DESC:TECHNICAL FIELD
[001] The embodiments herein generally relate to internal combustion engines, more particularly but not exclusively to a camshaft of an internal combustion engine having an internal oil passage (oil channel) for lubricating the camshaft and camshaft bearing assembly.
BACKGROUND
[002] Generally, lubrication system in an engine is used to supply lubrication oil to engine moving parts thereby reducing friction between the moving parts. Conventional engine assembly includes a cylinder head having integrated lower bearing caps, where one lower bearing cap is used to facilitate mounting of an intake camshaft and the other lower bearing cap is to facilitate mounting of an exhaust camshaft. Separate upper bearing caps are mounted onto corresponding lower bearing caps of the cylinder head thereby securing intake camshaft and exhaust camshaft to the cylinder head and also provides space for housing the camshaft bearings. Separate oil galleries provided in the cylinder head are fluidly connected to corresponding lower bearing cap of the cylinder head for lubricating corresponding camshaft bearings. The arrangement and method of providing oil to camshaft bearings and a hydraulic tensioner in the aforementioned engine assembly is complex in design and incur high manufacturing costs.
[003] In conventional designs, the cross drills in crankcase for the camshaft bearing lubrication mainly crosses from a main bearing wall area near to load line in structure. This creates a notch effect and leads to durability issues with fatigue failures. Further, it also reduces the efficiency of crankcase machining process since it adds to number of operations and corresponding setups for the crankcase machining due to different inclinations. It eventually adds to the machining cost. Furthermore, these cross drills are required to be plugged from outside, making the architecture prone to leakages, additional assembly operations and increasing hardware cost. There is a need to eliminate the above mentioned disadvantages of conventional design while simultaneously meeting the objectives of efficient lubrication, machining & assembly.
[004] Therefore, there exists a need for a camshaft having an internal oil passage (oil channel) which obviates the aforementioned drawbacks.
OBJECTS
[005] The principal object of the embodiments disclosed herein is to provide a camshaft having an internal oil passage (oil channel) for lubricating the cam shaft and cam bearing assembly.
[006] Another object of the embodiments disclosed herein is to provide a plurality of cross oil passages (branches) extending from the internal oil passage (oil channel) for lubricating camshaft bearings through the camshaft.
[007] Yet another object of the embodiments disclosed herein is to provide a camshaft having an internal oil passage (oil gallery) to address fatigue failures due to stress concentration of notch effect due to machining of oil gallery for camshaft lubrication.
[008] Still another object of the embodiments disclosed herein is to reduce possible machining operations on a crankcase.
[009] Also another object of the embodiments disclosed herein is to provide an inexpensive camshaft for an internal combustion engine.
[0010] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0011] The embodiments of the invention are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0012] FIG. 1 depicts a perspective view of a camshaft, according to an embodiment of the invention as disclosed herein;
[0013] FIG. 2 depicts a sectional view of a crankcase and oil passage, according to an embodiment of the invention as disclosed herein;
[0014] FIG. 3 depicts a perspective view of a camshaft having plurality of openings for lubrication, according to an embodiment of the invention as disclosed herein;
[0015] FIG. 4 depicts a sectional view of a camshaft having passage for oil for lubrication of camshaft bearings through the camshaft, according to an embodiment of the invention as disclosed herein;
[0016] FIG. 5 depicts a rear view of a camshaft having passage for oil for lubrication, according to an embodiment of the invention as disclosed herein;
[0017] FIG. 6 depicts front view of a camshaft having passage for oil for lubrication, according to an embodiment of the invention as disclosed herein;
[0018] FIG. 7 depicts rear perspective view of a camshaft having passage for oil for lubrication, according to an embodiment of the invention as disclosed herein;
[0019] FIG. 8 depicts front perspective view of a camshaft having passage for oil for lubrication, according to an embodiment of the invention as disclosed herein;
[0020] FIG. 9 depicts sectional view of a camshaft having passage for oil for lubrication and assembled in a crankcase, according to an embodiment of the invention as disclosed herein; and
[0021] FIG. 10 depicts sectional view of a camshaft having passage for oil for lubrication and oil flow in rear journal bearing, according to an embodiment of the invention as disclosed herein.

DETAILED DESCRIPTION
[0022] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0023] The embodiments herein achieve a camshaft having an integrated oil passage (oil channel). Further, the embodiments herein achieve a plurality of cross passages extending from the integrated oil passage for lubricating camshaft bearings through the camshaft. Referring now to the drawings, and more particularly to FIGS. 1 through 10, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0024] FIG. 1 depicts a perspective view of a camshaft, according to an embodiment of the invention as disclosed herein. The embodiments herein relate to a camshaft 100 for a heavy-duty diesel engine which includes an integrated oil passage 110 (hereafter referred as second oil channel 110 (or oil channel) in this description) for the camshaft lubrication.
[0025] FIG. 2 depicts a sectional view of a crankcase and oil passage, according to an embodiment of the invention as disclosed herein. In an embodiment, the camshaft 100 includes an engine (not shown), a cylinder head (not shown), a main oil gallery (not shown) (also referred as oil gallery), a shaft 102, a first end 102a, a second end 102b, a front journal 104, a rear journal 106, a first oil passage 108, a second oil passage 110 (oil passage or oil channel), a third branched oil passage 112, a cam portion 114, a journal portion 116, and at least one plug 118.
[0026] FIG. 3 depicts a perspective view of a camshaft having plurality of openings for lubrication, according to an embodiment of the invention as disclosed herein. The camshaft 100 includes the shaft 102. The shaft 102 is disposed between the first end 102a and the second end 102b. Further, the shaft 102 is adapted to be rotatably journaled between the front journal 104 and the rear journal 106 as shown in FIG. 4. The shaft 102 further includes a plurality of longitudinally spaced cam portions 114 and a plurality of journal portions 116 thereon.
