A variable valve timing assembly for an internal combustion engine

Abstract

The present invention relates to a variable valve timing assembly (100) for an internal combustion engine (10). The variable valve timing assembly (100) comprises at least one camshaft (102), a sprocket (104) rotatably configured on the at least one camshaft (102), a cam disc (108) being configured to transfer rotational motion of the sprocket (104) to the at least one camshaft and an eccentric coupler (110). The eccentric coupler (110) is coupled with the sprocket (104) and the cam disc (108). The eccentric coupler (110) is configured to selectively move in a first direction (F1) and a second direction (F2) such that an axis of rotation of the eccentric coupler (104) is offset with respect to an axis of rotation of the at least one camshaft (102) resulting in rotation of the at least one camshaft (102) at different angular speeds at different points of rotation of the sprocket (104).

Description

[0001] TITLE OF INVENTION

[0002] A VARIABLE VALVE TIMING ASSEMBLY FOR AN INTERNAL COMBUSTION ENGINE

[0003] FIELD OF THE INVENTION

[0004]

[0001] The present invention relates to an internal combustion engine. More particularly, the present invention relates to a variable valve timing assembly for the internal combustion engine.

[0005] BACKGROUND OF THE INVENTION

[0006]

[0002] Conventional vehicle engines having standard / fixed valvetrains, where valve opening and closing timing is fixed throughout the engine operating range, suffer from several drawbacks like providing poor fuel efficiency due to less effective airfuel mixture optimization, peak torque / performance at certain RPM ranges, higher emissions from incomplete fuel combustion, slower throttle response, and less adaptability to various riding conditions such as city commuting, highway cruising. In other words, the standard / fixed valvetrains do not adapt to different valve operating conditions of the internal combustion engine. This results in a compromise i.e., the engine cannot optimize fuel efficiency at low speeds or maximize performance at high speeds, as it cannot dynamically adjust the valve timing based on the operating conditions of the engine.

[0007]

[0003] To overcome disadvantages of the standard / fixed valve trains, prior arts discloses variable valve timing (WT). Variable Valve Timing (WT) is a technology used in modern internal combustion engines to optimize engine performance. WT involves altering timing of the opening and closing of the intake and exhaust valves of the engine in response to engine speed and load conditions. The Engine Control Unit (ECU) controls the valve timing based on the throttle control, the engine intake manifold pressure, and engine RPM. The main objective of WT is to enhance fuel efficiency, reduce emissions, and improve overall engine performance by adaptingvalve timing to suit various driving conditions (across high and low RPMs). For example, in a Double Overhead Camshaft (DOHC) systems, intake camshafts are positioned above the cylinders of the engine to control intake valves and exhaust camshafts to control exhaust valves. This layout provides a high degree of control over valve timing of the engine, allowing for more efficient air intake and exhaust, which is essential for high-performance engines. However, existing Variable Valve Timing (WT) systems conventionally rely on various sensors to monitor engine parameters and adjust the camshaft timing accordingly. The existing WT systems are, therefore, costly. Also, in case any of these sensors fail or become inaccurate, it can lead to improper timing adjustments, negatively affecting performance of the internal combustion engine and significantly increasing fuel consumption. Repairing and replacement of sensors will also lead to increase in repair costs and replacement costs.

[0008]

[0004] In view thereof, there is a need-felt to overcome at least the above-mentioned disadvantages of the prior arts.

[0009] SUMMARY OF THE INVENTION

[0010]

[0005] In one aspect of the invention, a variable valve timing assembly for an internal combustion engine is disclosed. The variable valve timing assembly comprises at least one camshaft, a sprocket, a cam disc and an eccentric coupler. The at least one camshaft is adapted to operate one or more valves of the internal combustion engine. The sprocket is rotatably configured on the at least one camshaft. The sprocket is connected to and driven by a crankshaft of the internal combustion engine. The cam disc is operably connected to the at least one camshaft. The cam disc is configured to transfer rotational motion of the sprocket to the at least one camshaft to rotate the at least one camshaft. The eccentric coupler is operably coupled with the sprocket and the cam disc. The eccentric coupler is configured to selectively move in a first direction and a second direction opposite the first direction such that an axis of rotation of the eccentric coupler is offset with respect to an axis of rotation of the atleast one camshaft upon movement of the eccentric coupler in the first direction or the second direction. The rotation of the eccentric coupler at a different axis of rotation than the rotation axis of the at least one camshaft results in rotation of the at least one camshaft at different angular speeds at different points of rotation of the sprocket.

[0011]

[0006] In an embodiment, the at least one camshaft is one of an intake camshaft and an exhaust camshaft.

[0012]

[0007] In an embodiment, the eccentric coupler comprises a disc with a mounting hole through which the camshaft is extended. The disc has at least a first elongated slot and a second elongated slot. The first elongated slot and the second elongated slot are provided diametrically opposite to each other and extends in a radial direction of the disc.

[0013]

[0008] In an embodiment, the eccentric coupler comprises a driving pin and a driven pin. The driving pin and the driven pin can be cylindrical shaped pins or ball shaped pins. The sprocket and the eccentric coupler are coupled by the driving pin. One end of the driving pin is connected to the sprocket and the other end of the driving pin is received in the first elongated slot of the eccentric coupler. The driving pin is configured to slide in the first elongated slot to allow selected movement of the eccentric coupler in the first direction and the second direction. The eccentric coupler is further coupled to the cam disc by the driven pin. One end of the driven pin is connected to the cam disc and the other end of the driven pin is received in the second elongated slot of the eccentric coupler. The driven pin is also configured to slide in the second elongated slot to allow selective movement of the eccentric coupler in the first direction and the second direction.

