FIELD OF INVENTION:
[001] The present subject matter described herein, relates to an internal combustion engine for a vehicle, and, in particular, to an intake air manifold with tumble generation mechanism to improve internal combustion engine knock resistance. More particularly, the present subject matter relates to a ramp shape tumble generating structure at end of air runners of intake air manifold to increase velocity of air vertex at top portion of intake port for avoiding knocking in the combustion chamber.
BACKGROUND AND PRIOR ART:
[002] In existing Intake air manifold is used to supply maximum amount of air in the combustion chamber through intake port. The internal combustion engine has a plurality of combustion cylinders. Further, in order to get stabilize combustion in the internal combustion engine (hereinafter referred to as engine), a lean air-fuel mixture is to be provided in the engine for better engine performances.
[003] The flow of air into the combustion cylinders can be changed by changing the plenum volume and shape, runner lengths and cross-sectional shapes, and overall manifold layout and geometry of the intake air manifolds. Generally, the intake air manifold has a fixed geometry that is optimized for a certain range of engine speeds and thus represents a compromise for other conditions.
[004] Further, the combustion efficiency of the engine can be improved by producing vortex flows in the intake air that is supplied to a combustion chamber. Generally, vortex flows are classified into a swirl flow, which is a lateral vortex flow that eddies and proceeds along the circumferential direction of a cylinder, and a tumble flow, which is a vertical vortex flow that eddies and proceeds along the axis perpendicular to cylinder axis in the cylinder.
[005] Fig. 1 illustrates assembly of intake air manifold and combustion chamber without tumble generation device. The intake air manifold 102 is connected with intake port 104 in the assembly 100. The intake valve 103 is fixed in the combustion chamber 101. During suction stroke, the intake valve 103 receives the air from top and bottom side both. There is no tumble generating device either in the intake air manifold or in the intake port. Therefore, there is less knocking resistance in the combustion chamber.
[006] In order to get the tumble flow in the engine, several techniques has been proposed to improve the flow of air in the combustion cylinder. In the conventional, tumble generating device, such as movable valve or butterfly valve are provided into intake port only at appoint just ahead of the intake valve which is closer to combustion chamber to generate the tumble flow in combustion chamber for fast/better combustion. Fig. 3 illustrates the position of tumble generating device in the intake port 106. The assembly 100 has a tumble generating device 106 in the intake port 104. The tumble generating device 106 releases the air just above the air intake valve 103. Several shortcomings are associated with the existing tumble generating devices in the intake port are that cost of providing tumble generation device/plate is higher in intake port, Metallic plate/device is required in intake port due to high temperature of intake port compare to intake air manifold, high loss of Coefficient of discharge in case the tumble generation plate/device in intake port. Further, in the existing system compromise to be done between coefficient of discharge and Tumble flow coefficient.
[007] In view of the above, it is beneficial to have a tumble generating device in the intake air manifold that eliminates the requirement of tumble generating device in the intake port. Therefore, there is a need in the art to provide a tumble generating structure in the intake air manifold that is more simple and inexpensive, and which can eliminates the existing above mentioned problems.

