Provided is a unit including: a heat exchanger; and a housing configured to accommodate a differential gear mechanism, in which the housing has a portion having an inclined surface surrounding the differential gear mechanism in a radial direction, and the heat exchanger has a portion that overlaps the inclined surface when viewed in an axial direction.

TECHNICAL FIELD

The present invention relates to a unit.

BACKGROUND ART

Patent Document 1 discloses a unit including a motor and a power transmission mechanism.

PRIOR ART DOCUMENT

Patent Document

Patent Document 1: JP 2008-185078 A

SUMMARY OF INVENTION

Problem to be Solved by the Invention

In a unit, oil is used to lubricate and cool rotating members. A heat exchanger for cooling the oil is mounted on the unit. The heat exchanger cools the oil by exchanging heat between a coolant such as cooling water and the oil.

In the unit in which the heat exchanger is mounted, it is required to provide a structure that contributes to a reduction in dimension in at least one direction.

Solutions to the Problems

According to one aspect of the present invention, a unit includes:a heat exchanger; anda housing configured to accommodate a differential gear mechanism, whereinthe housing has a portion having an inclined surface surrounding the differential gear mechanism in a radial direction, andthe heat exchanger has a portion that overlaps the inclined surface when viewed in an axial direction.

According to one aspect of the present invention, a unit includes:a heat exchanger;a housing configured to accommodate a differential gear mechanism, whereinthe differential gear mechanism has a portion that overlaps a motor when viewed in an axial direction,the heat exchanger has a portion that overlaps the housing when viewed in the axial direction, andthe heat exchanger is positioned above the differential gear mechanism in a gravity direction.

Advantageous Effects of Invention

An aspect of the present invention contributes to a reduction in dimension in at least one direction in a unit equipped with a heat exchanger.

DESCRIPTION OF EMBODIMENTS

First, definitions of terms in the present specification will be described.

A “unit” is also referred to as a “motor unit”, a “power transmission device”, or the like. The motor unit is a unit that includes at least a motor. The power transmission device is a device that includes at least a power transmission mechanism, and is, for example, a gear mechanism and/or a differential gear mechanism. A unit that is a device including a motor and a power transmission mechanism belongs to the concept of both the motor unit and the power transmission device.

A “housing” accommodates a motor, a gear, and an inverter. The housing includes one or more cases.

“3-in-1” means a form in which a part of a motor case accommodating a motor and a part of an inverter case accommodating an inverter are integrally formed. For example, when a cover and a case constitute one case, in “3-in-1”, the case accommodating a motor and the case accommodating an inverter are integrally formed.

A “motor” is a rotating electrical machine that has a motor function and/or a generator function.

When referring to a second element (component, portion, or the like) connected to a first element (component, portion, or the like), the second element (component, portion, or the like) connected downstream of the first element (component, portion, or the like), and the second element (component, portion, or the like) connected upstream of the first element (component, portion, or the like), it means that the first element and the second element are connected such that power can be transmitted. A power input side is upstream, and a power output side is downstream. The first element and the second element may be connected to each other via another element (clutch, other gear mechanism, or the like).

The description “overlap when viewed in a predetermined direction” means that a plurality of elements are disposed in a predetermined direction, and has the same meaning as the description “overlap in a predetermined direction”. The “predetermined direction” is, for example, an axial direction, a radial direction, a gravity direction, or a vehicle traveling direction (vehicle forward direction, vehicle backward direction).

When the drawing shows that a plurality of elements (components, portions, or the like) are disposed in a predetermined direction, in the description of the specification, it may be considered that there is a sentence explaining that the plurality of elements overlap when viewed in the predetermined direction.

The descriptions “do not overlap when viewed in a predetermined direction” and “are offset when viewed in a predetermined direction” mean that a plurality of elements are not disposed in a predetermined direction, and have the same meaning as the descriptions “do not overlap in a predetermined direction” and “are offset in a predetermined direction”. The “predetermined direction” is, for example, an axial direction, a radial direction, a gravity direction, or a vehicle traveling direction (vehicle forward direction, vehicle backward direction).

When the drawing shows that a plurality of elements (components, portions, or the like) are not disposed in a predetermined direction, in the description of the specification, it may be considered that there is a sentence explaining that the plurality of elements do not overlap when viewed in the predetermined direction.

The description “a first element (component, portion, or the like) is positioned between a second element (component, portion, or the like) and a third element (component, portion, or the like) when viewed in a predetermined direction” means that when viewed from the predetermined direction, it can be observed that the first element is between the second element and the third element. The “predetermined direction” is an axial direction, a radial direction, a gravity direction, a vehicle traveling direction (vehicle forward direction, vehicle backward direction), or the like.

For example, when the second element, the first element, and the third element are disposed in this order along the axial direction, it can be said that the first element is positioned between the second element and the third element when viewed in the radial direction. When the drawing shows that the first element is positioned between the second element and the third element when viewed in a predetermined direction, in the description of the specification, it may be considered that there is a sentence explaining that the first element is between the second element and the third element when viewed in the predetermined direction.

In a case where two elements (components, portions, or the like) overlap when viewed in the axial direction, the two elements are coaxial.

The “axial direction” means an axial direction of a rotation axis of a component that constitutes a unit. The “radial direction” means a direction orthogonal to the rotation axis of the component that constitutes a unit. Examples of components include a motor, a gear mechanism, and a differential gear mechanism.

When a rotating element (for example, sun gear, carrier, or ring gear) of a planetary gear mechanism is “fixed” to another element, the rotating element may be directly fixed or may be fixed via another member.

A “downstream side in a rotation direction” means a downstream side in a rotation direction when a vehicle moves forward or in a rotation direction when the vehicle moves backward. It is preferable to regard it as the downstream side in the rotation direction when the vehicle moves forward, which occurs frequently. A downstream side in a rotation direction of the planetary gear mechanism means a downstream side in a revolution direction of a pinion gear.

A “catch tank” is an element (component, portion, or the like) that has a function of a tank (container) into which oil is introduced. The supply of oil from the outside of the tank to the tank is expressed as “catch”. The catch tank is provided, for example, using at least a part of the housing, or is provided separately from the housing. The integrated formation of the catch tank and the housing contributes to a reduction in the number of components.

A “coolant” is a refrigerant and is a type of heat exchange medium. For example, the “coolant” is a liquid (cooling water or the like) or a gas (air or the like). The coolant is a concept that includes oil, but when both oil and coolant are described in the present specification, it means that the coolant is made of a material different from that of the oil.

A “heat exchange unit” is an element (component, portion, or the like) that exchanges heat between two different heat exchange media. Combinations of the two heat exchange media are, for example, oil and cooling water, cooling water and air, or air and oil. The heat exchange unit includes, for example, a heat exchanger (oil cooler), a flow path through which a coolant flows, and a heat pipe. In the present invention, it is preferable to use a heat exchanger (oil cooler) as the heat exchange unit. The use of the heat exchanger can contribute to the improvement in the heat exchange efficiency.

