Power transmission

Abstract

To enable switching between a torque transmission route where torque is transferred from single electric motor to right and left wheels and a torque transmission route where torque is independently transferred from two electric motors to right and left wheels respectively.SOLUTION: A transmission system 1 comprises: two motors 2, 3; a first gear train 11 which changes speed of rotation between one side output shaft 21 connected to a left wheel 9L and one side counter shaft 23; a second gear train 12 which changes speed of rotation between the other side output shaft 22 connected to a right wheel 9R and the other side counter shaft 24; a differential gear 4 which has side gears 4a, 4b respectively fixed to one side counter shaft 23 and the other side counter shaft 24; a third gear train 13 which changes speed of rotation between the other side output shaft 22 and a differential case 4c; and a changeover mechanism 5 which transfers rotation of the second gear train 12 or the third gear train 13 to the other side output shaft 22. Power of one motor 2 among two motors 2, 3 is transferred to one side counter shaft 23 and power of the other motor 3 is transferred to the differential case 4c.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power transmission device for a vehicle equipped with two electric motors. [Background technology]

[0002] Conventionally, there is known a power transmission device having two electric motors that transmit torque independently to the left and right wheels of a vehicle. For example, Patent Document 1 discloses a power transmission device having a pair of electric motors, a pair of planetary gear mechanisms, and a brake means capable of restricting the rotation of third elements of the pair of planetary gear mechanisms. In Patent Document 1, the first elements of the pair of planetary gear mechanisms are connected to the pair of electric motors, respectively, and the second elements are connected to the left and right wheels, respectively. In addition, the third elements of the pair of planetary gear mechanisms are connected to each other, and the rotation of the third elements is restricted by the brake means, so that the left and right wheels are driven independently by the pair of electric motors, respectively. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-079348 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the efficiency of an electric motor (hereinafter also referred to as "motor") depends on the rotation speed and output torque of the motor, and tends to decrease as the rotation speed and output torque decrease. For this reason, for example, when the required torque is in a low torque range, it may be possible to reduce motor loss by driving the left and right wheels with one motor rather than driving the left and right wheels with two motors.

[0005] The power transmission device of the present invention has been devised in view of such problems, and one of its objectives is to be able to switch between a path in which one electric motor transmits torque to the left and right wheels and a path in which two electric motors transmit torque independently to the left and right wheels, respectively. However, this objective is not the only objective, and another objective of the present invention is to achieve an effect that cannot be obtained by the conventional technology, which is derived from each configuration shown in the below-mentioned embodiment. [Means for solving the problem]

[0006] (1) The power transmission device disclosed herein includes two electric motors, a first gear train that changes the rotation speed between a one-side output shaft connected to one of the left and right wheels and a one-side counter shaft that is arranged upstream of the one-side output shaft in a power transmission path, a second gear train that can change the rotation speed between an other-side output shaft connected to the other of the left and right wheels and an other-side counter shaft that is arranged upstream of the other-side output shaft in a power transmission path, a differential device that is interposed coaxially between the one-side counter shaft and the other-side counter shaft and has side gears fixed to each of the one-side counter shaft and the other-side counter shaft, a third gear train that can change the rotation speed between the other-side output shaft and a differential case of the differential device, and a first switching mechanism that is provided on the other-side output shaft and switches between a connected / disconnected state of the second gear train or the third gear train and the other-side output shaft to transmit the rotation of either the second gear train or the third gear train to the other-side output shaft. The power of one of the two electric motors is transmitted to the one counter shaft, and the power of the other of the two electric motors is transmitted to the differential case.

[0007] (2) When the second gear train and the other side output shaft are connected by the first switching mechanism, the power of the other electric motor is distributed to the one side counter shaft and the other side counter shaft via the differential case and transmitted to the left and right wheels, and the power of one electric motor is transmitted to the one side counter shaft, preferably actively generating a rotation speed difference between the left and right wheels.

[0008] (3) It is preferable that the power transmission device includes a fourth gear train that changes the rotation speed between one side input shaft that rotates coaxially with the rotating shaft of the one electric motor and the one side counter shaft, and a fifth gear train that changes the rotation speed between the other side input shaft that rotates coaxially with the rotating shaft of the other electric motor and the differential case.

[0009] (4) It is preferable that the power transmission device comprises a three-element, two-degree-of-freedom one-side planetary gear mechanism having as its first element a carrier that rotates integrally with the rotating shaft of the one electric motor, a three-element, two-degree-of-freedom other-side planetary gear mechanism having as its first element a carrier that rotates integrally with the rotating shaft of the other electric motor, an engine that transmits power to both the second element of the one-side planetary gear mechanism and the second element of the other-side planetary gear mechanism, a sixth gear train that changes the rotation between the third element of the one-side planetary gear mechanism and the one-side counter shaft, and a seventh gear train that changes the rotation between the third element of the other-side planetary gear mechanism and the differential case.

[0010] (5) In the above case of (4), it is preferable that the power transmission device further includes a second switching mechanism provided on the one counter shaft and configured to disconnect the sixth gear train and the one counter shaft. Effect of the Invention

[0011] According to the disclosed power transmission device, it is possible to switch between a path in which torque is transmitted to the left and right wheels by one electric motor and a path in which torque is transmitted independently to the left and right wheels by two electric motors. [Brief description of the drawings]

