power transmission device

Abstract

To output further larger torque to an output shaft of a transmission from an electric motor while suppressing the size enlargement and a weight increase of a device as a whole, in a power transmission device including a reduction gear for amplifying torque from the electric motor, and transmitting it to an end part of the output shaft of the transmission.SOLUTION: A power transmission device of the present disclosure includes a transmission, a power transmission member connected to an end part of an output shaft of the transmission, an electric motor arranged between the transmission and the power transmission member, a reduction gear for amplifying torque from the electric motor, and transmitting it to the output shaft, and a case. The reduction gear includes an input element connected to the electric motor, a fixing element fixed to the case, and an output element connected to the end part of the output shaft between the electric motor and the power transmission member. The output element supports the input element from the inside in a radial direction, and is rotatably supported by the case via a bearing disposed outside in the radial direction, and the end part of the output shaft to which the output element and the power transmission member are connected has a constant outside diameter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power transmission device including a transmission that changes the speed of power transmitted from an engine to an input member and outputs the power to an output shaft, and an electric motor that is connected to the output shaft via a reducer. [Background technology]

[0002] A known power transmission device includes a torque converter having a lock-up clutch and connected to an engine, a transmission connected to the torque converter, a clutch that connects an output shaft of the transmission to a drive shaft and disconnects the two, an electric motor disposed axially between the transmission and the clutch, and a reducer that amplifies torque from the electric motor and transmits it to the output shaft of the transmission (see, for example, Patent Document 1). The reducer of this power transmission device includes a sun gear connected to a rotor of the electric motor, a ring gear held by a housing, and a planetary carrier that supports multiple pinion gears meshing with the sun gear and the ring gear. The reducer is also disposed axially between the electric motor and the clutch, and the planetary carrier is connected to the rear end of the output shaft of the transmission. In this power transmission device, by engaging the lock-up clutch and the clutch and placing the transmission in a power transmitting state, torque from the electric motor (assist torque) can be output to the output shaft of the transmission in addition to torque from the engine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent Application Publication No. 2007 / 0261901 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle including the above-described power transmission device, in order to output a higher assist torque from the electric motor to the output shaft of the transmission while suppressing an increase in the size of the electric motor, it is necessary to increase the reduction ratio of the reducer. However, Patent Document 1 does not disclose or suggest a specific structure for increasing the reduction ratio of the reducer.

[0005] Therefore, the main object of the present disclosure is to enable a power transmission device including a transmission, an electric motor, and a reducer that amplifies the torque from the electric motor and transmits it to the end of the output shaft of the transmission to output a greater torque from the electric motor to the output shaft of the transmission while suppressing an increase in size and weight of the entire device. [Means for solving the problem]

[0006] The power transmission device of the present disclosure includes a transmission that changes the speed of power transmitted from an engine to an input member and outputs the power to an output shaft, a power transmission member connected to an end of the output shaft opposite to the engine side, an electric motor arranged axially between the transmission and the power transmission member, a reducer that amplifies torque from the electric motor and transmits it to the output shaft, and a case that houses the transmission, the electric motor, and the reducer, wherein the reducer is a planetary gear mechanism that includes an input element that rotates integrally with a rotor of the electric motor, a fixed element fixed to the case, and an output element that is connected to the end of the output shaft between the electric motor and the power transmission member in the axial direction, and the output element supports the input element from the radially inner side and is rotatably supported by the case via a bearing arranged radially outward, and the end of the output shaft to which the output element and the power transmission member are connected is The outer diameter along the axial direction constant Yes This is what is done.

