# US 8,739,896 B2 · Percussion device

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- Number: US 8,739,896 B2
- Document ID: US8739896B2
- Status: Granted
- Kind: B2
- Application number: 11/663,016
- Filed: 2005-09-28
- Published: 2007-12-06
- Granted: 2014-06-03
- Earliest claimed: 2004-10-14
- Assignees: Atlas Copco Rock Drills AB
- Applicants: Kurt Andersson; Jörgen Rodert
- Inventors: Kurt Andersson; Jörgen Rodert
- Web page: https://patentgrep.com/patent/US8739896B2

## CPC

- B25D 9/14: Control devices for the reciprocating piston
- B25D 9/18: involving a piston-type slide valve
- B25D 9/20: involving a tubular-type slide valve
- B25D 2209/007: having a tubular-slide valve, which is not coaxial with the piston
- B25D: PERCUSSIVE TOOLS {(percussive machines for forging B21J; hand-held drilling machines, in general B23B45/00, for wood B27C3/08; drilling machines, used for mining or quarrying, with reciprocating tool which is turned intermittently when out of contact with the working face E21B1/00)}

## Abstract

A percussion device has a machine housing (1), a forwards and backwards movable percussion piston (2) in the machine housing, and a reciprocatingly movable valve body (6) in the machine housing. The percussion piston has a first (4) and a second (5) driving surface subjected to pressure to drive the percussion piston (2) forwards and backwards. The valve body (6) has a first end surface (12) and a second end surface (13) for driving the valve body in first and second directions by applied pressure. The valve body (6) is arranged over a channel (7) in the machine housing, to connect at least the second (5) driving surface alternately to a pressure source (8) or to low pressure (9), and the second end surface (13) is alternately connectable by the percussion piston (2) to the pressure source (8) or, over a valve device (11) for creating a counter-pressure, to the low pressure (8).

## Claims

### Claim 1

Percussion device for rock drilling machines including a machine housing, a forwards and backwards movable percussion piston in a cylinder bore in the machine housing, and a reciprocatingly movable valve body in the machine housing, said percussion piston being adapted to subject a tool to impacts, and said percussion piston including a first and a second percussion piston driving surface intended to be subjected to pressure in order to drive the percussion piston forwards and backwards, said valve body including a first valve body driving surface and a second valve body driving surface, wherein pressurizing the first valve body driving surface tends to drive the valve body in a first direction and pressurizing the second valve body driving surface tends to drive the valve body in a second direction, said valve body being arranged, over a first channel arranged in the machine housing, to connect at least the second of the percussion piston driving surfaces alternately to a pressure source or to low pressure, wherein the second valve body driving surface is connected, dependent on the position of the percussion piston, either to the pressure source or, over a valve device for creating a counter pressure, to the low pressure in a tank for reducing the time necessary for the valve body to change direction of movement between said first and second directions, said valve device being positioned in a second channel connecting the cylinder bore with the tank.

### Claim 2 (depends on 1)

Percussion device according to claim 1, wherein the first driving surface is continuously connected to the pressure source.

### Claim 3 (depends on 1)

Percussion device according to claim 1, wherein the first valve body driving surface is continuously connected to the pressure source.

### Claim 4 (depends on 2)

Percussion device according to claim 2, wherein the first valve body driving surface is continuously connected to the pressure source.

### Claim 5

Percussion device for rock drilling machines including a machine housing, a forwards and backwards movable percussion piston in a cylinder bore in the machine housing, and a reciprocatingly movable valve body in the machine housing, said percussion piston being adapted to subject a tool to impacts, and said percussion piston including a first and a second percussion piston driving surface intended to be subjected to pressure in order to drive the percussion piston forwards and backwards, said valve body including a first valve body driving surface and a second valve body driving surface, wherein pressurizing the first valve body driving surface tends to drive the valve body in a first direction and pressurizing the second valve body driving surface tends to drive the valve body in a second direction, said valve body being arranged, over a first channel arranged in the machine housing, to connect at least the second of the percussion piston driving surfaces alternately to a pressure source or to low pressure, wherein the second valve body driving surface is connected, dependent on the position of the percussion piston, either to the pressure source or, over a valve device for creating a counter pressure, to the low pressure in a tank for reducing the time necessary for the valve body to change direction of movement between said first and second directions, said valve device being positioned in a second channel connecting a portion of the cylinder bore in which portion the percussion piston moves during operation of the percussion device with the tank.