device 60 includes a sun gear 60a, a planetary gear 60b, an internal gear 60c meshing with the planetary gear 60b, and a carrier 60d supporting the planetary gear 60b. The sun gear 60a is connected to a rotor 18a of the second motor generator 18 via the rotating shaft 61. The rotating shaft 61 is outwardly engaged to the input shaft 23 in a rotatable manner. The carrier 60d is connected to the input shaft 23. The internal gear 60c is connected to an input shaft 25a of the forward-reverse switching device 25.

[0052] In the planetary device 60, the carrier 60d is driven by power from the input shaft 23, and the sun gear 60a is driven by the second motor generator 18 via the rotating shaft 61, so that the power from the engine 5 is combined with driving force of the second motor generator 18. Resultant combined power is transmitted from the internal gear 60c to the input shaft 25a of the forward-reverse switching device 25.

[0053] As illustrated in FIG. 2, the forward-reverse switching device 25 includes the input shaft 25a positioned rearward of the planetary device 60, and an output shaft 25b positioned in parallel with the input shaft 25a. The axial center of the input shaft 25a is positioned on the axial center of the input shaft 23. The input shaft 25a is provided with a forward clutch 25c and a reverse clutch 25d. A forward gear mechanism 25e is provided over the forward clutch 25c and the output shaft 25b. A reverse gear mechanism 25f is provided over the reverse clutch 25d and the output shaft 25b.

[0054] In the forward-reverse switching device 25, the output from the planetary device 60 is input into the input shaft 25a. When the forward clutch 25c is engaged, the power from the input shaft 25a is switched to forward power by the forward gear mechanism 25e and the forward clutch 25c, transmitted to the output shaft 25b, and output from the output shaft 25b. When the reverse clutch 25d is engaged, the power of the input shaft 25a is switched to rearward power by the reverse gear mechanism 25f and the reverse clutch 25d, transmitted to the output shaft 25b, and output from the output shaft 25b.

[0055] As illustrated in FIG. 2, the sub-transmission 26 includes an input shaft 26a connected to the output shaft 25b of the forward-reverse switching device 25, and an output shaft 26b provided rearward of the input shaft 26a. The input shaft 26a and the output shaft 26b are positioned on the same axial center. A high-speed clutch 26c is provided between a rear portion of the input shaft 26a and a front portion of the output shaft 26b. A low-speed gear mechanism 26f and a low-speed clutch 26d are provided over the input shaft 26a and a rear portion of the output shaft 26b.

[0056] In the sub-transmission 26, the output from the forward-reverse switching device 25 is input into the input shaft 26a. When the high-speed clutch 26c is engaged, the power from the input shaft 26a is transmitted to the output shaft 26b via the high-speed clutch 26c without being changed in speed, and power on a high-speed side is output from the output shaft 26b. When the low-speed clutch 26d is engaged, the power from the input shaft 26a is changed in speed to power on a low-speed side by the low-speed gear mechanism 26f and the low-speed clutch 26d, and the power on the low-speed side is transmitted to the output shaft 26b and then output from the output shaft 26b. The power on the low-speed side has a speed lower than that of the power on the high-speed side to be output when the high-speed clutch 26c is engaged.

[0057] As illustrated in FIG. 2, the rear-wheel differential mechanism 19 includes an input shaft 19a into which the output from the sub-transmission 26 is input. The input shaft 19a is connected to a rear portion of the output shaft 26b of the sub-transmission 26. The gear linkage mechanism 27 is provided over the output shaft 26b of the sub-transmission 26 and an input shaft 20a of the front-wheel transmission 20 and is configured to transmit the power from the output shaft 26b of the sub-transmission 26 to the input shaft 20a of the front-wheel transmission 20.

[0058] As illustrated in FIG. 2, the front-wheel transmission 20 includes the input shaft 20a connected to the gear linkage mechanism 27 and an output shaft 20e positioned in parallel with the input shaft 20a. The input shaft 20a is provided with a constant speed clutch 20b and a speed increasing clutch 20c. A constant speed gear mechanism 20d is provided over the constant speed clutch 20b and the output shaft 20e. A speed increasing gear mechanism 20f is provided over the speed increasing clutch 20c and the output shaft 20e.

[0059] In the front-wheel transmission 20, the output from the sub-transmission 26 is transmitted to the input shaft 20a via the gear linkage mechanism 27. When the constant speed clutch 20b is engaged, the power from the input shaft 20a is changed in speed to constant speed power by the constant speed clutch 20b and the constant speed gear mechanism 20d, and the constant speed power is transmitted to the output shaft 20e and then output from the output shaft 20e. The constant speed power is power by which the front wheels 2 and the rear wheels 3 are driven at the same speed. When the speed increasing clutch 20c is engaged, the power from the input shaft 20a is changed in speed to speed-increasing power by the speed increasing clutch 20c and the speed increasing gear mechanism 20f, and the speed-increasing power is transmitted to the output shaft 20e and then output from the output shaft 20e. The speed-increasing power is power by which the front wheels 2 are driven at a speed higher than that of the rear wheels 3. The power from the output shaft 20e of the front-wheel transmission 20 is transmitted to a front-wheel differential mechanism 39 via a rotating shaft 38.

[0060] In the traveling power transmission device 15, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the engine 5 and the driving force from the second motor generator 18 are transmitted to the front wheels 2 and the rear wheels 3.

