Power transmission device

Abstract

To improve pressing force for pressing an engagement element in an engagement device.SOLUTION: An engagement device 140 has a pressure plate 160 for pressing a clutch 150, a planetary gear mechanism 170, a motor 180 that inputs rotation to the planetary gear mechanism 170, an engagement output shaft 173 that is drivingly connected to each of a plurality of pinion gears 170P, and a screw portion 141 formed on the engagement output shaft 173 and the pressure plate 160. By rotating the engagement output shaft 173 in a first direction R1, the screw portion 141 moves the pressure plate 160 toward the clutch 150 in a direction of the rotation center line, so that the pressure plate 160 presses the clutch 150 to bring the clutch 150 into an engagement state. By rotating the engagement output shaft 173 in a second direction R2, the screw portion 141 moves the pressure plate 160 away from the clutch 150 in the direction of the rotation center line, so that the pressure on the clutch 150 by the pressure plate 160 is released to bring the clutch 150 into a released state.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This technology relates to a power transmission device mounted on a vehicle such as an automobile, for example.

Background Art

[0002] Conventionally, a differential device has been widespread as an example of a power transmission device suitable for mounting on a vehicle. The differential device has, for example, a first output shaft and a second output shaft arranged coaxially, and a differential mechanism that allows differential of the first output shaft and the second output shaft while transmitting the rotation of an input member to these first output shaft and second output shaft. Further, in recent years, a configuration has been known in which a third output shaft arranged coaxially with the first output shaft and the second output shaft, and an engagement device (so-called disconnect mechanism) that switches connection and disconnection between the first output shaft and the third output shaft are provided (see Patent Document 1).

[0003] This engagement device has, for example, a plurality of friction plates for connecting and disconnecting the first output shaft and the third output shaft, a pressing mechanism for pressing and engaging the friction plates, and an actuator such as an electric motor for operating the pressing mechanism. In this pressing mechanism, the rotation transmitted from the actuator via a reduction mechanism is converted into a pressing force in a linear direction using a ball cam or a ball screw.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the engagement device described in Patent Document 1, for example, when a ball cam is applied, since the pressing force of the ball cam is relatively small, it is necessary to increase the number of friction plates in order to ensure the torque capacity of the friction plate, and there is a problem that abrasion is likely to occur on the friction plate when the output shaft rotates.

[0006] Therefore, an object of the present invention is to provide a power transmission device including an engagement device capable of improving the pressing force for pressing an engagement element.

Means for Solving the Problems

[0007] A power transmission device according to an aspect of the present invention includes an input member drivingly connected to a drive source, an output member drivingly connected to a wheel, a transmission mechanism portion provided on a power transmission path between the input member and the output member, and an engagement device having an engagement element that engages by being pressed to connect power transmission between the input member and the output member. The engagement device includes a pressing portion that presses the engagement element, a plurality of output rotating elements, and an engaging rotating element that meshes with the plurality of output rotating elements, and has a planetary gear mechanism that rotates the plurality of output rotating elements by the input rotation, an engagement drive source that inputs rotation to the planetary gear mechanism, an engagement output shaft drivingly connected to each of the plurality of output rotating elements, a screwing portion formed on the engagement output shaft, and a screwed portion formed on the pressing portion and screwed with the screwing portion, and includes a screw portion. By rotating the engagement output shaft in a first direction, the screw portion moves the pressing portion toward the engagement element in the direction of the rotation center line, presses the engagement element by the pressing portion to bring the engagement element into an engaged state, and by rotating the engagement output shaft in a second direction opposite to the first direction, the screw portion moves the pressing portion away from the engagement element in the direction of the rotation center line, releases the pressing of the engagement element by the pressing portion, and brings the engagement element into a released state.

Effects of the Invention

[0008] In the engagement device of the power transmission device, the pressing force for pressing the engagement element can be improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0010] <The First Embodiment> Hereinafter, the power transmission device according to the first embodiment will be described. First, the schematic configuration of the vehicle 1 on which the power transmission device according to the present embodiment is mounted will be described with reference to FIG. 1. As shown in FIG. 1, the vehicle 1 has the direction F as the forward traveling direction, and the left - right direction is shown as the right side R and the left side L in the figure. The vehicle 1 is, for example, an electric vehicle on which the power transmission device is mounted. Generally, it includes an ECU 2 which is a control unit, a drive unit 110 on the front - wheel side, left and right front wheels 3L, 3R which are drivingly connected to the drive unit 110 via left and right drive shafts 111L, 111R, a drive unit 190 on the rear - wheel side, and left and right rear wheels 4L, 4R which are drivingly connected to the drive unit 190 via left and right drive shafts 191L, 191R. In the present embodiment, the drive shaft 111R on the right side R is an example of an output member drivingly connected to the front wheel 3R which is a wheel.

[0011] The drive unit 110 on the front - wheel side (front) is provided with a motor 112 (MG1) which is a rotary electric machine (motor - generator) as a drive source for front - wheel drive, and a differential device 113 for the front wheels that transmits the rotation of the motor 112 to the left and right front wheels 3L, 3R. Further, an inverter 6 which is connected to the power source 5 (BATTERY) of the vehicle 1 and is controlled by the ECU 2 is connected to the drive unit 110. Similarly, the drive unit 190 on the rear - wheel side (rear) is provided with a motor 192 (MG2) which is a rotary electric machine (motor - generator) as a drive source for rear - wheel drive, and a differential device 193 for the rear wheels that transmits the rotation of the motor 192 to the left and right rear wheels 4L, 4R. Further, an inverter 7 which is connected to the power source 5 of the vehicle 1 and is controlled by the ECU 2 is connected to the drive unit 190.

[0012] The inverter 6 of the drive unit 110 is PWM - controlled by the ECU 2, drives the motor 112 with the power of the power source 5, or regenerates with the motor 112 to charge the power source 5. Similarly, the inverter 7 of the drive unit 190 is PWM - controlled by the ECU 2, drives the motor 192 with the power of the power source 5, or regenerates with the motor 192 to charge the power source 5.

[0013] [Drive unit] The drive unit 110 on the front wheel side will be described with reference to FIG. 2. Note that the drive unit 190 on the rear wheel side has the same configuration as the drive unit 110 on the front wheel side described below, so a detailed description thereof will be omitted.

[0014] [Configuration of the case] The drive unit 110 includes a main case 114 that houses a motor 112 and a differential device 113, an intermediate plate 115 that partitions the internal space of the main case 114, a cover 116 that closes the opening of the main case 114, a sub-case 117 that is further attached to the outside of the cover 116, and a sub-cover 185 that closes the opening of the sub-case 117.

[0015] [Motor] The motor 112 is an example of a drive source, and is housed in a space defined by the main case 114 and the intermediate plate 115. It has a stator 112a which is a stator fixed to the main case 114, and a rotor 112b which is a rotor that rotates by induction of an embedded magnet by the magnetic force from a coil disposed on the stator 112a. Further, the rotor 112b is fixed so as to rotate integrally with the rotor shaft 118. The rotor shaft 118 is rotatably supported by a bearing 119 with respect to the main case 114 and by a bearing 120 with respect to the intermediate plate 115. The rotor shaft 118 is an example of an input member that is drivingly connected to the motor 112.

