Vehicle drive systems

Abstract

To form a vehicle drive device including an oil cooler with increase in the size of the vehicle drive device inhibited.SOLUTION: A vehicle drive device includes a rotary electric machine 1, an output member, a transmission mechanism, a case 9, and an oil cooler 8. A rotary electric machine housing room 98 and a transmission mechanism housing room 99 are formed within the case 9. The oil cooler 8 includes: an oil storage room 7 which is formed within the case 9 by using a specific inner surface 97 which is a part of an inner surface of the case 9; and a refrigerant passage 81 provided at a specific part 96 which is a portion of the case 9 forming the specific inner surface 97 and configured to circulate a refrigerant. The oil storage room 7 is disposed at a position located within the transmission mechanism housing room 99 and overlapping with the rotary electric machine 1 in an axial view along an axial direction L.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a vehicle drive device including a rotating electric machine, an output member, a transmission mechanism that transmits a driving force between the rotating electric machine and the output member, a case that houses the rotating electric machine and the transmission mechanism, and an oil cooler.

Background Art

[0002] In a vehicle drive device as described above, the rotating electric machine and the transmission mechanism are often lubricated (including cooling) with oil. Since the temperature of the oil used for lubrication rises due to heat exchange with the rotating electric machine and the transmission mechanism, an oil cooler may be provided to cool the oil. International Publication No. 2018 / 030343 discloses a vehicle drive device (motor unit (1)) including such an oil cooler (the reference numerals in parentheses in the background art refer to those of the cited documents). This motor unit (1) includes an oil pump (96) and an oil cooler (97) fixed to the outer peripheral surface of the case (housing (6)) of the motor unit (1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, an oil cooler has little freedom in shape, and for example, its shape in side view is often rectangular. In the case of a vehicle drive device that houses a rotating member, since the outer shape of the case often has an arc shape, when a rectangular parallelepiped oil cooler is arranged on the outer peripheral surface of the case, dead space is likely to occur, and the outer shape of the vehicle drive device is likely to become large.

[0005] In light of the above background, it is desirable to configure a vehicle drive system equipped with an oil cooler while suppressing an increase in the overall size of the vehicle drive system. [Means for solving the problem]

[0006] A vehicle drive system in view of the above problems comprises a rotating electric machine, a pair of output members each driven to a pair of wheels, a transmission mechanism for transmitting driving force between the rotating electric machine and the pair of output members, a case housing the rotating electric machine and the transmission mechanism, and an oil cooler, wherein the rotating electric machine and the pair of output members are arranged on two parallel axes, the transmission mechanism comprises a differential input gear arranged coaxially with the pair of output members to which driving force from the rotating electric machine is transmitted, and a differential gear mechanism for distributing the driving force transmitted to the differential input gear to the pair of output members, and inside the case The device comprises a rotating electric machine housing chamber in which the rotating electric machine is housed and a transmission mechanism housing chamber in which the transmission mechanism is housed, with the direction along the rotation axis of the rotor of the rotating electric machine as the axial direction, and the rotating electric machine housing chamber and the transmission mechanism housing chamber are arranged side by side in the axial direction, and the oil cooler comprises an oil storage chamber formed inside the case using a specific inner surface which is a part of the inner surface of the case, and a refrigerant passage provided in a specific part which is the part of the case that forms the specific inner surface, through which the refrigerant flows, and the oil storage chamber is located inside the transmission mechanism housing chamber and is positioned in a location that overlaps with the rotating electric machine in an axial view along the axial direction.

[0007] In this configuration, a refrigerant passage is formed using a specific part of the case, and an oil storage chamber is formed inside the case using a specific inner surface that corresponds to the inner surface of the said specific part. Therefore, the oil in the oil storage chamber can be cooled by the refrigerant passing through the refrigerant passage. Accordingly, this configuration makes it easier to simplify and miniaturize the structure of the vehicle drive unit compared to cases where a separate oil cooler is provided outside or inside the case. In other words, with this configuration, a vehicle drive unit equipped with an oil cooler can be constructed while suppressing an increase in the size of the vehicle drive unit.

[0008] Further features and advantages of the vehicle drive system will become clear from the following description of exemplary and non-limiting embodiments, which will be illustrated with reference to the drawings. [Brief explanation of the drawing]

[0009] [Figure 1] A cross-sectional view showing an example of a vehicle drive system. [Figure 2] Skeleton diagram of a vehicle drive system [Figure 3] Perspective view showing an example of a vehicle drive system case. [Figure 4] A schematic plan view of the vehicle drive unit as seen from the second axial side with the third case removed. [Figure 5] Schematic plan view of the third case section as seen from the first axial side. [Modes for carrying out the invention]

[0010] Embodiments of a vehicle drive system will be described below with reference to the drawings. In this application, "drive connection" refers to a state in which two rotating elements are connected in a manner that can transmit driving force, and includes a state in which the two rotating elements are connected so as to rotate as a whole, or a state in which the two rotating elements are connected in a manner that can transmit driving force via one or more transmission members. Such transmission members include various members that transmit rotation at the same speed or at a variable speed, such as shafts, gear mechanisms, belts, chains, etc. In addition, the transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices, meshing engagement devices, etc. However, when referring to "drive connection" for each rotating element of a planetary gear mechanism, it refers to a state in which multiple rotating elements in the planetary gear mechanism are connected to each other without the need for other rotating elements.

[0011] Furthermore, regarding the arrangement of the two elements, "overlapping in a specific viewing direction" means that when a virtual line parallel to the line of sight is moved in each direction perpendicular to that virtual line, there exists at least a portion of the region where the virtual line intersects both elements.

[0012] As shown in Figures 1 and 2, the vehicle drive unit 100 comprises a rotating electric machine 1, a pair of output members 2 that are each driven and connected to a pair of wheels W, a transmission mechanism 3 that transmits driving force between the rotating electric machine 1 and the pair of output members 2, and a case 9 that houses the rotating electric machine 1 and the transmission mechanism 3. The rotating electric machine 1 and the pair of output members 2 are arranged on two parallel axes (first axis A1 and second axis A2). The rotating electric machine 1 is positioned on the first axis A1. Inside the case 9, there is a rotating electric machine housing chamber 98 that houses the rotating electric machine 1 and a transmission mechanism housing chamber 99 that houses the transmission mechanism 3.