[0061] That is, the power from the input shaft 23 is transmitted to the carrier 60d of the planetary device 60 to drive the planetary gear 60b, the driving force from the second motor generator 18 is transmitted to the sun gear 60a of the planetary device 60 to drive the sun gear 60a, so that the power (engine power) from the engine 5 is combined with the driving force (motor power) from the second motor generator 18 by the planetary device 60, and combined power is output from the internal gear 60c. The combined power from the planetary device 60 is transmitted to the input shaft 25a of the forward-reverse switching device 25 and is output by being switched between forward power and rearward power in the forward-reverse switching device 25. The forward power or the rearward power from the forward-reverse switching device 25 is transmitted to the input shaft 26a of the sub-transmission 26 and is output by being changed in speed between power on the high-speed side and power on the low-speed side in the sub-transmission 26. The power from the sub-transmission 26 is input into the rear-wheel differential mechanism 19 and is output from the rear-wheel differential mechanism 19 toward the right and left rear wheels 3. The power from the sub-transmission 26 is transmitted to the input shaft 20a of the front-wheel transmission 20 via the gear linkage mechanism 27 and is output by being changed in speed to constant speed power or speed-increasing power in the front-wheel transmission 20. The constant speed power or the speed-increasing power from the front-wheel transmission 20 is output toward the front-wheel differential mechanism 39 (the front wheels 2).

[0062] The second motor generator 18 mainly works as an electric machine to drive the front wheels 2 and the rear wheels 3, but the second motor generator 18 works as a generator at the time of deceleration.

[0063] In the traveling power transmission device 15, when the front wheels 2 and the rear wheels 3 are to be driven, the first motor generator 17 is driven by the power transmitted from the engine 5 to the input shaft 23 and generates electric power. The electric power generated by the first motor generator 17 is supplied as charge power to the battery 22 via the inverter device 21 or supplied to the second motor generator 18 as driving power via the inverter device 21.

[0064] As illustrated in FIG. 2, a clutch 45 is provided over the output shaft 5b and the input shaft 23. The clutch 45 is switchable between an engaged state (an ON state) and a disengaged state (an OFF state) by a hydraulic electromagnetic valve or the like. When the clutch 45 is switched to the engaged state, the power from the engine 5 is transmitted to the electric transmission portion 16A and the gear transmission portion 16B, so that the hybrid transmission 16 is switched to a hybrid mode in which the front wheels 2 and the rear wheels 3 are driven by the power from the engine 5 and the driving force from the second motor generator 18, and electric power is generate by the first motor generator 17. When the clutch 45 is switched to the disengaged state, power transmission from the engine 5 to the electric transmission portion 16A and the gear transmission portion 16B is cut off, so that the hybrid transmission 16 is switched to an electrically-driven mode in which the front wheels 2 and the rear wheels 3 are driven only by the driving force from the second motor generator 18. As the clutch 45, a dry clutch can be used.

[0065] As illustrated in FIG. 2, it is possible to provide a planetary reduction gear in a space A between the second motor generator 18 and the planetary device 60, the planetary reduction gear being configured to transmit the driving force of the second motor generator 18 to the planetary device 60 by reducing the speed of the driving force.

[0066] A lubricant to lubricate and cool the first motor generator 17 and the second motor generator 18 is accumulated in the electric transmission chamber 28. A lubricant to lubricate the gear driving mechanism 30 is accumulated in the gear transmission chamber 29.

[0067] In the electric transmission chamber 28 and the gear transmission chamber 29, lubricants having the same oil quality can be accumulated. As the lubricants having the same oil quality to be accumulated in the electric transmission chamber 28 and the gear transmission chamber 29, a lubricant excellent in lubrication performance can be used, for example. The electric transmission chamber 28 and the gear transmission chamber 29 are separated from each other, and therefore, it is possible to accumulate, in the electric transmission chamber 28, a lubricant different in quality from the lubricant accumulated in the gear transmission chamber 29. In a case where lubricants different in quality are accumulated in the electric transmission chamber 28 and the gear transmission chamber 29, it is possible to use a lubricant with better cooling performance than lubrication performance as the lubricant accumulated in the electric transmission chamber 28 so that the first motor generator 17 and the second motor generator 18 are cooled efficiently, and it is also possible to use a lubricant with better lubrication performance than cooling performance as the lubricant accumulated in the gear transmission chamber 29 so that the gear driving mechanism 30 is lubricated efficiently, for example.

[0068] The electric transmission chamber 28 and the gear transmission chamber 29 are separated from each other, and therefore, it is possible to set the level of the lubricant in the electric transmission chamber 28 to be different from the level of the lubricant in the gear transmission chamber 29. That is, in a case where the lubricant with better cooling performance than lubrication performance is accumulated in the electric transmission chamber 28, and the lubricant with better lubrication performance than cooling performance is accumulated in the gear transmission chamber 29, the level of the lubricant in the electric transmission chamber 28 can be set to be higher than the level of the lubricant in the gear transmission chamber 29.

[0069] In either of the case where lubricants having the same quality are accumulated in the electric transmission chamber 28 and in the gear transmission chamber 29 and the case where lubricants different in quality are accumulated in the electric transmission chamber 28 and in the gear transmission chamber 29, the level of the lubricant in the electric transmission chamber 28 can be set to be lower than the level of the lubricant in the gear transmission chamber 29.

[0070] That is, in the gear transmission chamber 29, the lubricant is accumulated to the level set such that the lubricant easily reaches the gears positioned at different positions in the up-down direction, so that the gear driving mechanism 30 is lubricated efficiently. In the electric transmission chamber 28, the lubricant is accumulated only to the level set to be lower than the level in the gear transmission chamber 29 so that the first motor generator 17 and the second motor generator 18 do not enter the lubricant so deeply, thus restraining a driving load to be applied to the first motor generator 17 and the second motor generator 18.

