EP3519690A1

EP3519690A1 - An intake system for a two wheeled vehicle

Info

Publication number: EP3519690A1
Application number: EP17855117.2A
Authority: EP
Inventors: Vijaya BHASKAR ADIGA; Kothuru NARAYANA HARSHA; Damodaran PRAMOTH KUMAR; Maluvadu SUNDARAMAN ANANDKUMAR
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2016-09-30
Filing date: 2017-09-27
Publication date: 2019-08-07
Also published as: CN109891080A; MX2019003742A; EP3519690A4; CN109891080B; WO2018060874A1

Abstract

The present subject matter discloses an intake system for an internal combustion engine (101) comprising two inlet ports (210, 220) in its cylinder head (101b). The intake system comprises a fuel injector valve (201) mounted on a pipe intake (204) and configured to direct fuel inside the two intake ports (210,220). The fuel injection valve (201) is mounted to have a fuel injector axis (X-X) at a predetermined acute angle (Θ) with reference to a horizontal plane (Y-Y), and said fuel injector valve (201) mounted at a predetermined horizontal distance (a) between the tip of the fuel injection valve (201) and the cylinder head (101a). This ensures that, the fuel injected inside the two intake ports (210, 220) takes the shortest path with minimum wall wetting.

Description

FORM 2

AN INTAKE SYSTEM FOR A TWO WHEELED VEHICLE

TECHNICAL FIELD

[0001] The present subject matter relates generally to a two wheeled vehicle. More particularly, the present subject matter relates to the two wheeled vehicle having an intake system.

BACKGROUND

[0002] An Intake system plays a significant role in an internal combustion (IC) engine and affects driveability, provides increased mileage and to generates desired power and torque. Intake system comprises of pressurised pump, fuel injection valve, ECU, throttle valve, pipe intake, air cleaner and various sensors to provide input to the ECU. The fuel injection valve introduces fuel in metered quantity directly either inside the IC engine or inside the pipe intake in the form of a fuel spray formed by atomization of the fuel through a small nozzle under high pressure. Intake system having fuel injection has a lot of advantages like cleaner and complete combustion, minimal loss of fuel, better throttle sensitivity and prevent excess amount of fuel entering the IC engine. Overall, this improves IC engine performance and has better cold start characteristics. The location and orientation of fuel injection valve is very important as it provides advantages in terms of improved combustion, accessibility of the fuel injection valve and ease of connectivity of various inputs to the fuel injection valve. Typically, to improve combustion efficiency and to obtain desirable air fuel mixture combustion characteristics in the IC engine, the IC engine comprises a cylinder head having two inlet ports. In a two wheeled vehicle such as a straddle type motorcycle having cylinder head with two inlet ports, the mounting and placement of the fuel injection valve is a challenge. Mounting of the fuel injection valve in such two wheeled vehicles is difficult due to layout constraints and loss of fuel during fuel spray by fuel injection valve. Additionally, the direction of fuel spray from the fuel injection valve to the inlet port of the IC engine is important and the design of fuel spray path affects IC engine performance. In two wheeled vehicles having the cylinder head with two inlet ports has the attractive feature of increased mileage and fuel efficiency improved IC engine performance is of great importance. Hence, packaging and mounting of the fuel injection valve is challenging and various customer needs makes the vehicle layout compact as any additional change in layout will add to cost. In the present subject matter, the fuel injection valve is designed to be accommodated to alleviate the above mentioned drawbacks.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.

[0004] Fig. la. illustrates the side view of a two wheeled vehicle employing an embodiment of the present subject matter.

[0005] Fig. lb. illustrates the top view of the two wheeled vehicle employing the embodiment of the present subject matter.

[0006] Fig. 2a. illustrates the enlarged isometric view of the internal combustion engine and the intake structure according to the embodiment of the present subject matter.

[0007] Fig. 2b. illustrates the side view of a cylinder head of internal combustion engine according to the embodiment of the present subject matter.

[0008] Fig. 3. illustrates the cut sectional view of the internal combustion engine and the intake structure according to the embodiment of the present subject matter.

