EP1047872B1 - Fuel injection system - Google Patents

Description

State of the art

The invention relates to a fuel injection system for injecting fuel directly into the combustion chamber or the combustion chambers of an internal combustion engine.

The invention is based on a fuel injection system according to the genus of claim 1. It is already from the JP-OS 08-312503 known on the cylinder head of an internal combustion engine Receiving holes for one fuel injector each to provide, in each of which a spray section of the fuel injector is used. The Fuel injector is used by means of a clamp trained hold-down device against that in the combustion chamber prevailing relatively high combustion pressure held down. For the supply of fuel to the the fuel injection ports provided in the fuel injectors serves a fuel rail that the fuel injectors with a fuel pump combines. The fuel rail line points for each Fuel injection valve has a fuel outlet opening. To get the necessary seal, there is one Sealing element provided in the form of an O-ring.

In this known type of assembly, however, it is disadvantageous that the fuel injectors individually on the cylinder head need to be assembled, which requires considerable assembly effort with multiple operations required. A preliminary check of the Fuel injection system, e.g. B. on tightness is not possible. A fully automatic production is by the Variety of operations difficult.

Another disadvantage is that the attachment of the fuel rail and holding down the fuel injectors in the corresponding mounting holes of the Cylinder head through separate, separate elements he follows. The fuel injectors must therefore be pre-assembled in the mounting holes before put the fuel rail on and on the cylinder head can be attached. The degree of integration of this known type of assembly is therefore relatively small and Procedure is cumbersome.

From DE-OS 29 08 095 it is known not to Direct injection of fuel provided fuel injector on a fuel distribution line by means of a bracket to fix and the inlet section of the Fuel injector via a plug into the Introduce fuel distribution line. One that Withstanding the combustion pressure of the internal combustion engine However, hold-down force cannot be exerted via the holding bracket the fuel injectors are transmitted so that this type of assembly for fuel injectors for direct Injecting fuel into the combustion chamber of an internal combustion engine is unsuitable.

From EP-PS 0 491 582 it is known in principle fuel injectors on a fuel distribution line to be pre-assembled before inserting into the openings. However, this known fuel injection system is also not for injecting fuel directly into the Combustion chamber of an internal combustion engine but for the indirect one Injecting fuel into the intake manifold of the internal combustion engine suitable. The holding elements are also suitable not to transmit sufficient hold-down force, that withstands the combustion pressure of the internal combustion engine, so that this type of assembly for a fuel injection system for injecting fuel directly into the combustion chamber an internal combustion engine is unsuitable.

There are already several from the unpublished EP 0 945 611 A2 Design variants of fuel injection systems known. It is about around fuel injection systems for injecting fuel directly into at least a combustion chamber of an internal combustion engine. One for each combustion chamber Fuel injector is held in a receiving bore in the cylinder head. On the inlet side is the fuel injector with an inlet connection of a fuel distribution line connected. For fastening and fixing the fuel distribution line opposite the cylinder head and to hold down the Fuel injector are in the mounting hole of the cylinder head Fastening devices provided in the form of one or two screws. The The fuel distributor line is attached via at least one Connection bracket, which by tightening the screw, the fuel rail fixed to the cylinder head. The fuel injector is held down also by tightening the same screw or by a separate screw and Power transmission to the fuel injector via a claw-like attack Leaf spring.

Advantages of the invention

The fuel injection system according to the invention with the characteristic features of claim 1 has in contrast the advantage that the functions of fastening the fuel rail and holding down the fuel injectors in the associated mounting holes of the Cylinder head with each other in the corresponding Fastening devices are integrated. After this Fasten the fuel rail by tightening it of the first clamping elements of the fastening devices via those connected to the fasteners Hold-down devices on the fuel injectors a specifiable by means of the second clamping elements Hold-down force is transmitted so that the fuel injectors in the mounting holes against the Combustion pressure of the internal combustion engine is kept down become.

