JPS61254060A - Stroke type stepping motor - Google Patents

Abstract

PURPOSE:To shorten the axial length of the rotational shaft of a rotor by disposing rotation preventing means of a lead screw and external force bearing means coupled with one end of the screw in a recess formed on the rotor in the axial direction. CONSTITUTION:A rotor 3 is rotatably supported in stators 2-a-1-d. The rotor 3 is secured to an end bracket 4 without fluctuation, and supported to a slide bearing 6 press-fitted to a slide bearing housing 5-1 of a casing 5. The rotor 3 is formed in a recess shape, and a lead screw 7 and an external force bearing member 8 are disposed in the rotor 3. The screw 7 and the member 8 are integrally coupled, and the member 8 is unrotatably and axially slidably supported. When the rotor 3 rotates by a revolving magnetic field by the stators 1, the screw 7 and the member 8 axially slide.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a so-called stroke (stroke) that converts the rotational motion of a rotor into linear motion via a lead screw.
(linear displacement) type step motor.

[Background of the invention]

Step motors are often used as actuators for positioning control because they have advantages such as being able to be digitally controlled directly, not overrunning when stopped, and not accumulating position chain lengths. In addition, in general, it is more convenient to control positioning using a control actuator by linear displacement rather than by rotation angle UK, and stroke type step motors have recently been used in office automation equipment, automobile electrical equipment, etc. is beginning to be used.

In such a stroke type step motor, deceleration is also performed when converting rotational motion to linear motion, so even an inexpensive PM type step motor (rotor is composed of a magnet) with a relatively large step angle has a minimum step angle. Because the resolution is improved, it is mainly used in positioning mechanisms using PM type step motors.

For example, Japanese Patent Laid-Open No. 57-51934 discloses a system that uses a step motor to precisely control the air flow rate and control the idle-link rotational speed of an internal combustion engine.

This conventional stroke type step motor has an internal thread formed inside the rotor, and a lead screw (in this case, the valve shaft and It is said that KJI non-stick bearing (
By providing K, the lead screw is supported non-rotatably but slidably in the axial direction, and when the rotor rotates, the lead screw is linearly displaced. Due to these functions and structures, in the stroke type step motor according to the prior art described above, the length of the rotor in the direction of the rotational axis is long, and therefore, the appearance cannot help but be relatively large. Particularly, when placing this motor in a car where many control parts are arranged, it may cause inconvenience and trouble. It was requested.

[Purpose of the invention]

In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a stroke type step motor having a more compact structure, specifically, a structure in which the length of the rotor in the direction of the rotational axis is as short as possible. There is K to offer.

[Summary of the invention]

The object of the present invention is to provide a stator that generates a multi-rotation magnetic field in response to a supplied current, and a rotor that has a plurality of magnetized multi-pole magnets disposed on its outer circumferential surface and is rotatably supported within the stator. , has a threaded engagement mechanism that engages with a threaded portion provided on the rotational shaft of the rotor, and is non-rotatably supported so as to be slidable in the direction of the rotational shaft, and linearly moves in the axial direction with the rotational movement of the rotor. In a stroke type step motor, the step motor is equipped with a lead screw part that performs rotation of the rotor, and an external force receiving means that is connected to the lead screw part and transmits linear motion to a controlled part to be controlled in a linear manner. A recess is provided in the axial direction, and a means for preventing rotation of the lead screw part and an external force receiving means coupled to one end of the lead screw part are arranged inside the recess. ″′″／／402′″7
7'-E-/Kl)J.

will be accomplished.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a stroke type step motor that is an embodiment of the present invention. In the figure, coils 2-a and 2-b are housed in four stators 1-a, 1-b, 1-c and 1-d, respectively. 1-c and ld form a magnetic circuit to generate a rotating magnetic field.

The rotor 3 facing the inner peripheral surface of each stator is composed of a magnet 3-1 whose outer periphery is magnetized with multiple poles, a synthetic resin part 3-2 in which the magnet is insert-molded, and a ball bearing 3-3. A hole is provided in the portion 3-2 in the direction of the rotation axis of the rotor, and an internal thread portion 3-4 (trapezoidal thread) is formed on the surface of the hole.

The rotor constructed as described above is rotatably supported at both ends within the stator. That is, at one end, the inner ring of the ball bearing 3-3 is press-fitted to the abutment part 3-5 of the synthetic resin part and fixed to the heat-sealed part 3-6, and the outer ring is attached to the ball bearing housing part 4 of the end bracket 4. -1, it is fixed by caulking the housing end 4-2.

