# US 8,770,313 B2 · Impulse generator, hydraulic impulse tool and method for producing impulses > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,313 B2 - Document ID: US8770313B2 - Status: Granted - Kind: B2 - Application number: 11/918,704 - Filed: 2006-03-20 - Published: 2009-02-12 - Granted: 2014-07-08 - Earliest claimed: 2005-05-23 - Assignees: Atlas Copco Rock Drills AB - Applicants: Kenneth Weddfelt; Göran Tuomas; Risto Wisakanto - Inventors: Kenneth Weddfelt; Göran Tuomas; Risto Wisakanto - Web page: https://patentgrep.com/patent/US8770313B2 ## CPC - E21B 28/00: Vibration generating arrangements for boreholes or wells, e.g. for stimulating production ({for fishing for or freeing objects E21B31/005;} for transmitting measuring-signals E21B47/14; for geophysical measurements G01V1/02) - B25D 9/125: {driven directly by liquid pressure working with pulses} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - 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 An impulse generator (1) for a percussive tool includes a chamber (3) for receiving a liquid volume and an impulse piston (4) which is arranged for transferring pressure pulses in the liquid volume into stress wave pulses in the tool. The chamber (3) is adapted with respect to its shape such that it forms a resonance chamber for liquid in the liquid volume for forming at least one pressure antinode (11,15,17) inside the chamber. The invention also concerns a method and a hydraulic impulse tool. ## Claims ### Claim 1 Method for producing impulses for a percussive tool including a chamber for receiving a liquid volume and an impulse piston which is arranged for transferring pressure pulses in the liquid volume into stress wave pulses in the tool, the steps of said method comprising periodically influencing liquid in the chamber for setting the liquid volume in resonance for forming at least one pressure antinode in the chamber. ### Claim 2 (depends on 1) Method according to claim 1, wherein the liquid in the chamber is influenced periodically by input and output of liquid to the chamber with a certain frequency. ### Claim 3 (depends on 2) Method according to claim 2, wherein liquid is fed in to and fed out from the chamber through a plurality of liquid inlets/outlets which are distributed over the circumference of the chamber. ### Claim 4 (depends on 3) Method according to claim 3, wherein a pressure node is arranged to be formed in the region of said liquid inlets/outlets and a pressure antinode with the greatest pressure amplitude in the region of the impulse piston. ### Claim 5 (depends on 1) Method according to claim 1, wherein liquid is fed in to and fed out from the chamber through a plurality of liquid inlets/outlets which are distributed over the circumference of the chamber. ### Claim 6 (depends on 5) Method according to claim 5, wherein a pressure node is arranged to be formed in the region of said liquid inlets/outlets and a pressure antinode with the greatest pressure amplitude in the region of the impulse piston. ### Claim 7 (depends on 1) Method according to claim 1, wherein the resonance is generated such that in operation quarter wave resonance or odd multiple of quarter wave resonance prevails. ### Claim 8 (depends on 1) Method according to claim 1, wherein the frequency is controlled to be between about 200 and 1000 Hz. ### Claim 9 (depends on 1) Method according to claim 1, wherein liquid is fed in distributed over the circumference of the chamber. ### Claim 10 (depends on 1) Method according to claim 1, wherein the shape of the chamber is changed in order to control the resonance frequency. ### Claim 11 (depends on 10) Method according to claim 10, wherein the length of the chamber is changed. ### Claim 12 (depends on 1) Method according to claim 1, wherein pressure pulses are transferred to an impulse chamber which is positioned at the impulse piston, and which is separate from the chamber, over a channel arranged between the chamber and the impulse chamber. ### Claim 13 (depends on 12) Method according to claim 12, wherein the flow in said channel is controlled. ### Claim 14 (depends on 12) Method according to claim 12, wherein length or area of said channel is adjusted for controlling the shape of said stress wave pulses. ### Claim 15 (depends on 1) Method according to claim 1, wherein pressure pulses are transferred between a plurality of mutually series connected chambers. ### Claim 16 (depends on 1) Method according to claim 1, wherein a liquid from the group: water, silicon oil, hydraulic oil, mineral oil is used.