JPS61109437A - Stepping motor - Google Patents

Abstract

PURPOSE:To obtain an economical lead screw type motor of high precision, by supporting a load in the radial direction of a rotor with two plain bearings in the radial direction, and by supporting a load in the axial direction with a thrust roller bearing. CONSTITUTION:With regard to a stepping motor where a female screw 2 is formed on the inner periphery of a rotor 1 and a screw shaft 3 is spirally combined with the female screw 2 and the rotational force of the rotor 1 is converted to the motion of the screw shaft 3 in the axial direction is concerned, the rotor 1 is pivotally supported by two radial plain bearings 16, 18, to be rotated supporting a vertical load in the axial direction. The rotor 1 is pivotally supported to be rotated supporting a load in the axial direction, by a thrust roller shaft 20 where a retainer 22 and a ball or a roller 21 are arranged to be freely rotated in a plain washer 23.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention mainly relates to a lead screw type stepping motor used in office automation related equipment.

(Conventional configuration and its problems) Fig. 1 shows the configuration of a conventional lead screw type stepping motor, where 1 is a rotor consisting of a multi-pole magnetized magnet on the outer periphery, and 2 is a rotor 1. A female thread 3 is formed on the inner circumferential wall surface of the screw shaft 3, which is screwed into the female thread 2. This screw shaft 3 is prevented from rotating in the radial direction by a locking means (not shown), and a spring member (not shown) ) is biased toward the left in the figure. 4
12 is a mounting bracket for attaching the magnetic pole pieces 6 and 7 containing the coil 5 and the magnetic pole pieces 9 and 10 containing the coil 8 to the mount 11; 12 is the rear end of the rotor 1 and the opening 4a of the mounting bracket 4; between the tip of the rotor 1 and the mount 1
The bearings 12 are radial ball bearings (hereinafter referred to as bearings) interposed between the openings 11a of the rotor 1, and the distance between the outer peripheral wall of the rotor and the inner peripheral surfaces of the magnetic pole pieces 6 and 7, and the The magnetic pole pieces 9 and 10 are supported so that the distance between the outer circumferential wall surface and the inner circumferential surface of each of the pole pieces 9 and 10 is constant.

In the conventional example configured in this way, when the rotor 1 rotates, the screw shaft 3 moves linearly in the axial direction by a length proportional to the rotation angle of the rotor 1.

Incidentally, since the screw shaft 3 is always urged leftward in the figure by the spring member, the inner ring 13 of the bearing 12 fixed to the rotor 1 is urged leftward in the figure, and the inner ring 13 of the bearing 12 and A positional shift occurs in the axial direction relative to the outer shaft 14. Therefore, the frictional forces between the guide groove of the inner ring 13 and the balls 15 and between the guide grooves of the outer shaft 14 and the balls 15 increase, making it difficult to obtain the desired torque, desired feed accuracy, etc. Furthermore, even if the load in the thrust direction applied to the rotor 1 is to be supported by a thrust plain bearing, the frictional force between the members of the thrust plain bearing increases, making it impossible to obtain the desired torque, desired feed accuracy, etc. It becomes difficult. As a result, in order to support the load in the thrust direction applied to the rotor 1, a thrust rolling bearing must be additionally used, resulting in a drawback that the stepping motor becomes expensive.

(Object of the invention) 31 The object of the present invention was made in view of the above-mentioned drawbacks,
The object of the present invention is to provide an inexpensive and high-precision glued screw type stepping motor by using a rotor support structure that uses cheaper parts.

(Structure of the Invention) The present invention supports a load perpendicular to the axial direction applied to a rotor by two radial flat bearings, and a ball or roller rotatably held in a retainer is sandwiched between flat washers. The load in the axial direction applied to the rotor is supported by a single thrust rolling bearing.

