JPH0898497A - Step motor - Google Patents

Abstract

PURPOSE: To obtain a step motor having a stator produced through integral resin molding of a pair of stator yokes equipped with pole teeth in which fluctuation in the interval of pole tooth due to resin molding is suppressed. CONSTITUTION: First stator yokes 16, 22 having a plurality of tubular pole teeth are resin molded integrally with second stator yokes 18, 24 having a plurality of tubular pole teeth disposed oppositely to the pole teeth of the first stator yokes through a predetermined interval. A reinforcing plate 26 for preventing the molding pressure from acting on the periphery of the pole tooth is disposed below the second yoke 24. Ring members 19, 25 for regulating fluctuation in the interval of pole tooth are disposed in the first and second stator yokes 16, 18, 22, 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor, and more particularly to a stepping motor which constitutes a stator by integrally molding a pair of stator yokes each having a pole tooth with resin.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Laid-Open No. 60-1811
As disclosed in Japanese Patent Publication No. 77, a stepping motor is known in which a first stator yoke and a second stator yoke each having a plurality of pole teeth are arranged to face each other, and they are integrally resin-molded to form a stator. ing.

Here, the stator provided in the stepping motor described in the above publication has a plurality of pole teeth oppositely arranged at a predetermined interval on the inner peripheral surface thereof, and houses an electromagnetic coil therein. Therefore, when an appropriate current is passed through the electromagnetic coil and an axial magnetic field is generated in the center of the stator, the magnetic flux is exchanged between the pole teeth of the first stator yoke and the pole teeth of the second stator yoke. Then, one of the pole teeth is excited to the N pole and the other is excited to the S pole.

By the way, the electromagnetic coil incorporated in the above-mentioned stator is provided with two-phase coils independent of each other. Therefore, if the directions of the currents flowing through them are set to be opposite to each other, the direction of the magnetic field generated in the center of the electromagnetic coil will be inverted depending on which coil the current is to flow through.

Therefore, if the coils for passing the current are switched alternately, the magnetized states of the pole teeth of the first stator yoke and the pole teeth of the second stator yoke can be switched alternately. For example, when two such stators are used in combination, a rotating magnetic field can be easily generated on the inner peripheral surface of the stator.

In the stepping motor described in the above publication, the N pole and the S pole are alternately arranged on the inner peripheral side of the stator at every predetermined rotation angle.
It is supposed to arrange a rotor provided with a permanent magnet where the poles appear. In this case, if a rotating magnetic field is generated on the inner peripheral surface of the stator, the rotor rotates by the rotation angle of the rotating magnetic field, and the function as the stepping motor is appropriately realized.

By the way, the stator of the stepping motor described in the above publication is constructed by integrally molding the electromagnetic coil, the first and second stator yokes, and the like, as described above, with the first and second stator yokes. Stabilization of the relative positional relationship of the stator yoke, protection of the electromagnetic coil, and the like are appropriately realized, and excellent productivity and high reliability are obtained.

[0008]

However, the stator of the conventional stepping motor described above has an appropriate gap between the pole teeth of the first and second stator yokes in order to operate the stepping motor as described above. Since it is provided, the rigidity against the external force in the axial direction of the stator, especially the first
Also, the rigidity of the pole tooth portion of the second stator yoke is low, and it is easily deformed.

In this case, if the molding pressure generated during resin molding acts directly on the first and second stator yokes,
Due to the molding pressure, the first and second stator yokes are deformed in the direction in which the gap between the pole teeth of the first and second stator yokes is narrowed. Then, as a result of the deformation, an imbalance in the pole tooth spacing occurs for a plurality of pole tooth pairs, and if the pole teeth come into contact with each other, an imbalance also occurs in the excitation strength of each pole tooth, and stepping is performed. It becomes difficult to realize an appropriate function as a motor.

The present invention has been made in view of the above points, and when performing resin molding to form a stator, by restricting the action of molding pressure near the pole teeth of the stator yoke, or An object of the present invention is to provide a stepping motor that solves the above problems by restricting the displacement of the stator yoke near the pole teeth during resin molding.

