CN112912597B

CN112912597B - Internal combustion engine and method for manufacturing the same

Info

Publication number: CN112912597B
Application number: CN201980069727.6A
Authority: CN
Inventors: V·贾亚佐提约翰逊; B·玛尼; H·维奈查德坎特; S·巴拉尼拉姆
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2018-10-30
Filing date: 2019-10-27
Publication date: 2023-05-23
Anticipated expiration: 2039-10-27
Also published as: EP3874134A1; CN112912597A; WO2020089930A1; BR112021008498A2; CO2021005588A2

Abstract

The present subject matter provides an internal combustion engine (101) for a vehicle (100). The internal combustion engine comprises at least one cylinder head (203). The at least one cylinder head comprises at least one intake port (301). A combustion chamber is provided for receiving intake air from a fuel supply through at least one intake port. At least one exhaust port (304) is provided that is capable of exhausting combusted gases from the chamber to the atmosphere through an exhaust pipe (200) of the vehicle. The at least one exhaust port has an upstream portion (310) adjacent the combustion chamber and a downstream portion (307) adjacent the inlet opening (201) of the exhaust pipe. The downstream portion of the exhaust port has a first cross-sectional Area (APT) that is substantially equal to or substantially smaller than a second cross-sectional Area (APE) of the inlet opening of the exhaust pipe.

Description

Internal combustion engine and method for manufacturing the same

Technical Field

The present subject matter relates to an internal combustion engine for a two-or three-wheeled vehicle, and more particularly to an exhaust system of an internal combustion engine.

Background

Generally, in motor vehicles, an Internal Combustion (IC) engine includes an intake system for supplying air fuel to the IC engine. An exhaust system connects an internal combustion engine to a muffler of a vehicle. In general, exhaust gas generated in a combustion chamber of an IC engine is discharged to the atmosphere. In motor vehicles, the exhaust port of an IC engine is connected to an exhaust pipe of an exhaust system, so that burned gas can be discharged into the atmosphere. Generally, the location of the exhaust port depends on the particular orientation in which the engine is mounted to the vehicle, which presents challenges to the layout and packaging associated therewith. Moreover, in order to effectively reduce the emission of exhaust gas discharged from the engine, it is important to place the catalytic converter as close to the exhaust port as possible. However, in most motor vehicles, optimal positioning of the catalytic converter also becomes a challenge, mainly due to layout constraints of the motor vehicle.

Disclosure of Invention

Drawings

The detailed description is described with reference to the accompanying drawings. The same reference numbers will be used throughout the drawings to refer to similar features and components.

FIG. 1 depicts a right side view of an exemplary two-wheeled vehicle according to an embodiment of the present subject matter.

Fig. 2 shows a right side view of the internal combustion engine including its exhaust system according to the embodiment shown in fig. 1.

Fig. 3 (a) shows a cross-sectional front view of a cylinder head assembly of an internal combustion engine according to an embodiment of the present subject matter.

FIG. 3 (b) shows a cross-sectional view of the exhaust port of the engine shown in FIG. 3 (a) taken at section Z-Z according to one embodiment of the present subject matter.

FIG. 3 (c) shows a cross-sectional view of the exhaust port of the engine shown in FIG. 3 (a) taken at section XX-XX, according to one embodiment of the present subject matter.

FIG. 3 (d) shows a cross-sectional view of the exhaust port of the engine shown in FIG. 3 (a) taken at section YY-YY according to one embodiment of the present subject matter.

Fig. 4 (a) shows a cross-sectional view of an exhaust system of an internal combustion engine according to a first embodiment of the present subject matter.

Fig. 4 (b) shows a cross-sectional view of an exhaust system of an internal combustion engine according to a second embodiment of the present subject matter.

Fig. 4 (c) shows a cross-sectional view of a third exemplary exhaust system (400 c) of an internal combustion engine (101) according to a third embodiment of the present subject matter.

Fig. 4 (d) shows a cross-sectional view of a fourth exemplary exhaust system (400 d) of an internal combustion engine (101) according to a fourth embodiment of the present subject matter.

Fig. 5 illustrates a cross-sectional view of an exhaust port of an internal combustion engine according to another embodiment of the present subject matter.

Fig. 6 (a) depicts a characteristic curve of exhaust gas temperature in an exhaust system of an internal combustion engine according to an embodiment of the present subject matter.

Fig. 6 (b) shows a cross-sectional view of a conventional exhaust system, depicting the intersection of an exhaust port and an exhaust pipe.

Fig. 6 (c) shows a cross-sectional view of an exhaust system depicting the intersection of an exhaust port and an exhaust pipe, in accordance with an embodiment of the present subject matter.

Fig. 7 depicts a characteristic curve of engine torque of an internal combustion engine according to an embodiment of the present subject matter.

Fig. 8 depicts a method of manufacturing a cylinder head according to an embodiment of the present subject matter.

FIG. 9 illustrates a cross-sectional view of the cylinder head assembly of the present subject matter depicting the intake and exhaust ports passages with the integral sand core disposed therein.

Detailed Description

In general, internal combustion engines having a four-stroke cycle are popular. The four-stroke cycle begins with the intake stroke and ends with the exhaust stroke. The air-fuel mixture is compressed and then combusted during a compression stroke due to combustion of the air-fuel mixture, resulting in a power stroke. Combusted gases are transferred from the cylinder head to an exhaust system. In general, the performance of a vehicle depends on various parameters, including the air-fuel mixture supplied during intake. However, in some cases, the performance of the engine also depends on the nature of the exhaust gas being conveyed. For example, contaminants generated in the combustion chamber during combustion affect the lubrication performance in the combustion chamber. This in turn increases friction, thereby affecting the performance of the vehicle.

In addition, an upstream end of the exhaust pipe is connected to an exhaust port of the cylinder head. The muffler is disposed either toward one lateral side of the vehicle or along the center of the vehicle and generally downstream of the engine, with the exhaust pipe being arranged therebetween so as to be able to discharge the exhaust gas toward the downstream end of the vehicle. The upstream end of the exhaust pipe connected to the cylinder head assembly includes a curved portion connected to the exhaust port, which is typically disposed on the forward side of the cylinder head or on the downward side of the cylinder head. This generally requires complicated wiring of the exhaust pipe having a bent portion. In addition, an effective seal at the junction or interface of the exhaust pipe and the cylinder head assembly places high demands on the profile and geometric accuracy of the interface components, which is critical to ensuring a leak-proof system. Moreover, since the cylinder head is close to the combustion chamber, the operating temperature (thermal load) near the cylinder head is high, which further increases the challenge of having an effective engagement at the interface. The manufacture of curved tubes is also complex and difficult, involving manufacturing challenges such as spring back effects of materials, bending wrinkles, warpage, etc. To achieve a curved profile, it is often necessary to perform a multi-stage process, making it not economical to meet geometric accuracy.

Furthermore, any gaps that occur at the interface with the cylinder head assembly may result in undesirable leakage, performance loss, noise, contamination, and poor durability and service life of the entire powertrain as a whole. In addition, the curved portion also affects the flow of exhaust gases therethrough, which affects the performance of the engine. Moreover, the presence of the curved portion affects the flow of exhaust gas, thereby generating resistance, thereby adversely affecting performance. In addition, exhaust gases may cause undesirable exhaust noise. In addition, since the curved portion undergoes wall portion thinning on the outer surface of the exhaust pipe at the curved portion, the structural strength of the exhaust pipe is low at the curved portion on the exhaust pipe. This can lead to cracking or failure of the bent portion. Furthermore, the combination of manufacturing stresses and thermal loads on the exhaust pipe tends to cause rust, especially at the upstream end portion, resulting in failure of the exhaust pipe. It is also common that the complex shape of the exhaust pipe makes disassembly and repair of the engine assembly cumbersome.

In general, a conventional engine is provided with a cylinder head in which an exhaust port is provided on the opposite side from an intake port. In the case of ports having a circular cross-section, the diameter of the exhaust port and the diameter of the intake port are determined according to engine configuration and performance requirements. Alternatively, in the case of a port having a non-circular cross-section, such as an oval shape, the cross-sectional area of the exhaust port and the cross-sectional area of the intake port are considered. For example, the higher the swept volume of the engine, the larger the diameter or cross-sectional area of the port for drawing a large amount of air-fuel mixture into or out of the combustion chamber of the engine will be. Typically, the diameter or cross-sectional area of the intake port of the engine is greater than the diameter or cross-sectional area of the exhaust port. This is mainly due to the fact that: during the intake stroke, a large amount of air-fuel mixture must be inhaled without at least a too large pressure difference between the cylinder head and the atmosphere. On the other hand, when the pressure difference between the cylinder head and the atmosphere is large, exhaust gas from the combustion chamber is discharged from the exhaust port. In this process, it is also important to maximize combustion efficiency to produce maximum power and ensure minimum emissions.

For this purpose, the cylinder heads conventionally known are provided with one or more exhaust ports, the diameter or cross-sectional area of which increases gradually from the valve seat to the port outlet. Typically, the exhaust pipe has a configuration in which an end portion thereof connected to the exhaust port is flared, i.e., an end portion of the exhaust pipe connected to the exhaust port region is flared to be connectable to a mounting flange of the exhaust port. However, the diameter or cross-sectional area of the exhaust pipe at its interface with the outlet of the exhaust port is substantially smaller than the diameter or cross-sectional area of the outlet of the exhaust port. Such a configuration is necessary to achieve desired performance characteristics of the engine, such as an increase in low-speed torque (low end torque), an increase in exhaust gas velocity, without impeding the flow rate of the exhaust gas.

In general, providing flares on the joint surface of exhaust pipes made of sheet metal involves a cumbersome machining process, and the flares produced also lack uniformity. Furthermore, in such known exhaust systems, where the diameter or cross-sectional area of the exhaust port is progressively larger from the valve seat to the junction surface of the exhaust pipe and where the diameter or cross-sectional area of the exhaust pipe is substantially smaller than the outlet diameter or cross-sectional area of the exhaust port, such known exhaust systems often suffer from various other problems such as those described in the preceding paragraph, such as the lack of an effective seal at the junction or interface of the exhaust pipe and the cylinder head assembly, which places high demands on the profile and geometric accuracy of the interface components, thereby preventing the implementation of a leakage prevention system even though the flow of exhaust gas and desired engine performance are generally achieved.

Typically, to minimize emissions, the exhaust system is provided with one or more catalytic converters to achieve the desired emission control. For best results, such catalytic converters must be light-off in advance to improve the performance output of the catalytic converter. Accordingly, conventionally known exhaust systems designed with the ability to achieve desired engine performance characteristics may still be inadequate to achieve optimal emission control. Furthermore, in the known art, closed loop control systems with oxygen or lambda sensors are provided to further enhance emission control. However, such known systems suffer from high volumetric flows of exhaust gases, such that they must operate with poor low speed torque and other constituents, as outlined in the subsequent paragraphs.

The diameter or cross-sectional area of the exhaust port of a typical exhaust system increases gradually up to the interface with the exhaust pipe, and the diameter or cross-sectional area of the exhaust pipe at the interface is substantially smaller than the outlet diameter or cross-sectional area of the exhaust port, so that a typical exhaust system tends to reduce the velocity of exhaust gas reaching the one or more catalytic converters disposed downstream of the exhaust pipe. This is because the enlarged external cross section of the exhaust port and the corresponding interface of the exhaust pipe have a diameter or cross-sectional area that is substantially smaller than the outlet diameter or cross-sectional area of the exhaust port, which tends to increase the pressure and flow rate, but may result in a reduction in the velocity of the exhaust gas. The decrease in exhaust gas velocity means that the temperature of the exhaust gas reaching the one or more catalytic converters also decreases, which in most cases affects the early light-off of the catalytic converter.

Various attempts have been made in the past by providing stepped exhaust passages in the exhaust ports. However, such attempts have not achieved the desired effect of improving the efficiency of the catalytic converter without compromising the performance of the engine at certain operating points and without affecting the torque and power of the engine. For example, attempts have been made in the past to reduce exhaust resistance and improve the exhaust process by forming helically twisted exhaust ports, which results in the combusted exhaust gas being helically circulated prior to discharge. However, this configuration is more feasible in two-stroke engines without valves. Moreover, attempting such a configuration in a four-stroke engine is expensive and it is not possible to produce the desired performance of the engine. In view of improving the overall output of the engine, attempts have also been made to increase the exhaust emission efficiency. In view of achieving this, the vent is configured to include a combination of an inward expansion region and an external venturi unit. However, to achieve increased flow, this configuration of the exhaust ports may result in increased pressure of the exhaust gas and decreased outlet velocity. In contrast, the object of the present subject matter is to increase the velocity of the exhaust gases, for which purpose a pressure drop is produced, the flow losses that are to be caused being compensated by the profile of the exhaust opening, the chamfer with reduced cross section, the length of the land provided on the outlet face of the exhaust opening of the present subject matter.

Accordingly, there is a need for an internal combustion engine whose exhaust system addresses the above-identified shortcomings and others of the prior art. At the same time, the exhaust system should be capable of achieving optimal emission control, improving performance, and providing reduced resistance to exhaust flow while not affecting engine torque and power. Furthermore, the assembly and disassembly of the exhaust pipe should be less cumbersome for maintenance or other purposes.

Accordingly, the present subject matter provides an exhaust system for an internal combustion engine that includes an exhaust system that is capable of improving performance of the engine at a particular operating point.

Furthermore, the present subject matter ensures that the problems faced in the prior art with respect to the flaring of the exhaust pipe are overcome, which results in a lack of consistency in the geometric accuracy of the interface components, thereby impeding the implementation of a leak-proof system. The present subject matter is directed to achieving desired consistency in the design of an exhaust system by greatly reducing design variations. In order to achieve the above objects, the present subject matter provides an exhaust system in which flow characteristics are transferred from an exhaust pipe and incorporated in an exhaust port without compromising torque and power requirements of an engine.

