DE102010001870A1 - Cylinder head for a high-pressure fuel pump - Google Patents

Abstract

The invention relates to a cylinder head for a high-pressure fuel pump in a fuel injection system, in particular in a common rail injection system, wherein in the cylinder head a high pressure bore (1) for forming a pump working space (2) and for receiving a pump piston (3) and at least one further bore ( 4, 5) for receiving a suction valve (6) and / or a high-pressure valve (7) are formed.
According to the invention, the cylinder head is formed at least in two parts and has a first cylindrical part (8) for forming the high-pressure bore (1) and the pump working space (2) and a second annular or flange-like part (9) for receiving the suction valve (6) and / or High-pressure valve (7), wherein the annular or flange-like part (9) at least partially surrounds the cylindrical part (8).
Furthermore, the invention relates to a high-pressure fuel pump with at least one such cylinder head.

Description

The invention relates to a cylinder head for a high-pressure fuel pump in a fuel injection system, in particular in a common rail injection system having the features of the preamble of claim 1. Furthermore, the invention relates to a high-pressure fuel pump with at least one such cylinder head.

State of the art

A cylinder head of the aforementioned type has a high-pressure bore for forming a pump working space and for receiving a pump piston and at least one further bore for receiving a suction valve and / or a high-pressure valve.

Such a cylinder head is for example in the published patent application DE 10 2008 000 705 A1 disclosed. The cylinder head described herein has a pumping chamber in which fuel is periodically compressed and relieved via a reciprocating piston. Further, the pump working space communicates with a respective bore for receiving an intake valve and an exhaust valve via which the fuel supply and the fuel discharge is controlled. About the exhaust valve and a fuel line, the compressed fuel is supplied to a fuel rail.

Such a cylinder head usually has a complex shape and is therefore regularly produced as a cast component. Since ever higher demands are placed on the material with regard to compressive strength, but correspondingly resilient materials are generally not suitable for realizing complex shapes when using a casting method, it has already been proposed in the prior art to design a cast cylinder head housing in two parts.

From the EP 1 803 520 A1 For example, a cylinder head composed of at least two sections emerges, wherein the sections are subsequently joined together in a material-locking manner via a metallic intermediate layer to form a cylinder head. The material for the sections is selected such that one section is superior to the other section in terms of its thermal and / or mechanical load capacity. For the latter, on the other hand, a material is selected which has a good castability and therefore is also able to image complex shapes precisely.

Based on the above-mentioned prior art, the present invention seeks to provide a cylinder head ready, which is simple and inexpensive to manufacture and also compact. The cylinder head is intended to be suitable, in particular, for use in a high-pressure fuel pump designed as a radial piston pump of an injection system of air-compressing, self-igniting internal combustion engines.

To solve the problem, a cylinder head with the features of claim 1 is proposed. Advantageous developments of the invention are specified in the subclaims. The object is further achieved by a high-pressure fuel pump with at least one such cylinder head according to claim 13.

Disclosure of the invention

According to the invention, the cylinder head is formed at least in two parts and has a first cylindrical part for forming the high-pressure bore and the pump working chamber and a second annular or flange-like part for receiving the suction valve and / or the high-pressure valve, wherein the annular or flange-like part at least partially surrounds the cylindrical part. The two-part structure of the cylinder head allows the use of different materials, which can be selected according to the requirements of each part. For example, the materials can differ in terms of their mechanical strength, so that for the less stressed part of a material can be used, which in contrast favors the formation of complex shapes. Since the cylindrical part in which the high-pressure bore is formed, is usually more heavily loaded, this can be made of a material of high strength, while the annular or flange-like part consists of a material which has a lower strength and / or easier pourable is. The manufacturing costs can be optimized in this way.

Advantageously, the cylindrical part and the annular or flange-like part of the cylinder head in the installed state positively and / or non-positively connected to each other. The connection can therefore take place during assembly, so that a further pre-consuming further step of the assembly in the context of the production of the cylinder head is not required. This measure also has a favorable effect on the production costs.

According to a preferred embodiment, the cylindrical part in the region of the pump working chamber has a larger outer diameter, so that a radially extending annular shoulder for engagement with the annular or flange-like part of the cylinder head or on a housing part of the high-pressure fuel pump is provided. Preferably, the annular or flange-like part of the cylinder head also has a radially extending shoulder formed corresponding thereto, so that a positive engagement in the axial direction can already be effected via the contact surfaces of the shoulders. The assembly of the cylinder head on the high-pressure pump can be simplified by the radially extending shoulder of the cylindrical part has a centering ring which can be inserted into a corresponding receiving bore in the adjacent housing part of the high-pressure pump. Alternatively, the cooperating with a bore in the housing part of the high-pressure pump centering ring can also be provided on the annular or flange-like part of the cylinder head.

