U.S. patent application number 10/570165 was filed with the patent office on 2007-01-25 for pump for conveying an exhaust gas aftertreatment medium particularly a urea-water solution, for diesel engines.
This patent application is currently assigned to Hydraulik-Ring GmbH. Invention is credited to Stefan Klotz, Dieter Maisch, Roland Meyer.
Application Number | 20070020123 10/570165 |
Document ID | / |
Family ID | 34276550 |
Filed Date | 2007-01-25 |
United States Patent
Application |
20070020123 |
Kind Code |
A1 |
Meyer; Roland ; et
al. |
January 25, 2007 |
Pump for conveying an exhaust gas aftertreatment medium
particularly a urea-water solution, for diesel engines
Abstract
A pump for conveying an exhaust gas treatment medium in diesel
engines has a pump housing and a piston arranged in the pump
housing and movable in the pump housing against a counterforce. The
piston pumps an exhaust gas treatment medium form at least one
inlet of the pump to at least one outlet of the pump. A diaphragm
separates the piston from the exhaust gas treatment medium. The
counterforce is provided by at least one spring that is a pressure
spring.
Inventors: |
Meyer; Roland; (Nurtingen,
DE) ; Maisch; Dieter; (Kohlberg, DE) ; Klotz;
Stefan; (Alchtal, DE) |
Correspondence
Address: |
GUDRUN E. HUCKETT DRAUDT
LONSSTR. 53
WUPPERTAL
42289
DE
|
Assignee: |
Hydraulik-Ring GmbH
Marktheidenfeld
DE
|
Family ID: |
34276550 |
Appl. No.: |
10/570165 |
Filed: |
August 19, 2004 |
PCT Filed: |
August 19, 2004 |
PCT NO: |
PCT/DE04/01848 |
371 Date: |
April 17, 2006 |
Current U.S.
Class: |
417/413.1 |
Current CPC
Class: |
F04B 17/042 20130101;
F04B 17/003 20130101; F04B 17/046 20130101; F04B 43/04
20130101 |
Class at
Publication: |
417/413.1 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2003 |
DE |
103 41 995.0 |
Mar 8, 2004 |
DE |
10 2004 011 123.5 |
Claims
1.-27. (canceled)
28. A pump for conveying an exhaust gas treatment medium in diesel
engines, the pump comprising: a pump housing; a piston arranged in
the pump housing and movable in the pump housing against a
counterforce, wherein the piston pumps an exhaust gas treatment
medium from at least one inlet of the pump to at least one outlet
of the pump; and a diaphragm separating the piston from the exhaust
gas treatment medium.
29. The pump according to claim 28, wherein the piston is a hollow
piston.
30. The pump according to claim 28, comprising at least one spring
generating the counterforce.
31. The pump according to claim 30, wherein the at least one spring
is a pressure spring.
32. The pump according to claim 30, wherein the at least one spring
is a plate spring.
33. The pump according to claim 32, wherein the plate spring is
integrated into the diaphragm.
34. The pump according to claim 33, wherein the plate spring is
tightly enclosed by the diaphragm.
35. The pump according to claim 28, wherein the diaphragm is
comprised of thermoplastic elastomer or vulcanized elastomer.
36. The pump according to claim 28, comprising at least one
solenoid surrounding the piston.
37. The pump according to claim 36, wherein the piston is movable
by applying current to the at least one solenoid.
38. The pump according to claim 28, wherein the piston has a
bottom.
39. The pump according to claim 38, wherein the diaphragm is
fixedly connected to the piston in a movement direction of the
piston.
40. The pump according to claim 39, wherein the diaphragm is
connected to the bottom of the piston.
41. The pump according to claim 38, wherein the diaphragm has a
projection that projects through the bottom of the piston.
42. The pump according to claim 41, further comprising a fastening
part embedded in the diaphragm, wherein the projection projects
from the fasting part.
43. The pump according to claim 42, comprising a plate spring
generating the counterforce, wherein the plate spring is integrated
into the diaphragm and is secured on the fasting part
44. The pump according to claim 41, wherein the projection is a
threaded pin.
45. The pump according to claim 44, wherein the threaded pin is
screwed into the bottom of the piston.
