A reductant insertion assembly for inserting a reductant into an aftertreatment system comprises a pump assembly including a pump. A first metering assembly is fluidly coupled to the pump. A second metering assembly is fluidly coupled to first metering assembly in series with the pump. The pump is configured to pump the reductant to the first metering assembly, and to the second metering assembly via the first metering assembly, such that a first reductant pressure in the first metering assembly is equal to a second reductant pressure in the second metering assembly.

A method for adjusting a pressure sensor of an SCR system between a delivery pump and a dosing valve, with which the delivery pump is switched off during a switch-off phase of the SCR system and a pressure (p.sub.m) measured by the pressure sensor is detected at least during a section of the switch-off phase in which the delivery pump is switched off, and the adjustment of the pressure sensor is carried out by using the measured pressure (p.sub.m) as the reference pressure for the pressure sensor.

A reduction in measurement accuracy of a concentration sensor is minimized. An exhaust gas purifying device of a work machine includes a reduction catalyst that is placed in an exhaust flow passage of an exhaust gas of an engine and uses a reducing agent to reduce and purify nitrogen oxides in the exhaust gas, and a reducing agent injector to inject the reducing agent into the exhaust flow passage. The exhaust gas purifying device of a work machine includes: a storage unit that stores the reducing agent; a concentration sensor that has a sensing part placed within the storage unit to detect a concentration of the reducing agent; an air-bubble removal device that injects the reducing agent toward the sensing part; and a reducing agent pump that supplies the reducing agent in the storage unit to the air-bubble removal device.

A reductant delivery system for an internal combustion engine is arranged to inject a reductant into the exhaust aftertreatment system upstream of a catalytic device. A method for controlling the reductant delivery system includes operating the fluidic pump at a preset state, operating the injector at a zero-flow state, and monitoring, via a pressure sensor, a pressure in the reductant delivery system upstream of the injector to determine a zero-flow pressure. The injector is activated under a preset condition and an actual pressure drop upstream of the injector is monitored. A pressure drop deviation is determined based upon the actual pressure drop upstream of the injector and an expected pressure drop upstream of the injector. An adjustment to the activation of the injector is determined based upon the pressure drop deviation, and the injector is controlled based upon the adjustment.

Disclosed is a method for adapting control of a reducing agent dosing unit in a reducing agent provision system for emission control of a combustion engine. Characteristics relating to pressure variations associated with a dosing cycle are used for determining a first time period and a second time period. The time periods relate to a delay between activation of dosing and de-activation of dosing, respectively. The first time period and second time period are used for adapting operation of said reducing agent dosing unit.

A reducing agent dosing valve (24) on an exhaust system (12) of an internal combustion engine (10), having a pump (32) which generates an injection pressure (p_24), and having a control unit (14) which actuates the reducing agent dosing valve (24) with actuation signals is presented, wherein the actuation signals are formed in a manner dependent on a reducing agent pressure (p_36) prevailing at the pump side. The method is distinguished by the fact that the actuation signals are formed additionally in a manner dependent on at least one estimated value for an influence of a drop in the injection pressure (p_24), which occurs upon the opening of the reducing agent dosing valve (24), on the injected reducing agent quantity.

A method and a device for determining the injection quantity or the injection rate of a fluid which is transported to an injector through a hydraulic line and is injected into a reaction space by the injector. The fluid pressure in the hydraulic line is measured by a pressure sensor, the fluid pressure at the injector is determined using the pressure measured by the pressure sensor and a stored transmission function of the hydraulic line, and the injection quantity or the injection rate of the fluid injected by the injector is determined using the fluid pressure determined at the injector.

A method for detecting a dosing error of a reduction agent in a dosing module of an SCR catalytic converter system. The SCR catalytic converter system comprises the dosing module, which has a dosing valve and a flow valve as well as a delivery module with delivery pump. The SCR catalytic converter system, furthermore, has a return, in which a further flow valve is arranged. Said flow valve changes an effective cross-sectional area of the return. The method herein comprises the following steps: at the beginning, the dosing valve is closed (200). At a first pressure value (p.sub.1) in the system the delivery pump is switched off (201) and a measurement (202) of a first pressure rate (.sub.RL.sup.dynamic) of the flow valve of the return subsequently takes place. Additional operation of the pump and the dosing valve occurs and a ratio of pressure rates is determined.

A diesel exhaust fluid delivery system and a dual-variable control strategy for adjusting the delivery pressure and the mass flow rate of the fluid passing through the system. The method for operating the system using two operating modes: low flow rate and high flow rate. While operating in the low flow rate operating mode, the speed of a DEF pump remains constant and DEF delivery to the exhaust system is adjusted by controlling a backflow valve. While operating in the high flow rate operating mode, the backflow valve is closed and the speed of the pump is adjusted to regulate DEF delivery to the exhaust system.

The invention relates to a method for detecting a blocked pressure line in an SCR system of an internal combustion engine. The SCR system comprises a feed pump, a dosing module and a pressure sensor. The method comprises the following steps: a reference signal of a pressure (p) in the pressure line is measured over a measuring time (t.sub.M) if a reducing agent solution is not dosed by the dosing module, and a signal energy of the reference signal is then calculated. A pressure signal is measured over the measuring time (t.sub.M) during the dosing of a dosing mass of the reducing agent solution by the dosing module, and a signal energy of the pressure signal is then calculated. Finally, a ratio of the signal energies of the pressure signal to the signal energy of the reference signal is calculated. The blocked pressure line is detected if the ratio falls short of a first pre-definable threshold value.