FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)
"A LUBRICATION SYSTEM IN A CAMSHAFT BEARING OF AN INTERNAL
COMBUSTION"
MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY,
R&D CENTER, AUTOMOTIVE SECTOR,
89, M.I.D.C, SATPUR,
NASHIK - 422 007,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION DESCRIBES THE NATURE OF THE INVENTION AND MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION:-
The present invention is related to camshaft bearing lubrication system of an internal combustion engine. More particularly, the present invention is related to single or double overhead camshaft bearing lubrication system wherein lubrication oil is retained in the pockets or grooves provided therein to reduce starting friction between camshaft bearings and camshaft.
BACKGROUND OF THE PRESENT INVENTION:-
In today's engine technology, the overhead camshaft used for operating the valve is well known application in the internal combustion engine. Reduction of CO2, in turn friction reduction is necessary with consideration of government legislations. Effective lubrication system plays vital role in engine to reduce the friction generated by movable or rotating parts. To reduce the friction; optimum size of bearing, oil film thickness and less oil aeration time to bearing are necessary factors.
In an engine with overhead camshaft, due to upward spring force, camshaft always touches in the upper half portion of the bearing. So, lubricating oil supply time; at the contact point of camshaft and cylinder head cover is larger when engine started and generated oil film of lubrication not effective in case of every start and also engine idling condition.
In a prior art lubrication system (US00RE35382E), oil gateway opens from upper side of the bearing. But this system may leads to increase the oil reaching timing or oil aeration time.
Patent No. US4258673 discloses cam lubrication wherein oil groove has been provided on a camshaft itself rather than the cam bearing for lubrication. Due to the lubricating oil pocket provided on the camshaft, location of oil pocket will not

be same at every engine start and stop condition. In actual case with available clearances in between these two mating parts will retain or not retain oil in the pocket. That is the reason that at each start positively there not be oil film and which create friction.
Patent No. US6237719 describes lubricating oil discharge system wherein oil reservoir are provided on the lower half portion of the bearing with oil line opening in the same groove with discharge port. In overhead camshaft due to upward spring force action, camshaft touches to bearing at the upper portion only, while oil discharge port at lower portion will not help to maintain lubricating film.
Sliding bearing with small oil pockets claimed in Patent No. US6095690 are spread over entire plain bearing element. There is fear to fill these small pockets with soft bearing material. The plain bearing is in this claimed patent compromising main bearing and big end bearing of internal combustion engine.
Patent No. US6046430 educates on bearing designed with micropores in which the pore size and shape is controlled by means of laser beam profile and laser beam power. Such a small micropores may fill by foreign particles and bearing material itself. So it will score entire mating part and increase the friction.
OBJECTIVES OF THE PRESENT INVENTION:-
The main objective of the present invention is to provide camshaft bearing lubrication system.
Another objective of the present invention is to provide single or double overhead camshaft bearing lubrication system with pockets or grooves to retain the lubrication oil.

Another objective of the present invention is to reduce starting friction between camshaft bearings and camshaft by providing unique lubrication system.
The main objective of the present invention is to provide camshaft bearing lubrication system wherein minimum oil film thickness at any start and operating condition of the engine is maintained.
DESCRIPTION OF THE FIGURES:-
Detailed description of the present invention can be understood with reference of the following figures wherein,
Figure 1 is a detailed view of the oil pocket or oil groove on the cam shaft bearing in accordance with the present invention.
Figure 2 is sectional view detailed with location of oil pocket and camshaft position taken for explanation.
Figure 3 is sectional view detailed with the valve train component for explanation of forces coming from valve to camshaft.
Figure 4 is the load distribution diagram of camshaft which gives information regarding location of bearing area and load area.
Figures 5a, 5b, 5c and 5d are the possible bearing arrangement with invented oil pockets or oil grooves in accordance with the present invention.

Accordingly invention provides a lubrication system in a camshaft bearing of an Internal combustion comprising of cam shaft , facing upward force as herein described, supported in the bearing block consisting of lower half formed in the engine body portion and an upper half formed in the cylinder head cover; the improvement is that an oil pocket or oil groove provided in the upper half of the camshaft bearing
DETAILED DESCRIPTION OF THE PRESENT INVENTION:-
According to the present invention, a camshaft bearing lubrication system comprises oil pocket or oil groove provided in the upper half of the camshaft bearing which is made in the cylinder head cover. Reduction in the metal to bearing contact area is greatly help to reduce the friction. Pocket or groove is made by casting, machining or by chemical process. In an engine, overhead camshaft always touches the upper portion of the bearing, and covers the bearing portion of pocket due to initial spring force. With this invented construction, oil remains always available in the oil pocket which will be available to maintain the oil film required at every start.
In an engine operating conditions where the discharge pressure of oil has not yet to be sufficient when engine started; oil reserved in the oil pocket may help for creating the lubrication film and avoid the metal to metal direct contact. Power lost in friction is reduced by 10% to 12% with oil pocket bearing rather than the without oil pocket bearing in this case. Power reduction may be varying with the bearing size.
Size and Location of the oil pocket or groove position are depends upon the contact point location of minimum oil film thickness area with respect to bearing diameter and bearing length. Width of the oil pocket is 0.2 to 0.4 times of length of the bearing and arc angle is 2.5 to 3 times the calculated angle between the

vertical bearing axis and minimum oil film thickness point. Pocket depth shape will be disc key type with maximum depth same as a pocket width.
Referring to Fig. 1, oil pockets for lubrication are shown in upper half of the bearing portion. Referring to figure 2, location of the oil pocket '9' on double overhead camshaft engine can be seen. The upper bearing portion '5' and '7' is a part of cylinder head cover '1' assembled by means of fastener '4' with lower bearing portion '6' and '8' which are integrated with cylinder head '2'. Oil is supplied to the camshaft bearing through oil gallery '3'.
Referring to figure 3, the force coming from intake valve '10' and initial as well as operating force coming from spring '12' can be seen. These forces are transmitted to intake camshaft '13' via roller finger follower '15'. Similarly, force coming from the exhaust valve '11' and force from spring '12' transmitted to the exhaust camshaft '14' via roller finger follower '15'. With upward forces, journals of intake camshaft '13' and exhaust camshaft '14' are always contact with top portion of bearing [5' and '7' Referring to figure 4, 'A', 'C and 'E' are the bearing portion and 'B' and 'D' are the locations where the force at the time of closing and opening the valve is acted from can lobes of intake and exhaust camshaft '13' and '14'. The oil pocket '9' as shown in Fig.1 is provided at the bearing portion 'A', 'C and 'E' of the camshaft '13' and '14' on upper side bearing portion '5' and 7'.
This lubrication methodology with oil groove or oil pocket can be made by casting, etching or may be machining. The size and location of the oil pocket or groove position depends upon the contact point location of minimum oil film thickness area with respect to bearing diameter and bearing length. Width of the oil pocket is 0.2 to 0.4 times of length of the bearing and arc angle is 2.5 to 3 times the calculated angle between the vertical bearing axis and minimum oil film thickness point. Pocket depth shape will be disc key type with maximum pocket depth will be 0.1 to 0.15 times the bearing diameter.

The oil groove or oil pocket may be made on individual upper bearing portion, integrated bearing portion for intake and exhaust camshaft in case of DOHC engine, ladder plate consist of all upper bearing portion and cylinder head cover with all upper bearing portion as shown in Figures 5a, 5b, 5c and 5d respectively.
The number of oil pockets or grooves depends upon the bearing length and bearing load carrying capacity. This camshaft bearing lubrication system can be applicable for diesel, gasoline, CNG, LPG or gas engine, naturally aspirated and turbocharged, single and multi cylinder engine. It is also applicable gasoline direct injection engines and hybrids engines. The oil pockets can be made for aluminum alloy bearing cover as well.
The lubrication system of the present invention helps to reduce starting friction between camshaft bearings and camshaft and provides sufficient lubrication at the time of starting of the engine keeping camshaft always in contact with the upper half bearing because of the upward spring force.

WE CLAIM:-
1. A lubrication system in a camshaft bearing of an Internal combustion comprising of cam shaft , facing upward force as herein described, supported in the bearing block consisting of lower half formed in the engine body portion and an upper half formed in the cylinder head cover; the improvement is that an oil pocket or oil groove provided in the upper half of the camshaft bearing .
2. A lubrication system as claimed in claim 1 wherein the the said oil pocket/oil groove formed in the said cylinder head by casting or , machining or by chemical process.
3. A lubrication system as claimed in claims 1 and 2 wherein the width of the oil pocket is 0.2 to 0.4 times of length of the bearing and arc angle is 2.5 to 3 times the calculated angle between the vertical bearing axis and minimum oil film thickness point.
4. A lubrication system as claimed in the claims 1 to 3 wherein the said oil /oil groove having the pocket depth shape of disc key type with maximum pocket depth will be 0.1 to 0.15 times the bearing diameter.