Denso Corporation

Toyota Jidosha Kabushiki Kaisha

Shinichiro Imamura

Tomio Sugiyama

Hiroshi Sawada

Makoto Nakae

Syuichi Nakano

Hiromi Sano

Akio Tanaka

Masahiro Shibata

Susumu Naito

Toru Kidokoro

Isao Watanabe

Yasushi Iwazaki

Satoshi Hada

Naoto Miwa

Keigo Mizutani

Daisuke Shibata

Namitsugu Fujii

A NOx amount capable of being absorbed by a criteria catalyst as a boundary between degradation and normality is supplied to a NOx storage reduction catalyst and thereafter, a reducer amount corresponding to the NOx amount is supplied by a rich spike operation. Degradation of the NOx catalyst is determined based upon the output of the NOx sensor at this time. Since the degradation of the NOx catalyst is determined only by a magnitude of the NOx sensor output, the degradation diagnosis can be performed with high precision. While the catalyst is normal, the excessive reducers are not supplied and therefore, deterioration of the fuel consumption can be prevented.

Degradation diagnostic apparatus for NOx catalyst

The NOx sensor malfunction diagnostic device includes a control section. The control section performs the supplying of an excess amount of reducing agent, which is more than an amount required to reduce adsorbed NOx in a NOx reduction catalyst when a predetermined amount of NOx has been adsorbed in the NOx catalyst, and detects malfunctions of the NOx sensor based on NOx sensor output signal when the excess amount of reduction agent is supplied.

NOx sensor malfunction diagnostic device and malfunction diagnostic method

An NOx catalyst of storage reduction type and an after-catalyst NOx sensor are provided in an exhaust passage in an internal combustion engine. The after-catalyst NOx sensor detects the NOx concentration on the downstream side of the NOx catalyst. The NOx concentration on the upstream side of the NOx catalyst is detected or estimated. The possible abnormality of the after-catalyst NOx sensor is determined by comparing the NOx concentration on the upstream side of the NOx catalyst detected or estimated and the NOx concentration detected by the after-catalyst NOx sensor, under the condition that the NOx catalyst does not substantially absorb NOx in exhaust gas. Abnormality diagnosis is performed with the possible impact of the NOx catalyst inhibited.

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A gas sensor element which may be employed in measuring the concentration of gas such Ois provided. The gas sensor element is of a laminated type and designed to introduce gas to be measured into a measurement gas chamber through a diffusion resistor. The measurement gas chamber has a volume of 0.15 mmin order to facilitate expelling of the gas remaining within the measurement gas chamber during transition of thermal activation of the gas sensor element.

Quickly activatable structure of gas sensor element

A multilayered gas sensing elementis positioned in a cylindrical housingvia a cylindrical insulatorThe multilayered gas sensing elementincludes a narrow-width portionand a wide-width portionThe wide-width portionis in a fixed relationship with respect to the insulatorThe narrow-width portionis in a floating relationship with respect to the insulatorThe narrow-width portionhas a gas sensing portion for detecting the concentration of a specific gas contained in a measuring objective gas.

Gas sensor incorporating a multilayered gas sensing element

A nonfragile ad quickly activatable structure of a gas sensor element which may be built in a gas sensor employed in an air-fuel ratio control system for automotive vehicles for measuring the concentration of gas such O , NOx, or CO. The gas sensor element is made of a lamination of a measurement gas electrode, a reference gas electrode, and a heater. The heater works to elevate the temperature of the gas sensor element up to a given value required to bring the gas sensor element into an activated condition. The heater includes a heater substrate, a heating element, and power supply leads. A minimum distance X between an edge of the heater substrate and an edge of the heating element meets a relation of 0.1 mm&lE;X&lE;0.6 mm, thereby minimizing a thermal expansion difference between the heater element and the heater substrate to avoid cracks in a portion of the heater substrate near the heater element. It also becomes possible to elevate the temperature of the heating element up to a higher value, thereby allowing the gas sensor element to be activated quickly immediately after the power is supplied to the heating element.