In one embodiment, the present subject matter provides for an increase in exhaust gas velocity to achieve early light-off of a catalytic converter disposed downstream of an exhaust pipe, particularly in its cold state.

In one embodiment, the present subject matter provides an internal combustion engine for a two-wheeled or three-wheeled vehicle. In particular, the present subject matter provides a four-stroke internal combustion engine. More specifically, the present subject matter provides a four-stroke internal combustion engine having a single cylinder. Internal combustion engines typically include at least one cylinder head. The at least one cylinder head includes at least one intake port. A combustion chamber is provided that receives intake air from a fuel supply through at least one intake port. The cylinder head is also provided with at least one exhaust port capable of exhausting combusted gases from the chamber to the atmosphere through an exhaust pipe of the vehicle. The engine assembly includes at least one spark plug.

The at least one exhaust port has an upstream portion adjacent the combustion chamber and a downstream portion adjacent the inlet opening of the exhaust pipe. The first diameter or cross-sectional area of the downstream portion of the exhaust port is substantially equal to the second diameter or cross-sectional area of the inlet opening of the exhaust pipe at the junction of the exhaust pipe and the exhaust port.

In one embodiment, the exhaust port of the present subject matter has a middle portion disposed adjacent to a downstream portion. In addition, the second diameter or cross-sectional area of the inlet opening of the exhaust duct is about 1.10 to 1.20 times the first diameter or cross-sectional area of the downstream portion of the exhaust outlet. In one embodiment, the exhaust port has a first region connecting the upstream portion and the intermediate portion of the exhaust port and a second region connecting the downstream portion and the intermediate portion.

In one embodiment, the intermediate portion has a contoured design of the exhaust port, e.g., a reduced cross-section provided at a predetermined angle of 3 ° to 20 °. The upstream diameter or cross-sectional area of the reduced cross-section is substantially greater than the downstream diameter or cross-sectional area.

Further, in one embodiment, the length of the second region of the vent is approximately in the range of between 2.5mm and 4mm, and the first diameter is approximately in the range of between 15mm and 25 mm.

In one embodiment, the exhaust pipe comprises at least one catalytic converter unit arranged at a predetermined distance from the exhaust port, for example at a distance between about 175mm and 300mm from the reduced cross section of the exhaust port. The exhaust pipe further includes an oxygen sensor disposed between the exhaust port and the catalytic converter unit. In one embodiment, the oxygen sensor is arranged substantially closer to the catalytic converter unit, for example at a distance of between about 15mm and 20mm upstream of the catalytic converter unit.

In one embodiment, the intermediate portion of the exhaust port receives at least one secondary air injection outlet conduit, and in another embodiment, the exhaust port is provided with an exhaust gas recirculation conduit instead of at least one secondary air injection outlet conduit.

Furthermore, in one embodiment, the present subject matter provides an internal combustion engine for a two-wheeled or three-wheeled vehicle. The internal combustion engine typically includes at least one cylinder head. The at least one cylinder head includes at least one intake port. A combustion chamber is provided that receives intake air from a fuel supply through at least one intake port. The cylinder head is also provided with at least one exhaust port capable of exhausting combusted gases from the combustion chamber to the atmosphere through an exhaust pipe of the vehicle. The at least one exhaust port has an upstream portion adjacent the combustion chamber and a downstream portion adjacent the inlet opening of the exhaust pipe. The first diameter or cross-sectional area of the downstream portion of the exhaust port is substantially smaller than the second diameter or cross-sectional area of the inlet opening of the exhaust pipe at the junction of the exhaust pipe and the exhaust port. In one embodiment, the second diameter or cross-sectional area of the inlet opening of the exhaust pipe is about 1.2 to 1.5 times the first diameter or cross-sectional area of the downstream portion of the exhaust port.

Further, in another embodiment, the present subject matter provides an internal combustion engine for a two-wheeled or three-wheeled vehicle. Internal combustion engines typically include at least one cylinder head. The at least one cylinder head includes at least one intake port. A combustion chamber is provided that receives intake air from a fuel supply through at least one intake port. The cylinder head is also provided with at least one exhaust port capable of exhausting combusted gases from the chamber to the atmosphere through an exhaust pipe of the vehicle. The at least one exhaust port has an upstream portion adjacent the combustion chamber and a downstream portion adjacent the inlet opening of the exhaust pipe. The first diameter or cross-sectional area of the downstream portion of the exhaust port is substantially smaller than the second diameter or cross-sectional area of the inlet opening of the exhaust pipe at the junction of the exhaust pipe and the exhaust port. The exhaust port has a middle portion disposed adjacent the downstream portion. The exhaust port has a first region connecting an upstream portion and an intermediate portion of the exhaust port and a second region connecting a downstream portion and the intermediate portion. The intermediate portion has a reduced cross-section provided at a predetermined angle in the range of 3 ° to 20 °.

The present subject matter also provides a method of manufacturing a cylinder head of an internal combustion engine having at least one exhaust port. The method comprises the following steps: a monolithic sand core is formed having a stepped diameter or cross-sectional area prior to at least a predetermined distance ranging between 6mm and 12mm from a downstream portion of the exhaust port. After this step, the locating elements are formed beyond the stepped diameter or cross-sectional area of the monolithic sand core and received by the metal core.

In one embodiment, the forming includes integrally forming the at least one exhaust port with the at least one intake port and the combustion chamber. In addition, the method includes the step of Low Pressure Die Casting (LPDC).

In one embodiment, the present subject matter provides a cylinder head wherein the diameter or cross-sectional area of the exhaust port is substantially closer to the diameter or cross-sectional area of the exhaust pipe, but does not exactly match the diameter or cross-sectional area of the outlet portion of the exhaust port. In one embodiment, the present subject matter relates to forming a stepped portion in a casting of an exhaust port. At the exit point of the port, the end toward the port is modified over a width of about 6mm to 12 mm. The length of the second region of the exhaust port is approximately in the range between 2.5mm and 4mm to ensure that the minimum platform required for the mounting of the exhaust pipe to the port is maintained after machining, except for any production variations that may occur.

In addition, the sheet metal flaring process lacks consistency, which is compensated for by the casting process including forming a unitary sand core for the vent, which achieves the desired consistency, thereby reducing any variation in the process, diameter or tolerance of + -0.2 mm corresponding to cross-sectional area. Furthermore, the casting process involving the cylinder head forming the sand core enables the desired surface finish to be achieved. The present subject matter achieves a ratio of the diameter or cross-sectional area of the outlet of the portion of the port to the diameter or cross-sectional area of the inlet of the exhaust pipe of 1:1 to 1:1.3, taking into account any manufacturing variations, which helps achieve the desired increase in catalytic converter efficiency without compromising engine performance.

In one embodiment, the cross-sectional area of the port at the valve seat or the corresponding diameter of the port at the valve seat is approximately 20mm. Thus, the diameter of the port increases from the point where the port is near the valve seat until it reaches the port intermediate portion, after which it decreases at the outlet portion of the exhaust port. This helps achieve the desired outlet flow restriction, thereby increasing exhaust gas velocity. Further, in one embodiment, the increase in gas velocity is proportional to the area of the outlet area of the exhaust port achieved thereby, as the reduced cross section preceding the outlet portion of the exhaust port causes a reduction in the diameter or cross sectional area of the outlet portion of the exhaust port.

