Motor cooling device

Abstract

To provide a cooling device of an electric motor which can evenly cool the whole stator and contribute to continuous driving.SOLUTION: A stator core 5 of a cooling apparatus 1 comprises: a cylindrical back yoke 7; a plurality of teeth 8 projecting in a radial direction from the back yoke 7; a plurality of slots 9 formed between the teeth 8 adjacent to each other in a circumferential direction; cooling paths 12 provided in the circumferential direction so as not to communicate with the slots 9 in the back yoke 7 and in which coolant flows; and coolant supply ports 16 formed in the back yoke 7 to supply the coolant to the cooling paths 12. The cooling paths 12 are constituted by being divided into at least two in the circumferential direction and the coolant supply ports 16 are formed for every cooling path 12.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cooling device for an electric motor. [Background technology]

[0002] An electric motor comprises a stator around which a coil is wound and a rotor that is rotatable relative to the stator. When current is applied to the coil, a predetermined interlinkage magnetic flux is formed in the stator, causing the rotor to rotate continuously. Because the stator generates heat due to the current resistance of the coil, various techniques have been proposed for cooling the stator.

[0003] For example, a technology has been disclosed that includes a cylindrical housing that houses a stator on its inner periphery and a cover that covers the outer periphery of the housing and has a refrigerant inlet and outlet. The housing is formed with a first flow groove that communicates with the inlet and a second flow groove that communicates with the outlet. Each flow groove is formed in an annular shape. With this configuration, the refrigerant supplied to the inlet first flows around the outer periphery of the housing via the first flow channel, then flows to the second flow channel.The refrigerant then flows around the outer periphery of the housing via the second flow channel, and then is discharged from the outlet.This cools the entire outer periphery of the stator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-4658 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above-mentioned conventional technology, the more downstream the refrigerant is, the more it is heated by the stator between the inlet and the outlet. This reduces the cooling efficiency near the downstream of the stator, which limits the continuous operation of the motor.

[0006] SUMMARY OF THE INVENTION The present invention provides a cooling device for an electric motor that can cool the entire stator evenly and contribute to continuous driving. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. (1) A cooling device for an electric motor according to the present invention (for example, cooling device 1 in the embodiment) is a cooling device for an electric motor (for example, electric motor 2 in the embodiment) having a stator (for example, stator 3 in the embodiment), the stator including a stator core (for example, stator core 5 in the embodiment) and a coil (for example, coil 6 in the embodiment) wound around the stator core, and the stator core includes a cylindrical back yoke (for example, back yoke 7 in the embodiment) and a plurality of teeth (for example, teeth 1 in the embodiment) protruding radially from the back yoke. The back yoke includes a plurality of slots (e.g., slots 8 in the embodiment) formed between adjacent teeth in the circumferential direction, a cooling path (e.g., cooling path 12 in the embodiment) provided in the back yoke along the circumferential direction so as not to communicate with the slots and through which a refrigerant flows, and a refrigerant supply port (e.g., refrigerant supply port 16 in the embodiment) formed in the back yoke for supplying the refrigerant to the cooling path, wherein the cooling path is divided into at least two in the circumferential direction, and the refrigerant supply port is formed for each cooling path.

[0008] This configuration allows the refrigerant to be supplied separately to the cooling passages divided in the circumferential direction of the stator core, thereby allowing the entire stator to be cooled evenly, contributing to continuous driving of the electric motor.

[0009] (2) In the above configuration, the stator core has a fastening portion (e.g., fastening portion 14 in the embodiment) for fixing the stator core to a fixed body (e.g., vehicle body 101 in the embodiment), the fastening portion has a bolt insertion hole (e.g., bolt insertion hole 10 in the embodiment) through which a bolt (e.g., bolt 11 in the embodiment) for fixing to the fixed body is inserted, and the refrigerant supply port may be connected to the bolt insertion hole.

[0010] This configuration allows the coolant to be supplied to the cooling passage through the coolant supply port using the bolt insertion holes, reducing the cost of manufacturing the coolant supply port and minimizing the impact of forming the coolant supply port on the back yoke.

[0011] (3) In the above configuration, the device may include a pump (e.g., pump 17 in the embodiment) that supplies the refrigerant to each of the refrigerant supply ports, a flow rate control device (e.g., control valve 20 in the embodiment) that controls the flow rate of the refrigerant supplied from the pump to each of the refrigerant supply ports, a temperature detection unit (e.g., temperature sensor 21 in the embodiment) that detects the temperature of the stator, and a control unit (e.g., control unit 22 in the embodiment) that controls the flow rate control device based on the temperature detected by the temperature detection unit and controls the flow rate of the refrigerant supplied to the refrigerant supply ports.

