U.S. patent application number 11/912727 was filed with the patent office on 2008-08-07 for feed unit.
Invention is credited to Reinhard Dittmann, Christoph Mittermueller, Markus Moertl.
Application Number | 20080187451 11/912727 |
Document ID | / |
Family ID | 36691369 |
Filed Date | 2008-08-07 |
United States Patent
Application |
20080187451 |
Kind Code |
A1 |
Dittmann; Reinhard ; et
al. |
August 7, 2008 |
Feed Unit
Abstract
A feed unit for a fuel pup includes a rotor eccentrically
mounted in a pump chamber, and a plurality of grooves disposed on
the periphery of the rotor. The grooves receive a plurality of
sealing bodies which extend from within the grooves to an annular
wall of the pump chamber embodied as a curved track. A gap is
defined between the rotor and the curved track and is subdivided
into gap spaces that are sealed from each other by the sealing
bodies, which are configured as elastic spring elements.
Inventors: |
Dittmann; Reinhard;
(Feldkirchen, DE) ; Moertl; Markus; (Muenchen,
DE) ; Mittermueller; Christoph; (Muenchen,
DE) |
Correspondence
Address: |
RONALD E. GREIGG;GREIGG & GREIGG P.L.L.C.
1423 POWHATAN STREET, UNIT ONE
ALEXANDRIA
VA
22314
US
|
Family ID: |
36691369 |
Appl. No.: |
11/912727 |
Filed: |
May 8, 2006 |
PCT Filed: |
May 8, 2006 |
PCT NO: |
PCT/EP06/62116 |
371 Date: |
October 26, 2007 |
Current U.S.
Class: |
418/215 |
Current CPC
Class: |
F04C 2/3445 20130101;
F04C 5/00 20130101 |
Class at
Publication: |
418/215 |
International
Class: |
F04C 2/344 20060101
F04C002/344; F04C 5/00 20060101 F04C005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2005 |
DE |
10 2005 030 540.7 |
Claims
1-8. (canceled)
9. A feed unit for a fuel pump, comprising: a cylindrical pump
chamber having an annular wall embodied as a curved track; a rotor
supported rotatably and eccentrically within the pump chamber; a
plurality of pockets disposed on a periphery of the rotor; and a
plurality of sealing bodies disposed within the pockets and
extending from the pockets to the curved track of the rotor,
wherein the sealing bodies are embodied as elastic spring
elements.
10. The feed unit according to claim 9, wherein the spring elements
are supported unilaterally inside the pockets of the rotor.
11. The feed unit according to claim 10, wherein the pockets are
embodied in groovelike form, with two lateral flanks and a groove
base, and the spring elements are secured by a securing portion to
one of the lateral flanks or to the groove base.
12. The feed nit according to claim 9, wherein the spring element
has a spring arm with a curved portion cooperating with the curved
track.
13. The feed unit according to claim 11, wherein by elastic bending
the spring element can be resiliently pressed all the way into the
associated pocket.
14. The feed unit according to claim 9, wherein the elastic spring
elements are leaf springs or spiral springs.
15. The feed unit according to claim 9, wherein the elastic spring
elements are each embodied as a spring assembly, comprising two
leaf springs, joined solidly to one another at the ends, and are
placed loosely in the pockets.
16. The feed unit according to claim 9, wherein the spring elements
are embodied integrally on the rotor.
Description
PRIOR ART
[0001] The invention is based on a feed unit as generically defined
by the preamble to the main claim.
[0002] A feed unit is already known from U.S. Pat. No. 5,378,111,
having a rotor supported eccentrically in a pump chamber and having
grooves, disposed on the circumference of the rotor, in which
rollers, resting on a curved track of the pump chamber, are
provided as sealing bodies. Between the rotor and the curved track,
a gap is formed, which is split by the rollers into gap spaces that
are sealed off from one another by means of the rollers. The
grooves, the rollers supported in the grooves, and the curved track
require very great production precision, if low wear at the curved
track and a high degree of running smoothness of the feed unit are
to be attained. Since the rollers can be allowed to protrude only
scarcely halfway out of the groove at most, so that they will not
tilt, the volume of the gap spaces and hence the feed capacity are
limited. The sealing action of the rollers is based on the
centrifugal force with which the rollers are pressed against the
curved track. To seal off the gap spaces well from one another, a
comparatively high mass of the rollers is necessary, but when the
rollers vibrate, this causes wear to the curved track as well as
running noise. The grooves require great production precision, so
that the rollers will be adequately guided in the grooves. The
rotor must be embodied as wear-resistant.
