JP2021028183A - Driving device of vehicle - Google Patents

Abstract

To provide a driving device of a vehicle, which can improve cooling efficiency with a compact and simple configuration.SOLUTION: A driving device 10 of a vehicle comprises: motors 1 and 2 which drive left and right wheels of the vehicle; a gear box 3 that has gear mechanism, which amplifies torque of the motors 1 and 2 and transmits the torque to each of the left and right wheels, built-in and is sandwiched between the motors 1 and 2; and a power inverter 4 that inverts direct-current power to alternate-current power and then supplies the power to the motors 1 and 2. The gear box 3 is arranged to be offset in radial directions of the left motor 1 and the right motor 2, between left and right motor housings 11 to which the left motor 1 and the right motor 2 respectively are internally fitted. The power inverter 4 is fixed to be bridged between the left and right motor housings 11, and a portion of the power inverter 4 is arranged in a recessed part 8 surrounded by the left and right motor housings 11 and the gear box 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a drive device that drives the left and right wheels of a vehicle.

Conventionally, a drive device for driving the left and right wheels of a vehicle with two motors (electric motors) is known. For example, it has been proposed that individual motors are connected to each of the left and right wheels so that the left and right wheels can be driven independently of each other. In such a drive device, by making the driving force of the left and right motors different, it is possible to cause a difference in rotation speed and a difference in torque between the left and right wheels. As a result, the turning performance of the vehicle and the stability of the vehicle body during turning can be improved (see Patent Document 1).

JP-A-2017-184523

The technique described in Patent Document 1 employs a structure in which an inverter that supplies electric power to a motor is integrated with a speed reducer or a motor case. Such a structure has a problem that the heat generated by the motor or the inverter tends to be trapped in the drive device, and it is difficult to improve the cooling efficiency of the drive device. To solve such a problem, it is conceivable to arrange the inverter at a position separated from the motor and disperse the heat generated by each of them to improve the cooling efficiency. However, the power supply line (for example, a power supply cable or a bus bar) connecting the inverter and the motor becomes long, and the electric resistance increases. In addition, the size of the entire device becomes large, and the space utilization efficiency decreases.

One of the purposes of this case is to provide a vehicle drive device which has been devised in view of the above-mentioned problems and can improve the cooling efficiency with a compact and simple configuration. Not limited to this purpose, it is also an action and effect derived from each configuration shown in the "mode for carrying out the invention" described later, and it is also another purpose of the present invention to exert an action and effect that cannot be obtained by the conventional technique. Can be positioned as.

(1) The disclosed vehicle drive device includes a left motor and a right motor that drive the left and right wheels of the vehicle, a gearbox, and a power conversion device. The gearbox has a built-in gear mechanism that amplifies the torque of the left motor and the right motor and transmits them to each of the left and right wheels, and is sandwiched between the left motor and the right motor. The power conversion device converts DC power into AC power and supplies power to both the left motor and the right motor. Further, the gearbox is arranged so as to be offset in the radial direction of the left motor and the right motor with respect to the left and right motor housings in which the left motor and the right motor are respectively installed. Further, the power conversion device is fixed in a state of being bridged between the left and right motor housings, and a part of the power conversion device is arranged in a recess surrounded by the left and right motor housings and the gearbox.

By fixing the power converter in a state of being bridged between the left and right motor housings, the cooling efficiency can be improved with a compact and simple configuration.

It is a schematic perspective view which shows the drive device of the vehicle as an embodiment disassembled. It is a schematic front view of a drive device. It is a schematic cross-sectional view for demonstrating the internal structure of a drive device.

[1. Constitution]
Hereinafter, the vehicle drive device 10 as an embodiment will be described with reference to the drawings. The drive device 10 is interposed between the left and right wheels of the vehicle. The drive device 10 has a function of adjusting the magnitude of the yaw moment by actively controlling the magnitude of the drive / braking force (drive / braking torque) of the left and right wheels to stabilize the posture of the vehicle. As shown in FIGS. 1 to 3, the drive device 10 includes a left motor 1, a right motor 2, a gearbox 3, and a power conversion device 4 (inverter). The front, rear, left, right, up and down directions in the drawing represent directions determined with reference to the driver of the vehicle on which the drive device 10 is mounted.

