JP2021069134A - Drive unit - Google Patents

Abstract

To suppress heat transfer from a motor to an internal component of a power converter in a configuration where the motor and power converter are integrated.SOLUTION: A drive unit includes a motor and a control unit. The control unit includes a case 31 that is integrally fixed to a motor housing, a power module 33 that is housed in the case 31, and a cooler 35. The power module 33 is located in the cooler 35. The cooler 35 includes a deformation-allowing part 35b, which is provided around the periphery of a refrigerant flow path 35a, is fixed to the case 31, and deforms to follow the thermal deformation of the case 31.SELECTED DRAWING: Figure 3

Description

The present invention relates to a drive unit.

Conventionally, a drive unit in which a first case accommodating a motor and a generator and a second case accommodating a power control unit for controlling a motor and a generator are integrated is known (see, for example, Patent Document 1). In such a drive unit, the first case and the second case are fastened and fixed by a fastening member.

Japanese Unexamined Patent Publication No. 2016-140198

By the way, in the drive unit as described above, the power control unit is susceptible to heat effect due to heat generation of the motor and the generator due to the integrated first case and second case. In such an integrated drive unit, it is desired to suppress temperature rise and thermal expansion through the first case of the second case accommodating the power control unit.

An object of the present invention is to provide a drive unit capable of suppressing heat transfer from a motor to an internal component of a power converter in a configuration in which a motor and a power converter are integrated.

In order to solve the above problems and achieve the above object, the present invention has adopted the following aspects.
(1) The drive unit according to one aspect of the present invention includes a rotary electric machine (for example, the motor 11 in the embodiment), a power converter for controlling the rotary electric machine (for example, the power module 33 in the embodiment), and the like. A housing (for example, a case 31 and a motor housing 25 in the embodiment) for accommodating the rotary electric machine and the power converter is provided, and the power converter is a semiconductor element (for example, a high side arm in the embodiment). Each transistor UH, VH, WH, UL, VL, WL of the low side arm is provided with a cooler (for example, a cooler 35 in the embodiment) in which the semiconductor element is arranged. A portion (for example, in the embodiment) provided on the outer periphery of the refrigerant passage (for example, the refrigerant passage 35a in the embodiment), fixed to the housing, and deformed following thermal deformation of the housing. It is provided with a deformation allowable portion 35b).

(2) In the drive unit according to (1) above, the thickness of the portion may be smaller than the thickness of the cooler of the portion having the refrigerant passage.

(3) In the drive unit according to (1) or (2) above, the portion may be formed in a flat plate shape.

(4) In the drive unit according to any one of (1) to (3) above, the portion may be formed at a position that does not overlap with the refrigerant passage in a plan view.

(5) In the drive unit according to (1) above, the portion may be formed in a deformed shape.

(6) In the drive unit according to (1) above, the portion may be formed of a deformable material.

According to the above (1), the cooler of the power converter is fixed to the housing via a portion that follows the housing and deforms, so that the cooler and the housing for the semiconductor element arranged in the cooler It is possible to suppress the action of stress due to thermal deformation of. By arranging the semiconductor element of the power converter in the cooler, it is possible to suppress the direct heat transfer from the housing to the semiconductor element, and it is possible to suppress the temperature rise of the semiconductor element.

In the case of (2) above, it is possible to suppress an increase in the size of the entire cooler as compared with the case where the thickness of the deformed portion is thicker than the thickness of the cooler in the portion having the refrigerant passage, for example. At the same time, it is possible to promote the deformation of the part.
In the case of (3) above, a deformable portion can be easily formed.
In the case of (4) above, the deformable portion and the housing can be easily connected by fastening or the like, and the deformation of the portion can be promoted.

In the case of (5) above, the deformable portion is arranged in the cooler and the cooler because it is formed in a deformed shape such as a corrugated plate that expands and contracts between the housing and the cooler. It is possible to suppress the deformation of the semiconductor element.
In the case of (6) above, the deformable portion is formed of a deformable material such as a material having low rigidity or an elastic material, thereby suppressing the deformation of the cooler and the semiconductor element arranged in the cooler. Can be done.