The heat exchanger (oil cooler) is a separate component from the housing. In the heat exchanger, for example, heat is exchanged between oil and cooling water.

A “vehicle room” means a room in a vehicle into which passengers enter.

FIG.1is a skeleton diagram illustrating a unit mounted on a vehicle.

FIG.2is an external view of the unit.

FIG.3is a schematic cross-sectional view of the unit.FIG.3shows a state in which an inverter case is removed.

FIG.4is an enlarged view around a planetary reduction gear.

FIG.5is a top view of a motor case with a second case member removed.

FIG.6is a diagram showing a circulation system of cooling water in the unit.

FIG.7is a diagram illustrating a catch tank of a gear case.

As shown inFIG.1, a unit1is a 3-in-1 unit, and includes a motor2, a power transmission mechanism3that transmits the power output from the motor2to drive wheels K and K of a vehicle, and an inverter7(seeFIG.2) that is a power conversion device of the motor2.

In the embodiment, as shown inFIG.1, the unit1includes, as the power transmission mechanism3, a planetary reduction gear4(reduction gear mechanism, planetary gear mechanism), a differential mechanism5(differential gear mechanism), and drive shafts DA and DB as output shafts. In the unit1, the planetary reduction gear4, the differential mechanism5, and the drive shafts DA and DB are provided along a transmission path of output rotation about a rotation axis X of the motor2. Axes of the drive shafts DA and DB are coaxial with the rotation axis X of the motor2, and the differential mechanism5is coaxial with the motor2.

In the unit1, the output rotation of the motor2is decelerated by the planetary reduction gear4and input to the differential mechanism5, and then transmitted to the left and right drive wheels K and K of the vehicle on which the unit1is mounted via the drive shafts DA and DB.

Here, the planetary reduction gear4is connected downstream of the motor2. The differential mechanism5is connected downstream of the motor2via the planetary reduction gear4. The drive shafts DA and DB are connected downstream of the differential mechanism5.

As shown inFIG.2, the unit1includes, as a 3-in-1 type housing, a housing HS that accommodates the motor2, the power transmission mechanism3and the inverter7. The housing HS includes one or more cases. The housing HS includes, for example, a motor case10that accommodates the motor2, a gear case14that accommodates the power transmission mechanism3, and an inverter case17that accommodates the inverter7. The gear case14is joined to one end of the motor case10in a rotation axis X direction. The inverter case17is joined above the motor case10in a gravity direction when the unit1is mounted on the vehicle.

The inverter7is an electronic component including a smoothing capacitor, a power semi-conductor element, a driver board, and the like. The inverter7is electrically connected to the motor2inside the motor case10by wiring (not shown).

In the inverter case17, a cooling path CP2through which cooling water CL (seeFIG.6) for cooling the inverter7flows is formed.

The motor2has a portion that overlaps the differential mechanism5(differential gear mechanism) when viewed in an axial direction (seeFIG.3). Here, “when viewed in an axial direction” means when viewed from the rotation axis X direction. “When viewed in a radial direction” means when viewed from the radial direction of the rotation axis X direction.

When viewed in the axial direction, the motor2has a portion that overlaps the planetary reduction gear4(reduction gear mechanism).

When viewed in the axial direction, the planetary reduction gear4(reduction gear mechanism) has a portion that overlaps the differential mechanism5(differential gear mechanism).

When viewed in the axial direction, the planetary reduction gear4(reduction gear mechanism) has a portion that overlaps the motor2.

When viewed in the axial direction, the differential mechanism5(differential gear mechanism) has a portion that overlaps the planetary reduction gear4(reduction gear mechanism).

When viewed in the axial direction, the differential mechanism5(differential gear mechanism) has a portion that overlaps the motor2.

When viewed in the axial direction, the motor2has a portion that overlaps the differential mechanism5(differential gear mechanism).

As shown inFIG.3, the motor case10includes a first case member11, a second case member12fitted onto the first case member11, and a cover member13joined to one end of the first case member11. The first case member11includes a cylindrical support wall portion111and a flange-shaped joint portion112provided at one end111aof the support wall portion111.

The support wall portion111is provided in a direction along the rotation axis X of the motor2. The motor2is accommodated inside the support wall portion111.

The second case member12includes a cylindrical peripheral wall portion121, a flange-shaped joint portion122provided at one end121aof the peripheral wall portion121, and a flange-shaped joint portion123provided at the other end121bof the peripheral wall portion121.

The peripheral wall portion121of the second case member12is formed with an inner diameter that allows the peripheral wall portion121to be fitted onto the support wall portion111of the first case member11.

The first case member11and the second case member12are assembled by fitting the peripheral wall portion121of the second case member12onto the support wall portion111of the first case member11.

The joint portion122at the one end121aof the peripheral wall portion121comes into contact with the joint portion112of the first case member11from the rotation axis X direction. The joint portions122and112are connected with bolts (not shown).

As shown inFIG.5, a protrusion111bis provided on an outer periphery of the support wall portion111of the first case member11. The protrusion111bis a wall surrounding the rotation axis X at intervals. The protrusion111bof the support wall portion111is provided in a spiral shape with a phase shifted from one end toward the other end in the rotation axis X direction. The protrusion111bsurrounds the outer periphery of the support wall portion111over the entire circumference of the support wall portion111.

As shown inFIG.3, the peripheral wall portion121of the second case member12is fitted onto the support wall portion111of the first case member11. In this state, since an inner periphery of the peripheral wall portion121comes into contact with an outer periphery of the spiral protrusion111bof the support wall portion111, a space is formed between the peripheral wall portion121and the support wall portion111. The space surrounds the rotation axis X with gaps therebetween and is continuously formed in a spiral shape in the rotation axis X direction. The spiral space forms a cooling path CP1through which the cooling water CL (seeFIG.6), which is a coolant, flows. InFIG.6, the spiral cooling path CP1is simplified and shown as a straight line.

In the outer periphery of the support wall portion111of the first case member11, ring grooves111cand111care formed on both sides of the region where the protrusion111bis provided. Seal rings113and113are fitted and attached to the ring grooves111cand111c.

The seal rings113are pressed against the inner periphery of the peripheral wall portion121fitted onto the support wall portion111to seal gaps between the outer periphery of the support wall portion111and the inner periphery of the peripheral wall portion121.

A wall portion120(cover) extending radially inward is provided at the other end121bof the second case member12. The wall portion120is provided in a direction orthogonal to the rotation axis X. An opening120athrough which the drive shaft DA is inserted is provided in a region of the wall portion120intersecting the rotation axis X.

A tubular motor support portion125that surrounds the opening120aand extends toward the motor2is provided on a surface of the wall portion120closer to the motor2(right side in the drawing).

The motor support portion125is inserted inside a coil end253b, which will be described later. The motor support portion125faces an end portion21bof a rotor core21with a gap therebetween in the rotation axis X direction. Bearings B1are supported on an inner periphery of the motor support portion125. An outer periphery of a motor shaft20is supported by the motor support portion125via the bearings B1.

