WO2012127516A1

WO2012127516A1 - Motor, actuator, and method for manufacturing motor

Info

Publication number: WO2012127516A1
Application number: PCT/JP2011/001633
Authority: WO
Inventors: 波多野　健太; 陽一藤田
Original assignee: 三菱電機株式会社
Priority date: 2011-03-18
Filing date: 2011-03-18
Publication date: 2012-09-27
Also published as: JPWO2012127516A1

Abstract

A cylindrical stator (9) has a C-shaped cross-section with a notch (9a) formed therein, the cylindrical stator is attached to the outer circumferential side of magnets (10a-10d) that are disposed in a circular pattern, and a motor housing (8) is formed of a resin member by means of integral molding. Spaces between the inner circumferential surface of the stator (9) and the outer circumferential surfaces of the magnets (10a-10d) are eliminated by, at the time of performing the integral molding, reducing the diameter of the stator (9), while pressing the stator to the magnets (10a-10d) by applying molding pressure to the stator.

Description

Motor and actuator, and motor manufacturing method

The present invention relates to a DC motor with a brush, a manufacturing method thereof, and an actuator using the motor.

In general DC motors, a sheet metal member is drawn (pressed) into a cup shape to form a stator, and a back yoke is bonded to the outer peripheral surface of the stator to secure a magnetic circuit. Then, the inner wall surface of the stator is protruded inward to form a stopper, and one end of each of the plurality of magnets is placed on the inner wall of the stator with the stopper being in contact with the stopper from both ends. An elastic member such as a clip is mounted (for example, see Patent Document 1).

JP 2000-278925 A

The conventional motor has a problem in that a gap corresponding to part size variation is generated between the stator inner wall and the magnet because the magnet is fixed by an elastic member and a stopper. As this gap increases, the leakage flux increases and the motor output decreases.

The present invention has been made to solve the above-described problems, and an object of the present invention is to improve motor characteristics by eliminating a gap between a stator and a magnet.

A motor according to the present invention is cylindrical and has a stator having a notch formed by notching a part of the stator in the axial direction, and a stator having a magnet that contacts the inner peripheral surface of the stator and covers the notch The housing is made of a resin member integrally formed with the stator and the magnet, and includes a housing that covers the outer peripheral surface of the stator and a rotor that is rotatably held on the inner peripheral side of the stator.

The actuator of the present invention includes the motor described above and an output shaft that linearly moves by converting the rotational motion of the rotor into a linear motion in the axial direction.

In the motor manufacturing method according to the present invention, a magnet is installed along the outer peripheral surface of the columnar convex portion in the mold, and a stator having a notch formed on the outer peripheral side of the magnet is attached to hold the magnet. And a step of injecting a resin member into the mold and applying a molding pressure to the stator to integrally mold the stator while reducing the diameter to form a housing.

According to the present invention, the stator and magnet having the notch formed therein are integrally molded into a stator, so that even if there are variations in part dimensions, the stator is pressed to reduce the diameter during integral molding. A gap between the magnet and the magnet can be reduced. As a result, the leakage magnetic flux between the stator and the magnet can be reduced, and the motor characteristics can be improved.

It is a longitudinal cross-sectional view which shows the structure of the actuator which concerns on Embodiment 1 of this invention. FIG. 3 is a cross-sectional view of the actuator stator according to Embodiment 1 cut along the line AA shown in FIG. 1. FIG. 3 is a diagram showing a configuration of a mold for molding a motor housing of the actuator according to the first embodiment. It is the figure which expanded the area | region B of FIG. 3 among the actuators which concern on Embodiment 1. FIG.

Hereinafter, in order to explain the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
1 includes a motor 4 that linearly drives a rod 3 connected to a shaft (output shaft) 2 in the axial direction X, and a pin shaft 5 that can be flexibly attached to the end of the rod 3. And a lever 7 that rotates. For example, an EGR (Exhaust Gas Recirculation) valve is connected to the fulcrum 6 of the lever 7 to control opening and closing, thereby adjusting the amount of exhaust gas in the exhaust passage of the automobile engine recirculated to the intake passage. The amount of exhaust gas flowing into the exhaust turbine is adjusted by connecting the output vane of the turbocharger to the fulcrum 6 and controlling the opening degree.