Nonfragile and quickly activatable structure of gas sensor element

A gas sensor includes a body having a measurement-gas chamber and a reference-gas chamber. The measurement-gas chamber is supplied with a measurement gas. The reference-gas chamber is supplied with a reference gas. A detecting cell provided in the body includes (1) a solid electrolyte member, (2) a measuring electrode provided on the solid electrolyte member and facing the measurement-gas chamber, and (3) a reference electrode provided on the solid electrolyte member and facing the reference-gas chamber. A heater portion operates for heating the detecting cell. The heater portion includes (1) a first substrate, (2) a heating member provided on the first substrate, (3) a high-voltage-side lead portion provided on the first substrate and electrically connected to the heating member, (4) a low-voltage-side lead portion provided on the first substrate and electrically connected to the heating member, and (5) a second substrate covering the heating member. The first substrate has a first surface and a second surface opposite to each other. The first surface of the first substrate faces the body. The heating member extends on the first surface of the first substrate. The high-voltage-side lead portion extends on the second surface of the first substrate.

Gas sensor

A gas sensing element having a sample gas chamber into which a sample gas is introduced, and a reference gas chamber into which a reference gas is introduced. A sensor cell detects a specific gas concentration in the sample gas chamber. An oxygen pump cell pump cell pumps oxygen gas from or to the sample gas chamber. An introducing passage includes at least one pinhole provided on a surface of the oxygen pump cell for introducing the measuring gas into the sample gas chamber. The surface of the oxygen pump cell faces an outside of the gas sensing element. And, a porous diffusion resistive layer is provided on the surface of the oxygen pump cell so as to cover a portion corresponding to the introducing passage, thus serving to reduce or eliminate the effects of temperature dependency upon gas sensor output for properly sized and machine pinholes.

Gas sensing element and a method for measuring a specific gas concentration

A gas concentration detector comprises a plate sensor element including a sensing action and a signal output section. A flange section is formed between the sensing section and the signal output section so as to protrude in the lateral direction thereof. A cylindrical housing has an inside space for receiving the sensor element. Powder is disposed in the inside space of the cylindrical housing at a predetermined position adjacent to the flange section so that the sensor element is airtightly fixed to the housing by applying a pressing force on the powder. Furthermore, a cross-sectional area of the signal output section is larger than a cross-sectional area of the sensing section.

Gas concentration detector

An air-fuel ratio sensing element comprises a pump cell having at least one pair of pump electrodes thereon, a sensor cell having at least one pair of sensor electrodes thereon, and a gas chamber having two surfaces defined by the pump cell and the sensor cell. Two to five gas holes, each having approximately the same diameter and communicating with the gas chamber, are provided for introducing sensed gas into the gas chamber. The gas holes form their projection images on the surface of the sensor cell which has a sensor electrode thereon and faces the gas chamber. The sensor electrode is shaped such that it is dividable into a plurality of similar subsections defined by virtual lines connecting the geometric centroid of the sensor electrode and the center of the projection image of each gas hole.

Air-fuel ratio sensing element

An air-fuel ratio sensor comprises a platelike oxygen sensing section made of a solid electrolyte and a heater sheet heating the oxygen sensing section. The oxygen sensing section and the heater sheet are stacked via spacers to constitute a multilayer construction. The heater sheet comprises a first platelike insulating sheet chiefly containing at least one component selected from the group consisting of .alpha.-alumina, steatite and mullite, a filmy resistance element disposed on the first insulating sheet and having a resistance-temperature coefficient within a range of 0.5.times.10.sup.3 to 2.0.times.10.sup.3 ppm/.degree.C., and a second platelike insulating sheet covering the resistance element and chiefly containing at least one component selected from the group consisting of .alpha.-alumina, steatite and mullite.

Growing community of inventors

Chiryu, Japan

Shinichiro Imamura