Description:FIELD OF THE INVENTION
[001] The present invention generally relates to an internal combustion engine. More particularly, the present invention relates to an internal combustion engine for a motor vehicle.

BACKGROUND OF THE INVENTION
[002] Generally, in conventional motor vehicles with internal combustion engines, a camshaft is operatively connected to a crankshaft. The rotation of the crankshaft causes the rotation of the camshaft, which then facilitates the opening and closing of intake and exhaust valves. In that, a camshaft generally comprises a cam lobe and a finger follower. The finger follower is in contact with the cam lobe and the intake or exhaust valve, and the rotational motion of the cam lobe is transmitted as translational motion of the intake or exhaust valves through the finger follower. Generally, for each valve, a single cam lobe is provided, which provides for operation of the internal combustion engine at a single valve timing. Valve timing is defined as the precise timing of the opening and closing of the intake and the exhaust valves.
[003] In internal combustion engines with a single valve timing, the torque produced by the engine is always constant irrespective of the rotational speed of the engine. This leads to a reduction in overall efficiency of the engine, and thus the vehicle. Thus, when the torque requirement increases with higher engine speeds, the engine is unable to deliver the same.
[004] Further, in a dual cam or multi cam vehicle, the single valve timing further reduces the overall efficiency of the engine. This is because the required torque to run the engine at higher speed is not achieved due to low intake of air in the combustion chamber. Conventional systems for achieving variable valve timing use spacer mechanisms for moving the camshaft as a whole for bringing different cam lobes in contact with the valves. However, such conventional systems have a high part count, and the movement of the camshaft as a whole leads to increased chances of damage to the cam lobes.
[005] Thus, there is a need in the art for an internal combustion engine which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[006] In one aspect, the present invention is directed towards an internal combustion engine. The internal combustion engine has one or more camshafts. The one or more camshafts are disposed in a cylinder head of the internal combustion engine. Further, a plurality of cam lobes are provided on the each of the one or more camshafts, and the plurality of cam lobes have at least a first cam lobe and a second cam lobe. At least one valve is operably connected to the plurality of cam lobes. A cam follower is disposed between the valve and the plurality of cam lobes, wherein the cam follower is abutting the valve and selectively abutting one of the first cam lobe or the second cam lobe. A follower shaft is connected to the cam follower. Further, an actuator device is configured to drive the follower shaft, thereby moving the cam follower for selectively abutting the cam follower to one of the first cam lobe or the second cam lobe.
[007] In an embodiment of the invention, the one or more camshafts include an intake camshaft and an exhaust camshaft.
[008] In a further embodiment of the invention, a lobe height of the second cam lobe is greater than a lobe height of the first cam lobe.
[009] In a further embodiment of the invention, the cam follower is abutted to the first cam lobe when a rotational speed of the engine is below a first predetermined engine speed, and the cam follower is abutted to the second cam lobe when the rotational speed of the engine is greater than the first predetermined engine speed.
[010] In a further embodiment of the invention, the actuator device has a solenoid actuator. The solenoid actuator is connected to a first end of the follower shaft and the solenoid actuator is electrically or electronically driven by a vehicle control unit for driving the follower shaft.
[011] In a further embodiment of the invention, the actuator device has a return spring being connected to a second end of the follower shaft. The return spring is configured to be in a relaxed condition when the cam follower is abutted to the first cam lobe, and in a compressed condition when the cam follower is abutted to the second cam lobe.
[012] In a further embodiment of the invention, the actuator device has a locking mechanism provided at the second end of the follower shaft. The locking mechanism is configured to lock the follower shaft in position when the cam follower abuts the first cam lobe or the second cam lobe.
[013] In a further embodiment of the invention, the locking mechanism has a pin provided on the follower shaft and a slot provided in a housing of actuator device and the slot is configured to receive the pin.
[014] In a further embodiment of the invention, the pin is disengaged with the slot when the cam follower abuts the first cam lobe, and when the rotational speed of the engine is greater than the first predetermined engine speed, the actuator device pushes the follower shaft, and the pin is engaged with the slot, thereby allowing the cam follower to abut the second cam lobe.
[015] In a further embodiment of the invention, the pin is engaged with the slot when the cam follower abuts the first cam lobe, and when the rotational speed of the engine is greater than the first predetermined engine speed, the actuator device pushes the follower shaft, and the pin is disengaged with the slot, thereby allowing the cam follower to abut the second cam lobe.
[016] In a further embodiment of the invention, the internal combustion has a fixer spring. The fixer spring is provided on the actuator device and the fixer spring being configured to move the housing of the actuator device, thereby facilitating the engagement of the pin with the slot and the movement of the cam follower from the first cam lobe to the second cam lobe.
[017] In a further embodiment of the invention, the solenoid actuator has a cylindrical profile.
[018] In a further embodiment of the invention, the housing of the actuator device has a cylindrical profile.