[0007] In the power transmission device disclosed herein, torque from the electric motor is amplified by a reducer and transmitted to an end of the output shaft of the transmission opposite the engine side, and the amplified torque is output together with the torque from the engine to a power transmission member connected to the end. The reducer is a planetary gear mechanism including an input element that rotates integrally with the rotor of the electric motor, a fixed element fixed to a case, and an output element. The output element of the reducer is connected to the end of the output shaft opposite the engine side between the electric motor and the power transmission member in the axial direction. The output element supports the input element from the radially inner side and is rotatably supported by the case via a bearing disposed radially outward, thereby rotatably supporting the end of the output shaft opposite the engine side (radially) by the case via the output element. Therefore, in the power transmission device disclosed herein, it is not necessary to expand the diameter of the end of the output shaft to restrict axial movement of the output shaft by the case via the bearing, as is the case when the end of the output shaft opposite the engine side is supported by the case via a bearing, and the outer diameter of the end can be made constant. This allows the inner diameter of the output element and the outer diameter of the portion of the output element that supports the input element to be reduced, thereby making it possible to reduce the diameter of the input element and the reference circle diameter of the input element.As a result, in the power transmission device of the present disclosure, it is possible to increase the reduction ratio of the reducer, thereby suppressing an increase in the size of the electric motor, i.e., an increase in the size and weight of the entire device, while outputting a greater torque to the output shaft of the transmission than the electric motor. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram showing a vehicle equipped with a power transmission device according to the present disclosure. [Figure 2] 1 is an enlarged view of a main portion of a power transmission device according to the present disclosure; [Figure 3] FIG. 10 is a schematic diagram showing a vehicle equipped with another power transmission device of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0010] FIG. 1 is a schematic diagram showing a vehicle V equipped with a power transmission device 1 according to the present disclosure. The vehicle V shown in the figure is a four-wheel drive vehicle based on rear-wheel drive that includes an engine (internal combustion engine) EG in addition to the power transmission device 1. In this embodiment, the engine EG is a multi-cylinder gasoline engine (e.g., a V6 engine) that converts the reciprocating motion of pistons resulting from the combustion of a mixture of gasoline (hydrocarbon-based fuel) and air in multiple combustion chambers (cylinders) into the rotational motion of a crankshaft. The engine EG includes an electronically controlled throttle valve, multiple intake and exhaust valves, a variable valve mechanism, multiple fuel injection valves, multiple spark plugs, an exhaust purification device, and the like (all not shown). Furthermore, a motor generator (not shown) is connected to the crankshaft of the engine EG to generate electricity using power from the engine EG and to crank the engine EG. However, the engine EG may be an LPG engine or a diesel engine.

[0011] As shown in FIG. 1 , the power transmission device 1 includes a starting device 2, a mechanical oil pump 3, an electric oil pump (not shown), a hydraulic control device 4, a transmission 5, a transfer 6, a motor / generator MG, a reducer 7, and a case 8 that houses these elements. The starting device 2 also includes a torque converter 21, a lock-up clutch 22, and a damper mechanism 23. The torque converter 21 includes a pump impeller connected to the crankshaft of the engine EG via a drive plate and a front cover, a turbine runner connected to an input member (input shaft) 5i of the transmission 5, and a stator that amplifies torque by rectifying the flow of hydraulic oil from the turbine runner to the pump impeller. The lock-up clutch 22 is a multi-plate or single-plate friction hydraulic clutch that connects and disconnects the front cover and the input member 5i of the transmission 5. The damper mechanism 23 includes multiple rotating elements and elastic bodies, and damps vibrations between the front cover and the input member 5i of the transmission 5. However, the starting device 2 may include a fluid coupling without a stator instead of the torque converter 21.

[0012] The mechanical oil pump 3 is a gear pump including an inner rotor (internal gear) connected to the pump impeller of the torque converter 21 and an outer rotor (external gear), and is driven by power from the engine EG. The mechanical oil pump 3 and the electric oil pump each draw in and discharge hydraulic oil (ATF) from an oil pan formed in the lower part of the case 8. The hydraulic control device 4 includes a valve body with multiple oil passages formed therein, multiple regulator valves, multiple linear solenoid valves, etc. The hydraulic control device 4 adjusts the pressure of the hydraulic oil (hydraulic pressure) from at least one of the mechanical oil pump 3 and the electric oil pump, and supplies it to the torque converter 21, the lock-up clutch 22, the hydraulic engagement elements of the transmission 5, various objects to be lubricated, etc.

[0013] The transmission 5 is, for example, a 6- to 10-speed multi-speed transmission that includes an input member 5i, an output member 5o, multiple planetary gear mechanisms, and multiple clutches and brakes (hydraulic engagement elements). The transmission 5 changes the speed of power (torque) transmitted from the engine EG to the input member 5i via either a torque converter 21 or a lock-up clutch 22, and outputs the power to the output member 5o. As shown in FIG. 1, a front end 51 of an output shaft 50 that extends toward the rear of the vehicle V and is on the engine EG side is connected (fixed) to the output member 5o of the transmission 5 via a spline.

