Drive device

Abstract

To provide a drive device for a vehicle.SOLUTION: A drive device for a vehicle includes: a motor; a gear unit mechanically connected to the motor; a power conversion unit electrically connected to the motor; a casing; and a cooling system that circulates a heat medium in at least one of a first chamber and a second chamber. The casing has the first chamber and the second chamber separated from each other by a partition wall. The casing houses at least one of the motor and the gear unit in the first chamber and houses the power conversion unit in the second chamber. The cooling system includes a partition-wall cooling path for supplying the heat medium to the partition wall. The cooling system supplies the heat medium to the partition-wall cooling path more when a vehicle speed of the vehicle is low and output torque of the motor is high than that when the vehicle speed is high and the output torque is low.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a drive device for a vehicle. [Background technology]

[0002] The vehicle drive device disclosed in Patent Document 1 has a configuration in which a case that houses a power conversion unit and a case that houses a motor are integrally connected. In this drive device, a partition wall that separates the power conversion unit and the motor is provided with fins for air cooling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-35537 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the drive device of Patent Document 1, the optimization of cooling is not considered. As a result, the amount of heat transferred from the motor to the power conversion unit may increase during low-speed operation when cooling is difficult because of lack of wind while driving, or during high-torque operation when the motor generates a large amount of heat. As a result, the increase in thermal load may shorten the lifespan of various electronic components in the power conversion unit. [Means for solving the problem]

[0005] The present specification discloses a drive device for a vehicle that includes a motor, a gear unit mechanically connected to the motor, a power conversion unit electrically connected to the motor, a casing, and a cooling system that circulates a heat medium in at least one of a first chamber and a second chamber. The casing has a first chamber and a second chamber separated from each other by a partition. The casing houses at least one of the motor and the gear unit in the first chamber, and houses the power conversion unit in the second chamber. The cooling system includes a partition cooling path that supplies the heat medium to the partition. The cooling system includes a partition cooling path that supplies the heat medium to the partition, and supplies a larger amount of heat medium to the partition cooling path when the vehicle speed is low and the output torque is high than when the vehicle speed is high and the output torque of the motor is low.

[0006] The heat medium can take various forms. For example, the heat medium may be oil, water, air, or the like. With the above configuration, the amount of heat medium supplied to the partition cooling path can be appropriately adjusted according to the vehicle speed and output torque. The partition can be cooled even under conditions where cooling the partition is difficult (e.g., low vehicle speed conditions, high torque conditions). Since the amount of heat transferred from the motor to the power conversion unit can be suppressed, it is possible to suppress an increase in the thermal load of the power conversion unit. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing a schematic configuration of a drive device 1. FIG. [Diagram 2] 4 is an example of a torque curve TC of the motor 40. [Diagram 3] 1 is a table showing allocation of oil supply amounts. [Figure 4] FIG. 2 is a diagram showing a schematic configuration of a driving device 101. [Diagram 5] FIG. 2 is a diagram showing a schematic configuration of a driving device 201. [Figure 6] FIG. 2 is a diagram showing a schematic configuration of a driving device 301. [Figure 7] FIG. 4 is a diagram showing a schematic configuration of a driving device 401. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] When a vehicle speed index correlated with the vehicle speed falls below a first threshold value, the cooling system may increase the amount of heat medium supplied to the partition wall cooling path stepwise or continuously as the torque index correlated with the output torque increases.

[0009] According to the above configuration, when the vehicle speed is low, the cooling capacity of the partition can be increased as the heat generated by the motor increases.

[0010] The cooling system may adjust the amount of heat medium supplied to the partition wall cooling path to a first supply amount when the vehicle speed index is below a first threshold value and the torque index is below a second threshold value. The cooling system may adjust the amount of heat medium supplied to the partition wall cooling path to a second supply amount greater than the first supply amount when the vehicle speed index is below the first threshold value and the torque index is above the second threshold value.

[0011] According to the above configuration, when the vehicle speed is low, the output torque of the motor increases (that is, the heat generated by the motor increases), and accordingly, the cooling capacity of the partition can be increased.

[0012] When the torque index correlated with the output torque exceeds a second threshold value, the cooling system may stepwise or continuously reduce the amount of heat medium supplied to the partition wall cooling path as the vehicle speed index correlated with the vehicle speed increases.

