SHROUD FOR AN INTERNAL COMBUSTION ENGINE

FIELD OF THE INVENTION

[0001] The present subject matter relates generally to an internal combustion engine, and more particularly, to a shroud for aiding in cooling of an air cooled internal combustion engine.

BACKGROUND OF THE INVENTION

[0002] Generally, air cooled internal combustion engines are of two types: natural air cooled and forced air cooled. A forced air cooled internal combustion engine is partially covered with a shroud for proper cooling of the engine. The shroud has an air inlet anterior to and surrounding a centrifugal fan mounted on the crankshaft of the engine from where the atmospheric air is sucked in by the rotating fan. The incoming air is then radially pushed towards the engine cylinder and moves around the cylinder block as directed by the shroud profile. The circulating air reduces the high temperature of the cylinder walls caused by virtue of work done by the engine and hence cools the engine, particularly the cylinder block and cylinder head. After cooling, the circulating air becomes heated and the resultant hot air moves out of the shroud through an air outlet provided therein.

[0003] The air outlet area is generally kept small to approximately half the diameter of the centrifugal fan so that the air entering the upper portion of the shroud surrounding the cylinder block enters at a higher velocity. But the increased incoming air velocity leads to overshooting of the air flow around the cylinder block due to which a part of the incoming air is short circuited through the upper shroud air outlet. The resultant uneven cooling of the engine, mainly cylinder block, causes cylinder block overheating which further leads to piston liner scouring due to reduction in piston ring clearance. In addition to that, other implications include engine lubricant burning, piston ring sticking and piston under crown colouring thereby leading to an inefficient or disfunctional engine. High temperature gradient across the cylinder block is yet another consequence of uneven cooling of the engine.

[0004] Thus, in order to improve the performance and durability of such an engine, temperature of cylinder block should not go beyond a threshold value. The profile of the shroud should ensure that the incoming air spreads to all the corners of the cylinder head thereby uniformly cooling the engine.

[0005] Hence the present subject matter is directed to overcome all or any of the problems as set forth above and obviate the lacunae in the prior art. Therefore, it is an object of the present subject matter to disclose a shroud for uniform cooling of a forced air cooled internal combustion engine, particularly cylinder block, for improving the performance and durability of the engine. It is another object of the present invention to provide a shroud for an internal combustion engine to eliminate the short-circuiting of usefql incoming air to the exhaust in order to facilitate optimum and even cooling of the engine cylinder block and cylinder head. It is a further object of the present invention to define an air passage inside a shroud for an internal combustion engine for even cooling of the engine thereby increasing its durability.

SUMMARY OF THE INVENTION

[0006] To this end, the present subject matter discloses a shroud for an air cooled internal combustion engine comprising a lower shroud and an upper shroud connected to each other through a known joining mechanism. The lower shroud substantially covers a cooling fan and comprises a lower shroud air inlet covered with grating and a lower shroud air outlet at the periphery of the lower shroud whereas the upper shroud substantially conceals a cylinder head of the internal combustion engine and comprises an upper shroud air inlet and an upper shroud air outlet. The shroud is characterized in that an air deflector is provided proximately to the upper shroud air inlet to prevent short circuiting of the air directly towards the upper shroud air outlet.

[0007] According to an aspect of the present invention, the lower shroud air outlet area is increased, the upper shroud air inlet area increased proportionately to the lower shroud air outlet area to improve the air flow and the peripheral area of the upper shroud is increased by radially extending the upper shroud outward creating a crater around the peripheral profile of the upper shroud to accommodate more air flow around the cylinder block and allow uniform cooling of the internal combustion engine including the cylinder head.

[0008] According to another aspect of the present invention the upper shroud further comprises of a bent from where the circulating air is directed towards the upper shroud air outlet.

[0009] 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 subject matter and the claims should be read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[00010] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description, appended claims and accompanying drawings where:

FIG. 1 shows a side view of a typical three wheeled passenger carrier vehicle.

FIG. 2 shows the front view of the three wheeled passenger carrier vehicle.

FIG. 3 is a rear view of the three wheeled vehicle showing the internal combustion engine mounted on the posterior side of the three wheeled vehicle.

