Apparatus for and method of controlling air-fuel mixture in a carburetor of an automotive internal combustion engine

• US 3,921,612 A
• Filed: 09/13/1974
• Issued: 11/25/1975
• Est. Priority Date: 09/19/1973
• Status: Expired due to Term

• Current Assignee: Shigeo Aono
• Original Assignee: Shigeo Aono
• Inventors: Aono, Shigeo
• Primary Examiner(s): Myhre, Charles J.
• Assistant Examiner(s): Cop, Ronald B.
• Application Number:
  US05/505,540
• Time in Patent Office: 438 Days
• Field of Search: 123/32EA,32AE,119R,13R 261/72R,121B,19,39R
• US Class Current: 123/438
• CPC Class Codes: F02D 35/00 Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
• CPC Class Codes: F02M 3/09 Valves responsive to engine conditions, e.g. manifold vacuum carburettors with means for facilitating engine's idling below operational temperatures F02M1/00
• CPC Class Codes: F02M 7/11 Altering float-chamber pressure enriching the fuel-air mixture during starting by depressing float to flood carburettor F02M1/18
• CPC Class Codes: F02M 7/24 Controlling flow of aerating air
• CPC Class Codes: F02M 7/28 dependent on temperature or pressure
• CPC Class Codes: Y10S 261/19 Degassers
• CPC Class Codes: Y10S 261/67 Carburetors with vented bowl

Abstract

The richness of an air-fuel mixture produced by a carburetor of an internal combustion engine of an automotive vehicle, by increasing the pressure of air behind the fuel in a fuel discharge circuit for enrichment of the air-fuel mixture if the mixture is found excessively lean or injecting pressurized air into the fuel flowing in the fuel discharge circuit for leaning out the mixture if the mixture is found excessively rich. Increasing the air pressure behind the fuel in the fuel discharge circuit gives rise to an increase in the flow rate of the fuel to be discharged and injection of pressurized air into the fuel flowing in the fuel discharge circuit is causative of reduction of density of the fuel to be discharged and accordingly contribute to reduction of the flow rate of the fuel discharged from the circuit.

Claims

1. An apparatus for controlling the richness of an air-fuel mixture produced by a carburetor of an internal combustion engine of an automotive vehicle, comprising first passage means having an outlet end open into a substantially closed space behind the fuel in a fuel discharge circuit of the carburetor;

second passage means having an outlet end open into said fuel discharge circuit;

a source of pressurized air;

air-flow regulAtor valve means in communication with the source of pressurized air and operative to regulate the flow rate of pressurized air through the valve means when actuated;

air-flow shift valve means having a first operative condition providing communication between said air-flow regulator valve means and said first passage means and a second operative condition providing communication between said air-flow regulator valve means and said second passage means; and

an electric control unit responsive to predetermined operating conditions of the vehicle and operative to supply a first control signal to said air-flow regulator valve means for varying the flow rate of pressurized air through the regulator valve means in accordance with said operating conditions of the vehicle and a second control signal to said air-flow shift valve means for holding the air-flow shift valve in said first operative condition when the vehicle operating conditions are representative of an excessively lean condition of the air-fuel mixture being produced in the carburetor or in said second operative condition when the vehicle operating conditions are representative of an excessively rich condition of the air-fuel mixture.

2. An apparatus as claimed in claim 1, in which said electric control unit is responsive to the rate of flow of atmospheric air in said carburetor and is operative to produce said first control signal which is effective to decrease the rate of flow of pressurized air through said air-flow regulator valve means when the rate of flow of atmospheric air in the carburetor increases in a range lower than a first predetermined level and to increase the rate of flow of pressurized air through the regular valve means when the rate of flow of atmospheric air in the carburetor increases in a range higher than a second predetermined level and said second control signal which is effective to hold said air-flow shift valve means in said first operative condition when the rate of flow of atmospheric air in the carburetor is lower than said first predetermined level and in said second operative condition when the rate of flow of atmospheric air in the carburetor is higher than said first predetermined level.

3. An apparatus as claimed in claim 2, in which said electric control unit comprises a flow control circuit responsive to the rate of flow of atmospheric air in the carburetor and operative to produce a train of pulses having pulsewidths which are decreased as the rate of flow of atmospheric air in the carburetor increase in the range lower than said first predetermined level and which are increased as the rate of flow of atmospheric air in the carburetor decrease in the range higher than said second predetermined level, said train of pulses constituting said first control signal.