[0016] [Reduction mechanism] A speed reduction mechanism 121 composed of a planetary gear mechanism is interposed on the power transmission path between the rotor shaft 118 and the differential device 113. The speed reduction mechanism 121 is housed in the space between the middle plate 115 and the cover 116. The speed reduction mechanism 121 includes a sun gear 121S formed on the rotor shaft 118, a ring gear 121R, and a carrier 121C that rotatably supports pinion gears 121P meshing with the sun gear 121S and the ring gear 121R. A bearing 122 is provided between the shaft portion of the carrier 121C and the pinion gear 121P, and the pinion gear 121P is rotatably supported with respect to the shaft portion. The carrier 121C is drivingly connected to a transmission shaft 123 disposed coaxially with the rotor shaft 118. The transmission shaft 123 is rotatably supported by a bearing 124 with respect to the rotor shaft 118 and by a bearing 125 with respect to the cover 116. A transmission gear 126 is fixed to the transmission shaft 123 so as to rotate integrally.

[0017] [Differential device] The differential device 113 is an example of a transmission mechanism portion provided on the power transmission path between the rotor shaft 118 and the drive shaft 111R. The transmission mechanism portion here is a mechanism that transmits power only by gears, for example. The differential device 113 includes a differential case 127, a side gear 131 on the right side R which is a first transmission output member arranged coaxially with the drive shaft 111R, and a side gear 132 on the left side L which is a second transmission output member, and a differential mechanism 113a that allows differential of the side gears 131, 132 while transmitting the rotation of the rotor shaft 118 to the side gears 131, 132. The differential mechanism 113a includes a differential ring gear 128 integrated with the differential case 127, and a pinion gear 130 that is rotatably supported by a shaft 129 supported by the differential case 127 and meshes with the side gears 131, 132. The differential ring gear 128 meshes with a transmission gear 126 and is rotatably supported by a bearing 133 with respect to the cover 116. The side gear 131 on the left side L is drivingly connected to the drive shaft 111L. The drive shaft 111L is rotatably supported by a bearing 134 with respect to the main case 114, and an oil seal 135 is provided between the drive shaft 111L and the main case 114 to suppress oil leakage from the inside of the drive unit 110. The side gear 132 on the right side R is drivingly connected to an intermediate shaft 136. In addition, in the present embodiment, the case where the differential device 113 has a differential ring gear 128 and side gears 131, 132 has been described, but the present invention is not limited to this, and for example, a configuration applying a planetary gear mechanism may be used as the differential device.

[0018] The intermediate shaft 136 is rotatably supported by a bearing 137 with respect to the differential ring gear 128, and can be drivingly connected to the drive shaft 111R via an engagement device 140 described later. A clutch drum 138 is fixed to the intermediate shaft 136 so as to rotate integrally. The clutch drum 138 is rotatably supported by a bearing 139 with respect to the cover 116. The differential device 113 is configured to transmit the rotation of the differential ring gear 128 to the left and right drive shafts 111L, 111R while absorbing the differential rotation of the side gears 131, 132.

[0019] [Engaging device] Next, the engaging device 140, which is a disconnect mechanism for switching the intermediate shaft 136 and the drive shaft 111R between a connected state and a disconnected state, will be described. The engaging device 140 is housed in a space defined by the sub-case 117, the cover 116, and the sub-cover 185. The engaging device 140 includes a clutch 150, a pressure plate 160 capable of pressing the clutch 150, a planetary gear mechanism 170 capable of pressing the pressure plate 160, and an electric motor 180 for inputting rotation to the planetary gear mechanism 170. Note that the drive shaft 111R is rotatably supported by a bearing 186 with respect to the clutch drum 138 and by a bearing 187 with respect to the sub-cover 185, and an oil seal 188 is provided between the drive shaft 111R and the sub-cover 185 to suppress oil leakage from the inside of the drive unit 110.

[0020] The clutch 150 has a plurality of outer friction plates 151 and a plurality of inner friction plates 152. The outer friction plates 151 are spline-engaged with a spline 138s formed on the inner peripheral side of the drum portion of the clutch drum 138. The inner friction plates 152 are spline-engaged with a spline 111s formed on the outer peripheral side of the large-diameter portion of the drive shaft 111R. An end plate 153 is spline-engaged with the spline 138s. The end plate 153 is positioned and fixed with respect to the clutch drum 138 toward the left side L. In the present embodiment, the plurality of outer friction plates 151 and the plurality of inner friction plates 152 are an example of engaging elements, and when pressed, they engage to connect the power transmission between the rotor shaft 118 and the drive shaft 111R.

[0021] The pressing plate 160 is an example of a pressing part, and is a substantially annular member arranged on the right side R coaxial with the clutch 150, and can press the clutch 150 between it and the clutch drum 138. The pressing plate 160 is supported by the sub-cover 185 so as to be movable in the left-right direction (the direction of the rotation center line) by spline engagement. In the present embodiment, a bearing 161 made of, for example, a ball bearing is provided between the pressing plate 160 and the rightmost inner friction plate 152, and the pressing plate 160 presses the clutch 150 via the bearing 161.

[0022] The planetary gear mechanism 170 is interposed on the power transmission path between the pressing plate 160 and the motor 180, and is arranged with the rotation center line in the left-right direction. The planetary gear mechanism 170 includes a ring gear 170R and a carrier that rotatably supports a plurality of pinion gears 170P meshing with the ring gear 170R. In the present embodiment, the pinion gears 170P are arranged at three positions at equal intervals of 120 degrees in the rotational direction centered on the rotation center when viewed from the direction of the rotation center line (see FIG. 5). The ring gear 170R is an example of a meshing rotation element having internal teeth meshing with a plurality of pinion gears 170P, and the plurality of pinion gears 170P rotate synchronously. In the present embodiment, the case where the pinion gears 170P are arranged at three positions at equal intervals has been described, but it is not limited thereto, and they may be arranged at three non-equidistant positions, or provided at four or more positions at equal intervals, or provided at four or more non-equidistant positions.

[0023] In the present embodiment, the carrier is constituted by the sub-cover 185. Therefore, the carrier is fixed without rotating. The shaft portion of the pinion gear 170P is rotatably supported by the sub-cover 185 by a ball bearing 171, and the gear portion of the pinion gear 170P is rotatably supported by the sub-cover 185 by a thrust bearing 172. In this planetary gear mechanism 170, since the revolution of the pinion gear 170P is fixed by the sub-cover 185 which is the carrier, the pinion gear 170P rotates on its own axis at a fixed position due to the rotation of the ring gear 170R. That is, the pinion gear 170P is an example of an output rotation element with a fixed revolution.

[0024] On the left side L of each pinion gear 170P, an engagement output shaft 173 drivingly connected to the pinion gear 170P is provided. The engagement output shaft 173 is arranged with its rotation center line in the left-right direction.

