JPS61254061A - Stroke type stepping motor - Google Patents

Abstract

PURPOSE:To obtain stable and accurate operation for a high load by eliminating the direct application of a force from a load to rotor by screw means and engaging means. CONSTITUTION:A rotor 3a having a magnet 2 is rotated through bearings 6a, 6b on the outer periphery of a shaft 4 press-fitted to an end cover 1 by revolving magnetic field of coils 16a, 16b in stators 15a, 12b. When a high load A is applied externally to a slider 10, a load is applied through a ball bearing 9 to the screw engaging portion 13 of a screw 14 with a shaft 12, but since the shaft 12 and the shaft 4 for rotating the rotor 3a are independent, no load is applied to the shaft 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a so-called stroke type step motor that converts rotary motion of a rotor into linear motion.

The present invention particularly relates to a strophe step motor that can operate stably even under high loads.

[Background of the invention]

The step motor should not have direct digital control and should not overrun when stopped.

1 to have advantages such as position errors not being accumulated.
It is often used as an actuator for positioning control. In addition, in general, it is often more convenient to control positioning using a control actuator by linear displacement rather than by one rotation angle, and stroke type step motors have become popular in recent years.

It is beginning to be used in office automation equipment, automobile electrical components, etc.

A system for controlling the idle-link rotational speed of an internal combustion engine is known from, for example, Japanese Patent Laid-Open No. 57-51934, which uses this type of step control to precisely control the air flow rate.

In this stroke type step motor, since the rotational force of the rotor is converted into linear motion, it is important to suppress the axial load on the rotor shaft as much as possible. The shirt K which performs the linear motion of such a step motor has a male screw formed on its outer circumferential surface.

And... it is supported by a pair of bearings installed on the housing. A pin 31 is fixed to this shaft 30.

A bearing 33 provided in the housing 32 is provided with a slit 34 through which the bottle 31 can slide in the axial direction.

Therefore, when a high load is applied, an axial load acts on the end face of the rotor from the meshing part of the screw.

The inner frame of the ball bearing is pressed. The purpose of using the pair of ball bearings is to absorb the axial load that is constantly applied when pushing and pulling the shaft, but compared to other bearings, the ball bearings are durable. However, since the force on the load side is directly applied to the rotor side,
There is a problem in that the ball part of the ball bearing part wears out depending on the load, rotation speed, and operation frequency, making it impossible to withstand long-term use.

Moreover, since there is a rotor fitting part on the side of the center hole of the inner race and a shaft is provided in the center hole of the fitting part, the ball bearing must be large in size. These factors currently result in a considerable increase in costs.

[Purpose of the invention]

In view of the above-mentioned prior art, the object of the present invention is to convert the rotational motion of an a-tar into linear motion via a screw.

In a so-called stroke type step motor.

An object of the present invention is to provide a stroke type step motor that can operate stably and with high precision even under high loads.

[Summary of the invention]

The object of the present invention as described above is to provide a stator that generates a rotating magnetic field by a supplied current, and a stator that has a plurality of magnets magnetized to alternately reversed poles on its outer circumferential surface, and that rotates within the stator. A step motor consists of a rotor that rotates according to a magnetic field.

In the stroke type step motor that converts the rotation of the rotor into linear motion using a screw means, further:
a nine-row I/I) means that rotates together with the rotor and is slidably supported only in the axial direction of the rotor; and a screwing means that is screwed and fixed to the four-task screw. This is achieved by having a structure that includes means for transmitting the axial movement of the rotor squeezer means to the outside, and that force from a load is not directly applied to the rotor.

[Embodiments of the invention]

A first embodiment of the present invention will be explained below with reference to FIGS. 1 to 4. FIG. 1 is a longitudinal sectional view of a stroke type step motor device showing a first embodiment of the present invention. In the figure, coils 16a and 1 in stators 15a and 15b are shown.
The rotor 3a has a magnet 2 magnetized to 24 poles (N pole, 8 poles alternately) in the circumferential direction by the rotating magnetic field of the rotor 6b. The rotor 3a rotates via a pair of plain bearings 6a and 5b press-fitted into the center hole of the rotor 3a.

Note that the magnet 2 and rotor 3a are integrally molded.

The axial positioning of the rotor 3a on the shaft 4 is as follows.

A retaining ring 7 is attached via thrust washers 5a and 5b. SaraKcI-Evening 3aK is Lotus Creation 1
In this example, a hexagonal hole 3b is formed so that the rotor crease 14 independently slides back and forth in the rotational axis direction of the rotor 3af) while rotating with the rotor 3a. Molded as one piece. On the other hand, the outer periphery of the rotor screw 14 has a similar hexagonal shape that is slightly smaller than the hexagonal hole 3b of the rotor 3a, and the center hole thereof has a female thread and a male thread that engages with the housing. The rotor screw 14 opens the hexagonal hole 3 while rotating together with the rotor 3a.
b while meshing with the male thread of another shaft 12. Furthermore, the relative position ff of the axes of the shaft 4 and the other shaft 12 is better as it is higher, but it is possible to increase the tolerance of the positional accuracy by setting the fitting dimension of the sliding hexagon to be large. becomes.

