TECHNICAL FIELD
[0001] The present disclosure relates to a fuel rail assembly with the constrictor element
and to a fuel delivery assembly comprising the fuel rail assembly.
BACKGROUND
[0002] Fuel rail assemblies usually comprise a tubular fuel reservoir and a plurality of
fuel delivery lines which branch off from the fuel reservoir to connect the fuel rail
assembly hydraulically and mechanically to fuel injectors of an internal combustion
engine.
[0003] It is desirable to have an orifice in the fuel rail assembly between the fuel reservoir
and the fuel injectors. By means of such an orifice, pressure pulsations can be dampened
so as to decrease pressure peaks. In this way, a better functionality of the injector
and lower mechanical stress to the fuel rail assembly is achievable.
[0004] It is an object of the present disclosure to specify a fuel rail assembly which is
particularly reliable and/or producible with particularly small scrap costs. This
object is achieved by a fuel rail assembly having the features of the independent
claim. Advantageous embodiments and developments of the fuel rail assembly and a fuel
delivery assembly comprising the fuel rail assembly are specified in the dependent
claims, in the following description and in the drawings.
SUMMARY AND EMBODIMENTS
[0005] A fuel rail assembly is specified according to one aspect. The fuel rail assembly
is configured for delivering fuel to a plurality of fuel injectors. A fuel delivery
assembly comprising the fuel rail assembly and the fuel injectors is specified according
to another aspect. The fuel delivery assembly is preferably configured for delivering
fuel to an internal combustion engine.
[0006] The fuel rail assembly comprises a tubular fuel reservoir. The tubular fuel reservoir
can also be denoted as a main gallery. A plurality of outlet ports branch off from
the fuel reservoir. The fuel rail assembly further comprises a plurality of fuel delivery
lines. Each fuel delivery line is connected to a respective one of the outlet ports,
and is in particular configured for receiving a respective one of the fuel injectors.
[0007] Each fuel delivery line comprises a pipe and an injector cup. The pipe has a first
end which is hydraulically and mechanically connected to the respective outlet port
and a second end, remote from the first end, hydraulically and mechanically connected
to an inlet end of the injector cup. The injector cup has an outlet end, remote from
the inlet end, for receiving a respective one of the fuel injectors.
[0008] Each fuel injector may expediently have an inlet portion which is shifted into the
outlet end of the respective injector cup. In this way, the fuel injector is hydraulically
connected to the fuel reservoir so that fuel can be fed from the fuel reservoir through
the outlet port, the pipe and the injector cup to the injector.
[0009] Each fuel delivery line further comprises a constrictor element which has an orifice
extending through the constrictor element. The constrictor element is inserted into
the pipe so that an external surface of the constrictor element is in form-fit and/or
force-fit connection with an internal surface of the pipe. By means of the form-fit
and/or force-fit connection, in particular the displaceability of the constrictor
element in direction along the pipe from the first towards the second end and/or vice
versa is limited.
[0010] In the present context, that "an external surface of the constrictor element is in
form-fit and/or force-fit connection with an internal surface of the pipe" is understood
to include embodiments in which the constrictor element is movable relative to the
pipe so that it can engage into an disengage from the form fit and/or force fit connection
with the pipe. The constrictor element, however, may expediently be shaped, sized
and positioned in such fashion that it is in the form-fit and/or force-fit connection
with the pipe at least during producing connections between the outlet port and the
pipe and/or between the pipe and the injector cup during manufacturing of the fuel
rail assembly, the connections being in particular brazed connections.
[0011] With advantage, the constrictor element can be used for different fuel rail assembly
configurations by adapting its position. In addition, the size and/or the position
of the orifice of the constrictor element as well as other dimensions such as the
shape and the length of the constrictor element can be changed for different fuel
rail configurations by replacing the constrictor element without any further changes
to other components of the fuel rail assembly. The constrictor element is easily connectable
to the pipe. Due to the form fit and/or force fit connection, the position of the
constrictor element relative to the pipe can be easily adjusted during manufacturing
of the fuel rail assembly.
[0012] In one embodiment, the constrictor element is arranged adjacent to the first end
of the pipe and the pipe is connected to the outlet port by means of a brazed connection.
In an alternative embodiment, the constrictor element is arranged adjacent to the
second end of the pipe and the pipe is connected to the injector cup by means of a
brazed connection.
[0013] With advantage, due to the force-fit and/or form-fit connection of the external surface
of the constrictor element with the internal surface of the pipe, the constrictor
element or at least the inflow and outflow openings of the orifice may be positioned
at a distance from the respective brazed connection.
[0014] For example, the constrictor element is inserted into the pipe through the first
end and is offset, in its entirety, from the brazed connection of the pipe with the
outlet port in direction towards the injector cup along the pipe or the constrictor
element is inserted into the pipes from the second end and is offset, in its entirety,
from the brazed connection of the pipe with the injector cup in direction towards
the outlet port along the pipe. In another example, the inflow and outflow openings
of the orifice are offset in opposite directions along the pipe with respect to the
respective brazed connection. With advantage, the positioning may be reproducible
and particularly reliable in this way. The risk that brazing material obstructs the
orifice is particularly small. Therefore, scrap costs may be particularly small when
producing the fuel rail.
[0015] In one embodiment, the constrictor element is in the shape of a plug, in particular
in the shape of a cylindrical plug. In this case, the orifice preferably extends through
the constrictor element along the cylinder axis of the cylindrical plug. In another
embodiment, the constrictor element is in the shape of a cap having a circumferential
sidewall, in particular a cylindrical sidewall, and a cover portion which closes the
cap at one end of the circumferential sidewall. In this case, the orifice preferably
extends through the cover portion, in particular along a center axis of the circumferential
sidewall. With advantage, such constrictor elements are easily and cost efficiently
producible.
[0016] Expediently, a portion of the pipe may extend circumferentially around the constrictor
element and the constrictor element and its orifice are dimensioned such that the
constrictor element reduces the hydraulic diameter of said portion of the pipe by
25% or more, preferably by 50 % or more, and in particular by 90 % or less. In this
way, a particularly advantageous reduction of pressure peaks is achievable.
[0017] In one embodiment, in which the constrictor element is in force fit connection with
the pipe, the constrictor element is arranged in the pipe such that a portion of the
pipe extends circumferentially around the constrictor element, the internal surface
of said portion being in press-fit connection, i.e. in a force-fit connection, with
the external surface of the constrictor element. In this way, the position of the
constrictor element along the length of the pipe is particularly easily adjustable.
[0018] Preferably, surface portions of the constrictor element and of the pipe which are
in press-fit connection extend completely circumferentially around the constrictor
element at least in places so as to fluid tightly seal the interface between the internal
surface of the pipe and the constrictor element. In this way, particularly precise
adjustment of the hydraulic diameter of the fuel delivery line in the region of the
constrictor element is achievable.
[0019] In another embodiment, the pipe has a bend or kink which is operable to engage into
form-fit and/or force-fit connection with the constrictor element. In particular,
the pipe has a straight section comprising the first or second end, respectively,
of the pipe through which the constrictor element is inserted into the pipe. The bend
or kink may expediently delimit the straight section on the side remote from said
first or second end. In particular, the shape and size of the constrictor element
is adapted to the shape and size of the internal cross section of the straight section
and the bend in such fashion that the constrictor element is displaceable along the
straight portion to the bend, the bend limiting the displaceability of the constrictor
element along the pipe by form fit and/or force fit engagement.
[0020] In a preferred development of this embodiment, the constrictor element is in loose
fit engagement with the straight portion of the pipe. Thus, it can easily slide along
the straight portion of the pipe until it is stopped by the bend or kink.
[0021] For example in this embodiment, the constrictor element may be configured to move
along the pipe driven by gravity until it comes in contact with the bend or kink.
