DE102019120742B3 - Fuel rail - Google Patents

Abstract

The invention relates to a fuel distributor 1 which has a pressure accumulator pipe 2 for receiving fuel under pressure. The pressure accumulator tube 2 has a forged base body 6, on which connecting pieces 4, 5 and assembly supports 7 are formed from the same material. According to the invention, the assembly supports 7 have an outwardly open screw clearance 9 extending over their length L.

Description

The invention relates to a fuel distributor according to the features in the preamble of claim 1.

A fuel distributor is part of a fuel supply or a fuel injection system and is used to supply fuel to injection valves of an internal combustion engine. Here, statically compressed fuel is stored in a pressure accumulator tube and distributed to the injectors or injection valves of a cylinder bank.

In the case of fuel distributors with forged pressure accumulator tubes, the base body of the pressure accumulator tube is usually machined by drilling and turning or milling. In particular, the longitudinal bore is usually produced by a deep hole. Connection pieces or injector receptacles and assembly elements, in particular assembly supports between the pressure accumulator tube and the cylinder block, are molded on by forging technology or formed in one piece from the base body using the same material.

Through the EP 2 998 566 A1 includes a prior art fuel distributor with a forged base body and connecting pieces with flange sections that are made of the same material and made in one piece. The flange sections are machined to receive support sleeves.

The EP 3 165 760 A1 discloses a fuel distributor in which the pressure accumulator tube has a forged base body on which nozzle-shaped injector receptacles and mounting supports are formed from the same material and in one piece. The pressure accumulator tube is fixed to the cylinder head of an internal combustion engine via the supports using fastening screws. At their end on the cylinder head side, the supports have a flange section with a passage through which the fastening screw can pass. Above the outwardly closed flange section, the supports have a recess extending in their longitudinal direction.

To produce the recess in the assembly support, it is machined. In order to achieve a close connection to the cylinder head, the assembly support is milled out in the longitudinal direction by cutting and there is free space for the assembly of the fastening screw. The recess is located in the inner area of the support and ends at the flange section, so that a short fastening screw can be used. This solution is advantageously used for inclined adjustment and fastening of fuel distributors to the cylinder head, since the accessibility is improved. Here, however, relocating the screw-on surface down to the cylinder head reduces the flexibility of the fastening screws.

Also the DE 10 2015 120 962 A1 relates to a forged fuel distributor with a tubular base body, at least one inlet formed from the same material and integrally thereon, a plurality of uniformly material and integrally formed thereon injector receptacles and at least one support element formed from the same material and integrally thereon for fastening to a further motor vehicle component. A reinforcing web formed from the same material and formed in one piece extends between the injector receptacles and the at least one support element.

Through the DE 10 2005 029 842 A1 a fuel accumulator of a fuel injection system of a motor vehicle is known. To fasten the fuel accumulator, it has a flange-like fastening section which has a slot or a through opening closed in the circumferential direction for the arrangement of a connecting element.

On the basis of the prior art, the invention is based on the object of showing a forged fuel distributor with connecting pieces and fastening elements, which requires only a small amount of machining after the forging process.

According to the invention, this object is achieved in a fuel distributor according to claim 1.

Advantageous configurations and developments of the invention are the subject matter of the dependent claims.

A forged fuel distributor is proposed which has a pressure accumulator tube for receiving pressurized fuel, the pressure accumulator tube having a forged base body on which connecting pieces and assembly supports are formed from the same material in a forging process. The connecting pieces form injector receptacles. Furthermore, a connecting piece as a fuel inlet can be formed from the same material in one piece on the base body. The assembly supports form fastening elements between the pressure accumulator tube and another motor vehicle component, in particular the cylinder block. The result is a one-piece pressure accumulator tube made of the same material with its connection points.

The mounting supports have a screw clearance that extends over their length and is open to the outside along the longitudinal side. The assembly supports are provided with the screw clearance during the forging process. A screw clearance is designed as an outwardly open recess in a mounting bracket. There is no subsequent machining to produce a hole. The screw clearance is designed to be continuously open from the base body side.

Only a small amount of machining of the pressure accumulator tube produced by forging is necessary. Only the upper and lower flat surfaces on the assembly supports are machined and made flat. In particular, on their top side facing away from the cylinder head, the assembly supports have a planar clamping surface for a screw head of a fastening screw.