A tubular wall portion126extending toward the differential mechanism5is provided on a surface of the wall portion120closer to the differential mechanism5(left side in the drawing). The tubular wall portion126has a cylindrical shape surrounding the opening120a, and an inner periphery of the tubular wall portion126supports bearings B2. The bearings B2support a tubular wall portion61of a differential case50, which will be described later.

The cover member13includes a wall portion130orthogonal to the rotation axis X and a joint portion132.

When viewed from the first case member11, the cover member13is positioned on an opposite side (right side in the drawing) to the differential mechanism5. The joint portion132of the cover member13is joined to the joint portion112of the first case member11from the rotation axis X direction. The cover member13and the first case member11are connected to each other with bolts (not shown). In this state, in the first case member11, an opening of the support wall portion111closer to the joint portion122(right side in the drawing) is closed by the cover member13.

In the cover member13, an insertion hole130afor the drive shaft DA is provided in a central portion of the wall portion130.

Lip seals RS are provided on an inner periphery of the insertion hole130a. The lip seals RS bring a lip portion (not shown) into elastic contact with an outer periphery of the drive shaft DA. A gap between the inner periphery of the insertion hole130aand the outer periphery of the drive shaft DA is sealed by the lip seals RS.

A peripheral wall portion131surrounding the insertion hole130ais provided on a surface of the wall portion130closer to the first case member11(left side in the drawing). The drive shaft DA is supported on an inner periphery of the peripheral wall portion131via bearings B4.

A motor support portion135and a connection wall136are provided on an inner diameter side of the joint portion132. The motor support portion135is provided closer to the motor2(left side in the drawing) when viewed from the peripheral wall portion131. The motor support portion135has a tubular shape surrounding the rotation axis X with a gap therebetween.

The cylindrical connection wall136is connected to an outer periphery of the motor support portion135. The connection wall136is formed with a larger outer diameter than the peripheral wall portion131closer to the wall portion130(right side in the drawing). The connection wall136is provided along the rotation axis X and extends away from the motor2. The connection wall136connects the motor support portion135and the joint portion132.

One end20aof the motor shaft20penetrates the inside of the motor support portion135from the motor2to the peripheral wall portion131.

Bearings B1are supported on an inner periphery of the motor support portion135. The outer periphery of the motor shaft20is supported by the motor support portion135via the bearings B1.

A lip seal RS is provided at a position adjacent to the bearing B1.

Oil holes136aand136bare opened in an inner periphery of the connection wall136. Oil OL flows from the oil hole136ainto a space (internal space Sc) surrounded by the connection wall136. The oil OL flowing into the internal space Sc is discharged from the oil hole136b. The lip seal RS is provided to prevent the oil OL in the connection wall136from flowing into the motor2.

The gear case14includes a peripheral wall portion141and a flange-shaped joint portion142provided at an end portion of the peripheral wall portion141closer to the motor case10. A support portion145for bearings B2, which will be described later, is provided at an end portion of the peripheral wall portion141on a side (left side in the drawing) opposite to the joint portion142. The peripheral wall portion141includes a tubular wall portion141aconnected to the joint portion142, an inclined portion141c(inclined surface) connected to the support portion145, and a connection wall portion141bconnecting the tubular wall portion141aand the inclined portion141c. The tubular wall portion141aand the connection wall portion141bare gradually reduced in diameter from the joint portion142and connected to the inclined portion141c. The inclined portion141cis inclined radially inward from the connection wall portion141btoward the support portion145. The planetary reduction gear4and the differential mechanism5as the power transmission mechanism3are accommodated inside the peripheral wall portion141.

The gear case14is positioned closer to the differential mechanism5(left side in the drawing) when viewed from the motor case10. The joint portion142of the gear case14is joined to the joint portion123of the second case member12of the motor case10from the rotation axis X direction. The gear case14and the second case member12are connected to each other with bolts (not shown).

A space formed inside the joined motor case10and gear case14is divided into two spaces by the wall portion120(cover) of the second case member12. The motor case10side of the wall portion120is a motor chamber Sa that accommodates the motor2, and the gear case14side is a gear chamber Sb that accommodates the power transmission mechanism3. The wall portion120as a cover is sandwiched between the motor2and the differential mechanism5inside the housing HS.

The cover may have a portion accommodated in the housing HS, or the entire cover may be accommodated in the housing HS like the wall portion120. The cover may be, for example, separate from the second case member12. In this case, the cover may be sandwiched and fixed between the motor case10and the gear case14. A part of the cover may be exposed outside of the housing HS.

The motor2includes the cylindrical motor shaft20, the cylindrical rotor core21fitted onto the motor shaft20, and a stator core25surrounding an outer periphery of the rotor core21with a gap therebetween.

In the motor shaft20, the bearings B1and B1are fitted and fixed to both sides of the rotor core21.

The bearings B1positioned on the one end20a(right side in the drawing) of the motor shaft20when viewed from the rotor core21are supported on the inner periphery of the motor support portion135of the cover member13. The bearings B1positioned on the other end20b(left side in the drawing) are supported on the inner periphery of the cylindrical motor support portion125of the second case member12.

The motor support portion135is disposed facing one end portion21aof the rotor core21with a gap therebetween in the rotation axis X direction on an inner diameter side of a coil end253a, which will be described later, and the motor support portion125is disposed facing the other end portion21bof the rotor core21with a gap therebetween in the rotation axis X direction on an inner diameter side of a coil end253b, which will be described later.

The rotor core21is formed by laminating a plurality of silicon steel plates. The silicon steel plates are fitted onto the motor shaft20such that relative rotation with respect to the motor shaft20is restricted.

When viewed from the rotation axis X direction of the motor shaft20, the silicon steel plate has a ring shape. On an outer peripheral side of the silicon steel plate, N-pole and S-pole magnets (not shown) are alternately provided in a circumferential direction around the rotation axis X.

The stator core25surrounding the outer periphery of the rotor core21is formed by laminating a plurality of electromagnetic steel plates. The stator core25is fixed to the inner periphery of the cylindrical support wall portion111of the first case member11.

Each of the electromagnetic steel plates includes a ring-shaped yoke portion251fixed to the inner periphery of the support wall portion111, and a teeth portion252protruding from an inner periphery of the yoke portion251toward the rotor core21.

In the present embodiment, the stator core25in which a winding253is wound around the plurality of teeth portions252in a distributed manner is adopted. The stator core25is longer than the rotor core21in the rotation axis X direction by lengths of the coil ends253aand253bprotruding in the rotation axis X direction.

A stator core in which windings are concentratedly wound around each of the plurality of teeth portions252protruding toward the rotor core21may be adopted.

The opening120ais provided in the wall portion120(motor support portion125) of the second case member12. The other end20bof the motor shaft20penetrates through the opening120ato the differential mechanism5(left side in the drawing) and is positioned in the gear case14.

The other end20bof the motor shaft20faces a side gear54A, which will be described later, inside the gear case14with a gap therebetween in the rotation axis X direction.

The lip seals RS are inserted between the motor shaft20and the opening120aof the wall portion120.

