Abstract: There is provided a crack detection system in which a crack can be detected from a strain distribution of a part to be detected of an object. After taking the image of the part to be detected of the detection object by the imaging unit, the heat is applied by the heating unit. Furthermore, image of the part to be detected are taken again and an image analysis unit analyzes the images before and after applying the heat to acquire a strain distribution of the part to be detected, so that the crack can be detected based on difference in a state of strain between a place where the crack exist and the other place. Therefore, taking the images of the part to be detected including its coating layer enables the analysis to progress without removing the coating layer to detect the crack.

Abstract: There is provided a crack detection system in which a crack can be detected from a strain distribution of a part to be detected of an object. After taking the image of the part to be detected of the detection object by the imaging unit, the heat is applied by the heating unit. Furthermore, image of the part to be detected are taken again and an image analysis unit analyzes the images before and after applying the heat to acquire a strain distribution of the part to be detected, so that the crack can be detected based on difference in a state of strain between a place where the crack exist and the other place. Therefore, taking the images of the part to be detected including its coating layer enables the analysis to progress without removing the coating layer to detect the crack.

Abstract: To obtain an air-fuel ration control apparatus for an internal combustion engine capable of maintaining an NOx purification rate at a high level when a catalyst is in a deteriorated condition. The air-fuel ratio control apparatus includes: an oxygen concentration sensor for detecting an oxygen concentration at a position upstream of a catalyst; an oxygen concentration sensor for detecting an oxygen concentration at a position downstream of the catalyst; an injector drive unit for adjusting an amount of a fuel supplied to an internal combustion engine; a first air-fuel ratio control unit for controlling the injector drive unit such that the air fuel ratio at the position upstream of the catalyst matches a first target air-fuel ratio; a second air-fuel ratio control unit for setting the first target ratio such that the air fuel ratio at the position downstream of the catalyst matches a second target air-fuel ratio; and a target air-fuel ratio setting unit for setting the second target air-fuel ratio.

Abstract: To obtain an air-fuel ration control apparatus for an internal combustion engine capable of maintaining an NOx purification rate at a high level when a catalyst is in a deteriorated condition. The air-fuel ratio control apparatus includes: an oxygen concentration sensor for detecting an oxygen concentration at a position upstream of a catalyst; an oxygen concentration sensor for detecting an oxygen concentration at a position downstream of the catalyst; an injector drive unit for adjusting an amount of a fuel supplied to an internal combustion engine; a first air-fuel ratio control unit for controlling the injector drive unit such that the air fuel ratio at the position upstream of the catalyst matches a first target air-fuel ratio; a second air-fuel ratio control unit for setting the first target ratio such that the air fuel ratio at the position downstream of the catalyst matches a second target air-fuel ratio; and a target air-fuel ratio setting unit for setting the second target air-fuel ratio.

Abstract: A device for controlling the ignition timing for internal combustion engines correctly detecting fault of a knocking sensor over the whole rotational range of the engine. The device for controlling the ignition timing takes out knocking signals and produces an ignition timing control signal relying upon the knocking signals, and comprises a knocking sensor 1, a microcomputer 2 for producing a fault detection execution signal for executing the detection of fault of the knocking sensor and for applying a pulse voltage to the knocking sensor 1 relying upon the fault detection execution signal, comparison means 5 and 6 for comparing the charging voltage or discharging voltage of the knocking sensor 1 with two different threshold values, and logic means (NOR circuit) 7 for obtaining an OR of the outputs of the comparison means 5 and 6.

Abstract: In a misfire detecting device for an internal combustion engine having a plurality of cylinders, revolution detecting device detects the revolution of an engine; arithmetic device calculates deflections in revolution of the engine for each of the cylinders on the basis of a period of revolution of the engine in correspondence to the order of combustion of the cylinders; threshold value determining device determines a misfire decision threshold value for the cylinders from a value obtained by smoothing arithmetic values which are determined for the cylinders by the arithmetic device, and a predetermined value; and misfire deciding device compares the arithmetic values provided by the arithmetic device with the threshold value to comparison, to determine the occurrence of a misfire in any one of the cylinders.

