WO2025163974A1 - Drive device for vehicle - Google Patents

Abstract

In the present invention, a case comprises a case body (90) having a lower surface opening part (90a) that opens toward a lower side (V2), and a lower surface cover (93) that is attached to the case body (90) so as to close off the lower surface opening part (90a) and that forms at least part of an oil retention part (P). The lower surface cover (93) is provided with an intake port (96) that opens to the oil retention part (P), and a pump attachment part (94) formed in a portion serving as the inner side of the case. An oil pump (OP) is attached to the pump attachment part (94) and is connected to the intake port (96) via an oil passage formed in the lower surface cover (93).

Description

Vehicle drive unit

The present invention relates to a vehicle drive system that includes a rotating electric machine, a power transmission mechanism that transmits power between the rotor of the rotating electric machine and an output member that is drivingly connected to the wheels, a case that houses the rotating electric machine and the power transmission mechanism, and an oil pump that draws in and discharges oil that has accumulated in an oil reservoir at the bottom of the case.

Japanese Patent Publication No. 2023-513899 (Patent Document 1) discloses a transmission oil filter module. Below, in the description of the background art, the reference numerals in parentheses refer to those in Patent Document 1. As shown in Figures 1 to 4 of the document, the transmission oil filter module (1) in Patent Document 1 comprises a housing portion (2), a pump (3), and an oil pan (6). Figures 5 to 7 of Patent Document 1 show the flow of oil within the transmission oil filter module (1).

Special Publication No. 2023-513899

In a vehicle drive device such as the one described above, if the amount of oil in the case increases, the resistance to oil agitation by the rotor and power transmission mechanism increases, which can reduce the efficiency of driving force transmission in the vehicle drive device. Therefore, it is possible to reduce the amount of oil in the case, but if the amount of oil in the case decreases, it can become difficult to properly lubricate the oil pump. Patent Document 1 does not mention this point.

Therefore, it is desirable to develop technology that can properly lubricate the oil pump while minimizing the amount of oil inside the case.

The vehicle drive device disclosed herein is a vehicle drive device comprising: a rotating electric machine with a rotor; an output member drivingly connected to a wheel; a power transmission mechanism that transmits power between the rotor and the output member; a case that houses the rotating electric machine and the power transmission mechanism; and an oil pump that draws in oil accumulated in an oil reservoir below the case through an intake port and discharges it. The case comprises a case body having a bottom opening that opens downward, and a bottom cover that is attached to the case body to close the bottom opening and forms at least a part of the oil reservoir. The bottom cover comprises the intake port that opens into the oil reservoir and a pump mounting portion formed on the inside of the case. The oil pump is attached to the pump mounting portion and is connected to the intake port via an oil passage formed in the bottom cover.

With this configuration, the oil pump is attached to the part of the bottom cover that is inside the case, making it easy to immerse at least a portion of the oil pump in the oil reservoir. Therefore, even if the oil level in the oil reservoir is set low, the oil pump can be properly lubricated by immersing at least a portion of the oil pump in oil. Reducing the amount of oil in the case lowers the oil level in the oil reservoir, but with this configuration, as described above, the oil pump can be properly lubricated even if the oil level in the oil reservoir is set low, making it possible to keep the amount of oil in the case low while still properly lubricating the oil pump.

Furthermore, with this configuration, the oil pump is connected to the intake port via an oil passage formed in the lower cover, making it easier to keep the oil passage from the intake port to the oil pump short. Therefore, with this configuration, there is also the advantage that it is easier to keep the oil intake resistance of the oil pump low.

Further features and advantages of the vehicle drive system will become apparent from the following description of the embodiments, which are explained with reference to the drawings.

1 is an exploded perspective view of a vehicle drive device according to an embodiment; 1 is a skeleton diagram of a vehicle drive device according to an embodiment; 1 is an external view of a vehicle drive device according to an embodiment; 1 is a side view of the inside of a vehicle drive device according to an embodiment; FIG. 1 is a perspective view of a lower cover according to an embodiment; 1 is a cross-sectional view of a portion of a vehicle drive device according to an embodiment;

An embodiment of a vehicle drive device will be described with reference to the drawings.

In the following description, "driving connection" refers to a state in which two rotating elements are connected so that they can transmit driving force, and includes a state in which the two rotating elements are connected so that they rotate as a unit, or a state in which the two rotating elements are connected so that they 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, and chains. Note that transmission members may also include engagement devices that selectively transmit rotation and driving force, such as friction engagement devices and meshing engagement devices. However, when referring to each rotating element of a planetary gear mechanism, the term "driving connection" refers to a state in which the rotating elements are connected so that they can transmit driving force without going through other rotating elements of the planetary gear mechanism.

