Patent US3608915A successfully refreshed from Google Patents.
Patent US4072169A successfully refreshed from Google Patents.
US4072169A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hydraulic control system
Assignee: Robert Bosch GmbH
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Filing: 1976-07-06
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Granted: 1978-02-07
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Expires: 1996-07-06
Abstract
Abstract A hydraulic control system has a three-position valve which in its central position disconnects the high-pressure and low-pressure sides of a pressure source from outlet lines but connects these sides of the source together through a low-pressure valve. Moved to either of its end positions the valve is disconnected from between the sides of the pressure source and the output lines are connected to the high-pressure and low-pressure source sides. A pressure-limiting valve is connected between the sides of the source. In addition, the high-pressure side is connected via pressure-reducing valve and a restriction to a pair of pilot valves which are in turn connected to the low-pressure side. These pilot valves are also connected to opposite chambers of a pilot cylinder that controls the valve body. The pressure-reducing valve between the pilot valves and the high-pressure side maintains a medium-pressure level in the system when the valves move from its central position.
Inventors
- 👤 Joachim Heiser
- 👤 Rainer Hoheisel
- 👤 Heinz Flaschar
- 👤 Heinz Gand
- 👤 Heinz Kleinschmidt
- 👤 Konrad Braunlinger
- 👤 Klaus Sopha
- 👤 Roland Schempp
- 👤 Hermann Sanzenbacher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 07:48
CPC Classifications
F; F15; F15B; F15B13/00; F15B13/02; F15B13/04; F15B13/042; F15B13/043; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/86582; Y10T137/86614; Y10T137/87169; Y10T137/87177; Y10T137/87185
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
278 words
A hydraulic control system connectible to a pair of output lines, said system comprising: a source of fluid having a high-pressure side and a low-pressure side; means including a low-pressure limiting valve for maintaining a predetermined low-pressure differential between its input and output sides; means including a main valve connected to said lines, said sides, and said low-pressure valve and having a valve body displaceable from an end position for connecting each of said lines to a respective one of said sides and disconnecting said low-pressure valve from one of said sides and another position for disconnecting said lines from said sides and connecting said low-pressure valve across said sides; means including a medium-pressure limiting valve having an input connected to said high-pressure side and an output for maintaining pressure at its output below a predetermined medium-pressure level greater than said low-pressure differential and smaller than the pressure differential between said sides, said low-pressure valve and said medium-pressure valve being connected in parallel across said sides in said other position of said valve body; a differential pilot piston connected to said valve body and jointly displaceable therewith; and pilot-valve means connected between said output of said medium-pressure valve and said pilot piston for hydraulically actuating same and thereby displacing said body between its said positions, said pilot-valve means including a chamber at the smaller face of said piston and connected to said output of said medium-pressure valve, a pair of pilot valves, and a chamber at the larger face of said piston connectable through one of said pilot valves to said low-pressure side and through the other of said pilot valves to the other chamber of said piston.
Claim 2
Dependent Claim
278 words
A hydraulic control system connectible to a pair of output lines, said system comprising: a source of fluid having a high-pressure side and a low-pressure side; means including a low-pressure limiting valve for maintaining a predetermined low-pressure differential between its input and output sides; means including a main valve connected to said lines, said sides, and said low-pressure valve and having a valve body displaceable from an end position for connecting each of said lines to a respective one of said sides and disconnecting said low-pressure valve from one of said sides and another position for disconnecting said lines from said sides and connecting said low-pressure valve across said sides; means including a medium-pressure limiting valve having an input connected to said high-pressure side and an output for maintaining pressure at its output below a predetermined medium-pressure level greater than said low-pressure differential and smaller than the pressure differential between said sides, said low-pressure valve and said medium-pressure valve being connected in parallel across said sides in said other position of said valve body; a differential pilot piston connected to said valve body and jointly displaceable therewith; and pilot-valve means connected between said output of said medium-pressure valve and said pilot piston for hydraulically actuating same and thereby displacing said body between its said positions, said pilot-valve means including a chamber at the smaller face of said piston and connected to said output of said medium-pressure valve, a pair of pilot valves, and a chamber at the larger face of said piston connectable through one of said pilot valves to said low-pressure side and through the other of said pilot valves to the other chamber of said piston.