[0013] According to the above configuration, when the output torque of the motor is large, the higher the vehicle speed, the more the cooling capacity of the partition can be reduced. This allows the reduction in the cooling capacity of the partition to be allocated to other components such as the motor. This makes it possible to optimize the cooling capacity of the drive unit as a whole.

[0014] The cooling system may adjust the amount of heat medium supplied to the partition wall cooling path to a second supply amount when the torque index exceeds the second threshold value and the vehicle speed index is lower than the first threshold value. The cooling system may adjust the amount of heat medium supplied to the partition wall cooling path to a third supply amount smaller than the second supply amount when the torque index exceeds the second threshold value and the vehicle speed index is higher than the first threshold value.

[0015] According to the above configuration, when the output torque is large, the cooling capacity of the partition can be reduced in response to an increase in vehicle speed, so that the reduced cooling capacity of the partition can be allocated to other components such as the motor.

[0016] At least a motor may be housed in the first chamber. The cooling system may further include a motor cooling path that supplies a heat medium to the motor. The cooling system may switch a ratio of an amount of the heat medium supplied to the partition cooling path to an amount of the heat medium supplied to the motor cooling path between at least two levels in accordance with a combination of a vehicle speed index that correlates with the vehicle speed and a torque index that correlates with the output torque.

[0017] According to the above configuration, the allocation of cooling capacity between the partition wall and the motor can be controlled by controlling the ratio of the supply amount of heat medium between the partition wall and the motor.

[0018] The cooling system may reduce the rate stepwise or continuously for greater vehicle speed indicators when the torque indicator exceeds a second threshold.

[0019] According to the above configuration, when the output torque of the motor is large, the higher the vehicle speed, the more cooling capacity can be allocated to the motor rather than to the partition wall. This makes it possible to reduce the energy consumption of the motor and improve efficiency.

[0020] The cooling system may adjust the ratio to a first ratio when the torque index exceeds a second threshold and the vehicle speed index is below the first threshold. The cooling system may adjust the ratio to a second ratio less than the first ratio when the torque index exceeds the second threshold and the vehicle speed index is above the first threshold.

[0021] According to the above configuration, when the output torque is large, as the vehicle speed increases, a larger cooling capacity can be allocated to the motor than to the partition wall.

[0022] The heat medium may be in a liquid state. The cooling system may further include a pump that supplies the heat medium to the partition cooling path and the motor cooling path. The cooling system may further include a flow rate adjuster that adjusts a ratio of the amount of heat medium supplied to the partition cooling path to the amount of heat medium supplied to the motor cooling path.

[0023] According to the above configuration, the cooling capacity can be allocated between the motor and the partition wall by the pump and the flow rate adjuster.

[0024] The heat medium may be oil. The first chamber may further include a gear compartment for housing the gear unit. The oil may be stored in the first chamber.

[0025] The casing may further include a reservoir for storing oil in a lower portion of the gear compartment. A portion of the gear unit may be immersed in the oil stored in the reservoir. The cooling system may further include a pump for sending the oil stored in the reservoir to the partition cooling path. The cooling system may switch the pump output amount between at least two levels according to a combination of a vehicle speed index correlated with the vehicle speed and a torque index correlated with the output torque.

[0026] According to the above configuration, the allocation of the oil supply capacity between the partition and the gear unit can be controlled by the pump output.

[0027] The cooling system may stepwise or continuously reduce the amount of oil delivered to the partition cooling passage as the vehicle speed index increases.

[0028] According to the above configuration, the amount of oil stored in the storage section can be increased as the vehicle speed increases. Therefore, the higher the vehicle speed, the more the lubricating ability of the oil can be allocated to the gears. This makes it possible to prevent the gears from seizing.

[0029] The first chamber may further include a motor compartment that houses the motor. The cooling system may further include a motor cooling path that supplies oil to the motor. The pump may send the oil stored in the reservoir to the partition cooling path and the motor cooling path. The cooling system may switch a ratio of an amount of oil supplied to the partition cooling path to an amount of oil supplied to the motor cooling path between at least two levels in response to a combination of the vehicle speed index and the torque index.

[0030] According to the above configuration, the allocation of oil supply capacity between the partition wall, the gear unit, and the motor can be controlled.

[0031] The cooling system may reduce the rate stepwise or continuously for greater vehicle speed indicators when the torque indicator exceeds a second threshold.