1 and 2, the vehicle drive device 10 comprises a rotating electric machine 1 having a rotor 11, an output member 40 drivingly connected to wheels W, a power transmission mechanism TA that transmits power between the rotor 11 and the output member 40, and a case 9 that houses the rotating electric machine 1 and the power transmission mechanism TA. Note that Figure 1 omits some components, such as part of the cover member that constitutes the case 9. In this embodiment, the power transmission mechanism TA comprises an input member 2, a counter gear mechanism 3, and a differential gear mechanism 4. The input member 2 is connected to the rotor 11 of the rotating electric machine 1 so as to rotate integrally with the rotor 11. In this embodiment, the input member 2 is splined to a rotor shaft 20 connected to the rotor 11, and rotates integrally with the rotor 11 and the rotor shaft 20. Note that the rotor shaft 20 and the input member 2 may be the same component. The differential gear mechanism 4 distributes the driving force transmitted from the rotating electric machine 1 to a pair of output members 40 that are drivingly connected to a pair of wheels W. The case 9 houses the rotating electric machine 1, the power transmission mechanism TA, and the output member 40.

In this embodiment, the vehicle drive device 10 is equipped with a speed reduction mechanism that reduces the rotation of the input member 2 and transmits it to the output member 40. As shown in FIG. 2, in this embodiment, the speed reduction mechanism is configured to include an input gear 21, a counter gear mechanism 3, and a differential input gear 41. The input gear 21 is connected to the input member 2 so as to rotate integrally with the input member 2. The input gear 21 may be formed integrally with the input member 2, which is a shaft member, from the same member, or may be formed from a member separate from the input member 2 and integrated with the input member 2 by welding or the like. Similarly, the first counter gear 31 and second counter gear 32, described below, may be the same member as the shaft member (counter shaft 30) or may be separate members, and the differential input gear 41 may be the same member as the differential case 42 or may be a separate member.

The counter gear mechanism 3 comprises a first counter gear 31 and a second counter gear 32. The first counter gear 31 and the second counter gear 32 are both connected to the counter shaft 30 so that they rotate integrally. The first counter gear 31 meshes with the input gear 21, and the second counter gear 32 meshes with the differential input gear 41. The differential input gear 41 is connected to the differential case 42 so that they rotate integrally with the differential case 42.

As shown in FIG. 2, the rotating electric machine 1 (rotor 11) and input member 2 are disposed on a first axis A1 (first axis). The counter gear mechanism 3 is disposed on a second axis A2 (second axis), which is a separate axis parallel to the first axis A1. The output member 40 and differential gear mechanism 4 are disposed on a third axis A3 (third axis), which is a separate axis parallel to the first axis A1 and the second axis A2. In this embodiment, as shown in FIG. 1, the first axis A1 is disposed above the second axis A2 and the third axis A3 (V1). Note that while this embodiment illustrates a configuration in which the second axis A2 is disposed above the third axis A3 (V1), the second axis A2 and the third axis A3 may be disposed at the same position in the vertical direction V, or the third axis A3 may be disposed above the second axis A2 (V1).

In the following description, the direction parallel to the first axis A1, second axis A2, and third axis A3 will be referred to as the "axial direction L" of the vehicle drive device 10. One side of the axial direction L will be referred to as the "first axial side L1," and the other side of the axial direction L will be referred to as the "second axial side L2." The direction in which the rotating members orbit their respective rotational axes will be referred to as the "circumferential direction C" (see Figure 1). The directions perpendicular to the first axis A1, second axis A2, and third axis A3 will be referred to as the "radial direction R" based on each axis (see Figure 1). The side of the radial direction R closer to the axis will be referred to as the "radial inner side R1," and the side farther from the axis will be referred to as the "radial outer side R2." Note that when it is not necessary to distinguish which axis is used as the reference, or when it is clear which axis is used as the reference, the term "radial direction R" may be used simply.

Furthermore, when the vehicle drive device 10 is mounted on a vehicle, the direction along the vertical direction is referred to as the up-down direction V, and the upper side along the up-down direction V is referred to as the upper side V1, and the lower side along the up-down direction V is referred to as the lower side V2. In this embodiment, when mounted on a vehicle, 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. In this state, the direction perpendicular to the axial direction L and the up-down direction V is referred to as the fore-aft direction X, and one side of the fore-aft direction X is referred to as the "first fore-aft side X1," and the other side of the fore-aft direction X is referred to as the "second fore-aft side X2."

In this embodiment, the rotating electric machine 1 is exemplified as a wound-field synchronous rotating electric machine (EESM: Electrically Excited Synchronous Motor) having a stator 15 on which multiple phases (N phases, where N is any natural number, for example, three phases) of stator coils 17 are arranged, and a wound-field rotor 11. The rotor structure of a wound-field synchronous rotating electric machine has an electromagnet that uses a field winding (rotor coil 13) instead of a permanent magnet as a field source. The electric circuit unit EU, described later, has a control device and an excitation circuit, and a field current is supplied to the rotor coil 13 from the excitation circuit controlled by the control device via a contactless power supply 18 and a rectifier circuit 19 (see Figure 2). The field magnetic flux generated by the electromagnet can be adjusted by this field current. The excitation circuit adjusts the DC voltage supplied from a DC power source (not shown) so that a set field current flows through the rotor winding 13. The power generated by the excitation circuit is transmitted as AC via the non-contact power supply unit 18, converted to DC by the rectifier circuit 19, and provided to the rotor coil 13.

