Drive unit

Abstract

To improve the cooling efficiency in a drive device.SOLUTION: The drive device includes a plurality of rotary electric machines, a plurality of power conversion devices, and a refrigerant circuit having a plurality of refrigerant paths provided in parallel with each other to cool the plurality of rotary electric machines and the plurality of power conversion devices. Each of the plurality of power conversion devices is electrically connected to at least one of the plurality of rotary electric machines. Each of the plurality of refrigerant paths is configured to cool at least one of the plurality of power conversion devices and at least one of the plurality of rotary electric machines. Each of the plurality of rotary electric machines is electrically connected to a power conversion device different from the at least one of the plurality of power conversion devices cooled by the same refrigerant path as itself.SELECTED DRAWING: Figure 3

Description

Technical Field

[0005] ,

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

Background Art

[0002] Patent Document 1 discloses a vehicle having a plurality of rotating electric machines and a plurality of power conversion devices. In the vehicle, the rotating electric machine and the power conversion device electrically connected to each other are cooled by the same refrigerant path.

Prior Art Documents

Patent Documents

[0003] [[ID=,22]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Normally, the same current flows through a rotating electric machine and a power conversion device electrically connected thereto. Therefore, when one of the plurality of rotating electric machines operates at a high load, both the rotating electric machine and the power conversion device electrically connected thereto generate a large amount of heat. At this time, in the technology of Patent Document 1, those rotating electric machines and power conversion devices are cooled by the same refrigerant path. As a result, there is a problem that a large difference in the required cooling amount occurs between the refrigerant path and other refrigerant paths, and the cooling efficiency decreases. In this specification, a technology capable of improving the cooling efficiency in a drive device is provided as compared with the prior art.

Means for Solving the Problems

[0005] The drive system disclosed herein comprises a plurality of rotating electric machines, a plurality of power converters, and a refrigerant circuit having a plurality of refrigerant paths arranged in parallel with each other for cooling the plurality of rotating electric machines and the plurality of power converters. Each of the plurality of power converters is electrically connected to at least one of the plurality of rotating electric machines. Each of the plurality of refrigerant paths is configured to cool at least one of the plurality of power converters and at least one of the plurality of rotating electric machines. Each of the plurality of rotating electric machines is electrically connected to a power converter different from the at least one power converter that is cooled by the same refrigerant path as itself.

[0006] In the drive system described above, the electrically connected rotating electric machine and power converter are not cooled by the same refrigerant path. For example, even if one of the multiple rotating electric machines and the power converter connected to it generate heat, these rotating electric machines and power converters are cooled by different refrigerant paths. This allows for the equalization of the required cooling amount across multiple refrigerant paths, and an improvement in the cooling efficiency of the drive system can be expected.

[0007] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0008] [Figure 1] A block diagram of an electric vehicle equipped with the drive unit 20 of the first embodiment is shown. [Figure 2] The circuit diagram of the drive device 20 of the first embodiment is shown. [Figure 3] A cross-sectional view along line III-III in Figure 1 is shown. [Figure 4] A cross-sectional view similar to that shown in Figure 3 is shown for the drive unit 120 of the second embodiment. [Figure 5] A cross-sectional view similar to that shown in Figure 3 is shown for the drive unit 220 of the third embodiment. [Figure 6] A cross-sectional view similar to that shown in Figure 3 is shown for the drive unit 320 of the fourth embodiment. [Modes for carrying out the invention]

[0009] In one embodiment of this technology, the plurality of rotating electric machines may include a first rotating electric machine and a second rotating electric machine. In that case, the plurality of power converters may include a first power converter electrically connected to the first rotating electric machine and a second power converter electrically connected to the second rotating electric machine. Furthermore, the plurality of refrigerant paths may include a first refrigerant path for cooling the first power converter and the second rotating electric machine, and a second refrigerant path for cooling the second power converter and the first rotating electric machine. However, in another embodiment, the plurality of rotating electric machines may consist of three or more rotating electric machines. In that case, the plurality of power converters may consist of three or more power converters, and the plurality of refrigerant paths may consist of three or more refrigerant paths.

[0010] In one embodiment of this technology, the drive unit may further include a first oil cooler capable of cooling the first rotating electric machine, and a first oil pump that supplies oil to the first rotating electric machine via the first oil cooler. In that case, the 2 The refrigerant path may cool the oil in the first oil cooler.

[0011] With this configuration, the oil cools the first rotating electric machine and also allows the first rotating electric machine to rotate smoothly.

[0012] In one embodiment of this technology, the drive unit may further include a second oil cooler capable of cooling the second rotating electric machine, and a second oil pump that supplies oil to the second rotating electric machine via the second oil cooler. In that case, the 1 The refrigerant path may cool the oil in the second oil cooler.

[0013] With this configuration, the oil cools the second rotating electric machine and also allows the second rotating electric machine to rotate smoothly.

[0014] In one embodiment of the present technology, the drive device may further include a casing that houses the first rotating electric machine and the second rotating electric machine. However, in another embodiment, the drive device may include a first casing that houses the first rotating electric machine and a second casing that houses the second rotating electric machine.

[0015] In one embodiment of the present technology, the drive device may further include a first cooler that abuts at least a part of the surface of the first stator of the first rotating electric machine. In that case, the 2 refrigerant path may cool the first rotating electric machine via the first cooler. Here, the "cooler" is, for example, a device including a flow path through which a refrigerant circulates, and is a so-called water jacket.

[0016] With such a configuration, the first cooler can efficiently cool the first rotating electric machine.

[0017] In one embodiment of the present technology, the drive device may further include a second cooler that abuts at least a part of the surface of the second stator of the second rotating electric machine. In that case, the 1 refrigerant path may cool the second rotating electric machine via the second cooler.

[0018] With such a configuration, the second cooler can efficiently cool the second rotating electric machine.

