초록 ▼

It is an object of the invention to provide a technique that contributes to rationalization of a mechanism relating to reduction of vibration in an impact tool. Representative impact tool includes a tool body, a hammer actuating member, a dynamic vibration reducer and a positioning elastic element.

It is an object of the invention to provide a technique that contributes to rationalization of a mechanism relating to reduction of vibration in an impact tool. Representative impact tool includes a tool body, a hammer actuating member, a dynamic vibration reducer and a positioning elastic element. The positioning elastic element contacts the hammer actuating member and thereby positions the tool body with respect to the workpiece so as to absorb a reaction force caused by rebound from the workpiece and acts on the hammer actuating member when the hammer actuating member performs the hammering operation on the workpiece. The positioning elastic element includes the elastic element formed as a component part of the dynamic vibration reducer.

대표청구항 ▼

1. An impact tool which performs a predetermined hammering operation on a workpiece by a striking movement of a hammer actuating member in its axial direction, including: a tool body,a cylinder housed within the tool body,a driving element that linearly moves in the axial direction of the hammer act

1. An impact tool which performs a predetermined hammering operation on a workpiece by a striking movement of a hammer actuating member in its axial direction, including: a tool body,a cylinder housed within the tool body,a driving element that linearly moves in the axial direction of the hammer actuating member,a striker that linearly moves in the axial direction of the hammer actuating member within the cylinder, andan air chamber defined between the driving element and the striker within the cylinder, wherein the striker is caused to linearly move via pressure fluctuations of the air chamber as a result of the linear movement of the driving element and strikes the hammer actuating member, whereby the predetermined hammering operation is performed on the workpiece, comprising:a positioning member that is held in contact with the hammer actuating member under loaded conditions in which the hammer actuating member is pressed against the workpiece and pushed towards the driving element, while being separated from the hammer actuating member under unloaded conditions in which the hammer actuating member is not pressed against the workpiece,an elastically deformable positioning elastic element that positions the tool body with respect to the workpiece by contact with the positioning member under loaded conditions, and in this position, absorbs a reaction force that is caused by rebound from the workpiece and inputted from the hammer actuating member via the positioning member, the elastically deformable positioning elastic element being positioned outside the cylinder,a communication part that provides communication between the air chamber and the outside in order to prevent idle driving, anda communication part opening-closing member comprising the striker disposed inside the cylinder, the communication part opening-closing member being movable between a closed position for closing the communication part and an open position for opening the communication part, wherein, under unloaded conditions, the communication part opening-closing member is placed in the open position for opening the communication part and thereby disables the pressure fluctuations of the air chamber, while, under loaded conditions, the communication part opening-closing member is pushed by the hammer actuating member or the positioning member to the closed position for closing the communication part and thereby enables the pressure fluctuations of the air chamber. 2. The impact tool as defined in claim 1, further comprising an elastic member that biases the positioning member forward away from the striker. 3. The impact tool as defined in claim 2, wherein the positioning elastic element and the elastic member are arranged in parallel in the radial direction and in the same position on the axis of the hammer actuating member. 4. The impact tool as defined in claim 1, further comprising a dynamic vibration reducer having a weight that can linearly move under a biasing force of an elastic element and provided to reduce vibration during hammering operation by the movement of the weight in the axial direction of the hammer actuating member. 5. The impact tool as defined in claim 4, wherein the positioning elastic element comprises the elastic element designed as a component part of the dynamic vibration reducer. 6. The impact tool as defined in claim 1, wherein: the positioning member comprises an annular member that is disposed on the hammer actuating member and can contact an outside portion of the hammer actuating member from the rear,a facing member faces the positioning member with a predetermined clearance therebetween and is disposed rearward of the positioning member in the tool body in such a manner as to be prevented from moving rearward, andthe positioning elastic element comprises a coil spring disposed between the positioning member and the facing member. 7. The impact tool as defined in claim 6, wherein an axial front region of the coil spring is placed over an outside portion of the positioning member and wherein a front end of the coil spring is held in contact with the positioning member and located forward of a contact point between the hammer actuating member and the positioning member. 8. The impact tool as defined in claim 6, wherein a stopper is provided on one of the positioning member and the facing member and elastically deforms by contact with the other of the positioning member and the facing member before coils of the coil spring come into close contact when the reaction force is absorbed by compressive deformation of the coil spring.