Abstract: A sensor device is equipped with a housing having an element cover retaining a sensor element such that a detection section of the sensor element is positioned at the tip end of the sensor element. The element cover includes an inner cover provided with inner side holes and an inner tip face hole respectively provided therein, and an outer cover provided with outer side holes in a side thereof, with the tip position of the outer side holes located closer to the tip end than is the tip position of the inner cover. Between the outer surface of the inner cover and the inner surface of the outer cover there is a large clearance section at the tip end and a small clearance section at the base end, providing a flow path that is shaped for connecting the large clearance section and the small clearance section without a step.

Abstract: A sensor device includes an element cover at the tip end of a housing, retaining a sensor element. An outer cover is provided with outer side holes, with the tip position of the outer side holes being farther toward the tip end than is the tip position of an inner cover, and a first flow passage having a gas flow direction that is at right angles to the axial direction is formed at the inner side of the outer cover. An inner side hole in the inner cover is open to a second flow passage provided between the side surfaces of the inner cover and the outer cover, and a detection surface of the sensor element is located on an extension line in an extension direction of a guide member which extends obliquely into the interior of the inner cover from the tip-position edge of the inner side hole.

Abstract: A gas sensor is provided which includes a hollow metallic housing, a sensor device installed in the housing, and a seal disposed in the housing to hermetically isolate between the housing and the sensor device. The housing has an inner shoulder formed on an inner periphery thereof. The seal is retained on the inner shoulder. The seal is made up of a powder body and a glass body. The powder body is made of inorganic powder and mounted on the inner shoulder. The glass body is arranged on the powder body and has a varying coefficient of thermal expansion which alleviates a difference in thermal expansion between the sensor device and the housing, thereby ensuring the stability of hermetic sealing ability of the seal in high-temperature environments.

Abstract: A sensor device is equipped with a housing having an element cover retaining a sensor element such that a detection section of the sensor element is positioned at the tip end of the sensor element. The element cover includes an inner cover provided with inner side holes and an inner tip face hole respectively provided therein, and an outer cover provided with outer side holes in a side thereof, with the tip position of the outer side holes located closer to the tip end than is the tip position of the inner cover. Between the outer surface of the inner cover and the inner surface of the outer cover there is a large clearance section at the tip end and a small clearance section at the base end, providing a flow path that is shaped for connecting the large clearance section and the small clearance section without a step.

Abstract: A sensor device includes an element cover at the tip end of a housing, retaining a sensor element. An outer cover is provided with outer side holes, with the tip position of the outer side holes being farther toward the tip end than is the tip position of an inner cover, and a first flow passage having a gas flow direction that is at right angles to the axial direction is formed at the inner side of the outer cover. An inner side hole in the inner cover is open to a second flow passage provided between the side surfaces of the inner cover and the outer cover, and a detection surface of the sensor element is located on an extension line in an extension direction of a guide member which extends obliquely into the interior of the inner cover from the tip-position edge of the inner side hole.

Abstract: The gas sensor is equipped with a sensor device, a plurality of electrode springs contacting with electrodes and of the sensor device, an insulator retaining the electrode springs, and a plurality of leads connected to the respective electrode springs. Each of the electrode springs includes a retained portion retained by the insulator and a contact portion which is bent and inclined from the retained portion toward a front end side of the sensor device in the lengthwise direction. The contact portion is elastically deformed in contact with the electrode. Each of the electrode springs also includes a bent portion between the contact portion and the retained portion. The bent portion constitutes a base end of the contact portion and is oriented toward the base end side of the gas sensor in the lengthwise direction, thereby enabling the length of the sensor device to be decreased and improving the heat resistance of the electrode springs.