The oil OL for lubricating the planetary reduction gear4and the differential mechanism5are sealed on an inner diameter side of the gear case14.

The lip seals RS are provided to prevent the oil OL in the gear case14from flowing into the motor case10.

As shown inFIG.4, a sun gear41of the planetary reduction gear4is spline-fitted in a region of the motor shaft20positioned in the gear case14.

A teeth portion41ais formed on an outer periphery of the sun gear41, and a large-diameter gear portion431of a stepped pinion gear43meshes with the teeth portion41a.

The stepped pinion gear43includes the large-diameter gear portion431(large pinion) that meshes with the sun gear41and a small-diameter gear portion432(small pinion) that has a smaller diameter than the large-diameter gear portion431.

The large-diameter gear portion431and the small-diameter gear portion432are integrated gear components disposed side by side in a direction of an axis X1parallel to the rotation axis X.

An outer periphery of the small-diameter gear portion432meshes with an inner periphery of a ring gear42. The ring gear42has a ring shape surrounding the rotation axis X with a gap therebetween. On an outer periphery of the ring gear42, engagement teeth are provided, and the engagement teeth are spline-fitted to a teeth portion146aprovided on an inner periphery of the connection wall portion141b. The ring gear42is restricted from rotating about the rotation axis X.

A pinion shaft44penetrates inner diameter sides of the large-diameter gear portion431and the small-diameter gear portion432. The stepped pinion gear43is rotatably supported on an outer periphery of the pinion shaft44via needle bearings NB, NB.

As shown inFIG.3, the differential mechanism5includes the differential case50as an input element, the drive shafts DA and DB (output shafts) as output elements, and a differential gear set as a differential element. Although detailed description is omitted, the differential case50may be configured by two case members assembled in a rotation axis direction.

The differential case50also functions as a carrier that supports the stepped pinion gear43of the planetary reduction gear4. The stepped pinion gear43is rotatably supported by the differential case50via the pinion shaft44. As shown inFIG.7, three stepped pinion gears43are disposed at intervals in the circumferential direction around the rotation axis X.

As shown inFIG.3, in the differential case50, as the differential gear set, a pinion mate gear52, which is a bevel gear type differential gear, and side gears54A and54B are provided. The pinion mate gear52is supported by a pinion mate shaft51.

The pinion mate shaft51includes a central member510disposed on the rotation axis X and shaft members511connected to an outer diameter side of the central member510. Although not shown, the plurality of shaft members511are provided at equal intervals in the circumferential direction around the rotation axis X. The shaft members511are inserted through a support hole69extending in a radial direction of the differential case50and supported.

The pinion mate gear52is fitted onto the shaft members511and is rotatably supported.

In the differential case50, the side gear54A is positioned on one side of the central member510in the rotation axis X direction, and the side gear54B is positioned on the other side of the central member510. The side gears54A and54B are rotatably supported by the differential case50.

The side gear54A meshes with the pinion mate gear52from one side in the rotation axis X direction. The side gear54B meshes with the pinion mate gear52from the other side in the rotation axis X direction.

An opening60and a tubular wall portion61surrounding the opening60and extending toward the motor case10are provided in a central portion of one end (right side in the drawing) of the differential case50. An outer periphery of the tubular wall portion61is supported by the wall portion120of the second case member12via the bearings B2.

The drive shaft DA inserted through the opening60is inserted into the differential case50from the rotation axis X direction. The drive shaft DA penetrates the insertion hole130aof the wall portion130of the cover member13, and is provided across inner diameter sides of the motor shaft20of the motor2and the sun gear41of the planetary reduction gear4in the rotation axis X direction.

As shown inFIG.3, a through hole65and a tubular wall portion66surrounding the through hole65are formed in a central portion on the other end side (left side in the drawing) of the differential case50. The bearings B2are fitted onto the tubular wall portion66. The bearings B2fitted onto the tubular wall portion66are held by the support portion145of the gear case14. The tubular wall portion66of the differential case50is rotatably supported by the gear case14via the bearings B2.

The drive shaft DB penetrating an opening145aof the gear case14is inserted into the support portion145from the rotation axis X direction. The drive shaft DB is rotatably supported by the support portion145. The tubular wall portion66functions as a shaft support portion that supports the outer periphery of the drive shaft DB.

The lip seals RS are fixed to an inner periphery of the opening145a. Lip portions (not shown) of the lip seals RS are in elastic contact with an outer periphery of the tubular wall portion540of the side gear54B that is fitted onto the drive shaft DB.

Thus, a gap between the outer periphery of the tubular wall portion540of the side gear54B and the inner periphery of the opening145ais sealed.

Inside the differential case50, distal end portions of the drive shafts DA and DB face each other with a gap therebetween in the rotation axis X direction.

The side gears54A and54B supported by the differential case50are spline-fitted to outer peripheries of the distal end portions of the drive shafts DA and DB. The side gears54A and54B and the drive shafts DA and DB are coupled to each other so as to be integrally rotatable about the rotation axis X.

In this state, the side gears54A and54B are disposed facing each other with a gap therebetween in the rotation axis X direction. The central member510of the pinion mate shaft51is positioned between the side gears54A and54B.

The pinion mate gear52is assembled to the side gear54A positioned on one side in the rotation axis X direction and the side gear54B positioned on the other side in the rotation axis X direction such that teeth portions of the side gear54A and the side gear54B mesh with each other.

As shown inFIG.4, a support hole62at one end44aof the pinion shaft44is formed an outer diameter side of the opening60at the one end (right side in the drawing) of the differential case50. A support hole68at the other end44bof the pinion shaft44is formed at the other end (left side in the drawing) of the differential case50.

The support holes62and68are formed at overlapping positions in the rotation axis X direction. The support holes62and68are formed at intervals in the circumferential direction around the rotation axis X in accordance with the position where the stepped pinion gear43is disposed. The one end44aof the pinion shaft44is inserted into the support hole62, and the other end44bis inserted into the support hole68. The other end44bof the pinion shaft44is press-fitted into the support hole68, so that the pinion shaft44is fixed to the differential case50so as not to be rotatable relative to the differential case50. The stepped pinion gear43fitted onto the pinion shaft44is rotatably supported about the axis X1parallel to the rotation axis X.

Although not shown, the oil OL for lubrication is stored inside the gear case14. When the differential case50rotates about the rotation axis X, the oil OL is scraped up by the differential case50.

Although detailed description is omitted, an oil passage, an oil hole, and the like for introducing the oil OL scraped up by the differential case50are provided in the differential case50, the pinion shaft44, and the like. As a result, the oil OL is easily introduced into rotating members such as the bearing B2and the needle bearing NB.

As shown inFIG.7, a catch tank15is provided above the differential case50inside the gear case14. The catch tank15is positioned on one side (left side in the drawing) of a vertical line VL orthogonal to the rotation axis X. The catch tank15and an accommodation portion140of the differential case50communicate with each other via a communication port147. Part of the oil OL scraped up by the differential case50and scattered flows into the catch tank15from the communication port147and is collected.

