CA1178162A - Low power charge system - Google Patents
Low power charge systemInfo
- Publication number
- CA1178162A CA1178162A CA000434638A CA434638A CA1178162A CA 1178162 A CA1178162 A CA 1178162A CA 000434638 A CA000434638 A CA 000434638A CA 434638 A CA434638 A CA 434638A CA 1178162 A CA1178162 A CA 1178162A
- Authority
- CA
- Canada
- Prior art keywords
- pilot
- pressure
- communicated
- high pressure
- valve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- Fluid-Pressure Circuits (AREA)
- Details And Applications Of Rotary Liquid Pumps (AREA)
- Fluid-Driven Valves (AREA)
- Supply Devices, Intensifiers, Converters, And Telemotors (AREA)
Abstract
LOW POWER CHARGE SYSTEM
Abstract of the Disclosure A low power charge system includes a pilot-operated bypass valve having a unitary spool member movable in response to pressure in a pilot chamber to control fluid communication between a pump and separate low and high pressure circuits. The high pressure circuit includes an accumulator. A pilot valve includes a unitary shuttle member movable in response to the pressure in the high pressure circuit to control the fluid pressure in the pilot chamber.
Abstract of the Disclosure A low power charge system includes a pilot-operated bypass valve having a unitary spool member movable in response to pressure in a pilot chamber to control fluid communication between a pump and separate low and high pressure circuits. The high pressure circuit includes an accumulator. A pilot valve includes a unitary shuttle member movable in response to the pressure in the high pressure circuit to control the fluid pressure in the pilot chamber.
Description
I~8162 LOW POWER CHARGE SYSTEM
Background of the Invention Many valve systems are known which divert or bypass pump output from a high pressure system to a low pressure circuit, such as a reservoir, when the system pressure exceeds a specified pressure. However, many of these known systems are complex and thus expensive. Certain ones of these known systems also employ poppet or check valve elements to control various fluid flows therein. However, such poppet or check valves can produce unwanted noise due to the sometimes violent seating of the valve elements.
Summary of the Invention It is an object of the present invention to provide a simple and inexpensive bypass or diverter valve system.
Another object of the present invention is to provide a bypass valve system which does not make use of noise-producing poppet or check valves.
These and other objects are achieved by the present invention which includes a pilot-operated, spool-type bypass valve for controlling fluid communication between a pump and separate high and low pressure circuits in response to the fluid pressure in a pilot chamber. A spool-type pilot valve controls the fluid pressure in the pilot chamber as a function of the pressure in a sensin~ chamber communicated with the high pressure circuit. The valves cooperate to maintain the pressure in an accumulator in the high pressure circuit within a specified range.
Brief Description of the Drawings The sole figure is a schematic and sectional view of the present invention.
Detailed Description A vehicle conventional hydraulic system, such as a hydraulic assist-type transmission system 10, includes a pump 12 which supplies pressurized fluid to a high pressure circuit 14 which includes an accumulator 16 and the transmission control valves 18. The pump also supplies pressurized fluid to a low pressure circuit 20 which includes a cooler 22 and a transmission lubricating system 24.
~ccording to the present invention, a valve system for controlling communication between the pump 12 and the high and ' ~
:
, ~ ~ ~BlB2 lOW pressure circuits 14 and 20 includes a pilot-operated bypass valve 30 and a pilot valve 32. The bypass valve 30 has a housing 34 which defines an inlet annular groove 36 communicating with the pump 12, a first outlet annular groove 38 communicating with the low pressure circuit 20 and a second outlet annular groove 40 communicated with the high pressure circuit 14. The housing also defines a bore 42 which slidably receives a spool member 44. One end of the spool member 44 cooperates with the housing 34 to enclose a pilot chamber 46.