On the basis of the above description, in one embodiment, the nozzle action due to the reduced cross-section provided towards the end of the exhaust port of the present subject matter contributes to an increase in exhaust gas velocity. This phenomenon supports the rapid movement of exhaust gas to CAT at higher volumetric flows without causing the exhaust gas temperature to drop. Thus, faster light-off of CAT is achieved.

Further, the nozzle action due to the decreasing cross section toward the end of the exhaust port transfers exhaust gas from the exhaust port to the exhaust pipe rapidly and toward the end of the exhaust pipe to the muffler. This results in the lean gas in the combustion chamber being rapidly removed for the next combustion cycle. Thus, the volumetric efficiency is improved. This also contributes to better breathing of the engine and improves its low speed torque. This in turn improves the performance of the engine at the desired operating point.

In addition, well known exhaust systems are provided with Secondary Air Injection (SAI) outlets at the exhaust ports to improve the conversion of exhaust gases such as NOx, HC and CO. Thus, providing an SAI outlet at the reduced cross-section of the vent helps to enhance suction due to the vacuum created at the reduced cross-section. Furthermore, this ensures that more oxygen is available at the catalytic converter arranged downstream of the exhaust pipe. This can improve the efficiency of the catalytic converter and the performance of the engine.

The arrow in the upper right corner in the figure indicates the direction with respect to the vehicle, wherein arrow F indicates the forward direction, arrow R indicates the backward direction, arrow UP indicates the upward direction, arrow DW indicates the downward direction, arrow RH indicates the right side, and arrow LH indicates the left side.

Fig. 1 shows a two-wheeled vehicle (100), which is an exemplary motor vehicle, having an IC engine (101) arranged vertically. Preferably, the IC engine (101) is a single cylinder type IC engine. The two-wheeled vehicle comprises a front wheel (110), a rear wheel (103), a schematically shown frame member (102), a fuel tank (121) and a seat (106). The frame member (102) includes a head pipe (111), a main pipe (not shown), a down pipe (not shown), and a seat rail (not shown). The head pipe (111) supports a steering shaft (not shown), and two telescopic front suspensions (114) (only one shown) are connected to the steering shaft through a lower bracket (not shown). Two telescopic front suspensions (114) support the front wheels (110). The upper part of the front wheel (110) is covered by a front fender (115) mounted to the lower part of a telescopic front suspension (114) at the end of the steering shaft. The handle bar (108) is fixed to an upper bracket (not shown) and can rotate to both sides. A headlight (109), a sun visor shield (not shown), and an instrument cluster (not shown) are disposed at an upper portion of the head pipe (111). The down tube may be located forward of the IC engine (101) and extend obliquely downward from the head tube (111). The main pipe is located above the IC engine (101) and extends rearward from the head pipe (111). The IC engine (101) is mounted at the front through a down tube, and the rear of the IC engine (101) is connected at the rear portion of the main tube.

A fuel tank (121) is mounted on a horizontal portion of the main pipe (112). The seat rail is coupled to the main tube and extends rearward to support the seat (106). A rear swing arm (not shown) is connected to the frame member (102) to swing vertically, and a rear wheel (103) is connected to a rear end of the rear swing arm (118). Typically, the rear swing arm is supported by a single rear suspension (117) (as shown in this embodiment), or by two suspensions on either side of the two-wheeled vehicle. A tail light unit (not shown) is arranged at the end of the two-wheeled vehicle at the rear of the seat (106). An armrest (105) is also arranged at the rear part of the seat guide rail. A rear wheel (103) disposed below the seat (106) is rotated by a driving force of the IC engine (101) transmitted from the IC engine (101) through a chain transmission (116). A rear fender (127) is disposed above the rear wheel (103).

Fig. 2 shows a right side view of the internal combustion engine (101) comprising its exhaust system according to the embodiment shown in fig. 1. In one embodiment, an internal combustion engine (101) includes a cylinder head assembly (210), the cylinder head assembly (210) having a cylinder head (203) and a cylinder head cover (202) mounted atop the cylinder head (203). In one embodiment, the internal combustion engine (101) is a single cylinder engine. More specifically, in one embodiment, the internal combustion engine (101) is a four-stroke internal combustion engine (101). In another alternative embodiment, the internal combustion engine (101) may include more than one cylinder head (203), or include multiple cylinders. In one embodiment, the cylinder head (203) of the present subject matter includes one or more ports (not shown in this figure). For example, an exhaust port (not visible in the figure) of the internal combustion engine (101) enables exhaust gas generated by combustion of an air-fuel mixture occurring in a combustion chamber (not shown) of the internal combustion engine (101) to be discharged. The gas discharged from the exhaust port is conveyed through an exhaust pipe (200) of an exhaust system of the internal combustion engine (101). In one embodiment, the exhaust pipe (200) comprises an inlet opening (201), which inlet opening (201) is connected to an exhaust port (not visible in this figure) of the internal combustion engine (101) to enable smooth travel of the exiting exhaust gases.

In one embodiment, a cylinder head (203) of an internal combustion engine (101) is mounted on top of a cylinder block (204), the cylinder block (204) together with a crankcase (205) allowing up and down movement of pistons (not visible in this figure) of the internal combustion engine (101) for optimal combustion of an air-fuel mixture entering the combustion chamber. In one embodiment, the exhaust pipe (200) of the present subject matter includes a first curved portion (208) adjacent to the inlet opening (201) and a second curved portion (209) distal from the first curved portion (208). In one embodiment, the distance between the first curved portion (208) and the second curved portion (209) is defined by the vertical space between the exhaust port and the ground clearance (C) shown in fig. 1 of the vehicle (100). In one embodiment, an engine (101) includes at least one spark plug. In one embodiment, the vehicle (100) is a saddle-ride type vehicle. The distance between the first curved portion (208) and the second curved portion (209) also depends on, for example, the diameters of the front wheel (not shown in this figure) and the rear wheel (not shown in this figure) and the front-rear track between the two wheels.

In one embodiment, the exhaust pipe (200) includes at least one catalytic converter unit (206). Most particularly, the exhaust pipe (200) comprises at least one catalytic converter unit (206) substantially closer to the exhaust port of the cylinder head, particularly the catalytic converter unit (206) is arranged between a first curved portion (208) and a second curved portion (209) of the exhaust pipe (200). In one embodiment, the at least one catalytic converter unit (206) is a pre-catalytic converter or an auxiliary catalytic converter, which is arranged upstream of the main catalytic converter in the exhaust system of the present subject matter. In an alternative embodiment, a main catalytic converter (not shown) is disposed within a muffler assembly (130) of the exhaust system of the present subject matter. In one embodiment, the closer the catalytic converter unit (206) is to the exhaust port, the higher the efficiency of the catalytic converter unit (206). In one embodiment, the catalytic converter unit is arranged at a predetermined distance ranging between approximately 175mm to 225mm from a tapered portion (not visible in this figure) of the exhaust port.

