Information
-
Patent Grant
-
6644930
-
Patent Number
6,644,930
-
Date Filed
Tuesday, October 9, 200122 years ago
-
Date Issued
Tuesday, November 11, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Freay; Charles G.
- Belena; John F.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 417 53
- 417 46
- 417 393
- 417 395
- 417 426
-
International Classifications
-
Abstract
A pumping method and arrangement, in which at least two chamber pumps (A, B) are operated in order to achieve a constant output flow. In the pumping procedure and arrangement, the entry chamber (110, 130) of the chamber pump is pre-pressurised close to the actual working pressure after the filling stage in order to achieve a constant output flow.
Description
BACKGROUND OF THE INVENTION
The object of the invention is a method and arrangement for the pumping of a material used in the industry, such as graphite or a certain partial component of a material composition, in which method the material to be pumped is first pre-pressurised prior to the actual pumping event carried out on the material, in order to balance the yield of the pumping arrangement.
In the steel industry, rolling technology is used to manufacture steel plates, strip, pipes, and various profiles. Oils or other friction reducing lubricants are applied between the rolls and the material to be rolled in order to reduce friction. The use of lubricant and successful lubrication improves the uniformity of the rolling result and prevents the rolls from wearing.
In hot rolling, the temperatures are around +1000° C., and the rolls must often be cooled with ample amounts of water. Thus the oil used as a lubricant will remain on top of the water film and the lubrication result will deteriorate, simultaneously causing problems with the rolling quality. An unevenly rolled steel strip is rolled thinner by cold rolling, but rolling mistakes generated during hot rolling cannot always be corrected by cold-rolling. Thus the product will contain quality faults which mean additional waste costs for the manufacturer.
The U.S. Pat. No. 4,201,070 presents the use of graphite-water solutions in the manufacture of seamless pipes. The U.S. Pat. No. 5,638,893 presents a lubricant system, with which a continual flow of lubricant is achieved, as well as a multitude of nozzles connected to the system, and each of the nozzles can be directed separately. Moreover, it presents a nozzle moving system, which enables continual lubrication, grouping of nozzles into combinations, and automatic cleaning of nozzles at specified intervals. The U.S. Pat. No. 5,090,225 presents a method where oil-water solution is sprayed in the roll gap from both sides of the metal strip.
Laboratory tests have shown the graphite-liquid solution to be a better lubricant in the rolling process than the oil-based lubricant currently in use. The graphite-liquid solution reduces friction better than other lubricants, and its temperature stability is good. The chemical composition of graphite is carbon. The implementation of graphite as a lubricant has been prevented by the strong wear it causes to pumping equipment. In the procedures tested, graphite is sprayed via high-pressure pumping equipment, for example, on the rolling surfaces via several sapphire nozzles in order to spread the graphite evenly. The problem of this procedure is the wear of the pumping equipment parts, because the graphite particles grind the valves and other parts of the equipment. This results in the uneven spraying of graphite and in a greater demand on maintenance, and therefore, in high maintenance and downtime costs. In certain applications, where an exact dosage of partial components is required, excessive gas within the liquid circuits is the problem. Similarly, high pressure existing in certain pumping arrangements expands the flexible pipelines of the arrangement from time to time and causes leakages in packings and gaskets, etc. The above-mentioned adverse factors affecting the volume flow render it more difficult to maintain the yield of the prior art pumping arrangement at a uniform level.
In some industrial applications, the consumption of the material to be pumped is small and, in addition to that, the correct dosage of the material in relation to another partial component to be pumped is critical for the manufacture of the product. For example, in the manufacture of thin, shaped surgical gloves, the proportions of partial components to be sprayed are very accurately determined. The deviation in the mutual proportions of the partial components must not exceed a couple parts in thousand for the product to fulfill the requirements set. The manufacture of such products set very high demands on the pumps used in the processes, and especially on the evenness of their yield with regard to time. The U.S. Pat. No. 4,844,706 presents a procedure where an arrangement of two membrane pumps is used to achieve a uniform yield in the spraying nozzle connected in the system. The membrane pumps are controlled with the help of “OPEN-SHUT” valves controlled by external control logic. The problem with the valves in question is the slowness caused by their structure due to which the pressure only changes after a certain delay after the valve is opened. The U.S. Pat. No. 5,205,722 presents an arrangement where three membrane pumps are used to achieve a uniform yield of the liquid to be pumped. The pumping arrangement is controlled by a partially mechanical rotating cylinder system. It is especially difficult to make the joint yield of the pumps to remain constant in a situation where the pump pumping the liquid to be pumped is replaced by another pump in the pumping arrangement. Replacing a pump in the working phase by another causes a change in the volume flow, which in turn causes decrease in yield in the output circuit which, in some cases, will lead to a deterioration of quality in the end product.
SUMMARY OF THE INVENTION
The objective of the invention is to reduce the above-mentioned adverse effects relating to the prior art.