Compared to permanent magnet synchronous motors (PMSMs), wound-field synchronous rotating electric machines have the following advantages: (1) the variable field flux can be expected to improve efficiency in the medium-high speed, low torque operating range, and the constant output range can be expanded; and (2) they are not affected by supply instability of permanent magnets that use rare earths, etc. For this reason, wound-field synchronous rotating electric machines have recently been increasingly used as a driving force source for the wheels of electric vehicles and hybrid vehicles. For this reason, although an EESM is used as an example of the rotating electric machine 1 in this embodiment, the rotating electric machine 1 may also be a PMSM.

1 and 2, the input member 2, input gear 21, counter gear mechanism 3, and differential gear mechanism 4 are disposed on the first axial side L1 relative to the rotating electric machine 1. As described above, the input member 2, which rotates integrally with the input gear 21, is connected to the rotor shaft 20 so as to rotate integrally with the rotor shaft 20. The first counter gear 31 is disposed on the first axial side L1 relative to the second counter gear 32. In this embodiment, the first counter gear 31 that meshes with the input gear 21 has a larger diameter than the input gear 21, and the rotation of the input member 2 is transmitted to the counter shaft 30 at a reduced speed. Also, in this embodiment, the differential input gear 41 that meshes with the second counter gear 32 has a larger diameter than the second counter gear 32, and the rotation of the counter shaft 30 is transmitted to the differential case 42 that rotates integrally with the differential input gear 41 at a reduced speed.

In this embodiment, a bevel gear type differential gear mechanism 4 is exemplified. The differential gear mechanism 4 includes a plurality of differential pinion gears 44 housed in a differential case 42, and a pair of differential side gears 45. The differential pinion gears 44 are rotatably supported by a differential pinion shaft 43 that is fixed to the differential case 42 and rotates integrally with the differential case 42. The pair of differential side gears 45 mesh with the plurality of differential pinion gears 44. The differential side gears 45 are arranged to rotate around the third axis A3 as their rotation axis. Of the pair of differential side gears 45, the first differential side gear 45 is arranged on the first axial side L1 relative to the differential pinion shaft 43, and the second differential side gear 45 is arranged on the second axial side L2 relative to the differential pinion shaft 43.

In this embodiment, the differential side gears 45 are connected to the output member 40 so as to rotate integrally therewith. The differential side gears 45 are, for example, formed integrally with the output member 40. The differential gear mechanism 4 distributes the driving force transmitted from the rotating electric machine 1 to the differential case 42 to the pair of differential side gears 45, thereby distributing the driving force to the pair of output members 40. The output member 40 connected to the first differential side gear 45 (the output member 40 located on the first axial side L1) is connected to the first drive shaft DS, which is connected to the first wheel W. The output member 40 connected to the second differential side gear 45 (the output member 40 located on the second axial side L2) is connected to the connecting shaft JS, which is connected to the second drive shaft DS, which is connected to the second wheel W.

Note that while a bevel gear type differential gear mechanism 4 has been exemplified here, the differential gear mechanism 4 may also be a planetary gear mechanism. For example, if the differential gear mechanism 4 is a double pinion type planetary gear mechanism, the differential gear mechanism 4 distributes the driving force transmitted from the rotating electric machine 1 to the ring gear to the sun gear and carrier, thereby distributing the driving force to a pair of output members 40.

As shown in FIG. 1, the case 9 includes a first housing chamber E1 and a second housing chamber E2 that is partitioned from the first housing chamber E1. The first housing chamber E1 houses the rotating electric machine 1 and the power transmission mechanism TA, while the second housing chamber E2 houses the electric circuit unit EU. The electric circuit unit EU includes a control device that drives and controls the rotating electric machine 1, an inverter, a smoothing capacitor, and the like. The case 9 includes a case main body 90. The case main body 90 is a core component of the first housing chamber E1 and the second housing chamber E2. In this embodiment, the case 9 further includes a first cover 91, a second cover 92, and a third cover (not shown).

