FIELD OF INVENTION:
The present subject matter described herein, relates to an intake port structure, and, in particular to, an intake port structure for enhancement of turbulence intensity in combustion chamber of an internal combustion engine by improving tumble.
BACKGROUND AND PRIOR ART:
Generally, more attention has been given to various fluid mechanical approaches relating to techniques for determining configurations of intake ports and, in particular, the configurations of portions of the ports in close proximity to valve seat. Such configurations are one of the most important and decisive factors governing the flow pattern of intake air in cylinders. Typically, various efforts have been made to configure the intake port in order to produce a swirl in a plane parallel to the axis of the cylinder and a vertical "tumble" in a plane perpendicular to an axis of a combustion chamber in the internal combustion engine.
[003] Fig. 1 and 2 illustrate general structure of intake port with combustion chamber. As shown in the figure 1, the intake port structure has an inlet air passageway and a pair of first and second intake ports 101, 102 branching from the inlet air passageway toward first and second intake valve openings 105, 106. Further, a first valve and a second valve 103, 104 are slidably arranged in the first and the second intake valve openings 105, 106 to open and close the first and the second intake valve openings 105, 106 allow passage of air fuel mixture in the combustion chamber 107. Furthermore, stems 103a, 104a of the first valve and the second valve 103, 104 slides through stem guide portions in the intake port structure. Further, a fuel injector 108 is arranged at the joint of the first and second intake port 101, 102 to inject the fuel in the air flow towards the first and second intake valve. The intake port structure has a throat portion that connects the first and the second intake port 101, 102 with the first and the second intake valve openings 105, 106.
[004] In the existing prior art discloses an intake port to produce an enhanced tumble, such that the intake port is designed to be directed to and meet the outlet opening into the combustion chamber at a small angle. The intake port is further designed to have an approximately straight center line intersecting the axis of an intake valve and a cross-section which is enlarged toward a location at which a tumble is produced.
[005] Another existing prior art provides an intake port structure for a cylinder head of an internal combustion engine which has no increase in resistance to the flow of intake air at a transitional throat portion and enables determination of a center line so as to direct intake air flow in a desired direction.
[006] Based on the simulation study carried out by 3-D CFD simulations, it has been find out that variations in the intake port orientation, edge separation position and top profile angles are found out responsible for tumble improvement.
[007] There is a need in the art to modify the structure and to optimize the parameters of the intake port structure to improve the in-cylinder turbulence which highly influences the combustion process and the overall engine efficiency.
OBJECTS OF THE INVENTION:
[008] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed herein below.
[009] The principal objective of the present invention is to increase the turbulence intensity inside the combustion chamber that has a significant importance to accelerate burning rate of air-fuel mixture thereby increasing the thermal efficiency.
[0010] Another object of the present invention is to enhance exhaust gas recirculation (EGR) tolerance of internal combustion engine.
[0011] Another object of the present invention is to reduce the cyclic variability.
[0012] Yet another object of the present invention is to Increase the thermal efficiency (TE) by enabling higher compression ratio (CR) operation.
[0013] These and other objects and advantages will become more apparent when reference is made to the following description and accompanying drawings.
SUMMARY OF THE INVENTION:
[0014] This summary is provided to introduce concepts related to intake port structure of internal combustion engine. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0015] The present subject matter relates to an intake port structure for enhancement of turbulence intensity in an internal combustion engine. The intake port structure includes an inlet air passageway and a pair of first and second intake ports that is branching from the inlet air passageway toward first and second intake valve openings. The first and the second intake ports define upper wall and bottom wall divided by port center line. Further, a first valve and a second valve are slidably arranged in the first and the second intake valve openings to open and close the first and the second intake valve openings to allow passage of air fuel mixture. The intake port structure has a throat portion that bent from the linear port center line toward the valve openings. The throat portion curves with a radius sufficiently small to have no effect on directivity of intake air flow. The throat portion is provided in between the first and the second intake port and the first and the second intake valve openings. The throat portion connects the first and the second intake port with the first and the second intake valve openings. The intake port structure has a flow separation edge to guide flow of air toward the front side of the intake valve to generate tumble motion inside cylinder.
[0016] In an aspect, the intake port structure defines top and side profile angles, and valve angle (?) that plays vital role for enhancement of tumble.
