JPH0641810Y2 - electric screwdriver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Use of the Invention] The present invention relates to an output shaft of an electric screwdriver with a clutch.

[Background of the invention]

A conventional example will be described with reference to FIG. The rotation of the motor shaft 1 is transmitted via the pinion 2 and the first gear 3 to the second pinions 4 and 5 provided coaxially with the first gear 3. A gear 6 (hereinafter referred to as a final gear) meshing with the second pinions 4 and 5 is spline-fitted to the spindle 8 and moves on the shaft of the spindle 8 by moving the shift lever 9 back and forth. A drive side clutch 11 is fastened and fixed to one end of the spindle 8 and a hole 10 is formed in the shaft center. The output shaft 12 is securely supported by inserting one end of the output shaft 12 into the hole 10 and providing the bearing 7 at the other end. The output shaft 12 is spline-fitted with a driven side clutch 13 having a claw that meshes with a ball 11 'disposed in the driving side clutch 11. A thrust bearing 14, a thrust plate 15, and a spring 16 are arranged on the back surface of the driven clutch 13, and the spring force of the spring is received by a spring holder 17. Although the spring holder 17 does not rotate, it is free to move in the axial direction, and the torque adjusting cap 18 having a step-like protrusion formed inside is rotated to press the spring 16 and release torque (ball 11 'And the torque at which the driven side clutch 13 disengages) are adjusted. In such an electric screwdriver, normally, the spindle 8 and the output shaft 12 rotate together, but when a torque equal to or higher than a set torque is applied to the output shaft 12, the motor shaft 1 tries to continue to rotate, but the ball 11 ' The driven side clutch 13 is disengaged and the clutch operates. That is, the spindle 8 and the output shaft 12 are formed separately, and slippage occurs between them. As described above, in the conventional example, since the two shafts, the spindle 8 and the output shaft 12, are used to interrupt the rotation, the bearings are provided at four places to support the respective shafts. Further, because of the structure, one bearing is unavoidably provided on the end surface of the spindle 8.
The clearance between the output shaft 12 and the output shaft 12 needs to be larger than usual, and the distance between the bearings of the output shaft 12 is also short, which causes large runout of the tip tool (not shown) and reduces work accuracy. It had the drawback of

[Purpose of device]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a compact electric screwdriver with less runout of the tip tool.

[Outline of device]

The present invention focuses on the fact that if the spindle and the output shaft are coaxial, the spacing between the bearings that support the output shaft can be widened, and the number of bearings can be small. The shape of the output shaft is devised.

[Example of device]

An embodiment of the present invention will be described with reference to FIGS. The output shaft 28 is supported near both ends by a pair of bearings 7 and 34. A spline is formed in front of the middle of the output shaft 28 (on the tip tool side) and a driven side clutch 13 is slidably fitted. There is. Behind the middle of the output shaft 28 (on the side opposite the tip tool),
A hollow shaft 31 is provided, which rotates smoothly with respect to the output shaft 28 and has a drive side clutch 11 which is fixed by interference fitting at one end. A long hole 32 is bored in a part of the hollow shaft 31 in the longitudinal direction.
Insert key 33 into 32. On the other hand, the final gear 6 is a hollow shaft.
It can be slidably moved on 31 and can be rotated integrally with hollow shaft 31 by key 33. That is, the hollow shaft 31, the final gear 6, and the drive side clutch 11 are connected so that torque can be transmitted. If the electric screwdriver constructed as described above is normally used, the rotation transmitted to the final gear 6 is generated by the key 33,
The drive side clutch 11 is rotated via the hollow shaft 31. Next, the driven side clutch 13 having a pawl that meshes with the ball 11 'rotates, and the driven side clutch 13 is spline-fitted to the output shaft.
28 rotates. If a torque larger than the dissociation torque is applied to the output shaft 28 during work, slippage occurs between the hollow shaft 31 and the output shaft 28 and the clutch operates. In the above-described embodiment, the hollow shaft 31 and the final gear 6 are connected by the key 33,
The same effect can be obtained by forming the hollow shaft 31 into a polygonal shape such as a quadrangle as shown in FIG.

[Effect of device]

According to the present invention, since the output shaft has a double structure, the distance between the bearings supporting the output shaft can be widened without impairing the functions of the conventional speed change mechanism and clutch mechanism, and the touch of the tip tool can be reduced. Accuracy is improved. Further, as compared with the case where the spindle and the output shaft are supported separately, the overall length in the axial direction can be shortened, so that a compact product can be provided.

[Brief description of drawings]

1 is a longitudinal sectional view of an electric screwdriver showing an embodiment of the present invention, FIG. 2 is a partially enlarged perspective view of an output shaft showing an embodiment of the present invention, and FIG. FIG. 4 is a vertical sectional view of a hollow shaft showing a modified example of the present invention, and FIG. 5 is a vertical sectional view showing a conventional electric screwdriver. In the figure, 1 is a motor shaft, 6 is a gear, 7 is a bearing, and 11
Is a drive side clutch, 13 is a driven side clutch, 28 is an output shaft,
Reference numeral 31 is a hollow shaft, and 34 is a bearing.

Claims (1)

[Scope of utility model registration request] 1. A motor, a gear driven by the motor, a driving side clutch that rotates integrally with the gear, a driven side clutch that is disengageably engaged with the driving side clutch, and the driven side. In an electric screwdriver having a clutch and an output shaft that rotates integrally with the clutch, the output shaft is rotatably supported by supporting a pair of bearings around both ends of the output shaft, covering the output shaft, and rotatable with respect to the output shaft. An electric screwdriver having a hollow shaft, wherein the hollow shaft, the gear, and the drive-side clutch are connected so that torque can be transmitted.