[0012] This configuration allows the flow rate of the refrigerant in each cooling passage to be controlled according to the temperature of the stator, thereby allowing the entire stator to be cooled more evenly, which contributes to the continuous operation of the motor.

[0013] (4) In the above configuration, the stator may be fixed to a vehicle body (e.g., vehicle body 101 in the embodiment) so that its central axis (e.g., central axis A in the embodiment) is aligned with the vehicle width direction, and may include a pump that supplies the refrigerant to each of the refrigerant supply ports, a flow control device that controls the flow rate of the refrigerant supplied from the pump to each of the refrigerant supply ports, a tilt detection unit (e.g., tilt sensor 30 in the embodiment) that detects the tilt of the vehicle body, and a control unit that controls the flow control device based on the tilt detected by the tilt detection unit and controls the flow rate of the refrigerant supplied to the refrigerant supply ports.

[0014] This configuration allows the flow rate of the refrigerant in each cooling passage to be controlled according to the tilt of the vehicle body, so the entire stator can be cooled evenly even if the position of the stator changes, contributing to continuous driving of the electric motor. [Effects of the Invention]

[0015] According to the cooling device for an electric motor of the present invention, the entire stator can be cooled evenly, which contributes to the continuous operation of the electric motor. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a side view of a vehicle according to an embodiment of the present invention, viewed from the vehicle width direction. [Figure 2] 1 is a schematic configuration diagram of a cooling device according to an embodiment of the present invention. [Figure 3] FIG. 2 is an enlarged perspective view of a portion of the stator according to the embodiment of the present invention. [Figure 4] FIG. 2 is a partial cross-sectional view of a stator according to an embodiment of the present invention. [Figure 5] 4 is a flowchart illustrating a case where drive control of each valve is performed in the embodiment of the present invention. [Figure 6] 5 is a flowchart illustrating a case where drive control of each valve is performed using a torque sensor according to an embodiment of the present invention. [Figure 7] FIG. 10 is a schematic configuration diagram showing a modified example of the cooling device according to the embodiment of the present invention. [Figure 8]4 is a flowchart illustrating a case where drive control of each valve is performed using a tilt sensor according to an embodiment of the present invention. [Figure 9] FIG. 10 is a perspective view showing a modified example of the refrigerant supply port in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Next, an embodiment of the present invention will be described with reference to the drawings.

[0018] <Vehicle> Fig. 1 is a side view of a vehicle 100 equipped with a cooling device 1 according to the present invention, as viewed from the vehicle width direction. Fig. 2 is a schematic configuration diagram of the cooling device 1. 1 and 2, a vehicle 100 includes a vehicle body 101 and a cooling device 1 that cools an electric motor 2 mounted on the vehicle body 101. In this embodiment, the cooling device 1 includes the electric motor 2.

[0019] <Cooling device> <Electric motor> The electric motor 2 is a motor that rotates and drives wheels (e.g., rear wheels) 102 of a vehicle body 101. The electric motor 2 includes a cylindrical stator 3, a case 4 that houses the stator 3, and a rotor (not shown) that is disposed in the radial center of the stator 3 and rotatably supported by the case 4. The rotational force of the rotor is transmitted to the wheels 102, causing the wheels 102 to rotate. The rotational axis of the rotor is aligned with the vehicle width direction of the vehicle body 101. The axial center A of the stator 3 coincides with the rotational axis of the rotor. In the following explanation of the electric motor 2, the axial direction of the stator 3 will be simply referred to as the axial direction, the radial direction of the stator 3 will be simply referred to as the radial direction, and the circumferential direction of the stator 3 (the direction of rotation of the rotor) will be simply referred to as the circumferential direction.

[0020] Fig. 3 is an enlarged perspective view of a portion of the stator 3. For ease of understanding, Fig. 3 shows the outer surface of a stator core 5 (described later) in a see-through manner. Fig. 4 is a partial cross-sectional view of the stator 3. 2 to 4, the stator 3 includes a coil 6 wound around a cylindrical stator core 5. The stator core 5 is formed by laminating multiple electromagnetic steel sheets. The stator core 5 includes a cylindrical back yoke 7 and multiple teeth 8 that protrude radially inward from the inner circumferential surface of the back yoke 7.

[0021] The teeth 8 are arranged at equal intervals in the circumferential direction. A slot 9 is formed between two circumferentially adjacent teeth 8. A coil 6 is inserted into the slot 9 and wound around each tooth 8. In Figs. 3 and 4, the coil 6 is not shown to make the explanation easier to understand. With this configuration, when current is applied to the coil 6, a predetermined magnetic flux linkage is formed in each tooth 8. The magnetic effect of this magnetic flux linkage causes a rotor (not shown) to rotate continuously.

