Abstract: A misfire detecting device and method detects a misfiring state of an engine. A memory stores misfire-frequency data relating to a frequency of occurrence of a misfire of the engine, and a controller determines, on the basis of the misfire-frequency data, whether the misfiring state of the engine has occurred. The controller initiates a misfire detecting operation of detecting an occurrence of the misfire of the engine when a predetermined first condition is satisfied, and initializes the misfire-frequency data stored in the memory when a predetermined second condition is satisfied. The first condition indicates that the engine has entered into its firing state by cranking of the engine for starting thereof, while the second condition indicates that the engine has failed to enter into its firing state by the cranking. The misfire detecting device permits accurate detection of the misfiring state of the engine, irrespective of repeated cranking operations of the engine due to its repeated firing failures.

Abstract: A misfire detecting device and method detects a misfiring state of an engine. A memory stores misfire-frequency data relating to a frequency of occurrence of a misfire of the engine, and a controller determines, on the basis of the misfire-frequency data, whether the misfiring state of the engine has occurred. The controller initiates a misfire detecting operation of detecting an occurrence of the misfire of the engine when a predetermined first condition is satisfied, and initializes the misfire-frequency data stored in the memory when a predetermined second condition is satisfied. The first condition indicates that the engine has entered into its firing state by cranking of the engine for starting thereof, while the second condition indicates that the engine has failed to enter into its firing state by the cranking. The misfire detecting device permits accurate detection of the misfiring state of the engine, irrespective of repeated cranking operations of the engine due to its repeated firing failures.

Abstract: A misfiring detecting device comprising a sensor for detecting the angular velocity of the crankshaft. The elapsed time required for the crankshaft to rotate by a certain crank angle is detected at the time of combustion at each cylinder. The difference .DELTA.T.sub.n (=T.sub.n -T.sub.n-2) of the elapsed time T between cylinders with explosion strokes one interval apart is found and it is judged that a misfire has occurred when the difference .DELTA.T.sub.n has exceeded a set value K.sub.1 and also the pattern of change of the elapsed time (.DELTA.TC) has become the pattern of change of the time of a misfire.

Abstract: A device for detecting an occurrence of misfiring comprising a crankshaft sensor, which crankshaft sensor is used to detect the elapsed time required for the crankshaft to turn by a predetermined crankshaft angle during combustion in the cylinders. The difference in the elapsed time between cylinders where every other power stroke is performed is found and a determination is made as to at which cylinder the misfiring occurred when the difference exceeds a set value. The difference in elapsed times between cylinders with power strokes of crank angles 360.degree. apart is found and an estimated value of the difference changing due to acceleration or deceleration is found from that difference. This estimated value is used to correct the set value.

Abstract: A knocking detection apparatus for multi-cylinder engines, capable of detecting knocking through sensing pressure pulsation propagating through the cooling water flowing in a cylinder block surrounding the cylinders. The knocking detection apparatus has a diaphragm facing the space downstream from the detection apparatus as viewed in the direction of flow of the cooling water, and a transducer dixed to the diaphragm.

Abstract: A knock detecting apparatus for detecting the occurrence of knocking in an internal combustion engine by detecting variations in the pressure of engine cooling water. A sealed double diaphragm structure is formed by a first diaphragm which is directly responsive to variations in the cooling water pressure and not resonant at the knock frequencies and a second diaphragm which is resonant at the knock frequencies. A noncompressible fluid is contained in the sealed double diaphragm structure between the two diaphragms. Pulsations of the second diaphragm, resonant at the knock frequencies, are detected by a magnetic device or a piezoelectric device operative to output an ac signal.

Abstract: A method of sensing a knocking taking place in an internal combustion engine through the sensing of pulsative component of the cooling water pressure or lubricating oil pressure. The sensing of the pulsative component is made by removing the static component from the composite pressure which is the sum of the pulsative component and the static component. An apparatus for sensing a knocking taking place in an internal combustion engine has a differential pressure sensing mechanism including a pressure sensing diaphragm and a pulsation absorption mechanism. The pressure sensing diaphragm receives at its one side the composite cooling water pressure or composite lubricating oil pressure which is the sum of the pulsative component and static component. The pulsation absorption mechanism absorbs the pulsative component from the composite pressure so as to transmit only the static component of the pressure to the other side of the pressure sensing diaphragm.

Abstract: An engine knocking detection device has a diaphragm to be disposed in contact with the engine cooling water so as to resonate with pulsations of the pressure of the cooling water caused by engine knockings, and output elements responsive to the vibration of the diaphragm to produce an electrical output signal to be utilized for the control of engine spark timing. The water-contacting surface of the diaphragm is coated with a layer of a hydrophilic material operative to prevent attachment or adhesion of air bubbles to the water-contacting surface of the diaphragm whereby the sensitivity of the diaphragm to the water pressure pulsation is improved.

Abstract: A knocking sensing apparatus for sensing a knocking taking place in an internal combustion engine. The apparatus includes a diaphragm adapted to operate in response to the pressure of cooling water circulated in the engine, magnetism generating device, magnetic circuit including the diaphragm, and a magnetic flux detecting device adapted to detect in a manner like alternating current the change in the magnetic flux in the magnetic circuit caused by the operation of the diaphragm.

Abstract: A flow rate control mechanism for use in controlling the flow rate of exhaust gases in an exhaust gas re-circulating system of an internal combustion engine. This mechanism includes a swirl flow chamber having a circular cross section, a first nozzle and a second nozzle, the former of which is open through the inner wall of the swirl flow chamber therein in the direction normal thereto and the latter of which is open through inner wall of the swirl flow chamber therein in the direction tangential thereto. The latter nozzle is positioned close to the opening of the former or first nozzle. The first nozzle directed in the normal direction extracts part of exhaust gases through an exhaust manifold, while the second nozzle directed in the tangential direction is communicated with atmosphere. The opening of the first nozzle is close to the opening of the second nozzle, so that the pressure at the opening of the first nozzle approximates the atmospheric pressure.

Abstract: A flow control valve for an exhaust gas purifying system which is divided into a first valve chamber into which the exhaust gases flow and a second valve chamber out of which the exhaust gases flow. A first valve means responsive to the exhaust gases controls the communication between the first and second valve chambers and a second valve means controls the operation of the first valve means in response to the negative pressure in an air intake system.

Abstract: An improved air flow direction control valve particularly adapted for use with an exhaust gas purifying system on an internal combustion engine to control the direction of flow of air to be mixed into exhaust gas for effecting additional combustion of the uncombusted constituents therein. The valve essentially comprises a pair of valve members selectively operable to open one of two main outlets and a diaphragm operated shaft for selectively operating the two valve members upon movement between a first and a second position. The shaft is formed with a pair of shoulders which define a reduced diameter shaft portion therebetween, and the two valve members encircle the reduced diameter shaft portion in an oppositely facing relation.

Abstract: A value proportional to suction pressure is added to the difference between the maximum value and the minimum value of a pulsating exhaust pressure. When the sum exceeds a predetermined value, misfire of an engine is detected. The difference and the sum are formed electrically or pneumatically.