초록 ▼

It is an object of the invention to provide a technique for further improving the vibration reducing performance in a power impact tool that linearly drives a tool bit by using a swinging mechanism. According to the invention, a representative power impact tool is provided with a motor, a rotating

It is an object of the invention to provide a technique for further improving the vibration reducing performance in a power impact tool that linearly drives a tool bit by using a swinging mechanism. According to the invention, a representative power impact tool is provided with a motor, a rotating shaft, a swinging member, a tool driving mechanism and a counter weight. The swinging member is supported by the rotating shaft to swing in the axial direction of the rotating shaft by rotation of the rotating shaft. The counter weight is disposed in a region higher than a lower end region of the swinging member in the vertical direction to intersect with the axis of the rotating shaft, and a lower end of the counter weight is connected to the lower end region of the swinging member. The counter weight extends upward from the connection between the counter weight and the swinging member and has a pivot point in the extending end portion, and when the swinging member swings, the counter weight is driven by the swinging member to rotate in the axial direction of the tool bit, thereby reducing vibration caused in the axial direction of the tool bit.

대표청구항 ▼

What we claim is: 1. A power impact tool to perform a predetermined operation on a workpiece by using a striking movement of a tool bit in its axial direction comprising: a motor, a rotating shaft that is disposed substantially parallel to the axial direction of the tool bit and rotationally driven

