Clamping element for a fuel injection valve and fuel injection system

Information

  • Patent Grant
  • 6684860
  • Patent Number
    6,684,860
  • Date Filed
    Thursday, August 29, 2002
    22 years ago
  • Date Issued
    Tuesday, February 3, 2004
    20 years ago
Abstract
A clamping element for a fuel injector is provided that is insertable into a mounting hole of a cylinder head of an internal combustion engine, and that directly injects fuel into a combustion chamber of the internal combustion engine has a first step ring. This at least partially surrounds the fuel injector and has a valve pressure surface that may rest on the fuel injector. The first step ring has at least one circumferential slope surface on its side facing away from the valve pressure surface, which engages with a corresponding circumferential slope surface of a second step ring, which has a counterpressure surface. The slope surfaces are arranged so that the first step ring and the second step ring are pressed axially apart when they are rotated relatively to one another.
Description




FIELD OF THE INVENTION




The present invention relates to a clamping element and a fuel injection system.




BACKGROUND INFORMATION




A clamping element in the form of a hold-down element is referred to in Japanese Published Patent Application No. 08-312503. The hold-down element holds down a fuel injector against a relatively high combustion pressure prevailing in the combustion chamber of the internal combustion engine. The hold-down element engages with a collar of the fuel injector at two circumferentially opposite locations, the collar resting with its lower side on the upper side of the cylinder head, so that the fuel injector is held down. The hold-down element is pulled on to the cylinder head by a clamping screw.




It is believed that the hold-down element referred to in Japanese Published Patent Application No. 08-312503 has the disadvantage that it is difficult to access the clamping screw if a fuel distribution line has already been fitted. If the fuel distribution line is not fitted until after the hold-down elements have been fitted and after they have been pre-tensioned to the defined retention force, the fuel injectors may no longer be moved or may only be moved if considerable force is applied, and tolerances at the connection points to the fuel distribution line, which in the case of high-pressure injection systems is rigid, may not be modified. Furthermore, a tight connection may only be achieved with difficulty or not at all. If the clamping screws are not tightened until after the fuel distribution line has been fitted, it may be difficult to access the clamping screws.




Furthermore, a hold-down device embodied as a clamp bracket similar hold-down element referred to in Japanese Published Patent Application No. 08-312503, is referred to in German Published Patent Application No. 197 35 665. In the case of the hold-down device, the cylinder head has a recess in which the collar of the fuel injector is arranged, so that the collar of the fuel injector on which the hold-down device acts is lowered into the cylinder head. It is believed that this has the disadvantages already mentioned.




A clamping element that holds a fuel injector in a mounting hole of a cylinder head of an internal combustion engine and rests against a fuel distribution line, is referred to in German Published Patent Application No. 197 56 102. The clamping element includes a spiral spring that extends between a spring holding element of the fuel injector and a spring holding element of the fuel distribution line. Furthermore, from German Published Patent Application No. 197 56 102, for assembly, one or more assembly clamps, which pre-tension the fuel injector, the fuel distribution line and the spiral springs and hold them in their position until assembly has been completed, should be provided.




It is believed that a disadvantage of the clamping element referred to in German Published Patent Application No. 197 56 102 is that with a spiral spring it may be difficult to achieve the necessary high clamping forces. Furthermore, it may be disadvantageous that, if a pre-mounted unit that includes a fuel distribution line, clamping elements and fuel injectors is fitted, additional assembly clamps may be required. Moreover, it may be disadvantageous that, when the fuel distribution line is fitted all spiral springs should be tensioned simultaneously and adjustments of individual fuel injectors to any tolerances in the mounting hole in question may not be carried out consecutively.




SUMMARY OF THE INVENTION




By contrast, it is believed that an exemplary clamping element according to the present invention has the advantage that high clamping forces may be achieved using small clamping element dimensions.




It is believed to be advantageous if the first step ring and the second step ring have coaxial holes into which the fuel injector and a connection piece of a fuel distribution line may be inserted. Thus, small design dimensions and a favorable arrangement of the clamping element may be achieved because only one circumferential collar around the fuel injector is required to bear the clamping force. Furthermore, it is believed to be advantageous that the clamping element may be held in the holes.




It is believed to be advantageous if the first step ring and the second step ring are held so that they are concentric relative to one another by shoulder of the first step ring or second step ring that engages with a corresponding step of an axial hole of the other step ring. As a result, the clamping element may be a compact, self-contained component, which may be inserted as a single element during assembly.