[0009] Fig. 4a. illustrates the side view of the throttle body, fuel injection system and pipe intake employing the embodiment of the present subject matter. [00010] Fig. 4b. illustrates the isometric view of the fuel injection system, fuel injection system and pipe intake according to the embodiment of the present subject matter.

[00011] Fig. 5a. illustrates an insulator pad disposed on the cylinder head pipe intake mounting face according the embodiment of the present subject matter.

[00012] Fig. 5b. illustrates the side view of the insulator pad according to the embodiment of the present subject matter.

[00013] Fig. 5c. illustrates the isometric view of the insulator pad according to the embodiment of the present subject matter.

DETAILED DESCRIPTION

[00014] Various features and embodiments of the present subject matter here will be discernible from the following further description thereof, set out hereunder. According to an embodiment, an internal combustion engine (IC) described here operates in four cycles. Such an IC engine is installed in a step through type two wheeled vehicle. It is contemplated that the concepts of the present invention may be applied to other types of vehicles within the spirit and scope of this invention. The detailed explanation of the constitution of parts other than the present subject matter which constitutes an essential part has been omitted at suitable places.

[00015] Supply of optimum air and fuel mixture is essential for proper combustion inside the IC engine. If the mixture is not proper (lean mixture or rich mixture) it leads to improper combustion which affects IC engine performance and leads to increase of exhaust emissions. Maintaining proper ratio of mixture of mixture of air and fuel is essential and varying this ratio and rate of supply based on IC engine real-time operational data improves the IC engine performance tremendously. An intake system can essentially be of two types namely, a fuel injection system and carburetor system. The fuel injection system electronically injects and controls the air fuel mixture based on certain parameters determined by various plurality of sensors. The carburetor mechanically controls the air fuel mixture based on the throttle applied by a rider of the two wheeled vehicle. For the IC engine to have smooth drivability, increased mileage, improved power and torque, the intake system and fuel injection system plays a significant role.

[00016] Generally, the intake system comprises an air cleaner, an intake passage, a throttle body, a fuel injection valve and a pipe intake. The air cleaner draws air from the atmosphere and filters it before supplying air to the downstream components. The intake passage directs the air flow from the air cleaner through a throttle body which comprises a venturi through which the air is throttled and a butterfly valve to control the rate of entry of air based on the throttle control by the rider. The throttled air is directed to a plurality of intake ports of the IC engine by the pipe intake. The plurality of intake ports forms the part of a cylinder head of the IC engine which directs air fuel mixture to a combustion chamber. The outlet of the plurality of intake ports is controlled by equal number of intake valves configured to be operably connected to open and close to match the IC engine four cycles. The fuel injection valve is disposed such that, fuel is sprayed to the throttled air in the pipe intake after throttling. The fuel injection valve introduces fuel in metered quantity directly either inside the IC engine or inside the pipe intake in the form of a fuel spray formed by atomization of the fuel through a small nozzle under high pressure. The fuel injection valve can be mounted on the throttle body or the pipe intake. There are various sensors which determine the IC engine running state and riding conditions and an electronic Control Unit (ECU) adjusts the air fuel mixture based on these inputs. There is a fuel pump which is configured to supply pressurized fuel to the fuel injector so that the fuel can be injected easily. The pressure help atomize the fuel at the tip of the fuel injection valve which comes out as a mist of fuel spray. The IC engine running state and riding conditions measured by different sensors are stored in the memory block of the ECU called maps. The ECU is programmed for certain preset modes and fuel delivery quantities when the values are of certain quantity, and the ECU determines how much fuel to deliver based on these quantities. The various sensors are throttle position sensor, idling sensor, crankshaft revolution sensor etc. [00017] Typically to improve fuel efficiency and obtain efficient combustion characteristics inside the combustion chamber the motion of air fuel mixture inlet inside the combustion chamber plays an important role and the combustion characteristics are affected depending on the type of air fuel mixture inlet. The type and direction of air fuel mixture inlet depends on the profile and geometry of the inlet port. It is desirable to obtain swirl motion of the air fuel mixture at lower ranges of engine revolutions and tumble motion of the air fuel mixture at higher engine revolutions. It is further desired that inlet motion of air fuel mixture has combined swirl and tumble motion due to which the IC engine is able to extract the combined advantages of both swirl motion and tumble motion at all ranges of engine revolutions. The swirl motion and tumble motion of the air fuel mixture cannot be achieved in single port. Hence, a two intake port cylinder head for an IC engine is known in prior art in which two different intake ports will assist air fuel mixture for swirl motion and tumble motion in each intake port. The port geometry (direction and curvature) are different which determines the direction of air fuel mixture entry to the combustion chamber. The swirl port opening is at the centre of cylinder head bore and tumble port opening is offset from the centre of the cylinder bore and placed beside one above the other.

