Ngk Insulators, Inc.

Hiroshi Kurachi

Nobuhide Kato

Sang Jae Lee

Nobukazu Ikoma

Fujio Ishiguro

Takeya Miyashita

Takayuki Ogasawara

Yutaka Ogura

Yuichi Sasaki

Makoto Noda

Satoshi Yamada

A manufacturing method of a honeycomb structure that can improve a manufacturing efficiency and a raw material yield is provided. There is provided a manufacturing method of a honeycomb structure comprising: subjecting a raw material to extrusion forming to form a honeycomb formed bodyhaving a partition wall that partitions a plurality of cells that serve as flow paths for a fluid and are extended from one end surface to the other end surface; forming a plurality of notches extended in a direction along which the cells are extended in the honeycomb formed bodyto form a partial segment aggregatein such a manner that a plurality of partial segmentsare partitioned; and forming a buffer portionbetween respective partial segmentsadjacent to each other in the partial segment aggregateto fill an entire space between the respective partial segments adjacent to each other, thereby obtaining a honeycomb structure

Manufacturing method of honeycomb structure

A gas sensor includes a first space for a measurement gas from a gas-introducing hole via a first diffusion rate-determining section, a main pumping means for controlling a partial pressure of oxygen in the measurement gas introduced into the first space to have a predetermined value, a second space for the measurement gas from the first space via a second diffusion rate-determining section, and a measuring pumping means for reducing or decomposing a NOx component in the measurement gas introduced from the second space via a third diffusion rate-determining section so that oxygen produced thereby is pumped out to detect a current generated by pumping out the oxygen. A ratio (Wc/We) between a width (We) of an end of a sensor element and a width (Wc) of the gas-introducing hole is not less than 0.3 and less than 0.7.

Gas sensor

The present invention provides a gas sensor which allows separation to hardly occur. A gas sensorincludes a gas detecting sectionand a heater sectionsecured in the gas sensor, the heater section 8 including a heating elementand a supportwhich supports at least the heating element. An opening sectionis provided to reduce pressure generated between the heating elementand the support

A gas sensor includes a sensor element having a specific function, and a housing containing the sensor element therein and including a thread section, and a sealing surface which forms a sealing section together with an installation section at a position deeper than the thread section in a direction in which the sensor element is inserted. When the housing is screwed into the installation section, the release torque of the housing at 850&#xb0; C. (1123 K) is 9 N&#xb7;m or more, and an estimated value of a gap formed between the sealing surface and the installation section at 850&#xb0; C. (1123 K) that is calculated according to a specific equation is 31 &#x3bc;m or less.

Gas sensor, gas sensor installation structure, and method for installing gas sensor

A gas sensor includes a sensor element having a specific function, and a housing containing the sensor element therein and including a thread section, and a sealing surface which forms a sealing section together with an installation section at a position deeper than the thread section in a direction in which the sensor element is inserted. When the housing is screwed into the installation section, the release torque of the housing at 850&deg; C. (1123 K) is 9 N&middot;m or more, and an estimated value of a gap formed between the sealing surface and the installation section at 850&deg; C. (1123 K) that is calculated according to a specific equation is 31 &mgr;m or less.

An NOx removal system has a combustion apparatus for applying energy to a load based on a predetermined combustion control process, an NOx remover for reacting NOx emitted from the combustion apparatus with NH to produce N and H O, an NH and/or urea introducing apparatus connected upstream of the NOx remover, for introducing NH and/or urea into a gas passage extending from the combustion apparatus to the NOx remover, and sensor, which is also sensitive connected downstream of the NOx remover, for generating a detected signal based on NH and NOx contained in a gas discharged from the NOx remover. A controller controls a rate at which NH and/or urea is introduced into the gas passage by the NH and/or urea introducing apparatus while repeatedly increasing and reducing the rate, in response to the detected signal generated by the NOx sensor. The NOx removal system, which employs NH and/or urea as a reducing agent, is capable of accurately controlling the rate at which NH and/or urea is introduced into the gas passage through a simple arrangement, and minimizing the discharge of NH and NOx.