When the vehicle equipped with the unit1travels forward, the differential case50rotates in a counterclockwise direction CCW about the rotation axis X when viewed from the motor case10. As shown inFIG.4, the small-diameter gear portion432of the stepped pinion gear43meshes with the ring gear42fixed to an inner periphery of the gear case14. Therefore, as shown inFIG.7, the large-diameter gear portion431of the stepped pinion gear43revolves about the rotation axis X in the counterclockwise direction CCW while rotating clockwise about the axis X1.

The catch tank15is positioned on the left side of the vertical line VL, that is, on a downstream side in a rotation direction of the differential case50. As a result, most of the oil OL scraped up by the differential case50rotating about the rotation axis X can flow into the catch tank15.

As shown inFIG.3, the catch tank15is connected to a space Rx between the lip seal RS and the bearing B2via an oil passage151a. The catch tank15is connected to an oil cooler83(seeFIG.6) via an oil passage, a pipe, or the like (not shown). The oil cooler83is connected to the oil hole136a(seeFIG.3) formed in the connection wall136via a pipe, an oil passage, or the like (not shown).

An oil hole Ha is formed in the peripheral wall portion141of the gear case14. The oil hole Ha is connected to the oil hole136bformed in the internal space Sc via a pipe (not shown). The oil OL discharged from the internal space Sc through the oil hole136bis supplied again into the gear chamber Sb through the oil hole Ha.

As shown inFIG.6, the unit1is provided with a circulation system80for the cooling water CL. The circulation system80circulates the cooling water CL between the cooling path CP1of the motor case10and the cooling path CP2of the inverter case17. The circulation system80further includes the oil cooler83, a water pump WP, and a radiator82between the cooling path CP1and the cooling path CP2, which are connected by pipes or the like through which the cooling water CL flows.

The water pump WP feeds the cooling water CL through the circulation system80.

The radiator82is a device that dissipates the heat of the cooling water CL to cool the cooling water CL.

The oil cooler83is a heat exchanger that exchanges heat between the cooling water CL and the oil OL. The oil cooler83is provided with a flow path through which the cooling water CL and the oil OL flow. InFIG.6, the oil cooler83is simplified.

The oil OL collected by the catch tank15provided in the gear chamber Sb of the gear case14is introduced into the oil cooler83. The oil OL is cooled by heat exchange with the cooling water CL. The cooled oil OL is supplied from the oil hole136aof the motor case10to the internal space Sc. The oil OL supplied to the oil cooler83is not limited to the oil OL collected by the catch tank15, and may be supplied from another oil passage appropriately provided in the housing HS. The oil OL discharged from the oil cooler83may be supplied to a location other than the internal space Sc.

The cooling water CL is supplied to the oil cooler83after flowing through the cooling path CP2in the inverter case17and the cooling path CP1in the motor case10. After the heat exchange with the oil OL in the oil cooler83, the cooling water CL is cooled by the radiator82and supplied to the cooling path CP2of the inverter case17again.

As shown inFIG.2, the oil cooler83(heat exchanger) is provided on the inclined portion141c(inclined surface) of the gear case14.

The inclined portion141chas a truncated cone shape that decreases in diameter in a direction away from the motor case10. A space around the inclined portion141cis larger than a space around the motor case10and the like of the unit1by the reduced diameter of the gear case14. In the embodiment, the oil cooler83is disposed in the space around the inclined portion141c. Hereinafter, a configuration of the oil cooler83will be described.

FIG.8is a diagram of the gear case14when viewed from the rotation axis X direction.

FIG.9is a cross-sectional view of a main body portion830of the oil cooler83taken along line A-A inFIG.8. InFIG.9, the gear case14and the drive shaft DB are indicated by imaginary lines for convenience of description.

FIG.10is a diagram of the oil cooler83when viewed in the rotation axis X direction.

FIG.11is a schematic cross-sectional view taken along line A-A inFIG.10.

FIG.12is a schematic cross-sectional view taken along line A-A inFIG.10.

InFIGS.11and12, the gear case14is shown in a simplified manner to explain the flow of the oil OL between the gear case14and the oil cooler83.

As shown inFIG.8, the oil cooler83is disposed adjacent to the catch tank15provided in an upper portion of the gear case14. The oil cooler83includes the main body portion830(arc-shaped portion) formed in an arc shape when viewed in the rotation axis X direction. The main body portion830is disposed in the circumferential direction around the rotation axis X so as to surround the drive shaft DB. Although not shown, the main body portion830is fixed to the inclined portion141cvia bolts or the like. One end in a longitudinal direction of the main body portion830is positioned on one side (right side in the drawing) of the vertical line VL, and the other end is positioned on the other side (left side in the drawing) of the vertical line VL. With respect to a horizontal plane S passing through the rotation axis X and orthogonal to the vertical line VL, the main body portion830has a portion positioned above the horizontal plane S and a portion positioned below the horizontal plane S.

As shown inFIG.9, the main body portion830has a triangular shape in a cross-sectional view. The main body portion830includes a first wall portion831, a second wall portion832, and a third wall portion833.

The first wall portion831is a portion disposed to face an outer periphery of the inclined portion141cwhen the oil cooler83is attached to the gear case14, and is provided in a direction along the rotation axis X. One end portion831aof the first wall portion831in the rotation axis X direction is positioned on an inner diameter side (rotation axis X side) with respect to the other end831b, and the first wall portion831is disposed inclined with respect to the rotation axis X. The first wall portion831is inclined toward an outer diameter side from the one end portion831atoward the other end portion831b.

The second wall portion832extends in the rotation axis X direction from the end portion831bof the first wall portion831.

The third wall portion833extends outward in the radial direction of the rotation axis X from the end portion831aof the first wall portion831. The third wall portion833is provided in a direction substantially orthogonal to the rotation axis X when the oil cooler83is attached to the gear case14.

The third wall portion833connects the end portion831aof the first wall portion831and one end portion832aof the second wall portion832. As shown inFIG.10, the one end and the other end in the longitudinal direction of the main body portion830are closed by fourth wall portions834and834, respectively. The fourth wall portions834and834extend and are connected to the first wall portion831, the second wall portion832, and the third wall portion833.

An internal space Sd surrounded by the first wall portion831, the second wall portion832, the third wall portion833, and the fourth wall portion834is formed in the main body portion830. Flow paths for the oil OL and the cooling water CL are provided in the internal space Sd. For example, the flow paths may be configured by laminating a plurality of plates each having a passage hole formed therein Heat is exchanged by the oil OL and the cooling water CL flowing through the respective flow paths. InFIG.9, the internal space Sd is cross-hatched, and detailed illustration is omitted. Arrows of the oil OL and the cooling water CL shown inFIG.10indicate rough flow directions, not actual flow paths.

As shown inFIG.11, the inclined portion141cconstitutes part of a wall surface of the catch tank15formed in the upper portion of the gear case14. That is, the internal space Sd of the oil cooler83and the catch tank15are adjacent to each other with the inclined portion141cand the first wall portion831interposed therebetween.

