Systems and methods for determining fuel delay in a fuel injected engine with cylinders that may be deactivated are presented. In one example, the fuel injection delay is determined via a cylinder firing schedule array when the cylinder firing schedule array is available. The fuel injection delay is determined via weighted average of a fuel injection delay of a present engine cycle and a fuel injection delay of a past engine cycle when the cylinder firing schedule array is not available.

An internal combustion engine has a humidity sensor that is disposed in an intake passage of the internal combustion engine, a temperature sensor configured to detect an intake air temperature in a position of the humidity sensor, and a controller configured to correct an offset error of the sensor value by adding a correction value to the sensor value. The controller is configured to acquire the intake air temperatures respectively at a plurality of timings in a process of the intake air temperature changing, acquire the sensor values at the respective plurality of timings, calculate values excluding influences of temperature differences of the intake air temperatures from the respective sensor values as humidity index values respectively, and determine a correction value so that a variation degree of the humidity index values becomes small.

An air-fuel ratio control controls an air-fuel ratio (air-fuel ratio of an engine) of a mixture supplied to the engine, based on an output value of the downstream-side air-fuel ratio sensor disposed downstream of a catalyst. That is, the air-fuel ratio control apparatus sets the air-fuel ratio of the engine at a rich air-fuel ratio when the output Voxs is smaller than a reference value VREF (when a rich request is occurring). The air-fuel ratio control apparatus sets the air-fuel ratio of the engine at a lean air-fuel ratio when the output Voxs is larger than a reference value VREF (when a lean request is occurring). The air-fuel ratio control apparatus makes the target value VREF gradually come closer to a reference value VF (stoichiometric air-fuel ratio corresponding value) from a certain value, when the output value Voxs deviates greatly from the reference value Vf (points P1-P3).

Disclosed is a fuel injection control system for a single-cylinder diesel engine, comprising: a set of operating condition sensors including an accelerator pedal position sensor and a cooling water temperature sensor, an input signal interface capable of receiving an input signal from the operating condition sensors, a control unit connected to the input signal interface, and a rotational speed sensor provided at a camshaft or starting shaft of the single-cylinder diesel engine. The rational speed sensor is connected to the control unit via a rotational speed correction circuit. The control system can easily and quickly determine the rotational speed and operating stroke of the single-cylinder diesel engine, so as to quickly determine the fuel injection quantity and injection timing of the single-cylinder diesel engine in real time.

The present invention refers to a method for determining an amount of a substance in exhaust gas of an internal combustion engine, the method comprises the steps of: determining, for an effective condition of the engine, at least one operating parameter; determining, for a reference condition of the engine, a reference amount of the substance present in exhaust gas of the engine in the reference condition when being operated based on the determined operating parameter; determining an intake manifold temperature difference between the effective condition and the reference condition of the engine; and determining an effective amount of the substance in the exhaust gas of the engine in the effective condition in dependence on the determined reference amount of the substance and the determined intake manifold temperature difference.

An abnormality diagnosis device of an in-cylinder pressure sensor is provided. The device carries out a performance determination in which a performance quality of the sensor is determined based on an electric signal inputted from the sensor. The device carries out a first determination in which the performance determination is performed at a given timing, a performance recovery in which a given deposit removal control is executed in which a deposit accumulating inside the combustion chamber is removed when the performance quality of the in-cylinder pressure sensor is determined to fall below a given reference value, and a second determination in which the performance determination is carried out again after the performance recovery. In the second determination, the in-cylinder pressure sensor is diagnosed as abnormal when the performance quality of the sensor is determined to fall below the given reference value.

An object is to reduce the influence of a hydrogen-ascribable difference between the measurement value of an oxygen sensor and the actual value. An exhaust system includes an oxygen sensor configured to measure the air-fuel ratio of exhaust gas provided in an exhaust passage of an internal combustion engine and including a diffusion rate limiting layer and a controller configured to correct the measurement value of the oxygen sensor in such a way as to increase the measurement value of the oxygen sensor by an amount of correction that is made larger when the responsivity of the oxygen sensor to changes in the air-fuel ratio of the internal combustion engine is high than when it is low in the same operation state of the internal combustion engine.

Systems and methods for determining fuel delay in a fuel injected engine with cylinders that may be deactivated are presented. In one example, the fuel injection delay is determined via a cylinder firing schedule array when the cylinder firing schedule array is available. The fuel injection delay is determined via weighted average of a fuel injection delay of a present engine cycle and a fuel injection delay of a past engine cycle when the cylinder firing schedule array is not available.

The present invention provides a catalyst diagnosis device that enables precisely grasping a variation of AFR and diagnosing a deteriorated condition of the catalyst based on the variation. A timer counts elapsed time Tosc until downstream AFU (AFRd) meets a predetermined threshold condition when the fuel injection quantity is corrected by increasing or decreasing it so that as to the AFRu, the transition from either of leanness or richness to the other is repeated with the stoichiometric area between the leanness and the richness. An OSA calculating section calculates an Oxygen Storage Amount (OSA) as a function of the AFR, Mfuel, Ne and Tosa. An OPA calculating section calculates an Oxygen Purge Amount (OPA) as a function of the AFR, Mfuel, Ne and Topa. A deterioration diagnosing section diagnoses a deteriorated condition of the catalyst C on the basis of at least one of the OSA and OPA.

An engine system includes an air handling and fuel system whose states are managed by a reference managing unit. The engine system has a plurality of sensors whose sensor signals at least partially define a current state of the engine system. The reference managing unit includes a controller which controls the air handling and fuel system of the engine system as well as a processing unit coupled to the sensors and the controller. The processing unit includes an agent which learns a policy function that is trained to process the current state, determines air handling references and fuel system references by using the policy function after receiving the current state as an input, and outputs the air handling references and fuel system references to the controller. Then, the agent receives a next state and a reward value from the processing unit and updates the policy function using a policy evaluation algorithm and a policy improvement algorithm based on the received reward value. Subsequently, the controller controls the air handling and fuel system of the engine in response to receiving the air handling references and the fuel system references.