Patent US3750405A successfully refreshed from Google Patents.
US3750405A
Expired / Lapsed
US
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Closed center hydraulic system
Assignee: Case LLC
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Filing: 1971-08-16
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Granted: 1973-08-07
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Expires: 1991-08-16
Abstract
Abstract A closed center hydraulic system having a variable displacement pump, two or more motor circuits associated therewith, one circuit being of the proportional demand type, priority means assuring the power requirements of said proportional demand circuit are met prior to permitting power flow to the other circuit, and flow and pressure compensating means in the other circuit for controlling the displacement of the pump.
Inventors
- 👤 E Virtue
- 👤 M Jennings
- 👤 H Orth
- 👤 R Lech
- 👤 J Ziskal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:53
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/16; F15B11/20; F04; F04B; F04B1/00; F04B1/12; F04B1/26; F04B1/30; F04B1/32; F04B1/324; F04B49/00; F04B49/08; F15B11/02; F15B2211/00; F15B2211/20; F15B2211/205; F15B2211/2053; F15B2211/20546; F15B2211/20553; F15B2211/30; F15B2211/305; F15B2211/30505; F15B2211/30525; F15B2211/3053; F15B2211/30535; F15B2211/32; F15B2211/321; F15B2211/324; F15B2211/40; F15B2211/405; F15B2211/40515; F15B2211/415; F15B2211/41572; F15B2211/42; F15B2211/426; F15B2211/428; F15B2211/45; F15B2211/455; F15B2211/50; F15B2211/505; F15B2211/50509; F15B2211/50518; F15B2211/515; F15B2211/5151; F15B2211/60; F15B2211/605; F15B2211/6051; F15B2211/70; F15B2211/705; F15B2211/7051; F15B2211/7053; F15B2211/7054; F15B2211/71; F15B2211/78
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
142 words
A pressure compensated pump having a de-stroking mechanism for controlling the displace ment thereof, an improved control system therefor comprising: a. a delivery conduit interconnected between said pump and adapted to be connected to a load, b. a first pressure control adapted to be connected to said delivery conduit for sensing the pressure in said conduit, and controlling said de-stroking mechanism so as to limit the pressure of the fluid delivered by said pump, c. a flow control means connected to said delivery conduit and for regulating said de-stroking mechanism so as to set a limit on the quantity of fluid delivered by said pump, and d. a variable pressure compensator connected to said delivery conduit for sensing the pressure in said delivery conduit, and for regulating said de-stroking mechanism so as to variably control the fluid pressure in said delivery conduit.
Claim 2
Dependent Claim
142 words
A pressure compensated pump having a de-stroking mechanism for controlling the displace ment thereof, an improved control system therefor comprising: a. a delivery conduit interconnected between said pump and adapted to be connected to a load, b. a first pressure control adapted to be connected to said delivery conduit for sensing the pressure in said conduit, and controlling said de-stroking mechanism so as to limit the pressure of the fluid delivered by said pump, c. a flow control means connected to said delivery conduit and for regulating said de-stroking mechanism so as to set a limit on the quantity of fluid delivered by said pump, and d. a variable pressure compensator connected to said delivery conduit for sensing the pressure in said delivery conduit, and for regulating said de-stroking mechanism so as to variably control the fluid pressure in said delivery conduit.
Claim 3
Dependent Claim
46 words
A device as recited in claim 1 in which said second pressure control means is manually variable so as to control said de-stroking mechanism such that an infinite number of pressures may be developed below the rating set by said first compensator in the delivery conduit.
Claim 4
Dependent Claim
113 words
In a variable displacement hydraulic system having a pump adapted to be connected to a power source for delivering fluid power to hydraulic motors through a delivery circuit, an improved control means comprising: a. a first pressure compensator, b. a flow control compensator, c. a second pressure compensator, d. a control circuit between said pump and a reservoir, each of said compensatoRs having a pressure sensitive means connected in parallel to said delivery circuit and in series in said control circuit between said pump and a reservoir, each of said compensators being effective to independently de-stroke said pressure compensated pump through said control circuit, or to increase said stroke through said control circuit.
Claim 5
Dependent Claim
113 words
In a variable displacement hydraulic system having a pump adapted to be connected to a power source for delivering fluid power to hydraulic motors through a delivery circuit, an improved control means comprising: a. a first pressure compensator, b. a flow control compensator, c. a second pressure compensator, d. a control circuit between said pump and a reservoir, each of said compensatoRs having a pressure sensitive means connected in parallel to said delivery circuit and in series in said control circuit between said pump and a reservoir, each of said compensators being effective to independently de-stroke said pressure compensated pump through said control circuit, or to increase said stroke through said control circuit.
