JP2015229435A - Brushless motor and electric power steering device equipped with the same and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless motor which is lightweight, is easily manufactured, and includes a motor housing achieving compactification including attachment of an ECU, and to provide an electric power steering device equipped with the brushless motor and a vehicle.SOLUTION: A brushless motor including a motor housing having an integral structure where a motor attachment flange is provided at one end side of a motor yoke and an ECU attachment flange is provided at the other end side.

Description

  The present invention relates to a brushless motor having an integral motor housing made of aluminum, zinc alloy, or magnesium alloy, provided with a motor mounting flange on one end side of the motor yoke and an ECU mounting flange on the other end side, and The present invention relates to an electric power steering apparatus and a vehicle equipped with the same. An electric power steering device mounted on a vehicle applies an assist force by a motor (for example, a brushless motor) to a steering system of the vehicle based on a current command value calculated based on at least a steering torque, and includes a bridge circuit. Drive controlled by an inverter.

  There is an electric power steering device (EPS) as a device equipped with a brushless motor in the drive unit, and the electric power steering device applies a steering assist force (assist force) to the steering mechanism of the vehicle by the rotational force of the motor, The driving force of the motor controlled by the electric power supplied from the inverter is applied to the steering shaft or the rack shaft by a transmission mechanism such as a gear. Such a conventional electric power steering apparatus performs feedback control of the motor current in order to accurately generate the torque of the steering assist force. In feedback control, the motor applied voltage is adjusted so that the difference between the steering assist command value (current command value) and the motor current detection value is small. The adjustment of the motor applied voltage is generally performed by PWM (pulse width). Modulation) is performed by adjusting the duty of the control, and as a motor, a brushless motor that is excellent in durability and maintainability, and has less noise and noise is generally used.

  The general configuration of the electric power steering apparatus will be described with reference to FIG. The tie rods 6a and 6b are connected to the steered wheels 8L and 8R via the hub units 7a and 7b. Further, the column shaft 2 is provided with a torque sensor 10 for detecting the steering torque of the handle 1 and a steering angle sensor 14 for detecting the steering angle θ, and the motor 20 for assisting the steering force of the handle 1 is provided with the reduction gear 3. Are connected to the column shaft 2 via The control unit (ECU) 30 that controls the electric power steering apparatus is supplied with electric power from the battery 13 and also receives an ignition key signal via the ignition key 11. The control unit 30 calculates a current command value of an assist (steering assistance) command based on the steering torque Th detected by the torque sensor 10 and the vehicle speed Vel detected by the vehicle speed sensor 12, and compensates the current command value. The current supplied to the EPS motor 20 is controlled by the voltage control command value Vref subjected to.

  The steering angle sensor 14 is not essential and may not be provided, and the steering angle can be obtained from a rotation sensor such as a resolver connected to the motor 20.

  The control unit 30 is connected to a CAN (Controller Area Network) 40 that exchanges various types of vehicle information, and the vehicle speed Vel can also be received from the CAN 40. The control unit 30 is also connected to a non-CAN 41 that exchanges communications other than the CAN 40, analog / digital signals, radio waves, and the like.

  An example of a power transmission mechanism of the motor 20 of the electric power steering apparatus and a connection example of the motor 20 and the control unit (ECU) 30 are as shown in FIG.

  As shown in FIG. 2, the output shaft 21 of the motor 20 extends to the outside of the motor housing 22, and the motor housing 22 that forms a motor yoke is a substantially bottomed cylinder that houses a motor body having a rotor and the like. The case main body 23 and a motor attachment portion 24 attached to the opening side of the case main body 23 are configured. The motor mounting portion 24 is formed in a plate shape as a whole, and the output shaft 21 is inserted through the outside of the motor mounting portion 24 through a through hole in the center thereof. The motor mounting portion 24 may be formed in a flange shape.

  The power transmission mechanism 50 includes a worm speed reduction mechanism including a worm 51 and a worm wheel 52, and includes a connecting portion 53 that connects the worm speed reduction mechanism and the output shaft 21. The worm 51 is formed at an intermediate portion of a worm shaft 51 </ b> A coaxial with the output shaft 21 and meshes with the worm wheel 52. An upper (handle) side output shaft 2 </ b> A of the column shaft 2 that rotates integrally with the worm wheel 52 is connected to the shaft center of the worm wheel 52. The rotation of the motor 20, that is, the rotation of the output shaft 21, is decelerated by the worm deceleration mechanism and transmitted to the upper output shaft 2A.