Claim 3
Dependent Claim
84 words
The system defined in claim 1 wherein said valve body has a pair of such end positions, one of said lines being connected to said high-pressure side and the other line to said low-pressure side in one of said end positions and said one line being connected to said low-pressure side and said other line being connected to said high-pressure side in the other of said end positions, said low-pressure valve being disconnected from one of said sides in both of said end positions.
Claim 4
Dependent Claim
24 words
The system defined in claim 2 wherein said pilot-valve means is connected directly between said output of said medium-pressure valve and said low-pressure side.
Claim 5
Dependent Claim
19 words
The system defined in claim 3, further comprising a flow restriction between said medium-pressure valve and said pilot-valve means.
Claim 6
Dependent Claim
44 words
The system defined in claim 4, comprising a middle plate carrying said main valve, a plate connected to said source, to one side of said middle plate, and a plate connected to the other side of said middle plate and carrying said low-pressure valve.
Claim 7
Dependent Claim
92 words
The system defined in claim 4 further comprising means including a high-pressure limiting valve connected between said high-pressure and low-pressure sides for maintaining between its input and output a predetermined high-pressure differential greater than said medium-pressure differential and smaller than the pressure differential between said high-pressure and low-pressure sides, cutout means for disconnecting said high-pressure valve from at least one of said sides, and a closable cutoff valve between said medium-pressure valve and one of said sides, and a common plate carrying said high-pressure, medium-pressure, and cutoff valves and said cutout means.
Claim 8
Dependent Claim
236 words
A hydraulic control system connectable to a pair of output lines, said system comprising: a source of fluid having a high-pressure side and a low-pressure side; means including a low-pressure limiting valve for maintaining a predetermined low-pressure differential between its input and output sides; means including a main valve connected to said lines, said sides, and said low-pressure valve and having a valve body displaceable from an end position for connecting each of said lines to a respective one of said sides and disconnecting said low-pressure valve from one of said sides and another position for disconnecting said lines from said sides and connecting said low-pressure valve across said sides; means including a medium-pressure limiting valve having an input connected to said high-pressure side and an output for maintaining pressure at its output below a predetermined medium-pressure level greater than said low-pressure differential and smaller than the pressure differential between said sides; a pilot piston connected to said valve body and jointly displaceable therewith; pilot-valve means connected between said output of said medium pressure valve and said pilot piston for hydraulically actuating same and thereby displacing said body between its said positions; and means including a high-pressure limiting valve connected between said high-pressure and low-pressure sides for maintaining between its input and output a predetermined high-pressure differential greater than said medium-pressure differential and means for disconnecting said high-pressure valve from at least one of said sides.
Claim 9
Dependent Claim
236 words
A hydraulic control system connectable to a pair of output lines, said system comprising: a source of fluid having a high-pressure side and a low-pressure side; means including a low-pressure limiting valve for maintaining a predetermined low-pressure differential between its input and output sides; means including a main valve connected to said lines, said sides, and said low-pressure valve and having a valve body displaceable from an end position for connecting each of said lines to a respective one of said sides and disconnecting said low-pressure valve from one of said sides and another position for disconnecting said lines from said sides and connecting said low-pressure valve across said sides; means including a medium-pressure limiting valve having an input connected to said high-pressure side and an output for maintaining pressure at its output below a predetermined medium-pressure level greater than said low-pressure differential and smaller than the pressure differential between said sides; a pilot piston connected to said valve body and jointly displaceable therewith; pilot-valve means connected between said output of said medium pressure valve and said pilot piston for hydraulically actuating same and thereby displacing said body between its said positions; and means including a high-pressure limiting valve connected between said high-pressure and low-pressure sides for maintaining between its input and output a predetermined high-pressure differential greater than said medium-pressure differential and means for disconnecting said high-pressure valve from at least one of said sides.
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) | 1981-02-06 | 1981-08-08 | 1982-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-06 | 1985-08-08 | 1986-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-06 | 1989-08-08 | 1990-02-07 | $7700.00 | Window Closed / Lapsed |