The spool member has first and second lands 48 and 50 rigidly interconnected by a rod portion 52. The first land 48 is operable to open and close communication between the inlet 36 and the first outlet 38. The second land 50 is operable to open and close communication between the inlet 36 and the second outlet 40O The spool member 44 moves in response to changes in the pressure in pilot chamber 46. Spring 54 urges spool member 44 to the position shown where outlet 38 is closed from the inlet 36 and where outlet 40 is open to the inlet 36.
Pilot valve 32 includes a housing 60 which includes first and second bores 62 and 64 separated by a reduced diameter portion 66. The housing 60 also defines a first port annular groove 68 which communicates the first bore 62 with a reservoir or sump, a second port 70 which communicates the first bore with the high pressure circuit 14 via outlet 40, a third port 72 which communicates the first bore with the pump 12 via inlet 36 and a pilot outlet annular groove 7~ which communicates the first bore 62 with the pilot chamber 46. The second bore 64 is communicated with the sump.
The pilot valve 32 also includes a shuttle member B0 which is movable within the housing 60. The shuttle member 80 has first and second lands 82 and 84 slidable in the first bore 62 and rigidly interconnected by a rod 86. The first land 82 cooperates with the wall of the first bore 62 to define a sensing chamber 88 at one end thereof, and is movable to open and close pilot outlet 74 with the first port 68 and the sensing chamber 88. The sensing chamber 88 is communicated with the high pressure circuit 14 via the second outlet 40 and the second po~t 70. The second land 84 prevents communication between the third port 72 and the first port 68. A shaft 90 projects from the second land 84, slidably and sealingly engages a wall of the
Background of the Invention Many valve systems are known which divert or bypass pump output from a high pressure system to a low pressure circuit, such as a reservoir, when the system pressure exceeds a specified pressure. However, many of these known systems are complex and thus expensive. Certain ones of these known systems also employ poppet or check valve elements to control various fluid flows therein. However, such poppet or check valves can produce unwanted noise due to the sometimes violent seating of the valve elements.
Summary of the Invention It is an object of the present invention to provide a simple and inexpensive bypass or diverter valve system.
Another object of the present invention is to provide a bypass valve system which does not make use of noise-producing poppet or check valves.
These and other objects are achieved by the present invention which includes a pilot-operated, spool-type bypass valve for controlling fluid communication between a pump and separate high and low pressure circuits in response to the fluid pressure in a pilot chamber. A spool-type pilot valve controls the fluid pressure in the pilot chamber as a function of the pressure in a sensin~ chamber communicated with the high pressure circuit. The valves cooperate to maintain the pressure in an accumulator in the high pressure circuit within a specified range.
Brief Description of the Drawings The sole figure is a schematic and sectional view of the present invention.
Detailed Description A vehicle conventional hydraulic system, such as a hydraulic assist-type transmission system 10, includes a pump 12 which supplies pressurized fluid to a high pressure circuit 14 which includes an accumulator 16 and the transmission control valves 18. The pump also supplies pressurized fluid to a low pressure circuit 20 which includes a cooler 22 and a transmission lubricating system 24.
~ccording to the present invention, a valve system for controlling communication between the pump 12 and the high and ' ~
:
, ~ ~ ~BlB2 lOW pressure circuits 14 and 20 includes a pilot-operated bypass valve 30 and a pilot valve 32. The bypass valve 30 has a housing 34 which defines an inlet annular groove 36 communicating with the pump 12, a first outlet annular groove 38 communicating with the low pressure circuit 20 and a second outlet annular groove 40 communicated with the high pressure circuit 14. The housing also defines a bore 42 which slidably receives a spool member 44. One end of the spool member 44 cooperates with the housing 34 to enclose a pilot chamber 46.
The spool member has first and second lands 48 and 50 rigidly interconnected by a rod portion 52. The first land 48 is operable to open and close communication between the inlet 36 and the first outlet 38. The second land 50 is operable to open and close communication between the inlet 36 and the second outlet 40O The spool member 44 moves in response to changes in the pressure in pilot chamber 46. Spring 54 urges spool member 44 to the position shown where outlet 38 is closed from the inlet 36 and where outlet 40 is open to the inlet 36.
