Innovative Modification of Crankshaft with a Single Drill Oil Lubrication Gallery
1. TECHNICAL FIELD OF THE INVENTION
The invention relates to crankshaft used in internal combustion engine that translate reciprocating linear piston motion into rotation. Innovative modification has been carried out in the existing design of crankshaft for supply of lubricating oil to main bearing area of crankshaft and further to big end bearing area of the connecting rod via crank pin of crankshaft thus making it very cost effective and reinforced with further strengthen
The crankshaft converts the linear horizontal motion into rotating motion and has moving parts in the housing provided in crankcase. The relative movement of various metallic parts against each other generates considerable friction and heat buildup. Adequate lubrication of crankshaft is therefore essential that provides a continuous coat of the lubricating film around these components minimizing a direct contact between the two adjacent parts. Ensuring a continuous lubricating film in the crankshaft thus offers the following benefits
a) instant dissipation of heat
b) reduction in overall friction
c) reduction in wear and tear
d) enhanced life of the engine
e) cost savings on crankshaft
2. BACKGROUND AND THE PRIOR ART
In automotive application, two drillings are generally provided in the crankshaft for supply of lubricating oil to the main bearing area of crankshaft and a the connecting drill and from there onwards to crank pin area for supply of lubricating oil to the connecting rod big end area. In an internal combustion engine where a crankshaft converts the reciprocating motion to rotary motion through the forces generated due to combustion of air fuel mixture, it is important to give due

consideration to factors such as rigidity, compactness and functional requirement to make the system simple and cost effective.
The prior art is replete with several improvements in the crankshaft to overcome the problems of bearing shells and their overall life with heavier crankshaft generally at an increased cost of many drillings for lubrication. The plurality of drillings for lubrication attracts its own problems of more breakage of oil film thus negating the value of other advantages.
A US patent no. 7152569 describes oil supply systems disposed on opposite axial sides of the crankshaft journal each lubricating a corresponding one of a connecting rod journal. The oil supply systems are either axial or peripheral oil supply systems that do not require oil to be supplied to the crankshaft through the main crankcase bearings. A French patent application FR2896553A1 with equivalent patents under PCT and European systems and with Korea, Japan, China, Canada and Austria provides for hydrodynamic bearings lubricated by pressurized oil brought by orifices. Similarly two recent German patents under PCT WO2009049652 and WO2009049653 restore to pressurized oil supply device and an oil splash groove for lubricating oil supply concentrically arranged to reach main bearing pin, crank pin and the connecting rod bearing.
Multiple oil passages have been provided from bearing caps and bridges to crankshaft journal bearings at a laterally offset location rather than on the cylinder axis in US4656983. In US7152569 a crankshaft has a lubricating system in which passages for directing lubricating oil are precisely positioned to provide lubrication into the main bearing journals in areas removed from the main bearing load area and dispense such lubricating oil through plurality of outlets in the connecting rod journals.
US 6286466 discloses a lubricating system for an engine that has a vertically oriented crankshaft. One oil flow passage is defined through the crankcase chamber from a top end to a bottom end of the chamber. Oil is supplied through a main passage in the crankcase cover and a branch passage through each second crankshaft support members for lubricating the bearings. In the invention US6332443, a pair of oil grooves has been provided for supplying more lubricating oil to a connecting rod bearing as well as between the connecting rod and a crank pin.

US6684846 describes a method for distributing lubricant along a crankshaft deploying multiple oil grooves i) along the outer and inner edges of the flange, ii) between channel (extending from within the crank pin to the outer side) and the exterior portion of main segment. A patent held by Porsche AG (US6857411; oil ducts extending from the bearing journals to the crank pins. Two oil bores are provided in the respective bearing journals of the crankshaft for the lubricating oil supply to the connecting rod bearings adjoining on the left and right. The two oil bores interact with oil supply grooves provided in the main bearings for the lubricating oil supply.
Notwithstanding the innovative approaches brought about by various inventors as described above in the conventional design of most crankshafts employs at least two drilling bores, as shown in Figure 1, one for crankshaft main journal and the other for crank pin journal separately with persistent problem of breakage of oil film between various interfaces. This invention therefore addresses the problems of lubrication and the main drawbacks in the prior art with an objective of minimizing the chances of breakage of oil film in the crankshaft to result into the above benefits.
The drilling method described in this invention reduces the chances of oil film breakage at the main journal as compared to that provided by the prior art and thereby helps reducing the cost of machining as well as the need for extra reinforcement and strengthening of crankshaft itself. A better retention of oil film with considerable reduction in its breakage brings in corresponding reduction in metal to metal contacts. This helps in less wear and tear and in effectively increasing the bearing life as well as crankshaft life and bringing down the costs and the overall weight of the crankshaft.
3. OBJECT OF INVENTION
The main object of this invention is to develop a technically advanced crankshaft for a single or multiple cylinders internal combustion engines with a single oil drilling groove capable of supplying lubricating oil to the main bearing, crank pin and further to connecting rod big end bearing.
Another object of this invention is to make the crankshaft cost effective, compact and more rigid in its operation.

4. SUMMARY OF THE INVENTION
A method of determining the position for drilling a single oil lubrication gallery in the crankshaft has been described that is capable of forming the required oil film between crankcase main bearing housing and crankshaft journal and at the same time supplying oil to crankshaft journal to form a similar oil film between crankshaft crankpin journal and the main bearing big end of the connecting rod.
The required oil drilling axis is determinable by drawing a straight line in a conceptual two dimensional view of crankshaft journal and crank pin journal between point 'a' and point 'd' running straight from crankshaft journal to crank pin journal at point 'e' as shown in Figure 3. The point 'a' lies on the perimeter of crank shaft journal at an angle of 65° to 70° with the main journal vertical axis and the and the point 'd' is the middle point on the line b - c drawn between the points 'b' and 'c' where the main journal and the crank pin journal overlap each other.
Additionally, the rectangular area formed at the cross section of middle of main journal and crankpin journal overlap as shown in Figure 4 (Section F-F) needs to be kept with a dimension that is at least 110% of engine bore. A chamfer is added at both ends of the oil drilling to avoid sharp edges.
Following the methodology as explained above, this oil drilling needs to be done such that it shall pass through the centre of area of the common plane connecting crankshaft main journal and crankpin journal and joins the middle planes of main journal and crankpin journals as shown in the transverse view of the drill in section G-G of Figure 5.
5. STATEMENT OF INVENTION
A crankshaft is provided with main bearing and crankpin journals to convert reciprocating forces generated due to combustion of air fuel mixture into rotating forces. The crankshaft rotates in the crank case on main journal bearings and is connected to the piston through the connecting rod small end using piston pin and small end plain bearing. The big end of connecting rod connects to crankshaft crank journal with plain bearing.

Thus supply of lubricating engine oil from crankcase to crankshaft main journal plain bearing to crank journal and connecting rod big end plain bearing and piston pin connection at connecting rod small end is required. To accomplish this; a lubricating engine oil is supplied to form and maintain lubricating oil film around the metal parts to help avoid metal to metal contact between the two rotating parts as well as reducing the friction and dissipation of the generated heat.
This lubricating engine oil is supplied via crankcase oil gallery to main journal housing, from there to main and crank journal of crankshaft via a single oil drill per set of main and crank journal of crankshaft.
6. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING(S)
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
Figure 1 illustrates prior art of oil lubrication drillings in a conventional crankshaft
Figure 2 shows a perspective view of the complete crank shaft of a twin cylinder engine
Figure 3 illustrates the method of determining the direction of single lubrication gallery across various components in the crankcase
Figure 4 shows a sectional view of crankshaft journal vis-a-vis crank pin journal along with the position of bore of single oil lubrication drilling as claimed in this invention
Figure 5 shows a transverse view of the single drill for oil supply to crankshaft journal and crank pin journal as claimed in this invention
Figure 6 shows yet another transverse view of the single drill for oil supply to crankshaft journal and crank pin journal as claimed in this invention

Figure 7 shows a transverse view of twin single drills for oil supply to crankshaft journal and crank pin journal in each set as claimed in this invention
7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 shows the most commonly employed arrangement for lubrication of crankshaft main journal and crank pin journal bearing with at least two drilling bores. Figure 2 shows a detailed cross-sectional view of crankshaft assembly with internal combustion engine along with a layout of essential components viz., piston 1, piston ring 2, connecting rod 3, big end bearing upper 4, big end bearing lower 5, main bearing shell upper 6, main bearing shell lower 7 and crankshaft 8. The two main areas requiring continuous lubrication during operation and which are referred in this invention repeatedly are main bearing journal 25 and crank pin journal 35 shown in Figure 2. These two areas are beset with the persistent problem of breakage of oil film between various interfaces. This invention therefore addresses the problems of lubrication and the main drawbacks in the prior art with an objective of minimizing the chances of breakage of oil film in the crankshaft to result into a marked improvement in handling this situation and resulting into multiple benefits of cost reduction and operability.
Instead of the usual a minimum of two drillings as shown in Figure 1, a methodology is described herein to draw a single drill extending from the main bearing journal to the crank pin journal that provides the required lubrication more efficiently without breakage of oil film. Figure 3 provides a 2-dimensional view of the crankshaft from the front end with the periphery of crank pin journal, 35 partially overlapping that of the crankshaft main journal, 25. This helps in conceptualizing and determining the direction of such an axis for drawing this single crucial bore.
In the overlapping zone, a straight line is formed between point 'b' and point 'c' on which the peripheries of crankshaft journal, 25 and crank pin journal, 35 intersect each other. Point 'd' is the midpoint of line b - c. Point 'a' lies on the periphery of crankshaft journal, 25 where it forms an angle of 65° to 70 ° with its vertical axis. A straight line drawn between point 'a' and point 'd' and extending it to the other end of crank pin journal, 35 it intersects at point 'e' on its periphery.

Line a - e passing through the point 'd' is the line with its unique position and direction for drilling a single lubrication oil gallery that does away the need for multiple oil galleries on the crankshaft. A drilling of a singular oil lubrication gallery as described herein considerably reduces the incidents of oil film breakage at the main journal, 25 as compared to that provided by the prior art. A better retention of oil film with considerable reduction in its breakage brings in corresponding reduction in metal to metal contacts. Consequently, it leads to reduction in the cost of machining as well as the need for extra reinforcement and strengthening of crankshaft itself. This helps in less wear and tear and in effectively increasing the life of both the bearing and crankshaft and bringing down the costs and the overall weight of the crankshaft
In a preferred embodiment of the disclosed invention, for the singular oil lubrication drill as disclosed above, it is obligatory to maintain necessary dimensional requirements to perform the crankshaft successfully with this new invention. The rectangular area formed at the cross section of middle of the overlap between main journal, 25 and crankpin journal, 35 as shown in Figure 4 (Section F-F) should be kept with a dimension that is at least 110% of the engine bore.
Further in the preferred embodiment, the lubricating oil drill should be done in such a way that it shall pass through the centre of area of the common plane connecting crankshaft main journal, 25 and crankpin journal, 35 and joins the middle planes of main journal, 25 and crankpin journal, 35 as shown in the transverse view of the drill in section G-G of Figure 5. Further transverse views of the drill as an oil gallery is Figure 6 and 7. A chamfer is also recommended to be added at both ends of the oil drilling to avoid the sharp edges.
Example and Mode of Enablement
To validate industrial applicability of the disclosed invention, a proto type with the modifications as disclosed herein was built in-house and 500 hrs of durability tests carried out on an engine test bed with the following observations:
• Satisfactory performance tests carried out
• Wear analysis carried out for crankshaft, connecting rods and balancer bearings; the wear and tear of bearings remained well within acceptable limits
• No breakage of lubrication film observed during the test runs
• Satisfactory performance targets with respect to 'power' and 'torque' were noted

The novel and innovative design of the crank shaft described in this invention thus performs the following functions:
• Supply of lubricating engine oil from the main journal to crank pin journal in the crank shaft
• Provides a rigid design for the crank shaft
• Provides a highly cost effective crank shaft
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for the purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or equivalent thereof.

We claim -
1. A crankshaft for internal combustion engine with a single lubricating oil drill instead of usual
double lubricating drill for supplying of oil from main bearing journal to crank pin journal.
2. A crankshaft with geometric cross sections and modifications as described in this invention
with the axis of single oil lubricating drill connecting a point on the crankshaft main journal
forming an angle with its vertical axis between 60° -70° and a point on the crank pin journal in
such a way that the line will pass through the middle point of the common plane between them.
3. A single or multi-cylinder internal combustion engine fitted with crankshaft of the modified design as disclosed herein
4. A vehicle fitted with internal combustion engine with a crankshaft as embodied
5. The crank shaft substantially as herein described and illustrated in the figures of accompanying
drawings wherein it is employed in a single or multi-cylinder internal combustion engines of any
industrial application.