SUMMARY OF THE INVENTION:
[008] The subject matter disclosed herein relates to an intake air manifold for an internal combustion engine to improve tumble generation inside combustion cylinder. In order to improve fuel consumption and emission performance high compression ratio is requirement. While operating engine at high compression ratio knocking is major issue which lead to drop in engine performance. To counter the same flow vertex velocity inside the combustion chamber is increased, increased vertex velocity of flow lead to fast propagation of flame inside the combustion chamber and improve the knock performance of engine. To provide increased vertex velocity and to improve knock performance of the engine, a ramp shape tumble generating structure is disposed in the intake air manifold. The intake air manifold has a plurality of air runner depends on the number of cylinders in the internal combustion engine. The plurality of air runners allows passage of air to the combustion cylinder of the internal combustion engine. In order to achieve the object of the present invention, a ramp shape tumble generating structure (RSTGS) is provided at end of each of the plurality of air runners to change air flow cross section to generate tumble inside combustion cylinder of the internal combustion engine. The ramp shape tumble generating structure (RSTGS) is an inclined structure which starts from the base of the air runner and goes upto end surface of the air runner from where air intake port starts. The ramp shape tumble generating structure (RSTGS) reduces opening of the air runner towards air intake port and increases the pressure and velocity of the air in the air intake port. The plurality of air runners is in cylindrical pipe shape. The ramp shape tumble generating structure (RSTGS) changes the air flow cross section of the air stream so that air enters into the combustion chamber/cylinder from top of valve face and move along with the cylinder axis and generate high level of tumble when piston of the cylinder moves up and creates high velocity vertex to create turbulence in the combustion chamber during combustion and increases flame propagation speed to avoid knocking in the combustion chamber.
[009] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0011] Fig. 1 illustrate existing assembly of intake air manifold with the combustion cylinder without tumble generating device as known in the art;
[0012] Fig 2 illustrates tumble generation in intake manifold flange, in accordance with an embodiment of the present subject matter;
[0013] Fig. 3 illustrates intake air manifold with tumble generation device in intake port of the internal combustion engine as known in the prior art;
[0014] Fig. 4 illustrates cross section view of the intake air manifold with tumble generation device in intake air manifold, in accordance with an embodiment of the present subject matter;
[0015] Fig. 5a illustrates air flow direction in the intake air manifold in the existing combustion chamber;
[0016] Fig. 5b illustrates air flow direction from the intake air manifold to the combustion chamber, in accordance with an embodiment of the present subject matter;
[0017] Fig. 6a illustrates Air flow vertex in existing design of intake air manifold;
[0018] Fig. 6b illustrates air flow vertex in intake air in the combustion chamber, in accordance with an embodiment of the present subject matter; and
[0019] Fig. 7 illustrates PV diagram engine for high CR application while increasing pumping loss by minimum possible value, in accordance with an embodiment of the present subject matter.
[0020] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0021] The subject matter disclosed herein relates to an intake air manifold for an internal combustion engine to improve tumble generation inside combustion cylinder. In order to improve fuel consumption and emission performance high compression ratio is requirement. While operating engine at high compression ratio knocking is major issue which lead to drop in engine performance. To counter the same flow vertex velocity inside the combustion chamber is increased, increased vertex velocity of flow lead to fast propagation of flame inside the combustion chamber and improve the knock performance of engine. To provide increased vertex velocity and to improve knock performance of the engine, a ramp shape tumble generating structure is disposed in the intake air manifold. The intake air manifold has a plurality of air runner depends on the number of cylinders in the internal combustion engine. The plurality of air runners allows passage of air to the combustion cylinder of the internal combustion engine. In order to achieve the object of the present invention, a ramp shape tumble generating structure (RSTGS) is provided at end of each of the plurality of air runners to change air flow cross section to generate tumble inside combustion cylinder of the internal combustion engine. The ramp shape tumble generating structure (RSTGS) is an inclined structure which starts from the base of the air runner and goes upto end surface of the air runner from where air intake port starts. The ramp shape tumble generating structure (RSTGS) reduces opening of the air runner towards air intake port and increases the pressure and velocity of the air in the air intake port. The plurality of air runners is in cylindrical pipe shape. The ramp shape tumble generating structure (RSTGS) changes the air flow cross section of the air stream so that air enters into the combustion chamber/cylinder from top of valve face and move along with the cylinder axis and generate high level of tumble when piston of the cylinder moves up and creates high velocity vertex to create turbulence in the combustion chamber during combustion and increases flame propagation speed to avoid knocking in the combustion chamber.