[0013] The transmission mechanism 3 comprises at least a differential input gear 41 arranged coaxially (on the second shaft A2) with a pair of output members 2 to which the driving force from the rotating electric machine 1 is transmitted, and a differential gear mechanism 4 that distributes the driving force transmitted to the differential input gear 41 to the pair of output members 2. The differential input gear 41 may be considered as being included in the differential gear mechanism 4. That is, the transmission mechanism 3 may be considered as comprising a differential gear mechanism 4 equipped with a differential input gear 41. In this embodiment, the transmission mechanism 3 comprises a differential input gear 41, a differential gear mechanism 4, and a gear mechanism section 30 arranged coaxially (on the first shaft A1) with the rotating electric machine 1 to transmit the driving force from the rotating electric machine 1 to the differential input gear 41. As will be described later, in this embodiment, the gear mechanism section 30 comprises a planetary gear mechanism 31 and a transmission gear 32.

[0014] The rotating electric machine 1, which functions as the driving force source for the wheel W, comprises a stator 11 and a rotor 12. The rotation of the rotor 12 is transmitted to the output member 2 via a transmission mechanism 3. The rotating electric machine 1 has the function of a motor that generates power when power is supplied, and the function of a generator that generates power when power is supplied. Specifically, the rotating electric machine 1 is electrically connected to an energy storage device (not shown), such as a battery or capacitor. The rotating electric machine 1 generates driving force by moving using the power stored in the energy storage device. In addition, the rotating electric machine 1 generates electricity using the driving force transmitted from the wheel W to charge the energy storage device.

[0015] The rotor 12, planetary gear mechanism 31, and transmission gear 32 are arranged on a first axis A1, which serves as their axis. The output member 2, differential input gear 41, and differential gear mechanism 4 are arranged on a second axis A2, which serves as their axis.

[0016] In the following description, the direction parallel to the first axis A1 and the second axis A2 is referred to as the "axial direction L" of the vehicle drive unit 100. One side of the axial direction L is referred to as the "first axial side L1," and the other side of the axial direction L is referred to as the "second axial side L2." In this embodiment, in the axial direction L, the side on which the rotor 12 is positioned relative to the planetary gear mechanism 31 is referred to as the first axial side L1, and the opposite side is referred to as the second axial side L2. Furthermore, the direction perpendicular to the first axis A1 and the second axis A2 is referred to as the "radial direction R" with respect to each axis. Note that if it is not necessary to distinguish which axis is the reference axis, or if it is clear which axis is the reference axis, it may simply be written as "radial direction R." In addition, in the vehicle-mounted state, the direction along the vertical direction is referred to as the up-down direction V, and the upper part along the up-down direction V is referred to as the upper side V1, and the lower part as the lower side V2. In this embodiment, in the vehicle-mounted state, the axial direction L is along the horizontal direction, and the axial direction L and the up-down direction V are perpendicular to each other. Furthermore, as shown in Figures 3 to 5, the direction perpendicular to the axial direction L and the vertical direction V is called the front-rear direction H, the direction in which the first axis A1 is positioned relative to the second axis A2 is called the first front-rear direction H1, and the opposite direction is called the second front-rear direction H2.

[0017] As described above, the vehicle drive unit 100 includes a case 9 that houses the rotating electric machine 1 and the transmission mechanism 3. In this embodiment, the case 9 also houses the output member 2. In this embodiment, the case 9 includes a first case portion 91, a second case portion 92 joined to the first case portion 91 from the axial first side L1, and a third case portion 93 joined to the first case portion 91 from the axial second side L2. The first case portion 91 can also be called the case body, the second case portion 92 the rotating electric machine side cover case, and the third case portion 93 the transmission mechanism side cover case.

[0018] As shown in FIGS. 1 and 3, the first case portion 91 includes a first peripheral wall portion 91a, a second peripheral wall portion 91b, and a partition wall portion 91c. The first peripheral wall portion 91a is formed to cover the outside in the radial direction R of the rotating electric machine 1. The second peripheral wall portion 91b is formed to cover the outside in the radial direction R of the gear mechanism portion 30 (planetary gear mechanism 31, transmission gear 32) and the differential gear mechanism 4. The partition wall portion 91c is formed to partition the internal space (rotating electric machine housing chamber 98) of the first peripheral wall portion 91a and the internal space (transmission mechanism housing chamber 99) of the second peripheral wall portion 91b in the axial direction L. In the present embodiment, the first peripheral wall portion 91a is disposed on the first axial side L1 with respect to the partition wall portion 91c, and the second peripheral wall portion 91b is disposed on the second axial side L2 with respect to the partition wall portion 91c. As shown in FIG. 3, in the first front-rear side H1 of the case 9, the rotating electric machine housing chamber 98 and the transmission mechanism housing chamber 99 are arranged side by side in the axial direction L with the partition wall portion 91c interposed therebetween. In the second front-rear side H2 of the case 9, the transmission mechanism housing chamber 99 is disposed over the entire axial direction L.

[0019] The second case portion 92 includes a first side wall portion 92a. The first side wall portion 92a is formed to cover the first axial side L1 of the rotating electric machine 1. In the present embodiment, the second case portion 92 is joined to the first case portion 91 from the first axial side L1 so that the opening on the first axial side L1 of the first peripheral wall portion 91a is blocked by the first side wall portion 92a.

[0020] The third case portion 93 includes a second side wall portion 93a. The second side wall portion 93a is formed to cover the second axial side L2 of the transmission mechanism 3 and the differential gear mechanism 4. In the present embodiment, the third case portion 93 is joined to the first case portion 91 from the second axial side L2 so that the opening on the second axial side L2 of the second peripheral wall portion 91b is blocked by the second side wall portion 93a.

[0021] In addition, in the present embodiment, an opening is formed in which the first peripheral wall portion 91a is cut out on the upper side V1 of the first case portion 91. This opening is blocked by a fourth case portion (not shown).

