JP6800261B2 - Electric drive - Google Patents

Description

The present invention relates to an electric drive device and an electric power steering device, and more particularly to an electric drive device and an electric power steering device having a built-in electronic control device.

In the general industrial machinery field, mechanical control elements are driven by electric motors, but recently, electronic control units consisting of semiconductor elements that control the rotational speed and rotational torque of electric motors are electrically operated. So-called mechanical and electrical integrated electric drive devices that are integrated into the motor are beginning to be adopted.

As an example of an electric drive device integrated with electromechanics, for example, in an electric power steering device of an automobile, the rotation direction and rotation torque of the steering shaft that is rotated by the driver operating the steering wheel are detected, and the rotation torque is detected. The electric motor is driven so as to rotate in the same direction as the rotation direction of the steering shaft based on the detected value, and the steering assist torque is generated. In order to control this electric motor, an electronic control unit (ECU: Electronic Control Unit) is provided in the power steering device.

As a conventional electric power steering device, for example, the one described in Japanese Patent Application Laid-Open No. 2013-60119 (Patent Document 1) is known. Patent Document 1 describes an electric power steering device including an electric motor unit and an electronic control unit. The electric motor of the electric motor unit is housed in a motor housing having a tubular portion made of aluminum alloy or the like, and the substrate on which the electronic components of the electronic control unit are mounted is different from the output shaft in the axial direction of the motor housing. It is housed in an ECU housing arranged on the opposite side. The substrate housed inside the ECU housing includes a power supply circuit unit, a power conversion circuit unit having a power switching element such as a MOSFET for driving and controlling an electric motor, or an IGBT, and a control circuit unit for controlling the power switching element. The output terminal of the power switching element and the input terminal of the electric motor are electrically connected via a bus bar.

Then, electric power is supplied from the power supply to the electronic control unit housed in the ECU housing via the connector terminal assembly made of synthetic resin, and detection signals such as the operating state are supplied from the detection sensors. .. The connector terminal assembly functions as a lid, is connected to the electronic control unit so as to close the opening formed in the ECU housing, and is fixed to the outer surface of the ECU housing by fixing bolts.

In addition to this, as an electric drive device in which an electronic control unit and an electric motor unit are integrated, an electric brake, an electric hydraulic controller for various hydraulic control, and the like are known.

Japanese Unexamined Patent Publication No. 2013-60119

By the way, since the electric power steering device described in Patent Document 1 is arranged in the engine room of an automobile, it is necessary to be compact. In particular, recently, many auxiliary equipment such as exhaust gas countermeasure equipment and safety countermeasure equipment have tended to be installed in the engine room of automobiles, and various auxiliary equipment including electric power steering equipment should be made as small as possible. It is required to reduce the number of parts.

Then, in the electric power steering device having the configuration as described in Patent Document 1, the power supply circuit unit, the power conversion circuit unit, and the control circuit unit are mounted on two boards installed along the radial direction. .. For this reason, the number of electrical components required to control the electric motor is roughly determined. Therefore, when the electrical components with these components are mounted on two boards, the ECU that houses the electronic control unit is used. The housing naturally grows in the radial direction.

Further, in the electric power steering device, safety is particularly required for steering an automobile, and it is necessary to provide an electronic control unit having a redundant system such as a dual system. Therefore, two systems of the same electronic control unit are required as the configuration of the redundant system, and the ECU housing tends to be further large from this point as well.

Due to the structure of the electric power steering device, the axial length is relatively limited in the longitudinal direction, and the increase in size in the radial direction tends to be restricted. Therefore, the current situation is that the electric drive device is required to be miniaturized in the radial direction. In addition to this, the electric components constituting the power supply circuit section and the power conversion circuit section generate a large amount of heat, and when the size is reduced, it is necessary to efficiently dissipate the heat to the outside.

Further, the substrate of the electronic control unit is fixed to the heat radiating substrate. In this type of fixing method, a mounting flange is formed on the outer periphery of the heat radiating substrate, and the mounting flange and the outer periphery of the motor housing are fixed with fixing bolts. It is generally well known. However, when the bolts are fixed on the outer peripheral side in this way, the size tends to increase in the radial direction by this amount.

An object of the present invention is to prevent an electric drive device including an electric motor unit integrated with an electronic control unit having a redundant system from becoming large in the radial direction, and to reduce the number of parts as much as possible to simplify the configuration. It is an object of the present invention to provide a new electric drive device and an electric power steering device having a heat dissipation structure.

A feature of the present invention is that the motor housing containing the electric motor that drives the mechanical control element and the extension line of the rotation shaft of the electric motor on the end surface of the motor housing on the side opposite to the output portion of the rotation shaft of the electric motor. A control circuit provided with a heat dissipation base extending in the direction of the rotation axis opposite to the output unit, a power conversion circuit board having a switching element for driving and controlling an electric motor, and a control circuit board for controlling the switching element. The substrate is in an electric motor , which is arranged along the direction in which the heat dissipation base extends and is attached to the heat dissipation base .

According to the present invention, the electric drive device is provided by fixing the control circuit board of the electronic control unit, which also extends along the rotation axis direction, to the heat radiation substrate extending along the rotation axis direction of the electric motor so as to be thermally conductive. The size in the radial direction can be reduced to reduce the size. Further, since the heat from each substrate is radiated to the housing of the electric motor portion via the heat radiating substrate, the heat from the substrate can be efficiently radiated to the outside even when the size is reduced.

It is an overall perspective view of the steering apparatus as an example to which this invention is applied. It is an overall perspective view of the conventional electric power steering apparatus. It is an exploded perspective view of the electric power steering apparatus which becomes one Embodiment of this invention. It is a perspective view which shows the state which mounted the rotation angle detection board on the electric motor part. It is a perspective view of the heat dissipation base attached to the electric motor part. It is a perspective view which shows the state which the heat dissipation base is mounted on the electric motor part. It is sectional drawing explaining the method of fixing an electric motor part and a heat dissipation base. It is a perspective view which shows the state which the electronic control means of a redundant system is fixed to the heat radiation substrate. FIG. 8 is a cross-sectional view showing a vertical cross section of AA in FIG. 8 and explaining a modified example thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments, and various modifications and applications are included in the technical concept of the present invention. Is also included in that range.