Pilot valve 32 includes a housing 60 which includes first and second bores 62 and 64 separated by a reduced diameter portion 66. The housing 60 also defines a first port annular groove 68 which communicates the first bore 62 with a reservoir or sump, a second port 70 which communicates the first bore with the high pressure circuit 14 via outlet 40, a third port 72 which communicates the first bore with the pump 12 via inlet 36 and a pilot outlet annular groove 7~ which communicates the first bore 62 with the pilot chamber 46. The second bore 64 is communicated with the sump.
The pilot valve 32 also includes a shuttle member B0 which is movable within the housing 60. The shuttle member 80 has first and second lands 82 and 84 slidable in the first bore 62 and rigidly interconnected by a rod 86. The first land 82 cooperates with the wall of the first bore 62 to define a sensing chamber 88 at one end thereof, and is movable to open and close pilot outlet 74 with the first port 68 and the sensing chamber 88. The sensing chamber 88 is communicated with the high pressure circuit 14 via the second outlet 40 and the second po~t 70. The second land 84 prevents communication between the third port 72 and the first port 68. A shaft 90 projects from the second land 84, slidably and sealingly engages a wall of the
- 2 -~ ~7~162 1 reduced diameter portion 66 and projects into the second bore 64. The sealing engagement between shaft 90 and portion 66 prevents communication between the first and second bores 62 and 64. The shaft 90 includes a shoulder 92 for coupling with a spring 94 which urges the shuttle member 80 to the right, viewing the figure.
Mode of Operation The valve system is shown in its charging mode in the figure wherein all the pump output is directed by the bypass valve 30 to the high pressure circuit 14 to recharge the accumulator pressure Pa. As the accumulator 16 is charging, the pump pressure, Pp, will slightly exceed the accumulator pressure, Pa, and the shuttle member 80 will prevent communication between sensing chamber 88 and pilot port 74 until the accumulator pressure, Pa, is greater than a threshold pressure level defined by the relationship: (Sb ~ Pp x A2)/Al, where Sb is the force exerted by spring 94 when compressed to a bypass position, where A2 is the annular area of land 84 which is exposed to pump pressure from port 72 and where Al is the area of land 82 which is exposed to accumulator pressure in sensing chamber 88. When the accumulator pressure, Pa, exceeds this pressure level, the shuttle member 80 moves to the left and land 82 opens communication between sensing chamber 88 and pilot outlet 74, thus communicating accumulator pressure (or high pressure circuit pressure) to the pilot chamber 46.
The increased pressure in pilot chamber 46 moves spool member 44 to the left whereby land 50 closes communication between the pump 12 and the high pressure circuit 14 and whereby land 48 opens communication between inlet 36 and outlet 38, thus bypassing fluid from the pump 12 to the low pressure or lubricating circuit 20, thereby reducing the power required to drive the pump 12 and thus producing an energy savings.
In this bypass situation, land 82 of shuttle 80 prevents communication between pilot outlet 74 and the reservoir or sump
Mode of Operation The valve system is shown in its charging mode in the figure wherein all the pump output is directed by the bypass valve 30 to the high pressure circuit 14 to recharge the accumulator pressure Pa. As the accumulator 16 is charging, the pump pressure, Pp, will slightly exceed the accumulator pressure, Pa, and the shuttle member 80 will prevent communication between sensing chamber 88 and pilot port 74 until the accumulator pressure, Pa, is greater than a threshold pressure level defined by the relationship: (Sb ~ Pp x A2)/Al, where Sb is the force exerted by spring 94 when compressed to a bypass position, where A2 is the annular area of land 84 which is exposed to pump pressure from port 72 and where Al is the area of land 82 which is exposed to accumulator pressure in sensing chamber 88. When the accumulator pressure, Pa, exceeds this pressure level, the shuttle member 80 moves to the left and land 82 opens communication between sensing chamber 88 and pilot outlet 74, thus communicating accumulator pressure (or high pressure circuit pressure) to the pilot chamber 46.