[0032] According to the above configuration, when the output torque of the motor is large, the higher the vehicle speed, the more cooling capacity can be allocated to the motor rather than to the partition wall. This makes it possible to reduce the energy consumption of the motor and improve efficiency. EXAMPLES

[0033] (Configuration of driving device 1) FIG. 1 shows a schematic configuration of a drive unit 1 of this embodiment. The drive unit 1 is an integrated device in which a motor, a gear unit, and a power conversion unit for controlling the motor are housed in the same casing. FIG. 1 shows the drive unit 1 mounted on a vehicle (electric vehicle). The direction FR indicates the front in the longitudinal direction of the vehicle. The direction RH indicates the right in the lateral direction (or width direction) of the vehicle. And the direction UP indicates the upward direction in the vertical direction of the vehicle. In FIG. 1, multiple shafts (motor shaft 43, countershaft 52, drive shaft 57) are shown developed so as to be located on the same plane. Also, the cooling paths are shown by solid lines.

[0034] The drive device 1 is controlled by a control device 2. The control device 2 includes, for example, a CPU, a RAM, a ROM, an input / output interface, etc. The control device 2 is connected to the power conversion unit 21, the oil pump 64, the variable orifice 66, etc., by signal lines (not shown).

[0035] The drive device 1 includes a casing 10. The casing 10 has a first chamber 11 and a second chamber 12 separated from each other by a partition wall 13.

[0036] The first chamber 11 includes a motor compartment 31 and a gear compartment 32. The two compartments are separated from each other by a partition wall 35. The motor compartment 31 houses a motor 40. The motor 40 includes a stator 41, a rotor 42, and a motor shaft 43. The stator 41 has a cylindrical shape. The rotor 42 is rotatably disposed inside the stator 41. The motor shaft 43 is disposed coaxially with the center of rotation of the rotor 42. The motor shaft 43 is hollow.

[0037] The gear compartment 32 houses a gear unit 50. The gear unit 50 includes a shaft gear 51, a counter shaft 52, a first counter gear 53, a second counter gear 54, a ring gear 55, and a differential gear 56. The shaft gear 51 is attached to the motor shaft 43. This mechanically connects the gear unit 50 and the motor 40.

[0038] A first counter gear 53 and a second counter gear 54 are attached to the counter shaft 52. The first counter gear 53 meshes with the shaft gear 51. The second counter gear 54 meshes with a ring gear 55. The ring gear 55 is attached to a differential gear 56. The differential gear 56 drives a drive shaft 57. When the rotation of the motor 40 is transmitted to the drive shaft 57, a pair of wheels (not shown) connected to the drive shaft 57 rotate. This causes the vehicle to run.

[0039] A reservoir 33 is provided at the bottom of the gear compartment 32. Oil 34 is stored in the reservoir 33. The oil 34 functions as a heat medium for cooling the motor 40, the bulkhead 13, and the gear unit 50, and also functions as a lubricant for the gear unit 50. That is, the oil 34 has a cooling function and a lubricating function. A part of the gear unit 50 is immersed in the oil 34 stored in the reservoir 33. In the example of FIG. 1, the lower part of the differential gear 56 is immersed in the oil 34. The stored oil 34 is scooped up by the differential gear 56, thereby lubricating each gear of the gear unit 50.

[0040] The drive unit 1 also includes a cooling system 60. The cooling system 60 circulates the oil 34 stored in the first chamber 11. The cooling system 60 includes a motor cooling path 61, a partition wall cooling path 62, a strainer 63, an oil pump 64, an oil cooler 65, and a variable orifice 66.

[0041] The motor cooling path 61 is a path that supplies oil to the motor 40. The motor cooling path 61 is a path that extends from the strainer 63 to the motor 40 via the oil pump 64 and the oil cooler 65. The strainer 63 is disposed in the reservoir 33. The oil pump 64 draws the oil 34 in the reservoir 33 through the strainer 63. The oil pump 64 then delivers the drawn oil to the motor cooling path 61 and the partition cooling path 62. The amount of oil delivered by the oil pump 64 is controlled by the control device 2. The details of the control of the amount of oil delivered by the oil pump 64 will be described later. The oil cooler 65 is a heat exchanger that cools the oil by heat exchange with a refrigerant. The oil delivered from the oil cooler 65 is introduced into the upper part of the motor compartment 31.

