FORM -2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE
Specification
(See Section 10; rule 13)
MULTI STAGE VARIABLE VALVE TIMING AND LIFT CONTROL MECHANISM FOR IC ENGINES
MAHINDRA TWO WHEELERS LIMITED
an Indian Company of Dl Block, Plot No. 18/2 (Part), MIDC, Chinchwad, Pune - 411 019, Maharashtra, India.
INVENTORS
1. AYYAPPATH PRAJOD
2. KHAN SHAHNAWAZ AHMED
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE DISCLOSURE
The present disclosure generally relates to Internal Combustion engines (IC engines).
Particularly, the present disclosure relates to a multi stage variable valve timing and lift control mechanism for Internal Combustion engines (IC engines).
BACKGROUND
Variable valve timing (VVT) or Variable valve actuation (VVA) mechanism is a mechanism used to alter timing, duration and lift of an intake and/or exhaust valves of internal combustion engines (IC Engines). More specifically, VVT or VVA allows lift, duration or timing (in various combinations) of intake and/or exhaust valves to be changed white an IC engine is in operation. The Intake and exhaust valves within an IC engine are used to control flow of intake and exhaust gases into and out of a combustion chamber of the IC engine respectively. Timing, duration and lift of these valves have a significant impact on IC engine performance.
There exists various Variable valve timing (VVT) or Variable valve actuation (VVA) mechanisms in the prior art. These prior art Variable valve timing (VVT) or Variable valve actuation (VVA) mechanisms have numerous limitations. For example, these prior art Variable valve timing (VVT) or Variable valve actuation (VVA) mechanisms are operated by complicated hydraulic, electronic or centrifugal weight arrangement mechanisms to enable to provide continuous variation in these parameters.

Accordingly, there is need of a multi stage variable valve timing and lift control mechanism for IC engines that is simple in construction. Also, there is need of a multi stage variable valve timing and lift control mechanism for IC engines that is easily adaptable on a single cylinder engine but not limited to the single cylinder engine. Further, there is need of a multi stage variable valve timing and lift control mechanism for IC engines that is cost effective. Further there is need of a multi-stage variable valve timing and lift control mechanism which can be accommodates within smaller engines used particularly but not limited to 2 and 3 wheeled vehicles.
OBJECTS
Some of the objects of the present disclosure which at least one embodiment satisfies, are described herein below:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a multi-stage variable valve timing and lift control mechanism for IC engines that is simple in construction.
Also, an object of the present disclosure is to provide a multi-stage variable valve timing and lift control mechanism for IC engines that is easily adaptable on a single cylinder engine.
Additionally, an object of the present disclosure is to provide a multi-stage variable valve timing and lift control mechanism for IC engines that is cost effective.

Another object of the present disclosure is to provide a multi-stage variable valve timing and lift control mechanism for IC engines that is reliable.
Yet another object of the present invention is to provide a multi-stage variable valve timing and lift control mechanism for IC engines that accommodates within small engines used particularly but not limited to 2 and 3 wheeled vehicles.
Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.
SUMMARY
A multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (IC Engine) is disclosed in accordance with an embodiment of the present disclosure. The multi-stage variable valve timing and lift control mechanism includes a rotary drive, a coupling and a linear actuator. The linear actuator is functionally coupled to the rotary drive via the coupling and is actuated by the rotary drive. The linear actuator is mounted on a cam shaft holder of the valve actuation system. The linear actuator includes housing, a screw shaft, at least one pair of spring elements, a locking pin and an actuating pin. The housing is having a centrally disposed internally threaded bore. The screw shaft is centrally received inside the housing, wherein at least a portion of the screw shaft has threads formed on outer surface thereof complimentary to and threadably engaging with the threads of the bore to facilitate relative axial displacement between the screw shaft and the housing as a result of relative angular displacement between the screw shaft and the housing. The spring