Abstract: The gas sensor is equipped with a sensor device, a plurality of electrode springs contacting with electrodes and of the sensor device, an insulator retaining the electrode springs, and a plurality of leads connected to the respective electrode springs. Each of the electrode springs includes a retained portion retained by the insulator and a contact portion which is bent and inclined from the retained portion toward a front end side of the sensor device in the lengthwise direction. The contact portion is elastically deformed in contact with the electrode. Each of the electrode springs also includes a bent portion between the contact portion and the retained portion. The bent portion constitutes a base end of the contact portion and is oriented toward the base end side of the gas sensor in the lengthwise direction, thereby enabling the length of the sensor device to be decreased and improving the heat resistance of the electrode springs.

Abstract: The gas sensor includes a sensor element, a first insulator inside which the sensor element is inserted, a second insulator disposed on a proximal side of the first insulator so as to cover a proximal side of the sensor element, and a contact member held by the second insulator and sandwiching the sensor element. A proximal end portion of the first insulator and a distal end portion of the second insulator abut on each other in an axial direction. Each the proximal end portion and the distal end portion is provided with a positioning structure. The positioning structure is configured to restrict a relative movement between the first and second insulators in a sandwiching direction in which the sensor element is sandwiched by the contact member and in an orthogonal direction perpendicular to the sandwiching direction and in the axial direction.

Abstract: A gas sensor is provided which includes a hollow metallic housing, a sensor device installed in the housing, and a seal disposed in the housing to hermetically isolate between the housing and the sensor device. The housing has an inner shoulder formed on an inner periphery thereof. The seal is retained on the inner shoulder. The seal is made up of a powder body and a glass body. The powder body is made of inorganic powder and mounted on the inner shoulder. The glass body is arranged on the powder body and has a varying coefficient of thermal expansion which alleviates a difference in thermal expansion between the sensor device and the housing, thereby ensuring the stability of hermetic sealing ability of the seal in high-temperature environments.

Abstract: The gas sensor includes a sensor element, a first insulator inside which the sensor element is inserted, a second insulator disposed on a proximal side of the first insulator so as to cover a proximal side of the sensor element, and a contact member held by the second insulator and sandwiching the sensor element. A proximal end portion of the first insulator and a distal end portion of the second insulator abut on each other in an axial direction. Each the proximal end portion and the distal end portion is provided with a positioning structure. The positioning structure is configured to restrict a relative movement between the first and second insulators in a sandwiching direction in which the sensor element is sandwiched by the contact member and in an orthogonal direction perpendicular to the sandwiching direction and in the axial direction.

Abstract: The gas sensor includes a sensor element having electrode pads formed in its electrode forming surfaces at the proximal end portion thereof, an insert-holding insulator insert-holding the sensor element, a housing insert-holding the insert-holding insulator, and a terminal unit. The proximal end portion of the sensor element is held by the terminal unit which includes a pair of proximal end insulators formed with metal terminals at their inner surfaces, and a spring member pressing the proximal end insulators in a direction that they approach each other. Each of the proximal end insulators includes an insulator contact portion in contact with one of the electrode forming surfaces. The insulator contact portion is located closer to the proximal end of the sensor element than a terminal contact portion at which the metal terminal contacts a corresponding one of the electrode pads.

Abstract: The gas sensor includes a sensor element having electrode pads formed in its electrode forming surfaces at the proximal end portion thereof, an insert-holding insulator insert-holding the sensor element, a housing insert-holding the insert-holding insulator, and a terminal unit. The proximal end portion of the sensor element is held by the terminal unit which includes a pair of proximal end insulators formed with metal terminals at their inner surfaces, and a spring member pressing the proximal end insulators in a direction that they approach each other. Each of the proximal end insulators includes an insulator contact portion in contact with one of the electrode forming surfaces. The insulator contact portion is located closer to the proximal end of the sensor element than a terminal contact portion at which the metal terminal contacts a corresponding one of the electrode pads.