FIG. 4 illustrates a side perspective view of a typical uncovered internal combustion engine assembly.

FIG. 5 illustrates a perspective view of a shroud partially covering an internal combustion engine according to an embodiment of the present invention.

FIG. 6 depicts the different views of a lower shroud according to an embodiment of the present invention.

FIG. 7 shows a top view of the upper shroud as per the present invention.

FIG. 8 shows a bottom view of the upper shroud according to the present invention.

FIG. 9 depicts a sectional side view of the internal combustion engine covered by the shroud describing the incoming air flow.

FIG. 10 shows the sectional top view of the present invention describing the circulating air movement.

FIG. 11 shows a comparative graph for cylinder block temperatures with the proposed shroud and the prior art shroud.

DETAILED DESCRIPTION OF THE INVENTION

[00011] The subject matter described herein relates to a shroud for an internal combustion engine. In the ensuing exemplary embodiment of the present invention, the vehicle is a three wheeled passenger carrier vehicle. However it is contemplated that the concepts of the present invention may be applied to other types of vehicles such as a scooter, motorcycle or moped within the spirit and scope of this 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 vehicle. Furthermore, a longitudinal axis refers to a front to rear axis relative to the vehicle, while a lateral axis refers generally to a side to side, or left to right axis relative to the vehicle. Various other features and embodiments of the shroud according to the present subject matter here will be discernible from the following further description thereof, set out hereunder.

[0001] FIG. 1 describes a side view of a concerned three wheeled passenger carrier vehicle, referenced by the numeral 100, and driven by an internal combustion engine. The vehicle is laterally divided into two halves, along the axis X-Y, an anterior portion A having the driver's seat 107 while a posterior portion P has a long passenger seat 108 with a seating capacity of minimum three passengers. The anterior portion A has a front cowl 101 along with a windscreen 102. The lower portion of the front cowl 101 is connected to a front wheel 104 with a wheel cover 103 stationed in between. A handle bar assembly 109 is present behind the front cowl 101 which is used to operate the said three wheeled vehicle 100. In this view, a steering tube assembly 111 connected to the handlebar is not visible to an onlooker of the vehicle. Meanwhile, a rear compartment 106 is present in the posterior portion P of the vehicle below the passenger seat 108 and supported on a pair of rear wheels 105 located on either side of the longitudinal axis of the vehicle 100. Below the passenger seat, an internal combustion engine 300 is located used to power the vehicle.

[00012] FIG. 2 illustrates the front view of the three wheeled vehicle with the panels and styling parts removed. The said three wheeled vehicle 100 is supported on a frame structure spanning from the first half to the second half of the vehicle.

A front fork steering column assembly is connected to the front wheel 104 and comprises a steering column assembly, front suspension 203 and a trailing arm 204. The steering column assembly comprises of a steering column tube 202, rotatably supporting the front wheel 104 and acting as a mechanical link between a handle bar 109 and the front wheel 104. The steering column tube 202 is engulfed by a head pipe 205 on all sides and welded or secured to the head pipe. The head pipe usually houses bearings that allow the steering tube to turn freely. A clutch actuation lever 111 is pivotally mounted at a distal end of the handle bar 109 preferably on the left side thereof, such that the user may grip the handle bar to change the gear ratio by retracting and releasing the clutch actuation lever 111.

[00013] FIG. 3 shows the rear view of the said three wheeled vehicle 100 with the rear panel removed and hence showing the otherwise invisible internal combustion engine 300 mounted on the posterior side of the vehicle frame below the passenger seat 108. The internal combustion engine 300 produces the necessary power which is then transferred to the transmission through a clutch (not shown).

[00014] FIG. 4 illustrates a side perspective view of a typical uncovered internal combustion engine assembly of the said three wheeled vehicle 100. Since the basic construction of an internal combustion engine is known to those versed in the art, the details have been omitted. But briefly, the figure illustrates a cylinder head 311, a cylinder block 312, a crank case assembly 313, a muffler 320 and an intake system 310. The said engine 300 has the intake system 310 including an air filter through which the air is sucked in. This air is mixed with fuel and the air-fuel mixture is then ignited in combustion chamber of the engine 300 thereby producing motive power. This motive power rotates a crankshaft (not shown) and is transferred to the wheel(s) through transmission. The transfer of this power from crankshaft to transmission is aided by the clutch positioned inside the crankcase opposite to flywheel (not shown). Further the exhaust gases move out of the combustion chamber during the exhaust stroke by the exhaust system which includes the muffler 320.

