Cylinder control system for multicylinder combustion engine

Claim 1

A cylinder control system for a multicylinder internal combustion engine with an exhaust gas purification device for purifying the exhaust from the cylinders, the cylinders forming at least a first and a second group of cylinders, each of the groups having at least one fuel injection valve controlled independently of the fuel injection valves for other groups, the air supply to the first group being controlled by a first throttle valve, the air supply to the second group being controlled by the first and second throttle valves, the cylinder control system comprising: (a) air flow sensor means for measuring the air flow through the first throttle valve and generating an air flow signal indicative thereof; (b) Fuel injection control circuit means responsive to said air flow signal to generate a fuel injection signal indicative of a quantity of fuel to be injected; (c) cylinder control circuit means responsive to said fuel injection signal to generate a control signal when said fuel injection signal falls below a predetermined value, said second throttle responding to said control signal to interrupt the supply of air to the second group; (d) detector means for sensing the temperature of the exhaust purification device and generating a first signal indicative thereof; (e) comparator means for comparing said first signal to a first reference value representative of a predetermined temperature value above which the purification device may be damaged by heat and for generating a second signal when said first signal exceeds said first reference value; and (f) gate means responsive to said control signal and the absence of said second signal for gating said fuel injection signal to said at least one fuel injection valve of said second cylinder group.