Cooling system for rotating electrical machines

Abstract

The purpose of the present invention is to provide a cooling system for a rotary electric machine in which the flow rate ratio between a coolant supplied to a stator and a coolant supplied to a rotor can be changed and the cooling effect of the rotary electric machine can be improved. This cooling system 1 for a rotary electric machine 1 according to the present invention comprises a coolant flow path 7 that supplies a coolant, a switching mechanism 3 that switches the mode of the coolant flow path 7, and a pump 4 that pumps the coolant to the coolant flow path 7. The coolant flow path 7 has a first coolant flow path section 71 that supplies the coolant to a core 21A of a stator 21, and a second coolant flow path section 72 that supplies the coolant to a rotor 22. The switching mechanism 3 is configured to achieve: a 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 a second mode which causes the downstream of the first coolant flow path section 71 and the upstream of the second coolant flow path section 72 to communicate.

Description

[Technical Field]

[0001] The present invention relates to a cooling system for a rotating electrical machine. [Background technology]

[0002] Patent Document 1 describes a cooling system for a rotating electric machine that includes refrigerant flow paths (first refrigerant flow path and sixth refrigerant flow path) that supply refrigerant to first and second coil end portions of the rotating electric machine, and a refrigerant flow path (fifth refrigerant flow path) that supply refrigerant to magnets of the rotating electric machine (paragraphs 0027, 0031, and 0032). The first and second coil end portions are provided in the stator, and the refrigerant flow paths (first refrigerant flow path and sixth refrigerant flow path) constitute a refrigerant flow path that supplies refrigerant to the stator. The magnets are provided in the rotor, and the refrigerant flow path (fifth refrigerant flow path) constitutes a refrigerant flow path that supplies refrigerant to the rotor. The fifth refrigerant flow path is branched off from the first refrigerant flow path and is configured to direct a portion of the refrigerant flowing through the first refrigerant flow path toward the magnets of the rotor (paragraph 0031). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-161898 Summary of the Invention [Problem to be solved by the invention]

[0004] In the cooling system for a rotating electrical machine disclosed in Patent Document 1, the connection state between the first refrigerant flow path and the fifth refrigerant flow path remains unchanged, and therefore the flow rate of the refrigerant supplied to the stator and the flow rate of the refrigerant supplied to the rotor change while maintaining a constant flow rate ratio depending on the flow rate of the refrigerant flowing through the first refrigerant flow path.

[0005] The object of the present invention is to provide a cooling system for a rotating electric machine that can change the flow rate ratio of the refrigerant supplied to the stator and the refrigerant supplied to the rotor, thereby improving the cooling effect of the rotating electric machine. [Means for solving the problem]

[0006] In order to achieve the above object, a cooling system for a rotating electrical machine according to the present invention comprises: A cooling system for a rotating electric machine including a stator and a rotor, a refrigerant flow path that supplies a refrigerant; a switching mechanism that switches the state of the refrigerant flow path; and a pump that pressure-feeds the refrigerant to the refrigerant flow path, the refrigerant flow path includes a first refrigerant flow path portion that supplies refrigerant to the core of the stator and a second refrigerant flow path portion that supplies refrigerant to the rotor, The switching mechanism is configured to have a first mode in which refrigerant is supplied to the first refrigerant flow path section and refrigerant is not supplied to the second refrigerant flow path section, and a second mode in which the downstream of the first refrigerant flow path section is connected to the upstream of the second refrigerant flow path section. [Effects of the Invention]

[0007] According to the present invention, the flow rate ratio of the coolant supplied to the stator and the coolant supplied to the rotor can be changed, thereby improving the cooling effect of the rotating electrical machine.