(Explanation of Embodiment) FIGS. 2 to 4 show the configuration of an embodiment of the present invention, and the same reference numerals as those in FIG. 1 indicate the same parts. In the figures to FIG. 4, reference numeral 16 denotes a radial flat bearing (hereinafter referred to as shaft bearing) interposed between the rear end of the rotor 1 and the opening 4a of the mounting bracket 4. The rotor 1 is rotatably supported while supporting a load perpendicular to iN[. A radial plain bearing 17 rotatably supports the rotor 1 while supporting a load perpendicular to the axial direction at the inner edge of the opening 17a.
18 (hereinafter referred to as a bearing) is integrally formed, and a cylindrical flange 19 for protecting the bearing is integrally protruded from the outer periphery of the opening 17a.
, magnetic pole pieces 6 and 7 with a coil 5 inside and magnetic pole pieces 9 and 1o with a coil 8 inside are attached by mounting fittings 4, respectively. 20 is a thrust ball bearing (hereinafter referred to as a bearing) consisting of a retainer 22 holding a ball 21 and two flat washers 23 holding the ball 21; 24 is carved in the circumferential direction on the outer peripheral wall surface of the tip of the rotor 1; groove, 25 is flange 19 of mount +7
When this retaining ring 25 is fitted into the groove 24, one flat washer 23 is brought into close contact with the mount 17 and the retaining shaft is fitted into the groove 24 with the bearing 2o accommodated therein.
7, and the other flat washer 23 rotates with the ring 25 at 1.
The rotor 1 rotates in close contact with the rotor 1. In Figure 4,
26 is two guide rails with a stopper 27 attached to one end, 28 is a mounting plate to which the steering motor and the other end of the two guide rails 26 are fixed, and 29 is a screw shaft 3 attached to the two guide rails 26. A movable base is attached so as to be movable in the axial direction, 30 is a contact plate installed at the rear end of the movable base 29, and 11 is a base formed by cutting out a part of the bent end of the contact plate 30. The square-shaped stopper 32 is a rotation stopper with one end fixed to the tip of the screw shaft 3, and this rotation +1-
The other end of the eyelet 32 is engaged with the stopper 31. 33 is a spring interposed between the stopper 27 and the tip of the moving table 29;
The tension force of the spring 33 biases the movable table 29 to the left in the figure.

In this embodiment configured in this manner, when the rotor 1 is not rotating, the moving table 29 is biased to the left in the figure by the tension of the spring 33, and the contact plate 30 is pushed against the screw shaft 3.
is in contact with the tip of the Therefore.

When the rotor 1 is rotated in the direction of arrow A in FIG.
The screw shaft 3, which is prevented from rotating in the radial direction by the rotation stopper 32 engaged with the stopper 31, moves to the right in the figure, presses the contact plate 30 to the right in the figure, and moves the moving table 29.
is moved to the right in the figure against the tension of the spring 33.

Furthermore, when the rotor 1 is rotated in the direction opposite to the direction of arrow A in FIG.
Due to the tension of the spring 33, the movable table 29 moves to the left in the figure while maintaining the contact state between the screw shaft 3 and the contact plate 30.

By the way, as is clear from the above explanation, the tension force of the spring 33 is always applied to the screw shaft 3 via the moving table 29 and the contact plate 30, so that the tension force of the spring 33 is always applied to the screw shaft 3 through the moving table 29 and the contact plate 30. Although a load is always applied in the left direction in the figure, that is, in the thrust direction, no load is applied to the rotor l because it is supported by the single rotor bearing 20. Also, an attractive force is applied to the rotor 1 in the radial direction due to the load of the rotor 1 and the unbalance of the magnetic circuit, but since the load and the attractive force are not so large, the bearings 16 and 18
Even if the rotor is supported by the rotor, almost no load is applied to it.

(Effects of the Invention) As explained above, according to the present invention, the rotor is supported by an inexpensive plain bearing and a thrust rolling bearing, so that the reed-type stepping motor is inexpensive, and It has the advantage of high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a half cut section of a conventional lead screw type stepping motor, FIG. 2 is a plan view of a half cut section of an embodiment of the present invention, and FIG. 3 is an exploded perspective view of an embodiment of the present invention. , FIG. 4 is a perspective view showing an example of use of an embodiment of the present invention. 1...Rotor, 2...Female thread, 3...
・Screw shaft, 16.18...radial plain bearing,
20... Thrust ball bearing (thrust rolling bearing), 21... Ball, 22... Retainer, 2
3...Flat washer. Patent applicant Matsushita Electric Industrial Co., Ltd. = 8- Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a stepping motor that rotates a rotor having a female thread formed on its inner periphery to linearly move a screw shaft screwed into the female thread in an axial direction, the rotor is moved while supporting a load perpendicular to the axial direction. Rotatably pivoted 2
Two radial plain bearings and a ball or roller rotatably held in a retainer are sandwiched between flat washers, and one rotor is rotatably supported while supporting the load in the axial direction. A stepping motor characterized by being equipped with a thrust rolling bearing.