US3774502A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic percussion device with pressure-responsive control of impact frequency
Assignee: Fried Krupp AG
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Filing: 1971-05-14
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Granted: 1973-11-27
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Expires: 1991-05-14
Abstract
Abstract A hydraulic percussion device has a reciprocating ram with a smaller rearwardly facing land and a larger forwardly facing land, the former being continuously subjected to the supply pressure of a fluid source whereas the latter is alternately connectable to a low-pressure discharge line (for the forward stroke) and to a branch of a conduit carrying the supply pressure (for the return stroke) by a slide valve whose shifting is hydraulically controlled by the ram. A throttle valve in the branch conduit leading to the slide valve senses the supply pressure and, if that pressure falls below a predetermined level, partly blocks that branch so as to reduce the reverse pressure differential effective during the return stroke whereby the withdrawal of the ram from an impact-receiving tool is delayed so that the impact frequency decreases, thus reducing the demand upon the source and providng more time for the buildup of the requisite working pressure.
Inventors
- 👤 F Arndt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:33
CPC Classifications
E; E21; E21C; E21C37/00; E21C37/22; B; B25; B25D; B25D9/00; B25D9/14; B25D9/145; F; F03; F03C; F03C1/00; F03C1/08; F03C1/14; Y; Y10; Y10S; Y10S173/00; Y10S173/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
219 words
A hydraulic percussion device comprising: a housing provided with a bore; a ram reciprocable within said bore between a rearward position withdrawn from an impact-receiving element and a forward positon proximal to said element, said ram being provided with a relatively small rearwardly facing land confronting a first fluid space and with a relatively large forwardly facing land confronting a second fluid space; a source of high-pressure hydraulic fluid; conduit means permanently connecting said source to said first fluid space and carrying fluid at the supply pressure of said source; valve means controlled by said ram for connecting said second fluid space to a low-pressure discharge line in said rearward position wherby the fluid pressure in said first fluid space is effective to drive said ram forwardly toward said element, said valve means being operative in said forward position to connect said second fluid space to a branch of said conduit means for developing a reverse pressure differential across said lands to return said ram to said rearward position; and throttle means in said branch responsive to said supply pressure for reducing the reverse pressure differential effective during rearward motion of the ram by partly blocking said branch upon diminution of said supply pressure below a predetermined level, thereby delaying the return of said ram to said rearward position.
Claim 2
Dependent Claim
219 words
A hydraulic percussion device comprising: a housing provided with a bore; a ram reciprocable within said bore between a rearward position withdrawn from an impact-receiving element and a forward positon proximal to said element, said ram being provided with a relatively small rearwardly facing land confronting a first fluid space and with a relatively large forwardly facing land confronting a second fluid space; a source of high-pressure hydraulic fluid; conduit means permanently connecting said source to said first fluid space and carrying fluid at the supply pressure of said source; valve means controlled by said ram for connecting said second fluid space to a low-pressure discharge line in said rearward position wherby the fluid pressure in said first fluid space is effective to drive said ram forwardly toward said element, said valve means being operative in said forward position to connect said second fluid space to a branch of said conduit means for developing a reverse pressure differential across said lands to return said ram to said rearward position; and throttle means in said branch responsive to said supply pressure for reducing the reverse pressure differential effective during rearward motion of the ram by partly blocking said branch upon diminution of said supply pressure below a predetermined level, thereby delaying the return of said ram to said rearward position.
Claim 3
Dependent Claim
62 words
A device as defined in claim 1 wherein said valve means comprises a body having a smaller end face in a first fluid cylinder, communicating permanently with said branch downstream of said throttle means, and having a larger end face in a second fluid cylinder, the latter being alternately connectable by said ram to said conduit means and to said discharge line.
Claim 4
Dependent Claim
39 words
A device as defined in claim 2 wherein said ram is effective to connect said first fluid cylinder to said conduit means in said forward position and to said discharge line in an intermediate position remote from said element.
Claim 5
Dependent Claim
24 words
A device as defined in claim 1 wherein said throttle means comprises a slider provided with biasing means urging same into a branch-blocking position.
Claim 6
Dependent Claim
38 words
A device as defined in claim 4 wherein said biasing means comprises a compression spring bearing upon one end of the slider, said slider having its opposite end permanently subjected to the supply pressure in said conduit means.
Claim 7
Dependent Claim
15 words
A device as defined in claim 1 comprising a pressure accumulator communicating with said branch.
Claim 8
Dependent Claim
17 words
A device as defined in claim 6, comprising a further pressure accumulator communicating with said discharge line.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-26 | 1977-05-28 | 1977-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-26 | 1981-05-28 | 1981-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-26 | 1985-05-28 | 1985-11-27 | $7700.00 | Window Closed / Lapsed |