[0011]

The above object is to provide a first stator yoke having a plurality of pole teeth in a cylindrical shape, and a pole tooth provided to the first stator yoke, as set forth in claim 1. In a stepping motor including a stator integrally molded with a second stator yoke having a plurality of cylindrically arranged pole teeth that are arranged to face each other with respect to the stator, At least one of the end portion of the first stator yoke and the end portion of the second stator yoke is arranged at a predetermined distance from the end portion of the first stator yoke or the end portion of the second stator yoke. This is achieved by a stepping motor provided with a molding pressure regulating member provided.

[0012] Further, as described in claim 2, the above-mentioned object is predetermined for the first stator yoke having a plurality of pole teeth in a cylindrical shape and the pole teeth provided for the first stator yoke. In a stepping motor including a stator integrally molded with a second stator yoke, which has a plurality of cylindrically arranged pole teeth and are spaced apart from each other, the stator is the first stator. By a stepping motor that is in contact with the yoke and the second stator yoke, and that includes a displacement restricting member that restricts relative displacement between the pole teeth of the first stator yoke and the pole teeth of the second stator yoke. Is also achieved.

[0013]

In the invention according to claim 1, the first stator yoke and the second stator yoke are integrally resin-molded to excite the stator inner peripheral surface of the stepping motor with different polarities. To form possible polar teeth.

Further, when the molding pressure of the resin mold acts on the first stator yoke and the second stator yoke, the molding pressure regulating member directly applies the molding pressure to the first stator yoke and the second stator yoke. It is prevented from acting on the end portion or the end portion of the second stator yoke.

As a result, according to the present invention, at least one of the first stator yoke and the second stator yoke is arranged so as to narrow the gap between the pole teeth oppositely arranged at a predetermined gap. The molding pressure does not act directly, and the change in pole tooth spacing is suppressed.

Further, in the invention described in claim 2, the first stator yoke and the second stator yoke are magnetized to different polarities on the inner peripheral surface of the stator as in the invention described in claim 1. To form possible polar teeth.

By the way, in the present invention, the first stator yoke and the second stator yoke are in contact with a displacement regulating member which regulates relative displacement of the pole teeth of the both. In this case, high rigidity is ensured in the direction in which the pole tooth gap is narrowed, and during resin molding, the molding pressure acts on the first stator yoke and the second stator yoke in the direction that narrows the pole tooth gap. Even if it does, a large displacement of the pole tooth interval will be prevented.

[0018]

1 is a front sectional view showing the structure of a stepping motor 10 according to an embodiment of the present invention. The stepping motor 1 according to the present embodiment
0 is provided to switch the damping force of the shock absorber in the vehicle.

In the figure, the housing 12 is a member for accommodating various components and being fixed by bolts to the vehicle body, and has a bolt hole 12b provided with a metal collar 12a at its end.

Inside the housing 12, the electromagnetic coil 1
4, 20 and the first and second stator yokes 16, 1 that are arranged to face each other around the electromagnetic coils 14 and face each other.
8, 22, 24 and the first and second stator yokes 1
Ring members 19 and 25 for controlling the relative axial positions of 6, 18, 22, and 24 are housed.

A reinforcing plate 26 is arranged between the axial end portion of the second stator yoke 24 and the housing 12. The reinforcing plate 26 is in contact with the second stator yoke 24 only in the vicinity of the outer peripheral end thereof, and in other portions, a predetermined space is provided between the reinforcing plate 26 and the second stator yoke 24. ing.

Here, in this embodiment, the housing 12 is provided by injection molding a resin, and at that time, the metal collar 12a, the electromagnetic coils 14, 20, the first stator yoke 16, 22, the second stator yokes 18 and 24, and the reinforcing plate 26 are integrally resin-molded. In this case, the stator 28 of the stepping motor 10 is composed of the housing 12 and the respective members integrally resin-molded therein.

By the way, FIG. 2 is a perspective sectional view showing the construction of the first and second stator yokes 16 and 18, and the electromagnetic coil 14 and the ring member 19 housed therein.

As shown in FIG. 2, the first stator yoke 1
6 and the second stator yoke 18 have a plurality of pole teeth 16-i (16 _{-1 to} 16-n) and 18-i (18 _-1 to 18), respectively.
-n) cantilevered. That is, these pole teeth 16-i and 18-i are respectively connected to the second stator yoke 1
8 or the first stator yoke 16 is disposed so as to face each other, and a predetermined gap is provided between the pole teeth 16-i and 18-i.