In one embodiment, the oxygen sensor (207) is arranged substantially closer to and upstream of the catalytic converter unit (206). For example, in one embodiment, the oxygen sensor (207) is disposed at a distance of about 15mm to 20mm upstream of the catalytic converter unit (206).

Fig. 3 (a) shows a cross-sectional front view of a cylinder head assembly (210) of an internal combustion engine (101) according to one embodiment of the present subject matter. In one embodiment, the cylinder head assembly (210) of the present subject matter has at least one intake port (301), the intake port (301) allowing an air-fuel mixture to enter a combustion chamber (not shown). In one embodiment, an intake port (301) is seated on an intake valve seat (302) at a junction where an intake valve is disposed at an intake valve arrangement opening (303) on a cylinder head assembly (210). In one embodiment, the cylinder head assembly (210) includes at least one exhaust port (304) disposed on the other side of the intake port (301). In another embodiment, the cylinder head assembly (210) may include more than one exhaust port (304). In one embodiment, the exhaust port (304) is seated on an exhaust valve seat (305) of an exhaust valve (306). In one embodiment, the portion of the exhaust port (304) proximate the exhaust valve (305) is an upstream portion (310). In one embodiment, the diameter of the upstream portion (310) of the exhaust port (304) is about 20mm. In one embodiment, the middle portion (308) of the exhaust port (304) divides the exhaust port (304) into two regions, namely, a first region (311) that extends between the upstream portion (310) and the middle portion (308) of the exhaust port (304) more than three-quarters of the entire exhaust port (304), and a second region (312) that extends between the middle portion (308) and the downstream portion (307) of the exhaust port (304) substantially equal to or less than one-quarter of the entire exhaust port (304). In one embodiment, the intermediate portion (308) is disposed at a distance of about 6mm to 12mm from the downstream portion (307) of the exhaust port (304).

In one embodiment, the intermediate portion (308) of the vent (304) includes a reduced cross-section (309). In one embodiment, the reduced cross-section (309) may include a tapered section. In one embodiment, the reduced cross-section (309) has a predetermined angle ranging from 3 ° to 20 °, such as a taper angle ranging from 3 ° to 20 °. For example, in one embodiment, the reduced cross-section (309) has an upstream diameter or cross-sectional area that is substantially greater than a downstream diameter or cross-sectional area. In one embodiment, the second region (312) of the exhaust port (304) has a length approximately in the range of 2.5mm to 4mm, which ensures that a minimum platform is maintained that is required for mounting an exhaust pipe (not visible in this figure) to the port (304). Furthermore, in an alternative embodiment, the cylinder head assembly (210) includes two exhaust ports that are seated on two exhaust valve seats of two respective exhaust valves. In this embodiment, the two exhaust ports meet upstream of the reduced cross-section (309) and thereafter abut the exhaust pipe in a similar manner to the previous embodiment involving a single exhaust port (304).

FIG. 3 (b) shows a cross-sectional view of the exhaust port (304) of the engine shown in FIG. 3 (a) taken at a Z-Z cross-section according to one embodiment of the present subject matter. FIG. 3 (c) shows a cross-sectional view of the exhaust port (304) of the engine shown in FIG. 3 (a) taken at section XX-XX, according to one embodiment of the present subject matter. FIG. 3 (d) shows a cross-sectional view of the exhaust port (304) of the engine shown in FIG. 3 (a) taken at section YY-YY according to one embodiment of the present subject matter. In one embodiment, the diameter or cross-sectional area of the vent at section Z-Z (which is at least the first region of the vent (304)), as shown in FIG. 3 (b), is substantially smaller than the diameter or cross-sectional area of the vent at section XX-XX (which is at least the intermediate portion (308) of the vent (304)), as shown in FIG. 3 (c). Similarly, the diameter or cross-sectional area of the vent (304) at section XX-XX, which is at the intermediate portion (308) of the vent (304), is greater than the diameter or cross-sectional area of the vent at section YY-YY, which is taken at the second region (312) of the vent (304), as shown in fig. 3 (d). According to another embodiment, the profile of the vent may be any non-circular cross-section, such as a D-shape as shown in FIG. 3 (b), and similarly, the vent shape at the intermediate portion (308) and downstream portion (307) may also be a non-circular cross-section. In such embodiments, the equivalent cross-sectional area of the exhaust port at the upstream portion (310) is greater than the equivalent cross-sectional area of the exhaust port (304) at the intermediate portion (308), and the cross-sectional area of the exhaust port (304) at the downstream portion (307) is less than the cross-sectional area of the intermediate portion (308). Such a specific configuration enables higher exhaust gas speeds, increased volumetric efficiency without compromising the flow of exhaust gas.

Fig. 4 (a) shows a cross-sectional view of a first exemplary exhaust system (400 a) of an internal combustion engine (101) according to one embodiment of the present subject matter. In one embodiment, a first exemplary exhaust system (400 a) includes a first cross-sectional area (A) of a downstream portion (307) of an exhaust port (304) _PT ) The first cross-sectional area is substantially equal to the second cross-sectional area (A) of the inlet opening (201) of the exhaust pipe (200) _PE )。

In one embodiment, the second cross-sectional area (A) of the inlet opening (201) of the exhaust pipe (200) _PT ) Is a first cross-sectional area (A) of a downstream portion (307) of the vent (304) _PT ) I.e. the two cross-sectional areas are substantially equal but not matched. In one embodiment, the exhaust pipe (200) is attached to the exhaust port (304) by means of a mounting flange (401) adapted to be mounted on a mounting area of a downstream portion (307) of the exhaust port (304). Furthermore, in one embodiment, the intermediate portion (308) of the vent (304) includes a reduced cross-section (309). In one embodiment, the reduced cross-section (309) may include a tapered cross-section (309-1). In one embodiment, the tapered cross section (309-1) has a predetermined angle of 3 ° to 20 °, such as a cone angle in the range of 3 ° to 20 °.

Fig. 4 (b) shows a cross-sectional view of a second exemplary exhaust system (400 b) of an internal combustion engine (101) according to one embodiment of the present subject matter. In one embodiment, the second exemplary exhaust system (400 b) includes a first cross-sectional area (A) of a downstream portion (307) of the exhaust port (304) _PT ) The first cross-sectional area is substantially equal to the second cross-sectional area of the inlet opening (201) of the exhaust pipe (200)Product (A) _PE ). Furthermore, in one embodiment, the intermediate portion (308) of the vent (304) includes a reduced cross-section (309). In one embodiment, the reduced cross-section (309) may include a smooth merged cross-section (309-2). In one embodiment, the smooth merged cross-section (309-2) has a predetermined angle of 3 ° to 20 °.