BRIEF DESCRIPTION OF THE DRAWINGS
[019] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 illustrates a front view of an internal combustion engine, in accordance with an embodiment of the present invention.
Figure 2 illustrates an exploded view of the cam lobe actuation system of the internal combustion engine, in accordance with an embodiment of the present invention.
Figure 3 illustrates a perspective view of a camshaft of the internal combustion engine, in accordance with an embodiment of the present invention.
Figure 4 illustrates a perspective view of a valve of the internal combustion engine, in accordance with an embodiment of the present invention.
Figure 5 illustrates another perspective view of the internal combustion engine, in accordance with an embodiment of the present invention.
Figure 6A and 6B illustrate a side view of a locking mechanism with a pin engaged and disengaged with a slot respectively, in accordance with an embodiment of the present invention.
Figure 7 illustrates another perspective view of the internal combustion engine, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
[020] The present invention relates to an internal combustion engine. More particularly, the present invention relates to an internal combustion engine for a motor vehicle. The internal combustion engine of the present invention is typically used in a vehicle such as a two wheeled vehicle. However, it should be understood that the internal combustion engine as illustrated may find its application in a three wheeled vehicle, or a four wheeled vehicle, or other multi-wheeled vehicles, or any non-automotive application using an internal combustion engine as required.
[021] Figure 1 illustrates a front view of an internal combustion engine 100 and Figure 2 illustrates an exploded view of the internal combustion engine 100. As illustrated in Figure 1 and Figure 2, the internal combustion engine 100 comprises one or more camshafts 110. The one or more camshafts 110 are disposed in a cylinder head 12 of the internal combustion engine 100. The camshafts 110 are operably driven by a crankshaft (not shown) of the internal combustion engine 100. In an embodiment, the one or more camshafts 110 comprise an intake camshaft and an exhaust camshaft, wherein the intake camshaft is configured to operate intake valves and the exhaust camshaft is configured to operate exhaust valves.
[022] The internal combustion engine 100 further comprises a plurality of cam lobes 112. The plurality of cam lobes 112 are provided on the each of the one or more camshafts 110. Thus, in an embodiment, the plurality of cam lobes 112 are provided on the intake camshaft as well as the exhaust camshaft. Further, as also illustrated in Figure 3, the plurality of cam lobes 112 comprise at least a first cam lobe 112A and a second cam lobe 112B. As illustrated, the first cam lobe 112A and the second cam lobe 112B cam lobe have differing lobe heights or differing lobe dimensions.
[023] As further illustrated in Figure 2 and Figure 4, the internal combustion engine 100 further comprises at least one valve 120. In that, the at least one valve 120 is operably connected to the plurality of cam lobes 112. Herein, in an embodiment, the at least one valve 120 are provided in a combustion chamber of the internal combustion engine 100 and are configured to allow entry of air fuel mixture into the combustion chamber, i.e. acting as an intake valve, or to allow exit of exhaust gases from the combustion chamber after combustion, i.e. acting as an exhaust valve. Herein, the movement and the dimensions of the cam lobes 112 control the timing of the opening and closing of the valves 120 as well as the degree of opening of the valves 120, thus controlling the overall amount of time for which the valves 120 remain open.
[024] Further, the internal combustion engine 100 comprises a cam follower 130. The cam follower 130 is disposed between the at least one valve 120 and the plurality of cam lobes 112. Herein, as illustrated the cam follower 130 abuts the at least one valve 120. Further, the cam follower 130 selectively abuts one of the first cam lobe 112A or the second cam lobe 112B. Accordingly, the cam follower 130 is configured to be in contact with the first cam lobe 112A or the second cam lobe 112B, and move in a translational motion based on the rotational motion of the cam lobes 112. The cam follower 130 then transmits this translational motion to the at least one valve 120, thereby opening and closing the at least one valve 120. For allowing translational motion of the cam follower 130 and for supporting the cam follower 130, the internal combustion engine 100 comprises a follower shaft 140 wherein the follower shaft 140 is connected to the cam follower 130. As illustrated, the cam follower 130 is mounted on to the follower shaft 140.
[025] The internal combustion engine 100 further comprises an actuator device 150. The actuator device 150 is connected to the follower shaft 140 and is configured to drive the follower shaft 140. The driving of the follower shaft 140 moves the cam follower 130 for selectively abutting the cam follower 130 to one of the first cam lobe 112A or the second cam lobe 112B. Herein, since lobe height of the first cam lobe 112A is different from the second cam lobe 112B, depending on whether the cam follower 130 is abutting the first cam lobe 112A or the second cam lobe 112B, the degree of opening of the at least one valve 120 along with the overall timing for which the at least one valve 120 remains open is varied, thus achieving variable valve timing.
[026] In an embodiment, as illustrated in Figure 4, a lobe height of the second cam lobe 112B is greater than a lobe height of the first cam lobe 112A. Accordingly, when the cam follower 130 is abutting the second cam lobe 112B, a greater degree of opening of the valve and greater overall timing for which the at least one valve 120 remains open is achieved, as compared to when the cam follower 130 is abutting the first cam lobe 112A.
[027] In an embodiment, as illustrated in Figure 4 and Figure 5, the cam follower 130 is abutted to the first cam lobe 112A when a rotational speed of the engine 100 is below a first predetermined engine speed. Further, the cam follower 130 is abutted to the second cam lobe 112B when the rotational speed of the engine 100 is greater than the first predetermined engine speed. In an embodiment, the first predetermined engine speed is 5000 RPM. Thus, in operation, for example, when the rotational speed of the engine 100 is between 1000 RPM and 5000 RPM, which is a low speed range, the cam follower 130 abuts the first cam lobe 112A. Owing to the shorter lobe height of the first cam lobe 112A, a shorter degree of opening of the valve and smaller overall timing for which the at least one valve 120 remains open is achieved, which results in lower torque generation, which is appropriate for low speed range.
[028] In an embodiment, When the rotational speed of the engine is greater than 5000 RPM, which is a high speed range, the actuator device 150 drives the follower shaft 140 to move the cam follower 130, for the cam follower 130 to abut the second cam lobe 112B. Owing to the greater lobe height of the second cam lobe 112B, a greater degree of opening of the valve and greater overall timing for which the at least one valve 120 remains open is achieved, which results in higher torque generation, which is appropriate for high speed range.
