Patent Application
20220345003
The present invention relates to an electronic controller, an electric drive device including the electronic controller and an electric motor unit, and an electric power steering apparatus including the electric drive device.
An automobile is equipped with an electric power steering apparatus that generates torque by a motor to serve as a mechanism that assists in steering. A conventional technique for providing this type of apparatus, for example, is described in PTL 1.
PTL 1 describes a technique for providing a device that includes a cylindrical motor case forming an outer frame, a stator disposed radially inside the motor case and wound with windings constituting a plurality of current phases, and a rotor disposed radially inside the stator and supported rotatably. PTL 1 describes also a technique for providing a device that includes a shaft, a heat sink disposed in the axial direction of a motor case and having a plurality of columnar portions separated from each other, and a semiconductor module disposed on the columnar portions such that one drive system corresponds to one columnar portion.
PTL 1: JP 2011-176998 A
However, according to the technique described in PTL 1, the direction of inserting a terminal of an external device in a connector is set perpendicular to the axial direction of the device. As a result, according to the technique described in PTL 1, the connector sticks out in the direction perpendicular to the axial direction of the device, thus leading to an increase in the overall size of the device. Besides, improving assembling efficiency of an electronic controller has been in demand for years.
The present invention has been conceived in view of the above problems, and it is an object of the invention to provide an electronic controller, an electric drive device, and an electric power steering apparatus that allow miniaturization and make assembling work easy.
In order to solve the above problems and achieve the object, an electronic controller includes a board and a connector assembly. The board carries an electronic circuit and is placed on a pedestal disposed on one side in an axial direction of an electric motor unit. The connector assembly is disposed on one side in the axial direction of the board.
The board has a connection hole in which a coil wire of the electric motor unit is inserted. The connector assembly includes: a flat plate portion that leaves one side in the axial direction of an area of a board open, the area including the connection hole, while covering a part of the board; and a connector housing provided on the flat plate portion, the connector housing allowing a terminal of an external device to be inserted therein along the axial direction.
An electric drive device includes: an electric motor unit having an electric motor, a motor housing that houses the electric motor, and a pedestal provided on one end in the axial direction of the motor housing; and an electronic controller attached to the electric motor unit, the electronic controller controlling the electric motor unit. This electronic controller is the electronic controller described above.
An electric power steering apparatus includes an electric drive device that provides auxiliary torque to assist in operating/turning a steering wheel. This electric drive device is the electric drive device described above.
According to the electronic controller, the electric drive device, and the electric power steering apparatus that have the above-described configurations, miniaturization can be achieved as assembling work is easily performed.
Embodiments of an electronic controller, an electric drive device, and an electric power steering apparatus will now be described with reference to
A configuration of an electric power steering apparatus according to an embodiment (which will hereinafter be referred to as “this example”) will first be described with reference to
The apparatus shown in
One end in the axial direction of the steering shaft 2 is connected to a steering wheel (not illustrated). At the other end in the axial direction of the steering shaft 2, a pinion (not illustrated) is disposed. The pinion meshes with a rack (not illustrated) extending in the width direction of a vehicle body. The tie rods 3 for steering the driving wheels of the automobile toward the left and right are connected respectively to both ends of the rack. The rack is covered with the rack housing 4. Between the rack housing 4 and the tie rods 3, the rubber boots 5 are each provided.
The electric drive device 6 provides auxiliary torque for assisting in operating/turning a steering wheel. The electric drive device 6 includes a torque sensor 7, an electric motor unit 8 serving as a drive unit, and an electronic controller (electronic control unit or ECU) 9.
The torque sensor 7 detects the rotation direction and the rotation torque of the steering shaft 2.
A plurality of parts of the outer periphery of electric motor unit 8, the parts being on an output shaft side, are connected to the gear 10 via bolts (not illustrated). Based on a detection value from the torque sensor 7, the electric motor unit 8 gives a steering assist force to the rack via the gear 10. At an end of electric motor unit 8 that is opposite to the output shaft side, the electronic controller 9 is provided. The electronic controller 9 controls an electric motor disposed in the electric motor unit 8, thus controlling driving of the electric motor unit 8. The electric motor unit 8 and the electronic controller 9 make up an electric drive unit. The torque sensor 7 may be provided as a separate sensor independent of the electric drive device 6.
When the steering wheel is operated, the steering shaft 2 is rotated clockwise or counterclockwise. At this time, the torque sensor 7 detects the rotation direction and the rotation torque of the steering shaft 2. Based on a detection value from the torque sensor 7, the electronic controller 9 calculates a drive operation amount of the electric motor unit 8.
