U.S. patent application number 15/555797 was filed with the patent office on 2018-02-15 for dual-cylinder piston pump.
The applicant listed for this patent is SCHWING GMBH. Invention is credited to Thorsten Koch, Rudolf Rabsahl, Joseph Schnittker, Manfred Schwarz.
Application Number | 20180045186 15/555797 |
Document ID | / |
Family ID | 55628990 |
Filed Date | 2018-02-15 |
United States Patent
Application |
20180045186 |
Kind Code |
A1 |
Koch; Thorsten ; et
al. |
February 15, 2018 |
DUAL-CYLINDER PISTON PUMP
Abstract
The invention relates to a hydraulically actuated dual-cylinder
piston pump (1), with a first differential cylinder (22), with a
head-end chamber (51) and a rod-end chamber (53), which actuates a
first delivery piston (4) via a first piston rod (6), and also with
a second differential cylinder (23), with a head-end chamber (52)
and a rod-end chamber (54), which actuates a second delivery piston
(5) via a second piston rod (7), and with a switching device (14)
which by switching the hydraulic oil flow to the chambers (51, 52,
53, 54) of the differential cylinders (22, 23) establishes a
head-end or rod-end operating mode of the dual-cylinder piston pump
(1), wherein the switching device (14) is arranged on the bottoms
(48, 49) of the head-end chambers (51, 52) of the differential
cylinders (22, 23) as a bridge-forming connection between the
differential cylinders (22, 23). The invention is distinguished by
the fact that the switching device (14) comprises through-passages
(28, 29) for the hydraulic oil for actuating the differential
cylinders (22, 23), via which the head-end chambers (51, 52) of the
differential cylinders (22, 23) are connected to the switching
device (14) without hydraulic oil lines. The object of the
invention is also a method for operating a hydraulically actuated
dual-cylinder piston pump according to the invention.
Inventors: |
Koch; Thorsten; (Herne,
DE) ; Rabsahl; Rudolf; (Dortmund, DE) ;
Schnittker; Joseph; (Dortmund, DE) ; Schwarz;
Manfred; (Gelsenkirchen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCHWING GMBH |
Herne |
|
DE |
|
|
Family ID: |
55628990 |
Appl. No.: |
15/555797 |
Filed: |
March 7, 2016 |
PCT Filed: |
March 7, 2016 |
PCT NO: |
PCT/EP2016/054779 |
371 Date: |
September 5, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 1/02 20130101; F04B
15/02 20130101; F04B 7/02 20130101; F04B 23/06 20130101 |
International
Class: |
F04B 7/02 20060101
F04B007/02; F04B 1/02 20060101 F04B001/02; F04B 15/02 20060101
F04B015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 5, 2015 |
DE |
10 2015 103 180.9 |
Claims
1. Hydraulically actuated dual-cylinder piston pump comprising: a
first differential cylinder, with a head-end chamber and a rod-end
chamber, which actuates a first delivery piston via a first piston
rod, a second differential cylinder, with a head-end chamber and a
rod-end chamber, which actuates a second delivery piston via a
second piston rod, a switching device which by switching the
hydraulic oil flow to the chambers of the differential cylinders
establishes a head-end or rod-end operating mode of the
dual-cylinder piston pump, wherein the switching device is arranged
on the bottoms of the head-end chambers of the differential
cylinders as a bridge-forming connection between the differential
cylinders, characterized in that the switching block comprises
through-passages for the hydraulic oil for actuating the
differential cylinders, via which the head-end chambers of the
differential cylinders are connected to the switching device
without hydraulic oil lines.
2. Hydraulically actuated dual-cylinder piston pump according to
claim 1, characterized by flanges, arranged on the differential
cylinders, by means of which the differential cylinders are
fastened, preferably screwed, to the switching device.
3. Hydraulically actuated dual-cylinder piston pump according to
claim 1, characterized by-adapter flanges which are arranged
between the switching device and the bottoms of the differential
cylinders.
4. Hydraulically actuated dual-cylinder piston pump according to
claim 3, characterized in that the adapter flanges are inserted
into close-fitting seats which are introduced into the bottoms of
the differential cylinders.
5. Hydraulically actuated dual-cylinder piston pump according to
claim 2, characterized in that the expansion sleeves are arranged
on the flanges for accommodating screws.
6. Hydraulically actuated dual-cylinder piston pump according to
claim 1, characterized in that-the switching device comprises an
inlet for a control line for the switching over of the operating
mode.
7. Hydraulically actuated dual-cylinder piston pump according to
claim 6, characterized by a pilot valve for switching over the
operating mode of the switching device, which can be controlled by
the control line.
8. Hydraulically actuated dual-cylinder piston pump according to
claim 7, characterized by a latching device which holds the pilot
valve in its switched position when the control line is shut
down.
9. Switching device for establishing the operating mode of the
hydraulically actuated dual-cylinder piston pump according to claim
1.
10. Method for operating the hydraulically actuated dual-cylinder
piston pump according to claim 1, characterized in that before
startup of the dual-cylinder piston pump the last established
operating mode is determined a check is carried out as to whether
the last established operating mode is to be used for startup of
the pump, and in that in dependence of this the operating mode is
maintained or switched over before the pump is started.
11. Method according to claim 10, characterized in that the last
established operating mode is specified as the operating mode
during startup of the pump.
12. Method for operating a hydraulically actuated dual-cylinder
piston pump according to claim 1, characterized in that during the
operation of the dual-cylinder piston pump the pump pressure is
detected; it is determined whether the detected pump pressure lies
within a specified tolerance for the established operating mode,
and a check is carried out as to whether the operating mode is to
be maintained, and in that in dependence of the result of the check
the operating mode is maintained or switched over.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to International Patent
Application No. PCT/EP2016/054779, filed Mar. 7, 2016, which claims
the benefit of DE Application No. 10 2015 103 180.9, filed Mar. 5,
2015, both of which are herein incorporated by reference in their
entireties.
TECHNICAL FIELD
[0002] The invention relates to a dual-cylinder piston pump, for
example for pumping thick substances, such as sludge or concrete,
as are used for example in automatic concrete pumps, stationary
concrete pumps or trailer concrete pumps.
BACKGROUND
[0003] A dual-cylinder piston pump, which is operated by hydraulic
actuating cylinders which as a rule are designed as differential
cylinders, can be operated in a head-end or in a rod-end operating
mode. Whereas in the case of the head-end operation the complete
surfaces of the hydraulic pistons in the hydraulic cylinder are
acted upon by hydraulic oil in each case, in the case of the
rod-end operation only a partial surface of the pistons is acted
upon because in the case of the rod-end actuation the surface on
which the piston rod is attached to the hydraulic piston is not
effective for the hydraulic pressure. This leads to the pump being
operated with greater delivery volume but low delivery pressure in
the case of the rod-end operation and being operated with higher
delivery pressure but smaller delivery volume in the case of the
head-end operation.
[0004] A changeover of the operating mode is advisable for example
in the case of stationary concrete pumps during construction of a
building in which at the beginning of the concrete delivery
concrete is delivered with a higher delivery quantity but low
delivery pressure in stories located at low level. With increasing
construction progress, after reaching a specified building height,
a higher delivery pressure is necessary in certain circumstances in
order to pump the concrete through the delivery line to a
corresponding building height, for which, however, a lower concrete
output is accepted.
[0005] As a rule, the hydraulic actuation of dual-cylinder piston
pumps according to the prior art, as shown in FIG. 1, in which the
head-end actuation is displayed, is constructed so that the
hydraulic oil for actuating the differential cylinder 22, 23 of the
dual-cylinder piston pump 1 is directed via a control circuit (not
shown) to the actuating piston 8 of a differential cylinder 22. Via
a bridging oil line 13, which interconnects the two rod-end
chambers 53, 54 of the differential cylinders 22, 23, in the case
of the head-end actuation of the dual-cylinder piston pump for
example shown in FIG. 1, the hydraulic oil is forced from the
rod-end chamber 53 of the first differential cylinder 22 into the
rod-end chamber 53 of the second differential cylinder 23 and
therefore the second hydraulic cylinder 23 is actuated. As soon as
the first delivery piston 4 reaches its end point, the hydraulic
oil is directed into the chamber 54 instead of into the chamber 53,
as a result of which the piston 9 of the second differential
cylinder 23 is first of all actuated and the hydraulic oil is
directed via the bridging oil line 13 from the rod-end chamber 54
of the second hydraulic cylinder 23 into the rod-end chamber 53 of
the first hydraulic cylinder 22.
[0006] It is basically possible, by modifying the hydraulic lines,
to undertake the changeover of head-end to rod-end operation of a
dual-cylinder piston pump, but this is very costly and in practice
is hardly possible at a building site since for example draining
and replenishing of the hydraulic oil is required in order to alter
the hydraulic hose arrangement.
[0007] A hydraulic circuit, which enables the switching between a
rod-end and head-side operating mode without modifying the
hydraulic lines, is known from document DE 292 56 74. Such a
circuit, shown in principle in FIG. 2, includes a switching block
14 which is connected via hydraulic lines 15, 16, 17, 18 to the
chambers of the differential cylinders 22, 23. The arrows in FIG. 2
show the hydraulic oil flow in the head-end operating mode of the
dual-cylinder piston pump 1. Via a suitable switching device in the
switching block 14, the hydraulic oil flow is switched over so that
the dual-cylinder piston pump 1 is operated in rod-end mode.
[0008] In the case of such a switching device according to the
prior art, a disadvantage is that leak tightness problems
frequently occur on account of the numerous connecting points for
the hydraulic lines and high pressure losses occur on account of
the numerous system components, which makes economical use of such
hydraulic circuits difficult. Moreover, numerous hydraulic lines
are required, which create a high installation and financial outlay
and the complexity of the hose arrangement increases the risk of
leaks.
[0009] In order to position the switching device 14 as close as
possible to the hydraulic cylinders, this is attached to the
hydraulic cylinders in the middle, for example, as shown in FIG. 2.
Since, however, the hydraulic cylinders can move relative to each
other as a result of the high and varying hydraulic pressures in
the chambers, there is the danger that cracks or other damage occur
in the connecting point between the hydraulic cylinders and the
switching device.
SUMMARY
[0010] The switching of the operating mode of a dual-cylinder
piston pump, which could also be carried out automatically, is,
however, safety-critical and should only be carried out if the
operator is clear about the altered operating conditions regarding
the altered delivery pressure and the pumped delivery volume during
the switching of the operating mode.
[0011] It is therefore the object of the present invention to
provide a simple device for switching between head-end and rod-end
operating mode of a dual-cylinder piston pump, and also to provide
a method for the switching of the operating mode, which resolve the
aforesaid disadvantages of the prior art.
[0012] These objects are achieved by means of a dual-cylinder
piston pump, a switching device, and methods according to the
claims. Reference is to be made to the fact that the features which
are individually quoted in the claims can also be combined with
each other in an optional and technologically sensible manner and
therefore demonstrate further embodiments of the invention.
[0013] A hydraulically actuated dual-cylinder piston pump according
to the invention comprises a first hydraulically operated
differential cylinder, with a head-end chamber and a rod-end
chamber, which actuates a first delivery piston via a first piston
rod, a second differential cylinder, with a head-end chamber and a
rod-end chamber, which actuates a second delivery piston via a
second piston rod, and a switching device, which by switching the
hydraulic oil flow to the chambers establishes a head-end or
rod-end operating mode of the dual-cylinder piston pump, wherein
the switching device is arranged on the bottoms of the head-end
chambers of the differential cylinders as a bridge-forming
connection between the differential cylinders. The invention is
distinguished by the fact that the switching device comprises
through-passages for the hydraulic oil for actuating the
differential cylinders, via which the head-end chambers of the
differential cylinders are connected to the switching device
without hydraulic oil lines.
[0014] Compared with the prior art, the dual-cylinder piston pump
according to the invention has the advantage that on the one hand a
particularly force-locked connection of the components to each
other is created so that damage (e.g., crack developments,
fractures) at or in the region of the connecting points between the
differential cylinders and the switching device is not to be taken
into account. On the other hand, the dual-cylinder piston pump
according to the invention, compared with the prior art, has the
advantage that the risk of rupturing of hydraulic hoses is greatly
reduced since hydraulic hoses are required only between the rod-end
chambers of the differential cylinders and the switching block.
Moreover, the cost for the installation and screw-connecting of the
hydraulic hoses is greatly reduced.
