Deceleration fuel cut device for internal combustion engines

Claim 1

In a fuel supply control system including a fuel injection device for injecting fuel into an internal combustion engine having an intake pipe, at least one throttle valve arranged in the intake pipe, an exhasust pipe, and a catalytic device arranged in the exhaust pipe for purifying exhaust gases, said catalytic device being of the type increasing in temperature with an increase in the amount of exhaust gases flowing into said catalytic device, said fuel supply control system being operable to electronically control said fuel injection device for control of the amount of fuel being supplied to said engine, a deceleration fuel cut device comprising: means for detecting operating conditions of said engine, said detecting means including a first sensor for detecting the rotational speed of said engine and a second sensor arranged in the intake pipe of the engine at a location downstream of the throttle valve for detecting the pressure in said intake pipe of said engine; means responsive to the outputs of said detecting means for determining a predetermined fuel cut condition, said fuel cut condition determining means being adapted to determine that said engine is in a condition requiring interruption of the supply of fuel to said engine when the engine rotational speed detected by said first sensor has a value higher than a predetermined value and simultaneously the intake pipe pressure detected by said second sensor has a value lower than a predetermined value above which the temperature of the catalytic device becomes excessively high, said predetermined intake pipe pressure value being set to higher values with an increase in the value of the engine rotational speed detected by said first sensor; and fuel cut means responsive to the result of said determination of said fuel cut condition determining means for causing said fuel injection device to cut off the supply of fuel to said engine.