Based on the calculated drive operation amount, the electronic controller 9 drives the electric motor unit 8 through a switching element 101 mounted on a board 31, which will be described later. As a result, the output shaft of the electric motor unit 8 is rotated in such a way as to drive the steering shaft 2 in the same direction as the operation direction. The rotation of the output shaft of the electric motor unit 8 is transmitted from the pinion (not illustrated) to the rack via the gear 10. Hence the automobile is steered.
An example of detailed configurations of the electric motor unit 8 and the electronic controller 9 will then be described with reference to
As shown in
The motor housing 21 has a cylindrical hole in which the electric motor is placed.
To one end in the axial direction of the motor housing 21, the pedestal 22 is fixed. To this pedestal 22, the electronic controller 9 is attached. The other end in the axial direction of the motor housing 21 is on the output shaft side of the electric motor unit 8.
The electronic controller 9 includes the board 31 carrying electronic components, the connector assembly 41, and a cover 51 covering the board 31 and a part of the connector assembly 41. A detailed configuration of the electronic controller 9 will be described later.
As shown in
The pedestal 22 is disposed in such a way as to close an opening on the one end in the axial direction of the motor housing 21. The pedestal 22 has a plurality of bearing surfaces 22a, a plurality of supports 23A, 23B, 23C, and 23D (four supports 23A, 23B, 23C, and 23D in this example), and a coil wire opening 25.
The bearing surfaces 22a are formed on one end face in the axial direction of the pedestal 22, the one end face being opposite to the motor housing 21. The bearing surfaces 22a are surfaces projecting from the pedestal 22 toward one side in the axial direction. On the bearing surfaces 22a, the board 31 is placed. Near the bearing surface 22a on the one end face of the pedestal 22, board fixing portions 26 are formed. Fastening screws (not illustrated) for fixing the board 31 are screwed into the board fixing portions 26.
The coil wire opening 25 is formed near the outer edge of the pedestal 22. The coil wire opening 25 is a through-hole penetrating the pedestal 22 from its one end face to the other end face opposite thereto. A plurality of coil wires 8A (six coil wires 8A in this example) of the electric motor are inserted through the coil wire opening 25.
The plurality of supports 23A, 23B, 23C, and 23D are arranged on the outer edge of the one end face of pedestal 22. The supports 23A, 23B, 23C, and 23D project from the one end face of the pedestal 22 toward the one side in the axial direction. The projection height of the supports 23A, 23B, 23C, and 23D is set higher than the projection height of the bearing surfaces 22a. On the front ends of the supports 23A, 23B, 23C, and 23D, connector fixing holes 27, into which fastening screws (not illustrated) for fixing the connector assembly 41 are screwed, are each formed.
On outer side surfaces of the supports 23A, 23B, 23C, and 23D, first caulking recesses 23a are each formed. The first caulking recesses 23a are formed by recessing the supports 23A, 23B, 23C, and 23D inward. The cover 51 is fitted into the first caulking recesses 23a by caulking.
The first support 23A is disposed close to one end in the longitudinal direction of the coil wire opening 25, with a gap formed between the first support 23A and the one end. The second support 23B is disposed close to the other end in the longitudinal direction of the coil wire opening 25, with a gap formed between the second support 23B and the other end. The coil wire opening 25 is, therefore, disposed between the first support 23A and the second support 23B. In addition, the periphery of the coil wire opening 25 is left open.
On the other end of pedestal 22 that is closer to the motor housing 21, an O-ring fitting portion 24 is formed. The O-ring fitting portion 24 is formed continuously on the outer peripheral surface of the pedestal 22 along its circumferential direction.
As shown in
The board 31 carries a power conversion circuit made up of switching elements 101, capacitors 102, terminal connections 103, a magnetic sensor (not illustrated), and a set of an FS relay and a power choke coil (not illustrated). To the terminal connections 103, a power supply terminal and a GND terminal, which project from the connector assembly 41, are electrically connected.
The switching elements 101 convert direct current into three-phase alternating current. The capacitors 102, which are provided as aluminum electrolytic capacitors or the like, perform charging/discharging to suppress voltage fluctuations, such as switching noise. The magnetic sensor (not illustrated) is a sensor that detects a rotation angle of the electric motor. The FS relay of the set of the FS relay and the power choke coil (not illustrated) is a circuit component that cuts off a current flow in the electric motor when the electronic controller 9 fails, and the power choke coil is a circuit component that suppresses a radio wave generated as switching noise.
The board 31 carries also an integrated circuit or the like that calculates a control signal for controlling the electric motor unit 8. The board 31 thus functions as a power supply board and as a control board as well. As a result, the number of boards included in the electronic controller 9 can be reduced to one.