In order to achieve advantageous screw clearances without burr formation in the forging process, the recesses in the assembly supports, which form the screw clearances, are widened conically downwards in the direction of the connection to the cylinder head and upwards in the direction of the pressure accumulator tube. Accordingly, the pressure accumulator tube can be removed from the forging tool without burr formation. Each screw clearance has an upper length section and a lower length section, the upper length section widening conically in the direction of the top of the mounting bracket and the lower length section widening conically in the direction of the underside of the mounting bracket.

The cone angle of the conical widening in the upper longitudinal section and / or in the lower longitudinal section is practically between 1 ° and 6 °. A cone angle of 2 ° is particularly preferred.

The screw clearances are tailored. A constriction is formed between the upper length section and the lower length section. The narrow point is the narrowest point in a screw clearance. The conical shape of the recess of the screw clearance upwards and downwards creates a clamping connection for a fastening screw in the parting plane. The bottleneck is located in the upper third of the screw opening in relation to the entire length of a screw opening or the clamping length of an assembly support. The ratio between the length of the upper longitudinal section and the length of the lower longitudinal section is preferably 1: 3 to 1: 8, in particular 1: 6.

The forging-related production of the pressure accumulator tube offers the advantage that the fuel distributor according to the invention can be produced from the same material and in one piece with connecting pieces, in particular injector receptacles, and assembly supports. As a result of the forging process, soldered or welded seams or similar connection points between the individual components, which can represent potential weak points in the component, are avoided. In addition, the number of work steps required for assembly is reduced, which in turn leads to a favorable manufacturing process. The forging process also enables sophisticated component geometries to be realized. In principle, all forging processes can be used. However, a drop forging process is preferably used.

The pressure accumulator tube is forged from a blank. A stainless steel alloy is preferably used as the material. The use of stainless steel alloys of the material type 1.4307 or 1.4301 is particularly suitable.

The pressure accumulator pipe of the fuel rail has a forged tubular base body. A tubular base body is to be understood in the context of the invention as an elongated hollow body which, however, is not set to a round or circular cross-section, neither with regard to the interior nor with regard to the outer circumference. A round inner cross-section is preferred, however, insofar as the interior space is usually generated by a deep hole or blind hole.

The connecting pieces are injector receptacles that are used to connect to the fuel injectors.

A connecting piece for the fuel inlet and a connecting piece-shaped receptacle for mounting a pressure sensor can also be formed in one piece on the pressure accumulator tube of the fuel distributor.

One aspect of the invention provides that a reinforcement strut is formed between an assembly support and a connection piece. The reinforcement strut is also formed from the same material in one piece on the base body and extends between a mounting bracket and a connecting piece, the reinforcing strut merging into the mounting bracket and the connecting piece.

In particular, the reinforcement strut runs diagonally below the base body, that is to say at an angle from a connection piece in the form of an injector receptacle to an assembly support.

The reinforcing strut is particularly preferably arranged between the connecting piece or injector receptacle arranged at an outer end of the pressure accumulator tube and an assembly support.

Two reinforcement struts can also be provided. In this case, one embodiment can provide that two reinforcement struts, starting from a connection piece, each extend up to an assembly support, these assembly supports being on opposite sides of the pressure accumulator tube.

The reinforcement struts are used for stiffening and dimensional stability. In this way, the fuel rail can better withstand deformations caused by alternating bending stresses caused by dynamic and static loads. The reinforcement struts are also made of the same material in one piece on the forged base body. The reinforcement strut minimizes the load path between the force introduction point in a connecting piece or an injector receptacle and the force dissipation point in the assembly support. This leads to a stiffening and thus to a reduction in the deformation of the fuel rail.

The reinforcement struts can also contribute to a weight-optimized design of the fuel rail. The targeted reinforcement in highly stressed component regions can save material in other less stressed regions of the pressure accumulator pipe.

• 1 den Schmiederohling eines erfindungsgemäßen Kraftstoffverteilers in einer perspektivischen Ansicht vor einer spanenden Bearbeitung;
• 2 den Kraftstoffverteiler entsprechend der Darstellung von 1 nach der spanenden Bearbeitung;
• 3 einen Ausschnitt aus einem Anbindungsbereich eines an einem Zylinderblock festgelegten Kraftstoffverteilers mit einer Ansicht auf eine Montagestütze;
• 4 einen Endabschnitt des Druckspeicherrohrs eines Kraftstoffverteilers in einer Ansicht von unten;
• 5 einen Kraftstoffverteiler in einer Seitenansicht;
• 6 die Darstellung entsprechend der 5 in einer Ansicht von oben und
• 7 den Kraftstoffverteiler entsprechend der 5 in einer Stirnansicht.

