Abstract: A gas sensor including a detecting element having electrodes on first and second surfaces of an oxygen ion conductive solid-state electrolyte; a main fitting having a fitting portion to be fitted into a mounting hole formed on a wall of the pipe defining a flow path for a gas-to-be-measured for holding the detecting element in such manner that the first surface is disposed via the mounting hole at an inner position of the pipe with respect to the fitting portion; a cylindrical cover of which one end is connected to an outer position of the pipe with respect to the fitting portion of the main fitting and the other end is provided with a cylindrical sealing member having an air hole for introducing air to the second surface on one end and a through hole through which a lead connected to both electrodes of the detecting element passes on the other end; and a water repellant filter having gas permeability for closing the air hole, characterized in that the water repellant filter is formed in a sheet shape and mou

Abstract: A gas sensor is disclosed which attains high response speed, low power consumption, superior water splash resistance and a little setting direction dependency and setting angle dependency. In this gas sensor, a measured gas room is provided inside an inner cover, and gas passage holes for leading a measured gas in are provided on side surfaces of the inner cover and an outer cover. The gas passage holes provided on the outer cover are positioned much closer to a top end side than the gas passage hole provided closest to the top end side in the inner cover. Partitions disposed extendedly in an axial direction of the gas sensor are provided between the outer cover and the inner cover.

Abstract: A gas sensor includes a sensor element. The sensor element has a solid electrolytic member, a measurement electrode, and a reference electrode. The measurement electrode is provided on the solid electrolytic member, and is exposed to a measurement gas. The reference electrode is provided on the solid electrolytic member, and is exposed to a reference gas. A heater operates for heating the sensor element. A portion of the heater contacts a portion of the sensor element. The temperature of the sensor element is increased to 300° C. by the heater in ten seconds after the start of activation of the heater.

Abstract: A control circuit unit which enables an existing NOx sensor to serve not only as an NOx sensor but also as an oxygen concentration sensor by attachment to an existing NOx sensor. A control circuit unit 31 is connected to an NOx sensor 1. A first pump element control circuit 56 controls a voltage applied to a first pump element 3 so as to control the partial pressure of oxygen in a first processing chamber 9 such that an output voltage of an oxygen concentration detection element becomes substantially constant. A first pump current is detected using a current detection resistor 101 and is then output via an A/D converter circuit 65. A second pump element control circuit 57 applies a constant voltage to a second pump element 5 in a direction so as to pump out oxygen from a second processing chamber 10. A second pump current is detected using a current detection resistor 107 and is then output via an A/D converter circuit 65.

Abstract: A sensor is disclosed that comprises an electrolyte disposed between and in intimate contact with a sensing electrode and a reference electrode. A protective coating is disposed on the protective layer adjacent to the sensing electrode. The protective coating comprises a mixture of a metal oxide, a zeolite, and an alumina. A method for making the sensor is also disclosed.

Abstract: The protective shield arrangement for an exhaust sensor and method of making and using the same is achieved by providing a protective shield for an exhaust gas sensor that comprises a porous mesh material formed as a cap for placement over an end portion of a sensing element. This is formed by a method that comprises providing a unitary piece of the mesh material, and folding the mesh material to form the cap. Thereby, gas passes through the tortuous pathway created by the mesh material to be sensed by the sensor.

Abstract: An exhaust gas sensor is provided and formed by attaching the sensor's upper shield and shell. The attachment is attained by bending a protruding segment or lip over a terminal end portion of the lower shield. This produces a single sealing surface and eliminates the requirement of a conventional crimp which places high compressive forces on the sensing element..

Abstract: An oxygen concentration detector comprises a solid electrolyte 21, a sensing element 2 which consists of the solid electrolyte 21 coated on the surface with an outer electrode 23, a heater 3 provided inside the solid electrolyte 21, and a protecting cover 16 which protects the sensing element 2. The protecting cover 16 has two levels of openings 161, 162, the outer electrode 23 is constructed within the range defined by the length of the heat-generating part 31 of the heater 3, and the relationship between the length L1 of the heat-generating part 31 and the distance between the openings L2 of the two levels of openings 161, 162 in the axial direction is such that L1/L2=0.9 to 1.3.