[0025] The motor 180 is an example of an engagement driving source that inputs rotation to the planetary gear mechanism 170, and is attached, for example, outside the sub-case 117 (see FIG. 6). Here, the motor 180 and the drive shaft 111R are arranged adjacent to each other in the front-rear direction. Thereby, an increase in the size of the drive unit 110 in the vertical direction can be suppressed, and the mountability to the vehicle 1 can be improved. However, the motor 180 is not limited to being attached outside the sub-case 117, and may be housed in the sub-case 117, or may be housed in a motor case attached outside the sub-case 117.

[0026] A worm gear 181 is attached to the drive shaft of the motor 180. The worm gear 181 is an example of a first drive gear that meshes with the external teeth of the ring gear 170R and is driven by the motor 180. Therefore, when the motor 180 is driven, the worm gear 181 rotates and inputs rotation to the ring gear 170R. The planetary gear mechanism 170 rotates a plurality of pinion gears 170P by the input rotation. Here, since the worm gear 181 is used as a mechanism for inputting rotation to the planetary gear mechanism 170, self-locking can be applied by stopping the motor 180. Thereby, the engaged state of the clutch 150 can be maintained without constantly energizing the motor 180, and the fuel efficiency can be improved.

[0027] In the present embodiment, the case where the ring gear 170R synchronizes the pinion gears 170P has been described, but it is not limited thereto. For example, any configuration that synchronizes a plurality of rotating elements such as a belt or a chain can be appropriately applied.

[0028] [Threaded portion] Furthermore, the engagement device 140 has a threaded portion 141 as a configuration for the pinion gear 170P to press the pressing plate 160. The threaded portion 141 includes a male threaded portion 142 which is an example of a threaded portion formed on the engagement output shaft 173, and a female threaded portion 143 which is an example of a threaded portion formed on the pressing plate 160 and engaging with the male threaded portion 142. The male threaded portion 142 is formed on the engagement output shaft 173 and is formed with its rotation center line in the left - right direction.

[0029] Thus, by rotating the engagement output shaft 173 in the first direction R1 which is the right - hand rotation direction when viewed from the right side R, the threaded portion 141 moves the pressing plate 160 toward the clutch 150 in the rotation center line direction (axial direction), and the pressing plate 160 presses the clutch 150 to bring the clutch 150 into an engaged state. That is, the threaded portion 141 presses the pressing plate 160, and the pressing plate 160 pressed by the threaded portion 141 presses the clutch 150. Here, since three engagement output shafts 173 are provided at equal intervals, the pressing plate 160 can be pressed evenly, and a stable pressing force can be obtained. Also, taking the direction opposite to the first direction R1 as the second direction R2, by rotating the engagement output shaft 173 in the second direction R2 which is the left - hand rotation direction when viewed from the right side R, the threaded portion 141 moves the pressing plate 160 away from the clutch 150 in the rotation center line direction (axial direction), releases the pressing of the clutch 150 by the pressing plate 160, and brings the clutch 150 into a released state.

[0030] In this embodiment, the threaded portion 141 is arranged coaxially with the engagement output shaft 173, but it is not limited to this. The rotation center line of the threaded portion may be arranged as a different axis from the rotation center line of the engagement output shaft 173. In this case, for example, a speed - reducing mechanism or the like can be interposed between the engagement output shaft 173 and the threaded portion.

[0031] In addition, in this embodiment, the case where the clutch 150 is pressed when the male screw portion 142 moves in the direction of separating from the female screw portion 143 is described, but the present invention is not limited to this. For example, the screw portion may be configured to press the opposite side of the clutch across the rotation center line direction (axial direction), and the clutch may be pressed when the male screw portion moves in the direction of being drawn into the female screw portion.

[0032] As described above, according to the drive unit 110 of this embodiment, the planetary gear mechanism 170 synchronously rotates a plurality of male screw portions 142 via a plurality of pinion gears 170P, and can press the clutch 150 via the pressing plate 160 by screwing with the female screw portion 143. Therefore, compared with the case where a ball cam or a ball screw is used to press the clutch 150, a large pressing force for pressing the clutch 150 can be obtained by applying the screw portion 141. As a result, the number of friction plates in the clutch 150 can be reduced, so that the occurrence of dragging can be suppressed. In addition, since it is not necessary to increase the size of the motor 180 or the speed reduction mechanism to increase the pressing force, an increase in the size of the device can be suppressed.

[0033] In addition, according to the drive unit 110 of this embodiment, a differential device 113 is applied as a transmission mechanism unit. Therefore, since the driving of the left and right wheels can be connected and disconnected, the rotational resistance of the drive shaft can be reduced during the so-called N-range driving such as coasting.

[0034] In addition, according to the drive unit 110 of this embodiment, in the planetary gear mechanism 170, the ring gear 170R synchronously rotates a plurality of pinion gears 170P, and the rotation from the motor 180 is input to the ring gear 170R. Therefore, the rotation input from the motor 180 can evenly rotate a plurality of pinion gears 170P via the ring gear 170R, and the pressing force at each engagement output shaft 173 can be made uniform.

[0035] Furthermore, in the above-described embodiment, the case where the differential device 113 interposed between the left and right wheels is applied as the transmission mechanism unit has been described, but the present invention is not limited thereto. For example, it may be applied to a switching device provided on a propeller shaft that drivingly connects the front and rear wheels to cut off the transmission of driving force to the front and rear wheels. In addition, the present invention is not limited to being applied to an electric vehicle, and can also be applied to an internal combustion engine vehicle or a hybrid vehicle. For example, it may be applied to a drive unit that uses the driving force transmitted from the internal combustion engine via the propeller shaft as the driving force for running.

[0036] Also, in the above-described embodiment, the case where a plurality of friction plates are applied as the engaging elements of the clutch 150 has been described, but the present invention is not limited thereto. That is, any mechanism that engages by pressing in the direction of the rotation center line (axial direction) may be used. For example, a single friction plate, a dog clutch, or a brake may be applied.

[0037] Also, in the above-described embodiment, the case where the electric motor 180 is applied as the driving source for engagement has been described, but the present invention is not limited thereto. For example, a hydraulic pressure using oil may be used as the driving source for engagement.

[0038] Also, in the above-described embodiment, the screwed portion is a male screw portion and the screwed portion is a female screw portion, but the present invention is not limited thereto. For example, the screwed portion may be a female screw portion and the screwed portion may be a male screw portion, and a female screw portion may be provided on the engagement output shaft 173 and a male screw portion may be formed on the pressing plate 160. In addition, since there are a plurality of pinion gears 170P, in some of the pinion gears 170P, the screwed portion may be a male screw portion and the screwed portion may be a female screw portion, and in other pinion gears 170P, the screwed portion may be a female screw portion and the screwed portion may be a male screw portion.

[0039] <Second Embodiment> Next, the drive unit 210 of the second embodiment of the present disclosure will be described in detail with reference to FIG. 3. In this embodiment, the planetary gear mechanism 270 of the engagement device 240 has a sun gear 270S without using a ring gear, and the rotation is input to the pinion gear 270P, which is different in configuration from the first embodiment. However, since the other configurations are the same as those of the first embodiment, the same reference numerals will be used and the detailed description will be omitted.

