transaxle

Abstract

To provide a transaxle that can efficiently cool the object to be cooled inside the case. [Solution] The transaxle includes a connecting gear included in a gear mechanism connected to an electric motor 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 an oil passage through which oil scraped up in a case is supplied to the end on the connecting gear side and oil from a pump is supplied to the end on the rotor side, a first oil supply hole formed in the shaft to supply oil from the oil passage to a predetermined cooling target side, and a second oil supply hole formed in the shaft on the rotor side of the first oil supply hole to supply oil from the oil passage to the rotor. A movable closing member capable of closing the oil passage is arranged in the oil passage so as to be axially movable in the range from between the first oil supply hole and the second oil supply hole to between the second oil supply hole and the rotor-side end of the shaft.

Description

Technical Field

[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 by 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 shaft that rotates integrally with a coupling gear included in the gear mechanism and the rotor of the electric motor, which is spaced axially apart from the coupling gear. The shaft includes an oil passage formed to extend axially inside it, a first oil supply hole, and a second oil supply hole. Oil scraped up by at least one gear included in the gear mechanism is supplied to the coupling gear side end of the oil passage of the shaft, and oil from the pump is supplied to the rotor side end of the oil passage. The first oil supply hole is formed in the shaft to supply oil from the oil passage to a predetermined cooling target side, and the second oil supply hole is formed in the shaft on the rotor side in the axial direction of the first oil supply hole to supply oil from the oil passage to the rotor. Furthermore, a movable closing member capable of closing the oil passage is arranged within the oil passage of the shaft so as to be axially movable within a range from between the first oil supply hole and the second oil supply hole to between the second oil supply hole and the rotor-side end of the shaft.

[0007] As a result, when the movable closing member is positioned between the first and second oil supply holes in the oil passage, the movable closing member divides the oil passage into the first oil supply hole side and the second oil supply hole side, preventing the oil scraped up by at least one gear of the gear mechanism from mixing with the oil from the pump within the shaft. Therefore, the oil scraped up in the case can be supplied from the first oil supply hole to a predetermined cooling target within the case, and the oil from the pump can be supplied from the second oil supply hole to the rotor of the electric motor, which is another cooling target within the case. As a result, it is possible to suppress the temperature of one of the oils, the oil scraped up in the case and the oil from the pump, from rising due to the temperature rise of the other, thereby enabling efficient cooling of the predetermined cooling target and the electric motor. Furthermore, if oil stops being discharged from the pump due to a malfunction or the like, the oil scraped up in the case and supplied to the first oil passage can move the movable closing member between the second oil supply hole and the rotor-side end of the shaft. As a result, even if oil stops being discharged from the pump, the oil churned up within the case can be supplied to the designated cooling target through the first oil supply port and to the motor rotor through the second oil supply port, thereby enabling the cooling of both the cooling target and the motor. [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. [Figure 3] 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 in the hydraulic oil reservoir such that, for example, the suction port provided at the bottom opens downward. Further, 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 sucks the hydraulic oil in the hydraulic oil reservoir and pumps the sucked hydraulic oil to an air-cooled or water-cooled oil cooler 70 via an oil pipe or the like. The hydraulic oil from the electric oil pump 60 is cooled in the oil cooler 70 to, for example, around normal temperature (about 20 - 25°C), and is supplied to the lubrication and cooling targets in the case 40, that is, the gear chamber 44 and the motor chamber 46, via an oil passage formed in the cover 45 or the like. The lubrication and cooling targets include the motor generators MG1, MG2, the planetary gear 30, the gears 35 - 39r, the differential gear 39, the bearings B0 - B9, etc.

