Motor driven hammer having means for controlling the power of impact

Patent metadata

Field	Value
Publication number	US-9463562-B2
Application number	US-83663510-A
Country	US
Kind code	B2
Filing date	Jul 15, 2010
Priority date	Jul 15, 2009
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

A motor driven hammer having a housing, a motor having a motor shaft and being arranged in the housing, a hammer mechanism including a cylinder in which a ram is arranged the ram being slidable along a longitudinal axis (L) of the cylinder, and a tool holder which may support a tool bit so that the tool bit is aligned with the longitudinal axis of the cylinder, wherein the motor is coupled with the hammer mechanism, so that rotation of the motor shaft results in a reciprocating movement of the ram within the cylinder, the ram applying impacts on a tool bit supported by the tool holder during the reciprocating movement. Further, the ram is made of a paramagnetic or ferromagnetic material or comprises a permanent magnet and a coil is arranged within the housing adjacent to the cylinder so that the coil applies a force in the direction of the longitudinal axis on the ram if a current is applied to the coil.

First claim

The invention claimed is:

1. Motor driven hammer comprising: a housing, a motor having a motor shaft and being arranged in the housing, a hammer mechanism including a cylinder in which a ram is arranged, the ram being slidable along a longitudinal axis of the cylinder and a tool holder which may support a tool bit so that the tool bit is aligned with the longitudinal axis of the cylinder, wherein the motor is coupled with the hammer mechanism, so that rotation of the motor shaft results in a reciprocating movement of the ram within the cylinder, the ram applying impacts on a tool bit supported by the tool holder during the reciprocating movement wherein, the ram is made at least partially of a paramagnetic material, a ferromagnetic material or a permanent magnet material, a coil arranged within the housing adjacent to the cylinder, a control unit connected with the coil, and wherein the control unit is adapted to apply a current to the coil so that the coil applies a force to the ram in the direction of the longitudinal axis of the cylinder during the reciprocating movement of the ram.

2. The motor driven hammer of claim 1 , wherein at least a portion of the cylinder is formed at least partially of a non-magnetic material.

3. The driven hammer of claim 1 , wherein the ram has a forefront position within the cylinder, in which position the ram is closest to the tool holder with respect to the longitudinal direction and wherein, with respect to the longitudinal axis, at least a portion of the coil is arranged between the forefront position and the tool holder.

4. The motor driven hammer of claim 1 , wherein the ram has a forefront position within the cylinder, in which position the ram is closest to the tool holder with respect to the longitudinal direction and wherein, with respect to the longitudinal axis, the ram in its forefront position is located at least partially between the coil and the tool holder.

5. The motor driven hammer of claim 4 , wherein the hammer mechanism comprises a piston, which is guided within the cylinder, wherein the piston is coupled with the motor in such a way that the piston reciprocates upon rotation of the motor shaft and wherein an air cushion is provided between the piston and the ram.

6. The motor driven hammer of claim 5 , wherein the current depends on the position of the piston within the cylinder.

7. The motor driven hammer of claim 6 , further including a sensor for sensing at least one of a position, velocity, and acceleration of at least one of the piston and the ram.

8. The motor driven hammer of claim 7 , wherein the control unit receives a signal from the sensor and a current is applied to the coil depending on the signal.

9. The motor driven hammer of claim 5 , wherein the control unit is adapted to apply a current to the coil depending on the rotational speed of the motor.

10. The motor driven hammer of claim 5 , wherein the control unit is adapted to apply a current to the coil depending on the rotational speed of the motor and the and the position of the piston within the cylinder.

11. The motor driven hammer of claim 1 , wherein the longitudinal position of the coil is adjustable.

12. Motor driven hammer comprising: a housing, a motor having a motor shaft and being arranged in the housing, a hammer mechanism including a cylinder in which a ram is arranged, the ram being slidable along a longitudinal axis of the cylinder and a tool holder which may support a tool bit so that the tool bit is aligned with the longitudinal axis of the cylinder, wherein the motor is coupled with the hammer mechanism, so that rotation of the motor shaft results in a reciprocating movement of the ram within the cylinder, the ram applying impacts on a tool bit supported by the tool holder during the reciprocating movement wherein, the ram is made at least partially of a paramagnetic material, a ferromagnetic material or a permanent magnet material, a coil arranged within the housing adjacent to the cylinder, a control unit connected with the coil, and wherein the control unit is adapted to apply a current to the coil so that the coil applies a force to the ram toward the tool holder during the reciprocating movement of the ram.

Assignees

• Gumpert Rene
• Faatz Heinz-Werner
• Black & Decker Inc

Inventors

• Gumpert Rene
• Faatz Heinz-Werner

Classifications

• B25D2217/0023

  Pistons · CPC title

• B25D2250/025

  Auxiliary percussive devices · CPC title

• B25D11/005

  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

• B25D2211/003

  Crossed drill and motor spindles · CPC title

• B25D11/125

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