Power transmission device

Abstract

To reduce the size of a power transmission device.SOLUTION: A power transmission device includes: a gear 52P for first engagement which is rotated on a rotation axis by a motor; and a first pressing shaft 51 which is movably arranged in an axial direction and selectively presses a first brake B1 and a second brake B2. The first pressing shaft 51 rotates the gear 52P for first engagement in a first direction R1 from a non-engagement state in which each of the brakes B1 and B2 is not engaged, thereby moves the first pressing shaft 51 toward the first brake B1 by a first screw part 62, presses the first brake B1 and is brought into a first engagement state in which the first brake B1 is engaged, rotates the gear 52P for first engagement in a second direction R2 from the first engagement state, thereby moves the first pressing shaft 51 by the first screw part 62 so as to be separated from the first brake B1 in the axial direction, and releases pressing of the first brake B1 and is brought into the non-engagement 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. [Background technology]

[0002] Conventionally, a transmission mounted on a vehicle has been known that changes gears by changing the engagement state of rotating elements of a planetary gear mechanism to which driving force is input (see Patent Document 1). This transmission has a clutch and a brake as friction engagement elements, and changes gears by selectively engaging these clutches and brakes to switch the power transmission path. This transmission also has a pressing member that selectively presses the clutch and brake in the axial direction to engage them, and the engagement state of the clutch and brake is switched by moving the pressing member in either direction in the axial direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 176579 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the transmission described in Patent Document 1, a clutch and a brake are used as friction engagement elements, so one of the clutch and the brake rotates relative to the pressing member. For example, if the pressing member does not rotate relative to the case, the clutch rotates relative to the pressing member, so a thrust bearing that receives pressing force while allowing rotation in the axial direction must be provided between the pressing member and the clutch, which leads to an increase in the size of the device.

[0005] Therefore, an object of the present invention is to provide a power transmission device that can be made smaller. [Means for solving the problem]

[0006] A power transmission device according to one aspect of the present invention has an input section drivably connected to a drive source, an output section drivably connected to a wheel, a first rotating element, and a second rotating element, and includes a gear mechanism capable of forming a first power transmission path drivably connecting the input section and the output section, and a second power transmission path drivably connecting the input section and the output section and different from the first power transmission path, a case accommodating the gear mechanism, a first brake capable of forming the first power transmission path by making the first rotating element non-rotatable relative to the case, and a brake for connecting the second rotating element to the case. a second brake that is non-rotatable relative to the first brake and the second brake to form the second power transmission path; an engagement drive source; an engagement rotation member that is rotated on a rotation axis by the engagement drive source; a pressing member that is arranged movably in the axial direction of the rotation axis and that selectively presses the first brake and the second brake; and a threaded portion that has a screw-engaging portion formed on the pressing member and a threaded portion that is formed on the engagement rotation member and that screws into the screw-engaging portion, and By rotating the rolling member in a first direction, the threaded portion moves the pressing member toward the first brake in the axial direction, causing the pressing member to press the first brake, thereby establishing a first engaged state in which the first brake is engaged; by rotating the engaging rotating member in a second direction opposite to the first direction from the first engaged state, the threaded portion moves the pressing member away from the first brake in the axial direction, thereby releasing the pressing of the first brake by the pressing member, thereby establishing the disengaged state; by rotating the engaging rotating member in the second direction from the disengaged state, the threaded portion moves the pressing member toward the second brake in the axial direction, causing the pressing member to press the second brake, thereby establishing a second engaged state in which the second brake is engaged; and by rotating the engaging rotating member in the first direction from the second engaged state, the threaded portion moves the pressing member away from the second brake in the axial direction, thereby releasing the pressing of the second brake by the pressing member, thereby establishing the disengaged state. [Effects of the Invention]

[0007] The power transmission device can be made smaller. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic explanatory diagram showing the overall configuration of a vehicle according to a first embodiment. [Figure 2] 5 is a cross-sectional view taken along line AA in FIG. 4, showing the drive unit according to the first embodiment. [Figure 3] 5 is a cross-sectional view taken along line BB in FIG. 4, showing the drive unit according to the first embodiment. [Figure 4] FIG. 2 is a schematic side view showing the drive unit according to the first embodiment. [Figure 5] FIG. 10 is an explanatory diagram showing a drive unit according to a second embodiment. [Figure 6] FIG. 10 is an explanatory diagram showing an engagement mechanism of a drive unit in a second embodiment. [Figure 7] 10 is an explanatory diagram showing an engagement mechanism of a drive unit in a third embodiment. FIG. [Figure 8] FIG. 10 is an explanatory view showing an engagement mechanism of a drive unit in a fourth embodiment. [Figure 9] FIG. 11 is an explanatory view showing an engagement mechanism of a drive unit in a fifth embodiment. [Figure 10] FIG. 13 is an explanatory diagram showing an engagement mechanism of a drive unit in a sixth embodiment. [Figure 11] FIG. 13 is an explanatory view showing an engagement mechanism of a drive unit in a seventh embodiment. [Figure 12] FIG. 13 is an explanatory diagram showing an engagement mechanism of a drive unit in an eighth embodiment. [Figure 13] FIG. 13 is an explanatory diagram showing an engagement mechanism of a drive unit in a ninth embodiment. [Figure 14] FIG. 23 is an explanatory diagram showing an engagement mechanism of a drive unit according to a tenth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment A power transmission device according to a first embodiment will be described below with reference to FIGS. 1 to 4. First, a schematic configuration of a vehicle 1 equipped with a power transmission device according to this embodiment will be described with reference to FIG. 1. As shown in FIG. 1, the vehicle 1 travels forward in a direction F, and the left and right directions are indicated as right R and left L in the drawing. The vehicle 1 is, for example, an electric vehicle equipped with a power transmission device, and roughly includes an ECU 2 serving as a control unit, a front-wheel drive unit 10, left and right front wheels 3L, 3R drivingly connected to the drive unit 10 via left and right drive shafts 11L, 11R, a rear-wheel drive unit 90, and left and right rear wheels 4L, 4R drivingly connected to the drive unit 90 via left and right drive shafts 91L, 91R. In this embodiment, the left and right drive shafts 11L, 11R are an example of an output unit drivingly connected to the front wheels 3L, 3R.

[0010] The front-wheel (front) drive unit 10 includes a motor 12 (MG1), a rotating electric machine (motor-generator) serving as a drive source for front-wheel drive, a transmission 13 that changes the speed of the rotation output from the motor 12, and a front-wheel differential 14 that transmits the rotation, the speed of which has been changed by the transmission 13, to the left and right front wheels 3L, 3R. The drive unit 10 also includes an inverter 6 that is connected to a power source 5 (BATTERY) of the vehicle 1 and controlled by the ECU 2. Similarly, the rear-wheel (rear) drive unit 90 includes a motor 92 (MG2), a rotating electric machine (motor-generator) serving as a drive source for rear-wheel drive, a transmission 93 that changes the speed of the rotation output from the motor 92, and a rear-wheel differential 94 that transmits the rotation of the transmission 93 to the left and right rear wheels 4L, 4R. The drive unit 90 also includes an inverter 7 that is connected to the power source 5 of the vehicle 1 and controlled by the ECU 2.

[0011] The inverter 6 of the drive unit 10 is PWM controlled by the ECU 2, and powers the motor 12 with power from the power supply 5, or regenerates power from the motor 12 to charge the power supply 5. Similarly, the inverter 7 of the drive unit 90 is PWM controlled by the ECU 2, and powers the motor 92 with power from the power supply 5, or regenerates power from the motor 92 to charge the power supply 5.

[0012] [Drive unit] The front-wheel drive unit 10 will be described using Figures 2 to 4. Note that the rear-wheel drive unit 90 has the same configuration as the front-wheel drive unit 10 described below, and so a detailed description will be omitted. Figure 2 is a cross-sectional view taken along line AA in Figure 4, Figure 3 is a cross-sectional view taken along line BB in Figure 4, and Figure 4 is a schematic side view showing the drive unit 10. Note that in the following description, the left-right direction will be referred to as the axial direction.

[0013] [Case Configuration] The drive unit 10 has a case 15 that houses the motor 12, the transmission 13, and the differential 14, a middle plate 16 that divides the internal space of the case 15, and a cover 17 that closes the opening of the case 15.

[0014] [Motor] Motor 12 is an example of a drive source, and is housed in a space defined by case 15 and intermediate plate 16. It has a stator 12a, which is a fixed part, fixed to case 15, and a rotor 12b, which is a rotor that rotates when embedded magnets are induced by magnetic force from coils arranged in stator 12a. Rotor 12b is fixed to rotor shaft 18 so as to rotate integrally with it. Rotor shaft 18 is rotatably supported by bearings 19 on case 15 and by bearings 20 on intermediate plate 16. Rotor shaft 18 is an example of an input section that is drivingly connected to motor 12.

[0015] [Transmission] The transmission 13 is disposed on the power transmission path between the rotor shaft 18 and the differential device 14. The transmission 13 is an example of a power transmission device, and is housed in a space defined by a case 15, an intermediate plate 16, and a cover 17. The transmission 13 has a gear mechanism 40 having a planetary gear mechanism, and an engagement mechanism 50 capable of fixing some of the rotating elements of the gear mechanism 40.

[0016] [Gear mechanism] The gear mechanism 40 has a first planetary gear mechanism 41 and a second planetary gear mechanism 42, and is capable of forming a first power transmission path by the first planetary gear mechanism 41 and a second power transmission path different from the first power transmission path by the second planetary gear mechanism 42. In this embodiment, the first power transmission path and the second power transmission path both form power transmission paths that drivingly connect the rotor shaft 18 and the drive shafts 11L, 11R, but have different gear ratios, and speed is changed by switching between the first power transmission path and the second power transmission path.

[0017] The first planetary gear mechanism 41 includes a first sun gear 41S fixed to the rotor shaft 18, a first ring gear 41R which is an example of a first rotating element, and a first carrier 41C which rotatably supports a plurality of pinion gears 41P which mesh with the first sun gear 41S and the first ring gear 41R. The first carrier 41C is rotatably supported by a bearing 21 relative to the intermediate plate 16. A transmission shaft 43 which is disposed coaxially with the rotor shaft 18 is attached integrally to the first carrier 41C. The transmission shaft 43 is rotatably supported by a bearing 22 relative to the cover 17, and a transmission gear 44 is fixed to rotate integrally with the transmission shaft 43. The second planetary gear mechanism 42 is composed of a second sun gear 42S fixed to the rotor shaft 18, a second ring gear 42R which is an example of a second rotating element, and a second carrier 42C which rotatably supports a plurality of pinion gears 42P which mesh with the second sun gear 42S and the second ring gear 42R.

[0018] The diameter of second sun gear 42S is larger than the diameter of first sun gear 41S. The diameter of pinion gear 42P is smaller than the diameter of pinion gear 41P. Second carrier 42C is integrated with first carrier 41C. The outer diameter of second ring gear 42R is equal to the outer diameter of first ring gear 41R.

[0019] [Engagement mechanism] Next, the engagement mechanism 50 that switches the power transmission path formed by the gear mechanism 40 between a first power transmission path and a second power transmission path will be described. In this embodiment, the engagement mechanism 50 performs two-speed shifting by switching the power transmission path formed by the gear mechanism 40 between the first power transmission path and the second power transmission path. The engagement mechanism 50 has a first brake B1, a second brake B2, a first pressing shaft 51 that is an example of a pressing member that can selectively press the first brake B1 and the second brake B2, a planetary gear mechanism 52 that can move the first pressing shaft 51 in the axial direction, and a motor 53 (see FIG. 3) that inputs rotation to the planetary gear mechanism 52.

[0020] Inside the case 15, a fixed member 23 is fixed to the case 15 between the intermediate plate 16 and the cover 17 in the axial direction. The fixed member 23 has a first member 24 and a second member 25, which are integrally formed by abutting each other in the axial direction. The fixed member 23 is fixed to the inner circumferential surface of the case 15 in the axial and rotational directions. In the present embodiment, the fixed member 23 is formed by integrally forming the first member 24 and the second member 25, but this is not limited thereto, and the first member 24 and the second member 25 may be formed as a single member. In the present embodiment, the fixed member 23 attached to the case 15 supports the first outer friction plate 71 and the second outer friction plate 73 (described later) so as not to rotate relative to each other. However, this is not limited thereto, and the case 15 may have a spline and directly support the first outer friction plate 71 and the second outer friction plate 73 so as not to rotate relative to each other.

[0021] The first brake B1 has a plurality of first outer friction plates 71 (first friction plates) and a plurality of first inner friction plates 72 (second friction plates). The first outer friction plates 71 are spline-engaged with splines 24s formed on the inner circumferential side of the first member 24 of the fixed member 23, and are supported and arranged so as to be non-rotatable relative to the case 15. The first inner friction plates 72 are spline-engaged with splines 41s formed on the outer circumferential side of the first ring gear 41R, and are arranged so as to be non-rotatable relative to the first ring gear 41R. The plurality of first outer friction plates 71 and the plurality of first inner friction plates 72 are arranged alternately in the axial direction. The first outer friction plate 71 located on the leftmost side L of the first outer friction plates 71 is positioned and fixed toward the left side L with respect to a flange portion 24a protruding on the inner circumferential side of the first member 24. The first brake B1 can form a first power transmission path in the gear mechanism 40 by engaging the first ring gear 41R with the case 15 via the fixed member 23.

[0022] The second brake B2 has a plurality of second outer friction plates 73 (third friction plates) and a plurality of second inner friction plates 74 (fourth friction plates). The second outer friction plates 73 are spline-engaged with splines 25s formed on the inner circumferential side of the second member 25 of the fixed member 23, and are supported and arranged so as to be non-rotatable relative to the case 15. The second inner friction plates 74 are spline-engaged with splines 42s formed on the outer circumferential side of the second ring gear 42R, and are arranged so as to be non-rotatable relative to the second ring gear 42R. The plurality of second outer friction plates 73 and the plurality of second inner friction plates 74 are arranged alternately in the axial direction. The second outer friction plate 73 located on the rightmost side R of the second outer friction plates 73 is positioned and fixed toward the right side R with respect to a flange portion 25a protruding on the inner circumferential side of the second member 25. The second brake B2 can form a second power transmission path in the gear mechanism 40 by engaging the second ring gear 42R with the case 15 via the fixed member 23.

[0023] The planetary gear mechanism 52 includes a sun gear 52S and a carrier 52C that rotatably supports a first engagement gear 52P, a second engagement gear 152P, and a third engagement gear 252P (see FIG. 4) that mesh with the sun gear 52S as a plurality of pinion gears, and is disposed with its axial direction aligned in the left-right direction. The sun gear 52S has external teeth 52Sa that mesh with the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P. The first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P are examples of engaging rotating members, and are disposed between the first brake B1 and the second brake B2 in the axial direction of their rotation axes, and are disposed inside the fixed member 23. In this embodiment, the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P are arranged at three locations, equally spaced apart every 120 degrees in the rotational direction around the center of rotation, when viewed from the axial direction (see Figure 4).

[0024] Since the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P have the same configuration, the following will describe in detail the first engagement gear 52P, which is an example of a first engagement rotation member. The carrier 52C that supports the first engagement gear 52P has a first circular member 52Ca and a second circular member 52Cb that is arranged on the right side R and axially faces the first circular member 52Ca. The first circular member 52Ca and the second circular member 52Cb have through holes that penetrate in the axial direction at positions that support the first engagement gear 52P, and the first pressing shaft 51 passes through this through hole. The first circular member 52Ca is supported by an end portion on the right side R of the first member 24 of the fixed member 23, and its rotation and movement on the left side L and radial directions are restricted. The second circular member 52Cb is supported by an end portion on the left side L of the second member 25 of the fixed member 23, and its rotation and movement to the right side R and in the radial direction are restricted. In other words, the carrier 52C is fixed so as not to revolve.