[0022] Four fastening portions 14 are formed on the outer peripheral surface 7a of the back yoke 7 so as to protrude radially outward. The four fastening portions 14 are arranged at equal intervals in the circumferential direction. The fastening portions 14 are used to fasten and fix the stator 3 to, for example, the case 4. The fastening portions 14 are formed with bolt insertion holes 10 that penetrate in the axial direction. Bolts 11 are inserted into the bolt insertion holes 10 and tightened to the case 4, etc., to fasten and fix the stator 3 to the case 4.

[0023] The back yoke 7 is formed with cooling passages 12 extending in the circumferential direction. The cooling passages 12 are formed inside the back yoke 7 and are not open to the outside. The cooling passages 12 are divided into four in the circumferential direction. The circumferential length of each cooling passage 12 is the same length and is formed to be slightly shorter than one-quarter of the circumferential length. Therefore, the cooling passages 12 are not connected to each other. For ease of understanding, FIG. 2 shows the cooling passages 12 by cutting away a portion of the stator core 5.

[0024] Each cooling passage 12 is disposed to correspond to a fastening portion 14. That is, the fastening portion 14 is located on the radially outer side of the circumferential center of each cooling passage 12. The axial width of the cooling path 12 is, for example, about 1 / 3 of the axial width of the back yoke 7. However, this is not limited to this, and the cooling path 12 may be formed so as not to be open to the outside. The cooling path 12 is disposed in the center of the back yoke 7 in the axial direction.

[0025] A plurality of coolant discharge ports 15 are formed in the back yoke 7 at positions overlapping with the cooling paths 12 when viewed in the axial direction. The coolant discharge ports 15 penetrate the back yoke 7 in the axial direction via the cooling paths 12. In other words, the coolant discharge ports 15 are connected to the cooling paths 12. The coolant discharge ports 15 are arranged in a row at equal intervals in the circumferential direction. The back yoke 7 is formed with refrigerant supply ports 16 that connect the bolt insertion holes 10 and the cooling passages 12. A refrigerant supply port 16 is formed for each divided cooling passage 12. The refrigerant supply ports 16 are formed along the radial direction. The refrigerant supply ports 16 are disposed in the center of the back yoke 7 in the axial direction.

[0026] Returning to Figure 2, in addition to the electric motor 2, the cooling device 1 includes a pump 17 that discharges a refrigerant, a heat exchanger 18 that cools the refrigerant discharged from the pump 17, a refrigerant supply pipe 19 and a refrigerant return pipe 23 that connect the pump 17 and the electric motor 2 via the heat exchanger 18, a control valve 20 provided midway through the refrigerant supply pipe 19, a temperature sensor 21 provided in the stator 3, and a control unit 22 that controls the drive of the control valve 20.

[0027] The pump 17 pumps up and discharges the refrigerant stored in a tank (not shown). Refrigerant supply pipe 19 branches from heat exchanger 18 into four pipes corresponding to cooling paths 12, and each pipe is connected to bolt insertion holes 10. That is, refrigerant supply pipe 19 connects pump 17 and refrigerant supply port 16 via heat exchanger 18 and bolt insertion holes 10. The refrigerant return pipe 23 connects the case 4 to a tank (not shown).

[0028] A control valve 20 is provided in each of the branched refrigerant supply pipes 19. Each control valve 20 controls the flow rate of the refrigerant flowing through the corresponding refrigerant supply pipe 19. The temperature sensor 21 detects the temperature of the stator 3 and outputs the detection result as a signal to the control unit 22. The temperature sensor 21 is provided, for example, on the coil 6 of the stator 3 where the temperature becomes the highest. The control unit 22 controls the driving of the control valve 20 based on the detection result of the temperature sensor 21. The specific operation of the cooling device 1 will be described in detail below.

[0029] <Cooling device operation> For ease of understanding, in describing the operation of the cooling device 1, the names of the cooling paths 12, the refrigerant supply pipes 19, and the control valves 20 may be distinguished as follows depending on the installation posture of the electric motor 2. That is, as shown in Fig. 2, when the vehicle 100 is positioned on a horizontal road surface, the electric motor 2 is positioned such that the four fastening portions 14 are positioned one on each of the top and bottom (top and bottom of the paper) and one on each of the front and rear. The posture of the electric motor 2 shown in Fig. 2 is assumed to represent a state in which the vehicle 100 is positioned on a horizontal road surface.

[0030] In this position, in Figure 2, the top of the page is referred to as the 0 o'clock direction, the right side of the page is referred to as the 3 o'clock direction, the bottom side of the page is referred to as the 6 o'clock direction, and the left side of the page is referred to as the 3 o'clock direction. The cooling path 12 in the 0 o'clock direction is referred to as the 0 o'clock cooling path 12a. The cooling path 12 in the 3 o'clock direction is referred to as the 3 o'clock cooling path 12b. The cooling path 12 in the 6 o'clock direction is referred to as the 6 o'clock cooling path 12c. The cooling path 12 in the 9 o'clock direction is referred to as the 9 o'clock cooling path 12d.