elements are disposed inside and confined in the housing and interact with the screw shaft and the housing, wherein either of the spring elements gets compressed as a result of the relative axial displacement between the screw shaft and the housing. The locking pin facilitates relative angular displacement between the screw shaft and the housing. The actuating pin gets displaced as a result of the relative axial displacement between the screw shaft and the housing, wherein the actuating pin selectively engages with a high speed rocker arm and a low speed rocker arm that are functionally coupled to a high speed intake cam lobe and a low speed intake cam lobe to facilitate controlling the valve parameters of the valve actuation system.
Typically, the rotary drive is an electric motor.
Generally, the coupling is a gear transmission arrangement.
Alternatively, the coupling is a belt and pulley transmission arrangement.
Generally, the screw shaft receives drive torque from the rotary drive via the coupling and the angular movement of the housing is locked by the locking pin to facilitate relative angular displacement between the screw shaft and the housing to cause axial movement of the housing and axial movement of the actuating pin functionally connected to the housing such that the actuating pin selectively engages with the high speed rocker arm and the low speed rocker arm.
Alternatively, the housing receives drive torque from the rotary drive via the coupling and the locking pin to facilitate relative angular displacement between the screw shaft and the housing to cause axial movement of the screw shaft and axial movement of the actuating pin functionally connected to the screw shaft

such that the actuating pin selectively engages with the high speed rocker arm and the low speed rocker arm.
Typically, each spring element of the at least one pair of spring elements is a helical compression spring.
Generally, the spring elements are confined in the housing by a bulge formed on the screw shaft and a plunger member forming the housing.
Alternatively, the spring elements are confined in the housing by a pair of end caps and a piston nut threadably engaging with the threaded portion of the screw shaft.
Typically, the multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) further include a torsion spring mounted on a spring bolt for maintaining the high speed rocker arm in contact with the high speed intake cam lobe and the low speed intake cam lobe.
Typically, at low engine speed the actuating pin remains disengaged from the high speed rocker arm and engages with the low speed rocker arm to cause actuation of low speed intake valve.
Similarly, at high engine speed the actuating pin gets engaged with the high speed rocker arm as well as the low speed rocker arm to cause the high speed rocker arm to interact with the high speed intake valve lobe.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The multi stage variable valve timing and lift control mechanism for IC engines of the present disclosure will now be explained in relation to the non-limiting accompanying drawings, in which:
FIGURE 1 illustrates a schematic representation of a multi stage variable valve timing and lift control mechanism for an Internal Combustion Engine (IC engine), in accordance with one embodiment of the present disclosure;
FIGURE 2 illustrates a perspective view a valve actuation system of the multi stage variable valve timing and lift control mechanism of Figure 1, depicting a low speed intake cam lobe, a high speed intake cam lobe, an intake rocker shaft, a torsion spring, an exhaust cam lobe, a lock pin/ actuating pin, a low speed rocker arm, a high speed rocker arm, a torsion spring and a torsion spring bolt;
FIGURE 3a illustrates a perspective view of a special mechanism/ linear actuator of the multi stage variable valve timing and lift control mechanism of Figure 1, in accordance with an embodiment of the present disclosure, wherein housing of the special mechanism/ linear actuator moves relative to a screw shaft to cause a fork secured to the housing to actuate the actuating pin;
FIGURE 3b illustrates a side view of the special mechanism/ linear actuator of Figure 3a;
FIGURE 4 illustrates a sectional view of the special mechanism/ linear actuator of Figure 3a depicting housing, a piston nut, a screw shaft, a Cap A, a Cap B and a pair of compression springs;