Abstract: A gas sensor is provided which comprises a sensor element for detecting a component of a gas and a cup-shaped protector for covering a detecting section of the sensor element. The protector is dual-walled and have cup-shaped inner and outer protector members. The inner and outer protector members are constructed and arranged so that g1>g2 where g1 is the distance between an inner surface of a circumferential wall of the outer protector member and an outer surface of a circumferential wall of the inner protector member and g2 is the distance between an inner surface of a bottom wall of the outer protector member and an outer surface of a bottom wall of the inner protector member. The outer protector member has at the circumferential wall thereof a plurality of first gas holes. The inner protector member has at the circumferential wall thereof a plurality of second gas holes.

Abstract: A sensor element has a solid electrolyte body holding a reference gas side electrode and a measurement gas side electrode on surfaces thereof. The measurement gas side electrode is covered with a porous protective layer including a component as a lead getter, which reacts with lead contained in measurement gas. Accordingly, lead is removed from measurement gas by the protective layer not to be attached to the measurement gas side electrode. As a result, the sensor element can be used in measurement gas containing lead, without deteriorating responsibility and output thereof.

Abstract: An oxygen sensor is constituted by a ceramic separator being placed so that the rear thereof enters the inside of a filter holding part and the front enters the inside of a casing and formed with a plurality of lead insertion holes axially penetrating the ceramic separator and an elastic seal member being fitted elastically into a rear opening of the filter holding part and having seal lead insertion holes for inserting leads for sealing the gap between the outer faces of the leads and the inner face of the filter holding part. The rear end face of the ceramic separator is positioned on the rear side behind a gas introduction hole in the axial direction and a predetermined gap is formed between the elastic seal member and the ceramic separator at least at the lead insertion position.

Abstract: A sensor structure which reduces the resistance of insertion in the course of insertion of a metallic terminal member into the hollow portion of an oxygen detection element so as to enable smooth assembly and such that portions of the metallic terminal member become less susceptible to plastic deformation. An attachment portion 23c of a metallic terminal member 23 is in contact with the inner wall surface of a hollow portion 2a of an oxygen detection element 2, directly or indirectly via another member, at opposite sides thereof located along the direction of contact. Also, a gap is formed between an attachment portion 23c and the inner wall surface at opposite sides of the attachment portion 23c located along the direction of gap formation.

Abstract: A gas sensor having improved heat resistance and oil resistance. A portion of a cylindrical cover attached to a metallic shell 29 is formed of a bendable resin tube 50. When the sensor is installed in a location susceptible to oil splashes, a rubber member 54 having intercommunicating holes 58 formed therein can be moved to a position where the rubber member 54 is less susceptible to oil splashes, through appropriate bending of the resin tube 50. Thus, entry of oil into the interior of the sensor is avoided. Also, since the resin tube 50 is bendable, the length of the resin tube 50 can be increased so long as an ambient space around the installed sensor permits, thereby decreasing heat transmitted from the metallic shell 29 to the rubber member 54.

Abstract: A gas sensing element has a solid electrolytic body, a reference gas side electrode provided on a surface of the solid electrolytic body so as to be exposed to a reference gas, and a measured gas side electrode provided on another surface of the solid electrolytic body so as to be exposed to a measured gas. A crystal face strength ratio of the measured gas side electrode according to X-ray diffraction is 0.7≦{I(200)/I(111)} or 0.6≦{I(220)/I(111)}.

Abstract: A gas sensor 1 includes a casing 10 which covers a sensing element 2 and includes two cylindrical members. The cylindrical members are axially disposed in such a manner as to overlap each other. Examples of the cylindrical members are a protector 11 (outer member) and a protector attachment portion 9a (inner member) of a metallic shell 9. A diameter-reduced portion 81 is circumferentially formed on the outer member 11 through, for example, caulking. A weld zone 83 is circumferentially formed at the diameter-reduced portion 81 so as to weld the outer member 11 onto the inner member 9a. Through formation of the diameter-reduced portion 81, a gap between the outer member 11 and the inner member 9a as measured at the position of the weld zone is reduced, thereby improving adhesion therebetween. As a result, possibility of a weld defect arising can be suppressed.

