The present subject matter described herein, relates to an internal combustion engine with naturally aspirated or turbocharged, PFI or Direct injection engine for all fuel type having intake and exhaust valve operated by a single cam lobe, and, in particular, to a end pivoted rocker arm with double actuating valves using single cam Lobe and independent valve lash adjustment mechanism for each valve with and without Hydraulic Lash Adjuster (HLA) arrangement to make compact and low friction in the valve.
BACKGROUND AND PRIOR ART:
[002] In the four valve internal combustion engine, the internal combustion engine has two intake valves and two exhaust valves per cylinder. Currently, intake and exhaust valves are controlled and operated by single camshafts with individual cam lobes (for each valve) located in the engine. The intake valves opens in order to take fuel and air into a cylinder for combustion, while exhaust valves opens to allow combustion gas to escape from the cylinder. The intake and exhaust valves are actuated by the cam lobes which moves the intake and exhaust valves up and down as per the motion of the camshaft. Further, the cam lobe pushes rocker arm connected with the intake and exhaust valves and actuates the up and down movement of the valves.
[003] Fig. 1a and 1b illustrate the two end pivoted rocker arm actuated by two cam lobe for movement of valve as known in the art. The camshaft 102 has two cam lobes 102a and 102b. The two end pivoted rocker arms 104 are connected with the valves 106 of the engine. The rocker arms 104 have roller and pivot point. Wherein the valves 106 are connected with the top with the rocker arm 104 from one side and other side has lash adjuster to adjust the lash with the help of a screw 104a and nut 104b. Both the sides are pivoted to center roller 104d or center sliding contact 104c which is actuated by the cam lobe of the camshaft 102. Generally, valve has very small gap which is called valve lash that take care of thermal expansion and affects every stroke of the four stroke internal combustion engine. Resultantly, efficiency of the engine degrades and valve creates sound during movement of valve if lash is not controlled properly. In order to control the valve lash, screw 104a and nut 104b provided on the valve lash adjuster is tightened accordingly. Therefore, valve lash of one rocker arm is adjusted by the screw provided in the lash adjuster in the rocker arm. Fig. 1c illustrates the valve arrangement with Hydraulic Lash adjuster pivoted in the rocker arm.
[004] US Patent Publication US 7861680 B2 titled pushrod engine with multiple independent lash adjusters for each pushrod. The US patent discloses a multiple-cylinder internal combustion engine having a camshaft-driven valve train with a camshaft disposed within an engine block includes at least two intake and/or exhaust valves with multiple valves operated by a common lifter and pushrod that engages a follower having multiple independent lash adjusters coupled to associated rocker arms. The lifter contacts the common camshaft lobe and a corresponding pushrod that engages a reciprocating bucket follower with a compliant coupling to corresponding rocker arms. In this patent, single end pivoted rocker arm concept is not disclosed.
[005] Generally, in four wheel vehicles or heavy engine having more than 500cc capacity, single end pivoted rocker arm is used to actuate single valve in engine. Modern engines are mostly actuated through end pivot type of roller finger followers (rocker arm) where roller is placed just below the cam lobe. Rotation of the cam lobe over the roller of the rocker arm moves the valve up and down for strokes of the engine. Existing designs of the rocker arm is not feasible to use single end pivoted rocker arm to actuate two valves simultaneously. A single end pivoted rocker arm for such mechanism will not be able to accommodate the variation in component manufacturing to cater the valve lash.
[006] Fig. 2a, 2b and 2c illustrates the single end pivoted rocker arm for actuating double valve using single cam lobe. In the existing single end pivoted rocker arm which actuates both the valves together, the arm and valve adjuster is pivoted with the roller 200c of the rocker arm 200. One end of rocker arm 200 is connected with the valve 200 and the valve adjuster is used to adjust the valve lash. The present end pivoted rocker arm 200 has two arms, i.e., arm 200a and 200b to actuate two valves 206. Both the arms 200a and 200b are integrated with each other and form a single end pivoted rocker arm 200. The rocker arm 200 is actuated by the cam lobe 202a from the roller 200c of the rocker arm 200. The rocker arm 200 comprises two arms 200a, 200b and center roller 200c. Both the arms are pivoted with the center roller 200c. Further, the center roller receives the push from the cam lobe 202a of the camshaft to actuate the valve. Both the arms 200a and 200b are fixedly integrated with each other or are made from single mold, therefore, if valve adjustment screw of one arm is adjusted, it will rotate both the arms 200a and 200b. Accordingly, valve lash for both of the valve tips changes together which nullify the purpose of valve lash adjustment.
