Driving device in a self-propelled construction machine and method for setting a speed ratio in such a driving device

Abstract

The present invention relates to a device in a self-propelled construction machine with a first driving unit, which provides for a first speed of rotation (n.sub.1). By means of a planetary gear the first speed of rotation (n.sub.1) is translated into a different speed of rotation (n.sub.3) at which a working device of the construction machine, in particular a milling rotor for processing ground surfaces, can be operated.

Claims

1. A construction machine for processing ground surfaces comprising a milling rotor, wherein the construction machine comprises an internal combustion engine, and wherein a first drive train (A) is formed from said internal combustion engine to a summating transmission driving said milling rotor, said summating transmission being designed as a planetary gear comprising a sun wheel, and wherein said internal combustion engine generates a first speed of rotation (n.sub.1), and said milling rotor operates at a third speed of rotation (n.sub.3), and wherein a second drive train (B) is formed from a hydraulic engine or electric motor to said summating transmission driving said milling rotor via an output shaft of said summating transmission, with said hydraulic engine or electric motor having a power output that is lower than a power output of said internal combustion engine and said second drive train (B) being coupled to said sun wheel of said planetary gear, and that said first and second drive trains (A, B) are interconnected by the summating transmission to said output shaft of said summating transmission, and wherein the third speed of rotation (n.sub.3) is altered by changing the first speed of rotation (n.sub.1) and/or the second speed of rotation (n.sub.2) via the summating transmission.

2. The construction machine according to claim 1, wherein said planetary gear comprises a sun wheel, a planetary carrier incorporating a plurality of planetary wheels and a gear ring, wherein said gear ring is mounted for rotation on a driving shaft and said planetary carrier is rigidly connected to an output shaft and said hydraulic engine or electric motor engages said gear ring.

3. The construction machine according to claim 1, wherein said planetary gear comprises a sun wheel, a planetary carrier incorporating a plurality of planetary wheels, and a gear ring, wherein said planetary carrier is mounted for rotation on a driving shaft and said gear ring is rigidly connected to an output shaft and said hydraulic engine or electric motor engages said planetary carrier.

4. The construction machine according to claim 1, wherein said hydraulic engine is driven by said internal combustion engine.

5. The construction machine according to claim 1, wherein said internal combustion engine cooperates with an accumulator for storing electrical energy emitted by the internal combustion engine.

6. The construction machine according to claim 1, wherein said milling rotor is designed for processing ground surfaces.

7. A method for effecting a change in the speed of rotation of a milling rotor located in a first drive train of a self-propelled construction machine, wherein an internal combustion engine generates a first speed of rotation (n.sub.1), and wherein a second speed of rotation (n.sub.2) generated by a CVT transmission is summated at a summating transmission designed as a planetary gear comprising a sun wheel with said first speed of rotation (n.sub.1) to create a third speed of rotation (n.sub.3) at an output shaft of said summating transmission, with the CVT transmission being adapted to be driven by the internal combustion engine, wherein the third speed of rotation (n.sub.3) is altered by changing the first speed of rotation (n.sub.1) and/or the second speed of rotation (n.sub.2) via the summating transmission.

8. The method according to claim 7, wherein said first speed of rotation (n.sub.1) is kept constant and said second speed of rotation (n.sub.2) is varied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is explained in detail below with reference to preferred exemplary embodiments shown in the figures, in which:

(2) FIG. 1 is a self-propelled construction machine for processing the ground;

(3) FIG. 2 is a detailed view of the device according to the present invention built into the construction machine shown in FIG. 1; and

(4) FIG. 3 to FIG. 15 each show an exemplary embodiment of the device according to the present invention.

(5) Like parts are identified in the figures by the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 illustrates a construction machine 1 in the form of a road milling machine comprising a machine frame 3 and wheels 4 adapted to process a traffic area 2. In the example shown, it comprises a working device 5 designed as a milling rotor 6. In the view shown in FIG. 1, the milling rotor 6 is in a descended working position. The direction of travel during the milling operation is identified by the arrow P.sub.1. In this case the direction of rotation of the milling rotor 6 indicated by the arrow P.sub.2 is contrary to the direction of rotation of the wheels 4 denoted by the arrow P.sub.3.