[00015] In order to keep the engine temperature within the operating range, particularly that of cylinder block and cylinder head, it is usually force cooled with the help of atmospheric air. This air is sucked in by a cooling fan (not shown) and is directed to move around the cylinder block surface with the help of a shroud so as to cool the heated engine as effective cooling of the engine is necessary for better efficiency. In a preferred embodiment, the cooling fan is a centrifugal fan.

[00016] FIG. 5 shows a perspective view of the internal combustion engine 300 along with the cylinder block substantially covered with the shroud 600 according to the present invention. The shroud 600 surrounds the centrifugal fan mounted on the crankshaft. The movement of the incoming air after it is sucked in by the centrifugal fan is controlled by the profile of the shroud 600 which directs the incoEhing air to all the accessible parts for effective cooling of the engine 300, particularly the cylinder head 311 and cylinder block 312. The shroud 600 is detachably attached to the internal combustion engine 300 and comprises of two parts, namely an upper shroud 500 and a lower shroud 400. The incoming air first enters the lower shroud and is directed to the upper shroud. The shroud 600 is disposed over the engine at the mounting points 404a, 404b thereby attaching the shroud 600 to the engine 300 through a known joining mechanism. In a preferred embodiment, the shroud is detachably attachable i.e. the shroud is not fixed to the engine.

[00017] The upper shroud 500 and the lower shroud 400 are now explained. FIG. 6 depicts different views of the lower shroud 400 as per the present invention. The lower shroud 400 partially covers the lower portion of the engine 300 including the centrifugal fan mounted on the crankshaft. It comprises of a lower shroud air inlet 401 covered with grating and a lower shroud air outlet 403 present at the radial periphery of the lower shroud. The lower shroud air inlet 401 is of the same profile as that of the centrifugal fan to cover the fan. It is transversely disposed on the engine 300.

[00018] Through grating, the said inlet 401 allows the atmospheric air to enter inside the lower shroud 400, when sucked in by the centrifugal fan. The incoming air then exits from the lower shroud 400 towards the upper shroud 500 through the lower shroud air oudet 403. The lower shroud 400 is connected to the upper shroud 500 at a plurality of joining points 402 and is angularly disposed to it. In one of the embodiments of the present invention, the long axis of the lower shroud is approximately perpendicular to that of upper shroud.

[00019] The upper shroud 500 majorly covers the upper portion of the engine 300 including the cylinder block 312 and cylinder head 311. The said upper shroud 500 comprises an upper shroud air inlet 503, an air deflector 505 and an upper shroud air outlet 502a, 502b. The upper shroud 500 is mounted above the lower shroud 400 through a plurality of mounting points 402. The lower shroud air outlet 403 and the upper shroud air inlet 503 define a recess area namely an air passage 504 through which the incoming air after, exiting the lower shroud, passes.

[00020] The profile of the upper shroud 500 is similar to the profile of the cylinder block it covers to orient the incoming air. In an embodiment of the present invention, the profile of the upper shroud is largely circular in order to properly orient the air flow through the shroud around the cylinder block. The upper shroud air inlet 503 receives the incoming air from the lower shroud air outlet 403 and the said incoming air after passing through the air passage 504 progresses around the cylinder block 312 according to the profile of the upper shroud 500. The circulating air after cooling the cylinder block exits the shroud from the upper shroud air outlet 502a, 502b.

[00021] The air deflector 505 provided proximately to the upper shroud air inlet 503 prevents the short circuiting of the air flow directly towards the upper shroud air outlet. It is a small projection projected out from a wall adjacent to the upper shroud air outlet and may be made of any material including plastic resin or metal. The circulating air is further directed by a bent 506 incorporated in the upper shroud towards the cylinder block hot zones 314 for improved cooling of the cylinder block which then moves out towards the upper shroud air outlet.

