Abstract: The present invention provides a gas sensor having excellent humidity resistance even if used in a high temperature and high humidity atmosphere. According to the present invention, a gas sensor is comprised of: a silicon substrate; a metal-oxide semiconductor portion comprised mainly of SnO2 and formed on the substrate; and a catalytic portion comprised of Pd and dispersed on a surface of the metal-oxide semiconductor portion, wherein the metal-oxide semiconductor portion and the catalytic portion constitute a gas sensing portion. Furthermore, an insulating portion comprised mainly of SiO2 is formed dispersedly on a surface of the gas sensing portion.

Abstract: The object of the present invention is to provide a gas sensor in which a gas detection element is mounted on a wiring substrate; in which a protective cap having gas inlets formed therein is attached to the wiring substrate; and which has a structure capable of effectively preventing emanation of gas from the wiring substrate and the protective cap. A gas sensor comprises a gas detecting element on a writing board where a protective cap with air vents is mounted. The sensor effectively prevents a gas from emanating from the wiring board and the protective cap. The wiring board where a plurality of gas detecting elements (8,9) are to be mounted is formed of a ceramic wiring board (2) excellent in heat resistance. The protective cap (3) having air vents (31 to 39) is formed of a metal excellent in heat resistance. The metal protective cap (3) is fitted to the ceramic wiring board (2) instead of using adhesive. In this way a gas sensor (1) is manufactured.

Abstract: There is provided an oxidizing gas sensor that includes an insulating substrate, a gas sensing layer laminated on the insulating substrate and substantially made of tin oxide so as to make resistance changes in response to concentration variations in oxidizing gas and a plurality of catalyst grains applied to a surface of the gas sensing layer and substantially made of gold, wherein 20% or more of the catalyst grains have an aspect ratio of 2.0 or greater when viewed at from the surface of the gas sensing layer.

Abstract: The present invention provides a gas sensor having excellent humidity resistance even if used in a high temperature and high humidity atmosphere. According to the present invention, a gas sensor is comprised of: a silicon substrate; a metal-oxide semiconductor portion comprised mainly of SnO2 and formed on the substrate; and a catalytic portion comprised of Pd and dispersed on a surface of the metal-oxide semiconductor portion, wherein the metal-oxide semiconductor portion and the catalytic portion constitute a gas sensing portion. Furthermore, an insulating portion comprised mainly of SiO2 is formed dispersedly on a surface of the gas sensing portion.

Abstract: A micro-heater including a semiconductor substrate having a cavity; an insulating layer provided on an upper side of the semiconductor substrate and closing the cavity; and a heater element embedded in a portion of the insulating layer above the cavity and including a metallic material. The insulating layer includes: a compressive stress film made of silicon oxide; and a tensile stress film made of silicon nitride. The tensile stress film has a thickness not less than that of the compressive stress film.

Abstract: A mass flow sensor includes a semiconductor substrate 1, an insulating thin film 2, heaters 311 and 312, temperature measurement resistors 321 and 322, and a protective layer 4. The heaters 311 and 312 are formed on the surface of the insulating thin film 2, and are provided adjacently such that the heater 311 is provided upstream the heater 312 and the heater 312 is provided downstream the heater 311. A cavity 5 is formed below the heaters 311 and 312, and the heaters are thermally insulated from the remaining portion of the semiconductor substrate. The temperature measurement resistors 321 and 322 are formed on the top surface of the insulating thin film 2, and are provided at opposite sides of the heaters 311 and 312, such that the resistors are aligned with respect to the flow passage of a fluid. In the mass flow sensor and the mass flowmeter including the sensor, the flow rate and flow direction of a fluid can be detected by means of merely the heaters 311 and 312, which are active elements.

Abstract: A split-flow-type flowmeter includes a detection element 2 disposed to face a flow path thereof and a venturi structure 4 formed within a flow path 1 in the vicinity of the detection element 2 and adapted to throttle a flow directed toward the detection element 2 to thereby reduce disturbance of the flow. The venturi structure 4 is disposed in opposition to the detection element 2 within the flow path 1 and includes a protrusion 5 protruding toward the detection element 2 within the flow path 1 of the split-flow-type flowmeter.

