Claims:WE CLAIM:
1. An exhaust gas aftertreatment apparatus (120) for an engine (10), said apparatus (120) including a radiator (20) provided with a fan (90), a urea doser module (40) (hereinafter referred to as UDM) (40), a degassing tank (30) and a plurality of conduits circulating a cooling fluid within said apparatus (120), said apparatus (120) configured to establish a thermosyphoning effect for cooling said UDM (40), said apparatus (120) comprising:
• a first conduit (50) and a second conduit (60) provided between said engine (10) and a first port (42) of said UDM (40);
• a third conduit (60) and a fourth conduit (110) provided between a second port (44) of said UDM (40) and said engine (10) through said degassing tank (30);
• a cooler (100) defined between said first conduit (50) and said second conduit (60), wherein said cooler (100) is configured to cool the cooling fluid exiting said engine (10) for a predetermined time after said engine (10) is shut off, to initiate said thermosyphoning effect between said first conduit (50) and said second conduit (60).
2. The apparatus (120) as claimed in claim 1, wherein a fan (90) is provided on said radiator (20), said fan (90) is configured to be selectively run by said engine (10) or an external power source, while said apparatus (120) operates in either said first condition or said second condition.
3. The apparatus (120) as claimed in claim 1, wherein said UDM (40) has a first port (42) and a second port (44), said first port (42) configured to be in fluid commnication with an end of said second conduit (60), and said second port (44) configured to be in fluid communication with an end of said third conduit (70).
4. The apparatus (120) as claimed in claim 2, wherein said cooler (100) is in fluid communication with said first conduit (50), said second conduit (60) and is configured to be cooled by said radiator fan (20) .
5. The apparatus (120) as claimed in claim 1, wherein said apparatus (120) includes a fouth conduit (110) in fluid communication with said degassing tank (30) and said mechanical pump (80).
6. The apparatus (120) as claimed in claim 1, a mechanical pump (80) is provided on said engine to circulate said fluid into said engine (10).
, Description:FIELD
The present disclosure relates to exhaust gas aftertreatment apparatus for an engine having provision for thermosiphon cooling of UDM injector with initial forced convection cooler, for reducing harmful nitrous oxide emissions through the engine.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Exhaust gases emitting from engines contain high amounts of nitrogen oxides that need to be minimized. The selective catalytic reduction (SCR) technique is commonly incorporated into engine exhausts. SCR involves dosing urea (DEF, diesel exhaust fluid) into the exhaust gases emitting from the engine before the exhaust gas pass through the selective catalytic reducers. The temperature of the urea dozer tip increases during this dosing process as the dozer tip is exposed to the hot exhaust gas stream of the engine. This reduces the life of the urea dozer tips, replacement of which is expensive. Efficient cooling of the urea dozer tips needs is accomplished by employing a dedicated coolant pump which further increases the costs of the aftertreatment systems exhorbitantly as seen in figure 2. The coolant pump activates 8 minutes after engine shutoff to circulate the coolant in the UDM injector, thus cooling the UDM injector.
There is, therefore, felt a need of an efficient and frugal method for cooling of UDM injector used for exhaust gas aftertreatment apparatus to tackle the aforementioned problems. The UDM injector tip temperature is to be maintained less than 120 degrees Celsius.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide an exhaust gas aftertreatment apparatus that efficiently cools the UDM injector tip and thus increases life of the UDM using thermosyphon principle.
Another object of the present disclosure is to provide an aftertreatment apparatus that eliminates need for a dedicated pump.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to an exhaust gas aftertreatment apparatus for an engine including a radiator and a degassing tank. The exhaust gas aftertreatment apparatus comprises a urea doser module. The UDM cooling arrangement includes a first conduit routed from the Cooler to the UDM, and a second conduit routed from the UDM to the degassing tank. The cooling of the UDM is achieved initially (stage 1) by improving the thermosyphon efficiency, we integrated the cooler coil at the back of the radiator with after engine shutoff fan run strategy (fan switched ON for 3 min). This enables the forced convection and thus reduces the coolant temperature before the UDM-In and facilitates for thermosyphon process.
In the final stages i.e stage 2 to 4, the thermosyphon principle causes the coolant flow thorough the UDM, causing the UDM tip to be cooled. The coolant flows from UDM-In to UDM-Out or UDM-Out to UDM-In at different stage of the cooling cycle refer figure 3 and 4.
The cooler gets the coolant from the branch before the EGR inlet. The engine to the radiator and radiator to thermostat is conduit routed for engine coolant to be cooled and thus maintaining the engine temperature; The degassing bottom is conduit routed by a makeup hose and its function is to feed the coolant to the system.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The exhaust gas aftertreatment apparatus for an engine with UDM injector cooling of the present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 shows a schematic view of a proposed cooling of UDM injector with forced convection cooling circuit, in accordance with an embodiment of the present disclosure.
Figure 2 shows a schematic view of a conventional cooling of UDM injector used for exhaust gas aftertreatment apparatus for an engine, which uses and electric coolant pump;
Figure 3 shows an plot of experimentally observed temperature vs time monitored at UDM-In UDM-Out, cooler inlet and degassing tank port on the apparatus, corresponding to testcase static regeneration + hotshutoff condition;
Figure 4 shows an plot of experimentally observed temperature vs time monitored at UDM-In UDM-Out, cooler inlet and degassing tank port on the apparatus, corresponding to testcase max torque induced regeneration + hotshutoff condition; and
Figure 5 shows a plot of experimentally observed temperature vs time monitored at UDM-Tip, UDM-Out, Raditor inlet, of UDM injector used for exhaust gas aftertreatment apparatus for an engine, which uses an electric coolant pump, corresponding to testcase static regeneration + hotshutoff condition, described in the Figure 3.

LIST OF REFERENCE NUMERALS
10 – engine
20 – radiator
30 – degassing tank
40 – urea doser module (UDM)
42 – UDM first port
44 – UDM second port
50 – first conduit
60 – second conduit
70 – third conduit
80 – pump
90 – radiator Fan
100 – cooler
110 – fourth conduit
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises”, “comprising”, “including” and “having” are open-ended transitional phrases and therefore specify the presence of stated features, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
When an element is referred to as being “mounted on”, “engaged to”, “connected to” or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed elements.
Terms such as “inner”, “outer”, “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used in the present disclosure to describe relationships between different elements as depicted from the figures.
Referring to Figure 1, an exhaust gas aftertreatment apparatus 120 (hereinafter referred to as apparatus 120) of an engine 10 having a thermosyphon cooling method for UDM injector with forced convection cooler is shown, in accordance with an embodiment of the present disclosure. The engine 10 is provided with a radiator 20 that facilitates cooling of a coolant being circulated in the engine 10 by a pump 80, upon which the cooled coolant is recirculated back into the engine 10. The apparatus 120 having thermosyphon cooling of UDM injector with forced convection cooler includes a degassing tank 30, a urea doser module 40 (hereinafter referred to as UDM injector 40) and cooler 100. The cooled coolant is received into the pump 80 mounted on the engine 10. The pump 80 recirculates the cooled coolant into the engine 10 and a part of the cooled coolant is bled into an UDM injector 40 during the engine ON condition. The apparatus 120 comprises a first conduit 50 preferably in the form of a pipeline or a flexible hose with one end configured to receive the recirculated cooled coolant, while the other end of the first conduit 50 is connected to an inlet port of the cooler 100. The outlet port of the cooler 100 is connected by a second conduit 60 to a first port 42 of the UDM injector 40. A second port 44 of the UDM 40 is connected by a third conduit 70 to the vent port of degassing tank 30. The UDM apparatus 120 further comprises a fourth conduit 110 connected between the degassing tank 30 and the pump 80 which facilitates maintaining the required coolant quantity in the cooling system.
