EP1047872A1

EP1047872A1 - Fuel injection system

Info

Publication number: EP1047872A1
Application number: EP99950453A
Authority: EP
Inventors: Karl Gmelin; Jochen Staiger; Andreas Bretschneider; Thomas Fuerst
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-11-18
Filing date: 1999-07-29
Publication date: 2000-11-02
Anticipated expiration: 2019-07-29
Also published as: EP1047872B1; JP2002530569A; US6318341B1; DE19853090A1; RU2226616C2; KR20010034178A; DE59910742D1; WO2000029743A1; CZ293799B6; CZ20002625A3

Abstract

The invention relates to a fuel injection system (1) for directly injecting fuel into combustion chambers (2) of an internal combustion engine. Said fuel injection system (1) has at least one fuel injection valve (4) for every combustion chamber (2) of the internal combustion engine. Said fuel injection valve can be inserted in a respective bore (16) formed on the cylinder head (3) of the internal combustion engine. Said fuel injection valve is arranged at an injection section (15) and has a fuel inlet opening (11). The fuel injection system is further provided with a fuel distributor (5) which has a fuel outlet opening (8) assigned to every fuel injection valve (4) which can be connected to the fuel inlet opening (11) of the fuel injection valve (4) and which can be fixed to the cylinder head (3) by fixing means (20) assigned to every fuel injection valve (4). A holding down device (30) is assigned to every fuel injection valve (4) and holds the fuel injection valve (4) down in the assigned bores (16) of the cylinder head. Every holding-down device (30) is connected to the assigned fixing means (20). Every fixing means (20) has a first fixture (23) for fixing the fuel distributor (5) to the cylinder head (3) and a second fixture (37) for impinging the assigned fuel injection valve (4) with a holding-down force.

Description

Fuel injection system

State of the art

The invention relates to a fuel injection system for the direct injection of fuel 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 preamble of claim 1. It is already known from JP-OS 08-312503 to provide receiving bores on the cylinder head of an internal combustion engine, each for a fuel injection valve, into each of which an injection section of the fuel injection valve is inserted . The fuel injector is held down by means of a hold-down device designed as a clamping claw against the relatively high combustion pressure prevailing in the combustion chamber. A fuel distributor line, which connects the fuel injectors to a fuel pump, is used for supplying the fuel to the fuel inlet openings provided on the fuel injectors. The fuel rail has a fuel outlet for each fuel injector. In order to obtain the necessary seal, a sealing element in the form of an O-ring is provided in each case.

In this known type of assembly, however, it is disadvantageous that the fuel injection valves have to be mounted individually on the cylinder head, which requires considerable assembly effort with multiple operations required. A preliminary inspection of the fuel injection system, e.g. B. tightness is not possible. Fully automated production is made difficult by the large number of work steps.

Another disadvantage is that the fastening of the fuel distributor line and the holding down of the fuel injection valves in the associated receiving bores of the cylinder head are carried out by separate, separate elements. The fuel injectors must therefore be preassembled in the mounting holes before the fuel distributor line can be attached and attached to the cylinder head. The degree of integration of this known type of assembly is therefore relatively low and the procedure is cumbersome.

From DE-OS 29 08 095 it is known to fix a fuel injector which is not intended for the direct injection of fuel to a fuel distributor line by means of a retaining bracket and to introduce the inlet section of the fuel injector into the fuel distributor line via a plug nipple. However, a hold-down force that withstands the combustion pressure of the internal combustion engine cannot be transmitted to the fuel injectors via the retaining bracket, so that this type of assembly is unsuitable for fuel injectors for direct injection of fuel into the combustion chamber of an internal combustion engine.

