FUEL PUMP LUBRICATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

FIELD OF INVENTION

The present invention relates to the fields of lubrication system for an internal combustion engine of a motor vehicle, and more particularly to a lubricating system for improving the life of the fuel injection drive housed in the cam box by effectively lubricating the fuel pump cam, roller follower and tappet of the fuel pump.

BACKGROUND OF THE INVENTION

Fuel injection is normally utilized in the internal combustion engines to inject the required amount of fuel in a high pressure range into the combustion chamber and by this means improving the fuel consumption and increasing the engine performance. Normally the high pressure fuel injection system is applied for high speed diesel engines which usually adopt a common rail technology for various benefits such as improvements in engine performance and increase in fuel efficiency. The common rail fuel injection system is equipped with a common rail which accumulates a requisite amount of the high pressure fuel and a fuel pump that supplies the high pressure fuel to the common rail for high pressure fuel injection into each cylinders of the internal combustion engine.

The fuel pump pressurizes and delivers a high pressure fuel into the common rail unit for injecting into the combustion chamber of the engine. In response to the engine running conditions and various preset parameters, the engine control unit signals the fuel injectors to supply the high pressure fuel to the combustion chamber of each cylinder in the internal combustion engine for a predetermined period.

The fuel pump for an internal combustion is generally driven by a fuel pump cam and operated by a tappet in the engine cylinder head. The fuel pump includes a set of components which are mechanically connected and drives to generate a high pressure fuel to the common rail for injection into the engine cylinders. This high pressure fuel injection system directs the fuel pump to rotate in higher speeds to deliver high pressure fuel. Having mechanically connected and rotates in higher speeds, the fuel injection drive components often show wear and tear of parts due to the friction and heat generated during the operation of the fuel pump. This excessive operational friction and heat generation can impede the fuel injector drive performance and the life of the fuel pump.

In order to reduce the excessive amount of heat generated and to decrease the unwanted level of friction in the drive components during the operation of the fuel pump, the fuel injection drive components has to be lubricated to a requisite level, and thereby achieving improved fuel efficiency and increase in the engine performance.

The conventional lubrication system having external pipe routings for lubricating fuel pump for an internal combustion engine is described, in accordance to a prior art. Normally a lubricating oil pump is provided with the engine to pressurise the lubricating oil and force the lubricating oil to the required parts for lubrication in the internal combustion engine. The conventional arrangement of lubrication system for a fuel pump includes a main oil gallery and having external pipes provided for the supply of the lubrication oil to the engine cylinder head. The lubricating oil received in the cylinder head is forced to flow towards the fuel injection drive components with the use of external pipes placed in the engine cylinder head. This external pipe routings allows the lubricating oil to flow to the cylinder head cam shaft assembly and continue to lubricate the fuel injection drive components.

However the conventional arrangement of externally piped lubrication for the fuel pump suffers to provide a requisite level of lubrication. Further the arrangement of external pipe routing for the flow of lubricating oil obstruct the flow of lubricating oil in required pressure to lubricate the fuel pump and its components. Due to this deprived lubrication to the fuel pump, the generation of high pressure fuel in the fuel pump gets affected.

This poor lubrication of fuel pump leads to higher wear and tear of the fuel pump components and affects the fuel pump life and engine performance. With respect to the conventional lubrication system for fuel injection drive, it is necessary to provide an improved lubrication system to increase the lubrication characteristics for an internal combustion engine and effectively lubricating the fuel pump components. Therefore, it is desirable to provide an improved system developed for lubricating the fuel pump drive which is capable to address and overcome the above disadvantages of conventional lubrication systems.

SUMMARY OF INVENTION

An object of the present invention is to provide an improved lubrication system for a fuel pump drive for an internal combustion engine and effectively lubricate the fuel pump components.

Another object of the present invention is to efficiently improve the lubrication characteristics of the fuel pump drive for an internal combustion engine and to increase the life of the fuel pump drive.

Further object of the present invention is to provide an improved lubrication system for fuel pump drive which is simple in construction and eliminates the necessity of external pipe routings for lubrication.

The present invention, which achieves the objectives, relates to a fuel injection drive of an internal combustion engine includes a fuel injection pump housed in the cam box housing mounted with the engine cylinder head. The fuel pump is driven by a pump operating cam and a tappet and a roller follower which is actuated by the engine camshaft. The fuel pump operating cam is a tri lobe type construction by which the fuel pump delivers three impingement for one rotation of the cam shaft.

