초록 ▼

An electro-hydraulic system for operating a cooling fan and providing hydraulic fluid to a power steering system of the vehicle includes a hydraulic pump unit including first and second fixed displacement pumps and a common drive shaft for these pumps. A hydraulic fluid reservoir is connected to the

An electro-hydraulic system for operating a cooling fan and providing hydraulic fluid to a power steering system of the vehicle includes a hydraulic pump unit including first and second fixed displacement pumps and a common drive shaft for these pumps. A hydraulic fluid reservoir is connected to the inlet of each of the pumps. A priority valve is operatively connected to the outlet of the first pump and has an outlet connectible to the power steering system. This valve also has a second outlet connectible to a hydraulic motor for the cooling fan. This valve is arranged to provide a constant flow of hydraulic fluid to the power steering system. A hydraulic line connects an outlet of the second pump to the hydraulic motor. Hydraulic fluid flow through this line is combined with hydraulic fluid flow from the first pump to drive the motor. An electro-hydraulic proportional control valve has an inlet connected to the aforementioned line and an outlet connectible to the reservoir inlet and this control valve controls and limits the rotational speed of the motor. An electronic control device electrically operates and controls the control valve during use of the system.

대표청구항 ▼

We claim: 1. An electro-hydraulic system for operating a hydraulic motor for a vehicle cooling fan and providing pressurized hydraulic fluid to a power steering system of the vehicle, said system comprising: a hydraulic pump unit including at least first and second fixed displacement pumps and a co

