GB2399392A

GB2399392A - I.c. engine moulded fuel rail with crash-resistant protecting structure

Info

Publication number: GB2399392A
Application number: GB0305697A
Authority: GB
Inventors: Ronald Gerald Fly; Simon Philip Jesse; Milos Pavle Tipsarevic
Original assignee: Visteon Global Technologies Inc
Current assignee: Visteon Global Technologies Inc
Priority date: 2003-03-13
Filing date: 2003-03-13
Publication date: 2004-09-15
Also published as: GB0305697D0; EP1457663A2

Abstract

The fuel rail system 100 comprises an elongate moulded plastic material fuel rail (common rail)106, having a fuel inlet 110 and at a fuel outlet 122, and a moulded plastic barrier 113 extending along the length of the fuel rail 106 and having at least one bar 116 spaced laterally from the fuel rail 106 and joined to it by at least two diagonally extending webs 118 of moulded plastic material. The rail 106 and barrier 113 may be a unitary moulding from a single material, eg glass-filled polyamide, or in a modification (figs.6-9) from two different materials in a two-stage process, eg glass-filled nylon and polypropylene, respectively. The triangular voids defined by the fuel rail, bar and webs may be filled by projections (304, fig. 10) on a separately-moulded strip (301) of resilient material for extra impact protection. Mounting legs 114 may be included in the moulding of the fuel rail system.

Description

In recent years in the automotive industry, there has been an increasing

use of fuel rails made of plastic materials, rather than metal. Fuel, such as gasoline or diesel, is supplied to the engine through a channel in the plastic material, and so the material must be able to withstand prolonged contact with the fuel. One common choice of plastic material is polyamide.

Although plastic material fuel rails are less expensive to manufacture than those formed from metal, plastic materials generally are not as robust as metal materials against impact damage. One way to improve the robustness of a plastic material is to use a composite glass-filled plastic material.

Fuel rails normally have to be situated in close proximity with a cylinder head or engine block. (For convenience, the term "engine block" shall be used hereinafter to denote a cylinder head or engine block, either individually or in combination.) This is particularly the case in automotive applications, where there may be little free space in an engine compartment. The proximity of the fuel rail to the engine block, and other components within the engine compartment means that in the event of a collision the fuel rail may be impacted or pressed upon by such components. In one standard crash test (Legal Test ref. EC96/79), a fuel rail is deemed to pass if the volume of any egress of fuel is - 2 less than 30 g in one minute. I Therefore, care has to be taken over the placement of nearby components, such as an air inlet manifold or an electronic throttle assembly, as these may come into contact with or strike the fuel rail in the event of a collision. Even where an engine and vehicle design is optimized to minimise the possibility of fuel loss from a fuel rail in the event of a collision, it may not be possible to use the same fuel rail on a different vehicle application for this reason. There also remains the possibility that a change to another component in the engine compartment, seemingly unconnected with the fuel rail, may inadvertently increase the risk of fuel loss after a collision.

One known way of protecting a fuel rail from collision damage is to mount a protective metal shield around the fuel rail.

This however, adds to materials and production costs and tends to obviate some, if not all, of the advantages provided by the use of plastic materials for the fuel rail.

It is an object of the present invention to provide a more convenient fuel rail system for an internal combustion engine.

According to the invention, there is provided a fuel rail! system for an internal combustion engine, comprising an elongate moulded plastic material fuel rail, the fuel rail having at least one fuel inlet, and at least one fuel outlet for supplying fuel to the engine, wherein the system comprises additionally a moulded plastic barrier, the barrier extending along the length of the fuel rail and having at - 3 - least one bar spaced laterally from the fuel rail, the or each bar being joined to the fuel rail by at least two webs of moulded plastic material that extend diagonally between the fuel rail and the or each bar.

Optionally, the fuel rail system comprises additionally a second moulded plastic barrier, the second barrier extending along the length of the fuel rail on an opposite side from the first barrier, the second barrier having at least one bar spaced laterally from the fuel rail, the or each of said bars being joined to the fuel rail by at least two webs of moulded plastic material that extend diagonally between the fuel rail and the or each of said bars. The system may therefore absorb impacts or stresses from opposite directions. This may be useful if, in a collision, the fuel rail could be pinched between two opposing objects, for example an electronic throttle assembly on the one hand and a cylinder head on the other hand.