[0025] In the axial direction, an annular first thrust bearing 54 centered on the first rotation axis of the first engagement gear 52P is interposed between the first circular member 52Ca and the first engagement gear 52P, and an annular second thrust bearing 55 centered on the first rotation axis of the first engagement gear 52P is interposed between the second circular member 52Cb and the first engagement gear 52P. As a result, the first engagement gear 52P is a first pinion gear whose revolution is fixed, and is supported by the carrier 52C so that it only rotates on its own axis without revolving.

[0026] The first pressing shaft 51 is a shaft-shaped member that is disposed movably in the axial direction of the first rotation axis of the first engagement gear 52P, has its longitudinal direction in the axial direction, and selectively presses the first brake B1 and the second brake B2. The first pressing shaft 51 is rotatably inserted into an axial through-hole formed in the center of the first engagement gear 52P. A left end L of the first pressing shaft 51 is fixed in the axial direction to a first pressing member 56 that is annular and centered on the sun gear 41S by press-fitting or the like, and a right end R of the first pressing shaft 51 is fixed in the axial direction to a second pressing member 57 that is annular and centered on the sun gear 42S by press-fitting or the like.

[0027] In this embodiment, the first pressing shaft 51 selectively presses the first brake B1 and the second brake B2, but this is not limited to the first pressing shaft 51 directly pressing the first brake B1 and the second brake B2, and the first pressing shaft 51 may press the first brake B1 and the second brake B2 via the first pressing member 56 and the second pressing member 57, respectively.

[0028] 2, the engagement mechanism 50 has a first screw portion 62 as a configuration for the first engagement gear 52P to move the first pressing shaft 51. The first screw portion 62 is an example of a screw portion, and has a first male screw portion 63 which is an example of a first screw-engaging portion (screw portion) formed on the first pressing shaft 51, and a first female screw portion 64 which is an example of a first screwed portion (screwed portion) formed on the first engagement gear 52P and screws into the first male screw portion 63. The first male screw portion 63 is formed on the first pressing shaft 51, and is formed with its rotation axis in the left-right direction.

[0029] Next, the second engagement gear 152P and its surrounding configuration will be described with reference to Figure 3. Note that a description of configurations similar to those of the first engagement gear 52P will be omitted. The second engagement gear 152P is an example of a second engagement rotating member, rotated on a second rotation axis by the motor 53, and disposed between the first brake B1 and the second brake B2 in the axial direction of the second rotation axis. The second pressing shaft 151 is rotatably inserted into an axial through-hole formed in the center of the second engagement gear 152P, disposed movably in the axial direction of the second rotation axis, and selectively presses the first brake B1 or the second brake B2. The second screw portion 162 has a second male screw portion 163 which is an example of a second screw-engaging portion (screw-engaging portion) formed on the second pressing shaft 151, and a second female screw portion 164 which is an example of a second screwed portion (screwed portion) formed on the second engaging gear 152P and which screws into the second male screw portion 163.

[0030] The second engagement gear 152P is rotatably supported by the carrier 52C, which is fixed so as not to revolve. Therefore, the second engagement gear 152P is a second pinion gear whose revolution is fixed, and by being supported by the carrier 52C, it only rotates on its own axis without revolving.

[0031] Motor 53 is an example of an engagement drive source that inputs rotation to planetary gear mechanism 52, and is disposed on the side of drive shaft 11R as shown in Fig. 4. This prevents motor 53 from protruding in the vertical direction, prevents the drive unit 10 from becoming larger in the vertical direction, and improves mountability on vehicle 1. In other words, motor 53 is disposed outside fixed member 23 and outside case 15.

[0032] As shown in FIG. 3 , a pinion gear 58 is provided on the drive shaft of the motor 53. The pinion gear 58 is meshed with a large-diameter gear 59. The large-diameter gear 59 is provided to rotate integrally with a small-diameter gear 61, which has a diameter smaller than that of the large-diameter gear 59, via a transmission shaft 60, and the small-diameter gear 61 is meshed with a second engagement gear 152P. Therefore, when the motor 53 is driven, rotation is input from the second engagement gear 152P to the planetary gear mechanism 52 via the pinion gear 58, the large-diameter gear 59, the transmission shaft 60, and the small-diameter gear 61. In the planetary gear mechanism 52, the input rotation is transmitted to the first engagement gear 52P and the third engagement gear 252P via the sun gear 52S, causing the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P to rotate on their respective rotation axes. That is, the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P are driven synchronously by the driving of the motor 53.

[0033] Here, the small-diameter gear 61 is an example of a transmission member and is drivingly connected to the motor 53 and the second engagement gear 152P to transmit the rotational driving force from the motor 53 to the second engagement gear 152P. The fixed member 23 has a through-hole 23a that penetrates from the inside to the outside near the second engagement gear 152P. The small-diameter gear 61 is drivingly connected to the second engagement gear 152P via the through-hole 23a. This allows the driving force that rotates the second engagement gear 152P, which is disposed between the first brake B1 and the second brake B2 on the inner circumferential side of the fixed member 23, to be input from the outer circumferential side of the fixed member 23. This simplifies the mechanism compared to a configuration in which rotation is input from the inner circumferential sides of the first brake B1 and the second brake B2, improving the assembly of the drive unit 10. Furthermore, instead of using two driving sources to selectively engage and disengage the two brakes, a single driving source can be used.

[0034] [Differential device] The differential 14 is provided on a power transmission path between the rotor shaft 18 and the drive shafts 11L, 11R. In this embodiment, the differential 14 is configured, for example, by a double-pinion planetary gear mechanism. The differential 14 includes a sun gear 14S fixed to the drive shaft 11R, a ring gear 14R meshing with the transmission gear 44, a first pinion gear 14P meshing with the sun gear 14S, a second pinion gear (not shown) meshing with the ring gear 14R and the first pinion gear 14P, and a carrier 14C connected to the drive shaft 11L and rotatably supporting the first pinion gear 14P and the second pinion gear. That is, in this embodiment, the differential device 14 has a sun gear 14S and a carrier 14C arranged coaxially with the drive shafts 11L, 11R, and a planetary gear mechanism as a differential mechanism that transmits the rotation of the rotor shaft 18 to the sun gear 14S and the carrier 14C while allowing differential movement of the sun gear 14S and the carrier 14C.

[0035] The drive shaft 11L on the left side L is rotatably supported by a bearing 65 relative to the cover 17, and an oil seal 66 is provided between the cover 17 and the drive shaft 11L to prevent oil leakage from inside the drive unit 10. The drive shaft 11R on the right side R is rotatably supported by a bearing 67 relative to the case 15, and an oil seal 68 is provided between the case 15 and the drive shaft 11L to prevent oil leakage from inside the drive unit 10.

[0036] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. Here, the rotation of the first engagement gear 52P is described as an example, but the same applies to the second engagement gear 152P and the third engagement gear 252P.

[0037] From a disengaged state in which the first pressing shaft 51 does not engage the first brake B1 or the second brake B2, rotating the first engagement gear 52P in the first direction R1 causes the first thread portion 62 to move the first pressing shaft 51 to the left side L in the axial direction toward the first brake B1, causing the first pressing shaft 51 to press the first brake B1 and place the first brake B1 in the first engaged state. Then, from the first engaged state in which the first brake B1 is engaged, rotating the first engagement gear 52P in a second direction R2 opposite to the first direction R1 causes the first thread portion 62 to move the first pressing shaft 51 axially away from the first brake B1, releasing the pressure of the first pressing shaft 51 on the first brake B1 and placing the first brake B1 and the second brake B2 in the disengaged state.

[0038] On the other hand, by rotating the first engagement gear 52P in the second direction R2 from a disengaged state of the first brake B1 and the second brake B2, the first thread portion 62 moves the first pressing shaft 51 axially toward the second brake B2, causing the first pressing shaft 51 to press the second brake B2 and place the second brake B2 in the second engaged state. Then, by rotating the first engagement gear 52P in the first direction R1 from the second engaged state in which the second brake B2 is engaged, the first thread portion 62 moves the first pressing shaft 51 axially away from the second brake B2, releasing the pressure of the first pressing shaft 51 on the second brake B2 and placing the first brake B1 and the second brake B2 in the disengaged state.

[0039] As described above, according to the drive unit 10 of this embodiment, the first brake B1 and the second brake B2 can be selectively placed in an engaged state by moving the first pressing shaft 51. Here, in a drive unit that switches the power transmission path by selectively pressing two engagement elements with a pressing member, if there is relative rotation between the engagement elements and the pressing member, it was necessary to provide a thrust bearing between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the first pressing shaft 51, so there is no need to provide such a thrust bearing, and the drive unit 10 can be made more compact.

[0040] Furthermore, according to the drive unit 10 of this embodiment, the first screw portion 62 is used as a mechanism for converting rotation of the first engagement gear 52P into axial movement of the first pressing shaft 51. Therefore, a larger pressing force can be obtained compared to when a ball cam or ball screw is used to press the first brake B1 and the second brake B2. This allows the number of friction plates in the first brake B1 and the second brake B2 to be reduced, thereby suppressing the occurrence of drag. Furthermore, since there is no need to increase the size of the motor 53 or the engagement mechanism 50 to increase the pressing force, the size of the drive unit 10 can be suppressed.

[0041] Furthermore, according to the drive unit 10 of this embodiment, the motor 53 and the second engagement gear 152P are drivingly connected via the through-hole 23a of the fixed member 23. As a result, the drive force for rotating the second engagement gear 152P, which is disposed on the inner periphery of the fixed member 23, can be input from the outer periphery of the fixed member 23. This simplifies the mechanism compared to a configuration in which the drive force is input from the inner periphery of the first brake B1 and the second brake B2, improving the assembly of the drive unit 10. Furthermore, instead of using two drive sources to selectively engage and disengage the first brake B1 and the second brake B2, a single drive source can be used.

[0042] Furthermore, according to the drive unit 10 of this embodiment, the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P, which serve as multiple pinion gears, are rotated synchronously by the drive of the motor 53. For this reason, the rotation input from the motor 53 can uniformly rotate the multiple engagement gears, uniforming the pressing forces on the pressing shafts and evenly pressing the first brake B1 and the second brake B2, thereby reducing wear on the friction plates.

[0043] Furthermore, according to the drive unit 10 of this embodiment, the first and second pressing members 56 and 57, which are annular, are provided at the ends of the pressing shafts 51, 151 of the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P, respectively, so that the first brake B1 and the second brake B2 can be pressed more effectively and evenly.

[0044] Furthermore, the drive unit 10 of this embodiment has a sun gear 52S that meshes with the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P as a plurality of pinion gears. As a result, the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P are rotated synchronously by the drive of the motor 53. Furthermore, for example, the outer diameter of the planetary gear mechanism 52 can be made smaller and the weight can be reduced compared to when a ring gear is provided that meshes with the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P and the drive force of the motor 53 is input to this ring gear.

[0045] In the above-described embodiment, the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P are arranged at three equally spaced locations as multiple pinion gears, but this is not limited to this and they may be arranged at three unequally spaced locations, or at four or more equally spaced locations, or at four or more unequally spaced locations.

[0046] In addition, in the present embodiment, the first engagement gear 52P, the second engagement gear 152P, and the third engagement gear 252P are synchronized by the sun gear 52S, but this is not limited to this. For example, they may be synchronized by a ring gear. In this case, it is preferable that the driving force of the motor 53 is input to the ring gear. In this case, for example, a worm gear that meshes with the ring gear may be provided, and this worm gear may be rotated by the motor 53. Alternatively, synchronization is not limited to using gears, and any configuration that synchronizes multiple rotating elements, such as a belt or chain, may be used as appropriate.

[0047] In addition, in this embodiment, the motor 53 is described as being attached to the outside of the case 15, but this is not limited to this, and the motor 53 may be housed in the case 15, or may be housed in a motor case attached to the outside of the case 15.

[0048] In addition, in this embodiment, the electric motor 53 is used as the engagement drive source, but the present invention is not limited to this. For example, hydraulic pressure using oil may be used as the engagement drive source.

[0049] Furthermore, in this embodiment, a case has been described in which a planetary gear mechanism is used as the differential device 14, but the present invention is not limited to this, and for example, a configuration having a differential ring gear or a side gear may be used.

[0050] In addition, in this embodiment, the first brake B1 and the second brake B2 each have a plurality of friction plates, but this is not limiting and they may each have a single friction plate.

[0051] Furthermore, in this embodiment, the power transmission device has been described as being applied to a two-stage transmission 13, but the present invention is not limited to this. For example, the power transmission device may be provided on a propeller shaft that drive-connects front and rear wheels, and may be applied as a switching device for connecting and disconnecting the transmission of driving force to the front and rear wheels. Furthermore, the present invention is not limited to being applied to electric vehicles, but may also be applied to internal combustion engine vehicles and hybrid vehicles. For example, the power transmission device may be applied to a transmission that changes the speed of driving force from an internal combustion engine.

[0052] <Second embodiment> Next, a second embodiment will be described with reference to Figures 5 and 6. This embodiment differs from the first embodiment in the configuration of the transmission 213 of the drive unit 210. However, other configurations are the same as those of the first embodiment, so the same reference numerals will be used and detailed description will be omitted.

[0053] [Drive unit] The front wheel drive unit 210 will be described below with reference to Figures 5 and 6. Figure 5 is a skeleton diagram showing the drive unit 210, and Figure 6 is an explanatory diagram showing an engagement mechanism 250 of the drive unit 210. In the following description, the left-right direction will be referred to as the axial direction.

[0054] [Case Configuration] As shown in Fig. 6, the drive unit 210 includes a case 215 that houses the motor 12, the transmission 213, and the differential 14, and a cover 217 that closes an opening of the case 215. The case 215 includes a first chamber 215a that houses the first brake B1 and the second brake B2, a second chamber 215b that houses a gear mechanism 240 (described later), and a partition wall 215c that divides the internal space of the case 215 and separates the first chamber 215a from the second chamber 215b. A central shaft member 219 is fixed to the cover 217 and protrudes into the case 215 about a rotation axis C1 (described later). The central shaft member 219 includes a flange-shaped disk portion 219a that is centered on the rotation axis C1 inside the case 215.

[0055] [Motor] Motor 12 (see FIG. 1) is an example of a drive source, and has stator 12a, which is a fixed part, fixed to case 215, and rotor 12b, which is a rotor that rotates when embedded magnets are induced by magnetic force from coils arranged in stator 12a. Rotor 12b is fixed to rotor shaft 18 so as to rotate integrally with rotor 12b. Rotor shaft 18 is an example of an input part that is drivingly connected to motor 12.

[0056] [Transmission] A transmission 213 is interposed on the power transmission path between the rotor shaft 18 and the differential device 14. The transmission 213 is an example of a power transmission device, and has a gear mechanism 240 having a planetary gear mechanism, and an engagement mechanism 250 that can fix some of the rotating elements of the gear mechanism 240.

