Denso Corporation

Cataler Corporation

Shingo Nakata

Tomoo Kawase

Yuichi Takemura

Mikiyasu Matsuoka

Takao Mishima

Hiroaki Fujii

Yasuo Mukai

Kosuke Nakano

Kenichi Taki

Akimasa Hirai

Tomoaki Nakano

Hiroshi Katsurahara

Mikio Ishihara

Yuji Yamada

Yuji Yabuzaki

Masakazu Murata

Yasuhiro Kawakatsu

Hironori Niwa

Hiroki Nogami

Akira Miyashita

Shusaku Yamamura

Syusaku Yamamura

Kota Yamakoshi

Yuuji Yamada

Yoshiyasu Andoh

Kouta Yamakoshi

A particulate matter detection system detects a particulate matter in exhaust gas. The particulate matter detection system includes: a particulate matter detection sensor in which at least one detection portion is provided, the at least one detection portion including at least one pair of multiple electrodes and a deposition surface which is interposed between the pair of electrodes and which the particulate matter is deposited on; a capacitor connected to the at least one detection portion in series; a power supply configured to apply a direct voltage to a series body including the at least one detection portion and the capacitor; and a voltage measurement portion configured to measure a voltage of the capacitor.

Particulate matter detection system

An exhaust gas filter purifies exhaust gas containing particulate matter emitted from an engine. The filter has cell walls and cells surrounded by the cell walls. Through pores formed in the cell walls, adjacent cells are communicated. The cells have open cells opening along an axial direction of the filter, and plugged cells. An upstream end part of the plugged cell is plugged by a plug member. On a cross section perpendicular to the axial direction, a flow-passage sectional area of the plugged cells is larger than a flow-passage sectional area of the open cells. A total length of the filter is not less than a first standard value and is not more than a critical length Lm determined by respective predetermined equations.

Exhaust gas filter

A particulate detection device has an insulation part, electrodes, an adhesion amount calculation section, a heater and a controller. The insulation part is located in an exhaust passage of an internal combustion engine and has an adhesion surface to which exhaust particulates emitted from the internal combustion engine adhere. The adhesion amount calculation section calculates an adhesion amount of the exhaust particulates adhered to the insulation part based on an electrical resistance between two of the electrodes. The controller, in a normal control, controls an air/fuel ratio in the internal combustion engine to be a theoretical air/fuel ratio. The controller, in a regeneration control, controls the heater to increase a temperature of the insulation part and removes the exhaust particulates from the insulation part by burning the exhaust particulates, and controls the air/fuel ratio to be lean as compared to the theoretical air/fuel ratio.

Particulate detection device

A catalytic conversion characteristic of a catalyst, which indicates a relationship between an air-to-fuel ratio and a catalytic conversion efficiency of the catalyst, includes a second air-to-fuel ratio point, which is a point of starting an outflow of NOx from the catalyst and is located on a rich side of a first air-to-fuel ratio point that forms an equilibrium point for a rich component and oxygen. A constant current circuit, which induces a flow of an electric current from an exhaust side electrode to an atmosphere side electrode through a solid electrolyte layer in a sensor element, is connected to the sensor element. A microcomputer controls a current value of the electric current, which is induced by the constant current circuit, based on a difference between the first air-to-fuel ratio point and the second air-to-fuel ratio point at the catalyst.

Gas sensor control method

An exhaust gas purification device includes: an actual pressure difference obtainer that acquires an actual pressure difference which is an actual measurement value of a pressure difference of a filter; a flow rate obtainer that acquires a flow rate of exhaust gas flowing into the filter; a calculation pressure difference calculator that calculates a calculation pressure difference which is a calculated value of the pressure difference of the filter in a normal state when the exhaust gas flows into the filter with the flow rate acquired by the flow rate obtainer; and an abnormality determiner that performs an abnormality determination of the filter based on a pressure difference variation ratio which is a ratio between a variation in the actual pressure difference and a variation in the calculation pressure difference in response to a variation in the flow rate of the exhaust gas.

Exhaust gas purification device

An Osensor includes a sensor element using a solid electrolyte layer and a pair of electrodes placed at a position to interpose the solid electrolyte layer, detects an exhaust gas from an internal combustion engine as an object of a detection, and outputs an electromotive force signal depending on an air-fuel ratio of the exhaust gas. The sensor element is connected with a constant current circuit supplying a constant current that is prescribed. A microcomputer calculates an element resistance, determines whether the air-fuel ratio is at least rich, lean, or stoichiometric, on the basis of a comparison between an electromotive force output of the electrogenic cell and a prescribed threshold. Further, the microcomputer controls the constant current supplied by the constant current circuit on the basis of the element resistance.

Gas sensor control device

An Osensor includes a sensor element using a solid electrolyte layer and a pair of electrodes placed at a position to interpose the solid electrolyte layer, detects an exhaust gas from an internal combustion engine as an object of a detection, and outputs an electromotive force signal depending on an air-fuel ratio of the exhaust gas. The sensor element is connected with a constant current circuit supplying a constant current that is prescribed. A microcomputer conducts an abnormality diagnosis of an output response of the sensor element on the basis of a state of variation in an electromotive force output. Further, when the microcomputer conducts the abnormality diagnosis, the microcomputer restricts a supply of the constant current by the constant current circuit before conducting the abnormality diagnosis.