[0017] In an aspect, the intake port structure has a fish belly shape at the bottom wall before starting of the throat portion.
[0018] In an aspect, the intake port structure defines a port side profile angle (?) that is aligned with the exhaust pentroof, so that maximum charges can flow without any re- circulation/restriction.
[0019] In an aspect, the intake port structure defines top profile angle (a & ß) that is nearly perpendicular to crank axis which provides equally distributed flow from front of the intake valve. The side and top profiles are optimized as per current mass production line for smooth charge flow to the cylinder.
[0020] 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
[0021] 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:
[0022] Fig. 1 illustrates a general structure of intake port structure;
[0023] Fig. 2 illustrates conventional diagram of a side profile of intake port structure;
[0024] Fig. 3 illustrates a side profile of intake port structure consisting port side angle, valve angle, fish belly shape, and flow separation edge, in accordance with the present subject matter;
[0025] Fig. 4 illustrates a top profile angle of the intake port structure, in accordance with an embodiment of the present subject matter;
[0026] Fig. 5a illustrates a side view of base intake port showing medium velocity area to generate medium tumble, in accordance with an embodiment of the present subject matter;
[0027] Fig. 5b illustrates side view of optimized intake port showing high velocity area to generate tumble, in accordance with an embodiment of the present subject matter;
[0028] Fig. 6a illustrates top view of base intake port showing flow leaking from back side of the intake valve, in accordance with an embodiment of the present subject matter;
[0029] Fig. 6b illustrates top view of optimized intake port showing maximum flow from front side of intake valve, in accordance with an embodiment of the present subject matter; and
[0030] Fig. 7 illustrates Simulation calculated tumble and Mass Flow Rate (MFR) comparison of Base and Optimized design of intake ports, in accordance with an embodiment of the present subject matter.
[0031] 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:
[0032] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
[0033] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0034] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a",” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0035] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0036] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0037] 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.
[0038] In spark-ignition (SI) type internal combustion engine (ICE), optimized geometry of the intake port contributes to generation of first tumble peak to provide in-cylinder turbulence which highly influences the combustion process and therefore the overall engine efficiency improves. Turbulence level in the combustion chamber (CC) mainly depends on the tumble motion development during the intake phase due to intake port geometry, which realizes the rotating flow structure of the incoming charge. The vortex inside cylinder perseveres during the compression stroke by optimized combustion chamber and piston bowl shapes near to the firing top dead Centre (fTDC). This helps to increase turbulence in the combustion chamber, just when the spark ignites and combustion starts. This minimizes the delay in start of combustion (SOC), high flame growth-rate and excellent combustion stability with reduced cycle to cycle variation. Mainly port’s top, side profiles angles, and valve angle with respect to port angle play vital role for enhancement of tumble for intake port.
[0039] High tumble intake port support incoming charge to generate high tumble motion inside the combustion chamber. Turbulence kinetic energy (TKE) is conserved by piston bowl during the compression phase of engine near the spark plug area, which enhances the burning rate of charge. The enhancement of turbulence intensity with Intake port design, inside the combustion chamber has a significant role, which improve exhaust gas recirculation (EGR) tolerance Hot/cold EGR and reduce the cyclic variability. Further, it increases the thermal efficiency (TE) by enabling higher compression ratio (CR) operation.
[0040] Fig. 3 illustrates structure of intake port with optimized parameters to improve tumble in the combustion chamber, in accordance with an embodiment of the present subject matter. In the fig. 3 only one intake port is visible, however description explain position of other port as well. Further, two intake ports are visible in fig. 4. The intake port structure 200 includes an inlet air passageway and a pair of first and second intake ports 201, 202 branching from the inlet air passageway toward first and second intake valve openings 205, 206. Each of the first and the second intake ports 201, 202 defines a port center line 201g along complete length of the intake port structure 200. The first and the second intake ports 201, 202 has upper wall 201e, 202e and bottom wall 201d, 202d defined along the port center line 201g. The bottom wall 201d, 202d is closer to combustion chamber as compared to the top wall 201e, 202e. The intake port structure 200 further includes a first valve 203 and a second valve 204 that are slidably arranged in the first and the second intake valve openings 205, 206 to open and close the first and the second intake valve openings 205, 206. The first valve 203 and the second valve 204 has stem 203a, 204a respectively that slides in the stem guide portions 201a, 202a of the first and the second intake port 201, 202.
