Claims:
1. An exhaust after treatment system (100) for an internal combustion engine (10), the said exhaust after treatment system (100) comprising:
an exhaust system (110) fluidically connected to exhaust ports/runners (12) of the internal combustion engine (10), wherein the exhaust system (110) is configured with at least one Diesel Oxidation Catalyst (DOC, 112) and at least one Particulate Filter (PF, 114); and
an auxiliary gasoline engine (120), wherein exhaust gas from the auxiliary gasoline engine (120) is configured to be routed through the exhaust system (110) for heating and regeneration.

2. The exhaust after treatment system (100) as claimed in claim 1, wherein an exhaust conduit (126) of the auxiliary gasoline engine (120) is configured to be fluidically coupled to the exhaust system (110) of the internal combustion engine (10) at upstream of the PF (114) for regeneration of the PF.

3. The exhaust after treatment system (100) as claimed in claim 1, wherein the exhaust conduit (126) of the auxiliary gasoline engine (120) is configured to be fluidically coupled to the exhaust system (110) of the internal combustion engine (10) at upstream of the DOC (112) to heat catalyst for efficient oxidization of the hydrocarbons, carbon monoxide, unburned fuel and oil present in the exhaust gases.

4. The exhaust after treatment system (100) as claimed in claim 1, wherein the auxiliary gasoline engine (120) is configured to run an alternator for charging a battery (124).

5. The exhaust after treatment system (100) as claimed in claim 1, wherein the coolant heat of the auxiliary gasoline engine (120) is configured for heating up of the internal combustion engine (10).

6. The exhaust after treatment system (100) as claimed in claim 1, wherein the auxiliary gasoline engine (120) is configured to be mounted at a service station or a vehicle depot for servicing the exhaust system (110) of a vehicle by selective regeneration of the PF (114) and/or heating of the DOC (112).

7. The exhaust after treatment system (100) as claimed in claim 1, wherein the auxiliary gasoline engine (120) is a portable engine, configured to be transported near the vehicle for servicing the exhaust system (110) of the vehicle by regeneration of the PF (114) and/or heating of the DOC (112).

8. The exhaust after treatment system (100) as claimed in claim 1, wherein the auxiliary gasoline engine (120) is configured to be an integral part of the vehicle (1) and integrally connected to the exhaust system (110) for automatic heating and regeneration, wherein said auxiliary gasoline engine (120) is configured to be mounted in any compartment of the vehicle (1).

9. The exhaust after treatment system (100) as claimed in claim 8, wherein a Differential Pressure Sensor (DPS) (30) is configured to be mounted across the PF (114) to sense pressure difference across upstream and downstream of the PF (114) for automatically triggering ‘ON’ the auxiliary gasoline engine (120) through a control unit (20) for regeneration of the PF (114) on exceeding a value of the pressure difference across the PF (114) beyond a predetermined limit.

10. The exhaust after treatment system (100) as claimed in claim 1, wherein the auxiliary gasoline engine (120) is configured with a Three Way Catalyst (TWC) 122 for purification of the exhaust gases before supplying it to the exhaust system (110) of the internal combustion engine (10).
, Description:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
AN EXHAUST AFTER TREATMENT SYSTEM

Applicant:
Tata Motors Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400001,
Maharashtra, India

The following specification particularly describes the subject matter and the manner in which it is to be performed.

FIELD OF THE INVENTION
[001] The present subject matter described herein generally relates to an exhaust after treatment system for an internal combustion engine, and more specifically to a combined system for regeneration of a Particulate Filter and for heating of a Diesel Oxidation Catalyst.
BACKGROUND
[002] The exhaust gas emitted from an internal combustion engine such as but not limiting to diesel engines and some configurations of gasoline engines, is a heterogeneous mixture that may contain gaseous emissions such as carbon monoxide (“CO”), unburned hydrocarbons (“HC”) and oxides of nitrogen (“NOx”) as well as condensed phase materials (liquids and solids) that constitute particulate matter. Catalyst compositions typically disposed on catalyst supports or substrates are provided in an engine exhaust system to convert certain, or all of these exhaust constituents into products of complete combustion. This is for the reason that, if the particulate matter is passed to the surroundings directly, there is a high risk of environmental and health problems.
[003] Stringent regulatory requirements and increasing environmental concerns are driving new technological developments in exhaust after treatment systems. A Diesel Oxidation Catalyst (DOC), a Particulate Filter and Selective Catalytic Reduction (SCR) are the current trends for this purpose in Diesel engines. Similarly a three way catalyst and gasoline particulate filters are primarily being used for this purpose in gasoline engines. The PF effectively removes the particulate matter in the exhaust gas before passing it into the surroundings. However, the PF is a physical structure for removing particulates from exhaust gas and, it results in the accumulation of filtered particulates. Further, accumulation of particulate matter after a certain level will have the effect of increasing the exhaust system backpressure experienced by the engine. This is due to the clogging of the filters by accumulation of particulate matter. To address backpressure caused by the accumulation of exhaust gas particulates, the PF should be periodically cleaned or burnt by passing exhaust gas. The process of cleaning or burning of the accumulated particulate matter on the PF is called regeneration. Different methods of regeneration systems such as late fuel injection, down pipe fuel injection, passive regeneration etc., are conventionally used for regeneration of PF. However, in such conventional techniques oil dilution, deterioration of fuel economy and melting of trap due to spontaneous regeneration etc. are most common drawbacks.
[004] The present subject matter discloses a novel exhaust after treatment system to overcome the limitations stated above.

OBJECTS OF THE INVENTION
[005] An object of the present subject matter is to enable regeneration of a particulate filter of diesel engine by using an auxiliary IC engine & without depending on main diesel engine for regeneration of the particulate filter by its exhaust.
[006] An object of the present subject matter is to enable regeneration of the particulate filter of diesel engine without injecting excess fuel and oxygen in the diesel engine.
[007] Another object of the present subject matter is to enable regeneration of the particulate filter by using a small capacity auxiliary gasoline engine.
[008] Yet another object of the present subject matter is to enable to reduce consumption of fuel for regeneration of the particulate filter.
[009] Yet another object of the present subject matter is to enable automatic regeneration of the particulate filter by using the auxiliary gasoline engine.

SUMMARY
[0010] Before the present system is described, it is to be understood that this application is not limited to the particular machine or device, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to an exhaust after treatment system, and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.
[0011] The present subject matter discloses an exhaust after treatment system for an internal combustion engine. The exhaust after treatment system comprises an exhaust system fluidically connected to exhaust ports/runners of the internal combustion engine. The exhaust system is configured with at least one Diesel Oxidation Catalyst (DOC) and at least one Particulate Filter (PF). The exhaust after treatment system further comprises an auxiliary gasoline engine, wherein exhaust gas from the auxiliary gasoline engine is configured to be routed through the exhaust system for heating and regeneration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The foregoing summary, as well as the following detailed description of embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure, however, the disclosure is not limited to the specific methods and device disclosed in the document and the drawing. The detailed description is described with reference to the following accompanying figures.
[0013] Figure 1 illustrates a conventional exhaust after treatment system for an internal combustion engine (Prior Art).
[0014] Figure 2 illustrates an exhaust after treatment system for an internal combustion engine, in accordance with an embodiment of the present subject matter.
[0015] Figure 3 illustrates the exhaust after treatment system for the internal combustion engine, in accordance with an embodiment of the present subject matter.
[0016] Figure 4 illustrates the exhaust after treatment system for the internal combustion engine, in accordance with an embodiment of the present subject matter.
[0017] Figure 5 illustrates a vehicle comprising an exhaust after treatment system for an internal combustion engine, in accordance with an embodiment of the present subject matter.
[0018] The figures depict various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
[0019] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising", “having”, and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any devices and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, devices and methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0020] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.
[0021] As discussed above, a particulate filter of an internal combustion engine is required to be regenerated after a certain time interval to avoid choking. Different methods of regeneration for particulate filters such as late fuel injection, down pipe fuel injection, passive regeneration etc., are conventionally used. However, in such conventional techniques oil dilution, deterioration of fuel economy and melting of trap due to spontaneous regeneration etc. are most common drawbacks. The present subject matter discloses an effective and innovative system for regeneration of the particulate filters and for heating of catalyst in the internal combustion engine. Various embodiments are illustrated below in accordance with the figures 1 to 5.
[0022] Following is a list of elements and reference numerals used to explain various embodiments of the present subject matter.
Reference Numeral Element Description
1 Vehicle
10 Internal Combustion Engine
12 Exhaust ports/runners of the Internal Combustion Engine
20 Control Unit
30 Differential Pressure Sensor
100 Exhaust After Treatment System
110 Exhaust System
112 Diesel Oxidation Catalyst
114 Particulate Filter
116 Selective Catalytic Reduction
118 Muffler
120 Auxiliary Gasoline Engine
122 Three Way Catalyst
124 Battery
126 Exhaust Conduit
130 Mobile Trolley

