Drive apparatus

Abstract

The driving device (20; 120; 220; 320) has a plurality of rotary electric machines (30R, 30L; 330R, 330L) and a plurality of power converters (40R, 40L), and a plurality of refrigerant paths (62R, 62L) for cooling the plurality of rotary electric machines (30R, 30L; 330R, 330L) and the plurality of power converters (40R, 40L), which are arranged in parallel with each other. Each of the plurality of power converters (40R, 40L) is electrically connected to at least one of the plurality of rotary electric machines (30R, 30L; 330R, 330L). Each of the plurality of refrigerant paths (62R, 62L) is configured to cool at least one of the plurality of power converters (40R, 40L) and at least one of the plurality of rotary electric machines (30R, 30L; 330R, 330L). Each of the plurality of rotary electric machines (30R, 30L; 330R, 330L) is electrically connected to a power converter (40R, 40L) different from the power converter (40R, 40L) that is cooled by the same refrigerant path (62R, 62L).

Description

Technology Field

[0001] The technology disclosed in this specification relates to a driving device. Background Technology

[0002] Japanese Patent Publication No. 2018-121429 discloses a vehicle having a plurality of rotary electric machines and a plurality of power converters. In the vehicle, the rotary electric machines and power converters, which are electrically connected to each other, are cooled by the same refrigerant path. The problem to be solved

[0003] Typically, the same current flows through a rotating electric machine and a power converter electrically connected thereto. Consequently, when one of a plurality of rotating electric machines operates under high load, both the rotating electric machine and the power converter electrically connected thereto generate significant heat. In this case, according to the technology of Japanese Patent Publication No. 2018-121429, the rotating electric machine and the power converter are cooled by the same refrigerant path. As a result, a large difference in the required amount of cooling occurs between the said refrigerant path and other refrigerant paths, leading to a decrease in cooling efficiency. This specification provides a technology capable of improving cooling efficiency in a driving device. means of solving the problem

[0004] A driving device according to a first aspect of the present disclosure comprises a plurality of rotary electric machines, a plurality of power converters, and a plurality of refrigerant paths arranged in parallel with each other and configured to cool the plurality of rotary 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 rotary 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 rotary electric machines. Each of the plurality of rotary electric machines is electrically connected to a power converter other than the at least one power converter that is cooled by the same refrigerant path.

[0005] In the aforementioned drive device, electrically connected rotary electric machines and power converters are not cooled by the same refrigerant path. For example, even if one of a plurality of rotary electric machines and a power converter connected to that rotary electric machine generate heat, the rotary electric machine and the power converter are cooled by different refrigerant paths. By doing so, it is possible to equalize the required cooling amount for the plurality of refrigerant paths, and an improvement in the cooling efficiency of the drive device can be expected.

[0006] Details of the technology disclosed in this specification and further improvements are described in the following “Specific details for carrying out the invention”. Brief explanation of the drawing

[0007] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, where similar numbers in the drawings indicate similar elements. FIG. 1 shows a block diagram of an electric vehicle equipped with a driving device (20) of the first embodiment. Figure 2 shows a circuit diagram of a driving device (20) of the first embodiment. Figure 3 shows a cross-sectional view along line III-III of Figure 1. FIG. 4 shows a cross-sectional view similar to FIG. 3 of a driving device (120) of the second embodiment. FIG. 5 shows a cross-sectional view similar to FIG. 3 of a driving device (220) of the third embodiment. FIG. 6 shows a cross-sectional view similar to FIG. 3 of a driving device (320) of the fourth embodiment. Specific details for implementing the invention

[0008] In a driving device according to a first aspect of the present disclosure, the plurality of rotary electric machines may include a first rotary electric machine and a second rotary electric machine. The plurality of power converters may include a first power converter electrically connected to the first rotary electric machine and a second power converter electrically connected to the second rotary electric machine. Additionally, the plurality of refrigerant paths may include a first refrigerant path configured to cool the first power converter and the second rotary electric machine, and a second refrigerant path configured to cool the second power converter and the first rotary electric machine. However, in another embodiment, the plurality of rotary electric machines may comprise three or more rotary electric machines. In that case, the plurality of power converters may comprise three or more power converters, and the plurality of refrigerant paths may comprise three or more refrigerant paths.

[0009] A driving device according to the first embodiment of the present disclosure may also comprise a first oil cooler configured to cool the first rotating electric machine and a first oil pump configured to supply oil to the first rotating electric machine through the first oil cooler. The second refrigerant path may be configured to cool the oil in the first oil cooler.

[0010] According to this configuration, the first rotary electric machine can be cooled by oil, and the rotation of the first rotary electric machine can be made smooth.

[0011] A driving device according to the first embodiment of the present disclosure may also comprise a second oil cooler configured to cool the second rotating electric machine and a second oil pump configured to supply oil to the second rotating electric machine through the second oil cooler. The first refrigerant path may be configured to cool the oil in the second oil cooler.

[0012] According to this configuration, the second rotating electric machine can be cooled by oil, and the rotation of the second rotating electric machine can be made smooth.