What we claim is: 1. A power impact tool to perform a predetermined operation on a workpiece by using a striking movement of a tool bit in its axial direction comprising: a motor, a rotating shaft that is disposed substantially parallel to the axial direction of the tool bit and rotationally driven by the motor, a swinging member that is supported by the rotating shaft to swing in the axial direction of the rotating shaft by rotation of the rotating shaft, the swinging member having an upper end region and a lower end region, as viewed in the axial direction of the tool bit, the upper end region extending in a direction substantially perpendicular to the axial direction of the rotating shaft, a tool driving mechanism that is connected to the upper end region of the swinging member, the tool driving mechanism linearly moving in the axial direction of the tool bit by the swinging movement of the swinging member to linearly drive the tool bit, and a counter weight that reduces vibration caused in the axial direction of the tool bit during the operation of the power impact tool, wherein: the counter weight is disposed in a region higher than the lower end region of the swinging member, as viewed from the axial direction of the tool bit, and a lower end of the counter weight is connected to the lower end region of the swinging member and the counter weight extends upward from the connection between the counter weight and the swinging member and has a pivot point in an extending end portion, and when the swinging member swings, the counter weight is driven by the swinging member to pivot about the pivot point in the axial direction of the tool bit, thereby reducing vibration caused in the axial direction of the tool bit. 2. The power impact tool as defined in claim 1, wherein the pivot point is disposed at a position above the axis of the tool bit in the direction substantially perpendicular to the axial direction of the rotating shaft. 3. The power impact tool as defined in claim 1, wherein the counter weight includes a connecting part connected to the swinging member and extending upward and a weight part defining a vibration reducing weight, the connecting part and the weight part being provided as separate members and thereafter integrally formed with each other. 4. The power impact tool as defined in claim 1, wherein: the counter weight includes a connecting part connected to the swinging member and extending upward and a weight part defining a vibration reducing weight, the connecting part and the weight part being provided as separate members and thereafter integrally formed with each other, the connecting part includes a right arm and a left arm with respect to a longitudinal axis of the tool, the right and left arms respectively extending upward from the lower end connected to the swinging member and past the side of the swinging member, a lateral distance between the extending end portions of the arms is provided as changeable by using elastic deformation of the arms, the pivot point includes a stem that extends in a direction that intersects with the extending direction of the arms and a hole that is fitted onto the stem for relative rotation, and one of the stem and the hole is formed in the extending end portion of each of the arms, and the stem and the hole are engaged with each other by utilizing a movement of changing the distance between the arms by deformation of the arms. 5. The power impact tool as defined in claim 1 further comprising a dynamic vibration reducer that reduces vibration caused during the operation of the tool bit, the dynamic vibration reducer including a weight that is allowed to reciprocate in the axial direction of the tool bit with a biasing force of an elastic element being applied to the weight, wherein the counter weight drives the weight of the dynamic vibration reducer via the elastic element when the counter weight rotates. 6. The power impact tool as defined in claim 1, wherein the counter weight is substantially U-shaped having an open top, as viewed from the axial direction of the tool bit, and the counter weight is disposed on an outside of the swinging member in such a manner as to cover the swinging member. 7. The power impact tool as defined in claim 1, wherein the counter weight is substantially U-shaped having an open top, as viewed from the axial direction of the tool bit, and the counter weight is disposed on an outside of the swinging member in such a manner as to cover the swinging member, and wherein a weight concentration part for concentrating the weight is provided generally in a middle of the counter weight in the direction substantially perpendicular to the axial direction of the rotating shaft. 8. The power impact tool as defined in claim 1, wherein the counter weight is substantially U-shaped having an open top, as viewed from the axial direction of the tool bit, and the counter weight is disposed on an outside of the swinging member in such a manner as to cover the swinging member, and wherein the counter weight and the swinging member are connected to each other via a protrusion formed on one of the counter weight and the swinging member and an engagement hole formed on the other of the counter weight and the swinging member, the protrusion being loosely engaged in the engagement hole for free relative movement. 9. The power impact tool as defined in claim 1, wherein: the counter weight includes a connecting part connected to the swinging member and extending upward and a weight part defining a vibration reducing weight, the connecting part and the weight part being provided as separate members and thereafter integrally formed with each other, and the connecting part is formed by sheet metal that is bent substantially into a U shape having an open top, as viewed from the axial direction of the tool bit. 10. A power impact tool to perform a predetermined operation on a workpiece by using a striking movement of a tool bit in its axial direction comprising: a motor, a rotating shaft that is disposed substantially parallel to the axial direction of the tool bit and rotationally driven by the motor, a swinging member that is supported by the rotating shaft to swing in the axial direction of the rotating shaft by rotation of the rotating shaft, the swinging member having an upper end region and a lower end region, as viewed in the axial direction of the tool bit, the upper end region extending in a direction substantially perpendicular to the axial direction of the rotating shaft, a tool driving mechanism that is connected to the upper end region of the swinging member, the tool driving mechanism linearly moving in the axial direction of the tool bit by the swinging movement of the swinging member to linearly drive the tool bit, and a counter weight that reduces vibration caused in the axial direction of the tool bit during the operation of the power impact tool, wherein: the counter weight is disposed in a region higher than the lower end region of the swinging member, as viewed in the axial direction of the tool bit, and a lower end of the counter weight is connected to the lower end region of the swinging member, the counter weight extends upward from the connection between the counter weight and the swinging member and has a pivot point in an extending end portion, and when the swinging member swings, the counter weight is driven by the swinging member to pivot about the pivot point in the axial direction of the tool bit, thereby reducing vibration caused in the axial direction of the tool bit, and the counter weight includes a connecting part connected to the swinging member and extending upward and a weight part defining a vibration reducing weight, the connecting part and the weight part being provided as separate members and thereafter integrally formed with each other. 11. A power impact tool to perform a predetermined operation on a workpiece by using a striking movement of a tool bit in its axial direction comprising: a motor, a rotating shaft that is disposed substantially parallel to the axial direction of the tool bit and rotationally driven by the motor, a swinging member that is supported by the rotating shaft to swing in the axial direction of the rotating shaft by rotation of the rotating shaft, the swinging member having an upper end region and a lower end region, as viewed in the axial direction of the tool bit, the upper end region extending in a direction substantially perpendicular to the axial direction of the rotating shaft, a tool driving mechanism that is connected to the upper end region of the swinging member, the tool driving mechanism linearly moving in the axial direction of the tool bit by the swinging movement of the swinging member to linearly drive the tool bit, and a counter weight that reduces vibration caused in the axial direction of the tool bit during the operation of the power impact tool, wherein: the counter weight is disposed in a region higher than the lower end region of the swinging member, as viewed in the axial direction of the tool bit, and a lower end of the counter weight is connected to the lower end region of the swinging member, the counter weight extends upward from the connection between the counter weight and the swinging member and has a pivot point in an extending end portion, and when the swinging member swings, the counter weight is driven by the swinging member to pivot about the pivot point in the axial direction of the tool bit, thereby reducing vibration caused in the axial direction of the tool bit, and the counter weight includes a connecting part connected to the swinging member and extending upward and a weight part defining a vibration reducing weight, the connecting part and the weight part being provided as separate members and thereafter integrally formed with each other, the connecting part includes a right arm and a left arm with respect to a longitudinal axis of the tool, the right and left arms respectively extending upward from the lower end connected to the swinging member and past the side of the swinging member, a lateral distance between the extending end portions of the arms is provided as changeable by using elastic deformation of the arms, the pivot point includes a stem that extends in a direction that intersects with the extending direction of the arms and a hole that is fitted onto the stem for relative rotation, and one of the stem and the hole is formed in the extending end portion of each of the arms, and the stem and the hole are engaged with each other by utilizing a movement of changing the distance between the arms by deformation of the arms.