For fastening the cylinder head to the high-pressure pump, the annular or flange-like part is preferably screwed to the adjacent housing part of the high-pressure pump. Therefore, further holes are preferably provided for receiving fastening screws in the annular or flange-like part of the cylinder head.

In the annular or flange-like part, an inlet bore is furthermore preferably formed, which is sealed off from at least one adjoining surface by means of a sealing ring. The adjacent surface is preferably an area on the adjacent housing part of the high-pressure pump. But a seal via a sealing ring may also be required over another adjacent surface, such as a surface on a housing part of the suction valve, which may be received in a bore of the annular or flange-like part of the cylinder head. If the annular or flange-like part is screwed to the respective housing part, the screw connection ensures the sealing engagement of the sealing ring or the sealing rings.

The sealing of the cylindrical part relative to the annular or flange-like part is preferably carried out by a housing part and / or a valve plate of the suction valve.

For this purpose, according to a first preferred embodiment, the housing part of the suction valve is flanged axially on the annular or flange-like part of the cylinder head and fastened by means of fastening screws, which are guided by the annular or flange-like part, on the housing part of the high-pressure fuel pump. Accordingly, the cylinder head can also be fastened to the housing part of the high-pressure pump via the housing part of the suction valve. The fastening screws ensure a sealing engagement of the components clamped against each other.

According to a further preferred embodiment, at least the valve plate of the suction valve is inserted into a bore of the annular or flange-like part of the cylinder head and is held in engagement with the cylindrical part of the cylinder head via a screw plug also inserted into the bore. The suction valve is thus integrated into the cylinder head, so that an interface with a suction valve arranged outside the cylinder head is eliminated. The number of sealing points is consequently reduced.

In addition, it can be provided that a sealing and / or adjusting disk is arranged between the valve plate inserted into the bore and the cylindrical part of the cylinder head. Thereby, the tightness of the cylindrical part of the cylinder head relative to the suction valve and at the same time be increased relative to the annular or flange-like part of the cylinder head. The intermediate sealing disc also allows adjustment of the altitude of the valve plate of the suction valve, so that it can be optionally adapted to the altitude of an inlet bore. In addition, the setting of additional connection heights erfoderlich be appropriate connections should be present on the suction valve.

A further development measure provides that the valve plate of the suction valve is formed integrally with the cylinder-shaped part of the cylinder head. Thus, a separate valve plate can be omitted. The valve seat of the suction valve is accordingly formed in the cylindrical part of the cylinder head. With the elimination of a separate valve plate, the number of sealing points is further reduced and increases the high-pressure resistance of the cylinder head. For example, the "breathing" of the cylinder head under pressure decreases significantly.

In the pump working chamber opening inlet and outlet holes are preferably formed in the cylindrical part of the cylinder head and / or in the valve plate of the suction valve, if a separate valve plate is provided. Preferably, at least one such bore is sealed off from the annular or flange-like part of the cylinder head via at least one integrally formed or inserted sealing and / or compensating element. Such a sealing and / or compensating element proves to be particularly advantageous in the transition to the high pressure valve, since here the cylinder head is acted upon by high pressure. If the drain hole leading to the high-pressure valve is formed, for example, in the valve plate of the suction valve, a sealing seat for receiving a separate sealing and / or compensating element can be formed on the outside circumference of the valve plate. The sealing seat can also be designed in such a way that a separate sealing and / or Compensating element can be omitted. For example, on the outer peripheral side of the valve plate, a sealing cone may be formed, which engages in a corresponding thereto formed recess of the annular or flange-like part of the cylinder head. In order to ensure a sealing contact, the valve plate can also be biased against the annular or flange-like part by means of a grub screw acting on the outer peripheral surface of the valve plate opposite the sealing seat. In addition, height compensation can be effected via the sealing and / or compensating element, if this is necessary due to production and / or assembly-related tolerances.

According to a further preferred embodiment, the bore for receiving the high-pressure valve is formed in the annular or flange-like part of the cylinder head and has at least one branching holes as a rail connection. This eliminates the interface to the rail, since the rail connection or the rail is integrated into the cylinder head. The two-part design of the cylinder head allows a suitable choice of material adapted to the respective function. The part receiving the rail connection should, for example, be made of a material which has a high degree of toughness in accordance with a rail arranged outside the cylinder head. The other part of the cylinder head, however, can be made of another, especially cheaper material. The embodiment with integrated rail connection or rail is especially suitable for very small engines, eg. B. for engines with 2-3 cylinders.