[007] Though these prior arts provide the single end pivoted rocker arm for actuating the double valve, but the end purpose, i.e., valve lash adjustment is not achieved from the same. Technical problem for the present invention is to actuate two valves with single end pivoted rocker arm or using hydraulic lash adjuster at two locations to improve the stability while keeping the provision for independent valve lash adjustment for each valve. In each arrangement of the rocker arm and valve, valve lash adjusting screw is located at pivot end of rocker arm in place of valve tip side of rocker arm due to space and accessibility constraints for tightening the screw at valve tip side rocker arm end. If the arm 200a and arm 200b is made integral, it will lead to issue in independent valve lash adjustment to cater dimensional variation of valve lash related component. Further, the technical problem is to use single pivot point for actuating two valve lead to tilting of rocker arm due to variation in valve load/ dimensional variation in valve tip height and lead to uneven wear of cam and roller contact patch. Further, if HLA is used along with rocker arm actuating two valves then zero lash condition cannot be achieved.
[008] In order to cater all the above mentioned technical problems, a simple, inexpensive, and a single end pivoted rocker arm system is required to actuate double valve through a single cam lobe and to adjust valve lash independently from the other valve.
OBJECTS OF THE INVENTION:
[009] The principal objective of the present invention is to provide a single end pivoted rocker arm assembly to actuate double valve using single cam lobe in the internal combustion engine.
[0010] Another object of the present subject matter is to provide a single end pivoted rocker arm assembly to adjust the valve lash of two valves independently from each other.
[0011] Another object of the present subject matter is to provide a single end pivoted rocker assembly which has one arm free to rotate on roller shaft to set the valve lash independently.
[0012] Yet another object of the present invention is to provide a single end pivoted rocker arm assembly which reduces the number of cam lobe to half and cam shaft size also.
SUMMARY OF THE INVENTION:
[0013] The subject matter disclosed herein relates to structure of single end pivoted rocker arm assembly for actuating double valve using single cam shaft lobe and adjusting valve lash independently in internal combustion engine. The present single end pivoted rocker arm assembly has two arms integrated with each other. In present single end pivoted rocker arm assembly, first arm is integrated with second arm through roller shaft. The first arm is press fitted with the roller shaft, therefore, both the roller shaft and the first arm move as a single part. Further the second arm is rotatably connected with the roller shaft. The rotation of the first arm does not affect the rotation of the second arm. While adjusting the valve lash of the valve, one valve lash adjustment will not affect the valve lash adjustment of second valve. Adjustment of valve lash of both the valve is independent from each other due to rotatable integration of the first and the second arm in the single end pivoted rocker arm assembly. When the cam shaft lobe rolls over the roller, it pushes the roller of the single end pivoted rocker arm assembly in downward direction. Along with the roller, the complete single end pivoted rocker arm assembly moves in downward and upward direction, and oscillates about the vertical direction. In the present single end pivoted rocker arm assembly, double valve is actuated from a single cam shaft lobe which reduces the requirement of cam shaft lobes in the internal combustion engine.