Before explaining the embodiment of the present invention, the configuration of the steering device as an example to which the present invention is applied will be briefly described with reference to FIG. 1, and in order to help the understanding of the present invention, the conventional electric power steering The schematic configuration of the device will also be briefly described with reference to FIG.

First, a steering device for steering the front wheels of an automobile will be described. The steering device 1 is configured as shown in FIG. A pinion (not shown) is provided at the lower end of the steering shaft 2 connected to a steering wheel (not shown), and this pinion meshes with a rack (not shown) that is long in the left-right direction of the vehicle body. Tie rods 3 for steering the front wheels in the left-right direction are connected to both ends of the rack, and the rack is covered with a rack housing 4. A rubber boot 5 is provided between the rack housing 4 and the tie rod 3.

An electric power steering device 6 is provided to assist the torque when rotating the steering wheel. That is, the electric motor unit 8 is provided with a torque sensor 7 that detects the rotation direction and the rotation torque of the steering shaft 2, and applies a steering assist force to the rack via the gear 10 based on the detection value of the torque sensor 7. And an electronic control device (ECU) unit 9 for controlling the electric motor arranged in the electric motor unit 8. In the electric motor unit 8 of the electric power steering device 6, three locations on the outer peripheral portion on the output shaft side are connected to the gear 10 via bolts (not shown), and the electronic control unit 9 is on the side opposite to the output shaft of the electric motor 8 unit. Is provided.

In the conventional electric power steering device, as shown in FIG. 2, the electric motor portion 8 is composed of a motor housing 11A having a tubular portion made of an aluminum alloy or the like and an electric motor (not shown) housed therein. The control unit 9 is composed of an ECU housing 11B made of aluminum alloy or the like arranged on the side opposite to the output shaft in the axial direction of the motor housing 11A, and an electronically controlled assembly (not shown) housed therein. ..

The motor housing 11A and the ECU housing 11B are integrally fixed by fixing bolts on their opposite end faces. The electronically controlled assembly housed inside the ECU housing 11B has a power supply circuit unit that generates a necessary power supply, and a power conversion element having a power switching element including a MOSFET or an IGBT that drives and controls the electric motor of the electric motor unit 8. It consists of a circuit and a control circuit unit that controls the power switching element, and the output terminal of the power switching element and the input terminal of the electric motor are electrically connected via a bus bar.

A lid 12 made of synthetic resin, which also serves as a connector terminal assembly, is fixed to the end face of the ECU housing 11B by fixing bolts. The lid 12 includes a connector terminal forming unit 12A for power supply, a connector terminal forming unit 12B for a detection sensor, and a connector terminal forming unit 12C for transmitting a control state to an external device. The electronically controlled assembly housed in the ECU housing 11B is supplied with power from the power supply via the connector terminal forming portion 12A for power supply of the lid body 12 made of synthetic resin, and is operated from the detection sensors. A detection signal such as a state is supplied via the connector terminal forming terminal 12B for the detection sensor, and a control state signal of the current electric power steering device is sent via the connector terminal forming terminal 12C for sending the control state.

Here, the lid body 12 has a shape that covers the entire opening of the ECU housing 11B, but each connector terminal is formed in a small size, and an insertion hole formed in the ECU housing 11B is inserted to electronically. It may be configured to be connected to the control assembly.

In the electric power steering device 6, when the steering shaft 2 is rotated in any direction by operating the steering wheel, the torque sensor 7 determines the rotation direction and rotation torque of the steering shaft 2. It is detected, and the control circuit unit calculates the drive operation amount of the electric motor based on the detected value. The electric motor is driven by the power switching element of the power conversion circuit unit based on the calculated drive operation amount, and the output shaft of the electric motor is rotated so as to drive the steering shaft 1 in the same direction as the operation direction. The rotation of the output shaft is transmitted from a pinion (not shown) to a rack (not shown) via a gear 10, and the automobile is steered. Since these configurations and actions are already well known, further description thereof will be omitted.

In such an electric power steering device, as described above, many auxiliary devices such as exhaust gas countermeasure devices and safety countermeasure devices tend to be installed in the engine room of the automobile, and various auxiliary devices including the electric power steering device are installed. Machinery is required to be as small as possible.

In the electric power steering device having such a configuration, the power supply circuit unit, the power conversion circuit unit, and the control circuit unit are mounted on two boards and installed in the radial direction so as to be orthogonal to the axis of the ECU housing. ing. For this reason, the number of electrical components required to control the electric motor is roughly determined. Therefore, when the electrical components with these components are mounted on two boards, the ECU that houses the electronic control unit is used. The housing naturally grows in the radial direction.

Further, in the electric power steering device, safety is particularly required for steering an automobile, and it is necessary to provide an electronic control unit having a redundant system such as a dual system. For this reason, two systems of the same electronic control unit are required as the configuration of the redundant system, and the number of electronic components is doubled. Therefore, the ECU housing is further increased from this point as well.

Due to the structure of the electric power steering device, the axial length is relatively limited in the longitudinal direction, and the increase in size in the radial direction tends to be restricted. Therefore, the current situation is that the electric drive device is required to be miniaturized in the radial direction. In addition to this, the electric components constituting the power supply circuit section and the power conversion circuit section generate a large amount of heat, and when the size is reduced, it is necessary to efficiently dissipate the heat to the outside.

Further, the substrate of the electronic control unit is fixed to the heat radiating substrate. In this type of fixing method, a mounting flange is formed on the outer periphery of the heat radiating substrate, and the mounting flange and the outer periphery of the motor housing are fixed with fixing bolts. It is generally well known. However, when the bolts are fixed on the outer peripheral side in this way, the size tends to increase in the radial direction by this amount.

Against this background, the present embodiment proposes an electric power steering device having the following configuration.