[00018] Typically in a two-wheeled vehicle such as a straddle type motorcycle, it has a frame structure extending from the front to the rear direction comprising a head tube located in the front portion, a main tube extending horizontally from a head tube and a down tube extending downwards from the head tube. The main tube extends horizontally and curves downwards near the centre of the vehicle. A pair of side tubes is attached to the main tube which extends rearward. The IC engine is mounted at the below the main tube between the down tube and the downward portion of the main tube on the forward side of the vehicle. The IC engine is functionally connected to a rear wheel of the two wheeled vehicle by a final transmission system such as a sprocket and chain drive mechanism. A fuel tank is mounted on the front side of the vehicle on the main tube, and an air cleaner is located in rear of the downward portion of the main tube. For improving fuel efficiency and obtaining efficient combustion characteristics, it is desirable to have a cylinder head with two intake ports for such a two wheeled vehicle. For implementing fuel injection system in such vehicles as described above it is very essential to provide fuel spray to both the intake ports and in addition ensure fuel is injected as close to the intake port as possible, and the fuel spray path in each intake port should be such that wall wetting is minimized. Further, the fuel injection system must be easily accessible. A fuel injection system for such a cylinder head is challenging, mounting is difficult, lesser accessibility and difficult to accommodate it in the existing vehicle layout. Hence, in order to implement fuel injection system in such a two wheeled vehicle, various models of fuel injection valve mountings are proposed in art.

[00019] Typically, one solution is to provide two fuel injection valves to direct air fuel mixture into two different intake ports. Such designs have the drawbacks of use of additional fuel injection valves, increased complexity of mechanism and use of different ECU maps to control two fuel injection valves, and increased capacity of fuel pump. Replacing two fuel injection valves with single fuel injection valve is difficult due to inherent drawbacks of providing fuel spray to both the intake ports effectively. The vehicle layout constraints due to space limitations in various frame designs and vehicle layouts, makes the mounting and locating the fuel injection valve and throttle body in two wheeled vehicles such as one described in the preceding paragraphs a challenging task. The space provided between the main tube and the throttle body is less and hence the fuel injection valve cannot be accommodated to be part of the throttle body due to interference with the main tube. Additionally, such a single fuel injection valve would cause fuel wall wetting phenomenon due constrained locations which significantly affects fuel efficiency. Further, accommodating fuel injection valve on the pipe intake provides difficulty in accommodating the rubber hose from the fuel pump and is subjected to various bends and turns which reduces the fuel pressure significantly. Further, the wiring harness to fuel injection valve is difficult to route through the main tube due to improper location of fuel injection valve. The small length of the pipe intake further compounds the difficulty in suitably accommodating a single fuel injection valve. Additionally servicing and replacement is cumbersome and compact mounting make tool access difficult. The tool accessibility is difficult as the connecting member (such as fasteners) used to bind the fuel injection valve are not easy to access.

[00020] Hence, to obviate the limitations associated with the straddle type two wheeled vehicle as described above, the proposed subject matter discloses mounting and positioning of the fuel injection valve said fuel injection valve mounted on the pipe intake separated from the throttle body and mounted at an predetermined acute angle with reference to the horizontal plane and the distance between the tip of the fuel injection valve and the cylinder head is fixed to a predetermined value. The fuel injection valve is mounted on pipe intake in such a way that the fuel is sprayed directly on intake valve with minimal wall-wetting. The intake ports are separated till the end of a cylinder head intake mounting face. An insulator pad is disposed on the cylinder head intake mounting face to change and unify the directions of the both the intake ports in to one direction.

