Rotating electric machine unit

Abstract

In rotating electric machine units, the aim is to reduce size while suppressing vibration. [Solution] The system comprises a rotating electric machine 3, a case 2 housing the rotating electric machine 3, a power control device 202 arranged in a housing 4 integrated with the case 2 and controlling the rotating electric machine 3, and a cover 4 attached to the upper surface of the housing 4, the cover 4 having a passage 40 for a cooling medium formed in it.

Description

Technical Field

[0001] The present disclosure relates to a rotating electrical machine unit.

Background Art

[0002] In an electromechanical integrated unit in which a case housing a rotating electrical machine and a power control device for controlling the rotating electrical machine are integrated, it is known to provide an air layer between the housing of the power control device and the case (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present disclosure is to suppress the generation of vibration while achieving miniaturization in a rotating electrical machine unit.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a rotating electrical machine, a case for housing the rotating electrical machine, a power control device that is disposed in a housing integrated with the case and controls the rotating electrical machine, a cover attached to the upper surface of the housing, the cover having a passage for a cooling medium formed therein, and a rotating electrical machine unit including the above.

Effects of the Invention

[0006] According to the present disclosure, in a rotating electrical machine unit, it is possible to suppress the generation of vibration while achieving miniaturization.

Brief Description of the Drawings

[0007] [Figure 1] This is a schematic diagram showing a rotating electric machine unit in an embodiment. [Figure 2] This diagram schematically shows the cover and the configuration for supplying cooling water to the cover. [Figure 3] This is a cross-sectional view of the cooling water passage, seen from the side of the cover. [Figure 4] This is a flowchart showing the control flow of coolant pressure in the ECU. [Modes for carrying out the invention]

[0008] In transaxle structures where the case of a rotating electric machine and the housing of a power control device are integrated, there is a challenge in reducing noise and vibration. Here, the cover of the power control device housing is known as the noise-generating part, and measures such as curved surfaces and increased rib heights are taken to suppress the generation of noise and vibration here. However, because this requires a large size to ensure rigidity, the transaxle becomes large.

[0009] Furthermore, it is known that an air layer is provided between the case of the rotating electric machine and the housing of the power control device, and that the surfaces facing each other across the air layer are formed of different metals. By forming the surfaces facing each other across the air layer with different metals, resonance can be dispersed and vibration can be reduced.

[0010] However, this requires creating an air gap between the rotating electric machine case and the power control unit housing, which could increase the overall size of the unit. Furthermore, the presence of this air gap prevents the formation of a single, integrated wall surface, raising concerns about insufficient strength. Additionally, the need to use different metals increases costs.

[0011] Therefore, a rotating electric machine unit, which is one aspect of the present disclosure, comprises a rotating electric machine, a case housing the rotating electric machine, and a housing integrated with the case, which controls the rotating electric machine. The system comprises a power control device and a cover attached to the upper surface of the housing, the cover having a passage for a cooling medium.

[0012] With this configuration, the natural frequency can be changed by circulating a cooling medium through passages formed in the cover, thereby suppressing the occurrence of resonance. Consequently, the generation of noise and vibration can be suppressed. Furthermore, since there is no need to raise the height of the ribs or provide an air layer, the size of the rotating electric machine unit can be kept down. The cooling medium can be any liquid, such as water or oil. Alternatively, a mixture of antifreeze or similar liquids may be used as the cooling medium. Moreover, the cooling medium may be configured to circulate and cool other parts of the rotating electric machine unit.

[0013] Furthermore, the passage for the cooling medium may be formed inside ribs protruding from the surface of the cover. By forming these ribs, the rigidity of the cover can be increased.

[0014] The device further includes a circulation pump for circulating the cooling medium through the passage, a pressure control device for changing the pressure of the cooling medium circulated by the circulation pump, a sensor for detecting the vibration frequency of the cover, and a storage unit for storing a target pressure corresponding to the vibration frequency of the cover detected by the sensor. The pressure control device may change the pressure of the cooling medium to approach the target pressure. Changing the pressure of the cooling medium changes the rigidity of the cover. This changes the natural frequency of the cover. If the pressure control device changes the pressure of the cooling medium in a way that prevents resonance from occurring, the generation of noise and vibration can be suppressed.

[0015] Hereinafter, modes for implementing this disclosure will be described in detail by way of example with reference to the drawings. However, dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of this disclosure only to those, unless otherwise specified.

[0016] <Embodiment> FIG. 1 is a diagram schematically showing a rotating electrical machine unit 1 in an embodiment. The rotating electrical machine unit 1 is an electromechanical integrated unit. The rotating electrical machine unit 1 has a case 2. Inside the case 2, a motor 3 and a transaxle are accommodated. Also, on the upper surface of the case 2, a PCU (Power Control Unit) 20 is provided. The housing 21 of the PCU 201 is integrated with the case 2. The case 2 and the housing 21 of the PCU 201 are integrally formed using a metal material such as aluminum.

[0017] The PCU 201 controls the power supplied from the battery to the motor 3. The PCU 201 is electrically connected to the motor 3 and is also electrically connected to the battery. This motor 3 is a rotating electrical machine (motor - generator) capable of functioning as both an electric motor and a generator. The PCU 201 is mounted, for example, on a BEV (Battery Electric Vehicle) in which the motor 3 serves as a power source.

[0018] The PCU 201 houses a plurality of devices inside the housing 21 having a shielding function. It is knitted. The PCU 201 is configured to include an inverter that drives the motor 3 as a high-voltage component. Inside the housing 21, an electronic control unit (hereinafter referred to as "ECU") 202 that controls the motor 3, a DC / DC converter 203 that steps down high voltage, etc. may be further arranged. The PCU 201 has a structure in which high-voltage components such as power semiconductors are housed inside the housing 21. The inverter is housed inside the housing 21 in a modularized state of transistors and diodes. Also, the inverter is electrically connected to the motor 3 via a bus bar. The PCU 201 is an example of a power control device.

[0019] The housing 21 has a structure with an open upper part. A cover 4 is arranged on the upper part of the housing 21. The cover 4 is fixed to the housing 21, for example, by bolts so as to close the opening of the housing 21. The cover 4 is, for example, a metal member. This metal may be the same type of metal as the case 2 or a different type of metal. The cover 4 is, for example, made of die-cast.

[0020] In the cover 4 according to this embodiment, a passage through which cooling water as a cooling medium flows is formed. FIG. 2 is a diagram schematically showing the cover 4 and the configuration for supplying cooling water to the cover 4. FIG. 2 shows a bottom view of the cover 4. The cover 4 is formed so as to have a substantially rectangular shape when viewed from below. In the cover 4, an inlet 41 serving as an inlet for cooling water and an outlet 42 serving as an outlet for cooling water are formed. In the example shown in FIG. 2, the inlet 41 and the outlet 42 are formed in the same direction from the same side surface of the cover 4, but it is not limited to this, and for example, they may be formed so as to extend from different side surfaces of the cover 4.

[0021] The cover 4 has a cooling water passage 40 through which cooling water flows. The cooling water passage 40 is composed of two longitudinal sections 43 extending in the longitudinal direction of the cover 4 from an inlet 41 and an outlet 42, and four transverse sections 44 extending in the transverse direction of the cover 4 perpendicular to the two longitudinal sections 43. Figure 3 is a cross-sectional view of the cooling water passage 40 as seen from the side of the cover 4. The cooling water passage 40 is formed inside a rib 45 that protrudes downward (towards the front in Figure 2) from the lower surface of the cover 4. The upper surface of the cover 4 may be flat or curved. The shape of the cooling water passage 40 is not limited to this. For example, the cooling water passage 40 may be composed of a single meandering flow path. It is also not necessary for it to be formed inside the rib 45.

[0022] The inlet 41 is connected to the discharge port 11 of the pump 10 via the inlet pipe 5. The outlet 42 is connected to the suction port 12 of the pump 10 via the outlet pipe 6. The pump 10 is a pump that operates in response to commands from the ECU 202 and discharges cooling water. The outlet pipe 6 is equipped with a valve 7 that operates in response to commands from the ECU 202 and can adjust the flow rate of the cooling water. The cooling water discharged from the discharge port 11 of the pump 10 flows through the inlet pipe 5 and flows into the cooling water passage 40 of the cover 4 from the inlet 41. In the cover 4, the cooling water flows through the longitudinal section 43 on the inlet 41 side and flows into each of the short sections 44. Furthermore, the cooling water flows from each of the short sections 44 into the longitudinal section 43 on the outlet 42 side and flows toward the outlet 42. The cooling water that flows out from the outlet 42 flows through the outlet pipe 6 and is drawn into the pump 10 from the suction port 12. A radiator that removes heat from the coolant may be interposed in the outlet pipe 6. The pump 10, inlet pipe 5, and outlet pipe 6 may be mounted on the outside or inside of the case 2.

[0023] The ECU202 comprises a control unit 110 and a memory unit 120. In addition to controlling the motor 3, the control unit 110 also controls the pump 10 and the valve 7. Furthermore, the ECU202 is connected to a pressure sensor 130 for detecting the cooling water pressure and a vibration sensor 131 for detecting the vibration frequency of the cover 4, in addition to the pump 10 and the valve 7. The ECU202 is one of the pressure control devices. This is an example.

[0024] The control unit 110 can be implemented by a hardware processor such as a CPU. The control unit 110 may also include RAM, ROM (Read Only Memory), cache memory, etc. The storage unit 120 is a means for storing information and is composed of a storage medium such as RAM or flash memory. The storage unit 120 stores programs executed by the control unit 110, data used by those programs, etc. The storage unit 120 also stores pressure information 121, which shows the relationship between the vibration frequency detected by the vibration sensor 131 and the cooling water pressure to be set (hereinafter also referred to as the target pressure). The pressure information 121 is determined in advance through experiments or simulations.

[0025] The pressure sensor 130 can be installed in any location where it can detect the pressure of the cooling water in the cooling water passage 40, and may be installed on the cover 4, the inlet pipe 5, the outlet pipe 6, or the pump 10. The vibration sensor 131 can be installed in any location where it can detect the vibration frequency of the cover 4.

[0026] The control unit 110 controls the cooling water pressure by controlling at least one of the amount of cooling water discharged from the pump 10 and the opening degree of the valve 7. The pump 10 may operate continuously to cool the PCU 201, or it may operate, for example, when a temperature sensor on the PCU 201 exceeds a threshold. The control unit 110 also controls the cooling water pressure so that the natural frequency of the cover 4 falls outside the frequency detected by the vibration sensor 131. The pressure information 121 stored in the memory unit 120 stores a target pressure corresponding to the frequency detected by the vibration sensor 131, so that the natural frequency of the cover falls outside the frequency detected by the vibration sensor 131. Therefore, the control unit 110 obtains the target pressure by referring to the pressure information 121 according to the frequency detected by the vibration sensor 131. Then, it provides feedback control to at least one of the pump 10 and the valve 7 so that the cooling water pressure detected by the pressure sensor 130 becomes the target pressure.

[0027] Figure 4 is a flowchart showing the control flow of the cooling water pressure in the ECU 202. The routine shown in Figure 4 is executed in the ECU 202 at predetermined time intervals. In step S101, the control unit 110 acquires the vibration frequency detected by the vibration sensor 131. Once the processing in step S101 is completed, the process proceeds to step S102.

[0028] In step S102, the control unit 110 identifies a target pressure corresponding to the vibration frequency acquired in step S101. The control unit 110 identifies the target pressure according to the pressure information 121 stored in the memory unit 120. The target pressure may be identified as a pressure range with a certain width. Once the processing in step S102 is completed, the process proceeds to step S103.

[0029] In step S103, the control unit 110 controls at least one of the discharge rate of the pump 10 and the opening degree of the valve 7 so that the value detected by the pressure sensor 130 approaches the target pressure identified in step S102. If the value detected by the pressure sensor 130 is lower than the target pressure, the control unit 110 increases the discharge rate of the pump 10 and decreases the opening degree of the valve 7 to increase the cooling water pressure. If the value detected by the pressure sensor 130 is higher than the target pressure, the control unit 110 decreases the discharge rate of the pump 10 and increases the opening degree of the valve 7 to decrease the cooling water pressure. At this time, the control unit 110 may perform feedback control so that the pressure detected by the pressure sensor 130 becomes the target pressure.

[0030] As described above, according to this embodiment, the natural frequency of the cover 4 can be changed by controlling the pump 10, thereby suppressing the resonance of the cover 4. Therefore, it is possible to suppress the generation of noise and vibration.

[0031] <Other Embodiments> In the above embodiment, an example is described in which the pump 10 is controlled by feedback according to the value detected by the vibration sensor 131. However, instead, the pump 10 may be controlled according to the value detected by other sensors related to the vibration frequency. For example, since the vibration frequency is thought to change depending on the load and speed of the vehicle, the pump 10 may be controlled according to the vehicle speed, the amount the accelerator pedal is pressed, etc. [Explanation of Symbols]

[0032] 1. Rotating Electrical Unit 2 cases 3 motors 4 Covers 40 Cooling water passage 110 Control Unit 120 Storage section 202 ECU

Claims

1. Rotating electric machines and, A case for housing the aforementioned rotating electric machine, A power control device for controlling the rotating electric machine is housed in a housing integrated with the aforementioned case, A cover attached to the upper surface of the housing, the cover having a passage for a cooling medium, A rotating electric machine unit equipped with the following features.

2. The passage for the cooling medium is formed inside the ribs that protrude from the surface of the cover. The rotating electric machine unit according to claim 1.

3. A circulation pump for circulating the cooling medium in the passage, A pressure control device that changes the pressure of the cooling medium circulated by the circulation pump, A sensor for detecting the vibration frequency of the cover, A storage unit that stores a target pressure corresponding to the vibration frequency of the cover detected by the sensor, Furthermore, The pressure control device changes the pressure of the cooling medium so as to approach the target pressure. The rotating electric machine unit according to claim 1.

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