transaxle

Abstract

To provide a transaxle that can efficiently cool the object to be cooled inside the case. [Solution] The transaxle includes an electric motor, a gear mechanism connected to the electric motor and including at least a differential gear, a case housing the electric motor and the gear mechanism, a pump for sucking in and discharging oil stored in the case, a connecting gear included in the gear mechanism, and a shaft that rotates integrally with the rotor of the electric motor, which is spaced axially apart from the connecting gear. The shaft includes a first oil passage formed in the shaft to guide oil, which is scraped up by at least one gear and supplied to the end of the shaft on the connecting gear side, to a predetermined object to be cooled in the case, a second oil passage formed in the shaft to guide oil, which is supplied from the pump to the end of the shaft on the rotor side, to the rotor, and a closing portion provided on the shaft to restrict communication between the first oil passage and the second oil passage.

Description

Technical Field

[0004] , , , , ,

[0001] The present disclosure relates to a transaxle mounted on a vehicle.

Background Art

[0002] A conventionally known hydraulic control device supplies oil from a mechanical oil pump driven by a drive source of a vehicle including at least an engine and an electric oil pump driven by an electric motor different from the drive source to an oil supply part of the vehicle such as first and second motor generators and a power split mechanism (see, for example, Patent Document 1). This hydraulic control device includes a first oil passage connected to the mechanical oil pump, a second oil passage connected to the electric oil pump, a first check valve, a second check valve, a third oil passage, and a throttle mechanism. The first check valve is provided between the confluence of the first and second oil passages and the mechanical oil pump and allows only the flow of oil from the mechanical oil pump to the oil supply part. The second check valve is provided between the confluence and the electric oil pump and allows only the flow of oil from the electric oil pump to the oil supply part. The third oil passage is provided between the confluence and the electric oil pump so as to bypass the second check valve and communicate the confluence and the electric oil pump. The throttle mechanism is provided in the third oil passage so as to regulate the flow rate of the oil discharged from the mechanical oil pump.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the conventional hydraulic control device described above, more oil can be supplied to the oil supply unit as a cooling medium from both the mechanical oil pump and the electric oil pump. However, if the temperature of the oil from the mechanical oil pump and the temperature of the oil from the electric oil pump are different, the oil temperature may become high at the junction of the first and second oil passages, which may prevent the oil supply unit from being cooled efficiently.

[0005] Therefore, the primary objective of this disclosure is to provide a transaxle that can efficiently cool the object to be cooled inside the case. [Means for solving the problem]

[0006] The transaxle of this disclosure is a transaxle mounted on a vehicle and includes an electric motor, a gear mechanism connected to the electric motor and including at least a differential gear, a case housing the electric motor and the gear mechanism, and a pump for drawing in and discharging oil stored in the case. Furthermore, the transaxle includes a coupling gear included in the gear mechanism and a shaft that rotates integrally with the rotor of the electric motor, which is spaced axially apart from the coupling gear. The shaft has a first oil passage, a second oil passage, and a closure. The first oil passage is formed in the shaft to guide oil, which has been scraped up by at least one gear included in the gear mechanism and supplied to the coupling gear side end of the shaft, to a predetermined object to be cooled in the case. The second oil passage is formed in the shaft to guide oil, which has been supplied from the pump to the rotor side end of the shaft, to the rotor. The closure is provided in the shaft to restrict communication between the first oil passage and the second oil passage.

[0007] This allows the oil in the first oil passage and the oil in the second oil passage to be guided from the first oil passage to a predetermined cooling target inside the case without mixing them, while the oil from the pump is guided from the second oil passage to the rotor of the electric motor, which is another cooling target inside the case. As a result, it is possible to suppress the temperature of one of the oils in the first oil passage and the other oil passage from rising due to the temperature rise of the other, thereby enabling efficient cooling of the predetermined cooling target and the electric motor inside the case. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing a vehicle including the transaxle of this disclosure. [Figure 2] This is an enlarged view of the main part of the transaxle shown in this disclosure. [Modes for carrying out the invention]

[0009] Next, with reference to the drawings, embodiments for carrying out the invention of this disclosure will be described.

