Hammer tool

Patent metadata

Field	Value
Publication number	US-10052747-B2
Application number	US-201314425186-A
Country	US
Kind code	B2
Filing date	Aug 30, 2013
Priority date	Sep 3, 2012
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

A hammer tool for hammering on a workpiece by a tool bit moving at least linearly in a longitudinal direction of the tool bit, configured so that a hammering element moves toward the tool bit to hits the tool bit by way of air pressure fluctuation in an air chamber when a driving element is moved from a first position to a second position. In addition, the stroke center position of the reciprocating movement of the driving element moved between the first position and the second position is configured to be changeable.

First claim

The invention claimed is:

1. A hammer tool which at least linearly drives a tool bit at least linearly in a longitudinal direction of the tool bit and performs a hammering operation on a workpiece, comprising:
a main body,
a cylinder which is arranged in the main body and extended in the longitudinal direction of the tool bit,
a hammering element which drives linearly in the longitudinal direction of the tool bit in the cylinder and hits the tool bit,
a driving element which is slidably arranged in the cylinder and is configured to move the hammering element, and
a driving apparatus which drives the driving element,
wherein the driving element is arranged inside the cylinder such that it reciprocally moves in the cylinder along the longitudinal axis of the cylinder between a first position at which the driving element is most remote from the tool bit and a second position at which the driving element is closest to the tool bit,
when the driving element is moved from the first position to the second position, the driving element moves the hammering element toward the tool bit and the hammering element hits the tool bit, and
wherein the reciprocal movement of the driving element has a stroke center position relative to the cylinder between the first position and the second position; and
wherein the driving element and driving apparatus are configured to change the stroke center position.

2. The hammer tool according to claim 1 , comprising a switch apparatus for changing the stroke center position.

3. The hammer tool according to claim 2 , wherein the switch apparatus is configured to be manually operable by a user.

4. The hammer tool according to claim 3 , wherein the switch apparatus comprises an operation member which is operable by a user and a movable member which is switched its position due to a movement of the operation member, and
the stroke center position is changed by switching the position of the movable member.

5. The hammer tool according to claim 2 , comprising a control apparatus which controls the switch apparatus,
wherein the control apparatus is configured to change the stroke center position by controlling the switch apparatus.

6. The hammer tool according to claim 5 , wherein the switch apparatus comprises a driving member which is driven by the control apparatus and a movable member which is switched its position due to a driving of the driving member, and
the stroke center position is changed by switching the position of the movable member.

7. The hammer tool according to claim 5 , comprising a first sensor which measures reaction force caused by the hammering operation of the tool bit,
wherein the control apparatus is configured to control the switch apparatus based on a measured result of the first sensor and change the stroke center position.

8. The hammer tool according to claim 5 , comprising a second sensor which measures position of the tool bit,
wherein the control apparatus is configured to control the switch apparatus based on a measured result of the second sensor and change the stroke center position.

9. The hammer tool according to claim 5 , comprising a third sensor which measures vibration caused on the main body,
wherein the control apparatus is configured to control the switch apparatus based on a measured result of the third sensor and change the stroke center position.

10. The hammer tool according to claim 5 , comprising a fourth sensor which measures the current to the motor,
wherein the control apparatus is configured to control the switch apparatus based on a measured result of the fourth sensor and change the stroke center position.

11. The hammer tool according to claim 1 , wherein the driving apparatus comprises a motor and a crank mechanism which is driven by the motor,
the crank mechanism comprises a crank shaft having an eccentric shaft, the crank shaft rotationally driven by the motor, and a swing member which is connected to the eccentric shaft swingably around the eccentric shaft,
the hammer tool further comprises a connecting member which connects the swing member and the driving element, one end side of the connecting member is swingably connected to the swing member and the other end side is swingably connected to the driving element, and a control member one end side of which is swingably connected to the swing member and the other end side of which is swingably connected to a support part arranged on the main body, and
the stroke center position is changed by changing a position of the support part.

12. The hammer tool according to claim 11 , comprising a switch apparatus for changing the stroke center position, a control apparatus which controls the switch apparatus, and a fifth sensor which measures load applied on the support part,
wherein the control apparatus is configured to control the switch apparatus based on a measurement result of the fifth sensor and change the stroke center position.

13. The hammer tool according to claim 11 , wherein a stroke length of a driving element is changed when the stroke center position is changed.

14. The hammer tool according to claim 1 , comprising a connection rod which is connected to the driving element, and a crank mechanism which is connected to the connection rod, the crank mechanism configured to drive the driving element,
wherein while the driving element is moved from a bottom dead center which is the most remote from the tool bit to a top dead center which is the closest to the tool bit, a straight line between a connecting part of the connection rod and the driving element and a connecting part of the connection rod and the crank mechanism is arranged to be parallel to the cylinder.

15. The hammer tool according to claim 14 , with respect to a crank angle of the crank mechanism, an angle corresponding to the bottom dead center is defined as 0 degree, and an angle corresponding to the top dead center is defined as 180 degrees, and when the crank mechanism moving from the bottom dead center to the top dead center of the piston is positioned at substantially 90 degrees crank angle position, the connection rod is to be parallel to the cylinder.

16. The hammer tool according to claim 14 , when the connection rod is parallel to the cylinder, the hammering element is configured to start to move toward the tool bit.

17. The hammer tool according to claim 14 , wherein a rotation center of the crank mechanism is arranged to be offset from a reciprocating moving line of the driving element moved inside the cylinder with respect to a direction crossing the reciprocating moving line.

18. The hammer tool according to claim 14 , wherein the crank mechanism comprises a rotatable crank shaft and an eccentric shaft connected to the crank shaft at a position eccentric from a rotational axis of the crank shaft,
the hammer tool further comprises a swing member which is interveningly arranged between the eccentric shaft and the connection rod and swingably connected to both of the eccentric shaft and the connection rod respectively, and a control member one end side of which is swingably supported on the main body and the other end side of which is swingably connected to the swing member.

19. The hammer tool according to claim 18 , wherein the distance the piston moves is larger than the distance the eccentric shaft moves in the direction of movement of the driving element.

20. The hammer tool according to claim 18 , comprising a first support part which connects the swing member and the connection

Assignees

• Makita Corp
• Makita Corp

Inventors

• Aoki Yonosuke

Classifications

• B25D11/125

  with a fluid cushion between the crank drive and the striking body · CPC title

• B25D2250/245

  Spatial arrangement of components of the tool relative to each other · CPC title

• B25D2250/021

  Stroke length · CPC title

• B25D2250/275

  Tools having at least two similar components · CPC title

• B25D11/005 Primary

  Arrangements for adjusting the stroke of the impulse member or for stopping the impact action when the tool is lifted from the working surface · CPC title