Claim 6
Dependent Claim
155 words
A hydraulic power system comprising: a. a pressure compensated pump adapted for connection to a power input source, a reservoir, and a delivery conduit and having a servo mechanism responsive to fluid pressure in said delivery circuit for limiting the power developed by said pump, b. three three-way spool valves associated with said delivery circuit to sense the pressure or rate of flow therein, c. a control circuit interconnected between said servo mechanism and the reservoir, said three-way valves having a series connection with said control circuit for controlling the fluid flow in said circuit and pressure in said servo mechanism, each of said valves being responsive to pressure in said delivery circuit so as to shift in response to pressure changes to bleed fluid in said control circuit to said reservoir, or to direct fluid to said servo mechanism so as to increase the pressure therein, and thereby change the stroke of the pump.
Claim 7
Dependent Claim
155 words
A hydraulic power system comprising: a. a pressure compensated pump adapted for connection to a power input source, a reservoir, and a delivery conduit and having a servo mechanism responsive to fluid pressure in said delivery circuit for limiting the power developed by said pump, b. three three-way spool valves associated with said delivery circuit to sense the pressure or rate of flow therein, c. a control circuit interconnected between said servo mechanism and the reservoir, said three-way valves having a series connection with said control circuit for controlling the fluid flow in said circuit and pressure in said servo mechanism, each of said valves being responsive to pressure in said delivery circuit so as to shift in response to pressure changes to bleed fluid in said control circuit to said reservoir, or to direct fluid to said servo mechanism so as to increase the pressure therein, and thereby change the stroke of the pump.
Claim 8
Dependent Claim
32 words
An apparatus as recited in claim 4 in which: a. an orifice is placed in said conduit and one of said spool valves is responsive to a pressure differential across said orifice.
Claim 9
Dependent Claim
23 words
An apparatus as recited in claim 4 in which: a. one of said spool valves has means for varying its sensitivity to pressure.
Claim 10
Dependent Claim
116 words
An improved hydraulic power system comprising: a. a variable displacement pump having a displacement control means for controlling the delivery thereof, b. a first circuit interconnected between said pump and a first load, c. a second circuit also connected to said pump and adapted to be connected to a second load, d. a priority valve means separating said circuits, e. regulator means associated with said first circuit for controlling said displacement control means of said pump so as to limit the maximum pressure developed thereby, f. manually controlled compensator means associated with said second circuit and with said displacement control means for matching the fluid power transmitted to the second load with the power requirements thereof.
Claim 11
Dependent Claim
116 words
An improved hydraulic power system comprising: a. a variable displacement pump having a displacement control means for controlling the delivery thereof, b. a first circuit interconnected between said pump and a first load, c. a second circuit also connected to said pump and adapted to be connected to a second load, d. a priority valve means separating said circuits, e. regulator means associated with said first circuit for controlling said displacement control means of said pump so as to limit the maximum pressure developed thereby, f. manually controlled compensator means associated with said second circuit and with said displacement control means for matching the fluid power transmitted to the second load with the power requirements thereof.
Claim 12
Dependent Claim
36 words
An apparatus as recited in claim 7 in which: a. demand valves are associated with said priority valve means for matching the power delivered to said first circuit with the power requirements of said first circuit.
Claim 13
Dependent Claim
28 words
An apparatus as recited in claim 8 in which several loads are connected in parallel in said first circuit and a demand valve is associated with each load.
Claim 14
Dependent Claim
22 words
An apparatus as recited in claim 9 in which each of the demand valves are placed in series with said priority valve.
Claim 15
Dependent Claim
141 words
A hydraulic system comprising: a. a pressure compensated pump having a servo mechanism for controlling the displacement thereof, a delivery circuit associated with said pump, b. first and second circuits interconnected with said delivery circuit through a priority valve, c. said priority valve means requiring said servo mechanism to compensate for delivery of power needs to said first circuit, with additional fluid power flowing to said second circuit, d. compensator means in said second circuit and associated with said servo mechanism for controlling the displacement of said pump such that the displacement thereof is regulated to supply the power needs of the first circuit as well as the power needs of the second circuit, and e. demand valves associated with loads in said first circuit and with said priority valve for matching power input to this circuit with power needs thereof.