Another major advantage is that the Fuel injectors on the fuel rail pre-assembled together with their hold-down devices can be and the fuel injection system as Complete system to the manufacturer of the internal combustion engine is available. The fuel injection system already in the factory of the manufacturer of the fuel injection system perfect function, especially perfect Tightness, pre-checked. become. Through this preliminary check it is ensured that the manufacturer of the internal combustion engine only properly working fuel injection systems are delivered and thus the reliability of the Fuel injection systems are improved overall.

The pre-assembled fuel injection system can be in the factory of the Manufacturer of the internal combustion engine without major assembly effort on the internal combustion engine, e.g. B. by means of a fully automatic working manufacturing plant, quickly assembled become. All that is required is the fuel injection valves in the on the cylinder head of the internal combustion engine the intended mounting holes and the fuel distribution line is through with the cylinder head Tightening the first clamping elements of the fastening devices to fix. Then the fuel injectors by tightening the second clamping elements the fastening device has a sufficient hold-down force transferred so that the combustion pressure of the Withstand the internal combustion engine.

By the measures listed in the subclaims advantageous developments and improvements in Claim 1 specified fuel injection system possible.

It is advantageous between a fastening section Fuel distribution line and the cylinder head a support sleeve arranged, preferably as a threaded screw trained first clamping element the fastening section the fuel rail and the support sleeve penetrates and into an associated threaded hole of the Cylinder head can be screwed in. The hold-down device advantageously has one on the associated fuel injector attacking section of attack, a die Support sleeve, the associated mounting portion of the Fuel distribution line and the first tensioning element at least partially surrounding guide section and a connecting the attack section and the guide section Connection section on. The second clamping element advantageously designed as a threaded nut on a Screw head of the first clamping element can be screwed on and on the guide section of the hold-down device attacks. This structure enables integration of the Fastening device with the hold-down device created.

The hold-down device preferably has a radial inwardly projecting collar which is assigned to a groove in the Fuel injector can be used. This is it is possible on the associated fuel injector not just one directed towards the combustion chamber Hold-down force, but also one in the opposite direction to exert force. This is particularly the case with Disassembly of the fuel injection system advantageous because the Fuel injectors then with the hold-down device from the mounting holes in the cylinder head can be pulled out. Furthermore, the pre-assembled Condition of the fuel injection system reached that Fuel injectors via the hold-down devices and the fasteners on the fuel rail are locked and not detached from the can solve pre-assembled fuel injection system.

There is advantageously between each fuel outlet opening the fuel rail and the associated one Fuel inlet opening of the fuel injector each arranged a tubular intermediate piece. The tubular Intermediate piece allows one within certain limits Position and angle compensation. This affects the dimensional accuracy both the location holes for the fuel injectors on the cylinder head as well as on the Dimensional accuracy of the fuel outlet openings on the fuel distribution line to make less demands.

drawing

Fig. 1

einen auszugsweisen Längsschnitt durch ein Ausführungsbeispiel einer erfindungsgemäßen Brennscoffeinspritzanlage;

Fig. 2

eine Aufsicht auf das in Fig. 1 auszugsweise dargestellte Ausführungsbeispiel einer erfindungsgemäßen Brennstoffeinspritzanlage;

Fig. 3

einen Querschnitt entlang der Linie III-III in Fig. 2 und

Fig. 4

einen Querschnitt entlang der Linie IV-IV in Fig. 2.

An embodiment of the invention is shown in simplified form in the drawing and explained in more detail in the following description. Show it:

Fig. 1

an excerpt longitudinal section through an embodiment of a Brennscoffein injection system according to the invention;

Fig. 2

a plan view of the exemplary embodiment of a fuel injection system according to the invention shown in part in FIG. 1;

Fig. 3

a cross section along the line III-III in Fig. 2 and

Fig. 4

a cross section along the line IV-IV in Fig. 2nd

Description of the embodiment

Fig. 1 shows an embodiment of the invention Fuel injection system, generally with the Reference numeral 1 is designated, in a partial cross section. The fuel injection system 1 is used for direct Injecting fuel into the combustion chambers of the internal combustion engine. A combustion chamber 2 of the internal combustion engine is shown in Fig. 1 indicated. The combustion chambers of the internal combustion engine are by means of a cylinder head 3 shown in extracts locked. Each combustion chamber 2 is the internal combustion engine assigned at least one fuel injector 4. The Fuel injectors 4 are via a fuel rail 5 connected to a fuel pump.