[0057] [Gear mechanism] The gear mechanism 240 has a first planetary gear mechanism 241 and a second planetary gear mechanism 242, and is capable of forming a first power transmission path by the first planetary gear mechanism 241 and a second power transmission path different from the first power transmission path by the second planetary gear mechanism 242. In this embodiment, the first power transmission path and the second power transmission path both form power transmission paths that drivingly connect the rotor shaft 18 and the drive shafts 11L, 11R, but have different gear ratios, and the speed is changed by switching between the first power transmission path and the second power transmission path.

[0058] The first planetary gear mechanism 241 includes a first ring gear 241R and a first carrier 241C that rotatably supports a plurality of pinion gears 241P that mesh with the first ring gear 241R. A transmission gear 244 that is arranged coaxially with the rotor shaft 18 is integrally attached to the first carrier 241C. The second planetary gear mechanism 242 includes a second sun gear 242S that is fixed to the rotor shaft 18, a second ring gear 242R, and a second carrier 242C that rotatably supports a plurality of pinion gears 242P that mesh with the second sun gear 242S and the second ring gear 242R. The second carrier 242C is integral with the first carrier 241C.

[0059] The diameter of the pinion gear 241P is smaller than the diameter of the pinion gear 242P. The outer diameter of the second ring gear 242R is equal to the outer diameter of the first ring gear 241R.

[0060] A transmission gear 246 meshes with the external teeth of the first ring gear 241R. The transmission gear 246 is integrated with a cylindrical transmission shaft 247 that rotates about the rotation axis C1. The transmission shaft 247 is an example of a first rotating element. A transmission gear 248 meshes with the external teeth of the second ring gear 242R. The transmission gear 248 is integrated with a transmission shaft 249 that rotates about the rotation axis C1. The transmission shaft 249 is an example of a second rotating element, and is arranged coaxially with the transmission shaft 247.

[0061] [Engagement mechanism] Next, the engagement mechanism 250, which switches the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path, will be described. In this embodiment, the engagement mechanism 250 performs two-speed shifting by switching the power transmission path formed by the gear mechanism 240 between the first power transmission path and the second power transmission path. The engagement mechanism 250 includes a first brake B1, a second brake B2, a motor 253 as an example of an engagement drive source, a transmission mechanism 254, an engagement rotation member 255, a pressing member 251, and a threaded portion 262. The first brake B1, the second brake B2, and the engagement rotation member 255 are arranged in this order in the axial direction of the rotation axis C1. In this embodiment, the first brake B1 and the second brake B2 are dry multi-plate friction brakes. However, this is not limiting, and for example, wet or single-plate friction brakes may also be used. The motor 253 is provided outside the case 215 .

[0062] The engaging rotation member 255 has a substantially cylindrical shape, is rotatably provided on the central shaft member 219, and is rotated on the rotation axis C1 by the motor 253. The transmission mechanism 254 has a pinion gear 254a fixed to the drive shaft of the motor 253, a transmission gear 254b meshing with the pinion gear 254a, and a transmission gear 254c meshing with the transmission gear 254b. The transmission gear 254c is coaxially integrated with the engaging rotation member 255 on the rotation axis C1. Axialwise, a thrust bearing 265 is interposed between the engaging rotation member 255 and the disc portion 219a, and a thrust bearing 266 is interposed between the transmission gear 254c and the cover 217. When the motor 253 is driven to rotate, the engaging rotation member 255 is rotated via the transmission mechanism 254.

[0063] The pressing member 251 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 and the second brake B2. The pressing member 251 has a pressing portion 251a provided between the first brake B1 and the second brake B2 in the axial direction, an opposing portion 251b radially opposing the engaging rotation member 255, and a drum-shaped connecting portion 251c. In this embodiment, the pressing member 251 is an example of a drum-shaped member, and has a cylindrical connecting portion 251c (drum portion) disposed on the outer diameter side of one of the first brake B1 and the second brake B2 (here, second brake B2), and is rotatable about the rotation axis C1.

[0064] The pressing portion 251a can selectively press the first brake B1 or the second brake B2. The opposing portion 251b has an inner peripheral surface that faces the outer peripheral surface of the engaging rotation member 255. The connecting portion 251c is arranged to be axially movable relative to the case 215, is arranged at a position (outer diameter side) that is radially different from the second brake B2, and connects the pressing portion 251a and the opposing portion 251b. The connecting portion 251c has an external spline 251d formed on its outer peripheral surface. This external spline 251d engages with an internal spline 215s formed on the inner peripheral surface of the case 215, making the pressing member 251 non-rotatable relative to the case 215. In other words, the pressing member 251 is supported non-rotatably but axially movable relative to the case 215 by the spline engagement between the internal spline 215s and the external spline 251d.

[0065] The screw portion 262 has a female screw portion 263, which is an example of a screw-engaging portion, formed on the inner surface of the opposing portion 251b of the pressing member 251, and a male screw portion 264, which is an example of a threaded portion, formed on the outer surface of the engaging rotating member 255 and threaded onto the female screw portion 263.

[0066] A seal member 221 is provided between the transmission shaft 247 and the partition wall 215c. The first brake B1 is provided between the transmission shaft 247 and the case 215. The first brake B1 has a plurality of first outer friction plates 271 and a plurality of first inner friction plates 272. The outer diameter side of the first outer friction plates 271 is spline-engaged with an internal spline 215s formed on the inner circumference side of the case 215, and the first inner friction plates 272 are supported and arranged so as to be non-rotatable relative to the case 215. The inner diameter side of the first inner friction plates 272 is spline-engaged with a spline 258s formed on the outer circumference side of an inner circumference side member 258 which is provided so as to be non-rotatable relative to the transmission shaft 247 by a spline or the like, and the first inner friction plates 272 are arranged so as to be non-rotatable relative to the transmission shaft 247.

[0067] The multiple first outer friction plates 271 and the multiple first inner friction plates 272 are arranged alternately in the axial direction. The first outer friction plate 271 located on the leftmost side L of the first outer friction plates 271 is positioned and fixed toward the left side L with respect to the partition wall 215c. The first outer friction plate 271 located on the rightmost side R of the first outer friction plates 271 faces the pressing portion 251a in the axial direction. The first brake B1 can form a first power transmission path in the gear mechanism 240 by making the first ring gear 241R non-rotatable relative to the case 215 via the transmission shaft 247 and the transmission gear 246.

[0068] That is, the first brake B1 has a first outer friction plate 271 (first non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215, and a first inner friction plate 272 (first rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 247, and the first outer friction plate 271 and the first inner friction plate 272 are pressed by the pressing portion 251a, thereby making it impossible for the transmission shaft 247 to rotate relative to the case 215.

[0069] A seal member 222 is provided between the transmission shaft 249 and the inner peripheral member 258. The second brake B2 is provided between the transmission shaft 249 and the pressing member 251. The second brake B2 has a plurality of second outer friction plates 273 and a plurality of second inner friction plates 274. The second outer friction plates 273 are spline-engaged with splines 251s formed on the inner peripheral side of the connecting portion 251c of the pressing member 251, and are supported and arranged so as to be non-rotatable relative to the case 215 via the pressing member 251. The second inner friction plates 274 are spline-engaged with splines 259s formed on the outer peripheral side of the inner peripheral member 259, which is provided so as to be non-rotatable relative to the transmission shaft 249 by a spline or the like, and are arranged so as to be non-rotatable relative to the transmission shaft 249.

[0070] The multiple second outer friction plates 273 and the multiple second inner friction plates 274 are arranged alternately in the axial direction. The second outer friction plate 273 located on the rightmost side R of the second outer friction plates 273 is positioned and fixed toward the right side R with respect to the disc portion 219a of the central shaft member 219. The second outer friction plate 273 located on the leftmost side L of the second outer friction plates 273 faces the pressing portion 251a in the axial direction. The second brake B2 can form a second power transmission path in the gear mechanism 240 by making the second ring gear 242R non-rotatable relative to the case 215 via the transmission shaft 249 and the transmission gear 248.

[0071] That is, the second brake B2 has a second outer friction plate 273 (second non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the connecting portion 251c, and a second inner friction plate 274 (second rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 249, and the second outer friction plate 273 and the second inner friction plate 274 are pressed by the pressing portion 251a, thereby making it impossible for the transmission shaft 249 to rotate relative to the case 215.

[0072] In addition, in this embodiment, the disk portion 219a of the central shaft member 219 is an example of a pressure-receiving portion, and is arranged on the inner diameter side of the connecting portion 251c so as to be immovable in the axial direction relative to the case 215, and is positioned on the axial opposite side of the pressing portion 251a with respect to the second brake B2, so as to receive the pressing force when the second brake B2 is engaged.

[0073] In this embodiment, the pressing portion 251a selectively presses the first brake B1 and the second brake B2, but this does not mean that the pressing portion 251a is limited to directly pressing the first brake B1 and the second brake B2, and it also means that the pressing portion 251a may press the first brake B1 and the second brake B2 via another member. In this way, it is possible to selectively engage and disengage the two brakes using a single drive source, rather than using two drive sources.

[0074] [Differential device] The differential device 14 has, for example, the same configuration as that of the second embodiment shown in Fig. 2. However, the present invention is not limited to this, and other configurations may also be applied.

[0075] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 251a does not engage the first brake B1 or the second brake B2, rotating the engaging rotation member 255 in the second direction R2 causes the male thread portion 264 to move the pressing member 251 axially to the left side L toward the first brake B1, causing the pressing portion 251a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotation member 255 in a first direction R1 opposite to the second direction R2 causes the male thread portion 264 to move the pressing member 251 axially away from the first brake B1, releasing the pressing of the pressing portion 251a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0076] On the other hand, by rotating the engaging rotatable member 255 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the male thread portion 264 moves the pressing member 251 axially toward the second brake B2, causing the pressing portion 251a to press the second brake B2 and place the second brake B2 in the second engaged state. Then, by rotating the engaging rotatable member 255 in the second direction R2 from the second engaged state in which the second brake B2 is engaged, the male thread portion 264 moves the pressing member 251 axially away from the second brake B2, releasing the pressing of the pressing portion 251a on the second brake B2 and placing the first brake B1 and the second brake B2 in the disengaged state.

[0077] As described above, according to the drive unit 210 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 251. This allows a single motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 251a, so there is no need to provide such a thrust bearing, and the drive unit 210 can be made smaller. According to this embodiment, a reasonable electric brake actuator that can be applied to a transmission can be obtained.

[0078] Furthermore, according to the drive unit 210 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 255 are arranged in this order in the axial direction around the rotation axis C1. Therefore, compared to when the engaging rotational member 255 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be narrowed, thereby enabling the engagement mechanism 250 to be made more compact. Furthermore, because the central shaft member 219 is arranged on the rotation axis C1, not only the engaging rotational member 255 but also the pressing member 251 can be arranged around the rotation axis C1 and can be arranged in a position where they partially overlap with the engaging rotational member 255 in the axial direction, thereby preventing the engagement mechanism 250 from becoming larger.

[0079] Furthermore, according to the drive unit 210 of this embodiment, the pressing portion 251a of the pressing member 251 is disposed between the first brake B1 and the second brake B2. Therefore, the member that presses the first brake B1 and the member that presses the second brake B2 are made to be a common member, thereby simplifying the configuration and easily achieving modularization of the engagement mechanism 250.

[0080] Furthermore, according to the drive unit 210 of this embodiment, the connecting portion 251c of the pressing member 251 is drum-shaped and passes through the outer periphery of the second brake B2 in the axial direction. Therefore, the second brake B2 is disposed on the inner periphery side of the pressing member 251, which simplifies the configuration.

[0081] Furthermore, according to the drive unit 210 of this embodiment, dry multi-plate friction brakes are used as the first brake B1 and the second brake B2. Furthermore, seal members 221 and 222 are provided at the portions of the partition wall 215c through which the transmission shafts 247 and 249 pass. This allows for dry friction brakes to be provided in the air chambers, thereby reducing drag in the first brake B1 and the second brake B2, increasing friction, and improving responsiveness.

[0082] In the above-described embodiment, the motor 253 is attached to the outside of the case 215, but this is not limited to this, and the motor 253 may be housed in the case 215, or may be housed in a motor case attached to the outside of the case 215.

[0083] In addition, in this embodiment, the electric motor 253 is used as the engagement drive source, but the present invention is not limited to this. For example, hydraulic pressure using oil may be used as the engagement drive source.

[0084] Furthermore, in this embodiment, a case has been described in which a planetary gear mechanism is used as the differential device 14, but the present invention is not limited to this, and for example, a configuration having a differential ring gear or a side gear may be used.

[0085] Furthermore, in this embodiment, the power transmission device has been described as being applied to a two-stage transmission 213, but the present invention is not limited to this. For example, the power transmission device may be provided on a propeller shaft that drive-connects front and rear wheels, and may be applied as a switching device for connecting and disconnecting the transmission of driving force to the front and rear wheels. Furthermore, the present invention is not limited to being applied to electric vehicles, but may also be applied to internal combustion engine vehicles and hybrid vehicles. For example, the power transmission device may be applied to a transmission that changes the speed of driving force from an internal combustion engine.

[0086] <Third embodiment> Next, a third embodiment will be described with reference to Figure 7. This embodiment differs from the second embodiment in the configuration of the engagement mechanism 350 in the transmission 313 of the drive unit 310. However, other configurations are the same as those in the second embodiment, so the same reference numerals will be used and detailed description will be omitted.

[0087] [Engagement mechanism] In this embodiment, the engagement mechanism 350 performs two-stage gear shifting by switching the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path. The engagement mechanism 350 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 254, an engagement rotation member 355, a pressing member 351, and a threaded portion 362. The first brake B1, the second brake B2, and the engagement rotation member 355 are arranged in this order in the axial direction of the rotation axis C1.

[0088] The engaging rotation member 355 is a shaft-shaped member that is rotatable on the rotation axis C1, and its right end (R) is rotatably supported by the cover 217 via a bearing, while its left end (L) is rotatably supported by a disk-shaped support member 319 via a bearing. The support member 319 will be described later. The transmission mechanism 254 has a pinion gear 254a fixed to the drive shaft of the motor 253, a transmission gear 254b meshing with the pinion gear 254a, and a transmission gear 254c meshing with the transmission gear 254b. The transmission gear 254c is coaxially integrated with the engaging rotation member 355 on the rotation axis C1. A thrust bearing 265 is interposed axially between the flange portion of the engaging rotation member 255 and the support member 319, and a thrust bearing 266 is interposed between the transmission gear 254c and the cover 217. When the motor 253 is driven to rotate, the engagement rotation member 355 is rotated via the transmission mechanism 254 .

[0089] The pressing member 351 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 and the second brake B2. The pressing member 351 has a pressing portion 351a provided between the first brake B1 and the second brake B2 in the axial direction, a facing portion 351b facing the engaging rotation member 355 in the radial direction, and a drum-shaped connecting portion 351c. In this embodiment, the pressing member 351 is an example of a drum-shaped member, and has a cylindrical connecting portion 351c (drum portion) disposed on the outer diameter side of one of the first brake B1 and the second brake B2 (here, second brake B2), and is rotatable about the rotation axis C1.

[0090] The pressing portion 351a can selectively press the first brake B1 or the second brake B2. The opposing portion 351b has an inner peripheral surface that faces the outer peripheral surface of the engaging rotation member 355. The connecting portion 351c is arranged to be axially movable relative to the case 215, is arranged at a position (outer diameter side) that is radially different from the second brake B2, and connects the pressing portion 351a and the opposing portion 351b. The connecting portion 351c has an external spline 351d formed on its outer peripheral surface. This external spline 351d engages with an internal spline 215s formed on the inner peripheral surface of the case 215, making the pressing member 351 non-rotatable relative to the case 215. In other words, the pressing member 351 is supported non-rotatably but axially movable relative to the case 215 by the spline engagement between the internal spline 215s and the external spline 351d.

