PURPOSE: To detect the theoretical air-fuel ratio of B fuel gas through a simple constitution by previously determining the relational index between the sensor output and the theoretical air-fuel ratio of a reference mixture gas for a plurality of reference mixture gases each of which is mixed with hydrocarbon of specified carbon number at a known ratio.
CONSTITUTION: An air-fuel ratio controller 107 previously calculates the relational index between the theoretical air-fuel ratio of a reference mixture gas and the sensor output for a plurality of reference mixture gases (e.g. fuel gas such as LPG), each of which is mixed with hydrocarbon of 4C or less at a known ratio) using a gas heat conduction sensor S inserted into a fuel supply path 102. The relational index thus calculated is stored in a memory means S1. A theoretical air-fuel ration introduction means S3 determines the theoretical air-fuel ratio of fuel gas based on the output from the detecting means 3 with reference to the relational index. An air-fuel ratio control means S4 controls the air supply through a flow regulation valve 103a based on the theoretical air-fuel ratio thus regulating the air-fuel ratio of a gas engine 100.
NISHIMURA SACHIKO
NISHIDA MITSUTERU
TAKAHASHI YOSHIO
NIPPON GAS KYOKAI
NEW COSMOS ELECTRIC CO