[0010] Figure 1 is a schematic diagram showing a vehicle 1 including the transaxle 20 of this disclosure. The vehicle 1 shown in the figure is a front-wheel-drive hybrid vehicle including an engine (internal combustion engine) 10, a transaxle 20 which is a power transmission device connected to the engine 10 and includes motor generators MG1 and MG2, and a battery (energy storage device) (not shown) which exchanges power with the motor generators MG1 and MG2 of the transaxle 20. The engine 10 is a gasoline engine that burns a mixture of gasoline (hydrocarbon fuel) and air in multiple combustion chambers and converts the reciprocating motion of the pistons associated with the combustion of the mixture into rotational motion of the crankshaft. However, the engine 10 may be an LPG engine or a diesel engine.

[0011] As shown in Figure 1, the transaxle 20 includes, in addition to motor generators MG1 and MG2, a planetary gear 30, a differential gear 39, and a case 40 housing these elements. The motor generator MG1 (first motor) is a synchronous regenerative motor (three-phase AC motor) including a stator S1 and a rotor R1, and mainly operates as a generator that converts at least a portion of the power from the engine 10, which is under load operation, into electricity. The motor generator MG2 (second motor) is a synchronous regenerative motor (three-phase AC motor) including a stator S2 and a rotor R2, and mainly operates as a motor that generates driving torque, driven by power from at least one of the battery and the motor generator MG1. The motor generators MG1 and MG2 exchange power with the battery via a power control unit (PCU) (not shown) including an inverter, and also exchange power with each other via the power control unit.

[0012] The planetary gear 30 includes a sun gear (first rotating element) 31, a ring gear (second rotating element) 32, and a planetary carrier (third rotating element) 34 that rotatably supports a plurality of pinion gears 33. As shown in Figure 1, the sun gear 31 is connected to the rotor R1 of the motor generator MG1 via a hollow rotor shaft RS. The planetary carrier 34 is fixed coaxially to the carrier shaft CS and is connected to the crankshaft of the engine 10 via the carrier shaft CS and the damper mechanism 25. The ring gear 32 is integrated with a counter drive gear 35 as an output member, and the two rotate coaxially and as a single unit.

[0013] The counter drive gear 35 is connected to the left and right wheels (drive wheels) W via the counter driven gear 36 that meshes with the counter drive gear 35, the drive pinion gear (final drive gear) 37 that rotates integrally with the counter driven gear 36, the differential ring gear 39r that meshes with the drive pinion gear 37 and rotates integrally with the differential case of the differential gear 39, the differential gear 39, and the drive shaft DS. The gear mechanism of the transaxle 20, that is, the gear train from the planetary gear 30 and the counter drive gear 35 to the differential gear 39, connects the engine 10 and the motor generator MG1 to each other and transmits a portion of the output torque of the engine 10 as a power source to the drive shaft DS and the wheels W.

[0014] Furthermore, a connecting gear (reduction gear) 38 is connected (fixed) to the rotor R2 of the motor generator MG2 via a motor shaft MS, such that it is spaced apart from the rotor R2 in the axial direction of the motor shaft MS. In other words, the motor shaft MS rotates coaxially and integrally with the connecting gear 38 included in the gear mechanism of the transaxle 20 and the rotor R2 of the motor generator MG2, which is positioned spaced apart from the connecting gear 38 in the axial direction. The connecting gear 38 has fewer teeth than the counter-driven gear 36 and meshes with the counter-driven gear 36.

[0015] As a result, the motor generator MG2 is connected to the left and right drive shafts DS and wheels W via the coupling gear 38, counter-driven gear 36, drive pinion gear 37, differential ring gear 39r, and differential gear 39. The motor generator MG2 functions as a power source that outputs drive torque (driving force) to the drive shafts DS and wheels W, either alone or in cooperation with the engine 10, and also outputs regenerative braking torque when the vehicle 1 is braked.