[0071] In a case where the vehicle body is inclined in the front-rear direction, the transmission case 13 is inclined in the front-rear direction. As illustrated in FIG. 3, in a case where the transmission case 13 has an inclined posture (a forward-descending inclined posture) in which the electric transmission chamber 28 side is lowered, a lubricant a that is accumulated in the gear transmission chamber 29 flows toward the electric transmission chamber 28, but the lubricant a thus flowing is received by the partition wall 13b, so that the lubricant a does not flow into the electric transmission chamber 28. Thus, regardless of the inclination of the transmission case 13, the amount of the lubricant in the gear transmission chamber 29 does not decrease, so that the gear driving mechanism 30 can be kept lubricated. Although not illustrated herein, in a case where the transmission case 13 has an inclined posture (a rearward-descending inclined posture) in which the gear transmission chamber 29 side is lowered, a lubricant b accumulated in the electric transmission chamber 28 flows toward the gear transmission chamber 29, but the lubricant b thus flowing is received by the partition wall 13b, so that the lubricant b does not flow into the gear transmission chamber 29. Thus, regardless of the inclination of the transmission case 13, the amount of the lubricant in the electric transmission chamber 28 does not decrease, so that the motor generator portion 24 can be kept lubricated and cooled.

[0072] The traveling power transmission device 15 includes a first oil supply mechanism 80 (see FIG. 4) (first oil supplier) and a second oil supply mechanism 90 (see FIG. 5) (second oil supplier) different from the first oil supply mechanism 80. The traveling power transmission device 15 is configured such that the lubricant is supplied to the motor generator portion 24 by the first oil supply mechanism 80, and the lubricant is supplied to the gear driving mechanism 30 by the second oil supply mechanism 90.

[0073] As illustrated in FIG. 4, the first oil supply mechanism 80 includes a first hydraulic pump 81. The first hydraulic pump 81 includes a suction portion connected to an oil extraction portion (not illustrated) formed in a bottom portion of the transmission case 13 via a first suction oil passage 82. The oil extraction portion communicates with the electric transmission chamber 28. The first hydraulic pump 81 includes a discharge portion connected to the electric transmission chamber 28 via a first oil supply passage 83. The first oil supply passage 83 is connected to an oil jet nozzle (not illustrated) provided in the electric transmission chamber 28.

[0074] In the first oil supply mechanism 80, the first hydraulic pump 81 is driven by the power from the engine 5, so that the lubricant accumulated in the electric transmission chamber 28 is sucked by the first hydraulic pump 81 through the first suction oil passage 82 and supplied from the first hydraulic pump 81 to the electric transmission chamber 28 through the first oil supply passage 83. In the electric transmission chamber 28, the lubricant is emitted from the oil jet nozzle toward the motor generator portion 24, so that the lubricant is supplied to the first motor generator 17 and the second motor generator 18.

[0075] In the present preferred embodiment, the first hydraulic pump 81 preferably is a trochoid pump provided in the input shaft 23 as illustrated in FIG. 2. The first hydraulic pump 81 is not limited to the trochoid pump, and various hydraulic pumps of different types such as a gear pump are also usable. In the present preferred embodiment, the first suction oil passage 82 includes a filter 84. In the first oil supply passage 83, an oil cooler 85 and a cooling portion in the inverter device 21 are provided. The lubricant from the first hydraulic pump 81 is cooled by the oil cooler 85 and supplied to the cooling portion of the inverter device 21 so that the inverter device 21 is cooled, and after the inverter device 21 is cooled, the lubricant is supplied to the motor generator portion 24. Note that, after the lubricant is cooled by the oil cooler 85, the lubricant may be supplied to the first motor generator 17 and the second motor generator 18 without being used to cool of the inverter device 21.

[0076] As illustrated in FIG. 5, the second oil supply mechanism 90 includes a second hydraulic pump 91. The second hydraulic pump 91 includes a suction portion connected to an oil extraction portion (not illustrated) in the bottom portion of the transmission case 13 via a second suction oil passage 92. The oil extraction portion communicates with the gear transmission chamber 29. The second hydraulic pump 91 includes a discharge portion connected to the gear transmission chamber 29 via a second oil supply passage 93. The second oil supply passage 93 is connected to an oil jet nozzle (not illustrated) provided in the gear transmission chamber 29.

[0077] In the second oil supply mechanism 90, the second hydraulic pump 91 is driven by the power from the engine 5, so that the lubricant accumulated in the gear transmission chamber 29 is sucked by the second hydraulic pump 91 through the second suction oil passage 92 and is supplied from the second hydraulic pump 91 to the gear transmission chamber 29 through the second oil supply passage 93. The lubricant is emitted from the oil jet nozzle toward the gear driving mechanism 30 in the gear transmission chamber 29 and is supplied to the gears.

[0078] In the present preferred embodiment, the second suction oil passage 92 includes a filter 94. The second oil supply passage 93 includes an oil cooler 95. The lubricant from the second hydraulic pump 91 is cooled by the oil cooler 95 and then supplied to the gear driving mechanism 30.

[0079] As the first hydraulic pump 81 and the second hydraulic pump 91, a variable capacity hydraulic pump is usable as illustrated in FIG. 6. As a power source to drive the first hydraulic pump 81 and the second hydraulic pump 91, an electric motor 96 is usable as illustrated in FIG. 6. The electric motor 96 can be configured to be driven by electric power generated by the first motor generator 17.

[0080] As illustrated in FIG. 1, the power take-off shaft 12 is supported by the rear portion of the transmission case 13. As illustrated in FIG. 2, in the transmission case 13, a work power transmission device 40 configured to transmit the power from the engine 5 to the power take-off shaft 12 is accommodated.

[0081] As illustrated in FIG. 2, the work power transmission device 40 is provided behind the input shaft 23 in a state where the work power transmission device 40 extends along the vehicle-body front-rear direction. The work power transmission device 40 includes a rotating shaft 41 including a front portion connected to the input shaft 23, a work clutch 42 connected to a rear portion of the rotating shaft 41, and a power take-off shaft transmission 43 configured to vary the output from the work clutch 42 and transmit the output to the power take-off shaft 12. The axial center of the rotating shaft 41 and the axial center of the input shaft 23 are positioned on the same axial center. The input shaft 23 and the rotating shaft 41 are connected in an interlocking manner directly or via a joint.