FIGURE 5 illustrates a perspective view of the multi stage variable valve timing and lift control mechanism of Figure 1, depicting connection between an electric motor, a gear mechanism, the special mechanism/ linear actuator of Figure 4, an exhaust rocker arm, an exhaust valve, an intake valve, and a fork;
FIGURE 6 illustrates a perspective view of the multi stage variable valve timing and lift control mechanism of Figure 1, depicting the special mechanism/ linear actuator mounted on a camshaft holder of the valve actuation system;
FIGURE 7a illustrates a sectional view of the multi stage variable valve timing and lift control mechanism of Figure 1, depicting the wall A and wall B of the multi stage variable valve timing and lift control mechanism;
FIGURE 7b illustrates the lock pin of the multi stage variable valve timing and lift control mechanism of Figure 1 at low engine speed, wherein the actuating pin remains disengaged from the high speed rocker arm and engages with the low speed rocker arm to cause actuation of low speed intake valve;
FIGURE 8 illustrates a sectional view of the special mechanism/ linear actuator of Figure 3a depicting configuration of the compression springs, the actuating pin, and the piston nut of the multi stage variable valve timing and lift control mechanism at low engine speed, wherein the compression spring is in a compressed configuration and the housing of the special mechanism/linear actuator is in contact with the wall A;
FIGURE 9a illustrates a sectional view of the special mechanism/ linear actuator of Figure 3a depicting configuration of the compression springs, the actuating pin, and the piston nut of the multi stage variable valve timing and lift

control mechanism at high engine speed, wherein housing of the special mechanism/linear actuator is in contact with the wall B;
FIGURE 9b illustrates an enlarged view of the lock pin of the multi stage variable valve timing and lift control mechanism of Figure 1 at high engine speed, wherein the actuating pin engages with the high speed rocker arm as well as the low speed rocker arm to cause actuation of high speed intake valve;
FIGURE 10a illustrates a torque graph for 2 steps of the multi step valve timing of the multi stage variable valve timing and lift control mechanism of Figure 1;
FIGURE 10b illustrates a reference torque graph for 3 stages of the multi step valve timing of the multi stage variable valve timing and lift control mechanism of Figure 1;
FIGURE 11a illustrates position 'A' of the piston nut with respect to the screw shaft, when the first switch i.e. switch 1, is in a pressed condition or a position sensor sensing position 1 (switch or sensor not shown in figure);
FIGURE l1b illustrates the position 'B' of the piston nut with respect to the screw shaft, when the second switch i.e. switch 2, is in a pressed condition or a position sensor sensing position 2 (switch or sensor not shown in figure);
FIGURE 12 illustrates a control logic flow chart for an electric motor control of the multistage variable valve timing and lift control mechanism of Figure 1;
FIGURE 13 illustrates a graph depicting lift variation with respect to cam angles for a low speed cam lobe and a high speed cam lobe of FIGURE 2;

Figure 14 illustrates a sectional view of a multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) in accordance with another embodiment of the present disclosure, wherein the screw shaft is moving relative to the housing to actuate the actuating pin that in-turn causes actuation of the valves by the high speed and low speed intake cam lobes, and at low engine speed the actuating pin remains disengaged from the high speed rocker arm and engages with the low speed rocker arm to cause actuation of low speed intake valve; and
Figure 15 illustrates a sectional view of the multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) of Figure 14 at high engine speed wherein the actuating pin engages with the high speed rocker arm as well as the low speed rocker arm to cause actuation of high speed intake valve.
DETAILED DESCRIPTION
The multi stage variable valve timing and lift control mechanism for I C engines of the present disclosure will now be described with reference to the embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an

understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The description hereinafter, of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The present disclosure provides a multi stage variable valve timing and lift control mechanism for IC engines. A multi stage variable valve timing and lift control mechanism of the present disclosure is simple in construction and thereby easy to manufacture. Also, a multi stage variable valve timing and lift control mechanism of the present disclosure is easily adaptable on a single cylinder engine but not limited in application only to the single cylinder internal combustion engine. Further, a multi stage variable valve timing and lift control mechanism of the present disclosure is cost effective.
Referring to Figures 1 to 13, a multi stage variable valve timing and lift control mechanism 100 is disclosed in accordance with one embodiment of the present

