JP2005073338A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce material cost and manufacturing cost of a stepping motor which moves/drives the valve body of a valve. <P>SOLUTION: A wear reduction/axial direction locking member 9 of a flanged tube is attached to a rotation restricting part 2a of a stator 2. A rotation restricted part 5a of a valve body 5 slides on a tubular part 9a of the wear reduction/axial direction locking member 9. The valve body 5 abuts on a flange 9b of the wear reduction/axial direction locking member 9 to stop retreating of a shaft 3. Since the wear reduction/axial direction locking member 9 exhibits both a wear reduction function and an axial direction locking function, the number of components is decreased by one. Since the wear reduction/axial direction locking member 9 is attached to the stator 2 side, the tubular part 9a of the wear reduction/axial direction locking member 9 is not required to be extended according to the stroke of the shaft 3. In the molding process of the valve body 5, only the shaft 3 is required to be integrally molded. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stepping motor used to move a valve body of a valve closer to or away from a valve seat, for example, for the purpose of adjusting a flow rate of an air-fuel mixture supplied into a cylinder of an automobile engine. .

  3A and 3B are diagrams showing an example of a conventional stepping motor, in which FIG. 3A is a front sectional view thereof, and FIG. 3B is a sectional view taken along line BB in FIG.

  Conventionally, as this type of stepping motor, a motor having a mechanism for moving the valve body integrated with the shaft back and forth by converting the rotational motion of the rotor supported by the stator into the linear motion of the shaft is known. (For example, refer to Patent Document 1).

  That is, in this stepping motor 1, as shown in FIG. 3, a cylindrical rotor (not shown) is rotatably inserted in an approximately cylindrical stator 2 by electromagnetic force, and a shaft 3 is inserted into the rotor. Are inserted in the axial direction (arrows M and N directions) so as to freely advance and retract. Here, a female screw portion is formed on the inner peripheral surface of the rotor, and a male screw portion is formed on the outer peripheral surface of the shaft 3. The male screw portion of the shaft 3 is screwed into the female screw portion of the rotor. . Further, the valve body 5 of the valve is integrally attached to the tip of the shaft 3 by resin molding, and the valve body 5 has a double D-cut cross-sectional shape (circumferentially on the circumference) as shown in FIG. A rotation constrained portion 5a having a cross-sectional shape obtained by cutting out two places into a D shape is formed. On the other hand, the stator 2 is formed with a rotation restricting portion 2 a that fits into the rotation restricted portion 5 a of the valve body 5. Therefore, when the rotor rotates in the forward and reverse directions, the shaft 3 and thus the valve body 5 moves forward or backward in the axial direction of the shaft 3.

In this stepping motor 1, wear occurs between the rotation restricting portion 2 a of the stator 2 and the rotation restricted portion 5 a of the valve body 5 as the shaft 3 advances and retreats (forward and backward). For the purpose of reducing wear, a metal wear reducing member 6 formed in a cylindrical shape is fitted to the outer periphery of the rotation restricted portion 5 a of the valve body 5. Further, when the shaft 3 is retracted to the rotor side (in the direction of arrow N), a metal axial locking member 7 formed in a cylindrical shape is integrated with the valve body 5 in order to stop the retracting operation at a predetermined position. Is attached.
JP-A-5-284717

  However, this has the following disadvantages.

  First, since the stepping motor 1 requires two parts, the wear reducing member 6 and the axial locking member 7, the material cost of the stepping motor 1 must be increased by that amount. Moreover, since the wear reduction member 6 is attached to the valve body 5 side, the wear reduction member 6 must be fitted over the entire length of the stroke of the shaft 3, and in particular, the stroke of the shaft 3 (the travel distance of the valve body 5). ) Is longer, the longer wear reduction member 6 is required, and the material cost of the stepping motor 1 also increases from this point.

  Second, when manufacturing the stepping motor 1, in the molding process of the valve body 5, the operator inserts the shaft 3, the wear reducing member 6 and the axial locking member 7 into the molding die. Since these three parts must be integrally molded by molding, the time required for molding the valve body 5 is prolonged, and the manufacturing cost of the stepping motor 1 is increased. Although it is conceivable to automate the molding process of the valve body 5 by robot work, it is not realistic in that it is expensive in the initial stage.

  In view of such circumstances, an object of the present invention is to provide a stepping motor capable of reducing material costs and manufacturing costs.

  First, the invention according to claim 1 of the present invention has a stator, a rotor is rotatably inserted in the stator, and a shaft is screwed into the rotor so as to advance and retreat in the axial direction thereof. In a stepping motor in which a controlled body is attached to the tip, a rotationally restrained portion having a non-circular cross-sectional shape is formed on the controlled body, and a rotationally restraining portion is formed on the stator so as to be fitted to the rotationally restrained portion. And mounting a flanged cylindrical wear reduction / axial locking member on the rotation restraining portion of the stator so that the rotationally restrained portion of the controlled body becomes a cylindrical portion of the wear reduction / axial locking member. The control body is configured to slide against the wear-reducing and axially engaging member and stop the retreating operation of the shaft. An example of the controlled body is a valve body of a valve. Further, a non-circular cross-sectional shape may be a double D-cut cross-sectional shape.

  According to a second aspect of the present invention, a cylindrical skirt portion is formed on the controlled body to cover the wear reduction / axial locking member.

  According to the first aspect of the present invention, since the wear reduction / axial locking member exhibits both the wear reduction function and the axial locking function, the wear reducing member and the axial locking member In addition to reducing the number of parts by one compared to conventional stepping motors that require two parts, the wear reduction / axial locking member is attached to the stator, so the wear reduction member is a valve. Unlike conventional stepping motors attached to the body side, even if the stroke of the shaft is long, it is not necessary to reduce wear and lengthen the cylindrical part of the axial locking member according to the length of the stepping motor. The material cost can be reduced. In addition, since the wear reduction / axial locking member is attached to the stator, only the shaft needs to be integrally formed in the molding process of the controlled body. Compared to the conventional stepping motor that must be integrally molded, the time required for molding the controlled body is shortened, and the manufacturing cost of the stepping motor can be reduced.

  Further, according to the invention according to claim 2 of the present invention, the occurrence of a situation in which the fluid flowing through the valve or the like enters the stator through the clearance between the axial locking member and the controlled body is reduced. can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a stepping motor according to the present invention, where (a) is a front sectional view thereof, (b) is a sectional view taken along line BB of (a),
2 is a detailed view of the wear reduction / axial locking member of the stepping motor shown in FIG. 1, wherein (a) is a plan view thereof, (b) is a front view thereof, and (c) is a C portion of (a). It is sectional drawing by -C line | wire.

  As shown in FIG. 1, the stepping motor 1 has a substantially cylindrical stator 2, and a cylindrical rotor (not shown) is rotatably inserted into the stator 2 by electromagnetic force. . Further, the shaft 3 is screwed to the rotor so as to be able to advance and retreat in the axial direction (directions of arrows M and N). Here, a female screw portion is formed on the inner peripheral surface of the rotor, and a male screw portion is formed on the outer peripheral surface of the shaft 3, and the male screw portion of the shaft 3 is screwed into the female screw portion of the rotor. Yes. Also, a valve body 5 of a synthetic resin valve is integrally attached to the tip of the shaft 3 by resin molding as a controlled body. The valve body 5 has a double D as shown in FIG. A rotation constrained portion 5a having a cut cross-sectional shape (a cross-sectional shape which is a kind of non-circular cross-sectional shape and is cut off at two locations on the circumference in a D shape) is formed. On the other hand, the stator 2 is formed with a rotation restricting portion 2 a that fits into the rotation restricted portion 5 a of the valve body 5. Further, as shown in FIG. 1A, the valve body 5 is formed with a cylindrical skirt portion 5 b so as to cover the wear reduction / axial locking member 9. A valve seat (not shown) is provided oppositely. Therefore, when the rotor rotates in the forward / reverse direction, the shaft 3 moves forward or backward in the axial direction of the shaft 3 while restraining the rotation, and accordingly the valve body 5 approaches or moves away from the valve seat. The flow rate of the valve will increase or decrease.

  By the way, as shown in FIG. 1, the rotation restraining portion 2a of the stator 2 is provided with a metal wear reduction / axial locking member 9 formed in a cylindrical shape with a flange. As shown in FIG. 2, the locking member 9 includes a cylindrical portion 9 a having a double D-cut cross-sectional shape and a flange portion 9 b provided at one end of the cylindrical portion 9 a.

  Since the stepping motor 1 has the above-described configuration, when the shaft 3 advances and retreats in the axial direction (directions of arrows M and N), the rotation constrained portion 5a of the valve body 5 is opposed to the rotation constraining portion 2a of the stator 2. Although it moves in the axial direction of the shaft 3, the rotation restraining portion 2 a of the stator 2 is equipped with a wear reduction / axial locking member 9, and the rotationally restrained portion of the valve body 5 with respect to the cylindrical portion 9 a. Since 5a slides, the wear between them is reduced. Further, if the shaft 3 moves back in the axial direction (arrow N direction), the valve body 5 moves to the stator 2 side, but the rotation restraining portion 2a of the stator 2 is provided with a wear reduction / axial locking member 9. Therefore, the valve body 5 comes into contact with the flange portion 9b and the backward movement of the shaft 3 is stopped at a predetermined position.

  Thus, in this stepping motor 1, the wear reduction / axial locking member 9 exhibits a wear reduction function for reducing wear caused by the advance / retreat of the shaft 3 in the axial direction, and at the same time, the shaft 3 moves backward. An axial direction locking function for stopping at a predetermined position will be exhibited. As a result, since the number of parts can be reduced by one as compared with the conventional stepping motor 1 (see FIG. 3) that requires two parts of the wear reducing member 6 and the axial locking member 7, the material of the stepping motor 1 is used. Cost can be reduced.

  In addition, since the wear reduction / axial locking member 9 is attached to the stator 2 side rather than the valve body 5 side, even if the stroke of the shaft 3 (movement distance of the valve body 5) is long, the length thereof is reduced. Accordingly, there is no need to lengthen the cylindrical portion 9a of the wear reduction / axial locking member 9, and the material cost of the stepping motor 1 can be reduced from this point.

  Further, as described above, since the wear reduction / axial locking member 9 is attached to the stator 2 side instead of the valve body 5 side, when manufacturing the stepping motor 1, in the molding process of the valve body 5 It is sufficient to integrally mold only the shaft 3 to the valve body 5. As a result, compared with the conventional stepping motor 1 (see FIG. 3) in which the wear reduction member 6 and the axial locking member 7 must be integrally formed in addition to the shaft 3, the time required for molding the valve body 5 is reduced. Since the length is shortened, the manufacturing cost of the stepping motor 1 can be reduced.

  Further, since the skirt portion 5 b is formed on the valve body 5 so as to cover the wear reduction / axial locking member 9, the fluid flowing through the valve reduces the wear / axial locking member 9 and the valve body 5. Occurrence of a situation of entering the stator 2 through the gap can be suppressed.

  In the above-described embodiment, the case where the valve body 5 is used as the controlled body has been described. However, the present invention can also be applied to the stepping motor 1 including a controlled body other than the valve body 5. For example, an active headlight of a car (in order to prevent nighttime car accidents, the light axis is directed in the direction of travel by moving the reflector left and right or up and down based on the turning angle of the steering wheel and the vehicle speed at intersections and curves, etc. A connecting member of a reflecting mirror in a controllable headlight may be used as a controlled body.

  Moreover, in the above-mentioned embodiment, although the case where the double D cut cross-sectional shape was employ | adopted as a cross-sectional shape of the rotation restricted part 5a of the valve body 5 was demonstrated, the cross-sectional shape of the rotation restricted part 5a of the valve body 5 is non. As long as it has a circular cross-sectional shape, the rotation of the valve body 5 is restricted, so any cross-sectional shape may be used. For example, it is also possible to employ a cross-sectional shape in which one or more protrusion-like cross sections are arranged on the circumference of the circular cross section as the cross-sectional shape of the rotation restricted portion 5a of the valve body 5.

It is a figure which shows one Embodiment of the stepping motor which concerns on this invention, Comprising: (a) is the front sectional drawing, (b) is sectional drawing by the BB line of (a). It is a detailed view of the wear reduction / axial locking member of the stepping motor shown in FIG. 1, wherein (a) is a plan view thereof, (b) is a front view thereof, and (c) is a CC line of (a). It is sectional drawing by. It is a figure which shows an example of the conventional stepping motor, Comprising: (a) is the front sectional drawing, (b) is sectional drawing by the BB line of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Stepping motor 2 ... Stator 2a ... Rotation restraint part 3 ... Shaft 5 ... Valve body (controlled body)
5a …… Rotation restricted part 5b …… Skirt part 9 …… Abrasion reduction / axial locking member 9a …… Cylindrical part 9b …… Flange part

Claims (2)

Having a stator,
A rotor is rotatably inserted into the stator,
The shaft is screwed to the rotor so as to be able to advance and retract in the axial direction,
A controlled body is attached to the tip of the shaft,
In the stepping motor in which the rotation restraint portion having a non-circular cross-sectional shape is formed in the controlled body and the rotation restraint portion is formed in the stator so as to be fitted to the rotation restraint portion,
A cylindrical wear reduction / axial locking member with a flange is attached to the rotation restraining portion of the stator, and the rotational restraint portion of the controlled body is against the cylindrical portion of the wear reduction / axial locking member. The stepping motor is characterized in that the controlled body comes into contact with the flange portion of the wear reduction / axial locking member to stop the backward movement of the shaft. The stepping motor according to claim 1, wherein a cylindrical skirt portion is formed on the controlled body so as to cover the wear reduction / axial locking member.

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