Abstract: A water-proof type oxygen sensor including a sensor element having inner and outer electrodes at inner and outer surfaces, respectively; a metallic cap for housing the sensor element; a gas-tight sealing member provided in the cap for isolating the exhaust gases from the air; communicating openings provided in the cap for communicating a space inside the cap with the air; and a communicating member arranged around the outer periphery of the communicating openings and having gas permeability and water-repellent property. The inner and outer electrodes are adapted to contact with air and exhaust gases. The communicating member is cylindrical and is fixed to the metallic cap through a metallic fixing member having a coefficient of thermal expansion almost equal to that of the metallic cap.

Abstract: An oxygen sensor for measuring an oxygen concentration in exhaust gases discharged from an automobile including an oxygen sensing element having inner and outer electrodes which communicate with the atmospheric air serving as a reference oxygen and the exhaust gases, and a tube-like metal cap in which the sensing element is arranged. Within a space formed between the sensing element and the metal cap are arranged first and second compressed talc members serving as gas-tight sealing sections to constitute a first space which is isolated from the exhaust gases by means of the first and second talc members and a second space which is isolated from the exhaust gases by means of the second talc member.

Abstract: In an oxygen sensor having a plate-shaped oxygen sensor element, a measuring electrode on the broader width surface of the plate-shaped sensor element, and a protective cover covering the plate-shape sensor element, wherein the protective cover has gas inlet holes for introducing a gas to be measured therein and guide plates for changing the direction of the flow of a gas to be measured. The gas inlet holes have different spacings compared to each other, the guide plates and the gas inlet holes have different lengths compared to each other in the axial direction of the protective cover, and/or the gas inlet holes have different opening extents compared to each other. Consequently, the oxygen sensor always can provide a homogeneous swirling flow of the gas to be measured in the protective cover as well as precise measurement of the gas and a constant .lambda. controlling point.

Abstract: An excellent oxygen sensor is provided, comprising; a sensor element having electrodes on inner and outer surfaces thereof, the electrode on the inner surface communicating to the atmosphere, and the electrode on the outer surface communicating to a gas to be measured; a metallic accommodating member accommodating the sensor element; and at least two airtight sealing portions arranged in the accommodating member for separating the gas to be measured from the atmosphere, at least one airtight sealing portion at the low temperature side of the oxygen sensor having a recessed portion formed under compression by pressing the outer surface of the metallic accommodating member after the formation of the airtight sealing portions by compressing the talc powder in the axial direction of the oxygen sensor. The oxygen sensor has splendid airtight sealing property of the airtight sealing portions containing compressed talc powders filled therein.

Abstract: Excellent electrical connection between a female contact and an electrode terminal of an oxygen sensor can be assured for a long period of use even when the oxygen sensor is exposed to vibrations and/or humid atmosphere, by providing an oxygen sensor, comprising electrodes, a sensor element which generates an electromotive force or which changes its electric resistance value between the electrodes depending on oxygen concentration of a gas to be measured, electrode terminals arranged on the sensor element and connected to the electrodes, and a metallic accommodating member accommodating the sensor element, comprising; a female contact electrically connected to the electrode terminal; a ceramic housing electrically insulating the female contact from the metallic accommodating member; a resilient member pressing the ceramic housing; and a caulking ring pressing the resilient member to exhibit its resilient power; the female contact, the ceramic housing, the resilient member and the caulking ring forming a conse

Abstract: An oxygen sensor having construction of an upper open end portion plugged with a grommet through which lead wires are taken out of a protecting metallic cover. A resin grommet of a heat resistant resin such as Teflon, polyimide or the like is fitted in the upper open end portion of the metallic cover with a portion of the grommet being extended from upper open end portion of the metallic cover. A heat resistant non-metallic tube such as Teflon, polyimide, silicone rubber, fluororubber tube is closely fitted on the periphery of the extended portion of the resin grommet and the periphery of the upper end portion of the metallic cover and a metallic tube being closely fitted on the periphery of a portion of the non-metallic tube which is fitted on at least the metallic cover.