[0082] In the work power transmission device 40, the power from the input shaft 23 is transmitted to the rotating shaft 41 and is transmitted from the rotating shaft 41 to the power take-off shaft 12 via the work clutch 42 and the power take-off shaft transmission 43. The work clutch 42 switches between an engaged state where the power from the engine 5 is transmitted to the power take-off shaft 12 and a disengaged state where power transmission from the engine 5 to the power take-off shaft 12 is cut off.

Different Preferred Embodiments

[0083] FIG. 7 is a schematic view illustrating the traveling power transmission device 15 according to a first different preferred embodiment. FIG. 8 is a front view illustrating the arrangement of the motor generators in the traveling power transmission device 15 according to the first different preferred embodiment. In the traveling power transmission device 15 according to the first different preferred embodiment, the motor generator portion 24 in the electric transmission portion 16A includes two motor generators 17, 18, as illustrated in FIG. 7. In the traveling power transmission device 15 according to the first different preferred embodiment, as illustrated in FIG. 7, the gear driving mechanism 30 in the gear transmission portion 16B includes a gear driving mechanism 98, a low-speed planetary transmission portion 100, a low-speed clutch 100C, a high-speed planetary transmission portion 110, a high-speed clutch 110C, the forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27. The forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 have the same configurations as the configurations of the forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 illustrated in FIG. 2.

[0084] As illustrated in FIG. 8, the two motor generators 17, 18 are positioned in a direction along a vehicle-body width direction. As illustrated in FIGS. 7, 8, the two motor generators 17, 18 have respective rotation axial centers along the vehicle-body front-rear direction. The first motor generator 17 out of the two motor generators 17, 18 includes a first rotation axial center 17c, the second motor generator 18 out of the two motor generators 17, 18 has a second rotation axial center 18c, and the first rotation axial center 17c and the second rotation axial center 18c are positioned in parallel to each other. As the first motor generator 17 and the second motor generator 18, motor generators having a long length in the direction along the vehicle-body front-rear direction can be used, in comparison with a case where the two motor generators 17, 18 are positioned in the direction along the vehicle-body front-rear direction.

[0085] As illustrated in FIG. 8, the input shaft 23 of the transmission case 13 extends in the vehicle-body front-rear direction, between the first motor generator 17 and the second motor generator 18. The input shaft 23 extends in the front-rear direction above the first rotation axial center 17c of the first motor generator 17 and the second rotation axial center 18c of the second motor generator 18. The input shaft 23 includes an upper end 23t positioned above an upper end 17t of the first motor generator 17 and above an upper end 18t of the second motor generator 18.

[0086] As illustrated in FIG. 7, the gear driving mechanism 30 includes a driving mechanism input shaft 99 behind the input shaft 23 of the transmission case 13. The axial center of the driving mechanism input shaft 99 and the axial center of the input shaft 23 are positioned on the same axial center. The driving mechanism input shaft 99 includes a front portion connected to a rear portion of the input shaft 23, so that the power from the input shaft 23 is transmitted to the driving mechanism input shaft 99. The gear driving mechanism 98 is provided in the front portion of the gear transmission portion 16B. The gear driving mechanism 98 is provided over the driving mechanism input shaft 99 and a rotor support shaft 17b of the first motor generator 17 and is configured to transmit the power from the input shaft 23 to the first motor generator 17.

[0087] As illustrated in FIG. 7, the low-speed planetary transmission portion 100 includes a sun gear 101, a planetary gear 102, an internal gear 103, and a carrier 104. The low-speed planetary transmission portion 100 is provided behind the second motor generator 18 in a state where the rotation axial center of the sun gear 101 and a rotor support shaft 18b (the second rotation axial center 18c) of the second motor generator 18 are positioned on the same axial center. The internal gear 103 is connected to the driving mechanism input shaft 99 via a gear linkage mechanism 105. The sun gear 101 includes a first input shaft 136, and the first input shaft 136 is connected to the rotor support shaft 18b of the second motor generator 18.

[0088] In the low-speed planetary transmission portion 100, the power from the input shaft 23 is transmitted to the internal gear 103 to drive the internal gear 103, and the driving force from the second motor generator 18 is transmitted to the sun gear 101 to drive the sun gear 101, so that the power from the engine 5 and the driving force from the second motor generator 18 are combined to generate combined power on the low-speed side. The combined power on the low-speed side is output from the carrier 104.

[0089] The low-speed clutch 100C is provided between an output portion of the low-speed planetary transmission portion 100 and the input shaft 25a of the forward-reverse switching device 25 and is configured such that, when the low-speed clutch 100C is switched to an engaged state (an ON state), the low-speed clutch 100C transmits the combined power on the low-speed side, output from the low-speed planetary transmission portion 100, to the forward-reverse switching device 25, and when the low-speed clutch 100C is switched to a disengaged state (an OFF state), the low-speed clutch 100C cuts off power transmission from the low-speed planetary transmission portion 100 to the forward-reverse switching device 25.

[0090] As illustrated in FIG. 7, the high-speed planetary transmission portion 110 is provided behind the first motor generator 17. The high-speed planetary transmission portion 110 includes a sun gear 111, a planetary gear 112, an internal gear 113, and a carrier 114. The carrier 114 is connected to the driving mechanism input shaft 99 via a gear linkage mechanism 115. The sun gear 111 includes a second input shaft 137, and the second input shaft 137 is connected to the rotor support shaft 18b of the second motor generator 18 via a gear linkage mechanism 116 and the first input shaft 136.

[0091] In the high-speed planetary transmission portion 110, the power from the input shaft 23 is transmitted to the carrier 114 to drive the planetary gear 112, and the driving force from the second motor generator 18 is transmitted to the sun gear 111 to drive the sun gear 111, so that the engine power from the input shaft 23 and the driving force from the second motor generator 18 are combined to generate combined power on the high-speed side. The combined power on the high-speed side is output from the internal gear 113. The combined power on the high-speed side is combined power at a speed higher than that of the combined power on the low-speed side that is generated by combining in the low-speed planetary transmission portion 100.

[0092] The high-speed clutch 110C is provided between an output portion of the high-speed planetary transmission portion 110 and the input shaft 25a of the forward-reverse switching device 25 and is configured such that, when the high-speed clutch 110C is switched to an engaged state (an ON state), the high-speed clutch 110C transmits the combined power on the high-speed side, output from the high-speed planetary transmission portion 110, to the forward-reverse switching device 25, and when the high-speed clutch 110C is switched to a disengaged state (an OFF state), the high-speed clutch 110C cuts off power transmission from the high-speed planetary transmission portion 110 to the forward-reverse switching device 25.

[0093] The present preferred embodiment includes an arrangement configuration in which the rotation axial center of the sun gear 101 as the rotation axial center of the low-speed planetary transmission portion 100 and the second rotation axial center 18c of the second motor generator 18 are positioned on the same axial center.

[0094] Instead of this configuration, an arrangement configuration in which the rotation axial center of the low-speed planetary transmission portion 100 and the second rotation axial center 18c of the second motor generator 18 are positioned on different axial centers is usable.

[0095] In the traveling power transmission device 15 according to the first different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the engine 5 and the driving force from the second motor generator 18 are transmitted to the front wheels 2 and the rear wheels 3.

[0096] That is, the power (engine power) transmitted from the engine 5 to the input shaft 23 is combined with the driving force (motor power) from the second motor generator 18 into combined power on the low-speed side by the low-speed planetary transmission portion 100, and the power (engine power) transmitted from the engine 5 to the input shaft 23 is combined with the driving force (motor power) from the second motor generator 18 into combined power on the high-speed side by the high-speed planetary transmission portion 110. When the low-speed clutch 100C is switched to the engaged state and the high-speed clutch 110C is switched to the disengaged state, the combined power on the low-speed side from the low-speed planetary transmission portion 100 is transmitted to the input shaft 25a of the forward-reverse switching device 25 and then transmitted from the output shaft 25b of the forward-reverse switching device 25 to the sub-transmission 26. Then, the combined power is transmitted from the sub-transmission 26 to the rear-wheel differential mechanism 19 and the front-wheel transmission 20. When the high-speed clutch 110C is switched to the engaged state and the low-speed clutch 100C is switched to the disengaged state, the combined power on the high-speed side from the high-speed planetary transmission portion 110 is transmitted to the input shaft 25a of the forward-reverse switching device 25 and then transmitted from the output shaft 25b of the forward-reverse switching device 25 to the sub-transmission 26. Then, the combined power is transmitted from the sub-transmission 26 to the rear-wheel differential mechanism 19 and the front-wheel transmission 20.

[0097] In the traveling power transmission device 15 according to the first different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power transmitted from the engine 5 to the input shaft 23 is input into the first motor generator 17 via the driving mechanism input shaft 99 and the gear driving mechanism 98, so that the first motor generator 17 is driven to generate electric power.

[0098] FIG. 9 is a schematic view illustrating the traveling power transmission device 15 according to a second different preferred embodiment. As illustrated in FIG. 9, in the traveling power transmission device 15 according to the second different preferred embodiment, the motor generator portion 24 in the electric transmission portion 16A includes two motor generators 17, 18. In the traveling power transmission device 15 according to the second different preferred embodiment, the gear driving mechanism 30 of the gear transmission portion 16B includes the low-speed planetary transmission portion 100, the low-speed clutch 100C, the high-speed planetary transmission portion 110, the high-speed clutch 110C, the forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27.

[0099] The low-speed planetary transmission portion 100, the low-speed clutch 100C, the high-speed planetary transmission portion 110, and the high-speed clutch 110C have the same configurations as the configurations of the low-speed planetary transmission portion 100, the low-speed clutch 100C, the high-speed planetary transmission portion 110, and the high-speed clutch 110C included in the traveling power transmission device 15 of the first different preferred embodiment. The forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 have the same configurations as the configurations of the forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 illustrated in FIG. 2.

[0100] The two motor generators 17, 18 are positioned in the direction along the vehicle-body front-rear direction. The first motor generator 17 on the front side out of the two motor generators 17, 18 is closer to a side where the engine 5 is positioned than the second motor generator 18 on the rear side out of the two motor generators 17, 18, and the second motor generator 18 is closer to a side where the gear transmission portion 16B is positioned than the first motor generator 17. The rotation axial center of the first motor generator 17, the rotation axial center of the second motor generator 18, and the axial center of the input shaft 23 of the transmission case 13 are positioned on the same axial center.

[0101] An input transmission mechanism 120 is closer to the side where the engine 5 is positioned than the first motor generator 17. The input transmission mechanism 120 connects the first motor generator 17 to the input shaft 23 of the transmission case 13 and is configured to input the power from the input shaft 23 into the first motor generator 17.

[0102] More specifically, as illustrated in FIG. 9, the input transmission mechanism 120 includes a sun gear 121, a planetary gear 122, an internal gear 123, and a carrier 124. The sun gear 121 is connected to the rotor 17a of the first motor generator 17 in a state where the sun gear 121 rotates around its rotation axial center positioned on the axial center of the input shaft 23. The sun gear 121 is connected to the rotor 17a via a rotating shaft 125. The carrier 124 is connected to the input shaft 23. The internal gear 123 is fixed to the transmission case 13.