The motor 4 used in the actuator 1 is a DC motor with a brush, and a stator 9 and a magnet 10 are integrally formed in a resin motor housing 8 to form a stator. Inside the stator, a rotor core 11, a bobbin 12 attached to the rotor core 11, and a coil 13 wound around the bobbin 12 are integrally formed to constitute a rotor. The rotor is disposed at the center of the stator and is rotatably held by

bearings

14 and 15 that are press-fitted and fixed to the motor housing 8.

FIG. 2 is a cross-sectional view of the stator of the motor 4 taken along the line AA shown in FIG. As shown in FIGS. 1 and 2, a substantially cylindrical stator 9 is disposed on the inner peripheral surface of the substantially cylindrical motor housing 8, and a magnet 10 is disposed so as to contact the inner peripheral surface of the stator 9. Has been. Since the stator 9 is formed with a notch 9a that is partially cut in the axial direction X, the cross section is C-shaped. In the illustrated example, a plurality of (for example, four) arcuate magnets 10a to 10d are annularly arranged to constitute the magnet 10. In the following description, the magnets 10a to 10d are simply referred to as the magnet 10 if it is not necessary to distinguish them.

As shown in FIG. 1, an external input / output connector 17 is provided on a resin cover 16 that covers the upper opening of the motor housing 8, and a terminal 18 is protruded into the external input / output connector 17. An end portion of the terminal 18 is connected to a brush 19 fixed to the motor housing 8, and a commutator 20 is fixed to the rotor so as to face the brush 19. When a voltage is applied to the terminal 18, a current flows through the coil 13 via the brush 19 and the commutator 20, and the rotor core 11 polarized to a plurality of poles is NS magnetized. Then, the rotor is rotated by the magnetic force of the magnet 10 magnetized with NS. At that time, the stator 9 is arranged on the outer peripheral side of the magnet 10 to constitute a magnetic circuit.

One of the magnets 10a to 10d is arranged at a position covering the notch 9a of the stator 9 so that the magnetic circuit is not interrupted. In the example of FIG. 2, the magnet 10a covers the notch 9a.
Further, the areas of the two contact surfaces of the magnet 10a and the stator 9 are set to be equal to or larger than the cross-sectional area in the axial direction X of the stator 9 so as not to narrow the magnetic flux path (indicated by a white arrow in FIG. 2). That is, as shown in FIG. 2, assuming that the distance in the circumferential direction from each end of the arc-shaped magnet 10a to the notch 9a is t and the thickness in the radial direction of the stator 9 is T, on the outer peripheral side of the magnet 10a. A notch 9a is formed at a position where t ≧ T.

As shown in FIG. 1, a female screw portion 21 is formed in a central hole provided at the center of the rotor. On the other hand, a male screw portion 22 that is screwed into the female screw portion 21 is formed on the outer peripheral surface of the shaft 2. As the rotor rotates, the rotational force is transmitted to the male screw portion 22 meshed with the female screw portion 21, and the shaft 2 reciprocates in the axial direction X. An actuator housing 23 is fixed to an opening portion of the motor housing 8 opposite to the cover 16 fixing side, and a guide hole 24 through which the shaft 2 is inserted is formed in the actuator housing 23. The guide hole 24 serves as a bearing that supports the shaft 2 so as to be movable in the axial direction. Further, a part of the outer peripheral surface of the shaft 2 in the circumferential direction is made flat to form a rotation preventing portion 25, and a part of the inner peripheral surface of the guide hole 24 is made flat in accordance with the outer peripheral shape of the shaft 2. The anti-rotation part 26 is formed. Since the

rotation preventing portions

25 and 26 are fitted to prevent the shaft 2 from rotating in the guide hole 24, the shaft 2 does not rotate even if the rotational force of the rotor is transmitted. Moving. The rod 3 is connected to the tip of the shaft 2 penetrating the actuator housing 23 by a joint member 27.