4. An apparatus as claimed in claim 3, in which said air-flow regulator valve means comprises electromagnetically operated actuating means electrically connected to said flow control circuit for being energized by said train of pulses and actuating the air-flow regulator valve means into open condition in cycles which are dictated by said pulses produced by said flow control circuit.

5. An apparatus as claimed in claim 3, in which said air-flow shift valve means comprises electromagnetically operated actuating means electrically connected to said electric control unit for being energized by said second control signal for actuating the shift valve means between said first and second operative conditions thereof.

6. An apparatus as claimed in claim 4, in which said flow control circuit comprises function generating means operative to produce a signal voltage having a waveform which gradually declines as the rate of flow of atmospheric air in the carburetor increases in the range lower than said first predetermined level and which gradually increases as the rate of flow of atmospheric air in the carburetor increases in the range higher than said second predetermined level, adding means for adding A steady-state saw-tooth voltage to the signal voltage delivered from said function generating means for producing a saw-tooth signal voltage, and comparing and pulse generating means for comparing said saw-tooth signal voltage with a predetermined reference voltage and producing said train of pulses when the saw-tooth signal voltage is higher than said reference voltage.

7. An apparatus as claimed in claim 1, in which said electric control unit is responsive to variation in engine temperature lower than a predetermined level and is operative to produce said first control signal which is effective to decrease the rate of flow of pressurized air through said air-flow regulator valve means as the engine temperature rises toward said predetermined level and said second control signal which is effective to hold said air-flow shift valve means in said first operative condition thereof in response to the engine temperature lower than said predetermined level.

8. An apparatus as claimed in claim 7, in which said electric circuit comprises a flow control circuit responsive to the variations in the engine temperature lower than said predetermined level and operative to produce a train of pulses having pulsewidths which are decreased as the engine temperature rises toward said predetermined level, said train of pulses constituting said second control signal.

9. An apparatus as claimed in claim 8, in which said air-flow regulator valve means comprise electromagnetically operated actuating means electrically connected to said flow control circuit for being energized by said train of pulses and actuating the air-flow regulator valve means into open condition in cycles which are dictated by said pulses produced by said flow control circuit when the engine temperature is lower than said predetermined level.

10. An apparatus as claimed in claim 8, in which said air-flow shift valve means comprises electromagnetically operated actuating means electrically connected to said flow shift control circuit for being energized by said second control signal for actuating the shift valve means between said first and second operative conditions thereof.

11. An apparatus as claimed in claim 9, in which said flow control circuit comprises function generating means operative to produce a signal voltage having a waveform which gradually declines as the engine temperature rises toward said predetermined level, adding means for adding a steady-state saw-tooth voltage to said signal voltage for producing a saw-tooth signal voltage, and comparing and pulse generating means for comparing said saw-tooth signal voltage with a predetermined reference voltage and producing said train of pulses when the saw-tooth signal voltage is higher than the reference voltage.

12. An apparatus as claimed in claim 1, in which said electric control unit is responsive to variation in the temperature in the intake manifold of the engine and to idling condition of the engine and is operative to produce said first control signal which is effective to increase the rate of flow of pressurized air through said air-flow regulator valve means as the intake manifold temperature rises beyond a predetermined level and said second control signal which is effective to hold said air-flow shift valve means in said second operative condition thereof during idling of the engine.

13. An apparatus as claimed in claim 12, in which said electric control unit comprises a flow control circuit responsive to the variation in the temperature in the engine intake manifold and operative to produce a train of pulses having pulsewidths which are increased as the intake manifold temperature rises beyond said predetermined level, said train of pulses constituting said first control signal, and a flow shift control circuit responsive to the idling condition of the engine and operative to produce a control current when the engine is in the idling condition, said control current constituting said second control signal.

14. An apparatuS as claimed in claim 13, in which said air-flow regulator valve means comprise electromagnetically operated actuating means electrically connected to said flow control circuit for being energized by said train of pulses and actuating the air-flow regulator valve means into open condition in cycles which are dictated by said pulses produced by said flow control circuit when the intake manifold temperature is higher than said predetermined level.

15. An apparatus as claimed in claim 13, in which said air-flow shift valve means comprises electromagnetically operated actuating means electrically connected to said electric control unit for being energized by said control current for actuating the shift valve means between said first and second operative conditions thereof.

