U.S. patent application number 10/503446 was filed with the patent office on 2005-04-21 for radial piston pump with flat seal between flange and housing.
Invention is credited to Boos, Burkhard, Distel, Matthias, Schoetz, Alfons.
Application Number | 20050084389 10/503446 |
Document ID | / |
Family ID | 32185685 |
Filed Date | 2005-04-21 |
United States Patent
Application |
20050084389 |
Kind Code |
A1 |
Boos, Burkhard ; et
al. |
April 21, 2005 |
Radial piston pump with flat seal between flange and housing
Abstract
A radial piston pump, having a flange and a housing, a pump
element in the housing, and an eccentric drive shaft that actuates
a piston in the pump element radial to the drive shaft, which
piston seals a pump volume which upon expansion, delivers fuel from
an inlet chamber into the pump volume and upon contraction, exerts
pressure on the fuel in the pump volume and conveys it out at a
high pressure, having an inner chamber that contains the
eccentricity, and having a parting plane that extends between the
housing part and flange part and intersects the inner chamber and
the inlet chamber. A one-piece flat seal is disposed in the parting
plane and seals the inlet chamber, the inner chamber, and the
environment of the radial piston pump in relation to one
another.
Inventors: |
Boos, Burkhard; (Lambsborn,
DE) ; Schoetz, Alfons; (Ditzingen, DE) ;
Distel, Matthias; (Ostifildern, DE) |
Correspondence
Address: |
Ronald E Greigg
Greigg & Greigg
1423 Powhatan Street
Suite One
Alexandria
VA
22314
US
|
Family ID: |
32185685 |
Appl. No.: |
10/503446 |
Filed: |
August 4, 2004 |
PCT Filed: |
August 11, 2003 |
PCT NO: |
PCT/DE03/02705 |
Current U.S.
Class: |
417/273 ;
417/269 |
Current CPC
Class: |
F04B 1/0421 20130101;
F04B 1/0448 20130101 |
Class at
Publication: |
417/273 ;
417/269 |
International
Class: |
F04B 001/12; F04B
027/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 15, 2002 |
DE |
102531897 |
Claims
1-10. (canceled)
11. A radial piston pump (10) comprising a flange part (14), a
housing part (12), an inner chamber (60), and an inlet chamber
(34), at least one pump volume (30) disposed in the housing part
(12) and sealed by a moving piston (28), an eccentric drive shaft
(18) that extends in the axial direction through the inner chamber
(60) and actuates the piston (28) in the radial direction so that
the piston (28) delivers fuel from the inlet chamber (34) into the
pump volume (30), exerts pressure on the fuel in the pump volume
(30), and conveys it out of the pump volume (30) at a high
pressure, a parting plane (16) that extends between the housing
part (12) and flange part (14) and intersects the inlet chamber
(34), and a one-piece flat seal (70) disposed in the parting plane
(16) and sealing the inlet chamber (34) in relation to the
environment of the radial piston pump (10).
12. The radial piston pump (10) according to claim 11, wherein the
parting plane (16) intersects the inlet chamber (34) and inner
chamber (60), with the one-piece flat seal (70) sealing the inner
chamber (60) in relation to the inlet chamber (34) and sealing the
inlet chamber (34) in relation to the environment.
13. The radial piston pump (10) according to claim 11, wherein the
flat seal (70) has a sheet metal layer (94).
14. The radial piston pump (10) according to claim 12, wherein the
flat seal (70) has a sheet metal layer (94).
15. The radial piston pump (10) according to claim 13, wherein the
sheet metal layer (94) has a coating (96).
16. The radial piston pump (10) according to claim 14, wherein the
sheet metal layer (94) has a coating (96).
17. The radial piston pump (10) according to claim 15, wherein the
coating (96) contains elastic plastic material.
18. The radial piston pump (10) according to claim 16, wherein the
coating (96) contains elastic plastic material.