It is believed to be advantageous if the first step ring and the second step ring each have on their circumference a bolt that is rotatably mounted axially parallel to the step ring and is axially movable, and have a hole that extends across it, and if the hole of one bolt is a threaded hole, and if a screw that is held in the hole of the other bolt is present and engages with the threaded hole. Thus, the first and second step ring may be rotated against one another and the clamping force of the clamping element may be adjusted. For example, the screw may be arranged so that it is easily accessible, as the axis of the screw points away from a plane that is at least approximately formed by the fuel injectors and the fuel distribution line and does not lie in that plane.




It is believed that an exemplary fuel injection system according to the present invention has the advantage relative to the related art that the retention force is imparted against the fuel distribution line. As a result, no additional components may be required, which may save space. Moreover, the sequence of tensioning may be chosen freely.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

shows a clamping element via which a fuel injector is clamped into a mounting hole.





FIG. 2

shows an exemplary clamping element according to the present invention installed between a fuel distribution line and a fuel injector.





FIG. 3

is a sectional view of the exemplary clamping element according to the present invention shown in

FIG. 2

with fuel a distribution line.





FIG. 4

is a sectional view showing further detail of portion IV shown in FIG.


3


.





FIG. 5

is a sectional view of the exemplary clamping element of

FIG. 2

, with a tensioning device formed by a screw.





FIG. 6

shows an exemplary clamping element according to he present invention installed between a fuel distribution line and a fuel injector, shown in a side view that has been rotated by 90° relative to the exemplary embodiment shown in FIG.


2


.











DETAILED DESCRIPTION





FIG. 1

shows a clamping element. The clamping element is in the form of a hold-down element


1


, which holds a fuel injector


2


in a mounting hole


3


. Fuel injector


2


is connected to a rigid fuel distribution line


4


, for fuel injectors that inject fuel at high pressure into the combustion chamber. Hold-down element


2


has a contact piece


5


, which rests on a cylinder head


6


(shown here in section view, and only partly shown) and has an attachment element that is embodied as screw


7


. Screw


7


penetrates a lever arm


8


of hold-down element


1


and is screwed into a threaded hole


9


of cylinder head


6


.




Lever arm


8


divides in the shape of a fork around fuel injector


2


. Fuel injector


2


has a step


10


, on whose radial surface pressure mushrooms


11


, which are formed on the ends of the fork-shaped section of lever arm


8


of hold-down element


1


, rest. If it is rotated deeper into threaded hole


9


, screw


7


pulls lever arm


8


, which rests against cylinder head


6


via contact piece


5


, toward cylinder head


6


via a washer


12


, which allows angle compensation via a spherical surface


13


. As a result, at the fork-shaped end of lever arm


8


a clamping force is exerted on fuel injector


2


in the direction of mounting hole


3


via pressure mushrooms


11


(only one can be seen in the chosen view in the drawing) at two points of step


10


that are located opposite one another on the circumference of fuel injector


2


. This clamping force holds fuel injector


2


in mounting hole


3


against the combustion pressure in the combustion chamber (not shown).





FIG. 1

also shows connector plug


14


for triggering fuel injector


2


and seal


15


opposite the combustion chamber. Fuel distribution line


4


is connected to fuel injector


2


via connector nozzle


14




a.






There may be little space, for example, next to and above the cylinder head, since it is desirable for the design of the internal combustion engine to be compact. As a result, fuel distribution line


4


is arranged as directly as possible above fuel injectors


2


and is generally offset somewhat from the middle of the cylinder head. This results in the arrangement shown in

FIG. 1

, in which the extension of central axis


16


of screw


7


intersects with fuel distribution line


4


. As a result, once fuel distribution line


4


has been installed, a tool may be only introduced laterally and with freedom of movement in one plane. This may be hindered by other components, such as, for example, the ignition or gas exchange system.





FIG. 2

shows an exemplary clamping element according to the present invention that is arranged between a fuel distribution line


17


(only partly shown) and a fuel injector


18


(only partly shown), which is inserted into a cylinder head


26


. A first step ring


19


has a valve pressure surface


20


, which rests indirectly against fuel injector


18


. On the side facing away from fuel injector


18


and valve pressure surface


20


, first step ring


19


has a plurality of circumferential slope surfaces


21


, which are arranged in one direction circumferentially, have the same incline, and each form a section of a screw surface.