[0103] The input transmission mechanism 120 includes a planetary gear mechanism, and the input transmission mechanism 120 increases the speed of the power transmitted from the engine 5 to the input shaft 23 and inputs the power into the rotor 17a of the first motor generator 17. In the present preferred embodiment, the input transmission mechanism 120 includes a planetary gear mechanism, but as the input transmission mechanism 120, a gear linkage mechanism other than the planetary gear mechanism is usable. Further, as the input transmission mechanism 120, a transmission mechanism configured to transmit the power from the input shaft 23 to the first motor generator 17 without increasing the speed of the power.

[0104] As illustrated in FIG. 9, the internal gear 103 of the low-speed planetary transmission portion 100 is connected to the input shaft 23 via a first linkage mechanism 126. The carrier 114 of the high-speed planetary transmission portion 110 is connected to the input shaft 23 via a second linkage mechanism 127.

[0105] An output transmission mechanism 130 is closer to the side where the gear transmission portion 16B is positioned than the second motor generator 18. The output transmission mechanism 130 connects the second motor generator 18 to an input portion 135 positioned in a front portion of the gear transmission portion 16B such that the output transmission mechanism 130 transmits the driving force from the second motor generator 18 to the input portion 135.

[0106] More specifically, as illustrated in FIG. 9, the input portion 135 of the gear transmission portion 16B includes a first input shaft 136 connected to the sun gear 101 of the low-speed planetary transmission portion 100, and a second input shaft 137 connected to the sun gear 111 of the high-speed planetary transmission portion 110. The output transmission mechanism 130 includes a rotating shaft 131 connected to the rotor 18a of the second motor generator 18, a first gear linkage mechanism 132 connecting the rotating shaft 131 to the first input shaft 136, and a second gear linkage mechanism 133 connecting the rotating shaft 131 to the second input shaft 137.

[0107] In the traveling power transmission device 15 according to the second different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the engine 5 and the driving force from the second motor generator 18 are transmitted to the front wheels 2 and the rear wheels 3.

[0108] That is, the power from the input shaft 23 is transmitted to the internal gear 103 of the low-speed planetary transmission portion 100 via the first linkage mechanism 126, and the driving force from the second motor generator 18 is transmitted to the sun gear 101 of the low-speed planetary transmission portion 100 via the output transmission mechanism 130 and the first input shaft 136, so that the power (engine power) from the engine 5 is combined with the driving force (motor power) from the second motor generator 18 into combined power on the low-speed side by the low-speed planetary transmission portion 100. The combined power on the low-speed side is output to the low-speed clutch 100C. The power from the input shaft 23 is transmitted to the carrier 114 of the high-speed planetary transmission portion 110 via the second linkage mechanism 127, and the driving force from the second motor generator 18 is transmitted to the sun gear 111 of the high-speed planetary transmission portion 110 via the output transmission mechanism 130 and the second input shaft 137, so that the power (engine power) from the engine 5 is combined with the driving force (motor power) from the second motor generator 18 into combined power on the high-speed side by the high-speed planetary transmission portion 110. The combined power on the high-speed side is output to the high-speed clutch 110C. When the low-speed clutch 100C is switched to an engaged state (an ON state) and the high-speed clutch 110C is switched to a disengaged state (an OFF state), the combined power on the low-speed side from the low-speed clutch 100C is transmitted to the sub-transmission 26 via the forward-reverse switching device 25 and then transmitted from the sub-transmission 26 to the rear-wheel differential mechanism 19 and the front-wheel transmission 20.

[0109] When the low-speed clutch 100C is switched to the disengaged state (the OFF state) and the high-speed clutch 110C is switched to the engaged state (the ON state), the combined power on the high-speed side from the high-speed clutch 110C is transmitted to the sub-transmission 26 via the forward-reverse switching device 25 and then transmitted from the sub-transmission 26 to the rear-wheel differential mechanism 19 and the front-wheel transmission 20.

[0110] In the traveling power transmission device 15 according to the second different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power transmitted from the engine 5 to the input shaft 23 is input into the first motor generator 17 via the input transmission mechanism 120, so that the first motor generator 17 is driven to generate electric power.

[0111] FIG. 10 is a schematic view illustrating the traveling power transmission device 15 according to a third different preferred embodiment. As illustrated in FIG. 10, in the traveling power transmission device 15 according to the third different preferred embodiment, the motor generator portion 24 in the electric transmission portion 16A includes two motor generators 17, 18. The electric transmission portion 16A includes a first planetary device 31 and a second planetary device 32. In the traveling power transmission device 15 according to the third different preferred embodiment, the gear driving mechanism 30 in the gear transmission portion 16B includes the forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27.

[0112] The rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 have the same configurations as the configurations of the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 illustrated in FIG. 2.

[0113] The output shaft 25b of the forward-reverse switching device 25 is provided with the forward clutch 25c and the reverse clutch 25d, the forward gear mechanism 25e is provided over the input shaft 25a and the forward clutch 25c, and the reverse gear mechanism 25f is provided over the input shaft 25a and the reverse clutch 25d.

[0114] In the sub-transmission 26, the input shaft 26a and the output shaft 26b are provided in parallel with each other. The output shaft 26b is provided with the high-speed clutch 26c and the low-speed clutch 26d. A high-speed gear mechanism 26e is provided over the input shaft 26a and the high-speed clutch 26c, and a low-speed gear mechanism 26f is provided over the input shaft 26a and the low-speed clutch 26d.

[0115] The two motor generators 17, 18 are positioned in the direction along the vehicle-body front-rear direction. The first motor generator 17 on the rear side out of the two motor generators 17, 18 is provided on a side opposite to the side where the engine 5 is positioned, across the second motor generator 18 on the front side out of the two motor generators 17, 18. The rotation axial center of the first motor generator 17, the rotation axial center of the second motor generator 18, and the axial center of the input shaft 23 of the transmission case 13 are positioned on the same axial center.