The fuel distribution line shown partially in section in Fig. 1 5 is tubular and has in the Inside a fuel channel 6 on one Connecting flange 7 with a fuel line, not shown is connectable. For every fuel injector 4, the fuel rail 5 has a fuel outlet opening 8 on that of a cup-like Recording 9 is surrounded. Fuel inlet ports 11 of the Fuel injection valves 4 are in the exemplary embodiment via a tubular intermediate piece 10 with the associated Fuel outlet opening 8 of the fuel distribution line 5 connected so that the fuel from the fuel channel 6 via the associated fuel outlet opening 8 and that tubular intermediate piece 10 to the corresponding fuel inlet opening 11 of the associated fuel injector 4 can flow.

The intermediate piece 10 is on an inlet-side section 12 in the cup-like receptacle 9 of the fuel distribution line 5 can be used and surrounds on an outlet side Section 13 an inlet section of the associated fuel injector 4. The intermediate piece 10 is over suitable seals both against the receptacle 9 of the Fuel distribution line 5 as well as opposite the inlet section 14 of the fuel injector 4 sealed. The intermediate piece 10 has the purpose of possible position and Angular deviations of the fuel injection valves 4 in relation on the fuel outlet openings 8 and the receptacles 9 the fuel distribution line 5 to compensate.

The fuel injection valves 4 are at an injection section 15 in each one designed as a stepped bore Receiving bore 16 of the cylinder head 3 inserted so that the fuel injectors 4 fuel when actuated directly into the associated combustion chamber 2 of the internal combustion engine inject.

Deviations in the production technology that are unavoidable Position accuracy of the receiving bores 16 in the cylinder head 3 on the one hand and the receptacles 9 and the fuel outlet openings 8 on the fuel distribution line 5 on the other hand, are made reliable by the intermediate piece 10 balanced. At the same time, the intermediate piece 10 is also the same Angle deviations from the inlet section 14 of the Fuel injection valves 4 with respect to the longitudinal axis 17 due to manufacturing inaccuracies in some Has tolerance range.

There are several along the fuel distribution line 5 Fuel injection valves 4 arranged offset to one another, each combustion chamber 2 of the internal combustion engine at least one Fuel injector 4 is assigned. How better out FIG. 2, which is a partial supervision of the one in FIG. 1 illustrated embodiment of the invention Fuel injection system shows, everyone can see Fuel injection valve 4, a fastening device 20 assigned via which the fuel distribution line 5 is each attached to the cylinder head 3. It shows Fig. 1 shows a section along the line I-I in Fig. 2. Die Section line I-I is such that in Fig. 1 in the left Area the fastening device 20, in the right area the fuel rail 5 and the intermediate piece 10 are shown in section.

Fastening sections are on the fuel distributor line 5 21 integrally formed, each a fastening device 20 or a fuel injector 4 assigned. The attachment portions 21 each have a bore 22, each of one in the embodiment formed as a threaded screw first clamping element 23 are permeated. The in the embodiment as Threaded screw formed first clamping elements 23 each in an associated threaded bore 24 in the cylinder head 3 screwable. Between the respective fastening section 21 of the fuel distribution line 5 and there is a support sleeve 25 to the cylinder head 3, which is also designed as a threaded screw penetrated first clamping element 23 in the assembled state is. The first clamping element designed as a threaded screw 23 has a screw head 26, which on the associated Fastening section 21 of the fuel rail 5 engages so that the mounting portion 21 and the support sleeve 25 between the screw head 26 and the cylinder head 3 are clamped in the assembled state. The Screw head 26 of the first clamping element 23 an extension 27 in which, for example, a hexagonal recess 28 is provided on which a suitable tool can attack for tightening the first clamping element 23.