Next, on the end face of the rotor screw 14 facing opposite to the shaft 4, an extremely small ball bearing 9 is press-fitted with one outer race 8a of a thrust ball bearing 9 in this example, and the other outer race is press-fitted. 8bK is fitted with the leg portion 18 of the slider 10 which passes through a guide hole 17 partially provided in the housing 11 from the outside of the housing 11. In order to clearly show the structure of these fitting portions, FIG. 3 shows a comparative view from the direction of arrow A in FIG. 1. Therefore, while the rotor screw rotates, it slides on the other shaft 12, and the outer races 13a and 8bH, which sandwich the ball bearing 9, are rotatable.
Since the leg portions 18 of the slider 10 are prevented from rotating by the guide holes 17 partially provided in the housing 11, the slider 10 moves linearly. FIG. 2 shows a longitudinal sectional view at the maximum stroke position during operation, and t in FIG. 1 indicates the stroke.

Next, the operation when moving a high load will be explained using FIG. 2. When a high load is applied to the slider 10 from the outside in the direction of arrow C in the figure, the load is applied to the threaded engagement portion 13 between the rotor screw 14 and another shaft 12 via the ball bearing 9, but the shaft 12 and the rotor 3a are Since the shaft 4 rotates independently, no load is applied to the shaft 4. Furthermore, the engagement portion 13 of the screw has an engagement error due to the accuracy error of each screw, so-called backlash, and this backlash is caused by setting the lotus angle' shape and fitting dimension large with respect to the axis of the other shaft 12. Since the deviation of the axis of the rotor screw 14 can be absorbed, the rotor 3a can rotate smoothly and stably nine times when operating against a high load.

To be more specific, if the male screw formed on the other shaft 12 is a trapezoidal screw with a pitch of 5tts and 0.8 m, the step angle per pulse of the step motor is 7.
．． Since the angle is 5°, each step is approximately 0.017 degrees, and a high-resolution stroke type stepping motor can be realized.

FIG. 3 shows a guide hole 17 provided in the housing 11.

The recessed portion 19 of the guide hole 17 is connected to the leg portion 18 of the slider 10.
The reinforcing ribs slide. Furthermore, Figure 4 shows B- in Figure 2.
B' is a cross-sectional view showing a hexagonal shape in which the rotor screw 4 of the rotor 3a is fitted together.

As is clear from the above, in this embodiment, the high operating force and eccentric force caused by sudden changes in load, etc. are transmitted through the slider, rotor screw, shaft, and independent shaft, so these forces are directly transmitted to the rotor. The effect on the side shafts is extremely small. This makes it possible to use a small and inexpensive plain-type bearing for the shaft, making it possible to realize a stroke-type step motor that operates stably even under high loads.

Next, another embodiment of the present invention will be described with reference to FIGS. 5 and 6. In these figures, each component having the same reference numeral as in FIGS. 1 to 4 has the same structure as described above.

In this other embodiment, the rotor 3aK has an arm portion 2°,
The arm portion 20 has a hole 21 provided in the rotor screw 14.
The rotor screw 14 is slidably fitted to the rotor screw 14, and constitutes a rotation transmission section that transmits the rotation of the rotor 3a to the rotor screw 14. In addition, the outer circumferential surface of the Lotus Cleany 14 has a male thread,
This is configured to mesh with a female thread formed on the inner circumferential surface of the housing 11. Furthermore, the rotor screw 14 is on the same extension as the shaft 4,
It is supported by another shaft 7) 12 which is fixed separately from the sliding part.

With the above configuration, the rotor screw 14 is connected to the rotor 3a.
while rotating in synchronization with the rotation of the housing 11 and engaging with the female thread on the inner circumferential surface of the housing 11.

Moreover, it slides in the axial direction while rotating around the other shaft 12.

Next, to explain the operation of the above embodiment, when a high load is applied from the outside to the slider 10 in the direction of the arrow, the rotor screw 14 and the housing 11
A load in the thrust direction is applied to the threaded engagement portion 13 between the shirt 12 and the shaft 4 on which the rotor 3a rotates.
Since it is independent from the shaft 4, no load is applied to the shaft 4 in the thrust direction. Furthermore, the engagement portion 13 of the screw
There is a so-called backlash, which is an engagement error due to the accuracy error of each screw, and the backlash causes the axis of the rotor screw 14 to be misaligned with the precision of the screw 12. However, the hole 21 drilled in the rotor screw 14
By setting a large fitting dimension between the arm part 2.0 of the rotor 3a and the arm part 2.0 of the rotor 3a, it is possible to absorb the misalignment of the axis of the rotor screw 14, so that the rotor 3a rotates smoothly and stably when operating under high loads. becomes possible.

