INTAKE SYSTEM FOR A MOTORCYCLE

FIELD OF THE INVENTION

The present invention relates to intake system for a motorcycle and more particularly relates to an intake conduit intended for use with a single cylinder internal combustion engine.

BACKGROUND OF THE INVENTION

A conventional motorcycle is powered by a single cylinder internal combustion engine generally disposed at a lower half of the motorcycle. This engine converts chemical energy into mechanical energy by combustion of air-fuel mixture within a combustion chamber of the engine. The engine, among other components, has a cylinder block comprising a cylinder head atop the cylinder block and receiving a reciprocating piston from the bottom.

On combustion of the air-fuel mixture, the piston transfers the energy generated during combustion to a crankshaft through a connecting rod thereby driving the crankshaft. In this way, the reciprocatory motion of the piston is converted to rotatory motion of the crankshaft. The crankshaft is housed inside a crankcase beneath the cylinder block. In order to set the vehicle into motion, the power supplied to the crankshaft of the internal combustion engine is carried to a wheel of the vehicle, in a controllable way, through a transmission system.

Typically an intake system of such an engine comprises of an intake conduit, a carburettor and a cylinder head assembly. The carburettor comprises a die cast body of complex shape into which a series of carefully machined openings are provided. It provides a combustible charge to the engine combustion chamber for ignition. The typical carburettor, made of aluminium or an aluminium alloy, is connected to the intake conduit on one side and an air inlet device on the opposite side through known joining mechanisms. In the prior art, the intake conduit is located between the carburettor and the cylinder head and made of aluminium. It receives air-fuel mixture from the carburettor and supplies it to the combustion chamber of an internal combustion engine with the help of intake valves which are also situated in the cylinder head.

Usually an insulating pad generally measuring 6-7 mm is provided on one side of the intake conduit to prevent the heat of the cylinder head from being transferred to the carburettor. It provides heat insulation to the carburettor and resists heat transfer from the cylinder head of the engine to a float bowl of the carburettor. The presence of insulating pad leads to serviceability issues while servicing the intake system of the single cylinder engine. It leads to increase in number of parts during assembly of intake system causing increase in assembly time and reduction in efficiency. Further the use of intake conduit made of aluminium increases the weight and cost of the motorcycle. Furthermore such intake conduit has to be machined on either side for mating the matching surface thereby ensuring a proper, efficient and functional connection to the carburettor and the cylinder head. The present invention deals with all or any of the above problems and obviate the lacunae in the prior art.

Therefore it is an objective of the present invention to provide an improved intake system for a motorcycle comprising an intake conduit of elongated length capable of connecting a carburettor and a cylinder head in a single cylinder internal combustion engine and achieve cost and weight reduction. Another objective of the present invention is to achieve similar function and performance from the intake system in the absence of an insulating material.

Yet another object of the present invention is to provide better serviceability and surface finish to the intake conduit. Still another object of the present invention is to keep the temperature of the float bowl of the carburettor below a certain temperature in the absence of the insulating material.

SUMMARY OF THE INVENTION

Accordingly, the present invention relates to an improved intake system for a single cylinder internal combustion engine comprising an intake conduit, the intake conduit comprising: an elongated hollow pipe forming intake conduit body and having at least two ends, an inlet end facing a carburettor and connecting the said intake conduit to the carburettor, an outlet end facing a cylinder head and connecting the said intake conduit to the cylinder head, the inlet end and the outlet end respectively containing mounting flanges integrally connected to the said intake conduit body, wherein the said outlet end of the said intake conduit is directly clamped on the cylinder head through the respective mounting flange comprising of mounting provisions with steel inserts, the mounting flange of the outlet end of the said intake conduit further comprising an O-ring made of elastomeric material in a groove radially connecting the said mounting flange to the corresponding flange on the cylinder head in an integral and air tight manner in order to prevent leakage of the air fuel mixture to the atmosphere.

According to an embodiment of the present invention, the intake conduit is disposed between the carburettor and the cylinder head of the said engine and it acts as a channel to transport combustible mixture to the said cylinder head and also functions as an insulator to prevent the flow of heat from the said cylinder head to a float bowl of the said carburettor thereby keeping the temperature of the said float bowl below 45 degree Celsius

According to an embodiment of the present invention, the intake conduit of the intake system is more than 40 mm but less than 70 mm in length and fabricated from a thermo-resistant plastic resin including nylon 6- mixed with glass fibres.

The foregoing objectives and summary provide only a brief introduction to the present subject matter. To fully appreciate these and other objects of the present subject matter as well as the subject matter itself, all of which will become apparent to those skilled in the art, the ensuing detailed description of the invention and the claims should be read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features, aspects, and advantages of the subject matter will be better understood from the following description with reference to the accompanying drawings. The reference numerals have been used to refer to identical or functionally similar elements. The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present invention wherein:

Figure 1 shows a perspective view of a typical motorcycle.

Figure 2 depicts a front view of an improved intake system of a single cylinder motorcycle.