[0013] A driving device according to the first aspect of the present disclosure may also have a casing that accommodates the first rotary electric machine and the second rotary electric machine. However, in other embodiments, the driving device may have a first casing that accommodates the first rotary electric machine and a second casing that accommodates the second rotary electric machine.

[0014] A driving device according to the first embodiment of the present disclosure may also have a first cooler that contacts at least a portion of the surface of the first stator of the first rotary electric machine. The second refrigerant path may be configured to cool the first rotary electric machine through the first cooler. Here, the “cooler” is, for example, a device including a flow path for circulating refrigerant, and is a so-called water jacket.

[0015] According to this configuration, the first rotating electric machine can be efficiently cooled by the first cooler.

[0016] A driving device according to the first embodiment of the present disclosure may also have a second cooler that contacts at least a portion of the surface of the second stator of the second rotary electric machine. The first refrigerant path may be configured to cool the second rotary electric machine through the second cooler.

[0017] With this configuration, the second rotating electric machine can be efficiently cooled by the second cooler.

[0018] A driving device according to the first embodiment of the present disclosure may also comprise a first oil cooler configured to cool the first rotating electric machine and a first oil pump configured to supply oil to the first rotating electric machine through the first oil cooler. The second refrigerant path may also be configured to cool the oil within the first oil cooler. Furthermore, in the second refrigerant path, the first cooler and the first oil cooler may be connected in series with each other.

[0019] According to this configuration, the first rotary electric machine can be rapidly cooled by oil and the first cooler.

[0020] A driving device according to the first embodiment of the present disclosure may also comprise a second oil cooler configured to cool the second rotating electric machine and a second oil pump configured to supply oil to the second rotating electric machine through the second oil cooler. The first refrigerant path may also be configured to cool the oil within the second oil cooler. Furthermore, in the first refrigerant path, the second cooler and the second oil cooler may be connected in series with each other.

[0021] According to this configuration, the second rotary electric machine can be rapidly cooled by oil and the second cooler.

[0022] In a driving device according to a first aspect of the present disclosure, the driving device may be configured to be mounted on a vehicle. The driving device may comprise a charging circuit that supplies a charging current supplied from an external power source of the vehicle to a battery storage device of the vehicle through the neutral point of the first rotary electric machine.

[0023] In the drive device described above, when a charging current is supplied to the vehicle's battery storage device through the neutral point of the first rotary electric machine, only the first rotary electric machine and the first power device operate. In this case, the first rotary electric machine and the first power device generate heat, while the second rotary electric machine and the second power device do not generate heat. Therefore, the first refrigerant path that cools the second power device that does not generate heat can efficiently cool the first rotary electric machine that generates heat.

[0024] A driving device according to a first embodiment of the present disclosure may also comprise a first oil cooler configured to cool the first rotating electric machine, a first oil pump configured to supply oil to the first rotating electric machine through the first oil cooler, and a control device configured to control the first oil pump. The second refrigerant path may be configured to cool the oil in the first oil cooler. Additionally, the control device may drive the first oil pump during at least a portion of the charging period in which the charging current is supplied to the battery storage device of the vehicle through the neutral point of the first rotating electric machine.

[0025] According to this configuration, during the charging period, the first oil pump can supply oil cooled by the first refrigerant path, which cools the second power device that does not generate heat, to the first rotating electric machine that generates heat.

[0026] A driving device according to a first embodiment of the present disclosure may also comprise a second oil cooler configured to cool the second rotating electric machine and a second oil pump configured to supply oil to the second rotating electric machine through the second oil cooler. The first refrigerant path may be configured to cool the oil in the second oil cooler. Additionally, the control device may stop the operation of the second oil pump during at least a portion of the charging period.

[0027] According to this configuration, during the charging period, oil cooled by the second refrigerant path that cools the first power device generating heat is not supplied to the second rotary electric machine that is not generating heat. This prevents the second oil pump from being driven unnecessarily.

[0028] In a drive device according to a first embodiment of the present disclosure, the drive device may be configured to be mounted on a vehicle. The first rotary electric machine may be configured to transmit power to the first drive wheel of a pair of left and right drive wheels of the vehicle, and the second rotary electric machine may be configured to transmit power to the second drive wheel of a pair of left and right drive wheels of the vehicle. However, in other embodiments, the first rotary electric machine and the second rotary electric machine may drive both sides of a pair of left and right drive wheels of the vehicle. Additionally, the first rotary electric machine may transmit power to a drive wheel located on the front side of the vehicle, and the second rotary electric machine may transmit power to a drive wheel located on the rear side of the vehicle.

[0029] (1st embodiment)

[0030] FIG. 1 is a block diagram showing an electric vehicle (10) having a driving device (20) of a first embodiment, viewed from above. In this specification, the front of the electric vehicle (10) (i.e., the upper side of the ground in FIG. 1) may simply be labeled "front," and the opposite side may simply be labeled "rear." Additionally, the left side of the electric vehicle (10) (i.e., the left side of the ground in FIG. 1) may simply be labeled "left," and the opposite side may simply be labeled "right." Additionally, the upper side of the electric vehicle (10) (i.e., the front direction of the ground in FIG. 1) may simply be labeled "up," and the opposite side may simply be labeled "down."

