Fuel controller for an internal combustion engine

Claim 1

A fuel controller for an internal combustion engine which is equipped with a gas recovery passageway which returns blow-by gas from the engine to an air intake pipe, said fuel controller comprising: a Karman vortex air flow sensor which generates electrical output pulses having a frequency corresponding to the rate at which air flows into an air intake pipe of the engine; crank angle sensing means for generating an electrical output pulse at one or more prescribed crank angles of the engine; a load sensor which generates an electrical output signal AN.sub.(t) corresponding to the number of output pulses which were generated by said air flow sensor between a prescribed number of output pulses of said crank angle sensing means; determining means responsive to said load sensor for determining if the output of said air flow sensor is reliable and generating a corresponding output signal; calculating means responsive to said determining means and said load sensor for calculating the actual rate of air intake into the engine each time said load sensor generates an output signal and generating a corresponding output signal AN(n) having the value AN.sub.(n) =K×AN.sub.(n-1) +(1-K)×AN.sub.(t) when said determining means determines that the output of said air flow sensor is reliable and having the value AN.sub.(n) =AN.sub.(n-1) -Y when said determining means determines that the output of said air flow sensor is not reliable, wherein AN.sub.(n-1) is the value of the output signal which was generated by the calculating means the previous time that said load sensor generated an output signal and K and Y are constants; and a controller for controlling the supply of fuel to fuel injectors of the engine on the basis of the output signal AN.sub.(n) of the calculating means.