Therefore, the rotor 3 is fixed to the end bracket 4 without any play, and the other end is supported by a sliding bearing 6 press-fitted into a bearing housing portion 5-1 of the casing 5. Furthermore, an external force receiving member 8 is fixed to the tip end 7-2 of the lead screw 7, which has an external thread 7-1 that engages with the internal thread 3-4 inside the synthetic resin portion of the rotor 3.
The outer peripheral surface 8-1 of the guide portion 4-3 of the end bracket 4
It has a complementary shape to the inner peripheral surface of. This relationship is shown in FIG. 2 as a left front partial arrow view of FIG. 1, and in this embodiment, the shape is polygonal (hexagonal). Therefore, the lead screw 7 and the external force receiving member 8 are connected to the guide portion 4.
-3 is supported non-rotatably and slidably in the axial direction. Note that the outer circumferential surface 8-1 of the external force receiving member 8 integrated with the lead screw 7 and the inner circumferential surface of the guide portion 4-3 may have complementary shapes that cannot be rotated, and may have a polygonal shape (hexadecimal shape) as in this embodiment. In addition to the rectangular shape, it is also possible to have a shape as shown in Fig. 3.4.

In this way, by integrally connecting the lead screw 7 and the external force receiving member 8 and supporting the receiving member non-rotatably but slidably in the axial direction, when the rotor 3 is rotated by the rotating magnetic field of the stator 1, , the lead screw 7 and the external force receiving member 8 slide in the axial direction, and the external force receiving member 8 is provided with controlled means to be controlled by linear displacement, such as a valve for controlling the air flow rate of the internal combustion engine. By mounting it, its linear movement can be controlled in response to an external control signal.

In the stroke type step motor according to the present invention, the rotor is particularly formed into a concave shape as shown in FIG. 1 to prevent expansion in the axial direction of the motor. To explain this more specifically, the synthetic resin part 3-2 of the rotor extends from the part where the internal thread part 3-4 is provided and the peripheral part of this part to the left in the figure. The inner ring of a ball bearing 3-3 that rotatably supports the rotor is fixed to this synthetic resin extension, and a multi-pole magnet is mounted on the outer peripheral surface of the ball bearing 3-3. It is located.

On the other hand, a guide portion 4-3 integrally formed with the end bracket 4 of the motor is extended so as to be drawn into a recess formed in the synthetic resin portion of the rotor. A configuration is adopted in which the external force receiving member 8 is slidably supported using the cylindrical space formed by this extension. A structure is adopted in which multi-pole differentially magnetized magnets are arranged on the outer circumferential surface of the synthetic resin portion of the rotor.

By adopting such a structure, it is possible to incorporate the lead screw 7, the external force receiving member 8, etc. inside the rotor in the recessed part of the rotor. This makes it possible to shorten the step motor in the axial direction without reducing the length of the step motor.

Furthermore, due to the structure described above, when an external force (thrust load) is applied to the external force receiving member 8 of the step motor in the axial direction,
Although the thrust load is transmitted to the rotor 3 via the threaded engagement part (7-1 and 5-1), the thrust load is received by the ball bearing 3-3, so no thrust load is applied to the slide bearing 6, so the rotation loss is lower than that of a conventional ball bearing. It also produces the same effect as when two pieces are used. Since the rotor 3 is fixed to the end bracket 4 in the axial direction, even if an external force is applied, the lead screw 7 and the external force receiving member 8
Since the position does not move, highly accurate positioning is possible.

Incidentally, in this embodiment, the step angle is 7.5@, the thread pitch is 0.8 m, and the minimum resolution is 0.017 .

Furthermore, the flat bearing housing 5-IK can prevent eccentricity when the lead screw 7 slides. Furthermore, since the guide portion 4-3 and the housing 5-1 of the base bearing 1 are formed within the inner circumferential surface of both ends of the rotor 3, the space in the direction of the rotating shaft can be used effectively and can be made into a shed.

In addition, in the step motor described above, as described above, the external force receiving member 8 and the lead screw 7 are integrated by press fitting or the like, and the outer circumferential surface of the external force receiving member 8 and the recessed portion of the end bracket 4 are aligned. Depending on the shape of the inner periphery, it can be slid in the axial direction and also serves to prevent the lead screw 7 from rotating. Therefore, it is used in the prior art,
Like Toscryu 1. There is no need to provide a D-cut section that increases machining costs over the sliding range (i.e. stroke length), and there is no need to separately provide a stopper for the lead screw, making production easier and one-stroke type. It is also effective in converting the step motor into a shed.

