Back to results
US 4,290,107 AGranted
Electronic fuel control system for an internal combustion engine
AssigneeHitachi, Ltd.
InventorsSeiji Suda, Taiji Hasegawa, Yasunori Mouri, Toshio Furuhashi
Life of this patent
Estimating the term…
Abstract
A signal corresponding to the oxygen concentration in exhaust gas as detected by an O.sub.2 sensor is applied to a control logic circuit after analog conversion. The duty ratio of a pulse signal for keeping the optimum air-fuel ratio corresponding to a running state of an automobile is calculated by the use of the detection signal and in accordance with a program stored in a ROM in advance. The control pulse having the duty ratio is used for the switching control of a solenoid valve for regulating the air-fuel ratio of a mixture.
Claims11
A processor-based control apparatus for controlling the supply of fuel to an internal combustion engine comprising:
- regulation means for controlling the air-fuel ratio of a mixture of fuel and air to be supplied to said engine in response to a control signal applied thereto;
- first sensor means for producing a detection signal representative of the oxygen concentration in exhaust gas emitted from said engine;
- and
- a control unit, responsive to said detection signal produced by said first sensor means, for generating said control signal to be supplied to said regulation means, whereby said air-fuel ratio is controlled, said control unit comprising a processor unit and an input/output unit,
- said input/output unit comprising
- a register in which is stored data supplied by said processor unit representative of the duty cycle of said control signal,
- timing means for counting clock pulses supplied thereto and generating an output indicative of the count, and
- comparator means for comparing the count output of said timing means with the data stored in said register and producing said control signal in accordance with a prescribed relationship between the count output of said timing means and said stored data, and
- said processor unit is coupled to receive said detection signal and performs the following functions:
- (a) evaluating the maximum value and the minimum value of the detected signal capable of being produced by said first sensor means,
- (b) generating a signal representative of a threshold level V.sub.s intermediate said evaluated maximum and minimum values, in response to step (a), and
- (c) comparing said threshold level V.sub.s representative signal with said detected signal and generating data representative of said duty cycle in accordance with a predetermined relationship between said threshold level V.sub.s representative signal and said detected signal.
9 more elements
A processor-based control apparatus for controlling the supply of fuel to an internal combustion engine comprising:
- regulation means for controlling the air-fuel ratio of a mixture of fuel and air to be supplied to said engine in response to a control signal applied thereto;
- first sensor means for producing a detection signal representative of the oxygen concentration in exhaust gas emitted from said engine;
- a control unit, responsive to said detection signal produced by said first sensor means, for generating said control signal to be supplied to said regulation means, whereby said air-fuel ratio is controlled, said control unit comprising a processor unit and an input/output unit;
- and
- a current coupling path which couples current from said control unit to said first sensor means in order to control the response characteristics of said first sensor means;
- and wherein
- said input/output unit includes means for converting the detection signal into digital format so as to be compatible with data signals handled by said processor unit, and means for converting a prescribed data signal generated by said processor unit into analog format for providing a control current to be coupled over said current coupling path to said first sensor means, and
- said processor unit is coupled to receive said detection signal and performs the following functions:
- (a) evaluating the maximum value and the minimum value of the detected signal capable of being produced by said first sensor means,
- (b) generating a signal representative of a threshold level V.sub.s intermediate said evaluated maximum and minimum values, in response to step (a), and
- (c) comparing said threshold level V.sub.s representative signal with said detected signal and generating data representative of said duty cycle in accordance with a predetermined relationship between said threshold level V.sub.s representative signal and said detected signal.
8 more elements
A processor-based control apparatus for controlling the supply of fuel to an internal combustion engine comprising:
- regulation means for controlling the air-fuel ratio of a mixture of fuel and air to be supplied to said engine in response to a control signal applied thereto;
- first sensor means for producing a first detection signal representative of the oxygen concentration in exhaust gas emitted by said engine;
- second sensor means for generating pulses in accordance with the rotation of the engine crankshaft;
- third sensor means for producing a second detection signal representative of the negative suction pressure of a suction pipe of an engine cylinder;
- and
- a control unit, responsive to the pulses generated by said second sensor means and to the first and second detection signals produced by said first and third sensor means, for generating said control signal to be supplied to said regulation means, whereby the air-fuel ratio is controlled,
- said control unit comprising
- memory means for storing data representative of fluctuations in the air-fuel ratio versus quantity of suction air, and data representative of signals produced by said sensor means, and
- a processor unit coupled to said memory means, said processor performs the following functions:
- (a) generating, in response to pulses generated by said second sensor means and said second detection signal, first prescribed data representative of the quantity of suction air for said engine,
- (b) generating data representative of the duty cycle of said control signal associated with the air-fuel ratio determined in accordance with said first prescribed data,
- (e) evaluating the maximum value and the minimum value of said first detection signal capable of being produced by said first sensor means,
- (d) generating a signal representative of a threshold level V.sub.s intermediate said maximum and minimum values, in response to step (c), and
- (e) comparing said threshold level V.sub.s representative signal with said detected signal and generating data representative of a correction of said duty cycle-representative data generated in step (b) in accordance with a predetermined relationship between said threshold level V.sub.s representative signal and said detected signal.
11 more elements
Dependencies are inferred from the claim text.