power transmission device

Abstract

To downsize a power transmission device.SOLUTION: A power transmission device (1) according to an embodiment of the present disclosure comprises: a first driving unit (2) comprising a first driving source (21), and a first transmission (22) connected to the first driving source (21) so as to be capable of transmitting a driving force; a second driving unit (3) comprising a second driving source (31), and a second transmission (32) connected to the second driving source (31) so as to be capable of transmitting a driving force, and arranged in parallel with the first driving unit (2); and a friction type differential limiting element (4) arranged between the first transmission (22) and the second transmission (32), and for limiting a differential between rotation driving of the first transmission (22) and rotation driving of the second transmission (32).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power transmission. [Background technology]

[0002] Patent Document 1 discloses a power transmission device including a first drive source, a first differential gear connected to the first drive source so as to be able to transmit drive force, a second drive source, a second differential gear connected to the second drive source so as to be able to transmit drive force, and a differential limiting element connecting the first differential gear and the second differential gear.

[0003] In this case, the differential limiting element includes a differential gear having a first side gear fixed to a first connecting shaft connected to the first differential gear, a second side gear fixed to a second connecting shaft connected to the second differential gear, and a pinion gear meshed with the first side gear and the second side gear. The differential limiting element is configured to adjust the differential between the first connecting shaft and the second connecting shaft by the driving force of a motor connected to the pinion gear. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-283836 Summary of the Invention [Problem to be solved by the invention]

[0005] The present applicant has found the following problem: The power transmission device of Patent Document 1 has a problem of being large in size because the differential limiting element is configured by a differential gear.

[0006] The present disclosure has been made in consideration of such problems, and aims to achieve a reduction in the size of a power transmission device. [Means for solving the problem]

[0007] A power transmission device according to one aspect of the present disclosure includes: a first drive unit including a first drive source and a first transmission connected to the first drive source so as to be able to transmit drive force; a second drive unit including a second drive source and a second transmission connected to the second drive source so as to be able to transmit drive force thereto, the second drive unit being disposed in parallel with the first drive unit; a first friction-type differential limiting element disposed between the first transmission and the second transmission and limiting the differential between the rotational drive of the first transmission and the rotational drive of the second transmission; Equipped with.

[0008] In the above-described power transmission device, the first friction type differential limiting element preferably includes a viscous coupling.

[0009] In the above-described power transmission device, it is preferable that the first friction type differential limiting element comprises a first connecting shaft that connects the first transmission and the first friction type differential limiting element so as to be able to transmit driving force, and a first clutch plate that is connected so as to be able to transmit driving force, and a second connecting shaft that connects the second transmission and the first friction type differential limiting element so as to be able to transmit driving force, and a second clutch plate that is connected so as to be able to transmit driving force.

[0010] In the above-described power transmission device, it is preferable that the first friction type differential limiting element changes the contact force between the first clutch plate and the second clutch plate based on the axial force acting on the first connecting shaft.

[0011] The above-mentioned power transmission device a first protrusion provided on a gear of the first transmission; a second protrusion provided on the first connecting shaft, which comes into contact with the first protrusion when the gear rotates, thereby transmitting the driving force of the gear to the first connecting shaft; Equipped with It is preferable that the contact surface between the first convex portion and the second convex portion when the gear rotates in one direction has an inclined surface that slopes toward the rotation direction of the gear in the one direction as it moves toward the first drive unit in the axial direction of the first connecting shaft.

[0012] In the above-described power transmission device, it is preferable that the contact surface between the first convex portion and the second convex portion when the gear rotates in the other direction has a surface that is parallel to the axial direction of the first connecting shaft.

[0013] In the above-described power transmission device, it is preferable that the contact force between the first clutch plate and the second clutch plate varies based on the pressure of a pressure medium supplied to the first friction type differential limiting element.