disclosure. The multi stage variable valve timing and lift control mechanism 100 includes a low speed rocker arm 102 (illustrated in Figure 2), a high speed rocker arm 104 (illustrated in Figure 2), a low speed intake cam lobe 106 (illustrated in Figure 2), a high speed intake cam lobe 108 (illustrated in Figure 2), an exhaust cam lobe 110 (illustrated in Figure 2), a lock pin 112 (illustrated in Figure 2), an intake rocker shaft 114 (illustrated in Figure 2), a special mechanism 116 (illustrated in Figure 3a), a screw shaft 118 (illustrated in Figure 4), a piston nut 120 (illustrated in Figure 4), a pair of compression springs 122a and 122b (illustrated in Figure 4), a housing 124 (illustrated in Figure 4), a cap 126 (illustrated in Figure 4), a cap 128 (illustrated in Figure 4), a fork 130 (illustrated in Figure 3b), a fork pin 132 (illustrated in Figure 5), a torsion spring 134 (illustrated in Figure 2), a torsion spring bolt 136 (illustrated in Figure 2), a plurality of gears 138 (illustrated in Figure 5), an electric motor 140 (illustrated in Figure 5), an intake valve 142 (illustrated in Figure 5), an exhaust valve 144 (illustrated in Figure 5), a camshaft holder 146 (illustrated in Figure 6), an exhaust rocker arm 148 (illustrated in Figure 5) and a pin 150 (illustrated in Figure 3a).
Referring to Figure 2 in conjunction with Figure 12, a camshaft includes two cam lobes, the low speed intake cam lobe 106 and the high speed intake cam lobe 108 for intake. The high speed intake cam lobe 108 is more aggressive than low speed intake cam lobe 106 in terms of maximum lift, also angle of opening of the intake valve 142 is early and closing of the intake valve 142 is delayed for the high speed intake cam lobe 108 compared to the low speed intake cam lobe 106. Further, the camshaft includes the exhaust cam lobe 110 for exhaust.
Referring to Figure 2 in conjunction with Figure 4, the low speed rocker arm 102 and the high speed rocker arm 104 are used for intake and the exhaust rocker

arm 148 is used for exhaust. The high speed rocker arm 104 is maintained in contact with cam lobes using the torsion spring 134.
The screw shaft 118 is mounted on the camshaft holder 146. The screw shaft 118 is locked axially and is free to rotate via the gearing 138 connected to the electrical motor 140. The piston nut 120 is made in such a way that it has screw threads on an inner surface that mate with threads on an outer surface of the screw shaft 118, But the piston nut 120 cannot rotate inside the housing 124 due to the pin 150 locked in a slot on the housing 124 and mounted on the piston nut 120. Outer surface of the piston nut 120 is free to slide on an inner surface of the housing 124.
The pair of helical compression springs 122a and 122b is installed inside the housing 124 resting against the cap 126, the cap 128 and the piston nut 120 with some initial compression. Referring to Figure 3a, the special mechanism 116 is free to slide on the screw shaft 118. The fork 130 is mounted on the fork pin 132 such that the cap 126 holds the fork 130 and can move it axially which indirectly moves the lock pin 112 axially inside the rocker arms 102 and 104. The fork 130 is free to slide on the fork pin 132 which is mounted on the camshaft holder 146 and holds the lock pin 112 such that the lock pin 112 can oscillate about an intake rocker shaft axis with rocker arm but cannot move axially unless the fork 130 moves axially on the fork pin 132.
The lock pin 112 is always disposed inside the low speed intake rocker arm 102 and is free to slide inside a hole and can engage and disengage the high speed rocker arm 104 while still remaining inside the low speed intake rocker arm 102, by sliding in and out of the hole of the high speed rocker arm 104.

Working
Referring to Figures 7a and 7b, at lower engine speeds the lock pin 112 remains disengaged from the high speed rocker arm 104. At this position the piston nut 120 is at the centre of the special mechanism 116 so both the compression springs 122a and 122b remain balanced and the cap 126 is in contact with a wall A 152 of the camshaft holder 146. This causes the low speed intake cam lobe 106 to transfer motion to the intake valve 142 via the low speed rocker arm 102.
Referring to Figure 8 in conjunction with Figure 10a, 11a and lib, as the
engine speed exceeds a particular switch point value 156 then the screw shaft 118 is rotated by means of the electric motor 140 through the gears 138 which cause the piston nut 120 to move ahead from the cap 126 side to Cap 128 side by a certain distance that is from position A to position B as shown in Figure 11a and lib due to the screw motion between the screw shaft 118 and the piston nut 120. This causes the compression spring 122a to compress and store the energy.
Referring to Figures 9a and 9b in conjunction with Figure 12, when the lock pin 112 is free to move inside the high speed rocker hole at base circles of the intake camshaft lobes 106 and 108, the compressed spring 122a gets released pushing the special mechanism 116 towards a wall B 154 of the camshaft holder 146 until the cap 128 rests against the wall B 154. This causes the lock pin 112 to get engaged in the high speed rocker arm 104. This causes the high speed rocker arm 104 to become one unit with the low speed rocker arm 102. As the high speed rocker arm 104 rolls on the high speed intake cam lobe 108, which has a more aggressive profile in terms of valve timing and lift compared to the