[0016] The transaxle 20 case 40 includes a first case 41, a second case 42, and a cover (third case) 45. The first and second cases 41, 42, and the cover 45 are all castings made of, for example, aluminum alloy or steel. The first case 41 is fastened (connected) to the engine block of the engine 10 via a plurality of bolts. The second case 42 is fastened (connected) to the first case 41 via a plurality of bolts and together with the first case 41 constitute the case body. Furthermore, the second case 42 has a partition wall 42w that divides the inside of the case 40 (case body) into two. The cover 45 is fastened (connected) to the second case 42 via a plurality of bolts so as to cover the open end of the second case 42 opposite to the first case 41 side.

[0017] Furthermore, in this embodiment, the carrier shaft CS fixed to the planetary carrier 34 of the planetary gear 30 is supported by a bearing (e.g., a needle bearing) B0 held by the first case 41. In addition, the rotor shaft RS fixed to the sun gear 31 of the planetary gear 30 and the rotor R1 of the motor generator MG1 is supported by a bearing (e.g., a ball bearing) B1 held by the partition wall 42w of the second case 42 and a bearing (e.g., a ball bearing) B2 held by the cover 45. Also, the countershaft fixed to the counter driven gear 36 and the drive pinion gear 37 is supported by a bearing (e.g., a tapered roller bearing) B3 held by the first case 41 and a bearing (e.g., a tapered roller bearing) B4 held by the partition wall 42w of the second case 42.

[0018] Furthermore, the motor shaft MS, which rotates integrally with the rotor R2 and the connecting gear 38, is supported by bearings B5, B6, and B7, which are, for example, ball bearings. Specifically, the end of the motor shaft MS on the connecting gear 38 side (left end in Figure 1) is supported by a bearing (first bearing) B5 held by the first case 41. The end of the motor shaft MS on the rotor R2 side (right end in Figure 1) is supported by a bearing (second bearing) B7 held by the cover 45. Furthermore, the motor shaft MS is supported by a bearing (intermediate bearing) B6 held by the partition wall 42w of the second case 42 between the connecting gear 38 and the rotor R2 in the axial direction. In addition, the differential case of the differential gear 39 is supported by a bearing (e.g., a tapered roller bearing) B8 held by the first case 41 and a bearing (e.g., a tapered roller bearing) B9 held by the second case 42.

[0019] As shown in Figure 1, inside the case 40, a gear chamber 44 is defined on the engine 10 side of the partition wall 42w, and a motor chamber 46 is defined on the cover 45 side of the partition wall 42w. As shown in the figure, the gear chamber 44 houses the gear mechanism, i.e., the gear train from the planetary gear 30 and counter drive gear 35 to the differential gear 39. The motor chamber 46 houses motor generators MG1 and MG2. Furthermore, a hydraulic fluid reservoir is defined at the bottom of the motor chamber 46 for storing hydraulic fluid (ATF) as a lubricating and cooling medium. A strainer and an electric oil pump 60 (not shown) are located in the hydraulic fluid reservoir.

[0020] The strainer is fixed inside the hydraulic fluid reservoir, for example, with a suction port located at the bottom that opens downwards. The suction port of the electric oil pump 60 is connected to the oil outlet of the strainer, and a hollow oil pipe (not shown) is connected to the discharge port of the electric oil pump 60. The electric oil pump 60 draws in hydraulic fluid from the hydraulic fluid reservoir and pumps the drawn-in hydraulic fluid through oil pipes, etc., to an air-cooled or water-cooled oil cooler 70. The hydraulic fluid from the electric oil pump 60 is cooled in the oil cooler 70 to, for example, near room temperature (around 20-25°C), and supplied to the lubrication and cooling targets in the case 40, i.e., the gear chamber 44 and motor chamber 46, via oil passages formed in the cover 45. The lubrication and cooling targets include motor generators MG1, MG2, planetary gears 30, gears 35-39r, differential gear 39, bearings B0-B9, etc.