[0022] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0023] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0024] The existing intake air manifold is used to supply maximum amount of air in the combustion chamber through intake port. But for improving fuel consumption and emission performance high compression ratio is requirement. While operating engine at high compression ratio knocking is major issue which lead to drop in engine performance. To counter the same flow vertex velocity inside the combustion chamber is increased, increased vertex velocity of flow lead to fast propagation of flame inside the combustion chamber and improve the knock performance of engine. To provide this technical object, the present subject matter explains the intake air manifold with a ramp shape tumble generating structure (RSTGS).
[0025] Fig. 4 illustrates cross section view of assembly of combustion cylinder and the intake air manifold with tumble generating device, in accordance with the present subject matter. The engine assembly 400 has combustion chamber 401, an intake air manifold 402, air intake port 403, intake valve 404, air exhaust port 405 and a Ramp Shape Tumble Generating Structure (RSTGS) 406. The intake air manifold 402 has a plurality of air runners. The number of air runners depends on the number of cylinders in the internal combustion engine. Generally, the plurality of air runner is in cylindrical pipe shape. The plurality of air runners supplies fresh air to its corresponding combustion chamber 401. The plurality of air runners are connected to the air intake port 403 which transfers the supplied air to the combustion chamber 401. The intake air manifold 402 is provided with a Ramp Shape Tumble Generating Structure (RSTGS) 406 to change the air flow cross-section. The Ramp Shape Tumble Generating Structure (RSTGS) 406 is provided at the end and before joint of the air intake port 403 and the intake air manifold 402. The Ramp Shape Tumble Generating Structure (RSTGS) 406 is provided inside the intake air manifold 402 at the end towards the air intake port 403. The Ramp Shape Tumble Generating Structure (RSTGS) 406 changes the air flow cross-section to generate the air flow stream so that air enters in the combustion chamber 401 from top of the intake valve 404 face and move along the cylinder axis and generate high level of tumble when piston moves up and creates high velocity vertex to create turbulence in combustion chamber during combustion and increase the flame propagation speed to avoid knocking in the combustion chamber 401. The Ramp Shape Tumble Generating Structure (RSTGS) 406 is an inclined structure. Base of the Ramp Shape Tumble Generating Structure (RSTGS) 406 starts from the air runner and goes upto end surface of the air runner towards the air intake port 403. The Ramp Shape Tumble Generating Structure (RSTGS) 406 blocks the base opening area of the air runner and allows air to pass from the top end into the air intake port 403. The Ramp Shape Tumble Generating Structure (RSTGS) 406 can be solid ramp structure inside the air runner of the intake air manifold 402. Further, the Ramp Shape Tumble Generating Structure (RSTGS) 406 can be achieved by using a plate placed at an inclined angle at end of the intake air manifold 402. The Ramp Shape Tumble Generating Structure (RSTGS) 406 has an inclined angle in rang of 10o to 70o,, preferably in range 10o to 40o. Further, detailed and impact of the Ramp Shape Tumble Generating Structure (RSTGS) 406 is given in figure 7. The Ramp Shape Tumble Generating Structure (RSTGS) 406 can be integrated with the intake air manifold 402 during molding process. Further, the inclined angle of the Ramp Shape Tumble Generating Structure (RSTGS) 406 can be optimized as per requirements and
[0026] During Suction and compression stoke, the Intake air manifold having Ramp Shape Tumble Generating Structure (RSTGS) 504 (406 in figure 4) to change the air flow cross-section to generate the air flow stream as shown in red color, referring to fig. 5b. The Ramp Shape Tumble Generating Structure (RSTGS) 504 increases velocity of air vertex at the top portion of the intake port 505 and air enters through the top 506 of the intake valve 502 in the combustion chamber. As shown in figure 5b, below air velocity is higher on one side of cylinder and when piston in compression stoke move from bottom dead center to top dead center BDC to TDC it strikes the air vortex and flow vortex of circular shape generate along the axis perpendicular to cylinder axis. This high level of vertex creates turbulence in cylinder which in turn makes flame propagation faster to avoid knocking in combustion chamber. Fig. 5a and fig. 6a shows the air flow direction in the combustion chamber in existing systems.
