POWER TRANSMISSION SYSTEM

Abstract

Two reduction gears have at least two common rotation center axes. A first power source (121) is coupled to the high-speed side of a first reduction gear (111) on a first rotation center axis (101). A second power source (122) is coupled to the high-speed side of a second reduction gear (112) on a second rotation center axis (102). A first input/output shaft (141) is coupled to the low-speed side of the second reduction gear (112) on the first rotation center axis (101). The high-speed side of the first reduction gear (111) is coupled to the low-speed side of the second reduction gear (112) on the first rotation center axis (101) via a first clutch (131). The low-speed side of the first reduction gear (111) is coupled to the high-speed side of the second reduction gear (112) on the second rotation center axis (102) via a second clutch (132).

Claims

1. A power transmission system comprising: at least two power sources including a first power source and a second power source; at least one input/output shaft including a first input/output shaft; two reduction gears including a first reduction gear and a second reduction gear; and at least two clutches including a first clutch and a second clutch, the first reduction gear and the second reduction gear having at least two common rotation center axes including a first rotation center axis and a second rotation center axis, the first power source being coupled to a high-speed side of the first reduction gear on the first rotation center axis, the second power source being coupled to a high-speed side of the second reduction gear on the second rotation center axis, the first input/output shaft being coupled to a low-speed side of the second reduction gear on the first rotation center axis, the high-speed side of the first reduction gear being coupled to the low-speed side of the second reduction gear on the first rotation center axis via the first clutch, and a low-speed side of the first reduction gear being coupled to the high-speed side of the second reduction gear on the second rotation center axis via the second clutch.

2. The power transmission system according to claim 1, wherein at least one of the two reduction gears is configured by a sprocket and a chain.

3. The power transmission system according to claim 1, wherein at least one of the at least two clutches is a one-way clutch.

4. The power transmission system according to claim 1, wherein the at least two power sources include at least one electric motor.

5. The power transmission system according to claim 4, wherein the at least two power sources include at least one internal combustion engine.

6. The power transmission system according to claim 1, further comprising a third power source coupled to the low-speed side of the first reduction gear on the second rotation center axis via a third clutch.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0029] FIG. 1 is an illustrative diagram of a power transmission system 100 according to a first embodiment of the present invention.

[0030] FIGS. 2A-2C are an illustrative diagram of the operation of the power transmission system 100 according to the first embodiment of the present invention.

[0031] FIG. 3 is an illustrative diagram of a power transmission system 200 according to a second embodiment of the present invention.

[0032] FIGS. 4A-4C are an illustrative diagram of the operation of the power transmission system 200 according to the second embodiment of the present invention.

[0033] FIG. 5 is an illustrative diagram of a power transmission system 200B according to a first variation example of the second embodiment of the present invention.

[0034] FIG. 6 is an illustrative diagram of a power transmission system 200C according to a second variation example of the second embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

[0035] A power transmission system according to the present invention will be hereinafter described with reference to the drawings.

[0036] The power transmission system 100 according to the first embodiment of the present invention includes, as illustrated in FIG. 1, a first power source 121, a second power source 122, a first input/output shaft 141, a first reduction gear 111, a second reduction gear 112, a first clutch 131, and a second clutch 132.

[0037] The first reduction gear 111 and the second reduction gear 112 have two common rotation center axes, a first rotation center axis 101 and a second rotation center axis 102.

[0038] The first reduction gear 111 is configured to include a sprocket 151 on the first rotation center axis 101 on the high-speed side, a sprocket 152 on the second rotation center axis 102 on the low-speed side, and a chain passed around the sprocket 151 and the sprocket 152.

[0039] The second reduction gear 112 is configured to include a sprocket 154 on the second rotation center axis 102 on the high-speed side, a sprocket 155 on the first rotation center axis 101 on the low-speed side, and a chain passed around the sprocket 154 and the sprocket 155.

[0040] The first power source 121 is configured as an electric motor driven by an inverter circuit 124 and coupled to the high-speed side of the first reduction gear 111 on the first rotation center axis 101.

[0041] The second power source 122 is configured as an electric motor driven by an inverter circuit 125 and coupled to the high-speed side of the second reduction gear 112 on the second rotation center axis 102.

[0042] The inverter circuits 124 and 125 are controlled by a controller 103. The first input/output shaft 141 is coupled to the low-speed side of the second reduction gear 112 on the first rotation center axis 101.

[0043] The high-speed side of the first reduction gear 111 is coupled to the low-speed side of the second reduction gear 112 on the first rotation center axis 101 via the first clutch 131, and the low-speed side of the first reduction gear 111 is coupled to the high-speed side of the second reduction gear 112 on the second rotation center axis 102 via the second clutch 132.

[0044] The first clutch 131 is configured as a one-way clutch that transmits the torque only from the low-speed side of the second reduction gear 112 to the high-speed side of the first reduction gear 111.

[0045] Therefore, when the rotation speed on the high-speed side of the first reduction gear 111 is higher than that of the low-speed side of the second reduction gear 112, no torque transmission occurs.

[0046] The second clutch 132 is configured as a one-way clutch that transmits the torque only from the low-speed side of the first reduction gear 111 to the high-speed side of the second reduction gear 112.

[0047] Therefore, when the rotation speed on the high-speed side of the second reduction gear 112 is higher than that of the low-speed side of the first reduction gear 111, no torque transmission occurs.

[0048] By adopting one-way clutches that transmit torque only in one way in both forward and reverse directions (referred to as “bidirectional one-way clutch” or “two-way clutch”, etc.), the same power transmission effect will be achieved in both forward and reverse directions.

[0049] The operation of the power transmission system 100 configured as described above is now explained.

[0050] When transmitting a rotation torque to the first input/output shaft 141 by driving the first power source 121, the drive power of the first power source 121 is transmitted in the order of the high-speed side of the first reduction gear 111, the low-speed side of the first reduction gear 111, the second clutch 132, the high-speed side of the second reduction gear 112, the low-speed side of the second reduction gear 112, and the first input/output shaft 141, as illustrated in FIG. 2A.

[0051] At this time, the torque is transmitted to the second power source 122, too, because the high-speed side of the second reduction gear 112 and the second power source 122 are coupled together. However, with the second power source 122 set in an idle state, no drive power is consumed.

[0052] Alternatively, the drive power of the first power source 121 can be reinforced by driving the second power source 122 with a matching rpm.

[0053] When transmitting a rotation torque to the first input/output shaft 141 by driving the second power source 122, the drive power of the second power source 122 is transmitted in the order of the high-speed side of the second reduction gear 112, the low-speed side of the second reduction gear 112, and the first input/output shaft 141, as illustrated in FIG. 2B.

[0054] At this time, the torque is transmitted to the first power source 121, too, because the rotation on the low-speed side of the second reduction gear 112 is transmitted to the high-speed side of the first reduction gear 111 via the first clutch 131. However, with the first power source 121 set in an idle state, no drive power is consumed.

[0055] When transmitting a rotation torque of the first input/output shaft 141 to the first power source 121 or the second power source 122, the rotation of the first input/output shaft 141 is transmitted in the order of the low-speed side of the second reduction gear 112, the first clutch 131, the high-speed side of the first reduction gear 111, and the first power source 121, as well as transmitted in the order of the low-speed side of the second reduction gear 112, the high-speed side of the second reduction gear 112, and the second power source 122, as illustrated in FIG. 2C.

[0056] At this time, braking can be applied to the rotation of the first input/output shaft 141 by generating power by one or both of the first power source 121 and the second power source 122.

[0057] These operations can be performed only by controlling the drive and energy recovery of the first power source 121 and the second power source 122 by the controller 103, and there is no need to operate other systems.

[0058] The power transmission system 200 according to a second embodiment of the present invention is suitable for applications where the drive power of an internal combustion engine is assisted by an electric motor for energy recovery during the braking. As illustrated in FIG. 3, this embodiment has the same structure as that of the power transmission system 100 of the first embodiment except that the second power source 222 is configured as an internal combustion engine and does not include an inverter circuit, and therefore the description thereof will be omitted (reference numerals in the 200s are used with the same lower two digits).

[0059] The operation of the power transmission system 200 is now explained.

[0060] When transmitting a rotation torque to the first input/output shaft 241 by driving only the second power source 222 that is an internal combustion engine, the drive power of the second power source 222 that is an internal combustion engine is transmitted in the order of the high-speed side of the second reduction gear 212, the low-speed side of the second reduction gear 212, and the first input/output shaft 241, as illustrated in FIG. 4A.

[0061] At this time, the torque is transmitted to the first power source 221 that is an electric motor, too, because the rotation on the low-speed side of the second reduction gear 212 is transmitted to the high-speed side of the first reduction gear 211 via the first clutch 231.

[0062] However, with the first power source 221 that is an electric motor set in an idle state, no drive power is consumed. If there is a surplus in the drive power of the second power source 222 that is an internal combustion engine, this may be used to generate power by the first power source 221 that is an electric motor.

[0063] When transmitting a rotation torque to the first input/output shaft 241 by driving the first power source 221 that is an electric motor to assist the drive power of the second power source 222 that is an internal combustion engine, the drive power of the first power source 221 is transmitted in the order of the high-speed side of the first reduction gear 211, the low-speed side of the first reduction gear 211, the second clutch 232, the high-speed side of the second reduction gear 212, the low-speed side of the second reduction gear 212, and the first input/output shaft 241, as illustrated in FIG. 4B.

[0064] At this time, the high-speed side of the second reduction gear 212 is coupled to the second power source 222, and therefore, the drive power of the second power source 222 that is an internal combustion engine can be assisted by the drive power of the first power source 221 that is an electric motor, by controlling and driving the first power source 221 such as to match with the rpm of the second power source 222.

[0065] When applying braking to the rotation of the first input/output shaft 241, the rotation of the first input/output shaft 241 is transmitted in the order of the low-speed side of the second reduction gear 212, the high-speed side of the second reduction gear 212, and the second power source 222, as illustrated in FIG. 4C, so that engine braking by the second power source 222 that is an internal combustion engine is applied.

[0066] Since the rotation is also transmitted in the order of the low-speed side of the second reduction gear 212, the first clutch 231, the high-speed side of the first reduction gear 211, and the first power source 221, the braking can be further assisted by generating power by the first power source 221 that is an electric motor.

[0067] A power transmission system 200B according to a first variation example of the second embodiment of the present invention is configured to include a third clutch 233 between the second power source 222 that is an internal combustion engine and the high-speed side of the second reduction gear 212, to allow rotation transmission only from the second power source 222 that is an internal combustion engine to the high-speed side of the second reduction gear 212, as illustrated in FIG. 5. Other configurations are the same as those of the power transmission system 200 of the second embodiment.

[0068] With the power transmission system 200B according to this first variation example, braking on the rotation of the first input/output shaft 241 is applied only by the power generation by the first power source 221 that is an electric motor so that energy loss caused by engine braking can be reduced.

[0069] These operations can be performed only by controlling the drive and energy recovery of the first power source 221 by the controller 203, and there is no need to operate other systems.

[0070] More detailed control may be performed by configuring the system such that the controller 203 can control the On/Off or slip of the first clutch 231 and the second clutch 232.

[0071] A power transmission system 200C according to a second variation example of the second embodiment of the present invention includes, as illustrated in FIG. 6, a third power source 223 that is an electric motor driven by an inverter circuit 226 and coupled to the low-speed side of the first reduction gear 211 on the second rotation center axis 202. Other configurations are the same as those of the power transmission system 200B according to the first variation example of the second embodiment.

[0072] In the power transmission system 200B according to this first variation example, the first power source 221 that is an electric motor and the third power source 223 that is an electric motor are directly connected to the high-speed side and the low-speed side of the first reduction gear 211 and rotated always simultaneously at different rpms.

[0073] This enables optimal distribution of the drive and energy recovery to the two electric motors by the controller 203, which in turn enables a further improvement in drive efficiency and regeneration efficiency.

[0074] While embodiments of the present invention have been described above in detail, the present invention is not limited to the embodiments described above. Various design changes may be made without departing from the scope of the present invention set forth in the claims.

[0075] For example, as opposed to the configuration of the embodiments above in which the clutches are one-way clutches and switch among various modes without any control from outside, clutches that allow On/Off control or slip control by the controller 103 may be adopted to enable switching among a wider variety of modes and to enable smoother transition between modes.

[0076] While the power sources that are electric motors are driven by inverter circuits in the embodiments above, any types of electric motor may be used.

[0077] The reduction gears may be any drive systems that use belts, toothed wheels, hydraulic pressure, etc., or a combination of these, as opposed to the chain drive system in the embodiments above.

REFERENCE SIGNS LIST

[0078] 100, 200 Power transmission system

[0079] 101, 201 First rotation center axis

[0080] 102, 202 Second rotation center axis

[0081] 103, 203 Controller

[0082] 111, 211 First reduction gear

[0083] 112, 212 Second reduction gear

[0084] 121, 221 First power source

[0085] 122, 222 Second power source

[0086] 223 Third power source

[0087] 124, 224 Inverter circuit (of the first power source)

[0088] 125 Inverter circuit (of the second power source)

[0089] 226 Inverter circuit (of the second power source)

[0090] 131, 231 First clutch

[0091] 132, 232 Second clutch

[0092] 233 Third clutch

[0093] 141, 241 First input/output shaft

[0094] 151, 251 Sprocket (on the high-speed side of the first reduction gear)

[0095] 152, 252 Sprocket (on the low-speed side of the first reduction gear)

[0096] 154, 254 Sprocket (on the high-speed side of the second reduction gear)

[0097] 155, 255 Sprocket (on the low-speed side of the second reduction gear)