A ring member 19 is housed between the first stator yoke 16 and the second stator yoke 18.
Are in contact with the first stator yoke 16 and the second stator yoke 18 so that a predetermined gap is secured between the pole teeth 16-i and 18-i. Therefore, in the stator 28 configured as described above, when a current flows through the electromagnetic coil 14 and an axial magnetic flux is generated on the inner peripheral side of the electromagnetic coil 14,
The magnetic flux is exchanged between the first and second stator yokes 16 and 18 via the pole teeth 16-i and 18-i.
One of 18-i is excited to the N pole and the other is excited to the S pole.

The electromagnetic coil 14 has two phases of coils capable of generating the same magnetic force. Therefore, if it is assumed that current flows in the opposite direction to those coils, the pole tooth 1 depends on which coil the current flows.
The polarity of 6-i and 18-i can be reversed.

The first member disposed in the housing 12
The stator yoke 22, the second stator yoke 24, and the electromagnetic coil 20 are also provided with substantially the same configuration as the above-described first stator yoke 16, second stator yoke 18, and electromagnetic coil 14.

Further, the first and second stator yokes 1
6, 18 and the first and second stator yokes 22, 24
Are arranged so that the pole teeth of them are located in phase with each other by half a tooth. Therefore, in the stator 28, it is possible to generate a rotating magnetic field on the inner circumference of the stator 28 by appropriately controlling the energization state of the electromagnetic coils 14 and 20.

By the way, a cylindrical rotor 30 is inserted on the inner peripheral side of the stator 28 while ensuring a predetermined clearance. Here, the rotor 30 includes the housing 12
Both ends thereof are supported by a rotary bearing 34 arranged on the cap 32 fitted to the upper part of the stator and a rotary bearing 36 arranged on the inner periphery of the reinforcing plate 26 described above.
8 can be freely rotated.

Further, a permanent magnet 30a in which S poles and N poles are alternately magnetized at predetermined angles is incorporated on the outer peripheral side of the rotor 30. Therefore, when a rotating magnetic field is generated on the inner circumference of the stator 28, the rotor 30 is rotated by the rotation angle of the rotating magnetic field.
Will rotate.

By the way, the stepping motor 10 of this embodiment is provided so as to generate the rotational torque necessary for switching the damping force of the shock absorber as described above. Here, switching of the damping force of the shock absorber is performed by rotating a rotary valve incorporated in the shock absorber.

At this time, the switching of the damping force can be realized by giving an appropriate rotation angle to the rotary valve, and is not necessarily 3
An effective rotation angle of 60 ° is not required. Therefore, in the stepping motor 10, the stopper pin 38 is arranged near the upper end of the rotor 30 and the cap 32 is
An elastic member 40 that allows displacement of the stopper pin 38 only within a predetermined range is provided to regulate the rotation angle of the rotor 30 within an appropriate range.

In this case, for example, the rotor 30 is the stator 2
Even when the stepping out of the rotating magnetic field of No. 8 occurs, the rotation angle of the rotor 28 is restricted to the limit angle thereafter, and the proper operating state is easily restored.

An output shaft 42 is loosely fitted on the inner peripheral side of the rotor 30 to transmit the rotation of the rotor 30 to a rotary valve built in the shock absorber. Here, the output shaft 42 is a member that is fitted to the control rod 44 that is connected to the rotary valve when it is assembled to the vehicle body, and is the spring pin 4.
6, the connection with the rotor 30 is achieved.

The output shaft 42 is connected to the rotor 30 by the spring pin 46.
Spring pin 46 for output shaft 42
Of the output shaft 4 by allowing axial displacement of the output shaft 4 and rotational displacement about the spring pin 46 as a central axis.
This is to facilitate the assembling of the control rod 2 and the control rod 46.

An O-ring 48 is arranged on the outer circumference of the output shaft 46. As a result, a force for always correcting the position of the output shaft 46 to the center of the rotor 30 always acts, and while the appropriate displacement as described above is allowed, the output shaft 46 is not affected by any external force. The position of the shaft 42 is optimized.

By the way, in the stepping motor 10, the rotor 30 is supported by the rotary bearings 34 and 36 as described above. At this time, in order to obtain the centrality of the rotor 30, it is effective to apply a preload between the inner races 34a, 36a and the outer races 34b, 36b of the rotary bearings 34, 36 to absorb the play between them. Is.

