US3800664A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impact tools or apparatus
Assignee: Joy Global Industries Ltd
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Filing: 1972-01-18
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Granted: 1974-04-02
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Expires: 1992-01-18
Abstract
Abstract The invention is for an impact tool comprising a pressure fluid operating piston and cylinder device in which pressure fluid, for the cyclic operation of said device, is controlled by control means responsive to changes in fluid pressure brought about by relative reciprocatory movement between the piston and cylinder. In one preferred embodiment of the invention said control means comprises a valve means for controlling the supply of pressure fluid to the cylinder, for the retraction of the piston, and for controlling the exhausting of said pressure fluid from the cylinder, for the advance of the piston, a chamber or chambers connected to the cylinder so that a fluid therein will be subjected to pressure changes by movement of the piston, and means responsive to pressures in said chamber or chambers and operative cyclicly to switch said valve means between a pressure fluid supply position and a pressure fluid exhaust position. Conveniently said chamber or chambers is or are connected to the cylinder so that the fluid in said chamber or chambers will be compressed by retraction of the piston. The pressure fluid, for the operation of the tool, may be a liquid and the fluid in the chamber or chambers, which is compressible, may be a gas. Alternatively the pressure fluid, for the operation of the tool, may be a compressible liquid and the fluid in the chamber or chambers a similar compressible liquid.
Inventors
- 👤 R Phillips
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:54
CPC Classifications
E; E21; E21C; E21C37/00; E21C37/22; B; B25; B25D; B25D9/00; B25D9/06; B25D9/12; B25D9/14; B25D9/145; Y; Y10; Y10S; Y10S173/00; Y10S173/04
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
222 words
An impact tool comprising a housing including a first cylinder portion and a second cylinder portion, a piston working in said first cylinder portion, the first cylinder portion having pressure fluid supply and exhaust means for the retraction and advancement of the piston respectively, a control valve means for said pressure fluid supply and exhaust means, pressure sensitive means operative to actuate said control valve means, means for supporting a tool to be struck by the piston when it is advanced, said second cylinder portion including a chamber positioned to receive the piston when it is retracted, a separate body of fluid permanently disposed in said chamber and compressed therein by retraction of the piston into said chamber, and connecting means between said chamber and said pressure sensitive means whereby said compression of said fluid in the chamber acts on said pressure sensitive means to actuate the control valve means to exhaust the first cylinder portion and allow the piston to advance under the action of said compressed fluid and make a stroke in the impacting direction, and the resultant fall of fluid pressure in the chamber causes said pressure sensitive means to allow the control valve means to actuate to supply pressure fluid to the first cylinder portion for retraction of the piston thereby to cause cyclic operation of the tool.
Claim 2
Dependent Claim
222 words
An impact tool comprising a housing including a first cylinder portion and a second cylinder portion, a piston working in said first cylinder portion, the first cylinder portion having pressure fluid supply and exhaust means for the retraction and advancement of the piston respectively, a control valve means for said pressure fluid supply and exhaust means, pressure sensitive means operative to actuate said control valve means, means for supporting a tool to be struck by the piston when it is advanced, said second cylinder portion including a chamber positioned to receive the piston when it is retracted, a separate body of fluid permanently disposed in said chamber and compressed therein by retraction of the piston into said chamber, and connecting means between said chamber and said pressure sensitive means whereby said compression of said fluid in the chamber acts on said pressure sensitive means to actuate the control valve means to exhaust the first cylinder portion and allow the piston to advance under the action of said compressed fluid and make a stroke in the impacting direction, and the resultant fall of fluid pressure in the chamber causes said pressure sensitive means to allow the control valve means to actuate to supply pressure fluid to the first cylinder portion for retraction of the piston thereby to cause cyclic operation of the tool.
Claim 3
Dependent Claim
26 words
An impact tool as claimed in claim 1 wherein the pressure fluid supply is a liquid and the fluid compressed in the chamber is a gas.
Claim 4
Dependent Claim
27 words
An impact tool as claimed in claim 1 wherein the pressure fluid supply is a liquid and the fluid compressed in the chamber is a similar liquid.
Claim 5
Dependent Claim
46 words
An impact tool as claimed in claim 1 wherein the pressure sensitive means is a pressure actuated pilot valve and the control valve means is a spool valve, a supply of pressure fluid to said spool valve for its operation, being controlled by said pilot vaLve.
Claim 6
Dependent Claim
45 words
An impact tool as claimed in claim 1 wherein the pressure sensitive means comprises pressure actuated pilot valves and the control valve means is a spool valve, a supply of pressure fluid to said spool valve, for its operation, being controlled by said pilot valves.
Claim 7
Dependent Claim
57 words
An impact tool as claimed in claim 5 wherein one of said pilot valves which actuates the spool valve to the exhaust position is a high pressure piston operated pilot valve and the other of said pilot valves, which actuates the spool valve to the pressure fluid supply position, is a low pressure piston operated pilot valve.
Claim 8
Dependent Claim
70 words
A impact tool as claimed in claim 1 wherein the control valve means comprises a spool valve which is operated from the pressure fluid supply to the pressure fluid exhaust position under the control of a high pressure piston-operated pilot-valve connected for its operation to said chamber, and from the pressure fluid exhaust to the pressure fluid supply position by causing the exhaust fluid to act on said spool valve.
Claim 9
Dependent Claim
80 words
An impact tool as claimed in claim 1, wherein the control valve means comprises a spool valve which is operated from the pressure fluid supply to the pressure fluid exhaust position under the control of a high pressure piston-operated pilot-valve connected for its operation to said chamber, and from the pressure fluid exhaust to the pressure fluid supply position by causing the exhaust fluid to act on a pilot valve controlling a supply of pressure fluid to the spool valve.
Claim 10
Dependent Claim
16 words
An impact tool as claimed in claim 4 wherein said pilot valve has a lag characteristic.
Claim 11
Dependent Claim
22 words
An impact tool as claimed in claim 1 wherein means is provided for the charging of said chamber with a compressible fluid.
Claim 12
Dependent Claim
56 words
An impact tool as claimed in claim 1 and having a non return air inlet to permit an inflow of air to a part of the first cylinder portion so that the piston can act as an air pump to keep said part of the first cylinder portion at a higher pressure than the surrounding atmosphere.
Claim 13
Dependent Claim
26 words
An impact tool as claimed in claim 1 wherein the chamber of said second cylinder portion is a coaxial rearward extension of the first cylinder portion.
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) | 1977-04-01 | 1977-10-01 | 1978-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-01 | 1981-10-01 | 1982-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-01 | 1985-10-01 | 1986-04-02 | $7700.00 | Window Closed / Lapsed |