Abstract: A gas concentration detecting system has a first cell generating electric current at first oxygen sensitivity, a second cell generating current at second oxygen sensitivity and a reference cell generating current at reference oxygen sensitivity. The cells have the same structure except that the second cell has a catalyst layer for removing hydrogen as from measured gas containing oxygen gas. The system determines first corrected current from current of the first cell exposed to measured gas, current of the first cell exposed to inspection gas containing oxygen gas at reference concentration and reference cell current of the reference cell exposed to inspection gas, determines second corrected current from current of the second cell exposed to measured gas, current of the second cell exposed to inspection gas and the reference cell current, and detects concentration of hydrogen gas in measured gas from the corrected currents.

Abstract: A gas sensor includes a heater, leads connecting electrically with terminals of the heater, and a porcelain insulator surrounding the terminals of the heater within an air cover. The gas sensor also includes a recess formed in an end of the porcelain insulator to define a clearance between itself and an inner wall of the air cover. A gas flow path is defined to extend from an inner chamber of the air cover to a ventilator through a clearance between an outer periphery of the porcelain insulator and an inner periphery of the air cover and the recess to lead the gas having entered the inner chamber outside the sensor, thereby minimizing the entrance of the gas into the porcelain insulator to avoid the exposure of the terminals to the gas. This avoids the corrosion of the terminals with the gas to ensure the mechanical durability of the gas sensor.

Abstract: An improved structure of a gas sensor designed to withstand physical impact which may result in damage such as cracks to a sensor element built in the gas sensor. Specifically, the gas sensor includes a buffer provided by a clearance between an air cover a porcelain insulator. The clearance is in a range of 1 to 2.5 mm at a minimum. The gas sensor may alternatively have a harder portion in the air cover which has a Vickers hardness of 200 to 400. The gas sensor may alternatively have a rigidity enhancer in the air cover which works to provides an increased rigidity to the air cover.

Abstract: An improved structure of a gas sensor designed to withstand physical impact which may result in damage such as cracks to a sensor element built in the gas sensor. Specifically, the gas sensor includes a buffer provided by a clearance between an air cover a porcelain insulator. The clearance is in a range of 1 to 2.5 mm at a minimum. The gas sensor may alternatively have a harder portion in the air cover which has a Vickers hardness of 200 to 400. The gas sensor may alternatively have a rigidity enhancer in the air cover which works to provides an increased rigidity to the air cover.

Abstract: The present invention provides a process for producing optically active 3-hydroxy-4-methoxypyrrolidine, which is an intermediate for synthesizing a quinuclidine derivative useful as a squalene synthetase inhibitor, a salt thereof, or a hydrate thereof by subjecting a pyrrolidine derivative represented by the following formula (1-4): wherein R3a and R3b are different and each of R3a and R3b represents a hydrogen atom or a methyl group, to optical division purification by using an optically active dibenzoyltartaric acid derivative or the like.

Abstract: The present invention provides a process for producing optically active 3-hydroxy-4-methoxypyrrolidine, which is an intermediate for synthesizing a quinuclidine derivative useful as a squalene synthetase inhibitor, a salt thereof, or a hydrate thereof by subjecting a pyrrolidine derivative represented by the following formula (1-4): 1

Abstract: Disclosed are a novel process for preparing D-alloisoleucine and an improved process for epimerizing L-isoleucine to prepare D-alloisoleucine. In the former process, (2S, 3S)-tartaric acid derivative of formula I below; wherein R stands for a hydrogen atom, a C1-C3 lower alkyl group, lower alkoxy group, chlorine atom, bromine atom and nitro group; and “n” is a number of 0, 1 and 2; is combined with an epimer mixture of L-isoleucine and D-alloisoleucine in a reaction medium to form a complex of D-alloisoleucine and the compound of formula I. The precipitated complex is decomposed by putting it in an alcohol to isolate D-alloisoleucine. In the latter process, L-isoleucine is suspended in an inert solvent which does not substantially dissolve amino acids, and epimerized in the presence of C1-C5 saturated lower fatty acid and salicylaldehyde.