The invention is described in more detail below using an exemplary embodiment. Show it:

• 1 the forged blank of a fuel distributor according to the invention in a perspective view before machining;
• 2 the fuel rail as shown in 1 after machining;
• 3 a detail from a connection area of a fuel rail attached to a cylinder block with a view of a mounting bracket;
• 4th an end portion of the pressure accumulator tube of a fuel rail in a view from below;
• 5 a fuel rail in a side view;
• 6th the representation according to the 5 in a top view and
• 7th the fuel rail according to the 5 in a front view.

Based on 1 to 4th as well as the 5 to 7th is a fuel rail according to the invention 1 described.

The 1 shows the forged blank of the pressure accumulator tube 2 . The 2 shows the accumulator pipe 2 of the fuel rail 1 after the forging blank has been machined.

The fuel distributor 1 belongs to the accumulator injection system of an internal combustion engine. The pressure generation and fuel injection are decoupled from one another in such accumulator injection systems. A separate high pressure pump continuously generates pressure. This pressure, which is built up independently of the injection sequence, is in the fuel rail 1 permanently available.

The fuel distributor 1 includes an accumulator tube 2 with a fuel inlet on the pump side 3 and several connection pieces 4th , 5 . These form injector connections. The statically compressed fuel is in the pressure accumulator pipe 2 stored and distributed over the injector connections made available to the injectors of a cylinder bank.

The accumulator pipe 2 has a forged tubular body 6th on.

Uniform material forging technology on the base body 6th The connecting pieces are molded on 4th , 5 . For fixing or mounting the fuel distributor 1 on a cylinder head of a motor vehicle are on the base body 6th One-piece mounting supports made from the same material 7th shaped. The assembly supports 7th show you about their length L. extending and along the front long side 8th screw clearance open to the outside 9 on. The screw clearance 9 is through a recess that is U-shaped in horizontal cross-section 10 in the assembly support 7th formed, which extends over the entire length L. from the top 11 the assembly support 7th to the bottom 12 the assembly support 7th extends. The screw clearance 9 is on the front long side 8th the assembly support 7th continuously open.

Also the nozzle-shaped fuel inlet 3 is made of the same material in one piece in terms of forging technology on the base body 6th educated. In the basic body 6th a longitudinal cavity is created by means of deep drilling.

As in particular in the 3 can be seen, shows a screw clearance 9 an upper length 13 and a lower length 14th on. Between the upper length section 13 and the lower length section 14th is a bottleneck 15th educated. From the bottleneck 15th starting out, the upper length section widens 13 towards the top 11 the assembly support 7th conical. The lower length section 14th expands from the bottleneck 15th starting downwards towards the bottom 12 the assembly support 7th also conical. The cone angle α in the upper length section 13 and in the lower length section 14th is preferably 2 °. In this way, screw clearance can be advantageous in the forging process 9 can be generated without disadvantageous burr formation. The accumulator pipe 2 can be easily removed from the forging tool without burrs.

Between an assembly support 7th and a connection piece 4th is a reinforcement strut 16 on the main body 6th molded in one piece from the same material. The reinforcement strut 16 runs below the body 6th diagonally from the connecting piece 4th to the assembly support 7th . The reinforcement strut 16 is between that at an outer end 17th of the main body 6th arranged connection piece 4th and an adjacent mounting bracket 7th formed or extends between these. There can also be two reinforcement struts 7th be provided, which is based on the connection piece 4th at the outer end of the body 6th each diagonally to a mounting support 7th extend, with the mounting supports 7th on opposite pages 18th , 19th of the main body 6th are located. Such a second reinforcement strut 16 is in the 4th shown.

As mentioned earlier, the 1 the accumulator pipe 2 or its base body produced by forging 6th after the forging process. The assembly supports 7th , the connecting pieces 4th , 5 and the reinforcement struts 16 are made of the same material in one piece on the base body 6th educated.