Fig. 4 (c) shows a cross-sectional view of a third exemplary exhaust system (400 c) of an internal combustion engine (101) according to one embodiment of the present subject matter. In one embodiment, the second exemplary exhaust system (400 b) includes a first cross-sectional area (A) of a downstream portion (307) of the exhaust port (304) _PT ) The first cross-sectional area is substantially smaller than the second cross-sectional area (A) of the inlet opening (201) of the exhaust pipe (200) _PE )。

In one embodiment, the second cross-sectional area (A) of the inlet opening (201) of the exhaust pipe (200) _PE ) Is a first cross-sectional area (A) of a downstream portion (307) of the vent (304) _PT ) About 1.2 to 1.5 times of the total number of the first and second parts. In one embodiment, the exhaust pipe (200) is attached to the exhaust port (304) by a mounting flange (401) adapted to be mounted on a mounting area of a downstream portion (307) of the exhaust port (304). Furthermore, in one embodiment, the intermediate portion (308) of the vent (304) includes a reduced cross-section (309). In one embodiment, the reduced cross-section (309) may include a tapered cross-section (309-1). In one embodiment, the tapered cross section (309-1) has a predetermined angle of 3 ° to 20 °, such as a cone angle in the range of 3 ° to 20 °.

Fig. 4 (d) shows a cross-sectional view of a fourth exemplary exhaust system (400 d) of an internal combustion engine (101) according to one embodiment of the present subject matter. In one embodiment, a fourth exemplary exhaust system (400 d) includes a first cross-sectional area (A) of a downstream portion (307) of an exhaust port (304) _PT ) The first cross-sectional area is substantially smaller than the second cross-sectional area (A) of the inlet opening (201) of the exhaust pipe (200) _PE ). Additionally, in one embodiment, the intermediate portion (308) of the vent (304) includes a reduced cross-section (309). In one embodiment, the reduced cross-section (309) may include a smooth merged cross-section (309-2). In one embodiment of the present invention, in one embodiment, The smooth merging cross section (309-2) has a predetermined angle of 3 ° to 20 °.

Fig. 5 illustrates a third exemplary exhaust system (500) depicting a cross-sectional view of an exhaust port (304) of an internal combustion engine according to another embodiment of the present subject matter. In one embodiment, the intermediate portion (308), more specifically, the reduced cross-section (309) of the exhaust port (304), is provided with an entry point (502) for receiving at least one secondary air injection outlet conduit (501). In one embodiment, the provision of a secondary air injection outlet conduit (501) at the reduced cross section (309) of the exhaust port (304) helps to improve the suction due to the vacuum created at the reduced cross section (309). Furthermore, this ensures that more oxygen is available at a catalytic converter (not shown in this figure) arranged downstream of the exhaust pipe (200). This may improve the efficiency of the catalytic converter and the performance of the engine at the desired operating point.

Fig. 6 (a) shows a first characteristic curve (600) of exhaust gas temperature in an exhaust system of an internal combustion engine according to one embodiment of the present subject matter. In one exemplary embodiment, the first characteristic curve (600) depicts two variation curves, a first temperature curve (601) of an engine with a conventional cylinder head and a second temperature curve (602) of an engine with an improved cylinder head as described in the present subject matter. In one embodiment, the temperature of the exhaust gas passing through the exhaust port (304) and into the exhaust pipe (200) has a steep drop with the first temperature profile (601) of a conventional cylinder head assembly as compared to the second temperature profile (602) with the improved cylinder head assembly as described in the present subject matter. The reason for this steep drop in exhaust gas temperature is the improved structure of the exhaust port (304) at its outlet where it is connected to the exhaust pipe (200). In the case of a conventional cylinder head, the diameter or cross-sectional area of the exhaust port increases gradually from the valve seat until the downstream portion of the exhaust port (304). In contrast, the exhaust port (304) of the cylinder head assembly (210) of the present subject matter involves an initial increase in cross-sectional area and a decrease in cross-sectional area toward the end of the exhaust port (304), as shown in fig. 3 (a), 3 (b), 3 (c), and 3 (d). In addition, conventional exhaust systems also include an inlet opening of the exhaust pipe (200) having a diameter or cross-sectional area that is smaller than the diameter or cross-sectional area of the exhaust port (304) at a downstream portion (307) thereof. In this case, the velocity of the exhaust gas discharged from the exhaust port (304) does not exhibit a significant increase as it travels within the exhaust pipe passage. For example, in the case of a conventional cylinder head, at about 200mm from the exhaust port (where the catalytic converter is disposed), the temperature of the exhaust port is reduced by approximately 12% to 14% as compared with the case of the configuration of the improved cylinder head of the present subject matter. This sharp drop in exhaust gas temperature is due to a loss of velocity in the exhaust stream. The effect of a conventional exhaust system on the output exhaust speed is further described with reference to fig. 6 (b) and 6 (c) provided below.

Fig. 6 (b) shows a cross-sectional view of a conventional exhaust system (600 (b)) depicting the intersection of an exhaust port and an exhaust pipe. Meanwhile, fig. 6 (c) shows a cross-sectional view of an exemplary exhaust system (600 (c)) depicting the intersection of an exhaust port and an exhaust pipe, according to an embodiment of the present subject matter. As can be seen from the conventional exhaust system (600 (b)), the cross-sectional area of the conventional exhaust pipe (200 ') suddenly decreases at the junction surface of the exhaust port (304'). This abrupt change (603') in cross-sectional area tends to create turbulence in the exhaust flow. In contrast, as seen in fig. 6 (c), the subject exhaust system (600 (c)) provides a reduction in cross-sectional area within the exhaust port (304), which not only helps to increase exhaust gas velocity from that point, but also ensures a smoother transition of the exhaust gas flow, thereby preventing any turbulence in the exhaust gas flow due to the reduction in cross-sectional area toward the downstream portion (307) of the exhaust port (304).

Furthermore, the reduction of the cross-sectional area of the downstream portion (307) of the exhaust port (304) towards the exhaust system (600 (c)) of the present subject matter ensures that the high pressure within the exhaust port (304) is fully utilized to achieve an effective increase in exhaust gas velocity without any loss. In contrast, any increase in exhaust gas velocity that may be observed in a conventional exhaust system (600 (b)) may experience a pressure drop at the exhaust pipe (200'), which may affect an effective increase in exhaust gas velocity.

On the other hand, the improved cylinder head of the subject matter has when exhaust gases from the combustion chamber approach the downstream portion of the exhaust port (304)With a reduced cross-section. The reduced cross section, in particular the cone angle provided, ensures an increased velocity of the exhaust gas flowing through the reduced cross section. Furthermore, in the case of the exemplary exhaust system of the present subject matter, the diameter or cross-sectional area of the inlet opening of the exhaust pipe (200) varies between 1.10 times and 1.20 times the diameter or cross-sectional area of the downstream portion of the exhaust port (304), this configuration of the exhaust port and exhaust pipe interface, in combination with the reduced cross-section and the angle of the reduced cross-section, ensures that the velocity of the exhaust gas in the exhaust pipe passageway is not significantly reduced. For example, the catalytic converter unit (206) is arranged in the exhaust pipe (200) at a distance of about 175mm to 220mm from said reduced cross section of the exhaust port (304). The speed of the exhaust gas reaching the subject catalytic converter unit (206) is sufficiently high that the temperature of the exhaust gas is at least higher than in the case of a conventional cylinder head

This allows the catalytic converter unit (206) to light off in advance, which in turn increases the efficiency of the catalytic converter unit (206).

