U.S. patent application number 10/590615 was filed with the patent office on 2008-10-23 for piston pump for thick materials.
Invention is credited to Manfred Lenhart.
Application Number | 20080260560 10/590615 |
Document ID | / |
Family ID | 34917055 |
Filed Date | 2008-10-23 |
United States Patent
Application |
20080260560 |
Kind Code |
A1 |
Lenhart; Manfred |
October 23, 2008 |
Piston Pump for Thick Materials
Abstract
The invention relates to a multi-cylinder thick matter pump (1)
which is used to continuously deliver especially concrete. Said
thick matter pump comprises at least two delivery cylinders (3, 5)
which transport the thick matter from a prefill tank (7) into a
delivery pipe and a reversing valve (9) for alternately linking the
delivery cylinders with the delivery pipe. The invention is
characterized in that the reversing valve (9) comprises two pilot
valves (15, 17) which can be displaced in a substantially
translatory manner. Every pilot valve (15, 17) comprises a straight
pipe section (15L, 17L) for linking the respective assigned
delivery cylinder (3, 5) with the delivery pipe. Said pipe section
can be linked with a manifold (19) in a pipe position downstream of
the delivery cylinder. The invention also relates to a method for
operating the inventive thick matter pump for continuous
delivery.
Inventors: |
Lenhart; Manfred; (Haltern
am See, DE) |
Correspondence
Address: |
VAN DYKE, GARDNER, LINN & BURKHART, LLP
SUITE 207, 2851 CHARLEVOIX DRIVE, S.E.
GRAND RAPIDS
MI
49546
US
|
Family ID: |
34917055 |
Appl. No.: |
10/590615 |
Filed: |
January 26, 2005 |
PCT Filed: |
January 26, 2005 |
PCT NO: |
PCT/EP05/00747 |
371 Date: |
September 25, 2007 |
Current U.S.
Class: |
417/516 |
Current CPC
Class: |
F04B 15/02 20130101 |
Class at
Publication: |
417/516 |
International
Class: |
F04B 15/02 20060101
F04B015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 26, 2004 |
DE |
10 2004 009 362.8 |
Claims
1-33. (canceled)
34. A multi cylinder thick materials pump for providing concrete
comprising: at least two feeding cylinders for feeding thick
material from a pre filling container into a feed line; a shift
valve for alternatively connecting the feeding cylinders with the
feed line associated with it; the shift valve comprising at least
two moveable valve bodies, each body comprising a transfer section
between each of the feeding cylinders and the feed line, the shift
valve being connected downstream of the feeding cylinders to a
collector tube, and the shift valve comprising two substantially
translatorically movable control slides, each slide including a
straight transfer section for connecting each of their associated
feeding cylinders with the feed line and a blocking section
blocking the connection.
35. A thick materials pump according to claim 34, wherein the shift
valve includes a guidance structure for the control slides, the
guidance structure having openings for passing through thick
materials flows.
36. A thick materials pump according to claim 35, further
comprising a pre filling container, said control slides each having
an inlet opening, and the guidance structure being mounted into the
pre filling container in a fixed manner so that the control slides
and their inlet openings are always in contact with the thick
material filled in.
37. A thick materials pump according to claim 35, wherein the
guidance structure is substantially shaped as a box or a frame, the
box or frame forming a separate guide for each control slide.
38. A thick materials pump according to claim 34, wherein the
control slides can each be positioned within the guidance structure
in at least two different positions, the two positions including a
transfer position wherein the feeding cylinder can eject into the
collector tube, and a blocking- or inlet position wherein the
feeding cylinder can suck thick material out of the pre filling
container.
39. A thick materials pump according to claim 34, wherein the
control slides are substantially identically.
40. A thick materials pump according to claim 34, wherein at least
one of the control slides is divided into three sections along its
stroke, one of the three sections being the transfer section and
another of the three sections being an inlet section.
41. A thick materials pump according to claim 40, wherein the
blocking section is provided between the transfer section and the
inlet section.
42. A thick materials pump according to claim 40, wherein the
sections of the control slides are provided as single modules and
connected to each other in a disconnectable manner.
43. A thick materials pump according to claim 34, wherein the
guidance structure includes at least one flap for removing thick
material from the transfer section of one of the control
slides.
44. A thick materials pump according to claim 43, wherein the flap
is a common flap for both of the control slides.
45. A thick materials pump according to claim 34, wherein the
control slides are drivable and positionable independently from
each other.
46. A thick materials pump according to claim 45, further
comprising a drive for the control slide, the drive including a
tandem lifting cylinder array within two serially connected lifting
cylinders, each of the cylinders having a stroke corresponding to
the travel of the control slide from one position into a
neighboring position.
47. A thick materials pump according to claim 45, further
comprising a drive for the control slide, the drive including a
telescoping lifting cylinder with two lifting stages, each of the
stages of the cylinders corresponding to the travel of the control
slide from one position into a neighboring position.
48. A thick materials pump according to claim 46, wherein the
lifting cylinders are located in parallel next to the control
slides, said cylinders being coupled with the slides via consoles,
and the guidance structure including the control slide guides for
the consoles.
49. A thick materials pump according to claim 34, wherein the
transfer section of each control slide comprises a cylindrical tube
with the same diameter as the feeding cylinders.
50. A thick materials pump according to claim 40, wherein a
rerouting system is provided in the inlet section of at least one
control slide.
51. A thick materials pump according to claim 34, further
comprising a control unit and position indicators, the position
indicators providing to the control unit momentary positions of the
shift valve and the control slides as well as of the feeding
pistons of the feeding cylinders, and the control unit controlling
drives of the control slides and of the feeding pistons according
to a predetermined time distance pattern in a cyclical manner.
52. A process for operating a thick materials pump for continuous
feeding comprising: providing a thick materials pump, the pump
comprising at least two open feeding cylinders with feeding pistons
and a shift valve with control slides, which are controllable
independently from each other and adapted to the motion of the
feeding pistons, each control slide including at least one transfer
section for connecting an associated feeding cylinder with a feed
line and an intake section for sucking in thick material from a pre
filling container through the associated feeding cylinder; and
controlling a synchronous travel phase of the feeding pistons in a
cyclical manner while its at least two control slides are located
in a transfer position, wherein its transfer sections connect the
associated feeding cylinders to the feed line for preliminary
simultaneous expulsion of thick material.
