Patent ID: 6394206
Filing Date: 2002-05-28
Classification: B60K,F04B,H02K,H02P

Abstract:
Apparatus for driving a generator carried aboard a motor vehicle having an engine and a power take-off at a constant speed despite fluctuations in rotational speed of the engine, comprising:a hydraulic pump connectable to the power take-off to be driven thereby, having an inlet disposed to receive fluid for pumping and an outlet for discharging pumped fluid under pressure; a hydraulic motor drivably connectable to the generator, having an inlet disposed to receive fluid under pressure and an outlet disposed to discharge spent fluid; a fluid circuit comprising a supply conduit disposed to conduct fluid discharged by said pump to said motor, a return conduit disposed to return fluid discharged by said motor to said pump, and a recirculating conduit disposed to return fluid discharged by said pump to said inlet of said pump; a proportional control valve assembly disposed serially with respect to said supply conduit and interposed between said outlet of said pump and said inlet of said motor, said control valve assembly having a housing having a valve chamber, a valve disposed within said valve chamber, a solenoid disposed to move said valve within said valve chamber, a first fluid passage disposed in fluid communication with said valve chamber, a second fluid passage disposed in communication with said valve chamber, wherein said valve selectively closes and opens said first fluid passage and said second fluid passage, wherein said first fluid passage of said valve assembly is disposed within said supply conduit and said second fluid passage of said valve assembly is connected in fluid communication with said return conduit, and wherein said first fluid passage is dimensioned and configured such that said first fluid passage is of the minimum cross sectional surface area occurring within said supply conduit, and said second fluid passage is dimensioned and configured such that said second fluid passage is dimensioned and configured such that said second fluid passage is of the minimum cross sectional surface area occurring within said return conduit; and a control circuit disposed to control said valve assembly such that said valve assembly controls fluid flow within said first fluid outlet of said valve assembly and said second fluid outlet of said valve assembly, wherein said control circuit includes a sensor disposed to sense rotational speed of said motor, a reference signal generator disposed to generate a reference signal indicative of a predetermined rate of rotation, and a comparing subcircuit disposed to compare sensed rotational speed of said motor with said reference signal, and to generate a control signal controlling said valve assembly in a manner assuring that rate of fluid conducted to said supply conduit be constant independently of rate of fluid discharged by said pump.