[0042] The motor cooling path 61 branches into an upper path 61u and an axial path 61a in the motor compartment 31. The upper path 61u has a plurality of discharge holes that open radially downward. The stator 41 is cooled by oil discharged downward from the discharge holes. The motor shaft 43 has a hollow (cylindrical) shape, and the axial path 61a is provided on the axis. The axial path 61a has a plurality of discharge holes that penetrate in the radial direction. The oil that flows out from the discharge holes flows down to the bottom of the motor compartment 31 via holes (not shown) in the rotor 42.

[0043] The partition cooling passage 62 is a passage that supplies oil to the partition 13. The partition cooling passage 62 is a passage that extends from the branch 61b of the motor cooling passage 61, via the variable orifice 66 and the in-wall flow passage 62w, to the motor compartment 31. The variable orifice 66 is a flow rate adjustment unit that controls the flow rate of oil that branches into the partition cooling passage 62 and flows therethrough. In other words, the variable orifice 66 controls the ratio of the amount of oil supplied to the partition cooling passage 62 to the amount of oil supplied to the motor cooling passage 61. The control content of the variable orifice 66 will be described later. The in-wall flow passage 62w is a flow passage that is arranged inside the partition 13.

[0044] The oil supplied to the motor 40 through the motor cooling path 61 and the oil supplied to the partition wall 13 through the partition wall cooling path 62 flow downward within the motor compartment 31. The oil that has flowed downward returns to the reservoir 33 within the gear compartment 32 via a communication hole (not shown) or the like provided in the partition wall 35.

[0045] The second chamber 12 houses a power conversion unit 21. The power conversion unit 21 is a component for controlling the power supplied to the motor 40 and the generated power. Examples of components included in the power conversion unit 21 include an inverter and a converter. The power conversion unit 21 is electrically connected to the motor 40 by a bus bar 22. The power conversion unit 21 also includes a cooling water passage 23. The cooling water passage 23 includes a water pump 24 and a radiator 25. Cooling water circulates through the cooling water passage 23.

[0046] (Oil supply control) The cooling system 60 controls the oil pump 64 and the variable orifice 66 according to a combination of a vehicle speed index and a torque index. The vehicle speed index is an index that correlates with the speed of the vehicle. In this embodiment, the vehicle speed index is the rotation speed of the motor 40. The torque index is an index that correlates with the output torque of the motor 40. In this embodiment, the torque index is a torque command value of the motor 40.

[0047] A specific description will be given with reference to FIG. 2. FIG. 2 shows a torque curve TC of the motor 40. The horizontal axis of FIG. 2 is the rotation speed N of the motor 40, and the vertical axis is the output torque Te. The rotation speed N has a predetermined first threshold value TV1. The output torque Te has a predetermined second threshold value TV2. The first threshold value TV1 and the second threshold value TV2 may be determined in various ways. These threshold values ​​may be fixed values, or may be calculated each time based on a formula or a table, for example.

[0048] In the rotation speed N, a range lower than the first threshold value TV1 is defined as a low speed range LS, and a range higher than the first threshold value TV1 is defined as a high speed range HS. In the low speed range LS, the cooling capacity of the power conversion unit 21 is lower than in the high speed range HS. This is because the lower the vehicle speed, the lower the volume of the running wind passing through the radiator 25, and therefore the amount of heat dissipated by the radiator 25. Here, the running wind is the flow of air that flows into the vehicle when the vehicle is running. As the vehicle speed increases, the volume of the running wind also increases. In addition, as the vehicle speed decreases, the environmental temperature around the drive unit 1 may become more difficult to decrease. In addition, in the high speed range HS, the gear unit 50 is more likely to seize than in the low speed range LS. This is because the faster the gear unit 50 rotates, the more likely oil film rupture occurs.

[0049] In the output torque Te, a range lower than the second threshold TV2 is defined as a low torque range LT, and a range higher than the second threshold TV2 is defined as a high torque range HT. An example of a situation in which the low torque range LT occurs is when driving downhill or on flat ground. An example of a situation in which the high torque range HT occurs is when driving uphill. In the high torque range HT, the amount of heat generated by the motor 40 is greater than in the low torque range LT. This is because the greater the output torque Te, the greater the current flowing through the motor 40.

