EP2585706A1

EP2585706A1 - Inlet connector

Info

Publication number: EP2585706A1
Application number: EP11730544.1A
Authority: EP
Inventors: Christian Graspeuntner
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2010-06-22
Filing date: 2011-06-21
Publication date: 2013-05-01
Also published as: WO2011160148A1; JP2013529741A; CN103038494A; CN103038494B; JP5932784B2; AT509332A4; KR20130044304A; KR101489133B1; AT509332B1; US20130092131A1

Abstract

For an inlet connector (4) for connecting at least one high-pressure line of a common rail injection system to an inlet bore (6) of a fuel injector, a pressure pipe (7), which can be connected to the inlet bore (6), and a housing (8), which has a connection for the at least one high-pressure line, are connected to each other so as to form a sliding seat.

Description

An inlet connector

The invention relates to a pressure pipe socket for connecting at least one high pressure line of a common rail injection system with an inlet bore of a fuel injector. The invention further relates to an internal combustion engine with a common rail injection system comprising a high-pressure accumulator (common rail), at least one specified in a cylinder head injector for injecting fuel into a combustion chamber of the internal combustion engine and at least one high-pressure accumulator fed high-pressure line.

In modern diesel engines with common-rail technology, there is a pressure pipe connection between the fuel injector and the high-pressure fuel line, which connects the two components as an intermediate element. The pressure pipe socket must be sealed against the injector. The pressure pipe stub, which is penetrated in its longitudinal direction by a through hole, is usually located in a bore extending from a longitudinal side of the cylinder head to a port on the injector across the cylinder head. In order to produce a pressure-tight connection between the pressure pipe nozzle and the injector body, the pressure pipe nozzle is usually pressurized against the injector body via an element that builds up a press-fit pressure, with a cone arranged on the pressure pipe nozzle being pressed into a corresponding conical recess in the connector of the injector.

In this case, against the injector facing away from the cylinder head projecting end of the pressure pipe neck, the high pressure line by means of a nozzle on the high pressure line encompassing cap screw clamped, which is screwed into the pressure pipe socket receiving transverse bore in the cylinder head and so the pressure pipe socket axially against the am Injector body provided, the inlet channel delimiting seat presses. In such a construction, however, is disadvantageous that fluctuations in the dependent on the torque of the union nut axial Sealing force of the connection of the pressure pipe connection to the inlet line of the injector lead to strong fluctuations in the permissible pressure threshold strength. Another disadvantage is that the biasing force is subject to fluctuations at the said high pressure port, which are due to different thermal expansions of the pressure pipe socket and the cylinder head.

EP 2 058 509 A1, EP 1 719 899 A1 and EP 1 653 076 A1 show pressure pipe stubs from the prior art in which the above-mentioned problem occurs.

The present invention therefore aims to develop a pressure pipe socket of the type mentioned in such a way that the biasing force or the pressure of the pressure pipe socket on the connection of the inlet bore on the injector is independent of the connection situation at the opposite end of the pressure pipe socket, ie the connection situation of High pressure line. To achieve this object, according to a first aspect of the invention, a pressure pipe socket of the type mentioned above is characterized in that a connectable to the inlet bore pressure pipe and a connection for the at least one high-pressure line having housing with the formation of a sliding seat are interconnected. To achieve this object, according to a further aspect of the invention further comprises an internal combustion engine with a common rail injection system comprising a high-pressure accumulator (common rail), at least one defined in a cylinder head injector for injecting fuel into a combustion chamber of the internal combustion engine and at least one of the high-pressure accumulator provided high-pressure line, which is developed such that the at least one high-pressure line via a pressure pipe connection according to the invention to an inlet bore of the injector ange- is closing, wherein the pressure pipe socket passes through a transverse bore of the cylinder head.

Due to the fact that the pressure pipe socket comprises two components, namely the pressure pipe connectable to the inlet bore of the injector and the housing having a connection for the at least one high-pressure line, which are connected to one another by means of a sliding seat, the advantage is achieved that the pressure pipe is detached from the housing is separated in the axial direction, so that the provided at the two ends of the pressure pipe connection, namely the connection of the pressure pipe to the inlet bore of the injector and the connection of the high-pressure line to the housing, must be realized separated from each other, wherein the respective Connections applied biasing forces or the respectively applied input or contact pressures independently of each other come into effect.

In particular, this can be done with a corresponding tightening torque a very safe installation of the pressure tube. A preferred embodiment provides in this context that the pressure tube is screwed into the injector body for connection to the inlet bore of the injector.

The housing can be decoupled from the pressure pipe in particular by the fact that, as corresponds to a preferred embodiment, the housing has a flange with holes for fastening the housing to the cylinder head. The said decoupling also leads to a very good vibration damping, since any vibrations due to the connection of the housing with the pressure tube by means of said sliding seat are less strongly transmitted to the pressure tube.