[0021] The hydraulic fluid supplied from the electric oil pump 60 into the motor chamber 46 flows down to the hydraulic fluid reservoir within the motor chamber 46, passing through lubrication and cooling targets such as the motor generators MG1 and MG2, and bearings B2 and B7. Similarly, the hydraulic fluid supplied from the electric oil pump 60 into the gear chamber 44 flows down to the lower part of the gear chamber 44, passing through lubrication and cooling targets within the gear chamber 44, such as the planetary gear 30, gears 35-39r, differential gear 39, and bearings B0, B1, B3-B6, B8, and B9. Furthermore, the hydraulic fluid that has flowed down into the gear chamber 44 is scooped upwards by the differential ring gear 39r, connecting gear 38, counter-driven gear 36, counter-drive gear 35, etc., and supplied to lubrication and cooling targets within the gear chamber 44. Furthermore, the partition wall 42w of the second case 42 is provided with a number of oil holes (not shown) corresponding to the counter drive gear 35, the connecting gear 38, or the differential ring gear 39r, respectively. A portion of the hydraulic fluid stirred up in the gear chamber 44 flows into the motor chamber 46 through these oil holes. In addition, the partition wall 42w has a number of communication holes (not shown) that connect the lower part of the motor chamber 46, i.e., the hydraulic fluid reservoir, with the lower part of the gear chamber 44.

[0022] FIG. 2 is an enlarged view showing a main part of the transaxle 20. As shown in the figure, the motor shaft MS includes a metal first shaft MS1 and a metal second shaft MS2 coaxially connected to rotate integrally with the first shaft MS1. In the present embodiment, a connecting gear 38 is integrally formed on the first shaft MS1. However, the connecting gear 38 may be formed separately from the first shaft MS1 and fixed to the first shaft MS1. Further, the first shaft MS1 has a first oil passage OP1. The first oil passage OP1 is a circular hole that opens at one end (the right end in FIG. 2) of the first shaft MS1 and extends along the axis of the first shaft MS1.

[0023] Furthermore, at the other end (the left end in FIG. 2) of the first shaft MS1, a closing portion C that closes the end opposite to the opening of the first oil passage OP1 is formed. In addition, a plurality of first oil supply holes H1 are formed in the first shaft MS1 at intervals in the circumferential direction. Each first oil supply hole H1 opens in the vicinity of the closing portion C and on the inner peripheral surface of the first shaft MS1, communicates with the first oil passage OP1, and extends in the radial direction of the first shaft MS1 and opens on the outer peripheral surface of the first shaft MS1. Note that only one first oil supply hole H1 may be formed in the first shaft MS1.

[0024] The second shaft MS2 is inserted into the core center hole of the rotor R2 (rotor core) of the motor generator MG2 and fixed to the rotor R2 by an interference fit such as shrink fitting or press fitting. As shown in FIG. 2, the second shaft MS2 is formed hollow and has a through hole (circular hole) that extends along the axis of the second shaft MS2 and defines a second oil passage OP2. In addition, a plurality (for example, eight in the present embodiment) of second oil supply holes H2 are formed at intervals in the circumferential direction at the central portion in the longitudinal direction of the second shaft MS2. Each second oil supply hole H2 opens on the inner peripheral surface of the second shaft MS2, communicates with the second oil passage OP2, and extends in the radial direction of the second shaft MS2 and opens on the outer peripheral surface of the second shaft MS2 surrounded by the inner peripheral surface of the rotor R2.

[0025] As shown in Figure 2, the end of the first shaft MS1 on the side of the closing portion C is fitted into the through hole of the second shaft MS2, i.e., the second oil passage OP2, from one end (right end in the figure) of the second shaft MS2. In this embodiment, splines are formed on the outer circumferential surface of the end of the first shaft MS1 on the side of the closing portion C and on the inner circumferential surface of the second shaft MS2, and the splines of the first and second shafts MS1 and MS2 mesh with each other to form a spline fitting portion SP. Furthermore, the outer circumferential surface of the first shaft MS1 and the inner circumferential surface of the second shaft MS2 are in close contact with each other on the connecting gear 38 side (right side in Figure 2) of the spline fitting portion SP to form a spigot joint portion SJ. In addition, the end face of one end of the second shaft MS2 abuts against the flange portion FL formed on the first shaft MS1. Furthermore, a friction damper FD is positioned between the outer circumferential surface of the first shaft MS1 and the inner circumferential surface of the second shaft MS2, and between the spigot joint SJ and the flange FL in the axial direction.