[0012] [Figure 1] 1 is a skeleton diagram of a power transmission device according to a first embodiment. FIG. [Diagram 2] 2 is a skeleton diagram of the power transmission device shown in FIG. 1 in a case where two electric motors transmit torque independently to the left and right wheels, respectively. [Diagram 3] 2 is a skeleton diagram of the power transmission device shown in FIG. 1 in the case where torque is transmitted to the left and right wheels by one electric motor. [Figure 4] FIG. 4 is a skeleton diagram of a power transmission device according to a modified example of the first embodiment. [Diagram 5] FIG. 6 is a skeleton diagram of a power transmission device according to a second embodiment. [Figure 6] 6 is a velocity diagram for explaining the operation of the power transmission device of FIG. 5. [Figure 7] 6 is a skeleton diagram of the power transmission device in FIG. 5 when torque is transmitted to the left and right wheels through a third path. FIG. [Figure 8] 8 is a velocity diagram for explaining the operation of the power transmission device in the state shown in FIG. 7. [Figure 9] 6 is a skeleton diagram of the power transmission device of FIG. 5 in the case where torque is transmitted to the left and right wheels through a fourth path. FIG. [Figure 10] 10 is a velocity diagram for explaining the operation of the power transmission device in the state shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A power transmission device according to an embodiment will be described with reference to the drawings. The embodiment described below is merely an example, and is not intended to exclude various modifications or application of techniques not specified in the following embodiment. Each configuration of the present embodiment can be modified in various ways without departing from the spirit of the embodiment. In addition, the configurations can be selected as necessary, or can be combined appropriately.

[0014] [1. First embodiment] [1-1. Configuration] FIG. 1 is a skeleton diagram showing a power transmission device 1 according to a first embodiment. The power transmission device 1 is applied to a vehicle (not shown) and transmits the driving force (torque) of two electric motors 2, 3 (hereinafter also simply referred to as "motors") provided as driving sources to left and right wheels 9L, 9R of the vehicle. The power transmission device 1 can be applied to either the front wheels or the rear wheels of the vehicle. The power transmission device 1 may also be applied to a vehicle equipped with an engine and generator (both not shown) for generating electricity. The power transmission device 1 may also be applied to a plug-in hybrid vehicle (PHEV) capable of at least one of external charging and external power supply.

[0015] The power transmission device 1 is provided with two motors 2 and 3, a differential device 4, three gear trains 11, 12, and 13, and a first switching mechanism 5. Furthermore, the power transmission device 1 of the first embodiment is provided with two gear trains 14 and 15 that make the axial positions of the two motors 2 and 3 and the differential device 4 different. The power transmission device 1 is configured to be able to switch between a first path in which the two motors 2 and 3 independently transmit torque to the left and right wheels 9L and 9R, respectively, and a second path in which one of the two motors 2 and 3 transmits torque to both the left and right wheels 9L and 9R via the differential device 4, using the first switching mechanism 5. In the first path, the driving force of the first motor 2 (one electric motor) is transmitted to the left wheel 9L (one of the left and right wheels), and the driving force of the second motor 3 (the other electric motor) is transmitted to the right wheel 9R (the other of the left and right wheels). In the second path, the driving force of the second motor 3 is transmitted to both the left and right wheels 9L and 9R.

[0016] The two motors 2, 3 are motor generators that combine the functions of an electric motor and a generator. An inverter (not shown) that converts DC current and AC current is provided around (or inside) each of the two motors 2, 3. The rotation speed of each of the two motors 2, 3 is controlled by controlling the inverter. The operating states of the two motors 2, 3 and each inverter are controlled by an electronic control device (not shown).

[0017] The differential device 4 is a differential device in which a differential gear supported by a container-shaped differential case 4c is interposed coaxially between a left countershaft 23 (one-side countershaft) and a right countershaft 24 (the other-side countershaft). The left countershaft 23 is a shaft arranged upstream of the power transmission path from the left output shaft 21 (one-side output shaft) connected to the left wheel 9L. The left countershaft 23 is arranged parallel to the left output shaft 21, and the shaft center position thereof is different from the shaft center position of the left output shaft 21. The right countershaft 24 is a shaft arranged upstream of the power transmission path from the right output shaft 22 (the other-side output shaft) connected to the right wheel 9R. The right countershaft 24 is arranged parallel to the right output shaft 22, and the shaft center position thereof is different from the shaft center position of the right output shaft 22. In other words, the differential device 4 is interposed between the countershafts 23 and 24 arranged at positions different from the output shafts 21 and 22 coaxially connected to the left and right wheels 9L and 9R, respectively.

[0018] The left side gear 4a fixed to the left countershaft 23, the differential pinion gear 4p pivoted to the differential case 4c, and the right side gear 4b fixed to the right countershaft 24 are housed in a meshed state inside the differential case 4c. The rotation axes of the left side gear 4a and the right side gear 4b are arranged on the same straight line, and the rotation axis of the differential pinion gear 4p is arranged perpendicular to this. The left side gear 4a, the differential case 4c, and the right side gear 4b are capable of transmitting power to each other, and their respective structures (positions, shapes, number of teeth) are set so that the rotation speeds on the collinear diagram are arranged linearly in this order.

[0019] Of the three gear trains 11, 12, and 13, the first gear train 11 changes the speed of rotation between the left output shaft 21 and the left counter shaft 23. The first gear train 11 is composed of an upstream fixed gear 11a fixed to the left counter shaft 23 and a downstream fixed gear 11b fixed to the left output shaft 21. The two fixed gears 11a and 11b are, for example, spur gears. The two fixed gears 11a and 11b are constantly meshed with each other and transmit the rotation of the left counter shaft 23 to the left output shaft 21 after changing the speed (for example, reducing the speed).

[0020] Of the three gear trains 11, 12, and 13, the second gear train 12 is configured to be able to change the rotation speed between the right output shaft 22 and the right counter shaft 24. The second gear train 12 is made up of an upstream fixed gear 12a fixed to the right counter shaft 24, and a downstream free-wheeling gear 12b supported so as to be rotatable relative to the right output shaft 22. The upstream fixed gear 12a and the downstream free-wheeling gear 12b are, for example, spur gears, and are constantly meshed with each other.

