Method and apparatus for measuring air quantity in relation to engine speed

Claim 1

Apparatus for measuring the quantity of air supplied to an internal combustion engine in relation to the speed of rotation of said engine, said engine being adapted to operate under varying load conditions which result in a greater range of variations in the quantity of said supplied air than the range of variations of said engine speed, comprising: means for generating first electrical pulses, the repetition of frequency of which is proportionally related to the rate of air supplied to said engine; means for generating second electrical pulses, the repetition frequency of which is proportionally related to the speed of rotation of said engine and higher than the frequency of said first electrical pulses; counting means for counting the number of said second electrical pulses in response to each of said first pulses; computing means for computing the reciprocal of said counted number of said second electrical pulses to measure said quantity of air supplied to said engine in relation to said engine rotation speed; a first monostable device for generating an output signal in response to said first electrical pulses; a second monostable device connected to the output of said first monostable device to generate an output signal in response to an edge of the output signal from said first monostable device; and a latching circuit responsive to the output signal of said first monostable device for storing the contents of said counting means until the subsequent occurrence of an output signal from said first monostable device; and wherein said counting means is responsive to each of the output signals from said second monostable device to start counting said second electrical pulses.