Here, regarding the rotary bearing 36, the outer race 36b is held by the reinforcing plate 26, and the inner race 36b is fitted on the rotor 30. On the other hand, regarding the rotary bearing 34, the outer race 34b is held by the rotor 30, and the inner race 34a is held by the cap 32.
Is fitted to.

Therefore, by applying a downward preload to the inner race 34a of the rotary bearing 34 in FIG. 1, the play of the rotary bearing 34 is absorbed and the outer race 3
If a downward preload in FIG. 1 is applied to the rotor 30 via 4b, the play of the rotary bearing 36 can also be absorbed.

Therefore, in this embodiment, as shown in the enlarged view of FIG. 3, the inner race 34a of the rotary bearing 34 is shown.
A preload plate 50 including a ring portion 50a that abuts against the spring portion 50a and a spring portion 50b that applies a biasing force to the ring portion 50a by being elastically deformed is disposed above the rotary bearing 34.

As a result, in the stepping motor 10, a desired preload is secured with an extremely simple structure without causing a significant increase in cost or a decrease in assembling property.

Further, in order to prevent foreign matter from entering the inside of the stepping motor 10, it is necessary to fit the cap 32 to the housing 12 while ensuring the sealing property. On the other hand, if a sealing material such as an O-ring is used, the number of parts will increase and the cost will increase.

Therefore, in this embodiment, the cap 32 is fitted into the housing 12, and then the outer periphery of the housing 12 is caulked under heating, so that both are fixed and the sealing property is secured. I am trying. At this time, in order to ensure the sealing property, the portion where the cap 32 contacts the housing 12 is left with a sharp corner without chamfering, as shown in an enlarged view in FIG.

As a result, in the stepping motor 10, an excellent sealing property is secured between the cap 32 and the housing 12 without using any special sealing member.

By the way, in order to ensure the smooth operability of the stepping motor 10, the first stator yoke 1
6 and 22, the pole teeth and the second stator yoke 18,
It is extremely important to maintain the proper distance between the pole teeth of 24.

On the other hand, the first and second stator yokes 1
Since the pole teeth of 6, 18, 22, and 24 are cantilevered as described above, when the external force in the axial direction of the stator 28 acts, the periphery of the pole teeth is easily deformed. The intervals are likely to change.

On the other hand, in the stepping motor 10 of this embodiment, the reinforcing plate 26 is arranged below the second stator yoke 24 as described above, and the first stator yokes 16 and 22 and the second stator yokes 22 and 22 are arranged. By arranging the ring members 19 and 25 between the stator yokes 18 and 24, the change in the pole tooth spacing is suppressed.

That is, in FIG. 5, prior to molding the housing 12 by resin molding, a mold 6 for injection molding is used.
0, electromagnetic coils 14, 20, first and second stator yokes 16, 18, 22, 24, ring members 19, 2
5 and the situation in which the reinforcing plate 26 is set.

In this case, the molding pressure during resin molding is mainly the lower surface of the reinforcing plate 26 and the first stator yoke 16.
On the outer peripheral surface of the first stator yoke 1 and the outer peripheral surface of the second stator yoke 24.
6, 18, 22, 24 pole teeth 16-i, 18-i, 22-i,
It does not act directly around 24-i.

Further, as described above, the reinforcing plate 26 is in the vicinity of the outer peripheral end of the second stator yoke 24 (on the end side where the pole teeth are not present, and is relatively rigid as compared with the end portion where the pole teeth are present. The contact is made only at a high position), and an appropriate space is secured to the second stator yoke 24 at other portions. Therefore, due to the action of the molding pressure, the reinforcing plate 2
Even if 6 is deformed, pole teeth 16-i, 18-i, 22-i, 2
The molding pressure does not act around 4-i.

Further, due to the influence of the molding pressure acting near the outer peripheral end of the second stator yoke 24 and the influence of the molding pressure acting on the outer peripheral surfaces of the first stator yoke 16 and the second stator yoke 24, Teeth 16-i, 18-i, 22-i,
When an external force in the direction of narrowing the 24-i interval acts, the ring members 19 and 25 appropriately suppress the displacement associated with the external force.