19. The radial piston pump (10) according to claim 11, wherein the
flat seal (70) has a bead (82) that extends between the inner
chamber (60) and the inlet chamber (34) in the installed
position.
20. The radial piston pump (10) according to claim 11, wherein the
flat seal (70) has a bead (84) that extends between the inlet
chamber (34) and the environment in the installed position.
21. The radial piston pump (10) according to claim 19, wherein the
flat seal (70) has a bead (84) that extends between the inlet
chamber (34) and the environment in the installed position.
22. The radial piston pump (10) according to claim 13, wherein the
sheet metal layer (94) is 0.1 to 0.3 mm thick.
23. The radial piston pump (10) according to claim 15, wherein the
sheet metal layer (94) is 0.1 to 0.3 mm thick.
24. The radial piston pump (10) according to claim 17, wherein the
sheet metal layer (94) is 0.1 to 0.3 mm thick.
25. The radial piston pump (10) according to claim 19, wherein the
sheet metal layer (94) is 0.1 to 0.3 mm thick.
26. The radial piston pump (10) according to claim 19, wherein the
bead is 0.2 to 0.4 mm high.
27. The radial piston pump (10) according to claim 20, wherein the
bead is 0.2 to 0.4 mm high.
28. The radial piston pump (10) according to claim 11, wherein the
inlet chamber (34) is supplied with fuel at least in part by means
of grooves (74) that are disposed in the housing (12) or flange
(14) and are open toward the parting plane (16).
29. The radial piston pump (10) according to claim 12, wherein the
inlet chamber (34) is supplied with fuel at least in part by means
of grooves (74) that are disposed in the housing (12) or flange
(14) and are open toward the parting plane (16).
30. The radial piston pump (10) according to claim 13, wherein the
inlet chamber (34) is supplied with fuel at least in part by means
of grooves (74) that are disposed in the housing (12) or flange
(14) and are open toward the parting plane (16).
Description
PRIOR ART
[0001] The invention relates to a radial piston pump, having
[0002] a flange part, a housing part, an inner chamber, and an
inlet chamber,
[0003] at least one pump volume disposed in the housing part and
sealed by a moving piston,
[0004] an eccentric drive shaft that extends in the axial direction
through the inner chamber and actuates the piston in the radial
direction so that the piston delivers fuel from the inlet chamber
into the pump volume, exerts pressure on the fuel in the pump
volume, and conveys the fuel out of the pump volume at a high
pressure, and
[0005] a parting plane that extends between the housing part and
the flange part and intersects the inlet chamber.
[0006] Radial piston pumps of this type are used in injection
systems for combustion processes, in particular to generate
injection pressures of over 1000 bar in common rail direct
injection systems for combustion processes.
[0007] A radial piston pump of this type is described in DE 1 98 48
035.
[0008] In the known radial piston pump, a low-pressure pump
supplies the inlet chamber with fuel by means of a controllable
metering unit via bores and conduits that extend inside the flange
and housing. As a rule, a radial piston pump has a number of pump
elements that are disposed radial to a central drive shaft. The
fuel supply of pump volumes of the pump elements occurs on the side
oriented away from the drive mechanism and therefore, viewed in the
radial direction, away from the middle of the pump, in outer
regions of the radial piston pump.
[0009] Fuel is often supplied to the individual pump elements by
means of radially arranged conduits that extend through the flange,
parallel to the parting plane and feed into a central supply line
that is shared by all of the pump elements. The central supply line
is supplied with fuel via a supply conduit that extends axially
through the radial piston pump and passes through the parting plane
between the flange and housing.
[0010] In a similar fashion, the pump volumes of the pump elements,
which are disposed at the outermost radial periphery, are each
connected to their respectively associated radially outward
extending supply bores by means of axially disposed conduits. In
the known radial piston pump, these conduits also pass through the
parting plane between the flange and housing. In addition,
depending on the design of the radial piston pump, the parting
plane has still other conduits passing through it, for example a
conduit that is used to ventilate the inner chamber and an inlet
line for a low-pressure fuel delivery pump flange-mounted to the
radial piston pump.