[0014] The above-described power transmission device preferably includes a second friction-type differential limiting element that is disposed between the first transmission and the second transmission and at a location different from the first friction-type differential limiting element, and that limits the differential between the rotational drive of the first transmission and the rotational drive of the second transmission. [Effects of the Invention]

[0015] According to the present disclosure, it is possible to achieve a reduction in the size of the power transmission device. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a power transmission device according to a first embodiment. [Figure 2] FIG. 6 is a diagram showing a power transmission device according to a second embodiment. [Figure 3] 10 is a view of an engagement portion between a fourth gear of a first transmission and a connecting shaft in a power transmission device according to a second embodiment, as viewed from the negative Y-axis side. FIG. [Figure 4] 10 is a diagram showing the relationship between a first convex portion and a second convex portion of an engagement portion between a fourth gear of a first transmission and a connecting shaft in a power transmission device according to a second embodiment. FIG. [Figure 5] FIG. 10 is a diagram showing a power transmission device according to a third embodiment. [Figure 6] FIG. 1 is a diagram showing a solenoid valve used in a power transmission device. [Figure 7] FIG. 10 is a diagram showing a power transmission device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Specific embodiments to which the present disclosure is applied will be described in detail below with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0018] <First Embodiment> First, the configuration of the power transmission device of this embodiment will be described. The power transmission device of this embodiment is suitable as a power transmission device for a vehicle, for example. Fig. 1 is a diagram showing the power transmission device of this embodiment. In the following description, a three-dimensional (XYZ) coordinate system will be used for clarity.

[0019] As shown in FIG. 1, the power transmission device 1 includes a first drive unit 2, a second drive unit 3, and a friction type differential limiting element 4, which are housed in a housing 5.

[0020] 1, the first drive unit 2 includes a first drive source 21 and a first transmission 22. The first drive source 21 is, for example, a motor. That is, the first drive source 21 includes a stator 21a and a rotor 21b. However, the first drive source 21 is not limited to a motor and may be a drive source such as an internal combustion engine.

[0021] 1, the first transmission 22 includes a first gear 22a, a second gear 22b, a third gear 22c, and a fourth gear 22d. The first gear 22a is connected to a rotation shaft 21c of a rotor 21b in the first driving source 21 so as to be able to transmit driving force. The first gear 22a rotates around the Y axis.

[0022] As shown in Fig. 1, second gear 22b is meshed with first gear 22a and rotates around the Y axis. Third gear 22c is connected to second gear 22b via connecting shaft 22e extending in the Y axis direction so as to be able to transmit driving force, and rotates around the Y axis. Fourth gear 22d is meshed with third gear 22c and rotates around the Y axis. Fourth gear 22d is connected to wheel 6 on the positive side of the Y axis via connecting shaft 22f so as to be able to transmit driving force.

[0023] 1, the second drive unit 3 is disposed in parallel with the first drive unit 2 in the Y-axis direction. The second drive unit 3 has a configuration that is symmetrical with respect to the first drive unit 2, with an axis extending in the Z-axis direction as the axis of symmetry. Therefore, although a detailed description will be omitted, the second drive unit 3 includes a second drive source 31 and a second transmission 32. The second drive source 31 includes, for example, a stator 31a and a rotor 31b.

[0024] 1, the second transmission 32 includes a first gear 32a connected to a rotating shaft 31c of a rotor 31b in the second driving source 31 so as to transmit driving force, a second gear 32b meshed with the first gear 32a, a third gear 32c connected to the second gear 32b via a connecting shaft 32e so as to transmit driving force, and a fourth gear 32d meshed with the third gear 32c. The fourth gear 32d is connected to the wheel 7 on the negative side of the Y axis via a connecting shaft 32f so as to transmit driving force.

[0025] The friction type limited slip differential element 4 limits the differential between the rotational drive of the fourth gear 22d of the first transmission 22 and the rotational drive of the fourth gear 32d of the second transmission 32, i.e., the differential between the wheels 6 and 7. The friction type limited slip differential element 4 is disposed between the first transmission 22 and the second transmission 32, as shown in FIG.

[0026] The friction type differential limiting element 4 includes, for example, a viscous coupling. As shown in FIG. 1 , the friction type differential limiting element 4 includes, for example, a first clutch plate 41, a second clutch plate 42, a cylindrical portion 43, a third clutch plate 44, and a filler 45.