[0015] In a preferred embodiment of the invention, the switching
device is fastened on the bottoms of the differential cylinders
with the aid of adapter flanges. The particular advantage of this
embodiment of the invention exists in the fact that a modification
of the switching device is dispensed with if the switching device
is to be attached to differential cylinders with different
diameters because via the adapter flanges with different diameters,
which are adapted in each case to the inside diameter of the
head-end chamber of the differential cylinder, the switching device
of the same type of construction can be adapted to differential
cylinders with different diameters. The adapter flanges can be
arranged in corresponding recesses in the switching block. The
recesses in the switching block increase the stability of the
arrangement and at the same time unload the fastening/screwing of
the adapter flanges.
[0016] The hydraulically actuated dual-cylinder piston pump can
furthermore comprise flanges arranged on the differential
cylinders, by means of which the differential cylinders are
fastened, preferably screwed, to the switching device. Such flanges
enable a simple fastening/screwing of the differential cylinders to
the switching device. The flanges are for example attached to the
tubular differential cylinders by means of a welded or screwed
connection or already form a unit with the cylinder tubes during
production.
[0017] In a further preferred embodiment, the bottoms of the
head-end chambers of the differential cylinders comprise
close-fitting seats into which the adapter flanges are fitted. As a
result of this measure, the adapter flanges absorb in an optimally
form-locking manner the radial forces which originate from the
differential cylinders and therefore avoid the transverse force
loading of the flange screws between the differential cylinders and
the control block. Moreover, the adapter flanges increase the
mechanical loadability/durability of the connection between the
differential cylinders and the switching device.
[0018] In a further preferred embodiment of the invention,
expansion sleeves are arranged on the flanges for accommodating
screws. As a result of this, a secure screw fastening can be
ensured between the flanges and the switching device. As a result
of the expansion sleeves, longer screws can be used and the
expansion sleeve absorbs some of the expansion, e.g., as a result
of thermal loads and pressure loads, in the material and therefore
acts like a buffer, as a result of which the leak tightness of the
cylinder chambers under high pressure is always ensured and high
safety standards are met.
[0019] A further preferred embodiment of the invention is
distinguished by the fact that the switching device comprises an
inlet for a control line for the switching of the operating mode of
the dual-cylinder piston pump. This control line can be for example
hydraulically or electrically designed.
[0020] In a further preferred embodiment, the operating mode of the
dual-cylinder piston pump is switched over via a pilot valve which
is actuated via the control line. By means of a latching device,
this pilot valve is preferably also held in its last switched
position in the event of the control line being shut off or in the
event of a signal to the control line not being present, for
example with the pump switched off. As a result of this, the effect
of the pump being inadvertently started in an operating mode with
differs from the last used operating mode, e.g., during restarting,
is prevented.
[0021] The invention is furthermore distinguished by a method which
controls the changeover of the operating mode of the dual-cylinder
piston pump during startup of the pump. A further method relates to
the changeover of the operating mode while the pumping process is
running.
[0022] The invention and also the technical field are explained in
more detail below with reference to the figures. Reference is to be
made to the fact that the figures show a particularly preferred
embodiment variant of the invention. The invention, however, is not
limited to the depicted embodiment variant. In particular, the
invention, providing it is technically sensible, covers any
combinations of the technical features which are quoted in the
claims or are described in the description as being relevant to the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the drawing:
[0024] FIG. 1 shows a dual-cylinder piston pump according to the
prior art without a switching device for the operating mode,
[0025] FIG. 2 shows a dual-cylinder piston pump with a switching
device for the operating mode according to the prior art,
[0026] FIG. 3 shows a dual-cylinder piston pump according to the
invention in a head-end operating mode,
[0027] FIG. 4 shows a dual-cylinder piston pump according to the
invention in a rod-end operating mode,
[0028] FIG. 5 shows a perspective view of a switching device
according to the invention,
[0029] FIG. 6 shows a perspective view of a switching device with
connected differential cylinders according to the invention,
[0030] FIG. 7 shows a sectional view of the connection between the
switching block and a differential cylinder according to the
invention,
[0031] FIG. 8 shows a hydraulic circuit according to the
invention,
[0032] FIG. 9 shows a flow diagram for a method according to the
invention, and
[0033] FIG. 10 shows a flow diagram for a further method according
to the invention.
