Electric air-to-fuel ratio control system
First Claim
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1. An air-to-fuel ratio control system for internal combustion engines comprising:
- a carburetor, provided in the intake passage of an engine of a vehicle, for supplying said engine with air-fuel mixture, said carburetor including a float chamber in which fuel is stored, a venturi at which said fuel is mixed with air, and a fuel passage which communicates said float chamber with said venturi;
a speed detector for generating a first signal indicative of the vehicle speed;
an air-to-fuel ratio detector, provided in the exhaust passage of said engine, for generating a second signal related to the air-to-fuel ratio of said mixture supplied to said engine;
a pressure detector, provided in said intake passage, for generating a third signal indicative of the pressure in said intake passage;
a frequency-to-voltage converter circuit connected to said speed detector, for generating a fifth voltage signal whose voltage corresponds to the frequency of said first signal;
a first vehicle-speed function voltage generator connected to said frequency-to-voltage converter circuit, for generating a sixth voltage signal related to the comparison of said fifth voltage signal to a first predetermined level;
a second vehicle-speed function voltage generator connected to said frequency-to-voltage converter circuit, for generating a seventh voltage signal related to the comparison of said fifth voltage signal to a second predetermined level;
a first logical circuit connected to said first vehicle-speed function voltage generator and said pressure detector, for generating a first logical output signal from said second sixth signal and said third signal;
a second logical circuit connected to said second vehicle-speed function voltage generator and said pressure detector, for generating a second logical output signal from said seventh voltage signal and said third signal;
a third logical circuit connected to said first logical circuit and said air-to-fuel ratio detector, for generating a third logical output signal from said first logical output signal and said second signal; and
a fourth logical circuit connected to said second and third logical circuits, for generating a fourth signal by logical operation on said second and third logical output signals so that said fourth signal corresponds to said second signal when the speed of said vehicle is less than a first predetermined value, to one of said second and third signals when the speed of said vehicle is between said first value and a second predetermined value greater than said first value and to said third signal when the speed of said vehicle is greater than said second value; and
electromagnetic valve means, connected to said function signal generator and provided in said fuel passage, for controlling the amount of fuel flowing therethrough in response to said fourth signal, whereby the air-to-fuel ratio of said mixture is switched in response to said speed of said vehicle.
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Abstract
A function signal having a desired characteristic curve is generated through the logical operation on a vehicle speed signal indicative of the speed of a vehicle, a ratio signal indicative of the air-to-fuel of the mixture supplied to the engine mounted on the vehicle, and a pressure signal indicative of the pressure in the intake manifold of the engine. The position of an electromagnetic valve for adjusting the amount of fuel supplied to the engine is controlled in response to the function signal, thereby controlling the air-to-fuel of mixtures in accordance with the various driving conditions of the vehicle including the vehicle speed.
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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, provided in the intake passage of an engine of a vehicle, for supplying said engine with air-fuel mixture, said carburetor including a float chamber in which fuel is stored, a venturi at which said fuel is mixed with air, and a fuel passage which communicates said float chamber with said venturi; a speed detector for generating a first signal indicative of the vehicle speed; an air-to-fuel ratio detector, provided in the exhaust passage of said engine, for generating a second signal related to the air-to-fuel ratio of said mixture supplied to said engine; a pressure detector, provided in said intake passage, for generating a third signal indicative of the pressure in said intake passage; a frequency-to-voltage converter circuit connected to said speed detector, for generating a fifth voltage signal whose voltage corresponds to the frequency of said first signal; a first vehicle-speed function voltage generator connected to said frequency-to-voltage converter circuit, for generating a sixth voltage signal related to the comparison of said fifth voltage signal to a first predetermined level; a second vehicle-speed function voltage generator connected to said frequency-to-voltage converter circuit, for generating a seventh voltage signal related to the comparison of said fifth voltage signal to a second predetermined level; a first logical circuit connected to said first vehicle-speed function voltage generator and said pressure detector, for generating a first logical output signal from said second sixth signal and said third signal; a second logical circuit connected to said second vehicle-speed function voltage generator and said pressure detector, for generating a second logical output signal from said seventh voltage signal and said third signal; a third logical circuit connected to said first logical circuit and said air-to-fuel ratio detector, for generating a third logical output signal from said first logical output signal and said second signal; and a fourth logical circuit connected to said second and third logical circuits, for generating a fourth signal by logical operation on said second and third logical output signals so that said fourth signal corresponds to said second signal when the speed of said vehicle is less than a first predetermined value, to one of said second and third signals when the speed of said vehicle is between said first value and a second predetermined value greater than said first value and to said third signal when the speed of said vehicle is greater than said second value; and electromagnetic valve means, connected to said function signal generator and provided in said fuel passage, for controlling the amount of fuel flowing therethrough in response to said fourth signal, whereby the air-to-fuel ratio of said mixture is switched in response to said speed of said vehicle. - View Dependent Claims (2, 3, 4, 5)
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6. An air-to-fuel ratio control system for internal combustion engines comprising:
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a carburetor, provided in the intake passage of an engine of a vehicle, for supplying said engine with air-fuel mixture, said carburetor including a float chamber in which fuel is stored, a venturi at which said fuel is mixed with air, and a fuel passage which communicates said float chamber with said venturi; a speed detector for generating a first signal indicative of the vehicle speed; an air-to-fuel ratio detector, provided in the exhaust passage of said engine, for generating a second signal related to the air-to-fuel ratio of said mixture supplied to said engine; a pressure detector, provided in said intake passage, for generating a third signal indicative of the pressure in said intake passage; a function signal generator, connected to said detectors, for generating a fourth signal related to said second signal when the speed of said vehicle is less than a first predetermined value, to one of said second and third signals when the speed of said vehicle is between said first value and a second predetermined value, greater than said first value and to said third signal when the speed of said vehicle is greater than said second value; magnetic path forming means having a permanent magnet; a moving core having a needle valve portion which moves to control the amount of fuel flowing through said fuel passage, said moving core mounting an exciting coil thereon; spring means connected to said magnetic path forming means and said moving core, for biasing said moving core; and current control means connected between said function signal generator and the exciting coil mounted on said moving core, for controlling a current to said exciting coil in proportion to the voltage of said fourth signal.
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7. In an automotive vehicle driven by an internal combustion engine having a carburetor for supplying air-fuel mixture, an air-to-fuel ratio control system comprising:
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a plurality of condition detectors for detecting the operating conditions of said engine, respectively; a speed detector for detecting the travelling speed of said vehicle; a function generator connected to said condition detectors and said speed detector for generating an output according to first and second functions when said travelling speed of said vehicle is lower and higher than a predetermined speed, respectively, said first function related to at least one of said operating conditions of said engine and said second function related to at least one of said operating conditions of said engine different from said at least one of said operating conditions related to said first function; a pulse generator connected to said function generator for generating a train of pulse signals at a fixed frequency, each of said pulse signals having respective time intervals proportional to said function output; a needle valve positioned in said carburetor for controlling the air-to-fuel ratio of air-fuel mixture supplied to said engine in proportion to the position thereof; and electromagnetic means having a movable core secured to said needle valve and a first and second exciting coils arranged longitudinally such that said movable core is moved therethrough, longitudinally such that said movable core is moved therethrough, said first and second coils being connected to said pulse generator to be energized in response to the presence and the absence of said pulse signals, respectively for controlling the position of said movable core in proportion to said time intervals of said pulse signals. - View Dependent Claims (8, 9)
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Specification