[0027] 1, the first clutch plate 41 has a disk shape that is substantially parallel to the XZ plane, and is connected to the fourth gear 22d of the first transmission 22 via a connecting shaft 8 so as to be able to transmit driving force. The second clutch plate 42 has a circular ring shape that is substantially parallel to the XZ plane, and is disposed on the negative side of the Y axis relative to the first clutch plate 41.

[0028] 1, the cylindrical portion 43 has a cylindrical shape extending in the Y-axis direction. The peripheral edge of the first clutch plate 41 is fixed to the end of the cylindrical portion 43 on the + side of the Y-axis, and the outer peripheral edge of the second clutch plate 42 is fixed to the end of the cylindrical portion 43 on the - side of the Y-axis. Therefore, the first clutch plate 41 and the second clutch plate 42 rotate in accordance with the rotation of the connecting shaft 8.

[0029] 1, the third clutch plate 44 has a disk shape that is substantially parallel to the XZ plane, and is disposed between the first clutch plate 41 and the second clutch plate 42. The third clutch plate 44 is connected to the fourth gear 32d of the second transmission 32 via the connecting shaft 9 so as to be able to transmit driving force.

[0030] At this time, the connecting shaft 9 is passed through the hollow portion of the second clutch plate 42. The space S1 surrounded by the first clutch plate 41, the cylindrical portion 43, and the second clutch plate 42 is a substantially sealed space.

[0031] Filler 45 is a silicone oil used in general viscous couplings, and fills space S1. Filler 45 expands in volume as it generates heat. However, the configuration of frictional limited slip differential element 4 is not limited to the above, and for example, the configuration of a general viscous coupling can be adopted.

[0032] Next, we will explain the operation of the friction type differential limiting element 4 of the power transmission device 1. Due to the differential between the rotational drive of the fourth gear 22d of the first transmission 22 and the rotational drive of the fourth gear 32d of the second transmission 32, a differential is generated between the first clutch plate 41 and the second clutch plate 42 and the third clutch plate 44.

[0033] At this time, as the differential movement between the first clutch plates 41 and the second clutch plates 42 and the third clutch plates 44 increases, the filler 45 generates heat and expands in volume, and the first clutch plates 41 and the third clutch plates 44, and the second clutch plates 42 and the third clutch plates 44 are connected so as to be able to transmit driving force via the filler 45. As a result, the power transmission device 1 limits the differential movement between the wheels 6 and 7.

[0034] In this way, the power transmission device 1 of this embodiment uses the friction type differential limiting element 4 to limit the differential between the rotational drive of the first transmission 22 and the rotational drive of the second transmission 32. In other words, the power transmission device 1 of this embodiment does not use a large-scale differential limiting element like the power transmission device of Patent Document 1, and therefore can be made smaller in size than the power transmission device of Patent Document 1.

[0035] Furthermore, by changing the temperature characteristics of the volume expansion of the filler 45 of the friction type differential limiting element 4, the rotational difference between the wheels 6 and 7 on which the friction type differential limiting element 4 operates, i.e., the frictional force between the first clutch plate 41, the second clutch plate 42 and the third clutch plate 44, can be easily adjusted.

[0036] <Embodiment 2> Fig. 2 is a diagram showing a power transmission device of this embodiment. Fig. 3 is a diagram showing an engagement portion between the fourth gear of the first transmission and the connecting shaft in the power transmission device of this embodiment, viewed from the Y-axis - side. Fig. 4 is a diagram showing the relationship between a first convex portion and a second convex portion of the engagement portion between the fourth gear of the first transmission and the connecting shaft in the power transmission device of this embodiment. Note that Figs. 3 and 4 show the first convex portion and the second convex portion in a simplified manner.

[0037] Since the power transmission device 200 of this embodiment has substantially the same configuration as the power transmission device 1 of Embodiment 1, duplicated explanations will be omitted and the same components will be described using the same reference numerals. In the power transmission device 200 of this embodiment, the friction type differential limiting element 210 includes a first clutch plate 211, a second clutch plate 212, and a friction plate 213, as shown in FIG.