The left motor 1 and the right motor 2 are electric motors that drive the left and right wheels of the vehicle. The left motor 1 is connected (or intervened) to at least a power transmission path connected to the left wheel axle 27. Similarly, the right motor 2 is connected (or intervened) to at least a power transmission path connected to the right wheel axle 28. The left motor 1 and the right motor 2 are yaw moment generation sources that generate turning force by increasing or decreasing the driving / braking force of at least the left and right wheels in electric vehicles and hybrid vehicles equipped with other drive motors and engines. Functions as. In an electric vehicle not equipped with another drive motor, in addition to the above functions, it also has a function as a vehicle drive source.

Hereinafter, when it is not necessary to distinguish between the left motor 1 and the right motor 2, they are also simply referred to as motors 1 and 2. The motors 1 and 2 of the present embodiment are synchronous motors (synchronous AC motors) and can operate independently of each other. Further, the motors 1 and 2 have a function as a generator as well as an electric motor. The electric power for operating the motors 1 and 2 is supplied from a traveling battery mounted on the vehicle or an in-vehicle power generation system (generator, fuel cell, diesel power generation system, etc.). In addition, instead of the synchronous motor, another AC motor (induction motor, commutator motor) or DC motor may be used.

As shown in FIGS. 2 and 3, the left and right motors 1 and 2 have a symmetrical structure in the top view and the front view of the vehicle. The internal structure of the right motor 2 is almost the same as that of the left motor 1 except that it is symmetrical. Explaining the internal structure of the left motor 1 in detail, the exterior thereof is divided into two members, a motor housing 11 and a motor cover 12. Further, a stator 23, a rotor 24, and a motor shaft 25 are built in the left motor 1.

The stator 23 is, for example, a stator having a structure in which a coil is wound around a laminated iron core formed by laminating insulating steel plates and is fixed to the motor housing 11. The stator 23 is dispersedly arranged at a plurality of locations around a predetermined axis so as to form a cylindrical surface. The rotor 24 is, for example, a cylindrical rotor in which a permanent magnet is inserted in a laminated iron core formed by laminating insulating steel plates. The rotor 24 is loosely inserted inside the stator 23 in a state concentric with the central shaft thereof, and is fixed to the shaft-shaped motor shaft 25. The motor shaft 25 is pivotally supported by the motor housing 11 and the motor cover 12 via bearings (not shown). By changing the frequency of the AC power applied to the stator 23, the rotational speed of the magnetic field inside the stator 23 is changed, and the angular velocities of the rotor 24 and the motor shaft 25 are changed. One end of the motor shaft 25 is connected to a gear mechanism 26 built in the gearbox 3.

The motor housing 11 accommodates the main parts of the left motor 1, such as the stator 23 and the rotor 24. The shape of the motor housing 11 is a tubular shape in which the main parts of the motors 1 and 2 are housed, and has two openings. The motor housing 11 is attached to the gearbox 3 in a posture in which the two openings face left and right. Further, the motor housing 11 is shaped so as to project upward from the upper end of the gearbox 3 when attached to the gearbox 3. That is, the motor housing 11 is arranged offset on the left and right sides of the gearbox 3 in the radial direction of the left motor 1 and the right motor 2 (direction orthogonal to the motor shaft 25). As a result, a recess 8 surrounded by the left and right motors 1 and 2 and the gearbox 3 is formed above the gearbox 3. Of the two openings, one located on the left and right ends of the drive device 10 is closed with the motor cover 12 attached. The other opening is joined to the side surface of the gearbox 3 so as to communicate with the inside of the gearbox 3.