ADVANTAGES OF THE INVENTION
[0003] The feed unit according to the invention having the
definitive characteristics of the body of the main claim has the
advantage over the prior art that in a simple way, an improvement
is attained such that the prod-action costs of the feed unit are
reduced because the scaling bodies are embodied as elastic spring
elements. In this way, the volume of the gap spaces can be
increased markedly, so that a greater feeding capacity is attained
for the same rpm. The curved track requires much less production
precision than in the prior art, since the spring elements have a
long spring travel for adaptation to the cured track. Because of
the low mass of the spring elements, the wear to the curved track
is also reduced. The requisite production precision and the
requirements for wear resistance with regard to the rotor are
markedly less than in the prior art.
[0004] By the provisions recited in the dependent claims,
advantageous refinements of and improvements to the feed unit
defined by the main claim are possible.
[0005] It is especially advantageous if the spring elements are
supported unilaterally inside the pockets of the rotor, since in
this way a long spring travel of the spring elements is possible,
which makes it possible to embody large gap spaces and hence
permits a high feed capacity.
[0006] It is also advantageous if the pockets are embodied in
groovelike form, with two lateral flanks and a groove base, and the
spring elements are secured by a Securing portion to one of the
lateral flans or to the groove base.
[0007] It is highly advantageous if the spring element has a spring
arm, with a curved portion cooperating with the curved track, since
in this way a linear sealing is attained.
[0008] It is also advantageous that by elastic bending, the spring
element can be resiliently pressed all the way into the associated
pocket, since in this way the rotor can pass through an extremely
narrow gap.
[0009] In an advantageous embodiment, it is provided that the
elastic spring elements are embodied as leaf springs or spiral
springs.
[0010] It is also advantageous if the elastic spring elements are
each embodied as a spring assembly, comprising two leaf springs,
joined solidly to one another at the ends, and are placed loosely
in the pockets, since in this way an alternative version is
achieved.
DRAWINGS
[0011] Two exemplary embodiments of the invention are shown in
simplified form in the drawing and described in further detail in
the ensuing description.
[0012] FIG. 1 shows a feed unit in section;
[0013] FIG. 2 shows a view of a first exemplary embodiment;
[0014] FIG. 3 shows a section through a spring element of the
invention taken along the line III-III in FIG. 2; and
[0015] FIG. 4 shows a view of a second exemplary embodiment of the
feed unit of the invention.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0016] FIG. 1 shows a feed unit in which the embodiment according
to the invention can be employed.
[0017] The unit according to the invention has a housing 1, for
instance cylindrical in shape, with at least one inlet conduit 2
and one outlet conduit 3. The inlet conduit 2 of the unit
communicates, for instance via a suction line 6, with a tank 7, in
which fuel, fox instance, is stored. The outlet conduit 3 of the
unit communicates with an internal combustion engine 9, for
instance via a pressure line 8.
[0018] The housing 1 of the unit has a pump part 12 and a drive
part 13. The pump part 12 has a pump chamber 14, which for instance
is embodied cylindrically. A region upstream of the pump chamber 14
is called the intake side of the unit, while a region downstream of
the pump chamber 14 is called the compression side of the unit. A
rotor 15 is rotatably supported in the pump chamber 14, and the
rotor 15 and the pump chamber 14 are disposed eccentrically to one
another. The rotor 15 is driven to rotate by an actuator 18 via a
drive shaft 19, the actuator being provided in the drive part 13
and for instance being an armature of an electric motor.
