FUEL VAPOR PRESSURE SENSOR BY SOUND WAVE, AND FUEL INJECTION CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a fuel vapor pressure sensor taking advantage of a univocal correlation being present between a sound wave and a fuel vapor pressure regardless of temperature change.;SOLUTION: An ultrasonic transmitter receiver 53 of an ultrasonic sensor 50 is driven by a driving circuit 63 and transmits an ultrasonic wave into gasoline. When the ultrasonic wave is reflected by a low wall 51d of a cylinder 51, the ultrasonic transmitter receiver 53 receives the reflected ultrasonic wave and generates a received signal. An amplifying circuit 64 amplifies the received signal and generates an amplified signal. A comparator 65 compares the amplified signal with a reference voltage of a reference voltage setter 65a. A propagating time counter 66 counts an output rising time of the comparator 65 after the transmission of the ultrasonic wave by the ultrasonic sensor 50. A microcomputer 67 computes the speed of the ultrasonic wave based on the counted value of the propagating time counter 66, and determines the vapor pressure based on data showing the relationship between gasoline vapor pressure and ultrasonic wave speed.;COPYRIGHT: (C)2001,JPO