[0014] The transfer 6 includes an input shaft (power transmission member) 6i, a front propeller shaft 6f (first shaft), a rear propeller shaft 6r (second shaft), an auxiliary transmission, a power distribution mechanism, a center differential mechanism, a differential lock mechanism, and the like (all not shown). As shown in FIG. 1 , the input shaft 6i of the transfer 6 is spline-coupled (fixed) to a rear end 52 of the output shaft 50 of the transmission 5, which is the end opposite the engine EG side. The transfer 6 distributes and transmits the power (torque) transmitted to the input shaft 6i to the front propeller shaft 6f (first shaft) and the rear propeller shaft 6r (second shaft). The power output to the front propeller shaft 6f by the transfer 6 is transmitted to the left and right front wheels Wf via a front differential gear 9f. The power output to the rear propeller shaft 6r by the transfer 6 is transmitted to the left and right rear wheels Wr via the rear differential gear 9r.

[0015] The motor generator MG is a synchronous generator motor (three-phase AC motor) including a rotor R with a permanent magnet embedded therein and a stator S around which a three-phase coil is wound, and is disposed axially between the transmission 5 and the transfer 6. The rotor R of the motor generator MG is fixed to a hollow motor shaft MS, through which an output shaft 50 of the transmission 5 is inserted. The motor generator MG is connected to a rear end 52 of the output shaft 50 via a speed reducer 7. The motor generator MG exchanges power with a battery (high-voltage battery) (not shown) via a power control unit (PCU) including an inverter, a boost converter, and the like (not shown), and operates as an electric motor driven by power from the battery to generate drive torque. The motor generator MG also operates as a generator that generates power using at least a portion of the power from the engine EG operated under load, and outputs regenerative braking torque when braking the vehicle V.

[0016] The reducer 7 is a single-pinion planetary gear mechanism (differential rotation mechanism) that includes a sun gear (input element) 71, a ring gear (fixed element) 72, and a planetary carrier (output element) 74 that rotatably supports a plurality of pinion gears 73, and is disposed axially between the motor generator MG and the transfer 6. The sun gear 71 of the reducer 7 is connected to the motor shaft MS so as to rotate integrally with the rotor R of the motor generator MG. The ring gear 72 is non-rotatably fixed to the case 8, which serves as a stationary member. The planetary carrier 74, together with the input shaft 6i of the transfer 6, is connected (fixed) to the rear end 52 of the output shaft 50 of the transmission 5 via a spline.

[0017] The case 8 of the power transmission device 1 includes a transmission case 80, a motor case 81, a gear case 82, and a transfer case 83. In this embodiment, the transmission case 80, the motor case 81, the gear case 82, and the transfer case 83 are all cast products made of, for example, an aluminum alloy or steel. The transmission case 80 houses the starting device 2, the mechanical oil pump 3, the transmission 5, etc., and is fastened (coupled) to the engine block of the engine EG via a plurality of bolts. The motor case 81 houses the motor generator MG, etc., and is fastened (coupled) to the rear end of the transmission case 80 via a plurality of bolts. The gear case 82 houses the reducer 7, etc., and is fastened (coupled) to the rear end of the motor case 81 via a plurality of bolts. The transfer case 83 houses the transfer 6, etc., and is fastened (coupled) to the rear end of the gear case 82 via a plurality of bolts.

[0018] According to the power transmission device 1 configured as described above, with the operation of the engine EG stopped, the lock-up clutch 22 disengaged, and the transmission 5 in a neutral state, the motor generator MG is driven by electric power from the battery, and torque (only) from the motor generator MG is transmitted to the output shaft 50, allowing the vehicle V to start and travel. Furthermore, with the transmission 5 in a power transmission state, the motor generator MG can be driven by electric power from the battery so as to output cranking torque while the lock-up clutch 22 is slip-engaged, thereby cranking the engine EG to start it.

[0019] After engine EG has been started, the engine EG can be operated, for example, at an operating point near the optimum fuel economy line, while the battery is charged with electric power generated by the motor generator MG according to the battery's SOC, and torque (assist torque) from the motor generator MG driven by electric power from the battery can be amplified by the reducer 7 and added to the torque from the engine EG to be output to the output shaft 50. Therefore, the power transmission device 1 can ensure good power performance of the vehicle V while improving the fuel economy of the engine EG.

