Constant speed hydrostatic drive system
First Claim
1. A constant speed generator drive system adapted for use with a variable speed engine comprising:
- a. a variable displacement hydraulic pump connected to a powered rotating shaft;
b. a hydraulic motor;
c. hydraulic lines operatively connecting said hydraulic motor to said hydraulic pump;
d. a drive shaft connecting said hydraulic motor to an electrical generator;
e. means for controlling the displacement of said hydraulic pump relative to the magnitude of a direct current signal applied thereto;
f. means for delivering a direct current signal to said displacement controlling means responsive to the hydraulic pressure in said hydraulic lines;
g. speed sensor means;
h. means for controlling the rotational speed of said drive shaft relative to said speed sensor means;
i. timing reference means; and
j. digital trim control means for adjusting said speed sensor means to correspond to said timing reference means.
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Accused Products
Abstract
A constant speed hydrostatic drive system is disclosed wherein a generator drive shaft is maintained at a constant speed by utilizing an electro-hydraulic controlled displacement pump responsive to a pressure transducer to control a hydraulic motor. A speed sensor is used to produce a direct current signal responsive to the drive shaft speed. The signal is converted into a series of voltage pulses also responsive to the shaft speed which are compared to a speed reference signal to provide a speed error signal. A loop gain control means is provided to utilize said speed error signal to adjust the shaft speed to coincide with said reference signal. A timing reference and digital trim control are also provided to compensate for long term drifting in the type speed control circuit described above.
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Citations
12 Claims
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1. A constant speed generator drive system adapted for use with a variable speed engine comprising:
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a. a variable displacement hydraulic pump connected to a powered rotating shaft; b. a hydraulic motor; c. hydraulic lines operatively connecting said hydraulic motor to said hydraulic pump; d. a drive shaft connecting said hydraulic motor to an electrical generator; e. means for controlling the displacement of said hydraulic pump relative to the magnitude of a direct current signal applied thereto; f. means for delivering a direct current signal to said displacement controlling means responsive to the hydraulic pressure in said hydraulic lines; g. speed sensor means; h. means for controlling the rotational speed of said drive shaft relative to said speed sensor means; i. timing reference means; and j. digital trim control means for adjusting said speed sensor means to correspond to said timing reference means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification