The present invention relates to fuel-injection systems and more particularly, to an integrated fuel injection system having a fuel pump integrated directly into a cylinder head.

Background of the invention:

Fuel injection is a system for admitting fuel into an internal combustion engine. Modern fuel injection systems are designed specifically for the type of fuel being used. Some systems are designed for multiple grades of fuel.

Generally, in a conventional fuel injection pump (FIP) drive system, the FIP is driven by following means:
1. By a camshaft by mounting the FIP on a rear side of a cylinder head.
2. Directly by the camshaft by mounting the FIP on a cam cover.
3. The FIP is mounted on a crankcase and driven by a crankshaft with a separate chain drive.

A variety of injection systems existed in the prior art. For example, US patent no. US5839401A describes an internal combustion engine. A fuel injection pump (FIP) drive is designed for a double over head camshaft engine and an old ham coupling is used for the FIP drive. However, with the old ham coupling a driving mechanism for the FIP becomes complex.

Another US patent no. US6321724A discloses an engine with an integrated unit pump injector and a method of making the same. A fuel injection pump (FIP) drive is designed for a mechanical injection pump for which a complex engine governing system is required where fuel pressures are less. A shaft driving the FIP is mounted in a crankcase. However, in this patent, the injector and the pump need to be installed as a subassembly in the cylinder head and the crankcase simultaneously. A nozzle and a pump bore have to be aligned parallel. Also, a mechanical injection leak testing, fuel volume check and adjusting shim heights is required.

Reference may be made to US patent no. US5419298A disclosing an internal combustion engine. A fuel injection pump (FIP) and a drive shaft are mounted on a crankcase. The FIP drive is designed for mechanical fuel injection wherein a unit pump is required for each cylinder of the engine and fuel supply lines have to go through the crankcase. The drive shaft is driven by a separate gear which is prone to radiate lot of noise and leakage checks are required in fuel lines thereby making the system more complex and costly.

Another US patent no. 4168689A discloses a fuel injector internal passage and filler. A fuel injection pump (FIP) drive is designed for mechanical fuel injection wherein a unit pump is required for each cylinder of the engine and fuel supply lines have to go through the cylinder head. However, lot of linkages is involved in the FIP drive and a fuel supply system and fuel manifold are required for the FIP.

Drawbacks of the prior art:

1. If the camshaft is driving the FIP in addition to intake and exhaust valve actuation, the chain loads will be very high.
2. If the base engine camshaft which is actuating the valves is also used for driving the FIP then that shaft has to be made in steel to take care of higher contact stresses coming from the FIP loads. This makes the shaft costlier as longer shaft has to be used and all the lobes have to be induction hardened including FIP lobe.

Accordingly, there is a need to provide a fuel injection system having a fuel pump integrated directly into a cylinder head that overcomes the above mentioned drawbacks of the prior art.

Objects of the invention:

An object of the present invention is to provide a fuel injection pump drive for a common rail fuel injection system.

Another object of the present invention is to integrate a fuel injection pump directly into a cylinder head.

Summary of the invention:

Accordingly, the present invention provides an integrated fuel injection system. The fuel injection system comprises a fuel injection pump (hereinafter “the FIP”), a tappet, a lock pin, a housing, a thrust plate, a drive shaft, a dowel housing and a sprocket.

The dowel housing mounts the housing on a cylinder head. The housing positions a tappet, a lock pin and an internal oil gallery for the tappet therein. The lock pin avoids rotation of the tappet inside a bore of the cylinder head. The FIP is mounted on the tappet. The housing, the FIP and the drive shaft are accommodated on a front side of the cylinder head. The FIP includes a plurality of flanges attached thereto and a mounting plate positioned thereon. The drive shaft is supported in the cylinder head by two bearings for driving the FIP by taking drive from a camshaft via a chain. The chain is supported on an arm and the arm is supported on the sprocket. The drive shaft includes an internal oil gallery for lubrication of bearings. The sprocket is clamped to the drive shaft using a nut. The thrust plate is mounted on the drive shaft and fixed to the cylinder head using screws. The thrust plate includes a plurality of holes configured thereon. The plurality of holes of the thrust plate facilitates oil drain from the integrated fuel injection system into a crankcase.

Brief description of the drawings:

Figure 1 shows an assembly view of an integrated fuel injection system, in accordance with the present invention;

Figure 2 shows an exploded view of the integrated fuel injection system of figure 1;

Figure 3 shows a sectional view of the integrated fuel injection system of figure 1;

Figure 4 shows another sectional view of the integrated fuel injection system of figure 1;

Figures 5a and 5b show one more sectional view of the integrated fuel injection system of figure 1;

Figures 6a and 6b show another sectional view of the integrated fuel injection system of figure 1; and

Figure 7 shows a fuel injection pump drive shaft of the integrated fuel injection system of figure 1.

Detailed description of the invention:

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides a fuel injection system having a fuel pump integrated directly into a cylinder head. The fuel injection system is designed for a common rail fuel injection system and utilizes only one fuel pump for a complete engine to reduce the length of a drive shaft. The drive shaft is driven by a same chain that drives a camshaft and hence, no separate mechanism is required for driving the drive shaft thereby reducing cost.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring to figures 1-7, an integrated fuel injection system (200) (hereinafter “the system (200)”) for a vehicle (not shown) in accordance with the present invention is shown. The system (200) comprises a fuel injection pump (20) (hereinafter “the FIP (20)”), a tappet (30), a lock pin (40), a housing (50), a thrust plate (60), a drive shaft (70), a dowel housing (80) and a sprocket (90).