[0023] Referring to Figure 1, a conventional internal combustion engine with its exhaust system is illustrated. The exhaust system is configured to be mounted to exhaust ports/runners of the internal combustion engine. The exhaust system may comprise an after treatment system and a muffler. The after-treatment system may comprise a Diesel Oxidation Catalyst (DOC), a Particulate Filter (PF) and a Selective Reduction Catalyst (SCR) for treatment of the exhaust gases before exiting to the surroundings.
[0024] Referring to figure 2, the exhaust after treatment system 100 for an Internal Combustion Engine (ICE) 10 is disclosed in accordance to an embodiment of the present subject matter. The ICE 10 is a diesel engine or any other type of combustion engine. The system 100 comprises an exhaust system 110 fluidically connected to exhaust ports/runners 12 of the diesel engine 10. The exhaust system 110 may comprise a Diesel Oxidation Catalyst (DOC) 112, a Particulate Filter (PF) 114, a Selective Reduction Catalyst (SCR) 116 and a muffler 118. The exhaust system 110 is configured to transfer exhaust gases from the diesel engine 10 to the surrounding after passing from DOC, PF, SCR and the muffler. The DOC 112 oxidizes the hydrocarbons, carbon monoxide and unburned fuel and oil present in the exhaust gases. The PF 114 traps any remaining soot that DOC couldn’t oxidize. The soot remains in the PF 114 until it is regenerated. The SCR 116 introduces Diesel Emissions Fluid (DEF) into the stream of exhaust gases to cause reduction of nitrogen oxides in the exhaust gases that pass through to the SCR filter 116. In an embodiment of the present disclosure, the PF 114 provided in the system 100 is at least one of but not limiting to ceramic honeycomb wall flow filters, wound or packed fiber filters, open cell foams, sintered metal fibers, cyclonic separator etc.
[0025] The system 100 further comprises an auxiliary gasoline engine 120. In an embodiment, an exhaust conduit 126 of the auxiliary gasoline engine 120 may be fluidically connected to the exhaust system 110 of the diesel engine 10 at upstream of the PF 114 to route the high temperature exhaust gas from the gasoline engine through the PF 114 for regeneration. The soot or particulate matter accumulated on the PF 114 are burned down by presence of oxygen and heat in the high temperature exhaust gases emitted from the auxiliary gasoline engine 120. The auxiliary gasoline engine 120 may be configured to start at periodic intervals by manual intervention or by a control unit based on the requirement for regeneration of the PF 114.
[0026] The auxiliary gasoline engine 120 also produces a sufficient amount of mechanical energy which may be utilized to run an alternator for charging a battery 124. Further the battery 124 may be utilized to operate electric or electronic elements of the diesel engine 10 or a vehicle 1. Further the coolant heat of the auxiliary gasoline engine 120 may be utilized for heating up of the diesel engine 10. It is apparent that the gasoline engine 120 may be utilized fully by using various forms of energies produced from the auxiliary gasoline engine 120 for operation of various elements of the diesel engine 10. It is evident from above that the auxiliary gasoline engine 120 doesn’t affect the performance or efficiency of the diesel engine 10 in any way. Further the auxiliary gasoline engine 120 may be configured with a Three Way Catalyst (TWC) 122 for purification of the exhaust gases before supplying it to the exhaust system 110 of the diesel engine 10.
[0027] In another embodiment as illustrated in figure 3, the exhaust gases from the auxiliary gasoline engine 120 may be configured to selectively route through the PF 114 and the DOC 112. Whenever catalyst heating is required, the exhaust gases from the auxiliary gasoline engine 120 may be routed through the DOC 112. Similarly when regeneration of the PF 114 is required, the exhaust gases may be routed through the PF 114 and intermittent controlled misfire may be generated in the auxiliary gasoline engine 120 to cause limited supply of oxygen for regeneration reaction. Thus by controlling amount of misfire, the rate of regeneration can be controlled or stopped.
