A method for an SCR system comprising a dosing unit (250) for dosing reducing agent into an engine exhaust duct (290) upstream of a SCR catalytic converter (270) for reducing the NOx level in an exhaust flow from the engine. The SCR system comprises a pressurizing device (230) for feeding reducing agent from a container (205) to the dosing unit (250) arranged so as to dose reducing agent to the exhaust duct (290) under pressure. The method includes the step of: reducing, during periods of non-continuous dosing of reducing agent during continued maintained operation of the pressurizing device (230), the pressure (s301; s320) of the reducing agent at the dosing unit (250) compared to the pressure during continuous dosing. Also a computer program product containing program code (P) for a computer (200; 210) for implementing a method according to the invention. The invention also concerns an SCR system and a motor vehicle that is equipped with that system.

An exemplary vehicle exhaust system includes, among other things, a housing defining a fluid chamber and at least one pressure sensor positioned within the fluid chamber. The housing has a fluid inlet configured to receive fluid from a fluid supply and a fluid outlet. A heater heats fluid supplied from the fluid supply such that heated fluid can be injected into a vehicle exhaust component via the fluid outlet. A controller is configured to receive pressure data from the at least one pressure sensor and to determine optimal timing for dosing of the vehicle exhaust component based on the pressure data.

An exhaust postprocessing component comprises an exhaust pipe, a first support installed on the exhaust pipe, a common rail installed on the first support, an inlet pipeline and an outlet pipeline that are connected to the common rail, a sensor, and a bundle that is connected to the sensor. The common rail comprises a shell and a pressure detection apparatus and a pressure adjustment apparatus that are installed on the shell. The shell comprises an inlet passage and an outlet passage. The pressure detection apparatus is connected to the inlet passage. The pressure adjustment apparatus is connected between the inlet passage and the outlet passage, so as to connect or disconnect the inlet passage and the outlet passage. The engine exhaust postprocessing component further comprises a second support. The bundle, the inlet pipeline, and the outlet pipeline are all gathered at the second support. In this way, the exhaust postprocessing component is easy to be installed with another component.

A reduction-causing agent supply device includes a tank to store a reduction-causing agent, a pumping unit to pump the reduction-causing agent, a reduction-causing agent supply passage to supply the reduction-causing agent, an injection nozzle to inject the reduction-causing agent into an exhaust pipe, a drawing-back unit to draw the reduction-causing agent toward the tank, and a controller. After stop of an engine, the controller performs: reduction-causing agent drawing-back process of drawing the reduction-causing agent toward the tank and introducing exhaust gas from the injection nozzle into the reduction-causing agent supply passage; and gas discharge process of supplying the reduction-causing agent to compress the exhaust gas inside the reduction-causing agent supply passage, discharging the compressed exhaust gas from the injection nozzle, and closing a valve of the injection nozzle before the reduction-causing agent reaches the injection nozzle.

The present invention discloses methods and devices for controlling a heated mixer, situated downstream of a Urea-Water Solution (UWS) injector, to reduce NOx emission in an exhaust system from combustion engines, wherein the exhaust system has a Selective Catalytic Reduction (SCR) catalyst situated downstream of the UWS injector and the heated mixer, Methods include: determining a NOx reduction efficiency of the SCR catalyst; evaluating at least one reductant Uniformity Index (UI) based on operating parameters of the exhaust system and a mixer power calculation map; and modifying a mixer temperature of the heated mixer by regulating power to the heated mixer based on at least one reductant UI in order to improve at least one reductant UI and/or improve the NOx reduction efficiency. Alternatively, the method further includes: detecting at least one potential improvement of at least one UI and/or the NOx reduction efficiency based on an increased ammonia mass.

The present application provides a reductant dosing system for an SCR catalyst comprising an injector, a storage tank and a reductant pump arranged in a first fluid line between the storage tank and the injector for pumping reductant from the storage tank to the injector. The reductant dosing system comprises pressurizing means for pressurizing the storage tank.

An SCR device for a motor vehicle, comprising a tank for storing reducing liquid, an injection device for injection of the reducing liquid into an exhaust gas system of a motor vehicle, a liquid conduit for delivering reducing liquid from the tank to the injection device, a feed pump for conveying reducing liquid in the conduit, and a valve arrangement in the conduit, the valve arrangement designed to interrupt an injection flow in the conduit when the tank-side pressure is greater, than the injection device-side pressure in the conduit by less than an injection threshold value, and to allow the injection flow to pass when the tank-side pressure is greater by at least the injection threshold, the valve arrangement designed to interrupt a return flow in the conduit from the injection device to the tank when the injection device-side pressure is greater than the tank-side pressure by less than a return threshold value, and to allow the return flow to pass through when the injection device-side pressure is greater than the tank-side pressure in the conduit, by at least the return threshold value, the injection threshold value being greater than the return threshold value.

A controller including a self-tuning circuit for controlling a pressure system to output an input pressure corresponding to an input pressure value using an adaptive fuzzy control system and updating dosing command values of a dosing command table for controlling a dosing unit of an aftertreatment system. The self-tuning circuit is configured to determine an input pressure value and generate a pressure control signal using the adaptive fuzzy control system based on the input pressure value, a detected input pressure, and an error amount. The self-tuning circuit is further configured to regulate the input pressure of reductant to the dosing unit from a reductant tank using a pressure control signal for a pressure control device. The self-tuning circuit is further configured to update a dosing command value of a dosing command table of the controller in conjunction with regulating the input pressure of reductant.

When an integrated value of a determination value correlated with a command value for an amount of supply of a reducing agent at the time of the command value being larger than a command supply amount threshold value reaches an integration threshold value, a determination is made that a diagnosis condition is satisfied, and an abnormality in the supply of the reducing agent is diagnosed based on an integrated value of the command value for the amount of supply of the reducing agent and an integrated value of an estimated value of the amount of supply of the reducing agent, whereas in cases where a period of time in which the diagnosis condition is not satisfied is longer than a time period threshold value, an interval of supply of the reducing agent is extended.

A method for operating a dosing device for metering an additive to an exhaust-gas treatment device includes determining a dosing amount of additive required by the exhaust-gas treatment device in step a). Subsequently, in step b), an operating mode for the dosing device is determined by carrying out at least steps b.1) and b.2). In step b.1), at least one characteristic operating value of at least one component of the dosing device is provided being definitive of a degree of aging of the dosing device. In step b.2), an operating mode for the dosing device is set in dependence on the characteristic operating value from step b.1). In step c), the dosing device is operated with the set operating mode so that the dosing amount required in step a) is supplied to the exhaust-gas treatment device. A motor vehicle having a dosing device is also provided.