[0011] Another opening in the flange and housing comprises the
guide of the axially and centrally disposed drive shaft. In the
known radial piston pump, the openings mentioned above are
rotationally symmetrical. As a rule, the inner chamber of the
radial piston pump in which the drive shaft rotates is filled with
fuel. But the fuel pressure in the inner chamber is not the same as
the fuel pressure in the inlet chamber.
[0012] In order to prevent undesirable fuel flows between the inner
chamber and the inlet chambers and associated supply conduits,
which could impair the supply of fuel to the pump volumes, the
inlet chambers must be sealed in relation to the inner chamber.
Furthermore, the fuel-carrying inlet chambers and supply conduits
disposed on the radial periphery must be sealed in relation to the
environment so that the pump as a whole is sealed. For this reason,
all of the fuel-carrying conduits and/or chambers that are
intersected by the parting plane are sealed in the parting plane.
In the known radial piston pump, these seals are produced by a
large number of O-rings made of elastomer material.
[0013] In the manufacture of a radial piston pump, this type of
seal is relatively expensive. Each one of the large number of
O-rings must be inserted exactly into a recess provided to
accommodate it in the surface of the flange and/or housing. Such a
recess must be produced for each O-ring through a corresponding
removal of material, for example by milling, drilling, cutting, or
turning.
[0014] Furthermore, O-rings achieve a reliable sealing action only
when installed in the form of a ring, which inevitably involves
structural and production engineering disadvantages in the
manufacture of the radial piston pump. Thus, for example, the
radially extending connecting conduit between a supply line
disposed centrally in the radial piston pump and the connection on
the radial periphery to a pump volume must be routed on the inside
of the flange or housing and be connected by means of a bore in the
parting plane.
[0015] As a rule, the radially extending bore is produced by
drilling radially inward from the outside. The intrinsically
undesirable drilled holes that remain in the outer wall of the
radial piston pump are closed, for example, by means of
press-fitted sealing balls made of metal. This closing of the bores
represents an additional work cycle in the manufacturing process
and complicates production. In principle, the press-fitted balls
also represent a deviation from the ideal of a pump housing that is
sealed to the greatest degree possible.
[0016] In principle, the O-rings used in the dividing plane itself
are also susceptible to aging and thus represent a possible leak
source during subsequent operation of the radial piston pump.
[0017] The object of the invention, therefore, is to disclose a
seal between a flange part and a housing part in a radial piston
pump that does not have the above-mentioned disadvantages.
[0018] This object is attained in a radial piston pump of the kind
mentioned at the beginning by means of a one-piece flat seal that
is disposed in the parting plane and seals the inlet chamber in
relation to the environment of the radial piston pump.
ADVANTAGES OF THE INVENTION
[0019] This embodiment has the advantage that a one-piece flat seal
can be installed with particular ease and reliability since a
correct positioning of just two points of the flat seal results in
the correct positioning of all of the remaining points. This
prevents sealing structures from slipping unnoticed into central
regions of the radial piston pump during assembly, particularly at
the moment that the flange and housing are fitted together.
[0020] It is also no longer necessary to maintain a supply of
different sized O-rings since all of the different sizes of sealing
contours can be taken into account in the design of the flat
seal.
[0021] Another advantage is that a flat seal permits the embodiment
of sealing contours other than the circular form of O-rings. This
advantageously permits additional latitudes in the construction of
the parts that are to be sealed, as explained in detail further
below.
[0022] It is preferable for the parting plane to intersect the
inlet chamber and the inner chamber and for the one-piece flat seal
to seal the inner chamber from the inlet chamber and the inlet
chamber from the environment.
[0023] This embodiment has the advantage that a tight separation of
the inlet chamber, both from the inner chamber and from the
environment, can be achieved by a single component, i.e. the flat
seal.
[0024] It is also preferable for the flat seal to have a sheet
metal layer.
[0025] Sheet metal seals withstand aging and exposure to fuel and
are also dimensionally stable and inexpensive.