The case body 90 comprises a cylindrical portion having openings on both sides in the axial direction L, and a box-shaped portion. The box-shaped portion is formed so that the side wall portion forming the rectangular opening extends from the peripheral wall of the cylindrical portion to one side in the front-to-rear direction X (here, the second front-to-rear direction side X2). The first cover 91 is a lid member that closes the opening on the first axial side L1 of the cylindrical portion of the case body 90 from the first axial side L1 (see Figures 1 and 3). The second cover 92 is a lid member that closes the opening on the second axial side L2 of the cylindrical portion of the case body 90 from the second axial side L2 (see Figure 3). The third cover is a lid member that closes the opening on the second front-to-rear direction side X2 of the box-shaped portion of the case body 90. A first storage chamber E1 is formed in the space surrounded by the inner wall of the cylindrical portion of the case body 90, the first cover 91, and the second cover 92. Additionally, a second storage chamber E2 is formed in the space surrounded by the outer wall of the cylindrical portion of the case body 90, the side wall of the box-shaped portion, and the third cover.

Because the electric circuit unit EU is housed in the second housing chamber E2 of the case 9, the case 9 is provided with a first connector CN1 to which power wiring from a high-voltage DC power supply (not shown) with a rated voltage of 200 volts or more is connected. As will be described in detail below, a coolant supply port Wi, which serves as the inlet for coolant to cool the power transmission mechanism TA and the electric circuit unit EU (inverter, smoothing capacitor, etc.), and a coolant discharge port Wo, which serves as the outlet for coolant, are also provided on the case 9 or a component attached to the case 9 (e.g., an oil cooler OC).

The case 9 is also provided with a second connector CN2. The second connector CN2 is connected to a power wiring of approximately 12 volts that supplies drive power to the control device in the electric circuit unit EU, as well as signal wiring that is connected to a control device higher in level than the electric circuit unit EU (e.g., a vehicle control device not shown that controls the entire vehicle) and various sensors. The second connector CN2 is also connected to the cable 56 shown in FIG. 4, either directly or via another cable. While the cable 56 is omitted in FIGS. 5 and 6, the cable 56 is connected to a connector 55 of the oil pump OP (described later) to supply at least one of operating power and a control signal to the oil pump OP. In the example shown in FIG. 4, the cable 56 is arranged to pass through a communication port 77 formed at the bottom of the case body 90 and is connected to the oil pump OP (connector 55) located on the second axial side L2 (the far side of the paper in FIG. 4) of the communication port 77. Although details are omitted, after lubricating each part of the power transmission mechanism TA, the oil passes through the communication port 77, as shown by the arrows in Figure 4, and is supplied to the oil reservoir P (described below), which is located on the second axial side L2 of the communication port 77.

The case 9 contains oil for cooling and lubricating the rotating electric machine 1 and the power transmission mechanism TA. The oil is stored in an oil reservoir P (see Figure 6) formed in the lower part of the case 9 (the lower side V2 part). As shown in Figures 5 and 6, the vehicle drive device 10 is equipped with an oil pump OP that draws in and discharges oil stored in the oil reservoir P in the lower part of the case 9 (here, the lower part of the case main body 90) through an intake port 96. An intake oil passage 70 is connected to the intake port 51 (see Figure 6) of the oil pump OP, and a discharge oil passage 74 is connected to the discharge port 52 (see Figure 6) of the oil pump OP. The oil discharged by the oil pump OP is supplied to heat-generating parts such as the rotor coil end 13e and the stator coil end 17e, and to parts that need to be lubricated such as gears and bearings, and then returned to the oil reservoir P. In this embodiment, the vehicle drive system 10 is equipped with an oil cooler OC (heat exchanger) that exchanges heat between oil and a heat medium (coolant in this embodiment). The oil discharged from the oil pump OP is heat exchanged with the heat medium in the oil cooler OC, and is then supplied to the oil supply destinations, such as the heat-generating parts and parts to be lubricated, mentioned above.

5 and 6 , the oil pump OP includes a pump section 53 having a pump rotor and a motor section 54 having an electric motor. While details are omitted, the pump rotor is housed in a pump chamber formed in the pump section 53. The pump rotor is connected to the pump shaft 50 so as to rotate integrally with the pump shaft 50. The motor section 54 includes a connector 55 to which the above-mentioned cable 56 is connected. The electric motor included in the motor section 54 rotates the pump shaft 50 using power supplied via the cable 56. As the pump rotor connected to the pump shaft 50 rotates, oil is drawn into the pump chamber from the suction port 51 and discharged from the discharge port 52. As such, the oil pump OP is equipped with a rotating pump rotor and a drive source (electric motor) that drives the pump rotor.

6, the case body 90 has a bottom opening 90a that opens toward the lower side V2. The case 9 also has a bottom cover 93 that is attached to the case body 90 so as to cover the bottom opening 90a. In the example shown in FIG. 6, the bottom cover 93 is attached to the case body 90 by fastening an attachment portion 98 formed on the bottom cover 93 to the peripheral edge of the bottom opening 90a with bolts (not shown). The bottom cover 93 forms at least a portion of the oil reservoir P. In other words, the bottom cover 93 forms at least a portion of the wall surrounding the oil reservoir P. As shown in FIG. 6, the bottom cover 93 is attached to the case body 90 so as to form at least the bottom wall of the oil reservoir P. In this way, the bottom cover 93 is a member that functions as an oil pan. The bottom cover 93 is positioned below the rotating electric machine 1 on the lower side V2. In this embodiment, the lower cover 93 is positioned so that it at least partially overlaps with the rotating electric machine 1 when viewed in the vertical direction V.

