Method and apparatus for controlling a heater of a delivery and distribution system

Abstract

The invention relates to a method and device for a conveying and distribution system for thawing a reducing agent for selective catalytic reduction of exhaust gas of an internal combustion engine. Here, a maximum available electrical power is fully or in part distributed to the designated heaters during a warm-up period according to a time-variable priority specification.Pulse-width modulation of the heaters is carried out such that output pulses do not overlap or overlap only for the smallest possible time. A heating strategy for the conveying and distribution system is determined by energy balance for the reducing agent. The method and the device lead to increased thawing amount during the thawing time and lead to an optimized thawing time of the conveying and metering system in short breaks, so that the work ready state of the conveying and distribution system can be achieved quickly and sustainably.

Description

technical field [0001] The invention relates to a method for controlling at least two heaters of a system for the delivery and distribution of reducing agents for the selective catalytic reduction of exhaust gases of internal combustion engines with at least one heater for controlling Control unit for at least two heaters. [0002] The invention also relates to a control unit for controlling at least two heaters of a delivery and distribution system of a reducing agent for the selective catalytic reduction of exhaust gases of an internal combustion engine. Background technique [0003] In order to reduce pollutant emissions, it is known to dose a liquid, in particular in the form of a reducing agent, into the exhaust gas duct of an internal combustion engine. For example, nitrogen oxide emissions from internal combustion engines can be reduced by means of selective catalytic reduction (SCR) by means of exhaust gas aftertreatment. In this case, a defined quantity of selecti...

AI Technical Summary

Problems solved by technology

[0006] If ohmic heaters are increasingly used in the future instead of previously used heaters with PTC elements, then the existing control of the heaters will have another disadvantage, because the current of the ohmic heaters is constant at a constant voltage. is nearly constant over the entire operating range, so that the maximum allowable electrical power is exceeded when powering all heaters at full capacity

Furthermore, circuit boards, plugs and cable harnesses have to be designed correspondingly tediously according to the maximum current

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