The working of the apparatus 120 will now be described referring to figures 1,3 and 4. The heated coolant is received into the radiator 20 from the engine coolant outlet for cooling. After passing through the radiator 20, the cooled coolant is again routed into the engine coolant inlet for further recirculation for absorption of heat generated in the engine. A pump 80 mounted on the engine 10 receives the cooled fluid from the radiator 20. The coolant is pumped by the pump 80 into the engine 10, a part of which is bled into the first conduit 50.
During the engine ON condition, the first port 42 of the UDM injector 40 is now exposed to cold coolant at a temperature T1, while the second port 44 of the UDM 40 is exposed to hot fluid at a temperature T2 due to the heat impart by the tip of the UDM injector 40. The coolant flows from the first port 42 to the second port 44.
During the engine OFF condition, the mechanical pump 80 switches OFF and then the following stages of thermosyphon effect is observed. To improve the thermosyphon efficiency, the cooler 100 is integrated with after Engine shutoff fan run strategy (3 min). This enables the forced convection and thus reduces the coolant temperature at the first port 42 of the UDM 40 and facilitates for thermosyphon process. This temperature difference (T2-T1) or (T1-T2) sets up natural convection current in the apparatus 120 which causes the coolant to flow back and forth in the UDM 40 as seen in the below stages. Figures 3 and 4 depict result plots of experimental validation tests undertook under distinct running conditions of a vehicle on which the apparatus 120 was instrumented. Figure 3 shows testcase 1 ‘static regeneration + hotshutoff’ condition with the following observed conditions and monitored parameters as below:

Stage 1 - After engine shutoff, the fan is switched on for 3 minutes and the coolant flows from the first port 42 of the UDM 40 to the second port 44 of the UDM 40, as T2 > T1.
Stage 2 - After the fan is switched OFF and the coolant continues to flow from the first port 42 of the UDM 40 to the second port 44 of the UDM 40, as T2 > T1.
Stage 3 - There is a reverse flow of the coolant from the second port 44 of the UDM 40 to the first port 42 of the UDM 40, as T1 > T2
Stage 4 - There is a reversal flow of the coolant from the first port 42 of the UDM 40 to the second port 44 of the UDM 40, as T2 > T1.
Figure 4 shows testcase 2 max torque induced regeneration + hotshutoff condition with the following observed conditions and monitored parameters as below:
Stage 1 – After engine shutoff, the fan is switched on for 3 minutes and the coolant flows from the first port 42 to the second port 44 of the UDM 40, as T2 > T1.
Stage 2 - After the fan is switched OFF and the coolant flow reverses from the second port 44 to the first port 42 of the UDM 40, as T1 > T2.
Stage 3 There is a reverse flow of the coolant from the first port 42 to the second port 44, as T2 > T1.
Stage 4 There is again a reverse flow of the coolant from the second port 44 to the first port 42, as T1 > T2
As observed from figure 3 and figure 4, the temperature monitored the first port 42 and the second port 44 of the UDM 40 is well below the desired temperature limit of 120 degree Celsius. Hence, the UDM 40 tip temperature is ensured to be below 120 degree Celsius, and therefore safe.
The technical advantage lies in elimination of a dedicated electric pump 130 that would have been needed to be connected between the third conduit 70 and the fouth conduit 110, which would pump the coolant from the UDM 40 to the fourth conduit 110 during engine OFF condition. In the present disclosure, the coolant is cooled in the radiator 20 before entering the first port 42 of the UDM 40 via first conduit 50 during engine ON condition and by thermosyphon process during engine OFF condition.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of an exhaust gas aftertreatment apparatus for an engine that:
• offers increased life of a urea dosing module (UDM);
• facilitates efficient cooling of the UDM;
• eliminates the need for a dedicated pump for recirculation of the coolant, and
• saves power requirement of the apparatus and also the cost thereof.
The foregoing disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.