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Title: Hydraulic control system
Claims: What is claimed is: 1. A hydraulic control system including: a generating means for providing power to a work function, including a variable displacement pump for discharging hydraulic fluid into a power line connecting said variable displacement pump to said work function; a driving means for operating said generating means, including a rotating shaft for operating said variable displacement pump; a control circuit means connected to both said generating means and said driving means for permitting the delivery of power to said work function when said driving means is operating up to a predetermined speed and for stopping delivery of power to said work function when said driving means is running above said predetermined speed, wherein said control circuit means includes a speed control pump operated by said rotating shaft and connected to one end of a control line, said control line including a high speed restrictor means for restricting the flow of hydraulic fluid from said speed control pump; said control line being connected to both a limiting line located between said high speed restrictor means and said speed control pump and a shuttle valve line located upstream from said limiting line. 2. The system as defined in claim 1, wherein a primary restrictor means is located in said power line for restricting the flow of hydraulic fluid to said work function; said primary restrictor means further includes a first signal line connected at one end to the power line upstream of said primary restrictor and a second signal line connected to said primary line downstream of said primary restrictor means. 3. The system as defined in claim 1, wherein said control circuit means includes a shuttle valve means being connected to an actuating line, said shuttle valve line, and said first signal line for permitting fluid communication between said first signal line and said actuating line when the pressure in the first signal line is greater than the pressure in said shuttle valve line and for permitting fluid communication between said shuttle valve line and said actuating line when the pressure in said shuttle valve line is greater than in said first signal line. 4. The system as defined in claim 3, wherein said control circuit means includes a high speed shut off means being responsive to hydraulic fluid pressure in said control line for maintaining said variable displacement pump in a destroked position when said speed control pump is operating above a predetermined speed. 5. The system as defined in claim 4, wherein said high speed shut-off means includes a shut-off valve body being connected at first end to said limiting line and at a second end to a reservoir, said second end further including a shutoff spring, a shut-off plunger means being biased towards said first end by said shut-off spring and by fluid in said limiting line towards said second end for permitting fluid to flow from a destroke line into a chamber line and from a reservoir line into said reservoir when the force of said shut-off spring is greater than the force of fluid in said limiting line and blocking these flows when the force of fluid in said limiting line overcomes the force of said shut-off spring. 6. The system defined in claim 5, wherein said shut-off plunger means includes a shut-off plunger having four shut-off lands, said first shut-off land is between said limiting line and said actuating line, said second land is between said actuating line and said destroke line, said third land is between said destroke line and said fourth land, and said fourth land is between said third land and said reservoir line when the shut-off plunger is biased toward said first end by said shut-off spring. 7. The system as defined in claim 2, wherein said control circuit means includes a flow control means for adjusting said variable displacement pump in response to a differential pressure across said primary restrictor so as to maintain a constant flow rate across said primary restrictor. 8. The system as defined in claim 5, wherein said control circuit means includes a flow control means for adjusting said variable displacement pump in response to a differential pressure across said primary restrictor so as to maintain a constant flow rate across said primary restrictor. 9. The system as defined in claim 8, wherein said flow control means includes a flow control body being connected at a first end to said actuating line and at a second end to said second signal line, said second end further including a flow control spring for biasing a flow control plunger means towards said first end, said flow control plunger means for permitting unrestricted fluid flow through said actuating line, said destroke line, and said reservoir line when the pressure in said first signal line is less than the combined pressure from said flow control spring and the presssure of fluid in said second signal line for permitting fluid to flow from said actuating line to said destroke line while interrupting the flow through said reservoir line when the pressure of fluid in said first signal line is greater than the combined pressure of said flow control spring and the fluid in said second signal line. 10. The system defined in claim 9, wherein said flow control plunger means includes a flow control plunger having three flow control plunger lands, said first flow control land is located between said actuating line and said destroke line, said second flow control land is located between said destroke line and said reservoir line, and said third flow control land is located between said reservoir line and said second end when said flow control plunger is biased towards said first end by said flow control spring. 11. The system as defined in claim 1, wherein said control circuit means includes a pressure control valve means for maintaining a substantially constant torque for turning said variable displacement pump when the pressure in said actuating line is below a first value, for destroking said variable displacement pump when the pressure in said actuating line is between said first value and a second value and for destroking said variable displacement pump to zero displacement and maintaining this condition with said speed control pump when the pressure in said actuating line is above said second value. 12. The system as defined in claim 9, wherein said control circuit means includes a pressure control valve means for maintaining a substantially constant torque for turning said variable displacement pump when the pressure in said actuating line is below a first value, for destroking said variable displacement pump when the pressure in said actuating line is between said first value and a second value and for destroking said variable displacement pump to zero displacement and maintaining this condition with said speed control pump when the pressure in said actuating line is above said second value. 