[0022] As shown in Fig. 1, the stator 11 of the rotating electrical machine 1 includes a cylindrical stator core 11a fixed to a non-rotating member (here, the first peripheral wall portion 91a of the case 9). A stator coil is wound around the stator core 11a such that a pair of coil end portions 11b protruding on both sides of the stator core 11a in the axial direction L are formed. The rotating electrical machine 1 of the present embodiment is an inner rotor type rotating electrical machine. The rotor 12 of the rotating electrical machine 1 includes a cylindrical rotor core 12a disposed radially inward R1 with respect to the stator core 11a. In the present embodiment, the rotor 12 further includes a rotor shaft 12b connected so as to rotate integrally with the rotor core 12a. The rotor shaft 12b is rotatably supported by a rotor bearing B1. Although not shown, permanent magnets are provided on the rotor core 12a.

[0023] In the present embodiment, the rotor shaft 12b is formed in a cylindrical shape having an axis along the axial direction L. Also, in the present embodiment, the rotor shaft 12b is disposed so as to protrude from both sides of the rotor core 12a in the axial direction L. And the portion of the rotor shaft 12b protruding from the rotor core 12a to the first axial side L1 is rotatably supported with respect to the first side wall portion 92a of the case 9 via a first rotor bearing B11. On the other hand, the portion of the rotor shaft 12b protruding from the rotor core 12a to the second axial side L2 is rotatably supported with respect to the partition wall portion 91c of the case 9 via a second rotor bearing B12.

[0024] As described above, the gear mechanism portion 30 includes a planetary gear mechanism 31 and a transmission gear 32. The planetary gear mechanism 31 decelerates the rotation of the rotor 12 and transmits it to the transmission gear 32. The transmission gear 32 transmits the rotation of the rotor 12 decelerated by the planetary gear mechanism 31 to a differential input gear 41 disposed on a second shaft A2 different from the first shaft A1 on which the rotor 12 and the planetary gear mechanism 31 are disposed.

[0025] The planetary gear mechanism 31 comprises a sun gear SG, a carrier CR, and a ring gear RG. The sun gear SG is connected to the rotor 12 so as to rotate integrally with it. In this embodiment, the sun gear SG is connected to the rotor shaft 12b so as to rotate integrally with it via an input shaft 5. The input shaft 5 is formed to extend along the axial direction L. In this embodiment, the input shaft 5 is formed to extend from the sun gear SG toward the first axial direction L1. As shown in Figure 1, in this embodiment, the input shaft 5 is formed integrally with the sun gear SG.

[0026] Furthermore, as shown in Figure 1, in this embodiment, the input shaft 5 includes a connecting portion 51 and an enlarged diameter portion 52. The connecting portion 51 is connected to the rotor shaft 12b so as to rotate integrally with it. In this embodiment, the connecting portion 51 is positioned to penetrate the partition wall portion 91c of the case 9 in the axial direction L. The connecting portion 51 is positioned radially R inward relative to the rotor shaft 12b and is connected to the rotor shaft 12b by spline engagement. The enlarged diameter portion 52 is formed to have a larger diameter than the connecting portion 51. In this embodiment, the enlarged diameter portion 52 is positioned on the second axial side L2 relative to the partition wall portion 91c. A first thrust bearing B3 that supports the input shaft 5 in the axial direction L is positioned between the enlarged diameter portion 52 and the partition wall portion 91c in the axial direction L.

[0027] The carrier CR rotatably supports a first pinion gear PG1 and a second pinion gear PG2, which rotate integrally with each other. The first pinion gear PG1 meshes with the sun gear SG. The second pinion gear PG2 meshes with the ring gear RG. The second pinion gear PG2 is formed to have a smaller diameter than the first pinion gear PG1. In this embodiment, the second pinion gear PG2 is positioned axially on the first side L1 relative to the first pinion gear PG1. Each of the first pinion gear PG1 and the second pinion gear PG2 rotates (rotates) around its own axis and also revolves (revolves) around the sun gear SG together with the carrier CR. Multiple first pinion gears PG1 and second pinion gears PG2 are provided spaced apart from each other along their respective orbital trajectories. The carrier CR is connected to the transmission gear 32 so as to rotate integrally with it. The ring gear RG is fixed to the second circumferential wall portion 91b of the case 9.

[0028] In this embodiment, the planetary gear mechanism 31 is positioned on the second axial side L2 relative to the rotating electric machine 1 and on the first axial side L1 relative to the transmission gear 32. In other words, in this embodiment, the rotor 12, the planetary gear mechanism 31, and the transmission gear 32 are arranged on the first shaft A1 in the order described above, from the first axial side L1 to the second axial side L2.

[0029] The transmission gear 32 is rotatably supported relative to the case 9 via a first support bearing B2. The first support bearing B2 is positioned radially inward of the transmission gear 32 in the radial direction R, and overlaps with the transmission gear 32 in a radial view along the radial direction R. In this embodiment, the transmission gear 32 is supported axially in L relative to the case 9 by a second thrust bearing B4 and a third thrust bearing B5.

[0030] The differential input gear 41 meshes with the transmission gear 32. The differential input gear 41 is connected to the differential case 40, which will be described later, so as to rotate integrally with it. In this embodiment, the differential input gear 41 is formed to have a larger diameter than the transmission gear 32. Therefore, in this embodiment, the rotation of the carrier CR is reduced between the transmission gear 32 and the differential input gear 41 and transmitted to the differential case 40. In this embodiment, the differential input gear 41 is rotatably supported relative to the case 9 via a second support bearing B6. The second support bearing B6 is located radially inside the differential input gear 41 in the radial direction R, and is positioned to overlap with the differential input gear 41 in a radial view along the radial direction R.

[0031] The differential gear mechanism 4 comprises a differential case 40, a pair of pinion gears 42, and a pair of side gears 45 (a first side gear 43 and a second side gear 44). Here, the pair of pinion gears 42, as well as the first side gear 43 and the second side gear 44, are all bevel gears. The differential case 40 is a hollow member that houses the pair of pinion gears 42, as well as the first side gear 43 and the second side gear 44. The differential case 40 is connected to the differential input gear 41 so as to rotate integrally with it. In this embodiment, the differential case 40 is rotatably supported relative to the case 9 via a differential bearing B7.