[0021] The second dog gear 5b of the first switching mechanism 5 is connected to one side of the downstream side idle gear 12b in the axial direction. In this embodiment, the second dog gear 5b is provided on the left side of the downstream side idle gear 12b. The second gear train 12 changes the speed of rotation between the right output shaft 22 and the right counter shaft 24 when the second dog gear 5b is rendered unable to rotate relative to the right output shaft 22 by the operation of the first switching mechanism 5. Specifically, the second gear train 12 changes the speed (e.g., reduces the speed) of the rotation of the right counter shaft 24 and transmits it to the right output shaft 22. The reduction ratio of the second gear train 12 is, for example, the same as the reduction ratio of the first gear train 11.

[0022] Of the three gear trains 11, 12, and 13, the third gear train 13 is configured to be able to change the rotation speed between the right output shaft 22 and the differential case 4c of the differential device 4. In this embodiment, the third gear train 13 is provided on the left side of the second gear train 12 (between the second gear train 12 and the differential case 4c). The third gear train 13 is made up of an upstream fixed gear 13a fixed to the differential case 4c, and a downstream free-wheeling gear 13b supported so as to be rotatable relative to the right output shaft 22. The upstream fixed gear 13a and the downstream free-wheeling gear 13b are, for example, spur gears, and are constantly meshed with each other.

[0023] The first dog gear 5a of the first switching mechanism 5 is connected to the other axial side of the downstream side idle gear 13b. In this embodiment, the first dog gear 5a is provided on the right side of the downstream side idle gear 13b. In other words, from the above-mentioned positional relationship, it can be said that the first dog gear 5a of this embodiment is arranged to face the second dog gear 5b connected to the downstream side idle gear 12b of the second gear train 12 in the axial direction.

[0024] The third gear train 13 changes the speed of rotation between the right output shaft 22 and the differential case 4c by making the first dog gear 5a unable to rotate relatively to the right output shaft 22 due to the operation of the first switching mechanism 5. Specifically, the third gear train 13 changes the speed (e.g., reduces the speed) of the rotation of the differential case 4c and transmits it to the right output shaft 22. The reduction ratio of the third gear train 13 is set to be the same as the reduction ratios of the first gear train 11 and the second gear train 12, for example.

[0025] The fourth gear train 14 changes the rotation speed between a first input shaft 25 (one-side input shaft) which rotates coaxially and integrally with the rotating shaft 2s of the first motor 2 and the left countershaft 23. The first input shaft 25 is a shaft disposed upstream of the left countershaft 23 in the power transmission path, and may be integral with the rotating shaft 2s or may be provided separately and connected to the rotating shaft 2s. The first input shaft 25 is disposed parallel to the left countershaft 23, and the axial position of the first input shaft 25 differs from the axial position of the left countershaft 23. In other words, the fourth gear train 14 not only changes the rotation speed between the first input shaft 25 and the left countershaft 23, but also makes the axial position of the first motor 2 different from that of the left countershaft 23.

[0026] The fourth gear train 14 is made up of an upstream fixed gear 14a fixed to the first input shaft 25 and a downstream fixed gear 14b fixed to the left counter shaft 23. The two fixed gears 14a, 14b are, for example, spur gears and are constantly meshed with each other. The fourth gear train 14 changes the speed (for example, reduces the speed) of the rotation of the first input shaft 25 in response to the drive of the first motor 2 and transmits it to the left counter shaft 23.

[0027] The fifth gear train 15 changes the rotation speed between the differential case 4c and a second input shaft 26 (the other input shaft) which rotates coaxially with the rotating shaft 3s of the second motor 3. The second input shaft 26 is a shaft disposed upstream of the differential case 4c in the power transmission path, and may be integral with the rotating shaft 3s or may be provided separately and connected to the rotating shaft 3s. The second input shaft 26 is provided parallel to the rotating shaft of the differential case 4c, and the axial position of the second input shaft 26 is different from the axial position of the rotating shaft of the differential case 4c. In other words, the fifth gear train 15 has a role of changing the rotation speed between the second input shaft 26 and the differential case 4c, as well as a role of making the axial position of the second motor 3 different from the axial position of the rotating shaft of the differential case 4c. As described above, since the differential gear 4 is coaxially interposed between the left countershaft 23 and the right countershaft 24, the latter role can be said to be a role of making the axial center position of the second motor 3 different from the axial center positions of the countershafts 23, 24.

[0028] The fifth gear train 15 is composed of an upstream fixed gear 15a fixed to the second input shaft 26 and a downstream fixed gear 15b fixed to the differential case 4c. The two fixed gears 15a, 15b are, for example, spur gears and are constantly in mesh with each other. The fifth gear train 15 changes (for example, reduces) the speed of the rotation of the second input shaft 26 in response to the drive of the second motor 3, Differential Case Transmit to 4c.

[0029] In FIG. 1, the second input shaft 26 is illustrated as being disposed inside the first input shaft 25, but the relative positions of the first input shaft 25 and the second input shaft 26 are not limited thereto. For example, the first input shaft 25 and the second input shaft 26 may be disposed in parallel with each other by making the axial center position of the upstream fixed gear 14a of the fourth gear train 14 and the axial center position of the upstream fixed gear 15a of the fifth gear train 15 different in the vehicle longitudinal direction. In this case, the two motors 2, 3 may be disposed at the same position in the lateral direction (parallel in the vehicle longitudinal direction). In addition, the second motor 3 may be disposed to the right of the upstream fixed gear 15a of the fifth gear train 15, and the second input shaft 26 may be extended to the right of the upstream fixed gear 15a of the fifth gear train 15.

[0030] The first switching mechanism 5 switches between a connected / disconnected state of the second gear train 12 or the third gear train 13 and the right output shaft 22 to transmit rotation of either the second gear train 12 or the third gear train 13 to the right output shaft 22, and is provided on the right output shaft 22. In this embodiment, the first switching mechanism 5 is disposed between the downstream idler gears 12b, 13b of the second gear train 12 and the third gear train 13, respectively.