[0031] The refrigerant supply pipe 19 connected to the 0 o'clock cooling passage 12a via the bolt insertion hole 10 and the refrigerant supply port 16 and the control valve 20 provided on this refrigerant supply pipe 19 are referred to as the 0 o'clock supply pipe 19a and the 0 o'clock valve 20a, respectively. The refrigerant supply pipe 19 connected to the 3 o'clock cooling passage 12b via the bolt insertion hole 10 and the refrigerant supply port 16 and the control valve 20 provided on this refrigerant supply pipe 19 are referred to as the 3 o'clock supply pipe 19b and the 3 o'clock valve 20b, respectively. The refrigerant supply pipe 19 connected to the 6 o'clock cooling passage 12c via the bolt insertion hole 10 and the refrigerant supply port 16 and the control valve 20 provided on this refrigerant supply pipe 19 are referred to as the 6 o'clock supply pipe 19c and the 6 o'clock valve 20c, respectively. The refrigerant supply pipe 19 connected to the 9 o'clock cooling path 12d via the bolt insertion hole 10 and the refrigerant supply port 16 and the control valve 20 provided on this refrigerant supply pipe 19 are referred to as the 9 o'clock supply pipe 19d and the 9 o'clock valve 20d, respectively.

[0032] <Normal operation of the cooling system> First, normal operation of the cooling device 1 will be described. During normal operation, the refrigerant pumped up from a tank (not shown) by the pump 17 is supplied to each of the cooling paths 12a, 12b, 12c, and 12d via the bolt insertion holes 10 and the refrigerant supply port 16 (see arrow Y1 in Figures 3 and 4). At this time, a bolt 11 is inserted into the bolt insertion hole 10. However, a gap G is formed between the bolt insertion hole 10 and the bolt 11, and the refrigerant flows through this gap G into the refrigerant supply port 16.

[0033] Thereafter, the refrigerant flows into the entire cooling paths 12a, 12b, 12c, and 12d (see arrow Y2 in FIG. 3), and the refrigerant cools the entire circumference of the stator core 5. Then, the refrigerant that has received heat from the stator core 5 is discharged into the case 4 through the refrigerant discharge port 15. The refrigerant discharged into the case 4 is returned to a tank (not shown) via the refrigerant return pipe 23. Then, the refrigerant is pumped up again by the pump 17 and discharged to the refrigerant supply pipe 19. The refrigerant discharged from the pump 17 is cooled via the heat exchanger 18 and is supplied again to each of the cooling paths 12a, 12b, 12c, and 12d.

[0034] <Valve drive control> Next, the drive control of the valves 20a, 20b, 20c, and 20d will be described. In the normal operation described above, the opening degrees of the valves 20a, 20b, 20c, and 20d are approximately medium. When controlling the drive of the valves 20a, 20b, 20c, and 20d, the opening degrees of the valves 20a, 20b, 20c, and 20d are controlled to control the flow rates of the refrigerant supplied to the cooling paths 12a, 12b, 12c, and 12d.

[0035] Before describing the drive control of each valve 20a, 20b, 20c, and 20d, the position of the temperature sensor 21 will be described first. The temperature sensors 21 are respectively disposed on the coil 6 located at the 0 o'clock position and the coil 6 located at the 6 o'clock position. This is because the temperature difference between the 0 o'clock position and the 6 o'clock position in the stator core 5 tends to be greatest. That is, the refrigerant discharged from the refrigerant discharge port 15 drips downward (toward the 6 o'clock position). Because the refrigerant discharged from the refrigerant discharge port 15 has received heat from the stator core 5, its temperature is higher than the initial temperature when it was supplied to each cooling path 12a, 12b, 12c, and 12d.

[0036] The temperature of the stator core 5 tends to rise easily in the 6 o'clock direction where a relatively high temperature refrigerant drips, while the temperature does not rise easily in the 0 o'clock direction. For this reason, temperature sensors 21 are disposed on the coils 6 located at the 0 o'clock direction and the 6 o'clock direction. With this configuration, the cooling device 1 operates as follows.

[0037] FIG. 5 is a flowchart for controlling the driving of the valves 20a, 20b, 20c, and 20d. 2 and 5, with pump 17 in operation, it is first determined whether the difference between the temperature detected by temperature sensor 21 at 6 o'clock (hereinafter referred to as the 6 o'clock temperature) and the temperature detected by temperature sensor 21 at 0 o'clock (hereinafter referred to as the 0 o'clock temperature) is greater than a predetermined multiplier (step ST101). This predetermined multiplier is a preset allowable temperature difference.

