Opto-sensor steering system for forklift truck
First Claim
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1. A steering system for a forklift truck comprising:
- a steering circuit;
an orbital steer unit having means for generating a dynamic load sensing signal;
means for maintaining a continuous idle flow of fluid through said orbital steer unit and said signal generating means;
a detector for detecting a steering demand, said detector including an optical sensor; and
means for increasing said flow of fluid in response to said steering demand,wherein said maintaining means includes a load-sensing priority valve connecting said pump to said steer unit, said valve being controlled by said signal generating means; and
said means for maintaining an idle flow maintains said idle flow of said fluid even when no steering demand is detected.
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Abstract
An electric forklift truck having a single motor which drives a pump which provides, via a priority valve, hydraulic fluid for both the working hydraulics and a steer unit on the truck. The motor is driven continuously at an idle speed in order to generate in the steer unit a dynamic load sensing signal to control the position of the priority valve. An optical sensor is associated with the steering column in order to provide an electric control signal to the motor controller to step up the speed of the motor in response to a steering demand.
23 Citations
17 Claims
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1. A steering system for a forklift truck comprising:
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a steering circuit; an orbital steer unit having means for generating a dynamic load sensing signal; means for maintaining a continuous idle flow of fluid through said orbital steer unit and said signal generating means; a detector for detecting a steering demand, said detector including an optical sensor; and means for increasing said flow of fluid in response to said steering demand, wherein said maintaining means includes a load-sensing priority valve connecting said pump to said steer unit, said valve being controlled by said signal generating means; and
said means for maintaining an idle flow maintains said idle flow of said fluid even when no steering demand is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A steering system for a forklift truck comprising;
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a motor; a pump driven by said motor which provides an idle flow of fluid; an orbital steer unit; a priority valve interconnecting said steer unit and said pump for receiving said idle flow, said priority valve being movable between various positions; working hydraulics; said orbital steer unit including means for outputting a dynamic load sensing signal for controlling the position of said priority valve, and said priority valve including a detector for detecting said dynamic load sensing signal and adjusting the position of said valve in response thereto, said priority valve being connected to said working hydraulics for said truck; a steering wheel; a steering column connecting said steering wheel to said steer unit; a plurality of markings located on said column; an optical sensor disposed adjacent to said column for detecting movement of said markings, said sensor generating a signal upon detecting said movement; a processor connected to said processor for receiving and processing said sensor signal, said processor including means for outputting a control signal; and a controller connected to said processor for receiving said control signal, said controller including an adjuster for adjusting speed of said motor in response to said control signal, such that said motor drives said pump to supply a sufficient amount of said fluid to said steer unit to meet a steering demand from said steering wheel for proper operation of said steer unit. - View Dependent Claims (14, 15, 16, 17)
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Specification