Electronic control system

Patent metadata

Field	Value
Publication number	US-9523621-B2
Application number	US-201313793450-A
Country	US
Kind code	B2
Filing date	Mar 11, 2013
Priority date	Apr 12, 2012
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

An electronic control system includes a microcomputer and a signal processing circuit, and receives output signals of an in-cylinder pressure sensor and a crank angle sensor. The output signal of the pressure sensor indicates an output voltage of a piezoelectric transducer and a reference voltage. The signal processing circuit includes a hold circuit and a differential amplifier circuit. The differential amplifier circuit amplifies a difference between the output signal of the pressure sensor and the output signal of the hold circuit and outputs the result to the microcomputer. The hold circuit switches over the output signals in response to a switchover instruction of the microcomputer. When the switchover instruction is a set instruction, the hold circuit holds as its output signal the output signal of the pressure sensor outputted at the time of receiving the set instruction. The microcomputer outputs the set instruction to the hold circuit in response to the output signal of the crank angle sensor.

First claim

What is claimed is:

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.

2. The electronic control system according to claim 1 , wherein:
the set timing is set to be immediately before a start of a compression stroke of the cylinder.

3. The electronic control system according to claim 1 , wherein:
the microcomputer is configured to detect that the cylinder is at a reset timing based on the angle signal of the crank angle sensor;
the microcomputer is configured to output a reset instruction to the hold circuit when the cylinder is detected as being at the reset timing;
the hold circuit is configured to output the pressure signal of the pressure sensor after the reset instruction is received until the set instruction is received again; and
the reset timing is set to be in an exhaust stroke or in a suction stroke of the cylinder.

4. The electronic control system according to claim 3 , wherein:
the microcomputer is configured to output the set instruction after a time delay from output of the reset instruction, the time delay being corresponding to a period required for the output voltage of the hold circuit to stabilize.

5. The electronic control system according to claim 1 , further comprising:
a bypass circuit provided to transmit the pressure signal of the pressure sensor to the microcomputer bypassing the signal processing circuit.

6. The electronic control system according to claim 1 , wherein:
the microcomputer is configured to apply the set instruction and the reset instruction to the hold circuit once in one combustion cycle of a suction stroke, a compression stroke, a combustion stroke and an exhaust stroke of the cylinder of the engine.

7. The electronic control system according to claim 1 , further comprising
a drift correction circuit that is configured to correct a drift in the pressure signal of the pressure sensor, that is located within the signal input circuit, and that includes the hold circuit and the differential amplification circuit.

8. 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 that is 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 and that is configured to
detect that a cylinder is at a predetermined timing based on the angle signal of the crank angle sensor,
control the hold circuit to output a hold signal, which corresponds to the pressure signal received immediately before a set instruction is applied to the hold circuit, until the cylinder is detected as being at the predetermined timing, the predetermined timing is set to be in an exhaust stroke or in a suction stroke of the cylinder, and
output the set instruction to the hold circuit based on the angle signal of the crank angle sensor, 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, and
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 the 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, 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.

9. The electronic control system according to claim 8 , further comprising
a drift correction circuit that is configured to correct a drift in the pressure signal of the pressure sensor, that is located within the signal input circuit, and that includes the hold circuit and the differential amplification circuit.

10. The electronic control system according to claim 8 , wherein the predetermined timing is set to be in an exhaust stroke of the cylinder.

11. The electronic control system according to claim 8 , wherein the predetermined timing is set to be in a suction stroke of the cylinder.

12. The electronic control system according to claim 8 , wherein
the predetermined timing is a reset

Assignees

• Denso Corp

Inventors

• Oomi Keita

Classifications

• F02D45/00

  Electrical control not provided for in groups F02D41/00 - F02D43/00 · CPC title

• F02D35/00

  Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for · CPC title

• G01L19/04 Primary

  Means for compensating for effects of changes of temperature {, i.e. other than electric compensation} · CPC title

• G01L23/10

  by pressure-sensitive members of the piezoelectric type · CPC title

• G01L9/085 Primary

  with temperature compensating means (non electric temperature compensating means G01L19/04) · CPC title