[0038] If the determination in step ST101 is "No," that is, if the difference between the 6 o'clock temperature and the midnight temperature is equal to or less than the predetermined multiplier, the process ends without controlling the drive of each of the valves 20a, 20b, 20c, and 20d. In other words, normal operation is maintained.

[0039] If the determination in step ST101 is "Yes," that is, if the difference between the 6 o'clock temperature and the midnight temperature is greater than the predetermined multiplier, the opening of the 6 o'clock valve 20c is increased (step ST102), which increases the flow rate of refrigerant in the 6 o'clock supply pipe 19c and the 6 o'clock cooling path 12c, thereby promoting cooling of the 6 o'clock side of the stator core 5.

[0040] Next, the opening of midnight valve 20a is reduced (step ST103). This reduces the flow rate of refrigerant in midnight supply pipe 19a and midnight cooling path 12a. Therefore, even if the flow rate of refrigerant in 6 o'clock supply pipe 19c and 6 o'clock cooling path 12c is increased, the total discharge rate of refrigerant from pump 17 can be prevented from changing.

[0041] Next, it is determined whether the difference between the 6 o'clock temperature and the midnight temperature is equal to or less than a predetermined multiplier (step ST104). If the determination in step ST104 is "No," that is, if the difference between the 6 o'clock temperature and the midnight temperature is greater than the predetermined multiplier, the determination in step ST104 is continued. If the determination in step ST104 is "Yes," that is, if the difference between the 6 o'clock temperature and the midnight temperature is equal to or less than the predetermined multiplier, the valves 20a, 20b, 20c, and 20d are set to the same opening degree (step ST105). In other words, normal operation is resumed. This ends the drive control of the valves 20a, 20b, 20c, and 20d.

[0042] As described above, in the embodiment described above, the back yoke 7 is formed with the cooling passage 12 extending in the circumferential direction. The cooling passage 12 is divided into four portions in the circumferential direction. A refrigerant supply port 16 is formed for each of the cooling passages 12a, 12b, 12c, and 12d. This allows the refrigerant to be supplied separately to each of the cooling passages 12a, 12b, 12c, and 12d. This prevents uneven cooling of the stator core 5 by the refrigerant, allows the entire stator 3 to be cooled evenly, and contributes to continuous driving of the electric motor 2.

[0043] The stator core 5 has fastening portions 14. The fastening portions 14 have bolt insertion holes 10. The bolt insertion holes 10 are connected to refrigerant supply ports 16. Therefore, the bolt insertion holes 10 can be used to supply refrigerant to each of the cooling paths 12a, 12b, 12c, and 12d via the refrigerant supply ports 16. This reduces the processing cost of the refrigerant supply ports 16.

[0044] Furthermore, because bolt insertion holes 10 are used, the effect on back yoke 7 of forming refrigerant supply port 16 can be minimized. In other words, if the number of holes in back yoke 7 is increased unnecessarily, the magnetic circuit may be obstructed and the desired interlinkage magnetic flux may not be obtained for the entire stator 3. However, by using bolt insertion holes 10, the number of holes formed in back yoke 7 can be minimized. Therefore, the effect on back yoke 7 of forming refrigerant supply port 16 can be minimized.

[0045] In addition to the electric motor 2, the cooling device 1 includes a pump 17, a control valve 20 (valves 20a, 20b, 20c, and 20d), a temperature sensor 21, and a control unit 22. The control unit 22 controls the control valve 20 based on the temperature detected by the temperature sensor 21, thereby controlling the flow rate of the refrigerant supplied to each refrigerant supply port 16. This makes it possible to control the flow rate of the refrigerant in each of the cooling paths 12a, 12b, 12c, and 12d according to the temperature of the stator 3. This allows the entire stator 3 to be cooled more evenly, which reliably contributes to the continuous operation of the electric motor 2.

[0046] [Variations] In the above embodiment, the case where the temperature sensors 21 are provided at two locations, at the 0 o'clock and 6 o'clock positions of the stator 3, has been described. However, this is not limiting, and the number of temperature sensors 21 may be one or three or more. When there is one temperature sensor 21, it is desirable to provide the temperature sensor 21 at the 6 o'clock position of the stator 3. In this case, for example, the change in the temperature difference with respect to the 0 o'clock position of the stator 3 according to the temperature detected by the temperature sensor 21 may be stored in advance in the control unit 22 as a graph or table. Then, in the above step ST101 and step ST104 (also see FIG. 5), the determination may be made with reference to the graph or table.

