JPH08266035A - Direct acting stepping motor - Google Patents

Abstract

PURPOSE: To enable the scale-down of the outside diameter of an engaging shaft and downsize a bearing by forming a shaft hole for an output shaft, with its output side as an open end, at the center of a rotor, and dislocating the position of the bottom of the shaft hole at the other end and the position of the engaging part of a bearing arranged on that side so that they may not overlap each other in axial direction. CONSTITUTION: A shaft hole 23 is made, with its output end side open, at the center of the core 21 of a rotor 20, and the position of the bottom 25 of the shaft hole 23 is arranged to lie on the opening side more than the base of the the engaging shaft 24a where a ball bearing 26a is set, and the shaft hole 23 is not made within the section where the ball bearing 26a is set of the engaging shaft 24a. Hereby, it becomes possible to make the outside diameter of the engaging shaft 24a small, consequently, a small-sized ball bearing 26a can be used. Furthermore, by making it have stopper function by abutting the end face 31a of the output shaft 30 against the bottom of the shaft hole 23, the outside diameter of the engaging shaft 24b can be made small, too, and the ball bearing 26b can be downsized, too.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitrogen oxide contained in the exhaust gas of an engine, for driving a control valve for adjusting the amount of air for controlling the idling speed of an automobile engine, for example. Direct-acting stepping motor used in the recirculation passage from the exhaust passage to the intake passage in the exhaust gas re-combustion system for driving the control valve that controls the flow rate of the exhaust gas flowing in the recirculation passage. Regarding

[0002]

2. Description of the Related Art The structure of a conventional direct-acting stepping motor used for the above-mentioned applications will be described with reference to FIG. As shown in the figure, a direct-acting stepping motor (hereinafter simply referred to as a motor) 100 is a main case 10 made of a constituent resin and housing a stator 110 by integral molding.
2 and a sub-case 103 to which a sliding bearing 104 is attached, a main body case 101, a rotor 120 rotatably provided inside the stator 110, and a rotor 120.
Output shaft 1 slidably in the axial direction with the rotation of
It is composed of thirty.

The stator 110 has a pair of yokes 111 and 112, and field coils 113a and 1a wound around winding frames 113 and 114 housed in the respective yokes.
14a, and this field coil 113a, 1
Although not shown, 14a is connected to a connection terminal, and a control signal, that is, a control current is supplied through this connection terminal. The yokes 111 and 112 are fixed to each other by welding. In addition, the pair of yokes 111
And 112 are attached to the mounting member 115 by welding or the like.
And 116 are fixedly attached, and the mounting members 115 and 1
Each of 16 is provided with a press-fitting portion 115a and 116a into which a ball bearing described later is press-fitted. And the winding frame 11 around which the field coils 113a and 114a are wound.
The pair of yokes 111 and 112, which house 3 and 114 and are fixed to each other, and the mounting members 115 and 116, which are integrally fixed to the yokes 111 and 112, are integrally molded in the main case 102 made of synthetic resin, 10
A pair of yokes 111 and 112 and a mounting member 11 are provided in
It stores 5,116.

Next, the rotor 120 comprises a core 121 made of synthetic resin and the core 1 on the outer periphery of the core 121.
21 and a cylindrical permanent magnet 122 attached by integral molding. And this core body 121
A through hole 123 having an internal thread 123a formed on the inner peripheral surface thereof is provided at the center of the output shaft 130. The inner diameter of each core 121 is set to be larger than the outer diameter of the through hole 123. Fitting shafts 124a and 124b formed by annular walls are formed so as to form a space in which the can be moved. The edge of the through hole 123 located inside the fitting shaft 124b serves as a stopper 125. Then, the inner rings of the ball bearings 126a and 126b are press-fitted and attached to the fitting shafts 124a and 120b, respectively, and the outer rings of the ball bearings 126a and 126b attached to the fitting shafts 124a and 124b are attached to the fitting members 115 and 116, respectively. Each press fitting part 1
By press fitting into 15a and 116a, the rotor 1
20 is rotatably mounted in the main case 102.