53. A process according to claim 52, further comprising adjusting
the feeding pistons in the synchronous travel phase to each other,
so that the thick materials quantity pumped by the pistons
simultaneously is approximately equal to feeding through one piston
alone during the suction stroke of the respective other piston.
54. A process according to claim 52, further comprising momentarily
closing the opening of each feed cylinder at the beginning of the
pump stroke of each feeding piston of each feeding cylinder through
the blocking section of the control slides.
55. A process according to claim 54, further comprising providing
each pump stroke of a piston with a pre compression phase, a first
synchronous phase, a pump phase, and a second synchronous
phase.
56. A process according to claim 52, further comprising driving
both feeding pistons during the synchronous travel phase at the
same speed.
57. A process according to claim 52, wherein upon a pump stroke a
transition phase with a stand still of a feeding piston during a
continuing pump stroke of the other feeding piston follows.
58. A process according to claim 52, wherein the suction stroke of
each piston is faster than its pump stroke, in particular between a
transition phase and a pre compression phase.
59. A process according to claim 58, further comprising providing
each suction stroke of a piston with a start ramp and a stop ramp
with a reduced velocity.
60. A process according to claim 52, further comprising slowing
down or stopping momentarily the control slides during the
synchronous phases.
61. A process according to claim 52, further comprising slowing
down or stopping momentarily the control slides in a pre
compression phase.
62. A process according to claim 52, further comprising slowing
down or stopping momentarily the control slides in a transition
phase.
63. A process according to claim 52, further comprising slowing
down or stopping momentarily the control slides in a suction
phase.
64. A process according to claim 52, further comprising positioning
the control slides in an operating position in the operational
pauses of the thick materials pump, and allowing the removal of
remaining thick material and the insertion of a cleaning body when
required.
65. A process according claim 64, further comprising providing the
operational position at the inlet position of the control
slide.
66. A process according to claim 64, further comprising providing a
safety device for preventing the starting of the control slide, and
activating said safety device during the removal and/or insertion
process.
67. A process according to claim 47, wherein the lifting cylinders
are located in parallel next to the control slides, said cylinders
being coupled with the slides via consoles, and the guidance
structure including the control slide guides for the consoles.
Description
[0001] The present invention regards a pump for thick materials
with features according to the non characterizing part of patent
claim 1. In a broader sense it also regards the controls of such
thick materials pumps.
[0002] Thick materials piston pumps have been used for a long time
in particular at construction sites to feed concrete. Usually they
are provided as hydraulically operated piston pumps, mostly with
two cylinders, feeding concrete through hoses or pipes.
Subsequently, in a simplified manner, concrete feeding is being
referred to. The invention is not limited to an application with
concrete feeding pumps but can be used for all similar thick
materials pumps.
[0003] Such pumps have to fill a single feed line with two
alternatively filled cylinders and associated pistons. The
respectively filled cylinder is being connected with the feed line
via a moveable pipe switch. Subsequently the piston pushes out the
concrete (pump stroke), while the parallel piston is being
retracted, in order to fill the cylinder with concrete again
(suction stroke). At the end of each stroke the moving direction of
the cylinder pistons is reversed and the pipe switch is shifted, so
that pump strokes and suction strokes alternate continuously. The
two pump pistons are preferably driven hydraulically coupled
amongst each other, so that they basically work in a counteracting
manner.
[0004] Common pipe switches (DE 29 33 128 C2) are arranged, so that
they can be switched back and forth between two end positions,
wherein they alternatively establish the connection between the
cylinder openings and the feed line on the one hand, and the pre
filling container on the other hand. From this results a
discontinuous feeding.
[0005] U.S. Pat. No. 3,663,129 describe a concrete pump with
continuous feeding, wherein the shift valve or its pipe switch
consists of a so called sleeve slide. Its waist opening is
continuously but pivotally connected with the mouth of the feed
pipe as a downstream outlet. Its kidney shaped inseam opening
(inlet, upstream) is long enough to cover the openings of both pump
cylinders simultaneously. During the operation the pipe switch
performs a continuously oscillating pivoting motion, whose axis is
coaxial with the mouth of the feed pipe. The pivoting angle of the
pipe switch is approximately 50.degree. towards both sides from the
middle.
[0006] The pistons of the pump cylinders are controlled depending
on the momentary position of the pipe switch, so that in the moment
when both cylinder openings are covered by the sleeve opening, one
cylinder is at the end, and the other cylinder is at the beginning
of a pump stroke. Thereby the feeding action continuously shifts
from one cylinder to the other. In the state of the art control
system for the suction stroke and for the pump stroke of each
cylinder the same time span is used. Therefore there is no
simultaneous feeding of both cylinders.
[0007] Due to the one sided bearing of the state of the art pipe
switch on the side of the feed pipe and due to the enveloping
support and sealing surfaces only surrounding the sleeve opening,
the substantial tilting moments of the state of the art design can
not be completely received. It can not be excluded, that due to gap
formation substantial leaking losses occur in the seal area between
the sleeve opening of the pipe switch and the feeding cylinders,
which in turn denies the realization of a really continuous feed
action.
[0008] The British Patent 1,063,020, as a gender defining state of
the art describes a multi cylinder thick materials and concrete
pump, whose shift valve in one embodiment comprises two rotating
slides, (also formed as sleeve valves), each controlled by a
lifting cylinder of their own. Their outlet ports are connected
with a common Y-tube, which in turn is connected to the feed line
downstream. Each rotating slide can either work together with a
single, or with two pump cylinders. Though synchronous control of
the rotating slides is mentioned, however with this state of the
art pump and control system continuous feeding of the feeding
cylinder into the common feed line is neither intended nor
possible.
[0009] DE 30 06 542 C2 describes a guillotine flat valve for two
cylinder thick materials pumps. It comprises a guillotine flap
solidly connected with a control rod, which can be alternately
moved back and forth between two end positions in a guide housing
or -frame. This state of the art 2/2 way guillotine valve can also
be installed between the flanges of a Y-tube and an intake or
exhaust tube. In concrete pumps it is preferably installed between
the bottom of a prefilling container and the exhaust pipes of a
two-cylinder piston pump and/or the feed line and the exhaust
pipes.