As shown inFIG.10, the second wall portion832has an arc shape surrounding the rotation axis X with a gap therebetween when viewed from the rotation axis X direction. When viewed from the rotation axis X direction, the end portion831aof the first wall portion831surrounds the rotation axis X with a gap therebetween and has an arc shape with an outer diameter smaller than that of the second wall portion832.

An introduction portion836and a discharge portion837for the cooling water CL are provided above the main body portion830in the vertical line VL direction. The introduction portion836is provided at one end (right side in the drawing) in the longitudinal direction of the main body portion830, and the discharge portion837is provided at the other end (left side in the drawing).

The introduction portion836has an opening836aprovided through the second wall portion832of the main body portion830, and a peripheral wall portion836bsurrounding the opening836aand extending upward in the vertical line VL direction. The introduction portion836communicates with the flow path (not shown) for the cooling water CL provided in the internal space Sd of the main body portion830via the opening836a.

The discharge portion837has an opening837aprovided through the second wall portion832of the main body portion830, and a peripheral wall portion837bsurrounding the opening837aand extending upward in the vertical line VL direction. The discharge portion837communicates with the flow path (not shown) for the cooling water CL provided in the internal space Sd of the main body portion830via the opening837a.

The introduction portion836and the discharge portion837are positioned above the horizontal plane S. The main body portion830has a portion positioned above the horizontal plane S and connected to the introduction portion836and the discharge portion837, and a portion positioned below the horizontal plane S. In other words, the introduction portion836is connected to the discharge portion837via the portion positioned below the horizontal plane S of the main body portion830. The cooling water CL introduced into the internal space Sd of the main body portion830from the introduction portion836flows from the one end (right side in the drawing) to the other end (left side in the drawing) in the longitudinal direction of the main body portion830, and is discharged from the discharge portion837.

The peripheral wall portion836bof the introduction portion836is connected to the cooling path CP1(seeFIG.6) of the motor case10via a pipe or the like (not shown). The peripheral wall portion837bof the discharge portion837is connected to the radiator82(seeFIG.6) via a pipe or the like (not shown). As shown inFIG.8, the catch tank15is positioned on one side (right side in the drawing) of the vertical line VL along which the introduction portion836is disposed when viewed in the rotation axis X direction.

As shown inFIG.11, the main body portion830has an oil inlet838. The oil inlet838has a hole838apenetrating the first wall portion831in the rotation axis X direction, and a peripheral wall portion838bsurrounding the hole838aand extending in the rotation axis direction toward the gear case14.

As shown inFIG.12, the main body portion830has an oil outlet839. The oil outlet839has a hole839apenetrating the first wall portion831in the rotation axis X direction, and a peripheral wall portion839bsurrounding the hole839a.

As shown inFIG.10, the hole838ais provided at one end (right side in the drawing) in the longitudinal direction of the main body portion830, and the hole839ais provided at the other end (left side in the drawing). That is, the oil inlet838ais positioned on the same side as the introduction portion836of the cooling water CL, and the oil outlet839ais positioned on the same side as the discharge portion837.

The hole838aand the hole839aare positioned above the horizontal plane S. The hole838ais connected to the hole839avia the portion of the main body portion830positioned below the horizontal plane S. The oil OL introduced into the internal space Sd of the main body portion830from the hole portion838aflows from the one end (right side in the drawing) to the other end (left side in the drawing) in the longitudinal direction of the main body portion830and is discharged from the hole839a, similarly to the cooling water CL.

As shown inFIG.11, the inclined portion141cof the gear case14is provided with an opening141dat a position overlapping the hole838ain the rotation axis X direction. The opening141dpenetrates the inclined portion141cin the rotation axis X direction. The peripheral wall portion838bof the oil inlet838is inserted through the opening141dand inserted into the gear chamber Sb.

The peripheral wall portion838bis connected to the catch tank15in the gear chamber Sb via an electric oil pump OP, an oil passage, a pipe, or the like (not shown). As a result, part of the oil OL collected in the catch tank15is fed by the electric oil pump OP and introduced into the internal space Sd of the main body portion830. A seal ring for preventing oil leakage may be provided between the peripheral wall portion838band the opening141d. The hole839amay be provided with a filter for filtering contaminants contained in the oil OL.

As shown inFIG.12, the inclined portion141cof the gear case14is provided with an opening141eat a position overlapping the hole839ain the rotation axis X direction. The opening141epenetrates the inclined portion141cin the rotation axis X direction. The peripheral wall portion839bof the oil outlet839is inserted through the opening141eand inserted into the gear chamber Sb.

The peripheral wall portion839bis connected to the oil hole136a(seeFIG.3) formed in the connection wall136via an oil passage, a pipe, or the like (not shown). As a result, the oil OL discharged from the internal space Sd of the main body portion830is introduced into the internal space Sc (seeFIG.3) formed in the connection wall136. Although not shown, a seal ring for preventing oil leakage may be provided between the peripheral wall portion839band the opening141e. The peripheral wall portion839bmay be connected to the internal space Sc via a pipe or the like provided outside the housing HS instead of being inserted into the gear chamber Sb.

The operation of the unit1having such a configuration will be described.

As shown inFIG.1, in the unit1, the planetary reduction gear4, the differential mechanism5, and the drive shafts DA and DB are provided along a transmission path of output rotation of the motor2.

As shown inFIG.3, when the motor2is driven and the rotor core21rotates about the rotation axis X, the rotation is input to the sun gear41of the planetary reduction gear4via the motor shaft20that rotates integrally with the rotor core21.

In the planetary reduction gear4, the sun gear41serves as an input portion for the output rotation of the motor2, and the differential case50supporting the stepped pinion gear43serves as an output portion for the input rotation.

As shown inFIG.4, when the sun gear41rotates about the rotation axis X by the input rotation, the stepped pinion gear43(large-diameter gear portion431and small-diameter gear portion432) rotates about the axis X1by the rotation input from the sun gear41.

Here, the small-diameter gear portion432of the stepped pinion gear43meshes with the ring gear42fixed to the inner periphery of the gear case14. Therefore, the stepped pinion gear43revolves around the rotation axis X while rotating about the axis X1.

Here, in the stepped pinion gear43, an outer diameter of the small-diameter gear portion432is smaller than an outer diameter of the large-diameter gear portion431.

As a result, the differential case50supporting the stepped pinion gear43rotates about the rotation axis X at a rotation speed lower than that of the rotation input from the motor2.

Therefore, the rotation input to the sun gear41of the planetary reduction gear4is greatly decelerated by the stepped pinion gear43and then output to the differential case50(differential mechanism5).

As shown inFIG.3, when the differential case50rotates about the rotation axis X by the input rotation, the drive shafts DA and DB meshing with the pinion mate gear52rotate about the rotation axis X in the differential case50. As a result, the left and right drive wheels K and K (seeFIG.1) of the vehicle equipped with the unit1are rotated by the transmitted rotational driving force.

As shown inFIG.3, the oil OL for lubrication is stored in the gear chamber Sb. In the gear chamber Sb, when the output rotation of the motor2is transmitted, the stored oil OL is scraped up by the differential case50rotating about the rotation axis X.