The bend or kink is in particular positioned such that the constrictor element, in
its entirety, is spaced apart from any brazed joints between the pipe and the outlet
port and the pipe and the injector cup when the constrictor element is in form-fit
and/or force-fit engagement with the bend or kink. In this way, a reproducible position
of the constrictor element during production of the brazed connections of the fuel
rail assembly is easily achievable.
[0022] In a further embodiment, the internal surface of the pipe and the external surface
of the constrictor element have corresponding threaded portions for establishing a
threaded connection between the constrictor element and the pipe. In this way, the
position of the constrictor element is easily and precisely adjustable.
[0023] In another embodiment, the internal surface of the pipe has a step which is operable
to engage in form-fit connection with the external surface of the constrictor element.
In particular, the step represents an interface between a larger cross-section portion
and a smaller cross-section portion of the pipe, the constrictor element being inserted
into the larger cross-section portion. The larger cross-section portion is in particular
a straight section of the pipe comprising the first or the second end, respectively,
through which the constrictor element is inserted into the pipe. By means of the step,
the displaceability of the constrictor element along the pipe can be easily and/or
precisely limited.
[0024] In yet another embodiment, the constrictor element is shifted into the first end
of the pipe and projects from the first end into the outlet port. For example in this
embodiment, the inflow opening of the orifice may be positioned inside the tubular
fuel reservoir and the outflow opening may be positioned inside the pipe and spaced
apart from the brazed connection between the pipe and the outlet port on the side
of the brazed connection facing away from the fuel reservoir and towards the injector
cup. In this way, a particularly good damping function of the constrictor element
and/or a particularly small risk that brazing material obstructs the orifice are achievable.
[0025] In an alternative embodiment, the constrictor element is shifted into the first end
of the pipe such that it is arranged completely inside the pipe and spaced apart from
the first end and in particular spaced apart from a brazed connection between the
respective outlet port and the pipe in direction towards the injector cup. Such a
fuel rail assembly is particularly easily manufacturable and/or cost-efficient.
[0026] In another alternative embodiment, the constrictor element is shifted into the second
end of the pipe so that it is arranged subsequent to the inlet end of the injector
cup in direction towards the respective outlet port of the fuel reservoir. In this
way, the dampening function of the orifice may be achieved particularly close to the
fuel injector. Further, the inlet end of the injector cup may limit displacability
of the constrictor element. In this way, accidental removal of the constrictor element
through the second end of the pipe may be reliably prevented even if the constrictor
element is only in loose-fit connection with the pipe.
[0027] In one development of this embodiment, the internal surface of the pipe and the external
surface of the constrictor element have corresponding threaded portions for establishing
a threaded connection between the constrictor element and the pipe and the fuel delivery
line further comprises a brazed connection connecting the pipe and the injector cup.
The brazed connection may preferably be located in a region subsequent to the threaded
portions in direction towards the inlet end of the injector cup. In this way, the
risk for brazing material flowing into the threaded portions during manufacturing
of the fuel rail assembly is particularly small.
[0028] In another development of this embodiment, the internal surface of the pipe has a
step, herein also denoted as a first step, which is operable to engage in form-fit
connection with the external surface of the constrictor element. In addition, the
internal surface of the pipe has a further step positioned between said first step
and the inlet end of the injector cup. The fuel delivery line may further comprise
a brazed connection connecting the pipe and the injector cup in a region subsequent
to the further step in direction away from said first step. Preferably, the cross-section
of the pipe increases at the step and at the further step in direction towards the
second end of the pipe. In this way, the constrictor element can be inserted through
the second end into the pipe and its displaceability is limited by the first step.
At the same time, for example a ring of brazing material, having a larger cross-section
than the constrictor element, can also be inserted through the second end into the
pipe and is stopped by the further step preceding the first step in direction from
the second end towards the first end of the pipe. In this way, the constrictor element
and the brazing material can be reliably kept at a distance during production of the
fuel rail assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Further advantages, advantageous embodiments and developments of the fuel rail assembly
and the fuel delivery assembly will become apparent from the exemplary embodiments
which are described below in association with the figures.
