Fuel vapor recovery control system

• US 5,054,454 A
• Filed: 11/09/1989
• Issued: 10/08/1991
• Est. Priority Date: 11/09/1989
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Motor Company
• Inventors: Hamburg, Douglas R.
• Primary Examiner(s): Miller, Carl Stuart
• Application Number:
  US07/435,234
• Time in Patent Office: 698 Days
• Field of Search: 123/520, 123/519, 123/518, 123/521, 123/516, 123/494, 123/590, 123/533
• US Class Current: 123/520
• CPC Class Codes: F02D 41/004 Control of the valve or purge actuator, e.g. duty cycle, closed loop control of position
• CPC Class Codes: F02M 2025/0845 Electromagnetic valves
• CPC Class Codes: F02M 25/08 adding fuel vapours drawn from engine fuel reservoir electrical control of purge system F02D41/003

Abstract

A control system and method for an internal combustion engine and receiving inducted fuel vapors from a fuel vapor recovery system. An electronically actuated solenoid valve coupled to the fuel vapor recovery system regulates rate of vapor flow in response to the duty cycle of a desired rate of vapor flow command. The pressure differential across the valve is regulated to achieve substantially sonic vapor flow such that vapor flow is independent of engine manifold pressure fluctuations and linearly proportional to the duty cycle of the desired vapor flow command. An air/fuel ratio feedback control system is thereby able to maintain a desired air/fuel ratio during changes in inducted airflow.

Claims

1. A control system for an internal combustion engine having an air/fuel intake system coupled to a fuel system, comprising:

fuel vapor recovery means coupled to the fuel system for receiving fuel vapors;

an electronically actuated solenoid valve coupled between said fuel vapor recovery means and the air/fuel intake system for controlling flow rate of said vapors into the air/fuel intake system; and

regulating means for providing a minimal pressure differential across said valve greater than a critical pressure required to achieve substantially sonic flow through said valve such that flow through said valve is substantially independent of pressure variations in the air/fuel intake system.

2. The control system recited in claim 1 wherein said fuel vapor recovery system comprises a vapor storage canister coupled to a fuel tank.

3. The control system recited in claim 1 wherein said regulating means comprises an electrical pump responsive to a pressure measurement at an inlet of said valve.

4. A control system for an internal combustion engine having an air/fuel intake system coupled to a fuel system, comprising:

fuel vapor recovery means coupled to the fuel system for receiving fuel vapors;

control means for providing a desired rate of vapor flow signal;

an electronically actuated solenoid valve responsive to said desired rate of vapor flow signal and coupled between said fuel vapor recovery means and the air/fuel intake system for controlling actual rate of vapor flow; and

regulating means for regulating pressure differential across said valve to maintain said pressure differential above a critical pressure associated with sonic flow to achieve substantially sonic vapor flow through said valve such that said actual rate of vapor flow is linearly proportional to said desire rate of vapor flow signal.

5. The control system recited in claim 4 wherein said regulating means is responsive to at least a pressure measurement at an inlet of said valve.

6. The control system recited in claim 4 wherein said regulating means comprises a comparison of inlet pressure at said valve with a reference pressure.

7. The control system recited in claim 4 wherein said control means provides said desired rate of flow signal having a duty cycle proportioned to desired rate of flow.

8. A control system for an internal combustion engine having an air/fuel intake system coupled to a fuel system, comprising:

fuel vapor recovery means coupled to the fuel system for receiving fuel vapors;

control means for providing a desired rate of vapor flow command;

an electronically actuated solenoid valve responsive to said desired rate of vapor flow command and having an inlet coupled to said fuel vapor recovery means and an outlet coupled to the air/fuel intake system for controlling actual rate of vapor flow;

an electric pump coupled between said fuel vapor recovery means and said valve inlet; and

regulating means for applying electric power to said pump in response to a measurement of pressure at said inlet valve to achieve substantially sonic flow through said valve such that said actual rate of fuel vapor flow is linearly proportional to said desired rate of vapor flow command.

9. The control system recited in claim 8 further comprising a reservoir coupled between said pump and said valve inlet.

10. The control system recited in claim 8 wherein said regulating means comprises a pressure transducer for providing said measurement of pressure.

11. A control system for an internal combustion engine having an air/fuel intake system for inducting an air/fuel mixture and fuel from a fuel system, comprising:

fuel vapor recovery means coupled to the fuel system for receiving fuel vapors;

control means for providing a desired rate of vapor flow command in relation to a calculation of inducted airflow;

air/fuel ratio feedback control means responsive to both the calculation of inducted airflow and feedback from an exhaust gas oxygen sensor for regulating fuel inducted into the air/fuel intake system to achieve a desired air/fuel ratio of a mixture of air and fuel and fuel vapor inducted into the air/fuel intake system;

an electronically actuated solenoid valve responsive to said desired rate of vapor flow command and coupled between said fuel vapor recovery means and the air/fuel intake system for controlling actual rate of vapor flow; and

regulating means for regulating pressure differential across said valve above a critical pressure to achieve substantially sonic vapor flow through said valve such that said actual rate of vapor flow is linearly proportional to said desired rate of vapor flow command.

12. The control system recited in claim 11 wherein said regulating means is responsive to a comparison of pressure at an inlet of said valve to a reference pressure.

13. The control system recited in claim 11 wherein said regulating means is responsive to a comparison of pressure at an inlet of said valve to a value associated with pressure in said air/fuel intake system.

14. A control system for an internal combustion engine having an air/fuel intake system for inducting an air/fuel mixture and fuel from a fuel system, comprising:

a fuel tank and a first vapor line coupled between said fuel tank and a vapor control system;

a vapor storage canister coupled to said fuel tank via a vapor bleed line, said vapor storage canister being coupled directly to said vapor control system via a second vapor line; and

said vapor control system comprising a solenoid valve and pressure regulating means for regulating pressure differential across said valve such that vapor flow through said valve is linearly proportional to inducted airflow and vapor flow through said first vapor line is proportional to flow through said second vapor line.

15. The control system recited in claim 14 further comprising a first valve coupled to said first vapor line and a second valve coupled to said second vapor line.

16. A method for controlling rate of fuel vapor flow from a fuel vapor recovery system to an air/fuel intake system of an internal combustion engine via an electronically activated valve, comprising the steps of:

providing an electrical signal to the valve having a duty cycle proportional to a desired rate of vapor flow;

providing an indication of inlet pressure at said valve; and

regulating said inlet pressure to achieve a pressure differential across the valve above a critical pressure associated with sonic vapor flow such that rate of vapor flow through the valve is linearly proportional to duty cycle of said electrical signal.

17. The method recited in claim 16 wherein said regulating step is responsive to a comparison of said inlet pressure with a reference pressure.

18. The method recited in claim 16 wherein said electrical signal providing means is responsive to a measurement of airflow inducted into the air/fuel intake system.