From EP-PS 0 491 582 it is known in principle to pre-assemble fuel injection valves on a fuel distributor line before insertion into the receiving openings. However, this known fuel injection system is also not suitable for injecting fuel directly into the combustion chamber of an internal combustion engine, but rather for injecting fuel indirectly into the intake manifold of the internal combustion engine. The holding elements are also not suitable for transmitting a sufficient hold-down force that can withstand the combustion pressure of the internal combustion engine. so that this type of assembly is unsuitable for a fuel injection system for the direct injection of fuel into the combustion chamber of an internal combustion engine.

Advantages of the invention

The fuel injection system according to the invention with the characterizing features of claim 1 has the advantage that the functions of fastening the fuel distributor line and holding down the fuel injection valves in the associated receiving bores of the cylinder head are integrated with one another in the corresponding fastening devices. After fastening the fuel distributor line by tightening the first clamping elements of the fastening devices, a hold-down force which can be predetermined by means of the second clamping elements can be transmitted to the fuel injection valves via the hold-down devices connected to the fastening devices, so that the fuel injection valves are held down in the receiving bores against the combustion pressure of the internal combustion engine become.

Another important advantage is that the fuel injection valves can be preassembled on the fuel distributor line together with their hold-down devices and the fuel injection system can be supplied to the manufacturer of the internal combustion engine as a complete system. The fuel injection system can already be checked in the factory of the manufacturer of the fuel injection system to ensure that it functions properly, in particular that it is properly sealed. This preliminary check ensures that the manufacturer of the internal combustion engine is only supplied with fuel injection systems that work properly and that the reliability of the fuel injection systems is thus improved overall.

The pre-assembled fuel injection system can be installed in the factory of the engine manufacturer without major assembly expenditure on the internal combustion engine, for. B. can be quickly assembled by means of a fully automated manufacturing system. For this purpose, only the fuel injection valves are to be inserted into the mounting holes provided on the cylinder head of the internal combustion engine, and the fuel distributor line is to be fastened to the cylinder head by tightening the first clamping elements of the fastening devices. A sufficient hold-down force is then transferred to the fuel injection valves by tightening the second clamping elements of the fastening device so that they withstand the combustion pressure of the internal combustion engine.

Advantageous further developments and improvements of the fuel injection system specified in claim 1 are possible through the measures listed in the subclaims.

A support sleeve is advantageously arranged between a fastening section of the fuel distributor line and the cylinder head, wherein the first clamping element, which is preferably designed as a threaded screw, penetrates the fastening section of the fuel distributor line and the support sleeve and can be screwed into an associated threaded bore of the cylinder head. The hold-down device advantageously has an engagement section which engages the associated fuel injection valve, a guide section which at least partially surrounds the support sleeve, the associated fastening section of the fuel distributor line and the first tensioning element, and a connecting section which connects the engagement section and the guide section. The second clamping element is advantageously designed as a threaded nut that can be screwed onto a screw head of the first clamping element and engages on the guide section of the hold-down device. This construction creates an integration of the fastening device with the hold-down device. The hold-down device preferably has a radially inwardly projecting collar which can be inserted into a groove of the associated fuel injector. This makes it possible to exert not only a hold-down force acting in the direction of the combustion chamber but also a force acting in the opposite direction on the associated fuel injector. This is particularly advantageous when dismantling the fuel injection system, since the fuel injection valves can then be pulled out of the receiving bores of the cylinder head with the hold-down device. Furthermore, it is achieved in the preassembled state of the fuel injection system that the fuel injection valves are locked on the hold-down devices and the fastening devices on the fuel distribution line and cannot detach from the preassembled fuel injection system.

A tubular intermediate piece is advantageously arranged between each fuel outlet opening of the fuel distributor line and the associated fuel inlet opening of the fuel injection valve. The tubular intermediate piece allows position and angle compensation within certain limits. As a result, the dimensional accuracy of both the receiving bores for the fuel injection valves on the cylinder head and the dimensional accuracy of the fuel outlet openings on the fuel distributor line are subject to less stringent requirements.

drawing

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

1 shows a partial longitudinal section through an exemplary embodiment of a fuel injection system according to the invention; FIG. 2 shows a top view of the exemplary embodiment of a fuel injection system according to the invention shown in extracts in FIG. 1;

Fig. 3 shows a cross section along the line III-III in Fig. 2 and

FIG. 4 shows a cross section along the line IV-IV in FIG. 2.

