JP2652660B2 - Electric tool - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power tool configured to rotate a tool with an electric motor.

[Prior Art] A power tool configured to rotate a tool by an electric motor does not generate noise due to backlash on a reduction gear or the like when a load is applied to the tool, and generates noise. It is only due to the gear meshing noise and the processing generated by the tool.

However, when there is no load, since the tool rotates by inertia, another noise is generated from the gear due to backlash of the gear.

[Problems to be Solved by the Invention] This kind of noise is caused by a loosely fitted portion such as a backlash between the tool and the electric motor driving the tool because the tool rotates by inertia when no load is applied. A hit sound is generated at the connection portion.

In particular, in the case of an electric tool in which a grindstone such as a disc grinder is attached as a tool, the inertia due to the rotation of the grindstone is large, and a spline fitting mechanism is incorporated between the electric motor and the grindstone. Rush generates noise, which causes a large backlash between the electric motor and the grindstone as a whole, which increases the noise.

Then, such a backlash as a whole reciprocates between the tool and the electric motor via the fitting mechanism so as to reflect the impact, which is irregular and abnormally loud.

Such noise may be louder than when the motor is rotating under a load, and it has to be processed to reduce the backlash.

However, in order to reduce the backlash, the processing accuracy must be improved, resulting in disadvantageous results such as an increase in price.

The present invention has been made in view of such circumstances, and provides an electric power tool capable of reducing noise caused by backlash on a connection and reducing noise without improving machining accuracy. It is an object.

[Means for Solving the Problems] In a power tool configured to rotate a tool with an electric motor, a tool 6 is mounted on one side, and a load shaft 5 having a first spline 4 formed on the other side; It has a first gear 2 attached to a shaft 1 of the electric motor, and an extending portion that meshes with the first gear 2. An inner periphery of the first gear 2 is fitted with a first spline 4 of the load shaft 5. Forming a second spline 11,
A second gear 3 formed with a third spline 9 fitted on the elastic member 8 on the outer periphery of the side bulging portion 10, and one inner peripheral surface is connected to the first spline 4 of the load shaft 5 by the other. The problem is solved by providing an elastic member 8 whose inner peripheral surface is fitted to the third spline 9 of the gear 3.

[Operation] The noise caused by the backlash generated at the connecting part by the spline is such that the elastic member is used by the tool at a light load such as no load because the part of the connecting part is fitted via the elastic member. And the motor can be fitted to each other, and the effect of backlash of the fitting by the spline is reduced.

Then, since the entire loose fit state formed between the tool and the electric motor is absorbed, the reflection of the impact reciprocating between the tool and the electric motor is cut off, and irregular noise is not generated.

[Embodiment] The present invention will be described based on an embodiment shown in the drawings. FIG. 1 is a longitudinal sectional view of a main part of an electric power tool according to the present invention, and FIG. FIG.

In FIG. 1, in a power tool configured to rotate a tool by an electric motor, one is attached to a tool 6 and the other is a load shaft 5 having a first spline 4 formed thereon.
A first gear 2 attached to a shaft 1 of the electric motor;
It has an extended portion that meshes with the first gear 2, and a second spline 11 that fits with the first spline 4 of the load shaft 5 is formed on the inner periphery. Has an elastic member 8
Gear 3 having a third spline 9 fitted therein
And one inner peripheral surface of the first spline 4 of the load shaft 5.
And an elastic member 8 having the other inner peripheral surface fitted to the third spline 9 of the gear 3.

In such a configuration, the power tool rotates the shaft 1 by the rotation of the electric motor, and the first gear 2 attached to the shaft 1 meshes with another extended portion of the second gear 3 having a large diameter. And rotate it at reduced speed.

When the gear 3 rotates, the load shaft 5 rotates via the second spline 11 and the first spline 4, for example, a grindstone rotates as the tool 6, and can be used as an electric tool.

Further, when a load is applied to the tool 6, the torque of the electric motor is sequentially transmitted from the shaft 1 to the tool 6 by a coupling mechanism including the gear 2, the gear 3, the lower portion of the first spline 4 and the load shaft 5. .

When a load is applied to the tool 6, the tool 6 rotates by inertia, and the gears 2, 3, the first spline 4, and the second spline 11 are caused by backlash of a coupling mechanism formed between the tool 6 and the shaft 1. For example, a hitting sound is generated at the meshing and fitting portions. This is due to the phenomenon that the tool 6 becomes faster than the rotation by the electric motor due to inertia, and the impact in the rotating direction is reflected between the tool 6 and the shaft 1 to reciprocate.

However, according to the invention of the present application, the load shaft 5 and the gear 3 are partially fitted through the elastic member 8, so that the impact in the rotational direction is reflected between the tool 6 such as the upper part and the shaft 1. The phenomenon of reciprocation is absorbed and no longer occurs.

That is, at the time of no load, the gear 3
The load shaft 5 and the load shaft 5 are intermittently fitted to each other, so that the second spline 11 of the gear 3 and the spline 4 of the load shaft 5, that is, the portion where the gear 3 and the load shaft 5 are directly fitted by backlash. Even if the loose fit state is formed, the loose fit state can be substantially eliminated. Therefore, there is no phenomenon such as the impact being reflected between the tool 6 and the shaft 1, and no noise is generated.

[Effects of the Invention] According to the present invention, it is possible to obtain a power tool capable of reducing noise caused by backlash on a connection and improving noise without improving machining accuracy,
The effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an essential part of an electric power tool according to the present invention, and FIG. 2 is a transverse sectional view of the essential part. 1 ... shaft, 2 ... first gear, 3 ... second gear, 4 ...
... first spline, 5 ... shaft, 6 ... tool, 8 ... elastic member, 9 ... third spline, 10 ... bulge, 11 ... second spline.

Claims (1)

(57) [Claims] 1. A power tool configured to rotate a tool by an electric motor, a tool 6 is mounted on one side, a load shaft 5 having a first spline 4 formed on the other side, and a shaft 1 of the motor. A first spline 11 fitted to the first spline 4 of the load shaft 5 and having an extending portion meshed with the first gear 2. The elastic member 8 is provided on the outer periphery of the side bulge 10.
Gear 3 having a third spline 9 fitted therein
And an elastic member 8 having one inner peripheral surface fitted to the first spline 4 of the load shaft 5 and the other inner peripheral surface fitted to the third spline 9 of the gear 3. Electric tool.