[0008] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an outline of the configuration of a first embodiment (first embodiment) of a cooling system for a rotating electrical machine according to the present invention; [Figure 2] FIG. 10 is a schematic diagram showing a modification (first modification: modification 1) of the pump configuration in the cooling system for a rotating electrical machine according to the first embodiment of the present invention. [Figure 3] FIG. 10 is a schematic diagram showing a modification (second modification: modification 2) of the drive source of the pump in the cooling system for the rotating electrical machine according to the first embodiment of the present invention. [Figure 4]FIG. 10 is a schematic diagram showing a modification (third modification: modification 3) of the drive source of the pump in the cooling system for the rotating electric machine according to the first embodiment of the present invention. [Figure 5] 2 is an explanatory diagram showing a connection state of refrigerant flow paths in the cooling system for the rotating electrical machine of FIG. 1. FIG. [Figure 6] 4 is a diagram showing the relationship between vehicle speed and the amount of refrigerant supplied in the cooling system for a rotating electrical machine according to the present invention; FIG. [Figure 7] FIG. 10 is a schematic configuration diagram showing a modification (fourth modification: modification 4) of the switching mechanism in the cooling system for the rotating electrical machine according to the first embodiment of the present invention. [Figure 8] 8 is a diagram showing the open / closed state of a valve in each speed range in the cooling system for the rotating electrical machine of FIG. 7. FIG. [Figure 9] FIG. 10 is a schematic configuration diagram showing a modification (fifth modification: modification 5) of the switching mechanism in the cooling system for the rotating electric machine according to the first embodiment of the present invention. [Figure 10] 10 is a diagram showing the relationship between vehicle speed and the amount of refrigerant supplied when the operating range of the electric pump is changed in the cooling system for the rotating electrical machine according to the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] E-Axles, which integrate a motor, inverter, and gears, are experiencing high loss densities as their power output density increases. To accommodate this high loss density, it is desirable to improve the cooling performance of rotating electrical machines using a cooling system with a direct oil-cooling structure. An oil-cooling structure requires a pump to pressurize the refrigerant (cooling oil). This pump can be, for example, a mechanical pump (mechanical oil pump) or an electric pump (electric oil pump). Note that the discharge volume of a mechanical pump changes depending on the speed, so when using a mechanical pump, it is necessary to appropriately control the refrigerant supply volume to ensure cooling performance at each speed.

[0011] In the following embodiments, an example using a mechanical pump will also be described. Mechanical pumps have a reduced discharge rate at low speeds, which reduces the cooling performance of the rotating electrical machine at low speeds. To prevent this reduction in cooling performance at low speeds, the pump must be enlarged. In the embodiments using a mechanical pump, the reduction in cooling performance of the rotating electrical machine at low speeds is suppressed, thereby avoiding the need for an enlarged pump.

[0012] In the following embodiment, torque loss in the medium speed range, which is frequently used in urban driving, is reduced, thereby improving power consumption.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0014] [Example 1] FIG. 1 is a diagram showing an outline of the configuration of a first embodiment (first embodiment) of a cooling system 1 for a rotating electrical machine 2 according to the present invention.

[0015] The cooling system 1 of this embodiment is a cooling system 1 for a rotating electric machine 2 having a stator 21 and a rotor 22, and includes the rotating electric machine 2, a pump 4 that pumps out a refrigerant (cooling oil), a refrigerant flow path 7 through which the refrigerant (cooling oil) flows, a switching mechanism 3 that switches the connection state of each refrigerant flow path section 71, 72, 73, 74 configured in the refrigerant flow path 7, a refrigerant reservoir section (oil pan) 5 that stores the refrigerant, a vehicle speed sensor 9 that detects vehicle speed, and an electronic control unit (ECU) 6. The refrigerant used in this embodiment is oil, which may be referred to as cooling oil.

[0016] The rotating electric machine 2 includes a stator 21, a rotor 22, a housing 24 that accommodates the stator 21 and the rotor 22, and a refrigerant (cooling oil) outlet 25. 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 fixed to an output shaft 23. The output shaft 23 can also be considered part of the rotor 22. The housing 24 serves as a container that stores the refrigerant and is provided with an outlet 25 that discharges the refrigerant.

[0017] The pump 4 is a component that pumps the refrigerant to the refrigerant flow path 7, and in this embodiment, an example is shown 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 an electronic control unit 6 in accordance with the vehicle speed detected by a vehicle speed sensor 9. The electronic control unit (ECU) 6 is connected to the vehicle speed sensor 9 via a signal line E9 to receive a vehicle speed signal from the vehicle speed sensor 9. The electronic control unit (ECU) 6 is also connected to the electric motor 41A via 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. Because the discharge amount of the mechanical pump 42 changes depending on the vehicle speed, the discharge amount of the electric pump 41 is controlled by the electronic control unit 6 in accordance with the discharge amount of the mechanical pump 42.

[0018] Since the mechanical pump 42 sucks refrigerant from the rotating electric machine 2 side when the vehicle is moving backward (reverse rotation), it is preferable to provide a check valve (not shown) on the motor side to prevent the mechanical pump 42 from sucking refrigerant from the rotating electric machine 2 side when the vehicle is moving backward, and to suck refrigerant from the refrigerant reservoir (oil pan) 5 via a bypass path (not shown). In this case, it is preferable to provide the check valve inside the mechanical pump 42 or between the mechanical pump 42 and the first refrigerant flow path 71. It is also preferable to provide a bypass path between the refrigerant reservoir (oil pan) 5 and the first refrigerant flow path 71 so that the refrigerant bypasses the mechanical pump 42 when the vehicle is moving backward. It is also preferable to provide a check valve in the bypass path to prevent refrigerant leakage when the vehicle is moving forward.