That is, in the present embodiment, the motor housing in which the electric motor is housed and the end surface of the motor housing on the side opposite to the output portion of the rotation shaft of the electric motor extend in the direction of the rotation axis on the side opposite to the output portion. A pair of support shafts arranged facing each other, a heat radiation base arranged between the support shafts and extending in the same direction as the support shaft, and a fixing bolt screwed inward in the radial direction from the support shaft to connect the support shaft and the heat radiation base. One of the electronic control means of the redundant system including the substrate which is arranged along the direction in which the heat radiating substrate extends and is fixed to the heat radiating substrate so as to conduct heat, and the heat radiating substrate is arranged along the direction in which the heat radiating substrate extends The configuration was provided with the other electronic control means of the redundant system having a conductively fixed substrate.

Hereinafter, the configuration of the electric power steering device according to the embodiment of the present invention will be described in detail with reference to FIGS. 3 to 9. Note that FIG. 3 is a view of the entire components of the electric power steering device according to the present embodiment disassembled and viewed from an oblique direction, and FIGS. 4 to 9 show the components according to the assembly order of the components. It is a drawing which shows the state which was assembled. Therefore, in the following description, the description will be given with reference to each drawing as appropriate.

FIG. 3 shows an exploded perspective view of the electric power steering device 6. An annular iron side yoke (not shown) is fitted inside the motor housing 20, and an electric motor (not shown) is housed in the side yoke. The output unit 21 of the electric motor applies a steering assist force to the rack via gears. Since the specific structure of the electric motor is well known, the description thereof will be omitted here.

The motor housing 20 is made of an aluminum alloy, and functions as a heat sink that releases heat generated by an electric motor and heat generated by electronic components mounted on an electronic control board, which will be described later, to the outside atmosphere. The electric motor and the motor housing 20 constitute an electric motor unit EM.

An electronic control unit EC is attached to the end surface of the motor housing 20 on the opposite side of the output unit 21 of the electric motor unit EM. The electronic control unit EC includes a rotation position detection circuit board 22, a heat dissipation base 23, a first power conversion circuit board 24, a first control circuit board 25, a second power conversion circuit board 26, a second control circuit board 27, and a power connector 28. It is composed of.

Here, the first power conversion circuit board 24, the first control circuit board 25, the second power conversion circuit board 26, and the second control circuit board 27 form a redundant system, and the first power conversion circuit board 24, The first control circuit board 25 constitutes the main electronic control means, and the second power conversion circuit board 26 and the second control circuit board 27 constitute the sub-electronic control means.

Normally, the electric motor is controlled and driven by the main electronic control means, but if an abnormality or failure occurs in the first power conversion circuit board 24 or the first control circuit board 25 of the main electronic control means, the sub-electronic control is performed. It is switched to the means, and the electric motor is controlled and driven by the second power conversion circuit board 26 and the second control circuit board 27 of the sub-electronic control means.

Therefore, as will be described later, heat from the main electronic control means is normally transferred to the heat radiation base 23, and when an abnormality or failure occurs in the main electronic control means, the main electronic control means is stopped and the sub electronic control means is activated. The heat from the sub-electronic control means is transferred to the heat radiation base 23.

However, although it is not adopted in this embodiment, the main electronic control means and the sub electronic control means are combined to function as a regular electronic control means, and when an abnormality or failure occurs in one electronic control means, the other electronic control is performed. It is also possible to control and drive an electric motor with half the capacity by means. In this case, the capacity of the electric motor is halved, but the so-called "limp home function" is secured. Therefore, in a normal case, the heat of the main electronic control means and the sub-electronic control means is transferred to the heat radiation base 23.

The electronic control unit EC is not housed in the conventional ECU housing as shown in FIG. 2, and therefore the heat of the electronic control unit EC is not dissipated from the ECU housing. In the present embodiment, the electronic control unit EC is fixed and supported by the motor housing 20, and the heat of the electronic control unit EC is mainly dissipated from the motor housing 20. When the assembly of the electronic control unit EC and the electric motor unit EM is completed, the electronic control unit EC is covered with the cover 29, and the end face of the motor housing 20 and the cover 20 are butted against each other to connect them.

The cover 29 can be made of synthetic resin or metal, and is integrated with the motor housing 20 by bonding, welding, fixing methods such as bolts, and fixing means. As described above, in the present embodiment, when viewed as an electric power steering device, the portion to be sealed is only the joint portion between the motor housing 20 and the cover 29, so that an additional structure of the seal portion and parts necessary for sealing are required. Can be reduced.

Further, since the cover 29 does not need to support the electronic control unit EC, the thickness can be reduced, which contributes to the reduction in the radial length and the weight reduction of the electronic control unit EC. Further, if the cover 29 is made of metal (aluminum alloy, iron, etc.), it is provided with a heat dissipation function, so that the heat from the motor housing 20 is transferred to the cover 29, and the heat dissipation effect can be further enhanced.

As described above, in the present embodiment, the rotation position detection circuit board 22 is fixed to the end surface of the motor housing 20, and the first power conversion circuit board 24, the first control circuit board 25, the second power conversion circuit board 26, and the second control The circuit boards 27 are fixed to the heat radiation base 23 while facing each other, and the heat radiation base 23 is fixed so as to cover the rotation position detection circuit board 22 with the end face of the motor housing 20. Further, the cover 29 is liquid-tightly coupled to the end face of the motor housing 20. This configuration is one of the major features of this embodiment.

That is, in the present embodiment, an ECU housing made of an aluminum alloy or the like, which is arranged on the side opposite to the axial output shaft of the motor housing, such as the conventional electric power steering device shown in FIG. 2, is required. It doesn't.

Therefore, unlike the conventional case, the ECU housing, the seal for ensuring the liquidtightness in the ECU housing, the bolt for fixing the motor housing and the ECU housing, etc. are not required, and the physique of the electric power steering device itself can be reduced. This is possible, and the number of parts can be reduced, so that the assembly man-hours can also be reduced. As a result, the final product unit price can be suppressed, and the product racing ability can be enhanced.

Returning to FIG. 3, a rotor portion (not shown) of the electric motor is arranged in the central portion of the motor housing 20, and a stator winding is wound around the rotor portion. The fixed windings are star-connected, and the input terminals 30 of the windings of each phase and the neutral terminals 31 of each phase protrude from the opening 32 provided in the motor housing 20. Since the present embodiment is configured as a dual system, the input terminal 30 of the winding of each phase and the neutral terminal 31 of each phase are provided in the motor housing 20 for the other system. It sticks out from. The redundant input terminal 30 and the neutral terminal 31 project from the opening 32 at a distance of 180 ° from each other.

The input terminals 30 of the windings of each phase are connected to the output terminals of each phase of the first power conversion circuit board 24 constituting the main electronic control means. Further, the neutral terminals 31 of each phase are connected by a wiring pattern on the substrate of the rotation position detection circuit board 22 to form a neutral point. Similarly, the input terminals 30 of the windings of each phase of the other system are connected to the output terminals of each phase of the second power conversion circuit board 26 constituting the sub-electronic control means. Further, the neutral terminals 31 of each phase of the other system are also connected by a wiring pattern on the substrate of the rotation position detection circuit board 22 to form a neutral point. Since it is basically a redundant system, it has almost the same configuration.

This configuration is also one of the major features of this embodiment. In this way, since the neutral terminals 31 of each phase of the main electronic control means and the sub electronic control means are connected by a wiring pattern on the substrate of the rotation position detection circuit board 22, the neutral terminals 31 of each phase are connected. There is no need to route it, and the configuration is extremely simple. Furthermore, since it is not necessary to route the input terminals 30 of each phase to the power conversion circuit boards 24 and 26, respectively, a space for routing the input terminals 30 is not required, and the diameter of the electronic control unit EC can be further reduced. This will be described with reference to FIG.

Although not shown, a bearing for supporting the rotating shaft constituting the rotor portion is provided between the two openings 32 of the motor housing 20, and a sealing plate 33 is provided so as to cover the bearing portion from the outside. It is provided on the end face side of the motor housing 20. The sealing plate 33 shields the rotor portion from the outside, and is provided to prevent the filler filled in the cover 29 from entering the rotor portion after the cover 29 is attached. The filler flows to the winding side through the opening 32, but the winding side does not rotate, so there is no effect.

As shown in FIGS. 3 and 4, a rotation position detection circuit board 22 is fixed to the end surface of the motor housing 20 by bolts 34, and the neutral terminals 31 of each phase are fixed on the board of the rotation position detection circuit board 22. They are connected to form a neutral point. Further, the input terminals 30 of the windings of each phase extend along the axial direction from between the opening 32 and the rotation position detection circuit board 22. As will be described later, the input terminal 30 is connected to the output terminal of each phase of the power conversion circuit boards 24 and 26.

A GMR (giant magnetoresistive effect) element (not shown) is provided on the surface of the rotating position detection circuit board 22 on the sealing plate 33 side, and is a permanent magnet for position detection fixed to the rotating shaft on the opposite side of the output unit 21. In cooperation with, the magnetic pole position information of the rotor part is obtained. Further, a magnetic shield plate 35 is provided on the surface of the rotation position detection circuit board 22 opposite to the surface on which the GMR element is provided.

The magnetic shield plate 35 has magnetism caused by the operation of electronic components mounted on the first power conversion circuit board 24, the first control circuit board 25, the second power conversion circuit board 26, and the second control circuit board 27. It has a function of suppressing the influence on the GMR element.

On the end surface of the motor housing 20, a support shaft 36 planted in the axial direction toward the side opposite to the output portion 21 is integrally formed with the motor housing 20. Therefore, the support shaft 36 is made of an aluminum alloy and has high thermal conductivity. The support shafts 36 are provided so as to face each other at intervals of about 180 ° with the rotation position detection circuit board 22 interposed therebetween. The support shaft 36 has a function of fixing and supporting the heat radiating base 23 and transferring heat from the heat radiating base 23 to the motor housing 20 as described later.

The support shaft 36 is formed so as to be in thermal contact with the heat radiating base 23 on three surfaces, a front surface and side surfaces formed on both sides of the front surface. The side surface is formed on an inclined surface toward the tip in the axial direction in order to increase the heat conduction area. As a result, the length of the side surface becomes long and a large heat conduction area can be secured. Further, insertion holes 37 through which fixing bolts are inserted are formed on the front surface and the back surface of the support shaft 36.

In FIGS. 3, 5, and 6, the heat radiating substrate 23 is made of an aluminum alloy having good thermal conductivity, and is formed in a substantially rectangular parallelepiped shape. The heat radiation base 23 is basically arranged so as to pass through a region substantially in the center of the end surface of the motor housing 20, in other words, on an extension line of the rotation axis of the rotor portion, and is directed toward the side opposite to the output portion 21. It is arranged so as to extend in the axial direction. A redundant electronic control board, which will be described later, is arranged in the axial direction around the heat dissipation base 23. This configuration is also one of the major features of this embodiment.

A support shaft mounting portion 38 to which the support shaft 36 is mounted is formed on the lower side of both side surfaces 23S of the heat radiation base 23, and a connector mounting portion 39 is formed on the upper side. The support shaft mounting portion 38 is formed in a concave shape having a surface facing the front surface and a surface facing the side surface of the support shaft 36, and the support shaft 36 is housed and arranged in the concave portion shape portion. .. A bolt hole 40 into which a fixing bolt is screwed is formed on a surface of the support shaft 36 facing the front surface.

The surface of the support shaft mounting portion 38 facing the side surface of the support shaft 36 is formed as an inclined surface that narrows upward in accordance with the side surface of the support shaft 36. As a result, it is possible to secure a large heat conduction area of heat from the heat radiating base 23 toward the support shaft 36 and to guide the heat radiating base 23 when it is inserted into the support shaft 36.

Moreover, since the side surface of the support shaft 36 and the surface of the support shaft mounting portion 38 facing the side surface are inclined surfaces, the close contact between the two surfaces is improved, and the space between the support shaft 36 and the heat radiation base 23 is improved. It is possible to suppress the runout of. This makes it possible to suppress unnecessary vibration of the heat radiating substrate 23.