[00021] With the above design changes, the following advantages can be obtained such as ease of tool access, minimal fuel wall wetting in intake port while injecting fuel, improved IC engine performance, better fuel efficiency, and lesser exhaust emissions. Additionally, minimal layout changes are required to accommodate the fuel injection valve and throttle body with no change is the floorboard and side panel design. Further, fuel pressure loss to fuel injection valve is minimal. Also, the serviceability and accessibility of fuel injection valve and throttle body is easier and permits easy tool movement, connecting members access (such as fasteners).

[00022] The present subject matter along with all the accompanying embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs.

[00023] Fig. 1 illustrates a two wheeled vehicle, having the intake structure according to the embodiment of the present subject matter. In a preferred embodiment, the IC engine (101) is mounted in a straddle type motorcycle, and the present invention can be implemented in other two wheeled vehicles employing the similar engine layout. The two wheeled vehicle comprises, a front wheel (110), a rear wheel (103), a frame structure, a fuel tank (107) and seat (106). The frame structure includes a head pipe (111), a main tube (112), a down tube (113), and seat rails (126). The head pipe (111) supports a steering shaft (not shown) with two brackets D upper bracket (not shown) and lower bracket (not shown) at each end. Two telescopic front suspension (114) (only one shown) is attached to the lower bracket (not shown) on which is supported the front wheel (110). The upper portion of the front wheel (110) is covered by a front fender (115) mounted to the lower portion of the lower bracket at the end of the steering shaft. A handlebar (108) is fixed to upper bracket (not shown) and can rotate to both sides. A head light (109), visor guard (125) and instrument cluster (not shown) is arranged on an upper portion of the head pipe (111). Down tube (113) is located in front of the IC engine (101) and stretches slantingly downward from head pipe (111). A bracket (116) is provided at the lower end of down tube (113) for supporting the IC engine (101). Main tube (112) is located above the IC engine (101) and stretches rearward from head pipe (111) and connects the rear of the IC engine (101). A fuel tank (121) is mounted on the horizontal portion of the main tube (112). A vertical pipe (not shown) is joined to the rear end of main tube (112) and stretches downward from the point where the main tube (112) joins the seat rails (126). Seat rails (126) are joined to main tube (112) and stretch rearward to support a seat (106) disposed above seat rails (126). Left and right rear swing arm bracket portions (not shown) support a rear swing arm (118) to swing vertically, and a rear wheel (103) is connected to rear end of the rear swing arm (118). Generally, two rear wheel suspensions (117) are arranged between rear swing arms (118). A tail light unit (104) is disposed at the end of the two-wheeled vehicle at the rear of the seat rails (126). A grab rail (105) is also provided on the rear of the seat rails (126). A rear wheel (103) is arranged below seat (106) and rotates by the driving force of the IC engine (101) transmitted through a chain drive (not shown) from the IC engine (101). A rear fender (127) is disposed above the rear wheel (103). There is front brake (119) and back brake (not shown) arranged on the front wheel (110) and back wheel (103) respectively. [00024] Fig. lb. illustrates the location of mounting of the fuel injection valve (201), throttle body (120) and air cleaner (130) according to one embodiment. The intake system comprises an air cleaner (130), a cleaner outlet (203), a throttle body (120) and the fuel injection valve (201). The air cleaner (130) is disposed such that, at least more than half of the air cleaner (130) is adjacent to the vehicle horizontal axis (A-A) on any one side. In one embodiment the air cleaner (130) is located on the right side as viewed from the rear of the two wheeled vehicle. The outlet to the air cleaner (130) is located adjacent to the horizontal axis. The throttle body (120) is disposed advantageously in the space formed below the main tube and between the main tube and a crankcase of the IC engine (101). The cleaner outlet connects the air cleaner (130) outlet to the throttle body (120). The cleaner outlet has a profile that reduces the curves and bends to provide smooth air flow and prevents loss of air pressure. The cleaner outlet (203) is so shaped that, it has a slight curvature at its both its ends, one end being connected to the air cleaner outlet and the other end connected to the throttle body inlet, and having a substantially straight centre. This profile of the cleaner outlet (203) ensures that stresses are not concentrated on the cleaner outlet (203) to provide longer shelf life and having ease of accessibility in assembling and disassembling as it permits tool movement to access clips tightened by the screwdriver. The throttle body (120) is so placed such that its central axis is angularly oriented with respect to the horizontal axis. This placement ensures reduction of curvature on the cleaner outlet to enable smooth air flow. Additionally, this increases the space along the horizontal line between the throttle body (120) and the fuel injection valve (201) in order to provide better accessibility and better tool movement during servicing and removal. A pipe intake (204) connects the throttle body (120) to the cylinder head (101a). The fuel injection valve (201) is suitably disposed on the pipe intake (204) and it is this mounting of the fuel injection valve (201) which is an important aspect of the present subject matter.