[00022] Further, in a preferred embodiment, the area of lower shroud air outlet 403 is increased unlike prior art thus providing more air to flow through the air passage 504 for better cooling of the cylinder block 312 of the engine 300. The area of upper shroud air inlet 503 is increased proportionately to the area of lower shroud air outlet 403. Furthermore, the peripheral area of the upper shroud 500 is increased by radially extending the upper shroud outwards, thus creating an additional flow area to increase the air flow around the cylinder block. The additional flow area is a small crater 501 around the peripheral profile of the upper shroud 500 extending from the upper shroud air inlet point to the upper shroud air outlet point. The air flow is thus more uniformly distributed through the cylinder block 312 and the air follows the crater path. FIGS. 9 and 10 show the sectional view of the flow path (indicated by arrows) taken by the incoming air for cooling the engine. The lower shroud, the upper shroud and air deflector respectively may be made of any material including plastic resin. In a preferred embodiment, the shroud as a whole is made of any material including plastic resin.

[00023] The present subject matter and its equivalent thereof offer many advantages, including those which have been described henceforth. The present invention increases the area of the shroud while relaxing the incoming air velocity. The increased lower shroud air outlet area improves the overall air flow of incoming air towards the upper shroud for uniform cooling of the cylinder block by reducing the air flow restriction caused due to previously small lower shroud air outlet area. The extended periphery of the upper shroud in the form of the crater 501 accommodates more air flow around the cylinder block resulting in uniform and efficient cooling. Further, the wastage of incoming air is prevented through the air deflector which directs the incoming air along the air passage and thus enabling better cooling of the engine.

[00024] The profile of the shroud ensures that the incoming air for cooling reaches all the critical parts of the engine covered by the shroud. The present shroud aids better, more efficient and uniform cooling of the engine, particularly the cylinder block and cylinder head, so as to prevent cylinder block overheating and its ramifications. FIG. 11 shows that the overall temperature of the cylinder block is reduced significantly with proposed shroud when compared to the existing one. These temperatures are mapped at several places on the cylinder block walls. The temperature gradient around the block is also minimised.

[00025] The present subject matter is thus described. 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.

We claim:

1. A shroud for an air cooled internal combustion engine, the said shroud comprising a lower shroud and an upper shroud connected to each other through a known joining mechanism,

the lower shroud substantially covering a cooling fan and, comprising a lower shroud air inlet covered with grating and a lower shroud air outlet at the periphery of the lower shroud,

the upper shroud substantially concealing a cylinder head of the said internal combustion engine and comprising an upper shroud air inlet, an upper shroud air outlet,

characterized in that an air deflector provided proximately to the said upper shroud air inlet to prevent short circuiting of the air directly towards the upper shroud air outlet; and,

wherein the lower shroud air outlet area is increased, the upper shroud air inlet area increased proportionately to the lower shroud air outlet area to improve the air flow and,

wherein further, the peripheral area of the upper shroud is increased by radially extending the upper shroud outward creating a crater around the peripheral profile of the upper shroud to accommodate more air flow around the cylinder block and allow uniform cooling of the internal combustion engine including the cylinder head.

2. The shroud for an internal combustion engine as claimed in claim 1, wherein the long axis of the said lower shroud is approximately perpendicular to the long axis of the said upper shroud.

3. The shroud for an internal combustion engine as claimed in claim 1 or claim 2, wherein the upper shroud further comprises of a bent from where the circulating air is directed towards the upper shroud air outlet.

4. The shroud for an internal combustion engine as claimed in claim 1, wherein the atmospheric air enters the shroud from lower shroud air inlet and exits the shroud from upper shroud air outlet after passing through an air passage.

5. The shroud for an internal combustion engine as claimed in claim 1, wherein the said shroud is detachably attachable to the engine.

6. The shroud for an internal combustion engine as claimed in claim 1, wherein the shroud as a whole and its components including the air deflector are made of any material including heat withstanding plastic resin.

7. The shroud substantially as herein described and illustrated with reference to the accompanying drawings.