Abstract: A split-flow-type flowmeter in which an end portion of a flow splitter tube 1 is inserted into a main-flow pipe 10 having a diameter D. A flow splitter tube 1 includes a U-shaped split-flow passage 1a. A detection element is disposed at a bottom portion (not shown) of the U-shaped split-flow passage 1a. The split-flow passage 1a assumes a flow path structure symmetrical with respect to a plane passing through the detection element. A flow inlet 2a and a flow outlet 2b of the split-flow passage 1a face in mutually opposite directions along the flow direction of the main-flow pipe 10 and open symmetrically at the same position on the flow cross section of the main-flow pipe 10.

Abstract: A mass flow sensor includes a semiconductor substrate 1, an insulating thin film 2, heaters 311 and 312, temperature measurement resistors 321 and 322, and a protective layer 4. The heaters 311 and 312 are formed on the surface of the insulating thin film 2, and are provided adjacently such that the heater 311 is provided upstream the heater 312 and the heater 312 is provided downstream the heater 311. A cavity 5 is formed below the heaters 311 and 312, and the heaters are thermally insulated from the remaining portion of the semiconductor substrate. The temperature measurement resistors 321 and 322 are formed on the top surface of the insulating thin film 2, and are provided at opposite sides of the heaters 311 and 312, such that the resistors are aligned with respect to the flow passage of a fluid. In the mass flow sensor and the mass flowmeter including the sensor, the flow rate and flow direction of a fluid can be detected by means of merely the heaters 311 and 312, which are active elements.

Abstract: A flow measurement device is disclosed, in which an accumulation of pollution substance onto a detection element is prevented, and which can measure a reverse flow similarly to a normal flow. On both ends of an outer wall 23 outer peripheral portion of a divided flow pipe 20 having a &OHgr;-shape pipe passage, there are oppositely formed an inlet port 25 and an outlet port 26, which open in faces orthogonal to a flow direction of a main flow M that is a detection object. Within the divided flow pipe 20, by a curved partition 27, plural branch flow passages 28a, 28b mutually branching and joining in the divided flow pipe 20 are formed.

Abstract: A split-flow-type flowmeter includes a detection element 2 disposed to face a flow path thereof and a venturi structure 4 formed within a flow path 1 in the vicinity of the detection element 2 and adapted to throttle a flow directed toward the detection element 2 to thereby reduce disturbance of the flow. The venturi structure 4 is disposed in opposition to the detection element 2 within the flow path 1 and includes a protrusion 5 protruding toward the detection element 2 within the flow path 1 of the split-flow-type flowmeter.

Abstract: A flow rate and flow velocity measurement device. A part of a flow 10 in a main flow pipe 1, which is a detection object, is introduced into a passage of a divided flow pipe 2 and becomes a flow 11. The divided flow pipe 2 has a curved portion 2c or rather an inverted arc portion in which the flow is abruptly changed in direction or rather inverted by protuberances 2a, 2b formed preferably in symmetry in upstream and downstream sides of the curved portion 2c. Outside the main flow pipe 1, there is disposed on the bottom portion of the curved portion 2c of the divided flow pipe 2 a detection element 5 fixed to a support body 4 while protruding preferably 0.05-0.3 mm from flow passage faces 2e, 2f in the vicinity thereof. An opposed face 2d opposite to the detection element 5 protrudes toward the detection face so as to throttle the passage and to accelerate a flow speed at the element.

Abstract: A flow rate and flow velocity measurement device has a divided flow pipe (332) which is attached so as to be orthogonal to an intake pipe (1) of an engine, and into which a flow in the intake pipe (1) is introduced, an inlet plate (334) which extends in a direction orthogonal to a flow direction in the intake pipe (1) and forms a U-shape form pipe passage in the divided flow pipe (332) and a detection element (331) which is disposed so as to be exposed to a flow in the divided flow pipe (332) outside the intake pipe (1) and detects a flow rate and a flow velocity, wherein one end of the inlet plate (334) protrudes into the intake pipe (1) while passing a top opening of the divided flow pipe (332), and the divided flow pipe (332) has a flow passage structure symmetrical with the detection element (331) being made a center, so that an equivalent detection element (331) output is obtained in regard to both cases in which a fluid flows through the intake pipe (1) in a normal direction and a reverse direction.

