U.S. patent application number 14/901296 was filed with the patent office on 2016-12-01 for switchover device for a thick-matter pump.
This patent application is currently assigned to Schwing GmbH. The applicant listed for this patent is Thorsten KOCH, Wolfgang MERTEN, Joseph SCHNITTKER. Invention is credited to Thorsten KOCH, Wolfgang MERTEN, Joseph SCHNITTKER.
Application Number | 20160348655 14/901296 |
Document ID | / |
Family ID | 51022294 |
Filed Date | 2016-12-01 |
United States Patent
Application |
20160348655 |
Kind Code |
A1 |
MERTEN; Wolfgang ; et
al. |
December 1, 2016 |
SWITCHOVER DEVICE FOR A THICK-MATTER PUMP
Abstract
A switch-over apparatus for a thick-matter pump includes a
housing that forms a pre-fill vessel, which has first and second
inlet/outlet openings and an outlet opening positioned on opposite
sides of the housing. The apparatus further includes a pivot body
positioned within the housing and that forms a duct. The duct
includes a duct inlet configured to pivot between the first and
second inlet/outlet openings and includes a duct outlet configured
to align with outlet opening. The pivot body forms at least one
seal chamber adjacent the duct inlet or duct outlet. The apparatus
further includes an elastic seal positioned within the seal chamber
and includes a support strip positioned within the seal chamber
between the elastic seal and the pivot body. The seal strip forms
first and second oblique-cut ends.
Inventors: |
MERTEN; Wolfgang; (Witten,
DE) ; KOCH; Thorsten; (Witten, DE) ;
SCHNITTKER; Joseph; (Dortmund, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MERTEN; Wolfgang
KOCH; Thorsten
SCHNITTKER; Joseph |
Witten
Witten
Dortmund |
|
DE
DE
DE |
|
|
Assignee: |
Schwing GmbH
Herne
DE
|
Family ID: |
51022294 |
Appl. No.: |
14/901296 |
Filed: |
June 4, 2014 |
PCT Filed: |
June 4, 2014 |
PCT NO: |
PCT/EP2014/061568 |
371 Date: |
December 28, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 15/02 20130101;
F04B 15/023 20130101; F04B 7/0096 20130101 |
International
Class: |
F04B 7/00 20060101
F04B007/00; F04B 15/02 20060101 F04B015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 28, 2013 |
DE |
10 2013 010 768.7 |
Claims
1-12. (canceled)
13. A switch-over apparatus for a thick-matter pump, the apparatus
comprising: a housing forming a pre-fill vessel having a first and
second inlet/outlet opening and an outlet opening positioned on
opposite sides of the housing; a pivot body positioned within the
housing and forming a duct, the duct including a duct inlet
configured to pivot between the first and second inlet/outlet
openings and including a duct outlet configured to align with
outlet opening, wherein the pivot body forms at least one seal
chamber adjacent the duct inlet or duct outlet; an elastic seal
positioned within the seal chamber; and a support strip positioned
within the seal chamber between the elastic seal and the pivot
body, wherein the seal strip forms first and second oblique-cut
ends.
14. The apparatus of claim 13, wherein the support strip comprises
an elastic plastic having a hardness higher than a hardness of the
elastic seal.
15. The apparatus of claim 14, wherein the support strip comprises
Teflon.
16. The apparatus of claim 15, wherein the support strip comprises
bronze.
17. The apparatus of claim 13, wherein the first oblique-cut end
forms a first face that faces a second face formed by the second
oblique-cut end.
18. The apparatus of claim 17, wherein a distance between the first
and second face less than 1 mm.
19. The apparatus of claim 18, wherein the support strip has a
thickness of 1-3.5 mm.
20. The apparatus of claim 19, wherein the thickness is 2.5 mm.
21. The apparatus of claim 13, further comprising: a metal ring at
least partially positioned within the seal chamber, wherein the
elastic seal is directly coupled to the metal ring, pivot body, and
support strip.
22. The apparatus of claim 21, wherein the metal ring includes a
bottom surface in direct contact with a wear plate.
23. The apparatus of claim 22, wherein the bottom surface of the
metal ring comprises a hard-metal coating.
24. The apparatus of claim 23, wherein the hard-metal coating has a
hardness greater than a hardness of the housing.
25. The apparatus of claim 22, wherein the elastic seal is
kidney-shaped.
26. The apparatus of claim 22, wherein the metal ring includes a
side surface facing the pivot body and wherein the pivot body and
metal ring form a gap adjacent the side surface.