DETAILED DESCRIPTION
[0034] Shown in FIG. 1 and FIG. 2 are dual-cylinder piston pumps 1
according to the prior art, as have already been explained further
above. The dual-cylinder piston pump 1 according to FIG. 1
comprises two delivery cylinders 2, 3 with delivery pistons 4, 5
which in each case are actuated via piston rods 6, 7 of
differential cylinders 22, 23 with hydraulic pistons 8, 9. Arranged
between the delivery cylinders 2, 3 and the differential cylinders
22, 23 is a water tank 10 in which there is water which flushes the
delivery pistons 8, 9 on their rear side in order to cool and to
lubricate the pistons. Connected to the head-end chambers 51, 52 of
the differential cylinders 22, 23 are hydraulic feed/drain hoses
11, 12 via which the hydraulic oil for actuating the differential
cylinders 22, 23 is fed from a hydraulic pump, which is not shown.
The rod-end chambers 53, 54 are interconnected via a bridging oil
line 13. A cylinder bottom 49, 50 is located in each case at the
end of the head-end chambers 51, 52. The arrows in FIG. 1 show the
flow direction of the hydraulic oil for the head-end actuation of
the dual-cylinder piston pump 1.
[0035] FIG. 2 shows a dual-cylinder piston pump 1 corresponding to
FIG. 1, which is equipped with a switching device 14 for switching
between rod-end and head-side operating mode. The switching device
14 as a rule consists of a solid metal block in which are
introduced control valves and through-passages for the hydraulic
valves which are arranged in the switching device 14 and is
therefore also referred to as a control block or switching block.
The references switching block and switching device 14 are used
synonymously in the following text. The switching block 14 includes
a hydraulic circuit which is suitable for controlling the hydraulic
oil flow to the cylinder chambers 51, 52, 53, 54 so that a
corresponding operating mode can be established. The hydraulic oil
feed/drain lines 11, 12 are connected to the switching block 14.
The arrows show in FIG. 2 the flow direction of the hydraulic oil
and the movement direction of the delivery pistons for a head-end
operation of the dual-cylinder piston pump 1.
[0036] FIG. 3 shows an embodiment according to the invention of a
dual-cylinder piston pump 1 which comprises a first differential
cylinder 22 with a head-end chamber 51 and a rod-end chamber 53,
wherein the differential cylinder 22 actuates a first delivery
piston 4 via a first piston rod 6. The dual-cylinder piston pump 1
also comprises a second differential cylinder 23 with a head-end
chamber 52 and a rod-end chamber 54, which actuates a second
delivery piston 5 via a second piston rod 7. The dual-cylinder
piston pump 1 also comprises a switching device 14 which by
switching the hydraulic oil flow to the chambers 51, 52, 53, 54 of
the differential cylinders 22, 23 establishes a head-end or rod-end
operation of the dual-cylinder piston pump 1.
[0037] The switching device 14 is arranged on the bottoms 48, 49 of
the head-end chambers 51, 52 of the differential cylinders 22, 23
as a bridge-forming between the differential cylinders 22, 23.
[0038] The switching block 14 comprises two through-passages 28, 29
(see also FIG. 6) via which the head-end chambers 51, 52 of the
differential cylinders 22, 23 are connected directly to the
switching device 14. Via the through-passages 28, 29, the hydraulic
oil is directed directly from the switching device 14 to the
head-end chambers 51, 52 of the differential cylinders 22, 23, as a
result of which a failure-prone hydraulic hose arrangement
according to the prior art between the switching block 14 and the
head-end chambers 51, 52 can be avoided.
[0039] Arranged between the switching device 14 and the bottoms 49,
50 of the differential cylinders 22, 23 are adapter flanges 20, 21
which enable an individual adaptation of the switching block 14 to
the differential cylinders 22, 23 with different diameters.
[0040] The hydraulic oil flow represented by arrows in FIG. 3 shows
the head-end operating mode of the dual-cylinder piston pump 1.
That is to say, the hydraulic oil, which is conducted from a
hydraulic pump, not shown, at high pressure via the hydraulic oil
line 11 into the switching block 14, is directed from the switching
block 14 into the head-end chamber 51 of the differential cylinder
22. In the chamber 51, the greater volume in conjunction with the
larger piston surface than in the case of the rod-end actuation
(see FIG. 4) creates the effect of the delivery piston 4 being
pushed to the left in the first delivery cylinder 2 with high force
but comparatively slowly. The hydraulic oil in the rod-end chamber
53 is transported in the course of the movement via the hydraulic
line 16, the switching block 14 and the hydraulic line 18 into the
rod-end chamber 54 of the differential cylinder 23 and creates the
effect of the hydraulic piston 9 being pushed to the right. In the
process, the hydraulic oil is drained from the head-end chamber 52
of the differential cylinder 23 via the switching block 14 and the
hydraulic line 12. The delivery cylinder 2 in FIG. 3 is in pump
mode, whereas the delivery cylinder 3 is in suction mode.
[0041] As soon as the delivery pistons 4, 5 or the hydraulic
pistons 8, 9 have reached their end position, which for example is
detected by means of suitable limit switches or detectors, the
hydraulic oil flow is switched over and the hydraulic oil flows
from the hydraulic pump through the line 12 into the switching
block 14 and first all actuates the hydraulic piston 9 via the
head-end chamber. This mode, which is not shown, now creates the
effect of the delivery cylinder 3 working in pumping mode, whereas
the delivery cylinder 2 works in suction mode.
[0042] Shown in FIG. 4 is the dual-cylinder piston pump 1 from FIG.
3, in which the switching block 14 is changed over via the control
line 19 from the head-end operating mode into the rod-end operating
mode of the dual-cylinder piston pump 1. That is to say, the
hydraulic oil coming from the hydraulic feed line 11 in FIG. 4 is
first of all conducted via the switching block 14 into the rod-end
chamber 53 of the differential cylinder 22, as a result of which
the delivery cylinder 2 with the delivery piston 4 is in suction
mode at comparatively high speed but with lower force. In the
process, the hydraulic oil from the head-end chamber 51 of the
differential cylinder 22 is conducted via the switching block 14
into the head-end chamber 52 of the differential cylinder 23 and
actuates the hydraulic piston 9 or the delivery piston 5 in pumping
mode. After switching of the hydraulic oil flow, the pumping
direction of the delivery pistons of the dual-cylinder piston pump
1 is reversed, wherein the rod-end actuation is maintained
providing the switching block 14 is not switched over via the
control line 19 into the head-end operating mode.
[0043] FIG. 5 shows a perspective view of the switching block 14
according to the invention with installed adapter flanges 20, 21
with the through-passages 28, 29. The adapter flanges 20, 21 are
fitted in corresponding recesses in the switching block 14 and are
preferably screwed to the switching block by means of six screws in
each case. The adapter flanges 20, 21 could also be screwed onto
the switching block 14 without the recesses in the switching block
14. The recesses in the switching block 14 increase the stability
of the arrangement and at the same time unload the screw fastening
of the adapter flanges 20, 21. Shown on the sides of the switching
block 14 are inlet/outlet passages 57 for the hydraulic lines.
Arranged on the switching block 14 at the top is the housing of a
pilot valve 33 (see also FIG. 8) which by the control line 19 is
electronically acted upon by the control signal for the
establishing of the operating mode.
[0044] FIG. 6 shows the switching block 14 together with the
differential cylinders 22, 23 which via flanges 24, which are
preferably connected to the differential cylinders 22, 23 by means
of welded connections 26, are fastened to, preferably screwed to,
the switching block 14. The screw fastening of the flanges 24 to
the switching block 14 is not shown in this drawing, only the
drilled holes 25 for the screw fastening are visible. The flanges
24 can for example also be screwed to the cylinder tubes or
produced in one piece.
[0045] FIG. 7 shows in a perspective cross section the connection
of the differential cylinder 22 via the adaptor flange 20 to the
switching block 14. On the bottom 49 of the differential cylinder
22 provision is made for a close-fitting seat 55 so that the
adapter flange 20 is fitted into the differential cylinder 22 in a
form-fitting manner. For leakage-free sealing between the adapter
flange 20, the switching block 14 and the differential cylinder 22,
two sealing rings 30 are inserted in grooves in the adapter flange
20.