[0040] The engagement device 240 of this embodiment has a planetary gear mechanism 270 that can press the pressing plate 160. The planetary gear mechanism 270 includes a sun gear 270S and a carrier that rotatably supports a plurality of pinion gears 270P that mesh with the sun gear 270S. The sun gear 270S has an annular shape and is rotatably supported by the sub-cover 185. The sun gear 270S is an example of a meshing rotation element having internal teeth that mesh with a plurality of pinion gears 270P, and the plurality of pinion gears 270P rotate synchronously.

[0041] In this embodiment, the carrier is constituted by the sub-cover 185. Therefore, the carrier is fixed without rotating. In this planetary gear mechanism 270, since the revolution of the pinion gear 270P is fixed by the sub-cover 185 which is the carrier, the pinion gear 270P rotates on its own axis at a fixed position due to the rotation of the sun gear 270S. That is, the pinion gear 270P is an example of an output rotation element whose revolution is fixed. On the left side L of each pinion gear 270P, an engagement output shaft 173 that is drivingly connected to the pinion gear 270P is provided.

[0042] A worm gear 181 is attached to the drive shaft of the motor 180. The worm gear 181 is an example of a second drive gear that meshes with at least one pinion gear 270P and is driven by the motor 180. Therefore, when the motor 180 is driven, the worm gear 181 rotates and inputs rotation to the pinion gear 270P. The planetary gear mechanism 170 rotates a plurality of pinion gears 270P by the input rotation. That is, in the first embodiment, the ring gear 170R was used to synchronize the plurality of pinion gears 170P, but in this embodiment, the sun gear 270S is used. Also, in the first embodiment, the rotation of the worm gear 181 was input to the ring gear 170R, but in this embodiment, it is input to at least one pinion gear 270P.

[0043] As described above, according to the drive unit 210 of the present embodiment, only the configuration of the planetary gear mechanism 270 of the engagement device 240 is different and the rotation element input with rotation from the worm gear 181 is different, and the effects of the other first embodiment are applied as they are. That is, the planetary gear mechanism 270 can synchronously rotate a plurality of male screw portions 142 via a plurality of pinion gears 270P and press the clutch 150 via the pressure plate 160 by screwing with the female screw portion 143. For this reason, a large pressing force for pressing the clutch 150 can be obtained by applying the screw portion 141 as compared with the case of using a ball cam or a ball screw for pressing the clutch 150. As a result, the number of friction plates in the clutch 150 can be reduced, and the occurrence of dragging can be suppressed. Also, since it is not necessary to increase the size of the motor 180 or the speed reduction mechanism in order to increase the pressing force, an increase in the size of the device can be suppressed.

[0044] Also, according to the drive unit 210 of the present embodiment, the sun gear 270S synchronously rotates a plurality of pinion gears 270P in the planetary gear mechanism 270, and the rotation from the motor 180 is input to the pinion gear 270P. Therefore, the outer diameter of the planetary gear mechanism 270 can be reduced by eliminating the need for a ring gear, and weight reduction can also be achieved.

[0045] <Embodiment 3> Next, the drive unit 310 according to the third embodiment of the present disclosure will be described in detail with reference to FIGS. 4 to 6. In this embodiment, the configuration is different from that of the first embodiment in that the brake 350 of the engagement device 340 is arranged coaxially with the rotor shaft 318. However, since the other configurations are the same as those of the first embodiment, the same reference numerals are used and the detailed description is omitted. FIG. 5 is a schematic side view showing the drive unit 310, FIG. 4 is a cross-sectional view taken along line A-A of FIG. 5, and FIG. 6 is a cross-sectional view taken along line B-B of FIG. 5.

[0046] The vehicle is, for example, an electric vehicle equipped with a power transmission device, and roughly includes an ECU 2 which is a control unit, a drive unit 310 on the front wheel side, left and right front wheels 3L, 3R which are drivingly connected to the drive unit 310 via left and right drive shafts 311L, 311R, a drive unit on the rear wheel side, and left and right rear wheels 4L, 4R which are drivingly connected to the drive unit via left and right drive shafts. In this embodiment, the drive shaft 311R on the right side R is an example of an output member drivingly connected to the front wheel 3R which is a wheel.

[0047] The drive unit 310 on the front wheel side is provided with a motor 312 which is a rotary electric machine as a drive source for front wheel drive, and a differential device 313 for front wheels which transmits the rotation of the motor 312 to the left and right front wheels 3L, 3R. Further, an inverter 6 which is connected to the power supply 5 of the vehicle and is controlled by the ECU 2 is connected to the drive unit 310.

[0048] [Drive Unit] The drive unit 310 on the front wheel side will be described with reference to FIG. 4.

[0049] [Configuration of Case] The drive unit 310 has a main case 314 which houses the motor 312, an intermediate plate 315 which partitions the internal space of the main case 314, a sub-case 316 which houses the speed reduction mechanism 321 and the differential device 313, and a cover 317 which closes the opening of the sub-case 316.

[0050] [Motor] The motor 312 is an example of a drive source, and is housed in a space defined by the main case 314 and the middle plate 315, and includes a stator 312a which is a stator fixed to the main case 314, and a rotor 312b which is a rotor that rotates by induction of an embedded magnet by the magnetic force from a coil disposed in the stator 312a. Further, the rotor 312b is fixed so as to rotate integrally with the rotor shaft 318. The rotor shaft 318 is rotatably supported by a bearing 319 with respect to the main case 314 and by a bearing 320 with respect to the middle plate 315. The rotor shaft 318 is an example of an input member that is drivingly connected to the motor 312.

[0051] [Reduction mechanism] A reduction mechanism 321 composed of a planetary gear mechanism is interposed on the power transmission path between the rotor shaft 318 and the differential device 313. The reduction mechanism 321 includes a sun gear 321S fixedly provided on the rotor shaft 318, a ring gear 321R, and a carrier 321C that rotatably supports a pinion gear 321P that meshes with the sun gear 321S and the ring gear 321R. A transmission shaft 323 disposed coaxially with the rotor shaft 318 is integrally attached to the carrier 321C. A transmission gear 326 is fixedly provided on the transmission shaft 323 so as to rotate integrally.

[0052] [Engagement device] Next, an engagement device 340 that switches the speed reduction mechanism 321 between a connected state and a disconnected state will be described. Here, the connected state means a state in which the speed reduction mechanism 321 can transmit the driving force from the rotor shaft 318 to the differential device 313, and the disconnected state means a state in which the speed reduction mechanism 321 idles and cannot transmit the driving force from the rotor shaft 118 to the differential device 313. The engagement device 340 is housed in a space defined by the sub-case 316, the middle plate 315, and the cover 317. The engagement device 340 includes a brake 350, a pressing ring 360 capable of pressing the brake 350, a planetary gear mechanism 370 capable of pressing the pressing ring 360, and a motor 380 (see FIG. 6) that inputs rotation to the planetary gear mechanism 370.

