JPH0547373Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a structure that prevents contamination from a bearing that supports a rotary disk of an encoder, and that increases detection accuracy as well as miniaturization.

(Prior Art) As shown in FIG. 3, in a conventional encoder, a housing 4 is supported via a bearing 3 on the outer circumferential surface of a hollow shaft 2 which is inserted and fixed onto a rotating shaft 1. A light receiving element 7 and a light emitting element case 8 are attached via the base 5 of the housing 4, a light emitting element 8 is provided in the light emitting element case 7, and a rotating disk 11 is attached to a rotating disk mounting part 10 provided laterally from the bearing part of the hollow shaft 2. is fixedly placed between the light emitting element 8 and the light receiving element 6. (For example, Japanese Patent Laid-Open No. 61-273146) The bearing 3 has one end in contact with the stepped portion of the hollow shaft 2 and the housing 4, and the other end in a tightening nut 12, 13 screwed into the threaded portion of the hollow shaft and the housing, respectively. It is twisted and fixed.

(Problem to be solved by the present invention) However, it is necessary to firmly maintain the mutual positions of the bearings 3 so as not to reduce the detection accuracy due to eccentricity or vibration of the rotary disk 11, and the structure of the bearing portion is relatively small. It is becoming large. For this reason, there is a drawback that the lateral space becomes large when it is attached to a robot shaft or the like. In addition, in order to minimize the axial length, the bearing 3 and the detection part such as the rotating disk 11 are arranged as close as possible, so that the lubricating oil of the bearing 3 is splashed to the rotating disk side and the detection part There were problems such as contamination and miscounting, and since the screws were tightened with nuts, uneven tightening was likely to occur unless the screwing process was performed precisely, making the process cumbersome.

(Means for Solving the Problem) For this reason, the present invention extends the rotary disk mounting portion integrated with the hollow shaft to the outer circumference of the housing, and forms a slight gap between this extended portion and the outer surface of the housing. A rotary disk is held in the extension portion at a radial position of the bearing portion, and a detection element is provided opposite to the rotary disk.

(Function) Therefore, the rotary disk and the detection element are arranged in the radial position of the bearing part, reducing the axial length of the encoder, and since the detection part and the bearing part are not separated laterally, The vibration of the rotary disk due to the inclination of the bearing can be significantly reduced, and the rotary disk mounting part of the hollow shaft is extended to the outside of the housing to form a bent gap, which prevents the rotary disk from becoming dirty due to scattering of lubricating oil from the bearing.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which the same parts as in FIG. 3 are given the same reference numerals. In this embodiment, a translucent type encoder is used, and the hollow shaft 2 and a separately formed extension are press-fitted into one body by inserting the bearing 3 therein. 14 is a preload ring press-fitted into the housing 4.

The bearing 3 is fitted into the hollow shaft 2, inserted into the housing 4, and the preload ring 14 is cold press-fitted. The extension part 9 is press-fitted into the hollow shaft 2 to apply preload to the bearing, and the rotary disc 11 is attached to the rotary disc mounting part 10 at the end extending outward from the housing.
Attach. The housing 4 is provided with a base 5 to which a light emitting element case 7 having a light receiving element 6 and a light emitting element 8 is fixed.

The rotary disk mounting portion 10 is provided at the end of the extension portion 9 extending to the outer periphery of the housing 4, and the rotary disk 11 is attached at a radial position of the bearing 3, with a slight gap between it and the outer surface of the housing 4. Gap g
is formed.

FIG. 2 shows another embodiment, in which a ring-shaped ring protrudes in the axial direction from one side of the facing surface between the rotary disk mounting portion 10 and the housing 4, which constitutes a part of the gap g between the extension portion 9 and the housing 4. A protrusion 15 and a concave groove 16 into which the protrusion 15 is inserted are provided on the other surface to form a narrow gap.

(Effects of the present invention) As described above, the present invention provides an extension part integrated with the hollow shaft with a gap on the outside of the housing, and a rotary disk mounting part is provided at the end of this extension part. , the rotating disk can be placed in a radial position on the outside of the bearing, and there is no axial separation between the rotating disk and the bearing, reducing the inclination of the rotating disk due to backlash in the bearing, and reducing the distortion of the output waveform due to surface runout. In addition, a narrow curved gap is formed between the rotary disk mounting part and the outside of the housing, creating a labyrinth effect, eliminating contamination of the detection part due to lubricating oil from the bearing, and reducing the axial dimension. This has the effect of providing an encoder with excellent detection accuracy.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the upper half of an embodiment of the present invention;
FIG. 2 is a cross-sectional view of the upper half of another embodiment, and FIG. 3 is a cross-sectional view of the upper half of a conventional example. 1 is a rotating shaft, 2 is a hollow shaft, 4 is a housing, 5 is a base, 6 is a light receiving element, 7 is a light emitting element case, 8 is a light emitting element, 9 is an extension part, 10 is a rotating disk mounting part, 11 is a rotating disk, 12 and 13 are tightening nuts, and 14 is a preload ring.

Claims (1)

[Claims for Utility Model Registration] 1. A hollow shaft fitted to a rotating shaft, a rotating disk fixed to the hollow shaft with a bearing fitted between the hollow shaft and a housing, and a housing facing the rotating disk. In the encoder in which a detection element is attached to the shaft, an extension part is formed integrally with the hollow shaft and extends outside the housing with a slight gap, and a rotary disk is fixed to the extension part at a radial position of the bearing. An encoder characterized by having a disk mounting part. 2. The encoder according to claim 1, wherein a part of the gap between the extension part and the outside of the housing is formed with a ring-shaped protrusion provided on one side and protruding in the axial direction, and a groove into which the protrusion is inserted on the other side. .