TECHNICAL FIELD

[0001] The present subject matter relates to a multi-fuel vehicle platform. More particularly, to a secondary air injection system.

5 BACKGROUND

[0002] Conventionally, the vehicles are powered by an internal combustion (IC) engine. The internal combustion (IC) engine comprises a cylinder head, abutting a cylinder block to form a combustion chamber where the burning of air fuel mixture occurs. The cylinder head comprises of an intake valve and an exhaust valve which 10 control the intake of air fuel mixture inside the combustion chamber, and controls the exit of exhaust gases after the combustion. The exhaust gases include harmful emissions of hydrocarbons, carbon monoxide and nitrogen oxides into the atmosphere. In order to reduce the emissions of internal combustion engines, a number of different strategies are being used.

15

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The detailed description is described with reference to an embodiment of single cylinder engine assembly with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components. 20 [0004] Figure 1 illustrates a perspective view of a cylinder head of an internal combustion (IC) engine (100) (hereinafter “engine”) along with few peripheral systems where few parts are omitted from the figure for sake of brevity.

[0005] Figure 2 illustrates an exploded view of the engine (100) and a localized view of a flame retarding member (201) where few parts are omitted from the figure 25 for sake of brevity.

[0006] Figure 3 illustrates a cut section view of the engine (100) across A-A’ axis as shown in figure 1 and a localized view of the flame retarding member (201) where few parts are omitted from the figure. l DETAILED DESCRIPTION

[0007] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder. Further "front" and "rear", and "left" and "right" referred to in the ensuing description of the illustrated embodiment refer to front and rear, and left and right directions as seen from a rear portion of an engine assembly and looking forward. Furthermore, a longitudinal axis Y - Y’ unless otherwise mentioned, refers to a front to rear axis relative to the engine assembly, while a lateral axis C - C’ unless otherwise mentioned, refers generally to a side to side, or left to right axis relative to the engine assembly.

[0008] However, it is contemplated that the disclosure in the present invention may be applied any engine assembly without defeating the spirit of the present subject matter. The detailed explanation of the constitution of parts other than the present invention which constitutes an essential part has been omitted at suitable places.

[0009] The gasoline fueled spark ignition engines are the dominant powertrain configuration till date. The theoretical working cycle of a four-stroke engine gasoline fueled spark ignition engines is based on an Otto cycle. In four stroke engine the thermodynamic cycle is completed in four strokes of a piston. A combustible homogenous air fuel mixture, sucked inside an engine cylinder, is ignited with the help of a spark plug. More particularly, the charge of air fuel mixture is induced into the engine cylinder as the piston moves from a top dead center (hereinafter TDC) to a bottom dead center (hereinafter BDC). The charge is then compressed and ignited by the spark plug before the TDC producing high pressure and temperature at about the TDC. The gas expands and work is produced as the piston moves to the BDC. An exhaust valve opens and the exhaust gases come out from a combustion chamber as the piston again moves to the TDC. The exhaust valve closes and an intake valve opens with the piston now moving back towards the BDC to draw in a fresh charge. The tradeoff on the cost and effectiveness of the spark ignition (SI) engine technologies are complex in nature & include limitation on a compression ratio based on available octane level of the gasoline fuel. Therefore, automobile manufacturers continuously try improving the air fuel mixture formation and combustion process in order to reduce engine raw emissions and to get best power and torque with available fuel.

[00010] Hence various devices like exhaust turbochargers are used to improve the performance. But, the known exhaust solutions for the internal combustion engines are associated with several disadvantages that include excessively bulky engine compartment.