[0032] The pair of pinion gears 42 are positioned opposite each other, spaced radially in the direction R with respect to the second shaft A2. The pair of pinion gears 42 are attached to a pinion shaft 42a, which is supported to rotate integrally with the differential case 40. Each of the pair of pinion gears 42 is configured to rotate (rotate) around the pinion shaft 42a and to revolve (orbit) around the second shaft A2.

[0033] The first side gear 43 and the second side gear 44 mesh with a pair of pinion gears 42. The first side gear 43 and the second side gear 44 are arranged to rotate around the second shaft A2 as their axis of rotation. The first side gear 43 is positioned on the first axial side L1 relative to the pinion shaft 42a. The second side gear 44 is positioned on the second axial side L2 relative to the pinion shaft 42a.

[0034] A pair of side gears 45 are connected to a pair of drive shafts DS (see Figure 2). In this embodiment, the first side gear 43 is connected to the first drive shaft DS1 (see Figure 2), which is driven to the wheel W on the first axial side L1, via a transmission shaft 21 extending along the axial direction L, so as to rotate integrally with it. In the example shown in Figure 1, the transmission shaft 21 is inserted radially R inward from the first axial side L1 to the second axial side L2 relative to the first side gear 43, and they are connected to each other by spline engagement. The second side gear 44 is connected to the second drive shaft DS2 (see Figure 2), which is driven to the wheel W on the second axial side L2, so as to rotate integrally with it. In the example shown in Figure 1, the second drive shaft DS2 is inserted radially R inward from the second axial side L2 to the first axial side L1 relative to the second side gear 44, and they are connected to each other by spline engagement. The first side gear 43 and the second side gear 44, which are driven and connected to the drive shaft DS, correspond to the output member 2. The transmission shaft 21 may also be included in the output member 2.

[0035] In such vehicle drive systems 100, the rotating electric machine 1 and the transmission mechanism 3 are often lubricated (including cooled) with oil, and the vehicle drive system 100 of this embodiment is also lubricated with oil. In this embodiment, oil accumulated in the oil reservoir formed in the lower V2 of the case 9 is scraped up by the differential input gear 41 and supplied to lubrication targets such as bearings. Alternatively, the oil accumulated in the oil reservoir may be discharged by an oil pump (not shown) or the like to cool the stator coil of the rotating electric machine 1.

[0036] In order to properly guide the oil scooped up by the differential input gear 41 to the lubrication target, it is preferable to temporarily store the scooped-up oil. For this reason, the vehicle drive unit 100 of this embodiment is equipped with an oil storage chamber 7 that functions as a so-called catch tank and temporarily stores the oil in the case 9. As shown in Figures 3 to 5, the oil storage chamber 7 is formed in a region surrounded by a partition wall 91c, a second circumferential wall 91b (circumferential wall), and a first opposing wall 91d (opposing wall) which is arranged to face the second circumferential wall 91b from the inside of the case 9 and partitions the space between the transmission mechanism 3 and the second circumferential wall 91b.

[0037] As described above, the first case portion 91 is joined to the third case portion 93 on the second axial side L2. As shown in Figure 1, the third case portion 93 has a third circumferential wall portion 93b that extends along the axial direction L from the ends of the second side wall portion 93a in the vertical direction V and the front-rear direction H. The first case portion 91 and the third case portion 93 are joined by the contact between the end of the second circumferential wall portion 91b of the first case portion 91 on the second axial side L2 and the end of the third circumferential wall portion 93b of the third case portion 93 on the first axial side L1.

[0038] As shown in Figure 5, the third case portion 93 includes a second opposing wall portion 93d which is positioned to face the third circumferential wall portion 93b from the inside of the third case portion 93 and demarcates the space between the transmission mechanism 3 and the third circumferential wall portion 93b. The oil storage chamber 7 is also formed in the region surrounded by the second side wall portion 93a, the third circumferential wall portion 93b, and the second opposing wall portion 93d which is positioned to face the third circumferential wall portion 93b from the inside of the case 9 and demarcates the space between the transmission mechanism 3 and the third circumferential wall portion 93b. When the first case portion 91 and the third case portion 93 are joined, the first opposing wall portion 91d and the second opposing wall portion 93d come into contact, forming a continuous opposing wall portion. Therefore, it can also be said that the oil storage chamber 7 is formed in a region surrounded by a partition wall 91c, a peripheral wall (second peripheral wall 91b and third peripheral wall 93b), opposing wall portions (first opposing wall portion 91d and second opposing wall portion 93d) which are arranged to face the peripheral wall portion from the inside of the case 9 and partition the space between the transmission mechanism 3 and the peripheral wall portion, and a second side wall portion 93a.

[0039] In this example, the first opposing wall portion 91d and the second opposing wall portion 93d are integrally formed with the case 9. However, a structure in which a separate member constituting the first opposing wall portion 91d or the second opposing wall portion 93d is attached to the case 9 is also possible.

[0040] As shown in Figures 1 and 4, the gear mechanism 30 has a smaller diameter than the rotating electric machine 1. As shown in Figure 4, the oil reservoir 7 is located inside the transmission mechanism housing chamber 99 and is positioned in a location that overlaps with the rotating electric machine 1 in an axial view along the axial direction L. Because the gear mechanism 30 has a smaller diameter than the rotating electric machine 1, it is easier to secure space within the case 9 around the radial R. Therefore, by arranging the oil reservoir 7 using the space that tends to become dead space above the gear mechanism 30 V1, for example, it is possible to appropriately arrange the oil reservoir 7 inside the case 9 while suppressing an increase in the external size of the vehicle drive unit 100.

[0041] The oil storage chamber 7 includes an opening 73 (see Figure 4, etc.) that opens on the side of the differential input gear 41 at the upper side V1 of the gear mechanism 30, and a communication section 75 (see Figure 5) that communicates with supply oil passages 74 (first supply oil passage 74a, second supply oil passage 74b, third supply oil passage 74c) for supplying oil to lubrication-required locations in at least one of the rotating electric machine 1 and the transmission mechanism 3. This allows oil scraped up by the differential input gear 41 to be properly guided into the oil storage chamber 7 from the opening 73, and the oil stored in the oil storage chamber 7 to be supplied to lubrication-required locations via the communication section 75 and the supply oil passages 74.

[0042] As shown in Figure 4, in this embodiment, the upper end H41 of the differential input gear 41 is positioned above the upper end H30 of the gear mechanism 30 at V1. The opening 73 opens on the side where the upper end H41 of the differential input gear 41 is located.

[0043] As in this embodiment, with respect to the gear mechanism 30 and differential gear mechanism 4 which are arranged on different axes, if the upper end H41 of the differential input gear 41 is positioned above the upper end H30 of the gear mechanism 30 (V1), the gear mechanism 30 and differential gear mechanism 4 will be arranged side by side (in this case, in the front-to-back direction H) when mounted on a vehicle. Therefore, it is easier to reduce the vertical dimension V of the vehicle drive unit 100. In addition, an oil reservoir 7 is located above the gear mechanism 30 (V1), and an opening 73 in the oil reservoir 7 that opens towards the differential input gear 41 is also located above the gear mechanism 30 (V1). Because this opening 73 opens towards the side where the upper end H41 of the differential input gear 41 is located, it is easy to guide the oil scooped up by the differential input gear 41 into the oil reservoir 7.

[0044] As shown in Figure 4, the oil storage chamber 7 is arranged to extend continuously from the upper side V1 of the gear mechanism 30 and surround the side of the gear mechanism 30 opposite to the side of the differential gear mechanism 4 (the first side H1 in the front-rear direction). In other words, the oil storage chamber 7 includes at least a first region 7a located on the upper side V1 of the gear mechanism 30 and a second region 7b located on the first side H1 in the front-rear direction of the gear mechanism 30. This allows the opening 73 of the oil storage chamber 7 to be located on the upper side V1 of the gear mechanism 30, while utilizing the space on the upper side V1 of the gear mechanism 30 and the space on the side of the gear mechanism 30 opposite to the side of the differential gear mechanism 4 to secure the volume of the oil storage chamber 7.

[0045] In this embodiment, the oil reservoir 7 extends continuously from the upper side V1 of the gear mechanism 30, through the side opposite to the differential gear mechanism 4, to the lower side V2 of the gear mechanism 30, surrounding the gear mechanism 30. In other words, the oil reservoir 7 includes a first region 7a located on the upper side V1 of the gear mechanism 30, a second region 7b located on the first side H1 in the front-rear direction of the gear mechanism 30, and a third region 7c located on the lower side V2 of the gear mechanism 30. By also arranging the oil reservoir 7 below the gear mechanism 30 at V2, it is easier to increase the volume of the oil reservoir 7. Since the gear mechanism 30 is configured around a rotating member, its outer shape in an axial view is circular. The case 9 is formed along the outer shape of the gear mechanism 30, but is partially formed in a linear shape considering ease of mounting on a vehicle. Therefore, a space is created between the inner surface of case 9 and the gear mechanism 30, and this space can be used to efficiently form the oil storage chamber 7.

[0046] The supply oil passage 74 is configured to supply oil to the various bearings described above. As shown in Figure 1, the first support bearing B2, the first thrust bearing B3, the second thrust bearing B4, and the third thrust bearing B5 are housed in the transmission mechanism housing chamber 99, so oil can be supplied to these bearings relatively easily from the oil storage chamber 7 via the supply oil passage 74. However, for the rotor bearing B1 (especially the first rotor bearing B11), since it is far from the oil storage chamber 7 in the axial direction L, it is preferable that oil be supplied via an oil passage formed inside the rotor shaft 12b (rotor shaft internal oil passage 12c: see Figure 1). Although not shown, an internal shaft oil passage may also be formed in the input shaft 5 to guide oil to the rotor shaft internal oil passage 12c. Thus, the supply oil passage 74 is configured to supply oil to at least one of the following: a bearing (rotor bearing B1) that supports the rotor shaft 12b which rotates integrally with the rotor 12; bearings (first support bearing B2, first thrust bearing B3, second thrust bearing B4, third thrust bearing B5) that support the rotating shaft of the gear mechanism 30; and an oil passage (rotor shaft internal oil passage 12c) formed inside the rotor shaft 12b.

[0047] The oil stored in the oil storage chamber 7 flows out to the supply oil passage 74 via the communication section 75. The flowing oil then lubricates the lubrication target area and then falls back down to be stored in the oil reservoir. In this embodiment, the oil is configured to also flow through a path that returns it directly from the oil storage chamber 7 to the oil reservoir, in addition to the path through the supply oil passage 74. As shown in Figure 4, the lower part (third region 7c) of the oil storage chamber 7 is located below V2 from the gear mechanism section 30. A discharge section 79 for discharging oil from the oil storage chamber 7 is provided in this lower part (third region 7c).

[0048] As described above, the oil storage chamber 7 is positioned with a third region 7c below the gear mechanism 30 V2, making it easier to increase the volume of the oil storage chamber 7. Furthermore, by storing oil in the oil storage chamber 7, the amount of oil returning to the so-called oil reservoir via the discharge section 79 can be limited, thereby reducing the stirring resistance when the differential input gear 41 scrapes up the oil from the oil reservoir.

[0049] Incidentally, the oil used for lubrication in this manner rises in temperature due to heat exchange with the rotating electric machine 1 and the transmission mechanism 3. For this reason, the vehicle drive unit 100 of this embodiment is equipped with a cooling mechanism for cooling the oil whose temperature has risen due to heat exchange. As shown in Figure 3, a refrigerant passage 81 is provided in the circumferential wall portion (second circumferential wall portion 91b) in which an oil storage chamber 7 is formed on the inside. In this embodiment, a first refrigerant passage 81a and a second refrigerant passage 81b are provided along the vertical direction V on the first axial side L1 and the second axial side L2 of the second circumferential wall portion 91b, respectively. In the example shown in Figure 3, an opening is formed in the portion of the first case portion 91 located on the first front-rear side H1 with respect to the second region 7b, and this opening is closed by a case portion (a case portion that constitutes part of the second circumferential wall portion 91b) which is not shown. As in this example, the second peripheral wall portion 91b may be formed using multiple case portions (here, the first case portion 91 and one or more other case portions) rather than a single case portion (here, the first case portion 91).