Figure 3 shows a side view of the improved intake system of a single cylinder motorcycle.

Figure 4 shows a detailed front view of an intake conduit according to the present invention

Figure 5 shows the side view of an intake conduit as depicted in the present invention.

Persons skilled in the art will appreciate that elements in the drawings are illustrated for simplicity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The subject matter described herein relates to an improved intake system comprising of an intake conduit capable to achieve similar function and performance in the absence of an insulating material in the intake system.

Various other features and embodiments of the intake conduit according to the present invention here will be discernible from the following further description thereof, set out hereunder. In the ensuing exemplary embodiments, the vehicle used is a motorcycle. However it is contemplated that the disclosure in the present invention may be applied to other types of vehicles capable of accommodating the present subject matter without defeating the spirit of the invention. Further "Front" and "rear", and "left" and "right" wherever referred to in the ensuing description of the illustrated embodiment refer to front and rear, and left and right directions as seen in a state of being seated on a seat of the motorcycle. Furthermore, a longitudinal axis refers to a front to rear axis relative to the motorcycle, while a lateral axis refers generally to a side to side, or left to right axis relative to the motorcycle.

The intake system according to the present invention is now described in detail in connection with the rendered figures. The detailed explanation of the constitution of parts other than the invention which constitutes an essential part has been omitted at suitable places.

Figure 1 shows a perspective view of a typical motorcycle. A typical motorcycle M comprises a body frame assembly made up of a number of tubes welded together. The motorcycle M has a steerable front wheel 11 and a driven rear wheel 12. The body frame primarily includes a head pipe 1 disposed at a front end of the body frame, a main tube running across the longitudinal axis of the motorcycle M and enclosed by several motorcycle components, and a down tube 2. A front fork 3 may be connected to the head pipe 1 by any known type of suspension system and rotatably carries the front wheel 11. The head pipe 1 supports a steering shaft disposed inside the head pipe 1. The upper and lower ends of the steering shaft are fixed on an upper bracket and the under bracket. The front end of the main tube (not shown) and an upper end of the down tube 2 are connected to the head pipe 1. The down tube 2 extends obliquely downward in front of an engine 15 from the head pipe 1 whereas the main tube extends rearward from the front end thereof.

A front fender 4 is provided below the under bracket to avoid the motorcycle and its occupants from being splashed with mud. A fuel tank 5 is disposed above the main tube for storing the fuel for propelling the motorcycle M. A seat 6 for a driver and a pillion is further provided, with the said seat 6 being placed behind the fuel tank 5 and rearwardly of the main tube.

The rear wheel 12 revolves about a sprocket splined shaft (or central axle) 13. The axle 13 is supported at each end by a swing arm 14, the swing arm in turn pivotally connected to the body frame of the motorcycle M by a rear suspension 10. Generally a motorcycle may use any of the two arrangements for rear suspensions, namely dual suspension and mono suspension. However the present motorcycle is exemplified through a dual suspension system. The dual suspensions are fixed at their upper ends to the motorcycle frame. Their lower ends are fixed to the swing arm 14.

The anterior portion of the motorcycle placed forward to the fuel tank 5 comprises of a headlamp assembly, the headlamp assembly further comprising a headlamp 8 and a visor 7 placed forward to a handlebar assembly. The handle bar assembly further comprises of a handle bar 9 extending transversely to the vehicle and several control switches for various motorcycle operations.

The said motorcycle M is powered by an internal combustion engine 15 disposed below the main tube and supported by the down tube 2. The engine may be liquid-cooled or air-cooled. Drive force output from the engine 15 is transmitted to the rear wheel 12 through a transmission system. The transmission system includes a clutch actuated by a clutch lever placed forwardly to one side of the handle bar 9, a gear box and a chain drive. The transfer of power from the engine to the rear wheel takes place generally by disengaging the clutch by pulling the clutch lever and thereafter manually shifting the gears in the gear box through a foot pedal 16 manually operated by the operator of the motorcycle M.

The present invention proposes an improved intake system present in close proximity with the engine 15 comprising a means serving dual functions of acting as a channel to transport combustible (air-fuel) mixture to the cylinder head and functioning as an insulator to prevent the flow of heat from the cylinder head to a float bowl of the carburettor thereby keeping the temperature of the float bowl low in the absence of the insulating material.

Figure 2 and 3 depicts the improved intake system comprising an intake conduit adapted to be connected to the cylinder head (not shown) of the engine. The intake conduit 100 is disposed between a carburettor 200 and a cylinder head of the engine 15. As shown in Figure 4 and Figure 5, the said intake conduit 100 may be divided into two parts, Intake conduit body 101 and mounting flanges 102a, 102b present on either end of the intake conduit body 101. The Intake conduit body 101 is an elongated hollow body preferably of tubular or circular cross section.