[0020] FIG. 2 is an enlarged view of a main part showing the structure around the motor generator MG and the reducer 7 of the power transmission device 1. As shown in FIG.

[0021] As shown in FIG. 2, the motor case 81 has an annular support portion 81s extending radially inward from its inner circumferential surface. The stator S of the motor generator MG is non-rotatably fastened (fixed) to a base portion (thick portion) on the outer circumferential side of the support portion 81s via a plurality of bolts (not shown). The front end portion (left end portion in FIG. 2) of the motor shaft MS, which is fixed to the rotor R, on the engine EG side is rotatably (radially) supported by the inner circumferential portion of the support portion 81s via a bearing (ball bearing) Bmf. The rear end portion (right end portion in FIG. 2) of the motor shaft MS on the opposite side from the engine EG side is rotatably (radially) supported by a cover 82c of the gear case 82 via a bearing (ball bearing) Bmr. The cover 82c is fastened (fixed) to the gear case 82 via a plurality of bolts so as to close an opening of the motor case 81 on the opposite side from the engine EG side.

[0022] The opening of the motor case 81 on the engine EG side is closed by a cover 81c fastened (fixed) to the front end of the motor case 81 with multiple bolts. A space is defined between the cover 81c and a support portion 81s in the axial direction, and a resolver Rsv that detects the rotational position of the motor shaft MS, i.e., the rotor R, is disposed in this space. A lubrication / cooling pipe Plc with multiple oil holes is bridged between the support portion 81s of the motor case 81 and the cover 81c so as to be positioned radially outside and above the stator S. Hydraulic oil is supplied to the lubrication / cooling pipe Plc from the hydraulic control device 4 via oil passages formed in the motor case 81, oil passages formed in the cover 81c, and oil passages formed in the output shaft 50 and the output member 5o. This allows hydraulic oil, serving as a lubricating and cooling medium, to be supplied to the stator S and rotor R of the motor / generator MG from the multiple oil holes in the lubrication / cooling pipe Plc.

[0023] 2, the sun gear 71 of the reducer 7 includes a small-diameter portion fixed via a spline to the rear end of the motor shaft MS on the side opposite to the engine EG side, and a large-diameter portion on which a plurality of external teeth are formed. Furthermore, in this embodiment, the ring gear 72 of the reducer 7 is fitted to splines formed on the inner circumferential surface of a gear case 82 and is fixed non-rotatably to the gear case 82, i.e., the case 8, via a snap ring. The planetary carrier 74 of the reducer 7 includes a carrier body 740 and a carrier cover 741 that are fixed integrally to each other and support pinion shafts inserted through the plurality of pinion gears 73, and a carrier hub 742 that is fixed to the inner circumferential portion of the carrier body 740 so as to be located radially inward of the carrier body 740.

[0024] The carrier hub 742 of the planetary carrier 74 includes a cylindrical portion 743 and an annular flange portion 744 extending radially outward from the outer peripheral surface of the axial center portion of the cylindrical portion 743. As shown in the figure, the outer peripheral portion of the flange portion 744 of the carrier hub 742 is fixed to the inner peripheral portion of the carrier main body 740 by welding. In addition, a spline is formed on the inner peripheral surface of the cylindrical portion 743, and the spline of the cylindrical portion 743 is fitted with a spline SP formed on the rear end portion 52 into which the input shaft 6i of the transfer 6 is fitted. Then, as shown in FIG. 2, the cylindrical portion 743 of the planetary carrier 74 (carrier hub 742) is fitted with the spline SP on the rear end portion 52 of the output shaft 50. Furthermore, the rear end 52 of the output shaft 50 protrudes from the cylindrical portion 743 toward the rear side of the vehicle V (to the right in FIG. 2), and the input shaft 6i of the transfer 6 is fitted into the splines SP of the rear end 52 protruding from the cylindrical portion 743. As a result, the planetary carrier 74 and the input shaft 6i of the transfer 6 are connected to the rear end 52 so as to rotate integrally with the output shaft 50.