[0031] The electric vehicle (10) comprises a vehicle body (2), a battery pack (3), a pair of left and right front wheels (4R, 4L), a pair of left and right rear wheels (5R, 5L), a charging inlet (6), a drive unit (20), a radiator (60), a pair of left and right cooling fans (61R, 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) drives by driving the pair of left and right front wheels (4R, 4L) using the drive unit (20). Furthermore, the "electric vehicle" in this specification includes, for example, a rechargeable electric vehicle that is charged by an external power source, a fuel cell vehicle that uses a fuel cell as a power source, and a hybrid vehicle that combines an engine. In the following, the description "left and right pair" may be written simply as "pair."

[0032] The driving device (20) is equipped with a casing (21), a pair of electric motors (30R, 30L), a pair of power transmission mechanisms (50R, 50L), a pair of oil coolers (22R, 22L), a pair of inverters (40R, 40L), and a control device (80).

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

[0034] The casing (21) accommodates a pair of electric motors (30R, 30L) and a pair of power transmission mechanisms (50R, 50L). For better understanding, in FIG. 1, the shape of the casing (21) is shown with dashed lines, and devices such as a pair of electric motors (30R, 30L) accommodated in the casing (21) are shown with solid lines. A pair of inverters (40R, 40L) is provided with a first inverter (40R) located on the right side and a second inverter (40L) located on the left side, and is positioned on the upper surface of the casing (21). A pair of power transmission mechanisms (50R, 50L) includes a first power transmission mechanism (50R) located on the right side and a second power transmission mechanism (50L) located on the left side. A 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 the power of the first electric motor (30R) to a right drive shaft (14R) connected to the right front wheel (4R). The first power transmission mechanism (50R) has a plurality of gears, bearings, etc. The first power transmission mechanism (50R) functions as a reduction gear that, for example, reduces the rotational speed of the first electric motor (30R) to rotate the right drive shaft (14R). Likewise, the second power transmission mechanism (50L) transmits the power of the second electric motor (30L) to a left drive shaft (14L) connected to the left front wheel (4L). As shown in FIG. 1, the right drive shaft (14R) and the left drive shaft (14L) are separated at the center of the left and right directions of the electric vehicle (10). Therefore, a pair of front wheels (4R, 4L) are driven independently by a pair of electric motors (30R, 30L). In a modified example, each drive shaft (14R, 14L) may be connected at the center. In that case, two electric motors (30R, 30L) may drive a pair of front wheels (4R, 4L).

[0035] The charging inlet (6) is positioned on the right side of the vehicle body (2). The charging inlet (6) is configured to be connected to an external power source (7) (e.g., a charging stand) 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, 22L) are positioned on the front surface of the casing (21). The pair of oil coolers (22R, 22L) includes a first oil cooler (22R) located on the right side and a second oil cooler (22L) located on the left side.

[0037] A radiator (60) is positioned at the front end of the vehicle body of the electric vehicle (10). The radiator (60) is a device that performs heat exchange between the refrigerant circulating through each refrigerant path (62R) and refrigerant path (62L) and the outside air. The refrigerant is a liquid, for example, antifreeze or water. The radiator (60) cools the refrigerant by wind generated by, for example, a cooling fan (61R, 61L). A first radiator pump (64R) circulates the refrigerant to the first refrigerant path (62R). The first refrigerant path (62R) is provided with a first upstream path (66R), a first midstream path (67R), and a first downstream path (68L). Likewise, a second radiator pump (64L) circulates the refrigerant to the second refrigerant path (62L). The second refrigerant path (62L) is provided with a second upstream path (66L), a second midstream path (67L), and a second downstream path (68R). Each refrigerant path (62R, 62L) joins in a joining path (69). That is, in this embodiment, a common refrigerant flows in the first refrigerant path (62R) and the second refrigerant path (62L). The joining path (69) connects the radiator (60) with each downstream path (68R, 68L).

[0038] As indicated by the dashed arrow in FIG. 1, the first radiator pump (64R) pumps the refrigerant to the first upstream path (66R). By doing so, the refrigerant reaches the first inverter (40R). Additionally, the refrigerant is supplied to the second oil cooler (22L) through the first midstream path (67R). The refrigerant that has passed through the second oil cooler (22L) returns to the radiator (60) through the first downstream path (68L) and the confluence path (69). Likewise, in the second refrigerant path (62L), the refrigerant pumped to the second upstream path (66L) by the second radiator pump (64L) flows in the order of the second inverter (40L), the second midstream path (67L), the first oil cooler (22R), the second downstream path (68R), the confluence path (69), and the radiator (60).