[0028] In a yet another embodiment, a first valve (not shown) may be configured in the exhaust conduit 126 between the PF 114 and the auxiliary gasoline engine 120 to regulate the flow of exhaust gases through the PF 114. Further a second valve (not shown) may be configured in the exhaust conduit 126 between the DOC 112 and the auxiliary gasoline engine 120 to regulate the flow of exhaust gases through the DOC 112.
[0029] In an embodiment, the auxiliary gasoline engine 120 may be configured to be a separate and independent unit. The auxiliary gasoline engine 120 may be configured to be carried with the diesel engine 10 or it may be fixed at a service station where the diesel engine 10 may be transported to perform regeneration of the PF 114.
[0030] In an embodiment as illustrated in figure 4, the auxiliary gasoline engine 120 may be configured to be portable and separate from the diesel engine 110. The auxiliary gasoline engine 120 may be mounted on a mobile trolley 130 for movement from one place to another place. The exhaust after treatment system 100 configured in such way may be used at a vehicle depot or service station for PF regeneration of a fleet of vehicles. The auxiliary gasoline engine 120 may be moved by the mobile trolley 130 near to any of the diesel engines stationed at the depot and the exhaust conduit 126 of auxiliary gasoline engine 120 may be coupled to the upstream of the PF 114 of the diesel engine. When regeneration is required, the exhaust from the auxiliary gasoline engine 120 may be routed through the PF 114 and intermittent controlled misfire may be generated in the auxiliary gasoline engine 120 which gives limited supply of oxygen for regeneration reaction. Thus by controlling amount of misfire, the rate of regeneration can be controlled or stopped. The fleet vehicles running in city application normally need more frequent regeneration. With the help of mobile trolley, regeneration of PF can be achieved when the fleet vehicles are parked in depot during rest or vehicle servicing.
[0031] Referring to figure 5, the exhaust after treatment system 100 is disclosed in accordance to another embodiment of the present subject matter wherein the automatic regeneration of the PF 114 is carried out whenever required, based on the back pressure sensed by a Differential Pressure Sensor (DPS) 30 mounted across upstream and downstream of the PF 114. The auxiliary gasoline engine 120 may be an integral part of the vehicle 1 and may be placed in available space of any compartment of the vehicle 1. The exhaust conduit 126 of the auxiliary gasoline engine is configured to be coupled with the exhaust system 110 of the diesel engine 10. However, the combustion process of the auxiliary gasoline engine 120 is independent of the combustion in the diesel engine 10. Further the exhaust treatment system 100 configured with a Differential Pressure Sensor (DPS) 30 mounted across upstream and downstream of the PF 114 to continuously measure pressure difference across the PF 114 and this pressure difference is provided to a control unit 20. Initially, pressure difference across the PF 114 is low and it increases gradually as the soot/particulate matter starts trapping in the PF 114. When the pressure difference across the PF 114 exceeds a threshold value, the control unit 30 triggers regeneration of the PF 114 by controlling the operation of the auxiliary gasoline engine 120. The threshold value of the pressure difference may be defined based on the configuration of the diesel engine 10 and the PF 114. This configuration of the exhaust after treatment system 100 enables automatic regeneration of the PF 114 whenever required, based on pressure difference across upstream and downstream of the PF 114 and the amount of accumulated particulate matter on the PF 114.