A second step ring


22


has a counterpressure surface


23


, which rests against a shoulder of fuel distribution line


17


. On the side facing fuel injector


18


, second step ring


22


also has a plurality of circumferential slope surfaces.




Counterpressure surface


23


rests against a connection piece


25


of fuel distribution line


17


. Furthermore, a central axis


27


, which corresponds to the axis of the mounting hole (not shown) of fuel injector


18


in cylinder head


26


, is also shown in the drawing. Circumferential slope surfaces


21


,


24


of first step ring


19


and of second step ring


22


match one another in their incline and orientation of rotation so that they work together as a thread and, respectively, engage with one another via their slope surfaces


21


,


24


. Incline surfaces


21


,


24


may, for example, resemble the teeth of a saw.





FIG. 2

also shows a connector plug


28


of fuel injector


18


, which in the embodiment shown in

FIG. 2

is a fuel injector


18


having an electrically triggered actuator. Furthermore,

FIG. 2

shows parts of a tensioning device


29


(largely hidden) which allows first step ring


19


and second step ring


22


to be rotated relative to one another and which is described in detail with respect to

FIG. 5

below.




In the non-tensioned state shown in

FIG. 2

, individual circumferential slope surfaces


21


of first step ring


19


are in contact with the corresponding circumferential slope surfaces of second step ring


22


so that every circumferential slope surface


21


,


24


is in contact with a corresponding circumferential slope surface


21


,


24


over its entire surface. If first step ring


19


and second step ring


22


are rotated relative to one another, circumferential slope surfaces


21


,


24


slide against each other and push first step ring


19


and second step ring


22


apart. Valve pressure surface


20


and counterpressure surface


23


move in the axial direction relative to central axis


27


.




If valve pressure surface


20


rests on fuel injector


18


and counterpressure surface


23


rests on connection piece


25


of fuel distribution line


17


, the clamping element presses fuel injector


18


into mounting hole of cylinder head


26


, and rests against fuel distribution line


17


. If the incline of the circumferential slope surfaces


21


,


24


is appropriately chosen, the compressive force exerted may be determined as a function of the force with which first step ring


19


and second step ring


22


are rotated relative to one another. In particular, substantial compressive forces may be achieved.




The maximum distance in the axial direction relative to central axis


27


by which first step ring


19


and second step ring


22


may be pressed apart may be determined by the number of circumferential slope surfaces


21


,


24


and the incline. Thus, substantial tolerances may be offset in the axial direction relative to central axis


27


that arise between fuel distribution line


17


and fuel injector


18


. Furthermore, the clamping element does not require any further attachment point on cylinder head


26


, like screw


7


in

FIG. 1

in the case of a hold-down element. Altogether, the dimensions of an exemplary clamping element according to the present invention may be small.





FIG. 3

shows the exemplary clamping element according to the present invention shown in

FIG. 2

in a sectional view, fuel distribution line


17


being partially shown in a sectional view. In

FIG. 3

, the same reference numbers are used as in

FIG. 2

for the same elements. Fuel injector


18


, which is inserted into cylinder head


26


, is also only partly shown. Connection piece


25


of fuel distribution line


17


is connected via an inflow hole


35


to a distribution pipe


34


of fuel distribution line


17


. Central axis


27


, which is shown in the

FIG. 3

, corresponds to the axis of the mounting hole (not shown) of fuel injector


18


in cylinder head


26


.




Moreover, connection piece


25


has a smaller-diameter shoulder


36


, which is held in a coaxial hole


31


of first step ring


19


and in a coaxial hole


32


of second step ring


22


, which have the same diameter. Thus, the clamping element is defined radially relative to central axis


27


with regard to connection piece


25


of fuel distribution line


17


.




Fuel injector


18


is inserted into a hole


38


of connection piece


25


of fuel distribution line


17


via an inflow section


37


. A ring seal


39


seals inflow section


37


of fuel injector


18


against hole


38


of connection piece


25


. Fuel injector


18


has a clamping sleeve


40


(shown in a sectional view), on which first step ring


19


rests and which has a recess, e.g., in the area of connector plug


28


. This clamping sleeve


40


and fuel injector


18


may be a single component.