[0039] Referring to FIG. 2, the electrical circuit of the driving device (20) is described. The driving device (20) is equipped with a power supply circuit (11) in addition to a pair of electric motors (30R, 30L) and a pair of inverters (40R, 40L). The power supply circuit (11) is a circuit for supplying direct current charging power supplied from an external power source (7) to a battery pack (3). The first electric motor (30R) is a three-phase motor equipped with a U-phase coil (35U), a V-phase coil (35V), and a W-phase coil (35W). The first inverter (40R) is equipped with a U-phase arm (42U), a V-phase arm (42V), and a W-phase arm (42W). Each phase arm (42U, 42V, 42W) has two switching elements connected in series. The first inverter (40R) is a power conversion device that converts DC power supplied from the battery pack (3) into three-phase AC power suitable for driving the first electric motor (30R) by turning on / off the switching elements of each phase arm (42U, 42V, 42W). One end of the U-phase coil (35U), V-phase coil (35V), and W-phase coil (35W) of the first electric motor (30R) is 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] Likewise, the second electric motor (30L) is also equipped with a U-phase coil (35U), a V-phase coil (35V), and a W-phase coil (35W), and the second inverter (40L) is equipped with a U-phase arm (42U), a V-phase arm (42V), and a W-phase arm (42W). Each phase arm (42U, 42V, 42W) has two switching elements in series. The second inverter (40L) is a power conversion device that converts DC power supplied from the battery pack (3) into three-phase AC power suitable for driving the second electric motor (30L) by turning the switching elements of each phase arm (42U, 42V, 42W) on / off. One end of the U-phase coil (35U), the V-phase coil (35V), and the W-phase coil (35W) is 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 second inverter (40L) is electrically connected to the second electric motor (30L).

[0041] In the power supply circuit (11) of the present embodiment, one terminal of the charging inlet (6) is connected to the neutral point NP of the first electric motor (30R) and the positive electrode of the battery pack (3) through the first inverter (40R). The power supply circuit (11) supplies charging power supplied from an external power source (7) to the neutral point NP of the first electric motor (30R). Additionally, the other terminal of the charging inlet (6) is connected to the negative electrode of the battery pack (3) through the first inverter (40R). The power supply circuit (11) supplies charging power to the battery pack (3) through the neutral point NP of the first electric motor (30R). By doing so, 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). Accordingly, the driving device (20) can increase the output voltage of the external power source (7) using the first electric motor (30R) and the first inverter (40R). Accordingly, rapid charging can be performed even if, for example, the output voltage of the external power source (7) is lower than the voltage of the battery pack (3). Additionally, one terminal of the charging inlet (6) is directly connected to the positive terminal of the battery pack (3) through the switch (13). The power supply circuit (11) can bypass the neutral point NP of the first electric motor (30R) with the output voltage of the external power source (7) by turning on the switch (13) when the output voltage of the external power source (7) is equal to the voltage of the battery pack (3). Additionally, although not shown, the power supply circuit (11) also includes a charging unit including a relay, a capacitor, etc. The charging unit is connected to the neutral point NP and the first inverter (40R).

[0042] When the switch (13) is turned off along with the charging inlet (6) being connected to the external power source (7), the charging power of the external power source (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) through the supply to the neutral point NP of the first electric motor (30R) may be referred to as the "charging period." During the charging period, current flows through the coils (35U, 35V, 35W) of each phase of the first electric motor (30R). As a result, the coils (35U, 35V, 35W) of each phase generate heat, and the temperature of the first electric motor (30R) rises. Additionally, during the charging period, the switching element of each phase arm (42U, 42V, 42W) of the first inverter (40R) electrically connected to the first electric motor (30R) is turned on / off, causing the temperature of the first inverter (40R) to rise. Meanwhile, even if the charging inlet (6) is connected to an external power source (7), current does not flow through the coils (35U, 35V, 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) electrically connected to the second electric motor (30L) also does not rise.

[0043] The detailed structure of the drive device (20) will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view of the drive device along line III-III of FIG. 1. In addition to the aforementioned pair of electric motors (30R, 30L), the drive device (20) is equipped with a pair of oil pumps (70R, 70L) housed in the casing (21), a pair of suction pipes (72R, 72L), and a pair of discharge pipes (74R, 74L). Furthermore, the casing (21) is equipped with a partition wall (26) that extends downward from 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 connected at the bottom of the casing (21). A first electric motor (30R) and a first power transmission mechanism (50R) are positioned on the right side of the bulkhead (26). A second electric motor (30L) and a second power transmission mechanism (50L) are positioned on the left side of the bulkhead (26). The driving device (20) is configured symmetrically with respect to the center of the bulkhead (26), that is, the centerline CL1. For this reason, the configuration located on the right side of the centerline CL1 of the driving device (20) will be described mainly below.