[00011] Further, secondary air injection (SAI) systems are used to inject secondary air into the exhaust passage for the purpose of rebuming the unbumed elements in the exhaust gases. The system comprises of a valve and tubes. The tube comprising of a metallic tube and a hose. The one end of metallic tube is operatively connected to a cylinder head of an engine whereas other end is operatively connected to the hose. The hose connects the metallic tube with the valve. Under some situations because the engine operates at wide range of engine speed, the flame resulting from the combustion or after combustion passes through the metallic tube and enters into the hose. At times the flames from unbumt fuel at exhaust port are strong enough to potentially damage/puncture the hose. Such damage can spread throughout the length of the hose. As per an aspect, the entire connection of the exhaust port to the SAI system may be through a metal tube. However, this greatly constraints the degree of freedom to dispose the SAI in the layout of the vehicle. Additionally, achieving a secure & leak proof joint of the metal tube directly being coupled to the SAI output will necessitate very high geometrical accuracy which is either not feasible or can be exorbitantly expensive. Thus the use of a hose connecting the tube to SAI output region becomes practically unavoidable. In addition to above, unfiltered air can enter in the engine through the damaged hose which can thereby cause significant damage to engine. Further, the unattended damage to the engine can lead to engine seizure. [00012] To overcome aforesaid problem, it is known in the art to reduce the intensity of the flame within the metallic tube by using active cooling means. But it is observed that the solution does not focus at the source of origin of flame in the system. Further, cooling through external means require major changes in the layout of the engine due to introduction of new parts and components which will not only consume more layout space but also add undesirable weight and cost to the engine assembly. Furthermore, the increased number of mechanical components presents difficulty in the engine assembly at the time of manufacturing as well as service. [00013] Thus, overall, the design challenge to meet the above outlined requirements becomes an endless moving target to achieve and a trade-off becomes imminent. Designing a compact efficient engine assembly with a right trade-off and selecting the factors to trade-off is where lies the challenge for a design engineer.

Hence, there remains a need for a system overcoming all above problems and as well as overcoming problems of known art.

[00014] It is an object of the present invention to provide system which can retard the entering of flame from the exhaust port to the hose yet deliver sufficient secondary air in the engine.

[00015] It is another object of the present invention to provide a cost effective solution, requiring little space.

[00016] It is an object of the present invention to provide a system which is light in weight and easy to manufacture and assemble.

[00017] This and other objects are achieved by an improved secondary air injection system for an engine. The secondary air injection system as per the present invention comprises of one or more flame retarding member. The flame retarding member eliminates the entering of the flames from an exhaust port of an engine into one or more SAI tube. This improves the durability of the secondary air injection system. [00018] With respect to the layout, as per an embodiment of the present invention the secondary air injection system comprises of one or more secondary air injection (SAI) tube. The SAI tube includes one or more secondary air injection (SAI) metallic tube and one or more secondary air injection (SAI) elastomeric hose. The SAI metallic tube is operatively connected to one or more cylinder head. The cylinder head is configured to have one or more secondary air injection (SAI) ports.

[00019] Further, in one implementation, said flame retarding member is disposed in one or more SAI ports.

[00020] As per alternative embodiment, said flame retarding member is placed in the passageway of said SAI metallic tube. [00021] As per one implementation, said SAI port is configured to have one or more counterbore, said counterbore is adapted to receive a portion of the SAI metallic tube.

[00022] As per one implementation, said flame retarding member is disposed in said counterbore upstream of a front end of the SAI metallic tube.

[00023] As per one implementation, said flame retarding member is configured to have a peripheral portion and plurality of openings radiating outwardly from its center.

[00024] As per one implementation, said openings are four in number.

[00025] As per one implementation, said cross sectional area of said flame retarding member is substantially more than the cross sectional area of the SAI metallic tube such that the cross sectional area for secondary air intake is maintained as that of the SAI metallic tube.

[00026] As per one implementation, the flame retarding member is integrated with a front end portion of the secondary air injection tube.

[00027] The foregoing disclosure is not intended to limit the present disclosure to the precise forms or particular fields of use disclosed. As such, it is contemplated that various alternate embodiments and/or modifications to the present disclosure, whether explicitly described or implied herein, are possible in light of the disclosure. Having thus described embodiments of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the scope of the present disclosure. Thus, the present disclosure is limited only by the claims.

