Drive device for vehicle

Abstract

Provided is a technique for suppressing the occurrence of excessive vibration in an electric oil pump in a vehicle provided with an engine and the electric oil pump. A drive device is provided with: a drive system including an engine; a housing accommodating the driving system; an oil circulation path provided in the housing; an electric oil pump that circulates oil along the oil circulation path; an oil reservoir which is provided inside or near the electric oil pump, branches from the oil circulation path, and stores oil; and a control device that adjusts the amount of oil stored in the oil reservoir, the control device changing the amount of oil stored in the oil reservoir in accordance with the rotational speed of the engine.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a drive system for a vehicle. Background Technology

[0002] Patent Document 1 discloses a variable speed drive axle for a hybrid vehicle. An inverter, an engine, and other components are mounted on this variable speed drive axle. Furthermore, the variable speed drive axle includes a pump unit such as an oil cooler and an oil pump. In other words, in the technology of Patent Document 1, the drive mechanism, including the engine, is integrated with the oil pump.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-198229 Summary of the Invention In vehicles equipped with an engine and an electric oil pump, vibrations at a frequency corresponding to the engine's rotational speed are generated by the engine's rotation. If the frequency of the vibration generated by the engine's rotation coincides with the resonant frequency of the electric oil pump, resonance occurs in the electric oil pump. This specification provides a technique for suppressing excessive vibration generated in the electric oil pump in a vehicle equipped with an engine and an electric oil pump.

[0004] The technology disclosed in this specification is embodied in the drive system of a vehicle. In a first embodiment, the drive system includes: a drive system comprising an engine; a housing housing the drive system; an oil circulation path disposed in the housing; an electric oil pump that circulates oil along the oil circulation path; an oil reservoir disposed inside or near the electric oil pump and branching from the oil circulation path to store the oil; and a control device that regulates the amount of oil stored in the oil reservoir, the control device changing the amount of oil stored in the oil reservoir according to the engine speed.

[0005] Based on the engine speed, vibrations are generated at a frequency approximately matching the resonant frequency of the electric fuel pump. In this situation, the control device changes the amount of fuel stored in the reservoir. Typically, the resonant frequency of the electric fuel pump is determined by its structure, shape, and materials. By changing the amount of fuel stored in the reservoir, the resonant frequency of the electric fuel pump changes. Therefore, resonance caused by engine operation is suppressed in the electric fuel pump. Thus, excessive vibration in the electric fuel pump is suppressed.

[0006] In the second aspect of this technology, in addition to the first aspect described above, the control device can change the amount of oil stored in the oil reservoir between situations where the engine is operating within a specific speed range and situations where it is not operating within that specific speed range. While not particularly limited, the specific speed range can be a speed range that causes the electric oil pump to resonate. In this configuration, when the engine is operating within the specific speed range, the resonance generated in the electric oil pump due to engine operation is suppressed by changing the resonant frequency of the electric oil pump. Therefore, excessive vibration in the electric oil pump is suppressed.

[0007] In a third embodiment of this technology, in addition to the first or second embodiment described above, at least one valve may be provided, which is used to connect and disconnect the electric oil pump from the oil reservoir. The control device can change the amount of oil stored in the oil reservoir by controlling the operation of the at least one valve. In this configuration, the control device can change the amount of oil stored in the oil reservoir by controlling the operation of the valve.

[0008] The technology disclosed in this specification is embodied in the drive system of another vehicle. In the fourth embodiment, the drive system includes: a drive system comprising an engine; a housing housing the drive system; an oil circulation path disposed within the housing; an electric oil pump that circulates oil along the oil circulation path; and A pump control device controls the rotational speed of the electric oil pump, and the pump control device changes the rotational speed of the electric oil pump according to the rotational speed of the engine.

[0009] Based on the engine speed, vibrations are generated at a frequency approximately matching the resonant frequency of the electric oil pump. The control device adjusts the electric oil pump speed according to the engine speed. The rotation of the electric oil pump generates vibrations that counteract or at least reduce the vibrations caused by engine operation. Therefore, resonance caused by engine operation is suppressed in the electric oil pump. Consequently, excessive vibration in the electric oil pump is suppressed.

[0010] In the fifth aspect of this technology, in addition to the fourth aspect described above, the pump control device can change the speed of the electric oil pump between situations where the engine is operating within a specific speed range and situations where it is not operating within that specific speed range. While not particularly limited, the specific speed range can be a speed range that causes the electric oil pump to resonate. In this case, the pump control device can change the speed of the electric oil pump in a manner that generates an anti-phase vibration in the electric oil pump. In this configuration, the operation of the electric oil pump generates vibrations that are anti-phase with the vibrations generated by the engine's operation. By changing the speed of the electric oil pump, vibrations that can either cancel out or at least reduce the vibrations caused by the engine's operation can be generated. Therefore, resonance caused by the engine's operation is suppressed in the electric oil pump. Thus, excessive vibration in the electric oil pump is suppressed. Attached Figure Description

[0011] Figure 1 It is a diagram schematically representing the structure of the drive unit.

[0012] Figure 2 This is a schematic cross-sectional view of an electric oil pump.

[0013] Figure 3 This is a schematic top view of an electric oil pump.

[0014] Figure 4 It is a diagram used to illustrate the flow of oil.

[0015] Figure 5 This is a diagram used to illustrate the magnitude of vibration in an electric oil pump. Detailed Implementation

[0016] (First embodiment) Referring to the accompanying drawings, the drive unit 2 of the first embodiment will be described. The drive unit 2 of this embodiment is mounted on a so-called hybrid vehicle having an engine 22 and a drive motor 24. In a variation, the drive unit 2 can be mounted on a vehicle having an engine but not a drive motor. The drive unit 2 includes a control device 10, an engine 22, a motor 24, a gear set 26, a pair of drive shafts 28, and an electric oil pump 30. Hereinafter, the engine 22, motor 24, and gear set 26 will be collectively referred to as the "drive system." The drive system is housed in a housing 4.

[0017] Housing 4 is the housing of drive unit 2, and is made of metal, for example. An oil circulation path (not shown) is provided within housing 4. This oil circulation path is for the purpose of lubrication and cooling. For details regarding the circulation path, please refer to [reference needed]. Figure 4 To be described later.

[0018] The control device 10 controls the operation of the drive system, for example, according to instructions from a higher-level control device (not shown). Furthermore, although details will be described later, the control device 10 regulates the amount of oil stored in the oil reservoir 38 located inside or near the electric oil pump 30.

[0019] Engine 22 is a heat engine, such as a gasoline engine or a diesel engine, that generates power by burning fuel. Motor 24 is a motor for driving the vehicle equipped with drive unit 2. Power is supplied to motor 24 from a battery (not shown) via a power conversion device (not shown). Specifically, direct current (DC) power output from the battery is converted into alternating current (AC) power in the power conversion device, and the converted AC power is supplied to motor 24.

[0020] The gear set 26 includes a reduction gear and a differential. The reduction gear is mechanically connected to the engine 22 and the motor 24. The reduction gear amplifies the torque output by the engine 22 and the motor 24. The differential is mechanically connected to the engine 22 and the motor 24 via the reduction gear. The differential is connected to a pair of drive wheels (not shown) via a pair of drive shafts 28. Thus, the torque output by the engine 22 and the motor 24, after being amplified by the reduction gear, is distributed to the pair of drive shafts 28 through the differential. The vehicle can then drive the pair of drive wheels by the torque distributed to them.

[0021] An electric oil pump 30 is installed at the lower part of the housing 4. The electric oil pump 30 circulates oil along the oil circulation path inside the housing 4. Specifically, the electric oil pump 30 draws in oil that is retained in the lower part of the housing 4 and pumps it to various parts of the housing 4 via the oil circulation path inside the housing 4.

[0022] refer to Figure 2 and Figure 3 The structure of the electric oil pump 30 will be described. For example... Figure 2 As shown, the electric oil pump 30 includes a pump rotor 32, a pump motor 34, and a control circuit board 36. The pump rotor 32 is mechanically connected to the pump motor 34. The pump motor 34 is a small electric motor and serves as the prime mover of the electric oil pump 30. The rotation of the pump motor 34 drives the pump rotor 32. In the electric oil pump 30, when the pump rotor 32 rotates, the oil retained in the housing 4 is drawn into the electric oil pump 30. The control circuit board 36 drives the electric oil pump 30, for example, according to instructions input from a higher-level control device (e.g., control device 10).

[0023] Furthermore, an oil reservoir 38 is provided inside the electric oil pump 30, which branches off from the oil circulation path inside the housing 4 and stores oil. Alternatively, in a modified example, the oil reservoir 38 may not be provided inside the electric oil pump 30; for example, it may be provided near the electric oil pump 30.

[0024] Here, for reference Figure 4The flow path of the oil is explained. For example... Figure 4 As shown, the oil flow path includes an oil circulation path (i.e., a lubrication path) located within the housing 4 and an oil storage path branching off from the oil circulation path. Oil retained in the lower part of the housing 4 is supplied to a switching valve via a filter by an electric oil pump 30. The switching valve is located at the branch point between the lubrication path and the oil storage path. The switching valve adjusts the amount of oil flowing into the lubrication path and the amount of oil flowing into the oil storage path.

[0025] Under normal circumstances, the total amount of oil supplied to the switching valve is supplied to the lubrication path. The oil supplied to the lubrication path is used, for example, as lubricant for driving the engine 22, etc., and as oil for cooling the engine 22, motor 24, etc. The oil flowing through the lubrication path is then retained in the lower part of the housing 4.

[0026] Furthermore, a switching valve is also provided on the downstream side of the oil storage section 38. This switching valve adjusts the amount of oil discharged from the oil storage section 38. The oil discharged from the oil storage section 38 is then retained in the lower part of the housing 4.

[0027] The control device 10 controls the switching valve based on the engine speed of the engine 22. Specifically, the control device 10 changes the amount of oil stored in the oil reservoir 38 by controlling the operation of the switching valve between situations where the engine 22 is operating within a specific speed range and situations where it is not operating within a specific speed range. In one example, the control device 10 controls the switching valve located at the branch point of the lubrication path and the oil reservoir path, changing the amount of oil stored in the oil reservoir 38 (i.e., increasing) by increasing the flow rate of oil flowing into the oil reservoir path. In another example, the control device 10 controls the switching valve located downstream of the oil reservoir 38, changing the amount of oil stored in the oil reservoir 38 (i.e., decreasing) by releasing oil from the oil reservoir 38.

[0028] When engine 22 rotates, vibration is generated. The frequency of this vibration depends on the rotational speed of engine 22. If the frequency of the vibration generated by the operation of engine 22 is approximately the same as the resonant frequency of electric oil pump 30, resonance occurs in electric oil pump 30, causing excessive vibration in electric oil pump 30. The specific rotational speed range of engine 22 mentioned above is the rotational speed range in which resonance occurs in electric oil pump 30.

[0029] As described above, according to the structure of this embodiment, the control device 10 changes the amount of oil stored in the oil reservoir 38 when the engine 22 is operating within a specific speed range. Typically, the resonant frequency of the electric oil pump 30 is determined by its structure, shape, material, etc. By changing the amount of oil stored in the oil reservoir 38, the resonant frequency of the electric oil pump 30 changes. Therefore, even when the engine 22 rotates within a specific speed range, resonance in the electric oil pump 30 is suppressed. Thus, excessive vibration in the electric oil pump 30 is suppressed.

[0030] (Second embodiment) Next, refer to Figure 5 The second embodiment will now be described. In the second embodiment, the rotational speed of the electric oil pump 30 is changed to suppress resonance in the electric oil pump 30. The drive device 2 of the second embodiment may not have an oil reservoir 38. Other aspects are the same as the drive device 2 of the first embodiment.

[0031] As described above, resonance occurs in the electric oil pump 30 when the engine 22 is operating within a specific speed range. Figure 5 The dashed curve represents the relationship between the frequency of vibration generated by the rotation of engine 22 and the magnitude of vibration of electric oil pump 30 at that time. For example... Figure 5 As shown by the dashed line, if the frequency of the vibration generated by the rotation of the engine 22 is close to the resonant frequency FR of the electric oil pump 30, resonance occurs in the electric oil pump 30, and the vibration of the electric oil pump 30 becomes significantly larger. That is, when the engine 22 is operating within a specific speed range, the vibration of the electric oil pump 30 becomes excessively large.

[0032] Therefore, in the drive device 2 of the second embodiment, the control device 10 changes the rotational speed of the electric oil pump 30 according to the rotational speed of the engine 22. Specifically, the control device 10 changes the rotational speed of the electric oil pump 30 between situations where the engine 22 is operating within a specific rotational speed range and situations where it is not operating within that specific rotational speed range. The electric oil pump 30 also generates vibrations when it rotates. The frequency of the vibrations generated by the rotation of the electric oil pump 30 depends on the rotational speed of the electric oil pump 30. In this embodiment, the control device 10 changes the rotational speed of the electric oil pump 30 so that the electric oil pump 30 generates vibrations that are out of phase with the vibrations caused by the operation of the engine 22. Figure 5 The solid line curve represents the following relationship: the relationship between the frequency of vibration generated by the rotation of the engine 22 and the magnitude of vibration of the electric oil pump 30 when the rotational speed of the electric oil pump 30 is changed as described above. Figure 5As shown by the solid line curve, when the engine 22 operates within a specific speed range, even if the frequency of the vibration generated by the rotation of the engine 22 is close to the resonant frequency FR of the electric oil pump 30, the excessive increase in the magnitude of the vibration of the electric oil pump 30 is suppressed. This is because the vibrations caused by the operation of the engine 22 and the vibrations caused by the operation of the electric oil pump 30 interfere in directions that cancel each other out. Therefore, the resonance generated by the operation of the engine 22 in the electric oil pump 30 is suppressed. Thus, excessive vibration in the electric oil pump 30 is suppressed. The combination of the control device 10 and the control circuit board 36 is an example of the "pump control device" of this technology.

[0033] The above provides a detailed description of specific examples of the technology disclosed in this specification. However, these are merely illustrative and do not limit the scope of the patent claim. The technology described in the scope of the patent claim includes various modifications and variations of the specific examples illustrated above. The technical elements described in this specification or drawings are technically useful individually or in various combinations, and are not limited to the combinations described in the claims at the time of application. Furthermore, the technology illustrated in this specification or drawings can achieve multiple objectives simultaneously, wherein achieving one objective is itself technically useful.

[0034] Symbol Explanation 2-Drive unit, 4-Housing, 10-Control unit, 22-Engine, 24-Motor, 26-Gear set, 28-Drive shaft, 30-Electric oil pump.

Claims

1. A drive device for a vehicle, characterized in that, have: A drive system, which includes an engine; A housing that houses the drive system; An oil circulation path is provided within the housing; An electric oil pump that circulates oil along the oil circulation path; An oil storage unit is located inside or near the electric oil pump and stores the oil by branching off from the oil circulation path; and A control device that regulates the amount of oil stored in the oil reservoir. The control device changes the amount of oil stored in the oil reservoir according to the engine speed.

2. The driving device according to claim 1, characterized in that, The control device changes the amount of oil stored in the oil reservoir between when the engine is operating in a specific speed range and when it is not operating in a specific speed range.

3. The driving device according to claim 1 or 2, characterized in that, It also has: At least one valve for connecting and disconnecting the electric oil pump from the oil reservoir. The control device changes the amount of oil stored in the oil reservoir by controlling the operation of at least one valve.

4. A drive device, which is a drive device for a vehicle, characterized in that, have: A drive system, which includes an engine; A housing that houses the drive system; An oil circulation path is provided within the housing; An electric oil pump that circulates oil along the oil circulation path; and A pump control device that controls the rotational speed of the electric oil pump. The pump control device changes the speed of the electric oil pump according to the speed of the engine.

5. The driving device according to claim 4, characterized in that, The pump control device changes the speed of the electric oil pump between when the engine is operating in a specific speed range and when it is not operating in a specific speed range.

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