Cooling circuit and vehicular driving device

Abstract

To provide a cooling circuit capable of maintaining the cooling balance of a vehicle with high cooling efficiency, thereby contributing to the widespread adoption of a vehicle equipped with a TMU, with a low-cost configuration.SOLUTION: A cooling circuit comprises: a first cooling circuit 4A in which oil 8 is pressurized as a first refrigerant 8A by a first pump 10A, causes the oil to passes through a first heat exchanger 12A to thereby cool a first cooling-target portion 14A; a second cooling circuit 4B in which oil 8 is pressurized as a second refrigerant 8B by a second pump 10B, causes the oil to passe through a second heat exchanger 12B to thereby cool a second cooling-target portion 14B; and a third cooling circuit 4C that includes a third heat exchanger 16A and a fourth heat exchanger 16B through which a water-soluble refrigerant flows, and a radiator 20. The third heat exchanger 16A and the fourth heat exchanger 16B are arranged in series. The first cooling circuit 4A and the second cooling circuit 4B merge between a downstream portion of the first heat exchanger 12A and the second heat exchanger 12B and upstream portion of the first cooling-target portion 14A and the second cooling-target portion 14B. The merged refrigerant 8C cools both the first cooling-target portion 14A and the second cooling-target portion 14B.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cooling circuit and a vehicle drive device including the cooling circuit. [Background technology]

[0002] In recent years, the electrification of vehicles has progressed rapidly.Known methods for transmitting drive torque from a motor to the drive wheels include a single motor unit (hereinafter abbreviated as SMU) that distributes the drive torque of a single motor to the left and right drive wheels using a differential device and transmits it to the left and right drive wheels, and a twin motor unit (hereinafter abbreviated as TMU) that has independent left and right motors and transmits motor torque to each of the left and right drive wheels independently to precisely control the drive force on each side.

[0003] TMUs are only used in some high-end vehicles, sports vehicles, and vehicles designed for rough roads, and because the production volume of vehicles equipped with TMUs is lower than that of vehicles equipped with SMUs, depreciation is slow and costs are high. In order to cheaply manufacture vehicles equipped with TMUs, which are produced in small numbers, it is necessary to reuse as many parts as possible from the original SMU. This means that cooled parts such as motors and gears are reused from the SMU, but parts such as electric oil pumps (EOPs) and heat exchangers also need to be reused. This is because manufacturing new parts with a larger capacity than SMU parts would be costly.

[0004] Patent Document 1 discloses a cooling system that connects a first path for cooling a cooling target consisting of a pair of a motor and an inverter and a second path for cooling a cooling target also consisting of a pair of a motor and an inverter via a single reservoir tank and circulates the refrigerant. The reservoir tank is divided by partitions corresponding to the respective paths, and is formed so that the refrigerant introduced from each path partially merges above the partitions. This partial merge configuration allows the refrigerant to circulate in a series path that connects the first path and the second path in series. The partition configuration of the reservoir tank is provided so that if a refrigerant leak occurs in one path, the refrigerant can continue to circulate in the other path (cooling the drive path). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2022-94849 Summary of the Invention [Problem to be solved by the invention]

[0006] Because the capacity of a single SMU component is insufficient, vehicles equipped with a TMU are equipped with two of the same oil pumps and heat exchangers as the SMU, with each mechanism on the left and right sides cooled by its own oil-cooled circuit, thereby reducing costs. Meanwhile, the transmission fluid and other cooling lubricants that circulate through each oil-cooled circuit and cool and lubricate the motor, gears, etc. are cooled (heat exchanged) by the water-cooled circuit. The cooling efficiency of the water-cooled circuit depends on the water supply rate and water temperature. Given the relationship between water supply rate and cooling efficiency, when only one water-cooled circuit is used, it is desirable to connect the two heat exchangers in series with the water-cooled circuit. This is because the total heat exchange efficiency is higher when the left and right oil-cooled circuits are cooled in series with a high flow rate than when the water-cooled circuit is divided into two parts and cooled separately with half the flow rate.

[0007] However, in the case of a series system, the cooling temperatures of the upstream and downstream heat exchangers differ, which in turn changes the cooling temperatures of the left and right motors, gears, bearings, and other equipment in the vehicle, which may result in changes in the cooling balance between the left and right sides of the vehicle, changes in the heat balance between the left and right sides, changes in the performance balance between the left and right sides, and changes in the lifespan of the left and right sides.