Abstract: In an exemplary embodiment, the present invention provides an exhaust constituent sensor comprising a planar sensing element securely held in place within a tubular shield by disposing a high temperature mat support between the tubular inner shield and the planar sensing element. The high temperature mat support comprises suitable mat material, e.g., ceramic fibers or metal mesh, and preferably, comprises silica fibers, alumina fibers, alumina fibers with vermiculite, or any other suitable mat material providing the desired support, strength, and thermal and electrical insulating properties described herein. It is within the scope of the invention that the high temperature mat support may be in the form of a fibrous material or a more rigid perform structure, wherein in both instances, the high temperature mat support is adapted to be disposed concentrically around the planar sensing element for secure packaging thereof.

Abstract: A total of a most adjacent spacing distance in an axial direction between an outer gas-introducing hole of an outer protective cover and a slit provided at a flange of an intermediate protective cover and a most adjacent spacing distance in the axial direction between the slit of the intermediate protective cover and an inner gas-introducing hole of an inner protective cover is at least not less than 10 mm. Gaps for avoiding accumulation of water due to boundary tension are provided in a radial direction between the outer protective cover and the intermediate protective cover and in the radial direction between the outer protective cover and the inner protective cover.

Abstract: A gas sensor including a detection element having a front-end portion, a detection portion formed at the front-end portion of the detection element, and a protector that covers the detection portion. The protector includes a first portion having a first sidewall and a second portion having a second sidewall disposed outside the first portion. The first sidewall has an axial front end and a tapering portion. The tapering portion is formed from the axial front end of the first sidewall. The side portion has a front-end surface provided with a first gas outlet, and the second portion has a front-end surface provided with a second gas outlet. Furthermore, at least one gas inlet is formed to the sidewall of the second portion opposite the tapering portion, and plural gas inlets are formed on the sidewall of the first portion.

Abstract: A gas sensor comprises a first pump cell 6 including first internal and external electrodes 10 and 11 so formed as to face from inside and outside a first flow passage 2, respectively, for pumping oxygen out from, and into, the first flow passage, and a second pump cell 8 including second internal and external electrodes 14 and 15 so formed as to face from inside and outside a second flow passage 4 communicating with the first flow passage through a diffusion resistance, wherein a measurement gas component undergoes reaction inside the second flow passage 4 and a current corresponding to the concentration of the measurement gas component flows between the electrodes 14 and 15 through the oxygen ion conductor. At least a part of the first internal electrode 10 contains a platinum group element and Cu.

Abstract: A measuring device (e.g., an electrochemical sensor) has a sensor element arranged at a measuring point, the sensor element being arranged in a housing, which is linked via electrical connecting lines to an evaluation circuit away from the measuring point, and the electrical connecting lines being routed, at least in the vicinity of the measuring point, in a protective device. Provision is made that the protective device is joined, with a force-locking and form-locking fit, to the housing via an attachment device, which embraces (surrounds) the housing and the protective device, to form a sealing seat.

Abstract: The present invention is an exhaust sensor seal and a method for making the same. A talc disk disposed between two support disks forms a talc assembly where at least one of which is metal. As pressure is applied to the assembly, the talc is forced into any voids in the sensing end of the exhaust sensor body from exhaust gases.

Abstract: An oxygen sensor including an elongated casing including an exhaust gas inlet through which the exhaust gas from a vehicle engine enters thereinto, a sensing element including an outer planar surface opposed to the exhaust gas inlet, and an inner planar surface on the opposite side of the outer planar surface, and a heater separably disposed on the inner planar surface of the sensing element.

Abstract: An oxygen sensor is constituted by a ceramic separator being placed so that the rear thereof enters the inside of a filter holding part and the front enters the inside of a casing and formed with a plurality of lead insertion holes axially penetrating the ceramic separator and an elastic seal member being fitted elastically into a rear opening of the filter holding part and having seal lead insertion holes for inserting leads for sealing the gap between the outer faces of the leads and the inner face of the filter holding part. The rear end face of the ceramic separator is positioned on the rear side behind a gas introduction hole in the axial direction and a predetermined gap is formed between the elastic seal member and the ceramic separator at least at the lead insertion position.