As shown in Figures 5 and 6, the lower cover 93 has an intake port 96 that opens into the oil reservoir P. Note that in Figure 6, the intake port 96, which does not appear in the cross section of Figure 6, is shown with an imaginary line to indicate the location of the intake port 96. As shown in Figure 5, the intake port 96 is located toward the center of the lower cover 93 (in other words, the oil reservoir P) in the axial direction L, and is preferably located in the center of the lower cover 93 in the axial direction L. Also, as shown in Figures 5 and 6, the intake port 96 is located toward the center of the lower cover 93 (in other words, the oil reservoir P) in the fore-and-aft direction X, and is preferably located in the center of the lower cover 93 in the fore-and-aft direction X.

The bottom cover 93 includes a pump mounting portion 94 formed on the inside of the case 9. The oil pump OP is mounted on the pump mounting portion 94. As shown in FIG. 6, the pump mounting portion 94 has an intake port 51 and a discharge port 52 formed therein. The oil pump OP is mounted on the pump mounting portion 94 so that the pump section 53 abuts against the pump mounting portion 94. In the example shown in FIG. 6, the pump mounting portion 94 also includes a shaft accommodating portion that accommodates the tip end of the pump shaft 50 (the end opposite the motor section 54). As shown in FIG. 5, in this embodiment, the bottom cover 93 also includes a strainer mounting portion 95 formed on the inside of the case 9. A strainer ST that filters oil is mounted on the strainer mounting portion 95. The strainer ST is disposed in the intake oil passage 70, which will be described below.

The oil pump OP (specifically, the intake port 51) is connected to the intake port 96 by an intake oil passage 70. The oil pump OP is connected to the intake port 96 via an oil passage formed in the lower cover 93. That is, at least a portion of the intake oil passage 70 is formed in the lower cover 93, and in this embodiment, the entire intake oil passage 70 is formed in the lower cover 93. The intake oil passage 70 includes an oil passage connecting the intake port 96 and the strainer ST, and an oil passage connecting the strainer ST and the oil pump OP. In this embodiment, the intake oil passage 70 includes a first oil passage 71, a second oil passage 72 connected downstream of the first oil passage 71, and a third oil passage 73 connected downstream of the second oil passage 72. The first oil passage 71 forms the "oil passage connecting the intake port 96 and the strainer ST," and the second oil passage 72 and the third oil passage 73 form the "oil passage connecting the strainer ST and the oil pump OP."

At least a portion of the oil passage connecting the suction port 96 and the strainer ST, and at least a portion of the oil passage connecting the strainer ST and the oil pump OP, are formed in the lower cover 93. As described above, in this embodiment, the entire suction oil passage 70 is formed in the lower cover 93. Therefore, the entire oil passage connecting the suction port 96 and the strainer ST, and the entire oil passage connecting the strainer ST and the oil pump OP are formed in the lower cover 93. In other words, the entire first oil passage 71, the entire second oil passage 72, and the entire third oil passage 73 are formed in the lower cover 93.

The oil pump OP (specifically, the discharge port 52) is connected to the connection part 97 by the discharge oil passage 74. At least a portion of the discharge oil passage 74 is formed in the bottom cover 93, and in this embodiment, the entire discharge oil passage 74 is formed in the bottom cover 93. The connection part 97 is provided at an end of the discharge oil passage 74 (the end opposite the oil pump OP). As shown in FIG. 6 , when the bottom cover 93 is attached to the case body 90, the connection part 97 is connected to the case body side oil passage 76 formed in the case body 90. A seal member, for example, is disposed at the connection part between the connection part 97 and the case body side oil passage 76. In this embodiment, the oil supplied from the discharge oil passage 74 to the case body side oil passage 76 is supplied to the oil cooler OC and then to the oil supply destination.

As described above, the lower cover 93 is formed with the intake port 96, pump mounting portion 94, and intake oil passage 70, and in this embodiment, it is also formed with the strainer mounting portion 95 and discharge oil passage 74. Such a lower cover 93 can be formed, for example, by casting and machining.

As shown in Figure 6, in this embodiment, the cover bottom surface 93a, which is the surface of the lower cover 93 that faces the upper side V1 of the portion that will become the inside of the case 9, is arranged at an angle relative to the horizontal. The cover bottom surface 93a becomes the bottom surface of the oil reservoir P when the lower cover 93 is attached to the case main body 90. Note that the cover bottom surface 93a being "arranged at an angle relative to the horizontal" means that it is inclined overall relative to the horizontal, regardless of whether or not it has a partially uneven shape. In this embodiment, the cover bottom surface 93a refers to the portion of the lower cover 93 that will become the inside of the case 9, excluding the side wall portions and functional portions (pump mounting portion 94, strainer mounting portion 95, oil passages, etc.).

6, the pump mounting portion 94 is located on a lower side (here, the second side X2 in the front-to-rear direction) than the intermediate position H2 in the up-down direction V of the cover bottom surface 93a. Note that in FIG. 6, the highest position on the cover bottom surface 93a is the upper end position H1, the lowest position on the cover bottom surface 93a is the lower end position H3, and the central position between the upper end position H1 and the lower end position H3 is the intermediate position H2. In this embodiment, the cover bottom surface 93a is inclined overall toward the lower side V2 as it moves toward one horizontal side (here, the second side X2 in the front-to-rear direction). Therefore, the end on that one horizontal side of the cover bottom surface 93a (here, the end on the second side X2 in the front-to-rear direction) is the lowest point in the oil storage portion P, and the pump mounting portion 94 is located on that one horizontal side (here, the second side X2 in the front-to-rear direction) of the intermediate position H2 on the cover bottom surface 93a. In the example shown in Figure 6, the pump mounting portion 94 is provided at the lower end position H3 of the cover bottom surface 93a. Specifically, the pump mounting portion 94 is provided on a side wall portion (here, a wall portion having an inner surface inclined with respect to the vertical direction V) extending from the lower end position H3 of the cover bottom surface 93a toward the upper side V1. In the example shown in Figures 5 and 6, the connection portion 97 of the discharge oil passage 74 with the case body side oil passage 76 is located on a higher side (here, the first side X1 in the front-rear direction) than the intermediate position H2 of the cover bottom surface 93a in the vertical direction V.

As shown in FIG. 6, in this embodiment, the pump shaft 50 of the oil pump OP is positioned at an angle to the horizontal so as to align with the cover bottom surface 93a. The oil level OL (e.g., the stationary oil level) in the oil reservoir P is set so that at least a portion of the pump shaft 50 is immersed in oil (submerged in oil). The stationary oil level is the oil level OL in the oil reservoir P in a stationary state after a certain amount of time has elapsed since the vehicle stopped. In order to prevent the pump shaft 50 from seizing, the oil level OL is set so that at least the rotatably supported portion of the pump shaft 50 (e.g., the portion housed in the above-mentioned shaft housing of the pump mounting portion 94) is immersed in oil.

In conventional vehicles that use an internal combustion engine to drive the wheels W, the cooling water, whose temperature has risen through heat exchange with the internal combustion engine, is used as a heating source. However, in vehicles that do not have an internal combustion engine, such as electric vehicles, or vehicles that have an internal combustion engine but are sometimes stopped, such as hybrid vehicles, there are fewer heat sources that can use waste heat for heating than in conventional vehicles. For this reason, electric vehicles and hybrid vehicles are increasingly being equipped with electric heaters for heating, or using heat pump systems for heating as well as cooling. Naturally, using an electric heater increases electricity consumption. Furthermore, even in the case of a heat pump system, when the outside temperature is low, the amount of heat pumped from the outside air decreases, which can increase the load on the air conditioner compressor and other components, resulting in increased electricity consumption.

In the vehicle drive device 10 of this embodiment, the oil pump OP is attached to a portion of the lower cover 93 that is inside the case 9. This makes it easy to immerse at least a portion of the oil pump OP in the oil reservoir P, as shown in FIG. 6. Even if the amount of oil in the case 9 is reduced, the oil pump OP can be properly lubricated by immersing at least a portion of the oil pump OP in oil. By reducing the amount of oil in the case 9 in this way, the oil temperature tends to increase more quickly and heat can be easily recovered from the oil (for example, oil after being supplied to heat-generating parts such as the rotor coil 13 and stator coil 17). The recovered heat can then be effectively used as a heat source for heating, etc., improving the energy efficiency of the vehicle as a whole.

Here, the heat medium in the oil cooler OC, which serves as a heat exchanger, is coolant. In this embodiment, as shown in FIG. 3, the oil cooler OC is attached to the outside of the case 9. Coolant is supplied from the coolant supply port Wi, and after cooling the electric circuit unit EU (inverter, smoothing capacitor, etc.) and the rotating electric machine 1 (e.g., stator 15), is supplied to the oil cooler OC. That is, oil and coolant are supplied from inside the case 9 to the oil cooler OC, and the cooled oil is supplied back into the case 9. The coolant is discharged to the outside of the vehicle drive device 10 through the coolant discharge port Wo of the oil cooler OC. The discharged coolant can exchange heat with the air conditioner refrigerant in an air conditioner heat exchanger (chiller or water-cooled condenser) (not shown). The coolant can also exchange heat with the battery cooler coolant in a DC power supply battery cooler. Because DC power supplies' performance deteriorates in low-temperature environments, it is desirable to be able to warm the DC power supply to an appropriate temperature when the temperature of the DC power supply is low, such as when starting a vehicle.

The "heat medium" that exchanges heat with the oil in the case 9 is not limited to coolant, but may be an "air conditioner refrigerant" or a "battery cooler coolant." While this embodiment illustrates an example in which an oil cooler OC is provided outside the case 9, the oil reservoir P itself may be configured to function as an oil cooler OC. In other words, the "heat exchange unit" is not limited to a form in which heat is exchanged between oil and a heat medium outside the oil reservoir P, but may also be a form in which heat is exchanged between oil and a heat medium inside the oil reservoir P.

Other Embodiments
(1) In the above embodiment, a configuration has been described as an example in which the cover bottom surface 93a is inclined relative to the horizontal so that one end of the cover bottom surface 93a in the horizontal direction is the lowest point in the oil storage portion P. However, the present disclosure is not limited to such a configuration, and the cover bottom surface 93a may be inclined relative to the horizontal so that an intermediate portion (e.g., the center) of the cover bottom surface 93a in the horizontal direction is the lowest point in the oil storage portion P. In this case, the cover bottom surface 93a includes a portion that is inclined relative to the horizontal so as to extend overall toward the lower side V2 as it extends toward one side in the horizontal direction, and a portion that is inclined relative to the horizontal so as to extend overall toward the lower side V2 as it extends toward the other side in the horizontal direction. Alternatively, the cover bottom surface 93a may be inclined horizontally (horizontally as a whole).

(2) In the above embodiment, an example was described in which the portion of the case 9 to which the two covers (91, 92) are attached from both sides in the axial direction L is the case main body 90 having a bottom opening 90a. However, the present disclosure is not limited to such a configuration. In other words, the case 9 may be divided in any manner, and any component having a bottom opening 90a to which the bottom cover 93 is attached can serve as the case main body 90.

(3) The configuration of the power transmission mechanism TA shown in the above embodiment is one example, and the configuration of the power transmission mechanism TA can be modified as appropriate. For example, the power transmission mechanism TA may be configured to not include one or both of the counter gear mechanism 3 and the differential gear mechanism 4. The power transmission mechanism TA may also be configured to include a planetary gear mechanism (e.g., a planetary gear reduction mechanism) that transmits power between the rotor 11 and the differential gear mechanism 4, or to transmit power between the rotor 11 and one output member 40 (i.e., one wheel W). The power transmission mechanism TA may also include an engaging element such as a clutch or brake.

(4) In the above embodiment, the vehicle drive device 10 has been described assuming a configuration used as a drive device for an electric vehicle. However, the present disclosure is not limited to such a configuration, and the technology of the present disclosure can also be applied to a drive device for a hybrid vehicle, for example.

(5) In the above embodiment, an example has been described in which the member that rotates integrally with the pair of differential side gears 45 provided in the differential gear mechanism 4 is the output member 40. However, the present disclosure is not limited to such a configuration, and for example, the drive shaft DS in the above embodiment may also be the "output member."

(6) Note that the configurations disclosed in each of the above-described embodiments may be applied in combination with configurations disclosed in other embodiments (including combinations of embodiments described as other embodiments) as long as no contradictions arise. With regard to other configurations, the embodiments disclosed in this specification are merely illustrative in all respects. Therefore, various modifications may be made as appropriate within the scope of the present disclosure.

[Summary of this embodiment]
The above-described embodiment of the vehicle drive device will be summarized below.

The vehicle drive device (10) comprises a rotating electric machine (1) having a rotor (11), an output member (40) drivingly connected to a wheel (W), a power transmission mechanism (TA) that transmits power between the rotor (11) and the output member (40), a case (9) that houses the rotating electric machine (1) and the power transmission mechanism (TA), and an oil pump (OP) that draws in and discharges oil accumulated in an oil reservoir (P) at the bottom of the case (9) through an intake port (96), and the case (9) has a bottom opening that opens toward the bottom side (V2). The oil pump (OP) comprises a case body (90) having a lower opening (90a), and a lower cover (93) attached to the case body (90) so as to close the lower opening (90a) and forming at least a part of the oil reservoir (P). The lower cover (93) has an intake port (96) that opens into the oil reservoir (P) and a pump mounting portion (94) formed on the inside of the case (9). The oil pump (OP) is attached to the pump mounting portion (94) and connected to the intake port (96) via an oil passage formed in the lower cover (93).

With this configuration, the oil pump (OP) is attached to a portion of the bottom cover (93) that is inside the case (9), making it easy to immerse at least a portion of the oil pump (OP) in the oil reservoir (P). Therefore, even if the oil level (OL) in the oil reservoir (P) is set low, the oil pump (OP) can be properly lubricated by immersing at least a portion of the oil pump (OP) in oil. While the oil level (OL) in the oil reservoir (P) drops as the amount of oil in the case (9) is reduced, with this configuration, as described above, the oil pump (OP) can be properly lubricated even if the oil level (OL) in the oil reservoir (P) is set low. This makes it possible to keep the amount of oil in the case (9) low while properly lubricating the oil pump (OP).