[0019] The pump 4 may be configured using either an electric pump 41 or a mechanical pump 42. Fig. 2 is a schematic diagram showing a modified example (first modified example: modified example 1) of the configuration of the pump 4 in the cooling system 1 for the rotating electric machine 2 according to the first embodiment of the present invention. Fig. 2 shows an example in which the pump 4 is configured using an electric pump 41 without using a mechanical pump 42. The discharge rate of the electric pump 41 is controlled in accordance with the vehicle speed so as to satisfy the cooling performance.

[0020] In this embodiment, the mechanical pump 42 obtains power from the shaft (reduction gear shaft) of the reduction gear 101 provided between the rotating electric machine 2 and the drive shaft 104 .

[0021] That is, in this embodiment, the pump 4 includes a mechanical pump 42 and an electric pump 41 , and the mechanical pump 42 obtains power from the shaft of a reducer 101 provided between the rotating electrical machine 2 and a drive shaft 104 . However, the power of the mechanical pump 42 is not limited to the shaft of the reducer 101 (reduction gear shaft), and can also be secured from other parts.

[0022] 3 is a schematic diagram showing a modification (second modification: modification 2) of the drive source of the pump 4 in the cooling system 1 for the rotating electric machine 2 according to the first embodiment of the present invention. In the case of a system combined with a transmission 103, the mechanical pump 42 may be powered by the output shaft 23 of the rotating electric machine 2. That is, in this example, the pump 4 includes the mechanical pump 42 and an electric pump 41, and the mechanical pump 42 obtains power from the output shaft 23 of the rotating electric machine 2. In this example, a reducer 11 is arranged between the output shaft 23 and the mechanical pump 42.

[0023] The advantage of this case is that by securing power from the output shaft 23, it is possible to supply a refrigerant according to the rotation speed of the rotating electric machine 2, thereby maximizing cooling performance. On the other hand, the disadvantage is that the difference between the rotation speed of the rotating electric machine 2 and the required rotation speed of the mechanical pump 42 becomes large, so the reducer 11 for transmitting power to the mechanical pump 42 becomes large.

[0024] 4 is a schematic diagram showing a modification (third modification: modification 3) of the drive source of the pump 4 in the cooling system 1 for the rotating electric machine 2 according to the first embodiment of the present invention. In the case of a system combined with a transmission 103, the mechanical pump 42 may be powered by a drive shaft 104 that drives a tire 102. That is, in this example, the pump 4 includes a mechanical pump 42 and an electric pump 41, and the mechanical pump 42 obtains power from the drive shaft 104. In this example, a reducer 12 is arranged between the drive shaft 104 and the mechanical pump 42.

[0025] The advantage of this case is that the reducer 12 for the mechanical pump 42 can be made smaller because the power of the mechanical pump 42 is secured from the drive shaft 104. On the other hand, the disadvantage is that the vehicle speed and the rotation speed of the rotating electric machine 2 differ depending on the state of the transmission 103, so the mechanical pump 42 must be made larger in order to ensure cooling performance under the worst conditions.

[0026] 1, the refrigerant flow path 7 will now be described. The refrigerant flow path 7 includes a discharge-side refrigerant flow path section 70 connected to the discharge side of the pump 4, a first refrigerant flow path section 71 that supplies refrigerant to the stator core 21A, a second refrigerant flow path section 72 that supplies refrigerant to the rotor 22, a third refrigerant flow path section 73 that supplies the refrigerant that has cooled the stator core 21A to the coil ends 21B, and a fourth refrigerant flow path section 74 that supplies the refrigerant that has cooled the stator core 21A to the second refrigerant flow path section 72.

[0027] The first refrigerant channel section 71 is a refrigerant channel section configured between a branch point P1, which is the downstream end of the discharge-side refrigerant channel section 70, and the first valve 31. The upstream end of the first refrigerant channel section 71 is connected to the downstream end P1 of the discharge-side refrigerant channel section 70, and the first refrigerant channel section 71 is configured to communicate with the discharge-side refrigerant channel section 70. The downstream end of the first refrigerant channel section 71 is connected to the first valve 31.

[0028] A part 71A of the first refrigerant flow path portion 71 is provided on the surface of or inside the stator core 21A and constitutes a stator core cooling portion 71A. The refrigerant supplied by the first refrigerant flow path portion 71 cools the stator core 21A, i.e., the stator 21, in the stator core cooling portion 71A.

[0029] The second refrigerant channel section 72 is a refrigerant channel section configured between the second valve 32 and downstream end sections P41, 42, 43, and 44 provided on the rotor 22. The upstream end section P2 of the second refrigerant channel section 72 is connected to the second valve 32. The second valve 32 is provided between the branch point P1 and the branch point P2. The second refrigerant channel section 72 is connected to the discharge-side refrigerant channel section 70 via the second valve 32, and is configured to communicate with the discharge-side refrigerant channel section 70.