[0091] The threaded portion 362 has a female threaded portion 363, which is an example of a threaded portion, formed on the inner peripheral surface of the opposing portion 351b of the pressing member 351, and a male threaded portion 364, which is an example of a threaded portion, formed on the outer peripheral surface of the engaging rotating member 355 and which screws into the female threaded portion 363.

[0092] The first brake B1 has a first outer friction plate 271 (first non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215, and a first inner friction plate 272 (first rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 247, and the first outer friction plate 271 and the first inner friction plate 272 are pressed by the pressing portion 351a, making the transmission shaft 247 non-rotatable relative to the case 215.

[0093] The second brake B2 has a plurality of second outer friction plates 273 and a plurality of second inner friction plates 274. The plurality of second outer friction plates 273 and the plurality of second inner friction plates 274 are arranged alternately in the axial direction. A support member 319 is provided on the right side R of the second brake B2. The support member 319 has splines formed on its outer circumferential surface, and engages with splines 351s formed on the inner circumferential surface of the connecting portion 351c. This prevents the support member 319 from rotating relative to the case 215. The second outer friction plate 273 located on the rightmost side R of the second outer friction plates 273 is positioned and fixed toward the right side R with respect to the support member 319.

[0094] In this embodiment, the support member 319 is an example of a pressure-receiving portion, and is arranged on the inner diameter side of the connecting portion 351c so as to be immovable axially relative to the case 215, and is positioned on the axial opposite side of the pressing portion 351a relative to the second brake B2, so as to receive the pressing force when the second brake B2 is engaged.

[0095] The second brake B2 has a second outer friction plate 273 (second non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the connecting portion 351c, and a second inner friction plate 274 (second rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 249, and the second outer friction plate 273 and the second inner friction plate 274 are pressed by the pressing portion 351a, making the transmission shaft 249 non-rotatable relative to the case 215.

[0096] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 351a does not engage the first brake B1 or the second brake B2, rotating the engaging rotation member 355 in the second direction R2 causes the male thread portion 364 to move the pressing member 351 axially to the left side L toward the first brake B1, causing the pressing portion 351a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotation member 355 in the first direction R1, opposite the second direction R2, causes the male thread portion 364 to move the pressing member 351 axially away from the first brake B1, releasing the pressing of the pressing portion 351a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0097] On the other hand, by rotating the engaging rotatable member 355 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the male thread portion 364 moves the pressing member 351 axially toward the second brake B2, causing the pressing portion 351a to press the second brake B2 and place the second brake B2 in the second engaged state. Then, by rotating the engaging rotatable member 355 in the second direction R2 from the second engaged state in which the second brake B2 is engaged, the male thread portion 364 moves the pressing member 351 axially away from the second brake B2, releasing the pressing of the pressing portion 351a on the second brake B2 and placing the first brake B1 and the second brake B2 in the disengaged state.

[0098] As described above, according to the drive unit 310 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 351. This allows a single motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 351a, so there is no need to provide such a thrust bearing, and the drive unit 310 can be made smaller. According to this embodiment, a reasonable electric brake actuator applicable to a transmission can be obtained.

[0099] Furthermore, according to the drive unit 310 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 355 are arranged in this order in the axial direction around the rotational axis C1. Therefore, compared to when the engaging rotational member 355 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be narrowed, thereby enabling the engagement mechanism 350 to be made more compact. Furthermore, because there is no central shaft member as in the second embodiment, the number of parts can be reduced, simplifying the configuration and preventing the engagement mechanism 350 from becoming larger.

[0100] <Fourth embodiment> Next, a fourth embodiment will be described with reference to Fig. 8. This embodiment differs from the second embodiment in the configuration of the engagement mechanism 450 in the transmission 413 of the drive unit 410. However, other configurations are the same as those in the second embodiment, so the same reference numerals will be used and detailed description will be omitted.

[0101] [Engagement mechanism] In this embodiment, the engagement mechanism 450 performs two-stage gear shifting by switching the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path. The engagement mechanism 450 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 454, an engagement rotation member 455, a pressing member 451, and a threaded portion 462. The first brake B1, the second brake B2, and the engagement rotation member 455 are arranged in this order in the axial direction of the rotation axis C1.

[0102] The engaging rotation member 455 has a substantially cylindrical shape and is rotatably mounted on a central shaft member 419 fixed to the cover 217 via an opposing portion 451b of the pressing member 451, and is rotated on a rotation axis C1 by the motor 253. The transmission mechanism 454 has a pinion gear 454a fixed to the drive shaft of the motor 253, a transmission gear 454b meshing with the pinion gear 454a, a transmission gear 454c that is coaxially integrated with the transmission gear 454b and has a smaller diameter than the transmission gear 454b, and a transmission gear 454d that meshes with the transmission gear 454c. The transmission gear 454d is coaxially integrated with the engaging rotation member 455 on the rotation axis C1.

[0103] A central shaft member 419 is fixed to the cover 217 and provided to protrude into the case 215 about the rotation axis C1. The central shaft member 419 has a flange-shaped disk portion 419a at the end on the left side L and centered on the rotation axis C1, and a flange portion 419b between the engaging rotation member 455 and the transmission gear 454d. In the axial direction, a thrust bearing 465 is interposed between the engaging rotation member 455 and the flange portion 419b, and a thrust bearing 466 is interposed between the transmission gear 454d and the cover 217. When the motor 253 is driven to rotate, the engaging rotation member 455 is rotated via the transmission mechanism 454.

[0104] The pressing member 451 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 and the second brake B2. The pressing member 451 has a pressing portion 451a provided between the first brake B1 and the second brake B2 in the axial direction, an opposing portion 451b radially opposing the engaging rotation member 455, and a drum-shaped connecting portion 451c. In this embodiment, the pressing member 451 is an example of a drum-shaped member, and has a cylindrical connecting portion 451c (drum portion) disposed on the outer diameter side of one of the first brake B1 and the second brake B2 (here, second brake B2), and is rotatable about the rotation axis C1.

[0105] The pressing portion 451a can selectively press the first brake B1 or the second brake B2. The opposing portion 451b has an outer peripheral surface that faces the inner peripheral surface of the engagement rotation member 455. The connecting portion 451c is arranged to be axially movable relative to the case 215, is arranged at a position (outer diameter side) that is radially different from the second brake B2, and connects the pressing portion 451a and the opposing portion 451b. The connecting portion 451c has an external spline 451d formed on its outer peripheral surface. This external spline 451d engages with an internal spline 215s formed on the inner peripheral surface of the case 215, making the pressing member 451 non-rotatable relative to the case 215. In other words, the pressing member 451 is supported non-rotatably but axially movable relative to the case 215 by the spline engagement between the internal spline 215s and the external spline 451d.

[0106] The screw portion 462 has a male screw portion 463, which is an example of a screw-engagement portion, formed on the outer peripheral surface of the opposing portion 451b of the pressing member 451, and a female screw portion 464, which is an example of a threaded portion, formed on the inner peripheral surface of the engaging rotating member 455 and threaded onto the male screw portion 463.

[0107] The first brake B1 has a first outer friction plate 271 (first non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215, and a first inner friction plate 272 (first rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 247, and the first outer friction plate 271 and the first inner friction plate 272 are pressed by the pressing portion 451a, making the transmission shaft 247 non-rotatable relative to the case 215.

[0108] The second brake B2 has a plurality of second outer friction plates 273 and a plurality of second inner friction plates 274. The plurality of second outer friction plates 273 and the plurality of second inner friction plates 274 are arranged alternately in the axial direction. The second outer friction plate 273 located on the rightmost side R of the second outer friction plates 273 is positioned and fixed toward the right side R with respect to the disc portion 419a of the center shaft member 419. The second outer friction plate 273 located on the leftmost side L of the second outer friction plates 273 faces the pressing portion 451a in the axial direction.

[0109] In this embodiment, the disc portion 419a is an example of a pressure-receiving portion, and is arranged on the inner diameter side of the connecting portion 451c so as to be immovable axially relative to the case 215, and is positioned axially opposite the pressing portion 451a relative to the second brake B2, so as to receive the pressing force when the second brake B2 is engaged.

[0110] The second brake B2 has a second outer friction plate 273 (second non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the connecting portion 451c, and a second inner friction plate 274 (second rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 249, and the second outer friction plate 273 and the second inner friction plate 274 are pressed by the pressing portion 451a, making the transmission shaft 249 non-rotatable relative to the case 215.

[0111] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 451a does not engage the first brake B1 or the second brake B2, rotating the engaging rotation member 455 in the second direction R2 causes the female thread portion 464 to move the pressing member 451 axially to the left side L toward the first brake B1, causing the pressing portion 451a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotation member 455 in a first direction R1 opposite to the second direction R2 causes the female thread portion 464 to move the pressing member 451 axially away from the first brake B1, releasing the pressing of the pressing portion 451a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0112] On the other hand, by rotating the engaging rotation member 455 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the female thread portion 464 moves the pressing member 451 axially toward the second brake B2, causing the pressing portion 451a to press the second brake B2 and place the second brake B2 in a second engaged state. Then, by rotating the engaging rotation member 455 in the second direction R2 from the second engaged state in which the second brake B2 is engaged, the female thread portion 464 moves the pressing member 451 axially away from the second brake B2, releasing the pressing of the second brake B2 by the pressing portion 451a and placing the first brake B1 and the second brake B2 in a disengaged state.

[0113] As described above, according to the drive unit 410 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 451. This allows a single motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 451a, so there is no need to provide such a thrust bearing, and the drive unit 410 can be made smaller. According to this embodiment, a reasonable electric brake actuator applicable to a transmission can be obtained.

[0114] Furthermore, according to the drive unit 410 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 455 are arranged in this order in the axial direction around the rotational axis C1. Therefore, compared to when the engaging rotational member 455 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be made narrower, and the engaging mechanism 450 can be made more compact.

[0115] Furthermore, according to the drive unit 410 of this embodiment, the threaded portion 462 has a male threaded portion 463 formed on the outer peripheral surface of the opposing portion 451b of the pressing member 451, and a female threaded portion 464 formed on the inner peripheral surface of the engaging rotation member 455. As a result, the driving force from the motor 253 is transmitted from the outer peripheral side to the inner peripheral side in the threaded portion 462 to move the pressing member 451, so that the pressing member 451 can be directly supported by the central shaft member 419, and the movement of the pressing member 451 can be stabilized.

[0116] <Fifth embodiment> Next, a fifth embodiment will be described with reference to Figure 9. This embodiment differs from the second embodiment in the configuration of the engagement mechanism 550 in the transmission 513 of the drive unit 510. However, other configurations are the same as those in the second embodiment, so the same reference numerals will be used and detailed description will be omitted.

[0117] [Engagement mechanism] In this embodiment, the engagement mechanism 550 performs two-stage gear shifting by switching the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path. The engagement mechanism 550 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 254, an engagement rotation member 555, a pressing member 551, and a threaded portion 262. The first brake B1, the second brake B2, and the engagement rotation member 555 are arranged in this order in the axial direction of the rotation axis C1.

[0118] The engaging rotation member 555 has a substantially cylindrical shape, is rotatably provided on a central shaft member 519 fixed to the cover 217, and is rotated on a rotation axis C1 by the motor 253. The transmission mechanism 254 has a pinion gear 254a fixed to the drive shaft of the motor 253, a transmission gear 254b meshing with the pinion gear 254a, and a transmission gear 254c meshing with the transmission gear 254b. The transmission gear 254c is integrated with the engaging rotation member 555 coaxially on the rotation axis C1. When the motor 253 is driven to rotate, the engaging rotation member 555 is rotated via the transmission mechanism 254.

[0119] The pressing member 551 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 and the second brake B2. The pressing member 551 has a pressing portion 551a provided between the first brake B1 and the second brake B2 in the axial direction, a facing portion 551b facing the engaging rotation member 555 in the radial direction, and a drum-shaped connecting portion 551c. In this embodiment, the pressing member 551 is an example of a drum-shaped member, and has a cylindrical connecting portion 551c (drum portion) disposed on the outer diameter side of one of the first brake B1 and the second brake B2 (here, second brake B2), and is rotatable about the rotation axis C1.

[0120] The pressing portion 551a can selectively press the first brake B1 or the second brake B2. The facing portion 551b has an inner circumferential surface facing the outer circumferential surface of the engaging rotation member 555. The connecting portion 551c is arranged to be movable in the axial direction relative to the case 215, and is arranged at a different position (outer diameter side) from the second brake B2 in the radial direction, connecting the pressing portion 551a and the facing portion 551b.

[0121] A central shaft member 519 is fixed to the cover 217 and protrudes into the case 215 about the rotation axis C1. The central shaft member 519 has a flange-shaped disk portion 519a at the end on the left side L and centered on the rotation axis C1. A guide shaft 520 having an axial direction as its central axis is provided on the disk portion 519a at at least one location in the circumferential direction (in this embodiment, multiple locations). Meanwhile, a guide hole 551d is formed in the connecting portion 551c of the pressing member 551, through which the guide shaft 520 passes in the axial direction. A plain bearing 521 is interposed between the guide shaft 520 and the guide hole 551d. By having the guide shaft 520 pass through the guide hole 551d, the axial movement of the pressing member 551 is guided and the pressing member 551 is prevented from rotating relative to the case 215. That is, central shaft member 519 is an example of a shaft portion, is fixedly supported by case 215, and is disposed so as to penetrate the inner diameter side of engaging rotation member 555. Furthermore, disc portion 519a is an example of a flange portion, and is formed in a flange shape on the outer diameter side of central shaft member 519. Guide shaft 520 is an example of a guide member, and is fixed to one of disc portion 519a and connecting portion 551c (disc portion 519a in this embodiment), and guides the other so as to be movable in the axial direction. Note that, in this embodiment, the case where guide shaft 520 is fixed to disc portion 519a has been described, but the present invention is not limited thereto, and guided movably relative to a guide hole formed in disc portion 519a may also be used.

[0122] In this embodiment, the disc portion 519a is an example of a pressure-receiving portion, and is arranged on the inner diameter side of the connecting portion 551c so as to be immovable axially relative to the case 215, and is positioned axially opposite the pressing portion 551a relative to the second brake B2, so as to receive the pressing force when the second brake B2 is engaged.

[0123] The first brake B1 has a first outer friction plate 271 (first non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215, and a first inner friction plate 272 (first rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 247, and the first outer friction plate 271 and the first inner friction plate 272 are pressed by the pressing portion 551a, making the transmission shaft 247 non-rotatable relative to the case 215.

[0124] The second brake B2 has a second outer friction plate 273 (second non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the connecting portion 551c, and a second inner friction plate 274 (second rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 249, and the second outer friction plate 273 and the second inner friction plate 274 are pressed by the pressing portion 551a, making the transmission shaft 249 non-rotatable relative to the case 215.

[0125] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 551a does not engage the first brake B1 or the second brake B2, rotating the engaging rotation member 555 in the second direction R2 causes the male thread portion 264 to move the pressing member 551 axially to the left side L toward the first brake B1, causing the pressing portion 551a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotation member 555 in a first direction R1 opposite to the second direction R2 causes the male thread portion 264 to move the pressing member 551 axially away from the first brake B1, releasing the pressing of the pressing portion 551a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0126] On the other hand, by rotating the engaging rotatable member 555 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the male thread portion 264 moves the pressing member 551 axially toward the second brake B2, causing the pressing portion 551a to press the second brake B2 and place the second brake B2 in the second engaged state. Then, by rotating the engaging rotatable member 555 in the second direction R2 from the second engaged state in which the second brake B2 is engaged, the male thread portion 264 moves the pressing member 551 axially away from the second brake B2, releasing the pressing of the pressing portion 551a on the second brake B2 and placing the first brake B1 and the second brake B2 in the disengaged state.

