FUEL SUPPLY SYSTEM FOR INTERNAL COMBUSTION ENGINE

FIELD OF THE INVENTION

The present invention relates to a "Fuel supply system for an internal combustion engine" and more particularly to a choke lever assembly.

BACKGROUND OF THE INVENTION

To start an engine efficiently and effectively, the fuel-air ratio of a fuel charge delivered to the engine should be controlled both at the time of starting the engine and during the time the engine warms to its designed operating temperature.

When starting a cold engine, the charge (air fuel mixture) should contain a higher concentration of fuel because some percentage of the fuel will condense on the cold induction system of the engine before the charge is delivered to the combustion chamber. The initial ratio of fuel to air thus must be richer in order to supply a charge having the proper fuel to air ratio. Of course, colder weather condition increases this problem; with a lower starting temperature, a large percentage of the fuel in the charge condenses on the colder surfaces of the induction system.

Conventional charge formers use various types of cold starting devices to produce a richer charge when starting a cold engine. For instance a choke valve is used in a conventional carburetor to decrease air-flow into a mixture chamber of the carburetor, and consequently the concentration of fuel in the charge is increased.

The engine warms after starting. Less fuel condensation occurs as the engine and its induction system warms, and consequently, the percentage of fuel in the fuel charge can be decreased. The fuel to air ratio desirably decreases at a rate corresponding to the rise in engine temperature to maintain consistency in engine performance. Thus, the fuel to air ratio of the charge gradually decreases to a desirable ratio for operation after the engine has warmed.

In a motorcycle, generally, a lever to actuate the choke valve is either secured on the handlebar or is mounted on the body of the carburetor. In the former case, choke is operated by a choke cable connected to the choke lever on the handlebar and in the latter case, the choke lever is mounted on the body of the carburetor and is hand operated by the person riding the motorcycle. A bracket throttle lever that rotates when the throttle is opened is pivoted on the body of the carburetor. In motorcycles having choke lever mounted on the body of the carburetor, the bracket throttle lever is in close proximity to the said choke lever. In such motorcycles, once the choke lever is pulled to actuate the choke, and the throttle is opened, the bracket throttle lever rotates and may come in way of the finger that is used to operate the choke lever causing unsafe riding conditions.It is to be noted here that generally when the choke lever is operated, the operator is sitting on the motorcycle and in most cases he is riding the vehicle and therefore the operator almost has no view of the choke lever and therefore there is high probability of injuries being caused to the fingers of the choke operator. The choke lever position cannot be kept away from the carburetor as the overhang increases and also because of the packaging constraints. Therefore to obviate the defects in the prior art, there is a requirement for a protection mechanism to protect the finger of the operator during choke operation.

SUMMARY OF THE INVENTION

The principal objective of the present invention is to provide a carburetor for an internal combustion engine with an improved choke lever to enhance safety of the operator during choke operation. To achieve this objective, the abovementioned improved choke lever is characterized by a choke lever flange secured between the choke lever knob and the bracket throttle lever such that the fingers of the person operating the choke lever is prevented from getting in way of the rotation of the bracket throttle lever. The flange acts as a preventive mechanism and safety device against unsafe riding conditions as the movement of the fingers of the choke operator is restricted, thereby avoiding hurt being caused to the fingers. Further, the arrangement as per the present invention is a cost effective method for providing improved safety conditions to the customer and also makes choke operation very user friendly because installation of the choke lever flange leads to the operator getting a better grip on the choke lever knob and hence choke operation is made easier.

These and other features, aspects, and advantages of the present invention will be better understood with reference to the following description, the appended claims and the accompanying drawings. This summary is not intended to identify key features or essential elements of the claimed subject matter, nor is there an intention to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF DRAWINGS

