Method of checking for purge flow in an evaporative emission control system

• US 5,641,899 A
• Filed: 03/05/1996
• Issued: 06/24/1997
• Est. Priority Date: 03/05/1996
• Status: Expired due to Term

• Current Assignee: FCA US LLC (Stellantis NV)
• Original Assignee: Chrysler Corporation (Stellantis NV)
• Inventors: Blomquist, William B., Dawson, Gary D., Richardson, Roland T., Tallarek, Glen
• Primary Examiner(s): Dombroske, George M.
• Application Number:
  US08/611,140
• Time in Patent Office: 476 Days
• Field of Search: 73/118.2, 73/49.7, 73/116, 73/117.2, 73/117.3, 73/118.1, 123/518, 123/519, 123/520, 364/431.05
• US Class Current: 73/114.39
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations

Abstract

A method of checking for purge flow in an evaporative emission control system includes the steps of determining if there is a fault in a leak detection pump, de-energizing the leak detection pump if there is a fault, and determining the state of a leak detection pump switch. The method also includes the steps of concluding a pump switch closed state if the pump switch is not opened, concluding a pump switch opened state if the pump switch is not closed, and monitoring a purge duty cycle until the evaporative emission control system is depressurized.

Claims

1. A method of checking for purge flow in an evaporative emission control system, said method comprising the steps of:

determining if there is a fault in a leak detection pump;

de-energizing the leak detection pump if there is a fault;

determining the state of a leak detection pump switch;

concluding a pump switch closed state if the pump switch is not opened;

concluding a pump switch opened state if the pump switch is not closed; and

monitoring a purge duty cycle until the evaporative emission control system is depressurized.

2. A method as set forth in claim 1 wherein said step of determining if there is a fault in a leak detection pump includes:

determining if a purge flow monitor is clear if there is a fault;

energizing the leak detection pump if a purge flow monitor becomes active if the purge flow monitor is not clear; and

de-energizing the leak detection pump if the purge flow monitor is clear.

3. A method of leak detection for an evaporative emission control system to return to normal purge function, said method comprising the steps of:

determining if a leak detection pump fault indicator is set;

de-energizing the leak detection pump if the pump fault indicator is set;

determining the state of a leak detection pump switch;

setting a pump switch closed at end of last trip indicator if the pump switch state is not opened;

clearing the pump switch closed at end of last trip indicator if the pump switch state is opened;

determining if an accumulated purge indicator was cleared;

checking if a purge duty cycle is greater than or equal to a predetermined minimum purge duty cycle if the accumulated purge indicator was cleared;

periodically decrementing the accumulated purge indicator if the purge duty cycle is not greater than or equal to a predetermined minimum purge duty cycle; and

periodically incrementing the accumulated purge indicator if the purge duty cycle is greater than or equal to a predetermined minimum purge duty cycle and testing a new accumulated purge indicator value.

4. A method as set forth in claim 3 wherein said step of determining if a leak detection pump fault indicator is set includes:

determining if a purge flow monitor active indicator is clear if the pump fault indicator is not set;

energizing the leak detection pump if a purge flow monitor becomes active if the purge flow monitor indicator is not clear; and

de-energizing the leak detection pump if the purge flow monitor indicator is clear.