FORCED AIR COOLED INTERNAL COMBUSTION ENGINE

FIELD OF INVENTION

[0001] The present invention relates to a forced air-cooled internal combustion engine and more particularly to a sealing arrangement for the cooling system of a forced air-cooled internal combustion engine.

BACKGROUND OF INVENTION

[0002] In a conventional forced air cooled internal combustion engine, air for engine cooling purpose is drawn inside the cooling system from the outer atmosphere through a cooling air inlet by using rotating mechanism of a cooling fan. The rotation of the cooling fan is integrated to the rotation of the engine crankshaft. A shroud surrounding the cylinder block and the cylinder head guides the cooling air thereby cooling the cylinder block and cylinder head. The shroud consists of fan housing and a deflector. The fan housing including the fan cover extends from the cooling fan till the top surface of the cylinder head and covers half portion of the cylinder head and cylinder block. The deflector covers the other half and has a cutout for hot air exit. The deflector and the fan housing are attached to each other by using a snap fit mechanism.

[0003] The interface between the shroud and the top surface of the cylinder head is normally sealed to enhance cooling and to avoid hot air from leaking into the engine compartment. For this purpose, in arrangements known in the prior art, the cylinder head top surface is extended to form a sealing fin. This fin is similar to other fins of the cylinder block. The shroud hugs the sealing fin with a sealing member, sandwiched in between, in this manner that both the sealing fin and the shroud are secured to the sealing member. In such arrangements, during fastening of the fan housing and the deflector, there is a high possibility of the sealing member being detached from the sealing fin. Such an occurrence increases assembly time and adversely affects cylinder head and cylinder block cooling which in turn reduces the overall efficiency of the engine. Further, such arrangements are less cost efficient due to high material cost of the sealing member and due to high cost of sealants used for securing the sealing fin and the shroud to the sealing member.

[0004] Therefore to obviate defects in the prior art, there is required an improved sealing arrangement for the cooling system of a forced air cooled internal combustion which ensures optimal cooling of the cylinder block and cylinder head and this forms the principal objective of the present invention. It is a further objective of the present invention to provide a sealing arrangement, which reduces substantially the cost of material of the sealing member. It is a still further objective of the present invention to provide a sealing arrangement, which improves the overall efficiency of the engine.

SUMMARY OF THE INVENTION

[0005] In the current invention, a cooling mechanism for Continuously Variable Transmission (CVT) engine has been disclosed, wherein, an efficient way of guiding cooling air is disclosed. This cooling method uses fan housing and a deflector mechanism wherein both the fan hosing and the deflector surround the engine and they both are connected to each other by a snap fit mechanism. Another embodiment of the current invention discloses the placement of sealing material in between the housing cover and the top fin of the cylinder block or lowermost fin of the cylinder head. The lowermost portion of the cylinder head is made to have a fin-like material projection. This way, the sealing material is placed on the fan housing and the deflector top edge and is pushed towards the top fin of the cylinder block or the lowermost fin-like material projection on the cylinder head.

[0006] The current invention utilizes the wedge shaped portion of the cylinder head and the cylinder block for providing better sealing effect.

BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 Shows a typical diagram of a two wheeler vehicle.

[0008] Figure 2 Illustrates flow of air inside an engine of a typical two wheeler vehicle.

[0009] Figure 3 Shows the cross sectional view of engine illustrating the deflector and fan housing side.

[00010] Figure 4 Illustrates the sealing mechanism on the fan hosing side on the engine.

[00011] Figure 5 Illustrates the sealing mechanism on the deflector side on the engine.

[00012] Figure 6 Shows a close up view of sealing mechanism on the fan hosing side on the engine.

[00013] Figure 6 Shows a close up view of sealing mechanism on the deflector side on the engine.

DETAILED DESCRIPTION OF THE INVENTION

[00014] A two-wheeled vehicle with engine has been shown in Figure 1. A swinging engine unit 14 is arranged in substantially central lower portion of the side frames. The crank case of such a vehicle, as described in the invention has a V-belt drive CVT which is arranged in the lower part of the engine unit towards the rear wheel. This packing of CVT engine is visible from one side of the vehicle, while, the other side of the engine shows the cylinder head and cylinder block portion of the same engine. The V-belt drive CVT is housed between a transmission case and the crankcase. Normally the engine is to be provided with cooling mechanism on both the CVT engine side and the cylinder head and cylinder block side. There are many methods for achieving the cooling of the engine from the CVT side. The cooling arrangement as per the present invention is provided on the cylinder block and cylinder head portion of the engine. As it is shown in the figure, most of the part of the engine is covered by style parts and vehicle frame, footboard and the front cover. Natural air is obstructed from passing directly to the engine when vehicle is moving. Hence, there is a need for providing forced air-cooling for the cylinder head and the cylinder block for dissipating the large amount of heat generated during the process of combustion of fuel inside the engine.