46. The pump according to claim 28, comprising at least one
solenoid surrounding the piston, wherein the piston is movable by
applying current to the at least one solenoid, wherein the
diaphragm rests areally against the bottom of the piston when the
solenoid is not actuated.
47. The pump according to claim 28, wherein the diaphragm has a rim
that is clamped between the pump housing and a pump head of the
pump.
48. The pump according to claim 47, wherein the diaphragm delimits
a pump chamber.
49. The pump according to claim 48, wherein the pump chamber is
provided in the pump head.
50. The pump according to claim 49, comprising a first check valve
that is adapted to close a supply path to the pump chamber.
51. The pump according to claim 50, comprising a second check valve
that is adapted to close the at least one outlet.
52. The pump according to claim 51, wherein the first and second
check valves operate in opposite directions relative to one
another.
53. The pump according to claim 51, wherein the pump head has first
and second receiving chambers, wherein first check valve has a
first valve body arranged in the first receiving chamber and the
second check valve has a second valve body arranged in the second
receiving chamber.
54. The pump according to claim 53, wherein an outer diameter of
the first and second valve bodies is smaller than an inner diameter
of the first and second receiving chambers, respectively.
55. The pump according to claim 53, wherein the first and second
receiving chambers are connected to the pump chamber.
Description
[0001] The invention relates to a pump for conveying an exhaust gas
after treatment medium, in particular, a urea/water solution, for
diesel engines according to the preamble of claim 1.
[0002] Cleaning devices for diesel vehicles are known in which the
exhaust gas of diesel engines is treated with a medium, preferably
a 32.5% urea/water solution, in order to reduce or remove
completely the nitrous oxides in the exhaust gas. For conveying the
medium, a pump is provided that pumps the medium from a
reservoir.
[0003] The invention has the object to configure the pump of the
aforementioned kind such that by means of the pump the exhaust gas
after treatment medium can be properly and reliably conveyed under
the conditions occurring within diesel vehicles.
[0004] This object is solved for the pump of the aforementioned
kind in accordance with the present invention with the
characterizing features of claim 1.
[0005] In the pump according to the invention, the pump element is
a piston that is movable against a counterforce during the pumping
operation. The piston is separated by a diaphragm from the medium
to be pumped. By means of the pump according to the invention
sufficiently high pressures can be achieved. Since the piston is
separated from the medium by a diaphragm, it is corrosion-resistant
because it does not come into contact with the medium. The
diaphragm seals the piston so that a shaft seal is not required in
the area in contact with the medium. The pump is characterized by a
simple configuration and a long service life.
[0006] Further features of the invention result from the dependent
claims, the description, and the drawing.
[0007] The invention will be explained in more detail with the aid
of two embodiments illustrated in the drawings. It is shown in:
[0008] FIGS. 1 and 2 in axial section a pump according to the
invention in a first and a second pump position, respectively;
[0009] FIG. 3 a second embodiment of the pump according to the
invention in a representation corresponding to that of FIG. 2;
[0010] FIG. 4 the detail Z of FIG. 3 in an enlarged
illustration.
[0011] The pump is advantageously suitable for use in exhaust gas
after treatment devices for diesel engines. Of course, it can also
be used for other pumping purposes.
[0012] The pump has a housing 1 that is provided at one end face
with a cylindrical projection 2. At least one solenoid 3 is
embedded in the housing 1. The housing 1 has a central axial
receiving chamber 4 having at its inner wall a sleeve-shaped slide
bearing 5. The bearing is positioned with the first end on a
radially inwardly oriented annular shoulder 6 that projects away
from the inner wall 7 of the receiving chamber 4.
[0013] A cup-shaped piston 8 is arranged in the slide bearing 5 so
as to be axially movable against the force of at least one pressure
spring 9. One end of the pressure spring 9 is supported on the
bottom 10 of the piston and the other end on the bottom side of an
adjusting screw 11 that is screwed into the projection 2. By means
of the adjusting screw 11, the pretension of the pressure spring 9
can be adjusted continuously. For centering the pressure spring 9,
the adjusting screw 11 is provided at its underside with a central
projection 12 that projects into the appropriate end of the
pressure spring 9.