Fig. 7 depicts a second characteristic curve (700) of engine torque of an internal combustion engine according to an embodiment of the present subject matter. In one embodiment, the second characteristic curve (700) depicts a first torque curve (701) of an engine having a conventional cylinder head and a second torque curve (702) of an engine having a modified cylinder head as described in the present subject matter. In one embodiment, the first torque curve (701) has a significantly lower torque (Nm) at low engine speeds (rpm) than the second torque curve (702). This significant increase in engine torque at low engine speeds is achieved in the improved cylinder head of the present subject matter due to the specific profile design of the exhaust ports (304), such as the reduced cross section (309). The increase in exhaust gas velocity at the reduced cross section of the exhaust port (304) ensures an improvement in the low speed torque of the engine and it also improves the performance of the engine at certain specific operating points.

In one embodiment, the nozzle action caused by the tapered profile section toward the end of the exhaust port (304) creates backpressure or restriction during the valve overlap period. This back pressure helps the exhaust gas effectively push the piston down and helps improve the low speed torque of the engine. Further, the above low-speed torque is achieved without damaging the medium-speed and high-speed torques. In the high speed region of the engine, the nozzle action due to the tapered profile section of the exhaust port (304) helps to transfer exhaust gas quickly to the muffler body (130) without any restrictions on the next cycle, thereby enhancing the power of the engine.

FIG. 8 depicts an exemplary method (800) of manufacturing a cylinder head according to one embodiment of the present subject matter. In one exemplary embodiment, a method (800) of manufacturing a cylinder head of the present subject matter includes a first step (805) of forming a unitary sand core. The step of forming a unitary sand core (805) includes creating a sand core that is integral with the cylinder head along with one or more intake ports and one or more exhaust ports. In one embodiment, the sand core of the improved exhaust port of the present subject matter is integrally formed with the sand core of the cylinder head. In a second step (810), the method (800) includes providing a stepped diameter or cross-sectional area prior to an outlet or downstream portion of the exhaust port (304). The stepped diameter or cross-sectional area provided toward the end of the exhaust port (304) is such that the tapered profile portion of the exhaust port (304) is formed with the desired features that enable an increase in exhaust gas velocity without causing performance degradation in terms of low speed torque degradation of the engine. In a third step (815), the method (800) includes forming a locating element for a monolithic sand core that exceeds the stepped diameter or cross-sectional area. The locating elements so formed ensure that the sand core is held stably during casting and that metal is filled in the exhaust port throat after the stepped diameter or cross-sectional area.

In a fourth step (820), the method (800) includes receiving a locating element formed in the sand core beyond a stepped diameter or cross-sectional area of the vent hole (304) by a metal core that is held toward the end of the sand core. In a fifth step (825), the method (800) includes a flow of material, e.g., in one exemplary embodiment, the material is an aluminum alloy. The aluminum alloy is flowed into a casting containing the sand core. In a sixth step (830), the method (800) includes low pressure molding (LPDC) an aluminum alloy in the casting. Further, in a seventh step (835), the method (800) includes removing the gate or vent from the casting after performing the low pressure die casting for a predetermined time and under predetermined operating conditions. Further, in an eighth step (840), the method (800) includes cleaning the cast component; the cleaning includes operations such as scrubbing to remove unwanted edges and burrs from the cast part. In a ninth step (845), the method (800) includes heat treating the molded part for a predetermined time and under predetermined operating conditions. Further, in a tenth step (850), the method (800) includes machining the cast cylinder head. Machining is performed to ensure that a desired ratio of cone angle to length of the exhaust port (304) is achieved at the second region connecting the intermediate and downstream portions. Achieving the desired ratio is important because it is critical to achieve the desired increase in exhaust gas speed without compromising performance characteristics (e.g., low speed torque and power).

FIG. 9 illustrates a cross-sectional view of the cylinder head assembly of the present subject matter depicting the intake and exhaust ports passages with the integral sand core disposed therein. In one embodiment, the cylinder head assembly (210) of the present subject matter is molded with the aid of a monolithic sand core formed therein. In one embodiment, an air scoop metal core (901) is provided to securely hold the underlying sand core during the above-described molding process. In one embodiment, an intake port sand core (903), an exhaust port sand core (904), and a combustion chamber sand core (905). In one embodiment, the intake, exhaust and combustion chamber sand cores (903, 904, 905) are glued to form the monolithic sand core. In one embodiment, the vent sand core (904) is provided with a stepped diameter or cross-sectional area (906) prior to the outlet portion of the vent (304). In one embodiment, the locating element (907) is formed beyond the stepped diameter or cross-sectional area (906) of the exhaust port (304), which ensures the necessary reduced cross-section for achieving an increase in exhaust gas velocity and improving low speed torque without compromising engine performance prior to forming the downstream portion of the exhaust port (304) in the molded cylinder head assembly (210). In one embodiment, the locating element (907) is formed on the vent metal core (902).

Many modifications and variations of the present subject matter are possible in light of the above disclosure, within the spirit and scope of the present subject matter.

List of reference symbols:

100. vehicle 305 exhaust valve seat

101. 306 exhaust valve of internal combustion engine

102. Downstream portion of exhaust port of frame member 307

103. Rear wheel

105. Intermediate portion of armrest 308

106. Seat 309 reduced cross-section

108. Tapered cross section of handlebar 309-1

109. Smooth merging cross section of headlight 309-2

110. Front wheel

111. Upstream of the exhaust port of header 310

114. Front suspension

115. First region of the exhaust port of the front fender 311

117. Second region of rear suspension 312 exhaust port

121. Fuel tank

130. Muffler body 400 (a) first exemplary exhaust system

200. Exhaust pipe

201. Inlet opening 400 (b) of exhaust pipe second exemplary exhaust system

202. Cylinder head cover

203. Cylinder head 401 mounting flange

204. Cylinder block A _EPT First cross-sectional area of exhaust port

205. Crankcase

206. Catalytic converter unit A _PE Second cross-sectional area of exhaust pipe

207. Oxygen sensor

208. First curved portion 500 of exhaust pipe third exemplary exhaust system

209. Second curved portion of exhaust pipe

210. Secondary Air Injection (SAI) outlet conduit for cylinder head assembly 501

301. Air inlet

302. Entry point for SAI outlet of intake valve seat 502

303. First characteristic curve of intake valve 600

304. Exhaust port

601. First temperature profile of engine with conventional cylinder head

602. Second temperature profile of engine with improved cylinder head

603. Abrupt change in cross-section

700. Second characteristic curve

701. First torque curve of engine with conventional cylinder head

702. Second torque curve of engine with improved cylinder head

800. Exemplary method of manufacturing a Cylinder head

805. First step of the exemplary method

810. Second step of the exemplary method

814. Third step of the exemplary method

815. Fourth step of the exemplary method

820. Fifth step of the exemplary method

825. Sixth step of the exemplary method

830. Seventh step of the exemplary method

835. Eighth step of the exemplary method

840. Ninth step of the exemplary method

845. Tenth step of the exemplary method

850. Eleventh step of exemplary method

901. Air inlet metal core

902. Exhaust port metal core

903. Air inlet sand core

904. Sand core of exhaust port

905. Combustion chamber sand core

906. Stepped diameter and cross-sectional area

907. Positioning element

Claims

1. An internal combustion engine (101) for a vehicle (100), comprising:

at least one cylinder head (203) of the cylinder head assembly (210),

the at least one cylinder head (203) comprises at least one intake port (301), and at least one spark plug;