[0010] Furthermore it is also state of the art, to provide thick
materials pumps of the kind that is being discussed here, with an
insertion station, through which a cleaning body for removing
unused thick materials, which have remained in the feed line, can
be inserted. This insertion station comprises e.g. a chamber slide,
moveable by a motor or hydraulically, with at least two chambers of
equal cross section. In the resting position of the insertion
station the one chamber forms a section of the feed line, while the
other chamber is freely accessible. Into the latter the said
cleaning body can be manually inserted from the outside. For a
cleaning procedure, with the thick materials pump shut down, the
insertion station is shifted into a working position, wherein the
chamber containing the cleaning body replaces the other chamber
within the feed line. Then the cleaning body can be pressed through
the feed line with compressed air, whereby it pushes the thick
material ahead of itself. These state of the art insertion
stations, however have to be provided in addition to the shift
valve discussed above.
[0011] The objective of the invention is to provide an improved
thick materials pump and a process for controlling a thick
materials pump with continuous feeding.
[0012] This objective is accomplished according to the invention
with the features of patent claim one, with respect to the control
process with the features of the independent claim 19.
[0013] The features of the dependent claims associated with the
independent claims provide advantageous improvements of the
invention.
[0014] While with the pumps according to the above explained U.S.
and GB patents the control slides are mostly located at the thick
materials container in an exposed manner, through providing the
shift valve with two translatorically movable, in particular linear
guided control slides, an embodiment, less exposed to the thick
material especially to the concrete, can be created for the
preferred application. On the one hand this is valid for abrasive
uses, but also for loading through dynamic pressure in the feed
line or in the feeding cylinders. In the area of the control slides
the thick material is, different from the known sleeve slides, not
redirected under pressure, but substantially run through the tubing
sections in a straight manner. Only in the collector tube (also
Y-tube) the concrete flows from the feeding cylinders are merged.
This substantially contributes to the pressure relief of the slides
themselves and does not only reduce the loads on the bearings, but
also reduces the frictional forces when switching the control
slides. Consequently this engineering solution noticeably reduces
mechanical wear of the moveable and non moveable parts of the shift
valve.
[0015] It should be noted that, though a two cylinder thick
materials pump is discussed here in an a preferred embodiment, the
design according to the invention can also be transposed to pumps
with three or more cylinders, wherein a control slide would have to
be associated with each feeding cylinder.
[0016] It is not absolutely necessary to guide the control slides
in an exactly linear manner, but according to the invention a
slight arc can be provided, whereby the major part of the motion
remains translatoric.
[0017] Though it is conceivable to support the parallel control
slides directly at the surfaces facing each other, preferably
however the guidance structure for each control slide will have a
dedicated slide rail allowing larger offsets of the control slides
during their operational cycles.
[0018] For providing the shift valve (guidance structure and
control slide) with sliding guides with friction and abrasion
resistant materials and possibly with wear parts known means can be
applied, so this does not need to be discussed in detail. The same
applies for the seals between the control slides and the openings
of the feeding cylinders and the collector tube.
[0019] According to the invention it is advantageous, when the
control slides can occupy three different positions, a transfer
position, a blocking position and an inlet position. To these three
positions corresponds a design or a subdivision of the control
slides into three different sections, this means a transfer
section, a blocking section and an inlet section. The names of the
sections or positions are self explanatory and will be discussed in
connection with the description of the attached figures.
[0020] It is advantageously possible to provide/prefabricate the
above mentioned sections as single modules and assemble them in the
required order. Overall a control box or a control cage with the
necessary valve travel or functions is created. This design can
favor the simple replacement of single, prematurely worn or damaged
sections, in particular when connections are provided amongst them,
that can be disassembled.
[0021] It is understood that the two control slides are
advantageously provided identical amongst each other; variations
can result from space constraints, when attaching the respective
drive systems.
[0022] A substantial advantage of the solution according to the
invention is the simply applicable option to use at least one,
possibly both control slides of the shift valve also as insertion
station(s) for the cleaning bodies. The short tubing sections of
the control slides and the feed line have to be cleaned during
operation shut down of the pump, this means residual thick material
or concrete leftovers have to be removed.
[0023] For this purpose the invention provides access to the
control slides. This can be provided e.g. through flaps, which are
normally closed, but provide access to the control slides after
opening.
[0024] For this a separate cleaning- or insertion position of the
control slide(s) can be provided. According to an advantageous
refinement, however the inlet position of the control slide is used
as insertion position for the cleaning bodies at the same time.
This is possible, because in this inlet position the tubing cross
section of the control slides is without function and also without
pressure.
[0025] Based on the state of the art initially discussed such a
combination is neither provided, nor easily possible.
[0026] As drives for the control slides preferably hydraulic
positioning cylinders are used. However other suitable drives, e.g.
electric motors, linear gear drives, etc. can be used.
[0027] In a first practical embodiment two serially coupled
(working both ways) lifting cylinders can be used. In this
configuration the stroke of each of the cylinders corresponds to
the shifting distance of the associated control slide from one
position into the next. When both cylinders are completely
retracted, the control slide is in its lowest position (e.g. inlet
position). When a cylinder is extended, the control slide moves
into its middle position (e.g. blocking position). When also the
second cylinder is being fully extended the control slide reaches
its top position (e.g. the transfer position).
[0028] It is understood that the same effect can also be
accomplished with a two stage lifting cylinder (telescoping
cylinder), whereby its middle position, however has to be exactly
controllable and lockable, in order to assure defined shifting
positions of the control slides.
[0029] Besides locking the respective positions of the control
slides directly and only through their drives, dedicated locking
mechanisms certainly can also be provided, preferably engaging
directly between the guidance structure and the control slides.
These locking mechanisms can also be operated remotely, this means
engaged and disengaged. Furthermore it is also conceivable to
spring load such locking mechanisms in locking direction, so that
they lock by themselves when the control slide moves into the
position to be fixated.
[0030] In case the above mentioned drive lifting cylinders are not
to be located coaxial with the control slides, e.g. because of
space constraints, they can be located parallel next to the control
slides. In this case a load transfer in a perpendicular direction
between the control slides and the rod end pieces of the lifting
cylinders has to be provided, e.g. a cross beam or a console. For
this a respective opening in the guidance structure for the control
slides must be provided, so it can follow the lateral movements of
the slides.
[0031] Depending on the mounting conditions, the lifting cylinders
can also be located at an angle relative to the control slides, if
a suitable lever- or angular gear system can be installed for
adjusting the respective control slide positions.