[0026] As a result, the first and second shafts MS1 and MS2 are connected in the rotational direction via the spline fitting portion SP and coaxially via the spigot joint portion SJ. When the first and second shafts MS1 and MS2 are connected, the closing portion C formed at the other end of the first shaft MS1 restricts communication between the first oil passage OP1 of the first shaft MS1 and the second oil passage OP2 of the second shaft MS2. One end of the first shaft MS1 (the right end in Figure 2) forms the end of the motor shaft MS on the connecting gear 38 side and is supported by a bearing B5 held by the first case 41. Furthermore, one end of the second shaft MS2 (the right end in Figure 2) is supported by a bearing B6 held by the partition wall 42w of the second case 42 between the connecting gear 38 (flange portion FL) and the spigot joint portion SJ (rotor R2) in the axial direction. Furthermore, the other end of the second shaft MS2 (the left end in Figure 2) forms the end of the motor shaft MS on the rotor R2 side and is supported by a bearing B7 held by the cover 45.

[0027] When the motor shaft MS, including the first and second shafts MS1 and MS2, is positioned inside the case 40, the first oil passage OP1 of the first shaft MS1 opens near the bearing B5, and the second oil passage OP2 of the second shaft MS2 opens near the bearing B7. An extension 45e extending from the cover 45 is inserted into the opening of the second oil passage OP2. The extension 45e has an oil hole 45h that communicates with the oil passage 45p formed in the cover 45 and opens at the tip of the extension 45e.

[0028] Furthermore, as shown in Figure 2, each first oil supply hole H1 of the first shaft MS1 is positioned in the axial direction between the bearing (intermediate bearing) B6 and the end face ES on the connecting gear 38 side of the rotor R2, and opens on the outer circumferential surface of the first shaft MS1 that forms the spigot joint SJ. Also, each second oil supply hole H2 of the second shaft MS2 is located on the rotor RS side (left side in Figure 2) in the axial direction of the motor shaft MS of each first oil supply hole H1, facing the axial central portion of the inner circumferential surface of the rotor R2 (rotor core), and communicates with the corresponding refrigerant passage of the rotor R2 via a communication passage formed in the rotor R2. In this embodiment, the rotor R2 (rotor core) has a plurality of refrigerant passages formed at circumferential intervals so as to extend axially on the radially outer side of the core central hole. Furthermore, the closing portion C of the first shaft MS1 restricts communication between the first oil supply hole H1 and the second oil supply hole H2 in the axial direction, and more specifically, between the first oil supply hole H1 and the end face ES of the connecting gear side 38 of the rotor R2 in the axial direction.

[0029] While the vehicle 1, which includes the transaxle 20 described above, is in motion, hydraulic fluid that has been scraped up in the gear chamber 44 by the differential ring gear 39r, connecting gear 38, counter drive gear 35, etc., and hydraulic fluid that has passed through bearing B5, etc., flows into the first oil passage OP1 of the rotating motor shaft MS, i.e., the first shaft MS1, from an opening at one end of the first shaft MS1. The hydraulic fluid that has flowed into the first oil passage OP1 flows from the first oil passage OP1 to each first oil supply hole H1 by centrifugal force and is supplied to the spigot joint SJ, which is to be cooled. This makes it possible to effectively cool the spigot joint SJ (metal-to-metal contact area), where the outer surface of the first shaft MS1 and the inner surface of the second shaft MS2 are in close contact with each other, by utilizing the hydraulic fluid scraped up in the gear chamber 44. The hydraulic fluid supplied to the spigot joint SJ flows down into the lower part of the gear chamber 44, passing through the minute gap between the outer surface of the first shaft MS1 and the inner surface of the second shaft MS2, the friction damper FD, and the gap between the inner race of the bearing B6 and the partition wall 42w.