27. The apparatus of claim 24, wherein the support strip is
configured and arranged to prevent the elastic seal from migrating
into the gap.
28. The apparatus of claim 13, wherein the pivot body forms two
seal chambers, each chamber having an elastic seal and support
strip positioned therein, wherein the support strips each form
first and second oblique-cut ends.
Description
[0001] The invention relates to a switchover device for a
thick-matter pump as well as to the use of a support strip in such
a switchover device and to the use of a pivot body of such a
switchover device.
[0002] A switchover device for thick-matter pumps can be
configured, for example, as a transfer tube of a concrete pump.
With such a switchover device, concrete is pressed at high pressure
by means of two delivery cylinders via the transfer tube into a
concrete delivery tube. The pressure in the transfer tube of a
concrete pump which may pump concrete by several hundreds of meters
up onto building structures such as bridges or skyscrapers ranges
at up to 160 bar for concrete pumps of the present generation. With
a further increase in pump capacity to is allow for pumping
concrete up to levels higher than 500 meter, pump pressures of 300
bar will be needed in future which will expose the seals of the
delivery system to extreme strains and stresses.
[0003] With a switchover device of this type, the flow of concrete
and/or thick-matter from a pre-fill vessel is pressed into a
sucking delivery cylinder and from a pumping delivery cylinder into
the delivery line. Inasmuch as these are two-cylinder thick-matter
pumps, the inlet and the outlet of the pivot body swinging to and
fro in the housing at the cycle of the piston strokes are connected
to each other through a passage duct in the pivot body.
[0004] This switchover technique puts high demands on the seals of
the switchover device, particularly in order to avoid that the
concrete, and particularly the water contained therein, is pressed
from the passage duct of the pivot body into the pre-fill vessel.
In particular, the water contained in the concrete has the property
of improving fluidity and thus transportability of concrete in the
delivery line. Moreover, too dry concrete leads to clogging in the
delivery line and may entail costly repair measures if concrete
hardens in the deliver line.
[0005] For this purpose, a rubber seal made of hard rubber is
usually laid into the seal chambers of the pivot body, said rubber
seal pressing the pivot body against the two opposite sides of the
housing of the switchover device. Frequently, a hard metal ring is
inserted in addition to the rubber seal so that the rubber seal is
not directly moved to and fro at the housing wall due to the
pivoting motions of the pivot body, but the rubber seal presses the
hard metal ring to the housing sides.
[0006] During the pumping procedure, due to the high pressure of
the concrete in the passage duct of the pivot device, the rubber
seal is pressed outwardly, in particular into a gap between the
hard metal ring and the seal chamber. Owing to the abrasive effect
of concrete, this entails high wear and tear of the rubber seal.
Since an exchange of a rubber seal is very costly and leads to
standstill periods of the concrete pump, it is necessary to
reinforce the rubber seal in the outer circumference in order to
reduce this wear and tear.
[0007] In the printed publication DE 31 13 787 it was already
proposed to provide a rubber seal for a switchover device of the
afore-mentioned type, which is not equipped with the said hard
metal ring, with a metallic support ring on the outer circumference
of the rubber seal which prevents the seal exposed to high pressure
from penetrating into the gap between passage duct and pre-fill
vessel and thus preventing its premature wear and tear.
[0008] A metal support ring of this type, however, is costly in
manufacture and needs to be produced with utmost precision, in
particular for a kidney-shaped seal, in order to fulfill the set
task. Moreover, such a support ring does not have the elasticity
required to sufficiently adapt itself to the circumferential shape
of the seal chamber.
[0009] It is the object of the present invention to improve the
seal of the switchover device of a thick-matter pump by way of
simple and low-cost measures with the aim to increase stability of
the existing rubber seal.
[0010] The present invention achieves this object by way of a
switchover device for a thick-matter pump in accordance with claim
1.
[0011] Advantageous embodiments of the present invention are
indicated in the dependent sub-claims.
[0012] The present invention proposes to arrange a support strip
around the elastic seal and/or the rubber seal within the seal
chamber of the pivot body, said support strip supporting the
elastic seal towards the outside in order to prevent the elastic
seal from migrating into the gap between the seal ring and the
shoulder of the seal chamber.