The increased pressure in pilot chamber 46 moves spool member 44 to the left whereby land 50 closes communication between the pump 12 and the high pressure circuit 14 and whereby land 48 opens communication between inlet 36 and outlet 38, thus bypassing fluid from the pump 12 to the low pressure or lubricating circuit 20, thereby reducing the power required to drive the pump 12 and thus producing an energy savings.
In this bypass situation, land 82 of shuttle 80 prevents communication between pilot outlet 74 and the reservoir or sump
3~ pressure from port 68. This condition will persist until the accumulator pressure, Pa, falls below a second threshold pressure level defined by the relationship: lSc + Pp x A2)/Al, where Sc is the force of spring 94 when in a relatively expanded or "charging" state. When this threshold pressure level is reached, land 82 of shuttle member 80 moves to the 1 ~ 781~2 l right and opens communication between port 68 and pilot outlet 74, thus communicating pilot chamber 46 with the sump and lowering the pressure in pilot chamber 46. This lowered pilot chamber pressure permits spool member 44 to move back to its charging position wherein land 50 opens communication between the pump 12 and the high pressure circuit 14 and wherein land 4B
closes communication between pump 12 and the low pressure circuit 20, thus allowing the accumulator 16 to be recharged.
Since ~b is greater than Sc, the accumulator pressure at the end of a charging period will be greater than the accumulator pressure at the beginning of a charging period.
~ hile the invention has been described in conjunction with a specific embodiment, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the aforegoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and scope of the appended claims.
closes communication between pump 12 and the low pressure circuit 20, thus allowing the accumulator 16 to be recharged.
Since ~b is greater than Sc, the accumulator pressure at the end of a charging period will be greater than the accumulator pressure at the beginning of a charging period.
~ hile the invention has been described in conjunction with a specific embodiment, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the aforegoing description. Accordingly, this invention is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and scope of the appended claims.
- 4 -
Claims (11)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A valve system for controlling communication between a pump and separate high and low pressure fluid circuits, the high pressure circuit including an accumulator, the valve system comprising:
a pilot-operated bypass valve comprising a housing defining an inlet communicted with the pump, a first outlet communicated with the low pressure circuit and a second outlet communicated with the high pressure circuit, a unitary spool member movable in the housing and cooperating with the housing to define a pilot chamber therebetween, the spool member being movable in response to fluid pressure in the pilot chamber to control fluid communication between the inlet and the first and second outlets, the spool member having a first position wherein the inlet is communicated only with the first outlet and a second position wherein the inlet is communicated only with the second outlet, and resilient means for urging the spool member to the second position; and a pilot valve for controlling fluid pressure in the pilot chamber of the bypass valve in response to the fluid pressure in the high pressure circuit, the pilot valve comprising a housing having a first port communicated with a low pressure source, a second port communicated with a high pressure source and a pilot outlet communicated with the bypass valve pilot chamber, a unitary shuttle member movable in the pilot valve housing and cooperating therewith to define a sensing chamber therebetween communicated with the high pressure circuit, the shuttle member being movable in response to fluid pressure in the sensing chamber to control fluid communication between the pilot outlet and the first and second ports, the shuttle member having a first position wherein the pilot outlet is communicated with the second port and having a second position wherein the pilot outlet is communicated with the first port, and a resilient member urging the shuttle member to its second position, the bypass and pilot valves cooperating to connect the pump to the high pressure circuit when accumulator pressure falls below a first pressure level and to connect the pump to the low pressure circuit when accumulator pressure is above a second pressure level.
a pilot-operated bypass valve comprising a housing defining an inlet communicted with the pump, a first outlet communicated with the low pressure circuit and a second outlet communicated with the high pressure circuit, a unitary spool member movable in the housing and cooperating with the housing to define a pilot chamber therebetween, the spool member being movable in response to fluid pressure in the pilot chamber to control fluid communication between the inlet and the first and second outlets, the spool member having a first position wherein the inlet is communicated only with the first outlet and a second position wherein the inlet is communicated only with the second outlet, and resilient means for urging the spool member to the second position; and a pilot valve for controlling fluid pressure in the pilot chamber of the bypass valve in response to the fluid pressure in the high pressure circuit, the pilot valve comprising a housing having a first port communicated with a low pressure source, a second port communicated with a high pressure source and a pilot outlet communicated with the bypass valve pilot chamber, a unitary shuttle member movable in the pilot valve housing and cooperating therewith to define a sensing chamber therebetween communicated with the high pressure circuit, the shuttle member being movable in response to fluid pressure in the sensing chamber to control fluid communication between the pilot outlet and the first and second ports, the shuttle member having a first position wherein the pilot outlet is communicated with the second port and having a second position wherein the pilot outlet is communicated with the first port, and a resilient member urging the shuttle member to its second position, the bypass and pilot valves cooperating to connect the pump to the high pressure circuit when accumulator pressure falls below a first pressure level and to connect the pump to the low pressure circuit when accumulator pressure is above a second pressure level.
2. The valve system of claim 1, wherein:
the high pressure circuit comprises the high pressure source and the sensing chamber is connected to the high pressure circuit via the second port.
the high pressure circuit comprises the high pressure source and the sensing chamber is connected to the high pressure circuit via the second port.
3. The valve system of claim 1, wherein:
the spool member comprises first and second lands rigidly interconnected by a reduced diameter portion, the first land being slidable within the housing to open and close the first bypass valve outlet, the second land being exposed to fluid pressure in the pilot chamber and being slidable within the housing to open and close the second bypass valve outlet.
the spool member comprises first and second lands rigidly interconnected by a reduced diameter portion, the first land being slidable within the housing to open and close the first bypass valve outlet, the second land being exposed to fluid pressure in the pilot chamber and being slidable within the housing to open and close the second bypass valve outlet.
4. The valve system of claim 1, wherein the shuttle member comprises:
a first end face exposed to fluid pressure in the sensing chamber;
an annular surface exposed to pump pressure; and a second end face exposed to reservoir pressure, the shuttle member being movable in response to differential pressures created by fluid pressures acting upon the end faces and upon the annular surface to control fluid pressure in the pilot chamber.
a first end face exposed to fluid pressure in the sensing chamber;
an annular surface exposed to pump pressure; and a second end face exposed to reservoir pressure, the shuttle member being movable in response to differential pressures created by fluid pressures acting upon the end faces and upon the annular surface to control fluid pressure in the pilot chamber.
5. The valve system of claim 1, wherein:
the pilot valve housing includes a third port communicated with the pump, the shuttle member comprising a first land exposed to a pressure differential between the first port and the sensing chamber and movable to open and close the pilot outlet and a second land rigidly connected to the first land and exposed to a pressure differential between the first and third ports.
the pilot valve housing includes a third port communicated with the pump, the shuttle member comprising a first land exposed to a pressure differential between the first port and the sensing chamber and movable to open and close the pilot outlet and a second land rigidly connected to the first land and exposed to a pressure differential between the first and third ports.
6. The valve system of claim 1, wherein:
the pilot valve housing defines third port communicated with the pump and a first bore and a second bore separated by a reduced diameter portion, the first bore being communicated with the pilot outlet and the ports, the second bore being communicated with a fluid reservoir; and the shuttle member comprising a first land slidable in the first bore, exposed to a pressure differential between the first port and the sensing chamber and movable to open and close the pilot outlet, a second land slidable in the first bore, rigidly connected to the first land and exposed to a pressure differential between the first and third ports, and a shaft projecting from the second land and slidably and sealingly engaging the reduced diameter housing portion to prevent fluid communication between the first and second bores.
the pilot valve housing defines third port communicated with the pump and a first bore and a second bore separated by a reduced diameter portion, the first bore being communicated with the pilot outlet and the ports, the second bore being communicated with a fluid reservoir; and the shuttle member comprising a first land slidable in the first bore, exposed to a pressure differential between the first port and the sensing chamber and movable to open and close the pilot outlet, a second land slidable in the first bore, rigidly connected to the first land and exposed to a pressure differential between the first and third ports, and a shaft projecting from the second land and slidably and sealingly engaging the reduced diameter housing portion to prevent fluid communication between the first and second bores.