Next, the sub-case 103 has a cylindrical bearing fitting portion 105 having a bearing fitting hole 105a in the central portion and an annular flange portion 106 in the outer peripheral portion. A sliding bearing 104 having a D-shaped shaft hole 104a formed in the center is fixed to the bearing fitting portion 105a. The outer peripheral portion of the bearing fitting portion 105 is a spring mounting portion. The sub-case 103 is attached by fixing the annular flange portion 106 to the main case 102 by adhesion or the like. Further, the shaft center of the shaft hole 104a coincides with the shaft center of the through hole 123 formed in the core body 121 of the rotor 120.

Next, the output shaft 130 has a female screw 123a provided on the core body 121 of the rotor 120 at one end thereof.
A male screw 131 that is screwed in is formed, and the other end side is formed in a D-shaped section having the same shape as the shaft hole 104a of the sliding bearing 104 and can slide in the shaft hole 104a. The shaft portion 133 is formed. Also, the sliding shaft portion 1
A mounting screw 134 is formed at the tip of 33.
Further, the output shaft 130 is provided with an insertion hole 135 provided in a direction orthogonal to the shaft center, and the insertion hole 135 is brought into contact with the stopper 125 of the core body 121 of the rotor 120 so as to contact the output shaft 130. A blocking pin 136 that blocks movement is press-fitted and attached.

A valve head, that is, a valve body 140 is attached to the mounting screw 134, and the valve body 140 adjusts the opening amount of a flow passage port for exhaust gas or the like (not shown). A coil spring 141 is fitted between the valve body 140 and the sub case 103 so that one end side is fitted to the outer periphery of the bearing fitting portion 105 and constantly biases the valve body 140 in a direction away from the sub case 103. It is provided.

Then, the field coils 113a, 114
When a control current is supplied to a, the rotor 120 rotates while changing its rotation direction according to the change of the supply current, that is, the direction of generation of the rotating field. With the rotation of the rotor 120, the output shaft 130 slides in the shaft hole 104a of the bearing 104 in the valve closing direction, that is, the arrow A direction and the valve opening direction, that is, the arrow B direction, and the exhaust gas (not shown) or the like. The opening amount of the flow path port is adjusted, that is, controlled.

[0009]

By the way, in the above-mentioned conventional motor 100, the core 121 of the rotor 120 is used.
The fitting shafts 124a and 124b formed at both ends of the shaft must be formed as annular walls so that the output shaft 130 can move and the blocking pin 136 needs an annular space. As a result, inevitably the mating shaft 124
Since the outer diameters of a and 124b are large, it is necessary to use large ball bearings 126a and 126b attached to the fitting shafts 124a and 124b. Therefore, there is a problem that the outer diameter of the motor becomes large and the size cannot be reduced, and a large ball bearing must be used, resulting in an increase in cost.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and includes a stator mounted on a main body case and having a field coil attached thereto, and a central portion fixed with a permanent magnet on an outer peripheral portion thereof. Has a shaft hole with one end opened at the inner peripheral surface and a threaded portion formed on the inner peripheral surface, and is fitted to a fitting shaft formed at one side where the opening was formed and at the other side opposite to this one side. A rotor that is rotatably provided with a predetermined gap with the inner peripheral surface of the stator through a bearing, and has a non-circular shaft hole, and the shaft center of this shaft hole corresponds to the shaft hole of the rotor. A sliding bearing mounted on the main body case so as to match the shaft center, and a screw shaft portion screwed with a screw portion provided on the rotor at one end side, and the cross-sectional shape at the other end side is the sliding bearing. And an output shaft provided with a sliding shaft portion that slides in this shaft hole. In the direct acting stepping motor, the shaft hole is formed in the rotor at a position where it does not overlap with a portion of the fitting shaft formed on the other side where the bearing of the fitting shaft fits along the axial direction.

[0011]

According to the present invention, as described above, the position of the shaft hole formed in the rotor does not overlap with the position of the bearing of the fitting shaft formed on the other side of the rotor in the axial direction. Since the structure is formed on the rotor as described above, the outer diameter of the fitting shaft can be formed small, so that the bearing mounted on the fitting shaft can be downsized.

[0012]

Embodiments of the present invention will now be described with reference to FIGS.
It will be described based on.

As shown in FIG. 1, a direct-acting stepping motor (hereinafter simply referred to as a motor) 1 comprises a main case 2 made of a synthetic resin such as polybutylene terephthalate and polyethylene terephthalate, and a sub case 3 made of a metal such as an iron plate. A main body case 4 configured, a stator 10 housed and mounted in the main case 2 by integral molding, and a rotor 2 rotatably provided inside the stator 10.
0, the output shaft 30 is provided so as to be slidable in the axial direction while being prevented from rotating in accordance with the rotating operation of the rotor 20.