The board 31 is formed substantially into a circular shape with four cutouts 31a formed thereon. The cutouts 31a are each formed at positions at which the cutouts 31a face the supports 23A, 23B, 23C, and 23D, when the board 31 is placed on the bearing surfaces 22a of the pedestal 22. This prevents the board 31 and the supports 23A, 23B, 23C, and 23D from interfering with each other. In addition, aligning the cutouts 31a of the board 31 with the supports 23A, 23B, 23C, and 23D facilitates positioning the board 31 relative to the pedestal 22.
The board 31 has a plurality of connection holes 32 (six connection holes 32 in this example) and fixing holes 33. The plurality of connection holes 32 are formed on a part of the outer edge of the board 31. The plurality of connection holes 32 are arranged at equal intervals along the outer edge of the board 31. As shown in
Hence the board 31 and the electric motor are electrically connected to each other.
When the board 31 is placed on pedestal 22, the fixing holes 33 face the board fixing portions 26 of the pedestal 22. Fastening screws (not illustrated) are inserted into the fixing holes 33, and are screwed into the board fixing portions 26. This fixes the board 31 to the pedestal 22.
On the surface of board 31 that is opposite to the pedestal 22, the connector assembly 41 is disposed. The connector assembly 41 includes a flat plate portion 42, and a plurality of connector housings 44 (three connector housings 44 in this example).
The connector assembly 41 includes also the power supply terminal and the GND terminal (not illustrated) which project from the flat plate portion 42 and connect to the terminal connections 103 of the board 31. By connecting together the terminal connections 103 and the power supply terminal and GND terminal (not illustrated), the board 31 and the connector assembly 41 are electrically connected to each other.
The flat plate portion 42 is of a substantially flat plate shape. As shown in
The flat plate portion 42 has a plurality of connector-side fixing portions 46. The plurality of connector-side fixing portions 46 each face the connector fixing holes 27, when the flat plate portion 42 is placed on the supports 23A, 23B, 23C, and 23D. Fastening screws (not illustrated) are inserted into the connector-side fixing portions 46, and are screwed into the connector fixing holes 27. This fixes the connector assembly 41 to the pedestal 22.
As shown in
On one surface of the flat plate portion 42, the one surface being opposite to a counter surface of flat plate portion 42 that is counter to the board 31, the connector housings 44 are provided. The connector housings 44 project along the axial direction of the electronic controller 9, from the one surface of the flat plate portion 42 toward the side opposite to the board 31.
The connector housings 44 are each formed into a cylindrical shape that encircles a connector terminal. In a cylindrical hole of the connector housing 44, a connection terminal of an external device is inserted. The direction of insertion of the connection terminal of the external device is parallel to the axial direction of the electronic controller 9 and the motor housing 21.
As shown in
In this manner, the plurality of connector housings 44 do not stick out in the radial direction perpendicular to the axial direction of the motor housing 21 and the pedestal 22. This allows miniaturization of the electronic controller 9 and the electric drive unit.
The flat plate portion 42 has a groove 45. The groove 45 is formed continuously in such a way as to encircle the plurality of connector housings 44. The groove 45 is formed by recessing the flat plate portion 42 from its one surface toward the opposite surface.
As shown in
The opening 54 sinks almost vertically from the main surface 53, and has a front end facing the other end in the axial direction. The front end of the opening 54 is fitted into the groove 45 of the connector assembly 41 (see
The other end in the axial direction of the side surface 52 is counter to the outer peripheral surface of one end side in the axial direction of the motor housing 21. The other end of the side surface 52 has positioning recesses 55. The positioning recesses 55 are formed by recessing the side surface 52 inward. The positioning recesses 55 are fitted into the second caulking recesses 21a of the motor housing 21. This facilitates positioning of the cover 51 relative to the motor housing 21 and the pedestal 22.
An assembling procedure for the electronic controller 9 having the above-described configuration will then be described with reference to
First, the connector assembly 41 is superposed on the board 31, and the power supply terminal and GND terminal (not illustrated) of the connector assembly 41 are connected to the terminal connections 103. The board 31 and the connector assembly 41 are then coupled together.
Subsequently, the board 31 coupled with the connector assembly 41 is placed on the bearing surfaces 22a of the pedestal 22, as shown in
The first support 23A and the second support 23B are arranged near the coil wire opening 25 such that a gap is formed between each of the first and second supports 23A and 23B and the coil wire opening 25. As a result, a space allowing comb-teeth jigs 71 (see
Thus, as shown in
Further, as shown in
Hence, as shown in
Subsequently, the coil wires 8A are connected to the board 31 by, for example, the spot flow soldering method. Hence the board 31 and the electric motor are electrically connected to each other. It should be noted that methods of connecting the coil wires 8A to the board 31 are not limited to the spot flow soldering method but include other various methods, such as a method using a solder iron for soldering and a method of melting solder by laser irradiation.