Further, the connector mounting portion 39 formed on the upper side of the heat radiating base 23 is also formed in a shape in which the power connector is engaged. This will be described with reference to FIG.

FIG. 6 shows the mounting state of the heat radiating base 23 as seen from the side surface opposite to the side surface 23S of the heat radiating base 23 in the state shown in FIG.

As shown in FIG. 6, the support shaft mounting portion 38 of the heat radiation base 23 is moved downward along the support shaft 36 formed in the motor housing 20, and when it reaches a predetermined position, it is supported by the fixing bolt 41. The shaft 36 and the heat radiation base 23 are firmly fixed. In this state, the heat radiating substrate 23 is fixed at a position passing near the center of the end surface of the motor housing 20. In the present embodiment, the length of the mounting surface of the heat radiating substrate 23 to the end surface of the motor housing 20 is matched with the sizes of the control circuit boards 25 and 27 described later, so that the heat radiating substrate 23 is the end surface of the motor housing 20. It is installed so that it crosses near the center of the.

As a result, the heat from the electronic control board, which will be described later, can be transferred to the heat dissipation base 23, and the heat of the heat dissipation base 23 can be further transferred to the support shaft 36. Therefore, the heat from the electronic control board can be dissipated from the motor housing 20 without using the conventional ECU housing, so that the physique of the electric power steering device itself can be made smaller, and further, the parts Since the number of points can be reduced, the assembly man-hours can also be reduced. The contact portion between the support shaft 36 and the heat dissipation base 23 is provided with a heat dissipation functional material such as an adhesive having good thermal conductivity, a heat dissipation sheet, and heat dissipation grease in order to enhance thermal contact (reduce the interfacial thermal resistance). You can also do it.

Returning to FIG. 5, a fixing surface for fixing the first power conversion circuit board 24 and the first control circuit board 25 is formed on the board mounting surface 23F corresponding to the front side of the heat radiation base 23. As shown in FIGS. 1 and 8, the first power conversion circuit board 24 is fixed to the front side of the heat dissipation base 23, and the first control circuit board 25 is further fixed from above. ..

Similarly, a fixing surface for fixing the second power conversion circuit board 26 and the second control circuit board 27 is formed on the substrate mounting surface 23F corresponding to the back surface side of the heat radiation base 23. As also shown in FIG. 1, a second power conversion circuit board 26 is fixed to the back side of the heat dissipation base 23, and a second control circuit board 27 is further fixed from above.

The first power conversion circuit board 24 and the second power conversion circuit board 26 are a power switching element composed of a plurality of MOSFETs constituting the power conversion circuit on a metal substrate made of a metal having good thermal conductivity such as aluminum, and a power switching element thereof. An output connector for the output of is provided. Further, the first power conversion circuit board 24 and the second power conversion circuit board 26 are provided with a coil constituting a power supply circuit, a switching element made of MOSFET, and various connector terminals. Since many switching elements for switching a large current are mounted on the first power conversion circuit board 24 and the second power conversion circuit board 26, a large amount of heat is generated, and the first power conversion circuit board 24 and the second power conversion circuit The substrate 26 is the main heat generating source. Of course, heat is also generated from the first control circuit board 25 and the second control circuit board 27, but this is also configured to be dissipated to the heat dissipation base 23. This will be described later.

As shown in FIGS. 5 and 6, the metal substrates of the first power conversion circuit board 24 and the second power conversion circuit board 26 are fixed to the storage recesses 42 formed in the front and back surfaces of the heat dissipation base 23 by fixing bolts. ing. A power switching element is arranged between the metal substrate and the storage recess 42, and an adhesive having good heat conductivity, a heat dissipation sheet, and heat dissipation are provided between the power switching element and the storage recess 42 in order to improve the heat conduction performance. A heat dissipation functional material such as grease is interposed.

Needless to say, the power switching element may be arranged on the side opposite to the storage recess 42 so that the metal substrate and the storage recess 42 are brought into contact with each other. However, in the present embodiment, in order to transfer the heat of the power switching element to the heat radiating substrate 23 more efficiently, the power switching element and the storage recess 42 are brought into contact with each other.

In this way, the first power conversion circuit board 24 and the second power conversion circuit board 26 are housed in the storage recess 42 formed in the heat dissipation base 23, whereby the first power conversion circuit board 24 and the second power conversion are performed. The circuit board 26 is housed in the heat dissipation base 23 to prevent the electronic control unit EC from becoming larger in the radial direction.

Further, as shown in FIG. 8, the first control circuit board 25 and the second control circuit board 27 cover the heat dissipation base 23 so as to cover the first power conversion circuit board 24 and the second power conversion circuit board 26. It is fixed to the board mounting surface 23F by a fixing bolt 47. That is, the first control circuit board 25 and the second control circuit board 27 are fixed by fixing bolts 47 to the mounting flat portion 44 surrounding the storage recess 42 formed on the mounting surface 23F of the heat radiating base 23.

In the first control circuit board 25 and the second control circuit board 27, a microcomputer 48 for controlling a switching element of a power conversion circuit and a peripheral circuit 49 thereof are mounted on a resin substrate made of a synthetic resin or the like. In this embodiment, the electrolytic capacitor 43 constituting the power supply circuit is mounted on the first control circuit board 25 and the second control circuit board 27.

Since the electrolytic capacitor 43 has a large physique and is difficult to arrange in the storage recess 42 described above, it is mounted on the first control circuit board 25 and the second control circuit board 27. Since the space with the cover 29 is sufficient as shown in FIG. 1, there is no problem even if the electrolytic capacitor 43 is arranged.

Here, a passage space 45 that serves as a passage when the first control circuit board 25 and the second control circuit board 27 are fixed is formed between the storage recess 42 and the mounting flat surface portion 44. This passage space is formed to cool the storage recess 42 with air. Therefore, the heat from the first control circuit board 25 and the second control circuit board 27 flows into the air in the passage space 45, and also flows to the heat radiating base 23 through the mounting flat portion 44.

