U.S. patent application number 10/637767 was filed with the patent office on 2004-04-15 for piston press.
Invention is credited to Bringewatt, Wilhelm, Heinz, Engelbert.
Application Number | 20040069021 10/637767 |
Document ID | / |
Family ID | 31197197 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040069021 |
Kind Code |
A1 |
Bringewatt, Wilhelm ; et
al. |
April 15, 2004 |
Piston press
Abstract
A piston press in which hydraulic lines (32) of a hydraulic
cylinder (19) move a ram plate (21) up and down with relatively
large diameters, and in which use is made of a hydraulic pump (33)
with a continuously adjustable delivery flow, in particular with
constant output regulation, making it possible to move the ram
plate (21) more quickly in the unloaded or less loaded state, by
which means the operating time is shortened considerably as
compared with known piston presses (10).
Inventors: |
Bringewatt, Wilhelm; (Porta
Westfalica, DE) ; Heinz, Engelbert; (Vlotho,
DE) |
Correspondence
Address: |
TECHNOPROP COLTON, L.L.C.
P O BOX 567685
ATLANTA
GA
311567685
|
Family ID: |
31197197 |
Appl. No.: |
10/637767 |
Filed: |
August 9, 2003 |
Current U.S.
Class: |
68/21 ; 100/116;
100/211; 68/210; 68/241; 68/242; 68/96 |
Current CPC
Class: |
B30B 9/06 20130101; D06F
47/04 20130101; B30B 5/02 20130101 |
Class at
Publication: |
068/021 ;
068/096; 068/210; 068/241; 068/242; 100/116; 100/211 |
International
Class: |
D06F 047/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 16, 2002 |
DE |
102 38 359.6 |
Claims
What is claimed is:
1. Piston press for pressing liquids out of laundry (11) comprising
a press ram (18) which has a hydraulic cylinder (19) and a ram
plate (21) arranged at the free end of a piston rod (20) of the
hydraulic cylinder (19), and a hydraulic pump (33) for supplying at
least the hydraulic cylinder (19) of the press ram (18) with
hydraulic fluid, characterized in that the hydraulic pump (33) is
designed in such a way that its delivery flow can be adjusted
continuously.
2. Piston press according to claim 1, characterized in that the
delivery flow of the hydraulic pump (33) can be adjusted as a
function of the loading on the hydraulic cylinder (19) or the ram
plate (21).
3. Piston press according to claim 1, characterized in that the
delivery flow of the hydraulic pump (33) is regulated as a function
of the output.
4. Piston press according to claim 3, characterized in that the
delivery flow of the hydraulic pump can be regulated in such a way
that the output of the hydraulic pump (33) is always approximately
constant.
5. Piston press for pressing liquids out of laundry (11) comprising
a press ram (18) which has a hydraulic cylinder (19) with a ram
plate (21) assigned to the latter, and a hydraulic pump (33) for
supplying at least the hydraulic cylinder (19) of the press ram
(18) with hydraulic fluid, characterized in the hydraulic lines
(32) between the hydraulic cylinder (19) and the hydraulic pump
(33) and a tank for hydraulic fluid have a relatively large cross
section.
6. Piston press according to claim 5, characterized in that the
diameter of the hydraulic lines (32), including the hydraulic
connections, is greater, as compared with the piston diameter of
the hydraulic cylinder (19), then the usual standardized diameter
of the hydraulic lines (32) and their connections.
7. Piston press according to claim 5, characterized in that the
free flow cross section at least of the hydraulic lines (32) is at
least {fraction (1/15)} of the piston diameter of the hydraulic
cylinder (19).
8. Piston press according to claim 5, characterized in that the
diameter of the hydraulic line (32) on the piston side (31) is at
least 1/5 of the piston diameter of the hydraulic cylinder
(19).
9. Piston press according to claim 5, characterized in that the
free flow cross section of the hydraulic lines (32) and of the
connections on the piston side (31) of the hydraulic cylinder (19)
is greater than on the piston-rod side (34) of the hydraulic
cylinder (19).
10. Piston press according to claim 5, characterized in that the
temperature of the hydraulic fluid can be regulated in such a way
that the temperature of the hydraulic fluid approximately maintains
a predefined value.
11. Piston press for pressing liquids out of laundry (11)
comprising a press frame (17) which has a base (12) and a press ram
(18) which can be moved up and down, and a press basket (23) for
holding the laundry (11), characterized in that the base (12) has
at least one storage container for the liquid pressed out of the
laundry (11).
12. Piston press according to claim 11, characterized in that the
volume of the at least one storage container (36) is dimensioned to
be larger than the maximum amount of liquid which accumulates as
the laundry (11) is pressed in the press basket (23).
13. Piston press according to claim 12, characterized in that the
at least one storage container has a volume which is at least
suitable to accommodate twice the quantity of liquid which
accumulates as the laundry (11) is pressed in the press basket
(23).
14. Piston press according to claim 11, characterized in that each
storage container (36) is formed by constructing the base (12) as a
frame tank (35).
15. Piston press according to claim 14, characterized in that an
upper side of the base (12) is formed by a top wall (13) of the
frame tank (35) which, at least in the region of the press basket
(23), has drainage holes (14).
16. Piston press according to claim 15, characterized in that at
least part of the storage container (36) is arranged in the region
under the drainage holes (14).
17. Piston press for pressing liquids out of laundry (11)
comprising a press frame (17) which has a base (12) and a press ram
(18) which can be moved up and down, and a press basket (23) for
holding the laundry (11), characterized in that at least one
analogue distance measuring device is assigned to the press frame
(17) to determine the position of at least the press ram (18).
18. Piston press according to claim 17, characterized in that a
further analogue distance measuring device is provided, by means of
which the position of the press basket (23) can be determined.
19. Piston press according to claim 17, characterized in that the
respective distance measuring device is assigned to a press yoke
(16) of the press frame (17).
20. Piston press according to claim 17, characterized in that the
respective distance measuring device is designed as an acoustic
distance sensor.
21. Piston press according to claim 20, characterized in that the
ram plate (21) of the press ram (18) is assigned at least one
reflector for the ultrasound waves from the acoustic distance
sensor.
22. Piston press according to claim 20, characterized in that the
press basket (23) is assigned at least one reflector for the
ultrasound waves from the acoustic distance sensor.
23. Piston press according to claim 20, characterized in that the
acoustic distance sensor is an ultrasound sensor (40).
Description
STATEMENT OF RELATED APPLICATIONS
[0001] This patent application claims priority under 35 USC 119 on
German Patent Application No. 102 38 359.6 filed on 16 Aug.
2002.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The invention relates to piston presses for pressing liquids
out of laundry, in particular, comprising a press ram which has a
hydraulic cylinder and a ram plate assigned to the hydraulic
cylinder or arranged at the free end of a piston rod of the
hydraulic cylinder, and comprising a hydraulic pump for supplying
at least the hydraulic cylinder of the press ram with hydraulic
fluid, and to piston presses for pressing liquids out of laundry,
in particular, comprising a press frame which has a base and a
press ram which can be moved up and down, and comprising a press
basket for holding the laundry.
[0004] 2. Prior Art
[0005] Piston presses of the type addressed here are used for
removing liquids from moist or wet goods to be pressed. Such piston
presses are preferably used in laundries, in order to dewater
laundry of all types. For this purpose, the laundry coming from a
washing machine is freed in the piston press from a major part of
the liquid still bound in it, what is known as the bound solution.
The liquid is pressed out of the laundry under high pressure by the
piston press, and the laundry, for the major part freed from the
bound solution, is then dried.
[0006] The piston press has a press frame to which a press ram is
fixed. The press ram has a hydraulic cylinder and a ram plate which
can be moved up and down by the hydraulic cylinder. For this
purpose, the ram plate is fixed to the free end of a piston rod
which can be moved in and out and belongs to the hydraulic
cylinder.