[0050] As a result of the above, the torque curve TC is divided into four regions: low-speed, low-torque region R1, low-speed, high-torque region R2, high-speed, low-torque region R3, and high-speed, high-torque region R4. The low-speed, low-torque region R1 is defined by the low-speed range LS and the low-torque range LT. The low-speed, high-torque region R2 is defined by the low-speed range LS and the high-torque range HT. The high-speed, low-torque region R3 is defined by the high-speed range HS and the low-torque range LT. The high-speed, high-torque region R4 is defined by the high-speed range HS and the high-torque range HT. The low-speed, low-torque region R1 and the high-speed, low-torque region R3 are regions where the accelerator opening is relatively small. The low-speed, high-torque region R2 and the high-speed, high-torque region R4 are regions where the accelerator opening is relatively large.

[0051] The table in Fig. 3 shows the allocation of the oil supply amount among the partition wall 13, the motor 40, and the gear unit 50. Here, "priority" means that the oil supply amount is increased. The cooling system 60 changes the part to which oil is supplied preferentially in each of the low-speed, low-torque region R1 to the high-speed, high-torque region R4. A specific description will be given below.

[0052] In the low-speed, low-torque region R1, the amount of heat generated by the motor 40 is small, and oil shortage is unlikely to occur in the gear unit 50. Therefore, there is no need to give priority to the supply of oil to any of the motor 40, the gear unit 50, and the partition wall 13.

[0053] In the low-speed, high-torque region R2, the supply of oil to the motor 40 and the partition wall 13 is prioritized over the supply of oil to the gear unit 50. The reason why the cooling of the motor 40 is prioritized is because the amount of heat generated by the motor 40 is large in the high-torque range HT. The reason why the cooling of the partition wall 13 is prioritized is because the cooling capacity of the power conversion unit 21 is low in the low-speed range LS. If the cooling capacity of the power conversion unit 21 decreases, it becomes difficult to remove the amount of heat transferred from the motor 40 through the partition wall 13. Therefore, the thermal load applied to the power conversion unit 21 due to the heat generated by the motor 40 increases. Therefore, by improving the cooling function of the partition wall 13, the heat transfer from the motor 40 can be suppressed. That is, the reduction in the cooling capacity of the power conversion unit 21 due to the reduction in the vehicle speed can be compensated for by the cooling capacity of the partition wall 13.

[0054] In the high-speed, low-torque region R3, the supply of oil to the gear unit 50 is prioritized over the supply of oil to the motor 40 and the partition wall 13. This is because in the high-speed range HS, the gear unit 50 is more likely to seize up. Also, in the low-torque range LT, the amount of heat generated by the motor 40 is small.

[0055] In the high-speed, high-torque region R4, the supply of oil to the motor 40 and the gear unit 50 is prioritized over the supply of oil to the partition wall 13. The reason why cooling of the motor 40 is prioritized is because the amount of heat generated by the motor 40 increases in the high-torque range HT. The reason why lubrication of the gear unit 50 is prioritized is because the gear unit 50 is more likely to become seized in the high-speed range HS. In addition, the reason why cooling of the partition wall 13 does not need to be prioritized is because the amount of air flow during travel increases in the high-speed range HS, thereby increasing the cooling capacity of the power conversion unit 21.

[0056] (Operation and Effects of Cooling System 60) A specific operation of the cooling system 60 for performing the oil supply control shown in Fig. 3 will be described. In a low-speed, low-torque region R1, the cooling system 60 adjusts the amount of oil supplied to the partition cooling passage 62 to a first supply amount (see region A1 in Fig. 3). In a low-speed, high-torque region R2, the cooling system 60 adjusts the amount of oil supplied to the partition cooling passage 62 to a second supply amount that is larger than the first supply amount (see region A2). The control to increase the amount of oil supplied can be performed by at least one of increasing the oil distribution ratio to the partition cooling passage 62 by the variable orifice 66 and increasing the delivery amount of the oil pump 64.

[0057] In other words, in the low speed range LS, the cooling system 60 gradually increases the amount of oil supplied to the partition cooling path 62 as the output torque Te increases (see areas A1 and A2). This makes it possible to increase the cooling capacity of the partition 13 in response to the increase in the output torque of the motor 40 (i.e., the increase in heat generation by the motor 40) when the vehicle speed is low. It becomes possible to suppress the thermal load applied to the power conversion unit 21 due to the heat generation by the motor 40.