A further advantage of the invention is that the high preload forces allow secure mounting of the high-pressure lines without the risk of loosening the pressure tube or displacing the housing within the cylinder head. Due to the sliding seat, a length Immediately as a result of different thermal expansions without pre-tension loss at the pressure pipe possible.

The sliding seat preferably comprises two substantially sealingly cooperating cylindrical sealing surfaces. The seal is made in particular by the choice of a very small radial clearance between the cooperating sealing surfaces, with a radial clearance of a few micrometers is preferred. Furthermore, the seal between the pressure tube and the housing is favored by a large overlap length on the sliding seat. In this context, the design is preferably developed in such a way that the cylindrical sealing surfaces are formed by the outer jacket of a region of the pressure tube or housing formed with reduced outer diameter and by the inner surface of a bore formed in the other part.

The tightness of the realized by the sliding seat connection can be further increased by the radial play between see the pressure tube and the housing under the influence of the fuel pressure is further reduced and in particular almost eliminated. As a result, the leakage quantities occurring due to the annular gap can be minimized. In order to utilize the system pressure to reduce the radial play, a preferred development provides that the wall thickness of the region of the pressure tube formed with a smaller outer diameter is smaller than in the remaining region of the pressure tube. Due to the smaller wall thickness, the region of the pressure tube formed with a smaller outer diameter can expand in the radial direction, so that the sealing surface of the pressure tube is pressed against the sealing surface of the housing. Particularly advantageous in this connection is an embodiment in which the wall thickness of the region of the pressure tube formed with a smaller outer diameter amounts to between 30 and 70% of the inner diameter in this range. In order to achieve an additional seal on the sliding seat, in addition, a sealing element can be used, such as a PEEK ring or known from the prior art hydraulic seal packages.

Any leakage quantities can preferably be derived via a leakage discharge bore. In this context, the invention is preferably developed in such a way that a leakage discharge bore leads away from the transverse bore of the cylinder head, preferably in the region of the sliding seat of the pressure pipe neck.

For sealing between the housing of the pressure pipe socket and the cylinder head is preferably provided that a edge of the transverse bore of the cylinder head cross-area, in particular the flange of the housing of the pressure pipe socket with the interposition of a sealing element on the cylinder head. Pressure pipe sockets of the type described above generally have a flow restrictor. In a preferred embodiment of the invention, the flow restrictor is arranged in the housing of the pressure pipe socket. In order to facilitate the installation of the flow restrictor, a preferred development further provides that the bore of the pressure tube which has a smaller outer diameter is formed in an insert screwed into the housing. The insert screwed into the housing limits a cavity formed in the housing, in which the flow restrictor is arranged.

Further preferred embodiments will become apparent from the dependent claims. The invention will be explained in more detail with reference to an embodiment schematically illustrated in the drawing. In this is the injector body of a not dargestell- ten injector designated by 1. The cylinder head is designated 2 and has a transverse bore 3, which is penetrated by a pressure pipe stub 4. The pressure pipe stub 4 connects high-pressure lines, not shown, which are to be connected to the high-pressure connections 5, with the inlet bore 6 formed in the injector body 1, via which high-pressure fuel is supplied to the injector nozzle. The pressure pipe socket 4 consists of a pressure tube 7 and a housing. 8 For the passage of the high pressure fuel, the housing 8 of the high pressure ports 5 each obliquely away leading holes 9, which open into a cylindrical space 10 in the housing 8. The cylindrical space 10 is delimited by an insert piece 11 screwed into the housing 8, on whose annular end face a compression spring 12 of a flow restrictor 13 is supported. The displaceable in the axial direction actuator of the flow restrictor 13 is denoted by 14.

The insert 11 has a central bore 15 in which a region 16 of the pressure tube 7 formed with a reduced outer diameter is inserted. The formed with a reduced outer diameter portion 16 of the pressure tube 7 and the insert 11 of the housing 8 have cooperating cylindrical sealing surfaces which are freely displaceable in the direction of the double arrow 17 relative to each other. The sealing surfaces thus form a sliding seat, which establishes the connection between the housing 8 and the pressure tube 7. The cylindrical space 10 of the housing 8 is connected via the formed in the pressure tube 7 central bore 18 with the supply line 6.

The actuator 14 of the flow restrictor 13 has a blind hole 19 and is slidably guided in the cylindrical space 10 in the axial direction. The actuator 14 in this case has a conical transition surface 20 between its cylindrical peripheral surface and its closed end wall, with which it forms a valve sealing surface, which is connected to one at a conical cross-sectional transition between the cylindrical space 10 and the bore 18 formed valve seat 21 cooperates. The blind hole 19 is connected via at least one throttle bore 22 with the cylindrical space 10. Via this throttle bore 22, fuel flows from the blind hole 19 into the space 10 and from there further into the adjoining bore 18 when the actuating member 21 is lifted from the valve seat 21. The compression spring 12 is designed such that at a predetermined pressure difference between the not shown High pressure lines and the inlet bore 6, the actuator 14 is held in the illustrated open position. But as soon as the predetermined pressure difference is exceeded, for example, by the breakage of a pipe and an uncontrolled outflow of fuel from this line, the actuator 14 is displaced against the force of the compression spring 12 in the closed position, in which the conical valve surface 20 against the conical seat 21st is pressed and the further flow of fuel is stopped.

The installation of the pressure pipe socket takes place in such a way that first the pressure pipe 7 is guided through the cylinder head 2 and screwed into the injector body 1 by means of a tool acting on the hexagon 23. By choosing a suitable tightening torque, the pressure tube 7 can be securely mounted in this way. The housing 4 is preassembled, wherein the preassembled unit, the actuator 14 of the flow restrictor 13, the compression spring 12 and the insert 11 has. The insert 11 is screwed by means of a thread in the housing 8, wherein a suitable high-pressure seal due to the cooperating conical sealing surfaces 24 is achieved. The preassembled unit is connected via the sliding seat with the pressure tube 7. Thereafter, the housing 8 is fastened with a flange, not shown, and with screws on the cylinder head 2, wherein the biasing force is so high that the tightening torque used for connecting the high-pressure line to the high-pressure connections 5 can be taken with sufficient certainty. The housing 8 is additionally pierced with slots through pins positioned to prevent lateral positional deviation.

The housing 8 is sealed by means of seals 25 against the cylinder head 1. Emerging leaks are discharged via the leakage discharge bore 26. The pressure pipe stub 4 is received over its entire length with radial clearance in the transverse bore 3 of the cylinder head 2, so that height tolerances between the injector and the cylinder head can be compensated.

Claims

Claims:

1. Pressure pipe socket for connecting at least one high-pressure line of a common rail injection system with a Zulaufboh- tion of a fuel injector, characterized in that one with the inlet bore (6) connectable pressure pipe (7) and a connection (5) for the at least one high-pressure line housing (8) are connected to form a sliding seat with each other.

2. pressure pipe socket according to claim 1, characterized in that the sliding seat comprises two substantially sealingly cooperating with each other cylindrical sealing surfaces.

3. pressure pipe socket according to claim 2, characterized in that the pressure tube (7) and the housing (8) in the axial direction along the cylindrical sealing surfaces are freely displaceable against each other.

4. pressure pipe socket according to claim 2 or 3, characterized in that the cylindrical sealing surfaces of the outer shell formed with a reduced outer diameter portion (16) of the pressure tube (7) or the housing (8) and of the inner surface of a formed in the other part Bore are formed.

5. pressure pipe socket according to claim 4, characterized in that the wall thickness of the formed with a smaller outer diameter region (16) of the pressure tube (7) is formed smaller than in the remaining region of the pressure tube (7).

6. pressure pipe socket according to claim 4 or 5, characterized in that the wall thickness of the formed with a lower outer diameter region (16) of the pressure tube (7) is between 30 and 70% of the inner diameter in this range.

7. pressure pipe socket according to claim 4 to 6, characterized in that the formed with a smaller outer diameter portion (16) of the pressure tube receiving bore is formed in a screwed into the housing (8) insert.

8. pressure pipe socket according to one of claims 4 to 7, characterized in that the pressure tube (7) formed on the formed by the lower outer diameter portion (16) paragraph for the approach of a screwing a non-circular cross-section, in particular a hexagonal profile (23 ) having .

9. pressure pipe socket according to one of claims 1 to 8, characterized in that the housing (8) has a flow restrictor (13).

10. pressure pipe socket according to one of claims 1 to 9, characterized in that the housing (8) has a flange with holes for fastening the housing (8) on the cylinder head (2) has up.

11. Internal combustion engine with a common rail injection system comprising a high-pressure accumulator (common rail), at least one specified in a cylinder head injector for injecting fuel into a combustion chamber of the internal combustion engine and at least one of the high-pressure accumulator-fed high-pressure line, characterized in that the at least one high-pressure line is connected via a pressure pipe socket (4) according to one of claims 1 to 10 to an inlet bore (6) of the injector, wherein the pressure pipe socket (4) passes through a transverse bore (3) of the cylinder head (2).

12. Internal combustion engine according to claim 11, characterized in that the pressure pipe socket (4) is received with radial clearance in the bore (3) of the cylinder head (2).

13. Internal combustion engine according to claim 11 or 12, characterized in that the edge of the transverse bore (3) of the cylinder head (2) cross-range, in particular the flange of the housing (8) of the pressure pipe socket (4) with the interposition of a sealing element on the cylinder head (2) is present.

14. Internal combustion engine according to claim 11, 12 or 13, characterized in that of the transverse bore (3) of the cylinder head (2) leads away a leakage discharge bore, preferably in the region of the sliding seat of the pressure pipe socket (4).

15. Internal combustion engine according to one of claims 11 to 14, characterized in that the pressure tube (7) for connection to the inlet bore (6) of the injector in the injector body (1) is screwed.