[0050] By providing a refrigerant passage 81 through which refrigerant flows in the peripheral wall portion (second peripheral wall portion 91b) forming the oil storage chamber 7, the oil in the oil storage chamber 7 can be cooled by heat exchange between the oil stored in the oil storage chamber 7 and the refrigerant. In other words, the oil storage chamber 7 and the refrigerant passage 81 can be given the function of a so-called cooling mechanism. In this embodiment, the oil cooler 8 is composed of the oil storage chamber 7 and the refrigerant passage 81. The oil storage chamber 7 has the function of a catch tank for temporarily storing the oil in the case 9 and the function of an oil cooler 8 for cooling the oil.

[0051] Here, the oil cooler 8 can also be described as comprising an oil storage chamber 7 formed inside the case 9 using a specific inner surface 97 which is a part of the inner surface of the case 9, and a refrigerant passage 81 provided in a specific section 96 which is the part of the case 9 that forms the specific inner surface 97, through which the refrigerant flows (see Figures 3 to 5). The specific inner surface 97 is the inner surface of the case 9 (the inner surface 91e of the second circumferential wall 91b and the inner surface 93e of the third circumferential wall 93b) corresponding to the circumferential wall portion (the second circumferential wall portion 91b, in particular the second circumferential wall portion 91b) described above. The specific section 96 corresponds to the portion of the circumferential wall portion of the case 9 that forms the specific inner surface 97 (the second circumferential wall portion 91b in this embodiment) that is aligned with the vertical direction V.

[0052] As described above, the oil storage chamber 7 is formed between the specific inner surface 97 (peripheral wall portion (second peripheral wall portion 91b and third peripheral wall portion 93b)) and the opposing wall portion (first opposing wall portion 91d and second opposing wall portion 93d) which is positioned opposite the specific inner surface 97 and demarcates it from the transmission mechanism 3. The opposing wall portion (first opposing wall portion 91d and second opposing wall portion 93d) is positioned along the outer circumference of the gear mechanism portion 30, as shown in Figures 4 and 5. As described above, when forming the oil storage chamber 7 using the space between the inner surface of the case 9 and the gear mechanism portion 30, the opposing wall portion is formed along the outer circumference of the gear mechanism portion 30, making it easy to form an oil storage chamber 7 with sufficient volume using a simple structure.

[0053] As described above, the vehicle drive unit 100 of this embodiment comprises a rotating electric machine 1, a pair of output members 2, a transmission mechanism 3, a case 9, and an oil cooler 8. The rotating electric machine 1 and the pair of output members 2 are arranged on two axes parallel to each other, and the transmission mechanism 3 comprises a differential input gear 41 and a differential gear mechanism 4 arranged coaxially with the pair of output members 2. Inside the case 9, a rotating electric machine housing chamber 98 for housing the rotating electric machine 1 and a transmission mechanism housing chamber 99 for housing the transmission mechanism 3 are formed, and the rotating electric machine housing chamber 98 and the transmission mechanism housing chamber 99 are arranged side by side in the axial direction L. The oil cooler 8 comprises an oil storage chamber 7 formed inside the case 9 using a specific inner surface 97 which is part of the inner surface of the case 9, and a refrigerant passage 81 provided in a specific part 96 which is the part of the case 9 that forms the specific inner surface 97, through which the refrigerant flows. The oil storage chamber 7 is located inside the transmission mechanism housing chamber 99 and is positioned in a location that overlaps with the rotating electric machine 1 in an axial view.

[0054] In this embodiment, the oil storage chamber 7 is configured to store oil scraped up by the differential input gear 41, but it may also be configured to store oil supplied by a method other than scraping, for example, from an oil pump (not shown). That is, if the vehicle drive unit 100 is configured to include an oil cooler 8, and the oil cooler 8 is configured to include an oil storage chamber 7 and a refrigerant passage 81, the source of oil supply to the oil storage chamber 7 is not limited to scraping by gears, but may also be an oil pump or the like.

[0055] According to this embodiment, a refrigerant passage 81 is formed using a specific part 96 of the case 9, and an oil storage chamber 7 is formed inside the case 9 using a specific inner surface 97 that is on the inner surface of the specific part 96. Therefore, the oil in the oil storage chamber 7 can be cooled by the refrigerant passing through the refrigerant passage 81. Consequently, compared to the case in which a separate oil cooler 8 is provided outside or inside the case 9, it is easier to simplify and miniaturize the structure of the vehicle drive unit 100.

[0056] Furthermore, in this embodiment, the transmission mechanism 3 includes a gear mechanism 30 that is arranged coaxially with the rotating electric machine 1 and transmits the driving force from the rotating electric machine 1 to the differential input gear 41. The oil reservoir chamber 7 is arranged to surround the gear mechanism 30 on the side opposite to the differential gear mechanism 4 (first side H1 in the front-rear direction) and the upper side V1. This is preferable.

[0057] With this configuration, the volume of the oil reservoir 7 can be secured by utilizing the space above V1 of the gear mechanism 30 and the space on the opposite side of the gear mechanism 30 from the differential gear mechanism 4. Therefore, it is easy to arrange an oil reservoir 7 with sufficient volume inside the case 9 while suppressing an increase in the external size of the vehicle drive unit 100.

[0058] Furthermore, in this embodiment, the oil reservoir chamber 7 is arranged to surround the gear mechanism 30 on the side opposite to the differential gear mechanism 4 (first side H1 in the front-rear direction) and the upper side V1. The oil reservoir chamber 7 is formed between the specific inner surface 97 (inner surface 91e of the second circumferential wall portion 91b, inner surface 93e of the third circumferential wall portion 93b) and opposing wall portions (first opposing wall portion 91d, second opposing wall portion 93d) that are arranged to face the transmission mechanism 3 and partition the space between the reservoir chamber 7 and the specific inner surface 97. The opposing wall portions (first opposing wall portion 91d, second opposing wall portion 93d) are arranged along the outer circumference of the gear mechanism 30.