[0058] In the low-speed, high-torque region R2, the cooling system 60 adjusts the oil supply amount to the partition cooling passage 62 to a second supply amount (see region A2 in FIG. 3). In the high-speed, high-torque region R4, the cooling system 60 adjusts the oil supply amount to the partition cooling passage 62 to a third supply amount that is smaller than the second supply amount (see region A3).

[0059] In other words, in the high torque range HT, the cooling system 60 gradually reduces the amount of oil supplied to the partition cooling path 62 as the vehicle speed increases (see areas A2 and A3). This allows the cooling capacity of the partition 13 to be reduced in response to an increase in vehicle speed when the output torque is large. Therefore, the reduced cooling capacity of the partition 13 can be allocated to other components such as the motor 40. It becomes possible to optimize the overall cooling capacity of the drive unit 1.

[0060] In the low-speed, high-torque region R2, the cooling system 60 adjusts the ratio of the amount of oil supplied to the partition cooling path 62 to the amount of oil supplied to the motor cooling path 61 to a first ratio (see regions A2 and A4 in FIG. 3). In the high-speed, high-torque region R4, the cooling system 60 adjusts the above ratio to a second ratio smaller than the first ratio (see regions A3 and A5). The control to reduce the above ratio can be performed by lowering the oil distribution ratio to the partition cooling path 62 relative to the motor cooling path 61 using the variable orifice 66.

[0061] In other words, in the high torque range HT, the cooling system 60 gradually reduces the oil supply ratio to the partition cooling path 62 as the vehicle speed increases. This allows the cooling capacity to be distributed more to the motor 40 than to the partition 13 as the vehicle speed increases when the output torque of the motor 40 is large. Since the energy consumption of the motor 40 can be suppressed, it is possible to improve efficiency.

[0062] The cooling system 60 prioritizes oil lubrication of the gear unit 50 in the high-speed, high-torque region R4 (see region A7) over oil lubrication of the gear unit 50 in the low-speed, high-torque region R2 (see region A6). Control to increase the oil lubrication of the gear unit 50 can be performed by increasing the oil level in the reservoir 33 by reducing the amount of oil delivered from the oil pump 64.

[0063] In other words, the cooling system 60 gradually reduces the amount of oil delivered from the oil pump 64 as the vehicle speed increases. This allows the gear unit 50 to be allocated more of the lubricating ability of the oil as the vehicle speed increases. This makes it possible to prevent the gear unit 50 from seizing up.

[0064] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or drawings achieves multiple objectives simultaneously, and achieving one of the objectives itself has technical utility.

[0065] (First Modification) FIG. 4 shows a drive device 101 according to a first modified example. In the following, the same reference numerals are used to designate parts common to the drive device of the modified example and the drive device 1 (FIG. 1) of this embodiment, and description thereof will be omitted. The drive device 101 includes a cooling pipe 162p instead of the in-wall circulation path 62w of the drive device 1. The cooling pipe 162p is disposed in the motor compartment 31 so as to face the partition wall 13. The cooling pipe 162p is provided with a plurality of discharge holes that open toward the partition wall 13. Oil is ejected toward the partition wall 13 from each of the plurality of discharge holes. The partition wall 13 can be cooled.

[0066] (Second Modification) FIG. 5 shows a drive device 201 according to a second modification. The drive device 201 further includes a gear cooling path 263. The gear cooling path 263 is a path that supplies oil to the gear unit 50. The gear cooling path 263 is a path that extends from the branch 61c of the motor cooling path 61 to the gear compartment 32 via a variable orifice 268. A variable orifice 267 is also disposed in the motor cooling path 61. The cooling system 60 controls the variable orifices 66, 267, and 268. This allows the oil flow rate to be individually controlled in each of the partition cooling path 62, the axial center path 61a and upper path 61u of the motor 40, and the gear cooling path 263. Note that the gear cooling path 263 may be omitted in the drive device 201.

[0067] (Third Modification) The second chamber 12 may be disposed in various positions. For example, as shown in a driving device 301 according to a third modified example in Fig. 6, the second chamber 12 may be disposed adjacent to the gear compartment 32. This allows unnecessary space in the gear compartment 32 to be used for the second chamber 12, thereby making it possible to further reduce the size of the driving device 301.

[0068] (Fourth Modification) The heat medium for cooling the partition wall 13 is not limited to oil. For example, as shown in a drive device 401 according to a fourth modified example in Fig. 7, the partition wall 13 may be cooled by cooling water. In the drive device 401, the second chamber 12 is disposed adjacent to and above the motor compartment 31. In addition, the ring gear 55 and the drive shaft 57 are shown by dotted lines because they are located on the front side of the vehicle (i.e., the back side of the paper).

[0069] At branch 23b, cooling water passage 23 branches into power conversion unit cooling passage 23p and partition wall cooling passage 23w. Partition wall cooling passage 23w is a passage that returns from branch 23b to water pump 24 via variable orifice 26 and in-wall flow passage 62w. Variable orifice 26 is a flow rate regulator for controlling the flow rate of cooling water that branches into partition wall cooling passage 23w. In other words, variable orifice 26 controls the ratio of the amount of cooling water supplied to partition wall cooling passage 23w to the amount of cooling water supplied to power conversion unit cooling passage 23p.

[0070] In the drive device 401 of the fourth modified example, the amount of heat medium supplied can be controlled in the same manner as in the drive device 1 of the present embodiment. That is, the amount of cooling water supplied to the partition wall cooling path 23w can be appropriately adjusted according to the vehicle speed and output torque. Therefore, even under conditions where it is difficult to cool the partition wall 13 (e.g., low vehicle speed conditions, high torque conditions), it becomes possible to appropriately cool the partition wall 13.

[0071] (Other variations) The vehicle in which the drive device of this specification is installed is not limited to an electric vehicle. The drive device of this specification can be installed in, for example, a hybrid vehicle or a plug-in hybrid vehicle. In this case, the drive device of this specification may house multiple motors in a casing, or may house a planetary gear mechanism. The drive device of this specification can also be applied to vehicles that use an electric motor for at least part of the driving, such as a fuel cell vehicle.

[0072] The first threshold value TV1 for dividing the vehicle speed range and the second threshold value TV2 for dividing the torque range are not limited to one, and may be multiple. Furthermore, the adjustment of the oil supply amount by the cooling system 60 is not limited to a stepwise change. For example, the oil supply amount may be changed continuously in response to a change in the vehicle speed or the change in the output torque.

[0073] The vehicle speed indicator may be various, for example, the actual vehicle speed, and the torque indicator may be various, for example, the current value of the motor 40 or a torque measurement value by a torque sensor.

[0074] The wind flowing inside the vehicle while traveling may pass through not only the radiator 25 but also the surface of the casing 10 of the drive unit. Also, ribs functioning as heat dissipation fins may be provided on the surface of the casing 10. This makes it possible to reduce the thermal load applied from the motor 40 and gear unit 50 to the power conversion unit 21. [Explanation of symbols]

[0075] 1: Drive unit 10: Casing 11: First chamber 12: Second chamber 21: Power conversion unit 33: Reservoir 34: Oil 40: Motor 50: Gear unit 60: Cooling system 61: Motor cooling path 62: Partition cooling path 64: Oil pump 66: Variable orifice N: Rotational speed Te: Output torque

Claims

1. A drive device for a vehicle, comprising: A motor; a gear unit mechanically connected to the motor; a power conversion unit electrically connected to the motor; a casing having a first chamber and a second chamber separated from each other by a partition wall, the casing housing at least one of the motor and the gear unit in the first chamber and housing the power conversion unit in the second chamber; a cooling system that circulates a heat medium through at least one of the first chamber and the second chamber; Equipped with the cooling system includes a partition cooling path that supplies the heat medium to the partition, and an amount of the heat medium supplied to the partition cooling path is made larger when the vehicle speed is low and the output torque of the motor is high than when the vehicle speed is high and the output torque of the motor is low. Drive unit.

2. 2. The drive device according to claim 1, wherein the cooling system increases the amount of the heat medium supplied to the partition cooling path stepwise or continuously as the torque index correlated to the output torque becomes larger when a vehicle speed index correlated to the vehicle speed falls below a first threshold value.

3. The cooling system comprises: When the vehicle speed index is lower than the first threshold value and the torque index is lower than the second threshold value, the supply amount of the heat medium to the partition wall cooling path is adjusted to a first supply amount; 3. The drive device according to claim 2, wherein when the vehicle speed index falls below the first threshold value and the torque index exceeds the second threshold value, the amount of the heat medium supplied to the partition cooling path is adjusted to a second supply amount greater than the first supply amount.

