JPH0422938Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a device for preventing the striking action of a striking tool, such as an electric hammer, which has a striking element driven by an air spring when it is idling. be.

[Background of the idea]

Conventionally, in order to prevent the hitting operation when the ball is in the air (hereinafter referred to as "dry hitting"), the position of the intermediate element is changed, and when the hitting element comes to the non-striking element position, the air between the hitting element and the piston is created in the cylinder. It has a structure that allows it to go in and out through the air vent hole, which eliminates the absorption force of the piston. However, depending on the tip tool, the speed at which the striking element hits the intermediate element and bounces back is fast, and the time that the air vent hole is open is short. In some cases, prevention was insufficient.

[Purpose of invention]

The purpose of the present invention is to improve the above-mentioned drawbacks of the prior art without compromising the size of the aircraft and the impact force.

[Summary of the idea]

The striking force is approximately determined by the volume of the air chamber covered by the cylinder, piston end face, and striker end face. On the other hand, dry firing prevention comes into effect when the seal of the air chamber is opened at the air vent hole. In the prior art, the air vent hole was sealed even at the brim of the striker because the fitting gap between the inner diameter of the cylinder and the outer diameter of the striker was small. In the present invention, the brim portion of the striking element is made smaller in diameter than the guide portion to eliminate a sealed state, and the air vent hole is opened for a longer period of time, thereby increasing the effect of preventing dry firing.

[Example of idea]

The present invention will be explained below with reference to illustrated embodiments. The power of the electric motor is converted into linear reciprocating motion of the piston 4 by a crankshaft (not shown) and the connecting rod 2. The reciprocating motion of the piston 4 is transmitted to the striking element 6 by an air spring between the piston 4 and the striking element 6, and the striking element 6 strikes the intermediate element 7. Intermediate 7
strikes the tip tool 8 which is in contact with the meson 7. When the tip tool 8 separates from the work material such as concrete, the tip tool 8 moves forward until it hits the stop lever 9. The intermediate element 7 and the striking element 6 also move forward by approximately the same dimension. At this time, the O-ring 11 of the striker 6 passes through the air vent hole 10 of the cylinder 5, the air chamber 12 is opened, the suction force of the piston 4 disappears, and the movement of the striker 6 stops. Here, the outer diameter of the collar portion 13 of the striker 6 is configured to be smaller than the outer diameter of the guide portion 14 to a size that allows air to enter and exit.

In the present invention, the outer diameter of the brim of the striker 6 is made smaller than the outer diameter of the guide part, but the same effect can be obtained even if the brim is provided with an air vent hole or groove.

[Effect of idea]

According to the present invention, the opening time of the air vent hole is increased by twice the distance of the striker collar, without changing the volume of the air chamber or the amount of advance of the tip tool, thereby preventing dry striking. The effect increases. Also, the impact force and size of the aircraft remain unchanged.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing only the main parts of one embodiment of the present invention. FIG. 2 is a longitudinal sectional side view of the tool in a state where the tool tip is advanced to prevent blank firing. In the figure, 4 is a piston, 6 is a striker, 8 is a tip tool, 11 is an O-ring, 12 is an air chamber, 13
14 is a flange portion and a guide portion.

Claims (1)

[Scope of utility model registration request] A striking tool that includes a striking element driven by the reciprocating movement of a piston and air pressure in a cylinder and provides a striking action to the tip tool, wherein the striking element is formed with guide portions at both ends thereof to connect with the inner diameter of the cylinder; A sealing elastic body is disposed in the guide part on the piston side, and the outside diameter of the collar between the piston side end face and the elastic body is formed to be smaller than the outside diameter of the guide part, so that when the tip tool moves forward, A dry firing prevention device configured to extend the opening time of an air chamber.