[0013] Preferably, this support strip is made of elastic plastic,
the hardness of which is higher than the hardness of the elastic
seal. On the one hand, this ensures that the support strip itself
cannot migrate into the gap between the seal ring and the shoulder
of the seal chamber because of an alteration in its shape, and on
the other hand, owing to the existing elasticity of the support
strip, it can easily be adapted to the shape of the seal chamber,
which for example may be round or kidney-shaped.
[0014] Preferably, the support strip is made of a teflon material.
Teflon has got the property of not being attacked so severely by
the abrasive properties of concrete as other rubber or plastic
materials, and thus it has got a long service life.
[0015] Preferably, the support strip made of plastic and/or teflon
contains bronze, whereby its properties improve further, the said
bronze portion in particular increasing the crushing strength of
the teflon strip, thus preventing the risk of migrating into the
gap between the seal ring and the shoulder of the seal chamber.
[0016] Preferably, the support strip has a thickness of 1 to 3.5
mm. The support strip is particularly well suited for fulfilling
the intended task, if it is approx. 2.5 mm thick. If the support
strip is thinner than 1 mm, it itself does not have the necessary
stability required to prevent migration of the elastic seal, and
the support strip itself might migrate into the gap between the
seal chamber and the shoulder of the seal chamber. If the support
strip is too thick, it is no more sufficiently elastic to allow for
easy insertion into the seal chamber and it would demand
unnecesarily much space in the seal chamber.
[0017] The support strip is preferably cut off from a tape which
for example can easily be procured on a roll.
[0018] It is furthermore preferred to cut off the support strip to
a length that is determined by the outer circumference of the seal
chamber. Since the outer circumference of the seal chamber is
relatively constant with all pivot bodies of a product series, the
support strip can simply be cut to the length of the circumference
of the seal chamber, before the support strip is laid into the seal
chamber.
[0019] The support strip is preferably cut off by an oblique cut to
the necessary length and after inserting the support ring, the cut
faces should lie as closely as possible next to each other. This
ensures that the elastic seal cannot migrate at a circumferential
point into a gap of the support strip, thereby restricting its
function and/or being exposed to increased wear and tear at the
gap. Preferably, the remaining gap in the support strip after
inserting into the seal chamber is smaller than 1 mm.
[0020] In accordance with an advantageous embodiment of the present
invention, one opening of the passage duct of the pivot body is
kidney-shaped, with the elastic seal also being kidney-shaped and
being supported by the support strip in the seal chamber.
[0021] With further preference, wear plates are arranged at the
insides of the housing in the area of the inlet openings and/or
outlet openings. These wear plates are preferably made of a metal
having a hardness which is higher than the housing itself, so that
the insides of the housing are exposed to less wear and tear in the
area in which the pivot body is swung to and fro at the housing
wall. Moreover, the wear plates can be exchanged, if required,
without necessitating an exchange of the entire housing.
[0022] Practical examples of the present invention are elucidated
and explained in the following by way of drawings, where:
[0023] FIG. 1: is a schematic representation of a top view on a
switchover device of a thick-matter pump;
[0024] FIG. 2: is a side view of the switchover device from FIG.
1;
[0025] FIG. 3: is a schematic view of a section through a seal
chamber (Detail A) according to prior art in technology;
[0026] FIG. 4 is a schematic view of a cut through a seal chamber
(Detail A) according to prior art in technology during a pumping
procedure;
[0027] FIG. 5 is a schematic view of an elastic seal with a support
strip according to the present invention;
[0028] FIG. 6 is a support strip according to the present invention
in unrolled status;
[0029] FIG. 7 is a perspective view of the cutting edge of a
support strip according to the present invention;
[0030] FIG. 8 is a schematic view of a cut through a seal chamber
(Detail A) according to the present invention during a pumping
procedure.
[0031] FIG. 1 illustrates a schematic view from the top onto a
switchover device 1 for a thick-matter pump. The switchover device
is mainly comprised of an open-top pre-fill vessel 20 with the
housing sides 2a, 2b, 2e, 2f and a bottom 2c, in which a pivot body
3 is arranged. The pivot body 3 mainly comprises a passage duct 17
with an inlet opening 13 and an outlet opening 14. The switchover
device 1 is suitable, for example, to deliver the concrete conveyed
by hydraulically driven delivery cylinders 18a, 18b connected to
the inlet and outlet openings 19a, 19b through the passage duct 17
of the pivot body 3 in the direction of the outlet opening 14 into
a concrete delivery tube 17. In FIG. 1, the delivery cylinder 18b
sucks concrete in a suction stroke from the pre-fill vessel 20 and
the delivery cylinder in a simultaneous delivery stroke pushes the
concrete through the passage duct 17 of the pivot body 3 into the
concrete delivery tube 21. On a periodical alteration of the piston
movement of the delivery cylinders (18a, 18b), the pivot body 3 is
swiftly switched over by means of a non-illustrated hydraulic
unit.