Abstract: A microcomputer-based misfire detecting apparatus for a multi-cylinder internal combustion engine. A crank angle sensor is coupled to the engine for detecting first and second predetermined angular intervals set before and after a predetermined reference crank position close to a TDC preceding to combustion stroke in each of the cylinders. An acceleration detector is connected to the output of the crank angle sensor for determining an acceleration based on a time ratio between times taken for a crank shaft to rotate through the first and second predetermined angular intervals, respectively, from the output signal of the crank angle sensor. A misfire occurrence detector is connected to the acceleration detector for detecting misfire occurring in the engine cylinder on the basis of the output signal of the acceleration detector.

Abstract: A misfire detection device for a multi-cylinder internal combustion engine detects levels of angular acceleration .beta. of the crankshaft corresponding to predetermined phase intervals of respective cylinders. Further, the differences .DELTA..beta. between the levels of angular acceleration corresponding to successively ignited cylinders are calculated as the combustion condition parameters corresponding to respective cylinders, and when the absolute variance .DELTA..beta.R of the levels of combustion condition parameter (i.e., difference of acceleration .DELTA..beta.) corresponding to cylinders whose ignition timings are separated by 360 degrees of the crank angle is continuously less than a predetermined judgment level, an occurrence of continuous misfires is detected.

Abstract: An engine control device comprises: crank angle sensor provided for the cylinders of an engine; cylinder internal pressure sensor for detecting the internal pressures of the cylinders according to the output signals of the crank angle sensor; pressure normalizing unit for normalizing the cylinder internal pressures thus detected, according to the cylinder internal pressure which is obtained when the engine is in standard state; engine speed detector; charge efficiency calculating unit for calculating the charge efficiencies of the cylinders by using the output signals of the pressure normalizing unit and the engine speed detector; operating condition detecting unit for detecting the outputs of the pressure normalizing unit and the engine speed detector as operating conditions, calculation control unit for calculating the air/fuel ratio and the ignition timing of each cylinder according to the operating conditions; and adjusting unit for adjusting the air/fuel ratios and ignition timing of the cylinders accord

Abstract: A misfire detecting device is provided with a rotation detecting sensor 3 for detecting rotation signals corresponding to the timing of ignition of the cylinders of an engine. The device further includes a control unit which has continuous misfire detecting means for detecting the occurrence of a continuous misfire in the engine and intermittent misfire detecting means for detecting the occurrence of an intermittent misfire in it. Those detecting means operate according to the rotation signals provided by the rotation detecting sensor. When either the continuous misfire detecting means or the intermittent misfire detecting means detects the occurrence of a misfire, it is determined that a misfire has actually occurred in the engine.

Abstract: A misfiring sensing apparatus for an internal combustion engine measures the length of time required for two periods during the operation of an engine, each of the periods corresponding to a predetermined number of degrees of rotation of the crankshaft of the engine and corresponding to prescribed positions of the pistons of the engine. The two periods are selected so that the ratio of the lengths of the two periods will change when one of the cylinders of the engine is misfiring. Misfiring is detected based on the value of the ratio. In one form of the invention, misfiring is sensed by comparing the ratio with a reference value. In another form of the invention, the ratio is used to calculate a value indicative of the current angular acceleration of the crankshaft of the engine, and the calculated value is compared with a reference value to determine whether knocking is taking place.

Abstract: A method and apparatus capable of detecting the occurrence of misfiring in an internal combustion engine with high reliability over a wide engine operation range with a simplified structure. Starting from a fact that an engine acceleration changes in dependence upon combustion states in the engine cylinders, a ratio between two periods before and after a predetermined crank angle reference position is successively determined. An angular acceleration of the crankshaft is then determined on the basis of a difference between a current ratio and a preceding ratio for each cylinder. Subsequently, a change in the crankshaft acceleration is determined for comparison with a predetermined value at every ignition timing for each cylinder. If the change exceeds the predetermined value, it is determined the occurrence of misfiring. The method can be carried out by making use of only an output signal of a crank angle sensor which is usually utilized for ignition timing control of the engine.

Abstract: In a misfire detecting device for an internal combustion engine, a crank angle detector detects the crank angle of the engine, a speed detector detects the speed of the engine from the crank angle thus detected, a load detector detects the load of the engine from the speed thus detected; and a misfire detector detects the misfire rate of the engine from the load thus detected, and outputs a misfire detection signal when the misfire rate thus detected exceeds a misfire rate determining value set according to a certain amount of load.

Abstract: An apparatus for detecting the in-cylinder pressure of an internal combustion engine having a plurality of cylinders and for providing in-cylinder pressure parameters is described which comprises a plurality of pressure sensors for detecting the pressures in the respective cylinders, a signal selector, a microcomputer and a crank angle sensor. The signal selector sequentially selects the pressure signals from the pressure sensors to be transfer to the computer and the computer computes the pressure parameters in accordance with the received signals for each of the cylinders. The operation of the apparatus is executed by referring to the crank angle signal from the crank angle sensor.

Abstract: An apparatus for defecting occurrence of misfiring in an internal combustion engine with improved reliability. A change in an angular velocity of a crankshaft of the engine and a change in the output of an air/fuel ratio sensor are monitored. Only when both changes indicate occurrence of misfiring independently from each other, it is decided that misfiring in the cylinder has taken place. Reliability in misfiring detection is improved by using the results obtained through at least two mutually different types of misfiring detections.

Abstract: A combustion control device for internal combustion engines, comprising cylinder pressure detecting means for detecting the combustion pressure in a cylinder, crank angle detecting means for detecting a crank angle of the engine to be controlled, cylinder pressure monitoring means for finding and monitoring the waveform of the cylinder pressure based on the cylinder pressure detected by the cylinder pressure detecting means and a crank angle signal outputted from the crank angle detecting means, calculating means for calculating thermal efficiency based on the found waveform, and combustion control means for controlling the amount of fuel supply to the engine, ignition timing and the amount of exhaust gas recirculation, depending on the results of the calculation by the calculating means.

Abstract: A misfire detecting device of an internal combustion engine comprises a pressure detector(s) for detecting an inner cylinder pressure of the engine, a crank angle detector for detecting a crank angle, and a misfire detector for detecting a misfire based on signals from the pressure detector and the crank angle detector. The misfire detector judges that the engine is under a misfire, when a comparison is made between a first integrated value of an indicated inner cylinder pressure before a predetermined crank angle of a combustion cycle of the engine and a second integrated value of the indicated inner cylinder pressure after the predetermined crank angle, and when there is a difference between the first value and the second value by less than a predetermined value.

Abstract: A trouble diagnosis appartus comprises a cylinder internal pressure change detecting circuit to detect a change in the inner pressure of the cylinders of an internal combustion engine, a differentiation circuit to effect differentiation of an output signal outputted from the cylinder internal pressure change detecting circuit and a judging circuit to judge the internal combustion engine being faulty when a change quantity of output signal of the differentiation circuit is a predetermined value or lower.

Abstract: An electronic control fuel injection device for an internal combustion engine having an inner cylinder pressure sensor for detecting a pressure of a combustion chamber of the internal combustion engine; a crank angle sensor for detecting a crank angle; a device for synthesizing the detected inner cylinder pressure by predetermined crank angles; a device for calculating an intake air quantity based on an engine revolution number which is obtained from the synthesized inner cylinder pressure and the crank angle; a device for synthesizing the calculated intake air quantity in predetermined cycles; and a device for calculating a fuel injection quantity based on the synthesized intake air quantity.

Abstract: A misfire detecting device for an internal combustion engine comprises an inner cylinder pressure detector, a crank angle detector, and a misfire detector for determining that a misfire has occurred when the inner cylinder pressure at a predetermined crank angle after top dead center in an engine combustion cycle is below a predetermined value.