The pumping method for material in accordance with the invention is characterised by the fact that the pumping arrangement to be pre-pressurised is a chamber pump arrangement in which the entry chamber of the chamber pump between the filling stage and the working stage of the chamber pumps is pre-pressurised with the help of the working liquid to a pressure determined in advance.
The pumping arrangement for material in accordance with the invention is characterised by the fact that the pumping arrangement consists of two adjoined chamber pumping arrangement and their control system.
Some advantageous embodiments of the invention have been presented in dependent patent claims.
The basic idea of the pumping method and arrangement in accordance with the invention is as follows: the pumping arrangement consists of a separate, assisting working liquid circuit and of the pumping circuit of the material to be pumped. Thus the possible wearing, corrosive and other disadvantageous properties of the material to be pumped do not have an influence on the working liquid side. An arrangement of two or more chamber pumps is used for the pumping of material and, in this pumping arrangement, the entry chamber of each chamber pump is subjected to a short pre-pressurising after the filling stage in order to guarantee a uniform yield. The arrangement in accordance with this method may contain several pumping arrangements in accordance with the invention, connected in parallel. This method is suited both for low and high-pressure pumping. Pumping can be monitored and controlled specifically for each operation point, in which case the pumping of liquid remains highly controlled at all times. These properties make the liquid pumping arrangement in accordance with the invention free of maintenance, which means that standstill time in the manufacturing process is significantly reduced.
The advantage of this invention is that it enables the yield of the liquid to be pumped to have significantly smaller variations than methods according to the prior art.
A further advantage of the invention is the fact that a pumping arrangement in accordance with the invention is able to pump highly wearing liquid solutions dozens of times longer than prior art pumping arrangements before maintenance is required. Thus significant savings in costs can be achieved in the heavy metal industry.
Another advantage of the invention is the fact that a certain embodiment of the pumping arrangement can be used in applications where a part of the equipment/parts of the process are energised to more than 100 kV.
BRIEF DESCRIPTION OF THE DRAWINGS
A detailed description of the invention is given in the following. The description refers to the attached drawings where.
FIG. 1
depicts, as an example, the embodiment which is used in the pumping of graphite-liquid solution,
FIG. 2
depicts, as an example, the embodiment which is used in painting systems based on static electric charge, and
FIG. 3
depicts the behaviour of the pressure in the pumping arrangement as a rotation speed-pressure-time chart, measured from the working liquid circuit.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1
shows, as an example, a principle drawing of the pumping arrangement where the pumping method in accordance with the invention has been used. The pumping arrangement consists of two chamber pump systems which are alike: pumping arrangement A, reference numbers
101
to
116
of the figure, and pumping arrangement B, reference numbers
121
to
136
, and of a joint feeding system of the material to be pumped, reference numbers
137
to
139
, as well as of a control system for the pumping arrangement, reference number
140
. In the embodiment of the
FIG. 1
, the operation of the pumping arrangements A and B is synchronised with one another in order to guarantee a uniform, pulse-free yield. Both pumping arrangements, A and B, consist of two liquid circuits. The first circuit,
101
to
110
,
121
to
130
, where the working liquid flows, is later on referred to as the working liquid circuit. The other circuit,
112
to
115
,
132
to
135
, as well as
137
to
139
, where the material to be pumped (which advantageously in a certain embodiment is a graphite-liquid solution) flows, is later on referred to as the pumping circuit.
The parts of the pumping arrangement A and their operation are described in the following. The parts of the pumping arrangement B are alike, but its operation takes place in different stages, as described in the explanation to the FIG.
3
. In the pumping arrangement A, the working liquid is pumped from the container
102
through a standard flow pump
103
via a feed line to the chamber pump
109
. The pump
103
is operated with the motor
101
. A non-return valve
104
is located in the line after the pump
103
to prevent the working liquid from flowing back to the pump when the pump is not working. After the valve
104
there is a flow indicator
105
in the line, followed by a seat-type control valve
106
, through which the working liquid is directed to the chamber pump
109
or returned to the working liquid circuit via the receiver container
107
. After the control valve
106
there is a pressure-measuring device
108
for the measurement of the pressure in the entry chamber
110
of the chamber pump. The material to be pumped is fed from the container
137
through the valve
138
to the feed pump
139
and from there through the gravitational non-return valve
116
to the exit chamber
112
of the chamber pump
109
, when the pump in question is in the filling stage. The material to be pumped from the exit chamber
112
of the chamber pump
109
is fed during the working stage of the pump through the gravitational non-return valve
115
to the line
117
, along which the material is directed to the specific operation point in question. The line of the material to be pumped by the second chamber pump
129
is also connected to the same line
117
. A measuring instrument
118
′ for the location of the membrane, located in the protective pipe
118
, is attached to the membrane
111
of the chamber pump
109
; the measuring instrument
118
′ is favourably a piston-like body, whose end positions are perceived by the sensor bodies
113
and
114
attached to the protective pipe. The protective pipe
118
is dimensioned so loosely that the working liquid is able to fill the entire volume of the protective pipe. Thus the sensor bodies
113
and
114
are able to observe the working stage position of the membrane
111
. The data received from the sensor bodies
113
and
114
is used for the control of the pump
103
and the valves
106
and
138
. The pumping arrangement also includes a control system
140
which observes/controls the motors, valves and pressure measuring devices of the pumps.