The above and other features, aspects, and advantages of the present invention are further illustrated by the accompanying drawings. The drawings are given by way of illustration only and are not limitative of the present invention. A brief description of the drawings is as follows: Figure 1 is a side view of a conventional motorcycle. Figure 2 is a side view of a carburetor with a conventional choke lever Figure 3 is a side view of a carburetor with a choke lever as per the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A motorcycle 10 as illustrated in Figure 1 includes an engine 41, a front wheel 25, a rear wheel 27, a body frame 19 and a fuel tank 56. Body frame 19 includes a head pipe 12, a main tube 17, at least one down tube 22, and seat rails 18. The head pipe 12 is provided at the front end of body frame 19 to support a steering shaft 11 disposed within head pipe 12. The upper and lower ends of the steering shaft 11 are fixed to an upper bracket 13 and a lower bracket 14 respectively. Upper bracket 13 and lower bracket 14 retain front suspensions 16 that supports front wheel 25. The front wheel 25 is connected at the lower end of the front fork 16, and a front fender 54 mounted to the lower portion of the front fork 16 covers the upper portion of the front wheel 25. A handlebar 15 is fixed to upper bracket 13 and can rotate to both sides. A headlight 36 is arranged on an upper portion of the front fork 16. Down tube 22 is located in front of engine 41, and stretches slantingly downward from head pipe 12. A bracket 55 is provided at the lower end of down tube 22 for supporting the engine 41. Main tube 17 is located above engine 41 and stretches rearward from head pipe 12 and connects the rear of the engine 41. A carburetor 30, located above the engine 41, and below the main tube 17, is connected to the engine 41 by way of an intake pipe 29.A vertical pipe 28 is joined to the rear end of main tube 17 and stretches upward from the point where it joins to main tube 17 to seat rails 18. Seat rails 18 are joined to main tube 17 and stretch rearward to support a seat 57 disposed above seat rails 18. A side stand 58 is arranged on lower portion of engine unit of motorcycle 10. Left and right rear arm bracket portions support a rear arm 26 to swing vertically, and a rear wheel 27 is connected to rear end of the rear arm 26. Rear wheel 27 is arranged below seat and rotates by the driving force of engine transmitted by chains, belts and so on. A rear wheel suspension 34 is arranged between rear arms 26. A tail light unit 64 is disposed on the rear cover 61. A pillion footrest 31 is connected to the vertical pipe 28. A grab rail 62 is also provided on the rear of the seat rails 18.

Figure 2 and Figure 3 are side views of a carburetor with a conventional choke lever 101 and that with an improved choke lever 201 respectively. A conventional choke lever 101 has a choke knob 102 fixed to it at its free end. As shown in the figures, the choke lever (101 & 201) is mounted on the body of the carburetor 30a and the bracket throttle lever 100 is pivoted on the body of the carburetor 30a towards the rear of the choke lever knob (102 & 202). Conventionally, every carburetor is provided with a choke valve and a throttle valve to regulate air fuel mixture to the engine. The choke shaft supports the choke valve within an internal passage of the carburetor body and controls the opening degree of the choke valve as known in the art. In the illustrated embodiment as shown in figure 3, the choke valve desirably is a butterfly type valve and pulling the choke shaft moves the choke valve between a closed position and a full open position.

When the choke lever is pulled, the choke valve is closed, thereby providing richer mixture to the engine since air supply to the carburetor is choked off. After the engine starts, when throttle is opened, the bracket throttle lever 100 which is pivoted on the body of the carburetor 30a rotates towards the direction of the choke lever (101 & 201). Therefore, in case of conventional choke lever 101, after the engine starts, when the choke lever 101 is pushed back to its original position, the fingers of the operator are very likely to interfere with the bracket throttle lever operation, thereby causing injury. The risk of injury is further increased since at the time of pushing the choke lever to its original position, the operator would be normally sitting on the motorcycle or might be even riding the motorcycle and hence there are very minimal chances of the rider viewing the choke lever while operating it. Carburetor with an improved choke lever 201 as per the present invention has a choke lever flange 200 secured between the choke lever knob 202 and the bracket throttle lever 100 as shown in Figure 3. The flange 200 therefore acts as a shield and prevents the fingers of the choke operator from getting caught between the choke lever 201 and the bracket throttle lever 100 thereby enhancing user safety. The improved choke lever 201 as per the present invention is a very cost effective arrangement and also makes choke operation more user friendly since the choke lever knob 202 can be gripped more easily by the operator due to the choke lever flange 200 and hence choke operation is made easier.

We Claim:

1. A carburetor for an internal combustion engine comprising:

a choke lever on the body of the carburetor;

a choke lever knob fixed to the free end of the choke lever;

a bracket throttle lever pivoted to the body of the carburetor; and

a choke lever flange secured between the choke lever knob and the
bracket throttle lever.

2. The carburetor for an internal combustion engine as claimed in claim 1, wherein the said bracket throttle lever is arranged towards the rear of the choke lever flange.

3. The carburetor for an internal combustion engine as claimed in claim 1, wherein the said choke lever flange is preferably secured on the choke lever knob.

4. A carburetor for an internal combustion engine as hereinabove described in the specification with the accompanying drawings.