[0019] The pump chamber 14 is defined by two end walls
diametrically opposite one another in the direction of a
rotationally symmetrical axis 20 of the rotor 15, specifically a
first end wall 21 oriented toward the inlet conduit 2 and a second
end wall 22 oriented toward the outlet conduit 3, and in the radial
direction relative to the axis 20 the pump chamber is defined by an
annular wall 23.
[0020] The first end wall 21 is embodied on the inside, toward the
rotor 15, of an intake cap 26, for instance disklike in shape, and
the second end wall 22 is embodied on the inside, toward the rotor
15, of a pressure cap 27, which is for instance disklike in shape.
The annular wall 23 is provided for instance on the inside, toward
the rotor 15, of an annular intermediate cap 28. The intermediate
cap 28 is disposed for instance between the disklike intake cap 26
and the disklike pressure cap 27. The intermediate cap 28 may,
however, also be integrally joined to the intake cap 26 or to the
pressure cap 27. The intermediate cap 28 with the annular wall 23
is for instance disposed eccentrically to the rotor 15.
[0021] The housing 1 has a cylindrical portion 31, which has the
intake cap 26 on the face end toward the pump part 12 and has a
connection cap 32 on the face end toward the drive part 13. The
intake cap 26 and the connection cap 32 close off the cylindrical
portion 31 of the housing 1 tightly from the external
environment.
[0022] The inlet conduit 2 of the housing 1 is disposed for
instance on the intake cap 26 and communicates with the flow
direction with a pump chamber inlet 33 that discharges into the
pump chamber 14. The outlet conduit 3 of the housing 1 is disposed
for instance on the connection cap 32. The connection cap 32 has an
electrical terminal 36, for instance, for contacting the actuator
18 provided in the housing 1.
[0023] A pump chamber outlet 34, which connects the pump chamber 14
downstream with a pressure chamber 35 of the housing 1, is disposed
for instance in the pressure cap 27 of the unit. However, the pump
chamber outlet 34 may also be provided on the intake cap 26. The
pressure chamber 35 is embodied in the drive part 13 and is defined
radially by the cylindrical portion 31 and axially by the pressure
cap 27 and the connection cap 32. The actuator 18 is disposed for
instance in the pressure chamber 35. The pressure cap 27 has a
drive shaft conduit 37, which extends through the drive shaft 19
into the pump chamber 14 so as to drive the rotor 15 to rotate. The
drive shaft 19 is supported for instance on the end, remote from
the actuator 18, in a bearing recess 38 of the intake cap 26. The
pressure chamber 35 communicates at least indirectly with the
engine 9 via the outlet conduit 3 of the housing 1 and the pressure
line 8.
[0024] The rotor 15 is embodied for instance as a cylindrical disk.
A plurality of sealing bodies 39 are provided on the rotor 15. The
sealing bodies 39 are disposed for instance in pockets 40 of the
rotor 15 that are distributed uniformly over the circumference of
the rotor 15, and the sealing bodies extend from the pockets 40 of
the rotor 15 up to the annular wall 23. Upon the rotation of the
rotor 15, the sealing bodies slide along the annular wall 23. The
annular wall 23 forms a so-called curved track 24. The curved track
24 may be embodied circularly or elliptically, for instance, but is
expressly arbitrary.
[0025] FIG. 2 shows a unit according to the invention in section,
in accordance with a first exemplary embodiment.
[0026] In the unit of FIG. 2, the elements that remain the same or
function the same as in the unit of FIG. 1 are identified by the
same reference numerals.
[0027] The pockets 40 are embodied as a recess, which for instance
is groovelike but whose shape is expressly arbitrary. There is
preferably an odd number of pockets 40. For instance, the pockets
40 penetrate the rotor 15 in the axial direction, with respect to
the axis 20, from one face end of the rotor 15 to the other face
end. From the outer circumference, the pockets 40 extend radially
inward, with two lateral flanks 43, disposed parallel to one
another for instance, and each ends in a groove base 44.
[0028] Because of the eccentric arrangement of the rotor 15 in the
pump chamber 14, there is one region on the curved track 24 having
the least spacing between the rotor 15 and the curved track 24,
hereinafter called the narrow gap 45, and one region on the curved
track 24 having the greatest spacing between the rotor 15 and the
curved track 24, which will hereinafter be called the wide gap
46.