[0030] In the figures:
- Figure 1
- shows a sectional view of a portion of a fuel rail assembly according to a first exemplary
embodiment,
- Figure 2
- shows a sectional view of a portion of a fuel rail assembly according to a second
exemplary embodiment,
- Figure 3
- shows a sectional view of a portion of a fuel delivery assembly according to a third
exemplary embodiment,
- Figure 4
- shows a sectional view of a portion of the fuel delivery assembly according to a fourth
exemplary embodiment, and
- Figure 5
- shows a schematic exploded view of a portion of a fuel delivery assembly comprising
the fuel rail assembly according to the first embodiment and a fuel injector.
DETAILED DESCRIPTION OF EMBODIMENTS
[0031] In the exemplary embodiments and figures, similar, identical or similarly acting
elements are provided with the same reference symbols. In some figures, individual
reference symbols may be omitted to improve the clarity of the figures.
[0032] Figure 1 shows a sectional view of a portion of the fuel rail assembly 1 according
to a first exemplary embodiment. The fuel rail assembly 1 makes part of a fuel delivery
assembly, a portion of which is schematically shown in the exploded view of figure
5.
[0033] The fuel rail assembly 1 comprises a tubular fuel reservoir 20 and a plurality of
fuel delivery lines 23 which branch off at outlet ports 22 on the fuel reservoir 20.
Each fuel delivery line has a pipe 231 and an injector cup 233. A first end 2311 of
the pipe 231 is shifted into the outlet port 22. A second end 2312 of the pipe 231,
remote from the outlet port 22, is hydraulically and mechanically connected to the
injector cup 233.
[0034] The fuel delivery assembly comprises a plurality of fuel injectors 2, each fuel injector
2 being shifted into an outlet end 2332 of the injector cup 233 of a respective fuel
delivery line 23 of the fuel rail assembly 1 for hydraulically connecting the fuel
injector 2 to the fuel rail assembly 1. In the exploded view of figure 5, the inlet
portion 11 of the fuel injector 2 is visible outside the injector cup 233.
[0035] The fuel injector 2 and the injector cup 233 may have corresponding indexing features
for setting a predetermined angular position of the fuel injector 2 with respect to
the injector cup 233. In the present embodiment the indexing features are a tab projecting
from the outlet end 2332 of the injector cup 233 and a corresponding pocket in a housing
of the fuel injector 2.
[0036] The fuel delivery assembly of this and other embodiments is preferably configured
for delivering fuel to an internal combustion engine, in particular for injecting
fuel directly into individual cylinders of the internal combustion engine (not shown
in the figures). The fuel delivery assembly is preferably configured for being fixed
to a cylinder head (not shown in the figures) of the internal combustion engine. For
fixing to the cylinder head, the fuel rail assembly 1 has one or more brackets 24
which is/are, for example, configured for receiving a bolt that may be screwed into
or otherwise fixed to the cylinder head.
[0037] Only one fuel delivery line 23 is shown in figures 1 and 5. However, the fuel rail
assembly 1 preferably has a fuel delivery line 23 associated to each of the cylinders
of the internal combustion engine. Preferably, the fuel delivery lines 23 follow one
another along an elongation direction of the tubular fuel reservoir 20.
[0038] In the present embodiment, the outlet ports 22 are fixed to an outer surface of a
circumferential wall of the tubular fuel reservoir 20 and connected to the interior
of the fuel reservoir 20 by means of respective bores through the circumferential
wall. Each bore is expediently laterally enclosed by their respective outlet port
22.
[0039] The first end 2311 of the pipe 231 of each fuel delivery line 23 is shifted into
the corresponding outlet port 22 from the side of the outlet port 22 remote from the
fuel reservoir 20. The second end 2312 of the pipe 231 receives an inlet end 2331
of the injector cup 233.