[0014] The piston 8 is provided at the end facing the adjusting
screw 11 with a radially outwardly oriented flange 13 that rests
against the radially outwardly oriented shoulder 14 of the inner
wall 7 of the receiving chamber 4 in a first position (FIG. 2) of
the piston 8. The adjusting screw 11 has at its circumference an
annular wall 15 having an inner wall for guiding the flange 13 of
the piston 8.
[0015] A pump head 16 is connected, preferably by screwing, to the
end face of the housing 1 that is remote from the adjusting screw
11. The pump head 16 has a housing 17 with a radially outwardly
oriented flange 18 with which the pump head 16 rests areally and
sealingly against the end face of the housing 1. Along the rim of
the flange 18 fastening screws 19 are provided with which the pump
head 16 is screwed onto the housing 1. The head of the fastening
screws 19 is positioned advantageously recessed within the flange
18.
[0016] In the pump head there are two check valves 20, 21 that are
arranged at a spacing from one another; each is arranged in a
receiving chamber 22, 23 of the pump head 16. In the receiving
chamber 22 there is a valve body 24 having an outer diameter that
is smaller than the outer diameter of the receiving chamber 22. The
valve body 24 is loaded by at least one pressure spring 25 in the
direction toward its closed position illustrated in FIG. 1 in which
it closes off a bore 26 in the pump head 16. The axis-parallel bore
26 connects the receiving chamber 22 to a pump chamber 27 that is
closed off by a diaphragm 28. The pump chamber 27 is formed
essentially by a recess of the end face of the pump head 16. The
diaphragm 28 has a reinforced circumferentially extending rim 29
that is clamped between the housing 1 and the flange 18 of the pump
head 16. The diaphragm 28 has at its side facing the piston 8 a
central projection 30 that penetrates a central bore 31 of the
bottom 10 of the piston 8. The free end of the projection 30 has a
wider portion 32 that serves as an axial securing means of the
diaphragm 28 relative to the piston 8. The wider portion 32 rests
at the inner side of the piston bottom 10 and is designed such that
the diaphragm 28 is connected captively to the piston 8.
[0017] On the side of the pump head 16 opposite the bore 26, a bore
33 opens into the receiving chamber 22; the bore is provided in the
connecting plate 34. The plate is fastened to the end face of the
pump head 16 that is facing away from the housing 1.
[0018] In the receiving chamber 23 of the pump head 16 there is
also a valve body 35 that is identical to the valve body 24 but is
arranged in the receiving chamber 23 in a 180.degree. rotated
position relative to the valve body 24. The valve body 35 closes a
bore 36 that extends parallel to the bore 33 in the connecting
plate 34. The valve body 35 is loaded by at least one pressure
spring 37 in the receiving chamber 23 in the direction toward its
closed position (FIG. 2). The outer diameter of the valve body 35
is smaller than the diameter of the receiving chamber 23. A bore 38
is provided in the pump head 16 parallel to the bore 26 and opens
into the receiving chamber 23. The bore 38 connects the pump
chamber 27 to the receiving chamber 23.
[0019] The pressure spring 25 of the check valve 20 is supported
with one end on the connecting plate 34 and with its other end on
the valve body 24. The pressure spring 37 is supported with one end
on the bottom of the receiving chamber 23 and with its other end on
the valve body 35.
[0020] The bores 33, 36 open into connectors 39, 40 that are
provided at the end face of the connecting plate 34 facing away
from the pump head 16 and through which the medium to be conveyed
is sucked in or discharged.
[0021] In the position according to FIG. 1, current is supplied to
the solenoid 3 so that the piston 8 is moved against the force of
the pressure spring 9 until the piston with its flange 13 rests
against the adjusting screw 11 (FIG. 1). The diaphragm 28, because
it is axially fixedly connected to the piston 8, is entrained so
that vacuum is generated in the bores 26, 38. This has the result
that the valve body 24, assisted by the force of the pressure
spring 25, moves into the closed position in which it closes the
bore 26. The valve body 35 is lifted off the connecting plate 34 by
the generated vacuum acting against the force of the pressure
spring 37. In this way, through the connector 40 and the bore 36
the medium can reach the receiving chamber 23. Here, the sucked-in
medium flows past the valve body 35 through the bore 38 into the
pump chamber 27.
[0022] Subsequently, the current supply to the solenoid 3 is
switched off. This has the result that the piston 8 is returned by
the force of the pressure spring 9 so far that its flange 13
contacts the shoulder 14 of the pump housing 1 (FIG. 2). This axial
displacement process causes the diaphragm 28 to be entrained and
elastically deformed. The medium contained in the pump chamber 27
is pressurized. This has the result that the medium moves the valve
body 35 into the closed position illustrated in FIG. 2, assisted by
the force of the pressure spring 37. In this way, the bore 36 in
the connecting plate 34 is blocked. At the same time, however, the
valve body 24 is pushed back by the pressurized medium against the
force of the pressure spring 25 so that the bore 26 in the pump
head 16 is released. The medium reaches the receiving chamber 22
and can flow past the valve body 24 into the bore 33 and thus into
the connector 39.
[0023] The level of the pump pressure is dependent on the spring
force of the pressure spring 9 with which the piston 8 is actuated.
By means of the adjusting screw 11 the pump pressure can be
fine-adjusted after mounting.
[0024] Advantageously, the end face 41 of the piston bottom 10
facing the diaphragm 28 is curved (FIG. 1) such that the diaphragm
28 can rest in the deflected position according to FIG. 2 areally
against the end face 41 (FIG. 2). In this way, the diaphragm 28 is
optimally supported and therefore wears only minimally.
[0025] The pump is the combination of an oscillating piston pump
and a diaphragm pump. The oscillating piston part with the piston 8
serves as a maintenance-free drive while the diaphragm 28 provides
the pumping member. During the pumping action, only the diaphragm
28 is in contact with the medium but not the piston 8. Accordingly,
the material of the diaphragm 28 can be matched optimally to the
medium to be pumped. The piston 8 does not come into contact with
this medium and can therefore be manufactured of materials that are
accordingly less expensive.
[0026] The pump can generate pressures, for example, within the
range of approximately 5 bar. The pump is corrosion-resistant
relative to aqueous solutions because the oscillating piston part
is sealed by the diaphragm 28 relative to the medium. In the
diaphragm pump part a shaft seal is not provided so that problems
related with such seals do not occur. The described pump is
freeze-protected because the pump piston 8 in the rest state
(solenoid not supplied with current, FIG. 2) is in the position of
smallest dead pumping volume 27. When the medium freezes, the
resulting additional volume can be taken up by the piston 8 that
retreats against the spring 9. The pump can be easily heated by
means of the solenoid 3 so that a self-contained thawing of the
medium after a possible freezing action is enabled. possible. The
pump operates maintenance-free at least over the service life of
the vehicle in which it is mounted.
[0027] The pump according to FIGS. 3 and 4 differs from the afore
described embodiment essentially in that instead of the piston
spring 9 a plate spring 9' is provided that is integrated into the
diaphragm 28 and is tightly enclosed by the diaphragm. The plate
spring 9' is mounted on a fastening part 42 which is also embedded
in the diaphragm 28 and from which the projection 30 projects that
projects out of the diaphragm 28 and is configured as a threaded
pin. It is screwed into the bottom 10 of the piston 8. The
fastening part 42 and the projection 30 together form
advantageously a unitary part. The diaphragm 28 is comprised
preferably of thermoplastic elastomer or vulcanized elastomer.
[0028] FIG. 3 shows the piston 8 in a position in accordance with
FIG. 2 of the preceding embodiment. The solenoid 3 is not supplied
with current and the piston 8 is moved by the force of the plate
spring 9' into a position such that it rests with its flange 13
against the shoulder 14 of the pump housing 1. The diaphragm 28
rests areally on the curved end face 41 of the piston bottom
10.
[0029] When the coil 3 is supplied with current, the piston 8 is
moved against the force of the plate spring 9' until it comes to
rest with its flange 13 against the adjusting screw 11.
[0030] In other respects, the function of the pump is identical to
that of the embodiment of FIGS. 1 and 2.
* * * * *