초록 ▼

It is an object of the present invention to provide a power tool having a further improved vibration reducing performance. The representative power tool may comprise a tool bit, an actuating mechanism, a dynamic vibration reducer. The actuating mechanism drives the tool bit linearly by means of pres

It is an object of the present invention to provide a power tool having a further improved vibration reducing performance. The representative power tool may comprise a tool bit, an actuating mechanism, a dynamic vibration reducer. The actuating mechanism drives the tool bit linearly by means of pressure fluctuations so as to cause the tool bit to perform a predetermined operation. The dynamic vibration reducer has a weight that reciprocates under a biasing force of an elastic element to reduce vibration of the actuating mechanism. The weight may be driven by means of pressure fluctuations caused in the actuating mechanism. According to the invention, the weight of the dynamic vibration reducer can be actively driven by pressure fluctuations in the actuating mechanism for driving the tool bit. Therefore, regardless of the magnitude of vibration acting on the power tool, the dynamic vibration reducer can be forcedly and steadily operated.

대표청구항 ▼

The invention claimed is: 1. A power tool, comprising: a tool bit; a tool body to which the tool bit is coupled; an actuating mechanism disposed in the tool body to drive the tool bit linearly by means of pressure fluctuations so as to cause the tool bit to perform a predetermined operation, wherei

The invention claimed is: 1. A power tool, comprising: a tool bit; a tool body to which the tool bit is coupled; an actuating mechanism disposed in the tool body to drive the tool bit linearly by means of pressure fluctuations so as to cause the tool bit to perform a predetermined operation, wherein the actuating mechanism has a driving motor, a motion converting mechanism that converts a rotating output of the driving motor to a linear motion, a piston linearly reciprocating in a longitudinal direction of the tool bit via the motion converting mechanism, a striker disposed in front of the piston to cause the tool bit a linear motion, a first chamber between the striker and the piston, and a second chamber disposed adjacent to the piston within the tool body in an side of the first chamber; and a dynamic vibration reducer having a weight that reciprocates under a biasing force of an elastic element to reduce vibration of the actuating mechanism, the weight being driven by means of pressure fluctuations caused in the second chamber when the piston reciprocates, wherein the motion converting mechanism comprises a crank mechanism that drives the striker by converting a rotating output of the driving motor to a linear motion in an axial direction of the tool bit, and the second chamber is defined by a crank chamber that houses the crank mechanism. 2. The power tool as defined in claim 1, wherein, under loaded driving conditions, in which a load associated with the predetermined power tool operation is applied to the tool bit, the weight is allowed to be driven by means of fluctuating pressure developed in the second chamber, while, under unloaded driving conditions, in which a load associated with the predetermined power tool operation is not applied to the tool bit, the weight is prevented from being driven by means of fluctuating pressure developed in the second chamber. 3. The power tool as defined in claim 1, wherein, under loaded driving conditions, in which a load associated with the predetermined power tool operation is applied to the tool bit, the weight is allowed to be driven by means of fluctuating pressure developed in the second chamber, while, under unloaded driving conditions, in which a load associated with the predetermined power tool operation is not applied to the tool bit, the weight is prevented from being driven by means of fluctuating pressure developed in the second chamber and, wherein the dynamic vibration reducer includes a first actuating chamber and a second actuating chamber that are defined on opposite sides of the weight within the body, and wherein, at least under the loaded driving conditions, the fluctuating pressure developed in the second chamber is introduced into the first actuating chamber, and the second actuating chamber can communicate with the outside. 4. The power tool as defined in claim 1, wherein, under loaded driving conditions, in which a load associated with the predetermined power tool operation is applied to the tool bit, the weight is allowed to be driven by means of fluctuating pressure developed in the second chamber, while, under unloaded driving conditions, in which a load associated with the predetermined power tool operation is not applied to the tool bit, the weight is prevented from being driven by means of fluctuating pressure developed in the second chamber and the fluctuating pressure developed in the second chamber is released to the outside of the power tool under the unloaded driving conditions by communicating the second chamber to the outside. 5. The power tool as defined in claim 1, wherein the tool bit comprises a hammer bit that performs a predetermined hammer operation by applying a linear impact force to a work piece. 6. The power tool as defined in claim 1, wherein the actuating mechanism includes a piston and a cylinder that slide relative to each other in an axial direction of the tool bit, wherein the tool bit reciprocates in its axial direction by the action of an air spring which is caused by relative movement of the piston and the cylinder, and wherein the weight is disposed along a circumferential surface of the cylinder and can slide in the axial direction of the tool bit. 7. A power tool comprising: a tool body; a tool holder; a tool bit coupled to the tool holder; an actuating mechanism disposed in the tool body to drive the tool bit linearly by means of pressure fluctuations so as to cause the tool bit to perform a predetermined operation, wherein the actuating mechanism has a driving motor, a motion converting mechanism that converts a rotating output of the driving motor to a linear motion, a piston linearly reciprocating in a longitudinal direction of the tool bit via the motion converting mechanism, a striker disposed in front of the piston to cause the tool bit a linear motion, a first chamber between the striker and the piston, and a second chamber disposed adjacent to the piston within the tool body in an opposite side of the first chamber; a dynamic vibration reducer having a weight that reciprocates under a biasing force of an elastic element to reduce vibration of the actuating mechanism, the weight being driven by means of pressure fluctuations caused in the second chamber when the piston reciprocates; and a cylinder that houses the striker such that the striker slidingly reciprocates within the cylinder, wherein the cylinder moves between a first position near the tool holder and a second position remote from the tool holder than the first position, and under loaded driving conditions in which a load associated with the predetermined operation is applied to the tool bit, the cylinder moves to the second position so as to allow the weight to be driven by means of fluctuating pressure within the second chamber, while, under unloaded driving conditions in which a load associated with the predetermined operation is not applied to the tool bit, the cylinder moves to the first position so as to prevent the weight from being driven by means of fluctuating pressure within the second chamber. 8. The power tool as defined in claim 7, wherein under the loaded driving conditions, the cylinder moves to the second position so as to allow the striker to be driven by the action of the air spring function of the first chamber, while, under unloaded driving conditions, the cylinder moves to the first position, so as to prevent the striker from being driven by the action of the air spring function of the first chamber. 9. The power tool as defined in claim 8, wherein under the loaded driving conditions, the weight is allowed to be driven by fluctuating pressure within the second chamber after the striker is allowed to be driven by the action of the air spring function of the first chamber. 10. The power tool as defined in claim 7, further comprising an air vent that can communicate the second chamber with the outside, wherein when the cylinder moves to the second position, the air vent is closed so as to allow the weight to be driven, and when the cylinder moves to the first position, the air vent is opened so as to prevent the weight to be driven. 11. The power tool as defined in claim 7, further comprising an air vent that can communicate the first chamber with the outside, wherein the air vent is closed when the cylinder moves to the second position and the air vent is opened when the cylinder moves to the first position.