[0059] As described above, the vehicle drive unit 100 can have an oil reservoir 7 formed by utilizing the space between the inner surface of the case 9 and the gear mechanism 30. In this case, since the opposing wall portion is formed along the outer circumference of the gear mechanism 30, it is easy to form an oil reservoir 7 with sufficient volume using a simple structure.

[0060] Furthermore, in this embodiment, the oil storage chamber 7 includes an opening 73 that opens on the side of the differential input gear 41 at the upper V1 of the gear mechanism 30, and a communication portion 75 that communicates with a supply oil passage 74 for supplying oil to lubrication-required locations in at least one of the rotating electric machine 1 and the transmission mechanism 3.

[0061] With this configuration, the oil stirred up by the differential input gear 41 can be guided into the oil storage chamber 7 through the opening 73, and the oil stored in the oil storage chamber 7 can be supplied to the parts requiring lubrication via the communication section 75 and the supply oil passage 74. In other words, the oil storage chamber 7 of the oil cooler 8 can be used as a catch tank to temporarily store the oil to be supplied to the parts requiring lubrication. In this way, the oil cooler 8 can be configured to serve as both an oil cooler and a catch tank, so that the external size of the vehicle drive unit 100 can be kept small while providing both the oil cooler 8 and the catch tank inside the case 9.

[0062] Furthermore, in this embodiment, the supply oil passage 74 is configured to supply oil to at least one of the following: a bearing (rotor bearing B1) that supports the rotor shaft 12b which rotates integrally with the rotor 12; bearings (first support bearing B2, first thrust bearing B3, second thrust bearing B4, third thrust bearing B5) that support the rotating shaft of the gear mechanism 30; and an oil passage (rotor shaft internal oil passage 12c) formed inside the rotor shaft 12b.

[0063] The bearings are important lubrication-required parts within the vehicle drive system 100. Furthermore, the oil passages formed inside the rotor shaft 12b facilitate the delivery of oil to the rotor shaft 12b bearing (rotor bearing B1), which is located on the opposite side of the gear mechanism 30 in the axial direction L. According to this embodiment, the supply oil passage 74 facilitates the delivery of oil to the parts that require proper lubrication.

[0064] Furthermore, in this embodiment, the lower part (third region 7c) of the oil storage chamber 7 is located below V2 from the gear mechanism 30, and a discharge section 79 for discharging oil from the oil storage chamber 7 is provided in this lower part (third region 7c).

[0065] By positioning the oil storage chamber 7 below the gear mechanism section 30 (V2), it is easier to increase the volume of the oil storage chamber 7. Furthermore, by storing a large amount of oil in the oil storage chamber 7 that constitutes the oil cooler 8, a large amount of oil can be cooled. Additionally, by providing the discharge section 79 in the lower part of the oil storage chamber 7 (third region 7c), the cooled oil in the oil storage chamber 7 can be circulated within the case. Moreover, by storing oil in the oil storage chamber 7, the amount of oil returning to the oil reservoir via the discharge section 79 can be limited, thus reducing the stirring resistance when, for example, the gears are used to stir up the oil in the oil reservoir.

[0066] [Other Embodiments] Other embodiments will be described below. Note that the configurations of each embodiment described below are not limited to being applied independently, but can also be applied in combination with the configurations of other embodiments, as long as no inconsistencies arise.

[0067] (1) In the above description, an example was given in which the transmission mechanism 3 comprises a differential input gear 41, a differential gear mechanism 4, and a gear mechanism section 30. However, this does not preclude a configuration without the gear mechanism section 30, specifically a configuration without the planetary gear mechanism 31. For example, a configuration may be provided in which only an input gear (a gear corresponding to the transmission gear 32) is arranged on the first shaft A1 and meshes with the differential input gear 41.

[0068] (2) In the above, an example was given in which the gear mechanism 30 includes a planetary gear mechanism 31. However, in addition to the first axis A1 and the second axis A2, a third axis parallel to them may also be included, and a counter gear mechanism, for example, may be arranged on this third axis.

[0069] (3) In the above description, the configuration of the planetary gear mechanism 31 was illustrated in which the carrier CR is connected to the transmission gear 32 so as to rotate integrally with it, and the ring gear RG is fixed to the case 9. However, the ring gear RG may be connected to the transmission gear 32 so as to rotate integrally with it, and the carrier CR may be fixed to the case 9.

[0070] (4) In the above, an example was given in which the oil storage chamber 7 is arranged to surround the gear mechanism 30 on the side opposite to the differential gear mechanism 4 (first side H1 in the front-rear direction) and the upper side V1. However, the oil storage chamber 7 only needs to be able to form an oil cooler 8 together with the refrigerant passage 81. For example, if the refrigerant passage 81 is arranged along the vertical direction V as illustrated in Figures 3 and 4, it is sufficient that the oil storage chamber 7 is arranged at least on the side opposite to the differential gear mechanism 4 (first side H1 in the front-rear direction) in the gear mechanism 30. Also, if the refrigerant passage 81 is arranged along the front-rear direction H (not shown), it is sufficient that the oil storage chamber 7 is arranged at least on the upper side V1 and the lower side V2 in the gear mechanism 30.

[0071] (5) In the above description, a first refrigerant passage 81a and a second refrigerant passage 81b are provided along the vertical direction V on the first axial side L1 and the second axial side L2 of the second peripheral wall portion 91b, respectively, and are illustrated as being connected to the outside of the case 9. However, both or either of the first refrigerant passage 81a and the second refrigerant passage 81b may be connected within the case 9 to another refrigerant passage (not shown) located inside the case 9, and the refrigerant may be shared. For example, if an inverter (not shown) that drives the rotating electric machine 1 is located inside the case 9 or adjacent to the case 9, at least one of the refrigerant passages 81 may be connected to a refrigerant passage arranged to cool the inverter. Similarly, at least one of the refrigerant passages 81 may be connected to a refrigerant passage after the rotating electric machine 1 has been cooled.