[0008] The present invention has been made in consideration of the above points, and its purpose is to provide a cooling circuit that can maintain the cooling balance of a vehicle with high cooling efficiency, and which has an inexpensive configuration that will contribute to the widespread use of vehicles equipped with TMUs. [Means for solving the problem]

[0009] In order to achieve the above object, the cooling circuit (4) of the present invention includes a first cooling circuit (4A) having a first pump (10A) that pumps and delivers the refrigerant (8) stored in the refrigerant storage section (6) as a first refrigerant (8A), a first heat exchanger (12A) that adjusts the temperature of the first refrigerant (8A), and a first cooled portion (14A); a second cooling circuit (4B) having a second pump (10B) that pumps and delivers the refrigerant (8) stored in the refrigerant storage section (6) as a second refrigerant (8B), a second heat exchanger (12B) that adjusts the temperature of the second refrigerant (8B), and a second cooled portion (14B); a third pump (24) that pumps and delivers a third refrigerant (18), and a first and a third cooling circuit (4C) having a third heat exchanger (16A) that exchanges heat with the heat exchanger (12A), a fourth heat exchanger (16B) that exchanges heat with the second heat exchanger (12B), and a fifth heat exchanger (20) that adjusts the temperature of the third refrigerant (18), wherein the third heat exchanger (16A) and the fourth heat exchanger (16B) are arranged in series in the third cooling circuit (4C), and the first cooling circuit (4A) and the second cooling circuit (4B) join together downstream of the first heat exchanger (12A) and the second heat exchanger (12B) in the refrigerant circulation direction and upstream of the first cooled portion (14A) and the second cooled portion (14B).

[0010] The cooling circuit according to the present invention corrects the temperature unevenness between the first and second cooling circuits caused by the third and fourth heat exchangers in the third cooling circuit being connected in series by merging them, thereby maintaining the cooling balance of the vehicle and suppressing changes in the heat balance between the left and right sides of the vehicle, changes in the balance of performance between the left and right sides, and changes in lifespan between the left and right sides. This contributes to reducing the cost of vehicles equipped with TMUs and ultimately to expanding their use.

[0011] In addition, the cooling circuit (4) may be configured such that the refrigerant (8) is oil.

[0012] In the cooling circuit (4), the third refrigerant (18) may be a water-soluble refrigerant.

[0013] In the cooling circuit (4), the fifth heat exchanger (20) may be a radiator that exchanges heat with outside air.

[0014] In the cooling circuit (4), the first heat exchanger (12A) and the second heat exchanger (12B) may have the same structure. This reduces the change in heat balance, thereby enabling the cooling balance of the vehicle to be maintained with high precision.

[0015] In the cooling circuit (4), the third heat exchanger (16A) and the fourth heat exchanger (16B) may have the same structure. This reduces the change in heat balance, thereby enabling the cooling balance of the vehicle to be maintained with high accuracy.

[0016] In the cooling circuit (4), the first part to be cooled (14A) and / or the second part to be cooled (14B) may be a motor.

[0017] In the cooling circuit (4), the first cooled part (14A) and the second cooled part (14B) may be motors of the same structure. In this case, the change in the heat balance between the two motors is small, and therefore the cooling balance of the vehicle can be maintained with high precision.

[0018] In the cooling circuit (4), the first pump (10A) and the second pump (10B) may be configured to have the same structure. In this case, the difference in performance between the two pumps is small, and therefore the cooling balance of the vehicle can be maintained with high precision.

[0019] In the cooling circuit (4), the first pump (10A) and the second pump (10B) may be electric pumps, which facilitates control of the suction and discharge rates.

[0020] The cooling circuit (4) may also be configured to include a first pump failure detection means (42A) that detects a failure of the first pump (10A), a second pump failure detection means (42B) that detects a failure of the second pump (10B), a first valve (44A) that is arranged between the first heat exchanger (12A) and the first cooled section (14A) of the first cooling circuit (4A), a second valve (44B) that is arranged between the second heat exchanger (12B) and the second cooled section (14B) of the second cooling circuit (4B), and a control means (36) that closes the first valve (44A) when the first pump failure detection means (42A) detects a failure of the first pump (10A), and that closes the second valve (44B) when the second pump failure detection means (42B) detects a failure of the second pump (10B). This allows the cooling circuit provided by the other pump to function as a backup even if one of the pumps breaks down, making it possible to temporarily drive the vehicle to a repair facility such as a dealer.

[0021] In addition, in the cooling circuit (4), the control means (36) may be configured to increase the output of the second pump (10B) when the first pump failure detection means (42A) detects a failure of the first pump (10A), and to increase the output of the first pump (10A) when the second pump failure detection means (42B) detects a failure of the second pump (10B). This can suppress a decrease in cooling efficiency due to a decrease in the amount of refrigerant when the first cooled part and the second cooled part are cooled by only a single cooling circuit (the first cooling circuit or the second cooling circuit), and enables temporary driving to a repair facility such as a dealer.

[0022] The cooling circuit (4) may further include a first flow rate sensor (46A) that detects the refrigerant flow rate in the first cooling circuit (4A) and a second flow rate sensor (46B) that detects the refrigerant flow rate in the second cooling circuit (4B), and the control means (36) may determine that the first cooling circuit (4A) has failed and close the first valve (44A) when the first flow rate sensor (46A) detects that the discharge flow rate of the first pump (10A) has been lower than the specified value for a certain period of time or longer, and may determine that the second cooling circuit (4B) has failed and close the second valve (44B) when the second flow rate sensor (46B) detects that the discharge flow rate of the second pump (10B) has been lower than the specified value for a certain period of time or longer. In this way, even if one pump fails, the cooling circuit using the other pump can function as a backup, allowing the vehicle to temporarily travel to a repair facility such as a dealer.

[0023] Furthermore, the vehicle drive device (2A, 2B, 2C) of the present invention includes the above-described cooling circuits (4). The vehicle drive device of the present invention can obtain the effects of the above-described cooling circuits.

[0024] The vehicle drive device (2A, 2B, 2C) of the present invention includes first pump failure detection means (42A) for detecting a failure of the first pump (10A), second pump failure detection means (42B) for detecting a failure of the second pump (10B), a first valve (44A) arranged between the first heat exchanger (12A) and the first cooled portion (14A) of the first cooling circuit (4A), a second valve (44B) arranged between the second heat exchanger (12B) and the second cooled portion (14B) of the second cooling circuit (4B), and a valve (44B) for detecting a failure of the first pump (10A) when the first pump failure detection means (42A) detects a failure of the first pump (10A). and a control means (36) that closes the first valve (44A) when a failure of the pump (10A) is detected and closes the second valve (44B) when the second pump failure detection means (42B) detects a failure of the second pump (10B), and that reduces the functions of the first cooled part (4A) and the second cooled part (4B) when the first pump failure detection means (42A) detects a failure of the first pump (10A) and / or the second pump failure detection means (42B) detects a failure of the second pump (10B).The vehicle drive device according to the present invention can prevent a sudden decrease in cooling efficiency when the first pump or the second pump fails by setting the output to correspond to a small flow rate of oil (first refrigerant or second refrigerant). [Effects of the Invention]

[0025] According to the present invention, it is possible to maintain the cooling balance of the vehicle with high cooling efficiency, and ultimately the inexpensive configuration will contribute to the widespread use of vehicles equipped with TMUs. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic diagram of a cooling circuit of a vehicle drive device according to a first embodiment of the present invention. [Figure 2] 2 is a detailed diagram of a cooling circuit of the vehicle drive device shown in FIG. 1. [Figure 3] 2 is a detailed view of a first cooled portion and a second cooled portion in the cooling circuit shown in FIG. 1. [Figure 4] FIG. 10 is a detailed view of a cooling circuit of a vehicle drive device according to a second embodiment. [Figure 5] 5 is a partially omitted view showing a backup configuration in the event that one of the pumps in the cooling circuit shown in FIG. 4 fails. [Figure 6] 5 is a partially omitted view showing a backup configuration in the event that the other pump in the cooling circuit shown in FIG. 4 fails. [Figure 7] FIG. 10 is a detailed view of a cooling circuit of a vehicle drive device according to a third embodiment. [Figure 8] 8 is a partially omitted view showing a backup configuration in the event that one of the cooling circuits shown in FIG. 7 fails. [Figure 9] 8 is a partially omitted view showing a backup configuration in the event that the other cooling circuit in the cooling circuits shown in FIG. 7 fails. [Figure 10] These diagrams are used to explain the problems that arise due to the configuration of the water cooling circuit. (a) is a diagram showing the case where the water cooling circuit is divided, and (b) is a diagram showing the case where the water cooling circuit is connected in series to form a single system. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing, flow paths (pipes) and the fluid (refrigerant) flowing therethrough are shown by single lines without distinction.

[0028] Before describing this embodiment, we will specifically explain the problems associated with separate and serial water-cooling circuits. Figure 10(a) shows an example of a configuration in which two cooled components 100A and 100B, including motors and gears, are cooled by separate oil-cooling circuits. The water-cooling circuits are divided, with the flow rate halved, for heat exchange with the left and right oil-cooling circuits. In each oil-cooling circuit, oil is drawn from an oil reservoir 102 by electric oil pumps 104A and 104B, and passes through oil heat exchangers 108A and 108B, which exchange heat with water heat exchangers 106A and 106B, forming a circulation path for cooling the cooled components 100A and 100B. After heat exchange with oil heat exchangers 108A and 108B in the water-cooling circuits, the water is air-cooled in a radiator 110 and then resupplied by a water pump (not shown). This configuration eliminates heat unevenness in each oil-cooling circuit. However, the water flow rate of the left and right water cooling circuits is small, and the cooling efficiency of the water cooling circuits depends on the water flow rate, so the heat exchange rate with the oil heat exchangers 108A, 108B is low, and the oil discharged from the oil heat exchangers 108A, 108B is not sufficiently cooled and becomes lukewarm, resulting in a decrease in the cooling efficiency of the cooled parts 100A, 100B.

[0029] Figure 10(b) shows a single water-cooling circuit without splitting it, cooling the left and right oil-cooling circuits in series. The increased water flow rate in the water-cooling circuit improves the overall heat exchange rate. However, the cooling efficiency for the oil heat exchangers 108A and 108B differs between the upstream and downstream sides of the water-cooling circuit. Specifically, the oil discharged from the upstream oil heat exchanger 108B is cold due to its high heat exchange rate with the water heat exchanger 106B, while the oil discharged from the downstream oil heat exchanger 108A is warm due to its low heat exchange rate with the water heat exchanger 106A. This inevitably leads to changes in the cooling efficiency of the cooled components 100A and 100B, resulting in uneven heating. If uneven heating is allowed to continue for a long period of time, the balance between the performance and durability (lifespan) of the cooled components 100A and 100B is likely to be disrupted. This problem also occurs in cooling circuits constructed using SMU components to build a low-cost TMU.

[0030] [First embodiment] An outline of this embodiment, which solves the above problem, will be described with reference to Fig. 1. Fig. 1 shows a cooling circuit for a motor drive unit that individually drives the left and right drive wheels of a vehicle equipped with a TMU.

[0031] The vehicle drive device 2A has a cooling circuit 4. The cooling circuit 4 is composed of a first cooling circuit 4A, a second cooling circuit 4B, and a third cooling circuit 4C. The first cooling circuit 4A has a first pump 10A that pumps out oil 8, a refrigerant stored in an oil tank 6 that serves as a refrigerant storage unit, as a first refrigerant 8A, a first heat exchanger 12A that is connected in series with the first pump 10A and that adjusts the temperature of the first refrigerant 8A, and a first cooled part 14A. The second cooling circuit 4B has a second pump 10B that pumps out oil 8, a second heat exchanger 12B that is connected in series with the second pump 10B and that adjusts the temperature of the second refrigerant 8B, and a second cooled part 14B. The third cooling circuit 4C includes a third pump (described below) that pumps the third refrigerant 18, a third heat exchanger 16A that exchanges heat with the first heat exchanger 12A, a fourth heat exchanger 16B that exchanges heat with the second heat exchanger 12B, and a radiator 20 that exchanges heat with outside air as a fifth heat exchanger that adjusts the temperature of the third refrigerant 18. The first heat exchanger 12A and the second heat exchanger 12B have the same structure, and the third heat exchanger 16A and the fourth heat exchanger 16B also have the same structure.

[0032] The first pump 10A and the second pump 10B are both electric oil pumps (EOPs) of the same structure. The temperature of the first refrigerant 8A supplied to the first heat exchanger 12A by the first pump 10A is approximately the same as the temperature of the second refrigerant 8B supplied to the second heat exchanger 12B by the second pump 10B. The third refrigerant 18 is a water-soluble refrigerant, specifically a long-life coolant (LLC) mixed with antifreeze. Water may also be used as the third refrigerant 18.

[0033] The third heat exchanger 16A and the fourth heat exchanger 16B are arranged (connected) in series in the third cooling circuit 4C, and the first cooling circuit 4A and the second cooling circuit 4B are configured to merge downstream of the first heat exchanger 12A and the second heat exchanger 12B in the refrigerant circulation direction and upstream of the first cooled portion 14A and the second cooled portion 14B. The refrigerant circulation direction is the direction in which the first refrigerant 8A and the second refrigerant 8B circulate. By arranging the third heat exchanger 16A and the fourth heat exchanger 16B in series in the third cooling circuit 4C, the supply amount of the third refrigerant 18 is not dispersed. This improves the overall efficiency of the first heat exchange between the first heat exchanger 12A and the third heat exchanger 16A and the second heat exchange between the second heat exchanger 12B and the fourth heat exchanger 16B compared to the parallel arrangement shown in FIG. 10(a). This also enables the third cooling circuit 4C to be configured simply, lightweight, and inexpensively.

[0034] However, because the third heat exchanger 16A and the fourth heat exchanger 16B are connected in series, the temperature of the third refrigerant 18 is higher downstream in the circulation direction of the third refrigerant 18, resulting in different oil temperatures after heat exchange between the first heat exchanger 12A and the second heat exchanger 12B. This results in uneven heat distribution between the first cooled portion 14A and the second cooled portion 14B, resulting in different cooling temperatures. To prevent device malfunctions caused by uneven cooling temperatures, in this embodiment, the first refrigerant 8A' and the second refrigerant 8B' discharged from the first heat exchanger 12A and the second heat exchanger 12B, respectively, are merged before being supplied to the first cooled portion 14A and the second cooled portion 14B. The merged refrigerant 8C, whose temperature has been equalized, is then supplied to the first cooled portion 14A and the second cooled portion 14B, respectively. This allows for high cooling efficiency and maintains the cooling balance of the vehicle, suppressing changes in the heat balance between the left and right sides of the vehicle, changes in performance balance between the left and right sides, and changes in lifespan between the left and right sides.

[0035] This embodiment will be described in detail with reference to FIG. 2. In the third cooling circuit 4C, the third refrigerant 18, air-cooled by the radiator 20, is pumped to the fourth heat exchanger 16B by a third pump 24, which is an inverter pump. To maximize the reuse of SMU components, two inverter pumps may be used in combination as the third pump 24. Reference numerals 26A and 26B indicate water-cooled oil coolers. Oil 8 stored in the oil tank 6 is drawn by the first pump 10A as the first refrigerant 8A through a strainer 28A on the left side of the drawing, and drawn by the second pump 10B as the second refrigerant 8B through a strainer 28B on the right side of the drawing. In this embodiment, the oil 8 stored in the oil tank 6 is automatic transmission fluid (ATF), but the oil 8 may also be battery-powered electric vehicle fluid (BEVF), etc.

[0036] The first refrigerant 8A' that has passed through the first heat exchanger 12A and the second refrigerant 8B' that has passed through the second heat exchanger 12B join at a confluence point CF, where the temperature is equalized and then branched to the left and right to cool the first cooled portion 14A and the second cooled portion 14B. As shown in FIG. 3 in detail, the first cooled portion 14A includes a left-side motor 15A and an inverter 17 that drives it, while the second cooled portion 14B includes a right-side motor 15B and an inverter 17 that drives it. Only the motors 15A and 15B are shown in FIG. 2. The motors 15A and 15B have the same structure. The term "same structure" here also includes cases where the motors have slight structural differences but are substantially identical in terms of heat balance. The first pump 10A and the second pump 10B are controlled by an ECU (electronic control unit) 36, which serves as a control means. The ECU 36 includes a microcomputer having a CPU, ROM, RAM, interfaces, etc. The ECU 36 receives detection values from a motor temperature detection sensor 38A that detects the temperature of the left motor 15A, a motor temperature detection sensor 38B that detects the temperature of the right motor 15B, and an oil temperature detection sensor 40 that detects the temperature of the oil 8 in the oil tank 6.

[0037] 3, the ECU 36 also serves as a drive control means for controlling the driving of the motors 15A, 15B via the inverter 17 (omitted in FIG. 2). Of course, the control means for the cooling circuit 4 and the drive control means for the vehicle drive device 2A may be configured separately and connected to each other so as to be able to communicate with each other.

[0038] According to this embodiment, the temperature unevenness of the oil-cooled circuits (first cooling circuit 4A, second cooling circuit 4B) caused by connecting the water-cooled circuit (third cooling circuit 4C) in series is corrected by merging them, so the configuration of the water-cooled circuit can be simplified while maintaining the cooling balance of the vehicle with high cooling efficiency, and changes in the heat balance between the left and right sides of the vehicle, changes in the performance balance between the left and right sides, and changes in the lifespan between the left and right sides can be suppressed. This can also contribute to reducing the cost and expanding the use of vehicles equipped with TMUs by reusing SMU parts.