4. 2. The drive device according to claim 1, wherein when a torque index correlated with the output torque exceeds a second threshold value, the cooling system reduces the amount of the heat medium supplied to the partition cooling path in a stepwise or continuous manner as a vehicle speed index correlated with the vehicle speed becomes larger.

5. The cooling system comprises: When the torque index is greater than the second threshold value and the vehicle speed index is less than the first threshold value, the supply amount of the heat medium to the partition wall cooling path is adjusted to a second supply amount; 5. The drive device according to claim 4, wherein when the torque index exceeds the second threshold value and the vehicle speed index exceeds the first threshold value, the amount of the heat medium supplied to the partition cooling path is adjusted to a third supply amount smaller than the second supply amount.

6. At least the motor is housed in the first chamber, 2. The drive device of claim 1, wherein the cooling system further includes a motor cooling path that supplies the heat medium to the motor, and switches a ratio of an amount of the heat medium supplied to the partition cooling path to an amount of the heat medium supplied to the motor cooling path between at least two levels depending on a combination of a vehicle speed index that correlates with the vehicle speed and a torque index that correlates with the output torque.

7. The drive device according to claim 6 , wherein the cooling system is configured to reduce the ratio stepwise or continuously as the vehicle speed indicator increases when the torque indicator exceeds a second threshold value.

8. The cooling system comprises: When the torque indicator is greater than the second threshold and the vehicle speed indicator is less than the first threshold, the ratio is adjusted to a first ratio; The drive device according to claim 7 , wherein when the torque indicator exceeds the second threshold value and the vehicle speed indicator exceeds the first threshold value, the ratio is adjusted to a second ratio that is smaller than the first ratio.

9. The heat transfer medium is liquid, The cooling system comprises: a pump that supplies the heat medium to the partition wall cooling passage and the motor cooling passage; a flow rate adjusting unit that adjusts a ratio of an amount of the heat medium supplied to the partition wall cooling path to an amount of the heat medium supplied to the motor cooling path; The drive arrangement of claim 6 further comprising:

10. The heat transfer medium is oil, The first chamber further includes a gear compartment for storing the gear unit, The drive device of claim 1 , wherein the oil is stored in a first chamber.

11. The casing further includes a reservoir for storing the oil in a lower portion of the gear compartment, a portion of the gear unit is immersed in the oil stored in the storage portion, the cooling system further includes a pump that sends the oil stored in the storage portion to the partition wall cooling path, The drive device according to claim 10 , wherein the cooling system switches the pump output between at least two levels in response to a combination of a vehicle speed indicator correlated with the vehicle speed and a torque indicator correlated with the output torque.

12. The drive device according to claim 11 , wherein the cooling system reduces the amount of the oil delivered to the partition wall cooling path in a stepwise or continuous manner as the vehicle speed index increases.

13. The first chamber further includes a motor compartment that houses the motor, the cooling system further includes a motor cooling passage that supplies the oil to the motor; The pump delivers the oil stored in the storage portion to the partition wall cooling path and the motor cooling path, 13. The drive device according to claim 12, wherein the cooling system switches a ratio of the amount of oil supplied to the partition cooling path to the amount of oil supplied to the motor cooling path between at least two levels in response to a combination of the vehicle speed index and the torque index.

14. The drive device according to claim 13 , wherein the cooling system is configured to reduce the ratio stepwise or continuously as the vehicle speed indicator increases when the torque indicator exceeds a second threshold value.

15. The cooling system comprises: When the vehicle speed indicator is below a first threshold and the torque indicator is above the second threshold, the ratio is adjusted to a first ratio; The drive system of claim 14 , wherein when the vehicle speed indicator exceeds the first threshold and the torque indicator exceeds the second threshold, the ratio is adjusted to a second ratio that is smaller than the first ratio.

16. 16. The drive device according to claim 15, wherein the cooling system further comprises a flow rate adjuster capable of adjusting a ratio of an amount of the heat medium supplied to the partition cooling path to an amount of the heat medium supplied to the motor cooling path.

17. The drive unit according to claim 1 , wherein the partition cooling passage comprises a flow passage disposed within the partition.

18. The drive unit according to claim 1 , wherein the partition cooling path includes a portion for ejecting the heat medium onto the partition.

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