JPH0144473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for preventing a striking operation of a striking tool, such as an electric hammer, having a striking element driven by an air spring during idle rotation.

In the conventional case, in order to prevent the hitting operation during idle rotation (hereinafter referred to as idle hitting), the position of the hitting axis was changed,
When the striking element reaches the non-striking position, the air between the striking element and the piston can enter and exit through an air vent hole provided in the cylinder, thereby eliminating the suction force of the piston. However, in this case, when working upward, the striker falls down under its own weight and closes the air vent hole, so it is easy to strike blankly. Due to dry firing, the impact tool body receives impact force, which may cause damage.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art by utilizing pneumatic pressure, and to improve operability and service life.

The present invention focuses on the fact that an auxiliary air chamber is formed between the striker of the cylinder part, the tool holding sleeve, and the striking shaft, and uses the initial striking element forward energy when the striking tool shifts to the idling state. When the air in the auxiliary air chamber is compressed and a pressure above a certain level is generated, a check valve attached to the auxiliary air chamber is opened and the air flows out, and when the striking element retreats, the air pressure becomes negative pressure. As a result, the backward movement of the striking element can be prevented, thereby preventing dry firing. Furthermore, in order to achieve the above effect, a accumulated air chamber is provided in a part of the circumference of the striker, and the auxiliary air chamber and the accumulated air chamber are communicated, and the striker is moved into a cylinder by the pressure until the check valve is opened. It is pressed against a wall to consume the forward energy of the striker.

In FIG. 1, the rotational force of the electric motor section 1 is
Crankshaft 3 is rotated through gear 2. The rotation of the crankshaft is controlled by connecting rod 4.
This is converted into a reciprocating motion of the piston 6 by the piston pin 5. Between the cylinder 7, the striker 8 and the piston 6, there is a main air chamber 9 which is substantially sealed.
The reciprocating movement of the piston allows the main air chamber 9 to
The pressure of the internal air fluctuates, and this pressure causes the striking element 8 to perform a striking movement with respect to the striking shaft 10. The striking shaft 10 is inserted and held in the tool holding sleeve 11 and transmits the striking force of the striking element 8 to the tool 12 held in the tool holding sleeve 11. The tool holding sleeve 11 is fitted into the cylinder 7 so as to be non-rotatable and limitedly movable in the axial direction.
A coil spring 15 is installed between the cylinder cap 13 and the grip 14, and pushes the grip 14 forward. This pressing force acts to move the tool holding sleeve 11 forward through the cap 16. The first gear 2 also meshes with the second gear 17 and rotates the cylinder 7, the tool holding sleeve 11, and the tool 12 through the bevel pinion 18 and the bevel gear 19. The cylinder 7 is provided with an air hole 20 through which air enters and exits during normal impact, and further in front is a valve hole 23 that forms a check valve 22 together with a ring-shaped elastic body 21 that covers the outer periphery of the cylinder 7. It is provided.

FIG. 2 shows a normal striking state, in which the tool holding sleeve 11 is at approximately the full rearward position. At this time, the striking element 8, cylinder 7, and striking shaft 1
The auxiliary air chamber 24 formed by being surrounded by the cylinder 7 and the tool holding sleeve 11 and the accumulated air chamber 25 formed in a part of the circumference of the cylinder 7 and the striking element 8 are formed by the passage 26 and the air hole 20. Since it communicates with the outside and air enters and exits as the striking element 8 moves, no force is exerted to prevent the striking element 8 from moving.
When shifting from the normal striking state to idle rotation, the tool holding sleeve 11 moves almost fully forward as shown in FIG. 3, and the valve hole 23 opens to the auxiliary air chamber 24. On the other hand, the striker 8 is still in motion and moves forward. When the striker 8 advances to a predetermined position, the air hole 20 is closed by the striker 8,
The auxiliary air chamber 24 and the accumulated air chamber 25 are sealed, and when the striker 8 moves forward, the air in the auxiliary air chamber 24 and the accumulated air chamber 25 is compressed. This pressure causes the striking element 8 to move forward while being pressed against the cylinder 7. As it moves further forward, the elastic body 21 blocking the valve hole 23 is deformed and is discharged to the outside of the cylinder 7, as shown by the arrow in FIG. 3, for example.
When the forward movement of the striker 8 stops and the retreat begins, the auxiliary air chamber 24 and the accumulated air chamber 25 become under negative pressure with respect to the main air chamber 9 due to the action of the check valve 22, so that the striker 8 stops moving back. Movement is prevented, and the striking element 8 is connected to the striking axis 1.
Since it is held near the 0 end face, blank firing does not occur. Return to the striking state is achieved by pressing the tip of the tool against the workpiece and returning the tool holding sleeve 11 to the position shown in FIG.

(1) The check valve 22 may have any structure. If it opens only in the outflow direction,
You can get the same effect.

(2) The valve hole 23 may be open to the auxiliary air chamber from the beginning. However, the auxiliary air chamber must be constructed so that the volume when the striking element hits the striking shaft in the idling position is sufficiently small.

(3) The tool holding sleeve may be integral with the striking shaft.

(4) The passage 26 does not need to be provided in the striking element. For example, the same effect can be obtained with a cylinder.

According to the present invention, since the striking element can be held at a predetermined position, it is possible to prevent a striking action from occurring during idle rotation.

[Brief explanation of drawings]

Fig. 1 is a partially longitudinal side view showing an embodiment of the impact tool of the present invention, Fig. 2 is a partially longitudinal side view showing the surrounding state of the auxiliary air chamber during normal impact, and Fig. 3 is the idling tool. FIG. 4 is a sectional view taken along line A--A in FIG. 3, and FIG. 5 is a sectional view taken along line B--B in FIG. In the figure, 7 is a cylinder, 8 is a striker, and 10
1 is a striking shaft, 11 is a tool holding sleeve, 21 is an elastic body, 22 is a check valve, 23 is a valve hole, 24 is an auxiliary air chamber, 25 is a reservoir chamber, and 26 is a passage.

Claims (1)

[Claims] 1. A tool comprising a tool holding sleeve into which a striking shaft is inserted and held, a cylinder housing a striking element for striking the striking shaft, and a driving device for driving the striking element, wherein the striking element is When approaching the tool holding sleeve within a predetermined range, the striking shaft, the tool holding sleeve, the cylinder,
and communicates an auxiliary air chamber surrounded by the striking element with a reservoir chamber surrounded by the cylinder and a circumferential partial recess provided in the striking element; A striking tool in which an auxiliary air chamber is provided with a check valve that operates only in the direction in which air flows out from the auxiliary air chamber.