Abstract: A flow rate and flow velocity measurement device. A part of a flow 10 in a main flow pipe 1, which is a detection object, is introduced into a passage of a divided flow pipe 2 and becomes a flow 11. The divided flow pipe 2 has a curved portion 2c or rather an inverted arc portion in which the flow is abruptly changed in direction or rather inverted by protuberances 2a, 2b formed preferably in symmetry in upstream and downstream sides of the curved portion 2c. Outside the main flow pipe 1, there is disposed on the bottom portion of the curved portion 2c of the divided flow pipe 2 a detection element 5 fixed to a support body 4 while protruding preferably 0.05-0.3 mm from flow passage faces 2e, 2f in the vicinity thereof. An opposed face 2d opposite to the detection element 5 protrudes toward the detection face so as to throttle the passage and to accelerate a flow speed at the element.

Abstract: A split-flow-type flowmeter in which an end portion of a flow splitter tube 1 is inserted into a main-flow pipe 10 having a diameter D. A flow splitter tube 1 includes a U-shaped split-flow passage 1a. A detection element is disposed at a bottom portion (not shown) of the U-shaped split-flow passage 1a. The split-flow passage 1a assumes a flow path structure symmetrical with respect to a plane passing through the detection element. A flow inlet 2a and a flow outlet 2b of the split-flow passage 1a face in mutually opposite directions along the flow direction of the main-flow pipe 10 and open symmetrically at the same position on the flow cross section of the main-flow pipe 10.

Abstract: A flow rate and flow velocity measurement device has a divided flow pipe 332 which is attached so as to be orthogonal to an intake pipe 1 of an engine, and into which a flow in the intake pipe 1 is introduced, an inlet plate 334 which extends in a direction orthogonal to a flow direction in the intake pipe 1 and forms a U-shape form pipe passage in the divided flow pipe 332, and a detection element 331 which is disposed so as to be exposed to a flow in the divided flow pipe 332 outside the intake pipe 1 and detects a flow rate and a flow velocity, wherein one end of the inlet plate 334 protrudes into the intake pipe 1 while passing a top opening of the divided flow pipe 332, and the divided flow pipe 332 has a flow passage structure symmetrical with the detection element 331 being made a center, so that an equivalent detection element 331 output is obtained in regard to both cases in which a fluid flows through the intake pipe 1 in a normal direction and a reverse direction.

Abstract: A hollow ceramic piston pin has a pair of ribs in the form of partition walls axially separating the inside thereof. The piston pin has the ribs in the axial positions where it mates diameterially opposed inner ends of piston pin bosses of a piston and opposite ends of a small end portion of a connecting rod when attached to the piston and the connecting rod.

Abstract: Ceramic and metal shafts are joined at their ends by brazing, with a buffer member being interposed therebetween. The joined ends of the ceramic and metal shafts and the buffer member are received within a metal sleeve and joined by brazing to part of the inner circumferential wall of the metal sleeve in such a manner than an axial end of the joint where the inner circumferential wall is securely joined to the ceramic and metal shafts is positioned between opposite axial ends of the metal sleeve and at the same time between opposite axial ends of the ceramic shaft. The outer circumferential wall of the metal sleeve is formed with an annular groove in the place corresponding to the above mentioned axial end of the joint with respect to the axial direction of the metal sleeve.

Abstract: An inclined surface of a valve head extending between a valve stem and a valve seat contacting portion has an annular portion in the place intermediate between the valve steam and the valve seat contacting portion. The inclined surface is ground at the annular portion only.

Abstract: An end of a rocker arm proper is formed into a stepped shape and includes a base section and a mounting section projecting outwardly from the base section. A ceramic tip and a soldering or brazing metal have the same plane figure as the mounting section. The ceramic tip is soldered or brazed to the mounting section by means of a continuous furnace. During conveyance by a conveyor to and from the continuous furnace, the ceramic tip and the soldering or brazing metal are held in place on the mounting section by a jig. The jig is in the form of a framework and adapted to be installed on the base section and fittingly receive therein the mounting section. The jig is also adapted to fittingly receive therein the ceramic tip and the soldering or brazing metal.