(7) According to FIG. 2, the construction machine 1 comprises a driving device 26 for the milling rotor 6. It comprises a first driving unit 7 driving a belt transmission 9 at a first speed of rotation n.sub.1 via an output shaft 8. In this case, the first driving unit 7 is the powerful main drive of the construction machine 1 and is designed as an internal combustion engine. A decoupling unit 12, a transfer gear 14, a resilient coupling 15, and a switchable clutch 16 are disposed on the output shaft 8 in that order between the first driving unit 7 and the belt transmission 9. In addition to the milling rotor 6, a number of other working devices (not shown) or implements of the construction machine 1 can be driven by the transfer gear 14, in this case designed as hydraulic variable displacement pumps 13.

(8) The belt transmission 9 drives a first driving shaft 10 for a gear 11 of the milling rotor 6 disposed within the milling rotor 6. In the example shown, the output shaft 8 and the first driving shaft 10 run at the same first speed of rotation n.sub.1. The gear 11 is designed as a triple-shaft transmission comprising a second driving shaft 18 driven by a second driving unit 19 in the milling rotor 6 at a second speed of rotation n.sub.2. The second driving unit 19 is designed as a secondary drive having a lower power output than the first driving unit 7. The gear 11 drives the milling rotor by means of an output shaft 24 at a third speed of rotation n.sub.3.

(9) Starting from the first and the second driving unit 7, 19 respectively, two drive trains are formed leading to the output shaft 24. The gear 11 is a summation transmission connecting the two drive trains to the output shaft 24 and guiding these towards the milling rotor 6. The third speed of rotation n.sub.3 can be altered by changing the first and/or the second speed of rotation n.sub.2 by way of the summation transmission. The third speed of rotation n.sub.3, in particular, can be altered by changing the second speed of rotation n.sub.2 independently of the first speed of rotation n.sub.1.

(10) FIG. 3 shows a first exemplary embodiment of the driving device 26.sub.1, in which the above described components between the first driving unit 7 and the belt transmission 9 are not shown for the sake of simplification. The belt transmission 9 is depicted by a cogwheel symbol and the transfer gear is depicted by a cogwheel 14. The gear 11 comprises a planetary gear 25 comprising a sun wheel 21, planetary wheels 22, and a first gear ring 20.

(11) The second driving unit 19 is connected via the second driving shaft 18 to a cogwheel 17 engaging the planetary gear 25. In this first example, the second driving unit 19 is designed as a controllable hydraulic engine.

(12) Via the transfer gear 14 and the belt transmission 9, the first driving unit 7 drives the driving shaft 10 comprising the sun wheel 21 at the first speed of rotation n.sub.1. Said sun wheel engages the planetary wheels 22 mounted for rotation on a planetary carrier 23. The planetary carrier 23 is non-rotatably connected to the output shaft 24 driving the milling rotor 6 (see FIGS. 1 and 2) at the third speed of rotation n.sub.3. The first gear ring 20 is mounted for rotation on the driving shaft 10 and comprises an inner intermeshing gear system 28 and an outer intermeshing gear system 29. The first gear ring 20 engages the planetary wheels 22 via the inner intermeshing gear system 28 whilst the second driving unit 19 engages the outer intermeshing gear system 29 of the first gear ring 20 by means of the cogwheel 17 at the second speed of rotation n.sub.2.

(13) The first drive train comprises the first driving unit 7, the transfer gear 14, the belt transmission 9, the sun wheel 21, the planetary wheels 22, and the planetary carrier 23. The second drive train comprises the second driving unit 19, the cogwheel 17, the first gear ring 20, the planetary wheels 22, and the planetary carrier 23.

(14) During operation, the first driving unit 7 drives the driving shaft 10 at the first speed of rotation n.sub.1, at which the sun wheel 21 also rotates. When the second driving unit 19 is at a standstill, the first gear ring 20 is also at a standstill, so that the planetary wheels 22 roll on the inner intermeshing gear system 28 of the first gear ring 20 and cause the planetary carrier 23 to rotate at the third speed of rotation n.sub.3 at a fixed ratio relative to the first speed of rotation n.sub.1, as determined by the gear ratios of the gear 11.