As shown inFIGS.3and4, the scraped-up oil OL lubricates a meshing portion between the sun gear41and the large-diameter gear portion431, a meshing portion between the small-diameter gear portion432and the ring gear42, and meshing portions between the pinion mate gear52and the side gears54A and54B.

As shown inFIG.7, the differential case50rotates in the counterclockwise direction CCW about the rotation axis X.

The catch tank15is provided on an upper portion of the gear case14. The catch tank15is positioned on the downstream side in the rotation direction of the differential case50, and part of the oil OL scraped up by the differential case50flows into the catch tank15.

As shown inFIG.3, part of the oil OL flowing into the catch tank15is supplied to the space Rx between the lip seal RS and the bearing B2via the oil passage151ato lubricate the bearing B2. Part of the oil OL flowing into the catch tank15is fed to the electric oil pump OP and introduced to the peripheral wall portion838b(seeFIG.11) of the oil inlet838of the oil cooler83. The oil OL introduced into the peripheral wall portion838bis introduced into the internal space Sd of the main body portion830through the hole838a. As shown inFIG.10, the oil OL introduced to the one end (right side in the drawing) in the longitudinal direction of the main body portion830flows toward the hole839aat the other end through the flow path (not shown) formed in the internal space Sd.

As shown inFIG.11, the cooling water CL after flowing through the cooling path CP1(seeFIG.6) is introduced into the internal space Sd of the oil cooler83via the introduction portion836. As shown inFIG.10, the cooling water CL introduced to the one end in the longitudinal direction of the main body portion830flows toward the discharge portion837at the other end through the flow path (not shown) formed in the internal space Sd.

The oil OL introduced into the oil cooler83is scraped up by the differential case50(seeFIG.7) and flows into the catch tank15, and the temperature of the oil OL rises. The oil OL whose temperature rises is cooled by exchanging heat with the cooling water CL whose temperature is lower than that of the oil OL in the internal space Sd.

As shown inFIG.10, the oil OL cooled by heat exchange with the cooling water CL is discharged from the internal space Sd through the hole839aof the oil outlet839. As shown inFIG.12, the oil OL is returned from the peripheral wall portion839bof the oil outlet839to the inside of the gear chamber Sb. Then, the oil OL is supplied to the internal space Sc (seeFIG.3) formed in the connection wall136via an oil passage, a pipe, or the like (not shown). The oil OL supplied to the internal space Sc lubricates the bearing B4and is discharged from the oil hole136b. The oil OL discharged from the oil hole136bis supplied into the gear chamber Sb from the oil hole Ha via a pipe or the like (not shown).

As shown inFIG.3, the housing HS includes the inclined portion141cas an inclined surface surrounding the differential mechanism5in the radial direction of the rotation axis X. As shown inFIG.2, the oil cooler83is disposed at a position overlapping the inclined portion141cwhen viewed in the rotation axis X direction. Disposing the oil cooler83utilizing the space around the inclined portion141ccontributes to a reduction in dimension of the unit1in the radial direction of the rotation axis X.

As shown inFIG.8, the oil cooler83disposed to surround the inclined portion141coverlaps the inclined portion141cwhen viewed in the radial direction of the rotation axis X. This also contributes to a reduction in dimension of the unit1in the rotation axis X direction.

As shown inFIG.8, the main body portion830of the oil cooler83has the portion positioned above the horizontal plane S passing through the rotation axis X and orthogonal to the vertical line VL direction. As shown inFIG.2, the oil cooler83has a portion positioned above the differential mechanism5in the vertical line VL direction. Further, the oil cooler83has a portion overlapping the stepped pinion gear43in the rotation axis X direction. As a result, the oil cooler83has a portion positioned above the unit1in the vertical line VL direction.

As shown inFIG.3, in the unit1, the motor2and the differential mechanism5are coaxial, and the differential mechanism5has a portion overlapping the motor2when viewed in the rotation axis X direction. As described above, in the unit1in which the motor2and the differential mechanism5are coaxial, the layout on an upper side in the vertical line VL direction (vehicle height direction) is less constrained than on a lower side in the vertical line VL direction (vehicle height direction). Since the oil cooler83has the portion positioned above the unit1in the vertical line VL direction in which the layout is less constrained, a surface area of the oil cooler83can be increased. Since a heat exchange rate of the oil cooler83increases as the surface area increases, the oil OL can be efficiently cooled.

The introduction portion836of the cooling water CL positioned above the horizontal plane S is connected to the discharge portion837via the main body portion830having the portion positioned below the horizontal plane S. As a result, the cooling water CL introduced into the internal space Sd of the main body portion830from the introduction portion836can flow to the discharge portion837using gravity. As described above, the circulation system80(seeFIG.6) is provided with the water pump WP that feeds the cooling water CL, and the cooling water CL can flow more smoothly using gravity.

As shown inFIG.10, the hole838aof the oil inlet838positioned above the horizontal plane S is connected to the hole839aof the oil outlet839via the main body portion830having the portion positioned below the horizontal plane S. As a result, the oil OL introduced into the internal space Sd of the main body portion830from the hole838acan flow to the hole839ausing gravity. As shown inFIG.12, the oil OL from the catch tank15is fed by the oil pump OP, and the oil OL can flow more smoothly using gravity.

As shown inFIG.8, the internal space Sd of the oil cooler83is disposed adjacent to the catch tank15. Therefore, the cooling water CL introduced into the internal space Sd exchanges heat with the oil OL in the catch tank15in addition to the oil OL introduced into the internal space Sd. Further, the catch tank15is positioned on the same side as the introduction portion836for the cooling water CL. The low-temperature cooling water CL before heat exchange with the oil OL flows through the introduction portion836. Since the oil OL in the catch tank15exchanges heat with the low-temperature cooling water CL flowing through the introduction portion836, the heat exchange efficiency can be improved.

The unit1may be disposed on a rear side of a vehicle which is less likely to be affected by the traveling wind of the vehicle. As shown inFIG.8, when the unit1is mounted on the vehicle, a vehicle room VR is disposed above a space SP in which the unit1is disposed. The vehicle is provided with a ventilation port VP that communicates the space SP in which the unit1is disposed with the vehicle room VR.

By driving an air conditioner in the vehicle room VR or opening windows of the vehicle room VR, the air Air in the vehicle room VR is discharged from the ventilation port VP and flows into the space SP. The temperature of the air Air in the vehicle room VR is adjusted in accordance with the outside air temperature. For example, when the outside air temperature is high, cooling is used in the vehicle or the windows are opened. For example, when the outside air temperature is low, heating is used.

When the air Air whose temperature is adjusted according to the outside air temperature flows into the space SP, the air exchanges heat with the housing HS disposed in the space SP. As a result, on the rear side of the vehicle which is less likely to be affected by the traveling wind, the heat can be exchanged in a direction in which the temperature of the housing HS approaches the proper temperature. Further, the oil cooler83attached to the housing HS can also exchange heat with the air Air. Thereby, the temperature rise of the oil cooler83can be reduced, and as a result, the heat exchange efficiency between the oil OL and the cooling water CL in the oil cooler83is improved. By improving the heat exchange efficiency of the oil cooler83, the size of the oil cooler83can be reduced, which contributes to a reduction in dimensions of the entire housing HS.