the at least one intake port (301) is seated on an intake valve seat (302) at a junction where an intake valve is arranged at an intake valve arrangement opening (303) on the cylinder head assembly (210);

at least one exhaust valve (306);

the combustion chamber is arranged in the combustion chamber,

the combustion chamber receives intake air from a fuel supply through the at least one intake port (301); and

at least one exhaust port (304), said at least one exhaust port (304) being capable of being seated on an exhaust valve seat (305) of said exhaust valve (306),

the at least one exhaust port (304) is capable of exhausting combusted gases from the combustion chamber to the atmosphere through an exhaust pipe (200) of the vehicle (100),

The at least one exhaust port (304) has an upstream portion (310) adjacent the combustion chamber and a downstream portion (307) adjacent the inlet opening (201) of the exhaust pipe (200),

wherein,,

the at least one exhaust port (304) having an intermediate portion (308), the intermediate portion (308) being disposed adjacent the downstream portion (307),

wherein the downstream portion (307) of the exhaust port (304) has a first cross-sectional Area (APT) substantially equal to a second cross-sectional Area (APE) of the inlet opening (201) of the exhaust pipe (200), and

the intermediate portion (308) has a reduced cross-section (309) provided at a predetermined angle.

2. The internal combustion engine (101) according to claim 1, wherein,

the exhaust port (304) has a first region (311) and a second region (312), the first region (311) connecting an upstream portion (310) and the intermediate portion (308) of the exhaust port (304), the second region (312) connecting the downstream portion (307) and the intermediate portion (308).

3. The internal combustion engine (101) according to claim 1, wherein,

the reduced cross-section (309) includes a tapered cross-section (309-1), an upstream cross-sectional area of the tapered cross-section (309-1) being substantially larger than a downstream cross-sectional area.

4. The internal combustion engine (101) according to claim 1, wherein,

the reduced cross-section (309) comprises a smooth merged cross-section (309-2), an upstream cross-sectional area of the smooth merged cross-section (309-2) being substantially larger than a downstream cross-sectional area.

5. The internal combustion engine (101) according to claim 1, wherein,

the exhaust pipe (200) comprises at least one catalytic converter unit (206), the catalytic converter unit (206) being arranged at a predetermined distance from the exhaust port (304),

the at least one catalytic converter unit (206) is arranged at a predetermined distance ranging between 175mm and 300mm from the reduced cross section (309) of the exhaust port (304).

6. The internal combustion engine (101) according to claim 5, wherein,

the exhaust pipe (200) includes an oxygen sensor (207) arranged between the exhaust port (304) and the catalytic converter unit (206),

the oxygen sensor (207) is arranged substantially closer to the catalytic converter unit (206), and

the oxygen sensor (207) is arranged at a predetermined distance ranging between 15mm and 20mm upstream of the at least one catalytic converter unit (206).

7. The internal combustion engine (101) according to claim 5, wherein,

The intermediate portion (308) of the exhaust port (304) receives at least one secondary air injection outlet conduit (501).

8. A method (800) of manufacturing a cylinder head (203) of an internal combustion engine (101), the internal combustion engine (101) having at least one exhaust port (304), the method (800) comprising:

a first step (805) of forming a monolithic sand core (903, 904);

-a second step (810) of providing a stepped cross-sectional area (906) before at least a predetermined distance from a downstream portion (307) of the exhaust port (304);

-a third step (815) of forming a locating element (907) beyond the stepped cross-sectional area (906) of the monolithic sand core (903, 904); and

-a fourth step (820) of receiving the positioning element (907) of the monolithic sand core (903, 904) by a metal core (901, 902).

9. The method (800) of claim 8, wherein,

the first step (805) of forming the monolithic sand core (903, 904) includes integrally forming the at least one exhaust port (304) with at least one intake port (301) and a combustion chamber.

10. The method of claim 8, wherein,

the method (800) includes Low Pressure Die Casting (LPDC).

11. The method of claim 8, wherein,

The second step (810) includes providing (810) a stepped cross-sectional area before at least the predetermined distance ranging between 6mm and 12mm from the downstream portion of the exhaust port (304).

12. An internal combustion engine (101) for a vehicle (100), the internal combustion engine (101) comprising:

at least one cylinder head (203) of the cylinder head assembly (210),

the at least one cylinder head (203) comprises at least one intake port (301) and at least one spark plug;

at least one exhaust valve (306);

a combustion chamber for receiving intake air from a fuel supply through at least one intake port (301); and

at least one exhaust port (304), said at least one exhaust port (304) being seated on an exhaust valve seat (306) of said exhaust valve (305),

Wherein,,

wherein the downstream portion (307) of the exhaust port (304) has a first cross-sectional Area (APT) substantially smaller than a second cross-sectional Area (APE) of the inlet opening (201) of the exhaust pipe (200), and

13. The internal combustion engine (101) according to claim 12, wherein,

the second cross-sectional area (A) of the inlet opening (201) of the exhaust pipe (200) _PE ) Is the first cross-sectional area (A) of the downstream portion (307) of the exhaust port (304) _PT ) 1.2 to 1.5 times of (a).

14. The internal combustion engine (101) according to claim 12, wherein,

the second cross-sectional area (A) of the inlet opening (201) of the exhaust pipe (200) _PE ) Is the first cross-sectional area (A) of the downstream portion (307) of the exhaust port (304) _PT ) 1.10 to 1.20 times of (a).

15. An internal combustion engine (101) for a vehicle (100), the internal combustion engine (101) comprising:

at least one cylinder head (203) of a cylinder head assembly (210), the at least one cylinder head (203) comprising at least one intake port (301) and at least one spark plug;

The at least one intake port (301) is seated in an intake valve seat (302) at a junction where an intake valve is arranged at an intake valve arrangement opening (303) on the cylinder head assembly (210);

at least one exhaust valve (306);

a combustion chamber for receiving intake air from a fuel supply through at least one intake port (301);

at least one exhaust port (304), said at least one exhaust port (304) being seated on an exhaust valve seat (305) of said exhaust valve (306),

the at least one exhaust port (304) has an upstream portion (310) adjacent the combustion chamber and a downstream portion (307) adjacent the inlet opening (201) of the exhaust pipe (200), wherein,

-the downstream portion (307) of the exhaust port (304) has a first cross-sectional Area (APT) substantially smaller than a second cross-sectional Area (APE) of the inlet opening (201) of the exhaust pipe (200);

The exhaust port (304) has a first region (311) and a second region (312), the first region (311) connecting the upstream portion (310) and the intermediate portion (308) of the exhaust port (304), the second region (312) connecting the downstream portion (307) and the intermediate portion (308); and is also provided with