[0127] As described above, according to the drive unit 510 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 551. This allows one motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 551a, so there is no need to provide such a thrust bearing, and the drive unit 510 can be made smaller. According to this embodiment, a reasonable electric brake actuator that can be applied to a transmission can be obtained.

[0128] Furthermore, according to the drive unit 510 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 555 are arranged in this order in the axial direction around the rotational axis C1. Therefore, compared to when the engaging rotational member 555 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be made narrower, and the engaging mechanism 550 can be made more compact.

[0129] Furthermore, according to the drive unit 510 of this embodiment, the pressing member 551 is guided by the guide shaft 520, which improves the centering accuracy compared to when the outer periphery of the connecting portion 551c is supported by spline engagement, thereby enabling smooth movement in the axial direction.

[0130] Sixth Embodiment Next, a sixth embodiment will be described with reference to Figure 10. This embodiment differs from the second embodiment in the configuration of the engagement mechanism 650 in the transmission 613 of the drive unit 610. However, other configurations are the same as those in the second embodiment, so the same reference numerals will be used and detailed description will be omitted.

[0131] [Case Configuration] In this embodiment, a hub member 218 is provided between the case 215 and the cover 217 in the axial direction. The hub member 218 has a flange portion 218a located inside the case 215, and a hub portion 218b extending from the inner periphery of the flange portion 218a toward the left side L. A central shaft member 619 is fixed to the cover 217 and provided so as to protrude into the inside of the case 215 with the rotation axis C1 as its center. The central shaft member 619 is an example of a support shaft member, and has a flange-shaped disk portion 619a centered on the rotation axis C1 inside the case 215.

[0132] [Engagement mechanism] In this embodiment, the engagement mechanism 650 performs two-stage gear shifting by switching the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path. The engagement mechanism 650 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 254, an engagement rotation member 655, a pressing member 651, and a threaded portion 662. The first brake B1, the second brake B2, and the engagement rotation member 655 are arranged in this order in the axial direction of the rotation axis C1.

[0133] The engaging rotation member 655 has a substantially cylindrical shape, is rotatably mounted on the central shaft member 619, and is rotated on the rotation axis C1 by the motor 253. That is, the central shaft member 619 is fixedly supported by the case 215 and is disposed so as to penetrate the inner diameter side of the engaging rotation member 655. The transmission mechanism 254 has a pinion gear 254a fixed to the drive shaft of the motor 253, a transmission gear 254b meshing with the pinion gear 254a, and a transmission gear 254c meshing with the transmission gear 254b. The transmission gear 254c is coaxially integrated with the engaging rotation member 655 on the rotation axis C1. A thrust bearing 665 is interposed between the engaging rotation member 655 and the flange portion 218a in the axial direction, and a thrust bearing 266 is interposed between the transmission gear 254c and the cover 217. When the motor 253 is driven to rotate, the engagement rotation member 655 is rotated via the transmission mechanism 254 .

[0134] The pressing member 651 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 or the second brake B2. The pressing member 651 has a pressing portion 651a disposed between the first brake B1 and the second brake B2 in the axial direction, a facing portion 651b radially facing the engaging rotation member 655, and a drum-shaped connecting portion 651c. The pressing portion 651a can selectively press the first brake B1 or the second brake B2. The facing portion 651b has an inner circumferential surface facing the outer circumferential surface of the engaging rotation member 655. The connecting portion 651c is disposed movably in the axial direction relative to the case 215 and is disposed at a position (inner diameter side) different in the radial direction from the second brake B2, connecting the pressing portion 651a and the facing portion 651b. The connecting portion 651c has an external spline 651s formed on its outer circumferential surface. The external spline 651s engages with the internal spline 218c formed on the hub portion 218b, thereby making the pressing member 651 non-rotatable relative to the case 215 via the hub member 218. That is, the pressing member 651 is supported non-rotatable relative to the case 215 but movable in the axial direction by the spline fitting of the internal spline 218c and the external spline 651s.

[0135] The screw portion 662 has a female screw portion 663, which is an example of a screw-engaging portion, formed on the inner surface of the opposing portion 651b of the pressing member 651, and a male screw portion 664, which is an example of a threaded portion, formed on the outer surface of the engaging rotating member 655 and which screws into the female screw portion 663.

[0136] In this embodiment, the transmission shaft 247 is a second rotating element, and a drum member 658 is attached to the right R end portion thereof so as to be non-rotatable relative to the transmission shaft 247. In this embodiment, the transmission shaft 249 is a first rotating element, and a drum member 659 is attached to the right R end portion thereof so as to be non-rotatable relative to the transmission shaft 249. A seal member 621 is provided between the drum member 658 and the partition wall 215c. A seal member 622 is provided between the drum member 658 and the transmission shaft 249. In this embodiment, the drum member 659 is an example of a drum-shaped member, and has a cylindrical drum portion 659a that is arranged on the outer diameter side of one of the first brake B1 and the second brake B2 (here, first brake B1), and is rotatable about the rotation axis C1.

[0137] The first brake B1 is provided between the central shaft member 619 and the drum member 659. The first brake B1 has a plurality of first outer friction plates 271 and a plurality of first inner friction plates 272. The first inner friction plates 272 are spline-engaged with external splines 619s formed on the outer periphery of the central shaft member 619, and are supported and disposed via the central shaft member 619 so as to be non-rotatable relative to the case 215. The first outer friction plates 271 are spline-engaged with internal splines 659s formed on the inner periphery of the drum member 659, and are disposed so as to be non-rotatable relative to the transmission shaft 249.

[0138] The multiple first outer friction plates 271 and the multiple first inner friction plates 272 are arranged alternately in the axial direction. The first inner friction plate 272 located on the leftmost side L of the first inner friction plates 272 is positioned and fixed toward the left side L with respect to the disc portion 619a. The first inner friction plate 272 located on the rightmost side R of the first inner friction plates 272 faces the pressing portion 651a in the axial direction. The first brake B1 can form a first power transmission path in the gear mechanism 240 by making the second ring gear 242R non-rotatable relative to the case 215 via the transmission shaft 249 and the transmission gear 248.

[0139] In this embodiment, the disc portion 619a is an example of a pressure-receiving portion, and is arranged on the inner diameter side of the drum portion 659a so as to be immovable axially relative to the case 215, and is positioned on the axial opposite side of the pressing portion 651a relative to the second brake B2, so as to receive the pressing force when the second brake B2 is engaged.

[0140] That is, the first brake B1 has a first inner friction plate 272 (first non-rotating portion) whose inner diameter side is supported so as not to rotate relative to the case 215 via the central shaft member 619, and a first outer friction plate 271 (first rotating portion) whose outer diameter side is supported so as not to rotate relative to the transmission shaft 249, and the first outer friction plate 271 and the first inner friction plate 272 are pressed by the pressing portion 651a, making the rotation of the transmission shaft 249 non-rotatable relative to the case 215.

[0141] The second brake B2 is provided between the drum member 658 and the hub member 218. That is, the hub member 218 is fixedly supported by the case 215, and the hub portion 218b is disposed on the inner diameter side of the second brake B2. The second brake B2 has a plurality of second outer friction plates 273 and a plurality of second inner friction plates 274. The second inner friction plates 274 are spline-engaged with splines 218s formed on the outer periphery of the hub portion 218b of the hub member 218, and are supported and disposed via the hub member 218 so as to be non-rotatable relative to the case 215. The second outer friction plates 273 are spline-engaged with splines 658s ​​formed on the inner periphery of the drum member 658, and are disposed so as to be non-rotatable relative to the transmission shaft 247.

[0142] The multiple second outer friction plates 273 and the multiple second inner friction plates 274 are arranged alternately in the axial direction. The second inner friction plate 274 located on the rightmost side R of the second inner friction plates 274 is positioned and fixed toward the right side R with respect to the flange portion 218a. The second inner friction plate 274 located on the leftmost side L of the second inner friction plates 274 faces the pressing portion 651a in the axial direction. The second brake B2 can form a second power transmission path in the gear mechanism 240 by making the first ring gear 241R non-rotatable relative to the case 215 via the transmission shaft 247 and the transmission gear 246.

[0143] That is, the second brake B2 has a second inner friction plate 274 (second non-rotating portion) whose inner diameter side is supported so as not to rotate relative to the case 215 via the hub member 218, and a second outer friction plate 273 (first rotating portion) whose outer diameter side is supported so as not to rotate relative to the transmission shaft 247, and the second outer friction plate 273 and the second inner friction plate 274 are pressed by the pressing portion 651a, making the rotation of the transmission shaft 247 non-rotatable relative to the case 215.

[0144] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 651a does not engage the first brake B1 or the second brake B2, rotating the engaging rotation member 655 in the second direction R2 causes the male thread portion 664 to move the pressing member 651 axially to the left side L toward the first brake B1, causing the pressing portion 651a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotation member 655 in a first direction R1 opposite to the second direction R2 causes the male thread portion 664 to move the pressing member 651 axially away from the first brake B1, releasing the pressing of the pressing portion 651a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0145] On the other hand, by rotating the engaging rotation member 655 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the male thread portion 664 moves the pressing member 651 axially toward the second brake B2, causing the pressing portion 651a to press the second brake B2, thereby placing the second brake B2 in a second engaged state. Then, by rotating the engaging rotation member 655 in the second direction R2 from the second engaged state in which the second brake B2 is engaged, the male thread portion 664 moves the pressing member 651 axially away from the second brake B2, releasing the pressing of the pressing portion 651a on the second brake B2 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0146] As described above, according to the drive unit 610 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 651. This allows one motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 651a, so there is no need to provide such a thrust bearing, and the drive unit 610 can be made smaller. According to this embodiment, a reasonable electric brake actuator applicable to a transmission can be obtained.

[0147] Furthermore, according to the drive unit 610 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 655 are arranged in this order in the axial direction around the rotational axis C1. Therefore, compared to when the engaging rotational member 655 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be made narrower, and the engaging mechanism 650 can be made more compact.

[0148] Furthermore, according to the drive unit 610 of this embodiment, the connecting portion 651c of the pressing member 651 passes through the inner periphery of the second brake B2, so that the pressing member 651 can be made smaller.

[0149] Seventh Embodiment Next, a seventh embodiment will be described with reference to Fig. 11. This embodiment differs from the second embodiment in that the first brake B1 and the second brake B2 of the transmission 713 of the drive unit 710 are dog brakes. However, other configurations are the same as those of the second embodiment, so the same reference numerals are used and detailed description will be omitted.

[0150] [Engagement mechanism] In this embodiment, the engagement mechanism 750 switches the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path to perform two-stage gear shifting. The engagement mechanism 750 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 254, an engagement rotation member 755, a pressing member 751, and a threaded portion 262. The first brake B1, the second brake B2, and the engagement rotation member 755 are arranged in this order in the axial direction of the rotation axis C1. In this embodiment, the first brake B1 and the second brake B2 are dog brakes.

[0151] The engaging rotation member 755 has a substantially cylindrical shape, is rotatably provided on a central shaft member 719 fixed to the cover 217, and is rotated on a rotation axis C1 by the motor 253. The transmission mechanism 254 has a pinion gear 254a fixed to the drive shaft of the motor 253, a transmission gear 254b meshing with the pinion gear 254a, and a transmission gear 254c meshing with the transmission gear 254b. The transmission gear 254c is integrated with the engaging rotation member 755 coaxially on the rotation axis C1.

[0152] A central shaft member 719 is fixed to the cover 217 and provided to protrude into the case 215 with the rotation axis C1 as its center. The central shaft member 719 has a flange-shaped disk portion 719a at its end on the left side L and the disk portion 719a is centered on the rotation axis C1. In the axial direction, a thrust bearing 265 is interposed between the engaging rotation member 755 and the disk portion 719a, and a thrust bearing 266 is interposed between the transmission gear 254c and the cover 217. When the motor 253 is driven to rotate, the engaging rotation member 755 is rotated via the transmission mechanism 254.

[0153] The pressing member 751 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 or the second brake B2. The pressing member 751 has a pressing portion 751a disposed between the first brake B1 and the second brake B2 in the axial direction, a facing portion 751b radially facing the engaging rotation member 755, and a drum-shaped connecting portion 751c. The pressing portion 751a can selectively press the first brake B1 or the second brake B2. The facing portion 751b has an inner circumferential surface facing the outer circumferential surface of the engaging rotation member 755. The connecting portion 751c is disposed movably in the axial direction relative to the case 215 and is disposed at a position (outer diameter side) different in the radial direction from the second brake B2, connecting the pressing portion 751a and the facing portion 751b. The connecting portion 751c has an external spline 751d formed on its outer circumferential surface. The external spline 751d engages with an internal spline 215s formed on the inner circumferential surface of the case 215, thereby making the pressing member 751 non-rotatable relative to the case 215. That is, the pressing member 751 is supported non-rotatable relative to the case 215 but movable in the axial direction by the spline fitting of the internal spline 215s and the external spline 751d.

[0154] The screw portion 262 has a female screw portion 263, which is an example of a screw-engaging portion, formed on the inner surface of the opposing portion 751b of the pressing member 751, and a male screw portion 264, which is an example of a threaded portion, formed on the outer surface of the engaging rotating member 755 and which screws into the female screw portion 263.

[0155] The first brake B1 is provided between the transmission shaft 247 and the case 215. The first brake B1 has a first fitting portion 771 and a first fitted portion 772. The first fitting portion 771 is integrated with the pressing portion 751a and is supported and arranged so as to be non-rotatable relative to the case 215. The first fitting portion 771 is an example of a first non-rotating portion and is arranged so as to be non-rotatable relative to the pressing portion 751a. The first fitted portion 772 is integrated with an inner circumferential member 758 that is arranged so as to be non-rotatable relative to the transmission shaft 247 by a spline or the like and is arranged so as to be non-rotatable relative to the transmission shaft 247. The first fitted portion 772 is an example of a first rotating portion and is arranged so as to be non-rotatable relative to the transmission shaft 247 and is arranged so that the first fitting portion 771 can be fitted thereto. The first brake B1 can form a first power transmission path in the gear mechanism 240 by making the first ring gear 241R non-rotatable relative to the case 215 via the transmission shaft 247 and the transmission gear 246.

[0156] That is, the first brake B1 has a first engaging portion 771 (first non-rotating portion) that is arranged so as to be non-rotatable relative to the case 215, and a first engaged portion 772 (first rotating portion) that is arranged so as to be non-rotatable relative to the transmission shaft 247, and the first engaging portion 771 and the first engaged portion 772 are pressed by the pressing portion 751a, thereby making the transmission shaft 247 non-rotatable relative to the case 215.