[00025] Fig. 2a. illustrates the enlarged isometric view of the IC engine (101) and the intake structure according to the embodiment of the present subject matter. The fuel injection valve (201) is mounted below the main tube (112) on the pipe intake (204). The fuel injection valve (201) is mounted such that, a nipple fitting (201a) supplying fuel to the fuel injection valve (201) from a fuel pump (not shown) has a opening facing substantially forwardly upward towards the fuel tank (121). The location of the nipple fitting (201a) is such that a rubber hose (201d) can be easily attached to the nipple fitting (201a). The fuel injection valve (201) and nipple fitting (201a) is so positioned that, the rubber hose can be attached with least curvature and bends which ensures smooth fuel flow and no loss of fuel pressure. The fuel injection valve (201) also comprises a connector (201b) through which a wiring harness originating from the ECU can be drawn. The connector (201b) is so located that the wiring harness (404) can be easily drawn from the main tube (112) and connected to the fuel injection valve (201) connector (201b).

[00026] Fig. 2b. Illustrates the side view of the cylinder head (101a) according to the embodiment of the present subject matter. The cylinder head (101a) comprises a cylinder head intake mounting face (230) on one side facing the rear of the two wheeled vehicle whose surface is capable of receiving the pipe intake (204). The cylinder head (101a) includes two intake ports namely, swirl port (210) and tumble port (220), that control the flow of the air-fuel mixture into a combustion chamber (313), and whose opening are defined on the cylinder head intake mounting face (230). The swirl port (210) opening is in a vehicle centre plane and the tumble port (220) opening is placed offset from the centre plane (that is offset to the swirl port) and disposed above the swirl port (210) opening. The swirl port (210) runs parallel to the tumble port (220) separately up to the combustion chamber (313). The exit of the swirl port (210) and tumble port (220) are symmetric when viewed from the top of the two wheeled vehicle and are separated till the end of the cylinder head intake mounting face (230). The swirl port (210) and tumble port (220) opening have a parallelogram shape while the exit at the combustion chamber (313) is circular. The swirl port (210) is designed to have a profile with stronger curvature as compared with the profile of the tumble port (220), but the swirl port (210) has a lower inclination towards the valve axis. An exhaust port (315) provides a path for exhaust gases from the combustion chamber (313). The combustion chamber (313) also houses an opening substantially at the center of the combustion chamber (313), for a spark plug (lOld). By arranging the spark plug between the three valves, i.e., two intake valves and one exhaust valve, a position is achieved which is beneficial from the point of view of achieving increased combustion efficiency and fuel economy.

