Drive unit

Abstract

To arrange a power control unit and a noise filter efficiently in a mechano-electric integral structure.SOLUTION: A drive unit 5 includes: a case 20 which houses a motor, a speed reducer, and a differential mechanism; a PCU 30 configured to control the motor; and a noise filter 40 electrically connected to the motor through the PCU 30. The PCU 30 is integrated with the case 20, and the motor, the speed reducer, and the differential mechanism are arranged on the same axis in the case 20. The PCU 30 is formed separately from the noise filter 40. The noise filter 40 is integrated with the case 20 with at least part thereof arranged in a space between the PCU 30 and the motor.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a drive unit.

Background Art

[0002] Patent Document 1 discloses a structure (electromechanical integrated structure) in which a power control unit for controlling a motor is integrated into a case that houses a motor, a speed reducer, and a differential mechanism for a drive unit of an electric vehicle. In the configuration described in Patent Document 1, a three-shaft structure transaxle in which the motor, the speed reducer, and the differential mechanism are arranged on different axes is formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in addition to the three-shaft structure transaxle, a one-shaft structure transaxle in which a motor, a speed reducer, and a differential mechanism are arranged on the same axis is known. The one-shaft structure transaxle can be made smaller than the three-shaft structure transaxle. Therefore, it is conceivable to adopt an electromechanical integrated structure for a drive unit including a one-shaft structure transaxle.

[0005] In addition, since the power control unit needs to meet the standards regarding electromagnetic compatibility (EMC), an electric circuit is formed by electrically connecting a noise filter and the power control unit as a countermeasure against EMC noise. Therefore, for a drive unit equipped with a one-axis structure transfer axle, a structure is conceivable in which a noise filter is provided and the noise filter is integrated into a case that houses the one-axis structure transfer axle.

[0006] However, the size of the case that houses the one-axis structure transfer axle is smaller than that of the case that houses the three-axis structure transfer axle. As a result, in order to achieve an electromechanical integrated structure, it becomes difficult to secure a space for installing the power control unit in the case, and it is necessary to further secure a space for installing the noise filter.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a drive unit capable of efficiently arranging a power control unit and a noise filter for an electromechanical integrated structure.

Means for Solving the Problems

[0008] The present invention includes a transfer axle case that houses a motor, a speed reducer, and a differential mechanism, a power control unit that controls the motor, and a noise filter that is electrically connected to the motor via the power control unit. The power control unit is integrated with the transfer axle case, and inside the transfer axle case, the motor, the speed reducer, and the differential mechanism are arranged on the same axis. The drive unit is characterized in that the power control unit is separate from the noise filter, and at least a part of the noise filter is integrated with the transfer axle case while being arranged in the space between the power control unit and the motor.

[0009] According to this configuration, the power control unit and the noise filter can be efficiently arranged with respect to the mechatronic structure.

[0010] Further, it has a connection part that electrically connects the motor and the power control unit, and at least a part of the noise filter may be arranged in the space between the connection part and the speed reducer.

[0011] According to this configuration, the noise filter can be arranged with high space efficiency.

[0012] Further, the transaxle case has a motor case that houses the motor, and a gear case that houses the speed reducer and the differential mechanism. The PCU case that houses the power control unit is attached to the motor case, and the noise filter may be attached to the motor case in a state of being arranged in the space between the back surface of the PCU case and the motor case.

[0013] According to this configuration, the noise filter can be arranged with high space efficiency.

Advantages of the Invention

[0014] In the present invention, the power control unit and the noise filter can be efficiently arranged with respect to the mechatronic structure.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0016] Hereinafter, with reference to the drawings, the drive unit in the embodiment of the present invention will be specifically described. Note that the present invention is not limited to the embodiments described below.

[0017] FIG. 1 is a diagram schematically showing a vehicle in an embodiment. The vehicle 1 is an electric vehicle equipped with a motor 2 as a power source, and includes a traveling motor 2 and a power transmission device 4 that transmits the power of the motor 2 to the wheels 3. The drive unit 5 mounted on this vehicle 1 is configured to include the motor 2, the power transmission device 4, and the case 20.

[0018] The motor 2 is a motor - generator that functions as an electric motor and a generator. The motor 2 is driven by electric power supplied from a battery. The motor 2 can generate electricity by receiving torque input from the wheels 3. The motor 2 includes a rotor 2a, a stator 2b, and a rotor shaft 2c.

[0019] The rotor 2a rotates integrally with the rotor shaft 2c. The stator 2b has a coil wound around the stator core and is fixed to the case 20 while being disposed on the outer peripheral side of the rotor 2a. The rotor shaft 2c is the rotation shaft of the motor 2. The rotor shaft 2c is arranged to extend along the vehicle width direction of the vehicle 1 and is rotatably supported by the case 20 via a bearing. The axial direction of the motor 2 is the same as the vehicle width direction of the vehicle 1.

