Abstract: An apparatus for analyzing air/fuel ratio sensor characteristics makes it possible to perform highly accurate analysis of the characteristics of an air/fuel ratio sensor to be measured.

Abstract: A gas sensor using an ionic conductor has a thin-film gas detection portion on an alumina substrate. The gas detection portion comprises a zirconia ionic conductor layer, a pair of platinum electrodes provided with the ionic conductor layer interposed therebetween, and a pair of junction layers positioned between the ionic conductor layer and each electrode and formed in a state in which the substances of the ionic conductor layers and the electrodes are mixed therein.The gas sensor using an ionic conductor is formed by sequentially forming a first electrode, a first junction layer, an ionic conductor layer, a second junction layer, and a second electrode by a physical vapor deposition method on a substrate, wherein the first and second junction layers are formed to be in a state in which the substances of the ionic conductor layers and the electrodes are both present.

Abstract: A thin film mutilayered air-fuel ratio sensor having a sensor element including a first electrode formed on a porous substrate, a first solid electrolyte and a third electrode formed on the first electrode in this order, in such a manner that the first electrode is completely covered by the first solid electrolyte inclusive of its surroundings, and that the first solid electrolyte is completely covered by the third electrode inclusive of its surroundings, a second solid electrolyte and a fourth electrode and formed on the third electrode in this order, in such a manner that the peripheral portion of the third electrode is left uncovered by the second solid electrolyte and the fourth electrode and thereby left exposed. The first electrode, the third electrode, and the fourth electrode are made of a gas-permeable porous platinum, and the first solid electrolyte and the second solid electrolyte are made of a gas-permeable dense solid electrolyte having oxygen ion conductivity.

Abstract: An operation control system for an engine using alcohol fuel or mixed fuel of alcohol and hydrocarbon, or for an engine supplying cooling liquid such as alcohol, water or the like as fuel. Vapor concentration in exhaust gas and an air excess ratio of air-fuel mixture are detected, and a supply rate of alcohol, a water absorption ratio of alcohol or an amount of the cooling liquid is computed on the basis of the vapor concentration and the air excess ratio. Ignition timing, temperature of the coolant, a compression ratio and an air excess ratio are controlled on the basis of the supply rate of alcohol or the water absorption ratio of alcohol. Further, the cooling liquid is supplied which has its amount computed at a heavy load. Thus, operational performance of the engine is improved.

Abstract: A gas sampling valve is provided with a small opening for gas sampling and a gas flow channel communicating therewith and is adapted to sample a gas in the gas flow passage by operating a valve for opening and closing the small opening, wherein at least one detector for detecting the concentration of oxygen or combustion gas is disposed in the gas flow passage, whereby the concentration of oxygen, an air excess ratio, the combustion efficiency, or the like can be measured without using a separate analyzer.

Abstract: An air/fuel ratio sensor has a porous alumina substrate, a limiting current type oxygen detecting section on the porous alumina substrate for detecting the air/fuel ratio in the fuel lean region, a resistance-variable type oxygen detecting section on the porous alumina substrate for detecting the excess air ratio .lambda. when .lambda. is equal to one, a gas decomposition type hydrogen detecting section on the porous alumina substrate for detecting the air/fuel ratio in the fuel rich region and a heater for heating the respective detecting sections to the optimum temperature in operation, whereby the sensor can detect the air/fuel ratio over all the fuel rich and lean regions.

Abstract: An air-fuel ratio sensor comprising a limiting electric current type oxygen sensor portion, having a sequential stacking on a porous substrate of a first electrode with high gas permeability, a solid electrolytic thin film having a specific crystal orientation, a thickness of 0.1 to 30 .mu.m, and good crystallinity. The limiting electric current type oxygen sensor portion and second electrode with a high gas permeability, is arranged and connected in parallel with a resistive type oxygen sensor portion having interdigital electrodes formed on one or both major surfaces of an oxide semiconductor thin film, the resistance of which changes in accordance with oxygen partial pressure. The air-fuel ratio sensor also has a sensor heater formed on one surface of the porous substrate around the sensor portions. The overall structure of the sensor is coated with a porous ceramic coating to which a catalyst is added.

Abstract: This oxygen concentration detector employs an oxygen concentration sensor provided with a plate produced of a material which exhibits ionic conduction for oxygen (An oxygen ionic conductor), a cathode placed on the one surface of the oxygen ionic conductor plate, an anode placed on the other surface of the oxygen ionic conductor plate, and a porous material layer which functions to regulate the flow of oxygen which passes through the porous material layer to reach the cathode and the oxygen ionic conductor plate. The improvement realized in this oxygen concentration detector is to remove a drawback in which the output of this sensor makes an error depending on the temperature of a gas of which the oxygen concentration is measured.

Abstract: A limiting electric current type oxygen sensor comprising a first electrode of a gas-permeable film, a thin solid electrolyte film which is crystallized along one direction to decrease resistance and which has a thickness falling in the range between 0.1 .mu.m and 30 .mu.m, and a second electrode of a gas-permeable film sequentially formed on an electrically insulating substrate. This limiting electric current type oxygen sensor is also provided with a porous coating layer or a dense coating layer. The porous coating layer made of Al.sub.2 O.sub.3, SiO.sub.2, spinnel, SiC, Si.sub.3 N.sub.4 and etc., has a porosity of not more than 30% and a thickness of not less than 1 .mu.m, and serves as a gas diffusion flow rate-determining portion. The dense coating layer serves to control a gas permeation path such that either the first electrode or the substrate is used as the gas diffusion flow rate-determining portion.