[0007] After the laundry has been dewatered by moving the ram plate
downwards, the ram plate of the press ram has to be moved up,
unloaded, in an idle stroke. In the process, the hydraulic fluid
located on the piston side of the hydraulic cylinder has to flow
back into a hydraulic tank. As a result, in the case of known
piston presses, the idle stroke for moving the ram plate up
requires a great deal of time, which unnecessarily prolongs the
cycle time of the dewatering operation.
[0008] In addition, moving the ram plate downwards is also to some
extent carried out without any contact between the ram plate and
the laundry, that is to say substantially with no load. In order to
reduce the time for moving the ram plate downwards with no load, in
known piston presses it is known to use hydraulic pumps with two
different delivery flows. When the ram plate is moved downwards
with no load, the hydraulic cylinder is operated with a higher
delivery flow. At the correct time before the laundry is reached,
the hydraulic pump is switched over to a low delivery flow, as a
result of which the ram plate is lowered at a comparatively low
speed until dewatering has been completed. The two-stage lowering
speed of the ram plate which is brought about as a result still
leads to quite high cycle times of each dewatering operation.
[0009] On the basis of the above, the invention is based on the
object of providing a piston press which operates reliably and
which has cycle times which are reduced as compared with known
piston presses.
BRIEF SUMMARY OF THE INVENTION
[0010] A piston press for achieving this object has the features of
a press ram which has a hydraulic cylinder and a ram plate arranged
at the free end of a piston rod of the hydraulic cylinder, and
comprising a hydraulic pump for supplying at least the hydraulic
cylinder of the press ram with hydraulic fluid, characterized in
that the hydraulic pump is designed in such a way that its delivery
flow can be adjusted continuously. As a result of using a hydraulic
pump with continuously adjustable delivery flow, the ram plate of
the press ram can always be moved up and down at maximum speed. The
speed of travel of the ram plate can in this way be adapted to the
conditions prevailing at the time. As a result, the shortest
possible cycle times can be implemented. In particular, the ram
plate can execute idle strokes for moving up and for being lowered
onto the laundry under no load at the greatest possible speed.
[0011] Use is preferably made of a hydraulic pump whose delivery
flow can be varied as a function of the loading. In particular, the
hydraulic pump is regulated in such a way that its output is
approximately constant, by which means, with a lower loading on the
press ram, the hydraulic pump produces a higher delivery flow and,
as a result, the ram plate is moved up and down more quickly under
low loading.
[0012] A further piston press for achieving the object mentioned at
the beginning, which can also be an advantageous development of the
piston press described previously, has the features of a press ram
which has a hydraulic cylinder with a ram plate assigned to the
latter, and comprising a hydraulic pump for supplying at least the
hydraulic cylinder of the press ram with hydraulic fluid,
characterized in the hydraulic lines between the hydraulic cylinder
and the hydraulic pump and a tank for hydraulic fluid have a
relatively large cross section. To this end, hydraulic lines
leading at least to the piston side, preferably also to the
piston-rod side, of the hydraulic cylinder, including the
connections, are provided with a relatively large cross section.
This is a cross section which is larger than the usual,
standardized cross section of the connections and the associated
hydraulic lines to the respective hydraulic cylinder. As a result,
relatively large flow paths are provided for the hydraulic fluid
flowing to the hydraulic cylinders and also the hydraulic fluid
flowing away. In particular, the hydraulic cylinder for moving the
ram plate up and down can be supplied with high volume flows of
hydraulic fluid in the unloaded or little loaded state. Above all,
the flow cross sections of the hydraulic lines and connections for
hydraulic fluid flowing away are designed to be relatively large.
In this way, a large quantity of hydraulic fluid can flow away from
the hydraulic cylinder. An equally large quantity of hydraulic
fluid can be supplied on the other side of the hydraulic cylinder,
which means that the ram plate can be moved up and down at high
speed by the hydraulic cylinder. Above all, in this way the idle
stroke for raising the ram plate into the initial position of the
piston press may be shortened considerably. However, lowering the
ram plate until the latter is loaded can also be carried out very
quickly. This applies in particular when operations are carried out
with a hydraulic pump whose delivery flow can be adjusted
continuously. The speed when lowering the ram plate decreases
continuously, to be specific proportionally to the increase in the
pressing force, above all when using a hydraulic pump with a
continuously controllable delivery flow but constant output.