[0072] (6) In the above description, an example was given in which the oil storage chamber 7 is arranged along the outer circumference of the gear mechanism 30. However, the oil storage chamber 7 only needs to be able to form an oil cooler 8 together with the refrigerant passage 81, and does not need to be arranged along the outer circumference of the gear mechanism 30.

[0073] (7) In the above, an example was given in which the oil storage chamber 7 has an opening 73 that opens to the side of the differential input gear 41 and a communication portion 75 that communicates with the supply oil passage 74. However, the oil storage chamber 7 does not have to have an opening 73 that receives oil scraped up from the differential input gear 41. It may also have an oil receiving portion that receives the oil scraped up by the differential input gear 41 and an oil passage that guides the oil received by the oil receiving portion to the oil storage chamber 7. Furthermore, it is not necessary for the oil storage chamber 7 to communicate with the supply oil passage 74, and it may also have an example in which oil is supplied to another catch tank, and oil is supplied from that other catch tank to the lubrication target via an oil passage or the like.

[0074] (8) The destination of the oil supplied from the supply oil passage 74 is not limited to at least one of the rotor bearing B1, the first support bearing B2, the first thrust bearing B3, the second thrust bearing B4, the third thrust bearing B5, or the rotor shaft oil passage 12c, but may also be an oil pump, a stator coil, etc.

[0075] (9) In the above description, an example was given in which a discharge section 79 for discharging oil from the oil storage chamber 7 is provided in the third region 7c at the bottom of the oil storage chamber 7. However, such a discharge section 79 may not be provided if, for example, sufficient oil is discharged from the supply oil passage 74 or the like. [Explanation of symbols]

[0076] 1: Rotating electric machine, 2: Output member, 3: Transmission mechanism, 4: Differential gear mechanism, 7: Oil reservoir chamber, 7c: Third region (lower part of oil reservoir chamber), 8: Oil cooler, 9: Case, 12: Rotor, 12b: Rotor shaft, 12c: Oil passage inside rotor shaft (oil passage formed inside the rotor shaft), 30: Gear mechanism section, 41: Differential input gear, 73: Opening, 74: Supply oil passage, 75: Communication section, 79: Discharge section, 81: Coolant passage, 91d: First opposing wall section (opposing wall section), 91e: Inner surface, 93d: Second opposing wall section (opposing wall section), 93e: Inner surface, 96: Specific section, 97: Specific inner surface, 98: Rotating electric machine housing chamber, 99: Transmission mechanism housing chamber, 100 : Vehicle drive unit, A1: First axle, A2: Second axle, B1: Rotor bearing (bearing supporting the rotor shaft), B11: First rotor bearing (bearing supporting the rotor shaft), B12: Second rotor bearing (bearing supporting the rotor shaft), B2: First support bearing (bearing supporting the rotating shaft of the gear mechanism), B3: First thrust bearing (bearing supporting the rotating shaft of the gear mechanism), B4: Second thrust bearing (bearing supporting the rotating shaft of the gear mechanism), B5: Third thrust bearing (bearing supporting the rotating shaft of the gear mechanism), L: Axial direction, L1: First axial side, L2: Second axial side, V: Up and down direction, V1: Upper side, V2: Lower side, W: Wheel

Claims

1. Rotating electric machines and, A pair of output members that are driven and connected to each of the pair of wheels, A transmission mechanism for transmitting driving force between the rotating electric machine and a pair of output members, A case housing the aforementioned rotating electric machine and the aforementioned transmission mechanism, A vehicle drive system equipped with an oil cooler, The rotating electric machine and the pair of output members are arranged on two axes that are parallel to each other. The transmission mechanism comprises a differential input gear arranged coaxially with a pair of output members to transmit driving force from the rotating electric machine, a differential gear mechanism that distributes the driving force transmitted to the differential input gear to the pair of output members, and a gear mechanism arranged coaxially with the rotating electric machine to transmit driving force from the rotating electric machine to the differential input gear. Inside the case, a rotating electric machine housing chamber is formed in which the rotating electric machine is housed, and a transmission mechanism housing chamber is formed in which the transmission mechanism is housed. With the direction along the rotation axis of the rotor of the aforementioned rotating electric machine as the axial direction, the rotating electric machine housing chamber and the transmission mechanism housing chamber are arranged side by side in the axial direction. The oil cooler comprises an oil storage chamber formed inside the case using a specific inner surface which is a part of the inner surface of the case, and a refrigerant passage provided in a specific part which is the part of the case that forms the specific inner surface, through which the refrigerant flows. The aforementioned oil storage chamber is It extends from the upper side of the gear mechanism, through the side opposite to the differential gear mechanism in the gear mechanism, to the lower side of the gear mechanism, and is arranged to surround the perimeter of the gear mechanism, A vehicle drive device located inside the transmission mechanism housing chamber, in a position that overlaps with the rotating electric machine in an axial view along the axial direction.

2. The oil storage chamber is formed between an opposing wall portion, which is positioned opposite the specific inner surface and partitions it from the transmission mechanism, and the specific inner surface. The vehicle drive device according to claim 1, wherein the opposing wall portion is arranged along the outer circumference of the gear mechanism portion.

3. The vehicle drive device according to claim 1 or 2, wherein the oil storage chamber comprises an opening that opens on the side of the differential input gear above the gear mechanism and a communication portion that communicates with a supply oil passage for supplying oil to a lubrication required location in at least one of the rotating electric machine and the transmission mechanism.

4. The vehicle drive device according to claim 3, wherein the supply oil passage is configured to supply oil to at least one of the following: a bearing supporting a rotor shaft that rotates integrally with the rotor; a bearing supporting the rotating shaft of the gear mechanism; and an oil passage formed inside the rotor shaft.

5. The lower part of the oil storage chamber is located below the gear mechanism, and a discharge section for discharging oil from the oil storage chamber is provided at the lower part, as described in claim 1 or 2.

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