Electronically controlled valve for a materials handling vehicle
First Claim
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1. A materials handling vehicle comprising:
- a base;
a carriage assembly movable relative to said base;
at least one cylinder coupled to said base to effect movement of said carriage assembly relative to said base;
a hydraulic system to supply a pressurized fluid to said cylinder, said hydraulic system including an electronically controlled valve coupled to said cylinder; and
control structure to control the operation of said valve such that said valve is closed in the event of an unintended descent of a carriage assembly in excess of a commanded speed.
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Abstract
A materials handling vehicle is provided comprising: a base; a carriage assembly movable relative to the base; at least one cylinder coupled to the base to effect movement of the carriage assembly relative to the base; and a hydraulic system to supply a pressurized fluid to the cylinder. The hydraulic system includes an electronically controlled valve coupled to the cylinder. The vehicle further comprises control structure to control the operation of the valve such that the valve is closed in the event of an unintended descent of a carriage assembly in excess of a commanded speed.
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Citations
21 Claims
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1. A materials handling vehicle comprising:
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a base; a carriage assembly movable relative to said base; at least one cylinder coupled to said base to effect movement of said carriage assembly relative to said base; a hydraulic system to supply a pressurized fluid to said cylinder, said hydraulic system including an electronically controlled valve coupled to said cylinder; and control structure to control the operation of said valve such that said valve is closed in the event of an unintended descent of a carriage assembly in excess of a commanded speed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A materials handling vehicle comprising:
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a base; a carriage assembly movable relative to said base; at least one cylinder coupled to said base to effect movement of said carriage assembly relative to said base; a hydraulic system to supply a pressurized fluid to said cylinder, said hydraulic system including an electronically controlled valve coupled to said cylinder; and control structure to control the operation of said valve such that said valve is closed in the event of an unintended descent of said carriage assembly in excess of a commanded speed and a predefined speed. - View Dependent Claims (17)
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18. A materials handling vehicle comprising:
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a base; a carriage assembly movable relative to said base; at least one cylinder coupled to said base to effect movement of said carriage assembly relative to said base; a hydraulic system to supply a pressurized fluid to said cylinder, said hydraulic system including an electronically controlled valve coupled to said cylinder; control structure to control the operation of said valve such that said valve is closed in the event of a loss of pressure in the fluid being supplied by said hydraulic system to said valve, said control structure being capable of energizing said valve so as to open said valve to permit said carriage assembly to be lowered in a controlled manner to a desired position relative to said base, and said control structure acting to de-energize said valve when said carriage assembly is not being lowered in a controlled manner relative to said base; and wherein said valve functions as a check valve when de-energized so as to block pressurized fluid from flowing out of said cylinder, and allowing pressurized fluid to flow into said cylinder during a carriage assembly lift operation.
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19. A materials handling vehicle comprising:
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a base; a carriage assembly movable relative to said base; at least one cylinder coupled to said base to effect movement of said carriage assembly relative to said base; a hydraulic system to supply a pressurized fluid to said cylinder, said hydraulic system including an electronically controlled valve coupled to said cylinder; and control structure to control the operation of said valve such that said valve is closed in the event of a loss of pressure in the fluid being supplied by said hydraulic system to said valve, said control structure comprising; an encoder unit associated with said carriage assembly for generating encoder pulses as said carriage assembly moves relative to said base; and a controller coupled to said encoder unit and said valve for receiving said encoder pulses generated by said encoder unit and monitoring the rate of descent of said carriage assembly based on said received encoder pulses, said controller functioning to de-energize said valve causing it to move from its powered open state to its closed state in the event said carriage assembly moves downwardly in an unintended manner at a speed in excess of a commanded speed. - View Dependent Claims (20)
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21. A materials handling vehicle comprising:
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a base; a carriage assembly movable relative to said base; at least one cylinder coupled to said base to effect movement of said carriage assembly relative to said base; a hydraulic system to supply a pressurized fluid to said cylinder, said hydraulic system including an electronically controlled valve coupled to said cylinder; and control structure to control the operation of said valve such that said valve is closed in the event of an unintended descent of a carriage assembly in excess of a fixed threshold speed.
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Specification