Nissan Diesel Motor Co., Ltd.

Ud Trucks Corporation

Ngk Spark Plug Company, Limited

Bosch Corporation

Toshikazu Katou

Mitsuhiro Nishina

Hideki Matsunaga

Hiroyuki Kurita

Masayuki Motomura

Katsunori Yazawa

Shinji Kumazawa

Toshiki Sawaki

Eitarou Asakawa

On the basis of a correlation between exhaust gas temperature detected by an exhaust gas temperature sensor and exhaust gas temperature estimated according to an engine operating condition, it is detected whether or not abnormality occurs in the exhaust gas temperature sensor. Namely, when a change characteristic of the detected exhaust gas temperature follows a change characteristic of the estimated exhaust gas temperature, it is determined that the exhaust gas temperature sensor is normal. On the other hand, when the change characteristic of the detected exhaust gas temperature does not follow that of the estimated exhaust gas temperature, it is determined that the exhaust gas temperature sensor is abnormal.

Apparatus for and method of detecting abnormality in exhaust gas temperature sensor

An exhaust emission purifying apparatus for an engine, which is provided with: an electric pump sucking and supplying a liquid reducing agent by pumping out of a reducing agent tank; a flow control valve controlling flow rate of the liquid reducing agent; and an injection nozzle injection-supplying the liquid reducing agent with the controlled flow rate, to an exhaust emission upstream of NOx reduction catalytic converter. At the engine starting, a highly pressurized air is urged to reversely flow to a reducing agent supply system upstream of the flow control valve. Then it is determined whether or not the reducing agent supply system brings about clogging based on a pressure change produced by the reverse flow. When a number of frequency at which it is consecutively determined as occurrence of clogging reaches a predetermined number or more, it is determined that the clogging is serious, which is unable to be readily mended.

Exhaust emission purifying apparatus for engine

In an exhaust emission purifying apparatus for reductively purifying NOx in the exhaust emission by using a liquid reducing agent or its precursor, to be referred to as 'liquid reducing agent' herein, a dosing flow rate of the liquid reducing agent according to engine operating conditions is computed, and the dosing of the liquid reducing agent is controlled based on the computed dosing flow rate, and also, it is judged whether or not a supply system of the liquid reducing agent is failed, based on a ratio between an integrated amount obtained by sequentially integrating the dosing flow rate and a consumed amount of the liquid reducing agent.

A technology for purifying an exhaust emission from an engine is provided, in which a misjudgment caused by a time lag between the abnormality detection and an abnormality judgment is avoided, in the case where a plurality of abnormalities is judged on the aqueous solution of a reducing agent or the like. After a first abnormality judgment (Femp=1: the time t) is made, when a second abnormality is detected as a result that the concentration Dn as a state parameter is directly shifted from a first region A to a second region C (the time t), the first abnormality judgment is maintained for a predetermined period of time PRD after the second abnormality detection.

An exhaust emission purifying apparatus for an engine in which it is determined that a reducing agent supply system is clogged, which is arranged on the downstream of a pump carrying out suction and pumping of a liquid reducing agent out of a reducing agent tank, when a reduction in a pressure of the liquid reducing agent remaining in the downstream of the pump and also in the upstream of a flow control valve by an amount equal to or more than a first predetermined pressure does not occur until a cumulative injection amount obtained by sequentially integrating an injection amount of the liquid reducing agent computed in real time based on engine operating conditions reaches a predetermined amount after the pump has been temporarily stopped.

A concentration sensor for detecting a concentration of a liquid reducing agent through heat transfer characteristics between separate two points is provided in a storage tank for storing a liquid supplied to an NOreduction catalyst. When the concentration read from the concentration sensor is 0% or less, the liquid is discriminated to be water, that is, it is utilized that when water is converted to the concentration of a liquid reducing agent, it is 0%, and it is also 0% even when the concentration is reduced by convection. When the concentration is greater than a predetermined value, it is discriminated that no liquid is present, since it is considered that the output of the sensor is abnormal because of the absence of a liquid in the tank. On the other hand, when the concentration is greater than 0% and less than a predetermined value, the liquid is discriminated to be the liquid reducing agent, provided that the concentration value may include an error.

Liquid discriminating apparatus and liquid discriminating method

An engine C/Udetects an abnormality which has occurred in an engine, and outputs a signal that indicates the occurrence of this abnormality to an SCR-C/U. The SCR-C/Uincreases and decreases the urea water injection quantity corresponding to the abnormality which has occurred. On the other hand, the SCR-CUdetects an abnormality that has occurred in the SCR device, and outputs a signal that indicates the occurrence of this abnormality to an engine C/U. The engine C/Ucontrols an engine part such as an EGR valve, to reduce the NOx emission amount.

Engine exhaust emission control device and exhaust emission control method

Each of a first and a second number of times is counted, in which the first number of times indicates a condition where a concentration of a liquid reducing agent indirectly measured based on a characteristic of heat transmission between two separated points is successively determined to be equal to or higher than an upper limit threshold for no agent, and the second number of times indicates a condition the concentration is successively determined to be equal to or lower than a lower limit threshold for different agent. When the former becomes equal to or larger than the predetermined value, determination is made that no liquid reducing agent remains. When, the latter becomes equal to or larger than the predetermined value, determination is made that the liquid reducing agent is a solution of a different kind. When the former and the latter is less than the predetermined value, determination is made that correct liquid reducing agent remains.

Condition discriminating apparatus for liquid reducing agent

In a storage tank for storing a liquid reducing agent, a sensor for outputting a signal related to a concentration and a remaining amount of the liquid reducing agent based on a heat transfer characteristic between two points at a distance from each other is disposed. In a control unit which contains a built-in computer, it is determined that a vehicle state is stable when a stop time for which a vehicle is continuously in a stationary state reaches a predetermined determination time, the concentration of the liquid reducing agent is calculated based on the signal from the sensor when the vehicle state is stable, and the remaining amount of the liquid reducing agent is determined based on the signal from the sensor irrespective of the vehicle state, in response to a measurement trigger output every predetermined time after a start of an engine.

Apparatus for detecting concentration and remaining amount of liquid reducing agent

In an SCR apparatus mounted on a vehicle, the concentration of a reducing agent or a precursor thereof contained in an aqueous solution of the reducing agent or the precursor is accurately detected. In sensing the concentration, whether or not the urea water stored in a storage tank is in a stationary state is determined. Only it is in a stationary state, the concentration is detected. The determination of whether or not it is in a stationary state or not is preferably determined by determining whether the vehicle is stopped (S) and that the period of time TIM that has elapsed after the stoppage has reached a predetermined stationary time TIM(S). The deceleration DCL of the vehicle before stoppage thereof is detected, and the stationary time TIMis altered in accordance with the deceleration DCL (S).

Growing community of inventors

Ageo, Japan

Toshikazu Katou