System and method for controlling a vacuum pump that is used to check for leaks in an evaporative emissions system

• US 9,038,489 B2
• Filed: 10/15/2012
• Issued: 05/26/2015
• Est. Priority Date: 10/15/2012
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Jackson, Robert, Cadman, William R., Rasmussen, Paul William
• Primary Examiner(s): McCall, Eric S
• Assistant Examiner(s): Megna Fuentes, Anthony W
• Application Number:
  US13/651,533
• Publication Number:
  US 20140102565A1
• Time in Patent Office: 953 Days
• Field of Search: 7311438-11451, 73/497, 73/40, 73 492- 493
• US Class Current: 73/865.9
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 65/003 Measuring variation of fuel pressure in high pressure line
• CPC Class Codes: F04C 18/3441 the inner and outer member being in contact along one line or continuous surface substantially parallel to the axis of rotation
• CPC Class Codes: F04C 25/02 for producing high vacuum sealing arrangements F04C27/00; silencing F04C29/06
• CPC Class Codes: F04C 28/06 specially adapted for stopping, starting, idling or no-load operation
• CPC Class Codes: G01M 99/008 by doing functionality tests
• CPC Class Codes: Y10T 137/85986 Pumped fluid control

Abstract

A control system according to the principles of the present disclosure includes a fuel system diagnostic module and a pump control module. The fuel system diagnostic module performs a diagnostic test on a fuel system when a vacuum pump is switched off to prevent flow through the vacuum pump and thereby seal a portion of the fuel system from an atmosphere. The vacuum pump includes a cam ring, a rotor that rotates within the cam ring, and vanes that slide into and out of slots in the rotor as the rotor rotates. The pump control module switches on the vacuum pump for a predetermined period to force the vanes out of the slots and into contact with the cam ring to seal the vacuum pump before switching off the vacuum pump for the fuel system diagnostic test.

Claims

1. A control system comprising:

a fuel system diagnostic module that;

performs a diagnostic test on a fuel system when a vacuum pump is switched off to prevent flow through the vacuum pump and thereby seal a portion of the fuel system from an atmosphere, wherein the vacuum pump includes a cam ring, a rotor that rotates within the cam ring, and vanes that slide into and out of slots in the rotor as the rotor rotates; and

provides an instruction to switch off the vacuum pump; and

a pump control module that, in response to the instruction to switch off the vacuum pump, switches on the vacuum pump for a predetermined period to force the vanes out of the slots and into contact with the cam ring to seal the vacuum pump before switching off the vacuum pump for the fuel system diagnostic test.

2. The control system of claim 1 wherein the fuel system includes a fuel tank, an evaporative emissions (EVAP) system that provides fuel vapor from the fuel tank to an engine, and an EVAP leak check (ELC) system that checks for leaks in the EVAP system.

3. The control system of claim 2 wherein the ELC system includes the vacuum pump and an ELC pressure sensor that measures pressure within the ELC system.

4. The control system of claim 3 wherein the fuel system includes a tank pressure sensor that measures pressure within the fuel tank.

5. The control system of claim 4 wherein the fuel system diagnostic module selectively diagnoses a fault in the tank pressure sensor based on a difference between the tank pressure and the ELC system pressure when the vacuum pump is switched off.

6. The control system of claim 5 wherein the fuel system diagnostic module diagnoses the fault in the tank pressure sensor when the difference between the tank pressure and the ELC system pressure is greater than a predetermined value.

7. The control system of claim 3 wherein the EVAP system includes a canister that stores fuel vapor from the fuel tank and a purge valve that opens to allow fuel vapor to flow from the canister to an intake manifold of the engine.