We claim: 1. An electro-hydraulic system for operating a hydraulic motor for a vehicle cooling fan and providing pressurized hydraulic fluid to a power steering system of the vehicle, said system comprising: a hydraulic pump unit including at least first and second fixed displacement pumps and a common drive shaft to drive each of said pumps; a hydraulic fluid reservoir fluidly connected to at least one inlet of said pumps and capable of providing sufficient hydraulic fluid for operation of said pump unit; an electro-hydraulic drive circuit adapted for hydraulic fluid connection to said hydraulic motor for operating said cooling fan, said drive circuit including an electro-hydraulic proportional control valve operatively connectible to said pump unit for controlling and limiting the operational speed of said hydraulic motor and further including a priority valve for providing a constant flow of hydraulic fluid to said power steering system, the operation of said priority valve being controlled by hydraulic pressure in said fan drive circuit during use of the electro-hydraulic system, wherein said proportional control valve is adapted for electrical connection to an electronic control device capable of electrically operating and controlling said proportional control valve from predetermined input variable readable by said control device, said variables including at least one temperature variable, said control device being capable of calculating an appropriate cooling fan speed, generating electrical control signals based on said calculation, and transmitting these control signals to said proportional control valve in order to direct said cooling fan towards a more appropriate speed for cooling, and wherein said priority valve is arranged to direct excess flow of hydraulic fluid, if any, from the pump unit so that said excess flow is combined with hydraulic fluid flow from said second pump in order to drive said hydraulic motor and operate said fan. 2. An electro-hydraulic system according to claim 1 wherein said drive circuit includes an unloading valve having an unloading valve inlet operatively connected to a hydraulic line of the drive circuit that is extendible between an outlet of said second pump and said hydraulic motor, said unloading valve also having an unloading valve outlet connectible so as to provide hydraulic fluid flow to an inlet of said pump unit, said unloading valve during use of the system moving to an open position to allow hydraulic fluid from said second pump to flow to the inlet of the pump unit upon receipt of a predetermined amount of hydraulic pressure feedback from said hydraulic motor. 3. An electro-hydraulic system according to claim 1 including said electronic control device which is an electronic controller electrically connected to said proportional control valve. 4. An electro-hydraulic system according to claim 1 wherein said priority valve is arranged in said drive circuit between a first hydraulic fluid passage connectible to an outlet of said hydraulic motor and a second hydraulic fluid passage connected to a return flow inlet of said reservoir. 5. An electro-hydraulic system according to claim 1 wherein said priority valve is arranged in said drive circuit so that the priority valve is operatively connected to said first pump and is connectible to an inlet of said hydraulic motor. 6. An electro-hydraulic system according to claim 3 wherein said fluid reservoir is pressurized during use of the electro-hydraulic system and is provided with a pressure limiting valve. 7. An electro-hydraulic system according to claim 6 including a hydraulic fluid filter arranged in a filter housing, wherein hydraulic fluid returning from said drive circuit is first filtered by said filter and then returned to said fluid reservoir during use of the system. 8. An electro-hydraulic system according to claim 1 wherein said pump unit includes a third fixed displacement pump which in use is driven by said drive shaft and said drive circuit includes a second electro-hydraulic proportional control valve operatively connected to said third pump and said reservoir, wherein said second proportional control valve is also adapted for electrical connection to said electronic control device which is also capable of electrically operating and controlling said second proportional control valve from said predetermined input variables read by said control device. 9. An electro-hydraulic system according to claim 1 wherein said hydraulic motor is a variable displacement motor controlled by a hydraulic displacement control unit which is in turn operated and controlled by said proportional control valve. 10. An electro-hydraulic system according to claim 5 wherein said hydraulic motor is a variable displacement motor controlled by a hydraulic displacement control unit which is in turn operated and controlled by said proportional control valve. 11. An electro-hydraulic system according to claim 2 wherein said fluid reservoir is pressurized during use of the electro-hydraulic system and is provided with a pressure limiting valve and said electro-hydraulic system includes said electronic control device which is an electronic controller electrically connected to said proportional control valve. 12. An electro-hydraulic system for operating a hydraulic motor for a vehicle cooling fan and providing pressurized hydraulic fluid to a power steering system for the vehicle, said electro-hydraulic system comprising: a hydraulic pump arrangement having at least first and second fixed displacement pumps, each of which has an inlet and an outlet, and a common drive shaft connectible to a power source and connected to drive said pumps; a hydraulic fluid reservoir fluidly connected to at least one of the inlets of the pumps and capable of providing sufficient hydraulic fluids for operation of said pumps, said fluid reservoir being pressurized during use of the system; an electro-hydraulic drive circuit for connection both to said hydraulic motor for operating said cooling fan and said power steering system, said drive circuit including an electro-hydraulic proportional control valve operatively connectible to said pump arrangement for controlling and limiting the operational speed of said hydraulic motor and further including a priority valve for providing a constant flow of hydraulic fluid to said power steering system, the operation of said priority valve being controlled by hydraulic pressure in said drive circuit during use of the system, wherein said proportional control valve is adapted for electrical connection to an electronic control device capable of electrically operating and controlling said proportional control valve from predetermined input variables readable by said control device, said variables including at least one temperature variable, said control device being capable of calculating an appropriate cooling fan speed, generating electrical control signals based on said calculations, and transmitting these control signals to said proportional control valve in order to direct said cooling fan towards a more appropriate speed for cooling, and wherein, during use of the system, said priority valve is able to combine any excess flow of hydraulic fluid from the pump arrangement over the flow required by the power steering system with hydraulic fluid flow from said second pump in order to drive said hydraulic motor and operate said fan. 13. An electro-hydraulic system according to claim 12 wherein said drive circuit includes an unloading valve having an unloading valve inlet operatively connectible to said outlet of the second pump and an unloading valve outlet operatively connectible to said inlet of said first pump for hydraulic fluid flow therebetween, said unloading valve during use of the system moving to an open position to allow hydraulic fluid from said second pump to flow to the inlet of the first pump upon receipt of a predetermined amount of hydraulic pressure feedback from said hydraulic motor. 