[0041] The intake port structure 200 defines a throat portion 201b, 202b that is provided in between the first and the second intake port 201, 202 and the first and the second intake valve openings 205, 206. The throat portion 201b, 202b is bent portion. The throat portion 201b, 202b can be part of the intake port structure 200 or it can be part of combustion chamber. The throat portion 201b, 202b connects the first and the second intake port 201, 202 with the first and the second intake valve openings 205, 206. The throat portion201b, 202b curves with a radius sufficiently small to have no effect on directivity of intake air flow.
[0042] Generation of Tumble inside combustion chamber strongly depends upon the following key parameters of the intake port structure of internal combustion engine.
[0043] As shown in the fig. 3, a port side profile angle (?) is defined in between port center line 201g of the first and the second intake port 201, 202 and horizontal axis (X). The side profile angle (?) is important for direct flow of fresh air inside the cylinder to enhance tumble motion. The port side profile angle (?) is aligned with the exhaust pentroof, so that maximum charges can flow without any re- circulation/restriction. The side profile angle (?) is in range of 10°~30° angle along with 15° is the best angle.
[0044] Referring to fig. 2, the bottom wall 201d, 202d of the first and the second intake port 201, 202 has a fish belly shape 201f before the throat portion 201b, 202b to direct flow towards front side of the intake valve 204, 205 to generate tumble motion inside cylinder. Similarly, the bottom wall 201d, 202d of the first and the second intake port 201, 202 is provided with an edge portion 201c, 202c before the throat portion 201b, 202b or before bending portion of the intake port structure 200 to direct flow towards front side of the intake valve 204, 205 to generate tumble motion inside cylinder. The fish belly shape 201f and the edge portion 201c (it can be referred as flow separation edge portion 201c) improve flow separation and reduce counter tumble flow from rear end of the intake valve. For better tumble in the combustion chamber, it is ideal to allow more air flow or air fuel mixture from front end of the intake valve.
[0045] Referring to fig. 4, the intake port 201, 202 defines a port top profile angles (a and ß) in between the port centreline 201g and cylinder line 208 or crank axis 208. For better delivery of air fuel mixture at frontal end of the intake valves, the top profile angle (a) is in range of 80°~120°, however best results are achieved when the port top profile angle (a) is nearly perpendicular, i.e., 88o to 92o or 90o to the crank axis 208 to provide equally distributed flow from front end of the intake valves 203, 204. Further, the port top profile angle (ß) is in range 70°~100° and 90° is the best suitable angle for optimized design, . The port top profile angle (ß) helps to transfer the port flow straight inline from port entry, i.e., inlet passage to deliver equal frontal flow to both intake valves 203, 204.
[0046] As shown in the fig. 2, the intake port structure 200 defines a valve angle (?) in between the cylinder bore center line 207 and center line 205a, 206a of valve openings 205, 206. The valve angle (?) is in range of 5°~30° angle along with 15° is the best angle.
[0047] For testing, a base intake port structure is optimized as per the inventive parameters, such as fish belly shape, flow separation edge, port top profile angles, port side profile angle, and valve angle. Further, the flow separation edge and the fish belly shape improve the tumble creation. Furthermore, the side profile angle and the top profile angles are optimized as per current mass production line for smooth charge flow to the combustion chamber. The present intake port structure 200 is optimized using inventive parameters for the PFI gasoline engine to balance the conflicting requirement of better Tumble and higher MFR.
[0048] Fig. 5a and 5b shows comparison of base intake port structure with the present optimized intake port structure in respect of tumble generation. As shown in figure 5a, counter tumble is strong and front tumble 504 is medium. There is no sharp flow separation edge as indicated by 501 in the base intake port structure hence high flow of fresh charge as indicated by 502 is flowing from the back of intake valve to generate counter tumble. Leaking of charge from the back of the intake valve reduces flow strength from the front of the intake valve. Therefore, the intake port structure without flow separation edge and fish belly shape creates medium turbulence generation inside the cylinder as indicated by 503. Referring to fig. 5b, most of the intake charge as indicated by 504a flow from front of the intake valve to generate tumble. Further, addition of flow separation edge 501a does not allow the flow to go inside the cylinder from the back side of the intake valve which create counter-tumble inside the cylinder during the suction stroke. Therefore, the cylinder has high turbulence generation as indicated by 503a inside. As indicated by 502a, there is no or less flow (air fuel mixture) from back side of the valve.