Claim 16
Dependent Claim
141 words
A hydraulic system comprising: a. a pressure compensated pump having a servo mechanism for controlling the displacement thereof, a delivery circuit associated with said pump, b. first and second circuits interconnected with said delivery circuit through a priority valve, c. said priority valve means requiring said servo mechanism to compensate for delivery of power needs to said first circuit, with additional fluid power flowing to said second circuit, d. compensator means in said second circuit and associated with said servo mechanism for controlling the displacement of said pump such that the displacement thereof is regulated to supply the power needs of the first circuit as well as the power needs of the second circuit, and e. demand valves associated with loads in said first circuit and with said priority valve for matching power input to this circuit with power needs thereof.
Claim 17
Dependent Claim
20 words
An apparatus as recited in claim 11 in which said demand valves have a series connection with said priority valve.
Claim 18
Dependent Claim
16 words
An apparatus as recited in claim 11 in which: a. said compensator means are flow responsive.
Claim 19
Dependent Claim
48 words
An apparatus as recited in claim 11 in which: a. a variable orifice is placed in said second circuit and, b. said compensator means in said second circuit responds to pressure before and after said orifice so as to control the rate of fluid delivery from said pump.
Claim 20
Dependent Claim
69 words
A hydraulic system comprising: a. pump means having a de-stroking means to control the displacement thereof and a delivery conduit for receiving its discharge, b. first and second circuits separated by a priority valve for insuring the necessary power is directed to said first circuit, c. regulator means including a flow sensing device in said second circuit for de-stroking said pump as fluid delivered thereto reaches a selectable limit.
Claim 21
Dependent Claim
69 words
A hydraulic system comprising: a. pump means having a de-stroking means to control the displacement thereof and a delivery conduit for receiving its discharge, b. first and second circuits separated by a priority valve for insuring the necessary power is directed to said first circuit, c. regulator means including a flow sensing device in said second circuit for de-stroking said pump as fluid delivered thereto reaches a selectable limit.
Claim 22
Dependent Claim
17 words
An apparatus as recited in claim 15 in which said regulator means comprises a pressure sensing device.
Claim 23
Dependent Claim
109 words
A hydraulic power system comprising: a. variable displacement pump means having a servo mechanism for controlling displacement, b. a first circuit connected to said pump for directing power to a motor, c. a second circuit connected to said pump for directing power to a second motor, d. demand priority means associated with said pump for separating said circuits and for insuring power is directed to said first circuit to actuate motors associated therewith, e. power regulator means associated with said second circuit for controlling the displacement of said pump so as to provide power to actuate the motor associated with said second circuit in proportion to its power requirements.
Claim 24
Dependent Claim
109 words
A hydraulic power system comprising: a. variable displacement pump means having a servo mechanism for controlling displacement, b. a first circuit connected to said pump for directing power to a motor, c. a second circuit connected to said pump for directing power to a second motor, d. demand priority means associated with said pump for separating said circuits and for insuring power is directed to said first circuit to actuate motors associated therewith, e. power regulator means associated with said second circuit for controlling the displacement of said pump so as to provide power to actuate the motor associated with said second circuit in proportion to its power requirements.
Claim 25
Dependent Claim
123 words
A hydraulic power system comprising: a variable displacement pump means having a servo mechanism for controlling displacement; a delivery conduit means for receiving the discharge of said pump means and capable of being connected with a hydraulic motor; a pressure compensator means connected with said conduit means for sensing the pressure therein and causing the servo mechanism to de-stroke the pump means when a predetermined maximum pressure is reached; and a flow compensator connected with said conduit means for sensing the flow therethrough and causing the servo mechanism to de-stroke the pump means when a predetermined maximum flow is reached; whereby the displacement of the pump means is decreased whenever either said predetermined pressure or said predetermined flow is reached in said conduit.
Claim 26
Dependent Claim
123 words
A hydraulic power system comprising: a variable displacement pump means having a servo mechanism for controlling displacement; a delivery conduit means for receiving the discharge of said pump means and capable of being connected with a hydraulic motor; a pressure compensator means connected with said conduit means for sensing the pressure therein and causing the servo mechanism to de-stroke the pump means when a predetermined maximum pressure is reached; and a flow compensator connected with said conduit means for sensing the flow therethrough and causing the servo mechanism to de-stroke the pump means when a predetermined maximum flow is reached; whereby the displacement of the pump means is decreased whenever either said predetermined pressure or said predetermined flow is reached in said conduit.
Claim 27
Dependent Claim
27 words
A hydraulic power system according to claim 18, and further comprising: manually adjustable orifice means in said conduit means for selectively adjusting said predetermined maximum flow therethrough.
Claim 28
Dependent Claim
22 words
A hydraulic power system according to claim 19, and further comprising: manually adjustable spring means for selectively adjusting said predetermined maximum pressure.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |