Reductant dosing system

Abstract

A reductant dosing system for an engine is disclosed. The disclosed reductant dosing system includes a reservoir of reductant fluid that is connected to an inlet of a reductant pump. The pump has an outlet that is fluidly connected to the reservoir, an inlet of a pressure regulator and an inlet of an injector. The pressure regulator includes a reductant pressure control valve that fluidly connects the outlet of the reductant pump to the reservoir when the reductant pressure control valve is in an open position. A compressed gas source is fluidly connected to an air supply control valve that fluidly connects the compressed gas source to the reservoir when the air supply control valve is in an open position. The air supply control valve also has a closed position and is shifted between the open and closed positions by a controller.

Description

BACKGROUND[0001]1. Technical Field[0002]This disclosure is directed to exhaust systems for internal combustion engines that include reductant dosing systems. More specifically, the disclosed reductant dosing systems are less prone to pressure pulsations and can operate at high altitudes and at high temperatures without significant vaporization or boiling of the reductant fluid.[0003]2. Description of the Related Art[0004]Internal combustion engines include diesel, gasoline, gaseous fuel-powered and other engines known in the art. These engines produce a complex mixture of emissions. These emissions include gaseous compounds such as oxides of nitrogen, NO and NO2, or collectively, NOx. In atmospheric chemistry, the term NOx means the total concentration of NO and NO2. Due to increased environmental awareness, the amount of NOx emitted to the atmosphere by an engine is regulated depending on the type, size and / or class of the engine.[0005]In order to comply with the regulation of NOx ...

AI Technical Summary

Benefits of technology

The system effectively prevents boiling and vaporization of the reductant fluid, allowing for precise dosing and operation in high-altitude and high-temperature conditions, suitable for larger diesel power systems.

Problems solved by technology

These engines produce a complex mixture of emissions.

However, such a reductant dosing system can produce pressure pulsations, which cannot be accurately controlled by modifying the pump speed.

Further, the pressure drop in the pump suction line in combination with operation at high altitudes (low ambient pressure) and / or high temperatures can result in significant vaporization or boiling of the DEF.

Vaporization or boiling of the DEF may result in a mixture of vapor and fluid entering the pump, which prevents accurate dosing of the DEF into the exhaust stream.

While, such a system without a pump is applicable to passenger vehicles with diesel engines, reliance upon a pressurized DEF tank alone, without a pump, may not be suitable for larger diesel power systems, such as those for trucks, generators, construction equipment, mining equipment, etc.

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