As described above, according to the configuration of the stepping motor 10 of this embodiment, the pole teeth 16-i, 18-i, 22-i, 24-i can be appropriately applied to the molding pressure generated during resin molding.
The peripheral deformation can be suppressed, and the stator 30 can surely secure an appropriate pole tooth interval.

Therefore, in the stepping motor 10, uniform excitation strength can be obtained over the entire circumference of the stator 30, and smooth rotation operation can be obtained.

By the way, although the above-mentioned embodiment exemplifies the constitution in which the reinforcing plate 26 and the ring members 19 and 25 are used in combination, it is not always necessary to use them in combination, and only one of them is adopted. It is also possible to enjoy excellent effects.

Further, in the above embodiment, a part of the reinforcing plate 26 is brought into contact with the second stator yoke 24. However, the structure is such that the reinforcing plate 26 and the second stator yoke 2 are arranged.
This is to prevent the resin from flowing into between 4 and
If measures to prevent such inflow are taken,
The reinforcing plate 26 may be disposed completely apart from the second stator yoke 24.

In the above embodiment, the reinforcing plate 26 corresponds to the molding pressure regulating member described above, and the ring member 1
Reference numerals 9 and 25 correspond to the displacement regulating member described above.

[0057]

As described above, according to the first aspect of the invention, by providing the molding pressure regulating member, the poles of the first stator yoke and the second stator yoke are formed during resin molding. It is possible to suppress the molding pressure that acts to reduce the tooth gap. Therefore, the first
Further, it is possible to properly suppress the deformation of the second stator yoke around the pole teeth, and it is possible to properly secure a desired pole tooth interval after the resin molding.

Therefore, according to the present invention, since the pole tooth intervals are uniform over the entire inner surface of the stator, it is possible to easily and surely realize a stepping motor that generates a uniform rotating torque over the entire circumference. it can.

Further, according to the second aspect of the present invention, at the time of resin molding, high rigidity is obtained with respect to the molding pressure for displacing the first stator yoke and the second stator yoke in the direction of narrowing the pole tooth gap. be able to.

Therefore, according to the present invention, even if the molding pressure of the resin mold acts on the first and second stator yokes,
It is possible to appropriately maintain the pole tooth spacing, and it is possible to easily and surely realize a stepping motor that generates a uniform rotational torque over the entire circumference, as in the case of the above-described invention.

[Brief description of drawings]

FIG. 1 is a front sectional view of a stepping motor which is an embodiment of the invention described in claims 1 and 2. FIG.

FIG. 2 is a perspective sectional view around a stator yoke of the stepping motor according to the present embodiment.

FIG. 3 is an exploded enlarged view around a rotary bearing of the stepping motor according to the present embodiment.

FIG. 4 is an enlarged view of a caulking structure of a cap and a housing of the stepping motor according to the present embodiment.

FIG. 5 is a front cross-sectional view showing a state where the stator component parts of the stepping motor according to the present embodiment are set in a resin mold.

[Explanation of symbols]

 10 Stepping Motor 12 Housing 14, 20 Electromagnetic Coil 16, 22 First Stator Yoke 18, 24 Second Stator Yoke 19, 25 Ring Member 26 Reinforcing Plate 28 Stator 30 Rotor

Claims (2)

[Claims] 1. A first stator yoke having a plurality of pole teeth in a cylindrical shape, and a plurality of pole teeth arranged to face the pole teeth of the first stator yoke at a predetermined interval. In a stepping motor including a stator integrally molded with a second stator yoke, which is shaped like a ring, the stator includes an end portion of the first stator yoke and an end portion of the second stator yoke. At least one of the stepping motors is provided with a molding pressure regulating member disposed at a predetermined distance from the end of the first stator yoke or the end of the second stator yoke. 2. A first stator yoke having a plurality of pole teeth in a cylindrical shape, and a plurality of pole teeth arranged to face the pole teeth of the first stator yoke at a predetermined interval. In a stepping motor including a stator integrally molded with a second stator yoke provided in the shape of a ring, the stator includes the first stator yoke and the second stator yoke.
A stepping motor, which is in contact with the stator yoke and is provided with a displacement restricting member that restricts relative displacement between the pole teeth of the first stator yoke and the pole teeth of the second stator yoke.