[0032] To ensure a leakproof sealing of the pivot body 3 with the
opposite housing walls 2a and 2b, the pivot body 3 is pressed by
means of the sealing system (Detail A) explained later between the
housing walls 2a and 2b, but still remains movable for the
switchover movement.
[0033] FIG. 2 shows a side view of the switchover device 1 from
FIG. 1, wherein the outlet opening 14 is located on the side facing
the viewer and the inlet and outlet openings 13 are located on the
side averted from the viewer. From FIG. 2, it is especially the
swinging movement of the pivot body 3 in housing 3 that becomes
evident, wherein the pivot body 3 in this drawing is located in
position (a), that means upstream to the left-side inlet and outlet
opening 19a. In both positions (a, b), the kidney-shaped outlet
opening 14 of the pivot body 3 remains in a position upstream to
the outlet opening 15 of housing 2, but the outlet opening 14 of
the pivot body 3 is nevertheless moved to and fro upstream to the
outlet opening 15 of the housing side 2b when swiveled about the
swivel axis 11 from position a to position b and vice versa. While
the change from suction stroke to delivery stroke of the delivery
cylinders takes approx. 3 to 15 seconds, depending on the design
and size of the thick-matter pump, and since the pivot body 3
stands still during this period of time, the pivot body 3 must be
swiveled into the other position within a few tenths of a second
during the switchover. On operation of the thick-matter pump 1, a
pressure P with up to several hundreds bar prevails in the passage
duct 17 both during standstill and during the switchover
procedures, and this pressure also takes effect on the sealing unit
(Detail A).
[0034] FIG. 3 shows a schematic detail view of the sealing system
(Detail A) from FIG. 1 in accordance with prior art in non-burdened
status. It means the pivot body 3 is pressed to have contact with
the housing wall 2b via the elastic seal 16, seal ring 12, hard
metal coating 4 and the wear plate 5 mounted to the housing wall
2b, without there being any pressure of concrete in the passage
duct 17. The seal ring 12 in this case is shown as a metal ring
with a hard metal coating, but it could also be made of a different
solid material that offers high resistivity to the abrasive effect
of concrete on pumping. The hard metal coating 4 is not absolutely
necessary. In the following, however, a configuration with a metal
ring having a hard metal coating is described. The elastic seal 16
which may be comprised of a plastic or rubber material and which
may be reinforced in the interior with a metal ring serves the task
of pre-tensioning the seal ring 12 against the housing wall 2
and/or wear plate 5 in order to seal the passage duct 17 towards
the pre-fill vessel. The elastic seal 16 and the seal ring 12 with
the hard metal coating 4 are laid into the seal chamber 8 which is
confined towards the outside by the nose-shaped shoulder 10. In
non-installed status, the elastic seal 16 shown here would have a
round cross-section. Owing to the fact that the pivot body 3 is
pressed-in between housing walls 2a, 2b, the seal 16 has a slightly
oval deformation, whereby the metal ring 12 with the hard metal
coating 4 is pressed at pressure p to enter into contact with the
wear plate 5.
[0035] To allow the metal ring 12 to migrate forward and backwards
within the seal chamber 8 which is confined towards the outside by
the nose-shaped shoulder 10 so that it will always provide a flush
closure with the wear plate 5, a gap 9 having the width d is
provided for. Since the metal ring 12 is moved also laterally
during the switchover cycles, the width of the gap may vary between
0 and approx. 1 mm in operation. It becomes evident that due to
this movement, also the elastic seal 16 being subjected to the
contact pressure is laterally moved and tumbled.
[0036] FIG. 4 illustrates the sealing system according to FIG. 3 in
operation in conformity with prior art in technology. Because of
concrete being conveyed, a very high pressure P now prevails in the
passage duct 17. This pressure P which presses the metal ring 12
via the seal 16 during the pumping procedure additionally to the
wear plate 5, presses the elastic seal 16 in the direction of the
nose-shaped shoulder 10, and moreover, the elastic seal 16 is moved
laterally to and fro due to the relative movement of the metal ring
12 towards the seal chamber 8 of the metal ring 12.