A fan or the like may be provided so that the air Air in the vehicle room VR easily flows into the space SP.

As described above, the unit1according to the embodiment has the following configuration.

(1) The unit1includes the oil cooler83(heat exchanger) and the housing HS configured to accommodate the differential mechanism5(differential gear mechanism).

The housing HS has a portion having the inclined portion141c(inclined surface) surrounding the differential mechanism5in the radial direction.

When viewed in the rotation axis X direction (when viewed in the axial direction), the oil cooler83has a portion that overlaps the inclined portion141c.

This configuration contributes to a reduction in dimension of the unit1in at least one direction.

In the rotation axis X direction, the inclined portion141cof the gear case14is formed such that an outer diameter thereof decreases with increasing distance from the motor case10. When the oil cooler83is disposed as described above, the oil cooler83does not need to protrude greatly in the radial direction of the housing HS, which contributes to a reduction in dimension of the unit1in at least the radial direction of the rotation axis X.

(2) When viewed in the radial direction of the rotation axis X (when viewed in the radial direction), the oil cooler83has a portion that overlaps the inclined portion141c.

When the oil cooler83is disposed as described above, the oil cooler83does not need to protrude greatly in the rotation axis X direction of the housing HS, which contributes to a reduction in dimension of the unit1in both the radial direction of the rotation axis X and the rotation axis X direction.

(3, 4) In the unit1, the differential mechanism5has a portion that overlaps the motor2when viewed in the rotation axis X direction.

The oil cooler83has a portion positioned above the horizontal plane S that passes through an axis of the drive shaft DB, which is an output shaft of the differential mechanism5, and is orthogonal to the vertical line VL direction (gravity direction).

In the unit1in which the motor2and the differential mechanism5are coaxial, the layout on an upper side in the vertical line VL direction (vehicle height direction) is less constrained than on a lower side in the vertical line VL direction (vehicle height direction). Therefore, a surface area of the oil cooler83can be increased by disposing the oil cooler83upward in the vehicle height direction. Since a heat exchange rate of the oil cooler83increases as the surface area increases, the oil OL can be efficiently cooled.

(5) The unit1includes the oil cooler83and the housing HS configured to accommodate the differential mechanism5.

The differential mechanism5has a portion that overlaps the motor2when viewed in the rotation axis X direction.

The oil cooler83has a portion that overlaps the housing HS when viewed in the rotation axis X direction.

The oil cooler83is positioned above the differential mechanism5in the vertical line VL direction.

Disposing the oil cooler83at a position overlapping the inclined portion141cof the gear case14when viewed in the rotation axis X direction contributes to a reduction in dimension of the unit1in at least the radial direction.

In the unit1in which the motor2and the differential mechanism5are coaxial with each other, the layout on an upper side in a vehicle height direction is less constrained than on a lower side in the vehicle height direction. Therefore, the surface area of the oil cooler83can be increased by disposing the oil cooler83upward in the vehicle height direction. Since the heat exchange rate of the oil cooler83increases as the surface area increases, the oil OL can be efficiently cooled.

(6) When viewed in the rotation axis X direction, the oil cooler83has a shape including an arc-shaped portion disposed to surround the rotation axis X which is an axis of the drive shaft DB which is an output shaft of the differential mechanism5.

The oil cooler83includes the main body portion830which is an arc-shaped portion. By forming the oil cooler83in an annular shape surrounding the drive shaft DB, the oil cooler83can be disposed along the shape of the unit1, which contributes to a reduction in dimension of the unit1.

In the embodiment, although the main body portion830of the oil cooler83includes the first wall portion831along the inclined portion141cof the gear case14, the present invention is not limited thereto. The first wall portion81of the oil cooler83may be removed, and the second wall portion832, the third wall portion833, and the fourth wall portion834may be directly joined to the inclined portion141c. As a result, a space surrounded by the second wall portion832, the third wall portion833, the fourth wall portion834, and the inclined portion141cbecomes the internal space Sd. As in the embodiment, flow paths through which the cooling water CL and the oil OL flow may be provided in the internal space Sd.

In an aspect of the present invention, the power transmission mechanism3includes, for example, a gear mechanism and an annular mechanism.

The gear mechanism includes, for example, a reduction gear mechanism, an acceleration gear mechanism, and a differential gear mechanism (differential mechanism).

The reduction gear mechanism and the acceleration gear mechanism include, for example, a planetary gear mechanism and a parallel gear mechanism.

The annular mechanism includes, for example, an endless annular component.

The endless annular component includes, for example, a chain sprocket, a belt, and a pulley.

The differential mechanism5is, for example, a bevel gear type differential gear, a planetary gear type differential gear.

The differential mechanism5includes a differential case as an input element, two output shafts as output elements, and a differential gear set as a differential element.

In the bevel gear type differential gear, the differential gear set includes bevel gears.

In the planetary gear type differential gear, the differential gear set includes planetary gears.

The unit1includes a gear that rotates integrally with the differential case.

For example, a final gear (differential ring gear) of the parallel gear mechanism rotates integrally with the differential case. For example, when a carrier of the planetary gear mechanism is connected to the differential case, a pinion gear rotates (revolves) integrally with the differential case.

For example, a reduction gear mechanism is connected downstream of the motor2. A differential gear mechanism is connected downstream of the reduction gear mechanism. That is, a differential gear mechanism is connected downstream of the motor2via a reduction gear mechanism. An acceleration gear mechanism may be used instead of the reduction gear mechanism.

A single-pinion type planetary gear mechanism can use, for example, a sun gear as an input element, a ring gear as a fixed element, and a carrier as an output element.

A double-pinion type planetary gear mechanism can include, for example, a sun gear as an input element, a ring gear as an output element, and a carrier as a fixed element.

As a pinion gear of the single-pinion type planetary gear mechanism or the double-pinion type planetary gear mechanism, for example, a stepped pinion gear or a non-stepped pinion gear can be used.

The stepped pinion gear includes a large pinion and a small pinion. For example, it is preferable to mesh the large pinion with the sun gear. For example, it is preferable to fit the small pinion into the ring gear.

The non-stepped pinion gear is a type that is not a stepped pinion gear.

In the present embodiment, although an example in which the unit1according to an aspect of the present invention is mounted on a vehicle has been described, the present invention is not limited to this aspect. The present invention can be applied to other than vehicles. When a plurality of examples and modifications are described in the present embodiment, these examples and modifications may be freely combined.

Although the embodiment of the present invention has been described above, the above embodiment is merely an application example of the present invention and is not intended to limit the technical scope of the present invention to the specific configuration of the above embodiment. The embodiment can be changed as appropriate within the scope of the technical idea of the invention.

DESCRIPTION OF REFERENCE SIGNS