[0157] The second brake B2 is provided between the transmission shaft 249 and the pressing member 751. The second brake B2 has a second fitting portion 773 and a second fitted portion 774. The second fitting portion 773 is integrated with the pressing portion 751a and is supported and arranged so as to be non-rotatable relative to the case 215. The second fitting portion 773 is an example of a second non-rotating portion and is arranged so as to be non-rotatable relative to the pressing portion 751a. The second fitted portion 774 is integrated with an inner circumferential member 759 that is arranged so as to be non-rotatable relative to the transmission shaft 249 by a spline or the like and is arranged so as to be non-rotatable relative to the transmission shaft 249. The second fitted portion 774 is an example of a second rotating portion and is arranged so as to be non-rotatable relative to the transmission shaft 249 and is arranged so as to be able to fit with the second fitting portion 773. The second brake B2 can form a second power transmission path in the gear mechanism 240 by making the second ring gear 242R non-rotatable relative to the case 215 via the transmission shaft 249 and the transmission gear 248.

[0158] That is, the second brake B2 has a second engaging portion 773 (second non-rotating portion) that is arranged so as to be non-rotatable relative to the case 215, and a second engaged portion 774 (second rotating portion) that is arranged so as to be non-rotatable relative to the transmission shaft 249, and the second engaging portion 773 and the second engaged portion 774 are pressed by the pressing portion 751a, thereby making the transmission shaft 249 non-rotatable relative to the case 215.

[0159] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 751a does not engage the first brake B1 or the second brake B2, rotating the engaging rotatable member 755 in the second direction R2 causes the male thread portion 264 to move the pressing member 751 axially to the left side L toward the first brake B1, causing the pressing portion 751a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotatable member 755 in a first direction R1 opposite to the second direction R2 causes the male thread portion 264 to move the pressing member 751 axially away from the first brake B1, releasing the pressing of the pressing portion 751a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0160] On the other hand, by rotating the engaging rotatable member 755 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the male thread portion 264 moves the pressing member 751 axially toward the second brake B2, causing the pressing portion 751a to press the second brake B2 and place the second brake B2 in the second engaged state. Then, by rotating the engaging rotatable member 755 in the second direction R2 from the second engaged state in which the second brake B2 is engaged, the male thread portion 264 moves the pressing member 751 axially away from the second brake B2, releasing the pressing of the pressing portion 751a on the second brake B2 and placing the first brake B1 and the second brake B2 in the disengaged state.

[0161] As described above, according to the drive unit 710 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 751. This allows a single motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 751a, so there is no need to provide such a thrust bearing, and the drive unit 710 can be made smaller. According to this embodiment, a reasonable electric brake actuator that can be applied to a transmission can be obtained.

[0162] Furthermore, according to the drive unit 710 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 755 are arranged in this order in the axial direction around the rotational axis C1. Therefore, compared to when the engaging rotational member 755 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be made narrower, and the engaging mechanism 750 can be made more compact.

[0163] Furthermore, according to the drive unit 710 of this embodiment, a dog brake is used as the brake. This allows for lower costs compared to using a friction engagement element. Furthermore, since the brake can be applied without a dry type, a seal member is not required to separate the brake from the gear mechanism 240, or the partition wall 215c can be eliminated and the brake and gear mechanism 240 can be placed in the same room.

[0164] Eighth Embodiment Next, an eighth embodiment will be described with reference to Fig. 12. This embodiment differs from the second embodiment in that the configuration of the transmission 813 of the drive unit 810 is different, and the first brake B1 and the second brake B2 are dog brakes. However, other configurations are the same as those of the second embodiment, so the same reference numerals are used and detailed description will be omitted.

[0165] [Case Configuration] In this embodiment, a hub member 220 is provided inside the case 215. The hub member 220 has a hub portion 220a on the inner circumferential side. In addition, a central shaft member 819, which is an example of a support shaft member, is fixed to the cover 217 and is provided so as to protrude into the inside of the case 215 with the rotation axis C1 as its center.

[0166] [Engagement mechanism] In this embodiment, the engagement mechanism 850 performs two-stage gear shifting by switching the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path. The engagement mechanism 850 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 254, an engagement rotation member 855, a pressing member 851, and a threaded portion 862. The first brake B1, the second brake B2, and the engagement rotation member 855 are arranged in this order in the axial direction of the rotation axis C1. In this embodiment, the first brake B1 and the second brake B2 are dog brakes.

[0167] The engaging rotation member 855 has a substantially cylindrical shape, is rotatably mounted on the central shaft member 819, and is rotated on the rotation axis C1 by the motor 253. That is, the central shaft member 819 is fixedly supported by the case 215 and is disposed so as to penetrate the inner diameter side of the engaging rotation member 855. The transmission mechanism 254 has a pinion gear 254a fixed to the drive shaft of the motor 253, a transmission gear 254b meshing with the pinion gear 254a, and a transmission gear 254c meshing with the transmission gear 254b. The transmission gear 254c is coaxially integrated with the engaging rotation member 855 on the rotation axis C1. A thrust bearing 865 is interposed between the transmission gear 254c and the hub portion 220a in the axial direction, and a thrust bearing 266 is interposed between the transmission gear 254c and the cover 217. When the motor 253 is driven to rotate, the engagement rotation member 855 is rotated via the transmission mechanism 254 .

[0168] The pressing member 851 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 or the second brake B2. The pressing member 851 has a pressing portion 851a disposed between the first brake B1 and the second brake B2 in the axial direction, a facing portion 851b radially facing the engaging rotation member 855, and a drum-shaped connecting portion 851c. The pressing portion 851a can selectively press the first brake B1 or the second brake B2. The facing portion 851b has an inner circumferential surface facing the outer circumferential surface of the engaging rotation member 855. The connecting portion 851c is disposed movably in the axial direction relative to the case 215 and is disposed at a position (inner diameter side) different in the radial direction from the second brake B2, connecting the pressing portion 851a and the facing portion 851b. The connecting portion 851c has an external spline 851s formed on its outer circumferential surface. The external splines 851s engage with the internal splines 220s formed on the hub portion 220a, thereby making the pressing member 851 non-rotatable relative to the case 215 via the hub member 220. That is, the pressing member 851 is supported non-rotatable relative to the case 215 but movable in the axial direction by the spline engagement between the internal splines 220s and the external splines 851s.

[0169] The threaded portion 862 has a female threaded portion 863, which is an example of a threaded portion, formed on the inner surface of the opposing portion 851b of the pressing member 851, and a male threaded portion 864, which is an example of a threaded portion, formed on the outer surface of the engaging rotating member 855 and threaded into the female threaded portion 863.

[0170] In this embodiment, the transmission shaft 247 is the second rotating element, and has a drum-shaped drum portion 247a at its right R end, with a disk-shaped support member 858 attached to the right R end of the drum portion 247a so as to be non-rotatable relative to the shaft. In this embodiment, the transmission shaft 249 is the first rotating element, and has a disk-shaped support member 859 attached to its right R end so as to be non-rotatable relative to the shaft.

[0171] The first brake B1 is provided between the drum portion 247a of the transmission shaft 247 and the transmission shaft 249. The first brake B1 has a first fitting portion 871 and a first fitted portion 872. The first fitting portion 871 is integrated with the pressing portion 851a and is supported and arranged so as to be non-rotatable relative to the case 215. The first fitting portion 871 is an example of a first non-rotating portion and is arranged so as to be non-rotatable relative to the pressing portion 851a. The first fitted portion 872 is integrated with a support member 859 that is arranged so as to be non-rotatable relative to the transmission shaft 249 by a spline or the like and is arranged so as to be non-rotatable relative to the transmission shaft 249. The first fitted portion 872 is an example of a first rotating portion and is arranged so as to be non-rotatable relative to the transmission shaft 249 and is arranged so as to be able to fit with the first fitting portion 871. The first brake B1 can form a first power transmission path in the gear mechanism 240 by making the second ring gear 242R non-rotatable relative to the case 215 via the transmission shaft 249 and the transmission gear 248.

[0172] That is, the first brake B1 has a first engaging portion 871 (first non-rotating portion) that is arranged so as to be non-rotatable relative to the case 215, and a first engaged portion 872 (first rotating portion) that is arranged so as to be non-rotatable relative to the transmission shaft 249, and the first engaging portion 871 and the first engaged portion 872 are pressed by the pressing portion 851a, thereby making the transmission shaft 249 non-rotatable relative to the case 215.

[0173] The second brake B2 is provided between the drum portion 247a and the pressing member 851. The second brake B2 has a second fitting portion 873 and a second fitted portion 874. The second fitting portion 873 is integrated with the pressing portion 851a, and is supported and arranged so as to be non-rotatable relative to the case 215. The second fitting portion 873 is an example of a second non-rotating portion, and is arranged so as to be non-rotatable relative to the pressing portion 851a. The second fitted portion 874 is integrated with a support member 859 that is arranged so as to be non-rotatable relative to the transmission shaft 247, and is arranged so as to be non-rotatable relative to the transmission shaft 247. The second fitted portion 874 is an example of a second rotating portion, and is arranged so as to be non-rotatable relative to the transmission shaft 247, and is arranged so as to be able to fit with the second fitting portion 873. The second brake B2 can form a second power transmission path in the gear mechanism 240 by making the first ring gear 241R non-rotatable relative to the case 215 via the transmission shaft 247 and the transmission gear 246.

[0174] That is, the second brake B2 has a second engaging portion 873 (second non-rotating portion) that is arranged so as to be non-rotatable relative to the case 215, and a second engaged portion 874 (second rotating portion) that is arranged so as to be non-rotatable relative to the transmission shaft 247, and the second engaging portion 873 and the second engaged portion 874 are pressed by the pressing portion 851a, thereby making the transmission shaft 247 non-rotatable relative to the case 215.

[0175] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 851a does not engage the first brake B1 or the second brake B2, rotating the engaging rotatable member 855 in the second direction R2 causes the male thread portion 864 to move the pressing member 851 axially to the left side L toward the first brake B1, causing the pressing portion 851a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotatable member 855 in a first direction R1 opposite to the second direction R2 causes the male thread portion 864 to move the pressing member 851 axially away from the first brake B1, releasing the pressing of the pressing portion 851a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0176] On the other hand, by rotating the engaging rotatable member 855 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the male thread portion 864 moves the pressing member 851 axially toward the second brake B2, causing the pressing portion 851a to press the second brake B2, thereby placing the second brake B2 in a second engaged state. Then, by rotating the engaging rotatable member 855 in the second direction R2 from the second engaged state in which the second brake B2 is engaged, the male thread portion 864 moves the pressing member 851 axially away from the second brake B2, releasing the pressing of the pressing portion 851a on the second brake B2 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0177] As described above, according to the drive unit 810 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 851. This allows one motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 851a, so there is no need to provide such a thrust bearing, and the drive unit 810 can be made smaller. According to this embodiment, a reasonable electric brake actuator that can be applied to a transmission can be obtained.

[0178] Furthermore, according to the drive unit 810 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 855 are arranged in this order in the axial direction around the rotational axis C1. Therefore, compared to when the engaging rotational member 855 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be made narrower, and the engaging mechanism 850 can be made more compact.

[0179] Furthermore, according to the drive unit 810 of this embodiment, the connecting portion 851c of the pressing member 851 passes through the inner periphery side of the second brake B2, so that the pressing member 851 can be made smaller.

[0180] Furthermore, according to the drive unit 810 of this embodiment, a dog brake is used as the brake. This allows for lower costs compared to using a friction engagement element. Furthermore, since it can be applied to a system other than a dry system, it is not necessary to use a seal member to separate the brake from the gear mechanism 240, or it is possible to eliminate the partition wall 215c and place the brake and gear mechanism 240 in the same room.

[0181] <Ninth embodiment> Next, a ninth embodiment will be described with reference to Figure 13. This embodiment differs from the second embodiment in the configuration of the engagement mechanism 950 in the transmission 913 of the drive unit 910. However, other configurations are the same as those in the second embodiment, so the same reference numerals will be used and detailed description will be omitted.

[0182] [Case Configuration] In this embodiment, a support plate 919, which is an example of a support member fixedly supported to the case 215, is provided in the first chamber 215a of the case 215 to the right R of the second brake B2. The support plate 919 is, for example, a substantially circular plate-like member whose thickness direction is in the axial direction of the rotation axis C1, and its outer periphery is non-rotatably attached to the inner circumferential surface of the case 215. A substantially annular stopper member 922 fitted to the inner circumferential surface of the case 215 is provided on the right side R of the support plate 919 in abutting relation thereto. The cover 217 has a bearing portion 217a that opens to the first chamber 215a side and is a cylindrical recess centered on the rotation axis C1.

[0183] [Engagement mechanism] In this embodiment, the engagement mechanism 950 performs two-stage gear shifting by switching the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path. The engagement mechanism 950 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 954, an engagement rotation member 955, a pressing member 951, and a threaded portion 962. The first brake B1, the second brake B2, and the engagement rotation member 955 are arranged in this order in the axial direction of the rotation axis C1.

[0184] The engaging rotation member 955 has a generally cylindrical shape, is rotatably mounted via a bearing on the bearing portion 217a of the cover 217, and is rotated on the rotation axis C1 by the motor 253. The transmission mechanism 954 has a pinion gear 954a fixed to the drive shaft of the motor 253, a transmission gear 954b meshing with the pinion gear 954a, a transmission gear 954c that is coaxially integrated with the transmission gear 954b and has a smaller diameter than the transmission gear 954b, and a transmission gear 954d that meshes with the transmission gear 954c. The transmission gear 954d is coaxially integrated with the engaging rotation member 955 on the rotation axis C1.

[0185] The engaging rotation member 955 has a flange portion 955a that is centered on the rotation axis C1 at a location on the left side L and faces the support plate 919 toward the left side L. A thrust bearing 265 is interposed axially between the flange portion 955a of the engaging rotation member 955 and the support plate 919, and a thrust bearing 266 is interposed between the transmission gear 954d and the cover 217. When the motor 253 is driven to rotate, the engaging rotation member 955 is rotated via the transmission mechanism 954. In this embodiment, the end portion of the engaging rotation member 955 on the left side L is not particularly supported, but this is not limited thereto. For example, the engaging rotation member 955 may be rotatably supported in an opening provided in the center of the support plate 919 (see FIG. 14 ).

[0186] The pressing member 951 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 and the second brake B2. The pressing member 951 has a pressing portion 951a provided between the first brake B1 and the second brake B2 in the axial direction, an opposing portion 951b radially opposing the engaging rotation member 955, and a connecting portion 951c. In this embodiment, the pressing member 951 is an example of a drum-shaped member, and has a cylindrical connecting portion 951c (drum portion) disposed on the outer diameter side of one of the first brake B1 and the second brake B2 (here, second brake B2), and is rotatable about the rotation axis C1.

[0187] The pressing portion 951a can selectively press the first brake B1 or the second brake B2. The opposing portion 951b has an outer circumferential surface that faces the inner circumferential surface of the engaging rotation member 955. The connecting portion 951c is arranged to be freely movable in the axial direction relative to the case 215, is arranged at a position (outer diameter side) that is different from the second brake B2 in the radial direction, and connects the pressing portion 951a and the opposing portion 951b. In this embodiment, the connecting portion 951c has a drum-shaped drum portion 951d connected to the pressing portion 951a, and a substantially disk-shaped disk portion 951e that connects the drum portion 951d and the opposing portion 951b.

[0188] A guide shaft 920 having a central axis in the axial direction is provided on the support plate 919 at at least one location in the circumferential direction (in this embodiment, multiple locations). Meanwhile, a guide hole 951f, through which the guide shaft 920 passes in the axial direction, is formed in the disk portion 951e of the connecting portion 951c of the pressing member 951. A plain bearing 921 is interposed between the guide shaft 920 and the guide hole 951f. By having the guide shaft 920 pass through the guide hole 951f, the axial movement of the pressing member 951 is guided and the pressing member 951 is prevented from rotating relative to the case 215. In other words, the guide shaft 920 is an example of a guide member, and is fixed to one of the support plate 919 and the disk portion 951e of the connecting portion 951c (the support plate 919 in this embodiment) and guides the other for free movement in the axial direction.

