Patent ID: 6016832
Filing Date: 2000-01-25
Classification: F02D,F02M,Y02T,Y10T

Abstract:
A gas fuel metering valve for metering gas mass flow to an internal combustion engine, said valve having no mass flow sensor but adapted to respond to an electrical signal proportional to a desired gas mass flow rate to produce an actual gas mass flow rate corresponding to the electrical signal, the metering valve comprising:a housing having an inlet port and an outlet port and a flow passage therebetween, said outlet port adapted to communicate with said engine;a nozzle mounted in the housing in said flow passage, said nozzle having a converging inlet and a diffusing outlet;a flow control element coaxial with said nozzle and mounted for controllable positioning in said nozzle to control the flow therethrough;an electrical actuator connected to said flow control element for positioning said flow control element;a gas pressure sensor in said housing, said sensor having a sensing element in said flow passage between said housing inlet port and said nozzle inlet for producing an electrical signal relating to gas pressure;a gas temperature sensor in said housing, said sensor having a sensing element in said flow passage between said housing inlet port and said nozzle inlet for producing an electrical signal relating to gas temperature;a position sensor in said housing, said sensor linked to said flow control element for producing an electrical signal relating to the position of said flow control element; andan electronic circuit having a microprocessor and software mounted in said housing, said microprocessor adapted to receive said electrical signal proportional to said desired mass flow and said signals from said gas pressure sensor, said gas temperature sensor and said position sensor, said electronic circuit having an output connected to said actuator and being adapted to produce an output signal to control said actuator to produce a mass flow dependent on said signals received by said microprocessor; andwherein said flow control element is a needle contoured to promote diffusion, said needle having a first end connected to said electrical actuator, an elongate portion having a constant diameter therealong, and a contoured tip portion having a converging diameter at a second end thereof, said elongate portion being of greater length than said tip portion, said tip portion extending into said diffusing outlet; andwherein said valve has a discharge pressure and wherein said flow control member is positioned in said nozzle to maintain sonic flow through said housing at discharge pressure to supply pressure ratios substantially above the critical pressure ratio for said fuel being flowed.