[0025] The outer peripheral surface of the front end portion of cylindrical portion 743 on the engine EG side (left side in FIG. 2) is formed into a cylindrical shape, and this front end portion of cylindrical portion 743 rotatably supports the inner peripheral surface of sun gear 71 (large diameter portion) from the radially inner side via bushing Bs. Furthermore, a thrust bearing Bt is arranged axially between the end face (right end face in FIG. 2) of sun gear 71 (large diameter portion) and flange portion 744 of carrier hub 742. The rear end portion of cylindrical portion 743 on the opposite side from the engine EG side (right side in FIG. 2) is rotatably supported (radially) by an annular support portion 82s extending radially inward from the inner peripheral surface of gear case 82, via a bearing (ball bearing) Bsr arranged radially outward.

[0026] As a result, the rear end 52 of the output shaft 50 on the opposite side to the engine EG side is rotatably (radially) supported by the gear case 82, i.e., the case 8, via the cylindrical portion 743 of the planetary carrier 74. In addition, in this embodiment, the front end 51 of the output shaft 50 on the engine EG side is rotatably (radially) supported by a cover 81c fixed to the motor case 81, i.e., the case 8, via a bearing (ball bearing) Bsf arranged radially outward. Furthermore, a snap ring SR is attached to the output shaft 50 on the engine EG side (left side in FIG. 2) so as to abut against an inner race Li of the bearing Bsf.

[0027] As described above, in the power transmission device 1, the torque (assist torque) from the motor generator MG is amplified by the reduction gear 7 and transmitted to the rear end 52 of the output shaft 50 of the transmission 5, which is on the side opposite to the engine EG side. The torque can then be output, together with the torque from the engine EG, to the input shaft 6i (power transmission member) of the transfer case 6, which is connected to the rear end 52. In addition, in the power transmission device 1, the planetary carrier 74, which is an output element of the reduction gear 7, is connected to the rear end 52 of the output shaft 50 axially between the motor generator MG and the input shaft 6i of the transfer case 6. Furthermore, the cylindrical portion 743 of the planetary carrier 74 rotatably supports the sun gear 71, which is an input element of the reduction gear 7, from the radially inner side and is rotatably supported by the case 8 (gear case 82) via the bearing Bsr disposed radially outward. Furthermore, the rear end 52 of the output shaft 50 is rotatably supported by the case 8 (gear case 82) via the planetary carrier 74 (cylindrical portion 743).

[0028] Therefore, in the power transmission device 1, unlike in the case where the rear end portion 52 of the output shaft 50 is supported by the case 8 via a bearing, it is not necessary to increase the diameter of the rear end portion 52 in order to restrict axial movement of the output shaft 50 by the case 8 via the bearing, and the outer diameter of the rear end portion 52 (the outer diameter of the crest portion of the spline SP) can be made constant. This makes it possible to reduce the inner diameter of the cylindrical portion 743 of the planetary carrier 74 and the outer diameter of the portion of the cylindrical portion 743 that supports the sun gear 71, thereby reducing the diameter of the sun gear 71 (the large-diameter portion having external teeth) and thereby reducing the reference circle diameter of the sun gear 71. As a result, in the power transmission device 1, it is possible to increase the reduction ratio of the reducer 7 (reference circle diameter of the ring gear 72 / reference circle diameter of the sun gear 71). This makes it possible to output a larger assist torque from the motor generator MG to the output shaft 50 of the transmission 5 while suppressing an increase in the size of the motor generator MG, i.e., an increase in the size and weight of the entire device.

[0029] Furthermore, in the power transmission device 1, the rear end 52 of the output shaft 50 of the transmission 5 is formed with splines SP into which the cylindrical portion 743 of the planetary carrier 74 and the input shaft 6i of the transfer case 6 are fitted. By sharing the splines SP of the rear end 52 into which the planetary carrier 74 and the input shaft 6i are fitted in this way, it is possible to reduce the processing cost of the output shaft 50 and improve the ease of assembling the planetary carrier 74 and the input shaft 6i to the output shaft 50.

[0030] Furthermore, a front end portion 51 of the output shaft 50 on the engine EG side is rotatably supported by the case 8 (cover 81c) via a bearing (second bearing) Bsf arranged radially outward, and a snap ring SR is attached to the output shaft 50 so as to abut against an inner race Li of the bearing Bsf on the engine EG side. This makes it possible for movement of the output shaft 50 in the direction from the engine EG side toward the input shaft 6i side to be restricted by the case 8 via the snap ring SR and the bearing Bsf.