[0032] Further details and advantages become evident from the
drawing of an embodiment and it's following detailed
description.
[0033] In a highly simplified and purely schematic illustration it
is shown in:
[0034] FIG. 1 a perspective view of the assembly of the thick
materials pump with additional functional components;
[0035] FIG. 2 a cross section side view of the thick materials pump
with a multiple control slide shift valve according to the
invention;
[0036] FIG. 3 a cut view through the middle axis of the feeding
cylinders of the thick materials pump according to FIG. 2 (line
II-II) for emphasing the location of the feeding cylinder, the
shift valve and the collector tube;
[0037] FIG. 4 a frontal view, tilted by 90.degree. relative to FIG.
2 (cut along the line III-III in FIG. 1) of the shift valve with
two parallel control slides;
[0038] FIG. 5 a time-distance-diagram of the phase shifted strokes
of both pistons of the thick materials pump relative to the
respective positions of the two control slides;
[0039] FIG. 6 a first drive variant for a control slide, comprising
two hydraulic lift cylinders in tandem arrangement;
[0040] FIG. 7 a second drive variant for a control slide comprising
a telescopic cylinder, extendable in two stages, and
[0041] FIG. 8 a third drive variant for a control slide comprising
a single long stroke lifting cylinder
[0042] FIG. 1 shows the perspective outlines of a thick materials
pump 1 with two parallel feeding cylinders 3 and 5, lying next to
each other, a prefilling container 7, a shift valve 9, a collector-
or Y-tube 19, as well as a short section of a feed line. The shift
valve is located in a housing, or in a guidance structure 11,
reaching through the bottom of the prefilling container 7. Close to
the bottom of the guidance structure, on the side facing the
feeding cylinders 3 and 5, a maintenance flap 13 is provided. Above
the prefilling container, like an explosion drawing two control
slides 15 and 17 are shown, which are intended for moveable
insertion into the housing shaped guidance structure 11 of the
shift valve 9, forming its valve body. This will be subsequently
explained in detail.
[0043] FIG. 2 only shows the feeding cylinder 3 of the thick
materials pump 1, which is located in the front of this view, in
the area of its open (exhaust) end. The associated piston is not
shown. The second feeding cylinder 5 is located behind the feeding
cylinder 3 and covered in viewing direction. It is visible again in
FIG. 3 from the top. Both pistons of the feeding cylinders 3 and 5
are driven independently from each other (preferably hydraulically)
and can in principle operate at any relative position or velocity
within the limitations of their strokes and their control systems.
However it is also possible to operate them in hydraulically
coupled manner. Both cylinders and pistons have the same diameter,
e. g. 250 mm.
[0044] The funnel shaped prefilling container 7, of which only the
lower part (bottom part) is visible, is open at the top and is
bolted to the open ends of both feeding cylinders 3 and 5. The
thick material to be supplied by the thick material pump is poured
into it from the top. The openings of both feeding cylinders 3 and
5 exit in the lower area of the prefilling container 7. Thereby a
maximum filling level of thick material remains above the cylinder
openings when thick material is sucked into the feeding
cylinders.
[0045] In the bottom of the prefilling container 7 a shift valve
designated 9 in its entirety is located in a known manner. Only
through this shift valve 9 the thick material reaches the feeding
cylinders 3 and 5, and only via this shift valve the feeding
cylinders eject the thick material into the feed line, which is not
shown, as will be described in detail later.
[0046] The shift valve 9 comprises a nonmoving guidance structure
11, which is mounted solid to the prefilling container 7. It
protrudes to a certain extent upwards into the prefilling
container, and also reaches downwards through its bottom.
[0047] It should be noted, that in this example only a vertical
installation of the guidance structure is referenced. However this
is not mandatory.
[0048] In principle the guidance structure 11 can be provided as an
open frame, in particular shaped like a shelf. Preferably it is
constructed as a substantially closed box with several functional
openings, which in particular in its upper area which is located in
the prefilling container, is kept open far enough in order to
provide an undisturbed inflow of the thick material to the shift
valves, also directly at the bottom of the prefilling container.
Thereby, besides an upper opening also an open side, e.g. towards
the feeding cylinders can be advantageous, without thereby
compromising the exact guidance of the control slides in this
area.
[0049] In the lower section of the guidance structure 11, outside
the prefilling container 7 a flap 13 is located, which is normally
closed. By opening the flap 13 access to the interior of the
guidance structure 11 is provided, which is shaped like a box or a
housing in the embodiment shown.
[0050] The latter forms a linear guide for the two control slides
15 and 17 (the latter is visible in FIGS. 1, 3 and 4, and FIG. 2,
it is covered however as well as the feeding cylinder 5). These
provide the connection between the feeding cylinders on the one
hand and a collector tube 19 on the one hand, and the feed line
connecting to it, on the other hand, which is not shown here. The
feed tube 19 and the beginning of the feed line preferably are at
the same elevation as the axis of the feeding cylinders 3 and
5.
[0051] Since both control slides are preferably identical,
subsequently the control slide 15 is described in lieu in more
detail in FIG. 2. Its sections starting with "15" are present at
the control slide 17 in the same manner.
[0052] The control slide 15 can be positioned within the guidance
structure, relative to its longitudinal extension, in three
different predefined shifting positions; this is performed through
a drive system which is to be discussed later. It also comprises
three different functional sections. On top is the inlet section 15
E. It is open towards the prefilling container and towards the
feeding cylinder 3, so it has an opening in the direction of its
longitudinal axis and another one perpendicular to it. For
redirecting the thick material by 90.degree. from the prefilling
container into the feeding cylinder, a feed slide 15S, this means a
spherically curved gutter section is inserted. Its free cross
section preferably corresponds approximately to the cross section
of the feeding cylinder 3 and preferably forms a (deflection) angle
of 90.degree.. In its place an appropriately angled elbow tube,
possibly with an inlet that is expanded like a funnel can be
provided and integrated into the structure of the control slide.
This inlet section 15E becomes functional, when the control slide
15 within the guidance structure 11 is positioned in its lowest
position. At the same time the section 15E is closed on the surface
pointing away from the feeding cylinder 3, forming a sealing
surface 15D towards the collector tube 19. Thereby it is
accomplished, that in the inlet position of the control slide 15 no
connection exists to the collector tube, or that it remains closed
also relative to the prefilling container 7. As will become clearer
later, this enables a feed operation of the other respective
feeding cylinder during the refilling of the one feeding cylinder
in the sense of a continuous feed.