[0049] Fig. 6a and 6b shows comparison of base intake port structure with the present optimized intake port structure in respect of leakage of flow from back side of the intake valve. To have better tumble generation, it is required to have less or no flow from back side of the intake valve. As shown in fig. 6a, strength of flow as indicated by 602 from front of the intake valve is not strong. Even flow is not uniformly distributed over intake inner seat diameter. There is flow from the back of the intake valve which generate counter-tumble. Referring fig. 6b, the most intake flow as indicated by 602a is coming from front of intake valve which is equally distributed around the intake valve. There is no flow from the back of the intake valve as indicated by 601a which generally generate counter-tumble. Equal distribution of incoming charge on the intake valve seat helps to generate high tumble intensity in Y-axis to avoid restriction/damping of flow with the cylinder wall. A plane at half of diameter of the cylinder (D/2) is taken to see symmetry of charge at half of the cylinder bore.
[0050] Fig. 7 illustrates calculated tumble and MFR comparison of Base and Optimized design of intake ports. Based on the simulation result comparison base structure and optimized structure of intake port, the optimized intake port structure has improvements in tumble generation and MFR as 41% and 4% respectively in simulation.
[0051] In the actual testing of the optimized intake port structure, highest level of Tumble is achieved by keeping almost same flow co-efficient. The optimized structure of intake port demonstrates an outstanding balance of high tumble generation with negligible drop in flow coefficient (Optimized port on boundary curve). This allows improvement of Brake Thermal Efficiency (BTE) without a drop in Wide Open Throttle (WOT) performance.
[0052] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0053] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

We claim:
1. An intake port structure (200) for improvement in tumble generation in an internal combustion engine, the intake port structure (200) comprising:
an inlet air passageway and a pair of first and second intake ports (201, 202) branching from the inlet air passageway toward first and second intake valve openings (205, 206), the first and the second intake ports (201, 202) defines upper wall (201e, 202e) and bottom wall (201d, 202d) along port center line (201g);
a first valve and a second valve (203, 204) are slidably arranged in the first and the second intake valve openings (205, 206) to open and close the first and the second intake valve openings (205, 206), where stem (203a, 204a) of the first valve and the second valve (203, 204) slides through stem guide portions (201a, 202a); and
a throat portion (201b, 202b) provided in between the first and the second intake port (201, 202) and the first and the second intake valve openings (205, 206), the throat portion (201b, 202b) connects the first and the second intake port (201, 202) with the first and the second intake valve openings (205, 206);
characterized in that
an edge portion (201c) provided at bottom wall (201d, 202d) of the first and the second intake port (201, 202) along the intake port axis (Z) before the throat portion (201b, 202b) to guide air flow toward front side of the first valve and the second valve (203, 204).
2. The intake port structure (200) as claimed in claim 1, wherein the bottom wall (201d, 202d) has a fish belly shape (201f, 202f) before the throat portion (201b, 202b).
3. The intake port structure (200) as claimed in claim 1, wherein a valve angle (?) between central axis (205a, 206a) of the first and second intake valve openings (205, 206) and cylinder bore center line (207) is in range of 5°~30°, with preferable angle is 15°.
4. The intake port structure (200) as claimed in claim 1, wherein the first and the second intake port (201, 202) define top profile angles (a and ß) that are perpendicular to crank axis (A).
5. The intake port structure (200) as claimed in claim 4, wherein the top profile angle (a) is in range 80°~120°, preferably in range 88o to 92o.
6. The intake port structure (200) as claimed in claim 4, wherein the top profile angle (ß) is in range 70°~100°, preferably in range 88o to 92o.
7. The intake port structure (200) as claimed in claim 1, wherein a port side profile angle (?) is defined between port center line (201g) of the first and the second intake port (201, 202) and horizontal line (X) is in range 10°~30°, with preferable angle is 15°.
8. The intake port structure (200) as claimed in claim 1, wherein the first and the second intake ports (201, 202) are positioned on one side of the cylinder line.