In order to integrate the rail with a small volume in the cylinder head, for example, may be diverted from the high-pressure valve receiving bore at least one further bore. From this bore then preferably go from several rail or injector connections. The branching bore preferably branches off at right angles from the bore receiving the high pressure valve.

The bore for receiving the high-pressure valve is further preferably closed by a screw plug. Between the screw plug and the high-pressure valve, the bore branches off to receive the rail. Alternatively or additionally, a pressure sensor for regulating the rail pressure can be accommodated in the bore.

The proposed to solve the problem initially set high-pressure fuel pump has at least one cylinder head according to the invention. The number of cylinder heads determined by the number of arranged in the high-pressure fuel pump pump elements.

Preferred embodiments of the invention are described below with reference to the accompanying drawings. These show:

1 a section through a first embodiment of a cylinder head according to the invention,

2 a section through a second embodiment of a cylinder head according to the invention,

3a a section through a third embodiment of a cylinder head according to the invention,

3b -C each have a detail section 3a in the region of the sealing seat formed on the valve plate of the suction valve,

4 a section through a fourth embodiment of a cylinder head according to the invention,

5a a section through a fifth embodiment of a cylinder head according to the invention and

5b a cross section in the area AA the 5a ,

Detailed description of the figures

Of the 1 is to take a two-piece constructed cylinder head for a high-pressure fuel pump, wherein the first part 8th cylindrical and the second part 9 is annular. The cylindrical part 8th has a high pressure hole 1 for the formation of a pump working space 2 and for receiving a pump piston 3 up in the high pressure bore 1 is movable back and forth. The cylindrical part 8th owns in the area of the pump working space 2 a larger Außerndurchmesser, so that a radially outwardly projecting paragraph 10 is trained. With the paragraph 10 lies the cylindrical part 8th on a housing part 11 the high pressure pump. Paragraph 10 is with a centering 24 provided in a bore of the housing part 11 the high-pressure pump engages and thus facilitates the centering of the cylinder head.

In the area with the larger outer diameter is the cylindrical part 8th from the annular part 9 surrounded by the cylinder head. The ring-shaped part 9 has a first contact surface to rest on the housing part 11 the high-pressure pump and a second contact surface on which a housing part 14 a suction valve 6 by means of fastening screws 16 is axially flanged. The fixing screws 16 are through the annular part 9 passed through, so that not only the suction valve 6 , but also the cylinder head on the housing part 11 attached to the high pressure pump become. This is the housing part 14 of the suction valve 6 also on the cylindrical part 8th of the cylinder head, so that the cylindrical part 8th is fixed in position in the axial direction. In the radial direction we do this task of the annular part 9 accepted.

For compact construction of the high-pressure pump is a suction valve 6 leading inlet bore 12 within the housing part 11 led to the high-pressure pump, which extends through the cylinder head. The inlet bore 12 is present in the annular part 9 educated. At the interface to the housing part 11 the high-pressure pump is in the area of the transition of the inlet bore 12 a sealing ring 13 used. Another sealing ring 13 is located in the area of the transition to the housing part 14 of the suction valve 6 , The for fixing the housing part 14 and the annular part 9 the cylinder head provided mounting screws 16 ensure a sealing contact of the sealing rings 13 on the respective housing parts 11 . 14 , At the same time the axially flanged suction valve seals 6 over the housing part 14 and a valve plate 15 the cylindrical part 8th the cylinder head against the annular part 9 from.

The annular part 9 the cylinder head further has a bore 5 for receiving a high pressure valve 7 on, via a radially guided drain hole 20 in conjunction with the pump work space 2 stands. The high pressure valve 7 is thus integrated in the cylinder head. To the annular part 9 to relieve, is the high pressure valve 7 surrounded by a pressure pipe socket, which up to the cylindrical part 8th the cylinder head is zoomed up. To the tightness in the area of the transition to the cylindrical part 8th to ensure the pressure pipe socket is frontally cone-shaped and engages in a Korresopndierend trained recess of the cylindrical part 8th of the cylinder head. It is thus formed a cone-shaped sealing seat. Because the high pressure valve 7 in the ring-shaped part 9 the cylinder head is taken tension-free, the sealing effect of the pressure pipe socket is increased in the region of the sealing seat.

A second embodiment of a cylinder head according to the invention is the 2 refer to. In contrast to the previous embodiment, the suction valve is now also 6 integrated into the cylinder head. A housing part 14 can thus be omitted. The number of interfaces or sealing points is further reduced in this way. To attach the cylinder head to the housing part 11 to allow the high-pressure pump is now the second part 9 made of the cylinder head flange. Mounting screws received in the flange area 16 serve the determination of the cylinder head on the housing part 11 the high pressure pump. For integration of the suction valve 6 is in the flange-like part 9 a hole 4 formed, in which the valve plate 15 of the suction valve 6 is used. About one also in the hole 4 recorded screw plug 17 becomes the valve plate 15 opposite the cylindrical part 8th the cylinder head braced. Thus, the closure screw causes 17 a positive and non-positive connection of the two parts 8th . 9 the cylinder head with each other, as well as with the housing part 11 of the high pressure pump. Supporting here acts a radially extending paragraph 10 at the cylindrical part 8th and a corresponding trained paragraph on the flange-like part 9 , To center the two parts 8th . 9 in turn to facilitate the high-pressure pump is a Zentrierrng 24 provided in the present embodiment, however, on the flange-like part 9 is arranged.

Another difference of in 2 illustrated embodiment with respect to the 1 consists in the formation of the pump workspace 2 , the now of the valve plate 15 is limited radially. The to the high pressure valve 7 leading drainage hole 20 is therefore in the valve plate 15 of the suction valve 6 educated. The pressure pipe socket of the high pressure valve 7 is therefore not up to the cylindrical part 8th , but in a similar way to the valve plate 15 brought up. Correspondingly means that the pressure pipe socket is in turn conically shaped frontally and in a cone-shaped sealing seat of the valve plate 15 intervenes.

When in the 3a illustrated third embodiment of a cylinder head according to the invention is the pump working space 2 from the cylindrical part 8th the cylinder head radially limited. The valve plate 15 of the suction valve 6 closes the pump work space 2 only in the axial direction. To the tightness between the valve plate 15 and the cylindrical part 8th is between the valve plate 15 and the cylindrical part 8th a sealing and / or shim 18 inserted. In combination with the screw plug 17 can over the sealing and / or shim 18 not only the tightness of the sealing point can be increased, but also the altitude of the suction valve 6 be set. The altitude of the suction valve 6 can thus on the altitude of Zulaufbohrungen 19 and drainage holes 20 adjacent components are placed in the valve plate 15 of the suction valve 6 be continued. In the present embodiment, not only is an inlet hole 19 in the valve plate 15 integrated, but also a drain hole 20 that the pump work space 2 with the high pressure valve 7 combines. The hole 20 has for this purpose a radially and an axially guided part. The sealing point opposite the high pressure valve 7 is therefore on the valve plate 15 educated. Instead of a frontally conical pressure pipe socket, which in a conical recess of the valve plate 15 engages, in the present case, both connection surfaces have a conical recess for receiving a sealing and / or compensation element 21 on. The recorded sealing element 21 not only increases the sealing effect, but also serves to compensate manufacturing and / or assembly-related tolerances. A corresponding sealing and / or compensation element 21 is in 3b shown. An alternative embodiment of a sealing and / or compensating element 21 goes out of the 3c out. Instead of a separate element 21 On the outer circumference side of the valve plate, a sealing cone is formed, which in a corresponding thereto formed recess on the flange-like part 9 of the cylinder head, in which one to the high pressure valve 7 leading drainage hole 20 is formed, engages.

Regardless of the particular chosen embodiment of a sealing and / or compensating element 21 the sealing effect can be improved by the fact that the valve plate 15 is radially biased against the sealing point. For this purpose, one in the flange-like part 9 inserted grub screw 26 be used, the opposite of the sealing point, the outer peripheral side of the valve plate 15 attacks and thus the valve plate 15 presses against the sealing point.

A fourth embodiment is from the 4 out. In this embodiment, the cylindrical part forms 8th the cylinder head the valve seat for the suction valve 6 out. A separate valve plate 15 can thus be omitted. As a result, the number of interfaces to be sealed can be further reduced. At the same time, the high-pressure resistance of the cylinder head is increased. For example, a "breathing" of the cylinder head under pressure significantly less noticeable. Due to the omission of a separate valve plate 15 are now the inlet holes 19 and the drain holes 20 in the cylindrical part 8th formed of the cylinder head. The transition area to the high pressure valve 7 can by receiving or training a sealing and / or compensation element 21 corresponding 3a C take place or - as shown here - over a front cone-shaped pressure pipe socket of the high pressure valve 7 which is in a corresponding recess on the cylindrical part 8th engages the cylinder head.