[0047] In the above embodiment, the case where the control valve 20 is controlled based on the temperature detected by the temperature sensor 21 has been described. However, this is not limiting, and the control valve 20 may be controlled using a sensor that can predict the temperature of the stator 3. Examples of this type of sensor include a rotation speed detection sensor that detects the rotation speed of the electric motor 2 (rotor), a torque sensor 29 (see FIG. 2) that detects the torque of the electric motor 2, and a temperature sensor that detects the temperature of the lubricating oil for the electric motor 2. A threshold value may be set in advance depending on the type of sensor, and the control valve 20 may be controlled by determining whether or not the threshold value has been exceeded. Below, a specific example where the torque sensor 29 of the electric motor 2 is used will be described.

[0048] <Valve drive control> FIG. 6 is a flowchart for controlling the drive of each of the valves 20a, 20b, 20c, and 20d using the torque sensor 29. 6, while the pump 17 is being driven, it is first determined whether or not the torque value detected by the torque sensor 29 (hereinafter simply referred to as the torque value) is greater than a predetermined multiplier (step ST201). This predetermined multiplier is a preset designated torque value.

[0049] If the determination in step ST201 is "No," that is, if the torque value is equal to or less than the predetermined multiplier, it is determined that the temperature rise of the stator 3 has been suppressed. Therefore, the process ends without performing drive control of the valves 20a, 20b, 20c, and 20d. In other words, normal operation is maintained.

[0050] If the determination in step ST201 is "Yes," that is, if the torque value is greater than the predetermined multiplier, it is expected that a high load is being applied to the electric motor 2, causing the temperature of the stator 3 to rise. Therefore, the opening of the 6 o'clock valve 20c is increased (step ST202). This increases the flow rate of the refrigerant in the 6 o'clock supply pipe 19c and the 6 o'clock cooling path 12c, promoting cooling of the 6 o'clock side of the stator core 5.

[0051] Next, the opening of midnight valve 20a is reduced (step ST203). This reduces the flow rate of refrigerant in midnight supply pipe 19a and midnight cooling path 12a. Therefore, even if the flow rate of refrigerant in 6 o'clock supply pipe 19c and 6 o'clock cooling path 12c is increased, the total discharge rate of refrigerant from pump 17 can be prevented from changing.

[0052] Next, it is determined whether the torque value is equal to or less than a predetermined multiplier (step ST204). If the determination in step ST204 is "No", that is, if the torque value is greater than the predetermined multiplier, the determination in step ST204 is continued. If the determination in step ST204 is "Yes," that is, if the torque value is equal to or less than the predetermined multiplier, the valves 20a, 20b, 20c, and 20d are set to the same opening degree (step ST205). That is, normal operation is resumed. This ends the drive control of the valves 20a, 20b, 20c, and 20d.

[0053] By configuring in this way, the same effects as those of the above-described embodiment can be achieved.

[0054] In the above embodiment, the case where the control valve 20 is controlled using the temperature sensor 21, another temperature sensor that detects the temperature of the lubricating oil of the electric motor 2, and a rotation speed detection sensor or torque sensor 29 that can predict the temperature of the stator 3, etc. However, this is not limited to this, and the control valve 20 may also be controlled using an inclination sensor 30 (see FIG. 7) that detects the inclination of the vehicle body 101 (electric motor 2).

[0055] The tilt sensor 30 may be, for example, a tilt sensor that directly detects the tilt angle of an object, or an inertial sensor such as an acceleration sensor or gyro sensor that derives the tilt angle using acceleration. The tilt sensor 30 may be provided in any location as long as it can detect the tilt of the electric motor 2, and ultimately the tilt of the vehicle body 101. The drive control of each of the valves 20a, 20b, 20c, and 20d using the tilt sensor 30 will be described below.

[0056] FIG. 7 is a schematic diagram showing a modified example of the cooling device 1. In FIG. 7 shows a state in which the vehicle 100 is traveling, for example, on a slope, and the 0 o'clock direction of the vehicle body 101 (electric motor 2) is tilted toward the 3 o'clock direction (clockwise on the page). In this case, as shown in FIG. 7, the 0 o'clock cooling path 12a and the 9 o'clock cooling path 12d are positioned at the top, and the 3 o'clock cooling path 12b and the 6 o'clock cooling path 12c are positioned at the bottom.

[0057] As described above, the refrigerant supplied to each cooling path 12a, 12b, 12c, and 12d drips downward through the refrigerant outlet 15 after receiving heat from the stator core 5. As a result, the temperature of the stator core 5 is likely to rise in the lower portions of the stator core 5 corresponding to the 3 o'clock cooling path 12b and the 6 o'clock cooling path 12c. On the other hand, the flow rate of the refrigerant tends to decrease in the upper portions of the stator core 5 corresponding to the 0 o'clock cooling path 12a and the 9 o'clock cooling path 12d. For this reason, it is desirable to increase the flow rate of the refrigerant in the lower portions of the stator core 5 while maintaining a constant flow rate for the upper portions. Under these circumstances, the cooling device 1 operates as follows.