13. The system as defined in claim 12, wherein said pressure control valve means includes a pressure control valve body, said pressure control valve body being connected at one end to said actuating line and at a second end to said chamber line, said second end comprising a destroke chamber containing a servo-piston being biased towards said second end by a destroke spring, said servo-piston being connected to a rod extending to said variable displacement pump for adjusting said pump, a pressure control plunger means in said pressure control valve body for blocking flow of hydraulic fluid from said first end when the pressure in said actuating line is below a first value for permitting fluid communication between said actuating line and said reservoir line when the pressure in said actuating line is between said first value and a second value, and for permitting communication between said actuating line and said destroke line when the pressure in said actuating line is greater than said second value. 14. The system defined in claim 13, wherein said pressure control plunger means includes a pressure control plunger having two pressure control lands wherein said first pressure control land is located between said actuating line and said destroke line and said second pressure control land is located between said reservoir line and said second end of said pressure control valve body when the pressure in said actuating line is below a first value. 15. The system defined in claim 5, wherein said control line includes a secondary check means downstream of said high-speed restrictor means for prohibiting fluid flow from said reservoir line to said speed control pump when the pressure in said reservoir line is greater than the pressure in said control line. 16. The system defined in claim 13, wherein said control line includes a secondary check means downstream of said high-speed restrictor means for prohibiting fluid flow from said reservoir line to said speed control pump when the pressure in said reservoir line is greater than the pressure in said control line. 17. In a hydraulic control system including a variable displacement pump for providing hydraulic fluid to a work function, driving means including a rotating shaft for operating said variable displacement pump, the improvement comprising: a control circuit means connected to both said variable displacement pump and said driving means for permitting the delivery of fluid to said work function when said driving means is operating up to a predetermined speed and for stopping delivery of said hydraulic fluid to said work function when said driving means is running above said predetermined speed, wherein said control circuit means includes a speed control pump operated by said rotating shaft and connected to one end of a control line, said control line including a high speed restrictor means for restricting the flow of hydraulic fluid from said speed control pump, said control line being connected to both a limiting line located between said high speed restrictor means and said speed control pump and a shuttle valve line located upstream from said limiting line. 18. The system as defined in claim 17, wherein a power line connects a variable displacement pump to said work function, a primary restrictor means is located in said power line for restricting the flow of hydraulic fluid to said work function, said primary restrictor means further includes a first signal line connected at one end to said power line upstream of said primary restrictor and a second signal line connected to said primary line downstream of said primary restrictor. 19. The system as defined in claim 17, wherein said control circuit means includes a shuttle valve means connected to an actuating line, said shuttle valve line, and said first signal line for permitting fluid communication between said first signal line and said actuating line when the pressure in the first signal line is greater than the pressure in the shuttle valve line and for permitting fluid communication between said shuttle valve line and said actuating line when the pressure in said shuttle valve line is greater than in said first signal line. 20. The system as defined in claim 19, wherein said control circuit means includes a high speed shut-off means being responsive to fluid pressure in said control line for maintaining said variable displacement pump in a zero destroked position when said speed control pump is operating above a predetermined speed. 21. The system as defined in claim 20, wherein said high speed shut-off means includes a shut-off valve body being connected at a first end to said limiting line and at a second end to a reservoir, said second end further including a shutoff spring, a shut-off plunger means being biased towards said first end by said shut-off spring and by fluid in said limiting line towards said second end for permitting fluid flow from a destroke line into a chamber line and from a reservoir line into said reservoir when the force of said shut-off spring is greater than the force of fluid in said limiting line and blocking these flows when the force of fluid in said limiting line overcomes the force of said shut-off spring. 22. The system defined in claim 21, wherein said shut-off plunger means includes a shut-off plunger having four shut-off lands, said first shut-off land is between said limiting line and said actuator line, said second land is between said actuator line and said destroke line, said third land is between said destroke line and said fourth land, and said fourth land is between said third land and said reservoir line when the shut-off plunger is biased toward said first end by said shut-off spring. 23. The system as defined in claim 18, wherein said control circuit means includes a flow control means for adjusting said variable displacement pump in response to a differential pressure across said primary restrictor so as to maintain a constant flow rate across said primary restrictor. 24. The system as defined in claim 21, wherein said control circuit means includes a flow control means for adjusting said variable displacement pump in response to a differential pressure across said primary restrictor so as to maintain a constant flow rate across said primary restrictor. 25. The system defined in claim 24, wherein saaid flow control means includes a flow control body being connected at a first end to said actuating line and at a second end to said second signal line, said second end further including a flow control spring for biasing a flow control plunger means towards said first end, said flow control plunger means for permitting unrestricted fluid flow through said actuating line, said destroke line, and said reservoir line when the pressure of fluid in said first signal line is less than the combined pressure from said flow control spring and fluid in said second signal line, and for permitting fluid to flow from said actuating line to said destroke line while interrupting the flow through said reservoir line when the pressure of fluid in said first signal line is greater than the combined pressure of said flow control spring and the fluid in said second signal line. 26. The system defined in claim 25, wherein said flow control plunger means includes a flow control plunger having three flow control plunger lands, wherein said first flow control land is located between said actuating line and said destroke line, said second flow control land is located between said destroke line and said reservoir line, and said third flow control land is located between said reservoir line and said second end when said flow control plunger is biased towards said first end by said flow control spring. 