[0031] Furthermore, in the power transmission device 1, the reducer 7 is a single-pinion planetary gear mechanism that includes a sun gear 71 as an input element, a ring gear 72 as a fixed element, and a planetary carrier 74 as an output element that supports a plurality of pinion gears 73 that mesh with the sun gear 71 and the ring gear 72. This makes it possible to increase the reduction ratio of the reducer 7 while suppressing an increase in the number of parts and an increase in the size and weight of the entire power transmission device 1.

[0032] However, reducer 7 may also be a double-pinion planetary gear mechanism including a sun gear as an input element, a ring gear as an output element, and a planetary carrier as a fixed element that holds multiple pairs of pinion gears that mesh with each other and where one meshes with the sun gear and the other with the ring gear, so that they can rotate (rotate) and revolve. In this case, the hub of the ring gear, which serves as the output element, is fitted into the splines on rear end 52 of output shaft 50, and the sun gear is supported radially by the hub.

[0033] Furthermore, the vehicle V on which the above-described power transmission device 1 is mounted is a four-wheel drive vehicle, and the rear end 52 of the output shaft 50 of the transmission 5 is connected to the input shaft 6i of the transfer case 6 as well as the planetary carrier 74 of the reduction gear 7, but the power transmission member connected to the rear end 52 of the output shaft 50 is not limited to the input shaft 6i. That is, as shown in Fig. 3, if the vehicle V is a rear-wheel drive vehicle and is equipped with a power transmission device 1B in which the transfer case 6 is omitted from the above-described power transmission device 1, a propeller shaft PS may be connected to the rear end 52 of the output shaft 50 as a power transmission member, and the output shaft 50 and the differential gear 9 may be connected via the propeller shaft PS.

[0034] As described above, the power transmission device of the present disclosure is a power transmission device (1, 1B) including a transmission (5) that changes the speed of power transmitted from an engine (EG) to an input member (5i) and outputs the power to an output shaft (50), a power transmission member (6i, PS) connected to an end (52) of the output shaft (50) opposite to the engine (EG) side, an electric motor (MG) arranged axially between the transmission (5) and the power transmission member (6i, PS), a reducer (7) that amplifies torque from the electric motor (MG) and transmits the amplified torque to the output shaft (50), and a case (8) that accommodates the transmission (5), the electric motor (MG), and the reducer (7), The planetary gear mechanism includes an input element (71) that rotates integrally with a rotor (R) of a motor (MG), a fixed element (72) fixed to the case (8, 82), and an output element (74) that is connected to the end (52) of the output shaft (50) between the electric motor (MG) and the power transmission member (6i, PS) in the axial direction, wherein the output element (74) supports the input element (71) from the radially inner side and is rotatably supported by the case (8) via a bearing (Bsr) arranged on the radially outer side, and the end (52) of the output shaft (50) to which the output element (74) and the power transmission member (6i, PS) are connected has a constant outer diameter.

[0035] In the power transmission device disclosed herein, torque from the electric motor is amplified by a reducer and transmitted to an end of the output shaft of the transmission opposite the engine side, and the amplified torque is output together with the torque from the engine to a power transmission member connected to the end. The reducer is a planetary gear mechanism including an input element that rotates integrally with the rotor of the electric motor, a fixed element fixed to a case, and an output element. The output element of the reducer is connected to the end of the output shaft opposite the engine side between the electric motor and the power transmission member in the axial direction. The output element supports the input element from the radially inner side and is rotatably supported by the case via a bearing disposed radially outward, thereby rotatably supporting the end of the output shaft opposite the engine side (radially) by the case via the output element. Therefore, in the power transmission device disclosed herein, it is not necessary to expand the diameter of the end of the output shaft to restrict axial movement of the output shaft by the case via the bearing, as is the case when the end of the output shaft opposite the engine side is supported by the case via a bearing, and the outer diameter of the end can be made constant. This allows the inner diameter of the output element and the outer diameter of the portion of the output element that supports the input element to be reduced, thereby making it possible to reduce the diameter of the input element and the reference circle diameter of the input element.As a result, in the power transmission device of the present disclosure, it is possible to increase the reduction ratio of the reducer, thereby suppressing an increase in the size of the electric motor, i.e., an increase in the size and weight of the entire device, while outputting a greater torque to the output shaft of the transmission than the electric motor.