To ensure that the fuel injectors 4 in the receiving bores 16 against the in the combustion chamber 2 of the Internal combustion engine with a combustion pressure sufficient hold-down force are held down 4 hold-down devices for each fuel injector 30 provided. The hold-down devices 30 consist of one on the associated fuel injector 4 attacking and this in the embodiment at least partially enclosing attack section 31, one provided on the fastening device 20 Guide section 32 and an attack section 31 with the connecting portion 32 connecting portion 33. The attack section 31 has in the embodiment a collar 34 that fits into a groove 35 of the fuel injector 4 can be used or inserted. about the collar 34 of the engagement section 31 can hold down 30 not just one towards the Combustion chamber 2 of the internal combustion engine acting down force exert on fuel injector 4. Rather can a force on the fuel injector also in the opposite direction 4 are transmitted so that at Disassembly of the fuel injection system 1 on the Hold-down device 30 and fastening device 20 connected to the fuel rail 5 fuel injectors 4 easily from the associated Receiving holes 16 can be pulled out. This facilitates the disassembly of the fuel injection system 1 considerably.

The guide section 32 of the hold-down devices 30 surrounds both the support sleeve 25 and the Fastening section 21 and the screw head 26 of the first Clamping element 23 at least partially. On the top End face 36 of the guide section 32 can therefore be a Embodiment in the form of a threaded nut attack formed second clamping element 37. The second Clamping element 37 is on the extension 27 of the Screw head 26 can be screwed on and can therefore be used independently from the first designed as a threaded screw Clamping element 23 can be tightened.

The fuel injection system 1 can before the actual Final assembly on the cylinder head 3 of the internal combustion engine be pre-assembled. First, a fuel injector is used 4 in an associated hold-down device 30 used and on each fuel injector 4 an intermediate piece 10 is placed. The as threaded screws trained first clamping elements 23 each in the bore 22 of the mounting portions 21 of the Fuel distribution line 5 introduced and further through the support sleeves 25 passed through. Eventually they will Guide sections 32 via the support sleeves 25 and Fastening sections 21 pushed, while the Intermediate pieces 10 in the associated receptacles 9 of the fuel distribution line 5 will be introduced. To slip out of the guide section 32 from the sleeve 25 can prevent, on the opposite of the screw head 26 End of the first clamping element 23 a nut be screwed on and removed before final assembly becomes. The fuel injection valves 4 are on the collar 34 the holding-down device 30 against slipping out the intermediate piece 10 or from the receptacle 9 of the fuel distribution line 5 secured. That way pre-assembled fuel injection system 1 can already in Factory of the manufacturer of the fuel injection system 1 their functionality, especially their tightness, be checked before being sent to the manufacturer of the Internal combustion engine is delivered.

In the factory of the manufacturer of the internal combustion engine, the Fuel injection system 1 then in a simple manner and with extremely low assembly effort because the first clamping elements 23 designed as threaded screws into the threaded bores 24 provided on the threaded head 3 are screwed in and by means of a recess 28 attacking tool are tightened or clamped. The also pre-assembled as a threaded nut trained second clamping elements 37 are below by a tool that, for example, engages in scope tense, causing the fuel injectors 4 over the hold-down devices 30 on their guide sections 32 attack the second clamping elements 37 with sufficient hold-down force are applied, so that the fuel injectors 4 to the operation of the Internal combustion engine prevailing in the combustion chambers 2 Withstand combustion pressure. This extremely simple Final assembly can also be done using a fully automatic Manufacturing can be done without difficulty, which the manufacturing costs are significantly reduced.

A better understanding of the invention is shown in FIG extract cross-section along the line III-III in Fig. 2 and in Fig. 4 a partial cross-section along the Line IV-IV shown in Fig. 2, wherein already described Provide elements with matching reference symbols are.