Abstract: An electrochemical sensor for ascertaining a gas concentration of a measuring gas includes an electrochemical element, including a first solid electrolyte body having an electrochemical pump cell and a first and a second electrode, and having a gas compartment which is connected via a gas access opening to the measuring-gas compartment, and in which one of the two electrodes is arranged. The electrochemical element further includes a second solid electrolyte body having an electrochemical sensor cell (Nernst cell) and a third and a fourth electrode. The surface of the first solid electrolyte body faces the measuring-gas compartment, and the gas access opening is covered by a porous protective layer. The electrochemical sensor includes a layer that exhibits a higher density or a lower porosity compared to the protective layer and that is allocated to the porous protective layer.

Abstract: In an exemplary embodiment, the present invention provides an exhaust constituent sensor comprising a planar sensing element securely held in place within a tubular shield by disposing a high temperature mat support between the tubular inner shield and the planar sensing element. The high temperature mat support comprises suitable mat material, e.g., ceramic fibers or metal mesh, and preferably, comprises silica fibers, alumina fibers, alumina fibers with vermiculite, or any other suitable mat material providing the desired support, strength, and thermal and electrical insulating properties described herein. It is within the scope of the invention that the high temperature mat support may be in the form of a fibrous material or a more rigid preform structure, wherein in both instances, the high temperature mat support is adapted to be disposed concentrically around the planar sensing element for secure packaging thereof.

Abstract: A multilayered air-fuel ratio sensor consists of a plurality of substrate layers. At least one heterogeneous boundary layer is interposed between the plurality of substrate layers. The heterogeneous boundary layer has a thickness in a range of 10 to 100 &mgr;m. The heterogeneous boundary layer absorbs thermal shocks or any other stresses acting on the substrate layers and stops the growth of cracks.

Abstract: A gas sensor, in particular for determining the content of gases in the exhaust of an internal combustion engine, has a contact part carrier composed of two opposing, externally symmetrical half-shells, engaging in and contacting the terminal end of a sensor which runs axially and is installed in a tubular protective sleeve, with the half-shells of the contact part carrier being held together by a spring element. The spring element is designed to exert only a low clamping force on the half-shells of the contact part carrier in a first bracing step when the contact part carrier is pre-mounted on the terminal end of the sensor, so that the sensor can still be inserted easily between the two half-shells. In a second bracing step it presses from all sides against the two half-shells due to the inside wall of the protective sleeve and pushes them against the supporting contact points with a greater force than in the first bracing step.

Abstract: A sensor, particularly for determining the oxygen content in exhaust gasses of internal combustion engines, includes sensor element which is fixed in a metallic housing and a sealing flange which is integrally formed on the housing and rests on a sealing seat which is formed on an exhaust system. The sealing flange has two ring elements which are integrally formed on the housing and each have an inclined sealing surface, a hollow space being formed between the two ring elements inside the housing.

Abstract: An improved structure of a gas sensor is provided which includes a hollow housing and a sensing element. The sensing element has a flange and is disposed within the housing in engagement of the flange with an inner wall of the housing. An insulating powder is packed in a chamber defined by the inner wall of the housing, the flange and an outer wall of the sensing element to provide an air-tight seal between an air chamber to which one end of the sensing element is exposed and a gas chamber to which the other end of the sensing element is exposed. The air-tight seal has the structure designed to minimize an air leakage and breakage of the sensing element when installed in the housing.

Abstract: A sensing element has a cup-shaped solid electrolytic body with one end closed and an inside space serving as a reference gas chamber, a sensing electrode provided on an outer surface of the solid electrolytic body so as to be exposed to measured gas, and a reference electrode provided on an inner surface of the solid electrolytic body so as to be exposed to reference gas in the reference gas chamber. A heater is disposed in the reference gas chamber. The solid electrolytic body has a leg consisting of a proximal portion and a distal portion. The distal portion is thinner than the proximal portion. And, the heater is brought into contact with a surface defining the reference gas chamber at least partly in the region of the distal portion.