[0030] Furthermore, while the vehicle 1 is in motion, hydraulic fluid, discharged from the electric oil pump 60 and cooled by the oil cooler 70, is supplied to the opening at the other end of the rotating motor shaft MS, i.e., the second shaft MS2, i.e., the second oil passage OP2, via the oil passage 45p of the cover 45 and the oil hole 45h of the extension 45e. The hydraulic fluid that flows into the second oil passage OP2 flows from the second oil passage OP2 to each second oil supply hole H2 by centrifugal force, and from each second oil supply hole H2 flows into the corresponding refrigerant passage of the rotor R2 via the connecting passage formed in the rotor R2. As a result, the entire rotor R2 (rotor core and permanent magnets) can be cooled effectively by the hydraulic fluid flowing through the multiple refrigerant passages. The hydraulic fluid supplied to the rotor R2 absorbs heat from the rotor R2 and flows out to the outside through the openings of each refrigerant passage, and is also scattered radially outward by centrifugal force. The hydraulic fluid scattered outside the rotor R2 flows down into the hydraulic fluid reservoir in the motor chamber 46.

[0031] In the transaxle 20, a closed section C formed at the other end of the first shaft MS1 restricts communication between the first oil passage OP1 of the first shaft MS1 and the second oil passage OP2 of the second shaft MS2. Therefore, the hydraulic fluid churned up in the gear chamber 44 and supplied to the first oil passage OP1 does not mix with the hydraulic fluid supplied from the electric oil pump 60 to the second oil passage OP2 via the oil cooler 70 within the motor shaft MS. This allows the hydraulic fluid churned up in the gear chamber 44 to be supplied from the first oil supply hole H1 to the spigot joint SJ, which is a predetermined cooling target, and the hydraulic fluid from the electric oil pump 60, cooled by the oil cooler 70, to be supplied to the rotor R2 to effectively cool the motor generator MG2, which is another cooling target. In addition, a portion of the hydraulic fluid supplied from the electric oil pump 60 to the second oil passage OP2 via the oil cooler 70 passes through the spline fitting section SP and flows into the spigot joint SJ. This allows the spline fitting portion SP and the spigot joint portion SJ to be cooled by a portion of the hydraulic fluid from the electric oil pump 60.

[0032] As described above, the transaxle 20 mounted on the vehicle 1 includes a motor generator MG2, a gear mechanism connected to the motor generator MG2 and including at least a differential gear 39, a case 40 housing the motor generator MG2 and the gear mechanism, and an electric oil pump 60 that sucks in and discharges the hydraulic fluid stored in the case 40. Furthermore, the transaxle 20 includes a motor shaft MS that rotates integrally with a connecting gear 38 included in the gear mechanism and the rotor R2 of the motor generator MG2, which is spaced axially apart from the connecting gear 38. The motor shaft MS has a first oil passage OP1, a second oil passage OP2, and a closing section C. The first oil passage OP1 is formed on the motor shaft MS (first shaft MS1) so as to guide the hydraulic fluid, which is scraped up by at least one gear included in the gear mechanism such as the differential ring gear 39r and supplied to the end of the motor shaft MS on the connecting gear 38 side (one end of the first shaft MS1), to the spigot joint SJ in the case 40 which is to be cooled. The second oil passage OP2 is formed in the motor shaft MS (second shaft MS2) to guide the hydraulic fluid supplied from the electric oil pump 60 to the end of the motor shaft MS on the rotor R2 side (the other end of the second shaft MS2) to the rotor R2. The closing section C is provided in the motor shaft MS (first shaft MS1) to restrict communication between the first oil passage OP1 and the second oil passage OP2.

[0033] This allows the hydraulic fluid, which has been stirred up by the differential ring gear 39r, etc., to be guided from the first oil passage OP1 to the spigot joint SJ, which is the target of cooling, without mixing the hydraulic fluid in the first oil passage OP1 with the hydraulic fluid in the second oil passage OP2. At the same time, the hydraulic fluid from the electric oil pump 60 can be guided from the second oil passage OP2 to the rotor R2 of the motor generator MG2, which is another target of cooling within the case 40. As a result, the temperature of the hydraulic fluid in the second oil passage OP2, which has been cooled by the oil cooler 70, is suppressed from rising due to the temperature rise of the hydraulic fluid in the first oil passage OP1, making it possible to efficiently cool the spigot joint SJ and the motor generator MG2, which are the targets of cooling.