System for removing NOx from exhaust gases

A gas sensor is disclosed in order to decrease the offset value to a degree in which no trouble occurs in the measurement without causing any reduction of NOx so that the measurement accuracy for NOx is improved. In the gas sensor, NOx contained in a measurement gas introduced into a second chamber is decomposed by means of catalytic action and/or electrolysis to pumping-process oxygen produced by the decomposition so that NOx is measured on the basis of a pumping current flowing through a measuring pumping cell thereby. The gas sensor has the following pattern of a heater. That is, a minute pitch is provided for a pattern at a portion corresponding to the forward end of a sensor element, a coarse pitch is provided for a pattern at a central portion, and a pattern is removed at a portion corresponding to the backward end of the sensor element. Thus, the measuring pumping cell is allowed to have a resistivity of electronic conduction of not less than 1 M&OHgr; after conversion into a resistance value.

In a method of controlling an exhaust gas system of an internal combustion engine including a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst, the nitrogen oxide reducing catalyst and the nitrogen oxide sensor are disposed in the exhaust gas system operated mainly under a lean condition, respectively. An output value of the nitrogen oxide sensor is compared with a predetermined value, and an operation condition of the internal combustion engine is temporarily changed into a stoichiometric condition or a rich condition, or a fuel is injected upstream of the nitrogen oxide reducing catalyst, so that the nitrogen oxide adsorbed to the nitrogen oxide reducing catalyst is detached or decomposed, and again the internal combustion engine is operated under the lean condition. Deterioration of the catalyst is determined based on Nox amount which is calculated from the sensor output, exhaust has flow amount and vehicle running distance.

Method of controlling an engine exhaust gas system and method of

In a method of controlling an exhaust gas system of an internal combustion engine including a nitrogen oxide reducing catalyst capable of adsorbing nitrogen oxide under a lean atmosphere and a nitrogen oxide sensor disposed downstream of the nitrogen oxide reducing catalyst, the nitrogen oxide reducing catalyst and the nitrogen oxide sensor are disposed in the exhaust gas system operated mainly under a lean condition, respectively. An output value of the nitrogen oxide sensor is compared with a predetermined value, and an operation condition of the internal combustion engine is temporarily changed into a stoichiometric condition or a rich condition, or a fuel is injected upstream of the nitrogen oxide reducing catalyst, so that the nitrogen oxide adsorbed to the nitrogen oxide reducing catalyst is detached or decomposed, and again the internal combustion engine is operated under the lean condition.

A method for removing nitrogen oxides out of the exhaust gas from a combustion apparatus is provided by reducing the nitrogen oxides with injected ammonia or urea to produce nitrogen and water. The method further includes the provision of at least one, sensor placed downstream from the nitrogen oxides removal step for measuring the concentration of the residual ammonia and nitrogen oxides in the exhaust gas after the nitrogen oxides removal step. The method also further includes the provision of a controller for controlling the rate that the ammonia and/or urea is injected into the exhaust gas so that the rate of ammonia and/or urea injection is repeatedly increased and decreased in response to the signal generated by the sensor about a reference value plus the average of the increased and reduced rates of ammonia and urea injection.

Method of removing NO.sub.x from exhaust gases

A method for controlling an engine exhaust gas system includes the steps of detecting an air-fuel ratio of exhaust gas discharged from an internal engine by an oxygen sensor, controlling the exhaust gas to near the stoichiometric air-fuel ratio by a closed-loop control referring to a resultant signal, and leading the exhaust gas to a three-way catalyst to treat nitrogen oxide, hydrocarbon and carbon monoxide. A nitrogen oxide sensor is provided downstream of the three-way catalyst, and a control value of air-fuel ratio by a closed loop control by the oxygen sensor is corrected to set the nitrogen oxide concentration to a predetermined value in accordance with an output of the nitrogen oxide sensor. The deterioration of the three-way catalyst and/or oxygen sensor is detected by comparing a change in control corrected value for the air-fuel ratio of closed loop control referring to an output of the nitrogen oxide sensor with a predetermined value.

Method for controlling engine exhaust gas system

An oxygen sensor having an excellent durability against poisoning by Si is provided by adhering at least one oxide of Mg, Ca, Sr or Ba on the surface or in the pores of the protective layer covering the measuring electrode of the oxygen sensor.

Oxygen sensor and method of producing the same

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.

Electrode structure of an oxygen sensing element

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. The NOx concentration is determined, based on a difference between two outputs of the first and second detecting elements which represent the oxygen partial pressures of respective portions of the measurement gas detected by the first and second detecting elements.

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Aichi-gun, Japan

Hiroshi Kurachi