[0029] Because of the eccentric disposition of the rotor 15 in the
pump chamber 14, a crescent-shaped gap 48 is created between the
curved track 24 and the rotor 15; this gap is divided by the
sealing bodies 39 into a plurality of gap spaces 49, for instance
crescent-shaped, that are separated from one another. The number of
gap spaces 49 matches the number of sealing bodies 39.
[0030] Upon the rotation of the rotor 15 in a direction of rotation
16, the sealing bodies 39 rest on the curved track 24, so that the
individual gap spaces 49 are sealed off Thom one another.
[0031] The pump chamber inlet 33 and/or the pump chamber outlet 34
is embodied as a kidney-shaped groove, for instance.
[0032] The pump chamber inlet 33 is disposed for instance such that
each gap space 49, upon the rotation of the rotor 15,
intermittently communicates fluidically with the pump chamber inlet
33 through an overlap, and fluid flows into the applicable gap
space 49 via the inlet conduit 2 and the pump chamber inlet 33. The
pump chamber outlet 34 is disposed for instance such that each gap
space 49, upon the rotation of the rotor 15, intermittently
communicates fluidically with the pump chamber outlet 34 by
overlap, and fluid flows out of the applicable gap space 49 into
the pump chamber outlet 34.
[0033] The curved track 24 comprises an intake region 58, a
compression region 60, and a sealing region 61. The intake region
58 is located in the region of the pump chamber inlet 33 between
the narrow gap 45 and the wide gap 46; the reversing region 59 is
disposed in the region of the wide gap 46, between the pump chamber
inlet 33 and the pump chamber outlet 34; the compression region 60
is located in the region of the pump chamber outlet 34; and the
sealing region 61 is located in the region of the narrow gap
45.
[0034] In the intake region 58, the gap width of the gap 48
increases from the narrow gap as far as the wide gap 46, in the
direction of rotation 16 of the rotor 15, so that the volume of the
individual gap spaces 49, viewed in the direction of rotation of
the rotor 15, increases, and a negative pressure occurs there. As
soon as the pump chamber inlet 33, in the intake region 58,
overlaps with one of the gap spaces 49 as a result of the rotation
of the rotor 15, the pump chamber inlet 33 is open to the
applicable gap space 49, so that fluid flows continuously into the
applicable gap space 49. In the intake region 58, fluid is thus
aspirated into the applicable gap space 49.
[0035] The filling of the applicable gap space 49 ends when the gap
space 49, by further rotation of the rotor 15, no longer
communicates with the pump chamber inlet 33. The gap space 49 is
then closed off from the environment and reaches the reversing
region 59.
[0036] In the reversing region 59, the gap space 49 is closed and
in this way seals off the pump chamber outlet 34 from the pump
chamber inlet 33.
[0037] In the compression region 60, the applicable gap space 49 is
evacuated, because as a result of the reduction in the volume of
the applicable gap space 49 a pressure is built up, and the fluid
is forced in this way out of the gap space 49 into the pump chamber
outlet 34. This happens as soon as the pump chamber outlet 34, in
the rotation of the rotor 15, overlaps with the applicable gap
space 49. The pump chamber outlet 34 is then open to the applicable
gap space 49.
[0038] The sealing region 61 seals off the compression region 60
from the intake region 58, so that virtually no leakage from the
compression region 60 into the intake region 58 occurs. The radial
gap width between the rotor 15 and the cured track 24 in the
sealing region 61 should be embodied to be as small as possible and
the sealing region 61 should be embodied to be as large as
possible, so that the fluid of the applicable gap space 49 is
evacuated as completely as possible in the direction of the pump
chamber outlet '34 and does not reach the intake region 58 again in
the form of a leakage flow via the narrow gap 45.
[0039] According to the invention, it is provided that the sealing
bodies 39 are embodied as elastic spring elements. In an
advantageous feature, a leaf spring, spiral spring, or the like is
used for instance as the elastic spring element. As the material
for the elastic spring element 39, spring steel or plastic is for
instance used. The rotor 15 may be produced from an arbitrary
material, such as metal or plastic.
[0040] The spring elements 39 conform with a linear contact to the
curved track 24 and one another (FIG. 3) both at the curved track
24 and at the end walls 21, 22.
[0041] In a first embodiment, it is provided that the spring
elements 39 are supported only unilaterally; each spring element 39
is secured by a securing portion 50 inside the applicable pocket 40
on the rotor 15 and extends with a spring arm 51 as far as the
curved track 24. The spring arm 51 for instance has a curved
portion 51.1 with a radius, which rests on the cured track 24.
[0042] Upon the rotation of the rotor 15, the gap 48 varies in the
radial direction, so that the spring element 39 with the spring arm
51 is elastically bent toward the rotor 15 upon a reduction of the
gap 48 and is moved in the direction away from the rotor 15 upon an
increase in size of the gap 48. Upon an increase in size of the gap
48, the spring element 39 remains in contact with the curved track
24, since the spring element 39, being elastically prestressed, is
pressed against the curved track 24. Since the gap 48 at the narrow
gap 45 is very slight, the pockets 40 must extend in the
circumferential direction of the rotor 15 far enough that the
spring elements 39 with their spring arm 51 on passing through the
narrow gap 45 can be lowered in their pocket 40 and can plunge at
least nearly completely into the pocket. It is also possible to
embody the rotor 15 without pockets; then the spring elements 39,
instead of plunging into the pockets, rest on the circumference of
the rotor 15.
[0043] As an example, the spring elements 39 are disposed on a
lateral flank 43 that leads ahead in the direction of rotation of
the rotor 15 and extend, counter to the direction of rotation 16,
at an acute angle 52 as far as the curved track 24. The spring
elements 39, however, may also be solidly joined to the rotor 15 at
the groove base 44. The spring elements 39 are welded with the
securing portion 50 to the rotor 15, for instance, or pressed,
inserted, glued or the like into a groove 53 of the rotor 15.
However, they may also be provided integrally on the rotor 15, for
instance by means of injection molding. The spring elements 39 may
also be placed loosely in the pockets 40 (FIG. 4).
[0044] To avoid or reduce vibration of the spring elements 39 in
operation of the feed unit, the mass of the spring elements 39
and/or their spring stiffness is designed accordingly, for instance
by providing accumulations of material or additional weights at
certain points of the spring elements 39.
[0045] It is also possible to embody the spring elements 39 such
that upon loading above a predetermined overpressure, they yield
elastically, so that the sealing action of the spring elements 39
of the applicable gap space 49 no longer exists, and fluid can flow
out of the gap space 49 that is subjected to excessively high
pressure into the adjacent gap spaces 49. In this way, the spring
elements 39 have a pressure limiting valve function.
[0046] FIG. 3 shows a section through the spring element of the
invention taken along the line III-III in FIG. 2.
[0047] In the unit of FIG. 3, the elements that remain the same or
function the same as in the unit of FIGS. 1 and 2 are identified by
the same reference numerals.
[0048] The spring elements 39 are bent toward the face ends 21, 22,
in order to achieve good sealing with little friction.
[0049] FIG. 4 shows a unit according to the invention in a second
exemplary embodiment in section.
[0050] In the unit of FIG. 4, the elements that remain the same or
function the same as in the unit of FIGS. 1 through 3 are
identified by the same reference numerals.
[0051] The feed unit of FIG. 4 differs from the feed unit of FIG. 2
in that instead of the unilaterally supported spring element 51, a
spring assembly 54, each comprising two leaf springs, is disposed
in the pockets 40. The two leaf springs are solidly joined together
at their ends and in this way form an oval-shaped spring assembly.
The spring assemblies 54 may also be embodied in one piece and are
made for instance from spring steel or plastic. The spring
assemblies 54 are prestressed in the pockets 40 in such a way that
one of the leaf springs of the spring assembly 54 is pressed
against the curved track 24, and the other is pressed against the
groove base 44 of the applicable pocket 40. The spring assemblies
54 are placed loosely in the pockets 40.
* * * * *