[029] In an embodiment, as referenced in Figure 2, the actuator device 150 comprises a solenoid actuator 152. The solenoid actuator 152 is connected to a first end 140A of the follower shaft 140 and the solenoid actuator 152 is electrically or electronically driven by a vehicle control unit for driving the follower shaft 140. Thus, the vehicle control unit detects the rotational speed of the engine 100, and if the rotational speed of the engine 100 is above the first predetermined engine speed, the vehicle control unit drives the solenoid actuator 152 to push the follower shaft 140, thereby pushing the cam follower 130 from the first cam lobe 112A to the second cam lobe 112B. In an embodiment, the solenoid actuator 152 has a cylindrical profile.
[030] Further, in an embodiment, to ensure that the cam follower 130 can return to the first cam lobe 112A when the rotational speed of the engine 100 falls below the first predetermined engine speed, the actuator device 150 comprises a return spring 154. The return spring is connected to a second end 140B of the follower shaft 140. The return spring 154 is configured to be in a relaxed condition when the cam follower 130 is abutted to the first cam lobe 112A, and in a compressed condition when the cam follower 130 is abutted to the second cam lobe 112B. Thus, in operation, when the vehicle control unit detects that the rotational speed of the engine 100 has fallen below the first predetermined engine speed, the vehicle control unit ceases to operate the solenoid actuator 152. The return spring 154 which is in the compressed condition, when the cam follower 130 is abutted to the second cam lobe 112B, thus pushes the follower shaft 140 to move the cam follower 130 to abut the first cam lobe 112A, where the return spring 154 returns to the relaxed condition.
[031] In a further embodiment, the actuator device 150 comprises a locking mechanism 156 provided at the second end 140B of the follower shaft 140, the locking mechanism 156 is configured to lock the follower shaft 140 in position when the cam follower 130 abuts with one of the first cam lobe 112A or the second cam lobe 112B. The locking mechanism 156 ensures that the follower shaft 140 is locked in position, and there is no undesired movement of the follower shaft 140 in response to the rotation of the cam lobes 112.
[032] In an embodiment, the locking mechanism 156 comprises a pin 158 provided on the follower shaft 140 and a slot 160 provided in a housing 162 of actuator device 150. In an embodiment, the housing 162 of the actuator device 150 has a cylindrical profile. Herein, the slot 160 is configured to receive the pin 158. In an embodiment, as illustrated in Figure 6B, the pin 158 is disengaged with the slot 160 when the cam follower 130 abuts the first cam lobe 112A. As further illustrated in Figure 6A, when the rotational speed of the engine 100 is greater than the first predetermined engine speed, the actuator device 150 pushes the follower shaft 140, and the pin 158 is engaged with the slot 160, thereby allowing the cam follower 130 to abut the second cam lobe 112B and the follower shaft 140 being locked in position.
[033] In an alternative embodiment, as illustrated in Figure 6A, the pin 158 is engaged with the slot 160 when the cam follower 130 abuts the first cam lobe 112A thereby locking the follower shaft 140 in position. Thereafter, as illustrated in Figure 6B, and when the rotational speed of the engine 100 is greater than the first predetermined engine speed, the actuator device 150 pushes the follower shaft 140, and the pin 158 is disengaged with the slot 160, thereby allowing the cam follower 130 to abut the second cam lobe 112B.
[034] Under certain circumstances, during movement of the cam follower 130 from the first cam lobe 112A to the second cam lobe 112B or vice versa, the pin 158 may not be completely inserted inside or be engaged with the slot 160. This leads to the cam follower 130 being in contact with only a portion of the first cam lobe 112A or the second cam lobe 112B, which creates a hinderance in achieving variable valve timing and may cause mechanical damage to the pin 158 or other components. Thus, to ensure that the pin 158 does not get stuck in a position wherein the pin 158 is not completely inserted inside or be engaged with the slot 160, the internal combustion engine 100 has a fixer spring 170. The fixer spring 170 is provided on the actuator device 150 and the fixer spring 170 is configured to move the housing 162 of the actuator device 150. This facilitates the engagement of the pin 158 with the slot 160 and the movement of the cam follower 130 from the first cam lobe 112A to the second cam lobe 112B. In an embodiment, the fixer spring 170 is a torsional spring which compresses and initiates a rotational movement of the housing 162 so that the pin 158 moves completely inside the slot 160. This rotational movement of the housing 162 can be one of a clockwise or an anticlockwise direction as per requirement.
[035] In an exemplary embodiment, as illustrated in Figure 7, the camshaft 110 has two sets cam lobes 112, and accordingly has two sets of the first cam lobe 112A and the second cam lobe 112B. Further, in this embodiment, there are provided valves 120 and two cam followers 130 mounted on the follower shaft. Herein, each of the cam follower 130 is provided between one set of cam lobes 112 and one valve 120. As explained hereinabove, a single actuator device 150 drives the follower shaft 140, which causes movement of both the cam followers 130 thus achieving the required variable valve timing for all the valves 120 being operated by the camshaft. The present invention is thus capable of being applied to multiple camshafts 110 having multiple set of cam lobes 112 and multiple valves 120 as per requirement.
[036] Advantageously, the present invention provides an internal combustion engine which is capable of achieving a variable valve timing. The variable valve timing allows for generation of lower torque at lower engine speeds and higher torque at high engine speeds. This not only increases the efficiency of the engine but also increases overall performance of the engine by meeting the torque requirements at different engine speeds.
[037] Variable valve timing, including, variable degree of opening of the valve as well as variable overall time for which the valve remains open, also provides for better fuel efficiency since the valve timing is adjusted according to the rotational speed of the engine.
[038] Furthermore, in the present invention, the requirement of moving the entire camshaft for achieving the variable valve timing is eliminated. This results in substantial reduction in part count as well as reduction in complexity, which reduces overall complexity of the engine. The reduced complexity and part count further enhances fuel efficiency and ease of manufacturing and serviceability.
[039] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

