Conversion system with electronic controller for utilization of gaseous fuels in spark ignition engines

• US 6,145,494 A
• Filed: 08/28/1997
• Issued: 11/14/2000
• Est. Priority Date: 08/25/1997
• Status: Expired due to Fees

• Current Assignee: Alternative Fuel Systems Inc.
• Original Assignee: Alternative Fuel Systems Inc.
• Inventors: Klopp, Gerhard O.
• Primary Examiner(s): SOLIS, ERICK R
• Application Number:
  US08/919,660
• Time in Patent Office: 1,174 Days
• Field of Search: 123/525, 123/526, 123/527, 123/575, 123/27 GE, 123/577, 123/417, 123/418, 123/406.32, 123/492
• US Class Current: 123/525
• CPC Class Codes: F02D 19/061 by controlling fuel injectors
• CPC Class Codes: F02D 19/0615 being initiated by automatic means, e.g. based on engine or vehicle operating conditions
• CPC Class Codes: F02D 19/0631 by estimation, i.e. without using direct measurements of a corresponding sensor
• CPC Class Codes: F02D 19/0647 the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]
• CPC Class Codes: F02D 19/066 Retrofit of secondary fuel supply systems; Conversion of engines to operate on multiple fuels
• CPC Class Codes: F02D 21/08 the other gas being the exhaust gas of engine
• CPC Class Codes: F02D 2200/0404 Throttle position
• CPC Class Codes: F02D 2200/0408 Estimation of intake manifold pressure
• CPC Class Codes: F02D 2200/0414 Air temperature
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 2200/0606 Fuel temperature
• CPC Class Codes: F02D 2200/0612 determined by estimation
• CPC Class Codes: F02D 37/02 one of the functions being ignition
• CPC Class Codes: F02D 41/0025 Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
• CPC Class Codes: F02D 41/0027 the fuel being gaseous non-electrical control F02D19/02
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 41/187 using a hot wire flow sensor
• CPC Class Codes: F02P 3/0456 using digital techniques
• CPC Class Codes: F02P 5/1504 with particular means during a transient phase, e.g. acceleration, deceleration, gear change during starting F02P5/1506
• CPC Class Codes: F02P 5/1506 with particular means during starting
• CPC Class Codes: Y02T 10/30 : Use of alternative fuels, e.g. biofuels
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

A conversion system for converting a spark ignition engine to operate on gaseous fuel is disclosed. The conversion system includes an electronic controller which operates on several novel principles to provide superior performance/responsiveness and to reduce exhaust emissions. The controller in accordance with the invention assumes complete control of spark ignition timing when gaseous fuel mode is enabled and generates independent spark ignition signals tailored to the gaseous fuel. The controller also generates an independent pulse width modulated gaseous fuel injection signal that controls a high performance electronic solenoid injector valve to supply gaseous fuel to the engine. Variable injector speed is used to compensate for the dynamic range of the engine. A novel dual array block learn scheme is used to provide efficient fuel control in engines equipped with closed-loop monitoring systems and exhaust gas recirculation. A gasoline power boost mode is also provided to enable extra power when maximum engine torque is commanded. The advantage is an efficient fuelling system which provides all of the advantages of gaseous fuels while preserving the power capabilities of liquid fuels, and minimizing exhaust emissions.

Claims

1. An electronic controller for a gasoline powered Otto-cycle internal combustion engine having an original equipment engine control unit, which enables said engine to operate interchangeably between liquid and gaseous fuels, said controller comprising:

means for generating on the basis of sensed conditions and independently of an original sparking ignition module an ignition timing sequence and dwell time adapted for the gaseous fuel used;

means for generating on the basis of sensed conditions and independently of the original fuel injection control module a modulated fuel injection signal for at least one gaseous fuel injector, said signal being adapted to the gaseous fuel used;

means for generating signals to said original equipment engine control unit indicating normal gasoline operating conditions while operating using a gaseous fuel;

means for initiating a gasoline fuel operating mode and terminating a gaseous fuel mode in response to at least one signal indicating operating conditions; and

means for initiating gaseous fuel operation and terminating gasoline fuel operation in response to at least one signal indicating operating conditions.

2. An electronic controller according to claim 1 wherein said signal indicating operating condition which causes gasoline operating mode to be initiated or terminated is manifold air pressure.

3. An electronic controller according to claim 1 wherein said signal indicating operating condition which causes gasoline operating mode to be initiated or terminated is throttle position.

4. An electronic controller according to claim 1 wherein said signal indicating operating condition which causes gasoline operating mode to be initiated or terminated is a manual override switch.

5. An electronic controller according to claim 1 wherein said signal indicating operating condition which causes gasoline operating mode to be initiated or terminated is a combination of manifold air pressure and throttle position.

6. A controller according to claim 1 wherein said ignition timing control and injector pulse width changes which occur on initiating and terminating said gasoline operating mode occur at different times to ensure transition between fuel modes.