[0026] It is also preferable for the sheet metal seal to have a
coating.
[0027] A coating can further improve the sealing action of the
sheet metal seal, particularly if it contains a flexible, elastic
material.
[0028] It is therefore also preferable for the coating to contain
an elastic plastic material.
[0029] It is also preferable for the flat seal to have a bead that
extends between the inner chamber and the inlet chamber in the
installed position.
[0030] The bead further improves the sealing action of the flat
seal so that a particularly good seal is produced between the inner
chamber and the inlet chamber.
[0031] It is also preferable for the flat seal to have a bead that
extends between the inlet chamber and the environment in the
installed position.
[0032] This bead also further improves the sealing action of the
flat seal so that a particularly good seal is produced between the
inlet chamber and the environment.
[0033] It is also preferable for the sheet metal to be 0.1 to 0.3
mm thick.
[0034] It is also preferable for the bead to be 0.2 to 0.4 mm
high.
[0035] These dimensions have produced particularly reliable
seals.
[0036] It is also preferable for the inlet chamber to be supplied
with fuel at least in part by means of grooves that are disposed in
the housing or flange and are open toward the parting plane.
[0037] This embodiment relates to the above-mentioned possibility
of using the flat seal to also produce sealing contours that
deviate from the circular shape of O-rings. It is therefore no
longer necessary to route the above-mentioned radially extending
fuel conduit inside the flange material or housing material and
then to connect the conduit by means of bores that pass through the
parting plane.
[0038] When a flat seal is used, it is instead possible to place
conduits, in particular even radially aligned conduits, in the
parting plane, thus producing e.g. rectangular edges to be sealed.
The sealing action can then be achieved, for example, by beads of
an adapted form, which extend around the open conduits disposed in
the parting plane.
[0039] Other advantages ensue from the specification and the
accompanying figures.
[0040] It should be understood that the features mentioned above
and those that will be explained below can be used not only in the
respectively indicated combinations, but can also be used in other
combinations or individually without going beyond the scope of the
current invention.
[0041] Exemplary embodiments of the invention are shown in the
drawings and will be explained in detail in the subsequent
description.
DRAWINGS
[0042] FIG. 1 is a schematic sectional view of a radial piston pump
according to the prior art, when assembled;
[0043] FIG. 2 is a schematic top view of the flange from FIG.
1;
[0044] FIG. 3 is a schematic sectional view of a radial piston pump
as an exemplary embodiment of the invention;
[0045] FIG. 4 is a schematic top view of a flange of the radial
piston pump from FIG. 3;
[0046] FIG. 5 is a top view of an embodiment of a flat seal for
placement in the parting plane between a housing part and a flange
part of a radial piston pump;
[0047] FIG. 6 shows a section through the flat seal according to
FIG. 5.
[0048] The reference numeral 10 in FIG. 1 indicates a radial piston
pump with a housing 12 and a flange 14. The housing 12 and flange
14 are attached to each other in a parting plane 16; for the sake
of clarity, the connecting elements, e.g. screws, are not shown. A
drive shaft 18 is guided through the radial piston pump 10 in a
central position and is supported in bearings 20, 22. The drive
shaft 18 has an eccentric region 24, which actuates a piston 28 via
a slide element 26. The piston is disposed radially in a bore of
the housing 12 and seals a pump volume 30 in the housing 12 in a
mobile fashion. The pump volume 30 is coupled via a valve 32 to an
inlet chamber 34 by means of which fuel is supplied to the pump
volume 30. In addition, the pump volume 30 is connected via a valve
36 to a high-pressure conduit 38 that conveys high-pressure fuel
from the pump volume 30.
[0049] The drive shaft 18 rotating in the bearings 20, 22
periodically actuates the piston 28 so that the pump volume 30
periodically contracts and expands. With an expansion of the pump
volume 30, the valve 32 opens and fuel flows out of the inlet
chamber 34 into the pump volume 30. A contraction of the pump
volume 30 causes the valve 32 to close and, assuming there is a
sufficiently high pressure, causes the valve 36 to open, allowing
fuel to be ejected at high pressure from the pump volume 30.
[0050] The radial piston pump 10 is integrated into a low-pressure
circuit, not shown, in which a low-pressure delivery pump, also not
shown, feeds fuel into a supply conduit 40 in the housing 12. Fuel
from the supply conduit 40 is conveyed through the parting plane 16
into the first connecting bore 42 in the flange 14. From there, the
fuel flows through a first radial bore 44 that extends inside the
flange 14 and through a second connecting bore 48 into an annular
conduit or annular groove 50.
[0051] During manufacture, the first radial bore 44 is drilled
radially inward from the outside and after the bore is produced,
the undesirable opening remaining in the housing 12 is tightly
sealed with a first sealing ball 46. The annular groove 50 leads
around the central region of the radial piston pump 10 in which the
drive shaft 18 is supported in rotary fashion. Fuel travels out of
the annular groove 50 and into a second radial bore 54 through a
third connecting bore. The second radial bore 54 has been produced
in a manner analogous to the production of the first radial bore
44, by being drilled in from the outside. Here, too, the remaining
undesirable opening is sealed from the outside by means of a
sealing ball, in this case the second sealing ball 56. The fuel
travels from the second radial bore 54 into the inlet chamber 34
through a fourth connecting bore 58 that intersects the parting
plane 16.
[0052] The radial piston pump according to FIG. 1 thus has a number
of fuel paths that are intersected by the parting plane 16 between
the flange 14 and housing 12. In addition, the parting plane 16
between the housing 12 and flange 14 also intersects the inner
chamber 60 inside the housing 12, in which the eccentric section 24
of the drive shaft 18 rotates and actuates the piston 28. The fuel
paths (40, 42, 50, 54, 58) intersected by the parting plane 16 are
subjected to a high pressure that prevails in the inlet chamber 34.
The inner chamber 60 is usually filled with fuel and/or has fuel
flowing through it. However, a different pressure usually prevails
in the inner chamber 60 than in the inlet chamber 34 and the fuel
paths (40, 42, 50, 54, 58) that communicate with the inlet chamber
34.
[0053] In order to prevent unwanted fuel flows between the inner
chamber 60 and the fuel paths (40, 42, 50, 54, 58), in particular
the annular groove 50, an O-ring 62 is provided, which is disposed
in a recess in the flange 14 concentric to the drive shaft. Another
O-ring 64 seals the annular groove 50 in the parting plane 16 in
relation to the environment. Another O-ring 66 seals the first
connecting bore 42 in the parting plane 16. In an analogous
fashion, an additional O-ring 68 seals the fourth connecting bore
58 in the parting plane 16.
[0054] FIG. 3 schematically depicts a radial piston pump 10 in the
context of an embodiment of the invention. By contrast with the
subject of FIGS. 1 and 2, which depict a known radial piston pump,
the embodiment according to FIG. 3 does not have any O-rings 62,
64, 66, and 68 in the parting plane 16 between the housing 12 and
flange 14 of the radial piston pump 10. For the sake of
completeness, it should be noted that features that are the same in
the different figures are labeled with the same reference
numerals.
[0055] The O-rings, which are provided in the subject of FIGS. 1
and 2, are replaced in the embodiment according to FIGS. 3 and 4 by
a flat seal 70, which is disposed in the parting plane 16 between
the housing 12 and flange 14. The design of this flat seal 70 will
be explained in more detail below in conjunction with FIGS. 5 and
6. A significant advantage of using a flat seal 70 is that the flat
seal 70 permits a modified routing of fuel. Thus in the subject of
FIG. 3, the supply conduit 40 feeds into a radial groove 72, which
can be open toward the parting plane 16. The radial groove 72
connects the supply conduit 40 to the annular groove 50 and thus
replaces the first connecting bore 42, the first radial bore 44
with the sealing ball 46 and the second connecting bore 48 from
FIG. 1. In the same manner, the radial groove 74 in FIG. 3 replaces
the third connecting bore 52, the second radial bore 54 with the
sealing ball 56, and the fourth connecting bore 58 from FIG. 1. The
radial groove 74 is also open in relation to the parting plane
16.