[0038] 2, the first clutch plate 211 has a disk shape that is substantially parallel to the XZ plane, and is connected to the fourth gear 22d of the first transmission 22 via the connecting shaft 8 so as to be able to transmit driving force. Therefore, the first clutch plate 211 rotates in accordance with the rotation of the connecting shaft 8.

[0039] 2, the second clutch plate 212 has a disk shape that is substantially parallel to the XZ plane, and is disposed on the negative Y-axis side relative to the first clutch plate 211. The second clutch plate 212 is connected to the fourth gear 32d of the second transmission 32 via the connecting shaft 9 so as to be able to transmit driving force. Therefore, the second clutch plate 212 rotates in conjunction with the rotation of the connecting shaft 9.

[0040] At this time, the negative end of the Y-axis of the connecting shaft 9 is fixed to, for example, the fourth gear 32d of the second transmission 32, and movement in the Y-axis direction is substantially restricted. The friction plate 213 has an annular plate shape substantially parallel to the XZ plane, as shown in FIG. 2, for example, and is disposed between the first clutch plate 211 and the second clutch plate 212.

[0041] Such a friction-type differential limiting element 210 is actuated, for example, by the rotational drive of the wheel 6 when the wheel 6 rotates forward. In detail, as shown in Fig. 2, the power transmission device 200 has an engagement portion 220 between the fourth gear 22d of the first transmission 22 and the connecting shaft 8. As shown in Figs. 3 and 4, the engagement portion 220 has a first convex portion 221 and a second convex portion 222.

[0042] 3, the first protrusions 221 protrude toward the negative Y-axis side from the fourth gear 22d of the first transmission 22. The first protrusions 221 are arranged at approximately equal intervals in the circumferential direction of the fourth gear 22d, centered on the rotation axis of the fourth gear 22d, as viewed from the Y-axis direction.

[0043] 3 and 4, the first protrusion 221 has a generally rectangular block shape, and a first surface 221a on the side of the first protrusion 221 in the direction of rotation (the direction of arrow A) of the fourth gear 22d when the wheel 6 rotates forward is formed as an inclined surface that inclines toward the rotation direction of the fourth gear 22d as it moves toward the + side of the Y axis (i.e., the side of the wheel 6). On the other hand, a second surface 221b on the side of the first protrusion 221 opposite to the direction of rotation of the fourth gear 22d when the wheel 6 rotates forward is a flat surface that is generally parallel to the Y axis.

[0044] 3, the second protrusions 222 protrude radially outward from the end of the connecting shaft 8 on the + side of the Y axis. The second protrusions 222 are arranged at approximately equal intervals in the circumferential direction of the connecting shaft 8, centered on the rotation axis of the connecting shaft 8, as viewed from the Y axis direction. In this state, with the end of the connecting shaft 8 on the + side of the Y axis inserted inside the multiple first protrusions 221 lined up in the circumferential direction of the fourth gear 22d, the second protrusions 222 are arranged between the first protrusions 221. Therefore, the end of the connecting shaft 8 on the + side of the Y axis is not fixed to the fourth gear 22d of the first transmission 22, and the connecting shaft 8 is movable in the Y axis direction.

[0045] 3 and 4, the second protrusion 222 has a generally rectangular block shape, and is formed as an inclined surface that slopes toward the rotation direction of the connecting shaft 8 as the wheel 6 rotates forward in the second protrusion 222, in other words, the rotation direction of the fourth gear 22d, with the first surface 222a on the opposite side toward the +Y-axis side. On the other hand, the second surface 222b of the second protrusion 222 on the side facing the rotation direction of the connecting shaft 8 as the wheel 6 rotates forward is a flat surface that is generally parallel to the Y-axis.

[0046] At this time, the first surface 221a of the first convex portion 221 and the first surface 222a of the second convex portion 222 are capable of approximate surface contact, and the second surface 221b of the first convex portion 221 and the second surface 222b of the second convex portion 222 are capable of approximate surface contact.