[00027] Fig. 3 illustrates a cut section of the IC engine showing the main components of the IC engine and representatively illustrates the entry of fuel taking the shortest path according to the embodiment of the present subject matter. The IC engine comprises a reciprocating piston (305) enclosed in the cylinder block (101b), a connecting rod (306) connecting the reciprocating piston (305) to a rotatable crankshaft (307). During operation, the burning of fuel and oxidizer occurs in the combustion chamber (313) and transfers mechanical energy to the reciprocating piston (305) which transfers the mechanical energy to the rotatable crankshaft (307) which generates power due to the slider crank mechanism. The IC engine (101) further comprises other ancillary systems which include starting system (not shown), transmission system (308), lubrication system (not shown) and exhaust system (124) all housed in the crankcase (lOle). The cylinder head (101a) comprises of two intake valves namely swirl intake valve (not shown) and tumble intake valve (310) and at least one outlet valve (311) which are operated by means of rocker arms (312a, 312b) and a camshaft (314) which consists of at least one inlet cam lobe and at least one outlet cam lobe (316) which actuates the rocker arms (312a, 312b) when required. An intake rocker arm (312a) comprises two arms operated by one single inlet cam lobe. The opening and closing of the intake ports are controlled by the swirl intake valve (not shown), and tumble intake valve (310 respectively. A cam-chain (not shown) operably connects the rotatable crankshaft (307) and camshaft (314) to drive the camshaft (304) in the cylinder head assembly (301). Atmospheric air from the throttle body (120) and fuel is sprayed through a fuel injection valve (201) enters the swirl port (210) and the tumble port (220) respectively. The cylinder head (101a) also comprises an exhaust port (315) whose end facing the combustion chamber (313) is controlled by the exhaust valve (311) and the exhaust port (315) directs the exhaust gases out of the combustion chamber (313) to a muffler (124) is connected to the outer portion of the cylinder head (101a). In the embodiment of the present invention, the engine operates in four cycles namely, intake stroke, compression stroke, power, and exhaust stroke. Combustion of air fuel mixture occurs at the end of compression stroke and beginning of power stroke. After combustion, exhaust gases are generated which are expelled out of the cylinder block (101b) during the exhaust stroke.

[00028] Fig. 4a. illustrates a side view and Fig. 4b. illustrates an isometric view of the throttle body (120) and the fuel injection valve (201) according the embodiment of the present invention. In the exemplary embodiment, the throttle body (120) comprises a throttle housing (not shown), idle air controlled valve (402), a throttle position sensor (403), and throttle control system. The throttle housing comprises a housing having a venturi used for throttling inlet atmospheric air flowing towards the IC engine (101) under pressure. A butterfly valve (213) is disposed downstream of the venturi which can be swiveled about an axis. Controlling this swivel, the amount of air flowing towards the pipe intake (204) can be varied. The idle air control valve (402) comprises an electronic actuator and a separate idle air flow circuit which is used to control and maintain idling state of the IC engine (101). The throttle position sensor (in an exemplary embodiment, working on the principle of Hall Effect) is capable of detecting the real-time positions of the throttle state and transmits the signals to an electronic control unit (ECU) which is not shown. The control for varying throttle comprises a throttle pulley (401) configured to rotate on an input given by the rider by an accelerator cable, a throttle shaft (not shown), the butterfly valve (213), and a return spring (401a). The throttle pulley (401) is connected to the throttle shaft which is pivoted on both sides of the inner circumferential surface of the throttle housing. The butterfly valve (213) is integrally attached to the throttle shaft and capable of being swiveled based on the rotation of the throttle pulley (401). A return spring such as a torsion spring (401a) is operably attached to the throttle pulley (401) to exert a positive biasing force on the throttle pulley (401) to keep the butterfly valve (213) closed to prevent any inlet of air. On operation of the accelerator cable (not shown) by the rider, the throttle pulley (401) is configured to rotate against the biasing force of the return spring. On withdrawal of force on the accelerator cable, the potential energy of the return spring rotates the throttle pulley (401) back to closed position.