[0053] The brake 350 has a plurality of outer friction plates 351 and a plurality of inner friction plates 352. The outer friction plates 351 are spline-engaged with a spline 316s formed on the inner peripheral side of the sub-case 316. The inner friction plates 352 are spline-engaged with a spline 370s formed on the outer peripheral side of a ring gear 370R described later. An end plate 353 is provided in spline engagement with the spline 370s. The end plate 353 is positioned and fixed with respect to the sub-case 316 toward the left side L. In the present embodiment, the plurality of outer friction plates 351 and the plurality of inner friction plates 352 are an example of engagement elements, and when pressed, they engage to connect the power transmission between the rotor shaft 318 and the drive shaft 311R.

[0054] The pressing ring 360 is an example of a pressing portion, and is a substantially annular member disposed on the right side R coaxial with the brake 350, and can press the brake 3 between itself and the sub-case 316. The pressing ring 360 is supported by the sub-case 316 so as to be movable in the left-right direction (rotation center line direction) by spline engagement.

[0055] The planetary gear mechanism 370 is interposed on the power transmission path between the pressing ring 360 and the motor 380, and is arranged with the rotation center line in the left-right direction. The planetary gear mechanism 370 includes a ring gear 370R and a carrier 370C that rotatably supports a plurality of pinion gears 370P meshing with the ring gear 370R. In the present embodiment, the pinion gears 370P are arranged at three positions at equal intervals every 120 degrees in the rotational direction centered on the rotation center when viewed from the rotation center line direction (see FIG. 5).

[0056] On the left side L of each pinion gear 370P, an engagement output shaft 373 drivingly connected to the pinion gear 370P is provided. The engagement output shaft 373 is arranged with the rotation center line in the left-right direction.

[0057] The motor 380 is an example of an engagement driving source that inputs rotation to the planetary gear mechanism 370, and as shown in FIG. 5, it is arranged on the side portion of the drive shaft 311R. Thereby, it is possible to suppress the motor 380 from protruding in the vertical direction, suppress the enlargement of the drive unit 310 in the vertical direction, and improve the mountability on the vehicle. As shown in FIG. 6, a pinion gear 381 is attached to the drive shaft of the motor 380. The pinion gear 381 meshes with a large-diameter gear 382. The large-diameter gear 382 is provided to rotate integrally with a small-diameter gear 383, and the small-diameter gear 383 meshes with the pinion gear 370P. Therefore, when the motor 180 drives, rotation is input to the pinion gear 370P via the pinion gear 381, the large-diameter gear 382, and the small-diameter gear 383. The planetary gear mechanism 170 rotates the plurality of pinion gears 370P by the input rotation.

[0058] [Threaded portion] Furthermore, as shown in FIG. 4, the engagement device 340 has a threaded portion 341 as a configuration for the pinion gear 370P to press the pressing ring 360. The threaded portion 341 has a male threaded portion 342 which is an example of a threaded portion formed on the engagement output shaft 373, and a female threaded portion 343 which is an example of a threaded portion formed on the pressing ring 360 and screwed onto the male threaded portion 342. The male threaded portion 342 is formed on the engagement output shaft 373 and is formed with the rotation center line in the left - right direction.

[0059] Thus, by rotating the engagement output shaft 373 in the first direction R1, the threaded portion 341 moves the pressing ring 360 toward the brake 350 in the rotation center line direction, and the brake 350 is pressed by the pressing ring 360 to bring the brake 350 into an engaged state. That is, the threaded portion 341 presses the pressing ring 360, and the pressing ring 360 pressed by the threaded portion 341 presses the brake 350. Here, since three engagement output shafts 373 are provided at equal intervals, the pressing ring 360 can be evenly pressed, and a stable pressing force can be obtained. Also, by rotating the engagement output shaft 373 in the second direction R2, the threaded portion 341 moves the pressing ring 360 away from the brake 350 in the rotation center line direction, releases the pressing of the brake 350 by the pressing ring 360, and brings the brake 350 into a released state.

[0060] [Differential device] The differential device 313 is an example of a transmission mechanism provided on the power transmission path between the rotor shaft 118 and the drive shaft 111R. In the present embodiment, the differential device 313 is constituted by, for example, a double pinion type planetary gear mechanism. The differential device 313 includes a sun gear 313S fixedly provided on the drive shaft 311R, a ring gear 313R meshing with the transmission gear 326, a first pinion gear 313P meshing with the sun gear 313S, a second pinion gear (not shown) meshing with the ring gear 313R and the first pinion gear 313P, and a carrier 313C rotatably supporting the first pinion gear 313P and the second pinion gear. That is, in the present embodiment, the differential device 313 includes a sun gear 313S which is a first transmission output member disposed coaxially with the drive shaft 311R and a carrier 313C which is a second transmission output member, and a planetary gear mechanism as a differential mechanism that allows differential of the sun gear 313S and the carrier 313C while transmitting the rotation of the rotor shaft 318 to the sun gear 313S and the carrier 313C.

[0061] The left drive shaft 111L is rotatably supported by a bearing 334 with respect to the cover 317, and an oil seal 335 is provided between the left drive shaft 111L and the cover 317 to suppress oil leakage from the inside of the drive unit 310. The right drive shaft 111R is rotatably supported by a bearing 336 with respect to the sub-case 316 and is rotatably supported by a bearing 337 with respect to the main case 314, and an oil seal 338 is provided between the right drive shaft 111R and the main case 314 to suppress oil leakage from the inside of the drive unit 310.

[0062] As described above, according to the drive unit 310 of the present embodiment, the planetary gear mechanism 370 rotates a plurality of male screw portions 342 synchronously via a plurality of pinion gears 370P, and can press the brake 350 via the pressing ring 360 by screwing with the female screw portion 343. Therefore, as in the first embodiment, compared with the case of using a ball cam or a ball screw to press the brake 350, a large pressing force for pressing the brake 350 can be obtained by applying the screw portion 341. As a result, the number of friction plates in the brake 350 can be reduced, so that the occurrence of dragging can be suppressed. In addition, since it is not necessary to increase the size of the motor 380 or the speed reduction mechanism in order to increase the pressing force, an increase in the size of the device can be suppressed.

[0063] In addition, in the above-described embodiment, the case where the planetary gear mechanism 370 of the engagement device 340 is arranged between the motor 312 and the speed reduction mechanism 321 in the left-right direction has been described, but the present invention is not limited to this. For example, as shown in FIG. 7, the speed reduction mechanism 321 may be arranged between the motor 312 and the planetary gear mechanism 370. Thus, the arrangements of the motor 312, the speed reduction mechanism 321, the engagement device 340, the differential device 313, etc. are not limited to the forms shown in the embodiments.

[0064] <Fourth Embodiment> Next, the drive unit 410 of the fourth embodiment of the present disclosure will be described in detail with reference to FIGS. 8 to 10. In this embodiment, the configuration is different from that of the first embodiment in that an engagement device 440 is interposed between the differential case 427 of the differential device 413 and the drive shaft 411R on the right side R. However, since the other configurations are the same as those of the first embodiment, the same reference numerals are used and the detailed description is omitted. FIG. 9 is a schematic side view showing the drive unit 410, FIG. 8 is a cross-sectional view taken along line A-A of FIG. 9, and FIG. 10 is a cross-sectional view taken along line B-B of FIG. 9.