[0031] The first switching mechanism 5 includes a first dog gear 5a, a second dog gear 5b, a hub 5h fixed to the right output shaft 22, and an annular sleeve 5s coupled to the right output shaft 22 so as to be rotatable relative to the hub 5h (right output shaft 22) and to be slidable in the axial direction of the right output shaft 22. The sleeve 5s moves from a neutral position in the figure to both the left and right sides by an actuator (not shown) controlled by an electronic control device. The sleeve 5s is provided on its radially inner side with spline teeth (not shown) that engage with the dog teeth of the dog gears 5a and 5b. The spline teeth engage with the dog teeth, so that the sleeve 5s engages with the first dog gear 5a or the second dog gear 5b. Hereinafter, the state in which the sleeve 5s engages with the first dog gear 5a will be referred to as a first state, and the state in which the sleeve 5s engages with the second dog gear 5b will be referred to as a second state. The first state is a state in which the rotation of the third gear train 13 is transmitted to the right output shaft 22 , and the second state is a state in which the rotation of the second gear train 12 is transmitted to the right output shaft 22 .

[0032] [1-2. Actions and Effects] The above-described power transmission device 1 can switch between a first path in which the two motors 2, 3 transmit torque independently to the left and right wheels 9L, 9R, respectively, and a second path in which the second motor 3 transmits torque to the left and right wheels 9L, 9R. The operation and effect of the power transmission device 1 will be described in detail below with reference to Fig. 2 and Fig. 3. Fig. 2 is a skeleton diagram for explaining the power transmission path when the first switching mechanism 5 is in the first state, and Fig. 3 is a skeleton diagram for explaining the power transmission path when the first switching mechanism 5 is in the second state.

[0033] When the first switching mechanism 5 is in the first state, that is, when the sleeve 5s is engaged with the first dog gear 5a, the rotation of the differential case 4c can be transmitted to the right output shaft 22 via the third gear train 13. As a result, as shown by the dotted arrows in Fig. 2, a first path is formed that is made up of two paths, a path through which the driving force of the first motor 2 is transmitted to the left wheel 9L and a path through which the driving force of the second motor 3 is transmitted to the right wheel 9R.

[0034] In detail, the power transmission device 1 can transmit the driving force of the first motor 2 to the left wheel 9L via the first input shaft 25, the fourth gear train 14, the left countershaft 23 (left side gear 4a), the first gear train 11, and the left output shaft 21. The power transmission device 1 can transmit the driving force of the second motor 3 to the right wheel 9R via the second input shaft 26, the fifth gear train 15, the differential case 4c, the third gear train 13, the first switching mechanism 5, and the right output shaft 22. Thus, the two motors 2 and 3 can transmit driving forces independently to the left and right wheels 9L and 9R, respectively. In this state, the downstream idling gear 12b of the second gear train 12 is idling, so that the difference in rotation between the two motors 2 and 3 is absorbed by the idling of the right side gear 4b.

[0035] On the other hand, when the first switching mechanism 5 is in the second state, that is, when the sleeve 5s is engaged with the second dog gear 5b, the rotation of the right counter shaft 24 can be transmitted to the right output shaft 22 via the second gear train 12. This forms a second path in which the driving force of the second motor 3 is distributed to the left and right wheels 9L, 9R via the differential device 4, as shown by the dotted arrow in Fig. 3 .

[0036] In detail, the power transmission device 1 can transmit the driving force of the second motor 3 to the differential case 4c via the second input shaft 26 and the fifth gear train 15. In the second state, the downstream free-wheeling gear 13b of the third gear train 13 having the upstream fixed gear 13a fixed to the differential case 4c rotates idly with respect to the right output shaft 22. Therefore, the driving force transmitted to the differential case 4c is distributed to the left and right counter shafts 23, 24 via the left and right side gears 4a, 4b, and transmitted to the left and right wheels 9L, 9R via the first gear train 11 and the second gear train 12 and the left and right output shafts 21, 22, respectively. In other words, when the first switching mechanism 5 is in the second state, the left and right wheels 9L, 9R are driven only by the driving force transmitted from the second motor 3.

[0037] The power transmission device 1 can run the vehicle while taking into consideration the motor efficiency by switching between the first path and the second path described above. Here, the efficiency of the motors 2, 3 depends on the rotation speed and output torque of the motors 2, 3, and tends to be lower as the rotation speed and output torque are lower. For this reason, for example, when the output torque of each of the motors 2, 3 becomes lower than a predetermined value, the power transmission device 1 selects the second path and causes the single motor 3 to output the output torque of the two motors 2, 3 (the output torque for two), thereby allowing the vehicle to run with good motor efficiency.

[0038] For example, when the required torque is in a low torque range, if the two motors 2, 3 drive the left and right wheels 9L, 9R independently, the two motors 2, 3 will share the required torque to drive the left and right wheels 9L, 9R. That is, in this case, each motor 2, 3 may operate in a range of poor motor efficiency with a torque lower than the required torque. In such a case, the power transmission device 1 can suppress a decrease in motor efficiency by selecting the second path and driving the left and right wheels 9L, 9R with one second motor 3. This can improve the electric power consumption of the vehicle and improve the following distance of the vehicle. On the other hand, when a high required torque is required, the power transmission device 1 can realize a high required torque by selecting the first path and driving the left and right wheels 9L, 9R with each of the two motors 2, 3.

[0039] Furthermore, in the power transmission device 1, the differential gear 4 is not interposed between the left output shaft 21 and the right output shaft 22, but is interposed between the left counter shaft 23 and the right counter shaft 24. By configuring the differential gear 4 to be interposed between the counter shafts 23 and 24, which are arranged at an axial position different from that of the output shafts 21 and 22, in this manner, switching between the first path and the second path can be achieved by a single first switching mechanism 5. This can contribute to reducing the cost and size of the vehicle.