The exploded perspective view which shows the structure of the drive unit in embodiment of this invention. The sectional view which shows the structure of the drive unit in embodiment of this invention. FIG. 5 is an enlarged sectional view showing a power module and a cooler of a drive unit according to an embodiment of the present invention. The plan view which shows the power module and the cooler of the drive unit in embodiment of this invention. The figure which shows the structure of a part of the vehicle which mounts the drive unit of embodiment of this invention.

Hereinafter, an embodiment of the drive unit of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view showing the configuration of the drive unit 10 in the embodiment. FIG. 2 is a cross-sectional view showing the configuration of the drive unit 10 in the embodiment (cross-sectional view cut along a plane orthogonal to the axis O of the rotating shaft 21a of the motor 11). FIG. 3 is an enlarged cross-sectional view showing the power module 33 and the cooler 35 of the drive unit 10 in the embodiment. FIG. 4 is a plan view showing the power module 33 and the cooler 35 of the drive unit 10 in the embodiment (plan view seen from the thickness direction of the power module 33 and the cooler 35).
The drive unit 10 is mounted on the vehicle 1, for example. As shown in FIGS. 1 and 2, the drive unit 10 includes a motor 11 and a control unit 13 integrally fixed to the motor 11.

The motor 11 is, for example, a three-phase AC brushless DC motor. The three phases are the U phase, the V phase, and the W phase. The motor 11 includes a rotor 21 having a permanent magnet for a field magnet, a stator 23 having a three-phase stator winding for generating a rotating magnetic field for rotating the rotor 21, and a motor housing 25. For example, the motor 11 is an inner rotor type in which the rotor 21 is arranged inside the stator 23.

The motor 11 is connected to the transmission. The transmission is housed in, for example, a transmission case 27 fixed to the motor housing 25. The rotating shaft 21a of the rotor 21 of the motor 11 penetrates the transmission case 27 and is connected to the transmission.

The outer shape of the motor housing 25 is formed, for example, in a bottomed cylindrical shape. The motor housing 25 contains hydraulic oil (not shown) as a refrigerant in addition to the rotor 21 and the stator 23. The hydraulic oil exchanges heat with the rotor 21 and the stator 23 during the operation of the motor 11.
The motor housing 25 includes a mounting base 29 on which the control unit 13 is arranged. The outer shape of the mounting base 29 is, for example, formed in a rectangular tubular shape. The mounting base 29 includes a partition portion 29a that partitions the control unit 13 and the motor 11. The mounting base 29 is provided on the outer peripheral surface of the motor housing 25.

The control unit 13 includes a case 31, a power module 33, and a cooler 35. The outer shape of the case 31 is formed in a box shape, for example. The case 31 houses the power module 33 and the cooler 35 inside. The case 31 is integrally fixed to the mounting base 29 of the motor housing 25.
The power module 33 constitutes a power converter such as an inverter that controls the motor 11. The power converter is connected to the three-phase stator windings of the motor 11 to transfer power to and from the motor 11. The control unit 13 may include a booster circuit, a control board, a current sensor, and the like in addition to a power converter such as an inverter.

The cooler 35 cools the power module 33. The cooler 35 is, for example, a water jacket. Inside the cooler 35, a refrigerant flow path 35a connected to the supply pipe 34a and the discharge pipe 34b and through which the refrigerant flows is formed. The cooler 35 includes a plurality of fins that function as heat sinks on a part of the wall surface that forms the refrigerant flow path 35a.
As shown in FIG. 3, the power module 33 is arranged in the cooler 35. For example, the power module 33 is arranged on the surface (arrangement surface) 35A on the side opposite to the motor 11 side in the thickness direction of the cooler 35. The power module 33 is fixed to the cooler 35 by a first fastening member 37 such as a bolt.