27. The system as defined in claim 17, wherein said control circuit means includes a pressure control valve means for maintaining a substantially constant torque for turning said variable displacement pump when the pressure in said actuating line is below a first value, for destroking said variable displacement pump when the pressure in said actuating line is between said first value and a second value, and for destroking said variable displacement pump to zero displacement and maintaining this condition with said speed control pump when the pressure in said actuating line is above said second value. 28. The system as defined in claim 25, wherein said control circuit means includes a pressure control valve means for maintaining a substantially constant torque for turning said variable displacement pump when the pressure in said actuating line is below a first value, for destroking said variable displacement pump when the pressure in said actuating line is between said first value and a second value, and for destroking said variable displacement pump to zero displacement and maintaining this condition with said speed control pump when the pressure in said actuating line is above said second value. 29. The system as defined in claim 28, wherein said pressure control valve means includes a pressure control valve body, said pressure control valve body being connected at one end to said actuating line and at a second end to said chamber line, said second end comprising a destroke chamber containing a servo-piston being biased towards said second end by a destroke spring, said servo-piston being connected to a rod extending to said variable displacement pump for adjusting said pump, a pressure control plunger means in said pressure control valve body for blocking flow of hydraulic fluid from said first end when the pressure in said actuating line is below a first value, and for permitting fluid communication between said actuating line and said reservoir line when the pressure in said actuating line is between said first value and a second value and for permitting fluid communication between said actuating line and said destroke line when the pressure in said actuating line is greater than said second value. 30. The system defined in claim 29, wherein said pressure control plunger means includes a pressure control plunger having two pressure control lands wherein said first pressure control land is located between said actuating line and said destroke line and said second pressure control land is located between said reservoir line and said second end of said pressure control valve body when the pressure in said actuating line is below a first value. 31. The system defined in claim 21, wherein said control line includes a secondary check means downstream of said high-speed restrictor means for prohibiting fluid flow from said reservoir line to said speed control pump when the pressure in said reservoir line is greater than the pressure in said control line. 32. The system defined in claim 29, wherein said control line includes a secondary check means downstream of said high-speed restrictor means for prohibiting fluid flow from said reservoir line to said speed control pump when the pressure in said reservoir line is greater than the pressure in said control line. 33. A hydraulic control system including: a variable displacement pump for providing power to a work function; destroke control means for reducing the displacement of said variable displacement pump; driving means for operating said variable displacement pump; speed sensor means for generating a control pressure signal which is proportional to the speed of rotation of said variable displacement pump; first pressure sensing means for developing a first pressure signal proportional to the output pressure of said variable displacement pump; shuttle valve means connected to an actuating line and adapted to receive said control pressure signal and said first pressure signal, for comparing said control pressure signal and said first pressure signal and for permitting said actuating line to receive said first pressure signal when the difference between said control pressure signal and said first pressure signal is less than a predetermined value, and for permitting said actuating line to receive said control pressure signal when the difference between said control pressure signal and said first pressure signal exceeds a predetermined value; and high speed shut-off means connected to said actuating line and to said destroke control means and responsive to said control pressure signal to communicate said actuating line with said destroke control means for maintaining said variable displacement pump in a destroked position when said variable displacement pump is operating above a predetermined speed. 34. The system as defined in claim 33, further including: pressure control means connected to said actuating line for maintaining a substantially constant torque for turning said variable displacement pump when the pressure in said actuating line is below a first value, for destroking said variable displacement pump when the pressure in said actuating line is between said first value and a second value and for destroking said variable displacement pump to zero displacement and maintaining this condition with said high speed shutoff means when the pressure in said actuating line is above said second value. 35. The system as defined in claim 33, further including: primary restrictor means connected to the output of said variable displacement downstream of said first pressure sensing means; second pressure sensing means for developing a second pressure signal proportional to the pressure downstream of said primary restrictor means; and flow control means connected to said actuating line and adapted to receive said second pressure signal for adjusting the output of said variable displacement pump in response to the difference between the pressure in said actuating line and said second pressure signal to thereby maintain a constant flow rate across said primary restrictor. 36. The system as defined in claim 35, further including: pressure control means connected to said actuating line for maintaining a substantially constant torque for turning said variable displacement pump when the pressure in said actuating line is below a first value, for destroking said variable displacement pump when the pressure in said actuating line is between said first value and a second value and for destroking said variable displacement pump to zero displacement and maintaining this condition with said high speed shut-off means when the pressure in said actuating line is above said second value. Other info: Inventors: Murphy, Eugene Scott (Portage, MI, US) Stevens, Clyde Bennett (Kalamazoo, MI, US) Application Number: 490629 Filing Date: 1974-07-22 Publication_date: 1976-02-03 Assignee: General Signal Corporation (Rochester, NY) Primary Class(es): 60/444 60/445, 60/447, 417/24, 417/218 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Freeh, William L. Assistant Examiner: LaPointe, G. P. Attorney: Huberfeld; Harold, Mednick; Jeffrey S. |
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