[0030] A portion 72A of the second refrigerant flow path section 72 is provided inside the output shaft 23 and rotor core 22A of the rotating electric machine 2 and forms a rotor cooling section 72A. The refrigerant supplied by the second refrigerant flow path section 72 cools the rotor 22, including the output shaft 23 and rotor core 22A, in the rotor cooling section 72A. The refrigerant supplied by the second refrigerant flow path section 72 is supplied to the rotor cooling section 72A to cool the rotor 22, and then drips from downstream ends P41, 42, 43, and 44 of the second refrigerant flow path section 72 onto the coil end 21B, as indicated by reference numeral 81. The refrigerant 81 dripping onto the coil end 21B cools the coil end 21B and accumulates in the housing 24 of the rotating electric machine 2. The refrigerant accumulated in the housing 24 is collected from the discharge port 25 into the refrigerant reservoir 5 through piping (not shown).

[0031] The third refrigerant flow path section 73 is a refrigerant flow path section configured between the first valve 31 and downstream ends P31, P32 provided near the stator 21. When the third refrigerant flow path section 73 is connected to the first refrigerant flow path section 71 via the first valve 31, the third refrigerant flow path section 73 guides the refrigerant supplied from the first refrigerant flow path section 71 to the downstream ends (refrigerant drip portions) P31, P32, and drips from the downstream ends P31, P32 onto the coil ends 21B, as indicated by the reference numeral 82. In other words, the third refrigerant flow path section 73 is provided between the first valve 31 and the refrigerant drip portions P31, P32 toward the coil ends 21B.

[0032] The fourth refrigerant channel section 74 is a refrigerant channel section configured between the first valve 31 and the upstream end (portion corresponding to P2) of the second refrigerant channel section 72. The upstream end (portion corresponding to P2) of the second refrigerant channel section 72 forms a branch point of the refrigerant channel 7 where the second refrigerant channel section 72 and the fourth refrigerant channel section 74 are connected. The downstream end of the fourth refrigerant channel section 74 is connected to the upstream end of the second refrigerant channel section 72 at branch point P2. Note that branch point P2 does not need to be provided at the upstream end of the second refrigerant channel section 72, and may be provided in a portion of the second refrigerant channel section 72 upstream of the rotor 22.

[0033] The switching mechanism 3 switches the connection states of the first refrigerant flow path section 71, the second refrigerant flow path section 72, the third refrigerant flow path section 73, and the fourth refrigerant flow path section 74. The switching mechanism 3 in this embodiment is composed of two valves, including a first valve 31 and a second valve 32. In this case, the first valve 31 is composed of a three-port valve, and the second valve 32 is composed of an opening / closing valve. The opening and closing of the first valve 31 and the second valve 32 of the switching mechanism 3 is controlled by the electronic control device 6 in accordance with the vehicle speed or the rotational speed (rotational speed) of the rotating electric machine 2.

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

[0035] Fig. 5 is an explanatory diagram showing the connection state of the refrigerant flow passages 7 in the cooling system 1 of the rotating electric machine 2 of Fig. 1. In Fig. 5, (a) shows the connection state of the refrigerant flow passages 7 in the low speed range, (b) shows the connection state of the refrigerant flow passages 7 in the medium speed range, and (c) shows the connection state of the refrigerant flow passages 7 in the high speed range.

[0036] The low-speed range, medium-speed range, and high-speed range are defined as follows: The low-speed range is a range in which the rotating electrical machine 2 can be cooled 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 total amount of refrigerant required for the stator 21 and rotor 22 is equal to or greater than the limit of the refrigerant discharge capacity from the housing 2 (upper limit of the pump discharge amount).

[0037] In the low speed range (a), the switching mechanism 3 realizes a first mode in which refrigerant is supplied to the first refrigerant channel section 71 but not to the second refrigerant channel section 72. In this case, the first valve 31 is driven to connect the first refrigerant channel section 71 and the third refrigerant channel section 73, and the second valve 32 is closed. By closing the second valve 32, the refrigerant discharge channel section 70 and the second refrigerant channel section 72 are blocked from each other.

[0038] In the low-speed range of (a), the refrigerant cools the stator 21 in the stator core cooling section 71A of the first refrigerant flow path section 71, and then is supplied to the third refrigerant flow path section 73 via the first valve 31, and drips from downstream ends P31, P32 (see FIG. 1) of the third refrigerant flow path section 73 onto the coil ends 21B. The refrigerant 82 (see FIG. 1) that drips onto the coil ends 21B accumulates in the housing 24 of the rotating electrical machine 2 and is collected in the refrigerant reservoir 5 from the discharge port 25 through a pipe (not shown).