List of Reference Numerals
12: Cylinder head
100: Internal Combustion Engine
110: One or more Camshaft
112: Plurality of Cam Lobes
112A: First Cam Lobe
112B: Second Cam Lobe
120: Valve
130: Cam Follower
140: Follower Shaft
140A: First End of the Follower Shaft
140B: Second End of the Follower Shaft
150: Actuator Device
152: Solenoid Actuator
154: Return Spring
156: Locking Mechanism
158: Pin
160: Slot
162: Housing
170: Fixer Spring
, Claims:WE CLAIM:
1. An internal combustion engine (100), comprising:
one or more camshafts (110), the one or more camshafts (110) being disposed in a cylinder head (12) of the internal combustion engine (100);
a plurality of cam lobes (112), the plurality of cam lobes (112) being provided on the each of the one or more camshafts (110), the plurality of cam lobes (112) comprising at least a first cam lobe (112A) and a second cam lobe (112B);
at least one valve (120), the at least one valve (120) being operably connected to the plurality of cam lobes (112);
a cam follower (130), the cam follower (130) being disposed between the at least one valve (120) and the plurality of cam lobes (112), the cam follower (130) abutting the at least one valve (120) and selectively abutting one of the first cam lobe (112A) or the second cam lobe (112B);
a follower shaft (140), the follower shaft (140) being connected to the cam follower (130); and
an actuator device (150), the actuator device (150) being configured to drive the follower shaft (140), thereby moving the cam follower (130) for selectively abutting the cam follower (130) to one of the first cam lobe (112A) or the second cam lobe (112B).

2. The internal combustion engine (100) as claimed in claim 1, wherein the one or more camshafts (110) comprises an intake camshaft and an exhaust camshaft.

3. The internal combustion engine (100) as claimed in claim 1, wherein a lobe height of the second cam lobe (112B) is greater than a lobe height of the first cam lobe (112A).

4. The internal combustion engine (100) as claimed in claim 3, wherein the cam follower (130) is abutted to the first cam lobe (112A) when a rotational speed of the engine (100) is below a first predetermined engine speed, and the cam follower (130) is abutted to the second cam lobe (112B) when the rotational speed of the engine (100) is greater than the first predetermined engine speed.

5. The internal combustion engine (100) as claimed in claim 1, wherein the actuator device (150) comprises a solenoid actuator (152), the solenoid actuator (152) being connected to a first end (140A) of the follower shaft (140), the solenoid actuator (152) being electrically or electronically driven by a vehicle control unit for driving the follower shaft (140).

6. The internal combustion engine (100) as claimed in claim 1, wherein the actuator device (150) comprising a return spring (154) being connected to a second end (140B) of the follower shaft (140), the return spring (154) being configured to be in a relaxed condition when the cam follower (130) is abutted to the first cam lobe (112A), and in a compressed condition when the cam follower (130) is abutted to the second cam lobe (112B).

7. The internal combustion engine (100) as claimed in claim 6, wherein the actuator device (150) comprising a locking mechanism (156) provided at the second end (140B) of the follower shaft (140), the locking mechanism (156) being configured to lock the follower shaft (140) in position when the cam follower (130) abuts the first cam lobe (112A) or the second cam lobe (112B).

8. The internal combustion engine (100) as claimed in claim 7, wherein the locking mechanism (156) comprises a pin (158) provided on the follower shaft (140) and a slot (160) provided in a housing (162) of actuator device (150), the slot (160) being configured to receive the pin (158).

9. The internal combustion engine (100) as claimed in claim 8, wherein the pin (158) is disengaged with the slot (160) when the cam follower (130) abuts the first cam lobe (112A), and when the rotational speed of the engine (100) is greater than the first predetermined engine speed, the actuator device (150) pushes the follower shaft (140), and the pin (158) is engaged with the slot (160), thereby allowing the cam follower (130) to abut the second cam lobe (112B).

10. The internal combustion engine (100) as claimed in claim 8, wherein the pin (158) is engaged with the slot (160) when the cam follower (130) abuts the first cam lobe (112A), and when the rotational speed of the engine (100) is greater than the first predetermined engine speed, the actuator device (150) pushes the follower shaft (140), and the pin (158) is disengaged with the slot (160), thereby allowing the cam follower (130) to abut the second cam lobe (112B).

11. The internal combustion engine (100) as claimed in claim 9, comprising a fixer spring (170), the fixer spring (170) being provided on the actuator device (150) and the fixer spring (170) being configured to move the housing (162) of the actuator device (150), thereby facilitating the engagement of the pin (158) with the slot (160) and the movement of the cam follower (130) from the first cam lobe (112A) to the second cam lobe (112B).

12. The internal combustion engine (100) as claimed in claim 5, wherein the solenoid actuator (152) has a cylindrical profile.

13. The internal combustion engine (100) as claimed in claim 8, wherein the housing (162) of the actuator device (150) has a cylindrical profile.