Swellable adsorbent diagnostic for fuel vapor handling system

• US 5,408,976 A
• Filed: 05/02/1994
• Issued: 04/25/1995
• Est. Priority Date: 05/02/1994
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Reddy, Sam R.
• Primary Examiner(s): Wolfe, Willis R.
• Assistant Examiner(s): Moulis, Thomas N.
• Application Number:
  US08/235,960
• Time in Patent Office: 358 Days
• Field of Search: 123/516, 123/518, 123/519, 123/520, 123/198 D
• US Class Current: 123/519
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system

Abstract

An apparatus and method for use in diagnosing an evaporative emission canister collection and purge system. An EVAP system of a vehicle can be diagnosed through the use of a swellable adsorbent disposed in the system'"'"'s canister. The swellable adsorbent is expandable upon adsorption of fuel vapors and contractible upon desorption. By sensing the expansion and contraction response, a diagnostic mechanism can determine whether the vapor collection and purge functions are operating properly.

Claims

1. An evaporative emission control system comprising:

a fuel vapor storage canister;

a swellable material within the canister expandable and contractible in response to changes in the concentration of fuel vapor in the canister; and

a sensor positioned adjacent to the swellable material, wherein the expansion and contraction of the swellable material in response to changes in fuel vapor concentration as detected by the sensor is used to aid in diagnosing the system.

2. An evaporative emission control system according to claim 1 further comprising activated carbon contained within the canister.

3. An evaporative emission control system according to claim 1 further comprising a diagnostic system to determine if the evaporative emission control system is functioning correctly.

4. An evaporative emission control system that receives fuel vapor from a vehicle'"'"'s fuel system and releases stored fuel vapor to the vehicle'"'"'s engine induction system comprising:

a fuel vapor storage canister;

swellable adsorbent within the canister, the swellable adsorbent expandable upon adsorption of fuel vapor and contractible upon release of fuel vapor;

a vapor collection system to transfer fuel vapor to the canister;

a purge system to transfer fuel vapor from the canister to the engine induction system; and

a sensor detecting expansion and contraction of the adsorbent material to aid in diagnosing whether the vapor collection system and the purge system are operating correctly.

5. An evaporative emission control system according to claim 4 wherein the canister includes a first chamber containing the swellable adsorbent and a second chamber and further comprising activated carbon contained within the second chamber.

6. An evaporative emission control system according to claim 5 wherein the canister includes a third chamber adjacent to the first chamber containing the sensor and the sensor includes:

a movable wall between the first chamber and the third chamber responsive to expansion and contraction of the swellable adsorbent biased against the swellable adsorbent; and

a switch opening in response to contraction of the swellable adsorbent and closing in response to expansion of the swellable adsorbent, coupled to an electronic controller.

7. An evaporative emission control system for a vehicle having an engine and a fuel system with a fuel tank containing fuel comprising:

a fuel vapor storage canister including;

swellable adsorbent expandable upon adsorption of fuel vapor and contractible upon release of fuel vapor; and

a sensor adjacent to the swellable adsorbent; and

a diagnostic system to determine whether the evaporative emission control system is operating correctly by performing a multiple part diagnostic test including;

means responsive to a first signal from the sensor that the swellable adsorbent is expanded for determining whether the evaporative emission control system is functioning correctly; and

means responsive to a second signal from the sensor that the swellable adsorbent is contracted for determining whether the evaporative emission control system is operating correctly.

8. An evaporative emission control system for a vehicle having an engine and a fuel system with a fuel tank containing fuel comprising:

a fuel vapor storage canister including;

swellable adsorbent expandable upon adsorption of fuel vapors and contractible upon release of fuel vapors contained in the canister; and

an expansion sensor adjacent to the swellable adsorbent;

a vapor collection system to transfer fuel vapor emitted by the fuel system to the canister;

a purge system to selectively transfer fuel vapors from the canister to the engine;

a fuel tank level gauge;

a fuel temperature sensor;

an ambient air temperature sensor; and

a diagnostic system to determine whether the evaporative emission control system is operating correctly by performing a multiple part diagnostic test including;

means responsive to a first signal from the expansion sensor that the swellable adsorbent is expanded for analyzing the evaporative emission control system including means for waiting a sufficient time to estimate that the canister is purged and means for determining if the sensor indicates that the swellable adsorbent is contracting; and

means responsive to a second signal from the sensor that the swellable adsorbent is contracted for analyzing the evaporative emission control system including means for stopping the purge system and means for evaluating input from the fuel tank level gauge, the fuel and ambient air temperature sensors, the expansion sensor and the engine to determine whether the vapor collection system is operating correctly.

9. A method of diagnosing a fuel vapor emission control system having a canister containing a material expandable and contractible in response to changes in fuel vapor concentration and a sensor responsive to expansion and contraction of the material comprising the steps of:

reading the sensor; and

determining whether the sensor reading is indicative of an expanded condition of the material corresponding to a vapor loaded condition or a contracted condition of the material corresponding to a vapor unloaded condition.