In the following description, the invention will be described in terms of a single barrier, however, it will be understood that if the fuel rail system has two such barriers arranged on opposite sides of the fuel rail, the features described for one barrier may be present on both barriers.

The bar may therefore be arranged to bear an impact from another component. The stresses from the impact are then transferred between the fuel rail and the bar along the webs.

Because the bar is essentially separated from the fuel rail by the webs, and cracking or deformation of the bar will not affect the fuel integrity of the fuel rail. In addition, the webs may be made sufficiently thin that these may bend or - 4 otherwise deform. Any movement of the bar may therefore be at least partially accommodated by the deformation of the webs.

This movement will also help to dissipate the energy of the impact, so that this is born by the fuel rail over a longer time, and this has the effect of lowering the maximum forces on the bar.

Although the barrier may be formed separately from the fuel rail, for example being fitted to or around the fuel rail, it is preferred if the barrier is integrally formed with the fuel rail, for example being a unitary moulding.

In a preferred embodiment of the invention, the fuel rail is moulded from a first plastic material, and the barrier is moulded from a second plastic material.

The barrier may be comprised of discontinuous or discrete sections, but is preferably a unitary elongate barrier, and continuous along the length of the fuel rail.

The webs and/or fuel rail may be designed to help spread the load of any impact along the fuel rail, thereby reducing the chance of failure of the fuel rail at any one point. For example, the fuel rail may be reinforced along its length between points at which the webs of moulded plastic material join the fuel rail.

Additionally or alternatively, if the fuel rail and the bar extend substantially parallel with each other, and the or each web may extend non-transversely, i.e. angled away from a right angle, between the fuel rail and the bar. : - 5 -

Therefore, in a preferred embodiment of the invention, at least one web may extend away from one of the fuel rail or the bar at an acute angle, and extend towards the other of the fuel rail or the bar at an obtuse angle.

If there are at least three webs of moulded plastic material joining the bar and the fuel rail, these webs may be arranged in a zigzag pattern between the fuel rail and the bar (that is, arranged head-to-tail alternately from the bar to the fuel rail, and from the fuel rail to the bar). This has two benefits in the event of an impact on the barrier. First, any local movement of the bar will tend to cause a lateral deformation of the adjacent webs, thus absorbing impact energy. Second, the stresses will then be transferred in opposite lateral directions away from the localised impact, thereby spreading the forces on the fuel rail and so minimising the possibility of any significant damage to the fuel rail.

The zigzag arrangement permits adjacent webs, together with either the fuel rail or the bar, to define one or more triangular voids in the barrier. In this arrangement, each web may be joined to at least one other web at a vertex on the bar or on the fuel rail.

Preferably, the or each bar is square or rectangular in cross-section. Opposite flat faces of the bar may then be arranged to face respectively directly towards the fuel rail and directly away from the fuel rail. The face that faces away from the fuel rail will therefore be arranged to face towards a possible impact, which will help to spread loads across this face. In addition, this arrangement means that - 6 - there will not be any corners between such faces directed at the fuel rail, which could cause damage in the event of an impact.

If the fuel rail extends along a first axis, and the or each bar extends along a second axis, wherein the webs each extend in a plane that is transverse to a plane containing both the first axis and the second axis.

The webs may define, with the bar and/or the fuel rail, a plurality of voids, in which case the system may comprise additionally at least one strip of resilient material. This strip or strips may then have projections that are seated in corresponding voids. For ease of assembly, it is preferred if there is just one such strip for one barrier, and also if the projections fill the voids.

Also according to the invention, there is provided an internal combustion engine for a motor vehicle, comprising an engine block with one or more combustion chambers therein, and a fuel rail system mounted to the engine block for supplying fuel to the or each combustion chamber, wherein the fuel rail system is according to the invention.

The fuel rail system may then include at least one leg by which the fuel rail system is mounted to the engine block (either directly for example on the cylinder head, or via an intervening structure connected to the engine block, such as the inlet manifold), the or each leg being joined to the fuel rail and not the barrier(s). Preferably, there is one pair of legs, arranged towards opposite ends of the fuel rail. - 7

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is partial perspective view of a conventional internal combustion engine for a motor vehicle, having an engine block and a prior art plastic moulded fuel rail mounted to the engine block) Figure 2 is a perspective view of a moulded plastic fuel rail system according to a first embodiment of the invention, having an elongate moulded plastic material fuel rail with one fuel inlet, and a parallel with this rail a protective moulded barrier; Figures 3 and 4 are, respectively front side and top views of the fuel rail system of Figure 2, showing the barrier and fuel rail; Figure 5 is cross-sectional view through the fuel rail system of Figures 2-4 taken along line V-V of Figure 5; Figure 6 is a perspective view of a moulded plastic fuel rail system according to a second embodiment of the invention, having an elongate moulded plastic material fuel rail with an inlet and return outlet, and a parallel with this rail a protective moulded barrier; Figures 7 and 8 are, respectively top and rear side views of the fuel rail system of Figure 6; Figure 9 is cross-sectional view through the fuel rail - 8 system of Figures 6-8 taken along line IX- IX of Figure 8i Figure 10 is a perspective view of a moulded plastic fuel rail system according to a third embodiment of the invention, which is similar to the second embodiment of Figures 6-9, but having also a strip of resilient material which has projections that are seated in corresponding voids in the barrier; Figure 11 is a perspective view of a moulded plastic fuel rail system according to a fourth embodiment of the invention, which is similar to the first embodiment of Figures 2-5, but having a pair of legs each having rearwards portion that is joined to the fuel rail, and a forwards portion that is joined to the barrier; and Figure 12 is an end view of the moulded plastic fuel rail according to a fifth embodiment of the invention, which is similar to the second embodiment of Figure 9, but having a pair of legs similar to those of the fourth embodiment of Figure 11.

Figure 1 shows a partial view of a conventional reciprocating piston internal combustion engine 1, having an engine block 2, an inlet manifold 4 and a fuel rail 6 for delivering fuel to a number of cylinders (not shown) inside the engine block 2. In Figure 1, the fuel rail 6 is shown end on in the direction of an axis 8 in the centre of a hollow cylindrical fuel inlet 10. The fuel rail 6 is fixed to the engine block 2 by means of a mounting bracket 14 and bolts (not shown). Not shown, for clarity, is a fuel inlet pipe that would be - 9 - connected to the inlet 10. The fuel rail 6 extends along the direction of the axis 8 in order to conveniently supply fuel to the cylinders, for example by means of fuel injectors (not shown), in a manner that is well known to those skilled in the art.

As can be seen from Figure 1, a fuel rail 6 is positioned generally between the inlet manifold 4 and the engine block 2. The inlet manifold 4 may include other components, for example an electronic throttle control assembly 12.

Components such as the throttle assembly 12 may, in the event a vehicle collision, be thrust against the fuel rail 6, leading to the possibility of damage to the fuel rail and consequent escape of fuel. As a result, it may be preferable to manufacture the fuel rail 6 in a metal material, for example aluminium, rather than less expensive moulded plastic materials. If a plastic material is used, then the fuel rail 6 may have to be protected by a half-cylindrical metallic shield (not shown) extending along the length of the fuel rail 6 between the fuel rail and the inlet manifold 4 and throttle assembly 12.

Figures 2-5 show various views of a moulded plastic fuel rail system 100 according to a first embodiment of the invention.

The fuel rail system 100 comprises an elongate plastic material fuel rail 106 that extends along an axis 108 between a fuel inlet 110 and a closed end 111 of the fuel rail. The fuel rail system 100 also includes a moulded plastic barrier 113 that extends parallel with the fuel rail 106, and a pair of mounting legs 114 that extend from the fuel rail 106, and by which the fuel rail system 100 may be mounted to an engine block, for example the engine block 2 shown in Figure 1. Each - 10 leg has a forwards portion 115 with three similarly shaped parallel bars 117, and a single rearwards portion 119. The forwards and rearwards portions 115,119 are joined together at a base 109, from which these portions 115,119 extend upwards to the fuel rail 106. The rearwards portion 119 is essentially straight. A lower portion of each of the three bars 117 is approximately parallel and forwards with the rearwards portion 119. An upwards portion of each of the bars 117 is angled back towards the rearwards portion 119.

The barrier 113 extends along the length of the fuel rail 106 and has an elongate bar 116 spaced laterally from the fuel rail 106. The bar 116 is joined to the fuel rail by a number of webs 118 of moulded plastic material that extend diagonally between the fuel rail 106 and the bar 116. In the example of Figure 2-5, both the barrier 113 and the fuel rail 106 are formed in a unitary moulding, from a single glass filed polyamide material, which is resistant to the flow of fuel such as gasoline or diesel along a fuel passageway 120 that runs between the fuel inlet 110 and four fuel outlets 122 for connection to four corresponding fuel injectors (not shown). The webs 118 and bar 116 therefore form a unitary impact barrier 113, which is integrally moulded with the fuel rail 106.

As can be seen most clearly in Figure 5, the bar 116 is rectangular in cross-section, with one flat face 121 facing towards the fuel rail 106, and the opposite flat face 123 facing directly away from the fuel rail 106. Both the bar 116 and webs 118 have common upper and lower surfaces 124,125 that extend at right angles to the length of the fuel rail 106. The webs 118 are preferably thinner than the thickness of the bar 116, and most preferably are between 10% and 50% of the thickness of the bar 116. In the example of Figure 2- 5, the webs 118 are 20% the thickness of the bar 116. As a result, the webs 118 are considerably less ridged than the bar 116.

The webs 118 are also arranged in a zigzag pattern between the fuel rail 106 and bar 116. Therefore, if a force (F) as indicated by arrow 130 is exerted against the outer face 123 of the bar 116, for example during an impact of components such as an air inlet manifold 4 or throttle assembly 12 against the barrier 113, then one or more of the webs 118 may deform as the bar 116 moves towards the fuel rail 106. The deformation may take the form of bending or cracking through.

As can be seen in Figure 2 each web 118 splays outwards, and is therefore reinforced where this meets the fuel rail 106, and this together with the diagonal arrangement of the webs 118 tends to spread the force 130 laterally along the extent of the fuel rail 106.

Figures 6-9 show a moulded plastic fuel rail system 200 according to a second embodiment of the invention, in which features similar to those of the first embodiment 100 are indicated by reference numerals incremented by 100. The second embodiment 200 is similar to the first embodiment 100 in that it includes an elongate fuel rail 206 that is integrally moulded with a parallel barrier 213. The fuel rail system 200 includes both a fuel inlet 210 and a fuel return 209 together with an integrally moulded intervening pressure regulator 245. Such a fuel rail system 200 is designed for use in a motor vehicle fuel system having both flow and return fuel lines (not shown). In addition, the second - 12 embodiment 200 has a barrier 213 that is raised slightly relative to an axis 208 that runs along the centre of a fuel channel 220 through the fuel rail 206. This is in order to provide a degree of protection also to the fuel regulator 245, which extends above the fuel rail 206.

Because of these differences, the barrier 213 has webs 218 that extend between a front bar 216 and a rear reinforcing bar 226 that is integrally moulded with the fuel rail 206.

The rear reinforcing bar 226 is essentially part of the fuel rail 206. As shown most clearly in Figure 9, the rear bar 226 has planar top and bottom surfaces 221,225 in common with the webs 218 and front bar 216.

The second embodiment 200 also differs from the first embodiment 100 in that this is integrally moulded in a two-stage moulding process using a first plastic material for the fuel rail 206, including the rear bar 226, for example a glass-filed polyamide, and a second more compliant and resilient plastics material for the webs 218 and front bar 216 of the barrier 213, for example polypropylene. The two-stage moulding process is accomplished by using a moulding tool (not shown) which has a thin retractable gate that forms initially a barrier between, on the one hand, the webs 218 and bar 216 of the barrier 213 and, on the other hand, the fuel rail 206 and its reinforcing bar 226. When the moulding tool is nearly filed with both plastic materials, the barrier is withdrawn, thereby allowing the first and second plastic materials to come together at the boundary between the rear bar 226 and webs 218 in order to form a unitary moulded structure. In this process, a pair of legs 214 extending from the fuel rail 206 are also moulded at the same time in the first plastic material.

In use, the second embodiment of the fuel rail system 200 functions in a similar manner to the first embodiment. A force (F) 230 on the front surface 223 of the bar 216 may cause local damage to the bar 216 and deformation of the webs 218, however this deformation and the diagonal arrangement of the webs 218 will help to dissipate and spread the force 230 laterally over the fuel rail 206.

Figure 10 illustrates a third embodiment of a fuel rail system 300, in which features similar to those of the first embodiment 100 are indicated by reference numerals incremented by 100. The second embodiment 300 consists of the second embodiment 200 in combination with a strip of resilient material 301 which is made from a unitary moulding and acts to provide additional energy absorbing ability to the barrier 213. The zigzag arrangement of the webs 218 creates a series of laterally adjacent recesses 302. Each recess 302 has a triangular cross-section in planes parallel to the top and bottom surfaces 224,225 that extend across the front bar 216, webs 218 and rear bar 226. Each of the webs 218 is joined head to tail with at least one neighbouring web 218, so that each of the triangular recesses 302 is defined one two sides by two adjacent webs 218 which meet at an intervening vertex 228, and on the third side by either the rear surface 221 of the front bar 216 or a front surface 232 of the rear bar 226.

The resilient strip 301 has a series of laterally adjacent protrusions 304 each of which has a similar triangular cross-section shape so that these can partially or completely - 14 fill corresponding triangular recesses 302. The strip 301 is separately moulded from an elastomeric material, for example a natural rubber or nitrite material. The strip 301 has a planar backing 306 from one side of which the projections 304 extend. The flange 306 also has the same rectangular outer profile as the barrier 213 and rear bar 226. In the event of a collision, the resilient strip 301 will provide additional energy absorbing capability, as well as helping to maintain the structural integrity of the barrier 216.

Figures 11 and 12 show, respectively, a fourth and a fifth embodiment of the invention 400. In the fourth embodiment 400 features similar to those of the first embodiment 100 are indicated by reference numerals incremented by 200 from those of the first embodiment 100. In the fifth embodiment 500 features similar to those of the second embodiment 100 are indicated by reference numerals incremented by 200 from those of the second embodiment 200.

The fourth embodiment 400 differs from the first embodiment in having mounting legs 314 that extend from the fuel rail 306, and by which the fuel rail system 400 may be mounted to an engine block, for example the engine block 2 shown in Figure 1. Each leg has a forwards portion 315 with three similarly shaped parallel bars 317, and a single rearwards portion 319. The forwards and rearwards portions 315,319 are joined together at a base 309, from which these portions 315,319 extend upwards to the fuel rail 306. The rearwards portion 319 is essentially straight. The full extent of each of the three bars 317 is parallel with and forwards of the rearwards portion 319. It has been found that this configuration can provide additional bracing to the barrier - 15 313 in the event of an impact on the barrier. The effect is to transmit more of the impact energy into the base 309 of the legs 314, thereby reducing the amount of impact energy which is borne by the fuel rail 306.

The fifth embodiment 500 differs from the second embodiment 200, and is similar to the fourth embodiment 400 in having mounting legs 414 that extend from the fuel rail 406, and by which the fuel rail system 500 may be mounted to an engine block, for example the engine block 2 shown in Figure 1. Each leg has a forwards portion 415 with three similarly shaped parallel bars 417, and a single rearwards portion 419. The forwards and rearwards portions 415,419 are joined together at a base 409, from which these portions 415,419 extend upwards to the fuel rail 406. The rearwards portion 419 is essentially straight. The full extent of each of the three bars 417 is parallel with and forwards of the rearwards portion 419. The legs 414 provide improved bracing and load distribution as described above for the fourth embodiment 400.