[0058] <Valve drive control> FIG. 8 is a flowchart for controlling the driving of the valves 20a, 20b, 20c, and 20d using the tilt sensor 30. 8, with the pump 17 driven, it is determined whether the inclination of the vehicle body 101 detected by the inclination sensor 30 is greater than a predetermined multiplier (step ST301). This predetermined multiplier is a preset allowable inclination of the vehicle body 101.

[0059] If the determination in step ST301 is "No," that is, if the inclination of the vehicle body 101 is equal to or less than the predetermined multiplier, it is determined that the vehicle 100 is approximately positioned on a horizontal road surface. That is, it is determined that each of the cooling passages 12a, 12b, 12c, and 12d is positioned approximately in the predetermined vertical and longitudinal directions. Therefore, the process ends without performing drive control of each of the valves 20a, 20b, 20c, and 20d. That is, normal operation is maintained.

[0060] If the determination in step ST301 is "Yes," that is, if the tilt of the vehicle body 101 is greater than the predetermined multiplier, it is predicted that the vehicle 100 is traveling uphill or downhill. Therefore, the openings of the valves 20a, 20b, 20c, and 20d corresponding to the two cooling paths 12a, 12b, 12c, and 12d that are positioned upright due to the tilt are increased (step ST302).

[0061] For example, in the position shown in Fig. 7, the opening degrees of the 6 o'clock valve 20c and the 9 o'clock valve 20d are increased. For example, in the opposite direction to the position shown in Fig. 7 (when the 0 o'clock direction of the vehicle body 101 is tilted toward the 9 o'clock direction (counterclockwise on the page)), the opening degrees of the 3 o'clock valve 20b and the 6 o'clock valve 20c are increased. This increases the flow rate of refrigerant in the lower part of the stator core 5, promoting cooling of the lower part, while ensuring a constant flow rate of refrigerant in the upper part.

[0062] Next, the openings of the valves 20a, 20b, 20c, and 20d corresponding to the two cooling paths 12a, 12b, 12c, and 12d that are positioned downward due to the tilt are reduced (step ST303).

[0063] For example, in the position shown in Fig. 7, the openings of the 0 o'clock valve 20a and the 3 o'clock valve 20b are reduced. For example, in the opposite direction to the position shown in Fig. 7 (when the 0 o'clock direction of the vehicle body 101 is tilted toward the 9 o'clock direction (counterclockwise on the page)), the openings of the 0 o'clock valve 20a and the 9 o'clock valve 20d are reduced. This reduces the flow rate of refrigerant, preventing a change in the total amount of refrigerant discharged from the pump 17.

[0064] Next, it is determined whether or not the tilt of the vehicle body 101 has become equal to or smaller than a predetermined multiplier (step ST304). If the determination in step ST304 is "No", that is, if the tilt of the vehicle body 101 is greater than the predetermined multiplier, the determination in step ST304 is continued. If the determination in step ST304 is "Yes," that is, if the inclination of the vehicle body 101 is equal to or less than the predetermined multiplier, the valves 20a, 20b, 20c, and 20d are set to the same opening degree (step ST305). That is, normal operation is performed. This ends the drive control of the valves 20a, 20b, 20c, and 20d.

[0065] This configuration provides the same effects as the above-described embodiment, and in addition, it is possible to promote cooling of the lower part of the stator core 5 while ensuring a constant flow rate of the refrigerant in the upper part.

[0066] In the above embodiment, the case where each refrigerant supply port 16 is in communication with the bolt insertion hole 10 has been described. However, this is not limited to this, and the refrigerant supply port 16 may be formed without being in communication with the bolt insertion hole 10. This will be described in detail below.

[0067] Fig. 9 is a perspective view showing a modified example of the refrigerant supply port 16. Fig. 9 corresponds to the above-mentioned Fig. 3. In Fig. 9, the outer surface of the stator core 5 is shown in a see-through manner for ease of understanding. 9, each refrigerant supply port 16 is formed near the fastening portion 14. The refrigerant supply port 16 extends radially inward from the vicinity of the fastening portion 14 on the outer peripheral surface 7a of the back yoke 7 and is connected to the cooling path 12.

[0068] In this configuration, the refrigerant supply pipe 19 (see FIGS. 2 and 7) is directly connected to each refrigerant supply port 16. Therefore, the same effects as those of the above-described embodiment are achieved.

[0069] In the above embodiment, the cooling path 12 is divided into four parts in the circumferential direction. However, this is not limiting, and the cooling path 12 may be divided into at least two parts. The cooling path 12 may also be divided into five or more parts. In the above embodiment, the cooling device 1 has been described as being used to cool the electric motor 2 mounted on the vehicle body 101. However, the present invention is not limited to this, and the cooling device 1 can be used to cool electric motors for various purposes.

[0070] In the above embodiment, the control valve 20 is used as the flow path control device for adjusting the flow rate of the refrigerant. However, the present invention is not limited to this, and any structure capable of adjusting the flow rate of the refrigerant may be used. For example, variable displacement pumps may be provided separately for each of the supply pipes 19a, 19b, 19c, and 19d, and the parts that adjust the pump discharge capacities may be used as the flow path control device.

[0071] In the above embodiment, the tilt sensor 30 is used as the tilt detection unit that detects the tilt of the vehicle body 101 (electric motor 2). However, this is not a limitation, and any means may be used as the tilt detection unit as long as it can detect the tilt of the vehicle body 101 (electric motor 2). For example, the tilt detection unit may be configured to predict the tilt by calculation based on the driving conditions of the vehicle 100. In this case, specifically, for example, the torque value of the electric motor 2 and the actual traveling speed of the vehicle 100 are detected. If the actual traveling speed is slower or faster than the predicted traveling speed predicted from the torque value, it can be predicted that the vehicle body 101 is tilted. The tilt angle of the vehicle body 101 may be predicted based on the difference between the predicted traveling speed and the actual traveling speed.

[0072] Furthermore, the present invention is not limited to the above-described embodiments, and includes various modifications to the above-described embodiments without departing from the spirit of the present invention. [Explanation of symbols]

[0073] 1...Cooling device (electric motor cooling device) 2...Electric motor 3...Stator 5... Stator core 6...Coil 7...Back yoke 8...Teeth 9. Slot 10...Bolt insertion hole 11...Bolt 12…Cooling path 12a…0 hour cooling path (cooling path) 12c...3 o'clock cooling path (cooling path) 12d...6 o'clock cooling path (cooling path) 12e...9 o'clock cooling path (cooling path) 14... Fastening part 16...Refrigerant supply port 17...Pump 20...Control valve (flow control device) 20a...0 o'clock valve (flow control device) 20b...3 o'clock valve (flow control device) 20c...6 o'clock valve (flow control device) 20d...9 o'clock valve (flow control device) 21...Temperature sensor (temperature detection unit) 22...Control unit 30...Tilt sensor (tilt detection unit) 101...Car body A…Central axis line

Claims

1. A cooling device for an electric motor having a stator, The stator includes: A stator core; a coil wound around the stator core; Equipped with The stator core is A cylindrical back yoke and a plurality of teeth protruding from the back yoke in a radial direction; a plurality of slots formed between the teeth adjacent to each other in the circumferential direction; a cooling passage provided in the back yoke along a circumferential direction so as not to communicate with the slot, through which a coolant flows; a refrigerant supply port formed in the back yoke for supplying the refrigerant to the cooling path; Equipped with a pump for supplying the refrigerant to each of the refrigerant supply ports; a flow rate control device for controlling the flow rate of the refrigerant supplied from the pump to each of the refrigerant supply ports; a temperature detection unit that detects the temperatures of the upper and lower parts of the stator separately; a control unit that controls the flow rate control device based on the temperature detected by the temperature detection unit and controls the flow rate of the refrigerant supplied to the refrigerant supply port; Equipped with The stator is installed with its central axis aligned horizontally, The cooling passage is divided in the circumferential direction and divided into at least two in the vertical direction, The refrigerant supply port is formed for each of the cooling paths, The control unit makes the refrigerant flow rates above and below the stator the same when the temperature difference between the temperatures above and below the stator detected by the temperature detection unit is smaller than a certain allowable temperature difference, and makes the refrigerant flow rate below the stator greater than the refrigerant flow rate above the stator when the temperature below the stator is higher than the temperature above the stator and the temperature difference therebetween is larger than a certain allowable temperature difference. A cooling device for an electric motor.

2. the stator core has a fastening portion for fixing the stator core to a fixed body, the fastening portion has a bolt insertion hole through which a bolt for fastening to the fixed body is inserted, The refrigerant supply port is in communication with the bolt insertion hole.

2. The motor cooling device according to claim 1.

3. The stator is fixed to the vehicle body so that the central axis thereof is aligned with the vehicle width direction, an inclination detection unit that detects the inclination of the vehicle body; a gradient control unit that controls the flow rate control device based on the gradient detected by the gradient detection unit and controls the flow rate of the refrigerant supplied to the refrigerant supply port, 2. The motor cooling device according to claim 1.

Images