[0039] The cooling system disclosed in Patent Document 1 allows the refrigerant to flow in a serial path by partially merging the same refrigerant circuits in a reservoir tank, and the temperature of each refrigerant before merging can be considered to be approximately the same, so there is no problem of uneven temperature between the same refrigerant circuits due to heat exchange with a different type of refrigerant (third refrigerant 18 in this embodiment).

[0040] [Second embodiment] The second embodiment will be described with reference to Figures 4 to 6. Parts that are the same as or can be considered the same as those in the first embodiment are indicated by the same reference numerals, and the explanations of the configuration and function already given will be omitted as appropriate (the same applies to the other embodiments described below).

[0041] 4, the cooling circuit 4 of the vehicle drive system 2B according to this embodiment includes, in addition to the components shown in FIG. 2, a first flow meter 42A disposed immediately downstream of the first pump 10A as first pump failure detection means for detecting a failure of the first pump 10A, a second flow meter 42B disposed immediately downstream of the second pump 10B as second pump failure detection means for detecting a failure of the second pump 10B, a first valve 44A disposed between the first heat exchanger 12A and the first cooled portion 14A in the first cooling circuit 4A, a second valve 44B disposed between the second heat exchanger 12B and the second cooled portion 14B in the second cooling circuit 4B, and a control means (ECU 36) that closes the first valve 44A when the first flow meter 42A detects a failure of the first pump 10A and closes the second valve 44B when the second flow meter 42B detects a failure of the second pump 10B. The values detected by the first flow meter 42A and the second flow meter 42B are input to the ECU 36. The first valve 44A and the second valve 44B are both electromagnetic valves.

[0042] The ECU 36 determines that the first pump 10A has failed when the difference between the flow rate (known) of the pumped air by the first pump 10A and the flow rate detected by the first flow meter 42A is outside a predetermined range. Similarly, the ECU 36 determines that the second pump 10B has failed when the difference between the flow rate (known) of the pumped air by the second pump 10B and the flow rate detected by the second flow meter 42B is outside a predetermined range. When the ECU 36 determines that the first pump 10A has failed, it stops the operation of the first pump 10A and closes the first valve 44A. In this case, as shown in FIG. 5, oil (the second refrigerant 8B' that has passed through the second heat exchanger 12B) flows only in the second cooling circuit 4B, and this oil branches off to cool the first cooled portion 14A and the second cooled portion 14B. Because cooling is performed only by the second refrigerant 8B', the cooling temperatures of the first cooled portion 14A and the second cooled portion 14B are uniform, preventing uneven heating. When the ECU 36 determines that the second pump 10B has failed, it stops driving the second pump 10B and controls the second valve 44B to close. In this case, as shown in Fig. 6, oil (first refrigerant 8A' that has passed through the second heat exchanger 12A) flows only in the first cooling circuit 4A, and this oil branches off to cool the first cooled portion 14A and the second cooled portion 14B. Because cooling is performed only by the first refrigerant 8A', the cooling temperatures of the first cooled portion 14A and the second cooled portion 14B are uniform, and no uneven heating occurs.

[0043] According to this embodiment, even if one of the oil cooling circuits (the first cooling circuit 4A or the second cooling circuit 4B) does not function properly due to a malfunction of the first pump 10A or the second pump 10B, the remaining oil cooling circuit can function as a backup, which allows temporary driving to a repair facility such as a dealer.

[0044] When the first flow meter 42A detects a failure of the first pump 10A, the ECU 36 may increase the output of the second pump 10B if there is a margin in the output of the second pump 10B, and when the second flow meter 42B detects a failure of the second pump 10B, the ECU 36 may increase the output of the first pump 10A if there is a margin in the output of the first pump 10A. In this manner, it is possible to suppress a decrease in cooling efficiency due to a decrease in the amount of oil when the first cooled portion 14A and the second cooled portion 14B are cooled only by oil (first refrigerant 8A' or second refrigerant 8B') in a single oil cooling circuit, it is possible to suppress temporary functional limitations to the ability to transport the vehicle to a repair facility if either the first pump 10A or the second pump 10B fails, and it is possible to suppress a decrease in vehicle speed.

[0045] The configuration may include a drive control means for reducing the functions of the first cooled part 4A and the second cooled part 4B when the first flow meter 42A detects a failure of the first pump 10A and / or the second flow meter 42B detects a failure of the second pump 10B. That is, the ECU 36, which also serves as the drive control means, controls the inverter 17 to reduce the output of the motor 15A of the first cooled part 14A and the motor 15B of the second cooled part 14B. In this way, the output corresponds to the flow rate of a small amount of oil (first refrigerant 8A' or second refrigerant 8B'), thereby preventing a sudden decrease in cooling efficiency.

[0046] [Third embodiment] A third embodiment will be described with reference to Figures 7 to 9. As shown in Figure 7, the cooling circuit 4 of the vehicle drive system 2C according to this embodiment includes, in addition to the configuration shown in Figure 4, a first flow rate sensor 46A that detects the oil flow rate in the first cooling circuit 4A and a second flow rate sensor 46B that detects the oil flow rate in the second cooling circuit 4B. When the first flow rate sensor 46A detects that the discharge flow rate of the first pump 10A has been lower than the predetermined value for more than a certain period of time, the control unit (ECU 36) determines that the first cooling circuit 4A has failed and closes the first valve 44A. When the second flow rate sensor 46B detects that the discharge flow rate of the second pump 10B has been lower than the predetermined value for more than a certain period of time, the control unit (ECU 36) determines that the second cooling circuit 4B has failed and closes the second valve 44B. Note that the terms "flow meter" and "flow rate sensor" are merely used for illustrative purposes, and there is no structural or functional difference between them.

[0047] When the first flow rate sensor 46A detects that the discharge flow rate (known) of the first pump 10A has been lower for a certain period of time or longer, the ECU 36 determines that the first cooling circuit 4A has failed, stops the operation of the first pump 10A, and closes the first valve 44A. In this case, as shown in FIG. 8 , oil (the second refrigerant 8B' that has passed through the second heat exchanger 12B) flows only in the second cooling circuit 4B, and this oil branches off to cool the first cooled portion 14A and the second cooled portion 14B. Because cooling is performed only by the second refrigerant 8B', the cooling temperatures of the first cooled portion 14A and the second cooled portion 14B are uniform, preventing uneven heating. When the second flow rate sensor 46B detects that the discharge flow rate (known) of the second pump 10B has been lower for a certain period of time or longer, the ECU 36 determines that the second cooling circuit 4B has failed, stops the operation of the second pump 10B, and closes the second valve 44B. 9, oil (first refrigerant 8A' that has passed through second heat exchanger 12A) flows only in first cooling circuit 4A, and then branches to cool first cooled portion 14A and second cooled portion 14B. Because cooling is performed only by first refrigerant 8A', the cooling temperatures of first cooled portion 14A and second cooled portion 14B are uniform, and no uneven heating occurs.

[0048] If the first flow meter 42A or the second flow meter 42B does not detect a failure of the first pump 10A or the second pump 10B, and a failure of the first cooling circuit 4A or the second cooling circuit 4B is determined based on the first flow sensor 46A or the second flow sensor 46B, the ECU 36 determines that a refrigerant leak has occurred in the first cooling circuit 4A or the second cooling circuit 4B.

[0049] According to this embodiment, by arranging the first flow sensor 46A and the second flow sensor 46B at a position away from the first pump 10A and the second pump 10B, it is possible to detect not only failures of the first pump 10A or the second pump 10B, but also refrigerant leaks in the first cooling circuit 4A or the second cooling circuit 4B even when the first pump 10A or the second pump 10B is not malfunctioning, and it is possible to identify the malfunctioning part in detail.

[0050] Although the above describes embodiments of the present invention, the present invention is not limited to these embodiments and various modifications are possible within the scope of the claims and the technical concepts described in the specification and drawings. For example, while the above embodiments illustrate the cost reduction of TMU installation by reusing SMU components, cooling efficiency can also be improved when designing a new system without reusing SMU components. Furthermore, the horizontal positions of the first valve 44A and the first flow sensor 46A in FIG. 7 and the horizontal positions of the second valve 44B and the second flow sensor 46B in the same direction may be reversed. Furthermore, while the above embodiments are configured to detect failures of the first pump 10A and the second pump 10B using the first flow meters 42A and the second flow meters 42B, hydraulic pressure meters may be installed downstream of the first pump 10A and the second pump 10B, and a failure may be detected when the hydraulic pressure falls outside a specified range. Furthermore, an ammeter may be installed in the power circuit supplying power to the motors of the first pump 10A and the second pump 10B, which are electric oil pumps, and a failure may be detected when the current value falls outside a specified range. Furthermore, a tachometer may be installed on the motor shaft of the first pump 10A and the second pump 10B or on the gear shaft of the gear pump, and a failure may be determined when the rotation speed deviates from a predetermined range. [Explanation of symbols]