  The internal space of the motor mounting portion 54 on the speed reduction mechanism side is formed in a trumpet shape so as to expand toward the motor 20 side (opening side), and the motor mounting portion 54 is formed on the motor mounting portion 24 on the motor 20 side. By bolting, the opening of the motor mounting portion 54 is closed. In the state shown in FIG. 2 in which the motor 20 is attached to the motor attachment portion 54, the connecting portion 53 and the output shaft 21 are positioned at the axial center of the internal space of the motor attachment portion 54. When the motor mounting portion 24 is formed in a flange shape, the motor mounting portion 54 is also formed in a flange shape correspondingly.

  The motor 20 and the control unit (ECU) 30 or the ECU board are separated from each other by a lead wire 31, and the motor 20 is driven and controlled by the control unit (ECU) 30 via the lead wire 31.

  Even in such an electric power steering device, there is a demand for weight reduction and compactness including the motor, and even when external force is applied to the housing, smooth rotation can be maintained. Improvement of shaft accuracy is strongly desired.

  As a motor yoke, there is a flange welding structure in sheet metal working (drawing yoke structure with a steel plate). For example, JP 2004-180449 A (Patent Document 1) describes a housing that constitutes a brushless motor as aluminum that is lighter than iron. And a brushless motor for an electric power steering apparatus in which substantially the entire outer peripheral surface of the outer core is pressed against the inner peripheral surface of the housing.

JP 2004-180449 A JP 2005-168099 A

  However, the brushless motor of Patent Document 1 can achieve weight reduction and stabilization against external force, but it has not been solved at all about downsizing of the whole, improvement of assemblability and shaft accuracy.

  On the other hand, Japanese Unexamined Patent Application Publication No. 2005-168099 (Patent Document 2) discloses an electric power steering device and a manufacturing method that can reduce labor during motor assembly and prevent damage to the motor during assembly. Yes. In Patent Document 2, the housing is formed of an aluminum alloy, and the output shaft of the motor is provided integrally with the drive gear of the speed reduction mechanism. The speed reducer housing of the subassembly integrally connects the motor housing and holds the output shaft. doing. The outer periphery of the rotor held by the output shaft is surrounded and protected by the motor housing.

  However, Patent Document 2 has a structure of a housing case in which a speed reducing portion is integrated, and there is no mention of compactness including an ECU, connection relation with the ECU, improvement of shaft accuracy, and the like.

  As described above, in the prior art, the number of parts increases when the motor is mounted and connected to an accessory part such as an ECU, and the accuracy of the motor shaft is accumulated as the accuracy of each part, and the cost is increased to guarantee the accuracy. There was also a factor that led to

  The present invention has been made under the circumstances as described above, and an object of the present invention is to provide a brushless motor including a motor housing that is lightweight and easy to manufacture, and that has a compact motor housing including an ECU. An object is to provide an electric power steering apparatus and a vehicle that are mounted.

  The present invention relates to a brushless motor, and the above object of the present invention is achieved by providing a motor housing having an integral structure in which a motor mounting flange is provided on one end side of the motor yoke and an ECU mounting flange is provided on the other end side. .

  The object of the present invention is to provide a linear expansion coefficient compensating ring formed by insert casting on the inner side of the motor housing, or to arrange the motor internal components from one direction with respect to the motor housing. Due to the structure of sequential assembly, or because the motor internal components are in the order of the stator assembly, rotor assembly, motor cover, or the ring has a hole, notch, or groove detent mechanism. The motor cover is made of an aluminum material, a zinc alloy, a magnesium alloy, or a sheet metal material, and the rotor housing is held by mounting the motor cover, or the motor housing is made of an aluminum material or To be a casting of zinc alloy and magnesium alloy Ri, is more effectively achieved.

  An electric power steering device that applies an assist force to a steering system of a vehicle and a vehicle equipped with the same are achieved by a current command value that is drive-controlled by the brushless motor and is calculated based on at least a steering torque.

  According to the brushless motor of the present invention, it is provided with a motor housing made of aluminum, zinc alloy or magnesium alloy which can be easily cast by die casting, and has a motor mounting flange and an ECU mounting flange at the end of the motor housing. Therefore, it is possible to improve the assembling property and the shaft accuracy, and to easily manage the accuracy.