[0116] The first planetary device 31 and the second planetary device 32 are positioned along the vehicle-body front-rear direction between the first motor generator 17 and the second motor generator 18. The second planetary device 32 is positioned forward of the first planetary device 31.

[0117] The first planetary device 31 includes a first sun gear 31a, a first planetary gear 31b, a first internal gear 31c, and a first carrier 31d. The second planetary device 32 includes a second sun gear 32a, a second planetary gear 32b, a second internal gear 32c, and a second carrier 32d. The rotation axial center of the first sun gear 31a of the first planetary device 31, the rotation axial center of the second sun gear 32a of the second planetary device 32, the rotation axial center of the first motor generator 17, and the rotation axial center of the second motor generator 18 are positioned on the same axial center.

[0118] In the first planetary device 31, the first carrier 31d is connected to the input shaft 23. In the second planetary device 32, the second internal gear 32c is fixed to the transmission case 13, and the second carrier 32d is connected to the first sun gear 31a via a rotating shaft 33.

[0119] As illustrated in FIG. 10, the first motor generator 17 is connected to the first internal gear 31c of the first planetary device 31. The first motor generator 17 is connected to the first internal gear 31c by connecting the rotor 17a of the first motor generator 17 to the first internal gear 31c via a rotating shaft 34. The second motor generator 18 is connected to the second sun gear 32a of the second planetary device 32. The second motor generator 18 is connected to the second sun gear 32a by connecting the rotor 18a of the second motor generator 18 to the second sun gear 32a via a rotating shaft 35.

[0120] In the traveling power transmission device 15 according to the third different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the engine 5 and the driving force from the second motor generator 18 are transmitted to the front wheels 2 and the rear wheels 3.

[0121] That is, the power from the input shaft 23 is input into the first carrier 31d of the first planetary device 31 so that the first planetary gear 31b is driven to drive the first planetary device 31, and the driving force from the second motor generator 18 is input into the second sun gear 32a of the second planetary device 32 so that the second planetary device 32 is driven. The power (engine power) from the engine 5 is combined with the driving force (motor power) from the second motor generator 18 by the first planetary device 31 and the second planetary device 32, and the combined power is transmitted from an output gear 30a to the input shaft 25a of the forward-reverse switching device 25 via a transmission gear 36 and a transmission shaft 37 and then transmitted from the forward-reverse switching device 25 to the sub-transmission 26. The power from the sub-transmission 26 is transmitted to the rear-wheel differential mechanism 19. The power from the sub-transmission 26 is transmitted to the front-wheel transmission 20 via the gear linkage mechanism 27 and output from the front-wheel transmission 20 toward the front-wheel differential mechanism 39.

[0122] The second motor generator 18 mainly works as an electric machine to drive the front wheels 2 and the rear wheels 3, but the second motor generator 18 works as a generator at the time of deceleration.

[0123] In the traveling power transmission device 15 according to the third different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the first internal gear 31c of the first planetary device 31 is transmitted to the first motor generator 17 via the rotating shaft 34, so that the first motor generator 17 is driven by the power from the first internal gear 31c and generates electric power.

[0124] FIG. 11 is a schematic view illustrating the traveling power transmission device 15 according to a fourth different preferred embodiment. As illustrated in FIG. 11, in the traveling power transmission device 15 according to the fourth different preferred embodiment, the motor generator portion 24 in the electric transmission portion 16A includes two motor generators 17, 18. The electric transmission portion 16A includes one planetary device 50. In the traveling power transmission device 15 according to the fourth different preferred embodiment, the gear driving mechanism 30 in the gear transmission portion 16B includes the forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27.

[0125] The rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 have the same configurations as the configurations of the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 illustrated in FIG. 2. The forward-reverse switching device 25 and the sub-transmission 26 have the same configurations as the forward-reverse switching device 25 and the sub-transmission 26 illustrated in FIG. 10.

[0126] The two motor generators 17, 18 are positioned in the direction along the vehicle-body front-rear direction. The first motor generator 17 on the rear side out of the two motor generators 17, 18 is provided on a side opposite to the side where the engine 5 is positioned, across the second motor generator 18 on the front side out of the two motor generators 17, 18. The rotation axial center of the first motor generator 17, the rotation axial center of the second motor generator 18, and the axial center of the input shaft 23 of the transmission case 13 are positioned on the same axial center.

[0127] The planetary device 50 is provided between the first motor generator 17 and the second motor generator 18. The planetary device 50 includes a sun gear 50a, a planetary gear 50b, an internal gear 50c, and a carrier 50d. The carrier 50d is connected to the input shaft 23. The sun gear 50a is connected to an output gear 52 via a rotating shaft 51. The output gear 52 is connected to the transmission shaft 37. The second motor generator 18 is connected to the transmission shaft 37. The second motor generator 18 is connected to the transmission shaft 37 by connecting the rotor 18a of the second motor generator 18 to the transmission shaft 37 via a rotating shaft 55 and a gear linkage mechanism 54. The internal gear 50c of the planetary device 50 is connected to the first motor generator 17. The internal gear 50c is connected to the first motor generator 17 by connecting the rotor 17a of the first motor generator 17 to the internal gear 50c via the rotating shaft 34.

[0128] In the traveling power transmission device 15 according to the fourth different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the engine 5 and the driving force from the second motor generator 18 are transmitted to the front wheels 2 and the rear wheels 3.

[0129] That is, the power from the input shaft 23 is input into the carrier 50d so that the planetary gear 50b is driven to drive the planetary device 50, and the power from the sun gear 50a is transmitted from the output gear 52 to the transmission shaft 37. The driving force from the second motor generator 18 is transmitted to the transmission shaft 37 via the rotating shaft 55 and the gear linkage mechanism 54, and power obtained by varying the power (engine power) input from the engine 5 into the planetary device 50 is joined to the driving force (motor power) from the second motor generator 18 in the transmission shaft 37. The joined power is transmitted to the input shaft 25a of the forward-reverse switching device 25 and then transmitted from the output shaft 25b of the forward-reverse switching device 25 to the sub-transmission 26. The power from the sub-transmission 26 is transmitted to the rear-wheel differential mechanism 19. The power from the sub-transmission 26 is transmitted to the front-wheel transmission 20 via the gear linkage mechanism 27.

[0130] In the traveling power transmission device 15 according to the fourth different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the internal gear 50c of the planetary device 50 is transmitted to the rotor 17a of the first motor generator 17 via the rotating shaft 34, so that the first motor generator 17 is driven and generates electric power.

[0131] FIG. 12 is a schematic view illustrating the traveling power transmission device 15 according to a fifth different preferred embodiment. As illustrated in FIG. 12, in the traveling power transmission device 15 according to the fifth different preferred embodiment, the motor generator portion 24 in the electric transmission portion 16A includes two motor generators 17, 18. The electric transmission portion 16A includes one planetary device 70. In the traveling power transmission device 15 according to the fifth different preferred embodiment, the gear driving mechanism 30 in the gear transmission portion 16B includes the forward-reverse switching device 25, the sub-transmission 26, the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27.

[0132] The rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 have the same configurations as the configurations of the rear-wheel differential mechanism 19, the front-wheel transmission 20, and the gear linkage mechanism 27 illustrated in FIG. 2. The forward-reverse switching device 25 and the sub-transmission 26 have the same configurations as the forward-reverse switching device 25 and the sub-transmission 26 illustrated in FIG. 10.

[0133] The two motor generators 17, 18 are positioned in the direction along the vehicle-body front-rear direction. The first motor generator 17 on the front side out of the two motor generators 17, 18 is closer to the side where the engine 5 is positioned than the second motor generator 18 on the rear side out of the two motor generators 17, 18. The rotation axial center of the first motor generator 17, the rotation axial center of the second motor generator 18, and the axial center of the input shaft 23 of the transmission case 13 are positioned on the same axial center.

[0134] The planetary device 70 includes a sun gear 70a, a planetary gear 70b, an internal gear 70c, and a carrier 70d. The carrier 70d is connected to the input shaft 23. The internal gear 70c is connected to an output gear 72 via a rotating shaft 71. The sun gear 70a is connected to the rotor 18a of the second motor generator 18 via a rotating shaft 73. The rotor 17a of the first motor generator 17 is supported by the input shaft 23.

[0135] In the traveling power transmission device 15 according to the fifth different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the power from the engine 5 and the driving force of the second motor generator 18 are transmitted to the front wheels 2 and the rear wheels 3.

[0136] That is, the power from the input shaft 23 is input into the carrier 70d to drive the planetary gear 70b, and the driving force from the second motor generator 18 is input into the sun gear 70a to drive the sun gear 70a, so that the power (engine power) from the engine 5 is combined with the driving force (motor power) from the second motor generator 18 by the planetary device 70. The combined power is transmitted from the internal gear 70c to the output gear 72, transmitted from the output gear 72 to the forward-reverse switching device 25 via the transmission shaft 37, and then transmitted from the forward-reverse switching device 25 to the sub-transmission 26. The power from the sub-transmission 26 is transmitted to the rear-wheel differential mechanism 19 and the front-wheel transmission 20.

[0137] In the traveling power transmission device 15 according to the fifth different preferred embodiment, when the front wheels 2 and the rear wheels 3 are to be driven, the first motor generator 17 is driven by the power from the input shaft 23 and performs power generation.

[0138] The above preferred embodiments deal with examples in which the electric transmission portion 16A is provided between the engine 5 and the gear transmission portion 16B. However, the present invention is not limited to this. The gear transmission portion 16B may be divided into a front divisional gear transmission portion and a rear divisional gear transmission portion along the vehicle-body front-rear direction, and the electric transmission portion 16A may be provided between the front divisional gear transmission portion and the rear divisional gear transmission portion.

[0139] The above preferred embodiments deal with examples in which the motor generator portion 24 includes two motor generators 17, 18. However, the present invention is not limited to this. The motor generator portion 24 may include only one motor generator or three or more motor generators.

[0140] The above preferred embodiments deal with examples in which the engine 5 is provided in the front portion of the vehicle body, and the transmission case 13 is adjacently provided behind the engine 5. However, the engine 5 may be provided in the rear portion of the vehicle body, and the transmission case 13 may be adjacently provided in front of the engine 5.

[0141] The above preferred embodiments deal with preferred embodiments in which the engine 5 is connected to the transmission case 13. However, the engine 5 and the transmission case 13 may be distanced from each other without being connected to each other.

[0142] The above preferred embodiments deal with examples in which the front wheels 2 and the rear wheels 3 are provided as travel devices. However, the present invention is not limited to this. As the travel devices, a crawler travel device or a device in combination with wheels and a mini crawler may be employed.

[0143] The above preferred embodiments deal with examples in which the power take-off shaft 12 is provided, but the power take-off shaft 12 may not be provided.

[0144] Preferred embodiments of the present invention can be applied to hybrid work vehicles each including an engine and a hybrid transmission. The hybrid transmission includes an electric transmission and a gear transmission such that the electric transmission and the gear transmission are positioned along the vehicle-body front-rear direction. The electric transmission includes a motor generator, and the gear transmission includes a gear driver without a motor generator. The hybrid transmission is configured to output power from the engine toward travel devices by varying the power.

[0145] While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.