The motor cover 12 closes the outer side surfaces (the left side surface of the left motor 1 and the right side surface of the right motor 2) in the vehicle width direction in the opening of the motor housing 11. A known mounting structure can be adopted as the mounting structure of the motor cover 12. For example, flanges 19 and 20 may be formed as shown in FIGS. 2 and 3, and these may be joined and fixed. The flanges 19 and 20 extend outward from the open ends of the motor housing 11 and the motor cover 12 along the opening surface. By fastening and fixing (or welding and fixing) the flanges 19 and 20 in surface contact with each other, the sealability of the motors 1 and 2 at the attachment point of the motor cover 12 to the motor housing 11 is improved.

The gearbox 3 is a driving force transmission device sandwiched between the left motor 1 and the right motor 2. The gearbox 3 has a gearbox housing 13 forming an exterior and a gear mechanism 26 built therein. The gear mechanism 26 is a mechanism that amplifies at least the torque of the left motor 1 and the right motor 2 and transmits the torque to each of the left and right wheels. The gear mechanism 26 of the present embodiment includes a mechanism (for example, a differential gear mechanism, a planetary gear mechanism, etc.) for causing a drive / braking difference between the left wheel axle 27 and the right wheel axle 28. Further, the gear mechanism 26 is connected to a left wheel axle 27 connected to the left wheel of the vehicle and a right wheel axle 28 connected to the right wheel.

As the mounting structure of the motor housing 11 and the gearbox housing 13, the same structure as that of the motor housing 11 and the motor cover 12 can be adopted. For example, flanges 21 and 22 may be formed as shown in FIGS. 2 and 3, and these may be joined and fixed. The flanges 21 and 22 extend outward from the open ends of the motor housing 11 and the gearbox housing 13 along the opening surface. By fastening and fixing (or welding and fixing) the flanges 21 and 22 in a state of surface contact, the sealing performance at these joint surfaces is improved.

The power converter 4 (inverter) is a converter (DC-AC inverter) that mutually converts the power of the DC circuit (DC power) and the power of the AC circuit in which the motors 1 and 2 are interposed (AC power). is there. The power conversion device 4 has a function of converting DC power into AC power and supplying power to both the left motor 1 and the right motor 2. When the motors 1 and 2 are power running, the DC power is converted into AC power by the power conversion device 4 and supplied to the motors 1 and 2. When the motors 1 and 2 generate electricity, the AC power generated on the motors 1 and 2 is converted into DC power by the power converter 4. In the present embodiment, the power conversion device 4 and the motors 1 and 2 are connected by a three-phase AC power supply line (power supply cable, bus bar, etc.).

The power converter 4 includes a base plate 5, a capacitor 6, and a semiconductor module 7. The base plate 5 is a rectangular plate-shaped member (base plate) fixed to each of the left motor 1 and the right motor 2. The base plate 5 is made of a material having low thermal resistance. The capacitor 6 and the semiconductor module 7 are attached to the base plate 5. In the example shown in FIG. 1, the capacitor 6 is fixed to the lower surface side of the base plate 5, and the semiconductor module 7 is fixed to the upper surface side of the base plate 5.

The capacitor 6 is an electronic component for smoothing the electric power supplied to the motors 1 and 2. When the power conversion device 4 is a current control type inverter, the capacitor 6 is interposed in, for example, a power supply line for AC power converted by the power conversion device 4. By connecting each phase of the three-phase AC power supply line with a circuit in which a capacitor 6 is interposed, each capacitor 6 functions as a kind of filter and the current is stabilized. When the power conversion device 4 is a voltage-controlled inverter, the voltage is stabilized by interposing a capacitor 6 in parallel on the input side of DC power.

The semiconductor module 7 is a power module formed by forming a three-phase bridge circuit including a plurality of switching elements and diodes on a substrate (electronic circuit board, substrate). By intermittently switching the connection state of each switching element, three-phase AC power is generated. As the switching element, a semiconductor element such as a thyristor, an IGBT (Insulated Gate Bipolar Transistor), or a power MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) is used.

The upper surface cover 14 is attached to the upper surface of the base plate 5, and the lower surface cover 15 is attached to the lower surface. The semiconductor module 7 is arranged in a space surrounded by the base plate 5 and the top cover 14. Further, the condenser 6 is arranged in a space surrounded by the base plate 5 and the lower surface cover 15. The upper surface cover 14 and the lower surface cover 15 are made of a material having low thermal resistance.

