# US 10,370,900 B2 · Remote control of stroke and frequency of percussion apparatus and methods thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,370,900 B2 - Document ID: US10370900B2 - Status: Granted - Kind: B2 - Application number: 15/224,029 - Filed: 2016-07-29 - Published: 2017-02-02 - Granted: 2019-08-06 - Earliest claimed: 2015-07-31 - Assignees: Tei Rock Drills, Inc. - Applicants: TEI Rock Drills, Inc. - Inventors: William N. Patterson - Web page: https://patentgrep.com/patent/US10370900B2 ## CPC - E21B 4/14: Fluid operated hammers - B25D 9/12: comprising a built-in liquid motor {, i.e. the tool being driven by hydraulic pressure} - B25D 9/26: Control devices for adjusting the stroke of the piston or the force or frequency of impact thereof {(control systems adapted for earth drilling E21B44/00)} - E21B 44/02: Automatic control of the tool feed ({E21B44/005,} E21B44/10 take precedence) - 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 This disclosure describes methods and systems for remote control of stroke length and frequency of percussion apparatus, such as a rock hammer drill. At a high level, the hammer drill is allowed to stay at a default low stroke length and high frequency to avoid applying excessive cyclic stress to the housing of the hammer drill and can be controlled to operate at a long stroke length and low frequency when the hammer drill has engaged the target material. The long stroke length and low frequency during operation can be initiated when a sufficient forward feed pressure is provided. While the hammer drill is idling or retracting, the forward fee pressure is not sufficient for the long stroke length operation and thus the drill operates at the default state and at a safe stress level to avoid premature damage. ## Claims ### Claim 1 A percussion apparatus comprising: a reciprocating component producing an axial impact on a rotating component, the reciprocating component housed in a cylinder; a sliding selector comprising a resilient member applying a continuous force biasing a selection piston toward a default setting, the default setting corresponding to a first stroke length and a first frequency of the reciprocating component; wherein the sliding selector changes the first stroke length and the first frequency in response to a feed forward pressure when the feed forward pressure exceeds a threshold value, the threshold value corresponding to a value of the continuous force that the resilient member acts on the selection piston, to allow for selecting an operation setting of a second stroke length and a second frequency; wherein the first stroke length and the first frequency produce a cyclic stress level lower than a fatigue stress level; and the second stroke length and the second frequency produce a cyclic stress level greater than the fatigue stress level. ### Claim 2 (depends on 1) The percussion apparatus of claim 1, further comprising a primary housing enclosing the selection piston and a secondary housing enclosing at least a portion of the resilient member, wherein the secondary housing is affixed to the primary housing. ### Claim 3 (depends on 2) The percussion apparatus of claim 2, wherein the primary housing has a plurality of control ports hydraulically connected to the cylinder of the reciprocating component. ### Claim 4 (depends on 1) The percussion apparatus of claim 1, further comprises a pressure relief valve for limiting the feed forward pressure. ### Claim 5 (depends on 1) The percussion apparatus of claim 1, wherein the percussion apparatus is a hammer drill and the reciprocating component is a hydraulically actuated hammer piston. ### Claim 6 (depends on 1) The percussion apparatus of claim 1, wherein the first stroke length is shorter than the second stroke length and the first frequency is correspondingly higher than the second frequency. ### Claim 7 (depends on 6) The percussion apparatus of claim 6, wherein the sliding selector is operable to further select a third stroke length and a third frequency, the third stroke length has a value between the first and the second stroke lengths, and the third frequency has a value between the first and the second frequencies. ### Claim 8 A percussion apparatus comprising: a reciprocating component producing an axial impact on a rotating component, the reciprocating component housed in a cylinder; a sliding selector comprising a resilient member applying a continuous force biasing a selection piston toward a default setting, the default setting corresponding to a first stroke length and a first frequency of the reciprocating component; wherein the sliding selector changes the first stroke length and the first frequency in response to a feed forward pressure when the feed forward pressure exceeds a threshold value, the threshold value corresponding to a value of the continuous force that the resilient member acts on the selection piston, to allow for selecting an operation setting of a second stroke length and a second frequency, wherein the feed forward pressure is in response to an operation of the percussion apparatus and wherein the feed forward pressure increases when the percussion apparatus presses against a target surface. ### Claim 9 (depends on 8) The percussion apparatus of claim 8, further comprising a primary housing enclosing the selection piston and a secondary housing enclosing at least a portion of the resilient member, wherein the secondary housing is affixed to the primary housing. ### Claim 10 (depends on 9) The percussion apparatus of claim 9, wherein the primary housing has a plurality of control ports hydraulically connected to the cylinder of the reciprocating component. ### Claim 11 (depends on 1) The percussion apparatus of claim 1, further comprises a pressure relief valve for limiting the feed forward pressure. ### Claim 12 (depends on 8) The percussion apparatus of claim 8, wherein the percussion apparatus is a hammer drill and the reciprocating component is a hydraulically actuated hammer piston. ### Claim 13 (depends on 8) The percussion apparatus of claim 8, wherein the first stroke length and the first frequency produce a cyclic stress level lower than a fatigue stress level; and the second stroke length and the second frequency produce a cyclic stress level greater than the fatigue stress level. ### Claim 14 (depends on 13) The percussion apparatus of claim 13, wherein the first stroke length is shorter than the second stroke length and the first frequency is correspondingly higher than the second frequency. ### Claim 15 (depends on 14) The percussion apparatus of claim 14, wherein the sliding selector is operable to further select a third stroke length and a third frequency, the third stroke length has a value between the first and the second stroke lengths, and the third frequency has a value between the first and the second frequencies.