Patent US3765181A successfully refreshed from Google Patents.
US3765181A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Servosteering arrangement
Assignee: ZF Friedrichshafen AG
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Filing: 1972-07-06
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Granted: 1973-10-16
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Expires: 1992-07-06
Abstract
Abstract An arrangement of power steering cylinders having connected pistons is provided wherein an engine operated servopump is utilized to pressurize the cylinders. Normally one cylinder is used, but in the vent of predetermined increase in steering resistance the other cylinder is automatically pressurized to aid in the steering force applied. A metering or control pump operated by the steering spindle conrols flow in the system from the servopump and can pressurize both cylinders in the event of failure of the servopump.
Inventors
- 👤 A Lang
- 👤 E Wiedemann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:30
CPC Classifications
B; B62; B62D; B62D5/00; B62D5/06; B62D5/09; B62D5/093
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
179 words
A booster steering system having a servopump and a control pump connected thereto for metering flow therefrom to a primary servomotor and having a primary valve for directing flow to either chamber of a double acting booster cylinder and having a pressure operable secondary valve to control flow to either chamber of double acting secondary servomotor operable in unison with said primary servomotor, wherein said secondary valve is responsive to predetermined pressure at a respective side of said control pump for actuation to pressurize respective chambers of said secondary servomotor from said servopump for assisting in the steering effort of said primary servomotor, said secondary valve having respective pressure chambers for actuation in respective directions and said control pump having respective sides connected to said latter respective pressure chambers; including connection means froM said control pump to said secondary valve whereby actuation thereof can provide pressure feed from said secondary pump to said secondary servomotor in event of failure of said servopump, said secondary servomotor being operable by pressure directed thereto through said secondary valve from said control pump.
Claim 2
Dependent Claim
179 words
A booster steering system having a servopump and a control pump connected thereto for metering flow therefrom to a primary servomotor and having a primary valve for directing flow to either chamber of a double acting booster cylinder and having a pressure operable secondary valve to control flow to either chamber of double acting secondary servomotor operable in unison with said primary servomotor, wherein said secondary valve is responsive to predetermined pressure at a respective side of said control pump for actuation to pressurize respective chambers of said secondary servomotor from said servopump for assisting in the steering effort of said primary servomotor, said secondary valve having respective pressure chambers for actuation in respective directions and said control pump having respective sides connected to said latter respective pressure chambers; including connection means froM said control pump to said secondary valve whereby actuation thereof can provide pressure feed from said secondary pump to said secondary servomotor in event of failure of said servopump, said secondary servomotor being operable by pressure directed thereto through said secondary valve from said control pump.
Claim 3
Dependent Claim
48 words
A booster steering system as set forth in claim 1, wherein said connection means comprises respective unidirectional flow control means from respective sides of said control pump to respective pressure chambers of said secondary valve isolating said sides from each other but permitting pressure feed from either side.
Claim 4
Dependent Claim
44 words
A booster steering system as set forth in claim 2, wherein said unidirectional means are effected by check valves having means whereby respective unidirectional flow control means are operated at a predetermined pressure higher than the predetermined pressure effecting operation of said secondary valve.
Claim 5
Dependent Claim
30 words
A booster steering system as set forth in claim 3, said unidirectional flow control means and said pressure predetermining means comprising ball check valves having respective springs effecting closure thereof.
Claim 6
Dependent Claim
56 words
A booster steering system as set forth in claim 4, including a connection from said servopump to said secondary valve for providing feed pressure thereto and a unidirectional valve means in said connection to prevent reversal of flow from said secondary valve to said servopump when said control valve is fed pressure from said control pump.
Claim 7
Dependent Claim
146 words
In a booster steering system as set forth in claim 5, said control valve having pressure chambers and comprising a valve spool having an axial passageway therethrough and a pair of check valves in said passageway spring biased to close in opposite directions and exposed to pressure in respective pressure chambers of said control valve to be opened by said pressure; means for feeding fluid pressure from either side of said control pump to said respective pressure chambers for actuating said valve spool and a respective check valve; including passage means through said valve spool for flow from said axial passage for pressure feed from either said check valve to a respective chamber of said secondary servomotor upon actuation of said valve spool by predetermined pressure in either pressure chamber of said control valve and opening of a respective check valve by a higher predetermined pressure.
Claim 8
Dependent Claim
112 words
A booster steering system as set forth in claim 4, wherein said control valve has an inlet, and has outlets connected to said secondary servomotor, and has a valve spool with piston ends acting in respective pressure chambers for actuation of said valve spool in a respective direction depending upon pressurizing of one chamber or the other to pressurize a respective chamber of said secondary servomotor via a respective outlet; including connection means between the sides of said control pump with a pair of check valves therein openable in opposite directions and a connection from said connection means to said inlet of said control valve from a point intermediate said check valves.
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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) | 1976-10-15 | 1977-04-16 | 1977-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-15 | 1981-04-16 | 1981-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-15 | 1985-04-16 | 1985-10-16 | $7700.00 | Window Closed / Lapsed |