low speed intake cam lobe 106, the new high speed valve timing and lift is transferred to the intake valve 142.
Similarly, when the speed of the engine drops below a certain speed, the electric motor 140 rotates in a reverse direction with respect to previous rotation and the special mechanism 116 moves towards the wall A 152 disengaging the lock pin 112 from the high speed rocker arm 104.
Figures 10a and 10b illustrate a representation for gain in torque by a torque graph for 2 and 3 stages respectively but not limited to 2 or 3 stages of valve timing and lift of the multi stage variable valve timing and lift control mechanism 100. The torque graph represents variation of brake torque (represented by "axis Y" in the graph) with respect to engine speed (represented as "axis X" in the graph). The graph is plotted for normal engine without the multistage variable valve timing and lift control mechanism of Figure 1 (represented by reference numeral 158), low speed advantage zone (represented by reference numeral 160), medium speed (represented by reference numeral 162) and high speed advantage zone (represented by reference numeral 164). From the graph it is observed that optimum brake torque is obtained at intermediate engine speeds. Switch over points for switching to high speed cam lobe are represented by reference numeral 156.
FIGURE 13 illustrates a graph depicting lift variation with respect to cam angles for low speed cam lobe and high speed cam lobe for intake of FIGURE 2. The graph represents variation of lift (represented by "axis Y" in the graph) with respect to cam angles (represented as "axis X" in the graph). The reference numeral "166" represents variation of lift with respect to cam angles for the low speed cam lobe 106 and the reference numeral "168" represents variation of lift with respect to cam angles for the high speed cam lobe 108.

OPERATION EXPLANATION FOR MOTOR CONTROL
As seen from the working it is clear that to control the multi stage variable valve timing and lift control mechanism 100, there is need of a logic that can be incorporated in at least simple electronics means. As shown in Figure 12, the flow chart illustrates a logic that can be used when incorporated in a simple electronics means for controlling the electrical motor 140 of the multi stage variable valve timing and lift control mechanism 100 of the present disclosure but not limited only to the given logic. In one embodiment, the electrical motor 140 is a DC motor. The arrows in the flow chart represent the flow control direction and "Y" and "N" represent the "Yes" and "No" command from switches or sensors.
To control the position of the piston nut 120, there is need of switches that are to be incorporated in positions as shown in Figures 11a and lib. Figure Ha illustrates Position "A" of the piston nut 120 with respect to the screw shaft 118, when a first switch i.e. switch 1 (not shown), is in pressed condition. Figure lib illustrates Position "B" of the piston nut 120 with respect to the screw shaft 118, when a second switch i.e. switch 2 (not shown), is in pressed condition. In one embodiment, the switch 1 and switch 2 are position sensors to sense position "A" and position "B", using simple DC motor for control. Alternatively, in another embodiment positions are directly sensed/ controlled by a stepper motor that avoids position sensors. The reference for switch over points can either be engine speed or vehicle speed or both together.
In accordance with another embodiment of the present disclosure, a multi-stage variable valve timing and lift control mechanism 200 is disclosed. The multistage variable valve timing and lift control mechanism 200 includes a linear actuator/ special mechanism, wherein a screw shaft of the linear actuator of the