Abstract: A gas sensor has a housing integrally formed with a caulked fixation portion. A detection element is inserted into the housing and fixed therein by caulking the caulked fixation portion via a sealing member such as a metallic ring. The caulked fixation portion is composed of a caulked portion and a buckling portion, and satisfies dimensional relationships of T1<T3<T2; 2<T2/T1, and 3<L/{(T1+T2)/2}. T1 is a minimum thickness of the caulked portion, and T2 is a maximum thickness of the caulked portion. T3 is an average thickness of the buckling portion, and L is a length of the caulked portion in an axial direction of the gas sensor.

Abstract: A gas sensor is provided which can efficiently flow air into a casing while having a sufficient on-axis sectional area in a ceramic separator for allowing lead wires to pass therethrough. The oxygen sensor has a ceramic separator main body portion axially formed with a plurality of separator-side lead wire insertion holes penetrating therethrough, whereby a first part thereof is arranged to extend to an inner side of a filter support portion. The first part has an on-axis sectional outer shape formed in a shape other than a circle, e.g. a polygonal shape, such as a square shape. By making the on-axis sectional outer shape of the ceramic separator main body part non-circular as above, it is possible to locally expand a gap defined between an outer peripheral surface of the ceramic separator and an inner surface of the filter support portion.

Abstract: The invention reduces the activation time of an oxygen sensor with a heater through rapid heating of an oxygen sensing element. A shaft-like heating member is inserted and fixed into an oxygen sensing element of a hollow shaft-like member while a terminal member intervenes therebetween. A heating portion is locally formed at an extreme end of the heating member. A surface of the heating portion is elastically pressed against an element inner wall, thereby establishing a laterally-abutting structure. A positioning projection is formed on an internal electrode connecting portion and projects toward the interior of the internal electrode connecting portion. The positioning projection is adapted to position the heating element within a hollow portion of the oxygen sensing element such that the axis thereof becomes substantially parallel to the axis of the hollow portion.

Abstract: It is intended to avoid invasion of oxygen through any route except for an introducing port for a measurement gas so that the amount of oxide or inflammable gas contained in the measurement gas may be measured highly accurately. Insulative layers are provided for respective lead wires at positions corresponding to portions at which the temperature of the oxygen ion-conductive solid electrolyte is increased due to heat generation effected by a heater. Each of the insulative layers is formed to have a pattern in which one end is exposed to a first chamber or a second chamber, and the other end terminates at a position separated by a predetermined distance from a corresponding through-hole. At least the lead wires, which lead to an auxiliary pumping electrode and a detecting electrode, are densified. Preferably, the insulative layers for these lead wires are also densified.

Abstract: Air fuel ratio sensor for use in an exhaust gas purification system for an internal combustion engine. The sensor has an outer and inner cover 12 and 13 for protection of lead wires 16, 18 and 19 to a detecting element 3 and a heater 5 of the sensor, a rubber seal for 2 for obtaining a sealing between the covers and the lead wires and a water repellent filter 36 for obtaining a seal between the inner and outer covers 12 and 13, while keeping an air ventilation capability of the space inside the covers. For receiving the lead wires 16, 18 and 19, the seal 2 is formed with holes 20 such that the minimum thickness between the holes and the minimum thickness between the hole and an outer surface of the seal is 1 mm or more. A crimping of the outer cover 12 is done so that a deformation of the seal 2 in a range between 10 to 20% of the outer diameter is obtained.

Abstract: A gas sensor including a detecting element having electrodes on first and second surfaces of an oxygen ion conductive solid-state electrolyte; a main fitting having a fitting portion to be fitted into a mounting hole formed on a wall of the pipe defining a flow path for a gas-to-be-measured for holding the detecting element in such manner that the first surface is disposed via the mounting hole at an inner position of the pipe with respect to the fitting portion; a cylindrical cover of which one end is connected to an outer position of the pipe with respect to the fitting portion of the main fitting and the other end is provided with a cylindrical sealing member having an air hole for introducing air to the second surface on one end and a through hole through which a lead connected to both electrodes of the detecting element passes on the other end; and a water repellant filter having gas permeability for closing the air hole, characterized in that the water repellant filter is formed in a sheet shape and mou

Abstract: An improved structure of a gas sensor is provided. The gas sensor includes a gas sensitive element, a holder retaining therein the gas sensitive element, and a protective cover installed on the holder. The protective cover has a flange which is retained in a groove formed in the holder by crimping an outer extension formed on the holder adjacent the groove. The geometries of the groove in the holder and the flange of the protective cover are so determined as to provide for ease of installation of the protective cover on the holder, firm engagement of the protective cover with the groove of the holder, and ease of machining of the groove of the holder.