Next, another coupling structure between the external force receiving member 8 and the lead screw 7 will be explained with reference to FIGS. 5 to 11. FIG. 5 is a sectional view of the guide portion 4-1, external force receiving member 8, and lead screw tip portion 7-2 of the motor housing shown in FIG. Here, the gap g1 between the guide portion inner circumferential surface 4-1 and the external force receiving member outer circumferential surface 8-1, and the lead screw tip outer circumferential surface 7-3.
Gap g between ゜7-4 and the inner peripheral surface of the external force receiving member! The relationship is as follows.

gt<gs In other words, the inner circumferential surface of the guide part 4-1 and the outer circumferential surface of the external force receiving member 8-
The gap g1 between In addition, since the gap gs between the lead screw tip outer circumferential surface 7-3, 7-4 and the external force receiving member inner circumferential surface is relatively large, the screw engagement part, the guide part, and the external force Even if the axis of the receiving member is slightly misaligned, this can be absorbed, thereby preventing deterioration of the rotation to linear motion conversion efficiency caused by the threaded engagement portions (3-3 and 7-11).

As described above, according to this embodiment, when the axial eccentric force from the load side is received by the external force receiving member 8 with a small gap g1 with the guide portion 4-1, it is not transmitted to the lead screw. In addition, since the gap g3 between the external force receiving member and the lead screw is relatively large, the misalignment of the axis between the threaded engagement part and the guide part can be absorbed, which reduces the machining accuracy of the motor housing. It has a highly reliable structure with no fear of locking. Furthermore, although the lead screw tip 7-2 has a so-called D-cut shape, it only needs to be long enough to fit into the inner circumferential surface of the external force receiving member, and the machining length can be short.

6 to 11 are given as other examples of the shapes of the guide portion 4-1, external force receiving member 8, and lead screw tip 7-2 in FIG. 5, but the hexagonal shape may be other polygonal shapes. But it doesn't matter.

As described above, according to this embodiment, in a step motor of the so-called stroke (linear displacement) type in which the rotary motion of the rotor is converted into linear motion via the lead screw, the The motor does not lock even if a force (axial eccentric force) is applied, and the machining accuracy can be relatively lowered, resulting in cost reduction.

Axial space can be used effectively,
, This makes it possible to provide a stroke type step motor with a K-shaped structure and a shortened axial length I.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of a stroke type step motor which is an embodiment of the present invention, Fig. 2 is a partial view taken in the direction of the arrow in Fig. 1, and Figs. 3.4 are external force receiving members which are other embodiments. Outer surface view/
5 is a sectional view taken along the line 13-"B' in FIG. 1, and FIGS. 6 to 1'1 are sectional views taken along the line BB' according to other embodiments shown in FIG. 5. 3.・Rotor, 3-3...Ball bearing, 3-
5... Lugging part, 3-6... Heat tightening part, 4...
End bracket, 4-1...Ball bearing housing, 4-2...Housing end, 4-3...Guide part, 5...Casing, 5-1...Slide bearing housing part, 6 ...Subeshi bearing, 7...Lead screw, butt...External 1 drawing and 2 drawings

Claims (5)

[Claims] 1. a stator that generates a rotating magnetic field by a supplied current; a rotor having a plurality of magnetized multi-pole magnets disposed on its outer peripheral surface and rotatably supported within the stator; and a rotor provided on the rotating shaft of the rotor. a lead screw portion that has a threaded engagement mechanism that engages with the threaded portion, is non-rotatably supported so as to be slidable in the direction of the rotational axis, and that moves linearly in the axial direction in accordance with the rotational movement of the rotor; A stroke type step motor is provided with an external force receiving means coupled to a screw part and transmitting a linear motion to a controlled part to be linearly controlled, and a recess is provided in the direction of the rotational axis of the rotor, and a recess is provided inside the recess. A stroke type step motor, characterized in that a means for preventing rotation of the lead screw part and an external force receiving means coupled to one end of the lead screw part are arranged. 2. In claim 1, one end of the housing portion of the stator extends into the recess of the rotor, the external force receiving means is slidably supported in the axial direction on the inner peripheral surface of the extension, and the housing portion of the stator is extended into the recess of the rotor. A stroke type step motor, characterized in that a cross section of the inner peripheral surface of the part and a cross section of the external force receiving means have complementary shapes that cannot be rotated. 3. A stroke type step motor according to claim 2, wherein the sliding external force receiving means and the lead screw portion are integrally connected. 4. A stroke type step motor according to claim 2, characterized in that the sliding external force receiving means and the lead screw portion are coupled only in a mutually non-rotatable manner by a complementary shape. . 5. Claim 1: The stroke type stepper according to claim 1, wherein the stator has a housing portion, and the rotor is rotatably supported at one end by a ball bearing and at the other end by a slide bearing. motor.