Canister purge strategy for a hybrid electric vehicle

• US 6,557,534 B2
• Filed: 01/03/2001
• Issued: 05/06/2003
• Est. Priority Date: 01/03/2001
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Robichaux, Jerry D., Kotre, Stephen John
• Primary Examiner(s): Moulis, Thomas N.
• Application Number:
  US09/753,388
• Publication Number:
  US 20020083930A1
• Time in Patent Office: 853 Days
• Field of Search: 123/518, 123/519, 123/520, 123/179.16
• US Class Current: 123/520
• CPC Class Codes: B60K 6/00 Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units arrangement or mounting in vehicles of electrical gearing, in which an electrical machine serves only as reduction gearing and not as the prime mover and in which no electrical storing means are used B60K17/12; control and regulation of purely electrical prime movers B60L; prime-movers comprising electrical and internal combustion motors in a common engine block or housing per se F02B65/00; electric motors or motor-generators used for starting the combustion engine F02N11/04; electric motors for synchronising gearing F16H3/12 Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/24 including control of energy storage means
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: B60W 2510/0671 Engine manifold pressure
• CPC Class Codes: B60W 2710/0605 Throttle position
• CPC Class Codes: B60W 2710/065 Idle condition
• CPC Class Codes: F02D 11/105 characterised by the function converting demand to actuation, e.g. a map indicating relations between an accelerator pedal position and throttle valve opening or target engine torque
• CPC Class Codes: F02D 2200/0406 Intake manifold pressure
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 35/0007 using electrical feedback F02D35/0015 takes precedence
• CPC Class Codes: F02D 41/0032 Controlling the purging of the canister as a function of the engine operating conditions
• CPC Class Codes: F02D 41/08 for idling F02D41/06, F02D41/16 take precedence
• CPC Class Codes: F02M 25/08 adding fuel vapours drawn from engine fuel reservoir electrical control of purge system F02D41/003
• CPC Class Codes: F02N 11/0829 related to special engine control, e.g. giving priority to engine warming-up or learning
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor

Abstract

The present invention provides a method and system for purging a vapor canister in a Hybrid Electric Vehicle during vehicle idle conditions. The present invention first determines whether purging is necessary by measuring fuel tank pressure and the time since the last purge. If either of these elements exceeds a calibratable threshold, the controller determines that the engine needs to be on and that purging must occur. An electronic throttle controller can also be used to command the throttle plate to low positions to increase intake manifold vacuum while purging. This allows for very rapid ingestion of the fuel vapor without risk of engine stalls, if used in an HEV where the engine speed is controlled by an electric motor. Upon completion of the purging process, the engine is shut “off” and the vehicle is returned to its normal idle conditions.

Claims

1. A method of purging a vapor canister in a hybrid electric vehicle during vehicle idle conditions comprising the steps of:

determining if vehicle idle conditions are met;

determining if a purging process has been executed for a recent drive cycle;

determining fuel tank pressure;

comparing fuel tank pressure to a calibratable pressure threshold;

determining the time since last purge;

comparing time since last purge to a calibratable time threshold;

starting an engine;

purging by opening a valve between the vapor canister and an intake manifold; and

controlling a throttle plate via an electronic throttle controller to increase vacuum in the intake manifold.

3. The method of claim 1, further comprising:

determining a vapor canister condition.

4. The method of claim 3, wherein determining a vapor canister condition comprises:

determining how far an air/fuel ratio controller has shifted.

5. The method of claim 3, wherein determining a vapor canister condition comprises:

determining the mass of remaining vapor in the vapor canister.

6. The method of claim 1, further comprising:

stopping the engine.

7. The method of claim 1, wherein controlling a throttle plate via an electronic throttle controller to increase vacuum in the intake manifold comprises:

controlling the throttle plate to a calibratable position.

2. A system to purge a vapor canister in a hybrid electric vehicle during vehicle idle conditions comprising:

means for determining if vehicle idle conditions are met;

means for determining if a purging process has been executed for a recent drive cycle;

means for determining fuel tank pressure;

means for comparing fuel tank pressure to a calibratable pressure threshold;

means for determining time since last purge;

means for comparing time since last purge to a calibratable time threshold;

means for starting an engine;

means for opening a valve between the vapor canister and an intake manifold to start the purge process; and

means for controlling a throttle plate via an electronic throttle controller to increase vacuum in the intake manifold.

8. The system according to claim 2, further comprising a purge control strategy embodied in a vehicle system controller.

9. The system according to claim 2, further comprising a purge control strategy embodied in an engine control unit.

10. The system according to claim 2, wherein the means for determining fuel tank pressure comprises a fuel tank pressure transducer electronically connected to an engine control unit.

11. The system according to claim 2, wherein the means for opening a valve between the vapor canister and an intake manifold to start the purge process comprises an electric vapor management valve electronically connected to an engine control unit.

12. The system according to claim 2, further comprising:

means for determining a vapor canister condition.

13. The system according to claim 12, wherein the means for determining a vapor canister condition comprises:

means for determining how far an air/fuel ratio controller has shifted.

14. The system according to claim 12, wherein the means for determining a vapor canister condition comprises:

means for determining the mass of remaining vapor in the vapor canister.

15. The system according to claim 2, further comprising;

means for stopping the engine.

16. The system according to claim 2, wherein the means for controlling a throttle plate via an electronic throttle controller to increase vacuum in the intake manifold comprises:

means for controlling the throttle plate to a calibratable position.

17. A system for purging a vapor canister in a hybrid electric vehicle that includes an engine and a starter for said engine, comprising:

an electronic throttle controller and a throttle plate in an intake manifold of said engine;

a controller connected by means of a network to said electronic throttle controller;

a strategy in said controller for determining if a purging process has been executed for a recent drive cycle including a clock for determining whether a preselected minimum time since last purge has elapsed;

a pressure transducer operatively connected to the controller for determining fuel tank pressure;

a controller strategy for comparing fuel tank pressure against a preselected pressure threshold;

a valve controlled by said controller between the vapor canister and an intake manifold to start the purge process; and

a controller strategy for causing said electronic throttle controller to control said throttle plate to increase vacuum in said intake manifold of said engine.

18. The system according to claim 17, further comprising a controller strategy to determine a vapor canister condition.

19. The system according to claim 18, wherein the controller strategy to determine a vapor canister condition comprises a controller strategy to determine how far an air/fuel ratio controller has shifted.

20. The system according to claim 18, wherein the controller strategy to determine a vapor canister condition comprises a controller strategy to determine the mass of remaining vapor in the vapor canister.

21. The system according to claim 17, wherein the controller strategy for causing said electronic throttle controller to control said throttle plate to increase vacuum in said intake manifold of said engine controls said electronic throttle plate to a calibratable position.