[0014] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0016] Fig. 1a, fig. 1b, and fig. 1c illustrate single end pivoted rocker arm for actuating single valve as known in the art;
[0017] Fig. 2a, fig. 2b and fig. 2c illustrate single end pivoted rocker arm structure for actuating double valve in the internal combustion engine, in accordance with an embodiment of the present subject matter;
[0018] Fig. 3 illustrates structure of single end pivoted rocker arm assembly for actuating double valve using single cam shaft lobe and adjusting valve lash independently, in accordance with an embodiment of the present subject matter;
[0019] Fig. 4 illustrates single end pivoted rocker arm assembly with two valves, in accordance with an embodiment of the present subject matter;
[0020] Fig. 5 illustrates another view of single end pivoted rocker arm assembly with two valves, in accordance with an embodiment of the present subject matter; and
[0021] Fig. 6 illustrates working and motion of the single end pivoted rocker arm assembly with respect to cam shaft lobe and valve, in accordance with an embodiment of the present subject matter.
[0022] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0023] The subject matter disclosed herein relates to structure of single end pivoted rocker arm assembly for actuating double valve using single cam shaft lobe and adjusting valve lash independently in internal combustion engine. The present single end pivoted rocker arm assembly has two arms integrated with each other. In present single end pivoted rocker arm assembly, first arm is integrated with second arm through roller shaft. Further, a roller is fitted on the roller shaft using needle bearing to provide contact face with the single cam shaft lobe. The first arm is press fitted with the roller shaft, therefore, both the roller shaft and the first arm move as a single part. Further the second arm is rotatably connected with the roller shaft. Accordingly, rotation of the first arm does not affect the rotation of the second arm. Both the arms are independent from each other in rotational way, because first arm is fixed with the roller shaft and second arm is rotatably connected with the roller shaft. While adjusting the valve lash of the valve, one valve lash adjustment will not affect the valve lash adjustment of second valve. Adjustment of valve lash of both the valve is independent from each other due to rotatable integration of the first and the second arm in the single end pivoted rocker arm assembly. When the cam shaft lobe rolls over the roller, it pushes the roller of the single end pivoted rocker arm assembly in downward direction. Along with the roller, the complete single end pivoted rocker arm assembly moves in downward and upward direction, and oscillates about the vertical direction. In the present single end pivoted rocker arm assembly, double valve is actuated from a single cam shaft lobe which reduces the requirement of cam shaft lobes in the internal combustion engine. Further, the present single end pivoted rocker arm assembly reduces the size and friction in the cam shaft in the internal combustion engine.
[0024] Conventional, single end pivoted rocker arm for actuating the double valve exists, but the main purpose, i.e., valve lash adjustment is not achieved from the same. In arrangement of the rocker arm and valve, valve lash adjusting screw is located at pivot end of rocker arm in place of valve tip side of rocker arm due to space and accessibility constraints for tightening the screw at valve tip side rocker arm end. In the existing rocker arm both the arms are made integral with each other, therefore, fixed integration of one arm with the another arm leads to an issue of independent valve lash adjustment to cater dimensional variation of valve lash in the valve placement. Further, the technical problem is to use single pivot point for actuating two valve lead to tilting of rocker arm due to variation in valve load/ dimensional variation in valve tip height and lead to uneven wear of cam and roller contact patch. Further, if HLA is used along with rocker arm actuating two valves then zero lash condition cannot be achieved. Therefore, the existing systems do not provide independent valve lash adjustment in the single end pivoted rocker arm assembly.
[0025] The present subject matter provides a single end pivoted rocker arm assembly for actuating double valve using single cam shaft lobe and adjusting valve lash independently in internal combustion engine. In the present single end pivoted rocker arm assembly two arms are integrated with each other to actuate two valves. Further, first arm is integrated with second arm through roller shaft. Furthermore, a roller is fitted on the roller shaft using needle bearing to provide contact face with the single cam shaft lobe. The first arm is press fitted with the roller shaft, therefore, both the roller shaft and the first arm move as a single part. Further the second arm is rotatably connected with the roller shaft which rotates around the roller shaft during adjustment of the valve lash. Accordingly, rotation of the first arm will not affect the rotation of the second arm. Both the arms are independent from each other in rotational way. While adjusting the valve lash of the valve, valve lash adjustment of one valve does not affect the valve lash adjustment of second valve.