[00028] In the foregoing specification, the disclosure has been described with reference to specific embodiments. However, as one skilled in the art will appreciate, various embodiments disclosed herein can be modified or otherwise implemented in various other ways without departing from the spirit and scope of the disclosure. Accordingly, this description is to be considered as illustrative and is for the purpose of teaching those skilled in the art the manner of making and using various embodiments of the disclosure. It is to be understood that the forms of disclosure herein shown and described are to be taken as representative embodiments. Equivalent elements, materials, processes or steps may be substituted for those representatively illustrated and described herein. Moreover, certain features of the disclosure may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure. Expressions such as “including”, “comprising”, “incorporating”, “consisting of’, “have”, “is” used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.

[00029] Further, various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, coupled, connected, etc.) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer that two elements are directly connected to each other.

[00030] Additionally, all numerical terms, such as, but not limited to, “first”, “second”, “third”, “primary”, “secondary”, “main” or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader's understanding of the various elements, embodiments, variations and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any element, embodiment, variation and/or modification relative to, or over, another element, embodiment, variation and/or modification. [00031] It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. Additionally, any signal hatches in the drawings/figures should be considered only as exemplary, and not limiting, unless otherwise specifically specified. [00032] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[00033] Figure 1 illustrates a perspective view of a cylinder head of an internal combustion (IC) engine (100) (hereinafter “engine”) along with few peripheral systems where few parts are omitted from the figure for sake of brevity. The engine (100) comprises a cylinder head (101). A secondary air injection (SAI) system (102) is operatively connected to the engine (100). The SAI system (102) supplies air to the engine (100) to facilitate the combustion of hydrocarbons in the exhaust gases. The SAI system (102) includes secondary air injection (SAI) tube (102B), and a secondary air injection (SAI) valve (102A). The filtered air from SAI valve (102A) flows towards the cylinder head (101) via SAI tube (102B). The SAI tube (102B) comprises of secondary air injection (SAI) metallic tube (102BA) and a secondary air injection (SAI) elastomer hose (102BB). The one end of SAI metallic tube is operatively connected to the cylinder head (101) of the engine (100) whereas other end is operatively connected to the SAI elastomer hose (102BB). The SAI elastomer hose (102BB) connects the SAI metallic tube (102BA) with the SAI valve (102A). As indicated by the arrows, secondary air flows through the SAI tube (102B), through the SAI valve (102A) into cylinder head (101) of the engine.

