Two-cycle engine with electronic fuel injection

Claim 1

A fuel injection system for a two-stroke cycle engine of the type comprising at least one cylinder, a crankcase associated with said cylinder, a piston reciprocally mounted in said cylinder and crankcase; a reciprocally openable and closable crankcase inlet for enabling combustible fluid to be drawn into the crankcase, a reciprocally openable and closable transfer port for transferring combustible fluid compressed in said crankcase to said cylinder, an ignition system for igniting compressed combustible fluid in said cylinder, a reciprocally openable and closable exhaust port in said cylinder for enabling exhaust of burned combustible fluid from said cylinder, a crankshaft connected to said piston for transferring mechanical energy from said piston to a drive unit, and an electrical energy supply source including a battery for operating the ignition system and other electrical components, comprising: (a) fuel injection means for injecting fuel for combustion within said cylinder; (b) fuel supply means for supplying fuel to said fuel injection means; (c) battery voltage sensing means for sensing battery voltage and for providing a battery voltage sensing signal representative thereof; (d) air temperature sensing means for sensing the temperature of ambient air and for providing an air temperature signal representative thereof; (e) engine speed sensing means for sensing the speed of revolution of said engine and for providing an engine speed signal representative thereof; (f) timing sensing means for sensing each occurrence of a predetermined cyclically repeating state of said engine and for providing a timing signal indicative thereof; (g) barometric pressure sensing means for sensing atmospheric air pressure and for generating a barometric pressure sensing signal representative thereof; (h) throttle position sensing means for sensing the relative amount of opening of .[.said.]. .Iadd.a .Iaddend.throttle valve means and for generating a throttle position signal representative thereof; (.Iadd.i.Iaddend.) engine temperature sensing means for sensing engine temperature and providing an engine temperature signal representative thereof; (.[.i.]..Iadd.j.Iaddend.) first data processing means for receiving and processing said sensing signals comprising: (i) means for processing said engine speed sensing signal and said throttle position sensing signal and for generating a priming control signals to said fuel injection means for selectively injecting or not injecting fuel into .[.said.]. .Iadd.a .Iaddend.manifold means based on said engine speed signal and said throttle position signal; (ii) means for receiving and processing said engine speed signal and throttle position signal for determining a base fuel injection value; (iii) means for receiving and processing said air temperature signal and calculating an air temperature modification value of said base fuel injection value; (iv) means for receiving and processing said barometric pressure sensing signal for calculating a barometric pressure modification value of said base fuel injection value; (v) means for receiving and processing .[.said.]. .Iadd.an .Iaddend.engine temperature signal for calculating an engine temperature modification value of said base fuel injection value; (vi) means for determining a total fuel injection value representative of the total fuel amount which is to be injected by said fuel injection means during a single two-stroke operating cycle of said piston from said base fuel injection value, said air temperature modification value, said barometric pressure modification value, and said engine temperature modification value; (vii) means for determining an injector open duration interval based on said total fuel injection value and a known fuel output rate capacity of said fuel injection means; (viii) means for generating a control signal for opening said injection means for said determined injector .Iadd.open .Iaddend.duration .[.open.]. interval at a predetermined point in time determined from said timing sensing signal; (ix) means for receiving and processing said engine speed sensing signal for generating a pump control signal in response thereto for maintaining .[.said.]. .Iadd.a .Iaddend.pump at an optimum operating speed for providing .[.said.]. .Iadd.a .Iaddend.predetermined maximum operating pressure in .[.said.]. .Iadd.a .Iaddend. fuel circulation conduit means at said pump. .Iadd.

Claim 7

A method of controlling the amount of fuel injected per at least one repetitive occurrence into a two-stroke cycle internal combustion engine having a fuel injector and throttle valve comprising the steps of: storing an array of values representing base fuel flow rates at predetermined engine operating parameters and conditions, selecting a base fuel flow rate value as a function of throttle valve position and engine rotational speed, modifying the base fuel flow rate value as a function of engine temperature, air temperature and barometric pressure to obtain a total fuel flow value, controlling the quantity of fuel injected per at least one repetitive occurrence in the engine in response to the total fuel flow value, sensing a predetermined cyclically repeating occurrence in the rotation of the engine, and controlling the occurrence of the fuel injector operation in response to the said sensing. .Iaddend.

Claim 8

A method of controlling the amount of fuel injected per at least one repetitive occurrence into a two-stroke cycle internal combustion engine having a fuel injector and throttle valve comprising the steps of: storing an array of values representing base fuel flow rates at predetermined engine operating parameters and conditions, selecting a base fuel flow rate value as a function of throttle valve position and engine rotational speed, modifying the base fuel flow rate value as a function of engine temperature, air temperature and barometric pressure to obtain a total fuel flow value, controlling the quantity of fuel injected per at least one repetitive occurrence in the engine in response to the total fuel flow value, sensing a predetermined cyclically repeating occurrence in the rotation of the engine, and controlling the occurrence of the fuel injector operation in response to the said sensing. .Iaddend.