[0051] 2A, 2B, 2C Vehicle drive unit 4 Cooling circuit 4A first cooling circuit 4B Second cooling circuit 4C Third cooling circuit 6 Oil tank (refrigerant storage section) 8 Oil (refrigerant) 8A, 8A´ First refrigerant 8B, 8B´ Second refrigerant 10A First Pump 10B Second pump 12A first heat exchanger 12B Second heat exchanger 14A First cooled part 14B Second cooled part 15A, 15B motor 16A tertiary heat exchanger 16B Fourth heat exchanger 20 Radiator (fifth heat exchanger) 24 Third Pump 36 ECU (control means) 42A First flow meter (first pump failure detection means) 42B Second flow meter (second pump failure detection means) 44A First Valve 44B Second valve 46A First flow sensor 46B Second flow sensor

Claims

1. a first cooling circuit including a first pump that pumps out a refrigerant stored in a refrigerant storage portion as a first refrigerant, a first heat exchanger that adjusts a temperature of the first refrigerant, and a first cooled portion; a second cooling circuit including a second pump that pumps out the refrigerant stored in the refrigerant storage portion as a second refrigerant, a second heat exchanger that adjusts a temperature of the second refrigerant, and a second cooled portion; a third cooling circuit including a third pump that pumps a third refrigerant, a third heat exchanger that exchanges heat with the first heat exchanger, a fourth heat exchanger that exchanges heat with the second heat exchanger, and a fifth heat exchanger that adjusts the temperature of the third refrigerant; Equipped with the third heat exchanger and the fourth heat exchanger are arranged in series in the third cooling circuit; A cooling circuit characterized in that the first cooling circuit and the second cooling circuit converge downstream of the first heat exchanger and the second heat exchanger in the refrigerant circulation direction and upstream of the first cooled portion and the second cooled portion.

2. 2. The cooling circuit of claim 1, wherein the refrigerant is oil.

3. 2. The cooling circuit of claim 1, wherein the third refrigerant is a water-soluble refrigerant.

4. 2. The cooling circuit according to claim 1, wherein the fifth heat exchanger is a radiator that exchanges heat with outside air.

5. 2. The cooling circuit according to claim 1, wherein the first heat exchanger and the second heat exchanger have the same structure.

6. 2. The cooling circuit according to claim 1, wherein the third heat exchanger and the fourth heat exchanger have the same structure.

7. 2. The cooling circuit according to claim 1, wherein the first cooled part and / or the second cooled part is a motor.

8. 2. The cooling circuit according to claim 1, wherein the first cooled part and the second cooled part are motors having the same structure.

9. 2. The cooling circuit according to claim 1, wherein the first pump and the second pump have the same structure.

10. 2. The cooling circuit according to claim 1, wherein the first pump and the second pump are electric pumps.

11. a first pump failure detection means for detecting a failure of the first pump; a second pump failure detection means for detecting a failure of the second pump; a first valve disposed between the first heat exchanger of the first cooling circuit and the first cooled portion; a second valve disposed between the second heat exchanger and the second cooled portion of the second cooling circuit; a control means for closing the first valve when the first pump failure detection means detects a failure of the first pump, and for closing the second valve when the second pump failure detection means detects a failure of the second pump; The cooling circuit according to claim 10, characterized in that it comprises:

12. 12. The cooling circuit according to claim 11, wherein the control means increases the output of the second pump when the first pump failure detection means detects a failure of the first pump, and increases the output of the first pump when the second pump failure detection means detects a failure of the second pump.

13. a first flow rate sensor that detects an oil flow rate in the first cooling circuit; a second flow rate sensor that detects the oil flow rate in the second cooling circuit; Equipped with The cooling circuit according to claim 11, characterized in that when the first flow rate sensor detects that the discharge flow rate of the first pump has been lower than the specified value for more than a certain period of time, the control means determines that the first cooling circuit has failed and closes the first valve, and when the second flow rate sensor detects that the discharge flow rate of the second pump has been lower than the specified value for more than a certain period of time, the control means determines that the second cooling circuit has failed and closes the second valve.

14. A vehicle drive system comprising the cooling circuit according to any one of claims 1 to 13.

15. a cooling circuit according to claim 11; a drive control means for reducing the functions of the first cooled portion and the second cooled portion when the first pump failure detection means detects a failure of the first pump and / or when the second pump failure detection means detects a failure of the second pump; A vehicle drive device having the same.

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