Abstract: There is disclosed an oxygen sensor disposed before an exhaust gas purifying catalyst of an engine which uses a hydrocarbon containing fuel with a H/C ratio of three or more. An oxygen sensor 1 is provided with a solid electrolytic body 2 which can generate a difference in oxygen concentration with reference gas and measured gas, a reference electrode 3 and a detection electrode 4 formed on inner and outer surfaces of the solid electrolytic body 2, and a porous protective layer 5 for covering the detection electrode 4. The detection electrode 4 is formed only of a metal like Pt which promotes oxidizing reaction of methane to have a thickness of 1 to 2 &mgr;m. In the protective layer 5, only a second protective layer 5b carries Pt catalyst 6 which promotes oxidizing reaction of hydrogen, and the amount of carried catalyst is in the range of 0.5 to 7 mol % relative to the whole of the second protective layer 5b.

Abstract: An oxygen analyzer is provided including a shield probe assembly. An inner probe tube resides within the shield probe assembly. Also included is a heater assembly that is mounted to an end of the inner probe tube and situated within the shield probe assembly. A tubular sensor mechanism is removably secured within the heater assembly. A thermocouple-conductor assembly is positioned within the inner probe tube. A calibration tube has an end situated within the sensor. The thermocouple-conductor assembly and inner probe tube are conveniently accessible for repair and replacement.

Abstract: An electrochemical sensor for determining the oxygen content of gases of internal combustion engines includes a ceramic element that is inserted with a sealing ring into a housing. The sealing ring is built up from different metal layers. The arrangement of the metal layers proceeds from a metal support which is composed of a steel alloy. The sealing ring is covered on both sides with a roll-clad copper layer. A nickel layer can additionally be arranged beneath the copper layer.

Abstract: A detecting unit of an oxygen sensor as an A/F sensor has a solid electrolyte layer and a diffusion resistance layer and generates a current value according to the concentration of oxygen in an exhaust gas by applying a voltage across electrodes on an exhaust gas side and an atmosphere side of the solid electrolyte layer. An oxygen supply/exhaust unit has a solid electrolyte layer and a pair of electrodes formed on both faces of the solid electrolyte layer, and supplies oxygen near to the electrode on the atmosphere side of the detecting unit or exhausts oxygen near the electrode. A control unit controls, in response to a limit current value detected by a current detection unit, the amount of supply or exhaust of oxygen of the oxygen supply/exhaust unit on the basis of the detected current value.

Abstract: A gas sensor including a sealing arrangement for sensing exhaust gases of internal combustion engines includes a housing for the sealing arrangement having a longitudinal bore; a planar sensor element secured in the longitudinal bore of the housing; a spring element; upper and lower molded parts that are pressed together by means of the spring element; and a sealing material comprised of a ceramic powder and disposed between the upper and lower molded parts and surrounding the sensor element in a gas-tight manner, wherein the lower molded part consists of a disk-shaped base part and a ring that rests on the disk-shaped base part so that an inside space is defined within the ring for holding the ceramic powder, wherein the upper molded part has a ring-shaped, stepped recess which is pressed into the inside space of the lower molded part, and wherein the ceramic powder in the inside space is held in a compressed state due to compressing forces exerted by the spring element.

Abstract: An oxygen sensor element is inserted and fixed in a housing. A base body is provided at an end of the housing. The base body is made of a resin. The base body has a flange at an end. The housing has a caulking portion which is deformable when received a pressing force acting in a direction parallel to an axis of the oxygen sensor. By deforming the caulking portion, the flange is tightly connected with the caulking portion.

Abstract: A measuring device, in particular, an electrochemical sensor, has a sensor element arranged at a measuring point. The sensor element is arranged in a housing and is connected via electrical connecting lines to an evaluation circuit away from the measuring point. The electrical connecting lines are run, at least in the vicinity of the measuring point, in a protective device. The protective device forms a sealing seat with the housing. The housing in the area of the sealing seat, at least in some areas, has a coating.