7. The valve system of claim 6, wherein:
the high pressure circuit comprises the high pressure source and the sensing chamber is connected to the high pressure circuit via the second port.
the high pressure circuit comprises the high pressure source and the sensing chamber is connected to the high pressure circuit via the second port.
8. The pilot valve of claim 6, wherein:
the shuttle member first land includes an axially facing end face exposed to fluid pressure in the high pressure circuit;
the shuttle member second land includes an annular surface exposed to pump presure; and the shaft having a pressure-responsive area exposed to reservoir pressure, the shuttle member being movable in response to differential pressures created by the fluid pressures acting upon the end face, the annular area and the pressure-responsive area to control fluid pressure in the pilot chamber of the bypass valve.
the shuttle member first land includes an axially facing end face exposed to fluid pressure in the high pressure circuit;
the shuttle member second land includes an annular surface exposed to pump presure; and the shaft having a pressure-responsive area exposed to reservoir pressure, the shuttle member being movable in response to differential pressures created by the fluid pressures acting upon the end face, the annular area and the pressure-responsive area to control fluid pressure in the pilot chamber of the bypass valve.
9. A valve system for controlling communication between a pump and separate high and low pressure fluid circuits, the high pressure circuit including an accumulator, the valve system comprising:
a pilot-operated bypass valve comprising a unitary spool member movable in response to fluid pressure in a pilot chamber to a first position wherein the pump is communicated only with the low pressure circuit and to a second position wherein the pump is communicated only with the high pressure circuit and resilient means for urging the spool member to the second position; and a pilot valve for controlling the fluid pressure in the pilot chamber of the bypass valve, the pilot valve comprising a housing having a first port communicated with a low pressure source, a second port communicated with a high pressure source, a third port communicated with the pump and a pilot outlet communicated with the pilot chamber, the pilot valve housing defining first and second bores separated by a reduced diameter portion, the first bore being communicated with the pilot outlet and the ports, the second bore being communicated with a fluid reservoir, the pilot valve also comprising a shuttle member movable in the pilot valve housing and cooperat-ing therewith to define a sensing chamber communicated with the high pressure circuit, the shuttle member having a first land slidable in the first bore, exposed to a pressure differential between the first port and the sensing chamber and movable to open and close the pilot outlet, a second land slidable in the first bore, rigidly connected to the first land and exposed to a pressure differential between the first and third ports, and a shaft projecting from the second land and slidably and sealingly engaging the reduced diameter housing portion to prevent fluid communication between the first and second bores, the shuttle member being movable in response to fluid pressure in the sensing chamber to control fluid communication between the pilot outlet and the first and second ports, the shuttle member having a first position wherein the pilot outlet is communicated with the second port and having a second position wherein the pilot outlet is communicated with the first port, the pilot valve also comprising a resilient member urging the shuttle member to its second position, the bypass and pilot valves cooperating to connect the pump to the high pressure circuit when accumulator pressure falls below a first pressure level and to connect the pump to the low pressure circuit when accumulator pressure is above a second pressure level.
