Cooling system for a rotating electric machine

Abstract

An object of the present invention is to provide a cooling system for a rotating electric machine in which the flow rate ratio between a coolant supplied to a stator and the coolant supplied to a rotor can be changed, thereby improving the cooling effect of the rotating electric machine. The cooling system 1 for the rotating electric machine 1 of this embodiment comprises the coolant flow path 7, which supplies the coolant, the switching mechanism 3, which switches the mode of the coolant flow path 7, and the pump 4, which pumps the coolant to the coolant flow path 7. The coolant flow path 7 has the first coolant flow path section 71, which supplies the coolant to the core 21A of the stator 21, and the second coolant flow path section 72, which supplies the coolant to the rotor 22.The switching mechanism 3 is configured to achieve the first mode, in which the coolant is supplied to the first coolant flow path section 71 and the coolant is not supplied to the second coolant flow path section 72, and the second mode, in which the downstream of the first coolant flow path section 71 and the upstream of the second coolant flow path section 72 are connected.

Description

Technical area

[0001] This invention relates to a cooling system for a rotating electrical machine. State of the art

[0002] Patent Literature 1 describes a cooling system for a rotating electric machine including coolant flow paths (a first coolant flow path and a sixth coolant flow path) that supply coolant to a first coil end portion and a second coil end portion of the rotating electric machine, and a coolant flow path (a fifth coolant flow path) that supplies the coolant to a magnet of the rotating electric machine (paragraphs 0027, 0031, and 0032). The first coil end portion and the second coil end portion are provided on a stator, and the coolant flow paths (the first coolant flow path and the sixth coolant flow path) form coolant flow paths that supply the coolant to the stator. The magnet is provided in a rotor, and the coolant flow path (the fifth coolant flow path) forms a coolant flow path that supplies the coolant to the rotor.The fifth coolant flow path is provided branching from the first coolant flow path and is configured to allow a part of the coolant flowing in the first coolant flow path to flow to the magnet of the rotor (paragraph 0031). Citation listPatent literature

[0003] Patent Literature 1: Japanese Patent Application Laid-Open No. 2019-161898 Summary of the inventionTechnical problem

[0004] In the cooling system for the rotating electric machine of Patent Literature 1, the connection state of the first coolant flow path and the fifth coolant flow path is not changed. Therefore, the flow rate of the coolant supplied to the stator and the flow rate of the coolant supplied to the rotor are changed according to the flow rate of the coolant flowing in the first coolant flow path while maintaining the constant flow rate.

[0005] An object of the present invention is to provide a cooling system for a rotating electric machine in which the flow rate ratio between a coolant supplied to a stator and the coolant supplied to a rotor can be changed and the cooling effect of the rotating electric machine can be improved. Solution to the problem

[0006] To achieve the above object, in the present invention, a cooling system for a rotating electric machine having a stator and a rotor includes: a coolant flow path that supplies a coolant; a switching mechanism that switches the mode of the coolant flow path; and a pump that pumps the coolant to the coolant flow path.The coolant flow path includes a first coolant flow path portion that supplies the coolant to a core of the stator and a second coolant flow path portion that supplies the coolant to the rotor, and the switching mechanism is configured to achieve a first mode in which the coolant is supplied to the first coolant flow path portion and the coolant is not supplied to the second coolant flow path portion, and a second mode in which the downstream of the first coolant flow path portion and the upstream of the second coolant flow path portion are communicated with each other. Advantageous effects of the invention

[0007] According to the present invention, it is possible to change the flow rate ratio between a coolant supplied to a stator and the coolant supplied to a rotor and improve the cooling effect of the rotating electric machine.

[0008] Objects, configurations, and effects different from the above will become apparent from the description of the following embodiments. Short description of the drawings Fig. 1 is a diagram illustrating an outline of the configuration of a first embodiment (Embodiment 1) of a cooling system for a rotating electric machine of the present invention. Fig. 2 is a schematic diagram illustrating a changing example (a first changing example: Changing Example 1) of the configuration of a pump of the cooling system for the rotating electric machine according to the first embodiment of the present invention. Fig. 3 is a schematic diagram illustrating a changing example (a second changing example: Changing Example 2) of the drive source of the pump of the cooling system for the rotating electric machine according to the first embodiment of the present invention. Fig. 4 is a schematic diagram illustrating a changing example (a third changing example: changing example 3) of the drive source of the pump of the cooling system for the rotating electric machine according to the first embodiment of the present invention. Fig. 5 is an explanatory view showing the connection mode of a coolant flow path of the cooling system for the rotating electric machine of Fig. 1 illustrates. Fig. 6 is a graph illustrating the relationship between vehicle speed and coolant supply amount in the cooling system for the rotating electric machine according to the present invention. Fig. 7 is a schematic configuration diagram illustrating a changing example (a fourth changing example: changing example 4) of a switching mechanism of the cooling system for the rotating electric machine according to the first embodiment of the present invention. Fig. Figure 8 is a diagram showing the open or closed state of a valve in each speed range of the cooling system for the rotating electrical machine of Fig. 7 illustrates. Fig. 9 is a schematic configuration diagram illustrating a changing example (a fifth changing example: Changing Example 5) of the switching mechanism of the cooling system for the rotating electric machine according to the first embodiment of the present invention. Fig. 10 is a graph illustrating the relationship between the vehicle speed and the coolant supply amount in the case where the operating range of an electric pump is changed in the cooling system for the rotating electric machine according to the present invention. Description of the embodiments

[0009] An e-axle, which integrates a motor, inverter, and gearbox, has higher loss density with higher output density. To cope with this higher loss density, the cooling performance of a rotating electrical machine should be improved by a cooling system with a direct oil cooling configuration. In the oil cooling configuration, a pump that pumps a coolant (a cooling oil) is required. For example, a mechanical pump (a mechanical oil pump) and an electric pump (an electric oil pump) can be used as the pump. It should be noted that since the discharge amount of the mechanical pump changes according to the rotational speed, when the mechanical pump is used, the coolant supply amount must be appropriately controlled to ensure cooling performance at any rotational speed.

[0010] In the following embodiment, an example using a mechanical pump is also described. Since the discharge volume of the mechanical pump is reduced in the low-speed range, the cooling performance of the rotating electrical machine is reduced in the low-speed range. To prevent the cooling performance from decreasing in the low-speed range, the pump needs to be larger. In the embodiment using a mechanical pump, the pump size is prevented by suppressing the cooling performance of the rotating electrical machine from decreasing in the low-speed range.

[0011] In addition, in the following embodiment, the loss torque in the middle speed range, whose usage frequency is high in city driving, is reduced and the electrical efficiency is improved.

[0012] An embodiment of the present invention will be described below with reference to the drawings. Embodiment 1

[0013] Fig. 1 is a diagram illustrating an outline of the configuration of a first embodiment (Embodiment 1) of a cooling system 1 for a rotating electric machine 2 of the present invention.

[0014] The cooling system 1 of this embodiment is the cooling system 1 for the rotating electric machine 2 having a stator 21 and a rotor 22. The cooling system 1 includes the rotating electric machine 2, a pump 4 that pumps a coolant (a cooling oil), a coolant flow path 7 in which the coolant (the cooling oil) flows, a switching mechanism 3 that switches the connection states of the respective coolant flow path sections 71, 72, 73, and 74 configured in the coolant flow path 7, a coolant reserve section (an oil pan) 5 that reserves the coolant, a vehicle speed sensor 9 that detects a vehicle speed, and an electronic control unit (an ECU) 6. An oil is used as the coolant of this embodiment, and the coolant may be referred to as cooling oil for description.

[0015] The rotating electrical machine 2 includes the stator 21, the rotor 22, a housing 24 that houses the stator 21 and the rotor 22, and an outlet port 25 for the coolant (cooling oil). The stator 21 includes a core (stator core) 21A and a coil, and Fig. 1 illustrates a coil end 21B of the coil. The rotor 22 includes a core (rotor core) 22A and is attached to an output shaft 23. The output shaft 23 can also be considered part of the rotor 22. The housing 24 is a container for storing the coolant and is provided with the outlet opening 25 from which the coolant is discharged.

[0016] The pump 4 is a part that pumps the coolant to the coolant flow path 7, and in this embodiment, an example is illustrated in which an electric pump 41 driven by an electric motor 41A and a mechanical pump 42 are used together. The discharge amount of the electric pump 41 is controlled by the electronic control unit 6 according to the vehicle speed detected by the vehicle speed sensor 9. To receive a vehicle speed signal from the vehicle speed sensor 9, the electronic control unit (ECU) 6 is connected to the vehicle speed sensor 9 through a signal line E9. Furthermore, the electronic control unit (ECU) 6 is connected to the electric motor 41A through a signal line E41A to control the electric pump 41. A variable displacement pump or a fixed displacement pump is used as the mechanical pump 42.Since the discharge amount of the mechanical pump 42 is changed according to the vehicle speed, the discharge amount of the electric pump 41 is controlled by the electronic control unit 6 according to the discharge amount of the mechanical pump 42.

[0017] Since the mechanical pump 42 sucks the coolant from the rotating electric machine 2 side at the time of reverse movement (reversal) of the vehicle, an unillustrated check valve should be provided on the engine side so that the mechanical pump 42 does not suck the coolant from the rotating electric machine 2 side at the time of reversal, thereby sucking the coolant from the coolant reserve portion (oil pan) 5 through an unillustrated bypass path. In this case, the check valve should be provided in the mechanical pump 42 or between the mechanical pump 42 and the first coolant flow path portion 71. Moreover, the bypass path should be provided between the coolant reserve portion (oil pan) 5 and the first coolant flow path portion 71 so that the coolant bypasses the mechanical pump 42 at the time of reverse movement of the vehicle.It should be noted that the check valve should be provided to the bypass path so that the coolant does not leak at the time of forward movement of the vehicle.

[0018] The pump 4 may be configured using one of the electric pump 41 and the mechanical pump 42. Fig. 2 is a schematic diagram illustrating a changing example (a first changing example: Changing Example 1) of the configuration of the pump 4 of the cooling system 1 for the rotating electrical machine 2 according to the first embodiment of the present invention. In Fig. 2 illustrates an example in which the pump 4 is configured using the electric pump 41 without using the mechanical pump 42. The discharge amount of the electric pump 41 is controlled according to the vehicle speed to meet the cooling capacity.

[0019] In this embodiment, the mechanical pump 42 secures a driving force from the shaft (reduction gear shaft) of a reduction gear 101 provided between the rotating electrical machine 2 and a drive shaft 104.

[0020] That is, in this embodiment, the pump 4 includes the mechanical pump 42 and the electric pump 41, and the mechanical pump 42 secures the driving force from the shaft of the reduction gear 101 provided between the rotating electric machine 2 and the drive shaft 104.

[0021] However, the driving force of the mechanical pump 42 is not necessarily secured by the shaft (reduction gear shaft) of the reduction gear 101 and may also be secured by other sections.

[0022] Fig. 3 is a schematic diagram illustrating a changing example (a second changing example: Changing Example 2) of the drive source of the pump 4 of the cooling system 1 for the rotating electric machine 2 according to the first embodiment of the present invention. When the cooling system 1 is a system combined with a gear box 103, the driving force of the mechanical pump 42 can be secured from the output shaft 23 of the rotating electric machine 2. That is, in this example, the pump 4 includes the mechanical pump 42 and the electric pump 41, and the mechanical pump 42 secures the driving force from the output shaft 23 of the rotating electric machine 2. In this example, a reduction gear 11 is arranged between the output shaft 23 and the mechanical pump 42.

[0023] In this case, the advantage is that the coolant can be supplied according to the number of revolutions of the rotating electrical machine 2 by securing the driving force from the output shaft 23, and the cooling efficiency can be maximized. On the other hand, the disadvantage is that since the deviation between the number of revolutions of the rotating electrical machine 2 and the required number of revolutions of the mechanical pump 42 increases, the reduction gear 11 for transmitting the driving force to the mechanical pump 42 becomes larger.

[0024] Fig. 4 is a schematic diagram illustrating a changing example (a third changing example: changing example 3) of the drive source of the pump 4 of the cooling system 1 for the rotating electrical machine 2 according to the first embodiment of the present invention. When the cooling system 1 is a system combined with the transmission 103, the driving force of the mechanical pump 42 can be secured from the drive shaft 104 that drives a tire 102. That is, in this example, the pump 4 includes the mechanical pump 42 and the electric pump 41, and the mechanical pump 42 secures the driving force from the drive shaft 104. In this example, a reduction gear 12 is arranged between the drive shaft 104 and the mechanical pump 42.

[0025] In this case, the advantage is that since the driving force of the mechanical pump 42 is secured by the drive shaft 104, the reduction gear 12 for the mechanical pump 42 can be made smaller. On the other hand, since the vehicle speed and the number of revolutions of the rotating electrical machine 2 vary according to the state of the gear 103, the mechanical pump 42 is made larger to be able to secure the cooling performance under the worst conditions.

[0026] With further reference to Fig. 1, the coolant flow path 7 is described. The coolant flow path 7 includes an outlet-side coolant flow path portion 70 connected to the outlet side of the pump 4, the first coolant flow path portion 71 that supplies the coolant to the stator core 21A, the second coolant flow path portion 72 that supplies the coolant to the rotor 22, the third coolant flow path portion 73 that supplies the coolant that has cooled the stator core 21A to the coil end 21B, and the fourth coolant flow path portion 74 that supplies the coolant that has cooled the stator core 21A to the second coolant flow path portion 72.

[0027] The first coolant flow path portion 71 is a coolant flow path portion configured between a branch point P1 as the downstream end portion of the outlet-side coolant flow path portion 70 and a first valve 31. The upstream side end portion of the first coolant flow path portion 71 is connected to a downstream side end portion P1 of the outlet-side coolant flow path portion 70, and the first coolant flow path portion 71 is configured to communicate with the outlet-side coolant flow path portion 70. The downstream side end portion of the first coolant flow path portion 71 is connected to the first valve 31.

[0028] A part 71A of the first coolant flow path portion 71 is provided on the surface or inside of the stator core 21A and forms a stator core coolant portion 71A. The coolant supplied through the first coolant flow path portion 71 cools the stator core 21A, that is, the stator 21, through the stator core coolant portion 71A.

[0029] The second coolant flow path portion 72 is a coolant flow path portion configured between a second valve 32 and downstream side end portions P41, P42, P43, and P44 provided on the rotor 22. An upstream side end portion P2 of the second coolant flow path portion 72 is connected to the second valve 32. The second valve 32 is provided between the branch point P1 and a branch point P2. The second coolant flow path portion 72 is connected to the outlet-side coolant flow path portion 70 through the second valve 32 and is configured to communicate with the outlet-side coolant flow path portion 70.

[0030] A part 72A of the second coolant flow path portion 72 is provided on the output shaft 23 and inside the rotor core 22A of the rotating electrical machine 2, and forms a rotor cooling portion 72A. The coolant supplied through the second coolant flow path portion 72 cools the rotor 22, including the output shaft 23 and the rotor core 22A, through the rotor cooling portion 72A. The coolant supplied through the second coolant flow path portion 72 is supplied to the rotor cooling portion 72A to cool the rotor 22, and then, as indicated by reference numerals 81, is dropped from the downstream side end portions P41, P42, P43, and P44 of the second coolant flow path portion 72 to the coil end 21B. The coolant 81 dropped to the coil end 21B cools the coil end 21B and is accumulated in the casing 24 of the rotating electrical machine 2.The coolant accumulated in the housing 24 is collected from the outlet port 25 through a pipe not shown into the coolant reserve section 5.

[0031] The third coolant flow path portion 73 is a coolant flow path portion configured between the first valve 31 and downstream side end portions P31 and P32 provided near the stator 21. When the third coolant flow path portion 73 is connected to the first coolant flow path portion 71 through the first valve 31, the third coolant flow path portion 73 guides the coolant supplied from the first coolant flow path portion 71 to the downstream side end portions (coolant drop portions) P31 and P32, and, as indicated by reference numeral 82, drops the coolant from the downstream side end portions P31 and P32 to the spool end 21B. That is, the third coolant flow path portion 73 is provided between the first valve 31 and the coolant drop portions P31 and P32 to the spool end 21B.

[0032] The fourth coolant flow path portion 74 is a coolant flow path portion configured between the first valve 31 and the upstream side end portion (the portion corresponding to P2) of the second coolant flow path portion 72. The upstream side end portion (the portion corresponding to P2) of the second coolant flow path portion 72 configures the branch point of the coolant flow path 7, where the second coolant flow path portion 72 and the fourth coolant flow path portion 74 are connected. The downstream side end portion of the fourth coolant flow path portion 74 is connected to the upstream side end portion of the second coolant flow path portion 72 at the branch point P2.It should be noted that the branch point P2 does not necessarily have to be provided at the upstream side end portion of the second coolant flow path portion 72, and only has to be provided at the portion of the second coolant flow path portion 72 on the upstream side with respect to the rotor 22.

[0033] The switching mechanism 3 switches the connection states of the first coolant flow path portion 71, the second coolant flow path portion 72, the third coolant flow path portion 73, and the fourth coolant flow path portion 74. The switching mechanism 3 of this embodiment is configured with two valves including the first valve 31 and the second valve 32. In this case, the first valve 31 is configured with a three-way valve, and the second valve 32 is configured with an opening and closing valve. The first valve 31 and the second valve 32 of the switching mechanism 3 are controlled by the electronic control unit 6 according to the vehicle speed or the number of revolutions (speed) of the rotating electrical machine 2.

[0034] To control the first valve 31, the electronic control unit (ECU) 6 is connected to the first valve 31 via a signal line E31. To control the second valve 32, the electronic control unit (ECU) 6 is connected to the second valve 32 via a signal line E32.

[0035] Fig. 5 is an explanatory view showing the connection mode of the coolant flow path 7 of the cooling system 1 for the rotating electrical machine 2 of Fig. 1. It should be noted that Fig. 5(a) illustrates the connection mode of the coolant flow path 7 in the low speed range, Fig. 5(b) illustrates the connection mode of the coolant flow path 7 in the middle speed range and Fig. 5(c) illustrates the connection mode of the coolant flow path 7 in the high speed range.

[0036] The low speed range, the medium speed range, and the high speed range are defined as follows. The low speed range is a range in which cooling of the rotating electrical machine 2 is achieved without cooling the rotor 22. The medium speed range is a range between the low speed range and the high speed range. The high speed range is a range in which the sum of the required coolant amount of the stator 21 and the required coolant amount of the rotor 22 is equal to or greater than the coolant discharge capability limit (the upper limit of the discharge amount of the pump) from the housing 2.

[0037] In the low speed range of Fig. 5(a), the switching mechanism 3 enters a first mode in which the coolant is supplied to the first coolant flow path portion 71 and the coolant is not supplied to the second coolant flow path portion 72. In this case, the first valve 31 is driven to cause the first coolant flow path portion 71 and the third coolant flow path portion 73 to communicate with each other, and the second valve 32 is closed. By closing the second valve 32, the coolant discharge flow path portion 70 and the second coolant flow path portion 72 are shut off.

[0038] In the low speed range of Fig. 5(a), the coolant cools the stator 21 through the stator core coolant portion 71A of the first coolant flow path portion 71 and is then supplied to the third coolant flow path portion 73 through the first valve 31, thereby being cooled from the downstream side end portions P31 and P32 (see Fig. 1) of the third coolant flow path section 73 to the coil end 21B. The coolant 82 (see Fig. 1) dropped to the coil end 21B is accumulated in the casing 24 of the rotating electrical machine 2 and is collected from the outlet port 25 through the unillustrated pipe into the coolant reserve portion 5.

[0039] In the high speed range of Fig. 5(c), the switching mechanism 3 enters a second mode in which the downstream side end portion of the first coolant flow path portion 71 and the upstream side portion of the second coolant flow path portion 72 are communicated with each other with respect to the rotor 22. In this case, the first valve 31 is driven to cause the first coolant flow path portion 71 and the third coolant flow path portion 73 to communicate with each other, and the second valve 32 is closed. By closing the second valve 32, the coolant discharge flow path portion 70 and the second coolant flow path portion 72 are shut off.