16. An apparatus as claimed in claim 14, in which said flow control circuit comprises function generating means operative to produce a signal voltage having a waveform which gradually increases as the cooling water temperature rises beyond said predetermined level, adding means for adding a steady-state saw-tooth waveform to said signal voltage for producing a saw-tooth signal voltage, and comparing and pulse generating means for comparing said saw-tooth signal voltage with a predetermined reference voltage and producing said train of pulses when the saw-tooth signal voltage is higher than the reference voltage.

17. An apparatus as claimed in claim 1, in which said electric control unit is responsive to change in the vehicle speed and is operative to produce said first control signal which is effective to abruptly increase the rate of flow of pressurized air through said air-flow regulator valve means during an incipient stage of change of the vehicle speed and said second control signal which is effective to hold said air-flow shift valve means in said first operative condition thereof in response to an increase in the vehicle speed and in said second operative condition thereof in response to a decrease in the vehicle speed.

18. An apparatus as claimed in claim 17, in which electric control unit comprises a flow control circuit responsive to the change in the vehicle speed and operative to produce a train of pulses having pulse-widths which are abruptly increased at said incipient stage of the change of the vehicle speed, said train of pulses constituting said first control signal, and a flow shift control circuit responsive to an increase and a decrease in the vehicle speed and operative to produce a control current when the vehicle speed is increased or decreased, said control current constituting said second control signal.

19. An apparatus as claimed in claim 18, in which said air-flow regulator valve means comprise electromagnetically operated actuating means electrically connected to said flow control circuit for being energized by said train of pulses and actuating the regulator valve means into open condition in cycles which are dictated by said pulses produced by said flow control circuit during the incipient stage of the change of the vehicle speed.

20. An apparatus as claimed in claim 18, in which said air-flow shift valve comprise electromagnetically operated actuating means electrically connected to said flow shift control circuit for being energized by said control current and actuating said air-flow shift valve between said first and second operative conditions thereof.

21. An apparatus as claimed in claim 19, in which said flow control circuit comprises function generating means operative to produce a signal voltage having a waveform with a relatively short risetime in response to a change in the vehicle speed, adding means for adding a steady-state saw-tooth voltage to said signal voltage for producing a saw-tooth signal voltage, and comparing and pulse generating means for comparing said saw-tooth voltage with a predetermined reference voltage for producing said train of pulses when the saw-tooth signal voltage is higher than said reference voltage.

22. An apparatus as claimed in claim 1, in which said air-flow regulator valve means comprise an air-inlet port in communication with said source of pressurized fluid, an air-outlet port in communication with said air-flow shift valve means, a valve member which is movable between a first position providing communication between the air-inlet port and the air-outlet port and a second position interrupting the communication between the ports, and electromagnetically operated actuating means responsive to said first control signal for actuating said valve member between said first and second positions when energized and de-energized by the first control signal.

23. An apparatus as claimed in claim 22, in which said electric control unit comprises a flow control circuit responsive to said operating conditions of the vehicle and operative to produce a train of pulses having pulsewidths dictated by the vehicle operating conditions whereby said actuating means is energized in cycles by said pulses produced from the flow control circuit, said train of pulses constituting said first control signal.

24. An apparatus as claimed in claim 1, in which said air-flow shift valve means comprises an air-inlet port in communication with said air-flow regulator valve means, a first air-outlet port in communication with said first passage means, a second air-outlet port in communication with said second passage means, a valve member which is movable between a first porition providing communication between said air-inlet port and said first air-outlet port and a second position providing communication between said air-inlet port and said second air-outlet port, and electromagnetically operated actuating means responsive to said second control signal for actuating said air-flow shift valve between said first and second operative conditions when energized and de-energized by said second control signal.

25. An apparatus as claimed in claim 24, in which said electric control unit comprises a flow shift control circuit responsive to said operating conditions of the vehicle and operative to produce a control current responsive to an excessively rich or lean condition of the air-fuel mixture produced in the carburetor whereby said actuating means is energized or de-energized in accordance with the excessively rich or lean condition of the air-fuel mixture.

26. A method of controlling the richness of an air-fuel mixture produced by a carburetor of an internal combustion engine of an automotive vehicle, comprising producing a first control signal responsive to predetermined operating conditions of the vehicle, a second control signal responsive to an excessively rich or lean condition of the air-fuel mixture being produced in the carburetor, producing a flow of pressurized air, varying the rate of flow of pressurized air by said first control signal, and injecting the pressurized air into a substantially closed space behind the fuel in a fuel discharge circuit of the carburetor in response to the excessively lean condition of the air-fuel mixture or into the fuel flowing in the fuel discharge circuit in response to the excessively rich condition of the air-fuel mixture in accordance with said second control signal.

27. A method as claimed in claim 26, in which said operating conditions of the vehicle include the rate of flow of atmospheric air in the carburetor.

28. A method as claimed in claim 27, in which said first control signal is effective to decrease the rate of injection of said pressurized air as the rate of flow of atmospheric air in the carburetor increases in a range lower than a first predetermined level and to increase the rate of injection of the pressurized air as the rate of flow of atmospheric air increases in a range higher than a second predetermined level and in which said second control signal is effective to direct the flow of pressurized air into said space responsive to the unduly lean condition of the air-fuel mixture and into the fuel flowing in the fuel discharge circuit in response to the unduly rich condition of the air-fuel mixture.

29. A method as claimed in claim 28, in which said first control signal is produced by producing a signal voltage having a waveform which gradually decreases as the rate of flow of atmospheric air in the carburetor increases in the range lower than said first predetermined level and which gradually increases as the rate of flow of atmospheric air increases in the range higher than said second predetermined level, adding a steady-state saw-tooth voltage to said signal voltage for producing a saw-tooth signal voltage, comparing said saw-tooth signal voltage with a predetermined reference voltage and producing a train of pulses as said first control signal when the saw-tooth signal voltage is higher than said reference voltage, said train of pulses constituting said first control signal.

30. A method as claimed in claim 26, in which said operating conditions of the vehicle include the temperature of the cooling water the engine and idling condition of the engine.

31. A method as claimed in claim 30, in which said first control signal is effective to increase the rate of injection of said pressurized air as the cooling water temperature increases beyond a predetermined level and in which said second control signal is effective to direct the flow of the pressurized air into the fuel flowing in said fuel discharge circuit in response to the idling condition of the engine.

32. A method as claimed in claim 31, in which said first control signal is produced by producing a signal voltage having a waveform which gradually increases as the cooling water temperature rises beyond said predetermined level, adding a steady-state saw-tooth voltage to said signal voltage for producing a saw-tooth signal voltage, comparing the saw-tooth signal voltage be added to the signal voltage with a predetermined reference voltage and producing a train of pulses as said first control signal when the saw-tooth signal voltage is higher than said reference voltage.

33. A method as claimed in claim 26, in which said operating conditions of the vehicle include the engine temperature.

34. A method as claimed in claim 33, in which said first control signal is effective to decrease the rate of injection of said pressurized air as the engine temperature increases in a range lower than a predetermined level and in which said second control signal is effective to direct the flow of said pressurized air into said space behind the fuel in the fuel discharge circuit in response to the engine temperature lower than said predetermined level.

35. A method as claimed in claim 34, in which said first control signal is produced by producing a signal voltage having a waveform which gradually decreases as the engine temperature rises toward said predetermined level, adding a steady-state saw-tooth voltage to said signal voltage for producing a saw-tooth signal voltage, comparing the saw-tooth signal voltage with a predetermined reference voltage and producing a train of pulses as said first control signal when the saw-tooth signal voltage is higher than the reference voltage.

36. A method as claimed in claim 26, in which said operating conditions of the vehicle include change in the vehicle speed.

37. A method as claimed in claim 36, in which said first control signal is effective to abruptly increase the rate of injection of said pressurized air during an incipient stage of change of the vehicle speed and said second control signal is effective to direct the flow of said presssurized air into said space behind the fuel in the fuel discharge circuit in response to an increase in the vehicle speed and into the fuel flowing in the fuel discharge circuit in response to a decrease in the vehicle speed.

38. A method as claimed in claim 37, in which said first control signal is produced by producing a signal voltage having a waveform which has a relatively short resetime responsive to the change in the vehiCle speed, adding a steady-stage saw-tooth voltage to said signal voltage for producing a saw-tooth signal voltage, comparing the saw-tooth signal voltage with a predetermined reference voltage, and producing a train of pulses as said first control signal when the saw-tooth signal voltage is higher than the reference voltage.