[0020] The power transmission device 4 forms a power transmission path between the motor 2 and the wheels 3. The power transmission device 4 includes a speed reducer 6 and a differential mechanism 7. The power transmission device 4 includes a transaxle having a one-axis structure in which the motor 2, the speed reducer 6, and the differential mechanism 7 are arranged on the same axis.

[0021] When transmitting the power input from the motor 2 to the differential mechanism 7, the speed reducer 6 reduces the rotation input from the motor 2 and outputs it to the differential mechanism 7. This speed reducer 6 is constituted by a planetary gear mechanism. The speed reducer 6 has a sun gear 8, a ring gear 9 arranged concentrically with the sun gear 8, and a carrier 11 that rotatably and revolvably holds pinion gears 10 that mesh with the sun gear 8 and the ring gear 9. The pinion gear 10 is a stepped pinion gear having a large-diameter portion 10a and a small-diameter portion 10b.

[0022] The rotor 2a is connected to the sun gear 8. Since the rotation shaft of the sun gear 8 is spline-fitted with the rotor shaft 2c of the motor 2, the sun gear 8 rotates integrally with the rotor shaft 2c. In the pinion gear 10, the large-diameter portion 10a meshes with the sun gear 8, and the small-diameter portion 10b meshes with the ring gear 9. The ring gear 9 is fixed to the case 20. The wheels 3 are connected to the carrier 11 via the differential mechanism 7. The carrier 11 rotates integrally with the differential case 12 of the differential mechanism 7. The sun gear 8 is the input element, the ring gear 9 is the reaction force element, and the carrier 11 is the output element.

[0023] The differential mechanism 7 is a differential device that allows differential rotation of a pair of left and right axles 13. The differential mechanism 7 includes a differential case 12 which is a rotating member. The differential case 12 rotates integrally with the carrier 11 of the speed reducer 6. The differential mechanism 7 transmits the power transmitted from the motor 2 via the speed reducer 6 to the wheels 3 while allowing a difference in the rotational speeds of the pair of left and right axles 13.

[0024] The case 20 is a transaxle case that houses the motor 2, the speed reducer 6, and the differential mechanism 7. Inside the case 20, the motor 2, the speed reducer 6, and the differential mechanism 7 are arranged on the same axis. The case 20 houses a one-axis transaxle. The case 20 includes a first case member 21, a second case member 22, and a cover member 23.

[0025] The first case member 21 is a member that functions as a motor case and has a shape with openings on both axial sides. The second case member 22 is a member that functions as a gear case and is attached to one axial end of the first case member 21. The cover member 23 is a member that functions as a part of the motor case and is attached to the other axial end of the first case member 21. The first case member 21 and the second case member 22 are integrated by bolt fastening. The first case member 21 and the cover member 23 are integrated by bolt fastening.

[0026] In the case 20, the cover member 23, the first case member 21, and the second case member 22 are arranged in this order from the other side to the one side in the axial direction of the motor 2, forming a motor chamber 24 which is a space for housing the motor 2 and a gear chamber 25 which is a space for housing the speed reducer 6 and the differential mechanism 7.

[0027] The motor chamber 24 is formed by the cover member 23 and the first case member 21. The gear chamber 25 is formed by the first case member 21 and the second case member 22. The first case member 21 includes a partition wall portion 26 inside. The partition wall portion 26 is a wall portion that partitions the motor chamber 24 and the gear chamber 25.

[0028] Figure 2 is a diagram showing the electric circuit included in the drive unit. The drive unit 5 includes a power control unit (hereinafter referred to as PCU) 30 and a noise filter 40.

[0029] The PCU 30 controls the motor 2. The PCU 30 includes an inverter 31 that drives the motor 2. The inverter 31 is a power conversion device that converts the DC power supplied from the battery into AC power and supplies it to the motor 2. The inverter 31 includes a plurality of switching elements and performs a switching operation under the control of an electronic control device.

[0030] The noise filter 40 is electrically connected to the PCU 30. The noise filter 40 is provided in the electric circuit between the battery and the PCU 30 and is a filter for reducing noise when supplying the power from the battery to the inverter 31. The noise filter 40 is, for example, a filter for reducing EMC noise. In the electric circuit, the noise filter 40 is provided for the positive electrode wire and the negative electrode wire. In this electric circuit, a smoothing capacitor 32 is provided between the noise filter 40 and the inverter 31. The smoothing capacitor 32 smooths the power output from the noise filter 40 and supplies it to the inverter 31.

[0031] Here, with reference to FIGS. 3 to 5, the arrangement of the PCU 30 and the noise filter 40 in the drive unit 5 configured in an electromechanical integrated structure will be described.