FIG. 3

also shows connector plug


28


of fuel injector


18


, which in the embodiment shown in

FIG. 3

, is a fuel injector


18


having an electrically triggered actuator, and also partially shows tensioning device


29


, which is explained in detail with respect to

FIG. 5

below.





FIG. 4

shows detail section IV from FIG.


3


. First step ring


19


rests against clamping sleeve


40


of fuel injector


18


via valve pressure surface


20


. Second step ring


22


rests on a shoulder


30


of connection piece


25


of fuel distribution line


17


via counterpressure surface


23


. Circumferential slope surface


21


of first step ring


19


and circumferential slope surface


24


of second step ring


22


are formed so that radially inward they do not reach coaxial hole


31


of first step ring


19


and coaxial hole


32


of second step ring


22


. First step ring


19


has a shoulder


33


, which is held in a step


41


of coaxial hole


32


of second step ring


22


.




Fuel injector


18


and connection piece


25


of fuel distribution line


17


may be inserted into one another. The seal created by ring seal


39


may be checked when a pre-mounted unit that includes fuel injector


18


, the clamping element and fuel distribution line


17


is produced because, in the non-tensioned state, the exemplary clamping element according to the present invention may not exert any force on fuel injector


18


and fuel distribution line


17


, and therefore the components remain in the position relative to one another that they were in when checked. Furthermore, the exemplary clamping element according to the present invention may have small dimensions and be held by concentric holes


31


,


32


and smaller-diameter shoulder


36


of connection piece


25


. Moreover, shoulder


33


of first step ring


19


, which is held in step


41


of coaxial hole


32


of second step ring


22


, may help ensure that circumferential slope surfaces


21


,


24


are unable to move radially relative to one another.





FIG. 5

shows a top view of second step ring


22


across section plane V of FIG.


2


. The parts of fuel injector


18


and connection piece


25


of fuel injection line


17


that are located inside coaxial holes


31


,


32


of first step ring


19


and of second step ring


22


are not shown. As shown in

FIG. 5

, first step ring


19


is hidden by second step ring


22


. Tensioning device


29


includes a first double eye


42


, which is attached to first step ring


19


, and second double eye


43


, which is attached to second step ring


22


. A first bolt


44


is rotatably and axially movably mounted in first double eye.


42


. Correspondingly, a second bolt


45


is rotatably and axially movably mounted in second double eye


43


. Second bolt


45


has a threaded hole into which a screw


46


is inserted so that it extends transversely. Screw


46


is held in a hole of first bolt


44


and rests against first bolt


44


via a screw head


47


.




If this screw is rotated into the threaded hole of second bolt


45


, screw head


47


pulls second bolt


45


in the direction of first bolt


44


. First step ring


19


and second step ring


22


are rotated relative to one another via first double eye


42


and second double eye


43


and the clamping element is tensioned. As first step ring


19


and second step ring


22


move apart in the direction of the axes of bolts


44


,


45


, there may be a tendency for screw


46


to tilt in the threaded hole of second bolt


45


and the hole of first bolt


44


. To avoid this tendency, bolts


44


,


45


are axially movable, and therefore may compensate for the movement apart of first step ring


19


and second step ring


22


.





FIG. 6

shows a side view of an exemplary clamping element according to the present invention installed between a fuel distribution line


17


(only partly shown) and a fuel injector


18


(only partly shown) rotated by


900


relative to the side view in FIG.


2


. The same reference numbers have been used for the same components.





FIG. 6

shows fuel injector


18


having connector plug


28


and cylinder head


26


. First step ring


19


and second step ring


22


are located between connection piece


25


of fuel distribution line


17


and fuel injector


18


. First bolt


44


is held in first double eye


42


, which is connected to first step ring


19


. Screw head


47


rests against this first bolt


44


. First bolt


44


may be moved in the direction of its axis in first double eye


42


.




Screw head


47


is easily accessible with a tool because, as shown in

FIG. 6

, it may be arranged so that it points away from the internal combustion engine. The screw head


47


may be easily reached, since screw head


47


is not covered by other components and is reachable with an appropriate tool.