[0046] The adapter flange 20, on the side facing the switching
block 14, has an outside diameter dl which fits into a prepared
cutout in the switching block 14. On the side facing the
differential cylinder 22, the adapter flange 20 has the diameter d2
which is adapted to the inside diameter of the close-fitting seat
55 of the differential cylinder 22. The switching block 14 is
preferably also provided with fits/close-fitting seats with the
diameter dl for accommodating the adapter flanges 20, 21 in the
recesses provided for it. Arranged in the adapter flange 20, in the
middle, is a hole through which the hydraulic oil flows from the
passage 28 of the switching block 14 into the head-end chamber 51
of the differential cylinder 22. By using adapter flanges 20, 21
with different diameters d2, but identical diameters d1, the
switching block 14 together with the differential cylinders 22, 23
can be operated with different diameters. In the case of concrete
pumps, diameters of the differential cylinders of 20-25 cm, for
example, are customary, wherein the middle point of the
differential cylinders in relation to each other is often the same
so that a switching block 14 of the same type of construction can
be connected to different differential cylinders 22, 23.
[0047] The differential cylinder 22 is screwed via the welded-on
flange 24 to the switching block 14 by screws 27. The screwed
connections have expansion sleeves 36 which increase the security
of the screw fastening even under high pressure and extreme thermal
loads because the hydraulic pressure in concrete pumps can be up to
over 400 bar.
[0048] Shown in FIG. 8 is a possible hydraulic circuit, arranged in
the switching block 14, which is suitable for undertaking the
switching of the operating mode of the dual-cylinder piston pump 1.
The hydraulic circuit mainly comprises six cartridge valves 41-46
which are controlled by an electromagnetically controlled pilot
valve 33. Via the control oil inlet 35, which is protected by a
check valve 34, hydraulic oil is conducted to the pilot valve 33
for controlling the cartridge valves 41-46. Via the hydraulic oil
inlet/outlets 47 and 48, the hydraulic oil which is required for
operating the differential cylinders 22, 23 is fed to/drained from
the switching block 14.
[0049] The cartridge valves 41-45 control the hydraulic oil flow to
the head-end/rod-end chambers of the differential cylinders in the
respectively established operating mode. The cartridge valve 46 is
of slightly larger dimensions than the other cartridge valves
41-45. The valve 46 opens or closes the connection between the two
head-end chambers 51, 52 of the differential cylinders 22, 23 via
the through-passages 28, 29 which are shown schematically in FIG.
8.
[0050] The pilot valve 33 is set in FIG. 8 so that the cartridge
valves 41, 45 and 44 are closed via the control line 32 as a result
of the control oil pressure and the cartridge valves 42, 43 and 46
are opened by spring force action. As a result of this valve
setting, the rod-end operating mode of the dual-cylinder piston
pump 1 is established.
[0051] Via the electric control line 19, the pilot valve 33, by
means of two solenoids which are located at the side on the valve
body, is reversed in a known manner. A mechanical latching device
56 ensures that the pilot valve 33 remains in the last established
position even with the control line 19 shut down (e.g. after a
shutdown of the entire machine).
[0052] In the rod-end operating mode, as explained further above,
the pistons 8, 9 move more quickly than in the head-end operating
mode, which is why the hydraulic oil quantity to be passed through
the cartridge valve 46 between the head-end chambers is
particularly large, which requires a larger dimensioning of this
valve.
[0053] The hydraulic lines 16, 18 and also the hydraulic
connections 47, 48 are shown as being doubled here because the
quantity of hydraulic oil to be passed through is of such magnitude
that a simple hose arrangement with thicker hydraulic lines would
not be feasible so that a parallel hose arrangement with thinner
hydraulic lines is provided.
[0054] FIGS. 9 and 10 show flow diagrams for methods for
controlling a dual-cylinder piston pump 1, which relate to the
switching process between the rod-end and the head-end operating
mode.
[0055] In FIG. 9, startup of the pump 1 is requested by an operator
in step 100. Before the pump starts, the operating mode established
during the last operation of the pump 1, e.g., with reference to a
memory input, is first of all determined in step 101. In step 102,
the operator, for example via a display on the control unit of the
machine or on a remote control unit, asks whether the pump is to be
used again in the last established operating mode, which is also
displayed, during startup. If the operating mode is to be
maintained, via step 103 the pump is started in this operating mode
in step 105. If the operating mode is to be altered, because the
pump conditions have been altered (e.g., concrete delivery location
at a higher or lower level during the restart), in step 104, by
switching of the pilot valve 33, the operating mode is switched
over and only then is the pump started in step 105.