5a shows a fifth embodiment of a cylinder head according to the invention, in which a rail with a small volume is integrated into the cylinder head. This is the hole 5 for receiving the high pressure valve 7 extended executed and has a branching hole 22 perpendicular to the high pressure bore 5 on. From the bore serving as a rail 22 go in turn two rail or injector connections 25 from (see 5b ). The number two is chosen only as an example, so that the number of rail or injector connections can vary. Behind the branching, serving as a rail hole 22 is in the high pressure hole 5 a screw plug 23 set. Alternatively or additionally, a pressure sensor for rail pressure measurement can also be used here.

The embodiments given demonstrate the versatility of the design of a two-part cylinder head, since the respective equipment features can be exchanged or combined with each other. The cylinder head according to the invention is therefore suitable for a number of high pressure pumps. Vorzgusweise he finds use in a designed as a radial piston high-pressure fuel pump with several, for example, three pump elements, each pump element is associated with a corresponding cylinder head.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008000705 A1 [0003]
• EP 1803520 A1 [0005]

Claims (13)

Cylinder head for a high-pressure fuel pump in a fuel injection system, in particular in a common-rail injection system, wherein in the cylinder head a high-pressure bore ( 1 ) for forming a pump work space ( 2 ) and for receiving a pump piston ( 3 ) and at least one further bore ( 4 . 5 ) for receiving a suction valve ( 6 ) and / or a high pressure valve ( 7 ) are formed, characterized in that the cylinder head is formed at least in two parts and a first cylindrical part ( 8th ) for the formation of the high-pressure bore ( 1 ) and the pump work space ( 2 ) and a second annular or flange-like part ( 9 ) for receiving the suction valve ( 6 ) and / or the high pressure valve ( 7 ), wherein the annular or flange-like part ( 9 ) the cylindrical part ( 8th ) at least partially surrounds. Cylinder head according to claim 1, characterized in that the cylindrical part and the annular or flange-like part of the cylinder head in the installed state are positively and / or non-positively connected to each other. Cylinder head according to claim 1 or 2, characterized in that the cylindrical part ( 8th ) in the area of the pump working space ( 2 ) has a larger outer diameter, so that a radially extending annular shoulder ( 10 ) for engagement with the annular or flange-like part ( 9 ) of the cylinder head or on a housing part ( 11 ) of the high-pressure fuel pump is provided. Cylinder head according to one of the preceding claims, characterized in that in the annular or flange-like part ( 9 ) an inlet bore ( 12 ) is formed, which opposite at least one adjacent surface by means of a sealing ring ( 13 ) is sealed. Cylinder head according to one of the preceding claims, characterized in that the sealing of the cylindrical part ( 8th ) with respect to the annular or flange-like part ( 9 ) by a housing part ( 14 ) and / or a valve plate ( 15 ) of the suction valve ( 6 ) he follows. Cylinder head according to claim 5, characterized in that the housing part ( 14 ) of the suction valve ( 6 ) axially on the annular or flange-like part ( 9 ) of the cylinder head is flanged and by means of fastening screws ( 16 ) passing through the annular or flange-like part ( 9 ), on the housing part ( 11 ) of the high-pressure fuel pump can be fastened. Cylinder head according to claim 5, characterized in that at least the valve plate ( 15 ) of the suction valve ( 6 ) into a hole ( 4 ) of the annular or flange-like part ( 9 ) of the cylinder head is inserted and via a likewise in the bore ( 4 ) screw plug ( 17 ) in contact with the cylindrical part ( 8th ) of the cylinder head is held. Cylinder head according to one of claims 5 to 7, characterized in that between the in the bore ( 4 ) used valve plate ( 15 ) and the cylindrical part ( 8th ) of the cylinder head a sealing and / or shim ( 18 ) is arranged. Cylinder head according to one of the preceding claims, characterized in that the valve plate ( 15 ) of the suction valve ( 6 ) in one piece with the cylindrical part ( 8th ) of the cylinder head is formed. Cylinder head according to one of the preceding claims, characterized in that the cylindrical part ( 8th ) and / or the valve plate ( 15 ) of the suction valve ( 6 ) into the pump work space ( 2 ) inlet bores ( 19 ) and / or drain holes ( 20 ), wherein at least one bore ( 19 . 20 ) with respect to the annular or flange-like part ( 9 ) via at least one molded or inserted sealing and / or compensating element ( 21 ) is sealed. Cylinder head according to one of the preceding claims, characterized in that the bore ( 5 ) for receiving the high-pressure valve ( 7 ) in the annular or flange-like part ( 9 ) of the cylinder head is formed and at least one branching holes ( 22 ) has a rail connection. Cylinder head according to claim 11, characterized in that the bore ( 5 ) by a screw plug ( 23 ) is closed and / or in the bore ( 5 ) a pressure sensor for rail pressure control is included. High-pressure fuel pump with at least one cylinder head according to one of the preceding claims.

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