The stator 10 includes a pair of yokes 11 and 12 and reels 13 and 1 housed in the respective yokes.
4 and field coils 13a and 14a wound around it.
a and 17b are connected to each other, and these connection terminals 17a and 17b are connected.
A control signal, that is, a control current is supplied via the. As shown in FIG. 3, the yokes 11 and 12 are integrally fixed at their outer peripheral portions by welding S.
Further, mounting members 15 and 16 are fixed to the pair of yokes 11 and 12 by spot welding (not shown) at their joint surfaces.
Each of them is provided with a press-fitting portion 15a and 16a into which a ball bearing described later is press-fitted.

The pair of yokes 11 and 12 and the mounting members 15 and 16 fixed to the yokes 11 and 12 are fixed so that the winding frames 13 and 14 around which the field coils 13a and 14a are wound are accommodated. The main case 2 made of synthetic resin is integrally molded, and the pair of yokes 11 and 12 and the attachment members 15 and 16 are housed and attached in the main case 2.

A more specific structure and assembly of the stator 10 will be described with reference to FIGS. 2 and 3. First,
The structure of the pair of yokes 11 and 12 will be described. The yoke 11 is an annular yoke 1 as shown in FIG.
1d and a plate-shaped yoke 11f, the annular yoke 1
1d is an annular wall 11a formed by drawing a magnetic material such as an iron plate and a plurality of magnetic poles 11b formed by bending the annular wall 11a so as to be parallel to the annular wall 11a at predetermined intervals. And the annular wall 11a and the magnetic pole 11b.
An annular groove 11c having an opening on one side, that is, on the upper side in the drawing is formed by and. Further, the plate-shaped yoke 11f is
The magnetic pole 1 is formed by bending a magnetic material such as an iron plate to close the opening of the annular groove 11c and an inner portion of the flange 11f, which are bent at a predetermined distance from each other.
1b and a magnetic pole 11e combined with each other. The mounting member 15 is fixed to the lower surface of the annular yoke 11d by spot welding. Also,
The field coil 13a is formed by winding a predetermined number of coil windings around the winding frame 13, connecting the ends of the coil windings to the connection terminals 17a, and then covering with synthetic resin 13b. This yoke 11 is assembled by the annular groove 1 of the annular yoke 11d.
The field coil 13a coated with the synthetic resin is housed in 1c, and then the plate-shaped yoke 11f is attached so as to close the opening, and then the opening edge is protruded inward and fixed by caulking. Since the yoke 12 also has the same structure as the yoke 11, only the parts corresponding to the structure of the yoke 11 are designated by the corresponding reference numerals, and the description thereof will be omitted.

Then, the respective yokes 11 and 12
As shown in FIG. 3, the plate-shaped yokes 11f and 12f are joined together and joined, and the outer peripheral portions of the opening edges of the annular grooves 11c and 12c of both annular yokes 11 and 12 are fixed by welding S as described above. Are integrated and fixed, and 10 is assembled. And the stator 1 assembled in this way
0 around the main case 2 as shown by the chain double-dashed line in FIG.
Is formed integrally with a synthetic resin so as to form a coating. Further, the main case 2 is integrally formed with a connector portion 18, and the connection terminals 17a and 17b are arranged in the connector portion 18. 1, a plurality of mounting bosses 2b having mounting holes 2a (only one is shown in FIG. 1) are provided on the left side edge of the main case 2, and an annular recess 2d is provided on the left side wall 2c. Are formed.

Next, the rotor 20 comprises a core body 21 made of synthetic resin and a cylindrical permanent magnet 22 attached to the outer periphery of the core body 21 by integral molding with the core body 21. . Then, one end side is opened in the central portion of the core body 21, and a female screw 23a as a screw portion is formed on the inner peripheral surface.
Is formed, and the other end of the shaft hole 23, that is, the bottom surface 25 of the bottom of the shaft hole 23 is an abutting portion. On the one side of the core body 21, that is, on the opening side of the shaft hole 23, the diameter is larger than that of the shaft hole 23, that is, the output shaft 30.
A fitting shaft 24b formed of an annular wall is formed so as to form an axially movable gap. A fitting shaft 24a is integrally formed so as to project outward on the other side facing the one side, that is, on the bottom side of the shaft hole 23. The position of the bottom surface 25 of the shaft hole 23 is such that the shaft hole 23 does not overlap with a portion of the fitting shaft 24a where a ball bearing 26a, which will be described later, is fitted, along the axial direction. The body 21 is formed on the rotor 20. That is, as shown in FIG. 1, the bottom surface 25 of the shaft hole 23 is formed so as to be positioned closer to the opening side than the base portion of the fitting shaft 24a, and the inside of the fitting shaft 24a where the ball bearing 26a fits. The shaft hole 23 is not formed. As a result, the outer diameter of the fitting shaft 24a can be made small, and the ball bearing 26a attached to the fitting shaft 24a can also be made small.

Then, the fitting shaft 24 of the rotor 20
The inner rings of ball bearings 26a and 26b as bearings are press-fitted and attached to a and 24b, respectively, and the outer rings of the ball bearings 26a and 26b attached to the press-fit shafts 24a and 24b are attached to the press-fitting portions 15a and 16 of the mounting member 15, respectively. The rotor 20 is rotatably mounted in the main case 2 by being press-fitted into the press-fitting portions 16a.

Next, the sub case 3 is made of a metal such as an iron plate and is formed into a bottomed cylinder having an opening on one side and a bearing fitting portion 3a provided at the bottom, and the main case 2 is provided at the edge of the opening. An annular collar 3b is provided which fits in the annular recess 2d provided on the. A sliding bearing 5 having a D-shaped shaft hole 5a is attached to the bearing fitting portion 3a. When the sub case 3 is attached to the main case 2, the shaft center of the shaft hole 5a coincides with the shaft center of the screw hole 23 formed in the core body 21 of the rotor 20.

Next, the output shaft 30 is formed at one end with a male screw 31 as a screw shaft portion that is screwed into the female screw 23a provided on the core body 21 of the rotor 20, and at the other end side. Is formed in a D-shaped cross-section having the same shape as the D-shaped shaft hole 5a of the sliding bearing 5, and is formed with a sliding shaft portion 33 capable of sliding in the shaft hole 5a. The end surface 31a of the output shaft 30 having the male screw 31 formed therein is configured to abut the bottom surface 25 formed in the shaft hole 23, and the blocking pin conventionally used is eliminated. When the blocking pin is abolished in this way, the annular fitting shaft 24b formed on the opening side only needs to be provided with a gap inside which the output shaft 30 can move.
The outer diameter of the fitting shaft 24b can be made small, and as a result, a small pole bearing 26b can be used. Further, the mounting screw 3 is attached to the tip of the sliding shaft portion 33.
4 are formed.

Next, the assembly of the motor 1 will be described. First, the main case 2 in which the stator 10 is housed by integral molding, the rotor 20 in which the ball bearings 26a and 26b are press-fitted into the fitting shafts 24a and 24b,
The sub-case 3 to which the output shaft 30 and the sliding bearing 5 are attached is prepared. The ball bearings 26a and 26b attached to the rotor 20 are attached to the stator 10
The rotor 20 is positioned at a predetermined position with respect to the stator 10 and is rotatably attached to the stator 10 by being press-fitted into the press-fitting portions 15a and 16a of the attachment members 15 and 16 fixed to the. Next, the male screw 31 of the output shaft 30 is screwed and attached to the female screw 23 a of the rotor 20. Then, the sliding shaft portion 33 of the output shaft 30 is attached to the sliding bearing 5
The ring-shaped flange portion 3 of the sub-case 2 by being inserted into the shaft hole 5a of
The motor is assembled by fitting b into the annular recess 2d of the main case 2 and then fixing the sub case 3 to the main case 2 by ultrasonic welding or adhesive bonding.

The motor 1 is used in the same manner as the conventional one described above, for driving a control valve for adjusting the amount of air for controlling the idling speed of an engine of an automobile, and for the exhaust gas of the engine. When used for driving a control valve that controls the flow rate of exhaust gas flowing in the recirculation passage from the exhaust passage to the intake passage in an exhaust gas recombustion system for reducing contained nitrogen oxides Is a coil spring 41 for urging the valve element 40 to the mounting screw 34 at the tip of the output shaft 30 of the motor assembled in the above-described manner, in the direction in which the valve element 40 is always separated from the motor 1. Install by interposing. Then, the valve body 40 is set at a position corresponding to the opening amount of the flow passage port for combustion air or exhaust gas so that it can be adjusted, that is, controllable, and the mounting hole 2a of the mounting boss 2b is provided at a predetermined position of an engine (not shown). Attach to.

The field coil 13 of the stator 10
When a control current for controlling the opening amount is supplied to a and 14a such that the air flowing through the flow path port or the exhaust gas to be recirculated has a predetermined flow rate, how the supply current is supplied, that is, the direction of the field generation. The rotor 20 according to the change of
Rotates while changing its rotation direction. This rotor 20
With the rotation of the output shaft 30, the output shaft 30 slides in the shaft hole 5a of the sliding bearing 5 in the valve closing direction, that is, the arrow A direction and the valve opening direction, that is, the arrow B direction in FIG. The quantity is regulated or controlled.

In the above embodiment, the end surface 31a of the output shaft 30 is brought into contact with the bottom surface of the shaft hole 23, and this state is set to the reference position, that is, the home position. Although the block 33 has no blocking pin, it may have a block pin. Even in this case, at least the ball bearing 26a attached to the fitting shaft 24a provided on the bottom side can be downsized by not forming the shaft hole 23 in the fitting shaft 24a provided on the bottom side of the shaft hole 23. Is what comes. If a small diameter hole is formed in the axial center of the fitting shaft 24a in order to prevent so-called sink marks during molding, the accuracy of the fitting dimensions of the fitting shaft can be improved. Comes.

As described above, the end surface 31 of the output shaft 30 is
When a is brought into contact with the bottom surface of the shaft hole 23 and this state is set to the reference position, that is, the home position, and the blocking pin is abolished, precision machining is performed by press-fitting the blocking pin into the output shaft 30. It is possible to eliminate the required hole forming process for the insertion hole, reduce the number of parts, and eliminate the need for the press-in process of the blocking pin, thereby improving the productivity.

In the above embodiment, the case where the motor 1 is used in the control of the idling speed of the engine of the automobile and the exhaust gas re-combustion system has been described, but it goes without saying that the use of the motor is not limited to this. .

[0028]

As described above, according to the present invention, the shaft hole formed in the rotor does not overlap with the portion of the fitting shaft formed on the other side of the rotor where the bearing of the fitting shaft fits along the axial direction. Since the outer diameter of the fitting shaft can be made small, the bearing attached to this fitting shaft can be made small, and the motor can be made compact. At the same time, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a direct acting stepping motor according to an embodiment of the present invention.

FIG. 2 is an exploded view of the stator of the above embodiment.

FIG. 3 is an assembly view of the stator of the above embodiment.

FIG. 4 is a sectional view of a conventional direct acting stepping motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Direct acting stepping motor Stator 5 Sliding bearing 10 Stator 13a Field coil 14a Field coil 20 Rotor 22 Permanent magnet 23 Shaft hole 23a Female screw (screw part) 25 Bottom surface 24a Fitting shaft 24b Fitting shaft 30 Output shaft 31 Male Thread (Screw Shaft)

Claims (1)

[Claims] 1. A stator having a field coil attached to a main body case, and a shaft hole having a permanent magnet fixed to an outer peripheral portion, one end side opening at a central portion, and a screw portion formed on an inner peripheral surface. Rotating through a predetermined gap with the inner peripheral surface of the stator through bearings fitted to fitting shafts formed on one side where the opening is formed and on the other side facing the one side. A freely provided rotor, a non-circular shaft hole, a sliding bearing mounted on the main body case with the shaft center of the shaft hole aligned with the shaft center of the shaft hole of the rotor, and one end On one side, a screw shaft portion to be screwed with the screw portion provided on the rotor is provided, and on the other end side, the cross-sectional shape is substantially the same as the shaft hole shape of the sliding bearing, and a sliding shaft sliding on this shaft hole. In a direct acting stepping motor having an output shaft provided with a section, the shaft hole is formed on the other side. A direct-acting stepping motor, characterized in that it is formed on the rotor at a position where the bearing of the fitting shaft does not overlap with the fitting part along the axial direction.