# US 5,704,434 A · Hydraulic torque impulse mechanism

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- Number: US 5,704,434 A
- Document ID: US5704434A
- Status: Granted
- Kind: A
- Application number: 08/579,611
- Filed: 1995-12-26
- Granted: 1998-01-06
- Earliest claimed: 1994-12-30
- Assignees: Atlas Copco Tools AB
- Inventors: Knut Christian Schoeps
- Web page: https://patentgrep.com/patent/US5704434A

## CPC

- B25B 23/1453: {for impact wrenches or screwdrivers}
- B25B 21/02: with means for imparting impact to screwdriver blade or nut socket
- B25B: TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING, OR HOLDING

## Abstract

A hydraulic torque impulse mechanism comprising a rotatively driven drive member (10) which has a concentric fluid chamber (12) as well as radially acting cams (25, 26, 28), an output shaft (16) which extends into the fluid chamber (12) and which has two radially extending cylinder bores (18, 19) communicating with each other via a central high pressure chamber (23), two oppositely disposed piston elements (20, 21) reciprocable in the cylinder bores (18, 19) by the cams (25, 26, 28), and two valve chambers (45, 46) each comprising a number of fluid communicating openings (50) interconnecting the high pressure chamber (23) and the drive member fluid chamber (12), and a pressure responsive leaf spring valve element(51) for blocking fluid communication through these openings (50) as the pressure difference between the high pressure chamber (23) and the fluid chamber (12) exceeds a certain level.

## Claims

### Claim 1

Hydraulic torque impulse mechanism, comprising a rotatively driven drive member (10) provided with a concentric fluid chamber (12) as well as a radially acting cam means (25,26,28), an output shaft (16) extending through said drive member fluid chamber (12) and having two radially extending cylinder bores (18,19) which communicate continuously with each other via a central high pressure chamber (23), and two oppositely disposed piston elements (20,21) which are reciprocable in said cylinder bores (18,19) by said cam means (25,26,28),
characterized in that said output shaft (16) comprises at least one valve chamber (45,46) which communicates continuously with said high pressure chamber (23), said at least one valve chamber (45,46) comprises one or more fluid communicating openings (50) for connecting said high pressure chamber (23) to said drive member fluid chamber (12), and a pressure responsive valve means (51) arranged to block said one or more fluid communicating openings (50) as the pressure difference between said high pressure chamber (23) and said drive member fluid chamber (12) exceeds a certain level.

### Claim 2 (depends on 1)

Impulse mechanism according to claim 1, wherein said at least one valve chamber (45,46) is two in number and formed by a transverse bore extending through said output shaft (16) perpendicularly to said cylinder bores (18,19) and intersecting said high pressure chamber (23), said valve chambers (45,46) being defined by two end closures (47) comprising said fluid communicating openings (50) and forming a support for said valve means (51).

### Claim 3 (depends on 1)

Impulse mechanism according to claim 1 wherein said valve means (51) comprises one or more leaf spring elements.

### Claim 4 (depends on 1)

Impulse mechanism according to claim 1 wherein said valve means (51) comprises one or more Belleville-type spring washers.

### Claim 5 (depends on 2)

Impulse mechanism according to claim 2, wherein said valve means (51) comprises one or more leaf spring elements.

### Claim 6 (depends on 2)

Impulse mechanism according to claim 2, wherein said valve means (51) comprises one or more Belleville-type spring washers.