[0027] Referring to fig. 7, the objective of the present subject matter is to reduce engine knocking for high Compression ratio (CR) application while increasing pumping loss by minimum possible value as indicated in Pressure Volume (PV) diagram. Increased Tumble improves the combustion speed, Low end torque, and anti-knocking performance, which in turn helps to increase the Compression ratio (CR) of engine.
[0028] With the increased CR engine brake thermal efficiency also increases. But increased knock tendency with high CR needs to be taken care by increasing combustion speed/tumble. On increasing the ramp angle of the Ramp Shape Tumble Generating Structure (RSTGS), tumble and hence turbulence increases which expands both loops though not in direct proportion.
[0029] Loop 1 is work done by engine :--- Useful work
[0030] Loop 2 is pumping loss in engine breathing:--- Energy waste
[0031] To maximize efficiency expansion of useful work (loop 1) needs to be higher than waste energy (loop 2).
[0032] Therefore for a particular application based on maximum usage area of an engine, ramp angle can be optimized to achieve best trade-off for expansion of loop1 with respect to loop2. Further, the range of the ramp angle is in 10o to 60o, preferably in range of 10o to 22o.
[0033] The present subject matter provides several advantages over the existing solutions and technologies. The cost of providing tumble generation device/plate in intake air manifold is low. Further, the Ramp Shape Tumble Generating Structure (RSTGS) can be made of plastic material because of low temperature of intake air manifold compare to intake port. Further, Ramp Shape Tumble Generating Structure (RSTGS) can be made integrated with the intake air manifold. By providing the tumble generation plate/device in intake air manifold, there is smaller loss of Coefficient of discharge as compared to prior art with lower cost. The present subject matter increases the knocking resistance of engine. Better fuel economy and emission performance is also achieved. Further, flow of air improves power and torque output of engine due to lower knocking tendency.
[0034] The term “vehicle” as used throughout this detailed description and in the claims refers to any moving vehicle that is capable of carrying one or more human occupants and is powered by any form of energy. The term “vehicle” is a motor vehicle which includes, but is not limited to: cars, trucks, vans, minivans, hatchback, sedan, MUVs, and SUVs.
[0035] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0036] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

We claim:

1. An intake air manifold (402) for an internal combustion engine to improve tumble generation in combustion chamber (401), the intake air manifold (402) comprising:
a plurality of air runner for allowing passage of air to the internal combustion engine through air intake port (403);
a ramp shape tumble generating structure (RSTGS) (406) is provided at end of each of the plurality of air runner to change air flow cross section to generate tumble inside the combustion chamber (401) of the internal combustion engine.
2. The intake air manifold (402) as claimed in claim 1, wherein the ramp shape tumble generating structure (406) is integrated with the plurality of air runners of the intake air manifold (402).
3. The intake air manifold (402) as claimed in claim 1, wherein inclination angle of the ramp shape tumble generating structure (406) is in range of 10o to 70o.
4. The intake air manifold (402) as claimed in claim 1, wherein inclination angle of the ramp shape tumble generating structure (406) is in range of 10o to 25o.
5. The intake air manifold (402) as claimed in claim 1, wherein the ramp shape tumble generating structure (406) is made of same material as of the intake air manifold (402).
6. The intake air manifold (402) as claimed in claim 1, wherein the ramp shape tumble generating structure (406) is provided at base of the air runner.
7. The intake air manifold (402) as claimed in claim 1, wherein inclined surface of the ramp shape tumble generating structure (406) starts from base of the air runner and goes to end of the air runner.
8. The intake air manifold (402) as claimed in claim 1, wherein one end of the ramp shape tumble generating structure (406) reduces opening of the circular/elliptical air runner towards intake port by filling opening of the air runner.
9. The intake air manifold (402) as claimed in claim 1, wherein the ramp shape tumble generating structure (406) increases the air velocity of air vertex at the top portion of intake port and the air enters through the top of intake valve in the combustion chamber (401).