As shown in FIG. 5, a connector storage recess 46 is formed on the upper end surface of the heat radiating substrate 23 on the side opposite to the fixed side. The connector accommodating recess 46 accommodates the inner end of the power connector, which will be described later, and also has a positioning function.

FIG. 7 is a cross section showing a mounting state of the support member 36 and the heat radiating base 23. An end portion of the rotating shaft 50 opposite to the output portion 21 is located on the end surface of the motor housing 20, and a magnet holding member 51 is fixed to this end portion, and the inside of the magnet holding member 51 is fixed. A permanent magnet 52 for position detection, which constitutes a position detection sensor, is housed in the housing. The position detection permanent magnet 52 is magnetized so that a plurality of unit magnets are formed in an annular shape.

A sealing plate 33 is arranged between the permanent magnet 52 for position detection and the position detection circuit board 22, and the sealing plate 33 is fixed to the end face of the motor housing 20 to form a space in which the rotating shaft 50 is arranged. The space on the position detection circuit board 22 side is shielded. This makes it possible to shield the space where the rotating shaft 50 is arranged and the space on the position detection circuit board 22 side in a liquid-tight or airtight manner.

Therefore, it is possible to block the moisture entering through the rotating shaft 50 from moving to the space where the electronic control board is arranged, and the electronic components mounted on the electronic control board are adversely affected by the moisture. Can be suppressed. Of course, it is also possible to suppress the intrusion of fine dust generated by the rotation of the electric motor. This can also have the effect of avoiding the failure of electronic components.

It is also possible to arrange a sensor for detecting the intrusion of moisture on the position detection circuit board 22 to detect the intrusion of moisture. In the present embodiment, since the joint portion is formed only on the abutting surface of the motor housing 20 and the cover 29, water intrusion is assumed in this portion. Therefore, since the position detection circuit board 22 is fixed near the end face of the motor housing 20, if a sensor for detecting moisture is arranged on the position detection circuit board 22, the moisture can be detected at the earliest.

Further, the GMR element 53 is mounted on the surface of the position detection circuit board 22 on the side of the position detection permanent magnet 52, and is arranged at a position facing the position detection permanent magnet 52. Therefore, the GMR element 53 is integrally assembled with the motor housing 20. That is, the rotating shaft 50 to which the permanent magnet 52 for position detection is fixed is supported by the end face of the motor housing 20, and the position detection circuit board 22 on which the GMR element 53 is mounted is also fixed to the end face of the motor housing 20. ing. Therefore, since the positions of the position detection permanent magnet 52 and the position detection circuit board 22 are determined on the end surface of the motor housing 20, the assembly accuracy of the GMR element 53 is improved, and an accurate detection signal can be obtained.

Further, in FIG. 7, with the support shaft mounting portion 38 of the heat radiation base 23 inserted and arranged in the support shaft 36, the fixing bolt 41 passes through the support shaft 36 from the outer side in the radial direction to the inner side and passes through the heat radiation base 23. The support shaft 36 and the heat radiation base 23 are firmly fixed to each other.

Here, the fixing direction of the fixing bolt 41 is also a major feature of the present embodiment. In the present embodiment, the fixing bolt 41 is screwed into the heat radiation base 23 through the support shaft 36 from the outer side to the inner side in the radial direction. This makes it possible to reduce the diameter of the electronic control unit EC. In this type of fixing method, it is generally well known that a mounting flange is formed on the outer periphery of the heat radiation base 23, and the mounting flange and the outer periphery of the motor housing 20 are fixed with fixing bolts. However, when it is fixed on the outer peripheral side in this way, it tends to be larger in the radial direction by this amount.

On the other hand, in the present embodiment, the space formed by the heat radiating base 23 and the cover 29 is used, and the fixing bolt 41 is located in this space. Therefore, since the fixing bolt 41 is screwed into the heat radiation base 23 through the support shaft 36 from the outer side to the inner side in the radial direction, it is not fixed on the outer peripheral side. As a result, the diameter of the electronic control unit EC can be reduced. It is possible to plan.

Further, since the two support shafts 36 are cantilever beams in the motor housing 20, when the heat radiation base 23 and the support shaft 36 are fixed by the fixing bolts 41, the support shaft 36 is fixed with a slight deflection. become. As a result, an axial load always acts on the threads of the fixing bolt 41, so that loosening of the fixing bolt 41 can be suppressed.

After the heat dissipation base 23 is fixed to the motor housing 20, a redundant electronic control board is then attached.

In FIG. 8, the metal substrates of the first power conversion circuit board 24 and the second power conversion circuit board 26 are fixed to the storage recesses 42 formed on the front and back surfaces of the heat dissipation substrate 23 by fixing bolts. In FIG. 8, since the first control circuit board 25 and the second control circuit board 27 are assembled, they are not displayed. By configuring the first power conversion circuit board 24 and the second power conversion circuit board 26 to be housed in the storage recess 42 formed in the heat dissipation base 23, the first power conversion circuit board 24 and the second power conversion circuit board The 26 is housed in the heat radiating substrate 23, and it is possible to prevent the electronic control unit EC from becoming larger in the radial direction.

Further, the first control circuit board 25 and the second control circuit board 27 are attached to the substrate mounting surface 23F of the heat dissipation base 23 by fixing bolts 47 so as to cover the first power conversion circuit board 24 and the second power conversion circuit board 26. It is fixed. On the first control circuit board 25 and the second control circuit board 27, an electrolytic capacitor 43 used in a power supply circuit, a microcomputer 48 for controlling a switching element of a power conversion circuit, and peripheral circuits 49 thereof are mounted.

A power connector 28 is attached to the upper end surface of the heat radiating base 23, and is fixed by a fixing bolt 56 at a connector attachment portion 39 shown in FIG. The power connector is connected to the in-vehicle battery by a cable (not shown). Therefore, the electric power supplied from the power connector 28 is applied to the first power conversion circuit board 24, the first control circuit board 25, the second power conversion circuit board 26, and the second control circuit board 27, and further to the electric motor. The electric motor is driven by this. Further, after this, the cover 29 is fixed to the end face of the motor housing 20 so as to seal the electronic control unit EC.