[0034] Furthermore, the motor shaft MS (first or second shaft MS1, MS2) includes a first oil supply hole H1 that communicates with the first oil passage OP1 and supplies hydraulic fluid to the spigot joint SJ side, and a second oil supply hole H2 that communicates with the second oil passage OP2 and opens on the outer circumferential surface of the motor shaft MS (second shaft MS2) which is surrounded by the inner circumferential surface of the rotor R2. In addition, the closing portion C is positioned between the first oil supply hole H1 and the second oil supply hole H2 in the axial direction. Furthermore, in the transaxle 20, the hydraulic fluid discharged from the electric oil pump 60 is supplied to the second oil passage OP2 via the oil cooler 70.

[0035] This allows the hydraulic fluid discharged from the electric oil pump 60 and cooled in the oil cooler 70 to be supplied to the rotor R2 without being heated by mixing with the hydraulic fluid stirred up in the gear chamber 44, thereby enabling effective cooling of the motor generator MG2. In addition, the temperature of the hydraulic fluid flowing out of the oil cooler 70 may be detected in the transaxle 20, and the oil cooler 70, etc., may be controlled so that the detected temperature reaches a desired temperature.

[0036] Furthermore, the transaxle 20 includes a bearing (first bearing) B5 that supports one end of the first shaft MS1, i.e., the end of the motor shaft MS on the connecting gear 38 side, a bearing (second bearing) B7 that supports the other end of the second shaft MS2, i.e., the end of the motor shaft MS on the rotor R2 side, and a bearing (intermediate bearing) B6 that supports the motor shaft MS in the axial direction between the connecting gear 38 and the rotor R2. The first oil supply hole H1 is positioned in the axial direction between the bearing B6 and the end face ES of the rotor R2 on the connecting gear 38 side.

[0037] This provides stable support for the relatively long motor shaft MS, which rotates integrally with the connecting gear 38 and the rotor R2 of the motor generator MG2, and allows the hydraulic fluid scraped up within the gear chamber 44 (case 40) to be supplied from the first oil supply hole H1 to the spigot joint SJ (the object to be cooled) located between the bearing B6 and the rotor R2 in the axial direction. However, the object to be cooled by the hydraulic fluid supplied to the first oil passage OP1 is not limited to the spigot joint SJ, but can be arbitrarily determined within the range in which hydraulic fluid can be supplied from the first oil passage OP1.

[0038] Furthermore, in the transaxle 20, the motor shaft MS includes a first shaft MS1 having a first oil passage OP1 and rotating integrally with the connecting gear 38, and a second shaft MS2 having a second oil passage OP2 and fixed to the rotor R2. Moreover, the first shaft MS1 is fitted into the second oil passage OP2 so as to rotate integrally with the second shaft MS2. The closing portion C is formed at the end of the first shaft MS1 on the side of the second shaft MS2.

[0039] This makes it possible to easily form the first oil passage OP1, the second oil passage OP2, and the closing section C on the motor shaft MS. However, in the transaxle 20, the closing section C may be formed at the end of the second shaft MS2 on the first shaft MS1 side, and the motor shaft MS may be a single shaft member including the first oil passage OP1, the second oil passage OP2, and the closing section C.

[0040] Furthermore, the first and second shafts MS1 and MS2 are connected in the rotational direction via a spline fitting portion SP, and are also coaxially connected via a spigot joint portion SJ on the connecting gear 38 side of the spline fitting portion SP, where the outer surface of the first shaft MS1 is in close contact with the inner surface of the second shaft MS2. In addition, in the transaxle 20, a portion of the hydraulic fluid supplied to the second oil passage OP2 passes through the spline fitting portion SP and flows into the spigot joint portion SJ.

[0041] This allows the hydraulic fluid sloshed up in the gear chamber 44 to cool the spigot joint SJ, and also allows a portion of the hydraulic fluid from the electric oil pump 60 to cool the spline fitting SP and the spigot joint SJ. As a result, wear on the first and second shafts MS1 and MS2 in the spline fitting SP and the spigot joint SJ can be effectively suppressed.

[0042] Vehicle 1 may be a plug-in hybrid vehicle (PHEV) or a single-motor hybrid vehicle. Furthermore, the transaxle 20 may be modified to be installed in a battery electric vehicle (BEV) or a fuel cell vehicle (FCEV).

[0043] The invention disclosed herein is not limited in any way to the embodiments described above, and it goes without saying that various modifications can be made within the scope of this disclosure. Furthermore, the embodiments described above are merely one specific form of the invention described in the summary section of the invention, and do not limit the elements of the invention described in the summary section of the invention. [Industrial applicability]

[0044] The invention disclosed herein is applicable in industries such as the transaxle manufacturing industry. [Explanation of Symbols]

[0045] 1 Vehicle, 20 Transaxle, 30 Planetary gear, 35 Counter drive gear, 36 Counter driven gear, 37 Drive pinion gear, 38 Linking gear, 39 Differential gear, 39r Differential ring gear, 40 Case, 41 First case, 42 Second case, 42w Bulkhead, 44 Gear chamber, 45 Cover, 45e Extension, 45h Oil hole, 45p Oil passage, 46 Motor chamber, 60 Electric oil pump, 70 Oil cooler, B0, B1, B2, B3, B4, B5, B6, B7, B8, B9 Bearings, C Enclosure, 44 Gear chamber, 46 Motor chamber, H1 First oil supply hole, H2 Second oil supply hole, MG1, MG2 Motor generator, MS Motor shaft, MS1 First shaft, MS2 Second shaft, OP1 First oil passage, OP2 second oil passage, R1, R2 rotor, S1, S2 stator, SJ spigot joint, SP spline fitting, W wheel.

Claims

1. A transaxle mounted on a vehicle, comprising an electric motor, a gear mechanism connected to the electric motor and including at least a differential gear, a case housing the electric motor and the gear mechanism, and a pump for drawing in and discharging oil stored in the case, A connecting gear included in the gear mechanism and a shaft that rotates integrally with the rotor of the electric motor, which is spaced axially apart from the connecting gear, A first oil passage is formed in the shaft to guide oil, which has been scraped up by at least one gear included in the gear mechanism and supplied to the end of the shaft on the connecting gear side, to a predetermined object to be cooled in the case, A second oil passage is formed in the shaft to guide the oil supplied from the pump to the rotor-side end of the shaft to the rotor, A closing section is provided on the shaft to restrict communication between the first oil passage and the second oil passage, A transaxle equipped with a transaxle.

2. In the transaxle according to claim 1, The shaft includes a first oil supply hole that communicates with the first oil passage and supplies oil to the cooling target side, and a second oil supply hole that communicates with the second oil passage and opens on the outer surface of the shaft that is surrounded by the inner surface of the rotor. The closing portion is positioned between the first oil supply hole and the second oil supply hole in the axial direction. The oil discharged from the pump is supplied to the second oil passage via an oil cooler in the transaxle.

3. In the transaxle described in claim 2, A first bearing supporting the end of the shaft on the connecting gear side, A second bearing supports the rotor-side end of the shaft, The system further comprises an intermediate bearing that supports the shaft between the connecting gear and the rotor in the axial direction, The first oil supply hole is located in the transaxle between the intermediate bearing and the end face of the rotor on the connecting gear side in the axial direction.

4. In the transaxle according to any one of claims 1 to 3, The shaft includes a first shaft having the first oil passage and rotating integrally with the connecting gear, and a second shaft having the second oil passage and fixed to the rotor. The first shaft is fitted into the second oil passage so as to rotate integrally with the second shaft. The closing portion is a transaxle formed at the end of the first shaft on the second shaft side.

5. In the transaxle according to claim 4, The first and second shafts are connected in the rotational direction via a spline fitting portion, and are coaxially connected via a spigot joint portion on the connecting gear side of the spline fitting portion, where the outer surface of the first shaft is in close contact with the inner surface of the second shaft. The object to be cooled is the spigot joint, A portion of the oil supplied to the second oil passage flows through the spline fitting portion and into the spigot joint portion of the transaxle.

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