The Cam shaft being supported at the four journals of Cylinder head and by cylindrical roller bearing located in Cam box housing at rear end. The Cam shaft bearing caps clamped over the Cylinder head holds the Cam shaft firmly. The rear cam bearing cap which has machined oil passage to serve as an Oil outlet. This arrangement allows the flow of lubricating oil to the fuel pump tri lobe type cam and roller follower through the slots provided in the cam shaft.

In operation the lubricating oil is forced from main oil gallery to pass towards the cylinder head journal through the internally machined holes. The lubricating oil made available at the cylinder head journal is passed on to the cam shaft bearing cap through the internally machined cam shaft slots and lubricate the fuel pump cam and roller follower. The lubrication takes place such that the flow of oil at the cam and roller follower is continue to splash over the surfaces of the tappet and tappet bore of fuel injection pump, thus effectively lubricating the fuel pump components.

The cam lobes are dip lubricated when the cam lobes rotates down to the oil reservoir part of the cam box housing. This combined effect of splashing of oil and dipping of cam lobes at the com box housing oil reservoir, enables to provide a persisting thin film of lubrication on the fuel pump components and effectively lubricating the fuel pump components and improves the life of the fuel injection drive. The lubrication system allows metering for adequate quantity of oil flow towards lubrication of fuel pump cam and roller follower in the fuel injection system, thus effectively improving the lubrication characteristics of the fuel pump drive for the internal combustion engine.

The lubricating oil flows through the internally machined holes and lubricate all required parts of the internal combustion including the fuel injection drive thus eliminating the necessity of external pipe routings for the lubrication and making the lubrication system simple in construction and cost effective.
Further the arrangement of internally machined slots in the cam shaft and cam shaft bearing cap allows minimizing the length of lubricating oil travel line and thereby improving the flow of lubricating oil in required pressure to lubricate the fuel pump and its components.

The present invention allows providing an improved lubrication to the fuel pump and enables the fuel pump to deliver high pressure fuel to the fuel injectors and thereby increasing the fuel efficiency and engine performance.

BRIEF DESCRIPTION OF DRAWINGS

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.

FIG. 1 illustrates a schematic arrangement of a lubricating system for fuel injection drive and its components lubrication through internally machined holes in cam shaft and cam shaft bearing cap, with an exemplary embodiment of the present invention.

FIG. 2 shows an illustration of cam box housing having cam shaft bearing, bearing cap and internally machined cam shaft slots, in accordance with an exemplary embodiment of the present invention.

FIG. 3 shows a schematic arrangement of fuel pump and drive components assembled in the cam box housing of an internal combustion engine, in accordance with an exemplary embodiment of the present invention.

FIG. 4 shows an illustration of oil flow from the main oil gallery to the cylinder head journal and continuing to cam shaft bearing cap and cam shaft slots for lubricating the fuel pump, in accordance to the present invention.

FIG. 5 shows an illustration of splashing of oil from bearing cap oil hole to fuel pump cam and other pump components, in accordance with an exemplary embodiment of the present invention.

FIG. 6 shows an illustration of Dip lubrication of fuel pump cam and pump components, in accordance with an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

The fuel injectors and common rail fuel injection system are provided in the internal combustion engines in order to achieve an improved level of combustion characteristics and engine performance. The fuel pump works at higher speeds and large running cycles, and the friction and heat developed in the fuel pump and its components needs to be lubricated to improve the life and performance of the fuel injection drive. The present invention achieves improving the life of the fuel injection drive and fuel pump components.

According to the present invention, the lubrication system for the fuel injection drive is housed outside the cylinder head along with the cam box of the internal combustion engine to achieve various benefits in terms of improved lubrication for the fuel injection drive. The lubricating oil pressurized from a lubricating oil pump passes through the main oil gallery, and it is supplied to the fuel injection drive in a high pressure to lubricate the fuel pump drive components.

FIG. 1 illustrates a schematic arrangement of a lubricating system for fuel injection drive and its components lubrication through internally machined holes in cam shaft and cam shaft bearing cap, with an exemplary embodiment of the present invention. The fuel injection drive of an internal combustion engine includes a fuel pump 1 housed in the cam box housing 12 integrated with the engine cylinder head 9. The fuel pump 1 includes a tappet 5 and a roller follower 4 which is actuated by the fuel pump cam of engine camshaft 6. The fuel pump operating cam 2 is a tri lobe type construction by which the fuel pump 1 delivers three impingement for one rotation of the cam shaft 6.

The fuel pump operating cam lobes are provided with direct contact to the cam shaft 6 of the engine to build high pressure in the fuel pump 1. A delivery pressure of about 1450 bar is generated with this design of cam lobe assisted fuel pump. The fuel pump 1 supplies the pressurized fuel to the common rail unit and the high pressure fuel is injected into the combustion chamber of the internal combustion engine.

FIG. 2 shows an illustration of cam box housing having cam shaft bearing, bearing cap and internally machined cam shaft slots, in accordance to the present invention. A roller type cam shaft bearing 7 for supporting the cam shaft 6 is placed at one end of the cam box housing 12 and a cam shaft bearing cap 8
with an internally machined oil passage 10 is provided to serve as an oil outlet. The rotation of the cam shaft 6 enables the valve actuation which intends for opening and closing of the inlet and exhaust of the combustion chamber in the internal combustion engine. The valve timings are accorded with respect to the cam arrangement to open and close the valves of the engine.

The cam shaft 6 is supported by four cylinder head journals and the roller bearing 7 at one end of the cam box housing 12. The cam shaft 6 actuates the fuel pump cam 2 to pressurize the fuel available to the fuel pump 1 and pass on through the common rail system to inject the high pressure fuel into the combustion chamber of the internal combustion engine. This arrangement allows the flow of lubricating oil available at the cam shaft bearing cap 8 to the fuel pump tri lobe type cam 2 and roller follower 4 through the slots 11 provided in the cam shaft 6.

FIG. 3 shows a schematic arrangement of fuel pump 1 and drive components assembled in the cam box housing of an internal combustion engine, in accordance to the present invention. The pump 1 for fuel injection is housed in the cambox 12 of the internal combustion engine, such that the fuel injection drive and the lubrication system are housed outside the cylinder head 9 of the internal combustion engine. A journal surface of camshaft 6 is formed on the cylinder head 9 to support the assembly of the camshaft bearing 7 and an oil hole 11 is provided in the camshaft 6 to supply the lubricating oil received in the journal surface. The cambox 12 accommodate the fuel pump 1 and the related components to achieve the lubrication system for the fuel injection drive. The fuel pump 1 and related component are assembled in the cam box 12, such that the operating cam 2 of the fuel pump 1 having direct contact with the camshaft 6 transfers the cam shaft drive force through the tappet 5 and roller follower 4 to pressurize the fuel available in the fuel pump 1.

The lubrication of the fuel pump operating cam 2, tappet 5 and roller follower 4 is obtained by the high pressure lubricating oil from the main oil gallery through the cam shaft assembly.

FIG. 4 shows an illustration of oil flow from the main oil gallery to the cylinder head journal and the lubricating oil continuing to the cam shaft bearing cap and the cam shaft slots for lubricating the fuel pump, in accordance to the present invention. In operation the lubricating oil is forced from oil pump to the main oil gallery and continues to pass in an oil flow path 13 towards the cylinder head journal through the internally machined holes 10. The oil made available at the cylinder head journal is passed on to the cam shaft bearing cap 8 through the internally machined cam shaft slots 11 and lubricates the fuel pump operating cam 2 and the roller follower 4. The lubrication for fuel pump takes place such that the flow of oil at the fuel pump cam 2 and the roller follower 4 is continue to splash over the surfaces of the tappet 5 and tappet bore of fuel pump 1, and thereby effectively lubricating the fuel pump components.

In operation, with respect to the command from the engine control unit ECU, the high pressure fuel available in the common rail is injected and supplied through the fuel injection valves to each cylinder of the internal combustion engine. The fuel pump lubrication systems driven by the operating cam in accordance to the present reduces the friction and wears of the fuel pump and drive components, and this reduced friction and wear of the fuel pump allows for improved performance of the fuel pump and increased life of the fuel injection drive elements.

FIG. 5 shows an illustration of splashing of oil from bearing cap oil hole to fuel pump cam and other pump components, in accordance to the present invention. The jet of lubricating oil which hits the fuel pump operating cam 2 and its components such as roller follower 4 is again getting splashed over the surfaces of the tappet 5 and the related elements of the fuel injection pump 1. This jet type lubrication is used to meter the adequate quantity of oil for lubricating the operating cam 2 and roller follower 4. This combined system provides a persisting thin film of lubrication on the camshaft 6, fuel pump operating cam 2, roller follower 4 and tappet 5 of the fuel pump 1 in the fuel injection drive, thus achieving effective lubricating for the fuel pump drive and its components.

FIG. 6 shows an illustration of dip lubrication of fuel pump cam 2 and pump components, in accordance to the present invention. The cam lobes 3 are dip lubricated when the cam lobes 3 rotates down to the oil reservoir part 14 of the cam box housing 12. This combined effect of splashing of oil and dipping of cam lobes 3 at the com box housing oil reservoir, enables to provide a thin film of lubrication on the fuel pump elements and thereby effectively lubricating the fuel pump 1 and improves the life of the fuel injection drive in the internal combustion engine.

The lubrication system of present invention allows for metering of adequate quantity of oil flow towards lubrication of fuel pump cam and roller follower in the fuel injection system, thus effectively improving the lubrication characteristics of the fuel pump drive for the internal combustion engine.

The lubricating oil flows through the internally machined holes and lubricate all required parts of the internal combustion including the fuel injection drive thus eliminating the necessity of external pipe routings for the lubrication and making the lubrication system simple in construction and cost effective.
The arrangement of fuel pump cam having direct contact with camshaft to pressurize the fuel available in the fuel pump makes the fuel pump to pressurize the fuel and supply high pressure fuel to the common rail unit for injecting into the combustion chamber, and thereby achieving benefits in terms of enhanced combustion characteristics and meeting emission norms.

The present invention allows providing an improved lubrication to the fuel pump and enables the fuel pump to deliver high pressure fuel to the fuel injectors and thereby increasing the fuel efficiency and engine performance. According to the present invention, the friction generated between the tappet and the roller follower is reduced in the fuel pump, so the abrasion of the tappet is prevented and thereby providing an improved lubrication system and increasing the life of the fuel injection pump.

Further the arrangement of internally machined slots in the cam shaft and cam shaft bearing cap allows minimizing the length of lubricating oil travel line and thereby improving the flow of lubricating oil in required pressure to lubricate the fuel pump and its components.

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for 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 the equivalents thereof.

Part numbers:
Fuel pump 1 Fuel pump operating cam 2
Cam lobe 3 Roller follower 4 Tappet 5 Camshaft 6 Cam shaft bearing 7 Cam shaft bearing cap 8 Cylinder head 9 Internally machined holes for bearing and cap 10 Cam shaft slots 11 Cambox 12
Cylinder head journals 13 Flow path of oil 13 Oil reservoir part 14

WE CLAIM :

1. A lubrication system for a fuel injection drive of an internal combustion engine, comprising,

a fuel pump driven by a camshaft is housed in a cambox housing, and includes a pump operating cam, a tappet and a roller follower, wherein said cam is a tri lobe cam and delivers three impingement for one cam shaft rotation;

a cam shaft bearing supporting said cam shaft is placed at one end of said cam box housing and said bearing cap is provided with internally machined oil holes for lubricating said fuel pump;

wherein the lubricating oil available at cylinder head journal is passed on to said cam shaft bearing cap through internally machined cam shaft slots and lubricates said fuel pump cam and said roller follower,
and continues to splash over the surfaces of said tappet and tappet bore of fuel injection pump.

2. A lubrication system for a fuel injection drive as claimed in claim 1, wherein said fuel pump cam is integrated with said engine cam shaft to actuate said roller follower.

3. A lubrication system for a fuel injection drive as claimed in claim 1, wherein the lubricating oil flows from main oil gallery to said cylinder head journal through said internally machined holes.

4. A lubrication system for a fuel injection drive as claimed in claim 1, wherein the lubricating oil flows from cylinder head journal to said cam shaft bearing cap through cam shaft slots.

5. A lubrication system for a fuel injection drive as claimed in claim 1, wherein said cam lobes are dip lubricated when the cam lobes rotates down to the oil reservoir part of said cam box housing.

6. A lubrication system for a fuel injection drive as claimed in claim 1, wherein the combined effect of splashing of oil and dipping of cam lobes at the com box housing oil reservoir, provides a persisting thin film of lubrication on the fuel pump components.

7. A lubrication system for a fuel injection drive as claimed in claim 1, wherein said cam shaft bearing is a roller type bearing.

8. A lubrication system for a fuel injection drive as claimed in claim 1, wherein said cam shaft is supported by four cylinder head journals and one roller bearing at one end of said cam box housing.

9. A lubrication system for a fuel injection drive as claimed in claim 1, wherein the lubrication can be metered for adequate quantity of oil flow for lubricating of said fuel pump cam and roller follower in the fuel injection drive.