Hybrid cold start strategy using electrically heated catalyst

• US 8,209,970 B2
• Filed: 05/15/2007
• Issued: 07/03/2012
• Est. Priority Date: 05/15/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Gonze, Eugene V., Ament, Frank, Santoso, Halim G
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): BOGUE, JESSE SAMUEL
• Application Number:
  US11/803,682
• Publication Number:
  US 20080282673A1
• Time in Patent Office: 1,876 Days
• Field of Search: 60274-273, 60284-287
• US Class Current: 60/303
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 2240/445 Temperature
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• 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 2510/0676 Engine temperature
• CPC Class Codes: B60W 2510/24 Energy storage means
• CPC Class Codes: B60W 2555/20 Ambient conditions, e.g. wind or rain
• CPC Class Codes: B60W 2710/0688 Engine temperature
• CPC Class Codes: B60W 30/192 Mitigating problems related to power-up or power-down of the driveline, e.g. start-up of a cold engine
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 13/011 having two or more purifying devices arranged in parallel
• CPC Class Codes: F01N 2240/16 an electric heater, i.e. a resistance heater
• CPC Class Codes: F01N 3/2013 using electric or magnetic heating means
• CPC Class Codes: F02D 2200/0802 Temperature of the exhaust gas treatment apparatus
• CPC Class Codes: F02D 41/0235 in relation with the state of the exhaust gas treating apparatus control of exhaust gas treating apparatus per se F01N
• CPC Class Codes: F02D 41/064 at cold start F02D41/067 takes precedence
• CPC Class Codes: F02N 11/0818 Conditions for starting or stopping the engine or for deactivating the idle-start-stop mode
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method of operating an engine control system includes generating an engine start signal, determining whether a cold start condition exists, energizing an electrically heated catalyst based on the cold start condition, determining the temperature of the electrically heated catalyst and selectively starting an engine based on the engine start signal and the electrically heated catalyst temperature.

Claims

1. An engine control system comprising:

a cold start determination module to determine whether an engine coolant temperature of a hybrid vehicle engine is less than a threshold value;

an electrically heated catalyst (EHC) control module to selectively energize an electrically heated catalyst, the electrically heated catalyst including a heating element coated with a catalytic material and being positioned immediately upstream of a catalytic converter;

an EHC temperature module to directly measure a temperature of said electrically heated catalyst; and

an engine actuation module operable to selectively start said engine based on said engine coolant temperature and said electrically heated catalyst temperature, wherein said engine actuation module is operable to start said engine, independent of said electrically heated catalyst temperature, when at least one of an engine horsepower request exceeds a predetermined magnitude and a charge of a battery is less than a predetermined level,

wherein said EHC control module energizes the electrically heated catalyst after said start of said engine independent of the charge of the battery at said start of said engine.

2. The engine control system of claim 1 wherein said engine actuation module starts said engine when said electrically heated catalyst temperature is above a predetermined temperature.

3. The engine control system of claim 1, wherein said EHC control module continues to energize said electrically heated catalyst until a target temperature of a catalytic converter positioned downstream of said electrically heated catalyst may be maintained without energization of said electrically heated catalyst.

4. The engine control system of claim 3, further including an EHC optimization module to set ignition timing after top-dead-center to increase an exhaust gas temperature and minimize a time required for said catalytic converter to reach said target temperature.

5. The engine control system of claim 3, further including an EHC optimization module to set an air-to-fuel ratio to one of stoichiometry and lean of said stoichiometry.

6. A method of operating an engine control system in a hybrid vehicle, the method comprising:

generating an engine start signal;

determining whether a cold start condition exists by determining whether an engine coolant temperature of a hybrid vehicle engine is less than a threshold value;

determining an engine horsepower request;

energizing an electrically heated catalyst including a heating element containing catalytic material based on said cold start condition;

determining a temperature of said electrically heated catalyst;

selectively starting said engine based on said engine start signal, said engine horsepower request and said electrically heated catalyst temperature, wherein said engine is started, independent of said electrically heated catalyst temperature, when at least one of said horsepower request exceeds a predetermined magnitude and a charge of a battery is less than a predetermined level; and

energizing the electrically heated catalyst after said start of said engine independent of the charge of the battery at said start of said engine.

7. The method of claim 6 wherein energizing said electrically heated catalyst includes passing current through a heating element to increase the temperature of said electrically heated catalyst.

8. The method of claim 7 further comprising:

starting said engine when said electrically heated catalyst temperature is above a predetermined temperature.

9. The method of claim 8 further comprising:

continuing to energize said heating element after said engine starts and deactivating said electrically heated catalyst based on an estimation of the temperature of a catalytic converter positioned downstream of said electrically heated catalyst.

10. The method of claim 9 wherein said estimation of the catalytic converter temperature is based on at least one of an ambient air temperature, an engine flow, an engine coolant temperature and a spark ignition timing.

11. The method of claim 9 further comprising:

setting ignition timing after top-dead-center to increase an exhaust gas temperature and minimize the time required for said catalytic converter to reach a predetermined temperature.

12. The method of claim 9 further comprising:

setting an air-to-fuel ratio to one of stoichiometry and lean of said stoichiometry to minimize the time required for said catalytic converter to reach a predetermined temperature.

13. The method of claim 6 wherein said temperature of said electrically heated catalyst is measured directly.

14. The method of claim 6 wherein said temperature of said electrically heated catalyst is estimated.

15. The method of claim 14 wherein said temperature estimation of said electrically heated catalyst is based on the time a current and a voltage are supplied to said electrically heated catalyst.

16. An engine control system comprising:

a cold start determination module to determine whether an engine coolant temperature of a hybrid vehicle engine is less than a threshold value;

an electrically heated catalyst (EHC) control module to selectively energize an electrically heated catalyst including a heating element containing a catalytic material;

an EHC temperature module to determine a temperature of said electrically heated catalyst; and

an engine actuation module operable to selectively start said engine based on said engine coolant temperature and said electrically heated catalyst temperature, wherein said engine actuation module is operable to start said engine, independent of said electrically heated catalyst temperature, when at least one of an engine horsepower request exceeds a predetermined magnitude and a charge of a battery is less than a predetermined level, wherein said EHC control module estimates a time to continue energizing said electrically heated catalyst after said engine has started to maintain a minimum temperature of a catalytic converter positioned downstream of said electrically heated catalyst, energizes the electrically heated catalyst after said start of said engine independent of the charge of the battery at said start of said engine, and discontinues energization after said time estimate expires.

17. The system of claim 16, wherein said time estimate is based on at least one of an ambient air temperature, an engine coolant temperature, and an exhaust gas flow rate.