[0026] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0027] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0028] Fig. 3 illustrates structure of single end pivoted rocker arm assembly for actuating double valve using single cam shaft lobe and adjusting valve lash independently, in accordance with an embodiment of the present subject matter. The single end pivoted rocker arm assembly 300 has two arms, i.e., first arm 300a and second arm 300b. The first rocker arm 300a has two ends where one end 302 connects with valve tip and other end 306 has valve lash adjuster 316. Similarly, the second arm 300b has two ends where one end 304 connects with the valve tip and other end 308 has valve lash adjuster 316.
[0029] Single end pivoted rocker arm assembly can also be produced where in arm 300a is free to rotate and 300b is fixed with roller shaft 314. Single end pivoted rocker arm assembly can also be produced where in arm 300a and 300b both are free to rotate on center roller shaft 314. With all type of construction where either one arm is free or both arm is free to rotate can serve the same purpose where we can independently adjust the valve lash of both the valves.
[0030] The second arm 300b is rotatably integrated with the first arm 300a through roller shaft 314. On the roller shaft 314 a roller 310 is fitted using needle bearing. To allow independent rotation between the first arm 300a and second arm 300b, Second arm 300b is made free to rotate on the roller shaft 314 which is press fitted to the first arm 300a. Further, the roller 310 provides contact surface to the single cam shaft lobe to push the single end pivoted rocker arm assembly 300. The first arm 300a is press fitted with the roller shaft 314 and moves as a single part. Further, the second arm 300b is connected with the roller shaft 314 using rotational joint and free to rotate on the roller shaft 314. The roller shaft 314 allows rotational motion 312 to the second arm 300b about center of the roller shaft 314. In present connection of the roller shaft 314 and the second arm 300b, the roller shaft 314 does not rotate and also the first arm 300a during rotation of the second arm 300b and vice versa.
[0031] The second arm 300b is free to rotate on the roller shaft 314 during adjustment of the valve lash. The valve lash adjustment of both the valves is independent from each other in the present single end pivoted rocker arm assembly 300. Accordingly, rotation of the first arm 300a does not affect the rotation of the second arm 300b about the roller shaft 314. Adjustment of valve lash of both the valves is independent from each other due to rotatable integration of the first and the second arm in the single end pivoted rocker arm assembly. The valve lash of first valve is adjusted using tightening/untightening of valve gap adjusting screw 306a of the valve lash adjuster 306. While adjusting valve lash of the first valve using the valve gap adjusting screw 306a, it allows the rotation of the first arm 300a about center of the roller shaft 314 and adjust the gap at valve tip between first valve and face of the first arm 300a. During the procedure to adjust the valve lash of first valve using the first arm 300a, the second arm 300b does not rotate because it is free to rotate with respect to the roller shaft 314, and resultantly, there is no change in valve lash at valve tip of the second valve connected with the second arm 300b. With HLA automatic adjustment will happen for valve lash.
[0032] Similarly, during valve lash adjustment of second valve using valve gap adjusting screw 308a of the valve adjuster 308 of the second arm 300b rotates about the center of the roller shaft 314 and adjusts the gap at valve tip between the second valve and face of the second arm 300b. The roller shaft 314 does not rotate and also the first arm 300a therefore, there is no impact on valve lash at the first valve. With HLA automatic adjustment will happen for valve lash.
[0033] Further, the cam shaft lobe rolls over the roller 310, it pushes the roller 310 present at the center pivoted position of the single end pivoted rocker arm assembly 300 in downward direction. Along with the roller 310, the complete single end pivoted rocker arm assembly 300 moves in downward direction, and oscillates in the vertical direction. Further, the movement of the first arm 300a and the second arm 300b is fixed in the vertical direction. Therefore, both the arms 300a and 300b oscillates move together as a single arm to actuate two valves at same point.
[0034] The first arm 300a and the second arm 300b are pivoted at the end in the single end pivoted rocker arm assembly 300, therefore, it can be referred as double end pivoted single end pivoted rocker arm assembly. Further, the roller 310 is provided at the center to push the complete single end pivoted rocker arm assembly together. The single end pivoted rocker arm assembly 300 actuates the two valves from a single cam shaft lobe.