[0065] The vehicle is, for example, an electric vehicle equipped with a power transmission device, and roughly includes an ECU2 (see FIG. 1) which is a control unit, a drive unit 410 on the front wheel side, left and right front wheels 3L, 3R (see FIG. 1) which are drivingly connected to the drive unit 410 via left and right drive shafts 411L, 411R, a drive unit on the rear wheel side, and left and right rear wheels 4L, 4R (see FIG. 1) which are drivingly connected to the drive unit via left and right drive shafts. In this embodiment, the drive shaft 411R on the right side R is an example of an output member drivingly connected to the front wheel 3R which is a wheel.

[0066] The drive unit 410 on the front wheel side is provided with a motor 412 which is a rotating electric machine as a drive source for front wheel drive, a differential device 413 for the front wheels which transmits the rotation of the motor 412 to the left and right front wheels 3L, 3R, and a switching device 500 which is interposed in the power transmission path between the motor 412 and the differential device 413 and switches and transmits the rotation of the motor 412 to the differential device 413. Further, an inverter 6 which is connected to the power supply 5 of the vehicle and is controlled by the ECU2 is connected to the drive unit 410 (see FIG. 1).

[0067] [Drive Unit] The drive unit 410 on the front wheel side will be described with reference to FIGS. 8 to 10.

[0068] [Configuration of Case] The drive unit 410 has a first case 581 which houses the motor 412, a second case 582 which houses the differential device 413, a first middle plate 583 which partitions the internal spaces of the first case 581 and the second case 582, a first cover 584 which closes the opening of the second case 582, a third case 585 which houses the switching device 500, a second cover 586 which closes the opening of the third case 585, and an outer case 587 which is provided further outside the second cover 586.

[0069] [Motor] The motor 412 is an example of a drive source, and is housed in a space defined by a first case 581 and a first middle plate 583. It has a stator 412a which is a stator fixed to the first case 581, and a rotor 412b which is a rotor that rotates by induction of an embedded magnet by the magnetic force from a coil arranged in the stator 412a. Further, the rotor 412b is fixed so as to rotate integrally with the rotor shaft 418. The rotor shaft 418 is rotatably supported by a bearing 419 with respect to the first case 581 and by a bearing 424 with respect to a first transmission shaft 423 described later. The rotor shaft 418 is an example of an input member that is drivingly connected to the motor 412.

[0070] [Reduction mechanism] A reduction mechanism 421 composed of a planetary gear mechanism is interposed on the power transmission path between the rotor shaft 418 and the differential device 413. The reduction mechanism 421 is housed in a space between a second case 582 and the first middle plate 583. The reduction mechanism 421 includes a sun gear 421S formed on the rotor shaft 418, a ring gear 421R, and a carrier 421C that rotatably supports a pinion gear 421P that meshes with the sun gear 421S and the ring gear 421R. A bearing 422 is provided between the shaft portion of the carrier 421C and the pinion gear 421P, and the pinion gear 421P is rotatably supported with respect to the shaft portion. The carrier 421C is drivingly connected to a tubular first transmission shaft 423 arranged coaxially with the rotor shaft 418. The first transmission shaft 423 has a left shaft portion 423a and a right shaft portion 423b with the carrier 421C sandwiched therebetween in the axial direction. The first transmission shaft 423 is rotatably supported by a bearing 420 with respect to the first middle plate 583 and by a bearing 425 with respect to the second case 582. A transmission gear 426 is fixed to the left shaft portion 423a of the first transmission shaft 423 so as to rotate integrally.

[0071] As shown in Fig. 10, a gear 543 of the second transmission shaft 542 is meshed with the transmission gear 426 via an idler gear 541. The idler gear 541 is rotatably supported by a bearing 545 with respect to a support shaft 544 fixed to the first case 581. The second transmission shaft 542 is rotatably supported by a bearing 546 with respect to the first case 581, and forms a power transmission path between the transmission gear 426 and the switching device 500. Further, a gear 548 of a tubular third transmission shaft 547 arranged coaxially with the second transmission shaft 542 is meshed with the ring gear 421R. The third transmission shaft 547 is rotatably supported by a bearing 549 with respect to the third case 585, and forms a power transmission path between the speed reduction mechanism 421 and the switching device 500. Note that bearings 550 and 551 are interposed between the second transmission shaft 542 and the third transmission shaft 547.

[0072] [Switching device] Next, the switching device 500 that switches the power transmission path with respect to the rotation of the rotor shaft 418 and transmits it to the transmission gear 426 will be described. The switching device 500 is housed in a space defined by the third case 585 and the second cover 586. The switching device 500 includes a clutch drum 501, a clutch 510, a brake 520, and a switching mechanism 530. Further, a motor for switching the switching mechanism 530 is attached to the outer case 587. The clutch drum 501 is integrated coaxially with the third transmission shaft 547 and is rotatably supported by a bearing 502 with respect to the third case 585.

[0073] The clutch 510 is interposed between the clutch drum 501 and the second transmission shaft 542. The clutch 510 has a plurality of outer friction plates 511 and a plurality of inner friction plates 512. The outer friction plates 511 are spline-engaged with a spline 501s formed on the inner peripheral side of the drum portion of the clutch drum 501. The inner friction plates 512 are spline-engaged with a spline 542s formed on the outer peripheral side of the second transmission shaft 542. The plurality of outer friction plates 511 and the plurality of inner friction plates 512 are engaged by being pressed to connect the power transmission between the third transmission shaft 547 and the second transmission shaft 542.

[0074] The brake 520 is interposed between the clutch drum 501 and the second cover 586. The brake 520 has a plurality of outer friction plates 521 and a plurality of inner friction plates 522. The outer friction plates 521 are spline-engaged with the spline 501s of the clutch drum 501. The inner friction plates 522 are spline-engaged with the spline 586s formed on the outer peripheral side of the second cover 586. The plurality of outer friction plates 521 and the plurality of inner friction plates 522 are engaged by being pressed to fix the rotation of the third transmission shaft 547.

[0075] The switching mechanism 530 has a pressing plate 531, a screw member 532, and a motor 533. The pressing plate 531 is disposed coaxially between the clutch 510 and the brake 520 and is capable of selectively pressing the clutch 510 and the brake 520. The pressing plate 531 is supported by a slide bearing 534 so as to be axially slidable without rotating with respect to the second cover 586 and is supported so as to be movable in the left-right direction with respect to the clutch drum 501. The pressing plate 531 presses the brake 520 by moving to the right side R through the leftmost L outer friction plate 521 of the brake 520. A bearing 535 made of, for example, a ball bearing is provided between the pressing plate 531 and the rightmost R outer friction plate 511 of the clutch 510. The pressing plate 531 presses the clutch 510 through the bearing 535 by moving to the left side L.

[0076] The screw member 532 is rotatably supported by a bearing 536 on the second cover 586 coaxially with the clutch 510 and the brake 520. The screw member 532 has a male screw portion 532a. Further, a female screw portion 531a is formed on the pressing plate 531. The male screw portion 532a and the female screw portion 531a are screwed together, and the pressing plate 531 is movable in the left-right direction by the rotation of the screw member 532.

