JPH0562172U - Bearing device for stepping motor - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a stepping motor having a lead screw shaft used for a video camera or the like, which has a small number of parts and has excellent characteristics of low noise. [Structure] Since a steel ball 4 at the tip of the lead screw shaft 1 is received, a pivot bearing 5 made of a resin molded product having a conical shape with a conical angle θ of 80 ° to 120 ° is arranged, so that the number of parts is low and the assembly is low. With the number of steps, it is possible to obtain a low noise stepping motor bearing device without rolling noise of steel balls.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a bearing device for a stepping motor having a lead screw shaft used in a video camera or the like.

[0002]

[Prior Art]

 In recent years, stepping motors have been digitized, and have been used for new consumer applications such as video camera autofocus. Accordingly, low noise and low man-hours are required.

A conventional stepping motor will be described below. FIG. 2 shows the structure of a conventional stepping motor. In FIG. 2, reference numeral 1 is a shaft provided with a lead screw 1a. A bearing 2 is press-fitted and fixed to a cup-shaped frame 3. At the tip of the lead screw shaft 1, a steel ball 4 and a pivot bearing 5 for receiving the steel ball 4 are attached to an angle 6. At the tip of the lead screw shaft 1, there is provided a holding spring 7 for restraining the movement of the lead screw shaft 1 in the axial direction, and the lead screw shaft 1 is rotatably fixed. A magnet 8 is provided on the lead screw shaft 1 to form a rotor. A stator portion 9 is housed in a cup-shaped frame 3 at a position facing the outer circumference of the magnet 8. The pivot bearing 5 is provided with several steel balls 5a in a cup-shaped case, and a cover 5b is spot-welded to an upper flange portion of the case of the pivot bearing 5 to prevent the steel ball 5a from falling off during assembly.

The operation of the stepping motor configured as described above will be described below. Several steel balls 5a in the cup-shaped case of the pivot bearing 5 are brought into contact with the steel balls 4 as the steel balls 4 at the tip of the lead screw shaft 1 rotate together with the lead screw shaft 1 and roll.

[0005]

[Problems to be solved by the device]

 However, in the above-mentioned conventional configuration, there are problems that the pivot bearing 5 has a large number of parts and the number of assembling steps is large, and that the steel ball 5a rolls due to the rotation of the lead screw shaft 1 to generate noise. Was there.

The present invention solves the above conventional problems, and an object of the present invention is to provide a low noise stepping motor that does not use rolling and has a small number of parts.

[0007]

[Means for Solving the Problems]

 In order to achieve this object, the bearing device of the stepping motor according to the present invention has a pivot bearing made of a resin molded product, and the steel ball receiving portion has a conical configuration.

[0008]

[Action]

 With this configuration, the pivot bearing of the stepping motor has a reduced number of parts, and because the steel balls do not roll, noise can be reduced.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. The same components as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, a pivot bearing 5 receives a steel ball 4 at the tip of the lead screw shaft 1, and thus is a resin molded product having a conical shape with a conical angle θ, and is press-fitted and fixed to an angle 6.

The operation of the bearing device for the stepping motor configured as described above will be described with reference to FIG. First, when the lead screw shaft 1 rotates, the steel ball 4 also rotates and is pivotally supported by the conical pivot bearing 5. At this time, friction with the steel ball 4 occurs and the axial loss increases, but the pressure of the presser spring 7 that constrains the movement of the lead screw shaft 1 in the axial direction is as small as 40 to 120 gf for video camera autofocus. Therefore, when grease is applied to the pivot bearing material using polyacetal resin, the increase in shaft loss is as small as 0.1 gf · cm and it can be used practically. Further, in order to further reduce the friction, it is effective to use, for example, a fluorine resin-filled grade or an oil-impregnated grade polyacetal as the resin material. Further, the conical angle θ is 80 ° to 120 °, because if it is small, it becomes a wedge shape and the load increases, and if it is large, shaft misalignment occurs due to shaft side pressure load.

As described above, according to this embodiment, since the steel ball 4 receiving portion of the pivot bearing 5 is made of the resin molded product having the conical shape with the cone angle θ, the number of parts is small and the steel ball A low noise bearing device without rolling noise can be obtained.

[0013]

[Effect of the device]

 As is apparent from the above description of the embodiments, the present invention is a stepping motor bearing that is excellent in low assembly man-hours and low noise because the steel ball receiving portion of the pivot bearing is made of a resin molded product with a conical shape. The device can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a stepping motor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional stepping motor.

[Explanation of symbols]

 1 Lead screw shaft 2 Bearing 4 Steel ball 5 Pivot bearing 7 Presser spring

Claims (2)

[Scope of utility model registration request] 1. A bearing for rotatably holding a lead screw shaft, a steel ball mounted on a tip of the lead screw shaft, and a pivot bearing for receiving the steel ball.
A stepping motor which is provided at the other end of the lead screw shaft and is held by a pressing spring that restrains the axial direction, wherein the pivot bearing is made of a resin molded product, and the steel ball receiving portion is formed in a conical shape. Bearing device. 2. A bearing device for a stepping motor according to claim 1, wherein the conical angle of the conical shape of the steel ball receiving portion of the pivot bearing is 80 ° to 120 °.