Here, a method of integrally molding the motor housing 8, the stator 9, and the magnet 10 will be described. FIG. 3 is a schematic view showing a cross section of a mold for integrally molding the motor housing 8 with the stator 9 and the magnet 10. The mold is formed by combining the lower mold 100 and the upper mold 101, and the cylindrical protrusion 102, the motor housing 8 and the stator 9 are installed inside the lower mold 100 to integrally mold the motor housing 8. Are formed in a substantially concentric manner. In addition, although not shown, a gap or the like for press-fitting the bearing 15 may be provided. Further, a groove 104 for fitting the magnets 10a to 10d is formed on the bottom surface of the gap 103 of the lower mold 100.

First, each of the magnets 10a to 10d, which are insert parts, is arranged along the outer peripheral surface of the cylindrical convex portion 102 and is fitted into the groove 104 to be in a self-supporting state. Subsequently, the stator 9 formed with the notch 9a is attached to the outer peripheral side of the magnets 10a to 10d in this state, and the magnets 10a to 10d are held. Since the stator 9 has a spring property, the diameter can be reduced and expanded using the gap of the notch 9a. Therefore, even if the stator 9 and the magnets 10a to 10d have dimensional variations, the stator 9 is displaced and the variations are absorbed by the notch 9a, so that the magnets 10a to 10d can be held. Therefore, the dimensional accuracy of the stator 9 and the magnets 10a to 10d may not be high.

FIG. 4 is an enlarged view of region B in FIG. As shown in FIG. 4, the inner peripheral surface of the magnet assembly end portion of the stator 9 may be a tapered surface 9 b that expands toward the tip end side in the axial direction X. In this case, by inserting the magnets 10a to 10d from the tapered surface 9b side, the stator 9 can be easily displaced and can be easily mounted without being caught by the magnets 10a to 10d.

Finally, the lower mold 100 and the upper mold 101 are fitted and resin is injected into the gap 103 to form the motor housing 8, and the stator 9 and the magnets 10a to 10d are integrated to form a stator. Further, the mounting flange 8 a and the like may be formed simultaneously with the molding of the motor housing 8. Further, the stator 9 is pressed against the magnets 10a to 10d by using the molding pressure of the resin at this time, thereby reducing the diameter of the stator 9, and between the inner peripheral surface of the stator 9 and the outer peripheral surfaces of the magnets 10a to 10d. The gap can be eliminated. The displacement of the stator 9 due to the molding pressure is absorbed by the notch 9a.

The inner diameter of the stator 9 may be smaller than the outer diameter of the magnet 10 installed in the lower mold 100. In the case of this configuration, when the stator 9 is installed in the lower mold 100, the magnets 10a to 10d can be held by applying a preload using the spring property of the stator 9. Therefore, the magnets 10a to 10d, which are insert parts, do not tilt or play in the mold, and stable molding can be performed.

In the motor 4 which is a DC motor with a brush, the leakage magnetic flux decreases as the gap between the stator 9 and the magnet 10 is smaller due to the configuration of the magnetic circuit, and the motor characteristics are improved. In the prior art such as Patent Document 1 described in advance, the gap between the stator and the magnet is reduced by minimizing the dimensional variation of each component, but in the first embodiment, the molding pressure is reduced. It is possible to eliminate the gap (or make it much smaller than the conventional one) by displacing the stator 9 and bringing it into close contact with the magnet 10. Further, as described above, since the dimensional variation of the parts can be absorbed by the notch 9a, it is not necessary to increase the dimensional accuracy of the stator 9 and the magnet 10.

As described above, according to the first embodiment, the motor 4 used in the actuator 1 has a cylindrical shape and a stator 9 formed with a notch 9a in which a part thereof is notched in the axial direction X. A stator having a magnet 10 that contacts the inner peripheral surface and covers the notch 9a, a motor housing 8 that is made of a resin member integrally formed with the stator 9 and the magnet 10 and covers the outer peripheral surface of the stator 9, and an inner portion of the stator The rotor is configured to be rotatably supported on the circumferential side. For this reason, even if each of the magnets 10a to 10d constituting the magnet 10 and the stator 9 have dimensional variations, the stator 9 can be reduced in diameter by applying molding pressure to reduce the gap between the magnets 10. Moreover, since the notch 9a of the stator 9 is covered with the magnet 10a, a magnetic circuit can be secured even if a part of the stator 9 is notched. As a result, the leakage magnetic flux between the stator 9 and the magnet 10 can be reduced, and the motor characteristics can be improved. Furthermore, even if the dimensional variation is large, it can be absorbed by the notch portion 9a of the stator 9, so that the stator 9 and the magnet 10 do not require high dimensional accuracy, the part productivity can be improved, and the cost can be reduced.

