FIELD OF INVENTION

The invention generally relates to an internal combustion engine and more particularly to a valve actuation mechanism for an internal combustion engine.

BACKGROUND

Generally, internal combustion engine suffers from one very obvious technical defect the faster the engine turns, the shorter the time the valves remain open, since the camshaft and crankshaft make complete revolutions in a fixed relationship.

For more efficient engine operation, the reverse would be preferable that valves remain open for comparative longer time at higher speeds (relative to a complete engine revolution), both to ingest the greater volume of fuel-air mixture and to expel the greater volume of exhaust gases.

Whereas, a shorter valve duration at lower speeds would serve to curtail power loss at higher speed range and higher torque at low speed range and also to lessen the emission of unbumed hydrocarbons by avoiding short circuiting of fuel.

In practice, valve settings are always a compromise being efficient in narrow speed range but losing efficiency markedly in the high and low speed ranges. In order to avoid loss of fuel and make the engine produce continuous (in commuter vehicle) torque output, need to vary the valve opening duration with respect to the speed.

Accordingly, the present invention provides a compact variable valve actuation system for an internal combustion engine which serves to increase the valve timing at higher speed.

SUMMARY

Main objective of the present invention is to provide a compact variable valve actuation system for an internal combustion engine which serves to increase the valve timing at higher speed.

Present invention provides a valve actuation mechanism with a camshaft having a fly weight attached at outer side of the cam shaft disc. This cam shaft further has atleast an exhaust split cam lobe and atleast an intake split cam lobe. The intake split cam lobe further has a primary split cam lobe and a secondary split cam lobe connected through a lift mechanism.

This lift mechanism has multiple spring units placed near exposed ends of the primary split cam lobe and the secondary split cam lobe in a way that spring units are holding parallel ends of connecting units which are passing through and holding the primary split cam lobe and the secondary split cam lobe with a predefined degree of freedom of movement.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawing which is incorporated in and constitute embodiments of the invention, illustrate several aspects of the invention and together with a description of the embodiments serve to explain the principles of the invention and thus, are not limited of the present invention and a brief description of the drawing is as follows:

Figure 1 and Figure 2 are depicting arrangement of the claimed invention over the camshaft of the internal combustion engine.

Figure 3 is presenting the essential embodiments of the invention.

Figure 4 and Figure 5 are describing the enablement and the results of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments disclosed below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described for enablement purpose of the invention. The invention may have application to all types of vehicles. The scope of the invention is entirely based upon the claims provided.

Reference is made to Figure 1 and Figure 2 to describe the arrangement of the embodiments of the claimed invention. Camshaft 101 has a disc 106 on its one end over which a fly weight 107 is fixed through flywheel holder unit 105. Further, on the other end of the cam shaft intake 109 and exhaust 103 cam lobes are secured. Said intake cam lobe 109 is a split cam lobe having a specific lift mechanism 110 used for increasing the valve timing at higher speed as said lift mechanism 110 ensures opening of intake valve for a comparatively longer time.

Further Figure 3, explains the constructional details of the intake lift mechanism 110 of the split cam lobe 109. Said split cam lobe 109 has two parts i.e. primary intake lobe 114 and secondary intake lobe 115 secured adjacent to each other and fixed with connecting units or connecting rods 116, 117 and spring units 112, 113 such that both primary 114 and secondary 115 intake lobes can move in opposite direction and can get back to its original position due to spring action.

As the cam shaft 101 starts rotation a centrifugal force develops which gets amplified due to flyweights 107 fixed on the outer disc 106 of the cam shaft 101. Due to presence of the centrifugal force in the whole unit primary cam lobe 114 and the secondary cam lobe 115 starts moving away (Figure 4) from each other and hence intake time interval increases. Due to spring elements 113, 112 primary 114 and secondary 115 intake cam lobes return back (Figure 4) in their original position.

Figure 5 is describing the visible difference in valve lift duration of the system because of change in crank angle which is nothing but the angle between the primary 114 and secondary 115 intake crank lobe. Hence present arrangement helps in better charge intake and its combustion which results in better efficiency of the engine.

WHAT IS CLAIMED IS

1) A valve actuation mechanism for a four stroke internal combustion engine comprising a camshaft having atleast an exhaust split cam lobe and atleast an intake split cam lobe such that the intake split cam lobe comprises a primary split cam lobe and a secondary split cam lobe connected through a lift mechanism, wherein the lift mechanism comprises a plurality of spring units secured neighbouring exposed ends of the primary split cam lobe and the secondary split cam lobe such that the plurality of spring units is holding parallel ends of a plurality of connecting unit, passing through and holding the primary split cam lobe and the secondary split cam lobe with a predefined degree of freedom of movement.

2) The valve actuation mechanism, as claimed in claim 1, comprises a flyweight unit secured on outer surface of a camshaft disc through atleast one flyweight holder.

3) The valve actuation mechanism, as claimed in claim 2, wherein the flyweight unit is configured to amplify centrifugal force during rotation of the camshaft.