[0040] The first ends 2311 of the pipes 231 are hydraulically and mechanically connected
to the outlet ports 22 by means of brazed connections 71. The outlet ports 22 are
hydraulically and mechanically connected to the fuel reservoir 20 by brazed connections
72. Further, the second ends 2312 of the pipes 231 are hydraulically and mechanically
connected to the inlet ends 2331 of the injector cups 233 by means of brazed connections
73 (see also the third exemplary embodiments discussed below in connection with Fig.
3). In the fuel rail assembly 1 according to the present embodiment, the brackets
24 are fixed to the respective pipes 231 also by brazed connections 74.
[0041] Each fuel delivery line 23 has a constrictor element 235 which, in the present embodiment,
is shifted into the pipe 231 through the first end 2311 and arranged adjacent to the
first end 2311. In the present embodiment, the constrictor element 235 is in the shape
of a cylindrical plug having an orifice 2355 which extends centrally through the plug
along its cylinder axis. The diameter of the orifice 2355 has a value of, for example,
15% to 25% - e.g. of 20% - of an external diameter of the constrictor element 235,
the limits being included. The external diameter of the constrictor element 235 is
identical - or at least almost identical - to the internal diameter of the portion
2315 of the pipe 231 which extends circumferentially around the concert elements 235.
Therefore, the constrictor element 235 reduces the hydraulic diameter of said portion
2315 of the pipe 231 by 75% to 85%, the limits being included; e.g. it reduces the
hydraulic diameter by 80%.
[0042] The constrictor element 235 is dimensioned such that it can slide along a straight
end section which comprises the first end 2311 of the pipe 231. A circumferential
portion of the external surface 2353 of the constrictor element 235 is in loose-fit
connection with an internal surface 2314 of the pipe 231. In particular, the external
diameter of the constrictor element 235 corresponds almost to the internal diameter
of the straight section of the pipe 231, but being a little smaller so that the internal
surface 2314 of the pipe 231 and the external surface 2353 of the constrictor element
235 are in sliding contact.
[0043] In the present embodiment, the pipe 231 has a bend 2316. Due to the respective sizes
and shapes, the bend 2316 limits the displaceability of the constrictor element 235
along the pipe 231 in direction away from the first end 2311 by form-fit and/or force-fit
engagement. Typically, the bend 2316 limits the movement of the plug-shaped constrictor
element 235 by a combination of force-fit and form-fit engagement.
[0044] For producing the fuel rail assembly 1, rings of a brazing material, e.g. copper,
are inserted into the outlet port 22 for producing the brazed connections 71 and 72.
For example, a ring of brazing material is positioned between the first end 2311 of
the pipe 231 and a surface portion of the outlet port 22 in a recess of the outlet
port 22 which receives the pipe 231 and the ring of brazing material. For example,
the first end 2311 of the pipe 1231 locks the ring of brazing material in the recess
during manufacturing of the fuel rail assembly 1. In this and other embodiments, the
brazing material can have other shapes instead of a ring shape. For example, the brazing
material can be in the shape of a washer or the like.
[0045] The constrictor element 235 is spaced apart from the first end 2311 of the pipe 231
and from the ring of brazing material and is arranged subsequent to the outlet port
22 in direction towards the injector cup 233 along the pipe 231 when it is in form-fit
and/or force-fit connection with the bend 2316 of the pipe 231. During production
of the brazed connections 71, 72, the pipe 231 is preferably positioned such that
gravity forces the constrictor element 235 into the form-fit and/or force-fit connection
with the bend 2316. Therefore, when the brazing material rings melt, there is only
a small risk that brazing material flows into the orifice 2355. Brazing material flowing
into the orifice 2355 could lead to obstruction of the orifice 2355 by the brazing
material and to a malfunction of the fuel rail assembly 1.
[0046] Figure 2 shows a portion of a fuel rail assembly 1 according to a second exemplary
embodiment in a sectional view. The fuel rail assembly 1 according to the second embodiment
corresponds in general to the fuel rail assembly according to the first embodiment.
[0047] However, in the present embodiment, the constrictor element 235 is not in loose-fit
connection with the pipe 231. Rather, the constrictor element 235 is press-fitted
into the straight end section of the pipe 231 so that the circumferential portion
of its external surface 2353 and the internal surface 2314 of the straight portion
2315 of the pipe 231 which extends circumferentially around the constrictor element
235 are in force-fit engagement with one another.
[0048] In the present embodiment, the constrictor element 235 projects beyond the first
end 2311 of the pipe 231 into the outlet port 22 and further through the outlet port
22 and through the bore in the circumferential sidewall into the interior of the tubular
fuel reservoir 20. In this way, the inflow opening of the orifice 2355 is positioned
in the interior of the fuel reservoir 20. The outflow opening of the orifice 2355
is positioned inside the pipe 231, offset in direction from the first end 2311 towards
the second end 2312 along the pipe 231 with respect to the brazed connections 71,
72, the outlet port 22 and the first end 2311 of the pipe 231.
[0049] Figure 3 shows a portion of a fuel delivery assembly according to a third exemplary
embodiment in a sectional view. The fuel delivery assembly corresponds in general
to the fuel delivery assembly described in connection with figures 1 and 5. The portion
shown in figure 3 comprises the second end 2312 of the pipe 231, the injector cup
233 and the inlet end 11 of the fuel injector 2. The inlet end 11 of the fuel injector
2 is shifted into the injector cup 233 through the outlet end 2332 of the injector
cup 233.
[0050] The injector cup 233 has a nipple 2335 at its inlet end 2331 which is shifted into
the pipe 231 through the second end 2312 thereof and connected to the pipe 231 by
means of a brazed connection 73. Such a configuration may also be useful for other
embodiments of the fuel rail assembly 1, and may, for example, be realized in the
first and second embodiments described above.
[0051] In contrast to the first and second embodiments, the constrictor element 235 is not
arranged adjacent to the first end 2311 of the pipe 231, but adjacent to the second
end 2312 of the pipe 231. It is inserted into the pipe 231 through the second end
2312. A form-fit and force-fit connection between the external surface 2353 of the
constrictor element 235 and the internal surface 2314 of the pipe 231 is established
by a threaded connection between threaded portions 2317, 2357 of the pipe 231 and
of the constrictor element 235, respectively.
[0052] In the present embodiment, the constrictor element 235 is also not shaped as a cylindrical
plug, but it has the shape of a cap screw with a circumferential sidewall having a
hollow cylindrical basic shape and with a cover portion closing the sidewall at one
axial end thereof. The sidewall expediently comprises the threaded portion 2357 of
the constrictor element 235 at its external surface. Preferably, the sidewall has
a hexagonal internal cross-section so that the constrictor element 235 represents
a hexagon socket head cap screw. The cover portion may expediently comprise the orifice
2355 in the present embodiment of the constrictor element 235.
[0053] A constrictor element 235 having such a shape may also be useful for other embodiments
of the fuel rail assembly 1. It is also conceivable to use a plug shaped constrictor
element 235 in the present embodiment, such as described in detail above. However,
the constrictor element 235 in the shape of a hexagon socket head cap screw is particularly
advantageous for establishing the threaded connection between the threaded portions
2317, 2357.
[0054] In the present embodiment, the constrictor element 235 is shifted into the second
end 2312 of the pipe 231 so that it is arranged subsequent to the inlet end 2331 of
the injector cup 233 in direction towards the outlet port 22 of the fuel reservoir
20 along the pipe 231, i.e. in upstream direction along the pipe 231. Further, the
constrictor element 235 is offset from the brazed connection 73 between the pipe 231
and the injector cup 233 in direction towards the first end 2311 of the pipe 231.
In other words, the brazed connection 73 is arranged in a region subsequent to the
threaded portions 2317, 2357 in direction towards the inlet end 2331 of the injector
cup 233 and towards the second end 2312 of the pipe 231, i.e. in downstream direction
along the pipe 231. Therefore, also in this embodiment, the risk for brazing material
to obstruct the orifice 2355 is particularly small.