Abstract: An electrochemical device for detecting a measurement fluid, which includes a planar solid electrolyte body, a first electrode formed on the planar solid electrolyte body and substantially exposed to the measurement fluid, a second electrode formed on the planar solid electrolyte body and substantially isolated from the measurement fluid, a porous layer disposed in direct contact with the second electrode, and a device for applying an electric current so as to flow from the second electrode to the first electrode. The device may further include a third electrode, and a fourth electrode substantially directly exposed to the measurement fluid. In this case, the first and third electrodes are exposed to the measurement fluid through a thin flat space or porous layer having a predetermined diffusion resistance to the measurement fluid, and a current regulating device is connected between the third and fourth electrodes, for controlling an atmosphere adjacent to the first electrode.

Abstract: In an oxygen sensor having a plate-shaped oxygen sensor element, a measuring electrode on the broader width surface of the plate-shaped sensor element, and a protective cover covering the plate-shaped sensor element and having gas inlet holes for introducing a gas to be measured therein, a cylindrical body is provided between the plate-shaped sensor element and the protective cover in such fashion as to avoid direct impingement of the gas to be measured upon the measuring electrode, whereby the oxygen sensor can provide good measurements of the gas with high precision and a constant .lambda. controlling point.

Abstract: An oxygen sensor is disclosed, which includes a planar sensor element and a metallic cover. The planar sensor element is provided with a detecting section at least at one of outer side surfaces thereof for detecting a gas to be measured. The detecting section is protected with the metallic cover. The metallic cover is provided with gas introduction openings for introducing the gas into the metallic cover. The gas introduction openings are arranged so as not to be opposed to the detecting section of the oxygen sensor element. Guide plates are provided at the gas introduction openings, respectively for swirling the gas inside the metallic cover in a given direction. The metallic cover is provided with a gas discharge opening at the bottom face thereof.

Abstract: A heater-built-in oxygen sensor having an electrochemical cell, a reservoir formed in substantial communication with a reference electrode of the cell, an electrically insulating member held in communication with the reservoir, a heating element disposed in contact with the insulating member, and cooperating with the cell and insulating member to constitute a major portion of an oxygen sensing element, and a direct current power source which is located outside the sensing element and to which the heating element is electrically connected. The low-potential portion of the sensing element connected to the negative terminal of the power source is electrically connected to a measuring electrode of the cell, so that a leak current of at least 0.

Abstract: An electrode formed on an oxygen-ion conductive solid electrolyte body of an oxygen sensing element such that the electrode is exposed to a measurement fluid to be measured, for detecting a concentration of oxygen in the fluid. The electrode is formed of a porous cermet layer which has a thickness of at least 3 microns. The porous cermet layer includes as major components thereof an oxygen-ion conductive solid electrolyte, and at least two platinum-group metals which are selected from the platinum group and which includes platinum and rhodium. A content of said rhodium and a total content of the above at least two platinum-group metals are determined so as to satisfy the following formulas: R/M=0.2 to 0.8, and M/(SE+M)=0.3 to 0.8, where, R=volume % of rhodium included in the cermet layer, M=total volume % of the at least two platinum-group metals, and SE=volume % of the oxygen-ion conductive solid electrolyte included in the cermet layer.

Abstract: An electrochemical device for detecting a measurement fluid, which includes a planar solid electrolyte body, a first electrode formed on the planar solid electrolyte body and substantially exposed to the measurement fluid, a second electrode formed on the planar solid electrolyte body and substantially isolated from the measurement fluid, a porous layer disposed in direct contact with the second electrode, and a device for applying an electric current so as to flow from the second electrode to the first electrode. The device may further include a third electrode, and a fourth electrode substantially directly exposed to the measurement fluid. In this case, the first and third electrodes are exposed to the measurement fluid through a thin flat space or porous layer having a predetermined diffusion resistance to the measurement fluid, and a current regulating device is connected between the third and fourth electrodes, for controlling an atmosphere adjacent to the first electrode.

Abstract: An oxygen sensor element includes at least a standard electrode (i.e., reference electrode) and a measurement electrode and is made of an oxygen ion-conducting solid electrolyte and is accommodated in a casing. An airtight space formed in the oxygen sensor element or in the casing communicates with the standard electrode and is maintained substantially in an airtight state with respect to the external atmosphere. At least one pair of oxygen pump electrodes for supplying oxygen to the airtight space is arranged in the oxygen sensor element. Therefore, since it is not necessary to arrange a hole for the supply of a reference substance (such as air) in the oxygen sensor, it is possible to completely eliminate the deterioration and the damage of the oxygen sensor element due to the intrusion of water, sea water and the like from the external atmosphere.