[0040] In the high speed range of Fig. 5(c), the coolant cools the stator 21 through the stator core coolant portion 71A of the first coolant flow path portion 71 and is then supplied to the second coolant flow path portion 72 through the first valve 31 without being supplied to the third coolant flow path portion 73. The coolant supplied from the first coolant flow path portion 71 to the second coolant flow path portion 72 cools the rotor 72 including the output shaft 23 through the rotor cooling portion 72A. Thereafter, the coolant is supplied from the downstream side end portions P41, P42, P43, and P44 (see Fig. 1) for the second coolant flow path section 72 to the coil end 21B. The coolant 81 (see Fig. 1) dropped to the coil end 21B cools the coil end 21B and is accumulated in the casing 24 of the rotating electrical machine 2. The coolant accumulated in the casing 24 is collected from the outlet port 25 through an unillustrated pipe into the coolant reserve section 5.

[0041] In the middle speed range of Fig. 5(b) as the middle range between the low speed range of Fig. 5(a) and the high speed range of Fig. 5(c), the switching mechanism 3 enters a third mode in which the coolant is supplied to each of the first coolant flow path portion 71 and the second coolant flow path portion 72. In this case, the first valve 31 is driven to cause the first coolant flow path portion 71 and the third coolant flow path portion 73 to communicate with each other, and the second valve 32 is opened to be driven to cause the coolant discharge flow path portion 70 and the second coolant flow path portion 72 to communicate with each other.

[0042] In the middle speed range of Fig. 5(b), the coolant is supplied from the coolant discharge flow path portion 70 to each of the first coolant flow path portion 71 and the second coolant flow path portion 72. That is, the coolant supplied from the coolant discharge flow path portion 70 flows dividedly from the branch point P1 to the first coolant flow path portion 71 and the second coolant flow path portion 72.

[0043] The coolant supplied to the first coolant flow path portion 71 cools the stator 21 through the stator core coolant portion 71A and is then supplied to the third coolant flow path portion 73 through the first valve 31, thereby dropping from the third coolant flow path portion 73 to the coil end 21B. The coolant dropped to the coil end 21B is accumulated in the casing 24 of the rotating electrical machine 2 and is collected from the outlet port 25 through the pipe into the coolant reserve portion 5. This is the same as the description in the low speed range of Fig. 5(a).

[0044] The coolant supplied to the second coolant flow path section 72 cools the rotor 72 including the output shaft 23 through the rotor cooling section 72A and is then dropped to the coil end 21B. The coolant 81 (see Fig. 1) dropped to the coil end 21B cools the coil end 21B and is accumulated in the casing 24 of the rotating electrical machine 2. The coolant accumulated in the casing 24 is collected from the outlet port 25 through the pipe into the coolant reserve section 5. This is the same as the description in the high speed range of Fig. 5(c).

[0045] In the coil end 21B having a complicated configuration, the coolant having a lower viscosity extends to the details of the coil end 21B, and the thermal conductivity from the coil end 21B to the coolant is increased. In the connection mode of Fig. 5(c), since the coolant heated by the stator core 21A is dropped or sprayed to the coil end 21B, the viscosity of the coolant dropped or sprayed to the coil end 21B is reduced. Thus, the connection mode of Fig. 5(c) can also be used for other speed ranges without being limited to the high speed range, so that the thermal conductivity from the coil end 21B to the coolant can be increased to improve the cooling performance of the rotating electrical machine 2.

[0046] Next, the combination of the normally open and normally closed first valve 31 and the second valve 32 used for the switching mechanism 3 will be described.

[0047] The rotating electrical machine 2 must be thermally protected at the time of failure in the control of the first valve 31 and the second valve 32. Thus, the combination of the normally open and normally closed first valve 31 and the second valve 32 is selected to be able to ensure the cooling performance of the rotating electrical machine 2.

[0048] The connection mode of Fig. 5(b) is ideal because the first coolant flow path section 71, which supplies the coolant to the stator 21, and the second coolant flow path section 72, which supplies the coolant to the rotor 22, are connected in parallel, and the coolant can be reliably supplied to the heat generating section. Thus, both the first valve 31 and the second valve 32 are preferably normally open valves. It should be noted that Fig. 1 illustrates the state in which the normally open valves are used as the first valve 31 and the second valve 32 and the power supply is not turned on, and illustrates the state in which the first valve 31 and the second valve 32 are opened.

[0049] The cooling system 1 for the rotating electric machine 2 of this embodiment is the cooling system 1 for the rotating electric machine 2 having the stator 21 and the rotor 22. The cooling system 1 includes the coolant flow path 7 that supplies the coolant, the switching mechanism 3 that switches the mode of the coolant flow path 7, and the pump 4 that pumps the coolant to the coolant flow path 7. The coolant flow path 7 has the first coolant flow path section 71 that supplies the coolant to the core 21A of the stator 21, and the second coolant flow path section 72 that supplies the coolant to the rotor 22. The switching mechanism 3 is configured to switch the first mode ( Fig. 5(a)), in which the coolant is supplied to the first coolant flow path portion 71 and the coolant is not supplied to the second coolant flow path portion 72, and the second mode ( Fig. 5(c)), in which the downstream of the first coolant flow path portion 71 and the upstream of the second coolant flow path portion 72 are communicated with each other.

[0050] In this case, in the second mode ( Fig. 5(c)), the first coolant flow path portion 71 and the second coolant flow path portion 72 are connected in series, and the coolant that has cooled the stator 21 is supplied to the rotor 22 to cool the rotor 22.

[0051] Further, in the cooling system 1 for the rotating electric machine 2 of this embodiment, the switching mechanism 3 is configured to operate the third mode ( Fig. 5(b)) by supplying the coolant to each of the first coolant flow path portion 71 and the second coolant flow path portion 72.

[0052] In this case, in the third mode ( Fig. 5(b)), the first coolant flow path portion 71 and the second coolant flow path portion 72 are connected in parallel with respect to the rotating electric machine 2, and the coolant that cools the rotor 22 is supplied to the rotor 22 without passing through the flow path to which the coolant that cools the stator 21 is supplied.

[0053] Moreover, in the cooling system 1 for the rotating electric machine 2 of this embodiment, in the low speed range, the high speed range as a speed range higher than the low speed range, and the middle speed range between the low speed range and the high speed range included in the rotating electric machine 2, the first mode ( Fig. 5(a)) is configured in the low speed range, the second mode ( Fig. 5(c)) is configured in the high speed range and the third mode ( Fig. 5(b)) is configured in the middle speed range.

[0054] Furthermore, in the cooling system 1 for the rotating electric machine 2 of this embodiment, the coolant flow path 7 includes the third coolant flow path portion 73 in which the coolant is supplied to the coil end 21B of the stator 21, and the fourth coolant flow path portion 74 provided such that the downstream side end portion of the fourth coolant flow path portion 74 communicates with the second coolant flow path portion 72. The switching mechanism 3 includes the first valve 31 and the second valve 32.The first valve 31 is configured to be able to switch the connection mode in which the first coolant flow path portion 71 is connected to the third coolant flow path portion 73 to communicate with the third coolant flow path portion 73, and the connection mode in which the first coolant flow path portion 71 is connected to the fourth coolant flow path portion 74 to communicate with the fourth coolant flow path portion 74.The second valve 32 is arranged between the second coolant flow path portion 72 and the pump 4 and is configured to be able to switch the connection mode in which the second coolant flow path portion 72 is connected to the coolant discharge flow path 70 for the pump 4 so as not to communicate with the coolant discharge flow path 70 for the pump 4 through the first coolant flow path portion 71, and the connection mode in which the above connection is cut off in the connection mode.

[0055] Fig. 6 is a graph illustrating the relationship between the vehicle speed and the coolant supply amount in the cooling system 1 for the rotating electrical machine 2 according to the present invention.

[0056] The electric pump 41 is operated at the speed at which the sum of the coolant discharge amount of the electric pump 41 and the coolant discharge amount of the mechanical pump 42 exceeds the required coolant amount of the stator 21 and the required coolant amount of the rotor 22. That is, the discharge amount of the electric pump 41 is controlled so that the sum of the discharge amount of the electric pump 41 and the discharge amount of the mechanical pump 42 becomes the minimum required coolant amount (the required coolant amount of the stator and the required coolant amount of the rotor). In the low speed range, DC loss is dominant, and most of the losses are caused in the stator 21. By supplying coolant only to the stator 21 in the low speed range, even a small pump can ensure the required coolant amount for cooling.

[0057] In the mid-speed range, the coolant flow paths (the first coolant flow path portion 71 and the second coolant flow path portion 72) are made parallel to improve electrical efficiency. To minimize the torque loss of the mechanical pump 42 in the mid-speed range with the highest driving frequency, the switching mechanism 3 is opened and closed in the mid-speed range so that the coolant flow paths (the first coolant flow path portion 71 and the second coolant flow path portion 72) of the stator 21 and the rotor 22 are parallel. Since the pressure loss is reduced by making the coolant flow paths parallel, the loss of the mechanical pump 42 can be reduced.

[0058] In the high-speed range, the electrical efficiency is improved by hydraulically controlling the variable-displacement mechanical pump 42. In the high-speed range, the discharge amount of the mechanical pump 42 exceeds the coolant discharge capacity (the coolant discharge limit) of the housing 24, and friction is caused due to the coolant entering the gap of the rotating electrical machine 2. Accordingly, in the high-speed range, the discharge amount of the variable-displacement mechanical pump 42 is limited so that it does not exceed the coolant discharge capacity of the housing 24.At this time, when the discharge amount of the variable displacement mechanical pump 42 (≈ the coolant discharge ability of the housing 24) is less than the required coolant amount of the stator 21 and the required coolant amount of the rotor 22, the switching mechanism 3 is opened and closed so that the coolant paths (the first coolant flow path portion 71 and the second coolant flow path portion 72) of the stator 21 and the rotor 22 are in series, so that cooling is established at the discharge amount of the variable displacement mechanical pump 42 (≈ the coolant discharge ability of the housing 24).That is, by making the coolant paths (the first coolant flow path portion 71 and the second coolant flow path portion 72) of the stator 21 and the rotor 22 be in series in the high speed range, the amount of coolant required in cooling can be reduced compared to the case where the coolant paths (the first coolant flow path portion 71 and the second coolant flow path portion 72) of the stator 21 and the rotor 22 are parallel, so that the cooling performance can be achieved within the coolant outlet capability.

