JPS6017568Y2 - Gear holding mechanism on gear shaft - Google Patents

Description

[Detailed description of the invention] This invention is a gear that prevents the gear from being pressed between the bearing and the shaft retaining ring that prevents the gear from being pulled out when the gear shaft of the electric disc grinder is pulled out. Regarding the holding mechanism.

In electric disc grinders, in order to reduce noise by mitigating the meshing impact of gears and the propagation of impact force,
In some cases, the fit between the gear and the gear shaft is made smooth, and the gear is attached to the gear shaft using a retaining ring so that the gear can move slightly in the axial direction.

Even in this case, when a grinding wheel is attached to the gear shaft and grinding is performed, there is no force acting on the gear shaft that would cause it to pull out, so it will not pull out.

However, electric disc grinders are not only used for grinding work, but are also sometimes used for cutting work with a cutting wheel attached.

During cutting, the force exerted by the grindstone may act to cause the gear shaft to pull out, so with the gear shaft fixing method described above, the gear shaft may pull out, and the force between the bearing and the shaft retaining ring may cause the gear shaft to pull out. This compresses the gear and stops it from moving with the shaft.

As a result, the problem was that gear noise became worse.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above and more effectively reduce the noise of this type of power tool.

That is, in the present invention, when the gear shaft moves in the direction of extraction,
When the key inserted in the keyway of the gear shaft moves together with the gear shaft, the gear is held down between the bearing and the retaining ring that prevents the gear from being pulled out, preventing the gear from stopping. The key placement has been devised so that

An example of the present invention will be shown.

Between the gear cover 7 attached to the housing 1 and the packing gland 15 attached to the gear cover 7, the pinion 4 fixed to the tip of the motor shaft 2 with a nut 5 and the gear shaft 8 are smoothly fitted and the key is inserted. 11 and a gear 10 attached with a shaft retaining ring are meshed with each other.

As shown in FIG. 2, the gear 10 is mounted with a gap created by the dimensional difference between the end face of the gear 10 and the retaining ring 9.

Therefore, the gear 10 can move smoothly in the axial direction by a gap, and in the circumferential direction, the width of the key 11 fixed to the key groove of the gear shaft 8 is determined by the width of the key groove of the gear 10. It is in a state where it can move smoothly within the gap that is created.

The motor shaft 2 is rotatably supported by a ball bearing 3, and the gear shaft 8 is also rotatably supported by ball bearings 6 and 14.

A grindstone 16 is fixed to the tip of the gear shaft 8.

The keyway of the gear shaft 8 is such that one end surface 18 of the key 11 is connected to the gear shaft 8.
It is formed so as to be in contact with one end surface 20 of the key groove, and to provide a gap a between the other end surface 19 of the key 11 and the inner ring 17 of the ball bearing 14.

In this case, this gap a is made slightly smaller than the above-mentioned gap.

In FIG. 1, when a force in the direction of arrow A is applied to the grindstone 16, the gear shaft 8 does not move in the direction of extraction (in the direction of arrow B).

When a force in the direction of arrow B is applied to the grindstone 16, the gear shaft 8 is press-fitted into the ball bearings 6 and 14, but the gear shaft 8 is pulled out in the direction of arrow B.

At this time, the key 11 is pushed by the keyway end surface 20 of the gear shaft 8 and moves in the direction of arrow B together with the gear shaft 8. When the key 11 moves by the above-mentioned gap a, the inner ring 17 of the ball bearing 14 fixed to the packing gland 15 The movement is stopped when it hits.

Therefore, the gear shaft 8 also stops after moving by the gap a.
It won't move any further.

Here, as mentioned above, the relationship between the gap a and the gap is a
Since <b, a gap between the shaft retaining ring 9 and the end face of the gear 10 always exists, and the gear 10 is maintained in the above-described state and will not be pressed and become immobile.

As described above, according to the present invention, even if the gear shaft and gear are fitted with a loose fit, the key that transmits power is used to prevent the gear shaft from coming out and prevent the bearing and gear from coming out. This has the effect that the gear is not held down by the retaining ring that prevents it from moving (it does not worsen gear noise).

[Brief explanation of the drawing]

Fig. 1 is a partially longitudinal side view showing one embodiment of the present invention;
The figure is an enlarged vertical sectional side view of the main part in FIG. 1. 8... Gear shaft, 9... Shaft retaining ring, 10
...Gear (gear), 11 ...Key 1
4...Bearing, 17...Bearing inner ring.

Claims (1)

[Scope of utility model registration request] A bearing fixed to the main body, a gear shaft rotatably supported by the bearing, and a gear fixed to a fitting part between the gear shaft and a gear that loosely fits with the gear shaft and slidably connected to the gear. A gear shaft comprising a key that engages to transmit driving force, and a retaining ring that is fixed to the gear shaft and limits sliding movement of the gear, wherein one end of the key and the inner ring of the bearing A gear holding mechanism, wherein the key is set and arranged so that the gap is smaller than the gap between the end face of the gear and the retaining ring.