[0055] Figure 4 shows a sectional view of a portion of a fuel delivery assembly according
to a fourth exemplary embodiment. The fuel delivery assembly according to the fourth
embodiment corresponds in general to the fuel delivery assembly according to the third
embodiment.
[0056] In contrast thereto, the constrictor element 235 is shaped as a cylindrical plug
like in the first embodiment, not as a hexagonal socket head cap screw as in the third
embodiment. Correspondingly, the pipe 231 and the constrictor element 235 do not have
threaded portions 2317, 2357 as in the third embodiment.
[0057] Rather, the internal surface 2314 of the pipe 231 has a first step 2318 which is
shaped and arranged to limit axial displaceability of the constrictor element 235
in direction towards the first end 2311 of the pipe 231 by means of a form-fit connection
with the external surface 2353 of the constrictor element 235, in particular with
a front surface of the constrictor element 235. In addition, a circumferential portion
of the external surface 2353 of the constrictor element 235 may be in a force-fit
connection with the internal surface 2314 of a portion 2315 of the pipe 231 which
extends circumferentially around the constrictor element 235. In this way, a predetermined
position of the constrictor element 235 relative to the pipe 231 may be reliably set
by means of the form fit connection with the first step 2318 and the position may
be reliably retained against vibrations and gravity due to the force-fit connection
with the internal surface 2314 of the pipe 231.
[0058] In addition to the above-mentioned first step 2318, the pipe 231 comprises a further
step 2319 which is positioned between the first step 2318 and the second end 2312
of the pipe 231. The internal diameter of the pipe 231 decreases in stepwise fashion
in direction from the second end 2312 towards the first end 2311 of the pipe 231 at
the second step 2319 from a first to a second diameter and subsequently at the first
step 2318 from the second to a third diameter. The external diameter of the constrictor
element is larger than the third diameter, smaller than the first diameter and preferably
has almost the same value as the second diameter so as to allow press fitting of the
constrictor element 235 into the pipe 231 through the second end 2312 thereof until
it is stopped at the first step 2318.
[0059] For producing the fuel rail assembly 1 of the fuel delivery assembly according to
the fourth embodiment, a ring of brazing material, e.g. a copper ring, may be inserted
through the second end 2312 of the pipe 231 to engage in form fit connection with
the further step 2319. During production of the brazed connection 73 between the pipe
231 and the injector cup 233, displaceability of the ring of brazing material is expediently
limited by the further step 2319 and by the nipple 2335 of the injector cup 233 in
opposite directions along the pipe 231.
[0060] Analogously to the third embodiment, the constrictor element 235 may in this way
be offset along the pipe 231 in direction towards the first end 2311 of the pipe 231
with respect to the inlet end 2331 of the injector cup 233 and to the brazed connection
73.
[0061] The invention is not limited to specific embodiments by the description on basis
of these exemplary embodiments. Rather, it comprises any combination of elements of
different embodiments. Moreover, the invention comprises any combination of claims
and any combination of features disclosed by the claims.
1. Fuel rail assembly (1) for delivering fuel to a plurality of fuel injectors (2) comprising
a tubular fuel reservoir (20) with a plurality of outlet ports (22) and a fuel delivery
line (23) connected to each of the outlet ports (22), wherein
each fuel delivery line (23) comprises a pipe (231) and an injector cup (233), the
injector cup (233) having an outlet end (2332) for receiving a respective one of the
fuel injectors (2),
the pipe (231) has a first end (2311) which is hydraulically and mechanically connected
to the respective outlet port (22) and a second end (2312), remote from the first
end (2313), hydraulically and mechanically connected to an inlet end (2331) of the
injector cup (233), remote from the outlet end (2332),
each fuel delivery line (23) further comprises a constrictor element (235) which has
an orifice (2355) extending through the constrictor element (235),
the constrictor element (235) is inserted into the pipe (231) so that an external
surface (2353) of the constrictor element (235) is in form-fit and/or force-fit connection
with an internal surface (2314) of the pipe (231).