[0189] That is, the connecting portion 951c has a guide hole 951f which is an example of a through-portion that penetrates in the axial direction. The guide shaft 920 is an example of a support shaft, penetrates the guide hole 951f, is provided so as to be immovable in the axial direction relative to the case 215, and supports the flange portion 923a of the outer periphery side member 923 so as to be immovable in the axial direction relative to the case 215. Note that in the present embodiment, the case where the guide shaft 920 is fixed to the support plate 919 has been described, but the present invention is not limited to this, and the guide shaft 920 may be fixed to the disk portion 951e of the connecting portion 951c and movably guided relative to a guide hole formed in the support plate 919.

[0190] The threaded portion 962 has a male threaded portion 963, which is an example of a threaded portion, formed on the outer peripheral surface of the opposing portion 951b of the pressing member 951, and a female threaded portion 964, which is an example of a threaded portion, formed on the inner peripheral surface of the engaging rotating member 955 and which screws into the male threaded portion 963.

[0191] The first brake B1 has a first outer friction plate 271 (first non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215, and a first inner friction plate 272 (first rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 247, and the first outer friction plate 271 and the first inner friction plate 272 are pressed by the pressing portion 951a, making the transmission shaft 247 non-rotatable relative to the case 215.

[0192] The second brake B2 has a plurality of second outer friction plates 273 and a plurality of second inner friction plates 274. The plurality of second outer friction plates 273 and the plurality of second inner friction plates 274 are interposed radially between an outer peripheral side member 923 and an inner peripheral side member 259. The outer peripheral side member 923 is generally drum-shaped and has a flange portion 923a that protrudes inward at the end on the right side R. The flange portion 923a of the outer peripheral side member 923 is fixed to the guide shaft 920. In this embodiment, a plurality of guide shafts 920 are provided, and therefore the flange portions 923a are fixed to the guide shafts 920 at a plurality of locations around the rotation axis C1. As a result, the outer peripheral side member 923 is fixed to the case 215 via the guide shafts 920 and the support plate 919.

[0193] The multiple second outer friction plates 273 and the multiple second inner friction plates 274 are arranged alternately in the axial direction. The second outer friction plate 273 located on the rightmost side R of the second outer friction plates 273 is positioned and fixed toward the right side R with respect to the flange portion 923a. The second outer friction plate 273 located on the leftmost side L of the second outer friction plates 273 faces the pressing portion 951a in the axial direction.

[0194] In this embodiment, the flange portion 923a is an example of a pressure-receiving portion, and is arranged on the inner diameter side of the connecting portion 951c so as to be immovable axially relative to the case 215, and is positioned axially opposite the pressing portion 951a relative to the second brake B2, so as to receive the pressing force when the second brake B2 is engaged.

[0195] The second brake B2 has a second outer friction plate 273 (second non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215, and a second inner friction plate 274 (second rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 249, and the second outer friction plate 273 and the second inner friction plate 274 are pressed by the pressing portion 951a, making the transmission shaft 249 non-rotatable relative to the case 215.

[0196] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 951a does not engage the first brake B1 or the second brake B2, rotating the engaging rotation member 955 in the second direction R2 causes the female thread portion 964 to move the pressing member 951 axially to the left side L toward the first brake B1, causing the pressing portion 951a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotation member 955 in a first direction R1 opposite to the second direction R2 causes the female thread portion 964 to move the pressing member 951 axially away from the first brake B1, releasing the pressing of the pressing portion 951a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0197] On the other hand, by rotating the engaging rotation member 955 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the female thread portion 964 moves the pressing member 951 axially toward the second brake B2, causing the pressing portion 951a to press the second brake B2 and place the second brake B2 in the second engaged state. At this time, the pressing force received by the pressing portion 951a from the pressing portion 951a is received by the support plate 919 and the stopper member 922, and therefore a sufficient pressing force can be received. Then, by rotating the engaging rotation member 955 in the second direction R2 from a second engaged state in which the second brake B2 is engaged, the female thread portion 964 moves the pressing member 951 axially away from the second brake B2, releasing the pressing of the second brake B2 by the pressing portion 951a and placing the first brake B1 and the second brake B2 in the disengaged state.

[0198] As described above, according to the drive unit 910 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 951. This allows one motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 951a, so there is no need to provide such a thrust bearing, and the drive unit 910 can be made smaller. According to this embodiment, a reasonable electric brake actuator that can be applied to a transmission can be obtained.

[0199] Furthermore, according to the drive unit 910 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 955 are arranged in this order in the axial direction centered on the rotational axis C1. Therefore, compared to when the engaging rotational member 955 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be made narrower, and the engaging mechanism 950 can be made more compact.

[0200] Furthermore, according to the drive unit 910 of this embodiment, the opposing portion 951b and the engaging rotation member 955 are supported without using the central shaft member 419 as in the fourth embodiment. This allows the diameter of the threaded portion 962 to be smaller than when a central shaft member is used, and the engaging mechanism 950 can be made more compact.

[0201] <Tenth embodiment> Next, a tenth embodiment will be described with reference to Figure 14. This embodiment differs from the ninth embodiment in the configuration of the engagement mechanism 1050 in the transmission 1013 of the drive unit 1010. However, other configurations are the same as those of the second and ninth embodiments, so the same reference numerals will be used and detailed description will be omitted.

[0202] [Engagement mechanism] In this embodiment, the engagement mechanism 1050 performs two-stage gear shifting by switching the power transmission path formed by the gear mechanism 240 between a first power transmission path and a second power transmission path. The engagement mechanism 1050 has a first brake B1, a second brake B2, a motor 253 which is an example of an engagement drive source, a transmission mechanism 1054, an engagement rotation member 1055, a pressing member 1051, and a threaded portion 962. The first brake B1, the second brake B2, and the engagement rotation member 1055 are arranged in this order in the axial direction of the rotation axis C1.

[0203] The cover 217 has a bearing portion 217b that penetrates in the axial direction centered on the rotation axis C1. The engaging rotation member 1055 is generally cylindrical and rotatably mounted on the bearing portion 217b of the cover 217 via a bearing, and is rotated on the rotation axis C1 by the motor 253. The transmission mechanism 1054 has a pinion gear 1054a fixed to the drive shaft of the motor 253, a transmission gear 1054b that meshes with the pinion gear 1054a, a transmission gear 1054c that is coaxially integrated with the transmission gear 1054b and has a smaller diameter than the transmission gear 1054b, and a transmission gear 1054d that meshes with the transmission gear 1054c. The transmission gear 1054d is coaxially integrated with the engaging rotation member 1055 on the rotation axis C1.

[0204] The support plate 919 has a support hole 919a that penetrates and is centered on the rotation axis C1. The left end portion L of the engaging rotation member 1055 is rotatably supported by the support hole 919a of the support plate 919 via a bearing. The engaging rotation member 1055 also has a flange portion 1055a that is centered on the rotation axis C1 at a portion on the left side L and faces the support plate 919 toward the left side L. A thrust bearing 265 is interposed axially between the flange portion 1055a of the engaging rotation member 1055 and the support plate 919, and a thrust bearing 266 is interposed between the transmission gear 1054d and the cover 217. When the motor 253 is driven to rotate, the engaging rotation member 1055 is rotated via the transmission mechanism 1054. Further, the engaging rotation member 1055 is provided with a substantially cylindrical lid portion 1055b attached to the inner periphery of the end portion of the right side R, which closes the right side R.

[0205] The pressing member 1051 is disposed movably in the axial direction of the rotation axis C1 and selectively presses the first brake B1 and the second brake B2. The pressing member 1051 has a pressing portion 1051a provided between the first brake B1 and the second brake B2 in the axial direction, a facing portion 1051b facing the engaging rotation member 1055 in the radial direction, and a connecting portion 1051c. In this embodiment, the pressing member 1051 is an example of a drum-shaped member, and has a cylindrical connecting portion 1051c (drum portion) disposed on the outer diameter side of one of the first brake B1 and the second brake B2 (here, second brake B2), and is rotatable about the rotation axis C1.

[0206] The pressing portion 1051a can selectively press the first brake B1 or the second brake B2. The facing portion 1051b has an outer circumferential surface that faces the inner circumferential surface of the engaging rotation member 1055. The facing portion 1051b is housed in the inner circumferential portion of the engaging rotation member 1055 and is supported via a bearing so as to be rotatable relative to the inner circumferential surface of the engaging rotation member 1055.

[0207] The connecting portion 1051c is disposed axially movably relative to the case 215, is disposed at a different position (outer diameter side) radially from the second brake B2, and connects the pressing portion 1051a and the opposing portion 1051b. In this embodiment, the connecting portion 1051c has a drum-shaped drum portion 1051d connected to the pressing portion 1051a, and a substantially circular plate-shaped disk portion 1051e connecting the drum portion 1051d and the opposing portion 1051b. The drum portion 1051d has an external spline 1051g formed on its outer circumferential surface. This external spline 1051g engages with an internal spline 215s formed on the inner circumferential surface of the case 215, thereby preventing the pressing member 1051 from rotating relative to the case 215. That is, the pressing member 1051 is supported by the case 215 so as to be non-rotatable but axially movable due to spline engagement between the internal spline 215s and the external spline 1051g.

[0208] The support plate 919 is provided with a guide shaft 920 with its central axis in the axial direction at at least one location in the circumferential direction (in this embodiment, multiple locations). Meanwhile, a through hole 1051f through which the guide shaft 920 passes in the axial direction is formed in the disk portion 1051e of the connecting portion 1051c of the pressing member 1051. A gap is provided between the guide shaft 920 and the through hole 1051f. Alternatively, even if there is no gap, the guide shaft 920 is able to move in the axial direction relative to the through hole 1051f. Furthermore, a substantially annular member 1023 is attached to the end portion on the left side L of the guide shaft 920 and is centered on the rotation axis C1.

[0209] The screw portion 962 has a male screw portion 963, which is an example of a screw-engagement portion, formed on the outer peripheral surface of the opposing portion 1051b of the pressing member 1051, and a female screw portion 964, which is an example of a threaded portion, formed on the inner peripheral surface of the engaging rotating member 1055 and which screws into the male screw portion 963.

[0210] The first brake B1 has a first outer friction plate 271 (first non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215, and a first inner friction plate 272 (first rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 247, and the first outer friction plate 271 and the first inner friction plate 272 are pressed by the pressing portion 1051a, making the transmission shaft 247 non-rotatable relative to the case 215.

[0211] The second brake B2 has a plurality of second outer friction plates 273 and a plurality of second inner friction plates 274. The plurality of second outer friction plates 273 and the plurality of second inner friction plates 274 are provided radially between the drum portion 1051d and the inner peripheral side member 259. The plurality of second outer friction plates 273 and the plurality of second inner friction plates 274 are arranged alternately in the axial direction. The second outer friction plate 273 located on the rightmost side R of the second outer friction plates 273 is positioned and fixed toward the right side R with respect to the annular member 1023. The second outer friction plate 273 located on the leftmost side L of the second outer friction plates 273 faces the pressing portion 1051a in the axial direction.

[0212] In this embodiment, the circular member 1023 is an example of a pressure-receiving portion, and is provided on the inner diameter side of the connecting portion 1051c so as to be immovable in the axial direction relative to the case 215. The circular member 1023 is disposed on the axially opposite side of the pressing portion 1051a with respect to the second brake B2, and receives the pressing force when the second brake B2 is engaged. That is, the connecting portion 1051c has a through-hole 1051f, which is an example of a through-portion that penetrates in the axial direction. The guide shaft 920 is an example of a support shaft, and passes through the through-hole 1051f and is provided so as to be immovable in the axial direction relative to the case 215, supporting the circular member 1023 so as to be immovable in the axial direction relative to the case 215.

[0213] The second brake B2 has a second outer friction plate 273 (second non-rotating portion) whose outer diameter side is arranged so as not to rotate relative to the case 215 via the drum portion 1051d, and a second inner friction plate 274 (second rotating portion) whose inner diameter side is arranged so as not to rotate relative to the transmission shaft 249, and the second outer friction plate 273 and the second inner friction plate 274 are pressed by the pressing portion 1051a, making the rotation of the transmission shaft 249 non-rotating relative to the case 215.

[0214] [Brake engagement / disengagement] Next, the engagement and disengagement operations of the first brake B1 and the second brake B2 will be described. From a disengaged state in which the pressing portion 1051a does not engage the first brake B1 or the second brake B2, rotating the engaging rotation member 1055 in the second direction R2 causes the female thread portion 964 to move the pressing member 1051 axially to the left side L toward the first brake B1, causing the pressing portion 1051a to press the first brake B1 and place the first brake B1 in a first engaged state. Then, from a first engaged state in which the first brake B1 is engaged, rotating the engaging rotation member 1055 in a first direction R1 opposite to the second direction R2 causes the female thread portion 964 to move the pressing member 1051 axially away from the first brake B1, releasing the pressing of the pressing portion 1051a on the first brake B1 and placing the first brake B1 and the second brake B2 in a disengaged state.

[0215] On the other hand, by rotating the engaging rotation member 1055 in the first direction R1 from a disengaged state of the first brake B1 and the second brake B2, the female thread portion 964 moves the pressing member 1051 axially toward the second brake B2, causing the pressing portion 1051a to press the second brake B2 and place the second brake B2 in the second engaged state. At this time, the pressing force received by the pressing portion 951a on the second brake B2 is received by the support plate 919 and the stopper member 922, and therefore a sufficient pressing force can be received. Then, by rotating the engaging rotation member 1055 in the second direction R2 from a second engaged state in which the second brake B2 is engaged, the female thread portion 964 moves the pressing member 1051 axially away from the second brake B2, releasing the pressing of the second brake B2 by the pressing portion 1051a, and placing the first brake B1 and the second brake B2 in the disengaged state.

[0216] As described above, according to the drive unit 1010 of this embodiment, the first brake B1 and the second brake B2 can be selectively engaged by moving the pressing member 1051. This allows one motor to switch the engagement force of the two brakes, and both brakes are disengaged in the intermediate position, enabling a neutral mode. In a drive unit that selectively presses two engagement elements with a pressing member to switch the power transmission path, if there is relative rotation between the engagement elements and the pressing member, a thrust bearing must be provided between the engagement elements and the pressing member. However, according to this embodiment, there is no relative rotation between the brakes B1, B2 and the pressing portion 1051a, so there is no need to provide such a thrust bearing, and the drive unit 1010 can be made smaller. According to this embodiment, a reasonable electric brake actuator that can be applied to a transmission can be obtained.

[0217] Furthermore, according to the drive unit 1010 of this embodiment, the first brake B1, the second brake B2, and the engaging rotational member 1055 are arranged in this order in the axial direction centered on the rotational axis C1. Therefore, compared to when the engaging rotational member 1055 is arranged between the first brake B1 and the second brake B2, the distance between the first brake B1 and the second brake B2 can be made narrower, and the engaging mechanism 1050 can be made more compact.

[0218] Furthermore, according to the drive unit 1010 of this embodiment, the opposing portion 1051b and the engaging rotation member 1055 are supported without using the central shaft member 419 as in the fourth embodiment. This allows the diameter of the threaded portion 962 to be smaller than when a central shaft member is used, and the engaging mechanism 1050 can be made smaller.