[0019] In one embodiment of the present technology, the drive device may further include a first oil cooler capable of cooling the first rotating electric machine and a first oil pump that supplies oil to the first rotating electric machine via the first oil cooler. In that case, the 2 refrigerant path may further cool the oil in the first oil cooler. Further, the 2 in the refrigerant path, the first cooler and the first oil cooler may be connected in series with each other.

[0020] With this configuration, the first rotating electric machine can be rapidly cooled by the oil and the first cooler.

[0021] In one embodiment of this technology, the drive unit may further include a second oil cooler capable of cooling the second rotating electric machine, and a second oil pump that supplies oil to the second rotating electric machine via the second oil cooler. In that case, the 1 The refrigerant path may further cool the oil in the second oil cooler. 1 In the refrigerant path, the second cooler and the second oil cooler may be connected in series with each other.

[0022] With this configuration, the second rotating electric machine can be rapidly cooled by the oil and the second cooler.

[0023] In one embodiment of this technology, the drive unit may be configured to be mountable on a vehicle. In this case, the drive unit may constitute a charging circuit that supplies a charging current supplied from an external power source to the vehicle's energy storage device via the neutral point of the first rotating electric machine.

[0024] In the above-described drive system, when the charging current is supplied to the vehicle's energy storage device via the neutral point of the first rotating electric motor, the first rotating electric motor and the first power conversion Only the device operates. In this case, the first rotating electric machine and the first power conversion The device overheated, causing the second rotating electric machine and the second power machine to malfunction. conversion The device does not generate heat. Therefore, the second power supply does not generate heat. conversion Cooling the device 2 The refrigerant path can efficiently cool the first rotating electric machine, which generates heat.

[0025] In one embodiment of this technology, the drive device may further include a first oil cooler capable of cooling the first rotating electric machine, a first oil pump that supplies oil to the first rotating electric machine via the first oil cooler, and a control device that controls the first oil pump. In that case, the 2 The refrigerant path may cool the oil in the first oil cooler. Furthermore, the control device may drive the first oil pump for at least a portion of the charging period during which the charging current is supplied to the vehicle's energy storage device via the neutral point of the first rotating electric machine.

[0026] With this configuration, during the charging period, the first oil pump does not generate heat. conversion Cooling the device 2 The oil, cooled by the refrigerant path, can be supplied to the first rotating electric machine, which generates heat.

[0027] In one embodiment of this technology, the drive unit may further include a second oil cooler capable of cooling the second rotating electric machine, and a second oil pump that supplies oil to the second rotating electric machine via the second oil cooler. In that case, the 1 The refrigerant path may cool the oil in the second oil cooler. Furthermore, the control device may stop driving the second oil pump for at least a portion of the charging period.

[0028] With this configuration, during the charging period, the first power that is generating heat... conversion Cooling the device 1 The oil cooled by the refrigerant path is not supplied to the second rotating electric machine, which is not generating heat. This prevents the second oil pump from being driven unnecessarily.

[0029] In one embodiment of this technology, the drive unit may be configured to be mounted on a vehicle. In this case, the first rotating electric machine may transmit power to one of the left and right drive wheels of the vehicle, and the second rotating electric machine may transmit power to the other of the left and right drive wheels of the vehicle. However, in another embodiment, the first and second rotating electric machines may drive both of the left and right drive wheels of the vehicle. Furthermore, the first rotating electric machine may transmit power to the drive wheel located at the front of the vehicle, and the second rotating electric machine may transmit power to the drive wheel located at the rear of the vehicle.

[0030] (First embodiment) Figure 1 shows a block diagram of an electric vehicle 10 equipped with a drive unit 20 of the first embodiment, viewed from above. In this specification, the front of the electric vehicle 10 (i.e., the top of the page in Figure 1) may be simply referred to as "front," and the opposite side may be simply referred to as "rear." Furthermore, the left side of the electric vehicle 10 (i.e., the left side of the page in Figure 1) may be simply referred to as "left," and the opposite side may be simply referred to as "right." Also, the top of the electric vehicle 10 (i.e., the front of the page in Figure 1) may be simply referred to as "up," and the opposite side may be simply referred to as "down."

[0031] The electric vehicle 10 comprises a body 2, a battery pack 3, a pair of left and right front wheels 4R and 4L, a pair of left and right rear wheels 5R and 5L, a charging inlet 6, a drive unit 20, a radiator 60, a pair of left and right cooling fans 61R and 61L, a first refrigerant path 62R, a second refrigerant path 62L, a first radiator pump 64R, and a second radiator pump 64L. The electric vehicle 10 is driven by using the drive unit 20 to drive the pair of left and right front wheels 4R and 4L. In this specification, "electric vehicle" includes, for example, a rechargeable electric vehicle charged by an external power source, a fuel cell vehicle powered by a fuel cell, and a hybrid vehicle that also has an engine. Hereafter, the description "a pair of left and right" may be simply described as "a pair."

[0032] The drive unit 20 comprises a casing 21, a pair of electric motors 30R and 30L, a pair of power transmission mechanisms 50R and 50L, a pair of oil coolers 22R and 22L, a pair of inverters 40R and 40L, and a control device 80.

[0033] The pair of electric motors 30R and 30L are both rotating electric machines. The drive unit 20 drives the pair of front wheels 4R and 4L by supplying power from the battery pack 3 to the pair of electric motors 30R and 30L via a pair of inverters 40R and 40L. In other words, the pair of front wheels 4R and 4L are the drive wheels of the electric vehicle 10. In a modified example, the pair of rear wheels 5R and 5L may be the drive wheels of the electric vehicle 10, or the pair of front wheels 4R and 4L and the pair of rear wheels 5R and 5L may be the drive wheels of the electric vehicle 10.