[0013] Provision is also made to regulate the temperature of the
hydraulic fluid, preferably to keep it constant. As a result, the
flow rate of the hydraulic fluid through connections and hydraulic
lines is not impaired by any increasing viscosity when the
hydraulic fluid is too cold. The temperature of the hydraulic fluid
is preferably regulated by means of a thermostatic valve. By means
of any heating of the hydraulic fluid which may be required, this
ensures that the latter constantly has a specific minimum
temperature. If required, the hydraulic fluid can be cooled if it
is not to exceed a specific temperature.
[0014] A further piston press for achieving the objects mentioned
at the beginning, which can also be a preferred development of the
piston presses described previously, has the features of a press
frame which has a base and a press ram which can be moved up and
down, and comprising a press basket for holding the laundry,
characterized in that the base has at least one storage container
for the liquid pressed out of the laundry. The fact that the base
has at least one storage container for the liquid accumulating as
the laundry is pressed means that the space in the base, in
particular under the base, can be used. The piston press according
to the invention becomes more compact as a result. Separate storage
containers can in this way be dispensed with. Above all, the space
in the base or under the base provides sufficient space to
accommodate an adequate quantity of liquid.
[0015] The storage container is preferably dimensioned to be larger
than the liquid accumulating overall during each dewatering
operation. The storage container in the base of the piston press
preferably accommodates twice the quantity of liquid which
accumulates during dewatering of a batch of laundry. As a result,
the liquid in the storage container can be stored temporarily if
required until it is needed in particular for loading a washing
machine, namely for washing in the laundry to be washed. As a
result of the relatively high storage capacity of the storage
container in the base of the piston press, the operation of the
washing machine can be decoupled to the greatest extent from the
operation of the piston press. According to a development of the
piston press according to the invention, the storage container is
preferably constructed as a frame tank in the base. Then, virtually
the entire frame of the base of the piston press is available for
the storage container for storing accumulating liquid.
[0016] Provision is further made for the frame tank to extend at
least in a region of the top wall of the base of the piston press
which has through holes for leading away the liquid, in particular
water, which accumulates when dewatering the laundry. The water can
pass directly from the press basket, in which the laundry to be
dewatered is located, into the storage container constructed as a
frame tank in the base of the piston press. Any pipelines for
carrying the accumulating liquid away can be dispensed with as a
result.
[0017] A further piston press for achieving the object mentioned at
the beginning, which can also be a development of the piston
presses described previously, has the features of a press frame
which has a base and a press ram which can be moved up and down,
and comprising a press basket for holding the laundry,
characterized in that at least one analogue distance measuring
device is assigned to the press frame to determine the position of
at least the press ram. By means of the analogue distance
measurement, the position of the press ram and/or of the press
basket can be determined reliably and with sufficient accuracy.
However, the analogue distance measurement according to the
invention is less susceptible to interference and, above all,
cheaper than inductive measuring rods used in known piston
presses.
[0018] The respective distance measuring device is preferably
assigned to a press yoke of the press frame. This provides a
reliable, fixed reference point for the analogue distance measuring
device. From this fixed reference point, the analogue distance
measuring device determines the distance between the ram plate or
the press basket and the ram yoke. In this case, the ram plate
itself or a flag-like projection arranged on the press basket
serves as a reflector for the signals of the analogue distance
measuring device. The distance measuring device itself is in this
case simultaneously used as transmitter and receiver.
[0019] The analogue distance measuring device is preferably
constructed as an acoustic distance measuring device. This is
preferably at least one ultrasound sensor. In accordance with the
principle of an "echo sounder", this determines by means of
ultrasound waves the distance of the sensor from a point struck by
the ultrasound waves. This point acts as a reflector and is
assigned to a defined position of the ram plate or the press
basket. The distance of the ram plate from the top plate of the
base may be determined from the distance determined. Likewise, in
this way it is possible to determine whether the press basket is
supported with its underside on the top plate of the base or
not.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] A preferred exemplary embodiment of the piston press
according to the invention will be explained in more detail below
using the drawings, in which:
[0021] FIG. 1 shows a schematic side view of the piston press.