Further, according to the first embodiment, the notch portion 9 a of the stator 9 has a circumferential distance t from each end of the magnet 10 a covering the notch portion 9 a to the notch portion 9 a in the radial direction of the stator 9. It was made to form in the position used as thickness T or more. As a result, a necessary and sufficient magnetic circuit can be secured without narrowing the magnetic flux path, and stable motor characteristics can be secured.

Further, according to the first embodiment, since the inner diameter of the stator 9 before the integral molding is made smaller than the outer diameter of the magnet 10, even if the stator 9 and the magnet 10 have dimensional variations, the spring of the stator 9 It is possible to hold the magnet 10 by applying a preload using the property. Thereby, stable molding can be performed without the magnet 10 that is the insert part being tilted or loose in the mold.

Further, according to the first embodiment, the inner peripheral surface of the magnet assembly end portion of the stator 9 is the tapered surface 9b that widens toward the tip in the axial direction X, so the stator 9 is installed in the mold. In this case, the insertability into the magnet 10 is improved and the productivity is improved.

In the present invention, any component of the embodiment can be modified or any component of the embodiment can be omitted within the scope of the invention.

As described above, since the motor according to the present invention improves the motor characteristics by eliminating the gap between the stator and the magnet, it is suitable for use in a brushed DC motor for driving the actuator.

1 Actuator, 2 shaft, 3 rod, 4 motor, 5 pin shaft, 6 fulcrum, 7 lever, 8 motor housing, 8a mounting flange, 9 stator, 9a notch, 9b taper surface, 10, 10a-10d magnet, 11 rotor core , 12 bobbin, 13 coil, 14, 15 bearing, 16 cover, 17 external input / output connector, 18 terminal, 19 brush, 20 commutator, 21 female screw part, 22 male screw part, 23 actuator housing, 24 guide hole, 25 , 26 Non-rotating part, 27 joint member, 100 lower mold, 101 upper mold, 102 cylindrical convex part, 103 gap, 104 groove.

Claims

A stator that is cylindrical and has a notch formed in a part of which is cut out in the axial direction, and a stator that has a magnet that contacts the inner peripheral surface of the stator and covers the notch,
A housing made of a resin member integrally molded with the stator and the magnet, and covering the outer peripheral surface of the stator;
A motor comprising a rotor that is rotatably held on an inner peripheral side of the stator.
The notch portion of the stator is formed at a position where each circumferential distance from each end portion of the magnet covering the notch portion to the notch portion is equal to or greater than the radial thickness of the stator. The motor described.
2. The motor according to claim 1, wherein the inner diameter of the stator before integral molding is smaller than the outer diameter of the magnet.
2. The motor according to claim 1, wherein the inner peripheral surface of the magnet attachment end portion of the stator has a tapered shape spreading toward the tip in the axial direction.
A stator that is cylindrical and has a notch formed in a part of which is cut out in the axial direction, and a stator that has a magnet that contacts the inner peripheral surface of the stator and covers the notch,
A housing made of a resin member integrally molded with the stator and the magnet, and covering the outer peripheral surface of the stator;
A rotor rotatably held on the inner peripheral side of the stator;
An actuator comprising: an output shaft that linearly moves by converting rotational motion of the rotor into linear motion in the axial direction.
A stator that is cylindrical and has a notch formed in a part thereof in the axial direction, a stator having a magnet that contacts the inner peripheral surface of the stator and covers the notch, and an outer peripheral surface of the stator A method of manufacturing a motor comprising a resin housing covering
Installing the magnet along the outer peripheral surface of the cylindrical convex portion in the mold, attaching the stator formed with the notch on the outer peripheral side of the magnet, and holding the magnet;
A method of manufacturing a motor, comprising: injecting a resin member into the mold and forming the housing integrally by forming the stator integrally while reducing the diameter by applying molding pressure to the stator.