Description of the embodiment

Fig. 1 shows an embodiment of the fuel injection system according to the invention, which is generally designated by the reference numeral 1, in a partial cross section. The fuel injection system 1 is used to inject fuel directly into the combustion chambers of the internal combustion engine. A combustion chamber 2 of the internal combustion engine is indicated in FIG. 1. The combustion chambers of the internal combustion engine are closed by a cylinder head 3 shown in extracts. At least one fuel injection valve 4 is assigned to each combustion chamber 2 of the internal combustion engine. The fuel injection valves 4 are connected to a fuel pump via a fuel distributor line 5.

The fuel distributor line 5, shown partially in section in FIG. 1, is tubular and has a fuel channel 6 inside, which can be connected to a fuel line (not shown) via a connecting flange 7. For each fuel injection valve 4, the fuel distributor line 5 has a fuel outlet opening 8, which is surrounded by a cup-like receptacle 9. In the exemplary embodiment, fuel inlet openings 11 of the fuel injection valves 4 are connected via a tubular intermediate piece 10 to the associated fuel outlet opening 8 of the fuel distributor line 5, so that the fuel from the fuel channel 6 via the associated fuel outlet opening 8 and the tubular intermediate piece 10 to the corresponding firing material inlet opening 11 of the associated fuel injector 4 can flow.

The intermediate piece 10 can be inserted into the cup-like receptacle 9 of the fuel distributor line 5 at an inlet-side section 12 and surrounds an inlet section of the associated fuel injector 4 at an outlet-side section 13. The intermediate piece 10 is connected to the receptacle 9 of the fuel distributor line via suitable seals 5 and also sealed off from the inlet section 14 of the fuel injection valve 4. The intermediate piece 10 has the purpose of compensating for possible position and angle deviations of the fuel injection valves 4 with respect to the fuel outlet openings 8 or the receptacles 9 on the fuel distributor line 5.

The fuel injectors 4 are inserted at a spray section 15 into a receiving bore 16 of the cylinder head 3, which is designed as a stepped bore, so that when they are actuated, the fuel injectors 4 inject fuel directly into the associated combustion chamber 2 of the internal combustion engine.

Deviations in the positional accuracy of the locating bores 16 in the cylinder head 3, on the one hand, and the receptacles 9, or the fuel outlet openings 8 on the fuel distributor line 5, on the other hand, are reliably compensated for in production terms by the intermediate piece 10. At the same time, the intermediate piece 10 also compensates for angular deviations that the inlet section 14 of the fuel injection valves 4 has in a certain tolerance range with respect to the longitudinal axis 17 due to manufacturing inaccuracies.

A plurality of fuel injection valves 4 are arranged offset from one another along the fuel distributor line 5, with at least one fuel injection valve 4 being assigned to each combustion chamber 2 of the internal combustion engine. As better from Fig. 2, which is a partial supervision of the in Fig. 1st shows, shown embodiment of the fuel injection system according to the invention, each fuel injector 4 is assigned a fastening device 20, via which the fuel rail 5 is attached to the cylinder head 3. 1 shows a section along the line II in FIG. 2. The section line II is guided in such a way that in FIG. 1 the fastening device 20 in the left area, in the right area the fuel distributor line 5 and the intermediate piece 10 are shown in section .

