Scania Cv Ab

Christer Lundberg

Mikael Lundström

Håkan Sarby

Kurt Källkvist

Johan Lundström

Tobias Brännvall

David Tempelmann

A control device and a method for deriving an engine-out NOx concentration in an exhaust system comprising a SCR catalyst, a dosing device for dosing a reductant, a first NOx sensor arranged downstream of the dosing device and a second NOx sensor arranged downstream the SCR catalyst. The method comprises deriving engine-out NOx concentration based on a first concentration reading obtained from the first NOx sensor and a second concentration reading obtained from the second NOx sensor, said first concentration reading being obtained while the dosing device is in operation. An exhaust system as well as a vehicle comprising the control device are also provided.

Control device and method for deriving engine-out NOx concentration

The present disclosure relates to an exhaust gas aftertreatment system and method for controlling same. The exhaust gas aftertreatment system comprises: a reductant dosing device; a selective catalytic reduction device arranged downstream of the reductant dosing device; an ammonia slip catalyst arranged downstream of the SCR device; a feedback NOx sensor arranged downstream of the SCR device and upstream of the ammonia slip catalyst; a tailpipe NOx sensor arranged downstream of the ammonia slip catalyst; and a control device configured for: providing an initial dosing of reductant from the reductant dosing device; obtaining a feedback signal from the feedback NOx sensor and a tailpipe NOx signal from the tailpipe NOx sensor; and adjusting the dosing of reductant until the feedback signal exceeds the tailpipe NOx signal by a value within a predetermined positive interval.

Exhaust gas aftertreatment system

Disclosed is a method for use in a process of selective catalytic reduction (SCR) after-treatment of an exhaust gas of an exhaust gas stream, where the process comprises the reduction of nitrogen oxides of the exhaust gas stream through the use of a reducing agent derived from an additive. The disclosed method comprises: defining an integrand to be the difference between the rate of injection of the additive and the rate of evaporation of the additive to the reducing agent multiplied by a coefficient (s), wherein the value of the coefficient (s) is between zero and one; producing an integral controller output proportional to the integral of the integrand with time; requesting a countermeasure based on the integral controller output to counteract solid deposits derived from the additive.

Method and a control arrangement for a process of selective catalytic reduction after-treatment of an exhaust gas

Disclosed is a method for diagnosing functionality of dosing units of a fluid dosing system comprising at least two dosing units, a tank unit for holding a fluid, and a pump unit for pressurizing the fluid for the dosing units. The method comprises determining a first hydraulic stiffness value on the basis of first pressure variations and determining a second hydraulic stiffness value on the basis of said second pressure variations. The first hydraulic stiffness value and second hydraulic stiffness value are compared. In a case where the first hydraulic stiffness value and second hydraulic stiffness value differ to a certain extent, concluding that malfunction of at least one of said dosing units is at hand, and in a case where the first hydraulic stiffness value and the second hydraulic stiffness value do not differ to said certain extent, concluding that the first and second dosing units function as intended.

System and a method for diagnosing functionality of dosing units of a fluid dosing system

Disclosed is a method for control of dosage of a reducing agent into an exhaust stream, which includes: determining at least one sensor signal Sfrom at least one nitrogen oxides NOsensor arranged downstream of at least one of the one or more reduction catalysts as at least one sensor correction value S, respectively, if: 1) the engine rotates without fuel supply; 2) an exhaust mass flow M'is greater than an exhaust mass flow threshold M&#x2032;; M&#x2032;&#x3e;M&#x2032;; and 3) the sensor signal Shas had a value smaller than a sensor signal threshold S; S&#x3c;S; during at least a predetermined time period T; determining at least one adjusted sensor signal Sbased on the at least one sensor signal Sand the at least one sensor correction value S, respectively; and controlling the dosage of the reducing agent based on the at least one adjusted sensor signal S.

Method and control system for control of dosage of a reducing agent

The present invention relates to a method for determining when to correct supply of additive to an exhaust gas stream resulting from combustion in at least one combustion chamber, wherein the additive is arranged for reduction of at least one substance resulting from said combustion by supplying the additive to an exhaust gas stream resulting from said combustion. The quantity of additive being supplied is subjectable to correction, and a sensor is subjected to the exhaust gas stream and arranged to measure occurrence of said at least one substance. The method comprises: by means of sensor signals from said sensor, determining a level of occurrence of said first substance in said exhaust gas stream, and determining when to correct said supply of additive on the basis of said occurrence of said first substance in said exhaust gas stream.

Method and system for use when correcting supply of an additive to an exhaust gas stream

The present invention concerns a method in connection with the supplying of a first additive for treating an exhaust gas stream resulting from combustion in a combustion engine, wherein said first additive is supplied to said exhaust gas stream, and wherein said first additive is utilized for the reduction of at least a first substance (such as NO) present in said exhaust gas stream, wherein the method comprises: estimation of a reduction of said first substance based on a first measurement of a presence of said first substance in said exhaust gas stream downstream of said supply of said first additive, and a second measurement of a presence of said first substance in said exhaust gas stream upstream of said supply of additive, comparison of said estimated reduction to a first reduction, and correction of the estimation of said second measurement of said first substance based on said comparison.

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Rönninge, Sweden

Christer Lundberg