[0047] In such a power transmission device 200, for example, when the wheels 6 and 7 are rotating forward, the first surface 221a of the first protrusion 221 comes into approximate surface contact with the first surface 222a of the second protrusion 222 arranged on the side of the rotation direction of the fourth gear 22d when the wheel 6 is rotating forward relative to the first protrusion 221, and pushes the second protrusion 222.

[0048] At this time, first surface 221a of first protrusion 221 and first surface 222a of second protrusion 222 are formed as inclined surfaces that incline toward the rotation direction of fourth gear 22d of first transmission 22 as they move toward the + side of the Y axis. In other words, the contact surface between first surface 221a of first protrusion 221 and first surface 222a of second protrusion 222 is an inclined surface that inclines toward the rotation direction of fourth gear 22d of first transmission 22 as it moves toward the + side of the Y axis.

[0049] Therefore, when first surface 221a of first protrusion 221 presses against first surface 222a of second protrusion 222, a force toward the negative Y-axis side is generated, and connecting shaft 8 is pressed toward the negative Y-axis side. Accordingly, first clutch plate 211 is pressed against second clutch plate 212 via friction plate 213. As a result, friction type differential limiting element 210 is activated, and the differential between wheel 6 and wheel 7 is limited.

[0050] On the other hand, in the power transmission device 200, for example, when the wheels 6 and 7 are rotating backward, the second surface 221b of the first convex portion 221 comes into approximate surface contact with the second surface 222b of the second convex portion 222 arranged on the side of the rotation direction of the fourth gear 22d when the wheel 6 rotates backward relative to the first convex portion 221, and pushes the second convex portion 222.

[0051] At this time, second surface 221b of first convex portion 221 and second surface 222b of second convex portion 222 are disposed approximately parallel to the Y axis. In other words, the contact surface between second surface 221b of first convex portion 221 and second surface 222b of second convex portion 222 is approximately parallel to the Y axis. Therefore, even if second surface 221b of first convex portion 221 presses against second surface 222b of second convex portion 222, no force is generated in the Y axis direction. As a result, friction type differential limiting element 210 does not operate, and differential movement between wheel 6 and wheel 7 is permitted.

[0052] In this way, power transmission device 200 can operate friction type limited slip differential element 210 with a simple configuration of engagement portion 220 using first convex portion 221 and second convex portion 222. Moreover, because power transmission device 200 uses friction type limited slip differential element 210 like power transmission device 1 of embodiment 1, it is possible to achieve a more compact power transmission device than the power transmission device of Patent Document 1.

[0053] In addition, by adjusting the inclination angle of the contact surface between the first surface 221a of the first protrusion 221 and the first surface 222a of the second protrusion 222 with respect to the Y axis, the friction force between the first clutch plate 211 and the second clutch plate 212 can be easily adjusted.

[0054] In this embodiment, an engagement portion 220 is provided between the fourth gear 22d of the first transmission 22 and the connecting shaft 8, but an engagement portion may be disposed between the fourth gear 32d of the second transmission 32 and the connecting shaft 9. In this case, the engagement portion 220 may be omitted. The engagement portion between the fourth gear 32d of the second transmission 32 and the connecting shaft 9 may be configured to be line-symmetrical with respect to the engagement portion 220, with an axis extending in the Z-axis direction as the axis of symmetry.

[0055] <Third Embodiment> Fig. 5 is a diagram showing a power transmission device of this embodiment. As shown in Fig. 5, the power transmission device 300 of this embodiment has substantially the same configuration as the power transmission device 1 of embodiment 1, so duplicated explanations will be omitted and the same reference numerals will be used for the same members.

[0056] 5, in power transmission device 300 of this embodiment, a cooling medium such as oil is supplied from pump 320 into housing 5 via check valve 310, and housing 5 is filled with the cooling medium. Friction type differential limiting element 330 is configured to operate using the cooling medium filled in housing 5 as a pressure medium.

[0057] At this time, the friction type differential limiting element 330 includes a first clutch plate 331, a second clutch plate 332, a piston 333, a friction plate 334, and a housing 335, as shown in FIG.

[0058] 5, the first clutch plate 331 has a disk shape that is substantially parallel to the XZ plane, and is connected to the fourth gear 22d of the first transmission 22 via the connecting shaft 8 so as to be able to transmit driving force. At this time, the end of the connecting shaft 8 on the Y-axis positive side is fixed to the fourth gear 22d of the first transmission 22, for example, and movement in the Y-axis direction is restricted.

[0059] 5, the second clutch plate 332 has a disk shape that is substantially parallel to the XZ plane, and is disposed on the negative Y-axis side relative to the first clutch plate 331. The second clutch plate 332 is connected to the fourth gear 32d of the second transmission 32 via the connecting shaft 9 so as to be able to transmit driving force. At this time, the connecting shaft 9 and the fourth gear 32d of the second transmission 32 are connected, for example, by a spline, which allows movement of the connecting shaft 9 in the Y-axis direction.

[0060] 5, the piston 333 has an annular plate shape that is approximately parallel to the XZ plane, and is disposed on the negative Y-axis side of the second clutch plate 332. The friction plate 334 has an annular plate shape that is approximately parallel to the XZ plane, and is disposed between the first clutch plate 331 and the second clutch plate 332.

[0061] 5, the housing 335 includes a first cylindrical portion 335a, a second cylindrical portion 335b, and an annular portion 335c, and is configured as a substantially sealed space. The first cylindrical portion 335a has a cylindrical shape extending in the Y-axis direction, for example, and covers the first clutch plate 331, the second clutch plate 332, the piston 333, and the friction plate 334. An end of the first cylindrical portion 335a on the positive side of the Y-axis is fixed to the periphery of the first clutch plate 331.

[0062] 5, the second cylindrical portion 335b has a cylindrical shape extending in the Y-axis direction and has a smaller diameter than the first cylindrical portion 335a. The second cylindrical portion 335b is disposed in a hollow portion of the first cylindrical portion 335a, and the connecting shaft 9 passes through the hollow portion of the second cylindrical portion 335b. A piston 333 is disposed between the first cylindrical portion 335a and the second cylindrical portion 335b so as to be movable in the Y-axis direction.

[0063] 5, the annular portion 335c has a generally annular plate shape that is generally parallel to the XZ plane. An end portion of the first cylindrical portion 335a on the negative Y-axis side is fixed to an outer peripheral edge portion of the annular portion 335c, and an end portion of the second cylindrical portion 335b on the negative Y-axis side is fixed to an inner peripheral edge portion of the annular portion 335c.

[0064] At this time, the space S2 surrounded by the first cylindrical portion 335a, the annular portion 335c, the second cylindrical portion 335b, and the piston 333 is a substantially sealed space, and the space S2 communicates with the inside of the housing 5. That is, although not shown, the housing 335 is formed with a communication portion that communicates the inside of the housing 5 with the space S2.

[0065] As a result, the cooling medium in the housing 5 enters the space S2, and the pressure of the cooling medium in the space S2 becomes approximately equal to the pressure of the cooling medium in the housing 5. Then, in the friction type differential limiting element 330, the piston 333 is pressed against the second clutch plate 332 by the pressure of the cooling medium in the space S2.

[0066] This causes the second clutch plate 332 to press the first clutch plate 331 via the friction plate 334, and as a result, the friction type differential limiting element 330 is activated to limit the differential between the wheels 6 and 7.

[0067] In such a power transmission device 300, the friction type limited slip differential element 330 preferably constantly presses the second clutch plates 332 against the first clutch plates 331 using a cooling medium filled in the housing 5. This allows the friction type limited slip differential element 330 to be constantly maintained in an operating state even if the first clutch plates 331, the second clutch plates 332, etc. wear.

[0068] By connecting the inside of the housing 5 with the space S2 of the frictional differential limiting element 330, the pressure of the cooling medium inside the housing 5 and the pressure of the cooling medium in the space S2 of the frictional differential limiting element 330 are made approximately equal. However, for example, the path for supplying the cooling medium into the housing 5 and the path for supplying a pressure medium such as oil to the space S2 of the frictional differential limiting element 330 may be separated, and the pressure of the pressure medium in the space S2 of the frictional differential limiting element 330 may be controlled separately.

[0069] In this case, the solenoid valve 340 shown in Fig. 6 may be disposed in the path that supplies the pressure medium to the space S2 of the friction type differential limiting element 330. This makes it possible to easily adjust the friction force between the first clutch plate 331 and the second clutch plate 332.

[0070] <Fourth Embodiment> Fig. 7 is a diagram showing a power transmission device of this embodiment. As shown in Fig. 7, power transmission device 400 of this embodiment has substantially the same configuration as power transmission device 200 of embodiment 2, so duplicated explanations will be omitted and the same reference numerals will be used for the same members.

[0071] The power transmission device 400 of this embodiment includes, for example, a first friction type differential limiting element 410 arranged between the fourth gear 22d of the first transmission 22 and the fourth gear 32d of the second transmission 32, as well as a second friction type differential limiting element 420 between the second gear 22b of the first transmission 22 and the second gear 32b of the second transmission 32.

[0072] For example, the friction type limited slip differential element 210 of the second embodiment can be used as the first friction type limited slip differential element 410 and the second friction type limited slip differential element 420. That is, the first friction type limited slip differential element 410 includes a first clutch plate 411 connected to the fourth gear 22d of the first transmission 22 via the connecting shaft 8 so as to be able to transmit driving force, a second clutch plate 412 connected to the fourth gear 32d of the second transmission 32 via the connecting shaft 9 so as to be able to transmit driving force, and a friction plate 413 disposed between the first clutch plate 411 and the second clutch plate 412.

[0073] The second friction type differential limiting element 420 also includes a first clutch plate 421 that is connected to the second gear 22b of the first transmission 22 via a connecting shaft 430 so as to be able to transmit driving force, a second clutch plate 422 that is connected to the second gear 32b of the second transmission 32 via a connecting shaft 440 so as to be able to transmit driving force, and a friction plate 423 that is arranged between the first clutch plate 421 and the second clutch plate 422.

[0074] A first engagement portion 450 is disposed between the fourth gear 22d of the first transmission 22 and the connecting shaft 8, and a second engagement portion 460 is disposed between the second gear 22b of the first transmission 22 and the connecting shaft 430. The first engagement portion 450 and the second engagement portion 460 have substantially the same configuration as the engagement portion 220 of the second embodiment.

[0075] Here, by differentiating the inclination angle relative to the Y axis of the contact surface between the first surface of the first convex portion and the first surface of the second convex portion in the first engagement portion 450 and the inclination angle relative to the Y axis of the contact surface between the first surface of the first convex portion and the first surface of the second convex portion in the second engagement portion 460, the operating characteristics of the first frictional differential limiting element 410 and the second frictional differential limiting element 420 (i.e., the frictional force between the first clutch plate and the second clutch plate) can be made different.

[0076] In this embodiment, a first engagement portion 450 is provided between the fourth gear 22d of the first transmission 22 and the connecting shaft 8, and a second engagement portion 460 is provided between the second gear 22b of the first transmission 22 and the connecting shaft 430, but an engagement portion may be provided between the fourth gear 32d of the second transmission 32 and the connecting shaft 9, or between the second gear 32b of the second transmission 32 and the connecting shaft 440.

[0077] Furthermore, in this embodiment, the first clutch plate is pressed into the second clutch plate by contact between the first surface of the first convex portion and the first surface of the second convex portion at the engagement portion, thereby activating the frictional differential limiting element. However, for example, by individually controlling the operation of the first clutch plate of the first frictional differential limiting element 410 and the operation of the first clutch plate of the second frictional differential limiting element 420 using a pressure medium, it is possible to activate, for example, the first frictional differential limiting element 410 when the power transmission device 400 is powered, and the second frictional differential limiting element 420 when the power transmission device 400 is regenerating.

