# US 7,073,607 B2 · Operating system for hydraulic rock drill

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- Number: US 7,073,607 B2
- Document ID: US7073607B2
- Status: Granted
- Kind: B2
- Application number: 10/178,978
- Filed: 2002-06-25
- Published: 2003-01-09
- Granted: 2006-07-11
- Earliest claimed: 2001-06-25
- Inventors: Paul B. Campbell, Jr.
- Web page: https://patentgrep.com/patent/US7073607B2

## CPC

- B25D 9/125: {driven directly by liquid pressure working with pulses}
- B25D 9/20: involving a tubular-type slide valve
- B25D 16/00: Portable percussive machines with superimposed rotation {, the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit (combined percussion and rotary drilling adapted for earth drilling E21B6/00)}
- 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 hydraulic rock drill comprises a housing having a piston and valve bore formed therein, a rotation motor, and a fluid connection and fluid reservoir interposed between the housing and the rotation motor. Fluid connections to the hydraulic rock drill comprise a single inlet fluid connection to the housing and a single exhaust fluid connection from the rotation motor. The working shoulder areas of the piston are proportioned so that the exhaust stroke of the piston will pressurize the fluid in the reservoir, providing a fluid inlet source for the rotation motor. When the rotation torque demand increases, pressure in the fluid reservoir and pressure in the fluid inlet connection will rise accordingly, thus providing higher rotation torque while maintaining impact power. When fluid inlet pressure reaches a predetermined limit, rotation and impact will lessen or cease altogether.

## Claims

### Claim 1

An operating system for a rock drill consisting of a housing a single inlet and a single exhaust connection, an impact piston, an internal fluid reservoir, and a rotation motor, wherein
a. all fluid entering said single inlet connection flows sequentially, in series, from said impact piston through said internal fluid reservoir to said rotation motor;
b. said fluid reservoir is the only fluid supply source for said rotation motor;
c. all fluid flowing from said fluid reservoir through said rotation motor exits through said single exhaust connection;
d. said impact piston is driven toward impact by pressure acting against a drive shoulder and is retracted by pressure acting against a return shoulder, whereby said drive shoulder exhausts fluid into said fluid reservoir during retract;
e. flow requirements of said rotation motor are matched to flow requirements of said impact piston so as to utilize all of the exhaust flow from said impact piston for rotation,
whereby continuous and simultaneous impact and rotation occurs under all drilling conditions wherein adjustable bypass means is incorporated between said single exhaust connection to divert a percentage of fluid flow around said rotation motor and thus regulate the speed of said regulation motor.