Claims
  • 1. A clamping arrangement for a fuel injector, which is insertable into a mounting bole of a cylinder head of an internal combustion engine to directly inject fuel into a combustion chamber of the internal combustion engine, the clamping arrangement comprising:a first step ring at least partially surrounding the fuel injector and resting on the fuel injector via a valve pressure surface, the first step ring including at least one first circumferential slope surface on a side of the first step ring facing away from the valve pressure surface; and a second step ring including at least one second circumferential slope surface and a counterpressure surface; wherein the at least one first circumferential slope surface of the first step ring engages with the at least one second circumferential slope surface of the second step ring, and the at least one first circumferential slope surface of the first step ring and the at least one second circumferential slope surface of the second step ring are arranged so that the first step ring and the second step ring are pressed axially apart when rotated relatively to one another.
  • 2. The clamping arrangement of claim 1, wherein each of the first step ring and the second step ring includes coaxial holes into which the fuel injector and a connection piece of a fuel distribution line are insertable.
  • 3. The clamping arrangement of claim 2, wherein at least one of the first step ring and the second step ring is held in the coaxial holes by a smaller-diameter shoulder of the connection piece of the fuel distribution line.
  • 4. The clamping arrangement of claim 1, wherein the first step ring and the second step ring are held concentrically with respect to each other by a shoulder of one of the first step ring and the second step ring, the shoulder engaging with a corresponding step of an axial hole of the other step ring.
  • 5. The clamping arrangement of claim 1, wherein the first step ring and the second step ring are held concentrically relative to one another by a sleeve situated in a common axial hole of the first step ring and the second step ring.
  • 6. The clamping arrangement of claim 1, further comprising a tensioning device, wherein each of the first step ring and the second step ring includes a tensioning element on its circumference, the tensioning device is provided between the tensioning elements of the first step ring and the second step ring, the first step ring and the second step ring being axially pressed apart if the tensioning elements are pulled toward one another.
  • 7. The clamping arrangement of claim 6, wherein each of the tensioning elements includes a bolt rotationally mounted so that an axis of the bolt is parallel to an axis of a corresponding step ring, each of the bolts being axially movable and penetrated by a transverse hole.
  • 8. The clamping arrangement of claim 7, wherein the transverse hole of one of the bolts includes a threaded hole, and the tensioning device includes a screw held in the transverse hole of the other bolt and engaging with the threaded hole.
  • 9. The clamping arrangement of claim 8, wherein the tensioning device is positioned on the circumference of the first step ring and the second step ring so that one axis of the screw is approximately perpendicular to a plane defined at least approximately by a rigid fuel distribution line along its longitudinal extension and by the fuel injector connected to it.
  • 10. The clamping arrangement of claim 1, wherein the at least one first circumferential slope surface of the first step ring and the at least one second circumferential slope surface of the second step ring resemble teeth of a saw.
  • 11. A fuel injection system comprising:a fuel distribution line; fuel injectors for directly injecting fuel into combustion chambers of an internal combustion engine, the fuel injectors connected to the fuel distribution line via connection nozzles, the fuel injectors insertable into mounting holes of a cylinder head of the internal combustion engine; and clamping elements, each of the clamping elements at least partially surrounding a corresponding fuel injector and including a first step ring at least partially surrounding the corresponding fuel injector and resting on the corresponding fuel injector via a valve pressure surface, the first step ring including at least one first circumferential slope surface on a side of the first step ring facing away from the valve pressure surface and a second step ring including at least one second circumferential slope surface and a counterpressure surface; wherein the at least one first circumferential slope surface of the first step ring engages with the at least one second circumferential slope surface of the second step ring, and are arranged so that the first step ring and the second step ring are pressed axially apart when rotated relatively to one another.
Priority Claims (1)
Number Date Country Kind
100 34 084 Sep 2000 DE
PCT Information
Filing Document Filing Date Country Kind
PCT/DE01/03260 WO 00
Publishing Document Publishing Date Country Kind
WO02/18777 3/7/2002 WO A
US Referenced Citations (6)
Number Name Date Kind
5121731 Jones Jun 1992 A
5140963 Brackett et al. Aug 1992 A
5970953 Lorraine et al. Oct 1999 A
6148797 Gmelin Nov 2000 A
6186123 Maier et al. Feb 2001 B1
6318341 Gmelin et al. Nov 2001 B1
Foreign Referenced Citations (4)
Number Date Country
197 35 665 Jan 1999 DE
197 56 102 Jun 1999 DE
0 969 203 Jan 2000 EP
08 312503 Nov 1996 JP