The various embodiments of the invention 100,200,300,400 therefore provide an economical and convenient plastic moulded fuel rail system with integral impact protection for a fuel rail.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately, or in any suitable combination. - 17

Claims

Claims: 1. A fuel rail system for an internal combustion engine,

comprising an elongate moulded plastic material fuel rail, the fuel rail having at least one fuel inlet, and at least one fuel outlet for supplying fuel to the engine, wherein the system comprises additionally a moulded plastic barrier, the barrier extending along the length of the fuel rail and having at least one bar spaced laterally from the fuel rail, the or each bar being joined to the fuel rail by at least two webs of moulded plastic material that extend diagonally between the fuel rail and the or each bar.
2. A fuel rail system as claimed in Claim 1, in which the fuel rail is integrally moulded with the barrier.
3. A fuel rail system as claimed in Claim 2, in which the fuel rail is moulded from a first plastic material, and the barrier is moulded from a second plastic material.
4. A fuel rail as claimed in any preceding claim, in which the fuel rail is reinforced along its length between points at which the webs of moulded plastic material join the fuel rail.
5. A fuel rail system as claimed in any preceding claim, in which the fuel rail and the bar extend substantially parallel with each other, and the or each web extends non-transversely between the fuel rail and the bar.
6. A fuel rail system as claimed in any preceding claim, in which at least one web extends away from one of the fuel rail or the bar at an acute angle, and extend towards the other of the fuel rail or the bar at an obtuse angle.
7. A fuel rail system as claimed in any preceding claim, in which there are at least three webs of moulded plastic material joining the bar and the fuel rail, said webs being arranged in a zigzag pattern between the fuel rail and the bar.
8. A fuel rail system as claimed in Claim 7, in which adjacent webs form together with either the fuel rail or the bar define a triangular void in the barrier.
9. A fuel rail system as claimed in any preceding claim, in which each web is joined to at least one other web at a vertex on the bar or on the fuel rail.
10. A fuel rail system as claimed in any preceding claim, in which the or each bar is square or rectangular in cross section.
11. A fuel rail system as claimed in any preceding claim, in which the fuel rail extends along a first axis, and the or each bar extends along a second axis, wherein the webs each extend in a plane that is transverse to a plane containing both the first axis and the second axis.
12. A fuel rail system as claimed in any preceding claim, in which the webs define with the bar and/or the fuel rail, a plurality of voids, the system comprising additionally at least one strip of resilient material, the or each strip having projections that are seated in corresponding voids. l - 19
13. A fuel rail system as claimed in Claim 12, in which said projections fill the voids.
14. A fuel rail system as claimed in Claim 12 or Claim 13, in which the strip has a planar backing from one side of which the projections extend.
15. A fuel rail system as claimed in any of Claims 12 to 14, in which the strip is a unitary moulding.
16. A fuel rail system as claimed in any preceding claim, in comprising additionally a second moulded plastic barrier, the second barrier extending along the length of the fuel rail on an opposite side from the first barrier, the second barrier having at least one bar spaced laterally from the fuel rail, the or each of said bars being joined to the fuel rail by at least two webs of moulded plastic material that extend diagonally between the fuel rail and the or each of said bars.
17. An internal combustion engine for a motor vehicle, comprising an engine block with one or more combustion chambers therein, and a fuel rail system mounted to the engine block for supplying fuel to the or each combustion chamber, wherein the fuel rail system is as claimed in any preceding claim.
18. An internal combustion engine as claimed in Claim 17, in which the fuel rail system includes at least one leg by which the fuel rail system is mounted to the engine block, the or each leg being joined to the fuel rail and not the 1' ' - 20 barrier(s).
19. An internal combustion engine as claimed in any of Claims 1 to 17, in which the fuel rail system includes at least one leg by which the fuel rail system is mounted to the engine block, the or each leg having a rearwards portion that is joined to the fuel rail, and a forwards portion that is joined to the barrier(s).
20. An internal combustion engine as claimed in Claim 19, in which the rearwards portion of the leg and the forwards portion of the leg are parallel with each other.
21. A fuel rail system, substantially as herein described, with reference to or as shown in Figures 2 to 5, or Figures 6 to 9, or Figure 10, or Figures 11 to 12 of the accompanying drawings.
22. An internal combustion engine for a motor vehicle, having a fuel rail system substantially as herein described, with reference to or as shown in Figures 2 to 5, or Figures 6 to 9, or Figure 10, or Figures 11 to 12 of the accompanying drawings.