In this way, the first power conversion circuit board 24 and the first control circuit board 25 are provided on the front surface of the heat dissipation base 23, and the second power conversion circuit board 26 and the second control circuit board 27 are provided on the back surface of the heat dissipation base 23. As a result, normally, a part of the heat generated in the state where the first power conversion circuit board 24 and the first control circuit board 25 are operating is passed through the heat dissipation base 23 to the second power conversion circuit board 26 and the second. Since the two control circuit boards 27 are stored, the heat of the first power conversion circuit board 24 and the first control circuit board 25 can be efficiently dissipated. Of course, it goes without saying that much heat is radiated from the motor housing 20 via the heat radiating substrate 23.

Further, the output terminals 54 of each phase of the first power conversion circuit board 24 and the second power conversion circuit board 26 project radially outward from the upper surface of the position detection circuit board 22, and the output terminals 54 of each phase It is connected to the input terminal 30 of the winding of each phase. In this way, the input terminal 30 of the winding protruding from the opening 32 is directly connected to the output terminal 54 of each phase in the vicinity of the opening 32 without being routed, so that no extra space for routing is required. It is a thing. As a result, the diameter of the electronic control unit EC can be reduced.

Further, the neutral terminals 31 of each phase are connected by a wiring pattern on the substrate of the rotation position detection circuit board 22 to form a neutral point. Similarly, the neutral terminals 31 of each phase of the other system are also connected by the wiring pattern 55 on the substrate of the rotation position detection circuit board 22 to form a neutral point. Since the neutral terminals 31 of each phase of the main electronic control means and the sub electronic control means are connected by the wiring pattern 55 on the substrate of the rotation position detection circuit board 22, the neutral terminals 31 of each phase can be routed. The configuration is extremely simple. Furthermore, since it is not necessary to route the input terminals 30 of each phase to the power conversion circuit boards 24 and 26, respectively, there is no need for a space for routing them, so that the diameter of the electronic control unit EC can be further reduced. Become.

Then, in the electronic control unit EC assembled in this way, a part of the heat generated particularly in the first power conversion circuit board 24 (or the second power conversion circuit board 26) is passed through the heat dissipation base 23. Most of the heat stored in the second power conversion circuit board 26 (or the first power conversion circuit board 24) and transferred to the heat dissipation base 23 moves to the motor housing 20 through the support shaft 36 and is dissipated. To.

In the configuration described above, a fixing surface for fixing the first power conversion circuit board 24 and the first control circuit board 25 is formed on the substrate mounting surface 23F corresponding to the front side of the heat radiation base 23, and the heat radiation base 23 is formed. A fixed surface for fixing the second power conversion circuit board 26 and the second control circuit board 27 is formed on the board mounting surface 23F corresponding to the back side of the above. The substrate mounting surface 23F corresponding to the front side of the heat radiating substrate 23 and the substrate mounting surface 23F corresponding to the back side of the heat radiating substrate 23 are formed in a state of being substantially parallel to each other. Therefore, the first power conversion circuit board 24, the first control circuit board 25, the second power conversion circuit board 26, and the second control circuit board 27 are also arranged substantially in parallel.

However, in order to efficiently dissipate the heat generated by the electronic component of the electronic control means, it is advantageous that the heat capacity of the substrate for quickly storing the heat generated by the electronic component is large. Further, in order to efficiently dissipate the heat generated by one of the electronic control means (for example, the main electronic control means), it is advantageous that the capacity of the other electronic control means (for example, the sub-electronic control means) to store heat is large. Is. For the same reason, in order to efficiently release the heat generated by the electronic control means, it is advantageous that the contact area with the heat radiating substrate 23 is large. For this reason, the following configuration is adopted as the present embodiment, and this configuration is also a major feature of the present embodiment.

In the present embodiment, first, the first control circuit board 25 and the second control circuit board 27 are attached to the heat dissipation base 23 at an angle, and the board areas of the first control circuit board 25 and the second control circuit board 27 are increased. The capacity to store heat is increased. Further, the first power conversion circuit board 24 and the second power conversion circuit board 26 are attached to the heat dissipation base 23 at an angle, and the contact product of the first power conversion circuit board 24 and the second power conversion circuit board 26 is increased. The heat is quickly released to the heat dissipation substrate 23.

In FIG. 9, the first control circuit board 25 and the second control circuit board 27 are attached to the heat radiation base 23 with an inclination so as to spread downward. When the first control circuit board 25 and the second control circuit board 27 are tilted in this way, as shown in FIG. 3, when the first control circuit board 25 and the second control circuit board 27 are arranged substantially in parallel. In comparison, the substrate area can be increased. Therefore, since excess heat can be stored by the amount of this increase, the heat generated by the electronic components on the substrate can be quickly dissipated to the substrate, and the heat resistance of the electronic components can be improved.

Further, a first power conversion circuit board 24 and a first control circuit board 25 are provided on the front surface of the heat radiation base 23, and a second power conversion circuit board 26 and a second control circuit board 27 are provided on the back surface of the heat radiation base 23. Therefore, normally, a part of the heat generated in the state where the first power conversion circuit board 24 and the first control circuit board 25 are operating is passed through the heat dissipation base 23 to the second power conversion circuit board 26 and the second. Since it is stored in the control circuit board 27, the heat of the first power conversion circuit board 24 and the first control circuit board 25 can be quickly and efficiently dissipated.

Further, by inclining the first control circuit board 25 and the second control circuit board 27, the distance between the first control circuit board 25 and the second control circuit board 27 from the inner peripheral surface of the cover 29 becomes shorter, and the first The heat from the control circuit board 25 and the second control circuit board 27 is easily transferred to the cover 29, and the amount of heat dissipated from the cover 29 can be increased.