The FIP (20), the housing (50) and the drive shaft (70) are accommodated on a front side (not numbered) of a cylinder head (250) of an engine (not shown) of the vehicle. The dowel housing (80) mounts the housing (50) on the cylinder head (250). The housing (50) is used to house the tappet (30), the lock pin (40) and an internal oil gallery (not numbered) for the tappet (30) and also, to mount the FIP (20). The tappet (30) is used to transfer motion of a cam lobe/FIP lobe (290) to a plunger (not shown). The cam lobe (290) drives the FIP (20). The oil flow direction in the cam lobe (290) is shown by arrows in figure 7. The tappet (30) is lubricated to reduce friction caused by reciprocation thereof inside the housing (50). The lock pin (40) avoids rotation of the tappet (30) in a bore (not shown) of the cylinder head (250).

The FIP (20) is mounted on the tappet (30). The FIP (20) pumps the fuel at high pressure to a common rail (not shown). The FIP (20) includes a plurality of flanges (5) attached thereto and a mounting plate (18) positioned thereon. The mounting plate (18) includes a plurality of holes (not numbered) configured thereon. The plurality of holes is adapted to receive a plurality of studs (10). The plurality of studs (10) passes through the plurality of holes and gets fixed into the plurality of flanges (5) positioned on the FIP (20). The plurality of studs (10) facilitates fixing of the mounting plate (18) on the FIP (20) using a plurality of nuts (14).

The drive shaft (70) is supported in the cylinder head (250) by two bearings that is a front bearing (not numbered) and a rear bearing (not numbered). The drive shaft (70) includes an internal oil gallery (not numbered) for lubricating the front and rear bearings. The drive shaft (70) is driven by a chain (260). The drive shaft (70) drives the FIP (20) by taking drive from a camshaft (not shown) via the chain (260). In an embodiment, speed ratio of the drive shaft (70) with respect to the camshaft is 1:1. The chain (260) is supported on an arm (280). The arm (280) includes a pair of fixed guides (265) and movable guides (270). The arm (280) is supported on the sprocket (90). The sprocket (90) is clamped to the drive shaft (70) using a nut (75). The sprocket (90) facilitates driving of the drive shaft (70) by the chain (260).

The thrust plate (60) is mounted on the drive shaft (70) and fixed to the cylinder head (250) using screws (65). The thrust plate (60) is adapted to receive a thrust load coming from the drive shaft (70). The thrust plate (60) includes a plurality of holes (not numbered) configured thereon. The plurality of holes facilitates oil drain from the system (200) into a crankcase (not shown) thereby avoiding additional pipes, leakage joints and reduces cost.

Advantages of the invention:

1. The system (200) is designed for a single over head camshaft and the FIP (20) is directly driven by the chain (260).
2. The system (200) allows use of the cost effective chain (260) having less fatigue strength. Also, the chain loads are less as the FIP drive and cam shaft drive are separated.
3. The height of the housing (50) is variable as per use of FIP’s of different heights.
4. The drive shaft (70) is driven by the same chain (260) that is driving the camshaft and hence, no separate mechanism is required for driving the drive shaft (70) thereby reducing cost.
5. The system (200) is designed for the common rail fuel injection system which is technically advanced and there is only one FIP (20) for the complete engine, so the drive shaft (70) length is short and the housing (50) required for the FIP (20) is small. Also, there are no fuel lines running inside the crankcase and the cylinder head (250).
6. As the system (200) is designed for the common rail injection system, no leakage and volume checks for fuel are required. In the present invention, pump and injector assembly can be done independent of each other.
7. Oil supply to the tappet (30) and camshaft bearings is provided via the internal passages and oil drain from the system (200) is provided via the plurality of holes present in the thrust plate (60) into the crankcase thereby avoiding additional pipes, leakage joints and reduces cost.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

,CLAIMS:We Claim:

1. An integrated fuel injection system (200) comprising:
a dowel housing (80) being capable of mounting a housing (50) on a cylinder head (250), the housing (50) positioning a tappet (30), a lock pin (40) and an internal oil gallery for the tappet (30) therein, the lock pin (40) being capable of avoiding rotation of the tappet (30) inside a bore of the cylinder head (250);
a fuel injection pump (20) mounted on the tappet (30), the fuel injection pump (20) having a plurality of flanges (5) attached thereto and a mounting plate (18) positioned thereon;
a drive shaft (70) supported in the cylinder head (250) by two bearings for driving the fuel injection pump (20) by taking drive from a camshaft via a chain (260), the drive shaft (70) having an internal oil gallery for lubrication of the bearings;
a sprocket (90) clamped to the drive shaft (70) using a nut (75); and
a thrust plate (60) mounted on the drive shaft (70) and fixed to the cylinder head (250) using screws (65), the thrust plate (60) having a plurality of holes configured thereon,
wherein, the plurality of holes of the thrust plate (60) facilitates oil drain from the integrated fuel injection system (200) into a crankcase.

2. The integrated fuel injection system (200) as claimed in claim 1, wherein the housing (50), the fuel injection pump (20) and the drive shaft (70) are accommodated on a front side of the cylinder head (250).

3. The integrated fuel injection system (200) as claimed in claim 1, wherein the chain (260) is supported on an arm (280) and the arm (280) is supported on the sprocket (90).