[00015] The vehicle as shown in Figurel has a front body part 16, front suspension 17, front wheel 11 and rear 15, footboard 12, style part 13 and engine 14. By arranging a cushion between the engine unit and the rear part of the body frame, rear suspension is provided for the scooter. A pillion handle is attached to the rear end of side frames. Furthermore, a tail lamp is arranged below the pillion handle. A portion between the seat and the head pipe is provided with a low step floor on which a rider puts both feet is arranged in a bottom portion thereof. Also the step floor is arranged so as to cover a horizontal portion of the down tube from the above and is fixed to the down tube. A side stand is a provided upright and inclined slightly leftward.

[00016] Figure 2 shows the cover mechanism and housing mechanism for the fan and the engine. This housing mechanism consists of a provision for air entry 21, the said air that enters the housing mechanism through the inside of the fan cover 22 is guided towards the cylinder head. The airflow path after the air enters the fan cover 22 gets diverted into two paths namely path 23 and path 24. Path 23 surrounds the cylinder head and the air following the air path 23 takes a longer time and travels a longer distance as compared to the air, which follows the path 24. There is a provision shown in Figure 2 for air exit opening 29. The air following the air paths 23 and 24 exits out of the deflector after cooling the engine from the opening 29. The complete housing can be divided into three parts namely the fan cover 22, fan-housing 27 which extends from the end of the cover fan 22 till the fastening mechanism 270F on the lower side and 280F on the upper side and the deflector 28. The provision for fastening the fan housing to the other side covering called as deflector is done through the fastening mechanism 270D and 270F. In the nomenclature, the 270D indicates the deflector part of lower fastening mechanism of fan housing and deflector. Similarly, 280D indicates the deflector part of upper fastening mechanism of fan housing and deflector. The fastening provisions 270D, 270F & 280D, 280F are provided on both the sides of the fan housing. Such fastening mechanism may be present on atleast one location and as many as four locations in this invention.

[00017] The invention cools the cylinder head part of the engine considerably by providing better flow of air and at the same time providing better sealing mechanism so that the air entering the fan housing travels maximum distance thereby absorbing maximum heat and thereby exiting the housing after getting heated and consequently, new cooler air enters through the fan and again passes through engine fins which becomes a continuous process.

[00018] Figure 3 illustrates the cross section of the engine, with fan housing cross section and deflector cross section. This figure demonstrates the mechanism of placing the sealing material 42 and 51 below and above the topmost fin of the cylinder head on the fan housing and deflector side respectively, for providing better sealing mechanism for improved cooling efficiency of the described mechanism. In Figure 3, the sealing material 51 is of the deflector side, is designed and is placed on and above the fin 31 in such a way that the deflector portion 52 is made a projection at the end which hooks and fastens into the rubber sealing material. The embodiment 53 shows the wedging mechanism to grip the headings towards each other and to provide the tight sealing.

[00019] In Figure 3 on the other side, it shows the fastening mechanism of the sealing material 42 and the fan housing 43 end from the bottom side of the cylinder head fin 31. It is to be noted that in both the fastening mechanisms of the deflector and the fan housing, for the deflector side fastening and securing of the sealing material on the fin, and the deflector in between the sealing material, the sealing material 51 is placed on the top of the fin whereas in fan housing, the sealing material secures the fan housing from below side of the cylinder head fin.

[00020] Figure 4 shows the fan housing side fastening and sealing mechanism between the fan housing 43 and the sealing material 31. Figure 4 when read with Figure 6, it shows the closer view of the sealing mechanism. In both he figures, 31 is the top cylinder head fin, 42 is the sealing material and 43 is the housing fan. The housing fan is covering half of the cylinder head from one side as shown in Figure 4. The topmost cylinder fin 31surrounds the complete cylinder head with the sealing material 42 being below of the said fan housing side and thereby fastening the housing fan in that half. Multiple ribs also called as fins like cylinder head fin 43 help in dissipating heat from the fins to the outer atmosphere.