[0040] In addition, as shown by the black arrow in FIG. 3, when the first switching mechanism 5 is in the second state, the power transmission device 1 can actively generate a rotation speed difference between the left and right wheels 9L, 9R by operating the first motor 2. That is, torque vectoring is possible. Specifically, in the second state, the power (positive and negative torque) of the first motor 2 is input to the left countershaft 23 via the first input shaft 25 and the fourth gear train 14, and this generates a rotation speed difference between the left and right wheels 9L, 9R. Therefore, by actively controlling the ratio of the driving force shared by the left and right wheels 9L, 9R, the magnitude of the yaw moment can be adjusted, thereby realizing a function of stabilizing the posture of the vehicle (so-called AYC function). The magnitude and direction of the rotation speed difference between the left and right wheels 9L, 9R correspond to the rotation amount and rotation direction of the first motor 2.

[0041] The power transmission device 1 is provided with a fourth gear train 14 and a fifth gear train 15. This allows the axial center positions of the rotating shafts 2s, 3s of the two motors 2, 3 to be different from the axial center positions of the counter shafts 23, 24, improving layout flexibility. For example, by arranging the two motors 2, 3 at the same position in the left-right direction (parallel to each other in the vehicle front-rear direction), the lateral width of the power transmission device 1 can be reduced.

[0042] [1-3. Modifications] The configuration of the power transmission device 1 described above is an example. The configuration of the power transmission device may be symmetrical to the power transmission device 1 described above. That is, the "one side" in the claims may be the right side, and the "other side" may be the left side. In addition, in the above embodiment, the first switching mechanism 5 is disposed between the second gear train 12 and the third gear train 13, but the first switching mechanism 5 is not limited to this position as long as it is configured to switch between a connected / disconnected state of the second gear train 12 or the third gear train 13 and the right output shaft 22.

[0043] The fourth gear train 14 and the fifth gear train 15 may be omitted. Fig. 4 is a skeleton diagram of a power transmission device 1' in which the fourth gear train 14 and the fifth gear train 15 are omitted. The modified power transmission device 1' differs from the above-mentioned power transmission device 1 in that the fourth gear train 14 and the fifth gear train 15 are omitted and two motors 2', 3' are arranged coaxially with countershafts 23', 24', but the other configurations are similar. In Fig. 4, components corresponding to those in Fig. 1 are denoted with a prime (') after the reference numerals in Fig. 1, and some of the reference numerals of the same components as those in Fig. 1 are omitted.

[0044] In the power transmission device 1' of the modified example, the rotating shaft 2s' of the first motor 2' and the left countershaft 23' rotate coaxially as one unit. Furthermore, the left countershaft 23' passes through the inside of the rotating shaft 3s' of the second motor 3' and is fixed to the left side gear 4a' of the differential device 4'. The rotating shaft 3s' of the second motor 3' is a hollow shaft and is directly connected to the differential case 4c'.

[0045] The power transmission device 1' can achieve the same effect as the above-mentioned power transmission device 1. That is, when the first switching mechanism 5' is in the first state, the two motors 2', 3' can form a first path for transmitting torque to the left and right wheels 9L', 9R' via the first gear train 11' and the third gear train 13', respectively. When the first switching mechanism 5' is in the second state, the second motor 3' can form a second path for transmitting torque to the left and right wheels 9L', 9R' via the differential device 4' and the first gear train 11' and the second gear train 12', respectively. Furthermore, compared to the above-mentioned power transmission device 1, the power transmission device 1' can reduce the number of shafts, thereby reducing power transmission loss and contributing to reducing the cost of the vehicle.

[0046] [2. Second embodiment] [2-1. Configuration] FIG. 5 is a skeleton diagram showing a power transmission device 1" as a second embodiment. In the following explanation, configurations different from the above-mentioned first embodiment will be mainly explained, and configurations corresponding to those in the first embodiment will be indicated with double quotation marks (") by the reference numerals in FIG. 1, and duplicate explanations will be omitted. Also, in FIG. 5, some of the reference numerals for configurations that are the same as those in FIG. 1 have been omitted.

[0047] The power transmission device 1" differs from the power transmission device 1 of the first embodiment mainly in that it includes an engine 6, two planetary gear mechanisms 71, 72, a second switching mechanism 8, and an eighth gear train 18, and in that it includes a sixth gear train 16 and a seventh gear train 17 instead of the fourth gear train 14 and the fifth gear train 15. In other words, the power transmission device 1" of the second embodiment is applied to a hybrid vehicle in which the power of the engine 6 can also be transmitted to the left and right wheels 9L", 9R". The vehicle may be a plug-in hybrid vehicle (PHEV) that is capable of at least one of external charging and external power supply. The second switching mechanism 8 disconnects the connection between the sixth gear train 16 and the left counter shaft 23" when a fourth path described later is formed, and keeps the sixth gear train 16 and the left counter shaft 23" connected in paths other than the fourth path.

[0048] Similarly to the power transmission device 1 of the first embodiment, the power transmission device 1'' is configured to be switchable between a first path in which two motors 2'', 3'' independently transmit torque to the left and right wheels 9L'', 9R'', and a second path in which one of the two motors 2'', 3'' transmits torque to both the left and right wheels 9L'', 9R'' via a differential device 4'' by a first switching mechanism 5''. Furthermore, the power transmission device 1'' is formed with a third path in which the engine 6 transmits torque to the left and right wheels 9L'', 9R'' via two planetary gear mechanisms 71, 72, respectively. Moreover, the power transmission device 1'' is formed with a fourth path in which the engine 6 transmits torque to both the left and right wheels 9L'', 9R'' via the differential device 4'' by the second switching mechanism 8 disconnecting the connection between the sixth gear train 16 and the left countershaft 23''.

[0049] Between the engine 6 and the two motors 2", 3", there are provided an eighth gear train 18 that changes the rotation speed of the engine 6, an engine side input shaft 27 to which a downstream fixed gear 18b of the eighth gear train 18 is fixed, and two planetary gear mechanisms 71, 72. The engine 6 is an internal combustion engine (gasoline engine, diesel engine) that burns gasoline or diesel. In this embodiment, the engine 6 is a so-called transversely mounted engine that is disposed sideways so that the orientation of the crankshaft 6a is parallel to output shafts 21", 22" connected to the left and right wheels 9L", 9R". The operating state of the engine 6 is controlled by an electronic control device.

[0050] The eighth gear train 18 changes the rotation speed between the crankshaft 6a and the engine side input shaft 27. The eighth gear train 18 is made up of an upstream side fixed gear 18a that rotates integrally with the crankshaft 6a, and a downstream side fixed gear 18b fixed to the engine side input shaft 27. The two fixed gears 18a, 18b are, for example, spur gears and are constantly meshed with each other. In this embodiment, the first motor 2'' and a first planetary gear mechanism 71, and the second motor 3'' and a second planetary gear mechanism 72 are coaxially arranged on either side of the eighth gear train 18.

[0051] As shown in FIG. 5, one end of the engine-side input shaft 27 is connected to a ring gear 71r (second element) of the first planetary gear mechanism 71. The engine-side input shaft 27 also passes through the interior of a rotating shaft 3s'' of a second motor 3'', and the other end of the engine-side input shaft 27 is connected to a sun gear 72s (second element) of a second planetary gear mechanism 72. The first planetary gear mechanism 71 is located to the right of the first motor 2'', and the second planetary gear mechanism 72 is located to the right of the second motor 3''.

[0052] The first planetary gear mechanism 71 and the second planetary gear mechanism 72 are three-element two-degree-of-freedom planetary gears having coaxially arranged sun gears 71s, 72s, carriers 71c, 72c, and ring gears 71r, 72r as elements. The ring gears 71r, 72r are annular, and the sun gears 71s, 72s are arranged coaxially with the ring gears 71r, 72r inside the ring gears 71r, 72r. Between the ring gears 71r, 72r and the sun gears 71s, 72s, planetary gears meshing with both the ring gears 71r, 72r and the sun gears 71s, 72s are provided, and the carriers 71c, 72c support the rotation centers of the planetary gears so as to be rotatable coaxially with the sun gears 71s, 72s.

[0053] In the first planetary gear mechanism 71 of the present embodiment, the ring gear 71r is fixed to the engine side input shaft 27, the carrier 71c (first element) rotates integrally with the rotating shaft 2s'' of the first motor 2'', and the sun gear 71s (third element) is fixed to the first input shaft 25''. The first input shaft 25'' is a shaft fixed to the upstream fixed gear 16a of the sixth gear train 16, and passes through the inside of the rotating shaft 2s'' of the first motor 2''.

[0054] In the second planetary gear mechanism 72 of this embodiment, the sun gear 72s is fixed to the engine side input shaft 27, the carrier 72c (first element) rotates integrally with the rotating shaft 3s'' of the second motor 3'', and the ring gear 72r (third element) is fixed to the second input shaft 26''. The second input shaft 26'' is fixed to the upstream fixed gear 17a of the seventh gear train 17.

[0055] The sixth gear train 16 is configured to be able to change the rotation speed between the first input shaft 25", i.e., the sun gear 71s of the first planetary gear mechanism 71, and the left counter shaft 23". The sixth gear train 16 includes an upstream fixed gear 16a fixed to the first input shaft 25", and a downstream idle gear 16b supported coaxially with the left counter shaft 23" and capable of rotating relative to the left counter shaft 23". The upstream fixed gear 16a and the downstream idle gear 16b are, for example, spur gears and are constantly meshed with each other.

[0056] A dog gear 8a of the second switching mechanism 8 is connected to the downstream idler gear 16b on the other axial side thereof. In this embodiment, the dog gear 8a is provided on the right side of the downstream idler gear 16b. Operation of the second switching mechanism 8 renders the dog gear 8a unable to rotate relative to the left counter shaft 23'', so that the sixth gear train 16 transmits the rotation of the first input shaft 25'' to the left counter shaft 23'' after changing its speed (for example, reducing the speed).

[0057] The seventh gear train 17 changes the rotation speed between the second input shaft 26", i.e., the ring gear 72r of the second planetary gear mechanism 72, and the differential case 4c". The seventh gear train 17 consists of an upstream fixed gear 17a fixed to the second input shaft 26", and a downstream fixed gear 17b fixed to the differential case 4c". The two fixed gears 17a, 17b are, for example, spur gears and are constantly meshed with each other. The reduction ratio of the seventh gear train 17 is, for example, the same as the reduction ratio of the sixth gear train 16.

[0058] The second switching mechanism 8 is provided on the left counter shaft 23". The second switching mechanism 8 has a dog gear 8a, a hub 8h fixed to the left counter shaft 23", and an annular sleeve 8s coupled to the left counter shaft 23" so as to be unable to rotate relatively to the hub 8h (left counter shaft 23") and to be slidable in the axial direction of the left counter shaft 23". Spline teeth (not shown) that engage with dog teeth of the dog gear 8a are provided on the radially inner side of the sleeve 8s. The sleeve 8s and the dog gear 8a are engaged with each other by the spline teeth engaging with each other. The sleeve 8s moves to the right from the engagement position in the drawing by an actuator (not shown) being controlled by an electronic control device, thereby separating the connection between the sixth gear train 16 and the left counter shaft 23". Hereinafter, the state in which the sleeve 8s is engaged with the dog gear 8a will be referred to as the "connected state", and the state in which the sleeve 8s is not engaged with the dog gear 8a will be referred to as the "disconnected state".

[0059] [2-2. Actions and Effects] The above-mentioned power transmission device 1" can also provide the same effects as those of the power transmission device 1 of the first embodiment. That is, when the engine 6 is stopped and the second switching mechanism 8 is connected, if the first switching mechanism 5" is in the first state, a first path is formed that is made up of two paths: a path through which the driving force of the first motor 2" is transmitted to the left wheel 9L" and a path through which the driving force of the second motor 3" is transmitted to the right wheel 9R". If the first switching mechanism 5" is in the second state, a second path is formed in which the driving force of the second motor 3" is distributed to the left and right wheels 9L", 9R" via the differential device 4". Thus, the power transmission device 1" can run the vehicle while taking motor efficiency into consideration by switching between the above-mentioned first and second paths.

[0060] FIG. 6 shows a speed diagram when power is transmitted to the left and right wheels 9L", 9R" via the first path or the second path. In the first path, the driving force of each of the two motors 2", 3" (MG1, MG2) is transmitted to the left and right wheels 9L", 9R", respectively. In the second path, the driving force of the second motor 3" (MG2) is transmitted to the left and right wheels 9L", 9R" via a differential device 4" (diff). At this time, the rotation of the left countershaft 23" is transmitted to the first motor 2" via the sixth gear train 16, the first input shaft 25" and the first planetary gear mechanism 71, thereby rotating the first motor 2" (MG1).

[0061] Furthermore, in the power transmission device 1″, when the engine 6 is operated, a third path is formed that transmits torque to each of the left and right wheels 9L″, 9R″ via the two planetary gear mechanisms 71, 72, respectively. This makes it possible to increase the number of vehicle driving patterns. This will be described in detail below with reference to FIGS. 7 and 8. FIG. 7 is a skeleton diagram for explaining the power transmission path when the engine 6 is operating and the first switching mechanism 5″ is in the first state, and FIG. 8 is a speed diagram for explaining the operation of the power transmission device 1″ in the state of FIG. 7. In the state of FIG. 7, the second switching mechanism 8 is in a connected state.

[0062] When the first switching mechanism 5" is in the first state, as shown by the dotted arrows in FIG. 7, a third path is formed in which the driving force of the engine 6 branches at the engine-side input shaft 27 and is transmitted to the left and right wheels 9L" and 9R" via each of the two planetary gear mechanisms 71 and 72. In detail, the driving force of the engine 6 input to the first planetary gear mechanism 71 is transmitted to the left wheel 9L" via the first input shaft 25", the sixth gear train 16, the second switching mechanism 8, the left counter shaft 23" (left side gear 4a"), the first gear train 11", and the left output shaft 21". In addition, the driving force of the engine 6 input to the second planetary gear mechanism 72 is transmitted to the right wheel 9L" via the second input shaft 26", the seventh gear train 17, the differential case 4c", the third gear train 13", the first switching mechanism 5", and the right output shaft 22". R By using the third path in this manner, the power transmission device 1'' can also transmit the driving force of the engine 6 to the left and right wheels 9L'' and 9R'', thereby increasing the number of driving patterns of the vehicle.

[0063] Furthermore, the third path overlaps with the first path. For this reason, as shown by the hollow arrows in FIG. 7, by putting the two motors 2", 3" into a powering state while the engine 6 is running, further driving force can be transmitted to the left and right wheels 9L", 9R". The solid lines in FIG. 8 are speed diagrams when the two motors 2", 3" are put into a powering state while the engine 6 is running (i.e., during parallel running). In addition to the driving force of the engine 6 (EG), the driving forces of the two motors 2", 3" (MG1, MG2) are transmitted to the left and right wheels 9L", 9R" via the two planetary gear mechanisms 71, 72, respectively.

[0064] Furthermore, as shown by the black arrows in FIG. 7, if the two motors 2", 3" are put into a regenerative state while the engine 6 is running, part of the driving force of the engine 6 transmitted to the left and right wheels 9L", 9R" can be used to make both of the motors 2", 3" generate electricity. The dashed lines in FIG. 8 are speed diagrams when the two motors 2", 3" are put into a regenerative state while the engine 6 is running. Part of the driving force of the engine 6 (EG) is used as power to rotate the two motors 2", 3" (MG1, MG2) in the negative direction (to generate electricity), and the remainder is transmitted to the left and right wheels 9L", 9R" via the two planetary gear mechanisms 71, 72, respectively.

[0065] The power transmission device 1" of this embodiment is provided with the second switching mechanism 8, which further increases the number of vehicle driving patterns. A detailed description will be given below with reference to Figs. 9 and 10. Fig. 9 is a skeleton diagram for explaining a power transmission path when the engine 6 is running, the first switching mechanism 5" is in the second state, and the second switching mechanism 8 is in a disconnected state, and Fig. 10 is a speed diagram for explaining the operation of the power transmission device 1" in the state shown in Fig. 9.

[0066] When the second switching mechanism 8 is put into the disconnected state, the connection between the first input shaft 25'' and the left counter shaft 23'' is cut off. In this state, when the first switching mechanism 5'' is put into the second state, a fourth path is formed in which the driving force of the engine 6 is distributed to the left and right wheels 9L'', 9R'' via the differential device 4'' as shown by the dotted arrow in FIG.

[0067] More specifically, the driving force of the engine 6 is input to the differential case 4c'' via the eighth gear train 18, the engine side input shaft 27, the second planetary gear mechanism 72, the second input shaft 26'' and the seventh gear train 17. Furthermore, similar to the second path, the driving force transmitted to the differential case 4c'' is distributed to the left and right counter shafts 23'' and 24'' via the left and right side gears 4a'' and 4b'', and is transmitted to the left and right wheels 9L'' and 9R'' via the first gear train 11'' and the second gear train 12'' and the left and right output shafts 21'' and 22'', respectively. By passing through the fourth path in this way, the power transmission device 1'' can also transmit the driving force of the engine 6 to the left and right wheels 9L'' and 9R'', thereby increasing the number of driving patterns of the vehicle.

[0068] In addition, in the state of FIG. 9, the engine 6 can transmit torque to the first motor 2" via the first planetary gear mechanism 71, and can also transmit torque to the second motor 3" via the second planetary gear mechanism 72, as indicated by the black arrows in FIG. 9. Therefore, if the two motors 2", 3" are in a regenerative state while the engine 6 is running, a portion of the driving force of the engine 6 transmitted to the left and right wheels 9L", 9R" can be used to make both of the two motors 2", 3" generate electricity. The solid lines in FIG. 10 are speed diagrams when the two motors 2", 3" are in a regenerative state while the engine 6 is running. A portion of the driving force of the engine 6 (EG) is used as power to rotate the two motors 2", 3" (MG1, MG2) in the negative direction (to generate electricity), and the remainder is transmitted to the left and right wheels 9L", 9R" via the differential device 4" (diff).