As shown in FIG. 3, the top cover 14 is formed in a container shape having a size capable of accommodating the semiconductor module 7 inside. Further, the lower surface cover 15 is formed in a container shape having a size capable of accommodating the condenser 6 inside. Inside the wall body of the lower surface cover 15, a cover cooling passage 16 through which a refrigerant for cooling the condenser 6 flows is formed. Similarly, a plate cooling passage 17 through which the refrigerant flows is formed inside the base plate 5. These cooling passages 16 and 17 are in a communicating state. The cover cooling passage 16 extends in the front-rear direction on the left and right sides of the condenser 6, and extends in the vertical direction toward the plate cooling passage 17. Further, the plate cooling passage 17 is formed in a plane shape having a size overlapping with the semiconductor module 7 when viewed from above.

The power conversion device 4 is fixed in a state of being bridged between the left and right motor housings 11 in which each of the left motor 1 and the right motor 2 is incorporated. For example, as shown in FIGS. 2 and 3, in the power conversion device 4, the left end portion in the vehicle width direction is placed on the left motor housing 11 in which the left motor 1 is installed, and the right end portion is the right motor. It is mounted in a posture of being placed on the motor housing 11 on the right side in which the 2 is installed. The power conversion device 4 is in a state of being bridged between the left and right motor housings 11. By fixing the left and right motor housings 11 with the base plate 5 extending in the vehicle width direction, the vibration damping and quietness of the motors 1 and 2 are improved.

A part of the power conversion device 4 is arranged in a recess 8 surrounded by the left and right motor housings 11 and the gearbox 3. Further, a part of the power conversion device 4 is arranged inside the recess 8 at a predetermined interval with respect to the gearbox 3. Preferably, they are arranged at intervals with respect to a portion other than the fixed portion with the motor housing 11. As a result, the power conversion device 4 is in a state of floating above the gearbox 3. The running wind can pass through the space sandwiched between the gearbox 3 and the power conversion device 4 when the vehicle is running. Therefore, the motors 1, 2, the gearbox 3, and the power conversion device 4 are easily air-cooled, and the cooling performance of the drive device 10 is improved.

In the example shown in FIGS. 2 and 3, the condenser 6 and the cover cooling passage 16 are arranged inside the recess 8. As a result, the capacitor 6 is efficiently cooled, and the current and voltage of the AC power supplied to the motors 1 and 2 are easily stabilized. Further, since the refrigerant flowing inside the cover cooling passage 16 is efficiently cooled, the base plate 5 and the semiconductor module 7 are also efficiently cooled, and the current and voltage of the AC power supplied to the motors 1 and 2 are stable. It will be easier to do.

As shown in FIGS. 2 and 3, the power conversion device 4 is arranged between the left and right flanges 19 and 20 in a front view. The flanges 19 and 20 of the left motor 1 are arranged on the left side of the center positions of the stator 23 and the rotor 24 built in the left motor 1 in the vehicle width direction. Similarly, the flanges 19 and 20 of the right motor 2 are arranged on the right side of the center positions of the stator 23 and the rotor 24 built in the right motor 2 in the vehicle width direction. As a result, the positions of the flanges 19 and 20 move to the outside in the vehicle width direction as compared with the existing drive device 10, and a space for mounting the power conversion device 4 is secured. Further, by arranging the power conversion device 4 between the left and right flanges 19 and 20, the height dimension of the drive device 10 becomes compact, and the vehicle mountability is improved.

The power conversion device 4 of the present embodiment is fastened and fixed to the upper surfaces of the motors 1 and 2 with a fixture (for example, a bolt, a press-fit pin, etc.) via a plurality of bosses 9. The boss 9 is projected upward from the outer surface of the motor housing 11 in each of the motors 1 and 2. The general shape of the boss 9 is a cylindrical shape having a cylindrical shaft extending in the vertical direction, and a shaft hole for fitting a fixture is provided on the top surface thereof. By providing the plurality of bosses 9, the fixed posture of the power conversion device 4 mounted on the outer surface of the motor housing 11 is stabilized. The number of bosses 9 may be at least one for each of the motors 1 and 2, but two or more may be provided for each of the motors 1 and 2 in consideration of stability.