An Osensor includes a sensor element using a solid electrolyte layer and a pair of electrodes placed at a position to interpose the solid electrolyte layer, detects an exhaust gas from an internal combustion engine as an object of a detection, and outputs an electromotive force signal depending on an air-fuel ratio of the exhaust gas. The sensor element is connected with a constant current circuit supplying a constant current that is prescribed. A microcomputer calculates a resistance value (element resistance) of the sensor element, and performs a restriction on the constant current supplied by the constant current circuit on the basis of the element resistance.

An abnormality diagnosis device includes a partially-plugged filter, a pressure difference sensor, a PM sensor, a first estimation portion estimating a diagnosis amount of PM from the partially-plugged filter, according to a running condition of the internal combustion engine, a second estimation portion estimating the diagnosis amount of PM according to an output of the pressure difference sensor, a third estimation portion estimating the diagnosis amount of PM according to an output of the PM sensor, and an abnormality diagnosis portion distinctly determining an abnormality of the internal combustion engine, an abnormality of the partially-plugged filter, and an abnormality of the PM sensor by comparing the diagnosis amount of PM estimated by the first estimation portion, the diagnosis amount of PM estimated by the second estimation portion, and the diagnosis amount of PM estimated by the third estimation portion.

Abnormality diagnosis device

An exhaust purification device purifies an exhaust gas exhausted from an internal combustion engine. The exhaust purification device has a three-way catalytic agent that is located in an exhaust passage of the internal combustion engine and a particulate filter that is located downstream of the three-way catalytic agent in the exhaust passage and that collects an exhaust particulate. The particulate filter is provided with cells that includes sealed-inlet cells of which upstream ends are sealed and through cells through which an upstream side and a downstream side of the particulate filter communicate with each other. The particulate filter is arranged at a location where a temperature of the exhaust gas reaching an upstream end of the particulate filter is higher than or equal to a combustion temperature of the exhaust particulate, when the three-way catalytic agent is in an active state and when the internal combustion engine is operated.

Exhaust purification device

Gas sensor control apparatus

A constant current circuit is controlled to stop a constant current Ics (Ics=0) flowing between sensor electrodes of an oxygen sensor, in a period before the oxygen sensor becomes active, during a fuel cut of an engine, and after the engine stops. When an abnormality (for example, a failure) occurs in the constant current circuit, a sensor output equivalent to an output of the oxygen sensor of when the constant current circuit is controlled to stop the constant current Ics is different from a normal sensor output. An abnormality diagnosis is executed to determine a presence or absence of the abnormality in the constant current circuit depending on whether the output of the oxygen sensor is out of a predetermined normal range, in a period before the oxygen sensor becomes active, during a fuel cut of an engine, and after the engine stops (when the constant current circuit is controlled to stop the constant current Ics).

An Osensor has a sensor element, which includes a solid electrolyte layer and a pair of electrodes, while the solid electrolyte layer is interposed between the electrodes. The Osensor outputs an electromotive force signal in response to an air-to-fuel ratio of exhaust gas of an engine, which serves as a sensing subject. A constant current circuit, which induces a flow of a predetermined constant electric current between the pair of electrodes of a sensor element, and a current sensing arrangement, which senses a current value of an actual electric current that is conducted through the sensor element, are provided. A microcomputer determines whether an abnormality of the constant current circuit is present based on the current value of the electric current, which is sensed with the current sensing arrangement, in a case where the constant current is induced by the constant current circuit.

A deterioration diagnosis device, which performs a deterioration diagnosis of a catalyst, includes an exhaust-gas sensor provided downstream of the catalyst in a flow direction of exhaust gas such that an output value of the exhaust-gas sensor is used at least in the deterioration diagnosis. The deterioration diagnosis device further includes the constant current supply portion which applies a voltage to a sensor element of the exhaust-gas sensor to change an output characteristic of the exhaust-gas sensor, a response-time detection portion which detects a response time required for the output value of the exhaust-gas sensor to change from a rich threshold to a lean threshold, a response-time correction portion which controls the constant current supply portion to change the output characteristic of the exhaust-gas sensor so as to shorten the response time when the response time is longer than a predetermined reference time.

Deterioration diagnosis device for catalyst

An emission control system for an engine includes a catalyst and an exhaust-gas sensor provided downstream of the catalyst in a flow direction of exhaust gas. The exhaust-gas sensor includes a sensor element that includes a pair of electrodes and a solid electrolyte body located between the electrodes. The emission control system further includes a constant current supply portion that changes an output characteristic of the exhaust-gas sensor by applying a constant current between the electrodes, a rich direction control portion that performs a rich direction control after a fuelling-stop control, and a characteristic control portion that performs a rich responsiveness control during the rich direction control. In the rich direction control, an air-fuel ratio of the exhaust gas is made to be richer. In the rich responsiveness control, the constant current supply portion increases a detection responsiveness of the exhaust-gas sensor with respect to rich gas.

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Kariya, Japan

Shingo Nakata