[0022] FIG. 2 shows a detailed and enlarged illustration of an
upper part of the piston press with a press ram.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The figures show a piston press 10 for dewatering washed
laundry 11. For this purpose, the liquid contained in the washed
laundry 11, namely what is known as the bound solution, is pressed
out to the greatest extent by the piston press 10.
[0024] The piston press 10 has a lower base 12 which, on its top
side, has a flat top wall 13. In the top wall 13, drainage holes 14
are arranged in some regions. These are through holes, which are
designed to lead liquid, in particular water, through the top wall
13. On the top side of the top wall 13, an upper run of a conveyor
which is permeable to liquid, at least in the region of the
drainage holes 14, can be arranged, with which the laundry 11 can
be transported away from the piston press 10 after dewatering. The
conveyor, not shown in the figures, can be constructed in such a
way that the upper run can be driven in opposite directions, so
that the dewatered laundry 11 can optionally be transported away to
different, opposite sides of the piston press 10, for example to
different conveyors which can in each case be moved in front of a
row of dryers arranged beside one another. Each of the conveyors on
opposite sides of the piston press 10, which conveyors are
preferably also constructed such that they can be raised and
lowered, is used for the optional charging of all the dryers in a
row.
[0025] Arranged on the base 12 is a plurality of upright columns
15, preferably four columns. The upper ends of all the columns 15
are connected by a press yoke 16. The base 12, the columns 15 and
the press yoke 16 substantially form a rigid press frame 17.
[0026] The press yoke 16 bears a press ram 18, preferably
centrally. The press ram 18 is formed by a hydraulic cylinder 19
which is fixed to the press yoke 16 and whose piston rod 20 can be
led downwards through the press yoke 16. At the lower end, the
piston rod 20 has a ram plate 21 firmly connected to the same. The
ram plate 21 is preferably cylindrical and, on the underside, has a
cushioning element 22 of an elastically deformable material.
[0027] A press basket 23 corresponds to the ram plate 21. The
preferably cylindrical press basket 23 is completely open both on
the top side and on the lower side. During the dewatering of the
laundry 11, the press basket 23 rests with its open underside on
the top wall 13 of the base 12 or on the upper run of the conveyor
which at least partly covers the top wall 13 of the base 12. The
drainage holes 14 passing through the top wall 13 extend in the
manner of a grid at least over the region of the circular press
basket 23. The laundry 11 to be dewatered is located in the press
basket 23. The press ram 18 with the ram plate 21 can be moved into
the press basket 23 from the open top side. In the process, the
cushioning element 23 under the ram plate 21 presses on the laundry
11 located in the press basket 23 and in so doing dewaters the
latter.
[0028] The press basket 23 can be raised and lowered by preferably
two mutually opposite pressure-medium cylinders 24, preferably
hydraulic cylinders, of which only one pressure-medium cylinder 24
is shown in the figures for improved clarity. The pressure-medium
cylinders 24 are fixed with their piston parts 25 under the press
yoke 16. A piston rod 26 which can be moved up and down and belongs
to each pressure-medium cylinder 24 is attached to a carrier arm 27
firmly connected to a side wall of the press basket 23. The press
basket 23 can be raised by the pressure-medium cylinders 24 to such
an extent that the open underside of the press basket 23 is spaced
so far away from the top wall 13 of the base 12 that the dewatered
laundry 11 can pass out of the press basket 23 and can be
transported away out of the region of the piston press 10 by the
upper run of the conveyor.