[0032] The drive unit 5 has a structure (electromechanical integrated structure) in which the PCU 30 is integrated into the case 20. In the drive unit 5 having the electromechanical integrated structure, in addition to the PCU 30, the noise filter 40 is integrated into the case 20.

[0033] In addition, since the drive unit 5 includes a single-axis structure transaxle, as shown in FIG. 4, in a plane orthogonal to the axial direction of the motor 2, the horizontal dimensions of the case 20 are smaller than those of a case that houses a three-axis structure transaxle. Therefore, although miniaturization is possible, it becomes difficult to secure space for installing the PCU 30 and the noise filter 40. Thus, in the drive unit 5, the PCU 30 and the noise filter 40 are arranged with high space efficiency.

[0034] For comparison, when the PCU 30 and the noise filter 40 are attached to a case that houses a three-axis structure transaxle, since the differential mechanism is arranged on a different axis from the motor and at a different axial position of the motor, in a plane orthogonal to the axial direction of the motor, it is easy to secure an installation space for the PCU 30 and the noise filter 40 by utilizing the space on the axis of the differential mechanism near the motor. In contrast, since the case 20 that houses a single-axis structure transaxle is smaller in size than the case of the three-axis structure, if the PCU 30 and the noise filter 40 are arranged at the same position as in the three-axis structure, the overall shape of the drive unit 5 will become uneven. Thus, the drive unit 5 is configured to increase space efficiency while suppressing the imbalance of the overall shape.

[0035] Specifically, the PCU 30 and the noise filter 40 are attached to the first case member 21 of the case 20. The PCU 30 is separate from the noise filter 40. Since the noise filter 40 needs to be connected to the positive and negative lines, it needs to be arranged at a position close to the PCU 30. The noise filter 40 is arranged on the back side of the PCU 30 and in the space formed between the motor 2 and the PCU 30. The noise filter 40 is arranged in the space sandwiched between the motor 2 and the PCU 30.

[0036] The PCU 30 is attached to the upper part of the first case member 21 while being housed inside the PCU case. That is, the PCU case is attached to the first case member 21. A cover member 27 is attached to the upper part of the case 20. The space formed by the case 20 and the cover member 27 serves as a space for installing the PCU 30 and the noise filter 40. The noise filter 40 is integrated with the first case member 21 while being disposed in the space sandwiched between the back surface of the PCU case and the first case member 21.

[0037] Inside the case 20, an oil pipe is disposed in the space above the motor chamber 24. This oil pipe is disposed directly above the stator 2b and supplies oil for cooling the motor 2 to the upper part of the stator 2b. That is, since the space for housing the PCU 30 is restricted by this oil pipe, it is formed at a position shifted horizontally from directly above the motor 2. Further, inside the case 20, a catch tank is disposed in the space above the gear chamber 25. The catch tank stores the oil in the gear chamber 25 and catches the oil scraped up by the rotation of the speed reducer 6 and the differential mechanism 7. The oil stored in this catch tank is supplied to the oil pipe.

[0038] Therefore, as for the arrangement in the radial direction of the motor 2, the noise filter 40 is disposed in the space between the motor 2 and the PCU 30. As for the arrangement in the axial direction of the motor 2, the PCU 30 is disposed at a position overlapping a part of the motor 2 and a part of the speed reducer 6, and the noise filter 40 is disposed at a position overlapping the motor 2.

[0039] Also, the noise filter 40 is disposed in the space sandwiched between the connection part that electrically connects the motor 2 and the PCU 30 and the speed reducer 6. This connection part is a member that electrically connects the motor 2 and the inverter 31 and is configured to include a three-phase connection part composed of bus bars for each phase. For example, this three-phase connection part is composed of a connection base on which three-phase bus bars for electrically connecting the U-phase coil, the V-phase coil, and the W-phase coil of the motor 2 to the inverter 31 are installed.

[0040] The PCU 30 is difficult to freely change its aspect ratio and has a lower degree of freedom in shape compared to the noise filter 40. Therefore, the location where the PCU 30 can be installed is likely to be restricted to a place where a large planar area can be taken. And in the case 20, since the first case member 21 forming the motor chamber 24 is the member with the largest area, the PCU 30 is attached to the first case member 21.

[0041] The noise filter 40 has a higher degree of freedom in shape compared to the PCU 30. Therefore, on both sides of the accommodating portion of the noise filter 40, the connection portion between the motor 2 and the PCU 30 and the gear chamber 25 are respectively located. Even in a place where the installation space is likely to be restricted by the shape, that is, a place where it is difficult to obtain the axial length in the case 20, a space for installing the noise filter 40 can be secured.

[0042] As described above, in the drive unit 5 having an electromechanical integrated structure, by installing the noise filter 40 in the space between the motor 2 and the PCU 30, the space efficiency can be improved. Thereby, in the drive unit 5, it is possible to achieve both space saving by a one-axis structure transaxle and securing the mounting space for the noise filter 40 in the electromechanical integrated structure. Also, since the noise filter 40 is separate from the PCU 30, even if the noise filter 40 becomes larger, it is possible to mount the noise filter 40.

[0043] Also, by attaching the PCU 30 and the noise filter 40 to the first case member 21, the capacity of the catch tank can be expanded in the gear chamber 25 in the second case member 22.

[0044] Note that the PCU 30 does not necessarily have to be entirely attached to the first case member 21. Similarly, the noise filter 40 does not necessarily have to be entirely attached to the first case member 21. At least a part of the PCU 30 and the noise filter 40 may be attached to the first case member 21, and the remaining part may be attached to the second case member 22 or the cover member 23.

[0045] Also, the cover member 27 does not necessarily have to be provided. That is, the structure is not limited to the one in which the PCU 30 and the noise filter 40 are housed inside the closed space formed by the cover member 27.

[0046] Also, the noise filter 40 does not necessarily have to be entirely arranged in the space between the PCU 30 and the motor 2. That is, the noise filter 40 may be attached to the case 20 as long as at least a part of it is arranged in the space between the PCU 30 and the motor 2.

[0047] Also, the noise filter 40 does not necessarily have to be entirely arranged in the space sandwiched between the connection part that electrically connects the motor 2 and the PCU 30 and the speed reducer 6. That is, the noise filter 40 may be arranged as long as at least a part of it is arranged in the space between the connection part that electrically connects the motor 2 and the PCU 30 and the speed reducer 6.

[0048] Also, the installation locations of the PCU 30 and the noise filter 40 are not limited to the upper part of the case 20, and can be arranged at the front part, the rear part, the lower part, etc. of the case 20. An example of this modification is shown in FIGS. 6 to 9.

[0049] In the drive unit 5 in the modification, as shown in FIGS. 6 to 8, the PCU 30 is attached to the front part of the case 20. The noise filter 40 is arranged in the space between the PCU 30 and the motor 2 in the front-rear direction of the vehicle 1, and is arranged below the rotation center position of the motor 2 in the up-down direction of the vehicle 1.

[0050] In the drive unit 5 in another modification, as shown in FIG. 9, the noise filter 40 may be disposed above the rotational center position of the motor 2 in the vertical direction of the vehicle 1.

Explanation of Signs

[0051] 1 Vehicle 2 Motor 3 Wheel 4 Power transmission device 5 Drive unit 6 Reducer 7 Differential mechanism 8 Sun gear 9 Ring gear 10 Pinion gear 10a Large-diameter portion 10b Small-diameter portion 11 Carrier 12 Differential case 13 Axle 20 Case (transaxle case) 21 First case member 22 Second case member 23 Cover member 24 Motor chamber 25 Gear chamber 26 Partition portion 27 Cover member 30 Power control unit (PCU) 31 Inverter 32 Smoothing capacitor 40 Noise filter

Claims

1. A transaxle case that houses a motor, a speed reducer, and a differential mechanism, A power control unit that controls the motor, A noise filter electrically connected to the motor via the power control unit, A connection part that electrically connects the motor and the power control unit, Comprising, the power control unit and the noise filter are integrated with the transaxle case, and inside the transaxle case, the motor, the speed reducer, and the differential mechanism are arranged on the same axis, which is a drive unit, The power control unit is separate from the noise filter, The motor has a smaller diameter than the speed reducer, The noise filter is arranged in a state where at least a part of it is arranged in the space between the power control unit and the motor in the radial direction of the motor, and at least a part of it is arranged in the space sandwiched between the connection part and the speed reducer in the axial direction of the motor A drive unit characterized by the above.

2. As for the arrangement of the power control unit in the axial direction of the motor, it is arranged at a position that overlaps with a part of the motor and also overlaps with a part of the speed reducer, As for the arrangement of the noise filter in the axial direction of the motor, it is arranged at a position that overlaps with the motor The drive unit according to claim 1, characterized by the above.

3. The transaxle case, Functions as a motor case that houses the motor, and has a first case member with openings on both axial sides, Functions as a gear case that houses the speed reducer and the differential mechanism, and is a second case member attached to one axial end of the first case member, Functions as a part of the motor case, and has a cover member attached to the other axial end of the first case member, The PCU case that houses the power control unit is attached to the first case member, The noise filter is attached to the first case member in a state where it is arranged in the space between the back surface of the PCU case and the first case member The drive unit according to claim 1 or 2, characterized by the above.

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