Furthermore, with this configuration, the oil pump (OP) is connected to the intake port (96) via an oil passage formed in the lower cover (93), making it easier to keep the oil passage from the intake port (96) to the oil pump (OP) short. Therefore, with this configuration, there is also the advantage that it is easier to keep the oil intake resistance of the oil pump (OP) small.

Here, it is preferable that the bottom cover (93) has a strainer mounting portion (95) formed on the inside of the case (9), a strainer (ST) for filtering oil is mounted on the strainer mounting portion (95), and at least a portion of the oil passage (71) connecting the intake port (96) and the strainer (ST), and at least a portion of the oil passages (72, 73) connecting the strainer (ST) and the oil pump (OP) are formed in the bottom cover (93).

With this configuration, the strainer (ST) is attached to the bottom cover (93), and the oil passages formed in the bottom cover (93) can be used to connect the suction port (96) to the strainer (ST) and to connect the strainer (ST) to the oil pump (OP). Therefore, the oil passage from the suction port (96) to the oil pump (OP) can be kept short, making it easier to keep oil suction resistance low.

Furthermore, it is preferable that the cover bottom surface (93a), which is the surface facing the upper side (V1) of the part of the lower cover (93) that forms the inside of the case (9), is positioned at an angle relative to the horizontal, and that the pump mounting portion (94) is positioned lower than the middle position (H2) of the cover bottom surface (93a) in the vertical direction (V).

With this configuration, the oil pump (OP) is positioned at a relatively low position on the cover bottom surface (93a), making it even easier to immerse at least a portion of the oil pump (OP) in the oil stored in the oil reservoir (P). This makes it easier to lubricate the oil pump (OP).

Furthermore, it is preferable that a discharge oil passage (74) connected to the discharge port (52) of the oil pump (OP) is formed in the bottom cover (93), and that a connection portion (97) is provided at the end of the discharge oil passage (74) which is connected to a case body side oil passage (76) formed in the case body (90) when the bottom cover (93) is attached to the case body (90).

With this configuration, when the oil pump (OP) is attached to the bottom cover (93), the oil discharged from the oil pump (OP) can be appropriately supplied to the case body side oil passage (76).

The vehicle drive device according to the present disclosure is only required to achieve at least one of the above-mentioned effects.

1: Rotating electric machine, 9: Case, 10: Vehicle drive unit, 11: Rotor, 40: Output member, 52: Discharge port, 71: First oil passage (oil passage connecting the intake port and strainer), 72: Second oil passage (oil passage connecting the strainer and oil pump), 73: Third oil passage (oil passage connecting the strainer and oil pump), 74: Discharge oil passage, 76: Case body oil passage, 90: Case body, 90a: Bottom opening, 93: Bottom cover, 93a: Cover bottom, 94: Pump mounting portion, 95: Strainer mounting portion, 96: Intake port, 97: Connection portion, H2: Intermediate position, OP: Oil pump, P: Oil reservoir, ST: Strainer, TA: Power transmission mechanism, V: Vertical direction, V1: Upper side, V2: Lower side, W: Wheel

Claims (4)

A vehicle drive device comprising: a rotating electric machine having a rotor; an output member drivingly connected to a wheel; a power transmission mechanism for transmitting power between the rotor and the output member; a case accommodating the rotating electric machine and the power transmission mechanism; and an oil pump that draws in oil stored in an oil reservoir in a lower part of the case through an intake port and discharges the oil,
The case includes a case body having a bottom opening that opens downward, and a bottom cover that is attached to the case body so as to close the bottom opening and forms at least a part of the oil reservoir,
the lower cover includes the suction port that opens to the oil reservoir and a pump mounting portion that is formed in a portion that becomes the inside of the case,
The oil pump is attached to the pump attachment portion and connected to the intake port via an oil passage formed in the lower cover. the lower cover includes a strainer mounting portion formed in a portion that becomes the inside of the case,
A strainer for filtering oil is attached to the strainer attachment portion,
2. The vehicle drive device according to claim 1, wherein at least a portion of an oil passage connecting the intake port and the strainer, and at least a portion of an oil passage connecting the strainer and the oil pump, are formed in the lower cover. a cover bottom surface, which is a surface of the lower cover facing upward in a portion of the lower cover that will become the inside of the case, is disposed at an angle relative to the horizontal;
The vehicle drive device according to claim 1 or 2, wherein the pump attachment portion is disposed on a lower side than a middle position in the up-down direction of the bottom surface of the cover. a discharge oil passage connected to a discharge port of the oil pump is formed in the lower cover;
3. The vehicle drive device according to claim 1, wherein an end of the discharge oil passage is provided with a connection portion that is connected to a case body side oil passage formed in the case body when the lower cover is attached to the case body.