HYDRAULIC PUMP OPERATING DEVICE AND METHOD FOR USE IN HYDRAULIC SYSTEM
First Claim
1. A hydraulic pump operating device for use in a hydraulic system,the hydraulic system including:
- a variable speed motor;
a hydraulic pump driven by the variable speed motor; and
a pressure detector configured to detect a discharge pressure of the hydraulic pump,the hydraulic pump operating device comprising;
a pressure variation range detector configured to detect a range of variation of the discharge pressure detected by the pressure detector; and
a speed controller configured to control the speed of the variable speed motor based on the detected range of variation of the discharge pressure.
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Accused Products
Abstract
The rotational frequency of a variable speed motor is set to a normal rotational frequency setting value (N1). A pressure variation range (ΔP) is detected based on a pressure detection value P, of a variable displacement pump, detected by a pressure detector. It is determined whether a determination that the detected pressure variation range (ΔP) is less than or equal to a pressure maintained state detection level (L1) has been continuously given for a period indicated by a timer setting value (T1). If the determination that the detected pressure variation range (ΔP) is less than or equal to the pressure maintained state detection level (L1) has been continuously given for the predetermined period, then it is detected that the current state is a pressure maintained state, and the rotational frequency of the variable speed motor is switched from the normal rotational frequency setting value N1 to a pressure maintaining rotational frequency setting value (N2(<N1)).
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Citations
8 Claims
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1. A hydraulic pump operating device for use in a hydraulic system,
the hydraulic system including: -
a variable speed motor; a hydraulic pump driven by the variable speed motor; and a pressure detector configured to detect a discharge pressure of the hydraulic pump, the hydraulic pump operating device comprising; a pressure variation range detector configured to detect a range of variation of the discharge pressure detected by the pressure detector; and a speed controller configured to control the speed of the variable speed motor based on the detected range of variation of the discharge pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of operating a hydraulic pump in a hydraulic system,
the hydraulic system including: -
a variable speed motor; a hydraulic pump driven by the variable speed motor; and a pressure detector configured to detect a discharge pressure of the hydraulic pump, the method comprising; detecting, by a pressure variation range detector, a range of variation of the discharge pressure detected by the pressure detector; and controlling, by a speed controller, the speed of the variable speed motor based on the detected range of variation of the discharge pressure.
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Specification