[0078] The present disclosure is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the present disclosure. For example, the friction type differential limiting element in the above embodiment is merely an example, and may be configured to operate by the friction force between the first clutch plate and the second clutch plate. Furthermore, the actuation source for generating the friction force between the first clutch plate and the second clutch plate is not limited. For example, the power transmission device in the above embodiment is configured as a power transmission device for a vehicle, but it can also be applied to a power transmission device for a plant or the like, and is not limited thereto. [Explanation of symbols]

[0079] 1 Power transmission device 2 First drive unit 21 first driving source, 21a stator, 21b rotor, 21c rotating shaft 22 First Transmission 22a First Gear 22b Second Gear 22c Third Gear 22d Fourth Gear 22e, 22f connecting shaft 3 Second drive unit 31 second driving source, 31a stator, 31b rotor, 31c rotating shaft 32 Second Transmission 32a First Gear 32b Second Gear 32c Third Gear 32d Fourth Gear 32e, 32f connecting shaft 4 Friction-type differential limiting element 41 First clutch plate 42 Second clutch plate 43 Cylindrical part 44 Third clutch plate 45 Filler 5. Housing 6, 7 wheels 8, 9 Connecting shaft 200 Power Transmission Device 210 Friction-type differential limiting element 211 First clutch plate 212 Second clutch plate 213 Friction plate 220 Engagement part 221 first protrusion, 221a first surface, 221b second surface 222 second protrusion, 222a first surface, 222b second surface 300 Power Transmission Device 310 Check valve 320 Pump 330 Friction-type differential limiting element 331 First clutch plate 332 Second clutch plate 333 Piston 334 Friction plate 335 housing, 335a first cylindrical portion, 335b second cylindrical portion, 335c annular portion 340 Solenoid valve 400 Power Transmission Device 410 first friction type differential limiting element 411 First clutch plate 412 Second clutch plate 413 Friction plate 420 Second friction type differential limiting element 421 First clutch plate 422 Second clutch plate 423 Friction plate 430, 440 connecting shaft 450 first engagement portion 460 Second engagement portion S1, S2 space

Claims

1. a first drive unit including a first drive source and a first transmission connected to the first drive source so as to be able to transmit drive force; a second drive unit including a second drive source and a second transmission connected to the second drive source so as to be able to transmit drive force thereto, the second drive unit being disposed in parallel with the first drive unit; a first friction-type differential limiting element disposed between the first transmission and the second transmission and limiting a differential between a rotational drive of the first transmission and a rotational drive of the second transmission; a first protrusion provided on a gear of the first transmission; a second protrusion provided on a first connecting shaft that connects the first transmission and the first friction type differential limiting element so as to be able to transmit a driving force between them, and that comes into contact with the first protrusion when the gear rotates to transmit the driving force of the gear to the first connecting shaft; Equipped with the first friction type limited slip differential element has a first clutch plate connected to the first connecting shaft so as to be able to transmit a driving force, and a second connecting shaft connecting the second transmission and the first friction type limited slip differential element so as to be able to transmit a driving force, and a second clutch plate connected to the second connecting shaft so as to be able to transmit a driving force, a contact surface between the first convex portion and the second convex portion when the gear rotates in one direction has an inclined surface that inclines toward the first drive unit in the axial direction of the first connecting shaft in the direction of rotation of the gear in the one direction, and when the gear rotates in one direction and the first convex portion comes into contact with the second convex portion, the first clutch plate is pressed toward the second clutch plate via the first connecting shaft, thereby operating the first friction type limited slip differential element; a contact surface between the first convex portion and the second convex portion when the gear rotates in the other direction has a surface that is parallel to the axial direction of the first connecting shaft, and when the gear rotates in the other direction and the first convex portion comes into contact with the second convex portion, the first clutch plate is not pressed toward the second clutch plate via the first connecting shaft, and the first friction type differential limiting element is not activated.

2. The power transmission device of claim 1 , wherein the first frictional limited slip differential element comprises a viscous coupling.

3. 3. The power transmission device according to claim 1, further comprising a second friction type limited differential element disposed between the first transmission and the second transmission at a location different from the first friction type limited differential element, the second friction type limited differential element limiting the differential between the rotational drive of the first transmission and the rotational drive of the second transmission.

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