[0219] The disclosure of the above-described embodiments also includes the following configuration examples and method examples. (Configuration 1) an input portion drivingly connected to a drive source; an output section drivingly connected to the wheels; a gear mechanism having a first rotating element and a second rotating element, and capable of forming a first power transmission path that drivingly connects the input unit and the output unit, and a second power transmission path that drivingly connects the input unit and the output unit and is different from the first power transmission path; a case that houses the gear mechanism; a first brake that can form the first power transmission path by making the first rotating element unrotatable relative to the case; a second brake capable of forming the second power transmission path by making the second rotating element unrotatable relative to the case; an engagement drive source; an engagement rotation member that is rotated on a rotation axis by the engagement drive source; a pressing member that is arranged to be movable in the axial direction of the rotation axis and that selectively presses the first brake and the second brake; a threaded portion having a screw-engaging portion formed on the pressing member and a threaded portion formed on the engaging rotation member and adapted to be screwed into the screw-engaging portion, a first engagement state in which the pressing member does not engage the first brake or the second brake, and a second engagement state in which the pressing member engages the first brake by rotating the engaging rotation member in a first direction, whereby the threaded portion moves the pressing member toward the first brake in the axial direction, and the pressing member presses the first brake, and By rotating the engaging rotation member from the first engaged state in a second direction opposite to the first direction, the threaded portion moves the pressing member away from the first brake in the axial direction, thereby releasing the pressing member from the first brake and entering the disengaged state, By rotating the engaging rotation member in the second direction from the disengaged state, the threaded portion moves the pressing member toward the second brake in the axial direction, and the pressing member presses the second brake, thereby entering a second engaged state in which the second brake is engaged, By rotating the engaging rotation member in the first direction from the second engaged state, the threaded portion moves the pressing member away from the second brake in the axial direction, thereby releasing the pressing member from the second brake and establishing the disengaged state. Power transmission device. (Configuration 2) the engaging rotary member is disposed between the first brake and the second brake in the axial direction, the first brake includes a first outer friction plate arranged non-rotatably relative to the case, and a first inner friction plate arranged non-rotatably relative to the first rotating element, the second brake includes a second outer friction plate arranged non-rotatably relative to the case, and a second inner friction plate arranged non-rotatably relative to the second rotating element, a transmission member that is drivingly connected to the engagement drive source and the engagement rotational member and transmits the rotational drive force from the engagement drive source to the engagement rotational member; a fixed member fixed to the case and supporting the first outer friction plate and the second outer friction plate so that they cannot rotate relative to each other, the engaging rotary member is disposed inside the fixed member, the engagement drive source is disposed outside the fixed member, the fixing member has a through-hole that penetrates from the inside to the outside, The transmission member is drivingly connected to the engagement rotation member via the through-hole. 2. The power transmission device according to claim 1. (Configuration 3) the first brake, the second brake, and the engaging rotary member are arranged in this order in the axial direction, the pressing member has: a pressing portion that is provided between the first brake and the second brake in the axial direction and that selectively presses the first brake and the second brake; an opposing portion that faces the engaging rotation member in the radial direction; and a connecting portion that is arranged to be free to move in the axial direction relative to the case and that passes through a position that is radially different from the second brake and that connects the opposing portion and the pressing portion, the first brake has a first non-rotating portion provided so as to be non-rotatable relative to the case and a first rotating portion provided so as to be non-rotatable relative to the first rotating element, and the first non-rotating portion and the first rotating portion are pressed by the pressing portion to make the first rotating element non-rotatable relative to the case; the second brake has a second non-rotating portion provided so as to be non-rotatable relative to the connecting portion, and a second rotating portion provided so as to be non-rotatable relative to the second rotating element, and the second non-rotating portion and the second rotating portion are pressed by the pressing portion to make the second rotating element non-rotatable relative to the case; The threaded portion has the threaded portion formed on the opposing portion and the threaded portion formed on the engaging rotation member. 2. The power transmission device according to claim 1. (Configuration 4) the first non-rotating portion is a first outer friction plate whose outer diameter side is supported so as not to rotate relative to the case, the first rotating portion is a first inner friction plate whose inner diameter side is supported so as not to rotate relative to the first rotating element, the second non-rotating portion is a second outer friction plate whose outer diameter side is supported so as not to rotate relative to the case, the second rotating portion is a second inner friction plate whose inner diameter side is supported so as not to rotate relative to the second rotating element, The connecting portion passes through an outer diameter side of the second brake and connects the opposing portion and the pressing portion. 4. The power transmission device according to claim 3. (Configuration 5) the opposing portion has an inner circumferential surface opposing an outer circumferential surface of the engaging rotation member, The threaded portion has the threaded portion formed on the inner circumferential surface of the opposing portion and the threaded portion formed on the outer circumferential surface of the engaging rotation member. 5. The power transmission device according to claim 4. (Configuration 6) the opposing portion has an outer circumferential surface opposing an inner circumferential surface of the engaging rotation member, The threaded portion has the threaded portion formed on the outer peripheral surface of the opposing portion and the threaded portion formed on the inner peripheral surface of the engaging rotation member. 5. The power transmission device according to claim 4. (Configuration 7) a shaft portion fixedly supported by the case and disposed to penetrate the inner diameter side of the engaging rotation member; a flange portion formed in a flange shape on an outer diameter side of the shaft portion; a guide member fixed to one of the flange portion and the connecting portion and movably guiding the other of the flange portion and the connecting portion in the axial direction, 6. The power transmission device according to claim 5. (Configuration 8) the case has an internal spline; The coupling portion has an external spline, the pressing member is supported by the case so as to be non-rotatable and movably in the axial direction by spline engagement between the internal spline and the external spline; 4. The power transmission device according to claim 3. (Configuration 9) a hub member fixedly supported by the case and disposed on an inner diameter side of the second brake; a support shaft member fixedly supported by the case and disposed to penetrate an inner diameter side of the engaging rotation member, the first non-rotating portion is a first inner friction plate whose inner diameter side is supported so as not to rotate relative to the support shaft member, the first rotating portion is a first outer friction plate whose outer diameter side is supported so as not to rotate relative to the first rotating element, the second non-rotating portion is a second inner friction plate whose inner diameter side is supported so as not to rotate relative to the hub member, the second rotating portion is a second outer friction plate whose outer diameter side is supported so as not to rotate relative to the second rotating element, the connecting portion passes through an inner diameter side of the second brake and connects the opposing portion and the pressing portion. 4. The power transmission device according to claim 3. (Configuration 10) The hub member has an internal spline; The coupling portion has an external spline, the pressing member is supported by the case so as to be non-rotatable and movably in the axial direction by spline engagement between the internal spline and the external spline; 10. The power transmission device according to claim 9. (Configuration 11) the first non-rotating portion is a first fitting portion that is provided so as not to rotate relative to the pressing portion, the first rotating portion is a first fitted portion that is provided so as not to rotate relative to the first rotating element and into which the first fitting portion can be fitted, the second non-rotating portion is a second fitting portion that is provided so as not to rotate relative to the pressing portion, the second rotating portion is a second fitted portion that is provided so as not to rotate relative to the second rotating element and into which the second fitting portion can be fitted, The connecting portion passes through an outer diameter side of the second brake and connects the opposing portion and the pressing portion. 4. The power transmission device according to claim 3. (Configuration 12) the case has an internal spline; The coupling portion has an external spline, the pressing member is supported by the case so as to be non-rotatable and movably in the axial direction by spline engagement between the internal spline and the external spline; 12. The power transmission device according to claim 11. (Configuration 13) a hub member fixedly supported by the case and disposed on an inner diameter side of the second brake; a support shaft member fixedly supported by the case and disposed to penetrate an inner diameter side of the engaging rotation member, the first non-rotating portion is a first fitting portion that is provided so as not to rotate relative to the pressing portion, the first rotating portion is provided so as not to rotate relative to the first rotating element, and the first fitting portion is a first fitted portion that can be fitted with the first fitting portion and is provided so as not to rotate relative to the first rotating element, the second non-rotating portion is a second fitting portion that is provided so as not to rotate relative to the pressing portion, the second rotating portion is provided so as not to rotate relative to the second rotating element, and is a second fitted portion into which the second fitting portion can be fitted and which is provided so as not to rotate relative to the second rotating element, the connecting portion passes through an inner diameter side of the second brake and connects the opposing portion and the pressing portion. 4. The power transmission device according to claim 3. (Configuration 14) The hub member has an internal spline; The coupling portion has an external spline, the pressing member is supported by the case so as to be non-rotatable and movably in the axial direction by spline engagement between the internal spline and the external spline; 14. The power transmission device according to claim 13. (Configuration 15) The case is a first chamber that accommodates the first brake and the second brake; a second chamber that houses the gear mechanism; a partition wall separating the first chamber and the second chamber, 2. The power transmission device according to claim 1. [Explanation of symbols]

[0220] 3L, 3R...front wheels (wheels), 11L, 11R...drive shaft (output portion), 12...motor (driving source), 13...transmission device (power transmission device), 15, 215...case, 18...rotor shaft (input portion), 23...fixing member, 23a...through portion, 40...gear mechanism, 41R...first ring gear (first rotating element), 42R...second ring gear (second rotating element), 51...first pressing shaft (pressing member), 52P...first engaging gear (engaging rotating member, first engaging rotating member), 52S...sun gear, 52Sa...external teeth, 61...small diameter gear (transmission member), 62...first screw portion, 63...first male thread portion (threaded portion, first threaded portion), 64...first female thread portion (threaded portion, first threaded portion), 71...first outer friction plate, 72...first inner friction plate, 73...second outer friction plate, 74...second inner friction plate, 219a, 419a, 519a, 619a...disk portion (pressure receiving portion), 247...transmission shaft (first rotating element), 249...transmission shaft (second rotating element), 251, 351, 451, 551, 651, 751, 851, 951, 1051...pressure member (drum-shaped member), 251a, 351a, 451a, 551a, 651a, 751a, 851a, 951a ,1051a...pressing part, 251b,351b,451b,551b,651b,751b,851b,951b,1051b...opposing part, 251c,351c,451c,551c,651c,751c,851c,951c,1051c...connecting part (drum part), 253...Motor (drive source for engagement), 255,355,455,555,655,755,855,955,1055...Rotating member for engagement, 262,362,462,662,862...Threaded part, 263,363,663,863...Female threaded part (screwed part), 264,364 , 664, 864... male thread portion (threaded portion), 271... first outer friction plate (first friction plate), 272... first inner friction plate (second friction plate), 273... second outer friction plate (third friction plate), 274... second inner friction plate (fourth friction plate), 319... support member (pressure receiving portion), 463... male thread portion (threaded portion), 464... female thread portion (threaded portion), 919... support plate (support member), 920... guide shaft (support shaft), 923a... flange portion (pressure receiving portion), 951c... guide hole (through portion), 1023... annular member (pressure receiving portion), B1... first brake, B2... second brake, C1... rotation axis

Claims

1. an input portion drivingly connected to a drive source; an output section drivingly connected to the wheels; a gear mechanism having a first rotating element and a second rotating element, and capable of forming a first power transmission path that drivingly connects the input unit and the output unit, and a second power transmission path that drivingly connects the input unit and the output unit and is different from the first power transmission path; a case that houses the gear mechanism; a first brake that can form the first power transmission path by making the first rotating element unrotatable relative to the case; a second brake capable of forming the second power transmission path by making the second rotating element unrotatable relative to the case; an engagement drive source; an engagement rotation member that is rotated on a rotation axis by the engagement drive source; a pressing member that is arranged to be movable in the axial direction of the rotation axis and that selectively presses the first brake and the second brake; a threaded portion having a screw-engaging portion formed on the pressing member and a threaded portion formed on the engaging rotation member and adapted to be screwed into the screw-engaging portion, a first engagement state in which the pressing member does not engage the first brake or the second brake, and a second engagement state in which the pressing member engages the first brake by rotating the engaging rotation member in a first direction, whereby the threaded portion moves the pressing member toward the first brake in the axial direction, and the pressing member presses the first brake, and By rotating the engaging rotation member from the first engaged state in a second direction opposite to the first direction, the threaded portion moves the pressing member away from the first brake in the axial direction, thereby releasing the pressing member from the first brake and entering the disengaged state, By rotating the engaging rotation member in the second direction from the disengaged state, the pressing member is moved in the axial direction toward the second brake by the threaded portion, and the pressing member presses the second brake, thereby entering a second engaged state in which the second brake is engaged, By rotating the engaging rotation member in the first direction from the second engaged state, the threaded portion moves the pressing member away from the second brake in the axial direction, thereby releasing the pressing member from the second brake and establishing the disengaged state. Power transmission device.

2. the engaging rotary member is disposed between the first brake and the second brake in the axial direction, the first brake includes a first outer friction plate arranged non-rotatably relative to the case, and a first inner friction plate arranged non-rotatably relative to the first rotating element, the second brake includes a second outer friction plate arranged non-rotatably relative to the case, and a second inner friction plate arranged non-rotatably relative to the second rotating element, a transmission member that is drivingly connected to the engagement drive source and the engagement rotational member and transmits the rotational drive force from the engagement drive source to the engagement rotational member; a fixed member fixed to the case and supporting the first outer friction plate and the second outer friction plate so that they cannot rotate relative to each other, the engaging rotary member is disposed inside the fixed member, the engagement drive source is disposed outside the fixed member, the fixing member has a through-hole that penetrates from the inside to the outside, The transmission member is drivingly connected to the engagement rotation member via the through-hole. The power transmission device according to claim 1 .

3. the first brake, the second brake, and the engaging rotary member are arranged in this order in the axial direction, the pressing member has: a pressing portion that is provided between the first brake and the second brake in the axial direction and that selectively presses the first brake and the second brake; an opposing portion that faces the engaging rotation member in the radial direction; and a connecting portion that is arranged to be freely movable in the axial direction relative to the case and that passes through an outer diameter side or an inner diameter side of the second brake and connects the opposing portion and the pressing portion, a drum-shaped member having a cylindrical drum portion arranged on an outer diameter side of one of the first brake and the second brake, the drum-shaped member being rotatable around the rotation axis; a pressure-receiving portion that is provided on an inner diameter side of the drum portion so as to be immovable in the axial direction relative to the case, that is disposed on the opposite side of the one brake from the pressing portion in the axial direction, and that receives a pressing force when the one brake is engaged, the first brake includes a first friction plate supported non-rotatably relative to the case and a second friction plate supported non-rotatably relative to the first rotating element, and the first friction plate and the second friction plate are pressed against the pressing portion to prevent the first rotating element from rotating relative to the case; the second brake includes a third friction plate supported non-rotatably relative to the case and a fourth friction plate supported non-rotatably relative to the second rotating element, and the third friction plate and the fourth friction plate are pressed against the pressing portion to prevent the second rotating element from rotating relative to the case; The threaded portion has the threaded portion formed on the opposing portion and the threaded portion formed on the engaging rotation member. The power transmission device according to claim 1 .

4. the opposing portion has an outer circumferential surface opposing an inner circumferential surface of the engaging rotation member, The threaded portion has the threaded portion formed on the outer peripheral surface of the opposing portion and the threaded portion formed on the inner peripheral surface of the engaging rotation member. The power transmission device according to claim 3 .

5. the pressing member is the drum-shaped member, The connecting portion has a through portion that penetrates in the axial direction, a support shaft that passes through the through-hole, is provided so as to be immovable in the axial direction relative to the case, and supports the pressure-receiving portion so as to be immovable in the axial direction relative to the case; 5. The power transmission device according to claim 3 or 4.

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