[0039] In the high speed range (c), the switching mechanism 3 realizes a second mode in which the downstream end of the first refrigerant channel section 71 communicates with the portion of the second refrigerant channel section 72 upstream of the rotor 22. In this case, the first valve 31 is driven to communicate the first refrigerant channel section 71 with the third refrigerant channel section 73, and the second valve 32 is closed. By closing the second valve 32, the refrigerant discharge channel section 70 is blocked from the second refrigerant channel section 72.

[0040] In the high-speed range (c), the refrigerant cools the stator 21 in the stator core cooling section 71A of the first refrigerant flow path section 71, and then is supplied to the second refrigerant flow path section 72 via the first valve 31 without being supplied to the third refrigerant flow path section 73. The refrigerant supplied from the first refrigerant flow path section 71 to the second refrigerant flow path section 72 cools the rotor 72, including the output shaft 23, in the rotor cooling section 72A. The refrigerant then drips from downstream ends P41, 42, 43, and 44 (see FIG. 1) of the second refrigerant flow path section 72 onto the coil end 21B. The refrigerant 81 (see FIG. 1) dripped onto the coil end 21B cools the coil end 21B and accumulates in the housing 24 of the rotating electrical machine 2. The refrigerant accumulated in the housing 24 is collected in the refrigerant reservoir 5 from the outlet 25 through a pipe (not shown).

[0041] In the medium speed range (b), which is an intermediate range between the low speed range (a) and the high speed range (c), the switching mechanism 3 realizes a third mode in which the refrigerant is supplied to each of the first refrigerant channel section 71 and the second refrigerant channel section 72. In this case, the first valve 31 is driven to connect the first refrigerant channel section 71 and the third refrigerant channel section 73, and the second valve 32 is opened and driven to connect the refrigerant discharge channel section 70 and the second refrigerant channel section 72.

[0042] In the medium speed range (b), the refrigerant is supplied from the refrigerant discharge channel section 70 to each of the first refrigerant channel section 71 and the second refrigerant channel section 72. That is, the refrigerant supplied from the refrigerant discharge channel section 70 branches into the first refrigerant channel section 71 and the second refrigerant channel section 72 from the branch point P1.

[0043] The coolant supplied to the first coolant flow path 71 cools the stator 21 in the stator core cooling section 71A, and is then supplied to the third coolant flow path 73 via the first valve 31, and drips from the third coolant flow path 73 onto the coil ends 21B. The coolant that drips onto the coil ends 21B accumulates in the housing 24 of the rotating electrical machine 2, and is collected in the coolant reservoir 5 through the piping from the outlet 25. This is the same as the explanation for the low speed range in (a).

[0044] The refrigerant supplied to the second refrigerant flow path section 72 cools the rotor 72, including the output shaft 23, in the rotor cooling section 72A, and then drips onto the coil ends 21B. The refrigerant 81 (see FIG. 1) dripped onto the coil ends 21B cools the coil ends 21B and accumulates in the housing 24 of the rotating electrical machine 2. The refrigerant accumulated inside the housing 24 is collected in the refrigerant reservoir section 5 through the piping from the outlet 25. This is the same as the explanation for the high speed range in (c).

[0045] In the coil ends 21B, which have a complex structure, a coolant with a lower viscosity will reach every detail of the coil ends 21B and increase the coefficient of heat transfer from the coil ends 21B to the coolant. In the connection configuration shown in Figure 5(c), the coolant heated by the stator core 21A is dripped or sprayed onto the coil ends 21B, so the viscosity of the coolant dripping or sprayed onto the coil ends 21B is lower. Therefore, by using the connection configuration shown in Figure 5(c) not only in the high-speed range but also in other speed ranges, the coefficient of heat transfer from the coil ends 21B to the coolant can be increased, thereby improving the cooling performance of the rotating electric machine 2.

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

[0047] The rotating electrical machine 2 needs to be thermally protected in the event of a control failure of the first valve 31 and the second valve 32. For this reason, a combination of normally open or normally closed first valve 31 and the second valve 32 is selected so as to ensure the cooling performance of the rotating electrical machine 2.

[0048] The connection configuration shown in Figure 5(b) is ideal because it connects the first refrigerant flow path section 71, which supplies refrigerant to the stator 21, and the second refrigerant flow path section 72, which supplies refrigerant to the rotor 22, in parallel, ensuring that refrigerant is supplied to the heat-generating section. For this reason, it is preferable that both the first valve 31 and the second valve 32 be normally open valves. Note that Figure 1 illustrates a state in which the first valve 31 and the second valve 32 are normally open valves and are not turned on, and shows a state in which the first valve 31 and the second valve 32 are open.

[0049] The cooling system 1 for the rotating electrical machine 2 of this embodiment includes: A cooling system 1 for a rotating electric machine 2 including a stator 21 and a rotor 22, The cooling device includes a refrigerant flow path 7 for supplying a refrigerant, a switching mechanism 3 for switching the state of the refrigerant flow path 7, and a pump 4 for pressure-feeding the refrigerant to the refrigerant flow path 7, The refrigerant flow path 7 has a first refrigerant flow path portion 71 that supplies the refrigerant to the core 21A of the stator 21, and a second refrigerant flow path portion 72 that supplies the refrigerant to the rotor 22, The switching mechanism 3 is configured to have a first state (Figure 5(a)) in which refrigerant is supplied to the first refrigerant flow path section 71 but not to the second refrigerant flow path section 72, and a second state (Figure 5(c)) in which the downstream of the first refrigerant flow path section 71 is connected to the upstream of the second refrigerant flow path section 72.

[0050] In this case, in the second embodiment (Figure 5(c)), the first refrigerant flow path section 71 and the second refrigerant flow path section 72 are connected in series, and the refrigerant after cooling the stator 21 is supplied to the rotor 22 to cool the rotor 22.

[0051] Furthermore, in the cooling system 1 for the rotating electrical machine 2 of this embodiment, The switching mechanism 3 is configured to achieve a third mode (FIG. 5(b)) in which the refrigerant is supplied to each of the first refrigerant channel portion 71 and the second refrigerant channel portion 72.

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

[0053] In addition, in the cooling system 1 for the rotating electrical machine 2 of this embodiment, In the low speed region of the rotating electric machine 2, the high speed region which is a speed region higher than the low speed region, and the medium speed region between the low speed region and the high speed region, 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 medium speed range.

[0054] In addition, in the cooling system 1 for the rotating electrical machine 2 of this embodiment, The refrigerant flow path 7 includes a third refrigerant flow path portion 73 that supplies refrigerant to the coil end 21B of the stator 21, and a fourth refrigerant flow path portion 74 that has a downstream end portion that communicates with the second refrigerant flow path portion 72, The switching mechanism 3 includes a first valve 31 and a second valve 32. the first valve 31 is configured to be switchable between a connection mode in which the first refrigerant flow path portion 71 is connected to communicate with the third refrigerant flow path portion 73 and a connection mode in which the first refrigerant flow path portion 71 is connected to communicate with the fourth refrigerant flow path portion 74; The second valve 32 is arranged between the second refrigerant flow path section 72 and the pump 4, and is configured to be switchable between a connection mode in which the second refrigerant flow path section 72 is connected to the refrigerant discharge flow path 70 of the pump 4 without going through the first refrigerant flow path section 71, and a connection mode in which the connection in this connection mode is cut off.

[0055] FIG. 6 is a diagram showing the relationship between the vehicle speed and the amount of refrigerant supplied in the cooling system 1 for the rotating electrical machine 2 according to the present invention.

[0056] The electric pump 41 is operated at a speed where the combined refrigerant discharge rate with the mechanical pump 42 exceeds the amount of refrigerant required by the stator 21 and rotor 22. In other words, the discharge rate of the electric pump 41 is controlled so that the total discharge rate of the electric pump 41 and the mechanical pump 42 is the minimum amount of refrigerant required (amount of refrigerant required by the stator + rotor). In the low-speed range, DC loss is dominant, and most of the loss occurs in the stator 21. By supplying refrigerant only to the stator 21 in the low-speed range, it is possible to ensure the amount of refrigerant required for cooling even with a small pump.

[0057] In the medium speed range, the refrigerant flow paths (first refrigerant flow path portion 71 and second refrigerant flow path portion 72) are arranged in parallel to improve power efficiency. In order to minimize torque loss in the mechanical pump 42 in the medium speed range, which is the range where driving is most frequent, the switching mechanism 3 is opened and closed so that the refrigerant flow paths (first refrigerant flow path portion 71 and second refrigerant flow path portion 72) of the stator 21 and rotor 22 are arranged in parallel in the medium speed range. By arranging the refrigerant flow paths in parallel, pressure loss is reduced, and therefore loss in the mechanical pump 42 can be reduced.