[00021] Figure 5 shows the deflector side mechanism of fastening of the deflector 28 on the cylinder head fin 31 from top side of the cylinder head fin 31 using the sealing material 51 which secures the fastening or securing end of the deflector 28 shown as 52. The securing end 52 of deflector 28, can be more explicitly visualized in the Figure 7. The deflector securing end 52 is designed in such a way that it gets hooked to the sealing material 51, and this securing material 51 gets placed on the top of the cylinder head fin. The fastening mechanisms 280D on the upper and lower part of the deflector, fastens the deflector and the housing fan so that the fan housing 27 and the deflector 28 are pulled towards each other thus giving a very tight sealing effect on the cylinder head fin. The slanting effect of the cylinder head fin as can be seen in Figure 4 and Figure 6 produces a wedge shaped faceoff between the fan housing and the deflector thus adding to the sealing effect of the cylinder head. The current invention utilizes the wedge shaped mating of the deflector and fan housing with the corresponding gaskets above and below the top cylinder fin respectively.

[00022] In the arrangement as per the present invention, the sealing means 51 and 42 is not secured to the slanted fin 313 and is secured only to the fan housing 43 and the deflector 52. When the fan housing 43 and the deflector 52 is fastened together, the sealing means 51 and 42 butts on to the slanted fin 31 at a convenient position and seals the interface. Such an arrangement reduces assembly time. Further, there is substantial reduction in material cost of the sealing means when compared to prior art arrangements in which the sealing means is secured both to the shroud as well as to the slanted fin. Manufacturing cost is further reduced since the shroud is secured to the sealing means by way of a snap fit, hence avoiding the use of costlier sealants. The present invention allows the slanted fin of the cylinder head to be larger in size in comparison to that used in the prior art. There is therefore improved cylinder head cooling which further cools the intake air entering the cylinder block which in turn improves the volumetric efficiency of the engine thus enhancing the overall efficiency of the engine.

[00023] Due to the above described arrangement, when the fan housing 43 and the deflector 52 is fastened together during engine assembly (as illustrated in Figure 3 and Figure 8 ), there is a wedging action caused at the interfaces between the fan housing 42 and the slanted fin 31 and that between the deflector 52 and the slanted fin 31. This wedging action 53 shown in Figure 8 results in sandwiching of the sealing means 51 and 42 between the slanted fin and the shroud thereby leading to hermetic sealing of the interface between the slanted fin 31 and the shroud. The side of the sealing means 51 and 42 which comes in contact with the slanted fin 31, is corrugated and this further enhances the sealing properties of the system. The sealing means 51 and 42 is provided around the outer peripheral surface of the cylinder head and near the mating surface between the cylinder head and a cylinder head cover. The sealing means 51 and 42 are preferably comprised of two semi annular elastic rubber headings.

We Claim:

1. A forced air cooled internal combustion engine comprising:

a cylinder head;
a cylinder block;
a cooling fan which draws cooling air from outside for cooling the cylinder head and cylinder block;

a slanted fin formed at the cylinder head top surface, the said slanted fin further comprising a housing side fin and a deflector side fin wherein the housing side fin is coplanar with the cylinder head top surface and the deflector side fin is parallely offset downward from the housing side fin;

a shroud which surrounds the cylinder head and the cylinder block and guides cooling air from the cooling fan, the said shroud further consists of a fan housing and a deflector such that the said fan housing forms a T-joint with the bottom side of the housing side fin and the said deflector overlaps the deflector side fin at its top; and

a sealing means provided at the interfaces of the fan housing and the deflector with the slanted fin, the said sealing means secured to the fan housing and the deflector by a snap fit;

wherein wedging action is caused at the interfaces of the fan housing and the deflector with the slanted fin, when the fan housing and the deflector is fastened, resulting in sandwiching of the sealing means between the shroud and the slanted fin.

2. The forced air cooled internal combustion engine as claimed in claim 1 wherein the sealing means is provided around the outer peripheral surface of the cylinder head and near the mating surface between the cylinder head and a cylinder head cover.

3. The forced air cooled internal combustion engine as claimed in claim 1 wherein the sealing means is preferably comprised of two semi annular elastic rubber headings.

4. The forced air cooled internal combustion engine as claimed in claim 1 wherein the fan housing extends from the cooling fan to the slanted fin and covers one half portion of the cylinder head and cylinder block and the deflector covers the other half portion.

5. The forced air cooled internal combustion engine as claimed in claim 1 wherein corrugations are formed on a side of the sealing means, the said side which comes in contact with the slanted fin.

6. The forced air cooled internal combustion engine as claimed in claim 1 wherein the deflector side fin is parallely offset downward from the cylinder head top surface by an amount equal to the cross sectional thickness of the overlap of deflector and the sealing means with the slanted fin.

7. The forced air cooled internal combustion engine as claimed in claim 1 wherein the two halves mainly, the said deflector and the said fan housing are joined to each other by use of fasteners.

8. The forced air cooled internal combustion engine as claimed in claim 1, wherein the ends of the said deflector and the said housing fan are both secured inside the groove of the sealing material.