[00034] Figure 2 illustrates an exploded view of the engine (100) and a localized view of a flame retarding member (201) where few parts are omitted from the figure for sake of brevity. A front end (102BAA) of said SAI metallic tube (102BA) is adapted for connection to a secondary air injection (SAI) attachment portion (101A) in the cylinder head (101) of the engine (100). The other end of the SAI metallic tube (102BA) is connected to SAI elastomer hose (102BB) using suitable attaching means (102BC). The SAI metallic tube (102BA) is secured to the (SAI) attachment portion (101 A) through a flange (102BAC) and bolts (102BAB). A flame retarding member (201) is positioned upstream of the front end (102BAA) of the SAI metallic tube (102BA). The flame retarding member (201) is configured to have a peripheral portion (201B) and plurality of openings (201A). The plurality of openings (201A) are radiating outwardly from its center. As per preferred embodiment, the openings are four in number. [00035] Figure 3 illustrates a cut section view of the engine (100) across A-A’ axis as shown in figure 1 and a localized view of the flame retarding member (201) where few parts are omitted from the figure. The cylinder head (101) includes a secondary air injection (SAI) port (101D) extending from exhaust port (101B) towards the SAI attachment portion (101A). As per an embodiment, the flame retarding member (201) is positioned in the SAI port (101D). More specifically, the flame retarding member (201) is placed in the passageway communicating the SAI port (101D) and the SAI metallic tube (102BA). As per alternative embodiment, said flame retarding member (201) is placed in the passageway of said SAI metallic tube (102BA).Further, the SAI port (101D) is configured to have a counterbore (101C). The diameter of counterbore (101C) is larger than the SAI port diameter (101D) adapted to receive a portion of the SAI metallic tube (102BA). As per an alternate embodiment, the cross section of the SAI port (101D) and / or the counterbore portion (101C) (downstream portion) can be of any other geometrical shape & the cross sectional area of the SAI port (101D) is smaller than the cross sectional area of the counterbore portion (101C). Specifically, the front end (102BAA) of the SAI metallic tube (102BA) is inserted into the counterbore (101C). The flame retarding member (201) is disposed in a sandwich manner between the SAI port (101D) and the SAI tube (102B) and is fixed relative to position of the SAI metallic tube (102BA) and SAI port (101D). The outer diameter (A) of the flame retarding member (201) is substantially more than the outer diameter (B) of the SAI metallic tube (102BA) such that the required cross sectional area for secondary air intake is maintained as that of the SAI metallic tube (102BA). Thus, the openings (201A) permits the free passage of secondary air, but also quench the flames which would attempt to pass through the flame retarding member (201), that is, the flame retarding member (201) will intercept and retard any flame which would otherwise pass through from SAI port (101D) into SAI metallic tube (102BA). The flame retardation is achieved because flame retarding member (201) effectively segments or breaks the flames in the exhaust port (101B) of the cylinder head (101) due to plurality of opening (201A). As per an embodiment, the plurality of openings (201A) are spaced sufficiently far apart at a predetermined distance from each other. Thus the residual flame, which is segmented at the upstream source region, loses its intensity or is compelled to adequately die out within the SAI metallic tube (102BA) thereby not reaching to the hose which is vulnerable to damage. As per alternative embodiment; the flame retarding member (201) is integrated with the front end portion (102BAA) of the SAI metallic tube (102BA).

[00036] According to above architecture, the primary efficacy of the present invention is that the flame retarding member eliminates the entering of the flame into SAI tube which improves the durability of SAI system. More specifically, of the hose.

[00037] According to above architecture, the primary efficacy of the present invention is that the flame retarding member can be easily removed by removing the SAI metallic tube without dismounting the complete engine assembly from a vehicle which reduces the service time.

[00038] According to above architecture, the primary efficacy of the present invention is that the flame retarding member is positioned in the SAI port with minimum modification in the design of SAI port which enables ease of manufacturing, minimizes operational and assembly cost. Additionally, the assembly of the flame retarding member can be accomplished with the cylinder head in position in the engine or on the vehicle. This greatly facilitates ease of assembly. Subsequently, the SAI tube connections can be connected to the cylinder head. [00039] According to above architecture, the primary efficacy of the present invention is that the flame retarding member reduces the flame propagation from the exhaust port into the SAI tube without use of active cooling means which reduces overall weight of the engine and improves power to weight ratio.

[00040] According to above architecture, the primary efficacy of the present invention is that, the flame retarding member can be used for different operating strategies of the vehicles, internal combustion engines having different number of cylinders.

[00041] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention.

List of references F - Front 20 102B - Secondary air injection tube R - Rear 102BA - Secondary air injection metallic tube

C - C’ - Lateral axis

102BAA - Front end of the

Y - Y’ - Longitudinal axis secondary air injection tube

100 - Internal combustion engine

25 102BAB - Bolt to connect 101 - Cylinder head secondary air injection tube to the cylinder head

101 A - Secondary air injection tube attachment portion 102BAC - Flange

10 IB - Exhaust port 102BB - Secondary air injection 30 elastomer hose

101C -Counterbore

102BA - Attachment means 101 D - Secondary air inj ection port

201 - Flame retarding member

102 - Secondary air injection system 201 A - Opening in flame retarding member

102A - Secondary air injection valve 35 201A - Peripheral portion of flame retarding member.