JPS5841109Y2 - gear switching device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a switching device for a power tool having a rotational speed change mechanism.

In conventional switching knobs, the part that holds the gear is made of metal, the operating part is made of resin or metal, and the two parts are screwed together, and the part that comes into contact with the gear is made of metal and is not arc-shaped, resulting in high contact resistance. In addition, since the tip of the metal part is not narrower than the root, it hits the entire surface of the gear, making the movement on the shaft a little heavy, and the metal parts hitting each other, which has the disadvantage of causing noise and premature failure of the gear. Some improvement was needed.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to simplify this type of switching device.

The present invention focuses on a resin that is easy to mold and has excellent wear resistance, and has been devised so that there is little resistance due to contact with gears and smooth axial movement is possible.

Embodiments of the present invention will be described with reference to FIGS. 1, 2, 3, and 4.

FIG. 1 shows a sectional view of the main body.

In FIG. 1, the rotation of the motor 9 is controlled by gears (4) 10,
It is transmitted to the gear (1) 4 via the gear (3) 7 and the gear (2) 6, and the drive shaft 3 rotates.

This gear (1) 4 is movable on the drive shaft 3, and this movement is performed by a switching knob 12 integrally molded with resin.

When gear (1) 4 is moved and meshed with portions a and b of gear (2) 6, the rotation of drive shaft 3 changes.

In Fig. 2, the width of the switching knob 12 is changed between the root part A and the tip part B so that the part closest to the shaft of gear (1) 4 contacts the shaft of gear (1) 4 first. The upward movement becomes smooth.

In FIG. 4, the switching knob 12 is provided with an arcuate portion C at the portion that sandwiches the gear, thereby reducing the contact area with the gear (1) 4 and reducing contact resistance.

According to the present invention, the contact between the gear and the switching knob is kept small, and the tip of the leg of the switching knob is narrow and contacts the gear at a position close to the shaft, which reduces metallic noise during rotation and reduces rotation loss. The axial movement of the lowering gear can be performed smoothly.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the power tool of the present invention, FIG. 2 is a front view showing the relationship between the switching knob and the gear,
Figure 3 is a side view, and Figure 4 is a drawing seen from below. In the figure, 1 is the outer frame, 2 is the bearing (1), 3 is the drive shaft,
4 is a gear (1), 5 is a bearing (2), 6 is a gear (2), 7
8 is a gear (3), 8 is a bearing (3), 9 is a motor, 10 is a gear (4), 11 is a bearing (4), and 12 is a switching knob.

Claims (1)

[Scope of utility model registration request] A power tool in which a gear is sandwiched between a switching knob integrally molded with resin, and the switching knob moves the gear on the drive shaft to change the engagement of the gears and change the rotation of the drive shaft. The contact portion is formed in a circular arc shape, and the contact resistance between the circular arc portion and the gear is configured to be small, and the tip of the circular arc portion is brought as close as possible to the drive shaft, and the width of the tip of the pair of circular arc portions is increased. A switching device in which the gear is formed narrower than the center of the root so that the gear can move smoothly on the shaft.