[0053] Below the inlet section 15E follows a locking- or blocking
section 15B of the control slide 15. This only has the purpose of
blocking the connection between the feeding cylinder and the
collector tube 19, visible to the right of the shift valve, on both
sides. When the control slide is in the middle of its three
positions, the blocking section 15B lies in front of the opening of
the feeding cylinder. After filling with thick material it can
perform a short pre compression stroke, in order to adapt the
pressure in the freshly filled in thick material to the pressure in
the feed line, connected to the collector tube. At the same time a
reverse impact onto the pressure in the feed line is avoided
through the sealing surface 15D towards the collector tube 19.
[0054] The blocking section, which does not have any flow guiding
function, will be kept as short as possible, provided that it
assures a safe blockage of the feeding cylinders, also against a
substantial precompression pressure. An extension of a little more
than 250 mm (also a little larger than the diameter of the feeding
cylinders) should be sufficient, with exact positioning capability
furthermore provided.
[0055] At the very bottom in the control slide 15 lies a transfer
section 15L, preferably comprising a short, in particular straight
tube section, open on both sides having the same interior cross
section as the feeding cylinder 3. This adaptation of the shape and
size of the transfer section 1 5L can be seen well in FIG. 2, as
well as in FIG. 3. During the operation of the shift valve and of
the thick material pump it is constantly filled with thick
material.
[0056] As mentioned above, the mentioned sections can be considered
single modules, that can be prefabricated and assembled into a
control slide.
[0057] Overall the control slides form a 3/3 way valve together
with the inlet slides, the openings of the feeding cylinders and
the openings of the collector tube as paths, and with the three
above described positions.
[0058] In FIG. 3 on the right side the geometric layout of the
intake section (here 17E) next to the gutter (17S) of the control
slide (here 17) on the feeding cylinder (here 5), as well as the
position of the sealing surface 17D in front of the opening of the
collector tube 19 can be recognized. Here the thick material can
flow from the prefilling container 7 only via the slide 17S into
the opening of the feeding cylinder 5; the same holds for the
respective inlet position of the control slide 15.
[0059] Here also the side walls 15W, 17W of the control slides can
be seen. These can be completely closed and are preferably made
from a suitable flat material. On the top and on the bottom between
the respective sections, cross members have to be provided between
the side walls, in order to unite these into a stiff box forming
the frame for the sections and components of the control slides.
This frame e.g. has in the embodiment shown a planform of
approximately 300 mm by 300 mm and is approximately 800-900 mm
tall.
[0060] Thereby a width of approximately 300 mm is defined by the
diameter of the feeding cylinder of 250 mm. The height is
determined through the design of the control slide in 3 sections.
The depth (dimension in longitudinal direction of the feeding
cylinder) given above also at approximately 300 mm, can be adapted
to the respective installation requirements, in order to provide an
inlet cross section as big as possible for the slides, it should
however not be smaller than the cross section of the feeding
cylinders themselves.
[0061] Furthermore FIG. 3 also shows some design details of the
layout of the guidance structure 11, thus the side walls 11W and
the middle rim 11M. These form guide surfaces or rails for the
control slides 15 and 17. The layout of the details of the guide
elements is subject to the choice of appropriate and wear resistant
materials and shapes through a person skilled in the art.
[0062] In this cut view the shape and the technical function of the
collector tube 19 becomes more apparent. It is provided as a Y-tube
in a known manner, whose two branches each are connected to a
control slide 15 or 17 and its "mouth" or intake flange 20 is
directly connected to the feed line, which is not shown in more
detail.
[0063] The free cross section of the feed line in the mouth area is
smaller than in the intake area towards the control slides.
[0064] The compactness of the set up due to the directly adjacent
control slides can be seen very well in FIG. 4. In this cut view of
the guidance structure 11, the control slides 15 and 17 positioned
next to each other at different elevations and of the prefilling
container 7 it is emphasized, that the bottom of the latter is
penetrated by the guidance structure 11. Its bottom 11B is located
by 2/3 of the height of the control slides below the bottom of the
prefilling container. The walls 11W of the guidance structure and
its middle rim are visible in their full extension; they are by
about 2/3 longer than the control slides 15 and 17 themselves.
[0065] It is not mandatory to provide the walls of the guidance
structure in a fully enclosed manner, if the guiding elements for
the control slide do not require it. However, for safety reasons
(penetration of foreign objects, preventing people from reaching in
unintentionally, etc. accident risks) it can be advantageous to
keep them closed.
[0066] Also a bottom 11B of the guidance structure is shown here as
closed. However it can be useful to provide it in a perforated
manner, or with a dump flap in order to drain water seeping in
between the control slides and the guidance structure and in order
to avoid motion restricting air pockets during the downward travel
of control slides.
[0067] The two feeding cylinders 3 and 5 are located longitudinally
in viewing direction, covered behind the guidance structure 11. The
control slide 15 is at the same elevation as in FIG. 2 and FIG. 3
this means in its maximum possible (transfer)-position. The control
slide 17 is also shown in its inlet position according to FIG. 3,
its lowest possible position within the guidance structure 11.
[0068] Thereby, for the moment the transfer section of the control
slide 15 is positioned in front of the opening of the feeding
cylinder 3 (located behind it and covered up). The latter is
momentarily connected with the collector tube 19 and the feed line
in a fluidic manner, so that it can eject the filled in and
precompressed thick material.
[0069] On the other hand the inlet section 17E of the control slide
17 lies in front of the opening of the feeding cylinder 5, so that
the feeding cylinder 5 is connected with the prefilling container
7, so it can be refilled.
[0070] In FIG. 5, which will be discussed later, this corresponds
to the phase 7 of the motion phases of the shift valve.
[0071] At the same time the transfer section 1 7L of the control
slide 17, at its lowest position, is located at the elevation of
the flap 13, indicated by a dashed circle (See FIG. 1). It should
be noted in this context that flaps 13 can be provided for each
control slide 15 and 17, and that the flaps 13, due to the close
vicinity of both control slides in the guidance structure, can also
form a common maintenance and dump flap for both control slides 15
and 17. It would then certainly have to be wide enough to provide
unrestricted access (in particular for inserting cleaning bodies)
into both control slides (or their respective tubing section). Onto
these flap(s) no pressure will be exerted during normal operation,
so that they do not have to be very strong, or do not have to be
sealed in particular. However they should, as mentioned above, be
safely lockable against opening during the operation of the shift
valve 9.
