FIELD OF THE INVENTION

This invention relates generally to valve trains and more specifically to a means to control and vary the timing of valves in internal combustion engines.

BACKGROUND OF THE INVENTION

Present day internal combustion engines suffer 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. Obviously, for more efficient engine operation, the reverse would be preferable that valves remain open 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, while a shorter valve event at lower speeds would serve to curtail power loss and to lessen the emission of unburned hydrocarbons. In practice, valve settings are always a compromise being efficient in some middle range but losing efficiency markedly in the high and low speed ranges.

Accordingly, the present invention provides a simple and durable means of making variable the valve event in an internal combustion engine. The object of the present invention is to provide an improved valve operating mechanism for an internal combustion engine which serves to vary the valve events.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a cam shaft having two intake cam lobes having different profiles. The cam shaft is driven by the crank shaft. A slidable locking device is provided in the cylinder head cover that locks the selected cam lobe with the corresponding cam follower to operate the valve. The cam lobe having suitable profile is selected based on the engine speed. In one of the preferred embodiment an electric motor is used to actuate the slidable locking device.

Other and further objects of the invention will become apparent to those skilled in this art from the following description of the annexed sheets of drawings which by way of preferred example only, illustrate several embodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts a motorcycle embodying the present invention.

Figure 2 depicts the intake and the exhaust valve arrangement along with the camshaft.

Figure 3 depicts the camshaft having three cam lobes.

Figure 4 depicts an embodiment of the present invention.

Figure 5 depicts the rocker arm used in the embodiment depicted in figure 4.

Figure 6 depicts the third link used in embodiment depicted in figure 4.

Figure 7 depicts the threaded shaft used in the embodiment depicted in figure 4.

Figure 8 depicts the first link used in embodiment depicted in figure 4. Figure 9 depicts the cylinder head used in the embodiment depicted in figure 4 along with the electric motor/actuator.

DETAILED DESCRIPTION OF THE INVENTION

With reference to figures a motorcycle 01 having a four-cycle engine 02 is disclosed, the engine 02 uses a valve actuation mechanism as per an embodiment of the present invention.

The said engine 02 is a two-valve engine as an example but without any limitation.
Wherein, one of the said valves^ is configured as intake valve 03 and the other one as exhaust 04. To actuate the said valves a camshaft 05 having three cam lobes is used wherein the first cam lobe 06 and the second cam lobe 07 have different profiles (i.e. second cam lobe having a higher elevation than the first) and are used to actuate the intake valve 03 one at a time based on the requirement, the third cam lobe 08 is used to actuate the exhaust valve 04 and has profile suitable for the actuation of exhaust valve.

As illustrated a first follower component 09 configured to follow the first cam 06 and a second follower component 10 configured to follow the second cam 07, are provided, a slidable locking mechanism is provided to selectively lock one of the said cam lobes with the respective follower components so as to translate the contour of the respective cams into a corresponding actuation of the engine valve 03. The first follower component 09 is a rocker arm 09 rotatable on the rocker shaft 12 laid parallel to the camshaft 05 with the groove 09A, a locking ring with extended strip connected to second follower 10 over groove 09A on first follower 09 hereafter, referred as selector lock 11, the second follower component 10 is a roller and is also connected to selector lock 11, the selector lock 11 extends towards the second follower 10. Selector lock 11 used that connects the said rocker arm 09 and second follower 10 through taper surface on said selector lock 11 and on second follower 10 by moving axially. The axial movement is controlled by mechanical, electrical, hydraulic based on engine speed and driver demand. The selector lock 11 is connected to second follower 10 with a gap 13. The gap is reduced when the selector lock axially moved and transfers the contour of second cam 07, when it is moved back the gap 13 increases and the selector lock 11 idling within the gap 13, and transfers contour of first cam lobe 06. Thus, by axial movement of the selector lock 11 one of the cam lobes is selected. The said selection can be made on the basis of the speed parameters and can be regulated by the output of the speed sensor or the like and further, the same mechanism can be used for actuating the exhaust valves also with suitable adaptations.

The whole assembly is housed in the cylinder head 14 and cover cylinder head 15 of the engine. In the present embodiment a stepper motor is preferred. Further, a spring is provided on the end 10 of the second follower to ensure component 10 remains in operable relation with the second cam lobe 07.

It should also be noted that the configuration according to the above-mentioned embodiment is an example of the present invention. The invention can also be employed in other kinds of engines, such as multi cylinder and various modifications may be made therein without departing from the spirit of the present invention.

WHAT IS CLAIMED IS

1) A valve actuation system for an engine, comprising:

a) a plurality of valve defining at least one intake valve and at least one exhaust valve;

b) a camshaft having at least one first cam with a first cam lobe, at least one second cam shaft with a second cam lobe and a third cam lobe such that the second cam lobe has higher elevation than the first cam lobe;

c) a first follower component configured to follow the first cam and a second follower component configured to follow the second cam; and

d) a slidable locking device, secured in a cylinder head cover configured to lock the first cam lobe with the first follower component and the second cam lobe with the second follower component and is activated by an actuator.

2) The valve actuation system, as claimed in claim 1, wherein the slidable locking device is locking the first cam lobe with the first follower component to translate the contour of the first cam into actuation of the plurality of valve in the direction of movement of first follower component.

3) The valve actuation system, as claimed in claim 1, wherein the slidable locking device is locking the second cam lobe with the second follower component to translate the contour of the second cam into actuation of the plurality of valve in the direction of movement of second follower component.

4) The valve actuation system, as claimed in claim 3 and claim 4, wherein the slidable locking device is locking the first cam lobe with the first follower component and the second cam lobe with the second follower component in one by one sequence under predefined condition.

5) The valve actuation system, as claimed in claim 1, wherein the third cam lobe is configured to actuate the exhaust valve.

6) An internal combustion engine having a valve actuation system, comprising

a) A cylinder head;

b) An actuator secured over the cylinder head;

c) a plurality of valve defining at least one intake valve and at least one exhaust
valve;

d) a camshaft having at least one first cam with a first cam lobe, at least one second cam shaft with a second cam lobe and a third cam lobe such that the second cam lobe has higher elevation than the first cam lobe;

e) a first follower component configured to follow the first cam and a second follower component configured to follow the second cam; and

f) a slidable locking device, secured in cover of the cylinder head configured to lock the first cam lobe with the first follower component and the second cam lobe with the second follower component and is activated by the actuator.

7) The internal combustion engine, as claimed in claim 6, wherein the slidable locking device is locking the first cam lobe with the first follower component to translate the contour of the first cam into actuation of the plurality of valve in the direction of movement of first follower component.

8) The internal combustion engine, as claimed in claim 6, wherein the slidable locking device is locking the second cam lobe with the second follower component to translate the contour of the second cam into actuation of the plurality of valve in the direction of movement of second follower component.

9) The valve actuation system, as claimed in claim 6 and claim 7, wherein the slidable locking device is locking the first cam lobe with the first follower component and the second cam lobe with the second follower component in one by one sequence under predefined condition.

10) The internal combustion engine, as claimed in claim 6, wherein the third cam lobe is configured to actuate the exhaust valve.