[0077] The screw member 532 is connected to the pinion gear 533P of the motor 533 via the transmission gears 537 and 538. Therefore, when the motor 533 is driven, the screw member 532 rotates, and the clutch 510 or the brake 520 is selectively engaged depending on the rotation direction of the motor 533. When the brake 520 is engaged, since the third transmission shaft 547 is fixed, the ring gear 421R is fixed, and the rotation of the rotor shaft 418 is greatly decelerated and transmitted to the transmission gear 426 without passing through the second transmission shaft 542 via the speed reduction mechanism 421. On the other hand, when the clutch 510 is engaged, the second transmission shaft 542 and the third transmission shaft 547 are fixed, and the rotation of the rotor shaft 418 is transmitted to the transmission gear 426 via the speed reduction mechanism 421, the second transmission shaft 542, and the third transmission shaft 547.

[0078] [Differential device] The differential device 413 is an example of a transmission mechanism portion provided on the power transmission path between the rotor shaft 418 and the drive shaft 411R. The transmission mechanism portion here is a mechanism that transmits power only by gears, for example. The differential device 413 includes a differential case 427, a right side gear 431 which is a first transmission output member arranged coaxially with the drive shaft 411R, a left side gear 432 which is a second transmission output member, and a differential mechanism 413a that allows differential of the side gears 431 and 432 while transmitting the rotation of the rotor shaft 418 to the side gears 431 and 432. The differential mechanism 413a includes a differential ring gear 428 integrated with the differential case 427, and a pinion gear 430 that is rotatably supported by a shaft 429 supported by the differential case 427 and meshes with the side gears 431 and 432. The differential ring gear 428 meshes with the transmission gear 426 and is rotatably supported by a bearing 439 with respect to the first middle plate 583 and by a bearing 438 with respect to the second case 582, respectively. Further, in the present embodiment, a clutch drum 436 is fixed to the differential case 427 so as to rotate integrally.

[0079] The side gear 431 on the left side L is drivingly connected to the drive shaft 411L. The drive shaft 411L is rotatably supported by a bearing 434 with respect to the first case 581, and an oil seal 435 is provided between the drive shaft 411L and the first case 581 to suppress oil leakage from the inside of the drive unit 410. The side gear 432 on the right side R is drivingly connected to the drive shaft 411R. The drive shaft 411R is rotatably supported by a bearing 487 with respect to the first cover 584, and an oil seal 488 is provided between the drive shaft 411R and the first cover 584 to suppress oil leakage from the inside of the drive unit 410. Further, the drive shaft 411R is rotatably supported by a bearing 433 with respect to the differential case 427. The differential device 413 is configured to transmit the rotation of the differential ring gear 428 to the left and right drive shafts 411L and 411R while absorbing the differential rotation of the side gears 431 and 432.

[0080] [Engaging device] Next, the engaging device 440, which is a disconnect mechanism for switching the connection state and the disconnection state between the differential case 427 and the drive shaft 411R, will be described. The engaging device 440 is housed in a space defined by the second case 582 and the first cover 584. The engaging device 440 includes a clutch 450, a pressing plate 460 capable of pressing the clutch 450, a planetary gear mechanism 470 capable of pressing the pressing plate 460, and an electric motor 480 for inputting rotation to the planetary gear mechanism 470.

[0081] The clutch 450 has a plurality of outer friction plates 451 and a plurality of inner friction plates 452. The outer friction plates 451 are spline-engaged with splines 438s formed on the inner peripheral side of the drum portion of the clutch drum 436. The inner friction plates 452 are spline-engaged with splines 411s formed on the outer peripheral side of the large-diameter portion of the drive shaft 411R. An end plate 453 is provided in spline-engagement with the splines 438s. The end plate 453 is positioned and fixed toward the left side L with respect to the clutch drum 436. In the present embodiment, the plurality of outer friction plates 451 and the plurality of inner friction plates 452 are an example of engagement elements, and when pressed, they engage to connect the power transmission between the differential case 427 and the drive shaft 411R.

[0082] The pressing plate 460 is an example of a pressing portion, and is a substantially annular member disposed on the right side R coaxial with the clutch 450, and is capable of pressing the clutch 450 between it and the clutch drum 436. The pressing plate 460 is supported by a plurality of pinion gears 470P of the planetary gear mechanism 470 described later, and is supported so as to be movable in the left-right direction (rotation center line direction). In the present embodiment, a bearing 461 made of, for example, a ball bearing is provided between the pressing plate 460 and the rightmost outer friction plate 451, and the pressing plate 460 presses the clutch 450 via the bearing 461.

[0083] The planetary gear mechanism 470 is interposed on the power transmission path between the pressing plate 460 and the motor 480, and is arranged with its rotation center line in the left-right direction. The planetary gear mechanism 470 includes a sun gear 470S and a carrier that rotatably supports a plurality of pinion gears 470P meshing with the sun gear 470S. In the present embodiment, the pinion gears 470P are arranged at three locations at equal intervals of 120 degrees in the rotational direction centered on the rotation center when viewed from the rotation center line direction (see FIG. 5). The sun gear 470S is an example of a meshing rotation element having external teeth meshing with a plurality of pinion gears 470P, and the plurality of pinion gears 470P rotate synchronously. In the present embodiment, the case where the pinion gears 470P are arranged at three locations at equal intervals has been described, but it is not limited thereto, and they may be arranged at three non-equal intervals, or provided at four or more locations at equal intervals, or provided at four or more non-equal intervals.

[0084] In the present embodiment, the carrier is constituted by the second case 582. Therefore, the carrier is fixed without rotating. The pinion gear 470P is supported by the engagement output shaft 473 so as to rotate integrally with the engagement output shaft 173. In this planetary gear mechanism 470, since the revolution of the pinion gear 470P is fixed by the second case 582 which is the carrier, the plurality of pinion gears 470P rotate at a fixed position while being synchronized by the sun gear S. That is, the pinion gear 470P is an example of an output rotation element whose revolution is fixed.

[0085] On the left side L of each pinion gear 470P, an engagement output shaft 473 drivingly connected to the pinion gear 470P is provided. The engagement output shaft 473 is rotatably supported in a bearing hole of a support plate 582a attached to the second case 582 with its rotation center line in the left-right direction.

[0086] The motor 480 is an example of an engagement driving source that inputs rotation to the planetary gear mechanism 470, and is mounted so as to be exposed outside the second case 582. Here, the motor 480 and the drive shaft 411R are arranged in the front-rear direction in proximity to each other (see FIG. 8). Thereby, an increase in the size of the drive unit 410 in the vertical direction can be suppressed, and the mountability to the vehicle 1 can be improved. However, the motor 480 is not limited to being mounted outside the second case 582, and may be housed in the second case 582, or may be housed in a motor case mounted outside the second case 582.

[0087] A pinion gear 480P is attached to the drive shaft of the motor 480. The pinion gear 480P is connected to the pinion gear 470P of the planetary gear mechanism 470 via a transmission gear 481. Therefore, when the motor 480 is driven, the transmission gear 481 rotates and inputs rotation to the pinion gear 470P. The planetary gear mechanism 470 rotates a plurality of pinion gears 470P by the input rotation.