[0044] The first electric motor (30R) is equipped with a motor shaft (33R), a rotor (34R), and a stator (35R). The motor shaft (33R) extends in the left and right directions through the rotor (34R) and is rotatably held and supported 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 gear of the first power transmission mechanism (50R). When the motor shaft (33R) rotates as the rotor (34R) rotates, the gear of the first power transmission mechanism (50R) rotates. Although not shown in the illustration, the first power transmission mechanism (50R) rotates the right drive shaft (14R) (see FIG. 1) through a plurality of 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. A plurality of through holes (38R) are formed on the side of the motor shaft (33R). The plurality of through holes (38R) communicate the internal space of the motor shaft (33R) with the internal space of the casing (21). In addition, in FIG. 1, only the two through holes (38R) located at the right end among the plurality of through holes (38R) are labeled, and the labels of the other through holes (38R) are omitted.

[0045] Likewise, the second electric motor (30L) is equipped with a motor shaft (33L), a rotor (34L), and a stator (35L). The motor shaft (33L) extends in the left and right directions through the rotor (34L) and is rotatably held and supported in the casing (21) by a pair of bearings (39L). Additionally, the second power transmission mechanism (50L) also transmits the power of the second electric motor (30L) to the left drive shaft (14L) through a gear or the like connected to the motor shaft (33L) of the second electric motor (30L).

[0046] As illustrated in FIG. 3, oil (76) is stored in the lower part of the casing (21). The casing (21) forms a so-called oil tank. A pair of oil pumps (70R, 70L) is provided with 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 partition wall (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) is provided with 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 tank and bends to the left, connecting to the suction port of the first oil pump (70R). A pair of discharge pipes (74R, 74L) are provided with 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., inside the ground in FIG. 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) positioned on the front side wall. Additionally, 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), and is connected 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) through 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) falls into the internal space of the casing (21) and is then stored in the lower part 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 facilitates the smooth rotation of the first electric motor (30R). Additionally, the oil (76) lubricates the gears of the first power transmission mechanism (50R). As a result, the first power transmission mechanism (50R) rotates smoothly. In FIGS. 3 to 6, the flow of the oil (76) is indicated by solid arrows, and the flow of the refrigerant is indicated by dashed arrows.

[0047] Likewise, the second oil pump (70L) is fixed to the partition (26) from the left. The second oil pump (70L) is a pump that supplies oil (76) to the second electric motor (30L) through 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). By this, oil (76) is supplied to the second electric motor (30L). As indicated by the solid arrow in FIG. 3, the second oil pump (70L) circulates the oil (76). The oil (76) cools the second electric motor (30L) and facilitates the rotation of the second electric motor (30L) and the second power transmission mechanism (50L). In this way, in this embodiment, the first electric motor (30R) and the second electric motor (30L) are cooled by an oil cooling system.

[0048] The control unit (80) is positioned above the first inverter (40R). The control unit (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 unit (80) controls each cooling fan (61R, 61L) and each pump (64R, 64L, 70R, 70L) based on instructions from an upper vehicle control unit not shown. In addition, in a modified example, the control unit (80) may be positioned on any of the right, left, front, and rear sides of the first inverter (40R). Furthermore, the control unit (80) is not limited to one location and may be positioned, for example, on both the left and right sides of the first inverter (40R).

[0049] As described above, 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). Additionally, as described with reference to FIG. 1, the refrigerant cooled by the radiator (60) circulates through the second refrigerant path (62L) in the first oil cooler (22R). Because of this, 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) among the pair of electric motors (30R, 30L) through the oil (76).

[0050] Likewise, the second discharge pipe (74L) passes through the second oil cooler (22L) and is connected to the motor shaft (33L) of the second electric motor (30L). Additionally, as described with reference to FIG. 1, the refrigerant cooled by the radiator (60) circulates through the first refrigerant path (62R) in the second oil cooler (22L). Because of this, 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) among the pair of electric motors (30R, 30L) through the oil (76).

[0051] Additionally, 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 FIG. 1) through the second oil cooler (22L). The first inverter cooler (41R) has a 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) through the refrigerant.

[0052] Likewise, 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 FIG. 1) through the first oil cooler (22R). The second inverter cooler (41L) has a 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) through the refrigerant.

[0053] As illustrated in FIG. 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 centerline CL1 and the second oil cooler (22L) located to the left of centerline CL1. Additionally, 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 centerline CL1 and the first oil cooler (22R) located to the right of centerline CL1. Because of this, the first midstream path (67R) extends from the right of centerline CL1 to the left across centerline CL1, and the second midstream path (67L) extends from the left of centerline CL1 to the right across centerline CL1. As a result, when viewed from the rear of the vehicle, each midstream path (67R, 67L) intersects each other.

[0054] As described above, the first electric motor (30R) is electrically connected to the first inverter (40R). Additionally, the first electric motor (30R) is cooled by the same second refrigerant path (62L) as the second inverter (40L). That is, the first electric motor (30R) is electrically connected to the first inverter (40R), which is different from the second inverter (40L) that is cooled by the same refrigerant path (62L).

[0055] Likewise, the second electric motor (30L) is electrically connected to the second inverter (40L). Additionally, the second electric motor (30L) is cooled by the same first refrigerant path (62R) as the first inverter (40R). That is, the second electric motor (30L) is electrically connected to the second inverter (40L), which is different from the first inverter (40R) that is cooled by the same refrigerant path (62R).

