Initialization method of an automotive evaporative emission leak detection system

• US 6,658,925 B2
• Filed: 12/11/2002
• Issued: 12/09/2003
• Est. Priority Date: 09/05/1997
• Status: Expired due to Term

• Current Assignee: Siemens Canada Limited (Siemens AG)
• Original Assignee: Siemens Canada Limited (Siemens AG)
• Inventors: Cook, John, Perry, Paul D., Rasokas, Raymond, Weldon, Craig A.
• Primary Examiner(s): MCCALL, ERIC SCOTT
• Application Number:
  US10/315,943
• Publication Number:
  US 20030079533A1
• Time in Patent Office: 363 Days
• Field of Search: 123/434, 123/510, 123/516, 731/16, 731/172, 731/173, 731/181, 73/39, 73/40, 73/46, 73/47, 73/497
• US Class Current: 73/114.39
• CPC Class Codes: F02M 2025/0845 Electromagnetic valves
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• CPC Class Codes: F02M 25/0836 Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold

Abstract

An on-board evaporative emission leak detection system and method that detects leakage from an evaporative emission space of a fuel system of an automotive vehicle. A test includes an initialization, or stabilization, phase during which a differential between pressure in the evaporative emission space and atmospheric pressure is created, and then varied, over time, within a range of differential pressures suitable for performing a leak detection test. This varying of pressure differential alternately increases the created pressure differential above a nominal pressure differential and decreases the created pressure differential below the nominal pressure differential. The leak detection test is then performed.

Claims

1. An engine-powered automotive vehicle evaporative emission control having a fuel storage system comprising an evaporative emission space for containing volatile fuel vapors generated by the volatilization of fuel in the storage system and a purge valve for purging fuel vapors from the evaporative emission space to an engine for combustion therein during conditions conducive to purging, including a leak detection system for detecting leakage from the evaporative emission space which comprises:

a selectively operable prime mover for pumping gaseous fluid with respect to the evaporative emission space;

a selectively operable valve which operates to a first condition for allowing the prime mover to move gaseous fluid with respect to the evaporative emission space, and to a second condition disallowing the prime mover from moving gaseous fluid with respect to the evaporative emission space; and

a sensor providing an electric signal related to pressure in the evaporative emission space for controlling operation of the prime mover and of the valve;

the leak detection system initializing the evaporative emission space preparatory to performing a leak detection test by causing the pump to create a differential between pressure in the evaporative emission space and atmospheric pressure sufficient to perform a leak detection test, including varying, over time, the created pressure differential within a range of differential pressures sufficient to perform a leak detection test, and then isolating the evaporative emission space from communication with both the engine and atmosphere and performing a leak detection test.

2. An evaporative emission control as set forth in claim 1 in which the leak detection system initializes the evaporative emission space by increasing and decreasing the created pressure differential relative to a nominal pressure differential.

3. An evaporative emission control as set forth in claim 2 in which the leak detection system initializes the evaporative emission space by alternately increasing the created pressure differential above the nominal pressure differential and decreasing the created pressure differential below the nominal pressure differential.

4. An evaporative emission control as set forth in claim 3 in which the leak detection system initializes the evaporative emission space by a plurality of such alternate increases and decreases.

5. An evaporative emission control as set forth in claim 1 in which the leak detection system initializes the evaporative emission space by varying the pressure differential over a range between approximately 0.1 millibar above the nominal pressure differential and approximately 0.1 millibar below the nominal pressure differential.

6. An evaporative emission control as set forth in claim 5 in which the leak detection system initializes the evaporative emission space by establishing the nominal pressure differential at approximately 3.1 millibars.

7. An evaporative emission control as set forth in claim 1 in which the leak detection system initializes the evaporative emission space by varying the pump operation while the valve is open.

8. An evaporative emission control as set forth in claim 7 in which the leak detection system initializes the evaporative emission space by alternately throttling the pump up and down while the valve is open.

9. An evaporative emission control as set forth in claim 8, in which the leak detection system concludes the initialization of the evaporative emission space by closing the valve and stopping the pump.

10. An evaporative emission control as set forth in claim 1 in which the leak detection system initializes the evaporative emission space by creating a positive pressure in the evaporative emission space relative to atmospheric pressure.