Abstract: An apparatus for detecting concentrations of a plurality of gas components has a single polarographic sensor capable of detecting an oxygen concentration and a composite concentration of oxygen gas, carbon dioxide gas and steam. A first voltage is applied to the polarographic sensor which then measures only the oxygen concentration, or a second voltage is applied to the sensor which then measures only the composite concentration of oxygen gas, carbon dioxide gas and steam. The first and second voltages are applied to the sensor in a time division manner. Upon application of first and second voltages in such a time division manner, corresponding currents flowing through the sensor are detected to obtain signals corresponding to the oxygen concentration and the composite concentration of oxygen gas, carbon dioxide gas and steam.

Abstract: A thin film oxygen sensor with a microheater incorporates an oxide semiconductor and has an integral structure of a sensor portion and a heater portion, wherein a porous catalyst layer is formed on a surface of the sensor portion, and a thickness and an average pore diameter of the catalyst layer are determined such that a ratio of the thickness to the average pore diameter falls within a range of 50 to 3,000. The oxygen sensor has good reproducibility, high stability, and high sensitivity for changing a resistance in response to a change in an oxygen content in an atmosphere. The oxygen sensor can be manufactured at low cost and has a compact construction.

Abstract: A temperature control apparatus detects an actual temperature of an object (e.g., sensor) to be controlled, and compares the actual temperature with a preset target temperature to obtain a difference therebetween, thereby keeping a heater temperature constant. The temperature control apparatus has a temperature rise rate limiter for controlling a temperature rise rate of the object to be controlled so as not to exceed a predetermined temperature rise rate. The object may thus not be damaged by thermal strain which results from a high temperature rise rate.

Abstract: The invention provides a limiting electric current type oxygen sensor with a microheater, having: an oxygen ionic conductor; an anode and a cathode respectively formed on two major surfaces of the oxygen ionic conductor; an insulating film which has a porosity of not less than 0.2 [%], an average pore diameter of not less than 140 [.ANG.], and a thickness between 0.2 [.mu.m] and 10 [.mu.m], and which is formed on one of the anode and the cathode so as to regulate a flow rate of oxygen gas and to provide electrical insulation; and the microheater formed on the insulating film. The oxygen ionic conductor is electrically insulated from the microheater through the insulating film. The invention also provides a limiting electric current type oxygen concentration detecting device having the limiting electric current type oxygen sensor and a constant temperature control circuit.

Abstract: A sensor which has an insulating substrate on which is formed a heater layer for heating the sensor on a part thereof and which is operated above a predetermined temperature. The heater layer is made of a material which has a thickness of 0.2 .mu.m to 20 .mu.m and which is made of platinum, rhodium, palladium or a mixture thereof. The insulating substrate is made of alumina, quartz, spinel, magnesia, zirconia, or mixtures thereof. A heater protective layer having a thickness of 0.01 .mu.m to 500 .mu.m is made of materials based on alumina, silica, spinel, magnesia, zirconia or mixtures thereof.

Abstract: An engine vibration sensor for detecting the engine vibration as an electric signal including a vibrator set to resonate at a specific frequency of vibration of an engine to which it is attached, the vibrator being composed of at least one piezoelectric plate and having a root and a vibrator element; means for increasing the cross-sectional area of the vibrator element to make the second moment of area of the root of the vibrator relatively larger than that of the vibrator element; a base to be connected to an engine body; and a clamp for retaining the root firmly between the clamp and the base. The clamp may be provided with a projection having a flat surface for retaining the root of the vibrator. This construction prevents a change in the effective length of the vibrator element, thereby stabilizing the characteristics of the resonant frequency of the vibrator.

Abstract: An oxygen concentration detector provided with an oxygen concentration sensor further provided with an oxygen ionic conductor, a cathode placed on one surface of the oxygen ionic conductor, an anode placed on the other surface of the oxygen ionic conductor, and a layer convering the cathode for regulating the diffusion of oxygen gas toward the cathode. Temperature compensation is applied to the output of the detector which is inherently influenced by the temperature of the sensor. More specifically, an oxygen concentration detector is provided with the foregoing oxygen concentration sensor, and voltage or current is alternatively supplied to the sensor to measure a limiting current of the sensor and internal resistance of the sensor, and the current or the voltage produced by the foregoing application of voltage or current, and a temperature compensation is applied to the detected magnitude of limiting current according to the internal resistance of the sensor.

Abstract: An improvement in an engine vibration sensor of the type including a vibrator set to resonate at a specific frequency of vibration of the engine to which it is attached, for example the engine knocking vibration frequency, wherein the vibration of the vibrator is converted to an electric signal representing the specific engine vibration. The improvement consists of forming the vibrator from a magnetic material and providing a magnetic field generator for applying a magnetic field of controlled intensity to the vibrator, whereby the resonant frequency of the vibrator can be adjusted by varying the intensity of the magnetic field.