[2. Action / effect]
(1) In the above-described embodiment, the power conversion device 4 is fixed in a bridged state between the left and right motor housings 11, and a part of the power conversion device 4 is connected to the left and right motor housings 11 and the gearbox 3. It is arranged in the recess 8 surrounded by. With such a structure, the power conversion device 4 can be arranged in an empty space above the motors 1 and 2, and the space utilization efficiency of the vehicle can be improved. Further, the size of the drive device 10 can be made compact, and the vehicle mountability of the drive device 10 can be improved. In addition, since the motors 1 and 2 and the power conversion device 4 are formed separately, the heat dissipation of each of the motors 1 and 2 and the power conversion device 4 can be improved, and the cooling efficiency of the drive device 10 can be improved. Can be improved. Further, the distance between the power conversion device 4 and the motors 1 and 2 can be shortened, and the power line for driving the motors 1 and 2 can be shortened. Further, since the left and right motors 1 and 2 are integrally fixed by the base plate 5 extending in the vehicle width direction, the vibration damping and quietness of the motors 1 and 2 can be improved. As described above, according to the above-described embodiment, the cooling efficiency can be improved with a compact and simple configuration.

(2) In the above-described embodiment, a part of the power conversion device 4 is arranged inside the recess 8 at a predetermined interval with respect to the gearbox 3. With such a structure, the power conversion device 4 can be floated and fixed on the gearbox 3, and each of the motors 1, 2, the gearbox 3, and the power conversion device 4 can be efficiently air-cooled. Therefore, the cooling performance of the drive device 10 can be improved.

(3) As shown in FIGS. 2 and 3, in the above-described embodiment, the capacitor 6 is arranged on the lower surface side of the base plate 5. The condenser 6 is suspended from the base plate 5 inside the recess 8. By arranging the capacitors 6 with respect to the gearbox 3 at predetermined intervals in this way, the cooling efficiency of the capacitors 6 can be further improved, and the current of the AC power supplied to the motors 1 and 2 and the current can be increased. The voltage can be stabilized.

(4) In the above-described embodiment, the periphery of the condenser 6 is covered by the lower surface cover 15 in which the cover cooling passage 16 is formed. With such a structure, the cooling efficiency of the refrigerant flowing inside the cover cooling passage 16 can be further improved, and the cooling performance of the drive device 10 can be further improved. Further, by providing the cover cooling passage 16, the thickness of the plate cooling passage 17 can be reduced, and the height dimension of the drive device 10 can be made compact.

(5) As shown in FIGS. 2 and 3, in the above-described embodiment, the power conversion device 4 is arranged between the left and right flanges 19 and 20. With such a structure, the height dimension of the drive device 10 can be made compact as compared with the case where the power conversion device 4 is arranged on the flanges 19 and 20. As a result, for example, when the drive device 10 is arranged under the floor of the vehicle, the distance from the drive device 10 to the road surface can be increased, and the drive device 10 is damaged by flying stones from the road surface or foreign matter on the road surface. It is possible to reduce the occurrence of failures and improve the reliability of the product.

(6) In the above-described embodiment, the semiconductor module 7 is fixed to the upper surface side of the base plate 5, and the capacitor 6 is fixed to the lower surface side. By mounting the semiconductor module 7 and the capacitor 6 separately on both sides of the base plate 5 in this way, the area of the plate surface of the base plate 5 can be halved, and the size of the power conversion device 4 in the top view can be reduced. Can be done. Therefore, the size of the drive device 10 can be further reduced, and the vehicle mountability of the drive device 10 can be improved.

(7) As shown in FIGS. 1 and 3, in the above-described embodiment, the power conversion device 4 is fixed to the motor housing 11 via a plurality of bosses 9. By providing the plurality of bosses 9, the fixed posture of the power conversion device 4 mounted on the outer surface of the motor housing 11 can be stabilized. Further, for example, when the drive device 10 is arranged under the floor of the vehicle, it becomes easy to make the upper surface of the power conversion device 4 substantially parallel to the floor panel. Therefore, the vehicle mountability of the drive device 10 can be further improved.

[3. Modification example]
The above embodiment is merely an example, and there is no intention of excluding the application of various modifications and techniques not specified in the present embodiment. Each configuration of the present embodiment can be variously modified and implemented without departing from the gist thereof. In addition, it can be selected as needed, or can be combined as appropriate.

In the above-described embodiment, the drive device 10 in which the left and right motor shafts 25 are connected to the gear mechanism 26 is illustrated, but the power transmission path of the left wheel and the power transmission path of the right wheel may be separated. At least, in the drive device 10 in which the gearbox 3 incorporating the gear mechanism 26 is sandwiched between the left and right motors 1 and 2, the power conversion device 4 is bridged between the left and right motor housings 11 and the power conversion device 4 is bridged. By arranging a part of 4 in the recess 8 surrounded by the left and right motor housings 11 and the gearbox 3, the same effect as that of the above-described embodiment can be obtained.

In the above-mentioned power conversion device 4, the capacitor 6 is arranged on the lower surface side of the base plate 5, but the capacitor 6 may be arranged on the upper surface side of the base plate 5, or the semiconductor module 7 is arranged on the lower surface side of the base plate 5. You may. By arranging the semiconductor module 7 on the lower surface side of the base plate 5, the cooling efficiency of the semiconductor module 7 can be further improved, and the current and voltage of the AC power supplied to the motors 1 and 2 can be stabilized. Further, in this case, if the capacitor 6 is arranged on the upper surface side of the base plate 5, the power conversion device 4 can be configured in the same size as the above-described embodiment, and the vehicle mountability of the drive device 10 can be improved. Can be done.

1 Left motor 2 Right motor 3 Gearbox 4 Power converter (inverter)
5 Base plate 6 Condenser 7 Semiconductor module 8 Recess 9 Boss 10 Drive device 11 Motor housing 12 Motor cover 13 Gearbox housing 14 Top cover 15 Bottom cover 16 Cover cooling passage 17 Plate cooling passage

Claims (8)

The left and right motors that drive the left and right wheels of the vehicle,
A gearbox that has a built-in gear mechanism that amplifies the torque of the left motor and the right motor and transmits them to each of the left and right wheels, and is sandwiched between the left motor and the right motor.
A power conversion device that converts DC power into AC power and supplies power to both the left motor and the right motor is provided.
The gearbox is arranged so as to be offset in the radial direction of the left motor and the right motor with respect to the left and right motor housings in which each of the left motor and the right motor is installed.
The power conversion device is fixed in a state of being bridged between the left and right motor housings, and a part of the power conversion device is arranged in a recess surrounded by the left and right motor housings and the gearbox. A vehicle drive device, characterized in that. The vehicle drive device according to claim 1, wherein a part of the power conversion device is arranged inside the recess with a predetermined distance from the gearbox. The vehicle driving device according to claim 2, wherein a part of the power conversion device includes a capacitor. The vehicle driving device according to claim 2 or 3, wherein a part of the power conversion device includes a semiconductor module. The vehicle drive device according to any one of claims 2 to 4, wherein a part of the power conversion device includes a cooling circuit. It has a flange formed by abutting the left and right motor housings and the motor cover that closes the end faces thereof.
The vehicle drive device according to any one of claims 1 to 5, wherein the power conversion device is fixed to the left and right motor housings between the left and right flanges. The power conversion device is characterized by having a base plate bridged and fixed between the left and right motor housings, a capacitor attached to one surface of the base plate, and a semiconductor module attached to the other surface of the base plate. The vehicle driving device according to any one of claims 1 to 6. Claims 1 to 7 include a plurality of bosses that are projected upward from the outer surface of the left and right motor housings and to which fixtures for fixing the power conversion device are fastened. The vehicle driving device according to any one of the above items.

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