[0072] It is evident, that through locating the guidance structure
11 at the elevation of the bottom of the prefilling container 7,
the advantage can be reaped, that the respective inlet sections of
the control slides bridge an elevation difference of the thick
materials flow by themselves. As can be seen clearly in FIG. 2, the
thick material flows in from the top and downward following
gravity, offset by the height of the inlet section (approximately
250-300 mm) sideways (after a deflection of 90.degree. into the
feeding cylinder. The real bottom of the prefilling container is
therefore located slightly above the openings of the feeding
cylinders 3 and 5, hereby basically the advantage of the static
pressure in the area of the cylinder openings is used in order to
facilitate refilling and sucking in.
[0073] The respective middle position of the control slides
("blocking position") lies in the exact middle between the extreme
positions of the control slides 15 and 17, shown in FIG. 3. It can
either be adjusted and fixated directly through the drives, or
additional mechanical locking devices or rests for securing the
shifting positions in a defined manner can be provided as mentioned
above. The latter however are not shown here.
[0074] In FIG. 4 also drive variants mentioned above are shown in a
highly schematic manner. On the left, at the control slide 15 a
tandem lifting cylinder assembly 21 is provided. Onto a fixed point
23 a first lifting cylinder 25 is mounted, whose rod end piece
carries an additional lifting cylinder 27. The rod end piece of the
latter is connected through a console 29, which is only shown in
principle, with the flat slide 15. Certainly in the guidance
structure 11 a longitudinal opening is provided, wherein the
console 29 is guided in a sliding manner. Both lifting cylinders
are provided in a double acting set up. The lifting cylinder 27 has
to be provided with flexible feed lines.
[0075] Visibly both rod end pieces of the lifting cylinders 25 and
27 are fully extended. Through reversing one of the rod end pieces,
the control slide 15 can initially be brought into its middle
position (blocking position). When also the second rod end piece is
retracted, the control slide reaches its lower position (inlet
position). In reverse moving direction the rod end pieces are then
extended one after the other, whereby the strokes of the lifting
cylinders 25 and 27, in a suitable set up, jointly define the
positions of the flat slide exactly.
[0076] On the right side the drive of the flat slide 17 is
alternatively provided as a double acting 2 stage telescopic
cylinder 31. It is directly located between a fixed point 33 and a
console 35, which is only shown in principle, which is in turn is
connected with the control slide 17 in a solid manner. It is also
moveable in the guidance structure 11 through a longitudinal
opening. Since the control slide 17 is in its lowest (inlet -)
position, also the lifting cylinder 31 is fully retracted. Through
extending its rod end piece into a first stage or lifting position,
it positions the control slide 17 in its blocking position, in a
second stage, through further extension of the rod end piece, the
control slide 17 reaches its transfer position.
[0077] Again, with reference to FIG. 2, it becomes apparent in
connection with the low position of the control slide 17 in FIG. 2,
that after opening the flap, or the flaps 13, thick material still
remaining in the tubing sections 15L or 17L (the latter shown in
dashed lines) can easily be removed. During normal operation of the
shift valve it is certainly not necessary, since this relatively
small amount, or column of thick material is ejected again into the
collector tube and into the feed line, with the next feed or
ejection stroke.
[0078] Since the transfer section in this position is completely
separated from the feed line, there is no elevated pressure in it.
Besides that, it will be assured through appropriate means, that
the flap 13 can not be opened when the thick materials pump and the
shift valve run during feed operations and that the shift valve can
not be shifted while the flap is open.
[0079] After opening the flap 13 also a cleaning body 37 (also
shown in FIG. 2 in dashed lines) can be inserted into the transfer
section 15L or 17L (which have been purged by hand in a suitable
manner before). After closing the flap 13 it can be moved in the
transfer section through switching the control slide, between the
openings of the respective feeding cylinder or the collector tube
19. Subsequently it is run through the collector tube and the feed
lines e.g. through compressed air, which is provided through an in
feed between the feeding cylinder and the control slide, which is
not shown here, in order to purge these lines from remaining thick
material.
[0080] Through a passage of a cleaning body through both branches
of the collector- or Y-tube 19, these two are also purged, whereby
the thoroughness of the cleaning of the feed line can be increased
through double passage of a cleaning body (subsequently through
both branches of the collector tube and then through the common
feed line). It is understood, that for both processes the same
cleaning body can be used twice, or different cleaning bodies can
be used.
[0081] Through a suitable shape of the collector tube in the joint
area and/or through simultaneous pressurization into both branches
of the collector tube 19 it can be assured that the cleaning body
does not get caught in the collector tube branch, which has been
cleared before, upon its second passage.
[0082] With reference to FIG. 5, a time-distance diagram of the
feeding pistons and the motion phases of the control slides 15 and
17 of the shift valve 9, after introducing all major parts of the
thick materials pump and its periphery, the feed process per se and
the controls of the thick materials pump and its shift valve are
explained and discussed in detail. The two pistons of the feeding
cylinders 3 and 5 are only represented as reference numerals K3
& K5 at the beginning of the respective diagram line. The
motion or motion cycle of the piston K3 is shown in a dashed line,
the one of the piston K5 in a solid line.
[0083] The above mentioned motion phases of the shift valve, whose
reduced schematic display corresponds to the view of FIG. 4 are
numbered from 1 through 8 and shown next to each other in a diagram
plotted over time, and separated from each other through vertical
lines.
[0084] In phase one both control slides 15 and 17 are in their
"transfer position", this means their transfer sections 15L and 17L
are located in front of the openings of the feeding cylinders 3 and
5 at the same time (in the following also starting position). Both
feeding cylinders 3 and 5 are also connected to the collector tube
19 and the subsequent feed line. None of the feeding cylinders
communicates with the pre filling container 7.
[0085] According to phase 1 of the diagram the piston K3 of the
feeding cylinder 3 moves towards the end of a pumping stroke, while
the piston K5 of the (freshly filled) cylinder 5 just starts with a
new pump stroke after a pre compression. Both pistons are moved in
parallel and in the same direction at a relatively slow speed. This
can be called "synchronous motion phase".