[0034] The casing 21 houses a pair of electric motors 30R, 30L and a pair of power transmission mechanisms 50R, 50L. For the sake of understanding, Figure 1 shows the shape of the casing 21 with a dashed line and the devices housed in the casing 21, such as the pair of electric motors 30R, 30L, with a solid line. The pair of inverters 40R, 40L comprises a first inverter 40R located on the right and a second inverter 40L located on the left, and is located on the top surface of the casing 21. The pair of power transmission mechanisms 50R, 50L includes a first power transmission mechanism 50R located on the right and a second power transmission mechanism 50L located on the left. The pair of electric motors 30R, 30L includes a first electric motor 30R located on the right and a second electric motor 30L located on the left. The first power transmission mechanism 50R transmits power from the first electric motor 30R to the right drive shaft 14R connected to the right front wheel 4R. The first power transmission mechanism 50R has multiple gears, bearings, etc. The first power transmission mechanism 50R functions as a reduction gear, for example, to reduce the rotational speed of the first electric motor 30R and rotate the right drive shaft 14R. Similarly, the second power transmission mechanism 50L transmits the power of the second electric motor 30L to the left drive shaft 14L connected to the left front wheel 4L. As shown in Figure 1, the right drive shaft 14R and the left drive shaft 14L are separated in the center in the left-right direction of the electric vehicle 10. Therefore, the pair of front wheels 4R and 4L are driven independently by the pair of electric motors 30R and 30L. In a modified example, each drive shaft 14R and 14L may be connected in the center. In that case, two electric motors 30R and 30L may drive the pair of front wheels 4R and 4L.

[0035] The charging inlet 6 is located on the right side of the vehicle body 2. The charging inlet 6 is configured to be connected to an external power source 7 (for example, a charging station) via a power cable 8. When the charging inlet 6 is connected to the external power source 7, the charging power from the external power source 7 is supplied to the battery pack 3.

[0036] A pair of oil coolers 22R and 22L are located at the front of the casing 21. The pair of oil coolers 22R and 22L comprises a first oil cooler 22R located on the right and a second oil cooler 22L located on the left.

[0037] The radiator 60 is located at the front end of the body of the electric vehicle 10. The radiator 60 is a device that performs heat exchange between the refrigerant circulating in each refrigerant path 62R and refrigerant path 62L and the outside air. The refrigerant is a liquid such as antifreeze or water. The radiator 60 cools the refrigerant with air generated by cooling fans 61R and 61L, for example. The first radiator pump 64R ​​circulates the refrigerant to the first refrigerant path 62R. The first refrigerant path 62R includes a first upstream path 66R, a first midstream path 67R, and a first downstream path 68L. Similarly, the second radiator pump 64L circulates the refrigerant to the second refrigerant path 62L. The second refrigerant path 62L includes a second upstream path 66L, a second midstream path 67L, and a second downstream path 68R. The refrigerant paths 62R and 62L merge in the merging path 69. In other words, in this embodiment, a common refrigerant flows through the first refrigerant path 62R and the second refrigerant path 62L. The merging path 69 connects the radiator 60 to the downstream paths 68R and 68L.

[0038] As shown by the dashed arrow in Figure 1, the first radiator pump 64R ​​pumps refrigerant into the first upstream path 66R. This allows the refrigerant to reach the first inverter 40R. Furthermore, the refrigerant is supplied to the second oil cooler 22L via the first midstream path 67R. After passing through the second oil cooler 22L, the refrigerant returns to the radiator 60 via the first downstream path 68L and the merging path 69. Similarly, in the second refrigerant path 62L, the refrigerant pumped into the second upstream path 66L by the second radiator pump 64L flows in the following order: second inverter 40L, second midstream path 67L, first oil cooler 22R, second downstream path 68R, merging path 69, and radiator 60.

[0039] Referring to Figure 2, the electrical circuit of the drive unit 20 will be described. The drive unit 20 includes a pair of electric motors 30R, 30L, a pair of inverters 40R, 40L, and a power supply circuit 11. The power supply circuit 11 is a circuit for supplying DC charging power supplied from an external power source 7 to the battery pack 3. The first electric motor 30R is a three-phase motor comprising a U-phase coil 35U, a V-phase coil 35V, and a W-phase coil 35W. The first inverter 40R comprises a U-phase arm 42U, a V-phase arm 42V, and a W-phase arm 42W. Each phase arm 42U, 42V, and 42W has two switching elements connected in series. The first inverter 40R is a power converter that converts DC power supplied from the battery pack 3 into three-phase AC power suitable for driving the first electric motor 30R by switching the switching elements of each phase arm 42U, 42V, and 42W on and off. One end of the U-phase coil 35U, V-phase coil 35V, and W-phase coil 35W of the first electric motor 30R are connected to each other at the neutral point NP. The other end of the U-phase coil 35U is connected to the midpoint of the two switching elements of the U-phase arm 42U, the other end of the V-phase coil 35V is connected to the midpoint of the two switching elements of the V-phase arm 42V, and the W-phase coil 35W is connected to the midpoint of the two switching elements of the W-phase arm 42W. In this way, the first inverter 40R is electrically connected to the first electric motor 30R.

[0040] Similarly, the second electric motor 30L also comprises a U-phase coil 35U, a V-phase coil 35V, and a W-phase coil 35W, and the second inverter 40L comprises a U-phase arm 42U, a V-phase arm 42V, and a W-phase arm 42W. Each phase arm 42U, 42V, and 42W has two switching elements connected in series. The second inverter 40L is a power conversion device that converts the DC power supplied from the battery pack 3 into three-phase AC power suitable for driving the second electric motor 30L by switching the switching elements of each phase arm 42U, 42V, and 42W on and off. One end of the U-phase coil 35U, the V-phase coil 35V, and the W-phase coil 35W are connected to each other at the neutral point NP. The other end of the U-phase coil 35U is connected to the midpoint of the two switching elements of the U-phase arm 42U. The other end of the V-phase coil 35V is connected to the midpoint of the two switching elements of the V-phase arm 42V. The W-phase coil 35W is connected to the midpoint of the two switching elements of the W-phase arm 42W. In this way, the second inverter 40L is electrically connected to the second electric motor 30L.

[0041] In the power supply circuit 11 of this embodiment, one terminal of the charging inlet 6 is connected to the positive terminal of the battery pack 3 via the neutral point NP of the first electric motor 30R and the first inverter 40R. The power supply circuit 11 supplies charging power supplied from the external power source 7 to the neutral point NP of the first electric motor 30R. The other terminal of the charging inlet 6 is connected to the negative terminal of the battery pack 3 via the first inverter 40R. The power supply circuit 11 supplies charging power to the battery pack 3 via the neutral point NP of the first electric motor 30R. As a result, the first electric motor 30R and the first inverter 40R can function as three boost circuits connected in parallel between the charging inlet 6 and the battery pack 3. This allows the drive unit 20 to boost the output voltage of the external power source 7 using the first electric motor 30R and the first inverter 40R. This enables rapid charging even if the output voltage of the external power source 7 is lower than the voltage of the battery pack 3. Furthermore, one terminal of the charging inlet 6 is directly connected to the positive terminal of the battery pack 3 via switch 13. The power supply circuit 11 can bypass the neutral point NP of the first electric motor 30R to the output voltage of the external power supply 7 by turning on switch 13 when the output voltage of the external power supply 7 is equal to the voltage of the battery pack 3. Although not shown in the figures, the power supply circuit 11 also includes a charging unit that includes a relay, a capacitor, etc. The charging unit is connected to the neutral point NP and the first inverter 40R.

[0042] When the charging inlet 6 is connected to the external power supply 7 and the switch 13 is turned off, the charging power from the external power supply 7 is supplied to the neutral point NP of the first electric motor 30R. Hereinafter, the period during which the charging power is supplied to the battery pack 3 via the supply to the neutral point NP of the first electric motor 30R may be referred to as the "charging period". Throughout the charging period, current flows through the coils 35U, 35V, and 35W of each phase of the first electric motor 30R. As a result, the coils 35U, 35V, and 35W of each phase generate heat, and the temperature of the first electric motor 30R rises. In addition, during the charging period, the switching elements of the phase arms 42U, 42V, and 42W of the first inverter 40R, which is electrically connected to the first electric motor 30R, are turned on and off, causing the temperature of the first inverter 40R to rise. On the other hand, even when the charging inlet 6 is connected to the external power supply 7, no current flows through the coils 35U, 35V, and 35W of each phase of the second electric motor 30L, so the temperature of the second electric motor 30L does not rise. For this reason, the temperature of the second inverter 40L, which is electrically connected to the second electric motor 30L, also does not rise.

[0043] The detailed structure of the drive unit 20 will be described with reference to Figure 3. Figure 3 is a cross-sectional view of the drive unit along line III-III in Figure 1. In addition to the pair of electric motors 30R, 30L, etc. described above, the drive unit 20 further includes a pair of oil pumps 70R, 70L housed in a casing 21, a pair of suction pipes 72R, 72L, and a pair of discharge pipes 74R, 74L. The casing 21 also includes a partition wall 26 that extends downward in the center in the left-right direction. The partition wall 26 is a wall that separates the right space and the left space of the casing 21. However, the partition wall 26 does not reach the bottom surface of the casing 21. The right space and the left space of the casing 21 are in communication at the bottom of the casing 21. The first electric motor 30R and the first power transmission mechanism 50R are located to the right of the partition wall 26. The second electric motor 30L and the second power transmission mechanism 50L are located to the left of the partition wall 26. The drive unit 20 is configured symmetrically with respect to the center of the partition wall 26, i.e., the center line CL1. Therefore, the following description will mainly focus on the configuration of the drive unit 20 located to the right of the center line CL1.

[0044] The first electric motor 30R comprises a motor shaft 33R, a rotor 34R, and a stator 35R. The motor shaft 33R extends horizontally through the rotor 34R and is rotatably held in the casing 21 by a pair of bearings 39R. The motor shaft 33R extends to the left beyond the left end of the rotor 34R and is connected to the gears of the first power transmission mechanism 50R. When the motor shaft 33R rotates due to the rotation of the rotor 34R, the gears of the first power transmission mechanism 50R rotate. Although not shown in the figures, the first power transmission mechanism 50R rotates the right drive shaft 14R (see Figure 1) via multiple gears. That is, the first power transmission mechanism 50R transmits the power of the first electric motor 30R to the right drive shaft 14R. The motor shaft 33R has a hollow structure. Multiple through holes 38R are formed on the side surface of the motor shaft 33R. The multiple through holes 38R connect the internal space of the motor shaft 33R to the internal space of the casing 21. In Figure 1, only the two through holes 38R located at the rightmost end of the multiple through holes 38R are labeled, and the labels for the other through holes 38R are omitted.

[0045] Similarly, the second electric motor 30L comprises a motor shaft 33L, a rotor 34L, and a stator 35L. The motor shaft 33L extends in the left-right direction through the rotor 34L and is rotatably held in the casing 21 by a pair of bearings 39L. Furthermore, the second power transmission mechanism 50L also transmits power from the second electric motor 30L to the left drive shaft 14L via gears connected to the motor shaft 33L of the second electric motor 30L.

[0046] As shown in Figure 3, oil 76 is stored in the lower part of the casing 21. The casing 21 forms a so-called oil reservoir. A pair of oil pumps 70R, 70L comprises a first oil pump 70R located on the right and a second oil pump 70L located on the left. The first oil pump 70R is fixed to the bulkhead 26 from the right. The first oil pump 70R is a pump that supplies oil 76 to the first electric motor 30R. A pair of suction pipes 72R, 72L comprises a first suction pipe 72R located on the right and a second suction pipe 72L located on the left. The first suction pipe 72R extends upward from the oil reservoir, bends to the left, and connects to the suction port of the first oil pump 70R. A pair of discharge pipes 74R, 74L comprises a first discharge pipe 74R located on the right and a second discharge pipe 74L located on the left. The first discharge pipe 74R extends upward from the discharge port of the first oil pump 70R. The first discharge pipe 74R bends forward (i.e., towards the back of the paper in Figure 3) and penetrates the front side wall of the casing 21, extends upward along the outer surface of the front side wall, and passes through the first oil cooler 22R located in the front side wall. Furthermore, after passing through the first oil cooler 22R, the first discharge pipe 74R penetrates the front side wall of the casing 21 again and enters the casing 21, connecting to the left end of the motor shaft 33R of the first electric motor 30R. The first oil pump 70R supplies oil 76 to the motor shaft 33R of the first electric motor 30R via the first suction pipe 72R and the first discharge pipe 74R. The oil 76 supplied to the motor shaft 33R moves from the internal space of the motor shaft 33R to the internal space of the casing 21 through a plurality of through holes 38R. The oil 76 flows through the internal space of the casing 21 and is stored again at the bottom of the casing 21. In this way, the first oil pump 70R circulates the oil 76. The oil 76 cools the first electric motor 30R and makes the rotation of the first electric motor 30R smooth. Furthermore, the oil 76 also lubricates the gears of the first power transmission mechanism 50R. This allows the first power transmission mechanism 50R to rotate smoothly. In Figures 3 to 6, the flow of oil 76 is shown by solid arrows, and the flow of refrigerant is shown by dashed arrows.

[0047] Similarly, the second oil pump 70L is fixed to the bulkhead 26 from the left. The second oil pump 70L is a pump that supplies oil 76 to the second electric motor 30L via the second suction pipe 72L and the second discharge pipe 74L. The second discharge pipe 74L passes through the second oil cooler 22L and is connected to the right end of the motor shaft 33L of the second electric motor 30L. This supplies oil 76 to the second electric motor 30L. As shown by the solid arrow in Figure 3, the second oil pump 70L circulates the oil 76. The oil 76 cools the second electric motor 30L and smooths the rotation of the second electric motor 30L and the second power transmission mechanism 50L. Thus, in this embodiment, the first electric motor 30R and the second electric motor 30L are cooled by an oil-cooled cooling system.

[0048] The control device 80 is positioned above the first inverter 40R. The control device 80 has a CPU and memory and is a computer that controls a pair of cooling fans 61R, 61L, a pair of radiator pumps 64R, 64L, and a pair of oil pumps 70R, 70L. The control device 80 controls each cooling fan 61R, 61L and each pump 64R, 64L, 70R, 70L based on instructions from a higher-level vehicle control unit (not shown). In modified examples, the control device 80 may be positioned on any of the right, left, front, or rear sides of the first inverter 40R. Furthermore, the control device 80 is not limited to one, and may be positioned on both the left and right sides of the first inverter 40R, for example.

[0049] As previously mentioned, the first discharge pipe 74R passes through the first oil cooler 22R and is connected to the motor shaft 33R of the first electric motor 30R. Furthermore, as explained with reference to Figure 1, the refrigerant cooled by the radiator 60 circulates through the second refrigerant path 62L in the first oil cooler 22R. Therefore, the refrigerant in the first oil cooler 22R cools the oil 76 in the first discharge pipe 74R. The oil 76 absorbs heat from the first electric motor 30R. That is, the second refrigerant path 62L cools the first electric motor 30R of the pair of electric motors 30R, 30L via the oil 76.

[0050] Similarly, the second discharge pipe 74L passes through the second oil cooler 22L and connects to the motor shaft 33L of the second electric motor 30L. Furthermore, as explained with reference to Figure 1, the refrigerant cooled by the radiator 60 circulates in the second oil cooler 22L via the first refrigerant path 62R. Thus, the refrigerant in the second oil cooler 22L cools the oil 76 in the second discharge pipe 74L. The oil 76 absorbs heat from the second electric motor 30L. That is, the first refrigerant path 62R cools the second electric motor 30L of the pair of electric motors 30R, 30L via the oil 76.

[0051] Furthermore, the first inverter 40R is equipped with a first inverter cooler 41R. One end of the first inverter cooler 41R is connected to the first upstream path 66R of the first refrigerant path 62R, and the other end of the first inverter cooler 41R is connected to the first midstream path 67R. The first midstream path 67R is connected to the first downstream path 68L (see Figure 1) via the second oil cooler 22L. The first inverter cooler 41R has a flow path for circulating refrigerant and cools the first inverter 40R by circulating the refrigerant. That is, the first refrigerant path 62R cools the first inverter 40R of the pair of inverters 40R, 40L via the refrigerant.

[0052] Similarly, the second inverter 40L is equipped with a second inverter cooler 41L. One end of the second inverter cooler 41L is connected to the second upstream path 66L of the second refrigerant path 62L, and the other end of the second inverter cooler 41L is connected to the second midstream path 67L. The second midstream path 67L is connected to the second downstream path 68R (see Figure 1) via the first oil cooler 22R. The second inverter cooler 41L has a flow path for circulating refrigerant and cools the second inverter 40L by circulating the refrigerant. That is, the second refrigerant path 62L cools the second inverter 40L of the pair of inverters 40R, 40L via the refrigerant.

[0053] As shown in Figure 3, the first midstream path 67R of the first refrigerant path 62R connects the first inverter cooler 41R of the first inverter 40R, located to the right of the center line CL1, to the second oil cooler 22L, located to the left of the center line CL1. Similarly, the second midstream path 67L of the second refrigerant path 62L connects the second inverter cooler 41L of the second inverter 40L, located to the left of the center line CL1, to the first oil cooler 22R, located to the right of the center line CL1. Therefore, the first midstream path 67R extends from the right of the center line CL1, crossing over the center line CL1 to the left, and the second midstream path 67L extends from the left of the center line CL1, crossing over the center line CL1 to the right. As a result, when viewed from the rear of the vehicle, the respective midstream paths 67R and 67L intersect each other.

[0054] As mentioned earlier, the first electric motor 30R is electrically connected to the first inverter 40R. Furthermore, the first electric motor 30R is cooled by the same second refrigerant path 62L as the second inverter 40L. In other words, the first electric motor 30R is electrically connected to a first inverter 40R that is different from the second inverter 40L, which is cooled by the same refrigerant path 62L as itself.

[0055] Similarly, the second electric motor 30L is electrically connected to the second inverter 40L. Furthermore, the second electric motor 30L is cooled by the same first refrigerant path 62R as the first inverter 40R. In other words, the second electric motor 30L is electrically connected to a second inverter 40L that is different from the first inverter 40R, which is cooled by the same refrigerant path 62R as itself.

[0056] (Effects of this embodiment) The control device 80 drives a pair of cooling fans 61R, 61L, a second radiator pump 64L, and a first oil pump 70R in response to the charging inlet 6 being connected to an external power supply 7 via a power cable 8 and the switch 13 being turned off. As a result, the refrigerant cooled by the pair of cooling fans 61R, 61L is supplied to the first oil cooler 22R via a second refrigerant path 62L during the charging period. Furthermore, the oil 76 cooled by the refrigerant in the first oil cooler 22R is supplied to the first electric motor 30R. The second refrigerant path 62L supplies refrigerant to the first oil cooler 22R via a second inverter cooler 41L of the second inverter 40L. The refrigerant that has passed through the second inverter 40L, which does not generate heat, is supplied to the first oil cooler 22R, and the oil 76 cooled by this refrigerant cools the first electric motor 30R that is driven during the charging period. In other words, in the drive unit 20 of this embodiment, the electrically connected first electric motor 30R and the first inverter 40R are not cooled by the same second refrigerant path 62L. This makes it possible to equalize the amount of cooling required for each refrigerant path 62R, 62L, thereby improving the cooling efficiency of the drive unit 20.

[0057] Furthermore, the control device 80 drives the first radiator pump 64R ​​and stops driving the second oil pump 70L during the charging period. This allows the first inverter 40R, which operates during the charging period, to be cooled by the refrigerant circulating in the first refrigerant path 62R. Also, oil 76 is not supplied to the second electric motor 30L during the charging period. As mentioned earlier, since the second electric motor 30L is not driven during the charging period, the temperature of the second electric motor 30L does not rise. Thus, in the drive device 20 of this embodiment, by stopping the driving of the second oil pump 70L during the charging period, it is possible to prevent the second oil pump 70L from being unnecessarily driven to supply oil 76 to the second electric motor 30L, which is not being driven.

[0058] (Second example) Referring to Figure 4, the drive unit 120 of the second embodiment will be described. In addition to the configuration of the drive unit 20 of the first embodiment described above, the drive unit 120 of this embodiment further includes a pair of coolers 120R and 120L. The pair of coolers 120R and 120L includes a first cooler 120R that cools the first electric motor 30R and a second cooler 120L that cools the second electric motor 30L. That is, in this embodiment, the first electric motor 30R and the second electric motor 30L are cooled by an oil-water cooling system that combines oil cooling and water cooling. The first cooler 120R is in contact with the outer surface of the stator 35R of the first electric motor 30R. The first cooler 120R cools the stator 35R by passing a refrigerant through it. The first cooler 120R is located in the second refrigerant path 62L (see Figure 1). 1 Connection pipe 167 R It is connected to the first oil cooler 122R via [a certain route]. The refrigerant that has passed through the first cooler 120R returns to the radiator 60 via the second downstream route 168R and the merging route 69 (see Figure 1).

[0059] Similarly, the second cooler 120L is in contact with the outer surface of the stator 35L of the second electric motor 30L. The second cooler 120L is the first coolant path 62R (see Figure 1) 2 Connection pipe 167 LIt is connected to the second oil cooler 122L via this route. The refrigerant that has passed through the second cooler 120L returns to the radiator 60 via the first downstream path 168L and the confluence path 69 (see Figure 1).

[0060] In the drive unit 120 of this embodiment, the first electric motor 30R is cooled by a refrigerant in addition to the oil 76. This allows the first electric motor 30R to be cooled rapidly by the oil 76 and the refrigerant.

[0061] (Third embodiment) Referring to Figure 5, the drive unit 220 of the third embodiment will be described. Compared with the drive unit 120 of the second embodiment described above, the drive unit 220 of this embodiment does not have a pair of oil coolers 22R, 22L and a pair of oil pumps 70R, 70L. That is, in this embodiment, the first electric motor 30R and the second electric motor 30L are cooled by a water-cooled cooling system. For this reason, in the drive unit 220 of this embodiment, the first inverter cooler 41R of the first inverter 40R and the second cooler 120L are directly connected via the first midstream path 267R, and the second inverter cooler 41L of the second inverter 40L and the first cooler 120R are directly connected via the second midstream path 267L. Similar to the second embodiment, the refrigerant that has passed through the first cooler 120R returns to the radiator 60 via the first downstream path 268R and the merging path 69 (see Figure 1), and the refrigerant that has passed through the second cooler 120L returns to the radiator 60 via the second downstream path 268L and the merging path 69 (see Figure 1).

[0062] Furthermore, in the drive unit 220 of this embodiment, oil 76 (see Figure 3) is not stored in the lower part of the casing. For this reason, the drive unit 220 includes a first casing 221R that houses the first electric motor 30R and a second casing 221L that houses the second electric motor 30L. The casings 221R and 221L are arranged in the left-right direction.

[0063] (Fourth embodiment) Referring to Figure 6, the drive unit 320 of the third embodiment will be described. The drive unit 320 of this embodiment has basically the same configuration as the drive unit 20 of the first embodiment, but the arrangement of each device is different. In this embodiment, the electric motors 330R and 330L are arranged in the center of the casing 321 in the left-right direction. The motor shaft 333R of the first electric motor 330R extends to the right beyond the right end of the rotor 34R. The motor shaft 333R is connected to the first power transmission mechanism 350R located to the right of the first electric motor 330R. Similarly, the motor shaft 333L of the second electric motor 330L extends to the left beyond the left end of the rotor 34L. The motor shaft 333L is connected to the second power transmission mechanism 350L located to the left of the second electric motor 330L.

[0064] The first oil pump 370R is located on the right inner wall of the casing 321, and the second oil pump 370L is located on the left inner wall of the casing 321. The first oil cooler 322R is located on the right outer wall of the casing 321, and the second oil cooler 322L is located on the left outer wall of the casing 321. The first oil cooler 322R houses a portion of the first discharge pipe 374R, which extends upward along the right outer wall of the casing 321. The first oil pump 370R draws up oil 76 through the first suction pipe 372R and supplies the oil 76 to the motor shaft 333R of the first electric motor 330R via the first discharge pipe 374R. This supplies the first electric motor 330R with oil 76 cooled by the refrigerant in the first oil cooler 322R. Similarly, the second oil cooler 322L houses a portion of the second discharge pipe 374L that extends upward along the left outer wall of the casing 321. The second oil pump 370L draws up oil 76 through the second suction pipe 372L and supplies the oil 76 to the motor shaft 333L of the second electric motor 30L via the second discharge pipe 374L. This supplies the oil 76, cooled by the refrigerant in the second oil cooler 322L, to the second electric motor 330L.

[0065] As shown in Figure 6, in this embodiment as well, the first inverter cooler 41R of the first inverter 40R, located to the right of the center line CL1, and the second oil cooler 322L, located to the left, are connected by the first midstream path 367R. Furthermore, the second inverter cooler 41L of the second inverter 40L, located to the left of the center line CL1, and the first oil cooler 322R, located to the right, are connected by the second midstream path 367L. Therefore, when viewed from the rear of the vehicle, the midstream paths 367R and 367L intersect each other.

[0066] The specific examples of the technology disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples illustrated above. Modifications of the above embodiments are listed below.

[0067] (Modification 1) In the embodiment described above, the drive unit 20 comprises two electric motors 30R, 30L, two inverters 40R, 40L, and two refrigerant paths 62R, 62L. However, the number of electric motors, inverters, and refrigerant paths is not limited to two. The drive unit 20 may, for example, comprise three electric motors, three inverters, and three refrigerant paths. In this case, the first electric motor and the first inverter may be electrically connected, the second electric motor and the second inverter may be electrically connected, and the third electric motor and the third inverter may be electrically connected. Furthermore, the first refrigerant path may cool the first inverter and the second electric motor, the second refrigerant path may cool the second inverter and the third electric motor, and the third refrigerant path may cool the third inverter and the first electric motor. In another modified example, the drive unit 20 may include two electric motors for driving a pair of front wheels 4R and 4L, two electric motors for driving a pair of rear wheels 5R and 5L, and four inverters electrically connected to each motor. In yet another modified example, the first electric motors may drive a pair of front wheels 4R and 4L, and the second electric motors may drive a pair of rear wheels 5R and 5L. In this case, the first and second electric motors may be arranged in the left-right direction or in the front-rear direction.

[0068] (Modification 2) The drive unit 20 of the first embodiment does not need to include a power supply circuit 11. In this modification, the drive unit 20 does not need to supply charging power to the battery pack 3 via the neutral point NP of the first electric motor 30R. In this modification, the control device 80 may, for example, drive a pair of cooling fans 61R, 61L, a second radiator pump 64L, and a first oil pump 70R when the rotational speed of the first electric motor 30R exceeds a predetermined value. For example, when the electric vehicle 10 is traveling on a road that curves to the left, the rotational speed of the first electric motor 30R that drives the right front wheel 4R may exceed a predetermined value. In this modification, the electric motor with a higher rotational speed can be efficiently cooled using a refrigerant that cools an inverter electrically connected to the other electric motor with a lower rotational speed.

[0069] (Modification 3) The drive unit 20 of the first embodiment is equipped with two oil pumps 70R and 70L, but in this modification, it may be equipped with one oil pump. In this modification, one oil pump may supply oil 76 to two electric motors 30R and 30L. In this modification, the one oil pump is an example of the "first oil pump" and the "second oil pump".

[0070] (Modification 4) The control device 80 does not have to stop the second oil pump 70L during the charging period. In this modification, the control device 80 may drive the pair of cooling fans 61R, 61L, the pair of radiator pumps 64R, 64L, and the pair of oil pumps 70R, 70L throughout the charging period. In another modification, the control device 80 may drive the pair of cooling fans 61R, 61L, the second radiator pump 64L, and the first oil pump 70R during the charging period if the temperature of the first electric motor 30R exceeds a predetermined temperature.