Abstract: An oxygen sensor 3 having a heater 2 capable of providing an improved temperature increasing characteristic, while maintaining an increased amount of introduced air and a high production efficiency. The sensor 3 includes a sensor element 1 having an air chamber 100 in which a heater 2 is arranged. The heater 2 has a rectangular cross sectional shape. In order to produce the heater 2, onto a green ceramic sheet, a heater of a predetermined pattern including a plurality of heater sections is printed. Then, to the printed sheet, different ceramic green sheets are applied so as to obtain a laminated body. The laminated body is subjected to a cutting so as to produce an intermediate body in which a heater section is included. The intermediate body is subjected to a firing to obtain a completed heater.

Abstract: A sensor housing (10) for directing the flow of a gas over two sensitive regions (53, 54) of sensing device (52) includes an inner shroud (12) surrounding the sensing device (52). The inner shroud (12) is inserted into an outer shroud (14), such that a plurality of gas channels (44) are formed between the inner shroud (12) and the outer shroud (14). In operation, a gas enters through inlet orifices (28) in the outer shroud (14) and travels through the gas channels (44) to the proximal end (26) of the inner shroud (12). The flow direction of the gas is then reversed and the gas passes through an inner chamber (50) and over sensitive regions (53), (54) located on the surface of the sensing device (52). Vacuum pressure created at an outlet hole (46) located at a distal end (35) of the outer shroud (14) draws the gas out of the inner chamber (50) and return the gas to the exterior of the sensor housing (10).

Abstract: An A/F sensor outputs a linear air-fuel ratio detection signal proportional to the oxygen concentration in an exhaust gas from an engine upon application of a voltage. A computer controls the applied-voltage in a stoichiometric control region, a lean burn control region, an atmosphere detection region and a rich control region to have a fixed value such that the change rate of the applied-voltage is reduced to be less than that in other regions. In addition, when changing the voltage applied to the A/F sensor, the computer variably sets the voltage change speed sequentially. Thus, the influence of the capacitive characteristic of the A/F sensor is eliminated.

Abstract: A gas concentration detector using solid electrolyte layers laminated measures a concentration of gas constituents in measuring gas such as exhaust gas of an internal combustion engine without being influenced by oxygen concentration in the measuring gas. The measuring gas is introduced into an inner cavity of the detector and outside air as a reference gas is introduced into an air passage in the detector. Oxygen concentration in the measuring gas in the inner cavity is maintained at a predetermined level by operation of an oxygen pumping cell constituted by an ion conductive solid electrolyte layer and a pair of electrodes formed on both surfaces of the layer. The oxygen concentration in the inner cavity is measured by an oxygen sensor cell having one electrode exposed to the inner cavity and the other electrode exposed to the reference gas.

Abstract: Disclosed is a gas sensor comprising a sensor element for measuring a predetermined gas component contained in an introduced measurement gas, and a protective cover arranged to surround a forward end of the sensor element; the gas sensor including the sensor element having a gas-introducing port which is disposed at a forward end surface thereof for introducing the measurement gas thereinto; and the protective cover comprising an inner protective cover and an outer protective cover. The inner protective cover is provided with an opening section which makes communication with the gas-introducing port. An inner protective cover space, which is formed between the inner protective cover and the sensor element, is isolated from a communication passage which makes communication from the opening section of the inner protective cover to the gas-introducing port of the sensor element so that the measurement gas principally diffuses and flows from the opening section into the gas-introducing port of the sensor element.

Abstract: An oxygen sensor element includes a solid electrolyte having cavities on a surface thereof and an electrode formed on the surface of the solid electrolyte. In a method of producing the oxygen sensor element, a solution containing a noble metal compound for nucleus formation is first applied to an electrode forming portion of the solid electrolyte to form a coating film. Then, the coating film is heat-treated to form a nucleus forming portion where noble metal nuclei are deposited. Subsequently, metal plating is applied to the nucleus forming portion to form a plating film deeply entering the cavities. Thereafter, the plating film is burned to form the electrode deeply entering the cavities.