Abstract: An NOx sensor for determining the concentration of NOx contained in a measurement gas, having first and second electrochemical detecting elements each of which includes an oxygen pumping cell and an oxygen sensing cell. Each of the pumping and sensing cells of the first and second detecting elements consists of a solid electrolyte and a pair of electrodes. At least one of the electrodes of the oxygen pumping and sensing cells of the second detecting elements which are exposed to the introduced measurement gas, is used as a catalytic electrode which is provided with a catalyst for reducing the nitrogen oxides contained in the measurement gas. The second detecting element detects an oxygen partial pressure of the measurement gas while the nitrogen oxides are reduced by the catalyst of the catalytic electrode.

Abstract: An oxygen sensor for determining an oxygen partial pressure of a measurement gas in a measurement-gas space, includes an elongate planar sensing element, a tubular protective device, and a retainer housing. The sensing element has an oxygen detecting portion adjacent to one longitudinal end thereof, and electrical terminal contacts adjacent to the other longitudinal end thereof. The tubular protective device accommodates therein the sensing element, and includes a first protective covering for protecting at least an end portion of the sensing element which is located within the measurement-gas space and exposed to the measurement gas and which includes the oxygen detecting portion. The tubular protective device further comprises a second protective covering for covering the remaining portion of the sensing element which is not exposed to the measurement gas. The tubular protective device is attached by the retainer housing to a partition wall defining the measurement-gas space.

Abstract: An electric connection terminal arranged at a rear end of a sensor element and capable of affording quick and easy connection of the sensor element with a contacting element connected to a lead wire extending into a connector socket or connector insulator accommodating the contacting element for transmitting a signal detected at the front end of the sensor element, is composed of at least two conductive layers, and at least the lowermost layer of the conductive layers is composed of a mixture of a conductive metal and ceramics and/or glass, so that the layers bond firmly with each other and the lowermost layer bonds most firmly to the sensor element, whereby peeling-off of the connection terminal from the sensor element due to friction thereof against the contacting element and repetition of heating and cooling of the sensor element is eliminated.

Abstract: An oxyen sensor for determining an oxygen partial pressure of a measurement gas in a measurement-space, comprising (a) an elongate oxygen sensing element having an oxygen detecting portion adjacent to its one longitudinal end, (b) a first protective covering for protecting at least an end portion of the sensing element which is located within the measurement-space and exposed to the measurement gas and which includes the oxygen detecting portion; (c) a second protective covering for covering another portion of the sensing element which is not exposed to the measurement gas; and (d) a retainer housing for supporting the sensing element, and the first and second protective coverings such that the end portion of the sensing element having the detecting portion is located within the conduit. The first and second protective coverings consist of an integral protective tubing member which is supported by the retainer housing with fluid tightness therebetween and which accommodates the oxygen sensing element.

Abstract: An oxygen sensor includes a planar oxygen sensing element having an oxygen detecting portion located in the vicinity of one end thereof, and a protective covering encloses the sensing element to protect the detecting portion in particular. The detecting portion has an oxygen detecting member exposed to a measurement gas. The sensing element has opposite primary surfaces having a larger area than other surfaces thereof, and the detecting member is disposed on the side of one of the primary surfaces. The protective covering has apertures for allowing the measurement gas to flow through a wall of the protective covering so that the detecting member is exposed to the measurement gas. The apertures are formed through a part of the wall of the protective covering which does not face the above-indicated one primary surface of the planar sensing element.

Abstract: An oxygen sensor including an elongate planar oxygen sensing element which has an oxygen detecting portion adjacent to one longitudinal end thereof. The detecting portion is exposed to a measurement gas to determine an oxygen concentration of the measurement gas. The sensing element is electrically connected to at least one external device through conductor members. An electrical terminal portion is formed on the sensing element, adjacent to the other longitudinal end thereof. The terminal portion has at least one pair of electrical contacts which are disposed adjacent to corresponding connectors for direct contact therewith.

Abstract: An oxygen sensor having a bar-shaped heater inserted in an elongate bore formed in a tubular solid electrolyte body which has porous platinum electrodes on its inner and outer surfaces and which is supported by a housing such that its closed end portion is exposed to exhaust gas and such that the elongate bore is gas-tight with respect to the exhaust gas. The bar-shaped heater comprises a heating resistor having a positive temperature coefficient, and a ceramic boyd carrying the heating resistor so as to embed the latter.