[0056] (Effects of the present embodiment)

[0057] The control device (80) drives a pair of cooling fans (61R, 61L), a second radiator pump (64L), and a first oil pump (70R) as the charging inlet (6) is connected to an external power source (7) via a power cable (8) and the switch (13) is turned off. As a result, the refrigerant cooled by the pair of cooling fans (61R, 61L) is supplied to the first oil cooler (22R) through the second refrigerant path (62L) during the charging period. Additionally, 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 the refrigerant to the first oil cooler (22R) through the second inverter cooler (41L) of the second inverter (40L). The refrigerant that passes through the second inverter (40L) without generating heat is supplied to the first oil cooler (22R), and the oil (76) cooled by the refrigerant cools the first electric motor (30R) that is driven during the charging period. That is, in the driving device (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). By doing so, the amount of cooling required for each refrigerant path (62R, 62L) can be leveled, and the cooling efficiency of the driving device (20) can be improved.

[0058] Additionally, the control device (80) stops the operation of the second oil pump (70L) while driving the first radiator pump (64R) during the charging period. By doing so, the first inverter (40R) operating during the charging period can 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 described above, since the second electric motor (30L) is not driven during the charging period, the temperature of the second electric motor (30L) does not rise. In this way, in the driving device (20) of the present embodiment, by stopping the operation of the second oil pump (70L) during the charging period, it is possible to prevent the second oil pump (70L) from being driven unnecessarily in order to supply oil (76) to the second electric motor (30L) that is not being driven.

[0059] (2nd Example)

[0060] Referring to FIG. 4, a driving device (120) of a second embodiment will be described. In addition to the configuration of the driving device (20) of the first embodiment described above, the driving device (120) of this embodiment also includes a pair of coolers (120R, 120L). The pair of coolers (120R, 120L) includes a first cooler (120R) that cools a first electric motor (30R) and a second cooler (120L) that cools a 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 refrigerant through it. The first cooler (120R) is connected to the first oil cooler (122R) through the second connecting pipe (167R) of the second refrigerant path (62L) (see FIG. 1). The refrigerant that has passed through the first cooler (120R) returns to the radiator (60) through the second downstream path (168R) and the confluence path (69) (see FIG. 1).

[0061] Likewise, 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 connected to the second oil cooler (122L) through the first connecting pipe (167L) of the first refrigerant path (62R) (see FIG. 1). The refrigerant passing through the second cooler (120L) returns to the radiator (60) through the first downstream path (168L) and the confluence path (69) (see FIG. 1).

[0062] In the driving device (120) of the present embodiment, the first electric motor (30R) is cooled by a refrigerant in addition to the oil (76). By this, the first electric motor (30R) can be rapidly cooled by the oil (76) and the refrigerant.

[0063] (3rd Example)

[0064] With reference to FIG. 5, the drive device (220) of the third embodiment will be described. Compared to the drive device (120) of the second embodiment described above, the drive device (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 device (220) of this embodiment, the first inverter cooler (41R) of the first inverter (40R) and the second cooler (120L) are directly connected through the first midstream path (267R), and the second inverter cooler (41L) of the second inverter (40L) and the first cooler (120R) are directly connected through the second midstream path (267L). As in the second embodiment, the refrigerant passing through the first cooler (120R) returns to the radiator (60) through the first downstream path (268R) and the confluence path (69) (see FIG. 1), and the refrigerant passing through the second cooler (120L) returns to the radiator (60) through the second downstream path (268L) and the confluence path (69) (see FIG. 1).

[0065] In addition, in the driving device (220) of the present embodiment, oil (76) (see FIG. 3) is not retained in the lower part of the casing. For this reason, the driving device (220) is provided with a first casing (221R) that accommodates a first electric motor (30R) and a second casing (221L) that accommodates a second electric motor (30L). Each casing (221R, 221L) is arranged in a left-right direction.

[0066] (Fourth Example)

[0067] Referring to FIG. 6, the driving device (320) of the fourth embodiment will be described. The driving device (320) of this embodiment has a configuration basically the same as the driving device (20) of the first embodiment, but the placement location of each device is different. In this embodiment, each electric motor (330R, 330L) is arranged in the left-right central part of the casing (321). 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). Likewise, 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 a second power transmission mechanism (350L) located to the left of the second electric motor (330L).

[0068] The first oil pump (370R) is positioned on the inner wall of the right side of the casing (321), and the second oil pump (370L) is positioned on the inner wall of the left side of the casing (321). Additionally, the first oil cooler (322R) is positioned on the outer wall of the right side of the casing (321), and the second oil cooler (322L) is positioned on the outer wall of the left side of the casing (321). The first oil cooler (322R) accommodates a portion of the first discharge pipe (374R) that extends upward along the outer wall of the right side 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) through the first discharge pipe (374R). Accordingly, oil (76) cooled by the refrigerant in the first oil cooler (322R) is supplied to the first electric motor (330R). Likewise, the second oil cooler (322L) accommodates a portion of the second discharge pipe (374L) extending upward along the outer wall of the left side 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) through the second discharge pipe (374L). Accordingly, oil (76) cooled by the refrigerant in the second oil cooler (322L) is supplied to the second electric motor (330L).