[0029] In the piston press 10 shown here, the press basket 23 is
constructed from a plurality of parts. Accordingly, the press
basket 23 is composed of a lower press basket part 28 and an upper
press basket part 29. The lower press basket part 28 is constructed
as a thick-walled cylinder with completely open ends. The lower end
of the lower press basket part 28 rests on the top wall 13 of the
base 12. In terms of height, the lower press basket part 28 is
constructed in such a way that the action of pressing the water out
of the laundry 11 by means of the press ram 17 is carried out
exclusively in it. The upper press basket part 29 is provided with
a jacket element of thin sheet metal. The two opposite ends of the
upper press basket part 29 are also completely open. The upper
press basket part 29 rests with a lower end on the lower press
basket part 28, the internal diameter of the upper press basket
part 29 either corresponding to the external diameter of the lower
press basket part 28 or being slightly greater. The internal
diameter of the lower press basket part 28 and of the upper press
basket part 29 are somewhat greater than the external diameter of
the ram plate 20 of the press ram 17. The press ram 17 can
therefore be moved into and out of the press basket 23 without
being forced.
[0030] In the exemplary embodiment shown in FIG. 1, the upper
region of the upper press basket part 29 is somewhat larger than
the lower part of the upper press basket part 29, in that the upper
part of the upper press basket part 29 has a lateral widening on
one side, specifically on the left-hand side of FIG. 1. This
widening corresponds to a loading chute 30 illustrated only
schematically in FIG. 1. Via the loading chute 30, the laundry to
be dewatered can be conveyed into the press basket 23 with the
press ram 17 moved up. In this case, the upper press basket part 29
serves substantially only to guide the laundry 11, in order that
the latter passes specifically into the lower press basket part 28,
in which the subsequent dewatering of the laundry 11 exclusively
takes place.
[0031] On its piston side 31, the hydraulic cylinder 19 of the
press ram 18 can be supplied with hydraulic oil via a hydraulic
line 32. A hydraulic pump 33 is used for this purpose. If the
hydraulic pump 33 supplies hydraulic oil to the piston side 31 of
the hydraulic cylinder 19 via the hydraulic line 32, the piston rod
20 is extended and the ram plate 21 is lowered in order to press
water out of the laundry 11. In order to move the ram plate 21 up,
the piston-rod side 34 of the hydraulic cylinder 19 is supplied
with hydraulic oil by the hydraulic pump 33 via a hydraulic line,
not shown. In this case, hydraulic oil on the piston side 31 flows
at substantially zero pressure into an oil tank, not shown, via the
hydraulic line 32.
[0032] According to the invention, the hydraulic line 32 is
provided with a relatively large internal diameter. The connections
of the hydraulic line 32 to the hydraulic cylinder 19 are also
dimensioned such that they have a relatively large free cross
section, which preferably corresponds approximately to the internal
diameter of the hydraulic line 32.
[0033] The internal diameter of the hydraulic line 32 and the free
flow cross sections of the connections are dimensioned such that
they are considerably larger than normal connections and hydraulic
lines. The internal diameter of the hydraulic lines 32 and the free
flow cross section of the connections is preferably 20 to 40%, in
particular 25 to 30%, of the piston diameter of the hydraulic
cylinder 19. As a result of these relatively large cross sections,
relatively high-volume flows of hydraulic oil can flow to the
piston side 31 of the hydraulic cylinder 19 and, in particular,
large hydraulic oil volumes per unit time can also flow away when
the hydraulic cylinder 19 is retracted in order to move a ram plate
21 up. In this way, in particular idle strokes of the hydraulic
cylinder 19, specifically both in order to move the ram plate 21 up
and also to move the ram plate 21 down onto the laundry 11, are
carried out very quickly in spite of the relatively large hydraulic
cylinder 19.
[0034] The piston-rod side 34 of the hydraulic cylinder 19 has a
considerably smaller volume on the piston side 31, because of the
piston rod 26 which is guided therein and has a relatively large
diameter as shown in FIG. 2. For this reason, the hydraulic line
(not shown) leading to the piston-rod side 34 and its connections
are dimensioned with a smaller internal diameter than the hydraulic
line 32. As compared with conventional hydraulic lines which lead
to the piston-rod side 34 of hydraulic cylinders, the diameter of
the hydraulic line that is not shown on the piston-rod side 34 is
likewise designed to be considerably larger, according to the
invention.