a pilot-operated bypass valve comprising a unitary spool member movable in response to fluid pressure in a pilot chamber to a first position wherein the pump is communicated only with the low pressure circuit and to a second position wherein the pump is communicated only with the high pressure circuit and resilient means for urging the spool member to the second position; and a pilot valve for controlling the fluid pressure in the pilot chamber of the bypass valve, the pilot valve comprising a housing having a first port communicated with a low pressure source, a second port communicated with a high pressure source, a third port communicated with the pump and a pilot outlet communicated with the pilot chamber, the pilot valve housing defining first and second bores separated by a reduced diameter portion, the first bore being communicated with the pilot outlet and the ports, the second bore being communicated with a fluid reservoir, the pilot valve also comprising a shuttle member movable in the pilot valve housing and cooperat-ing therewith to define a sensing chamber communicated with the high pressure circuit, the shuttle member having a first land slidable in the first bore, exposed to a pressure differential between the first port and the sensing chamber and movable to open and close the pilot outlet, a second land slidable in the first bore, rigidly connected to the first land and exposed to a pressure differential between the first and third ports, and a shaft projecting from the second land and slidably and sealingly engaging the reduced diameter housing portion to prevent fluid communication between the first and second bores, the shuttle member being movable in response to fluid pressure in the sensing chamber to control fluid communication between the pilot outlet and the first and second ports, the shuttle member having a first position wherein the pilot outlet is communicated with the second port and having a second position wherein the pilot outlet is communicated with the first port, the pilot valve also comprising a resilient member urging the shuttle member to its second position, the bypass and pilot valves cooperating to connect the pump to the high pressure circuit when accumulator pressure falls below a first pressure level and to connect the pump to the low pressure circuit when accumulator pressure is above a second pressure level.
10. The valve system of claim 9, wherein:
the high pressure circuit comprises the high pressure source and the sensing chamber is connected to the high pressure circuit via the second port.
the high pressure circuit comprises the high pressure source and the sensing chamber is connected to the high pressure circuit via the second port.
11. The pilot valve of claim 9, wherein:
the shuttle member first land includes an axially facing end face exposed to fluid pressure in the high pressure circuit;
the shuttle member second land includes an annular surface exposed to pump pressure; and the shaft includes a pressure-responsive area exposed to reservoir pressure, the shuttle member being movable in response to differential pressures created by the fluid pressures acting upon the end face, the annular area and the pressure-responsive area to control fluid pressure in the pilot chamber of the bypass valve.
the shuttle member first land includes an axially facing end face exposed to fluid pressure in the high pressure circuit;
the shuttle member second land includes an annular surface exposed to pump pressure; and the shaft includes a pressure-responsive area exposed to reservoir pressure, the shuttle member being movable in response to differential pressures created by the fluid pressures acting upon the end face, the annular area and the pressure-responsive area to control fluid pressure in the pilot chamber of the bypass valve.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US41723782A | 1982-09-13 | 1982-09-13 | |
| US417,237 | 1982-09-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1178162A true CA1178162A (en) | 1984-11-20 |
Family
ID=23653146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000434638A Expired CA1178162A (en) | 1982-09-13 | 1983-08-15 | Low power charge system |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS5973603A (en) |
| AU (1) | AU1802783A (en) |
| BR (1) | BR8304936A (en) |
| CA (1) | CA1178162A (en) |
| DK (1) | DK415383A (en) |
| ES (1) | ES8503414A1 (en) |
-
1983
- 1983-08-15 CA CA000434638A patent/CA1178162A/en not_active Expired
- 1983-08-16 AU AU18027/83A patent/AU1802783A/en not_active Abandoned
- 1983-09-12 ES ES525529A patent/ES8503414A1/en not_active Expired
- 1983-09-12 BR BR8304936A patent/BR8304936A/en unknown
- 1983-09-13 DK DK415383A patent/DK415383A/en not_active Application Discontinuation
- 1983-09-13 JP JP58169111A patent/JPS5973603A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DK415383A (en) | 1984-03-14 |
| AU1802783A (en) | 1984-03-22 |
| BR8304936A (en) | 1984-04-24 |
| ES525529A0 (en) | 1984-07-01 |
| DK415383D0 (en) | 1983-09-13 |
| JPS5973603A (en) | 1984-04-25 |
| ES8503414A1 (en) | 1984-07-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |