EP1310669A2 - Fuel injector with simple mounting structure through an integral valve cover - Google Patents

Abstract

The arrangement has a fixing bolt screwed into the cylinder head and a forked clamping element (2) through which the bolt passes with two fork legs (2a,2b). The shaft (7) of the fuel injector narrows towards the injection nozzle (6) and the narrowed shaft has opposing fittings (5a,5b) at one point with a width not in excess of the original diameter of the fuel injector.

Description

Technical field

High-pressure injection systems are increasingly being used in fuel injection systems for internal combustion engines with a high-pressure common room. The fuel injectors on the internal combustion engine are made by these high-pressure injection systems supplied with fuel under very high pressure. by virtue of The prevailing pressure conditions make it extremely secure to secure the fuel injectors important. The fuel injectors are usually designed with a fork-shaped design Clamping claws (clamps) attached in the cylinder head.

State of the art

According to the fastening device for a fuel injector described in EP-A 0 957 263 the forks of a clamping claw rest on flat recesses in the fuel injector on. The forks also have curved lugs on the shoulders of the fuel injector rest. The clamping claw is through a fastening screw in the cylinder head attached; in addition, it is secured by a counter bearing, with a partial area this counter bearing on the lever point of the clamping claw reinforced with a survey acts. For an expansion of the injector, the cover must first of all, as well the counter bearing are removed. The expansion is therefore labor and time intensive.

The claws of GB-A 2 213 197 also have curved lugs Shoulders rest on the fuel injector. The inside of their forks are flat and lying flat recesses in the fuel injector. The forks of the clamp opposite part of the clamping claw is supported by an additional support arm. The fastening device for the fuel injector also contains a device which allows the support arm to be aligned.

DE-C 44 13 415 describes a fastening device in which the Spaunpratze from gripped like a claw and is thus additionally secured. They are also here Forks the clamp on flat recesses on the fuel injector.

The fastening devices for fuel injectors known from the prior art in the cylinder head of an internal combustion engine, the need is common, the clamping claw by additional devices such as a counter bearing, a support arm or secure a clamp to ensure an optimal fit of the fuel injector to be able to. In addition, the forks of the clamps each lie on flat recesses of the fuel injector.

Another common feature of the fastening devices known from the prior art is that the fuel injector is first brought into its final position during assembly must be before the fork of the claw from the side into the recesses on the injector can be inserted. Finally, a screw or nut is usually used assembled and the construction fixed with screw force. For this type of assembly Construction space must be available in the cylinder head, which is the case with cylinder heads with four Valves per cylinder is relatively difficult to do. Furthermore, there are requirements the compactness of the cylinder head construction, the lower part of the fuel injector in the oil mist to install the camshafts, so that on the shaft of the Fuel injector a seal to the valve cover closing the oil mist space is provided.

Presentation of the invention

With the solution proposed according to the invention, to taper the shaft of the fuel injector in the direction of the injection nozzle from a diameter d ₀ to a diameter d ₁ and to provide this tapered shaft with mutually opposite approaches (i.e. by 180 °), the width l ₁ the point with the lugs is not larger than the original diameter d ₀ , it is possible to push the stem of the fuel injector for mounting through a hole in the valve cover with diameter d ₀ and through the forks of the clamping claw with distance d ₂ , that the approaches are below the forks of the clamping claw, and to secure them by turning through 90 ° and fastening the clamping claw with a fastening screw. Here d ₁ ≤ d ₂ . The fuel injector is now pressed firmly into its mounting hole in the cylinder head by the forks of the clamping claw resting on the shoulders. The force ratios here are the same as in the fastening devices known from the prior art. Additional fastening elements for securing the clamping claw - apart from a fastening screw (clamping screw) - are however not necessary. Nor is it necessary for the fuel injector to have flat recesses.

The fuel injector can be easily removed after loosening the fastening screw by turning it 90 ° again and pulling the fuel injector through the forks the claw through the opening in the valve cover. An expansion the valve cover is no longer necessary. This is particularly advantageous because of an expansion of the valve cover means increased assembly effort and the risk of contamination of the oil mist space around the camshafts and their storage during assembly.

The fuel injector can therefore from above after the valve cover has already been installed through a round opening in the valve cover so that the part of the fuel injector towards the injector in the camshaft chamber with a claw located there is secured while the part of the fuel injector with the high pressure connection and the connector is outside the camshaft space. Because the opening in the valve cover is round, sealing is easily possible. The use of a split valve cover can be avoided.

A cylindrical sealing surface is preferably applied to the shaft of the fuel injector, on which the seal sits in the valve cover. Because the force of the claw preferred close to the cylinder, the sealing surface is at the top of the fuel injector above the claw appropriate.

The valve cover also has an additional opening through which the tool for Tightening or loosening the fastening screw of the clamping claw is made possible. The Dimension of this opening is determined by the dimension of the tool for loosening and tightening the fastening screw. The opening can be done with a simple plug or a screw can be closed.

So it is possible to install the clamp first, then the valve cover and finally the fuel injector and this by tightening the fastening screw that the Clamping claw penetrated to secure firmly.

The lugs on the shaft of the fuel injector can be of any shape and have a variable material thickness, but the following should be noted: The width l _{1 of} the fuel injector at the location provided with lugs is less than or equal to the original diameter d _{0 of} the fuel injector. The width l ₁ is preferably less than or equal to the length of the forks of the clamping claws l ₂ (l ₁ l l ₂ ). In addition, the lugs are preferably so large that in the assembled state the forks with the width d ₃ lie completely on the lugs, that is to say l ₁ = d ₁ + d ₃ . The forks of the clamp are generally rectangular. Their corners are preferably rounded. When assembled, the forks are usually not in direct contact with the shaft of the fuel injector, but are a tenth of a mm apart.

The tapered shaft of the fuel injector has a diameter d ₁ that is less than or equal to the distance d _{2 of} the two forks of the clamping claw from one another. The distance d _{5 of} the lugs from the point of the fuel injector at which it still has the diameter d ₀ must be at least as large as the material thickness d _{4 of} the forks of the clamping claw.

Generally the lugs are made from the same material as the fuel injector stem and shaped out of it. The approaches can also be done separately Output part to be attached to the fuel injector shaft.

drawings

The invention is explained in more detail below with the aid of the drawings.

Fig. 1

einen Schnitt durch einen Teil eines Zylinderkopfes einer Verbrennungskraftmaschine mit herkömmlich montiertem Kraftstoffinjektor und einem separaten Ventildeckel.

Fig. 2

eine Ausführungsvariante einer Befestigungsvorrichtung in Frontalansicht.

Fig. 3a, 3b

Jeweils eine Ausführungsvariante einer Befestigungsvorrichtung in Aufsicht.

Fig. 4

einen Schnitt durch einen Teil eines Zylinderkopfes einer Verbrennungskraftmaschine mit erfindungsgemäß montiertem Kraftstoffinjektor und einem ungeteilten Ventildeckel in Frontalansicht.

Fig. 4a

den mit Z bezeichneten Ausschnitt aus Fig. 4.

It shows:

Fig. 1

a section through part of a cylinder head of an internal combustion engine with a conventionally mounted fuel injector and a separate valve cover.

Fig. 2

a variant of a fastening device in a front view.

3a, 3b

In each case, an embodiment variant of a fastening device in supervision.

Fig. 4

a section through part of a cylinder head of an internal combustion engine with a fuel injector mounted according to the invention and an undivided valve cover in frontal view.

Fig. 4a

the section labeled Z from FIG. 4.

Figures 1, 2, 4 and 4a show the fuel injector in the assembled state, the figures 3a and 3b show it in the unmounted state.

variants

Figure 1 shows a device known from the prior art for fastening a Fuel injector 1. Part 1a of the fuel injector with the connector for the High-pressure manifold (common rail) lies outside the camshaft chamber of the internal combustion engine. The part of the fuel injector on the injector side is located itself in the camshaft space and is secured there by means of a traverse 9, which is secured with two fastening screws 3 is attached to the cylinder head. To remove the fuel injector too valve cover 4 must also be removed.

Figure 2 shows an inventive device for fastening a fuel injector 1 in the cylinder head of the camshaft chamber of an internal combustion engine, containing a fuel injector 1, the shaft 7 tapers towards the injection nozzle 6 from a diameter d ₀ to a diameter d ₁ and at the tapered shaft of each other opposite lugs 5a and 5b are at a distance d ₅ from the injector part 1a with the diameter d ₀ . In the assembled state of the fuel injector shown here, the forks 2a and 2b of the fork-shaped clamping claw 2, which have a material thickness d ₄ , rest on the shoulders. The approaches 5a and 5b are rectangular here on the side facing away from the fuel injector. It can clearly be seen that the point with the shoulders 5a and 5b is not wider than the original diameter d _{0 of} the fuel injector. The distance d ₅ must be at least as large as the material thickness d _{4 of} the forks 2a and 2b.

In Figure 3a, the fastening device according to the invention shown in Figure 2 can be seen in supervision and in the unassembled state. The clamping claw 2 is shown completely in this figure, as is its fastening screw 3. The fuel injector 1 has a diameter d ₁ at the point provided with projections 5a and 5b, which is at most as large as the distance d _{2 of} the two forks 2a and 2b of the claws from each other. The point with the shoulders 5a and 5b has a width l ₁ which is at most as large as the original diameter d _{0 of} the fuel injector. The width l ₁ is preferably less than or equal to the length of the forks l ₂ . In addition, the shoulders 5a and 5b are preferably each as wide as the width d _{3 of} the forks 2a and 2b, so that d ₁ + d ₃ = l ₁ .