[0035] Fig. 4 illustrates single end pivoted rocker arm assembly with two valves, in accordance with an embodiment of the present subject matter. In the present assembly 400, the single end pivoted rocker arm assembly 300 is mounted on the two valves 406. The one end 302 and 304 of the single end pivoted rocker arm assembly 300 is connected with the valve 406.
[0036] Fig. 5 illustrates another view of single end pivoted rocker arm assembly with two valves, in accordance with an embodiment of the present subject matter. The present figure illustrates the front view 500 of the single end pivoted rocker arm assembly 300 with two valves 506. The two valves have spring 504 in between the single end pivoted rocker arm assembly 300 and valves 506. The spring 504 helps in the vertical oscillation of the valve.
[0037] Fig. 6 illustrates working and motion of the single end pivoted rocker arm assembly with respect to cam shaft lobe and valve, in accordance with an embodiment of the present subject matter. In the present assembly 600, the single end pivoted rocker arm assembly 300 is in contact with the single cam shaft ob 602. During rotation of the cam shaft, the cam shaft lobe 602 pushes the roller 614 (310 in figure 3) in downward direction. The roller 614 forces both arms 300a and 300b of the single end pivoted rocker arm assembly 300 in downward direction. Since both the arms 300a and 300b fixed in vertical motion. Therefore, both arms moves in downward direction at same time along with the roller shaft 314 and provide desired equal valve lift to both the valves 612. The camshaft lobe 602 rotates in direction 604. When the cam shaft lobe 602 is not pushing the roller 614 of the single end pivoted rocker arm assembly 300, the springs 610 of the valves 612 pushes both arms 300a and 300b of the single rocker assembly 300 in upward direction. Accordingly, valves 612 oscillate in vertical direction 610 and also single end pivoted rocker arm assembly 300 in vertical direction 608. Both arms of the single end pivoted rocker assembly 300 are free to rotate in 616 directions from each other, and move as a single part in vertical direction 608.
[0038] The present single end pivoted rocker arm assembly 300 actuates two valves simultaneously with singe cam shaft lobe. Therefore, number of cam shaft lobes reduced to half and cam shaft size is also reduced. Due to rotational integration of first arm and second arm, it is possible to adjust the valve lash independently for both the valves. Further, the valve timing for opening and closing is not hampered by the single end pivoted rocker arm. The use of single roller for actuating two valves leads to reduction in the cost of manufacturing of the rocker arms.
[0039] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

Claims:We claim:
1.A single end pivoted rocker arm assembly (300) for actuating double valve (612) using single cam shaft lobe (602) and adjusting valve lash independently, the single end pivoted rocker arm assembly (300) comprising:
a first arm (300a);
a second arm (300b) integrated with the first arm (300a) through a roller shaft and rotational joint (314).

2. The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein the second arm (300b) is free to rotate on the roller shaft (314).
3.The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein the single end pivoted rocker arm assembly (300) comprises a roller (310) which is fitted on the roller shaft (314) using needle bearing to provide contact face with the single cam shaft lobe (602).

4.The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein the first arm (300a) is press fitted on the roller shaft (314).

5.The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein the roller shaft (314) oscillates along roller (310) movement actuated by the single cam shaft lobe (602).

6.The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein one end (302) of the first arm (300a) is connected to first valve (612) and other end has valve lash adjuster (306).

7.The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein one end (304) of the second arm (300b) is connected to second valve (612) and other end is has a valve adjuster (308).

8. The single end pivoted rocker arm assembly (300) as claimed in claim 7, wherein the valve adjuster (306, 308) is Hydraulic Valve Lash Adjuster (HLA).

9. The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein the single end pivoted rocker arm assembly (300) is double pivoted at end.
10. The single end pivoted rocker arm assembly (300) as claimed in claim 1, wherein the first arm (300a) is free to rotate in the roller shaft (314), where the second arm (300b) is fixed with the roller shaft (314), wherein the first arm (300a) and the second arm (300b) both can be free to rotate in the roller shaft (314). ,