[00029] Fig. 3 and Fig. 4b illustrates the fuel spray path taken when the fuel injector is arranged to direct fuel in the embodiment of the present subject matter. In the present engine layout, the swirl port (210) and tumble port (220) is facing horizontally towards the rear of the two wheeled vehicle. The position and mounting of the fuel injection valve (201) is one of the important aspects of the present invention. The fuel injection valve (201) is mounted angularly at a predetermined angle to the horizontal plane (Θ) to achieve the fuel spray target on both the swirl port (210) and tumble port (220). In one embodiment, the fuel injection valve (201) is placed at the predetermined angle (Θ) of between 50° to 60° to the vehicle longitudinal axis. The fuel injection valve (201) is of twin fuel spray type that can squirt fuel spray in two different angular directions. In one embodiment the angle of squirt to the swirl port (210) is in the range 8° to 15° and the angle of squirt to the tumble port (220) is in the range 18° to 25° with respect to a fuel injection valve axis. Further, the injector tip is disposed at a predetermined horizontal distance (a) from the cylinder head intake mounting face (230). In one embodiment, the predetermined horizontal distance (a) is 25 millimeter to 30 millimeter from the cylinder head intake mounting face (230). The fuel injection valve disposed in that position on the pipe intake (204) such that fuel spray is optimized such that the fuel spray target is on both the ports and greater quantity of fuel squirted in tumble port (220) is more accurate compared to the swirl port (210). This placement has advantages of better fuel injection and improved targeting. The fuel injection valve (201) is also mounted such that, the fuel spray travels the shortest distance to reach the outlet of the swirl port (210) and tumble port (220) with minimum wall wetting. In the present embodiment, the fuel spray path (410, 420) is directed towards the rear of the head of both the intake tappet valves (not shown). This ensures the fuel spray (410,420) travels directly to strike in close proximity to the outlet of the both the swirl and tumble ports. Fig. 4b. illustrates the profile of swirl port (210) and tumble port (220). It is seen that the entire tumble port (220) is disposed offset and has a profile different from that of the swirl port (210). This placement provides challenges to utilize a single fuel injection valve to provide fuel spray to both the intake ports (210, 220). An optimum position to mount the fuel injection valve (201) in this profile is the main important aspect of the present subject matter.

[00030] Fig. 5a, Fig. 5b and Fig. 5c illustrates an insulator pad (501) disposed on the cylinder head intake mounting face (230) at the junction where the intake pipe portion (230) is connected according to the embodiment of the present invention. It is necessary to prevent the fuel injection valve (201) from exceeding beyond a specified temperature in order to function effectively. The insulator pad (501) insulates the thermal energy generated from inside the two intake ports and prevents the temperature around the fuel injection valve from exceeding beyond a certain maximum temperature. Further, the insulator pad (501) is used to change and direct the fuel spray to both the swirl port (210) and tumble port (220) with less flow loss. Further, the insulator pad has a diverging shape with the relief cut (see 502) on the swirl port (210) opening to have smooth flow diversion between the swirl port (210) and tumble port (220). Additionally, at the tip of the cylinder head wall wherein the insulator pad is disposed, a relief cut is provided on the insulator pad to have fuel spray targeting in the swirl port (210) which is located below the tumble port (220).

[00031] Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.

Claims

We Claim:

1. A two wheeled straddle-type vehicle (100) comprising: a frame structure (111, 112), extending from a front portion (F) to a rear portion (R) along a vehicle horizontal axis (A- A), said frame structure (111, 112) further comprising:

a head pipe (111);

a main tube (112) disposed in the front portion (F), said main tube (112) having a horizontal portion (112a) extending horizontally from the head pipe (111) and a downward portion (112b) extending downwardly towards the rear portion (R); a down tube (113) extending downwards from the head tube (111) disposed in the front portion (F);

an internal combustion (IC) engine (101) disposed below the main tube (112) and mounted between the down tube (113) and downward portion (112b) of the main tube, said IC engine (101) including a cylinder head (101a), a crankcase body (lOle), and a cylinder block (101b) interposed between the cylinder head (101a) and crankcase body (lOle);

the cylinder head (101b) including two inlet ports (210, 220), said two intake ports (210,220) configured to direct air fuel mixture inside the cylinder block (101b);

an air cleaner (130) disposed on the behind the downward portion (112b) of the main tube, said air cleaner disposed adjacent to the longitudinal axis towards the vehicle width direction;