Fastening sections 21 are formed on the fuel distributor line 5, each of which is assigned to a fastening device 20 or a fuel injection valve 4. The fastening sections 21 each have a bore 22, each of which is penetrated by a first clamping element 23 designed as a threaded screw in the exemplary embodiment. The first clamping elements 23, which are designed as threaded screws in the exemplary embodiment, can each be screwed into an associated threaded bore 24 in the cylinder head 3. Between the respective fastening section 21 of the fuel distributor line 5 and the cylinder head 3 there is in each case a support sleeve 25, which is likewise penetrated by the first tensioning element 23 designed as a threaded screw in the assembled state. The first clamping element designed as a threaded screw

23 has a screw head 26 which engages the associated fastening section 21 of the fuel distributor line 5 in such a way that the fastening section 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 has an extension 27 in which, for example, a hexagonal recess 28 is provided, on which a suitable tool for clamping the first clamping element 23 can engage.

To ensure that the fuel injection valves 4 in the receiving holes 16 against the prevailing 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 30 are provided for each fuel injection valve. The hold-down devices 30 consist of an engagement section 31 engaging on the associated fuel injection valve 4 and at least partially enclosing it in the exemplary embodiment, a guide section 32 provided on the fastening device 20 and a connecting section 33 connecting the engagement section 31 to the guide section 32. The engagement section 31 In the exemplary embodiment has a collar 34 which can be inserted or inserted into a groove 35 of the fuel injection valve 4. The hold-down device 30 can not only exert a hold-down force acting on the fuel injection valve 4 in the direction of the combustion chamber 2 of the internal combustion engine via the collar 34 of the engagement section 31. Rather, a force can also be transmitted to the fuel injection valve 4 in the opposite direction, so that when the fuel injection system 1 is disassembled, the fuel injection valves 4 connected to the fuel distributor line 5 via the hold-down device 30 and the fastening device 20 are readily pulled out of the associated receiving bores 16 can. This considerably simplifies the dismantling of the fuel injection system 1.

The guide section 32 of the hold-down devices 30 at least partially surrounds both the support sleeve 25 and the fastening section 21 and the screw head 26 of the first clamping element 23. A second clamping element 37 designed in the form of a threaded nut in the exemplary embodiment can therefore act on the upper end face 36 of the guide section 32. The second clamping element 37 can be screwed onto the extension 27 of the screw head 26 and can therefore be clamped independently of the first clamping element 23 designed as a threaded screw. The fuel injection system 1 can be preassembled on the cylinder head 3 of the internal combustion engine before the actual final assembly. First, a fuel injector 4 is inserted into an associated hold-down device 30 and an intermediate piece 10 is placed on each fuel injector 4. The first tensioning elements 23, which are designed as threaded screws, are each inserted into the bore 22 of the fastening sections 21 of the fuel distributor line 5 and also passed through the support sleeves 25. Finally, the guide sections 32 are pushed over the support sleeves 25 and the fastening sections 21, the intermediate pieces 10 being simultaneously inserted into the associated receptacles 9 of the fuel distribution line 5. In order to prevent the guide section 32 from slipping out of the sleeve 25, a nut can be screwed onto the end of the first clamping element 23 opposite the screw head 26, which nut is removed again before the final assembly. The fuel injection valves 4 are secured on the collar 34 of the holding-down device 30 against slipping out of the intermediate piece 10 or out of the receptacle 9 of the fuel distributor line 5. The fuel injection system 1 preassembled in this way can already be checked in the factory of the manufacturer of the fuel injection system 1 for its functionality, in particular its tightness, before it is delivered to the manufacturer of the internal combustion engine.

In the factory of the manufacturer of the internal combustion engine, the fuel injection system 1 is then assembled in a simple manner and with extremely little assembly effort by screwing the first clamping elements 23, which are designed as threaded screws, into the threaded holes 24 provided on the threaded head 3 and by means of a tool acting on the recess 28 tightened or tightened. The second pre-assembled, designed as a threaded nut second clamping elements 37 are subsequently clamped by a tool, for example, engaging in the circumference, whereby the fuel injection valves 4 over The hold-down devices 30, on the guide sections 32 of which the second clamping elements 37 engage, are subjected to a sufficient hold-down force so that the fuel injection valves 4 withstand the combustion pressure prevailing in the combustion chambers 2 when the internal combustion engine is operating. This extremely simple final assembly can also be carried out without difficulty by means of fully automated production, as a result of which the production costs are considerably reduced.