[0086] Phase 2 is a transition of the feeding cylinder 3 between
the pump stroke and the intake stroke. The control slide 15
was--preferably after stopping the piston K3--moved downward by
half of its total stroke, while the control slide 17 remained
stationary. The opening of the feeding cylinder 3 is tightly sealed
by the blocking section 15B, its piston K3 stops for a short time
before changing its stroke direction ("transition phase"). The
feeding cylinder 3 is completely closed relative to the collector
tube 19. This in between- or blocking position of the control slide
15 safely avoids any fluidic short cut between the one pumping and
the other intaking feeding cylinder.
[0087] During this relatively short phase the control slide 15 can
move; or it can be stopped temporarily, in case the blocking
section 15b, as discussed, is provided very short.
[0088] During this time the piston K5 continues to be within its
pumping stroke, as can also be seen in the diagram phase 2. But the
slope of its motion is steeper now, this means its forward velocity
is increased to a normal level (e. g. doubled), compared to the
previous synchronous phase 1. Thereby compared to phase 1 a
continuous flow of thick material in the feed line is assured.
[0089] Phase 3 shows the first extreme relative position of both
control slides. The control slide 15 was displaced downward by its
total stroke (e.g. by a total of a little more than 500 mm). It is
located in its inlet position now; its slide 15S lies in front of
the opening of the feeding cylinder 3, at the same time the control
slide 17 is still in its "transfer position", still allowing a feed
from the feeding cylinder 5 into the feed line.
[0090] The diagram shows in phase 3, that the piston K5 still runs
at full speed or with full pumping power, while the piston K3
performs an intake stroke, preferably with a soft start and finish,
but overall with a higher speed than in the pump stroke ("intake
phase"). Through the normal (weight -) pressure of the thick
material in the prefilling container and its hydro dynamically
advantageous guides on the slide 15S, the feeding cylinder 3 is
filled in an optimal manner.
[0091] Also in this phase a temporary stop of the oscillating
motion of the control slide 15 can be advantageous, so that the
total intake stroke can be performed with the feeding cylinder 3
completely open.
[0092] The position of the shift valve 9 in phase 4 of FIG. 5
corresponds to phase 2. The control slide 15 was lifted from its
intake position by the first half of its stroke. Now, as can be
seen from the diagram, the piston K3 (locked solid again by the
blocking section 15B of the control slide 15) of the feeding
cylinder 3, can pre compress the thick material through a very
short stroke, that has just been taken in with low density,
preferably to the current operating pressure in the feed line ("pre
compression phase"). This is also recommended with respect to gases
taken in with the thick material (air bubbles) and with respect to
the counter pressure from the collector tube 19 and the feed line,
in order to avoid shocks in the system, when the cylinder opening
in the following phase is connected again from the transfer section
15L to the feed stream. Also here the control slide can be stopped
temporarily or at least slowed down.
[0093] The piston K5 just runs into the end phase of its pump
stroke, still with full speed.
[0094] Phase 5 exactly corresponds to phase 1 with respect to the
position of the shift valve 9 (starting position "synchronous
phase"). Also the diagram shows in phase 5, that now the pistons K3
and K5, with exchanged roles (relative to phase 1) recommence their
phase shifted operation with simultaneous pump feeding at reduced
speed. Now begins the motion cycle of the control slide 17.
[0095] Phase 6 is a mirror image of phase 2; now only piston K3
pumps at full speed, while the blocking section 17B of the control
slide 17 tightly seals the feeding cylinder 5 and its piston K5
rests according to the diagram phase 6. The control slide 17 is
shifted downward by half of its total stroke.
[0096] Phase 7 is a mirror image of phase 3. As mentioned before,
also FIG. 4 shows this phase. The control slide 17 has reached its
lowest position. The feeding cylinder 5 is being refilled. Its
piston K5 returns according to diagram phase 7 into its starting
position and via the slide 17S thick material flows into the
feeding cylinder 5. At the same time the feeding cylinder 3
provides full pumping power, its piston K5 is at full forward
velocity.
[0097] In phase 8, which is a mirror image of phase 4, the piston
K5 pre compresses the newly filled in thick material, while the
piston K3 reaches the end phase of its pumping stroke. In the
diagram a full operation cycle of the two cylinder thick material
pump is now completed, the further operation continues again with
phase 1.
[0098] For emphasizing the velocities, pressures, and forces during
the operation of the thick materials pump at continuous feed, it
should be mentioned that the total course of the phases 1-8 occurs
within only 6 seconds, as it is shown through the labeled time axis
below the diagram. Thereby the pistons of the feeding cylinders
have to go through strokes of approximately one meter length, while
the total strokes of the control slides are in a range between 500
mm and 600 mm.
[0099] For further interpretation of the diagram of FIG. 5 it
should initially be repeated, that in the phases 1 and 5 both
pistons simultaneously pump thick material into the collector tube
19 and into the feed line. During these phases their velocities are
adjusted relative to each other, so that their total feed volume
corresponds to the feed volume of one single piston at normal
forward velocity. Thereby, together with the pre compression phase
of the newly starting piston, a practically shock free constant
feed volume of the thick materials pump is accomplished.
[0100] In all other phases only one of the pistons is in pumping
operation, and it then runs preferably at constant speed. The
static pressure in the respective non moving branch of the
collector tube 19 then corresponds to the pressure in the feed
line. It is safely received by the sealing surfaces 15D or 17D of
the control slide in its blocking and/or inlet position.
[0101] The design of the shift valve according to the invention and
a dedicated forward motion control of the feeding pistons makes it
possible to accomplish a constant output of the thick materials
pump in the phases of the common pump strokes, compared to the
single pumping power of a piston, and thereby practically
eliminating the pulsation of the thick materials flow in the feed
line. This is especially facilitated by the pre compression of the
thick material in the phases 4 and 8, thereby avoiding the opening
of a freshly filled feeding cylinder 3 or 5, or connecting a
pressure free ("buffer space") with the feed line. The volume of
the thick material in the "reactivated" transfer section 15L or 17L
is negligible with respect to such buffer effect.
