Field of Invention

[0001] The present system relates to an improved lubrication system for an internal combustion engine and more particularly, to a lubrication system that distributes lubricating oil advantageously to main bearings of the crankshaft and other parts of crankcase which otherwise are difficult to lubricate.

Description of Prior Art

[0002] An internal combustion engine is composed of many moving parts, which have to be lubricated thoroughly to minimize the mechanical friction at the time when internal combustion engine is in operation. Some of the mandatory parts that require lubrication are piston, cylinder, crankshaft, connecting rod and main bearings etc. To supply lubricating oil to the pertinent elements of engine, an oil pump is driven by a crankshaft. The oil pump delivers lubricating oil collected in an oil sump at the bottom of the engine through a slinger or a lubrication oil circuit. The aforementioned system however becomes ineffective under various operating conditions, for example when the motorcycle is in tilted position. Further in the conventional arrangement, certain parts of the engine are not adequately lubricated such as the inner race of the main bearing of the crankshaft. Inadequate lubrication of main bearing may result in main bearing failure, which consequently increases crank noise and engine vibrations. The lubrication system aforementioned delivers oil to engine portions that need lubrication but the system currently employed never ensures appropriate distribution of lubricating oil as per the requirement of the component. For example crankshaft portion needs more lubrication oil than the cylinder head portion. Hence this inadequacy in existing system makes it ineffective sometimes during the operation of internal combustion engine.

[0003] Further it has been observed during empirical analysis of the crankpin, that in many cases, spalling occurs due to inadequate lubrication of the crankpin, which is another drawback of the conventional lubrication system.

[0004] It would therefore be highly desirable to have a lubrication system, which ensures sufficient lubrication of the main bearing of the crankshaft, that which prevents spalling of the crankpin and that which enables adequate lubrication of all engine parts.

Summary of Invention

[0005] The present invention has been conceived in view of the foregoing drawbacks in the prior art and it is the primary objective of the present invention to provide a lubrication system, which enables adequate lubrication of the main bearings of the crankshaft of the internal combustion engine. It is another objective of the present invention to provide an arrangement, which prevents spalling of the crankpin. It is another of the present invention to provide a lubrication system, which ensures sufficient lubrication of all engine parts and components.

[0006] The present invention is characterized by a lubricating channel formed longitudinally across the crankpin of the engine. The
crankpin lubricating channel extends substantially axially across the
crankpin. Metering jets are formed on both the ends of the crankpin lubricating channel. The metering jets are configured to direct lubricating oil to an inner race of the crankshaft main bearings. The main bearing
rotatably mount the crankshaft to a crankcase.

The present invention is also characterized by a contoured recess formed on the outer peripheral
surface of the crankpin. The contoured recess enhances lubrication of the crankpin and thereby prevents spalling. Hence the present invention
does away with drawbacks in the prior art due to inadequate lubrication of the main bearing and spalling of the crankpin. Therefore crank noise
and engine vibrations are reduced. Further main bearing wear is reduced and vehicle driving comfort is enhanced.

[0007] 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 limit the scope of the claimed
subject matter.

Brief Description of Drawings

[0008] 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:

Fig. 1 illustrates a side view of a convention two-wheeled vehicle.

Fig. 2 illustrates a cross sectional view of the internal combustion engine as per the present invention.

Fig. 3 illustrates a cross sectional view of the crankshaft assembly as per the present invention
Fig. 4 illustrates a cross sectional view of the crankshaft as per the present invention.

