Description:Complete Specification

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to a dosing module for a reducing agent, and more specifically to the dosing module for withdrawing reducing agent from the dosing module to a high pressure pump.

Background of the invention
[0002] US 2020347765 AA describes a reductant dosing system for an SCR catalyst. 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.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a drawing depicting the dosing module that includes a uni-directional valve secured thereto in one embodiment of the invention.

Detailed description of the embodiments
[0004] Figure 1 illustrates a dosing module 100 in one embodiment of the invention. The dosing module 100 comprises a barrel 110, and an injector needle 120 positioned within a needle chamber 130 defined within the barrel 110 and adapted to reciprocate within the barrel 110 to inject reducing agent into an exhaust gas flow path. A uni-directional valve 140 extends through the barrel 110, a first end of the uni-directional valve 140 in flow communication with air at ambient temperature. An opposite second end of the uni-directional valve 140 is in flow communication with the needle chamber 130, the uni-directional valve 140 adapted to channel air at ambient temperature to the needle chamber 130 to increase pressure of reducing agent in the needle chamber 130 to atmospheric pressure.
[0005] Figure 1 illustrates a dosing module 100 in one embodiment of the invention. The dosing module comprises a barrel 110, and an injector needle 120 positioned within a needle chamber 130 that is defined within the barrel 110. The injector needle 120 is adapted to reciprocate within the barrel 110 to inject a reducing agent into an exhaust gas flow path. More specifically, when the injector needle 120 translates towards the outlet of the dosing module 100, reducing agent is injected from the outlet of the dosing module 100 to an exhaust gas flow path for reducing the exhaust gas that flows from an engine.

[0006] In an exemplary embodiment, the uni-directional valve 140 extends through the barrel 110 of the dosing module 100. More specifically, a first end of the uni-directional valve 140 is in flow communication with air at ambient temperature and receives air at ambient temperature therethrough. An opposite second end of the uni-directional valve 140 extends through the barrel 110 and is in flow communication with the needle chamber 130. The uni-directional valve 140 is adapted to channel air at ambient temperature to the needle chamber 130 to increase pressure of air in the needle chamber 130 to atmospheric pressure. More specifically, when dosing of reducing agent is complete from the dosing module 100, the high pressure pump draws the reducing agent from the dosing module 100 and returns surplus reducing agent to the pump module of the high pressure pump. The low negative suction pressure created in the dosing module 100 makes it harder for the high pressure pump to draw the reducing agent and deliver reducing agent to the pump module. Therefore, the pressure of reducing agent within the dosing module 100 is required to be increased to the atmospheric pressure so that the high pressure pump can draw the reducing agent from the dosing module 100 and deliver the reducing agent to the pump module.

[0007] In an exemplary embodiment, an electronic control unit 150 is in electronic communication with the uni-directional valve 140 and adapted to control the uni-directional valve 140 to an open position. More specifically, once the dosing of reducing agent into the exhaust gas flow path is complete, the high pressure pump draws the reducing agent from the dosing module 100 and delivers it to the pump module. When the pressure of the reducing agent in the dosing module 100 decreases below a threshold limit that is pre-determined by a user, the electronic control unit 150 opens the uni-directional valve 140 to the open position. Therein, air at ambient temperature is allowed to flow into the dosing module 100, thereby increasing the pressure of the reducing agent in the dosing module 100 to a pressure that is equal to the ambient pressure of air. More specifically, the electronic control unit 150 is adapted to control the uni-directional valve 140 to the open position when a pressure of air in the needle chamber 130 defined within the barrel 110 decreases below the user defined pre-determined threshold pressure to facilitate channeling air at ambient temperature within the needle chamber 130 via the uni-directional valve 140. Once the pressure of the reducing agent in the needle chamber 130 increases to the atmospheric pressure, the high pressure pump draws the remaining reducing agent back into the pump module and is consequently disconnected. In the exemplary embodiment, the uni-directional valve 140 prevents a flow of reducing agent from the needle chamber 130 to the air at ambient temperature.

[0008] A working of the uni-directional valve 140 for the dosing module 100 for discharging reducing agent from the dosing module 100 is described as an example. At the end of the dosing cycle of the dosing module 100, the residual dosing agent is required to be drawn back into the pump module of the high pressure pump. Therein, the pump module is activated while the injector of the dosing module 100 closes the outlet port that is in flow communication with the exhaust gas flow path. Therefore, exhaust gas at high temperature is prevented from flowing into the dosing module 100. Once the reducing agent from the dosing module 100 is drawn into the pump module and the pressure of the dosing agent in the pump module decreases to a pressure that is below the threshold pressure that is pre-determined by the user, the electronic control unit 150 activates the uni-directional valve 140 to an open position. Air at ambient temperature flows through the uni-directional valve 140 into the dosing module 100 and decreases the pressure of air in the dosing module 100 to the atmospheric pressure. Therein, the pump module draws the residual reducing agent from the dosing module 100 and is disengaged after all the reducing agent is drawn into the pump module. Therefore, hot exhaust gas is not required to be drawn into the dosing module 100 to increase the pressure of the reducing agent in the dosing module 100.

[0009] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.

, Claims:We Claim

1. A dosing module (100), said dosing module (100) comprising:
a barrel (110);
an injector needle (120) positioned within a needle chamber (130) defined within said barrel (110) and adapted to reciprocate within said barrel (110) to inject reducing agent into an exhaust gas flow path; and
a uni-directional valve (140) extending through said barrel (110), a first end of said uni-directional valve (140) in flow communication with air at ambient temperature, an opposite second end of said uni-directional valve (140) in flow communication with said needle chamber (130), said uni-directional valve (140) adapted to channel air at ambient temperature to said needle chamber (130) to increase pressure of reducing agent in said needle chamber (130) to atmospheric pressure.

2. The dosing module (100) in accordance with Claim 1, further comprising an electronic control unit (150) in electronic communication with said uni-directional valve (140) and adapted to control said uni-directional valve (140) to an open position at an end of injection of reducing agent from said dosing module (100) to an exhaust gas flow path.

3. The dosing module (100) in accordance with Claim 2, wherein said electronic control unit (150) is adapted to control said uni-directional valve (140) to the open position when a pressure of reducing agent in said needle chamber (130) defined within said barrel (110) decreases below a user defined pre-determined threshold pressure to facilitate channeling air at ambient temperature within said needle chamber (130) via said uni-directional valve (140).
4. The dosing module (100) in accordance with Claim 2, wherein said uni-directional valve (140) prevents a flow of recusing agent from said needle chamber (130) to the air at ambient temperature.