The intake conduit 100 has at least two ends, namely an inlet end 103 facing towards the carburettor 200 and an outlet end 104 facing toward the cylinder head (not shown). The inlet end 103 is configured to receive the air-fuel mixture from the carburettor 200 and the outlet end 104 is configured to discharge the air-fuel mixture into the cylinder head (not shown) of the engine. The inlet end 103 is provided with a radially outwardly extending mounting flange 102a by which the intake conduit is connected to the carburettor via attachment means. Similarly the outlet end 104 is also provided with a mounting flange 102b for connecting it to the cylinder head. Intake conduit body 101 and mounting flanges 102a, 102b are rendered integral with each other and not separate. The Intake conduit body 101 has an opening (not marked) for air injection through which inputs are provided to other subsystems thereby facilitating their functions. A tubular pipe is generally press fitted onto this opening for sensing the vacuum levels in the intake path. This input (vacuum level) is used by a secondary air injection valve to cut off air supply into the exhaust to avoid after burn.

Further the mounting flange 102b on the outlet end 104 of the intake conduit 100 directly clamps it to the cylinder head through the corresponding mounting flange (not shown) present on the cylinder head. The clamping is completed by fasteners inserted into two diametrically opposite holes 106 on either mounting flange with steel inserts ensconced in them. Thus the Intake conduit 100 is directly clamped on the cylinder head through a mounting flange without the presence of insulating pad in between. Further the mounting flange 102b has a groove containing an O-ring 105 made of an elastomeric material such as rubber. The O-ring 105 radially connects the intake conduit 100 to the corresponding flanges on the cylinder head in an integral and air tight manner. Due to this the discharge of combustible mixture into the atmosphere and mixing of air contained in the atmosphere into the combustible mixture are prevented.

The length of the intake conduit 100 is elongated to the order of 40-70 mm. It is sufficiently long to gradually decrease temperature coming from the cylinder head to the carburettor and therefore maintains the float bowl temperature in the range of 40-50 degree Celsius for proper functioning. Moreover the said intake conduit may be made up of thermal resistant plastic resin. In one embodiment of the present invention, the intake conduit is fabricated of nylon 6 grade mixed with glass fibres.

From the forgoing description, it will be appreciated that the present subject matter and its equivalent thereof offer many advantages, including those which have been described henceforth. The required shape of such intake conduit is ensured even when the intake conduit undergoes vibrations from the single cylinder engine or a negative intake pressure. The arrangement in the present invention is advantageous because the intake conduit handles vibrations originating from the engine well when tested. Additionally as the intake conduit is made of nylon 6, it is light weight and cost effective.
Since the insulator pad is eliminated, the number of components and the required steps for assembly are decreased and thus a reduction in cost can be attained. Moreover the surface finish of the present invention is better than aluminium intake conduit due to the material used. The elimination of insulating pad leads to better serviceability of the intake system. The present invention requires no separate machining and is durable when tested.

The present invention is thus described. The term 'intake conduit' is used in this specification in generic sense, that is, to denote a device for connecting a carburettor and a cylinder head; but the invention is especially directed to intake conduit intended for use with petrol driven internal combustion engines.
The description is not intended to be exhaustive nor is it intended to limit the invention to the precise form disclosed. It will be apparent to those skilled in the art that the disclosed embodiments may be modified in light of the above description. The embodiments described are chosen to provide an illustration of principles of the invention and its practical application to enable thereby one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore the forgoing description is to be considered exemplary, rather than limiting, and the true scope of the invention is that described in the appended claims.

claim:

1. An improved intake system for a single cylinder internal combustion engine comprising an intake conduit, the intake conduit comprising: an elongated hollow pipe forming intake conduit body and having at least two ends,

an inlet end facing a carburettor and connecting the said intake conduit to the carburettor,

an outlet end facing a cylinder head and connecting the said intake conduit to the cylinder head, the inlet end and the outlet end respectively containing mounting flanges integrally connected to the said intake conduit body,

wherein the said outlet end of the said intake conduit is directly clamped on the cylinder head through the respective mounting flange comprising of mounting provisions with steel inserts, the mounting flange of the outlet end of the said intake conduit further comprising an O-ring made of elastomeric material in a groove radially connecting the said mounting flange to the corresponding flange on the cylinder head in an integral and air tight manner in order to prevent leakage of the air fuel mixture to the atmosphere.

2. The improved intake system as claimed in claim 1 wherein the said intake conduit is more than 40 mm but less than 70 mm in length and fabricated from a thermo-resistant plastic resin including nylon 6 mixed with glass fibres.

3. An improved intake system for a single cylinder internal combustion engine comprising a means, disposed between a carburettor and a cylinder head of the said engine, the said means acting as a channel to transport combustible mixture to the said cylinder head and also functioning as an insulator to prevent the flow of heat from the said cylinder head to a float bowl of the said carburettor thereby keeping the temperature of the said float bowl below 45 degree Celsius, the said means fabricated from a thermo resistant plastic resin including nylon 6 mixed with glass fibres and the length of the said means being in the range of 40 to 70 mm.

4. The improved intake system as claimed in claim 3 wherein the said means preferably has a tubular section and comprises of a mounting flange on either side.

5. An improved intake system substantially as herein described and illustrated with reference to the accompanying drawings.