[0069] As illustrated in FIG. 6, in this embodiment as well, the first inverter cooler (41R) of the first inverter (40R) located to the right of centerline CL1 and the second oil cooler (322L) located to the left are connected by the first midstream path (367R). Additionally, the second inverter cooler (41L) of the second inverter (40L) located to the left of centerline CL1 and the first oil cooler (322R) located to the right are connected by the second midstream path (367L). Because of this, when viewed from the rear of the vehicle, each midstream path (367R, 367L) intersects each other.

[0070] Although specific embodiments of the technology disclosed in this specification have been described in detail above, they are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific embodiments exemplified above. Variations of the above embodiments are listed below.

[0071] (Variation Example 1)

[0072] In the above-described embodiment, the driving device (20) is equipped with 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 driving device (20) may, for example, be equipped with three electric motors, three inverters, and three refrigerant paths. In that 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. Additionally, 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 addition, in another variant, the drive unit (20) may be equipped with two electric motors that drive a pair of front wheels (4R, 4L), two electric motors that drive a pair of rear wheels (5R, 5L), and four inverters electrically connected to each motor. In yet another variant, the first electric motor may drive a pair of front wheels (4R, 4L) and the second electric motor may drive a pair of rear wheels (5R, 5L). In that case, the first electric motor and the second electric motor may be arranged in the left-right direction or in the front-back direction.

[0073] (Variation Example 2)

[0074] The driving device (20) of the first embodiment does not need to be equipped with a power supply circuit (11). In this variant, the driving device (20) does not need to supply charging power to the battery pack (3) through the neutral point NP of the first electric motor (30R). In this variant, the control device (80) may drive a pair of cooling fans (61R, 61L), a second radiator pump (64L), and a first oil pump (70R) when, for example, the rotational speed of the first electric motor (30R) exceeds a predetermined value. For example, when the electric vehicle (10) travels on a road that curves to the left, the rotational speed of the first electric motor (30R) driving the right front wheel (4R) may exceed a predetermined value. In this variant, one electric motor with a high rotational speed can be efficiently cooled using a refrigerant that cools an inverter electrically connected to the other electric motor with a low rotational speed.

[0075] (Variation Example 3)

[0076] The driving device (20) of the first embodiment is equipped with two oil pumps (70R, 70L), but in this modified embodiment, it may be equipped with one oil pump. In this modified embodiment, oil (76) may be supplied to two electric motors (30R, 30L) by one oil pump. In this modified embodiment, said one oil pump is an example of a "first oil pump" and a "second oil pump".

[0077] (Variation Example 4)

[0078] The control device (80) does not need to stop the second oil pump (70L) during the charging period. In this variant, the control device (80) may drive a pair of cooling fans (61R, 61L), a pair of radiator pumps (64R, 64L), and a pair of oil pumps (70R, 70L) throughout the charging period. In addition, in another variant, the control device (80) may drive a pair of cooling fans (61R, 61L), a second radiator pump (64L), and a first oil pump (70R) when the temperature of the first electric motor (30R) exceeds a predetermined temperature during the charging period.

[0079] The technical elements described in this specification or drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of those objectives possesses technical utility in itself.