As described above, on the one side in the axial direction of the area of board 31 where the connection holes 32 are formed, the space allowing a tool to be inserted therein is formed. A tool for spot flow soldering, a solder iron, and the like can be inserted easily in the space, and therefore work of connecting the board 31 and the coil wires 8A together can be carried out easily. This facilitates assembling work of assembling the electronic controller 9 and the electric drive unit. In addition, increasing the size of the board 31 and the pedestal 22 to provide a space for tool insertion is unnecessary, which allows miniaturization of the electronic controller 9 and the electric drive unit.
In connection work using a solder iron or a laser, the plurality of coil wires 8A are connected to the board 31 one by one. In the electronic controller 9 and the electric drive unit of this example, in contrast, the plurality of coil wires 8A are collectively arranged at one part. Because of this arrangement, the spot flow soldering method can be applied to work of connecting the coil wires 8A and the board 31 together. Thus, the plurality of coil wires 8A can be simultaneously connected to the board 31 by the spot flow soldering method. As a result, a time required for work of connecting the board 31 and the coil wires 8A together can be reduced, which facilitates work of assembling the electronic controller 9 and the electric drive unit.
It should be noted that work of fixing the board 31 and the connector assembly 41 to the pedestal 22 may be carried out after the coil wires 8A are connected to the board 31.
Subsequently, the cover 51 is put on the connector assembly 41 and the board 31. The O-ring 29 is fitted in advance to the O-ring fitting portion 24 of the pedestal 22.
The groove 45 is filled with a sealant 91, which bonds the groove 45 and the opening 54 together. The sealant 91 thus fills up a gap between the groove 45 and the front end of the opening 54, thereby preventing entry of water from the opening 54 to the interior of the cover 51. A rubber gasket or the like may be used in place of the sealant 91.
Subsequently, as shown in
The first caulking portions 81 are formed on one side in the axial direction with respect to the O-ring 29 (see
By carrying out the caulking process of the cover 51 on its first caulking portions 81, outward expansion in the radial direction of the other end of cover 51 in the axial direction with respect to the O-ring 29 is suppressed by the second caulking portions 82 subjected to the caulking process. Likewise, by carrying out the caulking process of the cover 51 on its the second caulking portions 82, outward expansion in the radial direction of the one end of the cover 51 in the axial direction with respect to the O-ring 29 is suppressed by the first caulking portions 81 subjected to the caulking process.
As a result, the inner wall surface of the side surface 52 of the cover 51 can certainly be brought into close contact with the O-ring 29. This prevents entry of water from the other end side of the side surface 52 to the interior of the cover 51, thus improving a waterproofing effect.
In addition, because the cover 51 is fixed by the caulking process without using fastening screws, providing a flange or a projection for fitting fastening screws to the motor housing 21 or the pedestal 22 is unnecessary. This allows miniaturization of the electronic controller 9 and the electric drive unit.
Using a liquid gasket (FIPG: Formed In Place Gasket) as a means for fixing and waterproofing the cover 51 maybe a conceivable option. However, using the liquid gasket requires equipment for curing the liquid gasket, which takes much time to cure. Besides, the liquid gasket might peeled away from the cover 51 or the motor housing 21.
In contrast, waterproofing by the O-ring 29 and fixing the cover 51 by caulking makes equipment for curing the liquid gasket unnecessary. It also reduces a time required for fixing the cover 51, thus facilitating work of fixing the cover 51.
The example in which the first caulking recesses 23a are formed on the supports 23A, 23B, 23C, and 23D of the pedestal 22 has been described above. Formation of the first caulking recesses 23a is, however, is not limited to this example. The first caulking recesses 23a may be formed on the side surface of the pedestal 22 or may be formed on the motor housing 21.
It should be noted that the present invention is not limited to the embodiment described above and illustrated in the drawings, and that the invention may be modified into various forms within a range that does not deviate from the substance of the invention described in the claims.
In this specification, such terms as “parallel” and “perpendicular” are used. These terms should not be strictly interpreted as exact “parallel” and “perpendicular”, but should be interpreted as wider concepts that include “parallel” and “perpendicular” and “substantially parallel” and “substantially perpendicular” as well, which are substantially equivalent to “parallel” and “perpendicular” in terms of functional range.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-176096 | Sep 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/030854 | 8/14/2020 | WO |
