Engine cooling system

Field of the invention

The present invention relates to "Engine cooling system" and more particularly to efficient air-cooling of horizontally mounted engines in step through motorcycles.

Description of the prior art

All engines need to dispose off heat produced during its operation and various means are generally adopted for heat disposal such as water, oil or air-cooling. Air-cooled motorcycle engines rely heavily on airflow over it for cooling purposes by convection process. In the event when the air flow doesn't corresponds with the heating of the engine, it leads to high lubricating oil and engine temperatures, which may result to engine seizure and other compulsions and could damage various attributes such as performance, etc of the engine. Typically in step through motorcycles where the engine is horizontally mounted, plastic parts that enclose the engine such as cover main pipe on both left and right side of the vehicle facilitates the air to be directed towards the engine.

In such motorcycles, the cover main pipe form two different parts surrounding the engine and thus provide a larger open area for the incoming air to focus on the horizontally mounted engine. However, these separates parts of the cover main pipe create vibrations when the motorcycle runs on an uneven surface. Consequently, to avoid the vibrations both the said covers are joined. As a result of this joining the vibrations are eliminated. However, consequent to this joining the cooling of the engine is affected because the path of the incoming air is considerably reduced. To increase the cooling efficiency in the above said scenario, the inside structure of the cover main pipe is modified such that air is converged towards the engine. However, these above said modifications run through the entire part of inside of the cover main pipe surrounding the engine and as a result of this, it tends to be bulky and tends to be costly.

Another problem present in the current art is the ease of opening of spark plug in such designs. In such designs, the engine being surrounded by plastic parts having aesthetic functions makes access to the spark plug difficult. Moreover, the engine maintenance also becomes difficult owing to the surrounding of it by the plastic parts.

Hence the main objective of the present invention is to provide a deflector causing sustained cooling during riding conditions effectively.

Another objective of the present invention is to provide a structure that in addition to cooling also provides easy access to the spark plug and engine maintenance.

Brief description of the present invention

Air cooling of motorcycle engine, especially when the engine is surrounded by styling parts is limited by shape and frontal opening area of the styling parts. Some motorcycles have their main styling parts converged towards the engine and while other extend the main styling part back and make them convergent. In the present invention, instead of designing the main styling itself convergent or extending them inside, separate limited size, side deflectors are provided to converge the airflow towards the engine. Bulge and slot are also given in one of the side deflector for accessibility of spark plug removal tool.

Brief description of the drawings

Figure 1 illustrates side view of a motorcycle according to one embodiment of
the present invention

Figure 2 illustrates top view of the air deflector arrangement according to one
embodiment of the present invention

Figure 3 illustrates front view of the air deflector arrangement according to
one embodiment of the present invention

Figure 4 and 5 illustrates isometric views of air deflector arrangement
according to one embodiment of the present invention

Figure 6 illustrates the deflectors used in the present invention

Detailed description of the invention

A selected illustrative embodiment of the present invention will be now
described with respect to the accompanying figures 1,2 3,4,5 and 6.

Any known step through motorcycle can be divided into three major portions,
the front portion, the middle portion and the rear/tail portion.

The front portion comprises of the head tube 101, the handle bar 102, the
front suspension 103, the front wheel 104 with necessary brakes and the body
panels 105; the middle portion comprises of the step through portion 106, the
riders seat 107, the engine108, the brake pedals 109, the pillion and the rider
foot rest 110, the utility box etc; and the rear/tail portion comprises of the rear
fender 111, the pillion handle 112, shock absorbers 113 and the back wheel 114 with suspensions.

Typically, a frame structure (not shown in the drawing) for a step through motorcycle comprises a sub-frame and a main frame. The sub-frame is attached to the mainframe using appropriate fastening members. All the other components such as the body panels 105, the engine 108, and the electrical units are mounted on the main frame and the sub frame either directly or by means of brackets.

Furthermore, the main frame comprises a head tube 101, a main tube (not shown in the drawing) having one end attached to the head tube 101 and an engine 108 mounting arrangement attached to the other end of the main tube. One or more swing arms 115 are attached to the engine mounting arrangement with the help of a swing arm pivot tube. The frame structure further comprises one or more upper tubes attached to the main tube.

One or more rear shock absorber mounting brackets are attached to the upper tubes. Rear shock absorbers 113 are attached to the rear shock absorber mounting brackets at one end and to the swing arms 115 at the other end. The rear shock absorber mounting brackets are added to provide additional support to the said rear shock absorbers 113.
In assembling such a vehicle, especially the body cover 105, there are many sub assemblies and these are independently mounted onto the frame at different locations. The body covers 105 are mounted to the frame using brackets.

A cover main pipe 201 having a leg shield 202 is also attached along with the body covers 105 which comprises a cover main pipe left and right side, covering the front portion of the vehicle body and both sides of the engine 108 and having an air introducing opening 205 at the front portion. Moreover the air guide walls 206 are also present which guide the running air towards the engine 108.

According to the first aspect of the present invention, instead of designing the cover main pipe 201 surrounding the engine 108 converging or extending them further inside, a pair of separate limited size, side deflectors 207 are provided on the inside of cover main pipe 201 surrounding the engine 108 to converge the air flow towards the engine 108. These side deflectors 207 are mounted to the cover main pipe unit 201. Accordingly, this leads to material and cost savings.

According to the second aspect of the invention, since the air deflectors 207 guide the running air more efficiently towards the engine 108, they can further improve the cooling efficiency. The difference could be observed with the following table wherein the effect on engine oil temperature can be observed.

According to the third aspect of the invention, slot 208 and bulge 209 has also been given on the one of the side deflectors 207 for easy accessibility to the spark plug 210 and for removal of it for maintenance purposes. Moreover, these deflectors could be made either of plastic, metal or hard rubber. It provides easy serviceability.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

Claims

We claim:

1. An engine cooling system for a motorcycle comprising a cover main pipe 201 having a leg shield 202 attached along with body covers 105 covering the front portion of the said motorcycle body and both sides of the engine 108 and having an air introducing opening 205 at the front portion wherein a pair of separate limited size, side deflectors 207 are provided on the inside of cover main pipe 201 surrounding the engine 108 to converge the air flow towards the engine 108.

2. An engine cooling system for a motorcycle as claimed in claim 1 wherein the said side deflectors 207 are mounted to the cover main pipe unit 201.

3. An engine cooling system for a motorcycle as claimed in claim 1 wherein a slot 208 and a bulge 209 are located on either of the said deflectors 207 for easy accessibility to the spark plug 210 of the said engine 108.

4. An engine cooling system for a motorcycle as claimed in claim 1 wherein the said deflectors 207 are made of resin or metal.