[0014]

[0009] In an embodiment, the eccentric coupler comprises an inner ring and an outer ring. The outer ring is connected to the inner ring by a first rod and a second rod. The first rod and the second rod are provided diametrically opposite to each other. The eccentric coupler further comprises a driving slider pin being slidably configuredwith the first rod, and a driven slider pin being slidably configured with the second rod.

[0015]

[0010] The sprocket and the eccentric coupler are coupled by the driving slider pin. One end of the driving slider pin is connected to the sprocket and the other end of the driving slider pin is slidably disposed on the first rod of the eccentric coupler. The driving slider pin is configured to slide on the first rod to allow selective movement of the eccentric coupler in the first direction and the second direction.

[0016] [Oil] The cam disc and the eccentric coupler are coupled by the driven slider pin. One end of the driven slider pin is connected to the cam disc and the other end of the driven slider pin is slidably disposed on the second rod of the eccentric coupler. The driven slider pin is configured to slide on the second rod to allow selective movement of the eccentric coupler in the first direction and the second direction.

[0017]

[0012] In an embodiment, the variable valve timing assembly comprises a linear motion mechanism. The linear motion mechanism is adapted to selectively move the eccentric coupler in the first direction and the second direction.

[0018]

[0013] In an embodiment, the linear motion mechanism comprises an eccentric cage, a guide pin, a lead screw, a rotary device and a gear mechanism. The eccentric cage comprises at least a first hole and a second hole. The guide pin extends through the first hole to prevent rotation of the eccentric cage. The lead screw extends through the second hole. The lead screw is operably coupled to the rotary device and the gear mechanism. The rotary device is adapted to selectively rotate the lead screw in a first rotational direction and a second rotational direction opposite the first rotational direction based on one or more inputs received from an engine control unit. The rotation of the lead screw in the first rotational direction enables linear movement of the eccentric cage along with the eccentric coupler in the first direction. Similarly, the rotation of the lead screw in the second rotational direction enables linear movement of the eccentric cage along with the eccentric coupler in the second direction.

[0014] In an embodiment, the valve timing assembly comprises an eccentric bearing configured in the eccentric cage. The eccentric coupler is configured to be fitted inside the eccentric cage.

[0019]

[0015] In an embodiment, movement of the eccentric coupler in the first direction leads to a shift of an axis of rotation of the eccentric coupler in the first direction with respect to an axis of rotation of the at least one camshaft. This results in opening of the one or more valves by the camshaft for a longer period of time than a standard opening time. This also results in closing of the one or more valves by the camshaft for a shorter period of time than a standard closing time. The standard opening time and the standard closing time are timings of operation of the one or more valves when the axis of rotation of the eccentric coupler is coincident with the axis of rotation of the at least one camshaft.

[0020]

[0016] In an embodiment, movement of the eccentric coupler in the second direction leads to a shift of an axis of rotation of the eccentric coupler in the second direction with respect to an axis of rotation of the at least one camshaft. This results in opening of the one or more valves by the camshaft for a shorter period of time than a standard opening time. This also results in closing of the one or more valves by the camshaft for a longer period of time than a standard closing time. As already stated, the standard opening time and the standard closing time are timings of operation of the one or more valves when the axis of rotation of the eccentric coupler is coincident with the axis of rotation of the at least one camshaft.

[0021]

[0017] In an embodiment, the eccentric cage is configured with an end plate. The end plate is adapted to be mounted on a cylinder head of the internal combustion engine.

[0022]

[0018] In another aspect of the present invention, an internal combustion engine for a vehicle is disclosed. The internal combustion engine comprises a cylinder head and a variable valve timing assembly. The variable valve timing is configured in the cylinder head. The variable valve timing assembly comprises at least one camshaft, a sprocket, a cam disc and an eccentric coupler. The at least one camshaft is adapted tooperate one or more valves of the internal combustion engine. The sprocket is rotatably configured on the at least one camshaft. The sprocket is connected to and driven by a crankshaft of the internal combustion engine. The cam disc is operably connected to the at least one camshaft. The cam disc is configured to transfer rotational motion of the sprocket to the at least one camshaft to rotate the at least one camshaft. The eccentric coupler is operably coupled with the sprocket and the cam disc. The eccentric coupler is configured to selectively move in a first direction and a second direction opposite the first direction such that an axis of rotation of the eccentric coupler is offset with respect to an axis of rotation of the at least one camshaft upon movement of the eccentric coupler in the first direction or the second direction. The rotation of the eccentric coupler at a different axis of rotation than the rotation axis of the at least one camshaft results in rotation of the at least one camshaft at different angular speeds at different points of rotation of the sprocket.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024]

[0019] 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.

[0025] Figure 1 illustrates a perspective view of a variable valve timing assembly configured in a cylinder head of an internal combustion engine, in accordance with embodiments of the present invention.

[0026] Figure 2 illustrates a partially exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine, in accordance with the embodiments of the present invention.

[0027] Figure 3 illustrates a sectional view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the embodiments of the present invention.Figure 4 illustrates a fully exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine where a driving pin and a driven pin are cylindrical shaped pins, in accordance with a first embodiment of the present invention.

[0028] Figure 5 illustrates a sectional view of an eccentric coupler coupled with a sprocket and a cam disc through a driving pin and a driven pin which are ball shaped pins, in accordance with the first embodiment of the present invention.

[0029] Figure 6 illustrates a top sectional view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the first embodiment of the present invention.

[0030] Figure 7 illustrates a fully exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine where a driving pin and a driven pin are ball shaped pins, in accordance with a second embodiment of the present invention.