an intake system connecting the air cleaner (130) and to the two intake ports (210,220), and said intake system including:

a throttle body (120) disposed in a space formed between the horizontal portion (112a) of the main tube (112) and the crankcase body (lOle), said throttle body (120) configured to control air flow rate drawn from the air cleaner (130); a cleaner outlet (203) connecting the air cleaner (130) and the throttle body (120);

a pipe intake (204) disposed downstream of the throttle body (120) connecting the throttle body (120) to the two intake ports (210,220);

a fuel injector valve (201) mounted on the pipe intake (204) and configured to direct fuel inside the two intake ports (210,220), said fuel injection valve (201) mounted to have a fuel injector axis (X- X) at a predetermined acute angle (Θ) with reference to a horizontal plane (Y-Y), and said fuel injector valve (201) mounted at a predetermined horizontal distance (a) between the tip of the fuel injection valve (201) and the cylinder head (101a).

2. The two wheeled straddle-type vehicle (100) as claimed in claim 1, wherein the predetermined acute angle (Θ) is between 50 to 60 degrees and the predetermined value (a) is within the range 25 to 30 millimeters such that such that the fuel injected inside the two intake ports (210, 220) takes the shortest path with minimum wall wetting of the two intake ports (210, 220).

3. The two wheeled straddle-type vehicle (100) as claimed in claim 1, wherein said fuel injection valve (201) is of twin fuel spray type that can squirt fuel spray in two different angular directions from the injector nozzle.

4. The two wheeled straddle -type vehicle (100) as claimed in claim 3, wherein the angle of squirt of fuel to the swirl port (210) is in the range 8° to 15° and the angle of squirt of fuel to the tumble port (220) is in the range 18° to 25° with respect to the fuel injection axis (X-X).

5. The two wheeled straddle-type vehicle (100) as claimed in claim 1, wherein said throttle body (120) is placed to have its central axis angularly oriented with respect to the vehicle horizontal axis (A-A) to ensure reduction of curvature of the cleaner outlet (203) profile to enable smooth air flow, and to increases the space between the throttle body (120) and the fuel injection valve (201).

6. The two wheeled straddle-type vehicle (100) as claimed in claim 1, wherein the air cleaner (130) is disposed to have more than half of the air cleaner (130) adjacent to the vehicle horizontal axis (A-A) on any one side of the two wheeled straddle -type vehicle (100).

7. The two wheeled straddle-type vehicle (100) as claimed in claim 1, wherein the cleaner outlet (203) has a gentle curvature at its both its end portion and a substantially straight centre portion to provide smooth air flow.

8. The two wheeled straddle -type vehicle (100) as claimed in claim 1, wherein said fuel injection valve (201) comprises a nipple fitting (201a) supplying fuel to the fuel injection valve (201) from a fuel pump (not shown) through a rubber hose (201d), said nipple fitting (201a) has a opening facing substantially forwardly upward towards the fuel tank (121) to enable easy attachment of the rubber hose (201d) with least curvature and bends.

9. The two wheeled straddle -type vehicle (100) as claimed in claim 1, wherein said fuel injection valve (201) also comprises a connector (201b) through which a wiring harness originating from an electronic control unit can be drawn.

10. The two wheeled straddle-type vehicle (100) as claimed in claim 1, wherein said cylinder head (101a) includes two intake ports namely, a swirl port (210) and a tumble port (220), said swirl port (210) is designed to have a profile with stronger curvature and lower inclination towards the valve axis as compared with the profile of said tumble port (220), and said tumble port (220) is disposed offset from that of the swirl port (210).

11. The two wheeled straddle -type vehicle (100) as claimed in claim 1, wherein the pipe intake (204) to connected to the cylinder head (101a), and an insulator pad (501) is disposed there between at the junction to change and direct the fuel spray from the fuel injection valve (201) to both the swirl port (210) and tumble port (220).

12. The two wheeled straddle -type vehicle (100) as claimed in claim 11, wherein the insulator pad (501) has a diverging shape with a relief cut (502) at the centre of the partition to have smooth fuel diversion between the swirl port (210) and tumble port (220).