3b shows a further fastening device according to the invention for securing a fuel injector 1 with a clamping claw 2, which has two forks 2a and 2b and is fastened to the cylinder head via a fastening screw 3. The illustration shows the fastening device in the top view and the fuel injector in the unmounted state. The approaches 5a and 5b are adapted to the dimensions of the clamping claw at its lowest point 8. The shaft of the fuel injector has a diameter d ₁ at the point with the shoulders. It is here r ₁ ≤ r _2, wherein r ₁ = l _1/2 and r _{2 is} the length of the forks 2a and 2b from the deepest point 8 of the clamping claw to d to the center of the tapered with the diameter Kraftstoffinjektorschafts _1. Here, just as for the embodiment variant according to FIG. 3a, d ₁ ≤ the distance d _{2 of} the two forks 2a and 2b from one another, and l ₁ ≤ the original diameter d _{0 of} the fuel injector, and preferably l ₁ = d ₁ + d ₃ is where d ₃ = the width of the forks 2a and 2b.

FIG. 4 shows a fuel injector 1 which is fastened by a fastening device according to the invention is secured. The fuel injector 1 lies over a cylindrical sealing surface 10 on the undivided valve cover 4. The internal combustion engine is designated 11 here. Part 1a of the fuel injector with the connector for the high-pressure manifold (Common Rail) is outside the camshaft space. The lower part of the In the assembled state shown, the fuel injector is inserted into the receiving bore 13 of the cylinder head 12 pressed. The fastening screw for the clamping claw is in the cylinder head 12 attached (not shown). When dismantling the fuel injector after loosening the fixing screw of the clamping claw and turning the fuel injector simply pull the fuel injector through 90 ° through the valve cover 4.

FIG. 4a shows a section of a fastening device according to the invention in the assembled state. A fork 2a of the clamping claw lies on one of the lugs 5a attached to the shaft 7 of the fuel injector. The fork 2a of the clamping claw is rounded and has a small distance r ₃ from the shaft of the fuel injector. r ₃ is in the range of tenths of a mm.

LIST OF REFERENCE NUMBERS

1

fuel injector

1a

Part of the fuel injector with the connector for the high-pressure manifold (Common rail)

2

Sparin claw (bracket)

2a, 2b

Forks of the clamp

3

fixing screw

4

valve cover

5a, 5b

approaches

6

injection

7

Fuel injector stem

8th

lowest point of the clamp

9

traverse

10

sealing surface

11

Internal combustion engine

12

cylinder head

13

Location hole for the fuel injector in the cylinder head

d ₀

original or maximum diameter of the fuel injector

d ₁

Diameter of the tapered shaft of the fuel injector

d ₂

Distance between the two forks of the clamping claw

d ₃

Width of the forks of the clamping claw

d ₄

Material thickness of the forks of the clamping claw

d ₅

Distance of the lugs from the part of the injector with the diameter d ₀

l ₁

Width of the shaft of the fuel injector at the point with the opposite one approaches

l ₂

Length of the forks of the clamping claw

r ₁

l _1/2

r ₂

the length of the forks 2a and 2b from the lowest point 8 of the clamping claw to the center of the tapered fuel injector shaft with the diameter d ₁

r ₃

Distance between the forks of the clamping claw and the shaft of the fuel injector in assembled condition

Claims (9)

Device for fastening a fuel injector (1) in the cylinder head (12) of an internal combustion engine, comprising a fuel injector (1) with a diameter d ₀ and a fastening screw (3) screwed into the cylinder head (12), as well as a fork-shaped clamp (2) penetrated by this fastening screw ) with two forks (2a, 2b) of length l ₂ and distance d ₂ , characterized in that the shaft (7) of the fuel injector (1) tapers towards a diameter d ₁ in the direction of the injection nozzle (6), and the tapered shaft is provided at one point with mutually opposite lugs (5a, 5b), the width l _{1 of} this point not exceeding the original diameter d _{0 of} the fuel injector. Apparatus according to claim 1, characterized in that the clamping claw is supported at its one free end on a support surface on the cylinder head and, in the assembled state of the fuel injector, rests at its other free fork-shaped end on the attachments attached to the shaft of the fuel injector, and the fuel injector in presses a receiving bore (13) of the cylinder head (12). Apparatus according to claim 1 or 2, characterized in that the lugs (5a, 5b) are rectangular on the side facing away from the fuel injector (1). Apparatus according to claim 1 or 2, characterized in that the lugs (5a, 5b) on the side facing away from the fuel injector (1) are adapted to the dimensions of the clamping claw at their lowest point (8), and optionally r ₁ , half the width l ₁ , less than or equal to the length r _{2 of} the forks 2a and 2b from the lowest point 8 of the clamping claw to the center of the tapered fuel injector shaft with the diameter d ₁ . Device according to one of the preceding claims, characterized in that the point with the shoulders (5a, 5b) is at a distance d ₅ from the part (1a) of the fuel injector with the diameter d ₀ , and the forks (2a, 2b) the clamping claw have a material thickness d ₄ . Apparatus according to claim 5, characterized in that the distance d _{5 is} greater than or equal to the material thickness d _{4 of} the forks of the clamping claw. Device according to one of the preceding claims, characterized in that the shoulders (5a, 5b) are as wide as the forks (2a, 2b). Device according to one of the preceding claims, characterized in that the length l _{2 of} the forks (2a, 2b) is greater than or equal to the width l _{1 of} the point with the shoulders (5a, 5b). Device according to one of the preceding claims, characterized in that a cylindrical sealing surface (10) is attached to the shaft of the fuel injector above the clamping claw (2).

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