multi-stage variable valve timing and lift control mechanism 200 moves relative to the housing to actuate an actuating pin that in-turn causes actuation of valves by high speed and low speed intake cam lobes. Figure 14 illustrates a sectional view of the multi-stage variable valve timing and lift control mechanism 200 for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (IC Engine) in accordance with another embodiment of the present disclosure, wherein the screw shaft moves relative to the housing to actuate the actuating pin that in-turn causes actuation of the valves by the high speed and low speed intake cam lobes , and at low engine speed the actuating pin remains disengaged from the high speed rocker arm and engages with the low speed rocker arm to cause actuation of low speed intake valve. Figure 15 illustrates another view of the multi-stage variable valve timing and lift control mechanism 200 for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (IC Engine), wherein at high engine speeds, the actuating pin engages with the high speed rocker arm as well as the low speed rocker arm to cause actuation of high speed intake valve.
Referring to Figure 14, the multi-stage variable valve timing and lift control mechanism 200 (MSVVTL includes fork slot 201, a plunger A 202 (hereinafter referred to as the screw shaft), a rocker shaft lock plate 203, a plunger 204, a motor coupling 205, a balancing washer 206, a motor mount plate 207, a motor 208, an E-Clip washer 209, an intake rocker shaft B 210. The position of assembly as shown in Figure 14 is position A which is disengaged position of the lock pin 112 in which the lock pin remains disengaged from the high speed rocker arm 104 and engages with the low speed rocker arm 102 to cause actuation of low speed intake valve. The plunger 204 and intake rocker shaft B 210 form the housing in which the plunger A 202 or the screw shaft and the springs 122a and 122b are accommodated.

In case of the special mechanism/linear actuator of the multi-stage variable valve timing and lift control mechanism 200, the pin 112, the fork slot 201 is arranged such that the intake rocker shaft B 210 is disposed parallel to the intake rocker shaft 114. The springs 122a and 122b are assembled inside the intake rocker shaft 210. The balancing washer 206 helps position the fork slot
201 in position of either engaged or disengaged configuration. The plunger A
202 or the screw shaft is free to slide inside intake rocker shaft B 210. The fork slot 201 is connected to plunger A 202 or the screw shaft with help of threads. The plunger 204 is free to slide over plunger A 202. The motor coupling 205 is fixed to the plunger 204. The rocker shaft lock plate 203 locks the rocker shaft axially. The motor mount plate is connected to camshaft holder 146 and help to mount the motor 208. The motor 208 has its shaft connected to the motor coupling 205. The mechanism springs (122a and 122b) are assembled such that the spring 122a is installed between plunger A 202 and plunger 204, The compression spring 122b is installed between the balancing washer 206 and the E clip washer 209, wherein the balancing washer 206 rests against plunger 204. The fork slot 201 and the lock pin 112 are so arranged that the lock pin 112 is free to slide over the fork slot radially about intake rocker shaft B 210 centre axis but is axially locked by fork slot and moves axially towards right as position A or left as position B.
The basic working of mechanism remains same as explained in Figure 8, Figure 9a and Figure 9b. The engaged position of lock pin 112 is as shown in Figure 15 (position B) for a compact arrangement. The disengagement position is shown in Figure 14 (position A). The motor 208 is a special motor which moves the shaft towards right or left as against conventional motors which rotates the shaft. During disengagement, the motor 208 moves the motor coupling 205 towards right side to position A which is disengagement position as shown in Figure 14. Due to this the plunger 204 which is fixed to motor

coupling is also moved to position A, which in turn moves the plunger 202 and the fork slot 201 via spring balancing washer 206, the compression spring 122a and the E clip washer 209 to move towards right side which in turn causes the lock pin 112 to move out of high speed rocker arm 104.
During engagement as illustrated in Figure 15, the motor 208 moves the screw shaft such that motor coupling 205 moves towards left side to position B as shown in Figure 15, thereby causing the plunger 204 to move toward left side and compressing the spring 122a and hence pushing the plunger 202 or the screw shaft towards left side. The movement of the plunger 202 or the screw shaft towards left causes the fork slot 201 to move towards left side, thereby causing the actuating pin/ lock pin 112 to move towards left side and causing the actuating pin/ lock pin 112 to engage with the high speed rocker arm 104. The cushioning effect for lock pin 112 during engagement and disengagement is achieved by the spring 122a and 122b explained in the previous mechanism.
TECHNICAL ADVANCEMENTS AND ECONOMIC SIGNIFICANCE
The multi stage variable valve timing and lift control mechanism for IC engines, in accordance with the present disclosure described herein above has several technical advantages including but not limited to the realization of:
• a multi stage variable valve timing and lift control mechanism that is simple in construction;
• a multi stage variable valve timing and lift control mechanism that can be easily adaptable to a single cylinder engine but not limited in application only to the single cylinder internal combustion engine;

• a multi stage variable valve timing and lift control mechanism that is cost effective; and
• a multi stage variable valve timing and lift control mechanism that is reliable.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

We Claim:
1. A multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I C Engine), said multi-stage variable valve timing and lift control mechanism comprising:
• a rotary drive;
• a coupling;
• a linear actuator adapted to be functionally coupled to said rotary drive via said coupling and actuated by said rotary drive, said linear actuator mounted on a cam shaft holder of the valve actuation system, wherein said cam shaft holder supports a cam shaft, said linear actuator comprising:
oa housing having an centrally configured and internally threaded bore;
oa screw shaft centrally received inside said housing, wherein at least a portion of said screw shaft having threads formed on outer surface thereof complimentary to and threadably engaging with said threads of said bore to facilitate relative axially displacement between said screw shaft and said housing as a result of the relative angular displacement between said screw shaft and said housing;
oat least a pair of spring elements disposed inside and confined in said housing and interacting with said screw shaft and said housing, wherein either of said spring elements adapted to get compressed as a result of the relative axially displacement between said screw shaft and said housing;

o a locking pin adapted to facilitate relative angular displacement between said screw shaft and said housing; and
o an actuating pin adapted to be displaced as a result of relative axially displacement between said screw shaft and said housing, wherein said actuating pin adapted to selectively engage with a high speed rocker arm and a low speed rocker arm that are functionally coupled to a high speed intake cam lobe and a low speed intake cam lobe to facilitate controlling the valve parameters of said valve actuation system.
2. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein said rotary drive is an electric motor.
3. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein said coupling is a gear transmission arrangement.
4. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein said coupling is a belt and pulley transmission arrangement.
5. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein said screw shaft is adapted to receive drive torque from said rotary drive via said coupling and said angular movement of said housing is locked by said locking pin to facilitate relative angular displacement between said screw shaft and said housing to cause axial movement of the

housing and axial movement of the actuating pin functionally connected to said housing such that the actuating pin selectively engages with said high speed rocker arm and said low speed rocker arm.
6. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein said housing is adapted to receive drive torque from said rotary drive via said coupling and said locking pin to facilitate relative angular displacement between said screw shaft and said housing to cause axial movement of the screw shaft and axial movement of said actuating pin functionally connected to said screw shaft such that said actuating pin selectively engages with said high speed rocker arm and said low speed rocker arm.
7. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein each spring element of said at least a pair of spring elements is a helical compression spring.
8. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein said spring elements are confined in said housing by a bulge formed on said screw shaft and a plunger member forming the housing.
9. The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein said spring elements are confined in said housing by a pair of end caps and a piston nut threadably engaging with threaded portion of said screw shaft.

10.The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1 further comprising a torsion spring mounted on a spring bolt for maintaining said high speed rocker arm in contact with said high speed intake cam lobe and said low speed intake cam lobe.
11.The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein at low engine speed said actuating pin remains disengaged from said high speed rocker arm and engages with said low speed rocker arm to cause actuation of low speed intake valve.
12.The multi-stage variable valve timing and lift control mechanism for controlling valve parameters associated with a valve actuation system of an Internal Combustion Engine (I.C Engine) as claimed in Claim 1, wherein at high engine speed said actuating pin gets engaged with said high speed rocker arm as well as said low speed rocker arm to cause said high speed rocker arm to interact with said high speed intake valve lobe.