The cooler 35 includes a deformation allowable portion 35b fixed to the case 31. The deformation allowable portion 35b is formed of, for example, an elastic material. The outer shape of the deformation allowable portion 35b is formed in a shape that easily elastically expands and contracts between the cooler 35 and the case 31, for example, a corrugated plate shape that protrudes from the main body surface 35B of the cooler 35. The corrugated plate is a plate material having a corrugated cross-sectional shape cut in the thickness direction. The thickness of the deformation allowable portion 35b is formed to be thinner than the thickness of the cooler 35 of the portion having the refrigerant flow path 35a, for example. The deformation allowable portion 35b is provided on the outer peripheral side of the refrigerant flow path 35a of the cooler 35, for example, on the outer peripheral side of the arrangement surface 35A on which the power module 33 is arranged in the cooler 35. For example, the deformation allowable portion 35b is provided at a position that does not overlap with the refrigerant flow path 35a in a plan view from the thickness direction.

The deformation allowable portion 35b is fixed to the case 31 by a second fastening member 39 such as a bolt. For example, the deformation allowable portion 35b is fixed to a protrusion 31a provided on the inner surface of the case 31. The deformation allowable portion 35b is fixed to the case 31 by a second fastening member 39, for example, at a portion of the end portion of the cooler 35 that avoids the refrigerant flow path 35a. In the cooler 35, the distance between the power module 33 and the deformation allowable portion 35b, for example, the distance L between the first fastening member 37 and the second fastening member 39, is the heat transfer from the case 31 to the power module 33. Is set to the predetermined distance required to make the value less than the specified distance.
The deformation allowable portion 35b elastically expands and contracts between the cooler 35 and the case 31 in a protruding direction from the main body surface 35B of the cooler 35 toward the case 31 and the like, following the thermal deformation of the case 31. The deformation allowable portion 35b suppresses deformation of at least the arrangement surface 35A and the peripheral portion of the arrangement surface 35A in the cooler 35 by expansion and contraction deformation between the cooler 35 and the case 31.

An example of the vehicle 1 equipped with the drive unit 10 of the present embodiment will be described below. FIG. 4 is a diagram showing a partial configuration of a vehicle 1 equipped with the drive unit 10 of the present embodiment.
As shown in FIG. 5, the vehicle 1 includes a battery 51 (BATT), a traveling drive motor 11 (MOT), and a control unit 13.
The battery 51 is, for example, a high-voltage battery that is a power source for the vehicle 1. The battery 51 includes a battery case and a plurality of battery modules housed in the battery case. The battery module includes a plurality of battery cells connected in series or in parallel. The battery 51 includes a positive electrode terminal PB and a negative electrode terminal NB connected to the DC connector 13a of the control unit 13. The positive electrode terminal PB and the negative electrode terminal NB are connected to the positive electrode end and the negative electrode end of a plurality of battery modules connected in series in the battery case.
The motor 11 generates a rotational driving force (power running operation) by the electric power supplied from the battery 51. The motor 11 may generate generated electric power by a rotational driving force input to the rotary shaft. The motor 11 may be configured to be able to transmit the rotational power of the internal combustion engine.

The control unit 13 includes a power module 33 and a capacitor unit 53 constituting a power converter 52 such as an inverter, a resistor 54, a first current sensor 55, a second current sensor 56, and an electronic control unit 57 (MOT ECU). ) And a gate drive unit 58 (G / D).

The power module 33 is connected to the three-phase stator windings of the motor 11 by, for example, a three-phase connector 13b. The power module 33 converts the DC power input from the battery 51 into three-phase AC power. The power module 33 may convert the three-phase AC power input from the motor 11 into DC power. The DC power converted by the power module 33 can be supplied to the battery 51.

The power module 33 includes a bridge circuit formed by a plurality of switching elements connected by a bridge. For example, the switching element is a transistor such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semi-conductor Field Effect Transistor). For example, in a bridge circuit, a pair of high-side arm and low-side arm U-phase transistors UH and UL, a pair of high-side arm and low-side arm V-phase transistors VH and VL, and a pair of high-side arm and low-side arm. The W-phase transistors WH and WL are bridge-connected, respectively.