  By applying the brushless motor to an electric power steering device, a lightweight, compact and highly reliable electric power steering device can be achieved. By mounting the electric power steering device on a vehicle, the vehicle can be reduced in weight. I'm going.

It is a lineblock diagram showing an outline of an electric power steering device. It is a figure which shows the connection example of the connection mechanism example of the motor of the electric power steering device, the connection part of a deceleration part, and a control unit (ECU). It is a perspective view which shows the structural example of the motor housing which concerns on this invention. It is an assembly development view of the brushless motor concerning the present invention. 1 is a cross-sectional structure diagram of a brushless motor according to the present invention. It is a partial cross section mechanism figure showing an example of composition which equipped with a motor concerning the present invention. It is the front view and side view which show the state which mounted | wore the brushless motor which concerns on this invention with ECU. It is a perspective view which shows the other structural example of the motor housing which concerns on this invention. It is a perspective view which shows the other structural example of the ring which carries out insert casting.

  The present invention integrally molds an ECU mounting flange and a motor mounting flange in a housing made of aluminum, zinc alloy, or magnesium alloy (aluminum die casting), stator assembly (ASSY), rotor assembly (ASSY), motor A brushless motor that achieves weight reduction and downsizing of the motor, is easy to assemble, and has good axial accuracy by sequentially incorporating (press-fitting or shrink fitting) the motor internal parts of the cover from one direction. By making the motor housing die-cast aluminum (or other casting material (zinc alloy or magnesium alloy) is also possible), the motor mounting flange on the power transmission mechanism side end of the reduction gear (gearbox) and the other end side The motor housing structure is integrated with the ECU mounting flange. Such a flange-integrated structure exhibits the effects of reducing the weight and size, improving the assemblability, and improving the shaft accuracy compared to the flange and yoke structure of the conventional motor structure.

  In addition, internal parts of the motor such as an Fe-based stator assembly are press-fitted or shrink-fitted into a motor housing made of aluminum, zinc alloy or magnesium alloy. After assembly, the environmental conditions (specifications) of the product will affect the product. Therefore, the linear expansion coefficient is compensated by insert casting a cylindrical ring made of Fe in the motor housing. In addition, the ring is provided with a hole, a notch, a groove, and the like to prevent rotation, and also prevents slippage in the axial direction.

  Embodiments of the present invention will be described below with reference to the drawings. The aluminum die casting will be described below, but the same can be applied to a zinc alloy die casting and a magnesium alloy die casting.

  FIG. 3 shows the structure of the motor housing 110 of the brushless motor 100 of the present invention. The housing main body 113 has a cylindrical shape, and the bottom has a planar structure with an opening through which the motor output shaft projects at the center. Yes, the bottom also serves as the motor front cover (end plate). An ECU mounting flange 111 protrudes outward from the upper end (on the drawing) of the housing body 113, and a motor mounting flange 112 protrudes outward from the lower end (on the drawing). It has been. The motor housing 110 is integrally molded with an ECU mounting flange 111 and a motor mounting flange 112 by casting with aluminum die casting.

  In FIG. 3, there are two ECU mounting flanges 111 having a large and small symmetrical structure, and a symmetrical motor mounting flange 112 so as to intersect the ECU mounting flange 111. The number, shape, position, and the like can be changed as appropriate. It can be provided at any position, angle, and direction (vertical and horizontal) in consideration of motor attachment, ECU attachment, and the like. Further, the flanges 111 and 112 may have a disk shape.

  As shown in FIG. 4, the internal parts of the motor are press-fitted or shrink-fitted into such a motor housing 110 and assembled to assemble the brushless motor 100. That is, the stator assembly (ASSY) 120 is first inserted into the motor housing 110 and press-fitted or shrink-fitted, and then the rotor assembly (ASSY) 130 is inserted into the stator assembly 120 fixed to the motor housing 110 to press-fit or shrink. Finally, a motor cover 140 made of an aluminum material or a sheet metal material is attached and fixed to the stator assembly 120 with screws 141 or the like. The stator assembly 120 and the motor cover 140 are provided with bearings (121, 142), respectively, and hold the shafts (131, 132) of the rotor assembly 130 to rotate.

  By such an assembling process, the brushless motor 100 whose sectional structure is shown in FIG. 5 is obtained. A motor output shaft 131 protrudes from an opening in the bottom surface (front cover) of the motor housing 110. Further, the shafts 131 and 132 of the rotor assembly 130 are held by bearings 142 and 121, respectively, and are rotatable.