[0059] Fig. 7 is a schematic configuration diagram illustrating a changing example (a fourth changing example: changing example 4) of the switching mechanism 3 of the cooling system 1 for the rotating electric machine 2 according to the first embodiment of the present invention.

[0060] The switching mechanism 3 is not limited to the configuration of the first valve 31 and the first valve 32 of the first embodiment. For example, the first valve 31 illustrated in the first embodiment may be configured to be divided into two valves 311 and 312, and the switching mechanism 3 of this example is configured of three valves. That is, the first valve 31 of this example is configured of the third valve 311 and the fourth valve 312. The third valve 321 and the fourth valve 322 may be configured of opening and closing valves.

[0061] In this example, the downstream portion of the first coolant flow path portion 71 is caused to branch into two branch flow path portions 71A and 71B at a branch point P5. The first branch flow path portion 71A is connected to the third valve 311 to communicate with the third coolant flow path portion 73 through the third valve 311. The second branch flow path portion 71B is connected to the fourth valve 312 to communicate with the fourth coolant flow path portion 74 through the fourth valve 312.

[0062] That is, in the cooling system 1 for the rotating electric machine 2 of this example, the first valve 31 is configured from the two valves of the third valve 311 and the fourth valve 312. The downstream portion of the first coolant flow path portion 71 branches into the first branch flow path portion 71B connected to the third valve 311 and a second branch flow path portion 71C connected to the fourth valve. The third valve 311 is configured to open and close the connection of the first branch flow path portion 71B and the third coolant flow path portion 71C. The fourth valve 312 is configured to open and close the connection of the second branch flow path portion 71C and the second coolant flow path portion 72.

[0063] As in Fig. As illustrated in Figure 7, the electronic control unit (ECU) 6 is connected to the second valve 32 via the signal line E32 to control the second valve 32. To control the third valve 311, the electronic control unit (ECU) 6 is connected to the third valve 311 via a signal line E311. To control the fourth valve 312, the electronic control unit (ECU) 6 is connected to the fourth valve 312 via a signal line E312.

[0064] In the case of this example, in order to thermally protect the rotating electrical machine 2 at the time of failure in the control of the third valve 311, the fourth valve 312, and the second valve 32, it is preferable that the third valve 311 and the second valve 32 be normally opened and the fourth valve 312 be normally closed. It should be noted that Fig. 7 illustrates the state in which the normally open valves are used as the third valve 311 and the second valve 32, the normally closed valve is used as the fourth valve 312, and the power supply is not turned on, and illustrates the state in which the first valve 31 and the second valve 32 are open and the fourth valve 312 is closed.

[0065] All identical valves can be adopted from a cost perspective. In this case, the magnitude relationship between the respective flow path pressure losses in the normal state should be determined in order to be able to ensure the cooling capacity at the time of valve control failure. In the case of Fig. 7, for example, all of the third valve 311, the fourth valve 312 and the second valve 32 should be normally open, and the pressure loss design should be performed such that the coolant flows into the specific coolant path when all of the valves 311, 312 and 32 are open.

[0066] Fig. Figure 8 is a diagram showing the open or closed state of the valve in each speed range of the cooling system for the rotating electrical machine of Fig. 7 illustrates.

[0067] As in Fig. 8, the second valve 32, the third valve 321, and the fourth valve 322 are controlled by a control signal from the electronic control unit 6 according to the running mode (vehicle speed range), and the connection mode of the coolant flow path 7 is switched.

[0068] Fig. 9 is a schematic configuration diagram illustrating a changing example (a fifth changing example: changing example 5) of the switching mechanism 3 of the cooling system 1 for the rotating electric machine 2 according to the first embodiment of the present invention.

[0069] In the switching mechanism 3 of Fig. 7, some or all of a plurality of valves 32, 311 and 312 may be configured as an integrated unit. For example, the switching mechanism 3 of Fig. 1 an example in which the third valve 311 and the fourth valve 312 in the switching mechanism 3 of Fig. 7 are configured as an integrated unit (the first valve 31).

[0070] In Fig. 9 are all valves 32, 311 and 312 of Fig. 7 is configured as an integrated unit (the valve 3). By integrating the plurality of valves to form an integrated unit, the number of parts can be reduced, and the assembly of the cooling system 1 becomes simple.

[0071] Fig. 10 is a graph illustrating the relationship between the vehicle speed and the coolant supply amount in the case where the operating range of the electric pump 41 is changed in the cooling system 1 for the rotating electric machine 2 according to the present invention.

[0072] When the mechanical pump 42 has the remaining discharge capability as in Fig. As illustrated in Figure 10, the operating range of the electric pump 41 should be reduced to improve electrical efficiency. In this example, the operating range of the electric pump 41 is limited to the area where only the stator 21 is cooled in the low speed range.

