Patent US3802199A successfully refreshed from Google Patents.
US3802199A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Two-stage hydraulic device
Assignee: Individual
•
Filing: 1972-10-17
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Granted: 1974-04-09
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Expires: 1992-10-17
Abstract
Abstract A master cylinder for hydraulic brakes has large and small cylinders arranged end-to-end in an integral cylinder housing, with large and small pistons which are structurally integral operating in the two cylinders and having unidirectional seals in contact with the cylinder walls, the small piston seal positioned to cut off a passage connected with a reservoir at the beginning of the two-stage working stroke. As pressure in the large cylinder increases, a relief valve opens in a passage in the piston, equalizing the pressure in the two cylinders so that the entire operator effort applies to the small cylinder only. Hydraulic pressure for braking is thus substantially increased with little increase in operator effort.
Inventors
- 👤 J Hagberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:15
CPC Classifications
B; B60; B60T; B60T11/00; B60T11/10; B60T11/16; B60T11/165
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
371 words
A mechanically-powered hydraulic pressure device comprising a small diameter piston operating in a small diameter pressure input chamber; a large diameter piston operating in a large diameter pressure output chamber, and a connecting rod rigidly joining the two pistons together for effecting a power stroke and a return stroke; a liquid supply reservoir communicating with the input chamber via a single flow port in the input chamber side wall; said small diameter piston having a first unidirectional peripheral seal riding on the input chamber side wall to move across the flow port during each stroke of the piston means so that the input chamber is in free open communication with the port when the piston means nears the end of its return stroke, and the peripheral seal is interposed between the input chamber and flow port when the piston means nears the end of its power stroke; said first peripheral seal being oriented so that when it is interposed between the input chamber and flow port it will permit flow from the reservoir through the port while preventing backflow from the input chamber through the port; said large diameter piston having a second unidirectional peripheral seal riding on the output chamber sidewall to permit flow from the input chamber into the output chamber while preventing backflow from the output chamber to the input chamber; pressure-responsive check valve means disposed in the piston means; said valve means being operable to permit flow from the output chamber to the input chamber when the pressure differential between said chambers reaches a predetermined value, whereby during the power stroke the piston means advances relatively rapidly until the output chamber is pressurized, after which the pressureresponsive check valve means opens to pressurize the input chamber for reducing the mechanical force that must be applied to the pistons to maintain the output chamber at a given state of pressurization; and a normally closed valve means carried by the large diameter piston for depressurizing the pressure output chamber at the end of The return stroke; said depressurizing valve means having an actuator arranged to contact an end wall of the output chamber to open the depressurizing valve means as the piston nears the end of its return stroke.
Claim 2
Dependent Claim
371 words
A mechanically-powered hydraulic pressure device comprising a small diameter piston operating in a small diameter pressure input chamber; a large diameter piston operating in a large diameter pressure output chamber, and a connecting rod rigidly joining the two pistons together for effecting a power stroke and a return stroke; a liquid supply reservoir communicating with the input chamber via a single flow port in the input chamber side wall; said small diameter piston having a first unidirectional peripheral seal riding on the input chamber side wall to move across the flow port during each stroke of the piston means so that the input chamber is in free open communication with the port when the piston means nears the end of its return stroke, and the peripheral seal is interposed between the input chamber and flow port when the piston means nears the end of its power stroke; said first peripheral seal being oriented so that when it is interposed between the input chamber and flow port it will permit flow from the reservoir through the port while preventing backflow from the input chamber through the port; said large diameter piston having a second unidirectional peripheral seal riding on the output chamber sidewall to permit flow from the input chamber into the output chamber while preventing backflow from the output chamber to the input chamber; pressure-responsive check valve means disposed in the piston means; said valve means being operable to permit flow from the output chamber to the input chamber when the pressure differential between said chambers reaches a predetermined value, whereby during the power stroke the piston means advances relatively rapidly until the output chamber is pressurized, after which the pressureresponsive check valve means opens to pressurize the input chamber for reducing the mechanical force that must be applied to the pistons to maintain the output chamber at a given state of pressurization; and a normally closed valve means carried by the large diameter piston for depressurizing the pressure output chamber at the end of The return stroke; said depressurizing valve means having an actuator arranged to contact an end wall of the output chamber to open the depressurizing valve means as the piston nears the end of its return stroke.
References Cited (Backward Citations)
US2185072A
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US2299912A
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US2372015A
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US2448194A
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FR1062138A
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US2986886A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-08 | 1977-10-08 | 1978-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-08 | 1981-10-08 | 1982-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-08 | 1985-10-08 | 1986-04-09 | $7700.00 | Window Closed / Lapsed |