Next, although not shown in FIG. 9, the shape of the heat radiating substrate 23 is inclined so as to spread downward from each other in accordance with the inclination of the first control circuit board 25 and the second control circuit board 27. The first power conversion circuit board 24 and the second power conversion circuit board 26 can be attached to the inclined portion of the heat dissipation base 23 at an angle. When the first power conversion circuit board 24 and the second power conversion circuit board 26 are tilted in this way, as shown in FIG. 3, the first power conversion circuit board 24 and the second power conversion circuit board 26 are substantially parallel to each other. The contact area with the heat radiating substrate 23 can be increased as compared with the case where the arrangement is performed. Therefore, heat can be quickly released to the heat radiating substrate 23 by the amount of this increase, so that the heat resistance of the electronic component can be improved.

As described above, in the present embodiment, the electric drive device is electrically driven by fixing the substrate of the electronic control means extending along the axial direction to the heat radiating substrate extending along the rotation axis direction of the electric motor so as to be thermally conductive. Can be miniaturized to reduce the radial size of the. Further, since the heat from each substrate is radiated to the housing of the electric motor portion via the heat radiating substrate, the heat from the substrate can be efficiently radiated to the outside even when the size is reduced.

In addition, the space formed by the heat dissipation substrate and the cover is used so that the fixing bolts are located in this space. For this reason, the fixing bolt is screwed into the heat radiation base through the support shaft from the outer side to the inner side in the radial direction, so that the fixing bolt is not fixed on the outer peripheral side. As a result, the diameter of the electronic control unit EC is reduced. Is possible.

As described above, in the present invention, the motor housing in which the electric motor is housed and the end face of the motor housing on the side opposite to the output portion of the rotation shaft of the electric motor extend in the direction of the rotation axis on the side opposite to the output portion. A pair of support shafts arranged facing each other, a heat radiating base arranged between the support shafts and extending in the same direction as the support shaft, and fixed by being screwed from the support shaft in the radial direction from the outside to the inside to connect the support shaft and the heat radiating base. One electronic control means of a redundant system including a bolt and a substrate provided with a bolt and a substrate electrically conductively fixed to the heat radiating substrate along the direction in which the heat radiating substrate extends, and a heat radiating substrate arranged along the direction in which the heat radiating substrate extends. The configuration is provided with the other electronic control means of the redundant system having a substrate fixed so as to be heat conductive.

According to this, by fixing the substrate of the electronic control unit, which also extends along the rotation axis direction, to the heat radiating substrate extending along the rotation axis direction of the electric motor so as to be heat conductive, the radial direction of the electric drive device It can be reduced in size and downsized. Further, since the heat from each substrate is radiated to the housing of the electric motor portion via the heat radiating substrate, the heat from the substrate can be efficiently radiated to the outside even when the size is reduced. Further, since the fixing bolt is screwed into the heat radiation base through the support shaft from the outside to the inside in the radial direction, it is not fixed on the outer peripheral side, which makes it possible to reduce the diameter of the electronic control unit. It becomes.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

20 ... motor housing, 21 ... output unit, 22 ... position detection circuit board, 23 ... heat dissipation substrate, 24 ... first power conversion circuit board, 25 ... first control circuit board, 26 ... second power conversion circuit board, 27 ... 2nd control circuit board, 28 ... power connector, 29 ... cover, 30 ... winding input terminal, 31 ... neutral terminal, 32 ... opening, 33 ... sealing plate, 34 ... fixing bolt, 35 ... magnetic shield plate, 36 ... Support shaft, 37 ... Insertion hole, 38 ... Support shaft mounting part, 39 ... Connector mounting part, 40 ... Bolt hole, 41 ... Fixing bolt, 42 ... Storage recess, 43 ... Electrolytic capacitor, 44 ... Mounting flat part, 45 ... Passage space, 46 ... Connector storage recess, 47 ... Fixing bolt, 48 ... Microcomputer, 49 ... Peripheral circuit, 50 ... Rotating shaft, 51 ... Magnet holding member, 52 ... Permanent magnet for position detection, 53 ... GMR element, 54 ... Output terminal, 55 ... Wiring pattern, EM ... Electric motor, E
C ... Electronic control unit.

Claims (4)

A motor housing that houses an electric motor that drives mechanical control elements,
A heat dissipation substrate arranged on an extension line of the rotating shaft of the electric motor on the end face of the motor housing on the side opposite to the output portion of the rotating shaft of the electric motor and extending in the direction of the rotating shaft on the opposite side of the output portion. When,
A control circuit board that controls a switching element of a power conversion circuit that drives and controls the electric motor is provided.
The control circuit board is at least a first control circuit board on which a microcomputer is mounted and at least a second control circuit board on which a microcomputer is mounted.
An electric drive device characterized in that a substrate surface of the first control circuit board and a substrate surface of the second control circuit board are fixed to the heat radiation substrate so as to sandwich the heat radiation substrate . In claim 1,
The control circuit board includes a first control circuit board on which a microcomputer is mounted as two control systems for controlling switching elements of a power conversion circuit that drives and controls the electric motor, and a second control circuit board on which the microcomputer is mounted. Consists of
The first control circuit board is fixed to a surface having one surface of the heat radiating substrate facing in a direction orthogonal to the rotation axis of the electric motor.
The second control circuit board is an electric drive device characterized in that it is fixed to a surface which is a back surface of the heat radiation substrate with respect to a surface which is the front surface. In claim 1,
A pair of support shafts arranged on the end surface of the motor housing on the side of the rotation shaft of the electric motor opposite to the output portion and facing each other extending in the direction of the rotation axis on the side opposite to the output portion.
A fixing bolt for connecting the support shaft and the heat radiation base is provided.
The electric drive device is characterized in that the heat radiation substrate is arranged between the support shafts, and the fixing bolts are screwed from the radial outside to the inside of the support shafts to be coupled to the support shafts. .. In claim 1,
The power conversion circuit board on which the power conversion circuit is mounted is arranged between the control circuit board and the heat dissipation base, and the heat generated by the power conversion circuit board is dissipated to the heat dissipation base. Electric drive device.

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