14. An electro-hydraulic system according to claim 13 wherein an inlet port of said priority valve is operatively connected to the outlet of said first pump, a first outlet of said priority valve is connectible to said power steering system and a second outlet of said priority valve is connectible to an inlet port of said hydraulic motor. 15. An electro-hydraulic system according to claim 14 wherein said drive circuit includes a pressure relief valve operatively connected to said first outlet of said priority valve and capable of providing hydraulic pressure relief at a selected maximum pressure to protect said power steering system and wherein said fluid reservoir also has a pressure limiting valve. 16. An electro-hydraulic system according to claim 15 wherein an inlet of said proportional control valve is operatively connected to said second outlet of said priority valve and is connectible to said inlet port of said hydraulic motor and an outlet of said proportional control valve is operatively connected to a return flow inlet of the reservoir. 17. An electro-hydraulic system according to claim 16 wherein said drive circuit includes a suction relief valve having an outlet port connected to said fluid reservoir and an inlet operatively connected to the inlet of said first pump, said suction relief valve during use of the system acting to limit hydraulic fluid flow to said first pump. 18. An electro-hydraulic system according to claim 12 including said electronic control device which is an electronic controller electrically connected to said proportional control valve. 19. An electro-hydraulic system according to claim 16 including said electronic control device which is an electronic controller electronically connected to said proportional control valve, wherein said electronic controller includes a power supply regulator, a microcontroller chip that includes an analog-to-digital converter, temperature sensor signal conditioning circuitry for three temperature inputs, auxiliary digital input signal voltage limiting and transient protection circuitry, and power output circuitry. 20. An electro-hydraulic system for operating a vehicle cooling fan and providing pressurized hydraulic fluid to a power steering circuit, said electro-hydraulic system comprising: a hydraulic pump arrangement having at least first and second fixed displacement pumps, each having a fluid inlet and a fluid outlet, and a drive shaft connectible to a power source and connected to drive said pumps; a hydraulic fluid reservoir fluidly connected to the inlets of said pumps and capable of containing and providing sufficient hydraulic fluid for operation of said pumps; an electro-hydraulic drive circuit for hydraulic fluid connection to said pump arrangement, said hydraulic motor, and said power steering circuit, said drive circuit including an electro-hydraulic proportional control valve operatively connected to said second pump for controlling and limiting the operation of said hydraulic motor, and further including a priority valve for providing a constant flow of hydraulic fluid to said power steering circuit, the operation of said priority valve being controlled by hydraulic pressure in said drive circuit during use of said system, said priority valve being arranged in said drive circuit so as to be operatively connected between an outlet of said hydraulic motor and said power steering circuit, wherein said proportional control valve is adapted for electrical connection to an electronic control device capable of electrically operating and controlling said proportional control valve from predetermined input variables readable by said control device, said variables including at least one temperature variable, said control device being capable of calculating an appropriate cooling fan speed, generating electrical control signals based on said calculations, and transmitting these control signals to said proportional control valve in order to direct said cooling fan towards a more appropriate speed for cooling, and wherein, during use of the system, said priority valve returns any excess flow of hydraulic fluid over the flow required by the power steering system to said fluid reservoir. 21. An electro-hydraulic system according to claim 20 wherein said priority valve is arranged in said drive circuit between a first hydraulic fluid passage of said drive circuit connected to an outlet of said hydraulic motor and a second hydraulic fluid passage connectible to said power steering circuit. 22. An electro-hydraulic system according to claim 20 wherein said priority valve has a priority valve inlet and first and second priority valve outlets and is arranged in said drive circuit so that said first priority valve outlet is operatively connectible to said power steering circuit and said second priority valve outlet is connected to said fluid reservoir. 23. An electro-hydraulic system according to claim 21 wherein said fluid reservoir is pressurized during use of the electro-hydraulic system and is provided with a pressure limiting valve and said drive circuit includes a pressure relief valve operatively connected to an outlet of said priority valve and capable of providing hydraulic pressure relief at a selected maximum pressure to protect said power steering circuit. 24. An electro-hydraulic system according to claim 22 wherein said fluid reservoir is pressurized during use of the electro-hydraulic system and is provided with a pressure limiting valve and said drive circuit includes a pressure relief valve operatively connected to said first priority valve outlet and capable of providing hydraulic pressure relief at a selected maximum pressure to protect said power steering circuit. 25. An electro-hydraulic system according to claim 21 including said electronic control device which is an electronic controller electrically connected to said proportional control valve. 26. An electro-hydraulic system according to claim 22 including said electronic control device which is an electronic controller electrically connected to said proportional control valve.