[0021] The hydraulic oil supplied from the electric oil pump 60 into the motor chamber 46 flows down through the lubrication and cooling targets such as the motor generators MG1, MG2, and the bearings B2, B7, and into the hydraulic oil reservoir in the motor chamber 46. Further, the hydraulic oil supplied from the electric oil pump 60 into the gear chamber 44 flows down through the lubrication and cooling targets in the gear chamber 44 such as the planetary gear 30, the gears 35 - 39r, the differential gear 39, and the bearings B0, B1, B3 - B6, B8, B9, and into the lower part of the gear chamber 44. Furthermore, the hydraulic oil flowing down into the gear chamber 44 is scraped up upward by the defring gear 39r, the connecting gear 38, the counter driven gear 36, the counter drive gear 35, etc., and is supplied to the lubrication and cooling targets in the gear chamber 44. Also, a plurality of oil holes (not shown) corresponding to the counter drive gear 35, the connecting gear 38, or the defring gear 39r are provided in the partition wall 42w of the second case 42. A part of the hydraulic oil scraped up in the gear chamber 44 flows into the motor chamber 46 through these oil holes. Further, a plurality of communication holes (not shown) are formed in the partition wall 42w to communicate the lower part in the motor chamber 46, that is, the hydraulic oil reservoir, with the lower part in the gear chamber 44.

[0022] FIG. 2 is an enlarged view showing the 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.

[0023] Also, the first shaft MS1 is formed hollow and has a through hole (circular hole) that extends along the axis of the first shaft MS1 and defines a first oil passage OP1. Further, a plurality of first oil supply holes H1 are formed in the first shaft MS1 at intervals in the circumferential direction so as to be axially spaced from the connecting gear 38. Each first oil supply hole H1 opens on the inner peripheral surface of the first shaft MS1 and 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. Also, 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 and 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 adjacent to the first oil supply hole H1 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 adjacent to the first oil supply hole H1 and on the inner circumferential surface of the second shaft MS2. 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 end face of the end of the first shaft MS1 fitted into the second oil passage OP2 is located axially between the first oil supply hole H1 of the first shaft MS1 and the second oil supply hole H2 of the second shaft MS2. In addition, 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, axially between the connecting gear 38 (flange portion FL) and the spigot joint portion SJ (rotor R2). 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.

[0029] A movable closing member Cm is positioned within the second oil passage OP2 of the second shaft MS2 so as to be movable in the axial direction. In this embodiment, the movable closing member Cm is, for example, a metal sphere having an outer diameter larger than the inner diameter of the first oil passage OP1 and slightly smaller than the inner diameter of the spline formed on the inner circumferential surface of the second shaft MS2. However, the movable closing member X may be a cylindrical member having the same outer diameter as the sphere. Furthermore, the movable closing member Cm is movable in the axial direction from the end face of the end of the first shaft MS1 fitted into the second oil passage OP2 located between the first oil supply hole H1 and the second oil supply hole H2 in the axial direction, to the tip of the extension portion 45e of the cover 45 located between the second oil supply hole H2 and the other end of the second shaft MS2 (the end of the motor shaft MS on the rotor R2 side). As shown in Figure 2, when the movable closing member Cm contacts the end face of the end of the first shaft MS1 within the second oil passage OP2, the first oil passage OP1 of the first shaft MS1 is closed by the movable closing member Cm. Also, as shown in Figure 3, when the movable closing member Cm moves beyond each second oil supply hole H2 towards the extension portion 45e of the cover 45, the closure of the first oil passage OP1 is released, and each second oil supply hole H2 communicates with the first oil passage OP1 of the first shaft MS1 via the second oil passage OP2.

[0030] 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.

[0031] 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.

[0032] Furthermore, while the vehicle 1 is in motion, the electric oil pump 60 is controlled so that the flow rate of hydraulic fluid supplied from the electric oil pump 60 to the second oil passage OP2 is greater than the flow rate (analyzed value) of hydraulic fluid supplied to the first oil passage OP1. As a result, the axial thrust applied to the movable closing member Cm from the hydraulic fluid in the second oil passage OP2 is greater than the axial thrust applied to the movable closing member Cm from the hydraulic fluid in the first oil passage OP1. Consequently, while the vehicle 1 is in motion, the movable closing member Cm is pressed against the end face of the end of the first shaft MS1 by the axial thrust from the hydraulic fluid in the second oil passage OP2, closing the first oil passage OP1 of the first shaft MS1. As shown in Figure 2, when the movable closing member Cm closes the first oil passage OP1 of the first shaft MS1 between the first oil supply hole H1 and the second oil supply hole H2 in the axial direction, the hydraulic fluid that is scraped up in the gear chamber 44 and supplied to the first oil passage OP1 and the hydraulic fluid supplied from the electric oil pump 60 to the second oil passage OP2 will not mix in the motor shaft MS.

[0033] Therefore, the hydraulic fluid stirred up in the gear chamber 44 is supplied from the first oil supply hole H1 to the spigot joint SJ, which is a designated cooling target, and the hydraulic fluid from the electric oil pump 60 cooled by the oil cooler 70 is supplied to the rotor R2, making it possible 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 flows through the spline fitting portion SP into the spigot joint SJ. As a result, the spline fitting portion SP and the spigot joint SJ can be cooled by a portion of the hydraulic fluid from the electric oil pump 60.

[0034] On the other hand, if the electric oil pump 60 stops discharging hydraulic fluid due to a malfunction or other reason, the axial thrust from the hydraulic fluid that is stirred up in the gear chamber 44 and supplied to the first oil passage OP1 can move the movable closing member Cm between each second oil supply hole H2 and the end of the motor shaft MS on the rotor R2 side. As a result, even if the electric oil pump 60 stops discharging hydraulic fluid, each second oil supply hole H2 can be connected to the first oil passage OP1 via the second oil passage OP2, allowing the hydraulic fluid that is stirred up in the gear chamber C and supplied to the first oil passage OP1 to be supplied to the spigot joint SJ from the first oil supply hole HI, and also supplied to the rotor R2 of the motor generator MG2 from each second oil supply hole H2.

[0035] 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 connecting gear 38 included in the gear mechanism and a motor shaft MS that rotates integrally with the rotor R2 of the motor generator MG2, which is spaced axially apart from the connecting gear 38. The motor shaft MS includes first and second oil passages OP1 and OP2 formed to extend axially inside it, a first oil supply hole H1, and a second oil supply hole H2.

[0036] At the end of the first oil passage OP1 spaced away from the rotor R2 (the end on the side of the connecting gear 38 of the first and second oil passages OP1 and OP2), hydraulic fluid is supplied, which has been scraped up by at least one gear included in the gear mechanism, such as the differential ring gear 39r. At the end of the second oil passage OP2 spaced away from the connecting gear 38 (the end on the rotor R2 side of the first and second oil passages OP1 and OP2), hydraulic fluid is supplied from the electric oil pump 60. The first oil supply hole H1 is formed in the motor shaft MS (first shaft MS1) to supply hydraulic fluid from the first oil passage OP1 to the side of the spigot joint SJ (a predetermined cooling target), and the second oil supply hole H2 is formed in the motor shaft MS (second shaft MS2) on the rotor R2 side in the axial direction of the first oil supply hole H1 to supply hydraulic fluid from the second oil passage OP2 to the rotor R2. Furthermore, a movable closing member Cm capable of closing the first oil passage OP1 is positioned within the second oil passage OP2 so as to be axially movable within a range from the axial space between the first oil supply hole H1 and the second oil supply hole H2 to the axial space between the second oil supply hole H2 and the end of the motor shaft MS on the rotor R2 side.

[0037] As a result, when the movable closing member Cm is positioned in the second oil passage OP2 between the first oil supply hole H1 and the second oil supply hole H2 in the axial direction, the movable closing member Cm separates the first and second oil passages OP1 and OP2 into the first oil supply hole H1 side and the second oil supply hole H2 side, so that the hydraulic fluid stirred up in the gear chamber 44 by the differential ring gear 39r etc. and the hydraulic fluid from the electric oil pump 60 do not mix in the motor shaft MS. Therefore, the hydraulic fluid stirred up in the gear chamber 44 can be supplied from the first oil supply hole H1 to the spigot joint SJ, which is a predetermined cooling target in the case 40, and the hydraulic fluid from the electric oil pump 60 can be supplied from the second oil supply hole H2 to the rotor R2 of the motor generator MG2, which is another cooling target in the case 40. As a result, the temperature of the hydraulic fluid in the second oil passage OP2, which is cooled by the oil cooler 70, is suppressed from rising due to the temperature increase 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.

[0038] Furthermore, if the electric oil pump 60 stops discharging hydraulic fluid due to a malfunction or other reason, the hydraulic fluid churned up in the gear chamber 44 and supplied to the first oil passage OP1 can move the movable closing member Cm axially between the second oil supply hole H2 and the end of the motor shaft MS on the rotor R2 side. As a result, even if the electric oil pump 60 stops discharging hydraulic fluid, the hydraulic fluid supplied to the first oil passage OP1 can be supplied to the spigot joint SJ from the first oil supply hole HI and to the rotor R2 of the motor generator MG2 from the second oil supply hole H2, making it possible to cool the spigot joint SJ and the motor generators MG1 and MG2.

[0039] Furthermore, the motor shaft MS includes a first oil passage OP1 that communicates with the first oil supply hole H1, and a second oil passage OP2 that is larger in diameter than the first oil passage OP1 and communicates with the second oil supply hole H2. The second oil passage OP2 is able to communicate with the first oil passage OP1 in the axial direction between the first oil supply hole H1 and the second oil supply hole H2. In addition, the movable closing member Cm is arranged to be axially movable within the second oil passage OP2 so as to be able to close the first oil passage OP1. Furthermore, the hydraulic fluid discharged from the electric oil pump 60 is supplied to the second oil passage OP2 via the oil cooler 70.

[0040] This allows the axial thrust generated in the second oil passage OP2 based on centrifugal hydraulic pressure to be greater than the axial thrust generated in the first oil passage OP1 based on centrifugal hydraulic pressure when the first and second oil passages OP1 and OP2 are filled with hydraulic fluid. Therefore, the axial thrust generated in the second oil passage OP2 makes it possible to move the movable closing member Cm toward the first oil passage OP1 to close the first oil passage OP1. In addition, the transaxle 20 supplies the hydraulic fluid discharged from the electric oil pump 60 and cooled in the oil cooler 70 to the rotor R2 without raising its temperature by mixing with the hydraulic fluid stirred up in the gear chamber 44, thereby enabling good cooling of the motor generator MG2. In the transaxle 20, the temperature of the hydraulic fluid flowing out of the oil cooler 70 may be detected, and the oil cooler 70, etc., may be controlled so that the detected temperature reaches a desired temperature.

[0041] 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 also positioned in the axial direction between the bearing B6 and the end face ES of the rotor R2 on the connecting gear 38 side.

[0042] 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.

[0043] 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 being 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.

[0044] This makes it possible to easily form the first oil passage OP1 and the second oil passage OP2, in which the movable closing member Cm is located, relative to the motor shaft MS. However, in the transaxle 20, the motor shaft MS may be a single shaft member including the first oil passage OP1 and the second oil passage OP2. In this case, the first oil passage OP1 and the second oil passage OP2 may be formed to have the same diameter as each other to form a single oil passage.

[0045] 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.

[0046] 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.

[0047] 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).

[0048] 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]

[0049] The invention disclosed herein is applicable in industries such as the transaxle manufacturing industry. [Explanation of Symbols]

[0050] 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, Cm Movable closing member, 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, An oil passage formed inside the shaft so as to extend in the axial direction, wherein oil scraped up by at least one gear included in the gear mechanism is supplied to the end on the connecting gear side, and oil from the pump is supplied to the end on the rotor side, A first oil supply hole is formed in the shaft to supply oil from the oil passage to a predetermined cooling target side, A second oil supply hole is formed in the shaft on the rotor side in the axial direction of the first oil supply hole to supply oil from the oil passage to the rotor, A movable closing member is provided within the oil passage so as to be able to close the oil passage and move in the axial direction within a range from between the first oil supply hole and the second oil supply hole to between the second oil supply hole and the rotor-side end of the shaft, A transaxle equipped with a transaxle.

2. In the transaxle according to claim 1, The oil passage includes a first oil passage that communicates with the first oil supply hole, and a second oil passage that has a larger diameter than the first oil passage and communicates with the second oil supply hole. The second oil passage is able to communicate with the first oil passage between the first oil supply hole and the second oil supply hole in the axial direction, The movable closing member is arranged within the second oil passage so as to be movable in the axial direction, so as to be able to close the first oil passage. 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 supports 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 claim 2 or 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 a transaxle fitted into the second oil passage so as to rotate integrally with the second shaft.

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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