Behaviour of a Closed Loop Controlled Air Valve Type Mixer on a Natural Gas Fuelled Engine Under Transient Operation

951911

08/01/1995

Event
Future Transportation Technology Conference & Exposition
Authors Abstract
Content
Many current aftermarket natural gas conversions of gasoline fuelled spark ignited engines use an air-valve type mixer with closed loop control of the gas pressure. This control is often provided by an electronic integral controller that uses the output from an exhaust gas oxygen (EGO) sensor to control the duty cycle of a solenoid valve. By varying the duty cycle of this fuel control valve (FCV), the average pressure in the low pressure regulator (LPR) reference chamber and thus the gas pressure can be varied. The transient behaviour of these fuel systems is affected mainly by the mechanical response of the gas mixer and the LPR. The electronic controller can provide compensation only after the EGO sensor has detected an air-fuel ratio excursion.
The main weaknesses of this type of fuel system seems to be associated with the finite response of the mixer and the LPR and by the use of an airflow dependent vacuum signal strength for control. In order to achieve improved performance from this type of system, close attention should be paid to these parameters.
Meta TagsDetails
DOI
https://doi.org/10.4271/951911
Pages
12
Citation
Jääskeläinen, H., and Wallace, J., "Behaviour of a Closed Loop Controlled Air Valve Type Mixer on a Natural Gas Fuelled Engine Under Transient Operation," SAE Technical Paper 951911, 1995, https://doi.org/10.4271/951911.
Additional Details
Publisher
Published
Aug 1, 1995
Product Code
951911
Content Type
Technical Paper
Language
English