FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINE

• US 3,835,820 A
• Filed: 06/16/1972
• Issued: 09/17/1974
• Est. Priority Date: 06/17/1971
• Status: Expired due to Term

• Current Assignee: Hideya Fujisawa
• Original Assignee: Hideya Fujisawa
• Inventors: Fujisawa, Hideya
• Primary Examiner(s): Goodridge, Laurence M.
• Assistant Examiner(s): Flint, Cort R.
• Application Number:
  US05/263,618
• Time in Patent Office: 823 Days
• Field of Search: 123/119R,32EA,14MC
• US Class Current: 123/485
• CPC Class Codes: F02M 51/02 specially for low-pressure fuel-injection F02M51/005 takes precedence; pumpsper se F02M51/04; injectors per se F02M51/08

Abstract

This fuel injection system for internal combustion engines includes first means for generating a DC voltage proportional to the weight flow rate of air taken into an engine, second means for generating a sawtooth voltage which is synchronized with the working cycle of the engine and whose slope varies with the rotational speed of the engine, third means for comparing the output voltages of said first and second means and generating a pulse corresponding to the amount of fuel required for each engine cylinder per operating cycle of the engine, and at least one electromagnetic valve operable in response to a pulse generated by said third means.

Claims

1. A fuel injection system for internal combustion engines comprising, means for generating a DC voltage proportional to the weight flow rate of air taken into an engine, means for generating a sawtooth wave voltage which is synchronized with the working cycle of the engine and whose slope varies in accordance with the rotational speed of the engine, pulse generating means connected in circuit with said two means for comparing the output voltages of said two means for comparing the output voltages of said two means to produce a pulse corresponding to the quantity of fuel required for each cylinder of the engine per operating cycle thereof, and at least one electromagnetic valve connected in circuit with said pulse generating means and operable in response to said pulse generated by said pulse generating means, wherein the first mentioned generating means includes an air flow-voltage transducer comprises an air flow rate measuring element mounted downstream of an air cleaner in the inlet pipe of the engine and composed of a plurality of small tubes arranged in parallel in the direction of flow of the air in said inlet pipe, air pressure inlet pipes opened respectively at the upstream and downstream sides of said air flow rate measuring element to receive the air pressures at said upstream and downstreAm sides, and a differential pressure-voltage transducer connected to said air pressure inlet pipes for detecting the pressure difference between the air pressures induced through said air pressure inlet pipes to generate a voltage corresponding to said pressure difference.

2. A fuel injection system for internal combustion engines comprising, a first means for generating signals responsive to engine revolution, pulse generating means connected in circuit with said first means for generating a pulse synchronized with the working cycle of an associated engine, an engine revolution-voltage transducer connected in circuit with said first means for generating a DC voltage, the value of which is proportional to the engine revolution, a flip-flop circuit having two input terminals, one of said input terminals being connected in circuit with said pulse generating means, for succeeding to generate an output signal when the pulse of said pulse generating means is applied, an integrator circuit connected in circuit with said flip-flop circuit and said engine revolution-voltage transducer for generating a sawtooth wave voltage which is synchronized with the generation of the output signal from said flip-flop circuit and whose slope varies in accordance with the value of said DC voltage, a second means for generating a voltage signal responsive to the weight flow rate of the air taken into the engine, a comparator connected in circuit at the input terminals thereof with said integrator circuit and said second means and at the output terminal thereof with the other terminal of said flip-flop circuit for comparing a voltage signal of said second means with said sawtooth wave voltage and generating an output signal for stopping said output signal from said flip-flop circuit, and an electromagnetic valve means connected in circuit with said flip-flop circuit for supplying fuel to the engine during the time duration when the output signal of said flip-flop circuit is generating, wherein said second means comprises an air flow rate-voltage transducer for generating an output voltage directly proportional to the weight flow rate of the air taken into the engine, a temperature coefficient multiplier connected in circuit with said air flow rate-voltage transducer for generating an output voltage representative of the output voltage of said air flow rate-voltage transducer modified in accordance with the temperature of the air induced, an atmospheric pressure detector connected in circuit with said temperature coefficient multiplier for correcting the output voltage of said temperature coefficient multiplier in accordance with the value of the atmospheric pressure and generating an output voltage, and an air throttle valve opening coefficient multiplier connected in circuit with said atmospheric pressure detector for correcting the output voltage of said atmospheric pressure detector in accordance with the opening of said air throttle valve any generating an output signal to said comparator, and wherein said air flow rate-voltage transducer comprises an air flow rate measuring element mounted downstream of an air cleaner in the inlet pipe of the engine and composed of a plurality of small tubes arranged in parallel in the direction of flow of the air in said inlet pipe, air pressure inlet pipes opened respectively at the upstream and downstream sides of said air flow rate measuring element to receive the air pressures at said upstream and downstream sides, and a differential pressure-voltage transducer connected to said air pressure inlet pipes for detecting the pressure difference between the air pressures induced through said air pressure inlet pipes to generate a voltage corresponding to said pressure difference.

3. A fuel injection system for internal combustion engines comprising, a first means for generating signals responsive to engine revolution, pulse generating means connected in circuit with said first means for geneRating a pulse synchronized with the working cycle of an associated engine, an engine revolution-voltage transducer connected in circuit with said first means for generating a DC voltage, the value of which is proportional to the engine revolution, a flip-flop circuit having two input terminals, one of said input terminals being connected in circuit with said pulse generaating means, for succeeding to generate an output signal when the pulse of said pulse generating means is applied, an integrator circuit connected in circuit with said flip-flop circuit and said engine revolution-voltage transducer for generating a sawtooth wave voltage which is synchronized with the generation of the output signal from said flip-flop circuit and whose slope varies in accordance with the value of said DC voltage, a second means for generating a voltage signal responsive to the weight flow rate of the air taken into the engine, a comparator connected in circuit at the input terminals thereof with said integrator circuit and said second means and at the output terminal thereof with the other terminal of said flip-flop circuit for comparing a voltage signal of said second means with said sawtooth wave voltage and generating an output signal for stopping said output signal from said flip-flop circuit, and an electromagnetic valve means connected in circuit with said flip-flop circuit for supplying fuel to the engine during the time duration when the output signal of said flip-flop circuit is generating, wherein said second means comprises an air flow rate-voltage transducer for generating an output voltage directly proportional to the weight flow rate of the air taken into the engine, a temperature coefficient multiplier connected in circuit with said air flow rate-voltage transducer for generating an output voltage representative of the output voltage of said air flow rate-voltage transducer modified in accordance with the temperature of the air induced, an atmospheric pressure detector connected in circuit with said temperature coefficient multiplier for correcting the output voltage of said temperature coefficient multiplier in accordance with the value of the atmospheric pressure and generating an output voltage, and an air throttle valve opening coefficient multiplier connected in circuit with said atmospheric pressure detector for correcting the output voltage of said atmospheric pressure detector in accordance with the opening of said air throttle valve and generating an output signal to said comparator, and wherein said temperature coefficient multiplier comprises a bimetal adapted to make a predetermined amount of mechanical displacement with a change in temperature, and an electrical resistor connected with said bimetal strip whose resistance value changes in accordance with the mechanical displacement of said bimetal strip, whereby the output voltage of said air flow rate-voltage transducer is corrected in accordance with a change in the resistance value of said electrical resistor to produce an output voltage.

4. A fuel injection system for internal combustion engines comprising, means for generating a DC voltage proportional to the weight flow rate of air taken into an engine, means for generating a sawtooth wave voltage which is synchronized with the working cycle of the engine and whose slope varies in accordance with the rotational speed of the engine, pulse generating connected in circuit with said two means for comparing the output voltages of said two means to produce a pulse corresponding to the quantity of fuel required for each cylinder of the engine per operating cycle thereof, and at least one electromagnetic valve connected in circuit with said pulse generating means and operable in response to said pulse generated by said pulse generating means, wherein the first mentioned generating means includes an air flow rate-voltage transducer for generating an output voltage directly proportional to the weIght flow rate of the air taken into the engine, a temperature coefficient multiplier connected in circuit with said air flow rate-voltage transducer for generating an output voltage representative of the output voltage of said air flow rate-voltage transducer modified in accordance with the temperature of the air induced, an atmospheric pressure detector connected in circuit with said temperature coefficient multiplier for correcting the output voltage of said temperature coefficient multiplier in accordance with the value of the atmospheric pressure and generating an output voltage, and an air throttle valve opening coefficient multiplier connected in circuit with said atmospheric pressure detector for correcting the output voltage of said atmospheric pressure detector in accordance with the opening of said air throttle valve any generating an output signal to said comparator, and wherein said air flow rate-voltage transducer comprises an air flow rate measuring element mounted downstream of an air cleaner in the inlet pipe of the engine and composed of a plurality of small tubes arranged in parallel in the direction of flow of the air in said inlet pipe, air pressure inlet pipes opened respectively at the upstream and downstream sides of said air flow rate measuring element to receive the air pressures at said upstream and downstream sides, and a differential pressure-voltage transducer connected to said air pressure inlet pipes for detecting the pressure difference between the air pressures induced through said air pressure inlet pipes to generate a voltage corresponding to said pressure difference.

5. A fuel injection system according to claim 4, wherein said temperature coefficient multiplier comprises a bimetal adapted to make a predetermined amount of mechanical displacement with a change in temperature, and an electrical resistor connected with said bimetal strip whose resistance value changes in accordance with the mechanical displacement of said bimetal strip, whereby the output voltage of said air flow rate-voltage transducer is corrected in accordance with a change in the resistance value of said electrical resistor to produce an output voltage.

6. A fuel injection system for internal combustion engines comprising, means for generating a DC voltage proportional to the weight flow rate of air taken into an engine, means for generating a sawtooth wave voltage which is synchronized with the working cycle of the engine and whose slope varies in accordance with the rotational speed of the engine, pulse generating connected in circuit with said two means for comparing the output voltages of said two means to produce a pulse corresponding to the quantity of fuel required for each cylinder of the engine per operating cycle thereof, and at least one electromagnetic valve connected in circuit with said pulse generating means and operable in response to said pulse generated by said pulse generating means, wherein the first mentioned generating means includes an air flow rate-voltage transducer for generating an output voltage directly proportional to the weight flow rate of the air taken into the engine, a temperature coefficient multiplier connected in circuit with said air flow rate-voltage transducer for generating an output voltage representative of the output voltage of said air flow rate-voltage transducer modified in accordance with the temperature of the air induced, an atmospheric pressure detector connected in circuit with said temperature coefficient multiplier for correcting the output voltage of said temperature coefficient multiplier in accordance with the value of the atmospheric pressure and generating an output voltage, and an air throttle valve opening coefficient multiplier connected in circuit with said atmospheric pressure detector for correcting the output voltage of said atmospheric pressure detector in accordance with the opening of said air throttle valve and generating an output signal to said signal to said cOmparator, and wherein said temperature coefficient multiplier comprises a bimetal adapted to make a predetermined amount of mechanical displacement with a change in temperature, and an electrical resistor connected with said bimetal strip whose resistance value changes in accordance with the mechanical displacement of said bimetal strip, whereby the output voltage of said air flow rate-voltage transducer is corrected in accordance with a change in the resistance value of said electrical resistor to produce an output voltage.