Claims

Claim 1 A driving device (20; 120; 220; 320) comprises a plurality of rotary electric machines (30R, 30L; 330R, 330L) and a plurality of power conversion devices (40R, 40L), and a plurality of refrigerant paths (62R, 62L) configured to cool the plurality of rotary electric machines (30R, 30L; 330R, 330L) and the plurality of power conversion devices (40R, 40L), each of the plurality of power conversion devices (40R, 40L) is electrically connected to at least one of the plurality of rotary electric machines (30R, 30L; 330R, 330L), and each of the plurality of refrigerant paths (62R, 62L) is electrically connected to at least one of the plurality of power conversion devices (40R, 40L) and the plurality of rotary electric A driving device (20; 120; 220; 320) configured to cool at least one of the machines (30R, 30L; 330R, 330L), wherein each of the plurality of rotary electric machines (30R, 30L; 330R, 330L) is electrically connected to a power converter (40R, 40L) different from the at least one power converter (40R, 40L) that is cooled by a refrigerant path (62R, 62L) identical to itself. Claim 2 In claim 1, the plurality of rotary electric machines (30R, 30L; 330R, 330L) include a first rotary electric machine (30R; 330R) and a second rotary electric machine (30L; 330L), and the plurality of power converters (40R, 40L) include a first power converter (40R) electrically connected to the first rotary electric machine (30R; 330R) and a second power converter (40L) electrically connected to the second rotary electric machine (30L; 330L), and the plurality of refrigerant paths (62R, 62L) include a first refrigerant path (62R) configured to cool the first power converter (40R) and the second rotary electric machine (30L; 330L), and the second power converter (40L) and the first rotary electric machine (30R; A driving device (20; 120; 220; 320) comprising a second refrigerant path (62L) configured to cool 330R). Claim 3 In paragraph 2, the drive device (20; 120; 320) further comprises a first oil cooler (22R; 122R; 322R) configured to cool the first rotary electric machine (30R; 330R), and a first oil pump (70R; 370R) configured to supply oil to the first rotary electric machine (30R; 330R) through the first oil cooler (22R; 122R; 322R), wherein the second refrigerant path (62L) is configured to cool the oil within the first oil cooler (22R; 122R; 322R). Claim 4 In paragraph 3, the drive device (20; 120; 320) further comprises a second oil cooler (22L; 122L; 322L) configured to cool the second rotary electric machine (30L; 330L), and a second oil pump (70L; 370L) configured to supply oil to the second rotary electric machine (30L; 330L) through the second oil cooler (22L; 122L; 322L), wherein the first refrigerant path (62R) is configured to cool the oil within the second oil cooler (22L; 122L; 322L). Claim 5 In paragraph 2, a driving device (20; 120; 320) further comprising a casing (21; 321) accommodating the first rotary electric machine (30R; 330R) and the second rotary electric machine (30L; 330L). Claim 6 In paragraph 2, the drive device (120; 220) further comprises a first cooler (120R) in contact with at least a portion of the surface of the first stator (35R) of the first rotary electric machine (30R), and the second refrigerant path (62L) is configured to cool the first rotary electric machine (30R) through the first cooler (120R). Claim 7 In claim 6, the drive device (120; 220) further comprises a second cooler (120L) in contact with at least a portion of the surface of the second stator (35L) of the second rotary electric machine (30L), and the first refrigerant path (62R) is configured to cool the second rotary electric machine (30L) through the second cooler (120L). Claim 8 In claim 6, the drive device (120) further comprises a first oil cooler (122R) configured to cool the first rotary electric machine (30R) and a first oil pump (70R) configured to supply oil to the first rotary electric machine (30R) through the first oil cooler (122R), and the second refrigerant path (62L) is also configured to cool the oil within the first oil cooler (122R), and in the second refrigerant path (62L), the first cooler (120R) and the first oil cooler (122R) are connected in series with each other. Claim 9 In claim 7, the drive device (120) further comprises a second oil cooler (122L) configured to cool the second rotary electric machine (30L) and a second oil pump (70L) configured to supply oil to the second rotary electric machine (30L) through the second oil cooler (122L), wherein the first refrigerant path (62R) is also configured to cool the oil within the second oil cooler (122L), and wherein the second cooler (120L) and the second oil cooler (122L) are connected in series with each other in the first refrigerant path (62R). Claim 10 In paragraph 2, the driving device (20, 120, 220, 320) is configured to be mounted on a vehicle (10) and comprises a charging circuit (11) that supplies a charging current supplied from an external power source (7) of the vehicle (10) to a storage device (3) of the vehicle (10) through the neutral point (NP) of the first rotary electric machine (30R, 330R). Claim 11 In claim 10, the invention further comprises a first oil cooler (22R; 122R; 322R) configured to cool the first rotary electric machine (30R; 330R), a first oil pump (70R; 370R) configured to supply oil to the first rotary electric machine (30R; 330R) through the first oil cooler (22R; 122R; 322R), and a control device (80) configured to control the first oil pump (70R; 370R); the second refrigerant path (62L) is configured to cool the oil within the first oil cooler (22R; 122R; 322R); and the control device (80) is configured such that the charging current is to the capacitor (3) of the vehicle (10) through the neutral point (NP) of the first rotary electric machine (30R; 330R). A driving device (20; 120; 320) that drives the first oil pump (70R; 370R) for at least part of the supplied charging period. Claim 12 In claim 11, the apparatus further comprises a second oil cooler (22L; 122L; 322L) configured to cool the second rotary electric machine (30L; 330L), and a second oil pump (70L; 370L) configured to supply oil to the second rotary electric machine (30L; 330R) through the second oil cooler (22L; 122L; 322L), wherein the first refrigerant path (62R) is configured to cool the oil within the second oil cooler (22L; 122L; 322L), and the control device (80) stops the operation of the second oil pump (70L; 370L) during at least part of the charging period, the driving device (20; 120; 320). Claim 13 In paragraph 2, the drive device (20; 120; 220; 320) is configured to be mounted on a vehicle (10), the first rotary electric machine (30R; 330R) is configured to transmit power to the first drive wheel (4R; 5R; 4R, 5R) of a pair of left and right drive wheels (4R, 4L; 5R, 5L; 4R, 5R, 4L, 5L) of the vehicle (10), and the second rotary electric machine (30L; 330L) is configured to transmit power to the second drive wheel (4L; 5L; 4L, 5L) of a pair of left and right drive wheels (4R, 4L; 5R, 5L; 4R, 5R, 4L, 5L) of the vehicle (10). 320).

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