Patent ID: 8290685

Claim:
A control device for an engine comprising: an intake air flow rate sensor for sensing a flow rate of air taken into an engine; an exhaust flow rate sensor that directly senses a flow rate of exhaust from the engine; an exhaust temperature estimating device that senses or estimates a temperature of exhaust from the engine; an intake air flow rate control device that controls a flow rate of air taken into the engine; a fuel supply device that supplies fuel to the engine; a first exhaust heat quantity estimating device for estimating an quantity of exhaust heat from the engine based on an output of the exhaust flow rate sensor and an output of the exhaust temperature estimating device; a second exhaust heat quantity estimating device that estimates an quantity of exhaust heat from the engine based on an output of the intake air flow rate sensor and an output of the exhaust temperature estimating device; and an operating condition determination device that determines an operating condition of the engine, wherein an exhaust heat quantity is estimated by interchangeably using the first exhaust heat quantity estimating device and the second exhaust heat quantity estimating device; and wherein, when the difference between an output of the first exhaust heat quantity estimating device and an output of the second exhaust heat quantity estimating device exceeds a prescribed value and the exhaust flow rate sensor is determined to be malfunctioning by the operating condition determination device, exhaust heat quantity estimation based on the first exhaust heat quantity estimating device is prohibited and the intake air flow rate control device and the fuel supply device are controlled based on a result of estimation by the second exhaust heat quantity estimating device.