[0058] At high speeds, the hydraulic control of the variable displacement mechanical pump 42 improves power efficiency. At high speeds, the discharge rate of the mechanical pump 42 exceeds the refrigerant discharge capacity (refrigerant discharge limit) of the housing 24, causing friction due to the refrigerant entering the gaps of the rotating electrical machine 2. Therefore, at high speeds, the discharge rate of the variable displacement mechanical pump 42 is limited so as not to exceed the refrigerant discharge capacity of the housing 24. At this time, if the discharge rate of the variable displacement mechanical pump 42 (≈ refrigerant discharge capacity of the housing 24) is less than the amount of refrigerant required for the stator 21 and the rotor 22, the switching mechanism 3 is opened and closed so that the refrigerant flow paths (first refrigerant flow path portion 71 and second refrigerant flow path portion 72) between the stator 21 and the rotor 22 are in series, thereby achieving cooling at the discharge rate of the variable displacement mechanical pump 42 (≈ refrigerant discharge capacity of the housing 24). In other words, in the high-speed range, by connecting the refrigerant flow paths (first refrigerant flow path section 71 and second refrigerant flow path section 72) of the stator 21 and rotor 22 in series, the amount of refrigerant required for cooling can be reduced compared to when they are connected in parallel, and cooling performance can be achieved within the refrigerant discharge capacity.

[0059] FIG. 7 is a schematic configuration diagram showing a modification (fourth modification: modification 4) of the switching mechanism 3 in the cooling system 1 for the rotating electrical 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 shown in the first embodiment can be configured as two valves 311 and 312, and the switching mechanism 3 of this embodiment is configured as three valves. That is, the first valve 31 of this embodiment is configured as a third valve 311 and a fourth valve 312. The third valve 321 and the fourth valve 322 can be configured as open / close valves.

[0061] In this example, the downstream portion of first refrigerant channel portion 71 branches into two branch channel portions 71A and 71B at branch point P5. First branch channel portion 71A is connected to third valve 311 so as to communicate with third refrigerant channel portion 73 via third valve 311. Second branch channel portion 71B is connected to fourth valve 312 so as to communicate with fourth refrigerant channel portion 74 via fourth valve 312.

[0062] That is, the cooling system 1 for the rotating electrical machine 2 in this example is as follows: The first valve 31 is composed of two valves, a third valve 311 and a fourth valve 312. The first refrigerant flow path portion 71 is branched at its downstream portion into a 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 between the first branch flow path portion 71B and the third refrigerant flow path portion 73, The fourth valve 312 is configured to open and close the connection between the second branch channel portion 71C and the second refrigerant channel portion 72.

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

[0064] In this example, it is preferable that the third valve 311 and the second valve 32 are normally open and the fourth valve 312 is normally closed in order to thermally protect the rotating electric machine 2 in the event of a control failure of the third valve 311, the fourth valve 312, and the second valve 32. Note that Fig. 7 illustrates a state in which normally open valves are used for the third valve 311 and the second valve 32, and a normally closed valve is used for the fourth valve 312, with the power turned off, and also illustrates a state in which the first valve 31 and the second valve 32 are open, and the fourth valve 312 is closed.

[0065] From a cost perspective, it may be possible to use the same valves for all of the components. In this case, it is advisable to determine the magnitude relationship of the pressure loss in each flow path under normal conditions so that cooling performance can be ensured even if valve control fails. In the case of Figure 7, for example, it is advisable to set the third valve 311, the fourth valve 312, and the second valve 32 to be normally open, and to design the pressure loss so that the refrigerant flows through a specific refrigerant path when all valves 311, 312, and 32 are open.

[0066] FIG. 8 is a diagram showing the open / closed states of the valves in each speed range in the cooling system for the rotating electrical machine of FIG.

[0067] As shown in FIG. 8, the second valve 32, the third valve 321 and the fourth valve 322 are controlled by control signals from the electronic control device 6 according to the driving mode (vehicle speed range), and the connection state of the refrigerant flow path 7 is switched.

[0068] FIG. 9 is a schematic configuration diagram showing a modification (fifth modification: modification 5) of the switching mechanism 3 in the cooling system 1 for the rotating electrical machine 2 according to the first embodiment of the present invention.

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

[0070] In Fig. 9, all of the valves 32, 311, and 312 in Fig. 7 are configured as an integrated unit (valve section 3). By combining multiple valves into an integrated unit, the number of parts can be reduced, making it easier to assemble the cooling system 1.

[0071] FIG. 10 is a diagram showing the relationship between the vehicle speed and the amount of refrigerant supplied when the operating range of the electric pump 41 is changed in the cooling system 1 for the rotating electrical machine 2 according to the present invention.

[0072] If the discharge capacity of the mechanical pump 42 is sufficient, it is preferable to reduce the operating range of the electric pump 41 to improve the electricity consumption, as shown in Fig. 10. In this example, the operating range of the electric pump 41 is limited to a range in which only the stator 21 is cooled in the low speed range.