In Fig. 3, the guide section 32 are in particular the Hold-down device 30 and that on the upper end face 36 of the guide section 32 of the hold-down device 30 attacking second clamping element 37 clearly visible. Further it can be seen that the fastening device 20 and the associated fuel injector 4 not only in the longitudinal direction but also offset in the transverse direction are so that the connecting portion 33 of the hold-down devices 30 runs diagonally.

4 are the guide section 32 of the hold-down device 30, as well as the support sleeve 25, the first clamping element 23 and the second clamping element 37 each shown in section, the arrangement of these components is clearly visible to one another in the transverse direction.

Claims (10)

1. Fuel injection system (1) for the direct injection of fuel into at least one combustion space (2) of an internal combustion engine, with at least one fuel injection valve (4) for each combustion space (2), which fuel injection valve can in each case be inserted at an injection portion (15) into an assigned receiving bore (16) formed on a cylinder head (3) of the internal combustion engine and has a fuel inlet orifice (11), with a fuel distributor line (5) which has for each fuel injection valve (4) a fuel outlet orifice (8) connectable to the fuel inlet orifice (11) of the fuel injection valve (4) and which can be fastened to the cylinder head (3) by means of a fastening device (20), and with a holding-down device (30), assigned to each fuel injection valve (4), for holding down the fuel injection valve (4) in the assigned receiving bore (16) of the cylinder head (3), characterized in that each fuel injection valve (4) is assigned in each case a fastening device (20), and each holding-down device (30) is connected to the assigned fastening device (20), each fastening device (20) having a first tension element (23) for fastening the fuel distributor line (5) to the cylinder head (3) and a second tension element (37) for acting upon the assigned fuel injection valve (4) with a holding-down force.
2. Fuel injection system according to Claim 1, characterized in that a fastening portion (21) which is assigned to each fastening device (20) and on which the first tension element (23) engages is integrally formed on the fuel distributor line (5).
3. Fuel injection system according to Claim 2, characterized in that a supporting sleeve (25) is arranged in each case between each fastening portion (21) and the cylinder head (3).
4. Fuel injection system according to Claim 3, characterized in that each holding-down device (30) has an engagement portion (31) engaging on the assigned fuel injection valve (4), a guide portion (32) at least partially surrounding the supporting sleeve (25), the assigned fastening portion (21) of the fuel distributor line (5) and the first tension element (23), and a connection portion (33) connecting the engagement portion (31) to the guide portion (32).
5. Fuel injection system according to Claim 4, characterized in that the second tension element (37) is arranged concentrically to the first tension element (23) and engages on the guide portion (32) of the assigned holding-down device (30).
6. Fuel injection system according to Claim 4 or 5, characterized in that the first tension element (23) is a threaded screw which penetrates the assigned fastening portion (21) of the fuel distributor line (5) and the assigned supporting sleeve (25) and which can be screwed into an assigned threaded bore (24) of the cylinder head (3).
7. Fuel injection system according to Claim 6, characterized in that second tension element (37) is a threaded nut which can be screwed onto a screw head (26) of the first tension element (23).
8. Fuel injection system according to one of Claims 4 to 7, characterized in that the engagement portion (31) of each holding-down device (30) engages on the assigned fuel injection valve (4) in such a way that the fuel injection valve (4) can be acted upon both with the holding-down force acting in the direction of the combustion space (2) of the internal combustion engine and with a force acting in the opposite direction.
9. Fuel injection system according to Claim 8, characterized in that the engagement portion (31) of each holding-down device (30) has a radially inward-projecting collar (34) which can be inserted into a groove (35) of the assigned fuel injection valve (4).
10. Fuel injection system according to one of Claims 1 to 9, characterized in that a tubular intermediate piece (10) is arranged between each fuel outlet orifice (8) of the fuel distributor line (5) and the fuel inlet orifice (11) of the assigned fuel injection valve (4).

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