[0037] The pressure P and the motions of the metal ring 12 involve
that the elastic seal 16 is not only pressed into the direction of
the nose-shaped shoulder 10, but also into the gap 9, whereby on
the one hand the metal ring 12 is virtually clamped, but in
particular the elastic seal 16 in the area pressed into the gap 9
is subjected to a particular high wear and tear.
[0038] FIG. 5 illustrates a kidney-shaped elastic seal 16 as
utilized in a switchover device 3 of a thick-matter pump in
accordance with FIGS. 1 and 2. Around the elastic seal 16, a
support strip 6 made of teflon material is shown which together
with the elastic seal 6 is laid into the seal chamber 8 of the
switchover device. The teflon material 6 may advantageously be
enriched with bronze in order to increase the hardness of the
strip.
[0039] FIG. 6 shows the support strip 6 in unrolled status. The
support strip 6 has the length L which corresponds to the outer
circumference of the seal chamber 8. Clearly visible in FIGS. 5 and
6 are the oblique cutting faces 6a of the support strip 6. These
oblique cutting faces take the effect that the elastic seal 16 is
not point-wise stressed at a circumferential point in case of a
slight gap between the ends (2a) of the inserted support strip 16,
but stressed obliquely over a longer area, thereby distributing the
wear due to a gap between the support strip ends (2a) in the seal
chamber 8 at the elastic seal 16 over a broad range.
[0040] The cutting angle may amount to approx. 30 degrees as
illustrated in the drawing, but it should not be too small so that
the ends of the strip 16 do not become too thin and might slide
into the gap 9 and/or rotate; however, this angle should not be too
large either, because otherwise the elastic seal would be stressed
too much at one circumferential point.
[0041] The height H of the support strip 6 amounts to approx. 1.5
cm, but it should not exceed the height of the seal chamber 8 in
built-in status, because otherwise the support strip 16 is pressed
between the metal seal 12 and the upper end of the seal chamber 8,
and the elastic seal 16 would no longer be able to fulfill its
function of pressing the metal seal 8 to the wear plate. On the
other hand, the height H of the support strip 6 should not be much
lower than the height of the seal chamber 8, because otherwise a
gap would occur above or below the laid-in support strip 6 into
which the elastic seal 6 might unintentionally penetrate.
[0042] FIG. 7 shows a view of the oblique cutting face 6a of the
support strip 6 with the thickness D. The thickness D of the
support strip here for example amounts to 2.5 mm, but it could also
vary between 1 mm and 3 mm. The minimal thickness D should not be
less than the maximal width d of gap 9, because is otherwise there
would be a risk in that the support strip 6 migrates into the gap 9
and obstructs the mobility of the metal seal in the seal chamber 8.
Conversely, if the support strip is configured with too much
thickness, it does not leave sufficient space for the elastic seal
16 in the seal chamber 8.
[0043] Figure illustrates a sealing system according to FIG. 1,
Detail A, in which the support strip 6 is circumferentially laid
around the elastic seal 16 in the seal chamber 8. Here it is
clearly visible that at the pressure P of pumped concrete 7
prevailing in the seal chamber 8 which is open towards the passage
duct 17 (the direction of flow is illustrated here by way of the
larger downwardly directed arrow, whereas the effect of pressure P
on the elastic seal 16 is illustrated by way of the smaller arrows
directed towards the right side), the elastic seal is deformed only
slightly. Furthermore, the metal ring 12 is pushed to and fro
during the switchover cycles due to the frictional force
F.sub.R.
[0044] In this figure, it becomes clearly evident that the elastic
seal 16 is pressed into the direction of the nose-shaped shoulder
10 and becomes slightly deformed during this procedure, but the
support strip 6 prevents the elastic seal 16 from migrating into
gap 9 as it is subjected to pressure P. Thereby, wear and tear to
the elastic seal 16 is substantially reduced and the metal ring 12
is not restricted in its mobility.
[0045] It should still be noted that the support strip 6 shown here
may not only be utilized in the kidney-shaped seal chamber 8 of the
switchover device illustrated here, but for example also at the
round inlet opening 13 on the other side of the pivot body 3 in
order to seal the inlet and outlet openings during the pumping
cycle.
[0046] Furthermore, the use of such a support strip 16 is not
limited to the design version of a switchover device illustrated
here, but it could also be utilized for example in S-shaped
switchover valves for sealing at inlet and outlet openings.
* * * * *