[0035] The diameter of the hydraulic line leading to the piston-rod
side 34 of the hydraulic cylinder 19, including the free flow cross
sections of the connections, is preferably 5 to 25%, preferably 8
to 15%, of the piston diameter of the hydraulic cylinder 19. As a
result, hydraulic oil can escape quickly from the piston-rod side
34 of the hydraulic cylinder 19 when the hydraulic cylinder 19 with
the ram plate 21 is to be moved down onto the laundry 11 in the
press basket 23. Likewise, in order to move the press ram 18 up
quickly, the piston-rod side 34 of the hydraulic cylinder 19 can be
supplied with a relatively high hydraulic oil flow.
[0036] According to the invention, the hydraulic pump 33 is also of
special design. The hydraulic pump 33 is one whose hydraulic oil
delivery flow can be varied continuously. The hydraulic pump 33 can
preferably be regulated in such a way that its output remains
constant. As a result, when the press ram is unloaded, the delivery
flow, that is to say the quantity of the hydraulic oil flow
delivered per unit time by the hydraulic pump 33, will increase
and, as a result, the press ram 18 with the ram plate 21 will be
moved up and down more quickly. With increasing loading on the
piston press 10, specifically when the ram plate 21 is acting on
the laundry 11 to be dewatered, the delivery rate of the hydraulic
oil per unit time (delivery flow) will be reduced by the constantly
regulated output from the hydraulic pump 33 at constant pressure.
As a result, the pressing force required for effective dewatering
can be exerted on the laundry 11 by the ram plate 21 with the
cushioning element 22 fixed underneath it, by the press ram 18
being moved downwards more slowly in order to dewater the laundry
11.
[0037] As a result of the special design of the hydraulic pump 33
with constant output, the speed of travel of the ram plate 21
through the hydraulic cylinder 19 decreases proportionally with
increasing loading, while, when the press ram 18 is unloaded, for
example in order to move the press ram 18 up into the initial
position, a greater delivery flow is available, by which means idle
strokes of the press ram 18 both in the upward direction and
downwards can be carried out very quickly. The cycle time of the
piston press 10 according to the invention is effectively reduced
as a result.
[0038] The pressure-medium cylinders 24, likewise designed as
hydraulic cylinders, for moving the press basket 23 up and down are
preferably also supplied with hydraulic oil by the hydraulic pump
33. However, it is also conceivable to use a separate hydraulic
pump for this purpose, this also being in particular a hydraulic
pump 33 with a continuously variable delivery flow and a control
system which keeps the output constant. In addition, the hydraulic
connections, not shown, on the piston side and on the piston-rod
side of the pressure-medium cylinders 24 designed as hydraulic
cylinders are dimensioned with larger diameters than conventional
hydraulic lines, as a result of which, just like the hydraulic
cylinder 19, the pressure-medium cylinders 24 for raising and
lowering the press basket 23 can be retracted and extended
relatively quickly.
[0039] The hydraulic oil for supplying the hydraulic cylinder 19
and, if appropriate, also the pressure-medium cylinders 24 is
provided with temperature regulation in accordance with a further
proposal of the invention. This ensures that the hydraulic oil
which is delivered by the hydraulic pump 33 always has a minimum
temperature, that is to say is not colder than envisaged. The
regulation of the hydraulic oil temperature is preferably carried
out by means of a thermostatic valve. In order that the temperature
does not fall below a specific minimum, the thermostatic valve
regulates heating of the hydraulic oil, which may possibly become
necessary. It is also conceivable to provide regulation of the
maximum temperature of the hydraulic oil, in order that overheating
of the hydraulic oil is avoided. The thermostatic valve is then
used for the purpose of alternately managing heating or cooling of
the hydraulic oil if the temperature of the hydraulic oil exceeds a
maximum value (cooling) or falls below a minimum value
(heating).
[0040] The base 12 of the piston press 10 is also constructed in a
special way. For this purpose, the base 12 is configured as a frame
tank 35, in which at least one storage container 36 is integrated.