In each transistor UH, VH, WH of the high side arm, a collector is connected to the positive electrode bus bar PI to form the high side arm. In each phase, each positive electrode bus bar PI of the high side arm is connected to the positive electrode bus bar 53p of the capacitor unit 53.
The emitters of each of the transistors UL, VL, and WL of the low side arm are connected to the negative electrode bus bar NI to form the low side arm. In each phase, each negative electrode bus bar NI of the low side arm is connected to the negative electrode bus bar 53n of the capacitor unit 53.
The connection between the positive electrode bus bars PI, 53p and the connection between the negative electrode bus bars NI, 53n are, for example, smaller than bolt fastening and laser welded or clipped so as to suppress thermal damage to the insulated portion. Connection etc. are adopted.

In each phase, the emitters of the transistors UH, VH, and WH of the high side arm are connected to the collectors of the transistors UL, VL, and WL of the low side arm at the connection point TI.
The input / output bus bar 59 forming the connection point TI in each phase of the power module 33 is connected to the input / output terminal Q1. The input / output terminal Q1 is connected to the three-phase connector 13b. The connection point TI of each phase of the power module 33 is connected to the stator winding of each phase of the motor 11 via the input / output bus bar 59, the input / output terminal Q1, and the three-phase connector 13b.
The bridge circuit includes a diode connected between the collector and the emitter of each transistor UH, UL, VH, VL, WH, and WL in the forward direction from the emitter to the collector.

The power module 33 turns on (conducts) / turns off the transistor pairs of each phase based on the gate signal which is a switching command input from the gate drive unit 58 to the gates of the transistors UH, VH, WH, UL, VL, and WL. Switch off). The power module 33 converts the DC power input from the battery 51 into three-phase AC power, and sequentially commutates the energization of the three-phase stator windings of the motor 11 to AC the three-phase stator windings. U-phase current, V-phase current, and W-phase current are energized. The power module 33 is a three-phase AC power output from the three-phase stator windings of the motor 11 by on (conducting) / off (disconnecting) driving of the transistor pairs of each phase synchronized with the rotation of the motor 11. May be converted to DC power.

The capacitor unit 53 includes a smoothing capacitor 53a and a noise filter 53b.
The smoothing capacitor 53a is connected between the plurality of positive electrode bus bars PI and the negative electrode bus bar NI of the power module 33 via the positive electrode bus bar 53p and the negative electrode bus bar 53n. The smoothing capacitor 53a smoothes the voltage fluctuation generated by the on / off switching operation of each of the transistors UH, UL, VH, VL, WH, and WL of the power module 33.

The noise filter 53b is connected between the plurality of positive electrode bus bars PI and the negative electrode bus bar NI of the power module 33 via the positive electrode bus bar 53p and the negative electrode bus bar 53n. The noise filter 53b includes two capacitors connected in series. The connection points of the two capacitors are connected to the body ground of the vehicle 1 and the like.
The resistor 54 is connected between the plurality of positive electrode bus bars PI and the negative electrode bus bar NI of the power module 33 via the positive electrode bus bar 53p and the negative electrode bus bar 53n.

The first current sensor 55 forms a connection point TI for each phase of the power module 33, is arranged on an input / output bus bar 59 connected to the input / output terminal Q1, and has a U-phase, V-phase, and W-phase current. Is detected. The second current sensor 56 is arranged between the resistor 54 and the DC connector 13a, and detects the output current of the battery 51.
Each of the first current sensor 55 and the second current sensor 56 is connected to the electronic control unit 57 by a signal line.