[0036] The reducer (7) may also be a single-pinion planetary gear mechanism including a sun gear (71) as the input element, a ring gear (72) as the fixed element, and a planetary carrier (74) as the output element that supports a plurality of pinion gears (73) meshing with the sun gear (71) and the ring gear (72).

[0037] In a power transmission device including such a reducer, it is possible to increase the reduction ratio of the reducer while suppressing an increase in the number of parts and an increase in the size and weight of the entire device.

[0038] The end portion (52) of the output shaft (50) may be formed with splines (SP) into which the output element (74) and the power transmission member (6i, PS) are fitted.

[0039] In this way, by sharing the splines at the ends into which the output element and the power transmission member are fitted, it is possible to reduce the processing costs of the output shaft and improve the ease of assembly of the output element and the power transmission member to the output shaft.

[0040] In addition, the output shaft (50) may be rotatably supported by the case (8, 81c) via a second bearing (Bsf) arranged radially outward on the engine (EG) side, and a snap ring (SR) may be attached to the output shaft (50) so as to abut against an inner race (Li) of the second bearing (Bsf) on the engine (EG) side.

[0041] This makes it possible to restrict movement of the output shaft in the direction from the engine side toward the power transmission member side by the case via the snap ring and the second bearing.

[0042] Furthermore, the power transmission member may be an input shaft (6i) of a transfer (6) or a propeller shaft (PS) connecting the output shaft (50) of the transmission (5) and a differential gear (9).

[0043] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0044] The invention of the present disclosure can be used in the power transmission device and vehicle manufacturing industries, etc. [Explanation of symbols]

[0045] 1, 1B power transmission device, 2 starting device, 5 transmission, 5i input member, 5o output member, 50 output shaft, 51 front end, 52 rear end, 6 transfer, 6f front propeller shaft, 6i input shaft, 6r rear propeller shaft, 7 reducer, 71 sun gear, 72 ring gear, 73 pinion gear, 74 planetary carrier, 740 carrier body, 741 carrier cover, 742 carrier hub, 743 cylindrical portion, 744 flange portion, 8 case, 81 motor case, 81c cover, 81s support portion, 82 gear case, 82c cover, 82s support portion, 9 differential gear, 9f front differential gear, 9r rear differential gear, MG motor generator, R rotor, S stator, SP Spline, V vehicle.

Claims

1. A power transmission device including a transmission that changes the speed of power transmitted from an engine to an input member and outputs the power to an output shaft, a power transmission member that is connected to an end of the output shaft opposite to the engine side, an electric motor that is arranged axially between the transmission and the power transmission member, a reducer that amplifies torque from the electric motor and transmits it to the output shaft, and a case that houses the transmission, the electric motor, and the reducer, the reducer is a planetary gear mechanism including an input element that rotates integrally with the rotor of the electric motor, a fixed element that is fixed to the case, and an output element that is connected to the end of the output shaft between the electric motor and the power transmission member in the axial direction, the output element supports the input element from the radially inner side, and is rotatably supported by the case via a bearing arranged radially outward, A power transmission device in which the end of the output shaft to which the output element and the power transmission member are connected has a constant outer diameter along the axial direction.

2. 2. The power transmission device according to claim 1, The reducer is a power transmission device that is a single-pinion planetary gear mechanism that includes a sun gear as the input element, a ring gear as the fixed element, and a planetary carrier as the output element that supports a plurality of pinion gears that mesh with the sun gear and the ring gear.

3. 3. The power transmission device according to claim 1, A power transmission device in which the end of the output shaft is formed with a spline into which the output element and the power transmission member are fitted.

4. The power transmission device according to any one of claims 1 to 3, the output shaft is rotatably supported by the case via a second bearing disposed radially outward on the engine side, a snap ring attached to the output shaft so as to abut against an inner race of the second bearing on the engine side;

5. The power transmission device according to any one of claims 1 to 4, A power transmission device in which the power transmission member is an input shaft of a transfer case or a propeller shaft that connects the output shaft of the transmission and a differential gear.

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