JPH0285711A - Fitting structure for rotation detector - Google Patents

Abstract

PURPOSE:To extend the service life of an encoder so as to improve the reliability of the encoder by providing a ring spring, outside wheel, and inside wheel. CONSTITUTION:A ring spring 1 having a rigid structure in the circumferential direction and flexible structure in the radial direction is formed by connecting an outside and inside rings 11 and 12 with connecting bars 13 which intersect each other in the radial direction. The spring 1 is fitted to a motor side by means of tongue pieces 15 of the ring 1 protruding outward and, at the same time, an encoder is fitted to the spring 1 by means of holes H1 on the inside ring 12. Since the spring 1 has a rigid structure in the circumferential direction and flexible structure in the radial direction, the centers of the inside and outside rings displace or move along the applied line of force in parallel with the applied line even when the force is applied to the spring 1 from any direction. Therefore, even when a motor shaft deviates from the central axis of the encoder and the center of the encoder displaces from a point P to another point P1, then, a fixed slit is displaced from a point F to another point F1 when the motor shaft rotates by an angle Ma, the rotational angle detected by the encoder is Pa, and the relation of Ma=Pa is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mounting structure for a rotation detector (encoder) in a servo motor.

[Conventional technology]

FIG. 2 is a side view of a rotation detector mounting structure that is currently widely used. That is, a valve coder shaft 6 having a rotating slit 5 is fitted onto the motor shaft 7, the fixed slit 4 is fixed to the fixed slit base 3, and the stand 31 of the fixed slit base 3 and the motor stud 21 are connected to each other by a plate. It is attached to spring 1'. As shown in FIG. 4, the leaf spring 1' extends from an annular plate part 10 having a width W having a hole H for attaching a stand 31 to a tongue piece 1 having a hole H2 for attaching to a motor stud 21.
It has a structure in which the number 5 stands out.

[Problem to be solved by the invention]

In the above-mentioned conventional structure, the circumferential rigidity absolutely necessary for the rotation detector mounting plate spring consisting of the rotating slit and the fixed slit is satisfied by the annular plate portion 10 of the plate spring 1', and The elasticity needed to absorb mounting strain in the axial direction of the rotating shaft 7 can be absorbed by the bending of the temporary spring, but since the annular plate has high rigidity in the radial direction as well, the axial center of the motor shaft and encoder is slightly Even if the axis is misaligned, the strain cannot be absorbed, and if the axis is misaligned, an excessive load is applied to the encoder bearing, reducing the lifespan and reliability of the encoder.In the end, this type of encoder The mounting structure required precision, and the service life and operation reliability were insufficient.

The present invention solves the above-mentioned problems at once by employing a ring spring with a novel structure.

[Means to solve the problem]

For example, as shown in FIG. 1A, the conventional leaf spring 1' of FIG.
The outer ring 1 is formed by punching the annular plate portion 10 of the
1. The ring spring 1 is formed into a shape consisting of an inner ring 12 and a connecting bar 13 that connects the two rings and intersects in the radial direction to have a rigid structure in the circumferential direction and a flexible structure in the radial direction. Similarly, an encoder, that is, a fixed slit stand was attached to the motor side via the tongue piece 15 projecting outward, and to the hole H1 on the inner ring 12.

[For production]

The ring spring 1 has a rigid structure in the circumferential direction and a flexible structure in the radial direction, and even if a force is applied to the ring spring 1 from any direction,
The centers of the inner ring and outer ring of the ring spring are on the line of action of the force,
Alternatively, since the structure is such that the motor shaft and encoder are displaced and moved parallel to the line of action, there is a misalignment between the axial centers of the motor shaft and the encoder, and as shown in FIG. Even if the fixed slit is displaced from F to F, the rotation angle detected by the encoder is Pα, and the relationship Mα=Pα is maintained.

〔Example〕

(Example 1) As shown in FIG. 1A, three linear bars 13 of low rigidity are left between the outer ring 11 and the inner ring 12 of high rigidity at equal intervals and in a direction perpendicular to the radial direction, A conventional temporary spring (
Figure 4) The material was punched.

In the obtained ring spring l, since each connecting bar 13 is perpendicular to the radial direction, each bar 13 can be deformed in the radial direction, and the inner ring 12 is rigid in the circumferential direction compared to the outer ring 11. However, in the radial direction, it has elasticity caused only by the connecting bar.

As shown in FIG. 2, this ring spring 1 is attached to the encoder, that is, the stand 31 of the fixed slit stand by inserting the screw SI into the hole H1 of each protrusion 14 on the inner ring 11 side. The screws S2 were inserted into the mounting holes H2 and screwed and fixed to the three motor stands 21.

In the mounting structure of this embodiment, as shown in FIG. 3, even if the axis of the fixed slit base, that is, the encoder axis P and the motor axis M are misaligned, for example, when the motor rotates by an angle Mα, In this case, the encoder axis is displaced from P to P, but the position of the fixed slit is also displaced in parallel from F to F, so the encoder also rotates by an angle Pα, and Mα=Pα. This rotational angle relationship remains unchanged as long as the outer ring 11 and inner ring 12 of the ring spring maintain their rigidity in the circumferential direction. Therefore, in the mounting structure of this example, both the radial strain and the axial strain between the encoder and the motor can be suitably absorbed by the elasticity of the ring spring 1 in the radial and axial directions.

(Example 2) As shown in FIG. 1B, the structure was the same as in Example 1 except that the connecting bar 13 between the outer ring 11 and the inner ring 12 was arranged in a pantograph shape.

In the ring spring 1 of this example, the elasticity in the radial direction between the outer ring and the inner ring is considerably smaller than that in Example 1, but the rigidity in the circumferential direction is larger than that in Example 1. The same objectives and effects of the present invention have been achieved.

(Others) Various commonly used methods of connecting the outer ring 11 and inner ring 12 of the ring spring 1 to provide rigidity in the circumferential direction and elasticity in the radial direction include a piston-cylinder mechanism, a combination of a fixed pin and a coil spring, etc. It is possible to apply means.

〔Effect of the invention〕

The ring spring provides rigidity in the circumferential direction and elasticity in the radial direction to the motor and encoder, so even if the motor's center axis is misaligned with the encoder's center axis, rotation angle detection errors will be reduced. The detector (
The swinging motion of the encoder can be tolerated, and the life of the encoder can be extended without increasing the load on the bearings, and its reliability is also improved.

[Brief explanation of the drawing]

FIG. 1A is a plan view of a ring spring used in the present invention, and FIG. 1B is a modification thereof. FIG. 2 is a longitudinal cross-sectional view of the rotation detector mounting structure of the present invention. FIG. 3 is an explanatory diagram of the operation of the present invention. FIG. 4 is a plan view of a conventional leaf spring. 1...Ring spring, 11...Outer ring, 12...
- Inner ring, 13... Connection bar, 14... Protrusion, 15... Tongue piece, 2... Motor,
21...Motor stand, 3...Fixed slot/throat stand, 31...Stand, 4...Fixed slit,
5...Rotating slit, 6...Pulse coder shaft, 7...Motor shaft, 8...Printed circuit board.

Claims (1)

[Claims] 1. The outer ring (11) of a ring spring (1) having an inner ring (12) connected to the outer ring (11) with a rigid structure in the circumferential direction and a flexible structure in the radial direction is placed on the motor side. In this figure, the rotation detector mounting structure has the inner ring (12) attached to the fixed slit base (3) side. 2. The mounting structure according to claim 1, wherein the outer ring (11) and the inner ring (12) are connected by a plurality of connection bars (13) arranged in a direction crossing the radial direction.