[0071] The technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness in itself. [Explanation of Symbols]

[0072] 2: Body, 3: Battery pack, 4L: Left front wheel, 4R: Right front wheel, 5L, 5R: Rear wheels, 6: Charging inlet, 7: External power supply, 8: Power cable, 10: Electric vehicle, 11: Power supply circuit, 13: Switch, 14L: Left drive shaft, 14R: Right drive shaft, 20, 120, 220, 320: Drive unit, 21, 321: Casing, 22L, 122L, 322L: Second oil cooler, 22R, 122R, 322R: First oil cooler, 26: Bulkhead, 30L, 330L: Second electric motor 30R, 330R: First electric motor, 33L, 33R, 333L, 333R: Motor shaft, 34L, 34R: Rotor, 35L, 35R: Stator, 35U: U-phase coil, 35V: V-phase coil, 35W: W-phase coil, 38R: Through hole, 39L, 39R: Bearing, 40L: Second inverter, 40R: First inverter, 41L: Second inverter cooler, 41R: First inverter cooler, 42U: U-phase arm, 42V: V-phase arm, 42W: W-phase arm, 50L, 35 0L: Second power transmission mechanism, 50R, 350R: First power transmission mechanism, 60: Radiator, 61L: Cooling fan, 61R: Cooling fan, 62L: Second refrigerant path, 62R: First refrigerant path, 64L: Second radiator pump, 64R: First radiator pump, 66L: Second upstream path, 66R: First upstream path, 67L, 267L, 367L: Second midstream path, 67R, 267R, 367R: First midstream path, 68L, 168L, 268L: First downstream path, 68R, 168R, 268R: Second downstream path Flow path, 69: Confluence path, 70L, 370L: Second oil pump, 70R, 370R: First oil pump, 72L, 372L: Second suction piping, 72R, 372R: First suction piping, 74L, 374L: Second discharge piping, 74R, 374R: First discharge piping, 76: Oil, 80: Control device, 120: Second cooler, 120R: First cooler, 167L: Second connecting piping, 167R: First connecting piping, 221L: Second casing, 221R: First casing, CL1: Centerline, NP: Neutral point

Claims

1. Multiple rotating electric machines, Multiple power converters, Multiple refrigerant paths are provided in parallel with each other and for cooling the multiple rotating electric machines and the multiple power conversion devices, Equipped with, Each of the aforementioned power converters is electrically connected to at least one of the aforementioned rotating electric machines. Each of the plurality of refrigerant paths is configured to cool at least one of the plurality of power converters and at least one of the plurality of rotating electric machines. Each of the aforementioned rotating electric machines is electrically connected to a power converter different from the at least one power converter that is cooled by the same refrigerant path as itself. Drive unit.

2. The aforementioned multiple rotating electric machines are The first rotating electric machine and, The second rotating electric machine and, Includes, The plurality of power conversion devices, A first power converter electrically connected to the first rotating electric machine, A second power converter electrically connected to the second rotating electric machine, Includes, The aforementioned multiple refrigerant paths are A first refrigerant path for cooling the first power converter and the second rotating electric machine, A second refrigerant path for cooling the second power converter and the first rotating electric machine, including, The drive device according to claim 1.

3. The aforementioned drive device further, A first oil cooler capable of cooling the first rotating electric machine, A first oil pump that supplies oil to the first rotating electric machine via the first oil cooler, Equipped with, The second refrigerant path cools the oil in the first oil cooler. The drive device according to claim 2.

4. The aforementioned drive device further, A second oil cooler capable of cooling the second rotating electric machine, A second oil pump supplies oil to the second rotating electric machine via the second oil cooler, Equipped with, The first refrigerant path cools the oil in the second oil cooler. The drive device according to claim 3.

5. The drive device further comprises a casing for housing the first rotating electric machine and the second rotating electric machine. The drive device according to claim 2.

6. The drive device further includes a first cooler that contacts at least a portion of the surface of the first stator of the first rotating electric machine, The second refrigerant path cools the first rotating electric machine via the first cooler. The drive device according to claim 2.

7. The drive device further includes a second cooler that contacts at least a portion of the surface of the second stator of the second rotating electric machine, The first refrigerant path cools the second rotating electric machine via the second cooler. The drive device according to claim 6.

8. The aforementioned drive device further, A first oil cooler capable of cooling the first rotating electric machine, A first oil pump that supplies oil to the first rotating electric machine via the first oil cooler, Equipped with, The second refrigerant path further cools the oil in the first oil cooler, In the second refrigerant path, the first cooler and the first oil cooler are connected in series with each other. The drive device according to claim 6.

9. The aforementioned drive device further, A second oil cooler capable of cooling the second rotating electric machine, A second oil pump supplies oil to the second rotating electric machine via the second oil cooler, Equipped with, The first refrigerant path further cools the oil in the second oil cooler, In the first refrigerant path, the second cooler and the second oil cooler are connected in series with each other. The drive device according to claim 7.

10. The drive device is It is configured to be mounted on a vehicle. A charging circuit is configured to supply a charging current, which is supplied from an external power source of the vehicle, to the vehicle's energy storage device via the neutral point of the first rotating electric machine. The drive device according to claim 2.

11. The aforementioned drive device further, A first oil cooler capable of cooling the first rotating electric machine, A first oil pump that supplies oil to the first rotating electric machine via the first oil cooler, A control device for controlling the first oil pump, Equipped with, The second refrigerant path cools the oil in the first oil cooler. The control device drives the first oil pump during at least a portion of the charging period in which the charging current is supplied to the vehicle's energy storage device via the neutral point of the first rotating electric machine. The drive device according to claim 10.

12. The aforementioned drive device further, A second oil cooler capable of cooling the second rotating electric machine, A second oil pump supplies oil to the second rotating electric machine via the second oil cooler, Equipped with, The first refrigerant path cools the oil in the second oil cooler. The control device stops the operation of the second oil pump for at least a portion of the charging period. The drive device according to claim 11.

13. The aforementioned drive unit is configured to be mounted on a vehicle, The first rotating electric machine transmits power to one of the left and right drive wheels of the vehicle. The second rotating electric machine transmits power to the other of the left and right drive wheels of the vehicle. The drive device according to claim 2.

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