[0102] Though, thru the pre compression steps (phases 4 and 8)
considerable forces are imparted to the control slides 15 and 17,
however they are easily received and transferred through their
robust and still relatively simple linear slide bearing within the
guidance structure 11. Hereby also the advantage of a substantially
translatoric slide bearing comes to bear, as well as the advantage
of a constant connection of the down stream end of the collector
tube 19 with the feed line.
[0103] In an advantageous manner the weight of the thick material
can support the quick feed via the slide of the control slide
towards the cylinder opening to be feed.
[0104] The momentary position of the pistons K3 and K5 and of the
control slides 15 and 17 can be sensed with suitable sensors
(distance sensors, position sensors, pressure sensors), possibly
directly at the respective drives. The sensors preferably provide
their position signals to a preferably central control unit of the
thick materials pump, which in turn controls the drives of the
feeding pistons K3 and K5 and of the shift valve 9.
[0105] In particular, in moments of simultaneous feed from both
feeding cylinders it controls the reduction of their forward
velocities. Not necessarily both pistons have to be controlled to
half speed, but in principle one piston can be controlled to 1/3 of
full velocity and the other one to 2/3 of full velocity (assuming
equal diameters and total strokes). The goal remains a feed stream,
as constant as possible, of thick material in the feed line.
[0106] Furthermore the control unit has to, during the time span,
when the freshly filled feeding cylinder is locked by the blocking
section of the associated control slide 15 or 17, on the one hand
stop the shift valve or adjust it to slower travel, on the other
hand control the pre compression stroke of the associated piston.
This possibly requires an additional pressure sensor that can be
located in the cylinder in the piston, or also in the pressurized
branch of the collector tube 19. A blocking of the control slides
15 and 17 through increased pressure during pre compression can
certainly be excluded through a pressure limiter.
[0107] Also in other phases, e.g. the synchronous phases, the
transition phase and the inlet- or suction phase, a reduced speed
of the control slides 15/17 or even their momentary stand still
between the reversal points can be advantageous. Overall one will
have to carefully weigh between stand still times and motion times
of the control slides, so that on the one hand the available flow
cross sections are not reduced too much through overlap of the
blocking sections with the openings of the feeding cylinders, on
the other hand no excessive slide velocities are required.
[0108] For the continuous operation of the thick materials pump it
can also be helpful to run through the various slide positions at
constant speed without slowing down or stopping.
[0109] FIG. 6 once more addresses the control the slide drive 21
with tandem lift cylinders shown in FIG. 4 on the left in more
detail. Again, one can see the fixed point 23 provided with a joint
(preferably at the housing of the shift valve 9) and the lifting
cylinders 25 and 27, both arranged in series on top of each other,
as well as the console 29 for the control slide, which is not shown
here. The lifting cylinders 25 and 27 are shown here in a schematic
cut view so that three motion phases of this drive concept become
apparent from the right to the left: on the very left both lifting
cylinders are loaded on their rod sides and are in their respective
lowest position. Accordingly the control slide is in its inlet
position. In the middle phase the lower lifting cylinder 25 is
loaded on the piston side and is in its upper position, while the
upper lifting cylinder which is moved along, is still loaded on the
rod side (blocking position of the control slide). The third phase
shows both lifting cylinders in piston loaded, fully extended
position (transfer position of the control slide). For lowering the
latter the phases are performed in reverse direction. With
reference to the respective, previously discussed positions of the
control bodies in the previous figures the three phases in FIG. 6-8
are designated with the letters E (inlet position), B (blocking
position) and L (transfer position).
[0110] FIG. 7 shows the same process with a two stage telescopic
cylinder 31, as shown in FIG. 3 on the right side. The fixed point
33 which is attached to the housing of the shift valve 9 with a
pivotable joint, carries the lifting cylinder, which is connected
to a control slide through a console 35, with its rod. Again 3
working positions of the lifting cylinder 31 are provided, wherein
for the middle position an additional stop or blocking mechanism is
provided, in order to make this position approachable in a defined
manner. A hydraulic locking of this middle position directly in the
lifting cylinder 31 could also be realized, but might not be
adjustable exactly enough in demanding continuous operations. In
practice a small lifting cylinder 39 is provided here, which is
mounted to the housing of the shift valve in a solid manner,
possibly via an additional fixed console and whose rod end piece
can be extended into the travel of the telescopic cylinder 31.
[0111] In FIG. 7 one can see again from the left to the right,
analogous to FIG. 6 three motion phases, or positions E, B and L.
On the very left the telescopic cylinder is loaded on the rod side
and is in its lowest position. The blocking cylinder 39 is
retracted. In the middle the telescopic cylinder is semi extended;
its rod end piece abuts to the meanwhile also extended rod end
piece of the blocking cylinder 39, so that here the intermediate
position (blocking position) is reached. In the right phase the
blocking cylinder 39 is retracted again, so that the way for the
rod of the telescopic cylinder 31 into the upper most, fully
extended (stop -) position is free. Accordingly also the control
slide (not shown) which is connected via the console, is now in its
uppermost (transfer-) position L.
[0112] FIG. 8 shows an equivalent to FIG. 7, this means a two stage
controllable long stroke lifting cylinder 41, associated with a
blocking cylinder 43. The fixed point 33 and the console 35 are
identical to FIGS. 6 and 7. Again, on the very left, the long
stroke lifting cylinder 41 is loaded on the rod side in its lowest
possible position E. The blocking cylinder 43 is retracted. During
the transition of the lifting cylinder 41 (now loaded on the piston
side) into its middle position (B) also the blocking cylinder 43 is
extended, so that its rod end piece enters into the path of the rod
end piece of the lifting cylinder 41, blocking it in the middle
position. On the very right in FIG. 8, the blocking cylinder 43 is
retracted again and the rod of the lifting cylinder 41 can be
extended in its uppermost position (L).
[0113] Also in the configurations according to FIGS. 7 and 8,
certainly for downward motion of the associated control slide, the
reverse sequence of the previously discussed motion phases or
positions is required, what is being controlled through rod side
loading of the lifting cylinders.
[0114] It is understood that the blocking cylinders 39 and 43 with
the respective lifting cylinders or rod end pieces have to be
adjusted in any case in a manner, so that also during the upward
travel of the lifting cylinders the middle position is exactly
adjustable. The schematically simplified arrangements shown in here
only serve for better understanding of the working principle of
these drives, but do reflect the real installation conditions and
the cooperation between the lifting and blocking cylinders only on
a limited basis.
* * * * *