[0069] Furthermore, the fourth path overlaps with the second path. Therefore, as shown by the white arrow in FIG. 9, by putting the second motor 3'' into a power running state while the engine 6 is running, further driving force can be transmitted to the left and right wheels 9L'', 9R''. The dashed line in FIG. 10 is a speed diagram when the second motor 3'' is put into a power running state while the engine 6 is running. In addition to the driving force of the engine 6 (EG), the driving force of the second motor 3'' (MG2) is transmitted to the left and right wheels 9L'', 9R'' via a differential device 4'' (diff). At this time, part of the driving force of the engine 6 (EG) may be used as power to rotate the first motor 2'' (MG1) in the negative direction (to generate electricity).

[0070] [2-3.Other] The configuration of the power transmission device 1" described above is also one example. In the power transmission device 1" described above, the second switching mechanism 8 that disconnects the connection between the sixth gear train 16 and the left countershaft 23" may be omitted. In the power transmission device 1" described above, the ring gear 71r of the first planetary gear mechanism 71 is connected to the engine-side input shaft 27, and the sun gear 72s of the second planetary gear mechanism 72 is connected to the engine-side input shaft 27. However, the elements of the two planetary gear mechanisms 71, 72 connected to the engine-side input shaft 27 are not limited to this. For example, the first motor 2" may be arranged to the right of the first planetary gear mechanism 71, and the sun gear 71s of the first planetary gear mechanism 71 may be connected to the engine-side input shaft 27. Moreover, the second motor 3" may be arranged to the right of the second planetary gear mechanism 72, and the ring gear 72r of the second planetary gear mechanism 72 may be connected to the engine-side input shaft 27. [Explanation of symbols]

[0071] 1,1',1" Power Transmission Unit 2,2',2" First motor (electric motor) 2s, 2s', 2s" Rotation axis 3,3′,3″ Second motor (electric motor) 3s, 3s′, 3s″ Rotation axis 4,4′,4″ differential 4a,4a',4a" Left side gear 4b,4b′,4b″ Right side gear 4c, 4c', 4c" differential case 5,5′,5″ First change mechanism 6 Engine 8 Second switching mechanism 9L,9L′,9L″ Left wheel 9R,9R′,9R″ Right wheel 11,11′,11″ 1st gear train 12,12′,12″ 2nd gear train 13,13′,13″ 3rd gear train 14 Fourth gear train 15 Fifth gear train 16 Sixth Gear Train 17 Seventh gear train 21,21′,21″ Left output shaft (one side output shaft) 22,22′,22″ Right side output shaft (other side output shaft) 23,23′,23″ Left countershaft (one side countershaft) 24,24′,24″ Right countershaft (other countershaft) 25,25″ First input shaft (One side input shaft) 26,26″ Second input shaft (other side input shaft) 71 First planetary gear mechanism (one-side planetary gear mechanism) 71c Career (first element) 71r Ring gear (second element) 71s Sun gear (third element) 72 Second planetary gear mechanism (other side planetary gear mechanism) 72c Career (first element) 72r Ring gear (third element) 72s Sun gear (second element)

Claims

1. Two electric motors; a first gear train that changes the rotation speed between a first output shaft connected to one of the left and right wheels and a first counter shaft that is disposed upstream of the first output shaft in a power transmission path; a second gear train capable of changing the rotation speed between an other output shaft connected to the other of the left and right wheels and an other counter shaft disposed upstream of the other output shaft in a power transmission path; a differential device that is coaxially interposed between the one-side counter shaft and the other-side counter shaft and has side gears fixed to the one-side counter shaft and the other-side counter shaft, A third gear train capable of changing the rotation speed between the other output shaft and a differential case of the differential device; a first switching mechanism that is provided on the other-side output shaft and switches between a connected / disconnected state of the second gear train or the third gear train and the other-side output shaft to transmit rotation of one of the second gear train and the third gear train to the other-side output shaft, The power of one of the two electric motors is transmitted to the one side counter shaft, The power of the other of the two electric motors is transmitted to the differential case. A power transmission device comprising:

2. When the second gear train and the other-side output shaft are in a connected state by the first switching mechanism, The power of the other electric motor is distributed to the one-side counter shaft and the other-side counter shaft via the differential case and transmitted to the left and right wheels, The power of one of the electric motors is transmitted to the one side counter shaft to actively generate a rotation speed difference between the left and right wheels.

2. A power transmission device according to claim 1 .

3. a fourth gear train for changing the speed of rotation between an input shaft on one side and a counter shaft on one side, the input shaft coaxially rotating integrally with a rotary shaft of the one electric motor; a fifth gear train that changes the rotation speed between the differential case and another input shaft that rotates coaxially with the rotation shaft of the other electric motor, 3. A power transmission device according to claim 1 or 2.

4. a one-side planetary gear mechanism having three elements and two degrees of freedom, the one side planetary gear mechanism having a carrier as a first element that rotates integrally with a rotary shaft of the one electric motor; a second planetary gear mechanism having three elements and two degrees of freedom, the first element being a carrier that rotates integrally with a rotary shaft of the second electric motor; an engine that transmits power to both the second element of the one-side planetary gear mechanism and the second element of the other-side planetary gear mechanism; a sixth gear train that changes the rotation speed between the third element of the one-side planetary gear mechanism and the one-side countershaft; a seventh gear train that changes the rotation speed between the third element of the other planetary gear mechanism and the differential case.

3. A power transmission device according to claim 1 or 2.

5. A second switching mechanism is provided on the one side counter shaft and separates the connection between the sixth gear train and the one side counter shaft.

5. A power transmission device according to claim 4, characterized in that

Images