[0056] The top view of the flange 14 shown in FIG. 4 without the
flat seal 70 shows the open path of the radial grooves 72 and 74,
the absence of O-rings 62, 64, 66, and 68, and the absence of the
corresponding recesses for accommodating these O-rings in the
flange 14.
[0057] FIG. 5 is a top view of an embodiment of a flexible seal 70
for a radial piston pump. This embodiment corresponds to the radial
piston pumps actually in use better than the schematic depictions
in FIGS. 1 to 4. The flat seal 70 shown in FIG. 5 is likewise
intended for placement in a parting plane 16 between a housing 12
and a flange 14 of a radial piston pump 10. The flat seal 70 has
three regions 76, 78, and 80 arranged in a star pattern, each of
which contains an opening 77, 79, and 81. When installed, each of
the regions 76, 78, and 80 arranged radially in a star pattern
covers over a radial groove in the flange of a radial piston
pump.
[0058] The associated radial piston pump correspondingly has three
pump elements that are arranged radially in a star pattern. The
radial grooves are embodied, for example, like the radial groove 74
in the depiction in FIGS. 3 and 4. The openings 77, 79, and 81
respectively permit a flow of fuel from the radial groove, through
the flat seal 70, and into the associated pump volumes.
[0059] In the embodiment in FIG. 3, the opening in the seal 70 that
permits a flow from the radial groove 74 into the inlet chamber 34
corresponds to one of the openings 77, 79, and 81. Therefore the
inlet chamber pressure prevails in the region of these openings 77,
79, and 81. This inlet chamber pressure is sealed in relation to
the inner chamber of the radial piston pump by an inner bead 82.
This inner chamber corresponds to the inner chamber 60 in FIGS. 1
and 3. Toward the outside, the inlet chamber is sealed by another
bead 84, which extends in a closed line around all three regions
76, 78, and 80 arranged in a star pattern.
[0060] The flat seal 70 has additional openings 86, 88, 90, and 92
that are each encompassed by an associated, concentrically disposed
bead 87, 89, 91, and 93.
[0061] These openings are provided because the parting plane 16
intersects other conduits and/or pressure chambers. Thus, for
example, the opening 92 can be associated with a metering unit that
controls the supply of fuel to the radial piston pump. The openings
86, 88, and 90 can, for example, represent inlet conduits and
outlet conduits for a low-pressure gear delivery pump that is
flange-mounted to the radial piston pump, while the opening 90, for
example, can be associated with a ventilation bore for the inner
chamber 60 of the radial piston pump. Openings 95 permit fastening
elements such as screws to pass through.
[0062] FIG. 5 already shows particularly well the possibility, in a
flat seal, of producing sealing contours in the form of beads that
deviate from the concentric form of the O-rings that are usually
used. This makes it possible for the fuel conduits extending
radially outward to be placed in the parting plane, as represented
by a radial groove 74 in FIGS. 3 and 4. This makes it easier, for
example, to produce the flange 14 that contains the radially
extending fuel supply conduit. This allows a radial groove, for
example, which corresponds to the radial groove 74 in FIGS. 3 and
4, to be produced in a largely preformed fashion in a cast flange
14, thus to a large extent eliminating the need for additional
machining steps. The same is true for a forged flange 14.
[0063] FIG. 6 is a sectional depiction of the seal 70 according to
FIG. 5. The seal 70 has a sheet metal layer 94 that lends the flat
seal 70 structure and strength. In the embodiment shown, the sheet
metal layer 94 is coated with a layer of flexible, elastic plastic
96, which improves the sealing action. The beads 84 and 82 are
depicted as raised areas in the sectional view in FIG. 6.
* * * * *