The electronic control unit 57 controls each operation of the motor 11. For example, the electronic control unit 57 is a software function unit that functions by executing a predetermined program by a processor such as a CPU (Central Processing Unit). The software function unit is an ECU (Electronic Control Unit) equipped with a processor such as a CPU, a ROM (Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and an electronic circuit such as a timer. is there. At least a part of the electronic control unit 57 may be an integrated circuit such as an LSI (Large Scale Integration). For example, the electronic control unit 57 executes current feedback control using the current detection value of the first current sensor 55 and the current target value corresponding to the torque command value for the motor 11, and inputs the control signal to the gate drive unit 58. To generate. For example, the electronic control unit 57 executes current feedback control using the current detection value of the first current sensor 55 and the current target value corresponding to the regeneration command value for the motor 11, and inputs the control signal to the gate drive unit 58. May be generated. The control signal is a signal indicating the timing for driving the transistors UH, VH, WH, UL, VL, and WL of the power module 33 on (conducting) / off (disconnecting). For example, the control signal is a pulse width modulated signal or the like.

The gate drive unit 58 actually drives the transistors UH, VH, WH, UL, VL, and WL of the power module 33 on (conducting) / off (disconnecting) based on the control signal received from the electronic control unit 57. Generate a gate signal. For example, the gate drive unit 58 amplifies the control signal, shifts the level, and the like to generate the gate signal.

As described above, according to the drive unit 10 of the present embodiment, the case 31 with respect to the cooler 35 and the power module 33 arranged in the cooler 35 by the deformation allowable portion 35b between the cooler 35 and the case 31. The action of stress due to thermal deformation can be suppressed.
By arranging the power module 33 on the arrangement surface 35A of the cooler 35, the adhesion between the power module 33 and the cooler 35 can be increased, and the cooling efficiency of the power module 33 can be improved. This makes it possible to promote the miniaturization of the power module 33. Since the power module 33 is not in direct contact with the case 31, it is possible to suppress direct heat transfer from the case 31 to the power module 33. As a result, heat transfer from the motor 11 side to the power module 33 side, which becomes relatively hot, can be suppressed.
For example, since the thickness of the deformation allowable portion 35b is thinner than the thickness of the cooler 35 in the portion having the refrigerant flow path 35a, it is possible to suppress an increase in the size of the entire cooler 35 and the deformation allowable portion 35b. It is possible to promote the deformation of.
Since the deformation allowable portion 35b is provided at a position where it does not overlap with the refrigerant flow path 35a in a plan view from the thickness direction, the deformation allowable portion 35b and the case 31 are easily connected by the second fastening member 39. At the same time, it is possible to promote the deformation of the deformation allowable portion 35b.

Hereinafter, a modified example of the embodiment will be described.
In the above-described embodiment, the deformation allowable portion 35b is said to be formed in a shape that is elastically easily stretched and deformed, but the present invention is not limited to this, and the deformation allowable portion 35b may be formed in a simple shape such as a flat plate shape.
In the above-described embodiment, the deformable portion 35b is formed of an elastic material, but the present invention is not limited to this, and the deformable portion 35b may be formed so as to be plastically deformable by, for example, a material having low rigidity.

The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

10 ... drive unit, 11 ... motor (rotary electric machine), 13 ... control unit, 25 ... motor housing (housing), 31 ... case (housing), 33 ... power module (power converter), 35 ... cooler, 35a ... Refrigerant flow path (refrigerant passage), 35b ... Deformation allowable part (part)

Claims (6)

With a rotary electric machine
The power converter that controls the rotary electric machine and
A housing that houses the rotary electric machine and the power converter,
With
The power converter
With semiconductor elements
A cooler in which the semiconductor element is arranged and
With
The cooler
A drive unit provided on the outer periphery of a refrigerant passage, fixed to the housing, and provided with a portion that deforms following thermal deformation of the housing. The drive unit according to claim 1, wherein the thickness of the portion is thinner than the thickness of the cooler of the portion having the refrigerant passage. The drive unit according to claim 1 or 2, wherein the portion is formed in a flat plate shape. The drive unit according to any one of claims 1 to 3, wherein the portion is formed at a position that does not overlap with the refrigerant passage in a plan view. The drive unit according to claim 1, wherein the portion is formed in a deformed shape. The drive unit according to claim 1, wherein the portion is formed of a deformable material.

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