[0073] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0074] 1...cooling system for rotating electric machine 2, 2...rotating electric machine, 3...switching mechanism, 4...pump, 7...refrigerant flow path, 21...stator, 21A...core of stator 21 (stator core), 21B...coil end of stator 21, 22...rotor, 23...output shaft of rotating electric machine 2, 31...first valve, 32...second valve, 41...electric pump, 42...mechanical pump, 70...refrigerant discharge flow path of pump 4, 71...first refrigerant flow path section, 71B...first branch flow path section of first refrigerant flow path section 71, 71C...second branch flow path section of first refrigerant flow path section 71, 72...second refrigerant flow path section, 73...third refrigerant flow path section, 74...fourth refrigerant flow path section, 101...reduction gear, 104...drive shaft, 311...third valve, 312...fourth valve.

Claims

1. A cooling system for a rotating electric machine including a stator and a rotor, a refrigerant flow path that supplies a refrigerant; a switching mechanism that switches the state of the refrigerant flow path; and a pump that pressure-feeds the refrigerant to the refrigerant flow path, the refrigerant flow path includes a first refrigerant flow path portion that supplies refrigerant to the core of the stator and a second refrigerant flow path portion that supplies refrigerant to the rotor, The cooling system for a rotating electric machine is configured so that the switching mechanism has a first mode in which refrigerant is supplied to the first refrigerant flow path portion and not supplied to the second refrigerant flow path portion, and a second mode in which the downstream of the first refrigerant flow path portion is connected to the upstream of the second refrigerant flow path portion.

2. 2. The cooling system for a rotating electrical machine according to claim 1, In the second aspect, the first refrigerant flow path section and the second refrigerant flow path section are connected in series, and the refrigerant that has cooled the stator is supplied to the rotor to cool the rotor.

3. 3. The cooling system for a rotating electrical machine according to claim 2, The cooling system for a rotating electric machine is configured to achieve a third mode in which the switching mechanism supplies refrigerant to both the first refrigerant flow path portion and the second refrigerant flow path portion.

4. 4. The cooling system for a rotating electrical machine according to claim 3, In the third aspect, the first refrigerant flow path section and the second refrigerant flow path section are connected in parallel to the rotating electric machine, and the refrigerant that cools the rotor is supplied to the rotor through a flow path different from the flow path through which the refrigerant that cools the stator passes.

5. 5. The cooling system for a rotating electrical machine according to claim 4, In a low speed range of the rotating electric machine, a high speed range that is a speed range higher than the low speed range, and a medium speed range between the low speed range and the high speed range, The cooling system for a rotating electric machine according to the first aspect is configured in the low speed range, the second aspect is configured in the high speed range, and the third aspect is configured in the medium speed range.

6. 6. The cooling system for a rotating electrical machine according to claim 5, the refrigerant flow path includes a third refrigerant flow path portion that supplies refrigerant to the coil ends of the stator, and a fourth refrigerant flow path portion that is provided such that a downstream end thereof communicates with the second refrigerant flow path portion, the switching mechanism includes a first valve and a second valve; the first valve is configured to be switchable between a connection mode in which the first refrigerant flow path portion is connected to communicate with the third refrigerant flow path portion and a connection mode in which the first refrigerant flow path portion is connected to communicate with the fourth refrigerant flow path portion, The second valve is disposed between the second refrigerant flow path portion and the pump, and is configured to be switchable between a connection mode in which the second refrigerant flow path portion is connected to the refrigerant discharge flow path of the pump without going through the first refrigerant flow path portion, and a connection mode in which the connection is interrupted.

7. 7. The cooling system for a rotating electrical machine according to claim 6, The first valve is composed of two valves, a third valve and a fourth valve, a downstream portion of the first refrigerant flow path portion branches into a first branch flow path portion connected to a third valve and a second branch flow path portion connected to a fourth valve; the third valve is configured to open and close the connection between the first branch flow path portion and the third refrigerant flow path portion, The fourth valve is configured to open and close the connection between the second branch flow path portion and the second refrigerant flow path portion.

8. 8. The cooling system for a rotating electrical machine according to claim 7, The pump includes a mechanical pump and an electric pump, The mechanical pump is a cooling system for a rotating electric machine that secures power from the shaft of a reducer that is provided between the rotating electric machine and a drive shaft.

9. 8. The cooling system for a rotating electrical machine according to claim 7, The pump includes a mechanical pump and an electric pump, The mechanical pump is a cooling system for a rotating electric machine that secures power from the output shaft of the rotating electric machine.

10. 8. The cooling system for a rotating electrical machine according to claim 7, The pump includes a mechanical pump and an electric pump, The mechanical pump is a cooling system for a rotating electrical machine that obtains power from the drive shaft.

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