[0056] The sequence could also be configured so that in step 102
the operator of the pump can acknowledge the maintaining of the
operating mode in a relatively simple manner, whereas the switching
of the operating mode requires a specific acknowledgement which
expressly refers the operator to the altered pump behavior. It is
also conceivable that the operating mode in step 102 is maintained
after a certain waiting period (for example 5 or 10 seconds) and
the pump is automatically started in step 105 if the operator makes
no input within the waiting period.
[0057] FIG. 10 shows a method for switching the operating mode of
the pump 1 during continuous operation, in which the pressure of
the pumped medium or the hydraulic pressure of the hydraulic oil is
measured at a suitable point, e.g., in one or both delivery
cylinders 2, 3 in one or both differential cylinders 22, 23 or in
the switching block 14, in order to switch the pump over into a
suitable operating mode.
[0058] In step 110, the pump 1 is in normal pumping operation. At
regular intervals, or even continuously, the pump pressure is
checked in step 111, and in step 113, based on the established
operating mode 112, a check is made as to whether the pump pressure
lies within a tolerance range for the operating mode. In the case
of the rod-end actuation, which is better suited to speedier
pumping at lower pressure, the pump pressure should not exceed for
example a certain tolerance limit because beyond this limit the
head-end operation is more suitable in certain circumstances so as
not to overload the hydraulic system. Since, however, various
reasons can exist for the higher pump pressure, e.g., even a
blockage of the pipeline, the operator first of all asks in step
114 whether the operating mode is to be maintained. If this is the
case, the pump operation continues normally in step 110. If the
change of the operating mode is requested by the operator in step
115, the pilot valve 33 is switched over and the pump operation is
continued in step 117 with the altered operating mode.
[0059] An automatic switching over from the head-end operating mode
to the rod-end operating mode (and vice versa) would also be
conceivable if the pump pressure falls short of a certain tolerance
limit in order to increase the pump output. Since, however, the
spontaneous change of the operating mode at the building site can
also bring problems along with it, a manual switching over with
interrogation is to be preferred. Conversely, for example an
automatic changeover to the head-end operating mode could also be
undesirable because the piping system connected to the pump is not
designed for high pump pressure and pipes or hoses could burst.
LIST OF DESIGNATIONS
[0060] 1 Dual-cylinder piston pump
[0061] 2 First delivery cylinder
[0062] 3 Second delivery cylinder
[0063] 4 First delivery piston
[0064] 5 Second delivery piston
[0065] 6 First piston rod
[0066] 7 Second piston rod
[0067] 8 First hydraulic piston
[0068] 9 Second hydraulic piston
[0069] 10 Water tank
[0070] 11 Hydraulic feed line
[0071] 12 Hydraulic drain line
[0072] 13 Bridging oil line
[0073] 14 Switching device/switching block
[0074] 15 First hydraulic line
[0075] 16 Second hydraulic line
[0076] 17 Third hydralic line
[0077] 18 Fourth hydraulic line
[0078] 19 Control line
[0079] 20 First adapter flange
[0080] 21 Second adapter flange
[0081] 22 First differential cylinder
[0082] 23 Second differential cylinder
[0083] 24 Flange
[0084] 25 Holes
[0085] 26 Welded seam
[0086] 27 Screws
[0087] 28 Through-passage
[0088] 29 Through-passage
[0089] 30 Seals
[0090] 31 First hydraulic control line
[0091] 32 Second hydraulic control line
[0092] 33 Pilot valve
[0093] 34 Check valve
[0094] 35 Connection for hydraulic control oil
[0095] 36 Expansion sleeves
[0096] 41-45 Cartridge valves for switching
[0097] 46 Cartridge valve for connection of piston chambers
[0098] 47 Hydraulic oil feed/drain
[0099] 48 Hydraulic oil feed/drain
[0100] 49 Bottom of differential cylinder 22
[0101] 50 Bottom of differential cylinder 23
[0102] 51 Head-end chamber of differential cylinder 22
[0103] 52 Head-end chamber of differential cylinder 23
[0104] 53 Rod-end chamber of differential cylinder 22
[0105] 54 Rod-end chamber of differential cylinder 23
[0106] 55 Close-fitting seat
[0107] 56 Latching device for pilot valve
[0108] 57 Inlet/outlet passages for the hydraulic lines
* * * * *