The frame tank 35, illustrated schematically in FIG. 1, has a
hollow space, which forms the storage container 36, in the region
between the columns 15. The hollow space is arranged between the
top wall 13 and a bottom wall 37 of the base 12, spaced apart from
the former. The storage container 36 is located completely in the
region under the drainage hole 14 in the top wall 13. The storage
container 36 is provided with supporting sections 38 for reasons of
stability. The supporting sections 38 are located between the top
wall 13 and the bottom wall 37 and support the two mutually in the
manner of a frame. Transversely oriented through holes 39 in the
supporting sections 38 make the latter permeable to liquid so that,
in spite of the supporting profiles 38, a coherent storage
container 36 is located under the drainage hole 14 in the top wall
13. If necessary, it is conceivable to design some of the
supporting sections 38 to be impermeable to water, so that a
plurality of small storage containers 36 are produced, which can be
filled and emptied as required. The individual storage containers
36 can be connected to one another by means of pipelines and/or
valves in such a way that, if required, an interchange of liquid
between the individual storage containers 36 can take place.
[0041] A further special feature of the piston press 10 according
to the invention is that the instantaneous position of the press
ram 18, in particular of the ram plate 21, is determined
continuously by an analogue distance measuring device. In the
piston press 10 shown here, the position of the press basket 23 is
determined continuously in the same way. The analogue distance
measuring device has an acoustic sensor element which, in the
exemplary embodiment shown, is designed as an ultrasound sensor 40.
The latter is mounted in a fixed position under the press yoke 16,
specifically in such a way that an acoustic measuring signal,
namely sound waves sent out by the ultrasound sensor 40, strikes an
upper side of the ram plate 21. The sound waves are reflected here
and received again by the ultrasound sensor 40. By means of
measuring the propagation time of the sound waves, the distance of
the upper side of the ram plate 21 from the ultrasound sensor 40 on
the underside of the press yoke 16 is determined continuously. From
this, on the basis of the known constructional dimensions of the
piston press 10, the distance of the underside of the ram plate 21
and of the cushioning element 22 fixed underneath it from the press
basket 23, in particular the top wall 13 of the base 12, on which
the press basket 23 rests, can be determined. Alternatively or
additionally, it is also conceivable to provide an ultrasound
sensor 40 under the press yoke 16 or on the underside of the ram
plate 21, with which the distance of the ram plate 21 and of the
cushioning element 22 from the upper side of the heap of laundry 11
in the press basket 23 can be determined. The press ram 18 can then
be moved as far as the laundry 11 in a specific manner and at high
speed.
[0042] At least one further ultrasound sensor or another acoustic
distance measuring device is mounted on the underside of the press
yoke 16 in order to determine the position of the press basket 23.
This ultrasound sensor is mounted under the press yoke 16 in such a
way that its signal, specifically its sound waves, either strikes
the carrier arm 27 on the press basket 23 or a separate reflecting
means projecting outwards with respect to the press basket 23. By
using the sound waves reflected back, the distance of the carrier
arm 27 or of the separate reflector on the press basket 23 from the
ultrasound sensor on the underside of the press yoke 16 can then be
determined. By means of this ultrasound sensor, it is thus possible
to establish whether the press basket 23 is standing on the top
wall 13 of the base 12 and can be filled with laundry 11 to be
dewatered.
List of Reference Symbols
[0043] 10 Piston press
[0044] 11 Laundry
[0045] 12 Base
[0046] 13 Top wall
[0047] 14 Drainage hole
[0048] 15 Column
[0049] 16 Press yoke
[0050] 17 Press frame
[0051] 18 Press ram
[0052] 19 Hydraulic cylinder
[0053] 20 Piston rod
[0054] 21 Ram plate
[0055] 22 Cushioning element
[0056] 23 Press basket
[0057] 24 Pressure-medium cylinder
[0058] 25 Piston part
[0059] 26 Piston rod
[0060] 27 Carrier arm
[0061] 28 Press basket lower part
[0062] 29 Press basket upper part
[0063] 30 Loading chute
[0064] 31 Piston side
[0065] 32 Hydraulic line
[0066] 33 Hydraulic pump
[0067] 34 Piston-rod side
[0068] 35 Frame tank
[0069] 36 Storage container
[0070] 37 Bottom wall
[0071] 38 Supporting section
[0072] 39 Through hole
[0073] 40 Ultrasound sensor
* * * * *