[0027] FIGS. 5 and 7 depict a rear view and rear perspective view of a camshaft having passage for oil for lubrication, according to an embodiment of the invention as disclosed herein. The camshaft 100 further includes the rear journal 106. The rear journal 106 includes at least one first oil passage (first oil channel) 108 to receive oil from the oil gallery through at least one oil groove 120. The oil groove 120 is defined in a cam bush on the cylinder head. The rear journal 106 may include at least four first oil passages 108 disposed radially from a central axis A which extends until to a rear journal bearing surface 106a defined away from the central axis A. The at least four first oil passages 108 are configured to receive oil from said oil gallery through the oil groove 120. The first oil passages 108 may receive the oil from the oil gallery in at least one of continuously and intermittently.
[0028] FIGS. 6 and 8 depict front view and front perspective view of a camshaft having passage for oil for lubrication, according to an embodiment of the invention as disclosed herein. The camshaft 100 further includes the front journal 104. The front journal 104 includes at least two third branched oil passages 112 which extend from the second oil passage 110. The third branched oil passages 112 radially extends from the central axis A to a front journal bearing surface 104a defined away from the central axis A.
[0029] FIG. 9 depicts sectional view of a camshaft having passage for oil for lubrication and assembled in a crankcase, according to an embodiment of the invention as disclosed herein. The camshaft 100 further includes the at least one second oil passage 110 (oil channel). The second oil passage 110 extends internally from the front journal 104 to the rear journal 106. The second oil channel 110 is adapted to receive oil from the oil gallery through the rear journal 106. Further, the second oil passage 110 is blocked at both the first end 102a and the second end 102b by at least one plug 118 as shown in FIGS. 9 and 10. The camshaft 100 further includes the at least one third branched oil passage (oil channel) 112. The camshaft 100 may include plurality of third branched oil passages 112. The third branched oil passage 112 extends radially from the second oil channel 110 to a bearing surface 116a. Each journal portion 116 includes at least two third branched oil passages 112 which are disposed radially from the central axis A to a bearing surface 116a defined away from the central axis A. The third branched oil passages 112 are adapted to supply oil to the journal portions 116 of the shaft 102.
[0030] The embodiments herein facilitates in eliminating drilling operation for each bearing on crankcase. For example, a wall thickness around the second oil passage may vary from 5-10 mm. Also, an inner diameter of the second oil passage may vary from 9-11 mm, and diameter of the first oil passage and the third oil passage may vary from 4-6 mm. However, it is also within the scope of the invention to provide any dimensions of the passage for lubrication without otherwise deterring the intended function of lubrication as can be deduced from the description and corresponding drawings.
[0031] The dimensions of the first oil passage, the second oil passage, and the third oil passage (together referred as oil passage hereafter) are decided such that the proper oil pressure is maintained for the camshaft bearing lubrication. Further, the diameters of the oil passages are optimized considering the velocity and pressure required in oil passages. For example an oil pressure may be 3.5 bars and a velocity of the flow may be 1 m/s.
[0032] With the embodiments herein, an oil circuit having predetermined criteria could be designed for camshaft bearing lubrication for varying parameters and to carry out simulation to estimate the oil pressure conditions for the camshaft bearing lubrication. Further, CAE analysis could be performed to estimate a fatigue factor of safety in a region around the second oil passage. This results in the optimal design ensuring sufficient structural strength and rigidity and good oil flow and pressure characteristics in the aforementioned design. In an embodiment, the embodiments herein could be used in similar compact applications for oil circuit designs.
[0033] The advantages provided by the embodiments herein includes, integrated oil gallery in camshaft for simplified design of the block in main bearing wall area, ensures efficient lubrication of the camshaft bearings, increases the ease of manufacture of cylinder block and engine assembly, and improves stiffness and rigidity of the camshaft.
[0034] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. ,CLAIMS:We claim,
1. A camshaft 100 for an engine, said engine having a cylinder head and an oil gallery thereon, said camshaft 100 comprising:
a shaft 102 having first end 102a and a second end 102b, said shaft 102 being rotatably journaled between a front journal 104 and a rear journal 106;
at least one first oil passage 108 defined in said rear journal 106 to receive oil from said oil gallery through at least one oil groove 120;
at least one second oil passage 110 extending internally between said front journal 104 and said rear journal 106, said second oil passage 110 is adapted to receive oil from said oil gallery through said rear journal 106; and
at least one third branched oil passage 112 extending radially from said second oil passage 110,
wherein,
said shaft 102 includes a plurality of longitudinally spaced cam portions 114 and journal portions 116 thereon;
said third branched oil passages 112 extends from said second oil passage 110 at each said journal portions 116.
2. The camshaft 100 as claimed in claim 1, wherein said second oil passage 110 is blocked at both said first end 102a and said second end 102b by at least one plug 118.
3. The camshaft 100 as claimed in claim 1, wherein said rear journal 106 includes at least four first oil passages 108 disposed radially from a central axis A to a rear journal bearing surface 106a defined away from said central axis A to receive oil from said oil gallery through said oil groove 120.
4. The camshaft 100 as claimed in claim 1, wherein said front journal 104 includes at least two third branched oil passages 112 disposed radially from said central axis A to a front journal bearing surface 104a defined away from said central axis A.
5. The camshaft 100 as claimed in claim 1, wherein said each journal portions 116 includes at least two third branched oil passages 112 disposed radially from said central axis A to a bearing surface 116a defined away from said central axis A.
6. The camshaft 100 as claimed in claim 1, wherein said third branched oil passages 112 are adapted to supply oil to said journal portions 116 of said shaft 102.