Fig. 5 illustrates a cross sectional view of the crankpin as per the present invention.Detailed Description of Invention

[0009] The present invention is hereinafter described with reference to the accompanying drawings. It is to be noted that like reference numerals designate corresponding or identical elements
throughout the various drawings. The terms front and rear, and left and right as used indicate the front and rear and the left and right directions when viewed by a rider seated on the vehicle seat. The present invention is described herein as including a four-stroke single cylinder engine. However the invention is capable of being used in any number of cylinders. Therefore the reference is made only to the present embodiment (i.e. single cylinder engine) and before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

[0010] Fig. 1 illustrates a side view of a conventional two-wheeled vehicle. It includes a front wheel 2, a rear wheel 3, an internal combustion engine 11, and a body frame 5. A front fork 8 and a handlebar 7 is mounted to the body frame 5 for rotation. The front wheel 2 is mounted to the front fork 5 and the rear wheel 3 is mounted to the body frame 5. The motorcycle also includes a steering assembly 6 coupled to the frame 5. The steering assembly 6 is pivotable about a steering axis and the handlebar 7 for imparts such pivotal motion to the steering assembly 6.

[0011] Fig. 2 is a sectional view of an internal combustion engine incorporated with the present invention. Fig. 2 demonstrates a four stroke, single cylinder engine which includes a piston 15 arranged in the cylinder chamber, said piston 15 drives a crankshaft 23 arranged in a crankspace 27 by way of a connecting rod 30. A small end 29 of the connecting rod 30 is connected to piston 15 through a piston pin 31 and a big end 28 is connected to the crankshaft 23 through a crank pin 39.The crankshaft 23 is rotatably mounted to a crankcase 45 by a pair of main bearings 56 & 60.

[0012] An oil sump 50 is positioned at the bottom of crankcase 45. Oil sump 50 is a portion of crank space 27 and is aided with an oil pump (not shown in figure). The oil pump delivers the oil to the consuming elements of the engine such as camshaft bearing, cylinder running surface, crankshaft, piston, connecting rod and cylinder head etc. The oil supplied to various parts of the engine 11 returns back to the oil sump 50 due to gravitational pull. The oil pump 50 pumps the oil in the lubrication circuit 65.

Lubrication circuit 65 constitute of various oil path of variable diameters, the occupation bestowed upon the variable diameter circuit is to distribute oil flow to the critical elements of engine 11. Additionally this lubrication circuit is fitted with oil nozzles to maintain pressure and oil requirements at critical positions of internal combustion engine. The lubrication circuit 65 communicates with engine components through communication holes provided on the engine components.

[0013] Fig. 3 illustrates a side view of a crankshaft assembly as per the present invention. The crankshaft 23 is rotatably mounted to the crankcase 45 by way of main bearings 56 & 60. The crankshaft 23 comprises a crankpin 39, a first crankshaft element 21 and a second crankshaft element 22. The crankpin 39 couples the first crankshaft element 21 and the second crankshaft element 22. In the present invention, the crankpin 39 is characterized by a crankpin lubricating oil channel 70. The crankpin lubricating oil channel 70 extends longitudinally and substantially axially across the crankpin 39. The crankpin lubricating oil channel 70 is provided with metering jets 90 & 95 at both its sides. The metering jets 90 & 95 direct lubricating oil to the mnner race of main bearings 56 & 60. Lubricating oil enters the crankpin lubricating oil channel 70 from the crankshaft lubricating oil channel 75. The lubricating oil then passes through the openings 80 & 85 before entering the metering jets jets 90 & 95. The metering jets 90 & 95 ensure supply of lubricating oil in sufficient quantity and pressure to the inner race of the main bearings 56 & 60.

[0014] Fig. 4 is a cross sectional view of the first crankshaft element. It is to be noted that the second crankshaft element 22 is
structurally and functionally identical to the first crankshaft element 21.

For the sake of explanatory convenience only the first crankshaftelement 21 is described and an identical mechanism for lubrication can
be incorporated in the second crankshaft element 22 as well.

[0015] As shown in Fig. 4 the first shaft element 21 is provided with a bearing mounting space 100 to rotatably support the bearing 56 and a crank web 105 integrally forged at the end of bearing mounting space 100.The said crank web 105 is further equipped with counter weight and a cylindrical aperture 110 for mounting the crank pin 39. The cylindrical aperture 110 contains the dyadic opening 115a through which lubricating oil flows from the crankshaft lubricating oil channel 75 to the crankpin lubricating oil channel 70. The crankshaft lubricating oil channel 75 is connected to the main lubricating circuit through known means.

[0016] Fig. 5 illustrates a cross sectional view of the crankpin 39 as per the present invention. A dyadic opening 115b complementary to the dyadic opening 115a is formed on the crankpin 39 for lubricating oil flow into the crankpin 39. A contoured recess 150 is provided on the outer peripheral surface of the crankpin 39. The contoured recess 150 acts as a bulwark and prevents material erosion of the crankpin 39 and therefore eliminates spalling.

[0017] The foregoing description is a specific embodiment of the present invention and has been described for the purpose of illustration only. Persons skilled in the art may practice numerous alterations and modifications of the present invention without departing from its spirit and scope. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We Claim:

1. A crankshaft 23 for an internal combustion engine, said crankshaft 23 rotatably mounted to a crankcase 45 by a pair of
main bearings 56 & 60, said crankshaft 23 comprising a crankpin 39 characterized by:
a contoured recess 150 formed on its outer peripheral surface; and atleast one crankpin lubricating oil channel 70 extending longitudinally through said crankpin 39, said lubricating oil
channel 70 having metering jets 90 & 95 at both ends, said metering jets 90 & 95 configured to direct lubricating oil to an
inner race of the main bearings 56 & 60.

2. The crankshaft 23 for an internal combustion engine as claimed in claim 1, wherein said crankshaft 23 further comprises a first crankshaft element 21 and a second crankshaft element 22, said first crankshaft element 21 having a crankshaft lubricating oil channel 75 which communicates to the crankpin lubricating oil channel 70 through dyadic openings 115a & 115b.

3. The crankshaft 23 for an internal combustion engine as claimed in claim 1, wherein said crankshaft 23 further comprises a first crankshaft element 21 and a second crankshaft element 22, said second crankshaft element 21 having a crankshaft lubricating oil channel 75 which communicates to the crankpin lubricating oil channel 70 through dyadic openings 115a & 115b.

4. The crankshaft 23 for an internal combustion engine as claimed in claim 1, wherein the crankpin lubricating channel 70 extends axially through the crankpin 39.

5. A two-wheeled automotive vehicle comprising a body frame 5;

a front fork 8 and a handlebar 7 mounted for rotation on the body frame 5; a front wheel 2 mounted to the front fork 8; a rear wheel 3 mounted to the body frame 5; an internal combustion engine 11 mounted to the body frame 5,
said internal combustion engine 11 comprising a crankshaft 23, said crankshaft 23 rotatably mounted to a crankcase 45 by a pair of main bearings 56 & 60, said crankshaft 23 further comprises a crankpin 39 characterized by:
a contoured recess 150 formed on its outer peripheral surface; and atleast one crankpin lubricating oil channel 70 extending
longitudinally through said crankpin 39, said lubricating oil channel 70 having metering jets 90 & 95 at either of its ends, said
metering jets 90 & 95 configured to direct lubricating oil to an inner race of the main bearings 56 & 60.

6. The two-wheeled automotive vehicle as claimed in claim 5, wherein said crankshaft 23 further comprises a first crankshaft element 21 and a second crankshaft element 22, said first crankshaft element 21 having a crankshaft lubricating oil channel 75 which communicates to the crankpin lubricating oil channel 70 through dyadic openings 115a & 115b.

7. The two-wheeled automotive vehicle as claimed in claim 5, wherein said crankshaft 23 further comprises a first crankshaft element 21 and a second crankshaft element 22, said second crankshaft element 21 having a crankshaft lubricating oil channel 75 which communicates to the crankpin lubricating oil channel 70 through dyadic openings 115a & 115b.

8. The two-wheeled automotive vehicle as claimed in claim 5, wherein the crankpin lubricating channel 70 extends axially through the crankpin 39.

9. The crankshaft for an internal combustion engine as hereinabove described in the specification and illustrated in the accompanying drawings.