Patent ID: 9523621
Filing Date: 2016-12-20
CPC Classification: F02D,G01L

Claim Text:
1. An electronic control system for an engine having a pressure sensor for outputting a pressure signal and a crank angle sensor for outputting an angle signal, the pressure signal being a difference between an output signal of a piezoelectric transducer and a reference voltage, the electronic control system comprising: a signal processing circuit that is connected to the pressure sensor for processing the pressure signal of the pressure sensor, and that includes a hold circuit and a differential amplification circuit; and a microcomputer connected to the signal processing circuit for controlling the engine based on the pressure signal processed by the signal processing circuit and the angle signal of the crank angle sensor, the microcomputer is configured to detect that a cylinder, on which the pressure sensor is mounted, is at a set timing based on the angle signal of the crank angle sensor, and to output a set instruction to the hold circuit when the cylinder is detected as being at the set timing, the set timing is set to be in a suction stroke of the cylinder, wherein the differential amplification circuit is configured to amplify a difference between the pressure signal of the pressure sensor and an output signal of the hold circuit and output an amplified difference signal to the microcomputer, the hold circuit is configured to switch over the output signal thereof based on a switchover instruction of the microcomputer, the hold circuit continues to output a hold signal under a state that the switchover instruction is the set instruction, the hold signal corresponding to the pressure signal received from the pressure sensor immediately before the set instruction is received, and the microcomputer is configured to output the set instruction to the hold circuit based on the angle signal of the crank angle sensor, wherein the pressure signal of the pressure sensor is a pressure detection start-time voltage, the microcomputer calculates a fuel injection start time based on the pressure detection start-time voltage, the cylinder cycles through a plurality of compression cycles, each of the plurality of compression cycles includes the suction stroke, a compression stroke, a combustion stroke, and an exhaustion stroke, and the hold circuit is configured to update the pressure detection start-time voltage during the suction stroke and before the cylinder enters the compression stroke of each compression cycle of the cylinder.