JPH0137906Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an impact tool that is compact and durable.

An impact tool for drilling into concrete or the like rotates a bit and applies a strong impact in the axial direction to crush hard materials such as concrete.

For this reason, although it is easy to rotate the bit with the impact tool, it is structurally difficult to apply an impact in the axial direction, and furthermore, due to the severe impact, durability has been a problem.

Moreover, the structure for generating such impact becomes larger in size and weight.
The tools I had on hand were tiring to use.

The structure that generates the impact in the axial direction uses the force of compressed air from a piston to reciprocate the impacting body.
It was common to be configured to strike the bit on the head.

The structure for operating the piston is as follows:
A method using a crank, and a method using an inclined plate or the like on a rotating shaft and utilizing swinging of the plate in the axial direction have been considered.

In either case, a crank rod is connected to the piston, but the end of the crank rod does not move only in the axial direction in which the piston operates, but because there is a process in which it tilts in the direction in which the piston operates, the piston Forces are generated between the cylinder and the sliding cylinder that cause unnecessary wear.

For this reason, the cylinder and piston of impact tools suffer from significant wear, and to improve durability, structural and material improvements have been made at the expense of weight and shape.

Such an impact tool is extremely disadvantageous not only when drilling holes in floors but also when drilling holes in ceilings because the operator must support the weight of the impact tool.

The present invention has been developed in view of the above circumstances, and an object of the present invention is to provide an impact tool that can be constructed to be small and lightweight, and yet has sufficient durability.

Hereinafter, the present invention will be explained based on an embodiment shown in the drawings. Fig. 1 is a vertical sectional view of the main part of the impact tool according to the invention, and Fig. 2 explains the principle of its operation. It is a diagram.

In FIG. 1, in the impact tool, a gear 2 for deceleration is meshed with an output shaft 1 of an electric motor, and a first eccentric shaft 3 is provided on the upper surface of this gear 2.

A second eccentric shaft 4 is provided which is rotatably supported on the first eccentric shaft 3, and the second eccentric shaft 4 is provided eccentrically with respect to the rotating portion supported on the first eccentric shaft 3. A piston 5 and a guide 6 are provided on the shaft.

Further, the guide 6 is fitted into a groove 7 formed linearly in the upper part, so that the piston 5 and the guide 6 are configured to move linearly.

The amount of eccentricity of the first eccentric shaft 3 and the amount of eccentricity of the second eccentric shaft 4 are set to the same amount of eccentricity.

Further, the piston 5 is fitted into a cylinder 8, and the cylinder 8 is provided with a striking body 9 that is operated by the reciprocating motion of the piston 5.
It is configured to strike a bit (not shown).

In FIG. 2, a line 10 is a locus of movement of the first eccentric shaft 3, and a line 11 is a point showing a locus of movement of the second eccentric shaft 4.

And the line 12 connects the piston 5 and the guide 6
This is the trajectory of the movement.

In such a configuration, when the shaft 1 of the electric motor rotates, the gear 2 rotates while being decelerated, and the first eccentric shaft 3 provided on the gear 2 moves along the trajectory shown by the line 10 in FIG. It will rotate.

As the first eccentric shaft 3 rotates, the portion of the second eccentric shaft 4 supported by the first eccentric shaft 3 is moved along the line 10.
However, since the eccentric shaft portion of the second eccentric shaft 4 is restrained by the linear groove 7 via the guide 6, circular movement is not possible.

Therefore, as the second eccentric shaft 4 rotates along the trajectory shown by the line 11, the piston 5 moves in a straight line as shown by the line 12.

Then, the piston 5 stops momentarily at both the top dead center and the bottom dead center of the piston in the process of forward movement and then return movement, but the piston 5 stops for a moment, but 4 is at a position 90 degrees from the travel line of piston 5, the dead center of the crank will occur, but the piston is traveling at a constant speed for forward or backward movement, and this dead center It never stops.

Therefore, the direction of movement of the piston does not change at the dead center of the crank formed by the first eccentric shaft and the second eccentric shaft, and the piston moves from this dead center to
It will pass depending on its running speed.

Therefore, the piston reciprocates by the sum of the first eccentric shaft, the second eccentric shaft, and the eccentricity.

Therefore, as a result, the piston 5 and the guide 6 are
This will result in a linear motion trajectory shown by line 12.

Such a linear motion of the piston 5 can obtain a large linear motion that is the sum of the eccentricity of the first eccentric shaft 3 and the eccentricity of the second eccentric shaft 4.

For example, if the amount of eccentricity of the first eccentric shaft 3 is 6 mm and the amount of eccentricity of the second eccentric shaft 4 is 6 mm, a linear motion of the piston 5 of 24 mm will be obtained.

Therefore, compared to the conventional system using a crank, the conversion mechanism from rotation to linear motion required to obtain the same linear movement distance of the piston is smaller.

In other words, when a piston is driven by a crank, the crank must be reciprocated by the same distance as the reciprocating distance of the piston, and the eccentric shaft that drives the crank must also be eccentric by a distance twice the eccentricity of the present invention. Therefore, it was unavoidable that the dimensions of the piston would increase in the direction of movement of the piston.

According to the structure of the present invention, since the amount of eccentricity between the first eccentric shaft 3 and the second eccentric shaft 4, which serve as the drive mechanism of the piston 5, is substantially halved in terms of motion, the piston 5
The impact tool can be made smaller in size in the direction of motion, and the impact tool can be made smaller and lighter.

In addition, since the piston 5 is linearly restrained by the guide 6, there is no negative effect on sliding with respect to the cylinder 8, and wear on the sliding parts can be reduced.
In addition to extending the service life, there is no friction loss and efficient operation can be expected.

Furthermore, when the wear characteristics of the piston 5 and the like are improved, deterioration of lubricating oil necessary for sliding parts and mixing of wear particles can be avoided, and the effect that long-term repairs are no longer required can be obtained.

As explained above, according to the present invention, since the piston is driven linearly by the first eccentric shaft and the second eccentric shaft, it is possible to make a large linear movement of the piston with a drive mechanism with a small amount of eccentricity. In addition, unnecessary forces that differ from the direction of movement are not applied to sliding parts such as pistons, which improves wear resistance and improves efficiency. It also has a longer service life, eliminating the need for long-term repairs and inspections. In addition, since it can be configured to be compact and lightweight, its utility value as a portable tool can be improved, and its practicality is
It is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a main part of the impact tool according to the present invention, and FIG. 2 is a diagram illustrating the principle of its operation. 3...First eccentric shaft, 4...Second eccentric shaft, 5...
Piston, 6...guide, 7...groove, 8...cylinder.

Claims (1)

[Scope of utility model registration request] A first eccentric shaft driven by an electric motor, a second eccentric shaft supported by the first eccentric shaft, and the first eccentric shaft and the second eccentric shaft having the same eccentricity, and An impact tool comprising: a piston supported on an eccentric shaft and restrained to travel in a straight line.