Air-to-fuel ratio control system for internal combustion engines
First Claim
1. An air-to-fuel ratio control system for internal combustion engines comprising:
- a carburetor, positioned upstream of an engine of a vehicle and having a throttle valve therein, for supplying said engine with air-fuel mixture corresponding to the opening angle of said throttle valve;
a speed detector for generating a speed voltage indicative of the speed of said vehicle;
a pressure detector, provided in an intake passage connecting said carburetor with said engine, for generating a pressure voltage indicative of the pressure in said intake passage;
an oxygen detector, provided in the exhaust passage of said engine, for generating an oxygen voltage indicative of the air-to-fuel ratio of the mixture supplied to said engine;
a speed function generator, connected to be responsive to said speed voltage, for generating a speed function voltage the level of which is constant while the speed of said vehicle is lower than a lower preset speed and is higher than a higher preset speed;
a pressure function generator, connected to be responsive to said pressure voltage, for generating a pressure function voltage which varies in accordance with the pressure in said intake passage;
an oxygen function generator, connected to be responsive to said oxygen voltage, for generating an oxygen function voltage which varies in accordance with the air-to-fuel ratio of said mixture;
a selection circuit, adapted to select one of said pressure function voltage and said oxygen function voltage in response to the level of said speed function voltage, said selection circuit selecting said oxygen function voltage while the speed of said vehicle is lower than said lower preset speed and said pressure function voltage while the speed of said vehicle is higher than said higher preset speed; and
an air addition passage, positioned to by-pass said carburetor and connected to be responsive to the function voltage selected by said selection circuit, for supplying said engine with air to thereby control the air-to-fuel ratio of said mixture in response to the speed of said vehicle, the amount of said air being controlled by said oxygen function voltage and said pressure function voltage while the speed of said vehicle is lower and higher than said respective lower preset speed and higher preset speed, respectively.
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Abstract
A desired function signal is provided by a logical circuit which selects one of a signal corresponding to the speed of a vehicle carrying an internal combustion engine, a signal corresponding to the intake pressure, a signal corresponding to the air-to-fuel ratio of the mixture supplied to the engine, and a signal corresponding to the opening of a throttle valve in accordance with the driving conditions of the vehicle. The amount of additional intake air flowing through an additional intake system provided in the engine is controlled in accordance with the desired function signal, thus providing an air-fuel mixture ratio which suits the driving conditions of the vehicle, the running speed of the vehicle in particular.
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Citations
9 Claims
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1. An air-to-fuel ratio control system for internal combustion engines comprising:
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a carburetor, positioned upstream of an engine of a vehicle and having a throttle valve therein, for supplying said engine with air-fuel mixture corresponding to the opening angle of said throttle valve; a speed detector for generating a speed voltage indicative of the speed of said vehicle; a pressure detector, provided in an intake passage connecting said carburetor with said engine, for generating a pressure voltage indicative of the pressure in said intake passage; an oxygen detector, provided in the exhaust passage of said engine, for generating an oxygen voltage indicative of the air-to-fuel ratio of the mixture supplied to said engine; a speed function generator, connected to be responsive to said speed voltage, for generating a speed function voltage the level of which is constant while the speed of said vehicle is lower than a lower preset speed and is higher than a higher preset speed; a pressure function generator, connected to be responsive to said pressure voltage, for generating a pressure function voltage which varies in accordance with the pressure in said intake passage; an oxygen function generator, connected to be responsive to said oxygen voltage, for generating an oxygen function voltage which varies in accordance with the air-to-fuel ratio of said mixture; a selection circuit, adapted to select one of said pressure function voltage and said oxygen function voltage in response to the level of said speed function voltage, said selection circuit selecting said oxygen function voltage while the speed of said vehicle is lower than said lower preset speed and said pressure function voltage while the speed of said vehicle is higher than said higher preset speed; and an air addition passage, positioned to by-pass said carburetor and connected to be responsive to the function voltage selected by said selection circuit, for supplying said engine with air to thereby control the air-to-fuel ratio of said mixture in response to the speed of said vehicle, the amount of said air being controlled by said oxygen function voltage and said pressure function voltage while the speed of said vehicle is lower and higher than said respective lower preset speed and higher preset speed, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An air-to-fuel ratio control system for internal combustion engines comprising:
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a carburetor, positioned in an intake passage of an engine of a vehicle and having a throttle valve, for supplying said engine with air-fuel mixture corresponding to the opening angle of said throttle valve; a speed detector for generating a speed signal indicative of the vehicle speed; an air-to-fuel ratio detector, provided in the exhaust passage of said engine, for generating a ratio signal indicative of the air-to-fuel ratio of said mixture supplied to said engine; a pressure detector, provided in said intake passage, for generating a pressure signal indicative of the pressure in said intake passage; a function signal generator, connected to said detectors, for generating a function signal which corresponds to said ratio signal during a predetermined lower vehicle speed range, to one of said ratio and pressure signals during a predetermined medium vehicle speed range, and to said pressure signal during a predetermined higher vehicle speed range; and an auxiliary intake passage, provided to supply the air into said intake passage at the downstream of said carburetor, for controlling the air-to-fuel ratio of said mixture in response to said function signal, whereby the air-to-fuel ratio of said mixture is switched in response to said speed of said vehicle. - View Dependent Claims (9)
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Specification