(15) In the event of the second driving unit 19 being operated at a second speed of rotation n.sub.20, the first gear ring 20 will rotate about the driving shaft 10. Accordingly, the planetary wheels 22 run at a different relative speed on the first gear ring 20 compared with the first gear ring 20 being at a standstill, resulting in a change in the third speed of rotation n.sub.3 of the output shaft 24. The third speed of rotation n.sub.3 may be increased or reduced depending on the direction of rotation and the second speed of rotation n.sub.2 of the second driving unit 19. In this way it is even possible to reduce the third speed of rotation n.sub.3 to zero. In addition, the direction of rotation of the output shaft 24 can also be altered by way of the second driving unit 19.

(16) When the first driving unit 7 is at a standstill, the second driving unit 19 determines the third speed of rotation n.sub.3.

(17) The second speed of rotation n.sub.2 of the second driving unit 19 can be controlled by a control device according to fixed algorithms, wherein a variety of programs can be provided for the various materials of the road surface 12 or for achieving the desired surface condition. Alternatively or additionally, the second speed of rotation n.sub.2 of the second driving unit 19 may also be regulated to suit various aims. In this case, the third speed of rotation n.sub.3 is registered by means of a sensor (not shown) and compared with a setpoint value. If necessary, the second speed of rotation n.sub.2 of the second driving unit 19 may be altered for the purpose of setting the setpoint value. In this way, it is possible to balance out any fluctuations in the first speed of rotation n.sub.1, or in the third speed of rotation n.sub.3.

(18) In the event of the second driving unit being used to start the milling rotor 6 and/or to support the milling operation, the performance ratio between the first driving unit 7 and the second driving unit 19 (P.sub.A1/P.sub.A2) is typically 10 or more. For example, P.sub.A1 can thus be 500 to 240 kW, the first speed of rotation n.sub.1 being, for example, 1800 min.sup.1 and the third speed of rotation n.sub.3 300 min.sup.1.

(19) For the purpose of effecting installation and maintenance work on the milling rotor 6, the first driving unit 7 will be disconnected and the milling rotor 6 moved solely by means of the second driving unit 19. To this end, the second driving unit 7 must be designed such that the third speed of rotation n.sub.3 can be adjusted to such a low setting that the milling rotor 6 can be moved slowly without risk to an operator and stopped at short angular intervals.

(20) FIG. 4 shows a second exemplary embodiment of the driving device 26.sub.2. This comprises a planetary gear 25 comprising the sun wheel 21, the planetary wheels 22, and a second gear ring 31. Unlike the first exemplary embodiment, a second planetary carrier 30 is mounted for rotation on the driving shaft 10 in the second exemplary embodiment, and the second gear ring 31 is non-rotatably connected to the output shaft 24. The second gear ring 31 comprises an inner intermeshing gear system 28 engaging the planetary wheels 22. The second driving unit 19 engages the second planetary carrier 30, which comprises an outer intermeshing gear system 29 for this purpose, by means of the cogwheel 17.

(21) In the present example, the first drive train comprises the first driving unit 7, the belt transmission 9, the sun wheel 21, the planetary wheels 22, and the second gear ring 31. The second drive train comprises the second driving unit 19, the cogwheel 17, the second planetary carrier 30, the planetary wheels 22, and the second gear ring 31.

(22) The exemplary embodiments shown in FIG. 5, FIG. 6, FIG. 7, and FIG. 8 each further illustrate examples for the propulsion of the second driving unit 19. In all other respects, the first and second drive trains each correspond to the drive trains of the first example illustrated in FIG. 3.

(23) FIG. 5 shows a third exemplary embodiment of the driving device 26.sub.3 wherein the second driving unit 19 designed as a hydraulic engine is supplied by one of the hydraulic pumps 13 via a hydraulic line 32. It is driven by a cogwheel 33 by way of the transfer gear 14. The first driving unit 7 thus also indirectly drives the second driving unit 19.

(24) The input shaft 10 is designed as a hollow shaft in order that the hydraulic line 32 can be guided into the milling rotor.

(25) In the fourth exemplary embodiment of the driving device 26.sub.4 shown in FIG. 6, the first driving unit 7 directly drives a hydraulic pump 34 supplying the second driving unit 19, designed as a hydraulic engine, by way of the hydraulic line 32.