After the forging process, there is still a little machining of the pressure accumulator tube 2 required. The tops 11 and the undersides 12 the assembly supports 7th are machined to provide flat surfaces. At the top 11 the assembly supports 7th is a clamping surface 20th for the screw head 21st a fastening screw 22nd educated.

Furthermore, the connection piece 4th for the fuel inlet 3 machined and opened.

The machined pressure accumulator tube 2 of the fuel rail 1 with the machined surfaces on the top 11 and the bottom 12 as well as the fuel inlet 3 show the 2 .

The cutout on a cylinder head 23 mounted fuel rail 1 show the 3 . There is an assembly support there 7th in a view of the screw clearance 9 shown. The screw clearance 9 extends continuously from the top 11 the assembly support 7th to the bottom 12 . The screw clearance 9 is as an outwardly from the tubular body 6th path-pointing continuously open recess 10 in the assembly support 7th Formed by forging technology. The grip length of a fastening screw 22nd corresponds to the length L. . The fastening screw 22nd penetrates the assembly support 7th along the screw clearance 9 and is in a threaded hole 24 in the cylinder head 23 screwed in. At the top 11 the assembly support 7th lies the screw head 21st on the clamping surface 20th at.

In the area of the bottleneck 15th becomes the fastening screw 22nd held clamped. Furthermore is the fastening screw 22nd in screw clearance 9 through the side walls 25th the assembly support 7th so far enclosed that the fastening screw 22nd is held clamped.

Especially in the 7th you can see that the mounting supports 7th outside, i.e. on their outside 26th the side walls 25th taper conically. On the outside 26th the side wall 25th has a mounting bracket 7th a widest waistband area 27 on and an upper length section 28 and a lower length 29 . The upper length section 28 tapers starting from the collar area 27 to the top 11 down. The lower length section 29 tapers starting from the collar area 27 towards the bottom 12 . An assembly support 7th is on their outside 26th opposite to the waisted structure on the inside along the screw clearance 9 designed.

List of reference symbols

1 -

Fuel rail

2 -

Accumulator pipe

3 -

Fuel inlet

4 -

Connection piece

5 -

Connection piece

6 -

Base body

7 -

Assembly support

8th -

front long side of 7

9 -

Screw clearance

10 -

Recess

11 -

Top of 7

12 -

Bottom of 7

13 -

upper length section

14 -

lower length section

15 -

Bottleneck

16 -

Reinforcement strut

17 -

outer end of 6

18 -

Page of 6

19 -

Page of 6

20 -

Clamping surface

21 -

Screw head

22 -

Fastening screw

23 -

Cylinder head

24 -

Threaded hole

25 -

Side wall

26 -

Outside of 25

27 -

Waistband area

28 -

upper length section

29 -

lower length section

L -

Length of 7

α -

Cone angle

Claims (6)

Fuel distributor (1) which has a pressure accumulator tube (2) for receiving pressurized fuel, the pressure accumulator tube (2) having a base body (6) on which connecting pieces (4, 5) and mounting supports (7) are formed from the same material , wherein the assembly supports (7) have an outwardly open screw clearance (9) extending over their length (L), characterized in that the base body (6) is forged and the screw clearance (9) in relation to the installation position of the fuel distributor (1 ) relative to a cylinder head (23) has an upper longitudinal section (13) oriented away from the cylinder head (23) and a lower longitudinal section (14) oriented towards the cylinder head (23), the upper longitudinal section (13) extending in the direction of the top ( 11) the assembly support (7) widens conically and the lower longitudinal section (14) widens conically in the direction of the underside (12) of the assembly support (7). Fuel distributor (1) Claim 1 , characterized in that the cone angle (α) in the upper length section (13) and / or in the lower length section (14) is dimensioned between 1 ° and 6 ° and is preferably 2 °. Fuel distributor (1) Claim 1 or 2 , characterized in that a constriction (15) is formed between the upper length section (13) and the lower length section (14). Fuel distributor (1) after one of the Claims 1 to 3 , characterized in that the assembly support (7) has a clamping surface (20) for the screw head (21) of a fastening screw (22) on its upper side (11). Fuel distributor (1) after one of the Claims 1 to 4th , characterized in that a reinforcing strut (16) is formed between an assembly support (7) and a connecting piece (4). Fuel distributor (1) Claim 5 , characterized in that the reinforcement strut (16) extends between a connecting piece (4) arranged at an outer end (17) of the base body (6) and an assembly support (7).

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