[0073] The present invention is not limited to the above-described embodiments and further includes various modifications. For example, the above-described embodiments have been described in detail to facilitate understanding of the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Moreover, part of the configuration of one embodiment may be replaced by the configurations of other embodiments, and furthermore, the configuration of one embodiment may also be added by the configurations of other embodiments. Furthermore, part of the configuration of each of the embodiments may be subjected to addition, deletion, and replacement with respect to other configurations. List of reference symbols

[0074] 1: Cooling system for the rotating electrical machine 2, 2: rotating electrical machine, 3: switching mechanism, 4: pump, 7: coolant flow path, 21: stator, 21A: core of the stator 21 (stator core), 21B: coil end of the stator 21, 22: rotor, 23: output shaft of the rotating electrical machine 2, 31: first valve, 32: second valve, 41: electric pump, 42: mechanical pump, 70: coolant outlet flow path for the pump 4, 71: first coolant flow path section, 71B: first branch flow path section of the first coolant flow path section 71, 71C: second branch flow path section of the first coolant flow path section 71, 72: second coolant flow path section, 73: third coolant flow path section, 74: fourth coolant flow path section, 101: Reduction gear, 104: drive shaft, 311: third valve, 312: fourth valve QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-161898

[0003]

Claims

[1] Cooling system for a rotating electrical machine with a stator and a rotor, wherein the cooling system comprises: a coolant flow path that supplies a coolant; a switching mechanism that switches the mode of the coolant flow path; and a pump that pumps the coolant to the coolant flow path, wherein the coolant flow path has a first coolant flow path portion that supplies the coolant to a core of the stator and a second coolant flow path portion that supplies the coolant to the rotor, and the switching mechanism is configured to achieve a first mode in which the coolant is supplied to the first coolant flow path portion and the coolant is not supplied to the second coolant flow path portion, and a second mode in which the downstream of the first coolant flow path portion and the upstream of the second coolant flow path portion are communicated with each other. [2] The cooling system for the rotating electric machine according to claim 1, wherein in the second mode, the first coolant flow path portion and the second coolant flow path portion are connected in series, and the coolant that has cooled the stator is supplied to the rotor to cool the rotor. [3] The cooling system for the rotating electric machine according to claim 2, wherein the switching mechanism is configured to achieve a third mode in which the coolant is supplied to each of the first coolant flow path portion and the second coolant flow path portion. [4] The cooling system for the rotating electric machine according to claim 3, wherein in the third mode, the first coolant flow path portion and the second coolant flow path portion are connected in parallel with respect to the rotating electric machine, and the coolant that cools the rotor is supplied to the rotor in the flow path different from the flow path in which the coolant that cools the stator passes. [5] The cooling system for the rotating electric machine according to claim 4, wherein in the low speed range, the high speed range as a speed range higher than the low speed range, and the middle speed range between the low speed range and the high speed range of the rotating electric machine, the first mode is configured in the low speed range, the second mode is configured in the high speed range, and the third mode is configured in the middle speed range. [6] Cooling system for the rotating electric machine according to claim 5, wherein the coolant flow path includes: a third coolant flow path portion in which the coolant is supplied to a coil end of the stator; and a fourth coolant flow path portion provided such that the downstream side end portion of the fourth coolant flow path portion communicates with the second coolant flow path portion, the switching mechanism includes a first valve and a second valve, the first valve is configured to be able to switch between a connection mode in which the first coolant flow path portion is connected to the third coolant flow path portion to communicate with the third coolant flow path portion, and a connection mode in which the first coolant flow path portion is connected to the fourth coolant flow path portion to communicate with the fourth coolant flow path portion, and the second valve is arranged between the second coolant flow path portion and the pump and is configured to be capable of switching a connection mode in which the second coolant flow path portion is connected to a coolant discharge flow path for the pump so as not to communicate with the coolant discharge flow path for the pump through the first coolant flow path portion, and a connection mode in which the above connection is cut off in the connection mode. [7] The cooling system for the rotating electric machine according to claim 6, wherein the first valve is configured from two valves, a third valve and a fourth valve, the downstream portion of the first coolant flow path portion branches into a first branch flow path portion connected to the third valve and a second branch flow path portion connected to the fourth valve, the third valve is configured to open and close the connection of the first branch flow path portion and the third coolant flow path portion, and the fourth valve is configured to open and close the connection of the second branch flow path portion and the second coolant flow path portion. [8] Cooling system for the rotating electric machine according to claim 7, wherein the pump includes a mechanical pump and an electric pump, and the mechanical pump secures a driving force from the shaft of a reduction gear provided between the rotating electrical machine and a drive shaft. [9] Cooling system for the rotating electric machine according to claim 7, wherein the pump includes the mechanical pump and the electric pump, and the mechanical pump secures a driving force from an output shaft of the rotating electrical machine. [10] Cooling system for the rotating electric machine according to claim 7, wherein the pump includes the mechanical pump and the electric pump, and the mechanical pump ensures a driving force from the drive shaft.

Images