[0031] Figure 8 illustrates a sectional view of the eccentric coupler coupled with the sprocket and the cam disc through a driving pin and a driven pin which are ball shaped pins, in accordance with the second embodiment of the present invention Figure 9 illustrates a perspective view of the eccentric coupler where a driving pin and a driven pin are ball shaped pins, in accordance with the second embodiment of the present invention.

[0032] Figure 10 illustrates a top sectional view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the second embodiment of the present invention.

[0033] Figure 11 illustrates a fully exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine depicting an eccentric coupler with a driving slider pin and a driven slider pin configuration, in accordance with a third embodiment of the present invention.Figure 12 illustrates a sectional view of the eccentric coupler coupled with the sprocket and the cam disc through a driving slider pin and a driven slider pin, in accordance with the third embodiment of the present invention

[0034] Figure 13 illustrates a perspective view of the eccentric coupler with a driving slider pin and a driven slider pin, in accordance with the third embodiment of the present invention.

[0035] Figure 14 illustrates a top sectional view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the third embodiment of the present invention.

[0036] DETAILED DESCRIPTION OF THE INVENTION

[0037]

[0020] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder.

[0038]

[0021] In the present invention, the term “vehicle” includes all the vehicles having an internal combustion engine and a variable valve timing assembly 100 configured in a cylinder head 10 of the internal combustion engine to control valves of the internal combustion engine.

[0039]

[0022] Figure 1 illustrates a perspective view of a variable valve timing assembly 100 configured in a cylinder head 10 of an internal combustion engine, in accordance with embodiments of the present invention. Figure 2 illustrates a partially exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine, in accordance with the embodiments of the present invention. Figure 3 illustrates a sectional view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the embodiments of the present invention.

[0040]

[0023] As shown, the variable valve timing assembly 100 is configured in the cylinder head 10 of the internal combustion engine. In a non-limiting example, the internal combustion engine is a Dual Overhead Camshaft Engine (DOHC) where an intake camshaft for controlling operations of one or more intake valves and anexhaust camshaft for controlling operations of the one or more exhaust valves is supported by the cylinder head 10 of the internal combustion engine. However, this should not be construed as limiting and the variable valve timing assembly of the present invention can be used for now known or later developed internal combustion engines.

[0041]

[0024] The variable valve timing assembly 100 of the present invention comprises at least one camshaft 102, a sprocket 104, an eccentric coupler 110, 210, 310 and a cam disc 108. The construction of the eccentric coupler 110, 210, 310 can vary as shown in different embodiments covered in Figure 4-6, Figure 7-10 and Figure 11-14. The construction of other elements of the variable valve timing assembly 100 can remain the same or can also change for all the embodiments covered in Figure 4-6, Figure 7-10 and Figure 11-14.

[0042]

[0025] The camshaft 102 is a central rod or a bar that holds one or more cam lobes (not shown). The one or more cam lobes are responsible for opening and closing of the one or more valves (not shown). As the camshaft 102 rotates, each cam lobe of the camshaft 102 pushes against a lifter (or tappet) (not shown), which in turn operates push rods or rocker arms. The shape and size of the lobes determine the timing and lift of the valves. The camshaft 102 can be an intake camshaft and / or an exhaust camshaft.

[0043]

[0026] The sprocket 104 is rotatably configured on the at least one camshaft 102. The sprocket 104 is a toothed gear generally configured on an end of the at least one camshaft 102. The sprocket 104 meshes with and is driven by a timing chain 144 or a timing belt. The sprocket 104 ensures that the camshaft 102 is driven by a crankshaft (not shown) at a correct ratio ensuring that the valves open and close in proper sequence during the operation of the internal combustion engine. In a non-limiting example, the correct ratio is 2:1. The sprocket 104 is rotatably configured on the at least one camshaft 102 by means of a bearing 146. In a non-limiting example, the bearing 146 is a needle bearing. The sprocket 104 can spin independently of the atleast one camshaft 102. An axis of rotation of the sprocket 104 is always coincidental with an axis of rotation of the intake camshaft 102.

[0044]

[0027] The eccentric coupler 110, 210, 310 comprises a mounting hole 148 through which camshaft 102 extends. The eccentric coupler 110, 210, 310 is operably coupled to the sprocket 104 by a driving pin / driving slider pin 126, 226, 326 (shown in Figure 4, Figure 7 and Figure 11) and operably coupled to the cam disc 113 by a driven pin / driven slider pin 128, 228, 328 (shown in Figure 4, Figure 7 and Figure 11). The eccentric coupler 110, 210, 310 is configured such that both the driving pin / driving slider pin 126, 226, 326 and the driven pin / driven slider pin 128, 228, 328 are capable of sliding in a radial direction of the eccentric coupler 110, 210, 310 or in a direction perpendicular to an axis of rotation of the camshaft 102. The different construction and operation of the eccentric coupler 110, 210, 310 are discussed in subsequent paragraphs corresponding to Figure 3-6, Figure 7-10 and Figure 11-14.

[0045]

[0028] The cam disc 108 is operably connected to the camshaft 102 and the eccentric coupler 110, 210, 310. The cam disc 108 is mounted on the camshaft 102 to rotate along with the camshaft 102. The cam disc 108 is configured to transfer rotational motion of the sprocket 104 to the camshaft 112 to rotate the camshaft 102. In other words, rotation of the cam disc 108 will rotate the camshaft 102 as well. The camshaft 102, the sprocket 104 and the cam disc 108 all have the same axis of rotation that is fixed. The eccentric coupler 110, 210, 310 has an axis of rotation allowed to translate in a first direction Fl and a second direction F2 with respect to the axis of rotation of the at least one camshaft 102. In other words, in the present invention, the axis of rotation of the eccentric coupler 110, 210, 310 can be made offset with respect to an axis of rotation of the camshaft 102 upon movement of the eccentric coupler 110, 210, 310 in the first direction Fl or the second direction F2. Change in axis of rotation of the eccentric coupler 110, 210, 310 resulting in rotation of the camshaft 102 at different angular speeds at different points of rotation of the sprocket 104, i.e. the camshaft 102 rotates at different angular speeds at differentpoints of rotation of the camshaft 102 based on change in the axis of rotation of the eccentric coupler 110, 210, 310, as discussed in detail in the subsequent paragraphs.

[0046]

[0029] The cam disc 108 can be secured with the camshaft 102 through a fastener such as bolt 141 to rotate along with the camshaft 102. In addition, the cam disc 108 is rotatably configured with the end plate 142.

[0047]

[0030] To allow selective movement of the eccentric coupler 110, 210, 310 in the first direction Fl and the second direction F2, an eccentric cage 132 and a lead screw mechanism are also provided in the variable valve time assembly 100. The eccentric cage 132 is configured to receive the eccentric coupler 110, 210, 310. In a nonlimiting example, an eccentric bearing 130 is configured in the eccentric cage 1322 and the eccentric coupler 110, 210, 310 is fitted inside the eccentric bearing. 130 The eccentric cage 132 is further configured to be connected to an end plate 142. The end plate 142 is connected to the eccentric cage 132 and is configured to mount the eccentric cage 132 to a cylinder head wall of the cylinder head 10 of the internal combustion engine. The eccentric cage 132 further comprises at least two holes i.e., a first hole 132a configured to receive a guide pin 134 and a second hole 132b configured to receive a lead screw 136 of the lead screw mechanism. In other words, the guide pin 134 extends through the first hole 132a and the lead screw 136 extends through the second hole 132b. The guide pin 134 prevents rotation of the eccentric cage 132 about its own axis and also acts as a supporting member for the eccentric cage 132. The lead screw 136 has a threaded external surface and can rotate about its own axis. The lead screw 136 is coupled with a rotary device 138 and a gear mechanism 140. In a non-limiting example, the rotary device 140 is a motor. In a non-limiting example, the gear mechanism 140 is a worm gear mechanism. The rotary device 138 and the gear mechanism 140 are configured to rotate the lead screw 136 based on inputs received from a control unit (not shown) disposed in the vehicle. In a non-limiting example, the control unit is an engine control unit. In a non-limiting example, the control unit is a vehicle control unit. The inputs are provided by thecontrol unit based on different operating conditions of the internal combustion engine. Upon receiving inputs from the control unit, the rotary device 138 rotates the lead screw 136 either in a first rotational direction or a second rotational direction opposite to the first rotational direction. Since the lead screw 136 is fixed, rotation of the lead screw 136 in either of the first rotational direction or the second rotational direction leads to linear movement of the eccentric cage 132 (operably coupled to the lead screw) in the first direction Fl or the second direction F2 respectively. This linear movement of the eccentric cage 132 results in linear movement of the eccentric bearing 130 and the eccentric coupler 110, 210, 310 along with the eccentric cage 132. Therefore, rotation of the lead screw 136 results in a linear translation of the eccentric coupler 110, 210, 310 causing the axis of rotation of the eccentric coupler 110, 210, 310 to be offset with respect to the axis of rotation of the at least one camshaft 102.

[0048]

[0031] In a non-limiting example, upon a clockwise rotation of the lead screw 136, the eccentric coupler 110, 210, 310 moves towards the rotary device 138 and upon a counterclockwise rotation of the lead screw 136, the eccentric coupler 110, 210, 310 moves away from the rotary device 138. It is to be understood that the rotation of the lead screw 136 can be adjusted to achieve a required offset of the axis of rotation of the eccentric coupler 110, 210, 310 with respect to the axis of rotation of the at least one camshaft 102. In other words, the extent and direction of offset of the axis of rotation of the eccentric coupler 110, 210, 310 with respect to the axis of rotation of the camshaft 102 is dependent on direction and extent of rotation of the lead screw 136. This offset of the axis of rotation of the eccentric coupler 110, 210, 310 is possible owing to sliding of the driving pin / driving slider pin 126,226,326 and the driven pin / driven slider pin 128, 228, 328 in the eccentric coupler 110, 210, 310 as discussed in subsequent paragraphs while explaining different embodiments of the eccentric coupler 110, 210, 310. This movement of the driving pin / driving slider pin 126,226,326 and the driven pin / driven slider pin 128, 228, 328 results in the drivingpin / driving slider pin 126,226,326 and the driven pin / driven slider pin 128, 228, 328 being offset from the axis of rotation of the camshaft 102 at different distances, resulting in a varied angular momentum for the driving pin / driving slider pin 126,226,326 and the driven pin / driven slider pin 128, 228, 328. Even though the driving pin / driving slider pin 126,226,326 and the driven pin / driven slider pin 128,228,328 have the same rotations per minute (RPM), their varied distance from the axis of rotation of the camshaft 102 results in the driving pin / driving slider pin 126,226,326 and the driven pin / driven slider pin 128,228,328 having different relative angular momentum. The pin (driving pin / driving slider pin 126,226,326 or driven pin / driven slider pin 128,228,328) that is further offset from the axis of rotation of the camshaft 102 will have a higher relative angular momentum with respect to a pin (driven pin / driven slider pin 128,228,328 or driving pin / driving slider pin 126,226,326) that is closer to the centre of axis of rotation of the at least one camshaft 102. The different angular momentum of the driving pin / driving slider pin 126,226,326 and the driven pin / driven slider pin 128,228,328 caused due to the linear translation of the eccentric coupler 110, 210, 310 in the first direction Fl results in differing valve timings. Due to the offset motion of the driven pin / driven slider pin 128,228,328 which does not travel in a concentric path to the camshaft 102, there is a timing variation in the rotation of the at least one camshaft 102. Therefore, by adjusting the offset of the axis of rotation of the eccentric coupler 104 by rotating the lead screw 136, the present invention allows the internal combustion engine to operate at three different valve timings i.e., the standard timing, the expanded timing and the retarded timing.

[0049]

[0032] The standard timing is the timing of operation of the valves when the axis of rotation of the eccentric coupler 110, 210, 310 is coincident with the axis of rotation of the at least one camshaft 102. In the standard timing, the camshaft 102 rotates normally and the valves open normally and close normally resulting in normal power delivery by internal combustion engine of the vehicle.

[0033] In the expanded timing, the eccentric coupler 110, 210, 310 linearly translates in the first direction i.e. towards the rotary device 138. This leads to rotation of the at least one camshaft 102 at varied timing resulting in opening of the one or more intake valves by the at least one camshaft 102 for a longer time than the standard opening time and closing of the one or more valves by the at least one camshaft 102 for a shorter time than the standard closing time. In a non-limiting example, in the expanded timing, the intake valves remains open for a longer duration, resulting in an increased power delivery by the internal combustion engine of the vehicle.

[0050]

[0034] In the retarded timing, the eccentric coupler 110, 210, 310 linearly translates in the second direction F2 i.e. away from the rotary device 138. This leads to rotation of the at least one camshaft 102 at varied timing resulting in opening of the one or more intake valves by the at least one camshaft 102 for a shorter time than the standard opening time and closing of the one or more valves by the at least one camshaft 102 for a longer time than the standard closing time. In a non-limiting example, in the retarded timing, the intake valves remains close for a longer duration, resulting in a decreases power delivery by the internal combustion engine of the vehicle.

[0051]

[0035] Figure 4 illustrates a fully exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine where a driving pin and a driven pin are cylindrical shaped pins, in accordance with a first embodiment of the present invention. Figure 5 illustrates a sectional side view of an eccentric coupler coupled with a sprocket and a cam disc through a driving pin and a driven pin which are ball shaped pins, in accordance with the first embodiment of the present invention. Figure 6 illustrates a top sectional plan view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the first embodiment of the present invention.

[0052]

[0036] The variable valve timing assembly 100 shown in Figure 4-6 comprises the camshaft 102, the sprocket 104 rotatably configured on the camshaft 102 androtatably connected to an exhaust cam shaft 101, the cam disc 108 mounted on the camshaft 102, the eccentric cage 132, the eccentric bearing 130, the end plate 142 and a lead screw mechanism, the construction and operation of which are same as that discussed in preceding paragraphs corresponding to Figures 1-3. The construction of the eccentric coupler 110 illustrated in Figure 4-6 is however different from the construction of the eccentric coupler 210, 310 shown in Figure 7-10 and Figures 11-14, which have been discussed in detail herein. The operation of the eccentric coupler 110 is same as discussed in the preceding paragraphs corresponding to Figures 1-3. As shown in Figure 4-6, the eccentric coupler 110 is a generally a circular component such as a disc with a mounting hole 148 through which the camshaft 102, that is an intake camshaft, extends. The eccentric coupler 110 further comprises at least two elongated slots i.e. a first elongated slot 114 and a second elongated slot 116, extending in the radial direction of the eccentric coupler 110. In a non-limiting example, the first elongated slot 114 and the second elongated slot 116 are provided diametrically opposite to each other. However, this should not construed as limiting and other positions of the first and second elongated slots 114, 116 with respect to each other are well within the scope of the present invention. The eccentric coupler 110 further comprises the driving pin 126 and the driven pin 128. The driving pin 126 and the driven pin 128 are cylindrical in shape. The eccentric coupler 110 is coupled to the sprocket 104 by the driving pin 126. One end of the driving pin 126 is connected to the sprocket 104 and other end of the driving pin 126 is slidably received in the first elongated slot 114 of the eccentric coupler 110. In a non-limiting example, the driving pin 126 is press-fitted onto the sprocket 104. The driving pin 126 is configured to slide in the first elongated slot 114 to allow selective movement of the eccentric coupler 110 in the first direction Fl and the second direction F2. Similarly, the eccentric coupler 110 is coupled to the cam disc 108 by the driven pin 128. One end of the driven pin 128 is connected to the cam disc 108 and other end of the driven pin 128 is slidably received in the second elongated slot 116 of theeccentric coupler 110. In a non-limiting example, the driven pin 128 is press-fitted onto the sprocket 104. The driven pin 128 is configured to slide in the second elongated slot 116 to allow selective movement of the eccentric coupler 110 in the first direction Fl and the second direction F2. The driving pin 126 and the driven pin 128 can, therefore, laterally translate across a length of the first elongated slot 114 and the second elongated slot 116, respectively to allow selective movement of the eccentric coupler 110 in the first direction Fl and the second direction F2 based on movement of the eccentric cage 132.

[0053]

[0037] The cam disc 108 can be secured with the camshaft 102 through a fastener such as bolt 141 to rotate along with the camshaft 102. In addition, the cam disc 108 is rotatably configured with the end plate 142 through though a bearing 143 (as shown in Figure 2 and 6) configured in a hole of the end plate 142. A shaft potion of the cam disc 108 is extended through the eccentric cage 132 and the end plate 142.

[0054]

[0038] Figure 7 illustrates a fully exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine where a driving pin and a driven pin are ball shaped pins, in accordance with a second embodiment of the present invention. Figure 8 illustrates a sectional view of the eccentric coupler coupled with the sprocket and the cam disc through a driving pin and a driven pin which are ball shaped pins, in accordance with the second embodiment of the present invention. Figure 9 illustrates a perspective view of the eccentric coupler where a driving pin and a driven pin are ball shaped pins, in accordance with the second embodiment of the present invention. Figure 10 illustrates a top sectional view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the second embodiment of the present invention.

[0055]

[0039] The variable valve timing assembly 100 shown in Figure 7-10 comprises the camshaft 102, the sprocket 104, the cam disc 108, the eccentric cage 132, the eccentric bearing 130, the end plate 142 and the lead screw mechanism, theconstruction and operation of which are same as that discussed in preceding paragraphs corresponding to Figures 1-3. The construction of the eccentric coupler 210 illustrated in Figure 7-10 is however different from the construction of the eccentric coupler 110, 310 shown in Figure 4-6 and Figures 11-14, which has been discussed in detail herein. The operation of the eccentric coupler 210 is same as discussed in the preceding paragraphs corresponding to Figures 1-3. As shown in Figure 7-10, the eccentric coupler 210 is a generally a circular component such as a disc 213 with the mounting hole 248 through which the at least one camshaft 102 extends. The eccentric coupler 210 further comprises a first elongated slot 214 and a second elongated slot 216, extending in the radial direction of the eccentric coupler 210. In a non-limiting example, the first and second elongated slots 214, 216 are provided diametrically opposite to each other. However, this should not construed as limiting and other positions of the first and second elongated slots 214, 216 with respect to each other are well within the scope of the present invention. The eccentric coupler 210 further comprises the driving pin 226 and the driven pin 228. The driving pin 226 and the driven pin 228 are ball shaped pins. The eccentric coupler 210 is coupled to the sprocket 104 by the driving pin 226. The ball shaped driving pin 226 is connected to the sprocket 104 as well as slidably received in the first elongated slot 214 of the eccentric coupler 210. In a non-limiting example, the driving pin 226 is press-fitted onto the sprocket 104. The ball shaped driving pin 226 is configured to slide in the first elongated slot 214 to allow selective movement of the eccentric coupler 210 in the first direction Fl and the second direction F2. Similarly, the eccentric coupler 210 is coupled to the cam disc 108 by the driven pin 228. The ball shaped driven pin 228 is connected to the cam disc 108 as well as slidably received in the second elongated slot 216 of the eccentric coupler 210. In a non-limiting example, the driven pin 228 is press-fitted onto the sprocket 104. The driven pin 228 is configured to slide in the second elongated slot 216 to allow selective movement of the eccentric coupler 210 in the first direction Fl and the second direction F2. Thedriving pin 226 and the driven pin 228 can, therefore, laterally translate across a length of the first elongated slot 214 and the second elongated slot 216, respectively to allow selective movement of the eccentric coupler 210 in the first direction Fl and the second direction F2 based on movement of the eccentric cage 132.

[0056]

[0040] Figure 11 illustrates a fully exploded view of the variable valve timing assembly with the cylinder head of the internal combustion engine depicting an eccentric coupler with a driving slider pin and a driven slider pin configuration, in accordance with a third embodiment of the present invention. Figure 12 illustrates a sectional view of the eccentric coupler coupled with the sprocket and the cam disc through a driving slider pin and a driven slider pin, in accordance with the third embodiment of the present invention. Figure 13 illustrates a perspective view of the eccentric coupler with a driving slider pin and a driven slider pin, in accordance with the third embodiment of the present invention. Figure 14 illustrates a top sectional view of the variable valve timing assembly configured in the cylinder head of the internal combustion engine, in accordance with the third embodiment of the present invention.

[0057]

[0041] The variable valve timing assembly 100 shown in Figure 11-14 comprises the at least one camshaft 102, the sprocket 104, the cam disc 108, the eccentric cage 132, the eccentric bearing 130, the end plate 142 and the lead screw mechanism, the construction and operation of which are same as that discussed in preceding paragraphs corresponding to Figures 1-3. The construction of the eccentric coupler 310 illustrated in Figure 11-14 is however different from the construction of the eccentric coupler 110, 210 shown in Figure 4-6 and Figures 7-10, which has been discussed in detail herein. The operation of the eccentric coupler 310 is same as discussed in the preceding paragraphs corresponding to Figures 1-3. As shown in Figure 11-14, the eccentric coupler 310 comprises an inner ring 318 and an outer ring 320. The outer ring 320 is connected to the inner ring 318 by at least a first rod 322 and a second rod 324. The inner ring 318 comprises a mounting hole 348 throughwhich the at least one camshaft 102 extends. In a non-limiting example, the first rod 322 and the second rod 324 are provided diametrically opposite to each other. However, this should not construed as limiting and other positions of the first rod 322 and the second rod 324 with respect to each other are well within the scope of the present invention. The eccentric coupler 310 further comprises the driving slider pin 326 and the driven slider pin 328 slidably coupled to the first rod 322 and the second rod 324, respectively. Each of the driving slider pin 326 and the driven slider pin 328 comprises a first portion 326a and a second portion 326b. The first portion 326a of the driving slider pin 326 is slidably coupled with the first rod 322 and the second portion 326b of the driving slider pin 326 is connected to the sprocket 104. Similarly, the first portion 328a of the driven slider pin 328 is slidably coupled with the second rod 324 and the second portion 328b of the driven slider pin 328 is connected to the cam disc 108. In a non-limiting example, the second portion 326b of the driving slider pin 326 is press-fitted onto the sprocket 104. In a non-limiting example, the second portion 328b of the driven slider pin 328 of the driven slider pin 328 is press-fitted onto the cam disc 108. In a non-limiting example, the first portion 326a, 328a of each of the driving pin 326 and the driven slider pin 328 comprises a hole corresponding to outer diameter of the first rod 322 and the second rod 324 for slidably coupling the driving slider pin 326 and the driven slider pin 328 on the first rod 322 and the second rod 324, respectively. The driving slider pin 326 slides along the first rod 322 and the driven slider pin 328 slides along the second rod 324 to allow movement of the eccentric coupler 310 in in the first direction Fl and the second direction F2 upon movement the eccentric cage 132. The driving slider pin 326 and the driven slider pin 328 can, therefore, laterally translate across a length of first rod 322 and the second rod 324 respectively to allow movement of the eccentric coupler 310 in in the first direction Fl and the second direction F2 based on movement of the eccentric cage 132.

[0042] The claimed features of the present invention as discussed above are not routine, conventional, or well understood in the art, as the claimed features enable the following solutions to the existing problems in conventional technologies. Specifically, the technical problem of absence of reliable and cost effective WT systems that can ensure peak power delivery at all engine speeds of the vehicle, is solved by present invention.

[0058]

[0043] The present invention provides a reliable, durable and cost-efficient variable valve timing assembly that can ensure peak power delivery at all engine speeds of the vehicle, lower emissions, better mileage, and better handling of the vehicle.

[0059]

[0044] 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

[0060] 10: cylinder head

[0061] 100-variable valve timing assembly 102- camshaft

[0062] 104- sprocket

[0063] 108- cam disc

[0064] 110, 210, 310- eccentric coupler 113, 213- disc

[0065] 114, 214- first elongated slot

[0066] 116, 216- second elongated slot 318- inner ring

[0067] 320- outer ring

[0068] 322- first rod

[0069] 324- second rod

[0070] 126,226,326- driving pin

[0071] 128, 228, 328- driven pin

[0072] 326a- first portion of driving pin 326b- second portion of driving pin28a- first portion of driven pin 28b- second portion of driven pin 130- eccentric bearing

[0073] 132- eccentric cage

[0074] 132a- first hole

[0075] 132b- second hole

[0076] 134- guide pin

[0077] 136- lead screw

[0078] 138- rotary device

[0079] 140- gear mechanism

[0080] 142- end plate

[0081] 144- timing chain

[0082] 146- bearing

[0083] 148, 248, 348- mounting hole Fl- first direction

[0084] F2- second direction

Claims

WE CLAIM:

1. A variable valve timing assembly (100) for an internal combustion engine (10), the variable valve timing assembly (100) comprising:at least one camshaft (102), the at least one camshaft (102) adapted to operate one or more valves of the internal combustion engine (10);a sprocket (104) rotatably configured on the at least one camshaft (102), the sprocket (104) being connected to and driven by a crankshaft of the internal combustion engine (10);a cam disc (108) operably connected to the at least one camshaft (102), the cam disc (108) being configured to transfer rotational motion of the sprocket (104) to the at least one camshaft (102) to rotate the at least one camshaft (102);an eccentric coupler (110, 210, 310), the eccentric coupler (110, 210, 310) being operably couple with the sprocket (104) and the cam disc (108), wherein the eccentric coupler (110, 210, 310) is configured to selectively move in a first direction (Fl) and a second direction (F2) opposite the first direction (Fl) such that an axis of rotation of the eccentric coupler (110, 210, 310) is offset with respect to an axis of rotation of the at least one camshaft (102) upon movement of the eccentric coupler (110, 210, 310) in the first direction (Fl) or the second direction (F2), andwherein the rotation of the eccentric coupler (110, 210, 310) at a different axis of rotation with respect to the axis of rotation of the at least one camshaft (102) resulting in rotation of the at least one camshaft (102) at different angular speeds at different points of rotation of the sprocket (104).

2. The variable valve timing assembly (100) as claimed in claim 1, wherein the at least one camshaft (102) being one of an intake camshaft and an exhaust camshaft.

3. The variable valve timing assembly (100) as claimed in claim 1, wherein the eccentric coupler (110, 210) comprises a disc (113, 213) with a mounting hole (148, 248) through which the at least one camshaft (102) is extended, the disc (113, 213) having at least a first elongated slot (114, 214) and a second elongated slot (116, 216) provided diametrically opposite to each other and extending in a radial direction of the disc (113, 213).

4. The variable valve timing assembly (100) as claimed in claim 3, wherein the eccentric coupler (110, 210) comprises:a driving pin (126, 226); anda driven pin (128, 228),wherein the sprocket (104) and the eccentric coupler (110, 210) being coupled by the driving pin (126, 226), one end of the driving pin (126, 226) being connected to the sprocket (104) and other end of the driving pin (126, 226) being received in the first elongated slot (114, 214) of the eccentric coupler (110, 201), the driving pin (126, 226) being configured to slide in the first elongated slot (114, 214) to allow selective movement of the eccentric coupler (110, 210) in the first direction (Fl) and the second direction (F2), and wherein the cam disc (108) and the eccentric coupler (110, 210) being coupled by the driven pin (128, 228), one end of the driven pin (128, 228) being connected to the cam disc (108) and other end of the driven pin (128, 228) being received in the second elongated slot (116, 216) of the eccentric coupler (114, 214), the driven pin (128, 228) being configured to slide in the second elongated slot (116, 216) to allow selective movement of the eccentric coupler (110, 210) in the first direction (Fl) and the second direction (F2).

5. The variable valve timing as claimed in claim 4, wherein the driving pin (126, 226) and the driven pin (128, 228) being one of cylindrical shaped pins and ball shaped pins.

6. The variable valve timing assembly (100) as claimed in claim 1, wherein the eccentric coupler (310) comprises:an inner ring (318);an outer ring (320) connected to the inner ring (318) by a first rod (322) and a second rod (324), the first rod (322) and the second rod (324) being provided diametrically opposite to each other;a driving slider pin (326) being slidably configured with the first rod (322); anda driven slider pin (328) being slidably configured with the second rod (324).

7. The variable valve timing assembly (100) as claimed in claim 6, wherein:the sprocket (104) and the eccentric coupler (310) being coupled by the driving slider pin (326), one end of the driving slider pin (326) being connected to the sprocket (104) and other end of the driving slider pin (326) being slidably disposed on the first rod (322) of the eccentric coupler (310), the driving slider pin (326) being configured to slide on the first rod (322) to allow selective movement of the eccentric coupler (310) in the first direction (Fl) and the second direction (F2); andthe cam disc (108) and the eccentric coupler (310) being coupled by the driven slider pin (328), one end of the driven slider pin (328) being connected to the cam disc (108) and other end of the driven slider pin (328) being slidably disposed on the second rod (324) of the eccentric coupler (314), the driven slider pin (328) being configured to slide on the second rod (324) to allow selective movement of the eccentric coupler (310) in the first direction (Fl) and the second direction (F2).

8. The variable valve timing assembly (100) as claimed in claim 1, comprising a linear motion mechanism, the linear motion mechanism being adapted toselectively move the eccentric coupler (110, 210, 310) in the first direction (Fl) and the second direction (F2).

9. The variable valve timing assembly (100) as claimed in claim 8, wherein the linear motion mechanism comprises:an eccentric cage (132), the eccentric cage (132) comprising at least a first hole (132a) and a second hole (132b);a guide pin (134) extended through the first hole (132a) for preventing rotation of the eccentric cage (132); anda lead screw (136) extended through the second hole (132b); a rotary device (138); anda gear mechanism (140);wherein the lead screw (136) is operably coupled to the rotary device (138) by the gear mechanism (140); andwherein the rotary device (138) being adapted to selectively rotate the lead screw (136) in a first rotational direction and a second rotational direction opposite the first rotational direction based on one or more inputs received from an engine control unit, the rotation of the lead screw (138) in the first rotational direction enabling linear movement of the eccentric cage (132) along with the eccentric coupler (110, 210, 310) in the first direction (Fl) and the rotation of the lead screw (138) in the second rotational direction enabling linear movement of the eccentric cage (132) along with the eccentric coupler (110, 210, 310) in the second direction (F2).

10. The variable valve timing assembly (100) as claimed in claim 9, comprising an eccentric bearing (130) configured in the eccentric cage (132), wherein the eccentric coupler (110) is fitted inside an eccentric bearing (130).

11. The variable valve timing assembly (100) as claimed in claim 1, wherein, movement of the eccentric coupler (110, 210, 310) in the first direction (Fl) leads to a shift of an axis of rotation of the eccentric coupler (110, 210, 310) in the first direction (Fl) with respect to an axis of rotation of the at least one camshaft (102) resulting in opening of the one or more valves by the camshaft (102) for a longer time than a standard opening time and closing of the one or more valves by the camshaft (102) for a shorter time than a standard closing time, the standard opening time and the standard closing time being timings of operation of the one or more valves when the axis of rotation of the eccentric coupler (110, 210, 310) being coincident with the axis of rotation of the at least one camshaft (102).

12. The variable valve timing assembly (100) as claimed in claim 1, wherein movement of the eccentric coupler (110, 210, 310) in the second direction (F2) leads to a shift of an axis of rotation of the eccentric coupler (110, 210, 310) in the second direction (F2) with respect to an axis of rotation of the at least one camshaft (102) resulting in opening of the one or more valves by the camshaft (102) for a shorter time than a standard opening time and closing of the one or more valves by the camshaft (102) for a longer time than a standard closing time, the standard opening time and the standard closing time being timings of operation of the one or more valves when the axis of rotation of the eccentric coupler (110, 210, 310) being coincident with the axis of rotation of the at least one camshaft (102).

13. The variable valve timing assembly as claimed in claim 9, wherein the eccentric cage (132) being configured with an end plate (142), the end plate (142) being adapted to be mounted on a cylinder head of the internal combustion engine (10)14. An internal combustion engine for a vehicle, comprising:a cylinder head; anda variable valve timing assembly (100) configured in the cylinder head, the variable valve timing assembly (100) comprising:at least one camshaft (102), the at least one camshaft (102) adapted to operate one or more valves of the internal combustion engine (10);a sprocket (104) rotatably configured on the at least one camshaft (102), the sprocket (104) being connected to and driven by a crankshaft of the internal combustion engine (10);a cam disc (108) operably connected to the at least one camshaft (102), the cam disc (108) being configured to transfer rotational motion of the sprocket (104) to the at least one camshaft (102) to rotate the at least one camshaft (102);an eccentric coupler (110, 210, 310), the eccentric coupler (110, 210, 310) being operably couple with the sprocket (104) and the cam disc (108), wherein the eccentric coupler (110, 210, 310) is configured to selectively move in a first direction (Fl) and a second direction (F2) opposite the first direction (Fl) such that an axis of rotation of the eccentric coupler (110, 210, 310) is offset with respect to an axis of rotation of the at least one camshaft (102) upon movement of the eccentric coupler (110, 210, 310) in the first direction (Fl) or the second direction (F2), andwherein the rotation of the eccentric coupler (110, 210, 310) at a different axis of rotation with respect to the axis of rotation of the at least one camshaft (102) resulting in rotation of the at least one camshaft (102) at different angular speeds at different points of rotation of the sprocket (104).

Images