[0088] [Threaded portion] Furthermore, the engagement device 440 has a threaded portion 441 as a configuration for the pinion gear 470P to press the pressing plate 460. The threaded portion 441 has a male threaded portion 442 which is an example of a threaded portion formed on the engagement output shaft 473, and a female threaded portion 443 which is an example of a threaded portion formed on the pressing plate 460 and screwed into the male threaded portion 442. The male threaded portion 442 is formed on the engagement output shaft 473 and is formed with its rotation center line in the left-right direction.

[0089] By rotating the engagement output shaft 473 in the first direction R1, which is the clockwise direction when viewed from the right side R, the screw portion 441 moves the pressing plate 460 toward the clutch 450 in the rotation center line direction (axial direction), and presses the clutch 450 with the pressing plate 460 to engage the clutch 450. That is, the screw portion 441 presses the pressing plate 460, and the pressing plate 460 pressed by the screw portion 441 presses the clutch 450. Here, since three engagement output shafts 473 are provided at equal intervals, the pressing plate 460 can be evenly pressed, and a stable pressing force can be obtained. Also, the direction opposite to the first direction R1 is defined as the second direction R2. By rotating the engagement output shaft 473 in the second direction R2, which is the counterclockwise direction when viewed from the right side R, the screw portion 441 moves the pressing plate 460 away from the clutch 450 in the rotation center line direction (axial direction), releases the pressing of the clutch 450 by the pressing plate 460, and sets the clutch 450 to the released state.

[0090] In the present embodiment, the screw portion 441 is arranged coaxially with the engagement output shaft 473, but it is not limited thereto. For example, the rotation center line of the screw portion may be arranged as a separate axis from the rotation center line of the engagement output shaft 473. In this case, a speed reduction mechanism or the like can be interposed between the engagement output shaft 473 and the screw portion.

[0091] Also, in the present embodiment, the case where the clutch 450 is pressed when the male screw portion 442 moves in the direction of separating from the female screw portion 443 is described, but it is not limited thereto. For example, the screw portion may be configured to press the opposite side of the clutch sandwiching the rotation center line direction (axial direction), and the clutch may be pressed when the male screw portion moves in the direction of being drawn into the female screw portion.

[0092] As described above, according to the drive unit 410 of the present embodiment, the power transmission between the differential case 427 and the drive shaft 411R can be disconnected by the engagement device 440. Thereby, during normal driving, the power transmission between the differential case 427 and the drive shaft 411R is disconnected, and the differential of the side gears 431 and 432 by the differential device 413 is allowed. For example, when performing control that does not allow the differential of the side gears 431 and 432 during extreme slip or the like, the differential case 427 and the drive shaft 411R can be connected to perform differential lock.

[0093] According to the drive unit 410 of the present embodiment, in addition to the above-described effects, the effects of the first embodiment are applied as they are. That is, the planetary gear mechanism 470 can rotate a plurality of male screw portions 442 synchronously via a plurality of pinion gears 470P and press the clutch 450 via the pressing plate 460 by screwing with the female screw portion 443. Therefore, compared with the case where a ball cam or a ball screw is used to press the clutch 450, a large pressing force for pressing the clutch 450 can be obtained by applying the screw portion 441. Thereby, the number of friction plates in the clutch 450 can be reduced, and the occurrence of dragging can be suppressed. Further, since it is not necessary to increase the size of the motor 480 or the reduction mechanism in order to increase the pressing force, an increase in the size of the device can be suppressed.

Explanation of Signs

[0094] 3R... Front wheel (wheel), 111R, 316R, 411R... Drive shaft (output member), 112, 312, 412... Motor (drive source), 113, 313, 413... Differential device (transmission mechanism part), 113a, 413a... Differential mechanism, 118, 318, 418... Rotor shaft (input member), 131, 431... Side gear (first transmission output member), 132, 432... Side gear (second transmission output member), 140, 240, 340, 440... Engagement device, 141, 341, 441... Threaded part, 142, 342, 442... Male threaded part (threaded engagement part), 143, 343, 443... Female threaded part (threaded part to be engaged), 151, 351, 451... Outer friction plate (engagement element), 152, 352, 452... Inner friction plate (engagement element), 160, 460... Pressing plate (pressing part), 170, 370, 470... Planetary gear mechanism, 170P, 270P, 470P... Pinion gear (output element), 170R... Ring gear (meshing rotating element), 173, 373, 473... Engagement output shaft, 180, 380, 480... Motor (engagement drive source), 181... Worm gear (first drive gear, second drive gear), 270S, 470S... Sun gear (meshing rotating element), 313C... Carrier (second transmission output member), 313S... Sun gear (first transmission output member), 360... Pressing ring (pressing part)

Claims

1. An input member drivingly connected to a drive source; An output member drivingly connected to the wheels; a transmission mechanism provided on a power transmission path between the input member and the output member; an engagement device having an engagement element that is pressed to engage and connect the power transmission between the input member and the output member, The engagement device is A pressing portion that presses the engaging element; a planetary gear mechanism including a plurality of output rotating elements and meshing rotating elements meshing with the plurality of output rotating elements, the planetary gear mechanism rotating the plurality of output rotating elements by input rotation; an engagement drive source for inputting rotation to the planetary gear mechanism; an engagement output shaft drivingly connected to each of the plurality of output rotating elements; a threaded portion including a screw portion formed on the engagement output shaft and a screwed portion formed on the pressing portion and screwed into the screw portion, By rotating the engagement output shaft in a first direction, the threaded portion moves the pressing portion toward the engagement element in the direction of the rotation center line, and the pressing portion presses the engagement element to bring the engagement element into an engaged state. A power transmission device in which, by rotating the engagement output shaft in a second direction opposite to the first direction, the screw portion moves the pressing portion away from the engagement element in the direction of the rotation center line, thereby releasing the pressing portion against the engagement element and placing the engagement element in a released state.

2. the transmission mechanism portion is a differential device including a first transmission output member and a second transmission output member arranged coaxially with the output member, and a differential mechanism that allows differential movement of the first transmission output member and the second transmission output member while transmitting rotation of the input member to the first transmission output member and the second transmission output member, 2. The power transmission device according to claim 1, wherein the engagement element is provided on a power transmission path between the differential mechanism and the output member.

3. the meshing rotating element is a ring gear having internal teeth meshing with the plurality of output rotating elements; the plurality of output rotation elements are a plurality of pinion gears whose revolution is fixed, 2. The power transmission device according to claim 1, wherein the engagement device includes a first drive gear that meshes with external teeth of the ring gear and is driven by the engagement drive source.

4. the meshing rotating element is a sun gear having external teeth meshing with the plurality of output rotating elements, the plurality of output rotation elements are a plurality of pinion gears whose revolution is fixed, 2. The power transmission device according to claim 1, wherein the engagement device includes a second drive gear that meshes with at least one of the plurality of output rotary elements and is driven by the engagement drive source.

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