[0032] The present subject matter discloses an exhaust after treatment system for an internal combustion engine. The exhaust after treatment system comprises an exhaust system fluidically connected to exhaust ports/runners of the internal combustion engine. The exhaust system is configured with at least one Diesel Oxidation Catalyst (DOC) and at least one Particulate Filter (PF). The exhaust after treatment system further comprises an auxiliary gasoline engine, wherein exhaust gas from the auxiliary gasoline engine is configured to be routed through the exhaust system for heating and regeneration.
[0033] An exhaust conduit of the auxiliary gasoline engine may be configured to be fluidically coupled to the exhaust system of the internal combustion engine at upstream of the PF for regeneration of the PF. Further the exhaust conduit of the auxiliary gasoline engine may be configured to be fluidically coupled to the exhaust system of the internal combustion engine at upstream of the DOC to heat catalyst for efficient oxidization of the hydrocarbons, carbon monoxide, unburned fuel and oil present in the exhaust gases.
[0034] The auxiliary gasoline engine may be configured to run an alternator for charging a battery to efficiently utilize mechanical energy of the auxiliary gasoline engine. Further the coolant heat of the auxiliary gasoline engine may be configured for heating up of the internal combustion engine.
[0035] In an embodiment, the auxiliary gasoline engine is configured to be mounted at a service station or a vehicle depot for servicing the exhaust system of a vehicle by selective regeneration of the PF and/or heating of the DOC. In another embodiment, the auxiliary gasoline engine is portable and configured to be transported near the vehicle for servicing the exhaust system of the vehicle by regeneration of the PF and/or heating of the DOC.
[0036] Further the auxiliary gasoline engine is configured with a Three Way Catalyst (TWC) for purification of the exhaust gases before supplying it to the exhaust system of the internal combustion engine.
[0037] In a yet another embodiment, the auxiliary gasoline engine is configured to be an integral part of the vehicle and integrally connected to the exhaust system for automatic heating and regeneration, wherein said auxiliary gasoline engine is configured to be mounted in any compartment of the vehicle .A Differential Pressure Sensor (DPS) is configured to be mounted across the PF to sense pressure difference across upstream and downstream of the PF for automatically triggering ‘ON’ of the auxiliary gasoline engine through a control unit for regeneration of the PF on exceeding a value of the pressure difference across the PF beyond a predetermined limit.
[0038] Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include the following.
[0039] Some embodiments of the subject matter enable regeneration of a PF of diesel engine without injecting excess fuel and oxygen in the diesel engine.
[0040] Some embodiments of the subject matter enable to achieve regeneration of the PF by using a small capacity auxiliary gasoline engine.
[0041] Some embodiments of the subject matter enable to reduce consumption of fuel for regeneration of the PF.
[0042] Some embodiments of the subject matter enable to achieve regeneration of the PF in a shorter time.
[0043] Some embodiments of the subject matter enable to increase thermal efficiency of the diesel engine by utilizing coolant heat of the auxiliary gasoline engine.
[0044] Some embodiments of the subject matter enable to utilize mechanical energy of the auxiliary gasoline engine by charging a battery.
[0045] Although implementations for the exhaust after treatment system 100 have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features described. Rather, the specific features are disclosed as examples of implementation for the exhaust after treatment system 100.