Hydraulically powered fan system for vehicles

Claim 2

A control system for first and second hydraulic devices in a vehicle which contains a hydraulic pump, comprising: a) a first valve for receiving fluid from the pump, and delivering flow at a rate controlled by a control signal; b) a second valve for allocating said flow between said devices, based on predetermined operating conditions of the first valve: wherein the second valve comprises: i) a first port which senses input pressure of the first hydraulic device; ii) a second port which senses pressure at an output of the pump; and iii) a pintle which diverts flow from the first hydraulic device to the second hydraulic device, when pressures in the first and second ports reach a predetermined difference; and wherein said first and second valves cooperate to cause said first and second hydraulic devices to be off when an output from a pump is low and a cooling demand is zero.

Claim 3

A control system for first and second hydraulic devices in a vehicle which contains a hydraulic pump, comprising: a) a first valve for receiving fluid from the pump, and delivering flow at a rate controlled by a control signal; b) a second valve for allocating said flow between said devices, based on predetermined operating conditions of the first valve; wherein the second valve comprises: i) a first port which senses input pressure of the first hydraulic device; ii) a second port which senses pressure at an output of the pump; and iii) a pintle which diverts flow from the first hydraulic device to the second hydraulic device, when pressures in the first and second ports reach a predetermined difference; wherein said first and second valves cooperate to cause said first and second hydraulic devices to be on when a cooling demand is small.

Claim 4

A control system for first and second hydraulic devices in a vehicle which contains a hydraulic pump, comprising: a) a first valve for receiving fluid from the pump, and delivering flow at a rate controlled by a control signal; b) a second valve for allocating said flow between said devices, based on predetermined operating conditions of the first valve; wherein the second valve comprises: i) a first port which senses input pressure of the first hydraulic device; ii) a second port which senses pressure at an output of the pump; and iii) a pintle which diverts flow from the first hydraulic device to the second hydraulic device, when pressures in the first and second ports reach a predetermined difference; wherein said first and second valves cooperate to cause said first and second hydraulic devices to be on when a cooling demand is small.

Claim 5

The control system as recited in claim 2 wherein said first and second valves cooperate to cause said first and second hydraulic devices to be on when said pump output is high, and said cooling demand is large.

Claim 6

The control system as recited in claim 2 wherein said first and second valves cooperate to cause said first hydraulic device to be on and said second hydraulic device to be off when said pump output is low and said cooling demand is large.

Claim 7

The control system as recited in claim 4 wherein said output is less than 0.5 gpm.

Claim 8

The control system as recited in claim 2 wherein said first and second hydraulic devices are hydraulic motors.

Claim 9

The control system as recited in claim 6 wherein said first and second hydraulic devices are coupled to a common shaft driving a fan blade.

Claim 10

The control system as recited in claim 2 wherein said first and second valves cooperate to cause said first hydraulic device to be on and said second hydraulic device to be modulated when said pump output is low and said cooling demand is medium.

Claim 11

The control system as recited in claim 8 wherein said output is less than 0.5 gpm.

Claim 12

A control system for first and second hydraulic devices in a vehicle which contains a hydraulic pump, comprising: a first valve for receiving fluid from the pump, and delivering flow at a rate controlled by a control signal; a second valve for allocating said flow between said devices, based on predetermined operating conditions of the first valve; wherein said system causes said first and second hydraulic devices operate in accordance with the following logic: ______________________________________ First Hydraulic Second Hydraulic Pump Output Cooling Demand Device Device ______________________________________ Low Zero Off Off Low Small On On Low Medium On Modulated Low Large On Off High Zero Off Off High Small On On High Large On On. ______________________________________

Claim 13

A control system for first and second hydraulic devices in a vehicle which contains a hydraulic pump, comprising: a first valve for receiving fluid from the pump, and delivering flow at a rate controlled by a control signal; a second valve for allocating said flow between said devices, based on predetermined operating conditions of the first valve; wherein said system causes said first and second hydraulic devices operate in accordance with the following logic: ______________________________________ First Hydraulic Second Hydraulic Pump Output Cooling Demand Device Device ______________________________________ Low Zero Off Off Low Small On On Low Medium On Modulated Low Large On Off High Zero Off Off High Small On On High Large On On. ______________________________________