WO2002029238A1

WO2002029238A1 - High-pressure common fuel rail system for internal combustion engine

Info

Publication number: WO2002029238A1
Application number: PCT/US2001/042361
Authority: WO
Inventors: Samuel Pearlman
Original assignee: Detroit Diesel Corporation
Priority date: 2000-10-03
Filing date: 2001-09-27
Publication date: 2002-04-11
Also published as: AU2001296927A1

Abstract

The system includes at least one fuel injector (70) secured by the cylinder head (14) for metering fuel to at least one combustion chamber (22). A common fuel rail (26) is positioned within a fuel rail bore (24) within the cylinder head (14) and at least one anchoring screw (86) is positioned within an anchoring screw bore (84) within the cylinder head (14).

Description

HIGH-PRESSURE COMMON FUEL RAIL SYSTEM FOR INTERNAL COMBUSTION ENGINE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to high-pressure common rail fuel injection systems for internal combustion engines and more specifically to a system having a common fuel rail in direct contact with at least one fuel injector to communicate fuel from the former to the latter.

2. Background Art

Existing common rail fuel injection systems typically include a common fuel rail, a fuel pump to force fuel under high pressure into the common fuel rail, a plurality of fuel injectors each connected to the common fuel rail to receive fuel at a common pressure, and a control system to control the operation of the fuel injectors and to maintain fuel rail pressure within prescribed limits.

The existing common rail fuel injection systems also include fuel pipes for communicating high-pressure fuel between the common fuel rail and the plurality of fuel injectors. These fuel pipes require an additional number of connections, which increases in the number of potential leak sites. The fuel pipes are expensive and time consuming to manufacture, assemble and service; and various fuel pipe bends and additional connections promote fuel flow turbulence. Additionally, fuel pipes are often exposed to vibration and potentially damaging impacts, which can lead to fuel leaks. SUMMARY OF THE INVENTION

In accordance with the present invention, provided is a high-pressure fuel rail system for use with an internal combustion engine having a cylinder head, at least one cylinder and at least one combustion chamber. The fuel rail system includes at least one fuel injector connected to the cylinder head for metering fuel into the at least one combustion chamber. The at least one fuel injector has therein an injector inlet to receive pressurized fuel.

In a first embodiment of the present invention, a first fuel rail has therein at least one rail inlet to receive pressurized fuel, has therein a first internal rail cavity to store pressurized fuel input tlirough the at least one rail inlet, has therein a rail outlet, and has therein at least one rail output port. The at least one rail output port is disposed at the end of a hollow projection that is integral with and that extends from the first fuel rail and communicates through the hollow projection with the first internal rail cavity.

The cylinder head has a rail bore extending horizontally therewithin.

The first fuel rail extends within the rail bore and is disposed so that the at least one rail output port is juxtaposed with the injector inlet of the at least one fuel injector. At least one rail securing member, each of which being in the form of an anchoring screw threadably disposed within an anchoring screw bore in the cylinder head, is advanceable to force the fuel rail at its at least one rail output port against the at least one fuel injector at its injector inlet to provide a seal therebetween. The at least one rail output port and the at least one injector inlet cooperate to communicate pressurized fuel from the fuel rail cavity directly into the at least one fuel injector without requiring a high-pressure fuel pipe therebetween.

A second embodiment of the present invention is similar to the first except that the first fuel rail has been replaced by a second fuel rail. The first and second fuel rails differ in that the hollow projection of the first fuel rail is an integral part thereof, whereas the similarly shaped hollow projection of the second fuel rail is a separate part brazed to the second fuel rail. A third embodiment is similar to the first and second except that the it uses a third fuel rail, the similarly shaped hollow projection of which is a separate part sealingly held witliin a recess in the third fuel rail when the fuel rail system is assembled by force provided by the anchoring screw.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof may be readily obtained by reference to the following detailed description when considered with the accompanying drawings in which like reference characters indicate corresponding parts in all the views, wherein:

FIGURE 1 is a schematic diagram, partially in section, illustrating a high-pressure fuel rail system in accordance with the present invention;

FIGURE 2 is a sectional side view of a common fuel rail, showing an internal fuel rail cavity and fuel rail output ports, in accordance with the present invention;

FIGURE 3 is a cross-sectional end view of cylinder head at a location indicated in FIGURE 1, illustrating the interface of a fuel injector and a common fuel rail, in accordance with the present invention;

FIGURE 3A is an enlarged view, partially in section, of a portion of the view shown by FIGURE 3;

FIGURE 4 is a cross-sectional view, at a location indicated in

FIGURE 2, showing a first embodiment of the common fuel rail of the present invention;

FIGURE 5 is a view similar to that of FIGURE 4 and showing a second embodiment of the common fuel rail of the present invention; and FIGURE 6 is a view similar to that of FIGURE 4 and showing a third embodiment of the common fuel rail of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to Figure 1, illustrated is a high-pressure fuel rail system, generally indicated by reference numeral 10, for an internal combustion engine, generally indicated by reference numeral 12. The internal combustion engine 12 includes a cylinder head 14 and a block 16. The block 16 has at least one cylinder 18; and the cylinder head 14, the block 16, and a piston 20 within the at least one cylinder 18 cooperate to define therebetween an at least one combustion chamber, generally indicated by reference numeral 22.

A first embodiment of the fuel rail system 10 includes the cylinder head 14, which has therein a generally horizontally extending rail bore, generally indicated by reference numeral 24. A first fuel rail 26, having a rail inlet 28, a rail outlet 30 and a first internal rail cavity 32 therebetween, extends within the rail bore 24. FIGURE 2 provides a side sectional view of the first fuel rail 26. As shown by FIGURES 2 and 4, the first internal rail cavity 32 has at least one rail output port, generally indicated by reference numeral 34. As illustrated by FIGURE 4, which is a cross-sectional view of the first fuel rail taken in the direction of line 4-4 of FIGURE 2, the at least one rail output port 34 is centrally disposed within a hollow projection 36 extending from the first fuel rail 26, the hollow projection 36 having a rounded end 38 that is preferably semispherically configured. Diametrically opposite to the hollow projection 36 is a first rail concavity 40. As further illustrated by FIGURE 4, the hollow projection 36 of the first embodiment is an integral portion of the first fuel rail 26.

Second and third embodiments of the fuel rail system 10 are the same as the first embodiment shown by FIGURES 1, 2, 3 and 3A except for the first fuel rail 26, which has been replaced by second and third fuel rails 42 and 56 respectively. Since only the respective fuel rail projections 48 and 62 and the reference numerals of the illustrated fuel rails 42 and 56 of the respective second and third embodiments differ from those of the first embodiment, to avoid triplicating FIGURES 1, 2, 3 and 3A, the latter figures have been used to illustrate descriptions of the second and third embodiments as well as the description of the first embodiment. Distinct reference numerals are used in the descriptions of the fuel rails 42 (26) and 56 (26) shown in respective FIGURES 5 and 6; and their counterpart, first embodiment reference numerals are included in parentheses as illustrated in this sentence.

The second embodiment of the fuel rail system 10 includes the cylinder head 14, which has therein a generally horizontally extending rail bore, generally indicated by reference numeral 24. A second fuel rail 42 (26) (FIGURE

5) having a second internal rail cavity 44 (32) extends within the rail bore 24. As shown by FIGURES 1, 2, 3 and 3 A, the second internal rail cavity 44 (32) has at least one rail output port, generally indicated by reference numeral 46 (34). As illustrated by FIGURE 5 , which is a cross-sectional view of the second fuel rail 42

(26) taken in the direction of line 4-4 of FIGURE 2, the at least one rail output port

46 (34) is centrally disposed within a hollow projection 48 (36) extending from the second fuel rail 42 (26), the hollow projection 48 (36) having a rounded end 50 (38) that is preferably semispherically configured. Diametrically opposite to the hollow projection 48 is a second rail concavity 54 (40). As further illustrated by FIGURE

5, the hollow projection 48 (36) of the second embodiment is not an integral portion of the second fuel rail 42 (26). Rather, it is a similarly shaped but separate part brazed into a recess 52 within the second fuel rail 42 (26) using a brazing filler 53.

The third embodiment of the fuel rail system 10 includes the cylinder head 14, which has therein a generally horizontally extending rail bore, generally indicated by reference numeral 24. A third fuel rail 56 (26) having a third internal rail cavity 58 (32) extends within the rail bore 24. As shown by FIGURES 1, 2 and 3, the third internal rail cavity 58 (32) has at least one rail output port, generally indicated by reference numeral 60 (34). As illustrated by FIGURE 6, which is a cross-sectional view of the third fuel rail 56 (26) taken in the direction of line 4-4 of FIGURE 2, the at least one rail output port 60 (34) is centrally disposed within a hollow projection 62 (36) extending from the third fuel rail 56 (26), the hollow projection 62 (36) having a rounded end 64 (38) that is preferably semispherically configured. Diametrically opposite to the hollow projection 62 (36) is a third rail concavity 68 (40). As further illustrated by FIGURE 6, the hollow projection 62 (36) of the third embodiment is not an integral portion of the third fuel rail 56 (26) . Rather, it is a similarly shaped but separate part sealingly held within a recess 66 in the third fuel rail 56 (26) when the fuel rail system 10 is assembled by force provided by an anchoring screw 86 (FIGURE 3).

The fuel rail system 10 also includes at least one fuel injector 70 for metering fuel into the at least one combustion chamber 22. The at least one fuel injector 70 (FIGURE 3) has an injector inlet 72 (FIGURE 3A) and a nozzle 74, as shown by FIGURE 3, is typically retained within a fuel injector bore 71 in the cylinder head 14 by a clamp 76 and a bolt 78. As shown in greater detail by

FIGURE 3A, the injector inlet 72 is centrally disposed within an injector recess 80 having a rounded interior end 82 that is preferably semispherically configured. The at least one fuel injector 70 extends downwardly through the cylinder head 14 generally vertically and at right angles past the first fuel rail 26. The at least one fuel injector 70 is disposed so that the at least one rail output port 34 is juxtaposed with the injector inlet 72, and the injector nozzle 74 extends to a position for injecting fuel for combustion within the at least one combustion chamber 22

(FIGURE 1).

As shown by FIGURES 3 and 3 A, the cylinder head 14 has therein a generally horizontal anchoring screw bore 84 extending at right angles to both the at least one fuel injector 70 and to the rail bore 24. An anchoring screw 86 is threadably disposed within the anchoring screw bore 84. The anchoring screw 86 has an external end 88 typically configured to form a hexagonal head to facilitate rotating the anchoring screw 86; and it has an internal end 90, preferably rounded to cooperatively fit within the first rail concavity 40. Rotating the anchoring screw 86 in one direction advances it toward the first rail concavity 40 in the first fuel rail 26 and forces the at least one rail output port 34 of the first fuel rail 26 against the injector inlet 72 of the at least one fuel injector 70. Also shown by FIGURE 3 is a fuel port 92 representing at least one passage (not shown) that returns excess fuel from the at least one fuel injector 70 to a fuel reservoir 94 (FIGURE 1).

FIGURES 3 and 3A show that the semispherically shaped projection end 38 cooperates with the semispherical recess end 82 to facilitate laterally aligning the at least one fuel rail output port 34 with the injector inlet 72 of the at least one fuel injector 70 and to compensate for small amounts of misalignment therebetween. The semispherically configured ends 38 and 82 also facilitate the creation of a metal- to-metal seal therebetween when the anchoring screw 84 forces the first fuel rail 26 toward the at least one fuel injector 70, thereby providing a path for communicating pressurized fuel from the first internal rail cavity 32 into the at least one fuel injector 70.

With reference once more to FIGURE 1, shown is a fuel filter 96 in communication with the fuel reservoir 94. A high-pressure pump 98 draws fuel from the fuel reservoir 94, through a fuel filter 96, and forces it into the first fuel rail 26 via the fuel rail inlet 28. Fuel within the first fuel rail 26 is maintained within a specific pressure range by any of a number of well-known control systems (not shown). The pressurized fuel is communicated to the at least one fuel injector 70 via the fuel rail output port 34 and the injector inlet 72. Fuel is then controUably metered and injected from the nozzle 74 of the at least one fuel injector 70 for combustion within the at least one combustion chamber 22. Fuel not used by the at least one fuel injector 70 is returned via the fuel return port 92 (FIGURE 3) to the fuel reservoir 94.

Since the at least one fuel injector 70 is provided with pressurized fuel directly from the first fuel rail 26, the need for there being high-pressure fuel pipes to perform this function is eliminated. The high-pressure fuel rail system 10 of the present invention thus saves the expense and time required to manufacture, assemble and service high-pressure fuel pipes, eliminates fuel flow turbulence promoted by various fuel pipe bends and connections, and avoids fuel leaks caused by vibration and potentially damaging impacts to which fuel pipes are exposed. The high-pressure fuel rail system 10 of the present invention is assembled, as shown by FIGURES 3 and 3A, by securing the at least one fuel injector 70 to the cylinder head 14 with the clamp 76 and the bolt 78. The fuel rail 26 is then positioned within the rail bore 24 so that the at least one rail output port 34 is juxtaposed with the injector inlet 72 of the at least one fuel injector 70. An anchoring screw 86 is next inserted in the at least one anchoring screw bore 84 and rotated to drive the anchoring screw 86 into contact with the fuel rail 26 with sufficient force to ensure that there is no fuel leakage between the fuel rail 26 output port 34 and the injector inlet 72.

While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A high-pressure fuel rail system for use in an internal combustion engine having a cylinder head and at least one combustion chamber, the system comprising: at least one fuel injector connected vertically to the cylinder head for metering fuel into the at least one combustion chamber, the at least one fuel injector having an injector inlet to receive pressurized fuel; a common fuel rail including at least one rail inlet to receive pressurized fuel, an internal rail cavity to store pressurized fuel input through the at least one rail inlet, at least one rail outlet, and at least one rail output port, the cylinder head having a rail bore extending horizontally therewithin, the common fuel rail extending within the rail bore at right angles to the at least one fuel injector so that the at least one rail output port is juxtaposed with the injector inlet of the at least one fuel injector; and at least one securing member supported by the cylinder head and being advanceable to force the common fuel rail at its at least one rail output port normally against the at least one fuel injector at its injector inlet to provide a fuel seal therebetween, the at least one rail output port and the at least one injector inlet cooperating to communicate pressurized fuel from the internal rail cavity directly into the at least one fuel injector.

2. The fuel rail system as defined by claim 1, wherein the common fuel rail has extending therefrom at least one hollow projection within the distal tip of which is disposed the at least one rail output port, and wherein the injector inlet is disposed within a recess in the at least one fuel injector, the recess in the at least one fuel injector having an interior end and closely receiving and laterally locating the tip of the at least one hollow projection of the common fuel rail.

3. The fuel rail system as defined by claim 2, wherein the cylinder head has at least one anchoring screw bore that extends horizontally inward from a side of the cylinder head to a position proximate and at right angles to the common fuel rail and at right angles to the at least one fuel injector, and wherein the at least one securing member is an anchoring screw threaded within the at least one anchoring screw bore, a rotation of the anchoring screw advancing it toward the common fuel rail, thereby forcing the tip of the at least one hollow projection of the common fuel rail into the recess in the at least one fuel injector.

4. The fuel rail system as defined by claim 3, wherein the configuration of the tip of the at least one hollow projection of the common fuel rail and the configuration of the interior end of the recess of the at least one fuel injector are semispherical.

5. The fuel rail system as defined by claim 4, wherein the end of the anchoring screw proximate the common fuel rail has a rounded tip and the common fuel rail has a concavity disposed diametrically opposite the at least one rail outlet, the concavity in the common fuel rail receiving and laterally locating the rounded tip of the anchoring screw.

6. The fuel rail system as defined by claim 5, further including a fuel return port tlirough which uninfected fuel is recovered for return to a fuel reservoir.

7. The fuel rail system as defined by claim 6, wherein the hollow projection having the at least one rail output port therein is integral with the common fuel rail from which it extends.

8. The fuel rail system as defined by claim 6, wherein the hollow projection having the at least one rail output port therein is a separate part brazed to the common fuel rail from which it extends.

9. The fuel rail system as defined by claim 6, wherein the hollow projection having the at least one rail output port therein is a separate part snarlingly held, after the anchoring screw has been advanced, within a recess in the common fuel rail from which it extends.

10. An internal combustion engine, comprising: a cylinder head; at least one combustion chamber; at least one fuel injector connected vertically to the cylinder head for metering fuel into the at least one combustion chamber, the at least one fuel injector having an injector inlet to receive pressurized fuel; a common fuel rail including at least one rail inlet to receive pressurized fuel, having therein an internal rail cavity to store pressurized fuel input tlirough the at least one rail inlet, having therein at least one rail outlet, and having therein at least one rail output port, the cylinder head having a rail bore extending horizontally there within, the common fuel rail extending within the rail bore and being disposed at right angles to the at least one fuel injector so that the at least one rail output port is juxtaposed with the injector inlet of the at least one fuel injector; and at least one securing member fixedly supported by the cylinder head and being advance able to force the common fuel rail at its at least one rail output port normally against the at least one fuel injector at its injector inlet to provide a fuel seal there between, the at least one rail output port and the at least one injector inlet cooperating to communicate pressurized fuel from the internal rail cavity directly into the at least one fuel injector.

11. The internal combustion engine as defined by claim 10, wherein the common fuel rail has extending therefrom at least one hollow projection within the distal tip of which is disposed the at least one rail output port, and wherein the injector inlet is disposed within a recess in the at least one fuel injector, the recess in the at least one fuel injector having an interior end and closely receiving and laterally locating the tip of the at least one hollow projection of the common fuel rail.

12. The internal combustion engine as defined by claim 11, wherein the cylinder head has at least one anchoring screw bore that extends horizontally inward from a side of the cylinder head to a position proximate and at right angles to the common fuel rail and at right angles to the at least one fuel injector, and wherein the at least one securing member is an anchoring screw threaded within the at least one anchoring screw bore, a rotation of the anchoring screw advancing it toward the common fuel rail, thereby forcing the tip of the at least one hollow projection of the common fuel rail into the recess in the at least one fuel injector.

13. The internal combustion engine as defined by claim 12, wherein the configuration of the tip of the at least one hollow projection of the common fuel rail and the configuration of the interior end of the recess of the at least one fuel injector are semispherical.

14. The internal combustion engine as defined by claim 13, wherein the end of the anchoring screw proximate the common fuel rail has a rounded tip and the common fuel rail has a concavity disposed diametrically opposite the at least one rail outlet, the concavity in the common fuel rail receiving and laterally locating the rounded tip of the anchoring screw.

15. The internal combustion engine as defined by claim 14, further including a fuel return port through which uninfected fuel is recovered for return to a fuel reservoir.

16. The internal combustion engine as defined by claim 15, wherein the hollow projection having the at least one rail output port therein is integral with the common fuel rail from which it extends.

17. The internal combustion engine as defined by claim 15, wherein the hollow projection having the at least one rail output port therein is a separate part brazed to the common fuel rail from which it extends.

18. The internal combustion engine as defined by claim 15, wherein the hollow projection having the at least one rail output port therein is a separate part snarlingly held, after the anchoring screw has been advanced, within a recess in the common fuel rail from which it extends.

19. A cylinder head for use in an internal combustion engine, the cylinder head comprising: at least one fuel injector for communicating a metered amount of fuel to at least one combustion chamber; and a common fuel rail disposed within the cylinder head and in direct fluid communication with the at least one fuel injector for transmitting pressurized fuel to the at least one combustion chamber, the at least one fuel injector cooperating with the common fuel rail to create a metal-to-metal seal there between.

20. The cylinder head as defined by claim 19, wherein: the at least one fuel injector is connected vertically to the cylinder head and has an injector inlet to receive pressurized fuel; the common fuel rail includes at least one rail inlet to receive pressurized fuel, an internal rail cavity to store pressurized fuel input through the at least one rail inlet, at least one rail outlet, and at least one rail output port; the cylinder head has a rail bore extending horizontally there within, the common fuel rail extending within the rail bore at right angles to the at least one fuel injector so that the at least one rail output port is juxtaposed with the injector inlet of the at least one fuel injector, the cylinder head has at least one anchoring screw bore extending horizontally inward from a side of the cylinder to a position proximate and at right angles to the common fuel rail and at right angles to the at least one fuel injector; and the cylinder head has an anchoring screw threaded within the at least one anchoring screw bore, a rotation of the anchoring screw advancing it toward the common fuel rail, thereby forcing the at least one rail output port of the common fuel rail directly against the injector inlet of the fuel injector to establish and maintain the metal-to-metal seal there between.

21. The cylinder head as defined by claim 20, wherein the common fuel rail has extending therefrom at least one hollow projection within the distal tip of which is disposed the at least one rail output port, and wherein the injector inlet is disposed within a recess in the at least one fuel injector, the recess in the at least one fuel injector having an interior end and closely receiving and laterally locating the tip of the at least one hollow projection of the common fuel rail.

22. The cylinder head as defined by claim 21, wherein the configuration of the tip of the at least one hollow projection of the common fuel rail and the configuration of the interior end of the recess of the at least one fuel injector are semispherical.

23. The cylinder head as defined by claim 22, wherein the end of the anchoring screw proximate the common fuel rail has a rounded tip and the common fuel rail has a concavity disposed diametrically opposite the at least one rail outlet, the concavity in the common fuel rail receiving and laterally locating the rounded tip of the anchoring screw.

24. The cylinder head as defined by claim 23, further including a fuel return port through which uninfected fuel is recovered for return to a fuel reservoir.

25. The cylinder head as defined by claim 24, wherein the hollow projection having the at least one rail output port therein is integral with the common fuel rail from which it extends.

26. The cylinder head as defined by claim 24, wherein the hollow projection having the at least one rail output port therein is a separate part brazed to the common fuel rail from which it extends.

27. The cylinder head as defined by claim 24, wherein the hollow projection having the at least one rail output port therein is a separate part snarlingly held, after the anchoring screw has been advanced, within a recess in the common fuel rail from which it extends.

28. A method for assembling a high-pressure fuel rail system for use in an internal combustion engine having a cylinder head extending in a generally horizontal, longitudinal direction and at least one combustion chamber, the method comprising the steps of:

(a) forming at least one vertical fuel injector bore within the cylinder head;

(b) forming a common fuel rail bore within the cylinder head to extend longitudinally at right angles past the fuel injector bore;

(c) forming at least one internally threaded anchoring screw bore extending horizontally inward from a side of the cylinder head to a position proximate and at right angles to the common fuel rail bore and at right angles to the at least one fuel injector bore;

(d) securing within the at least one fuel injector bore an at least one fuel injector having an injector inlet and a nozzle, the nozzle being positioned to inject fuel for ignition in the combustion chamber; (e) inserting within the fuel rail bore a common fuel rail having therein at least one rail inlet to receive pressurized fuel, an internal rail cavity to store pressurized fuel input through the at least one rail inlet, at least one rail outlet to pass fuel exiting the internal cavity, and at least one rail output port, the common fuel rail extending at right angles to the an at least one fuel injector so that the at least one rail output port is juxtaposed with the injector inlet of the an at least one fuel injector; and

(f) inserting and advancing within the at least one anchoring screw bore an anchoring screw to force the common fuel rail at its at least one rail output port normally against the an at least one fuel injector at its injector inlet to provide a fuel seal therebetween, the at least one rail output port and the at least one injector inlet cooperating to communicate pressurized fuel from the internal rail cavity directly into the at least one fuel injector.