FIG. 6 is a cross-sectional view taken from E to E' in FIG. 5, and shows an example of the shape of the engaging portion 13 between the rotor 3a and the rotor screw 14 and the hole 21 provided in the rotor screw 14. It is.

Next, a third embodiment of the stroke type step motor according to the present invention will be described with reference to FIGS. 7 and 8.

In this embodiment, unlike the above two embodiments, a shaft 4 rotatably supports the rotor 3a.
and another shirt (4b) having a male thread formed on the outer periphery that engages with the female thread of the rotor screw 14 are integrally formed coaxially and fixed to the housing 11. As a result, the rotor screw 14 also has the following characteristics:
While rotating with the 1-taper 3a, it slides in the axial direction within the hexagonal hole 3b while engaging with the male thread of the shirt 4b.

By the way, in the above embodiment, the inner race 81 of the extremely small radial ball bearing 90 is press-fitted to the nine end face of the rotor screw 94 facing away from the rotor 3a.
For outer lace 82.

A slider 10 is press-fitted. Therefore, while the rotor screw 13 rotates, it slides on the threaded portion 4b of the shaft 4, but the outer race 8a1 and the inner race 8b, which sandwich the ball bearing 9, are rotatable, and external loads such as springs and other pushing forces are applied. is slider 1
0, the slider 10 does not rotate in synchronization with the rotor screw 13, but moves linearly back and forth. FIG. 2 shows a longitudinal sectional view at the maximum stroke position during operation.

Other components having the same reference numerals as in FIGS. 1 to 4 have the same structure as described above.

Even in the above embodiment, the high operating force and eccentric force caused by sudden changes in load, etc. are stopped at the threaded engagement part between the rotor screw and the shaft, so these forces are directly applied to the shaft on the rotor side. The influence is extremely small, and at the same time, according to this embodiment, the rotor's rotating shaft and the rotor screw's sliding shaft are integrally configured on the same axis, and the shaft is press-fitted into the end cover, so that the axial direction affected by the rotor screw is It is now possible to use plain type bearings for tilted rotor bearings where the load is not transmitted to the rotor side, making it possible to operate stably under high loads.
A stroke type step motor that is small, inexpensive, and easy to integrate can be obtained.

〔Effect of the invention〕

As is clear from the above, since no load force is directly applied to the shaft on the four-way side, stable operation is achieved even when driving a high load. Moreover, it is possible to provide a stroke type step motor with high control accuracy.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of a stroke type step motor according to the present invention. ! FIG. 2 is a diagram for explaining the operation of the stroke type step motor in FIG. 1, FIG. 3 is a left side view from arrow A in FIG. 1, and FIG. is a BB' cross-sectional view in FIG. 2, FIG. 5 is a cross-sectional view of a second embodiment of the stroke type step motor according to the present invention, and FIG. 6 is a cross-sectional view taken along E-E in FIG. 7 is a sectional view of still another embodiment of the stroke type step motor according to the present invention, and FIG. 8 is a diagram for explaining the operation of the embodiment shown in FIG. 7. It is. 1... End cover, 2... Macscrew) t3a...
・Rotor, 3b...hexagonal hole, 4...shirt)%
5"#5b...Washer% 5a, 5b...Plain type bearing. 7...Retaining ring ssa, sb...Outer race, 9
...Ball bearing, 10...Slider, 11.../~
Uzing. 12...Shaft, 13...Screw engagement part, 1
4゜...Rotor screw 1 15a, 15b...
stator. 16a, 16b...Coil, 17...Guide hole, 1
8... Leg portion, 19... Concave portion. 12th Hayabusa 2 Figure 5 SjJ bb

Claims (5)

[Claims] 1. It consists of a stator that generates a rotating magnetic field by a supplied current, and a rotor that has a plurality of magnets magnetized to alternately reversed poles on its outer circumferential surface and rotates within the stator according to the rotating magnetic field. A step motor and a stroke type step motor that converts the rotation of the rotor into linear motion using a screw means, further comprising a rotor screw means that rotates integrally with the rotor and is supported so as to be slidable only in the axial direction of the rotor. A stroke type step motor comprising: a screwing means screwed and fixed to the rotor screw; and means for transmitting the axial movement of the rotor screw to the outside. 2. 2. A stroke type step motor according to claim 1, wherein said rotary motion external transmission means is interlocked with the axial movement of said rotor screw and is non-rotatably supported. 3. In claim 1, the rotor is rotatably supported by a shaft means, a threaded part is formed in a hole formed in the rotation shaft of the rotor screw, and the threaded part is mounted on the outer periphery of the rotor. A stroke type step motor, characterized in that the shaft means has a threaded portion formed therein. 4. 4. A stroke type step motor according to claim 3, wherein said rotor support shaft means and said rotor screw support shaft means are individually fixed to a motor housing. 5. 4. A stroke type step motor according to claim 3, wherein said rotor support shaft means and said rotor screw support shaft means are constructed coaxially and integrally.