For a better understanding of the invention, FIG. 3 shows an excerpted cross section along the line III-III in FIG. 2 and in FIG. 4 an excerpted cross section along the line IV-IV in FIG. 2, elements already described with matching reference numerals are provided.

3, in particular, the guide section 32 of the holding-down device 30 and the second clamping element 37 engaging on the upper end face 36 of the guide section 32 of the holding-down device 30 can be clearly seen. It can also be seen that the fastening device 20 and the associated fuel injection valve 4 are offset not only in the longitudinal direction but also in the transverse direction, so that the connecting section 33 of the hold-down devices 30 runs diagonally in each case.

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

Claims

Expectations

1. Fuel injection system (1) for injecting fuel directly into at least one combustion chamber (2) of an internal combustion engine with at least one fuel injection valve (4) for each combustion chamber (2), each of which is arranged on an injection section (15) in an associated one on a cylinder head ( 3) of the internal combustion engine designed receiving bore (16) can be used and has a fuel inlet opening (11), a fuel distributor line (5) which for each fuel injection valve (4) with the fuel inlet opening (11) of the fuel injection valve (4) Connectable fuel outlet opening (8) and can be fastened to the cylinder head (3) by means of a fastening device (20), and a hold-down device (30) assigned to each fuel injection valve (4) for holding down the fuel injector (4) in the associated receiving bore ( 16) of the cylinder head (3), characterized in that each fuel injection valve (4) each An attachment device (20) is assigned and each hold-down device (30) is connected to the associated attachment device (20), each attachment device (20) having a first clamping element (23) for attaching the fuel distributor line (5) to the cylinder head (3) and a second clamping element (37) for loading the assigned fuel injector (4) with a hold-down force.

2. Fuel injection system according to claim 1, characterized in that on the fuel distributor line (5) each fastening device (20) associated fastening section (21) is formed, on which the first clamping element (23) engages.

3. Fuel injection system according to claim 2, characterized in that a support sleeve (25) is arranged between each fastening section (21) and the cylinder head (3).

4. Fuel injection system according to claim 3, characterized in that each hold-down device (30) engages on the associated fuel injection valve (4) engaging portion (31), one of the support sleeve (25), the associated fastening portion (21) of the fuel distribution line (5) and the first clamping element (23) has at least partially surrounding guide section (32) and a connecting section (33) connecting the engagement section (31) to the guide section (32).

5. Fuel injection system according to claim 4, characterized in that the second clamping element (37) is arranged concentrically to the first clamping element (23) and engages on the guide section (32) of the associated hold-down device (30).

6. Fuel injection system according to claim 4 or 5, characterized in that the first clamping element (23) is a threaded screw which the associated fastening section (21) of the fuel distributor line (5) and the associated support sleeve (25) penetrates and can be screwed into an associated threaded bore (24) of the cylinder head (3).

7. Fuel injection system according to claim 6, characterized in that the second clamping element (37) is a threaded nut which can be screwed onto a screw head (26) of the first clamping element (23).

8. Fuel injection system according to one of claims 4 to 7, characterized in that the engagement section (31) of each hold-down device (30) on the associated fuel injection valve (4) engages so that the fuel injection valve (4) with both in the direction of the combustion chamber ( 2) the holding-down force acting on the internal combustion engine can also be acted upon by a force acting in the opposite direction.

9. Fuel injection system according to claim 8, characterized in that the engagement section (31) of each hold-down device (30) has a radially inwardly projecting collar (34) which can be inserted into a groove (35) of the associated fuel injection valve (4).

10. Fuel injection system according to one of claims 1 to 9, characterized in that between each fuel outlet opening (8) of the fuel distribution line (5) and the fuel inlet opening (11) of the associated fuel injection valve (4), a tubular intermediate piece (10) is arranged.