2. Fuel rail assembly (1) according to the preceding claim, wherein the constrictor element
(235) is arranged adjacent to the first end (2311) of the pipe (231) and the pipe
(231) is connected to the outlet port (22) by means of a brazed connection (71) or
wherein the constrictor element (235) is arranged adjacent to the second end (2312)
of the pipe (231) and the pipe (231) is connected to the injector cup (233) by means
of a brazed connection (72).
3. Fuel rail assembly (1) according to one of the preceding claims, wherein the constrictor
element (235) is arranged in the pipe (231) such that a portion (2315) of the pipe
(231) extends circumferentially around the constrictor element (235), the internal
surface (2314) of said portion (2315) being in press-fit connection with the external
surface (2353) of the constrictor element (235).
4. Fuel rail assembly (1) according to one of the preceding claims, wherein the pipe
(231) has a bend (2316) or kink which is operable to engage into form-fit and/or force-fit
connection with the constrictor element (235).
5. Fuel rail assembly (1) according to one of the preceding claims, wherein the internal
surface (2314) of the pipe (231) and the external surface (2353) of the constrictor
element (235) have corresponding threaded portions (2317, 2357) for establishing a
threaded connection between the constrictor element (235) and the pipe (231).
6. Fuel rail assembly (1) according to one of the preceding claims, wherein the internal
surface (2314) of the pipe (231) has a step (2318) which is operable to engage in
form-fit connection with the external surface (2353) of the constrictor element (235).
7. Fuel rail assembly (1) according to one of the preceding claims, wherein the constrictor
element (235) is shifted into the first end (2311) of the pipe (231) and projects
from the first end (2311) into the outlet port (22).
8. Fuel rail assembly (1) according to one of the preceding claims 1 to 6, wherein the
constrictor element (235) is shifted into the first end (231) of the pipe (231) such
that it is arranged completely inside the pipe (231) and spaced apart from the first
end (2311) and in particular spaced apart from a brazed connection (71) between the
respective outlet port (22) and the pipe (231) in direction towards the injector cup
(233).
9. Fuel rail assembly according to one of the preceding claims 1 to 6, wherein the constrictor
element (235) is shifted into the second end (2312) of the pipe so that it is arranged
subsequent to the inlet end (2331) of the injector cup (233) in direction towards
the respective outlet port (22) of the fuel reservoir (20).
10. Fuel rail assembly (1) according to claims 9 and 5,
wherein the fuel delivery line (23) further comprises a brazed connection (73) connecting
the pipe (231) and the injector cup (233) in a region subsequent to the threaded portions
(2317, 2357) in direction towards the inlet end (2331) of the injector cup (233).
11. Fuel rail assembly (1) according to claims 9 and 6,
wherein the internal surface (2314) of the pipe (231) has a further step (2319) positioned
between said step (2318) and the inlet end (2331) of the injector cup (233), the fuel
delivery line (233) further comprising a brazed connection (73) connecting the pipe
(231) and the injector cup (233) in a region subsequent to the further step (2319)
in direction away from said step (2318) which is operable to engage in form-fit connection
with the external surface (2353) of the constrictor element (235).
12. Fuel rail assembly (1) according to one of the preceding claims, wherein a portion
(2315) of the pipe (231) extends circumferentially around the constrictor element
(235) and the constrictor element (235) and its orifice (2355) are dimensioned such
that the constrictor element (235) reduces the hydraulic diameter of said portion
(2315) of the pipe (231) by 50 % or more and in particular by 90 % or less.
13. Fuel delivery assembly comprising a fuel rail assembly (1) according to one of the
preceding claims and the fuel injectors (2), wherein each fuel injector (2) has an
inlet portion (11) which is shifted into the outlet end (2332) of the respective injector
cup (233).