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US 6,314,729 B1Granted
Hydraulic fan drive system having a non-dedicated flow source
AssigneeSauer-Danfoss Inc.
InventorsStanley W. Crull, Mark A. Peterson
Life of this patent
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AssigneeSauer-Danfoss Inc.
InventorsStanley W. Crull, Mark A. Peterson
Estimating the term…
A specific type of hydraulic fan drive system is provided for engine drive machines, such as on road and off road machines, such as buses, construction equipment, agricultural equipment, and so on. The hydraulic fan drive systems turn a cooling fan (39) which provides airflow to cool the engine on such machines. This system uses a proportional pressure reducing valve (34) (or combination of valves providing a pressure reducing function) between the pump (12) and the fan motor (38). This valve (34) or (combination of valves) controls the pressure drop across the fan motor (38) based on a control signal from an electronic controller (50). The valve allows as little or as much flow to pass as is required to maintain this pressure drop at the load (the fan motor (38)).
A hydraulic fan drive system, comprising, a fan coupled to a fan hydraulic motor, a single hydraulic purnp connected to the fan hydraulic motor and having a pressure outlet flow capability greater than the fluid flow required to operate the fan motor at the normal operating speed, a pressure reduction valve connected to a pressure flow outlet line of the pump upstream of the fan hydraulic motor, an electronic controller operatively connected to the pressure reduction valve to control the fluid pressure therethrough, a plurality of temperature sensitive bodies associated with the system, a signal emitting sensor associated with at least some of the bodies and connected to the controller to transmit an electronic signal to the controller relative to the temperature of the body from which it extends, whereby the controller can adjust the fluid pressure to the fan motor through the pressure reduction valve to increase or decrease the speed of the fan to accommodate the temperature needs of the bodies which the controller determines;
A hydraulic fan drive system, comprising, a fan coupled to a fan hydraulic motor and having the capability of operating at variable speeds up to a maximum speed, a single hydraulic pump connected to the fan hydraulic motor and having a pressure outlet flow capability greater than the fluid flow required to operate the fan motor at the maximum operating speed, a pressure reduction valve connected to a pressure flow outlet line of the pump upstream of the fan hydraulic motor, an electronic controller operatively connected to the pressure reduction valve to control the fluid pressure therethrough to the fan hydraulic motor, at least one functional hydraulic work circuit connected to the pressure outlet flow of the pump in addition to the fan hydraulic motor, a load sensor circuit connected to the pump, the work circuit, and to the pressure outlet of the pump at a location between the fan and pressure reduction valve so that if the work circuit requires more pressure than the fan hydraulic motor, the pump will produce such additional fluid pressure to the work circuit, and the pressure to the fan motor will be reduced;
Dependencies are inferred from the claim text.