8. A control system comprising:

a fuel system diagnostic module that performs a diagnostic test on a fuel system when a vacuum pump is switched off to prevent flow through the vacuum pump and thereby seal a portion of the fuel system from an atmosphere, wherein the vacuum pump includes a cam ring, a rotor that rotates within the cam ring, and vanes that slide into and out of slots in the rotor as the rotor rotates; and

a pump control module that switches on the vacuum pump for a predetermined period to force the vanes out of the slots and into contact with the cam ring to seal the vacuum pump before switching off the vacuum pump for the fuel system diagnostic test, wherein the fuel system includes a fuel tank, an evaporative emissions (EVAP) system that provides fuel vapor from the fuel tank to an engine, and an EVAP leak check (ELC) system that checks for leaks in the EVAP system, wherein the ELC system includes the vacuum pump and an ELC pressure sensor that measures pressure within the ELC system, wherein the EVAP system includes a canister that stores fuel vapor from the fuel tank and a purge valve that opens to allow fuel vapor to flow from the canister to an intake manifold of the engine, and wherein the fuel system diagnostic module selectively diagnoses a fault in the purge valve based on a change in the ELC system pressure when the vacuum pump is switched off.

9. The control system of claim 8 further comprising a pressure difference module that determines a difference between an initial value of the ELC system pressure during a diagnostic period and a present value of the ELC system pressure during the diagnostic period.

10. The control system of claim 9 wherein the fuel system diagnostic module diagnoses the fault in the purge valve when the difference between the initial value of the ELC system pressure and the present value of the ELC system pressure is less than a predetermined value throughout the diagnostic period.

11. A method comprising:

performing a diagnostic test on a fuel system when a vacuum pump is switched off to prevent flow through the vacuum pump and thereby seal a portion of the fuel system from an atmosphere, wherein the vacuum pump includes a cam ring, a rotor that rotates within the cam ring, and vanes that slide into and out of slots in the rotor as the rotor rotates;

providing an instruction to switch off the vacuum pump; and

in response to the instruction to switch off the vacuum pump, switching on the vacuum pump for a predetermined period to force the vanes out of the slots and into contact with the cam ring to seal the vacuum pump before switching off the vacuum pump for the fuel system diagnostic test.

12. The method of claim 11 wherein the fuel system includes a fuel tank, an evaporative emissions (EVAP) system that provides fuel vapor from the fuel tank to an engine, and an EVAP leak check (ELC) system that checks for leaks in the EVAP system.

13. The method of claim 12 wherein the ELC system includes the vacuum pump and an ELC pressure sensor that measures pressure within the ELC system.

14. The method of claim 13 wherein the fuel system includes a tank pressure sensor that measures pressure within the fuel tank.

15. The method of claim 14 further comprising selectively diagnosing a fault in the tank pressure sensor based on a difference between the tank pressure and the ELC system pressure when the vacuum pump is switched off.

16. The method of claim 15 further comprising diagnosing the fault in the tank pressure sensor when the difference between the tank pressure and the ELC system pressure is greater than a predetermined value.

17. The method of claim 13 wherein the EVAP system includes a canister that stores fuel vapor from the fuel tank and a purge valve that opens to allow fuel vapor to flow from the canister to an intake manifold of the engine.

18. A method comprising:

performing a diagnostic test on a fuel system when a vacuum pump is switched off to prevent flow through the vacuum pump and thereby seal a portion of the fuel system from an atmosphere, wherein the vacuum pump includes a cam ring, a rotor that rotates within the cam ring, and vanes that slide into and out of slots in the rotor as the rotor rotates; and

switching on the vacuum pump for a predetermined period to force the vanes out of the slots and into contact with the cam ring to seal the vacuum pump before switching off the vacuum pump for the fuel system diagnostic test, wherein the fuel system includes a fuel tank, an evaporative emissions (EVAP) system that provides fuel vapor from the fuel tank to an engine, and an EVAP leak check (ELC) system that checks for leaks in the EVAP system, wherein the ELC system includes the vacuum pump and an ELC pressure sensor that measures pressure within the ELC system, and wherein the EVAP system includes a canister that stores fuel vapor from the fuel tank and a purge valve that opens to allow fuel vapor to flow from the canister to an intake manifold of the engine, the method further comprising selectively diagnosing a fault in the purge valve based on a change in the ELC system pressure when the vacuum pump is switched off.

19. The method of claim 18 further comprising determining a difference between an initial value of the ELC system pressure during a diagnostic period and a present value of the ELC system pressure during the diagnostic period.

20. The method of claim 19 further comprising diagnosing the fault in the purge valve when the difference between the initial value of the ELC system pressure and the present value of the ELC system pressure is less than a predetermined value throughout the diagnostic period.