  The brushless motor 100 according to the present invention is attached to a reduction gear (gear box) via a motor mounting flange 112 in the form shown in FIG. 6, and the ECU 200 is connected to the brushless motor 100 via the ECU mounting flange 111. Mounted on. The attachment by the flanges 111 and 112 may be performed with bolts, nuts, and screws.

  FIG. 7 is a front view and a side view showing how the ECU 200 is attached to the brushless motor 100. The ECU 200 is connected to the ECU mounting flange 111 via terminal blocks 201 and 202 provided on the bottom side of the ECU 200 (on the drawing). In addition, electrical connections are made together. The connection between the terminal blocks 201 and 202 and the ECU mounting flange 111 may be performed by bolts, nuts, screws, insertion-type fixing members, or the like.

  Since the motor housing 110 of the present invention is made of aluminum and the stator assembly 120 is mainly made of an Fe-based material, the linear expansion coefficients of the two differ. The motor housing 110 and the stator assembly 120 are affected by the linear expansion coefficient due to the temperature change, resulting in an error in dimension setting when the motor parts are assembled. After the assembly, there is a gap between the motor housing 110 and the stator assembly. Undesirable relative rotational misalignment occurs with the assembly 120.

  Therefore, in the present invention, as shown in FIG. 8, a cylindrical ring 115 made of an Fe-based material and having the same linear expansion coefficient as the stator assembly 120 is provided by insert casting inside the motor housing 110. The ring 115 is integrally formed with the motor housing 110, and the stator assembly 120 is press-fitted or shrink-fitted into the motor housing 110, whereby the ring 115 is interposed between the stator assembly 120 and the motor housing 110. By interposing the ring 115, it is possible to eliminate the influence of the difference in linear expansion coefficient between the motor housing 110 and the stator assembly 120.

  FIG. 9 shows another shape of the ring. The ring 115A in FIG. 9A is an example in which several rectangular notches 116 are provided at the lower end of the ring. At the time of aluminum die casting, since the notch 116 is also molded with aluminum, the motor housing 110 is prevented from rotating. FIG. 9B is an example in which several round holes 117 are provided on the wall surface of the ring 115B, and in addition to detents, it also prevents axial removal. Further, FIG. 9C shows an example in which a groove 118 perpendicular to the wall surface of the ring 115C is provided. If the groove 118 is provided in an inclined manner, it can be prevented from coming off in addition to rotation prevention.

1 Handle 2 Column shaft (steering shaft, handle shaft)
DESCRIPTION OF SYMBOLS 10 Torque sensor 12 Vehicle speed sensor 14 Rudder angle sensor 20 Motor 21 Rotation sensor 30, 200 Control unit (ECU)
40 CAN
100 Brushless motor 110, 110A Motor housing 111 ECU mounting flange 112 Motor mounting flange 115, 115A to 115C Ring 120 Stator assembly (ASSY)
130 Rotor assembly (ASSY)
140 Motor cover

Claims (9)

A brushless motor comprising a motor housing having an integral structure in which a motor mounting flange is provided on one end side of the motor yoke and an ECU mounting flange is provided on the other end side. The brushless motor according to claim 1, wherein a ring for linear expansion coefficient compensation formed by insert casting is provided inside the motor housing. The brushless motor according to claim 1, wherein the motor housing has a structure in which motor internal components are sequentially assembled in one direction with respect to the motor housing. The brushless motor according to claim 3, wherein the motor internal components are in the order of a stator assembly, a rotor assembly, and a motor cover. The brushless motor according to claim 2, wherein the ring has a hole, a notch, or a groove detent mechanism. The brushless motor according to claim 4, wherein the motor cover is made of an aluminum material, a zinc alloy, a magnesium alloy, or a sheet metal material, and has a structure in which a rotor bearing is held by mounting the motor cover. The brushless motor according to any one of claims 1 to 6, wherein the motor housing is a cast molding of an aluminum material, a zinc alloy, or a magnesium alloy. 8. An electric power steering system that is driven and controlled by the brushless motor according to claim 1 and that applies an assist force to a steering system of a vehicle based on a current command value calculated based on at least a steering torque. apparatus. A vehicle equipped with the electric power steering device according to claim 8.

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