(26) FIG. 7 shows a fifth exemplary embodiment of the driving device 26.sub.5 that differs from the first exemplary embodiment shown in FIG. 3 in that the second driving unit 19 is designed as an electric motor. A control unit 35 serves to control the speed of rotation and the power output.

(27) FIG. 8 shows a sixth exemplary embodiment of the driving device 26.sub.6, comprising a generator 36 in addition to the arrangement of the fifth exemplary embodiment as shown in FIG. 7. This serves to supply the second driving unit 19 designed as an electric motor and is directly driven by the first driving unit 7. The electric motor and the generator 36 are interconnected via an electric line 37. The generator 36 can be designed as a flywheel generator. In this case, the flywheel serves to store the kinetic energy provided by the first driving unit 7.

(28) The input shaft 10 is designed as a hollow shaft for the purpose of guiding the electric conductor 37 into the milling rotor.

(29) FIG. 9 shows a seventh exemplary embodiment of the driving device 26.sub.7, which differs from the sixth exemplary embodiment shown in FIG. 8 in that an accumulator 38 is provided between the second driving unit 19 designed as an electric motor and the generator 36 for the purpose of storing the electric energy generated by the generator 36. In this variant too, the generator 36 may be designed as a flywheel generator.

(30) In the eighth exemplary embodiment of the driving device 26.sub.8 shown in FIG. 10, the second driving unit 19 designed as an electric motor is supplied solely by a separate energy source 42, more particularly, by an accumulator. In other respects, the driving device 26.sub.8 is equivalent to the seventh exemplary embodiment shown in FIG. 9.

(31) FIG. 11 shows a ninth exemplary embodiment of the driving device 26.sub.9 in which the second driving unit 19 is designed as a continuous gear (CVT transmission). The pair of bevel disks 39 on the output side of the CVT transmission drives the second driving shaft 18 of the second drive train. In other respects, the first and second drive trains are equivalent to the first exemplary embodiment shown in FIG. 3. The pair of bevel disks 40 on the input side of the CVT transmission is connected to the output shaft 8 of the first driving unit 7 via the transfer gear 14 and a cogwheel 43. The gear ratio of the CVT transmission is set by means of an adjustable hydraulic unit 41 controlled by an adjusting or regulating device 42.

(32) The tenth exemplary embodiment shown in FIG. 12 comprises a planetary gear comprising a sun wheel 21, two planetary wheels 22, and a second gear ring 31 with the output shaft 24. A second planetary carrier 30 is driven by the transfer gear depicted as a cogwheel 14. The second planetary carrier is mounted for rotation on the second driving shaft 18, which, coming from the second driving unit 19, drives the sun wheel 21.

(33) An eleventh exemplary embodiment shown in FIG. 13 comprises a planetary gear 25 comprising a sun wheel 21, and a planetary carrier 23 on the output side comprising two planetary wheels 22. The shaft of the planetary carrier 23 forms the output shaft 24. A first gear ring 20 meshes with the two planetary wheels 22 by way of its inner intermeshing gear system 28. The first gear ring is driven by the cogwheel 14 via its outer intermeshing gear system 29. The first gear ring 20 is mounted for rotation on the second driving shaft 18, which, coming from the second driving unit 19, drives the sun wheel 21.

(34) The twelfth exemplary embodiment shown in FIG. 14 comprises a planetary gear 25 comprising a sun wheel 21, two planetary wheels 22, and a planetary carrier 30. The shaft of the sun wheel 21 forms the output shaft 24. A first gear ring 20 is mounted for rotation on the output shaft 24, its inner intermeshing gear system 28 meshing with the planetary wheels 22. This is driven by the cogwheel 14 by means of its outer intermeshing gear system 29. A cogwheel 17 engaging the second planetary carrier is non-rotatably mounted on the second driving shaft 18.

(35) The thirteenth exemplary embodiment shown in FIG. 15 differs from the twelfth exemplary embodiment shown in FIG. 14 in that the cogwheel 17 located on the second driving shaft 18 meshes with the outer intermeshing gear system 29 of the first gear ring and in that the first driving unit 7 drives the second planetary carrier 30 by way of the cogwheel 14.

(36) While the present invention has been illustrated by description of various embodiments and while those embodiments have been described in considerable detail, it is not the intention of Applicant to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily appear to those skilled in the art. The present invention in its broader aspects is therefore not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicants' invention.