The overall yield of the material to be pumped is adjusted by the pumping arrangement where the material is pumped with the help of the pumping arrangements A and B through the line
117
to the operation target. A feeding line of the material to be pumped comes from the container
137
to the exit chamber
112
of the chamber pump
109
in the pumping arrangement A. In the feeding line, the flow to the chamber pump
109
is controlled by the non-return valve
116
, enabling the flow of the material to be pumped from the container
137
to the exit chamber
112
of the chamber pump
109
only in the filling stage of the chamber pump
109
in question. There is a line
117
leading from the exit chamber
112
of the chamber pump
109
through the non-return valve
115
to the operation target. The feeding line of the material to be pumped coming from the pumping arrangement B is also connected to the line in question.
The movement of the membrane
111
in the chamber pump
109
is directed advantageously with the pressure difference existing in the working liquid circuit and the pumping circuit. When the pressure on the side of the entry chamber
110
of the chamber pump
109
is greater than the pressure in the exit chamber
112
, the chamber pump
109
is in the working stage, i.e. the membrane is moving the material to be pumped through the non-return valve
115
to the line
117
. The volume flow of the material to be pumped is maintained constant by adjusting the rotational speed of the standard volume pump
103
located in the working liquid circuit in such a way that the volume flow of the working liquid circuit remains constant. When the pressure of the exit chamber
112
of the chamber pump
109
is greater than the pressure in the entry chamber
110
, i.e. the chamber pump
109
is in the filling stage, the membrane
111
in the chamber pump
109
moves to the direction, in which the material to be pumped is flowing from the container
137
to the exit chamber
112
. In this case, only a flow from the container
137
via the non-return valve
116
to the exit chamber
112
of the chamber pump
109
is allowed.
The pressure difference on the different sides of the membrane is controlled with the help of the pumps
103
,
123
and
139
in such manner that the chamber pump
109
and
129
alternate in working and filling stages. When one of the chamber pumps
109
and
129
come to the working stage, the flow of the material to be pumped to the working stage from the exit chamber of the chamber pump in question opens the non-return valve following the exit chamber of the chamber pump in question. The other chamber pump is simultaneously reaching the end of its working stage, in which case the standard volume pump located in the working liquid circuit of the other chamber pump in question is stopped. As a result, the non-return valve after the other chamber pump in question is closed gravitationally during a couple of seconds. When the non-return valve in question has closed, the other chamber pump in question moves to the filling stage, in which case the exit chamber of the other chamber pump in question is filled with the material to be pumped. In other advantageous embodiment, a spring or a working cylinder is attached to the membrane of the chamber pumps
109
and
129
, and it is used to help the membrane
111
,
131
during the filling stage to return to the starting position of the working stage.
After the completion of the filling stage of the chamber pump, pre-pressurising in accordance with the invention is carried out. Pre-pressurising is achieved by rotating the standard volume pump
103
,
123
as long as it takes to achieve the desired pressure in the entry chamber
110
,
130
of the chamber pump
109
,
129
. After this, the standard volume pump is stopped, and the gravitationally operating non-return valves located in the feeding line of the working liquid close, and thus prevent a pressure decrease in the entry chamber
110
,
130
of the chamber pump
109
,
129
. The cycles of the working and filling stages for the pumps A and B are presented in more detail in connection with the description to the FIG.
3
.
The example pumping arrangement in the
FIG. 1
consists of the membrane location sensor bodies
113
,
114
and
133
,
134
, located in the protective pipe
118
,
141
of the measuring body attached to the membrane
111
,
131
of the chamber pump
109
,
129
; with the sensor bodies and measuring instruments
118
′ and
141
′ it is possible to observe the various operational positions of the membrane
111
,
131
. The sensor bodies can be realised in several different manners. Advantageously they can be either galvanic, inductive, electrostatic, or optical identification elements. In
FIG. 1
, when the membrane
111
of the chamber pump
109
has achieved the end stage of the working stage, the sensor body
113
gives a signal which is directed to the control system
140
of the pumping arrangement. The control system gives a stopping command to the motor
101
of the standard volume pump
103
of the pumping arrangement A. Simultaneously, the seat valve
106
located in the line connected to the pumping arrangement A is given a command to move into a position in which the flow of the working liquid is also allowed to the container line
107
, and from there, to the container
102
. Simultaneously, the control system gives the motor
121
of the standard volume pump
123
of the pumping arrangement B a command to start, and similarly, the seat valve
126
is given the command to move into a position, in which it no longer allows the working liquid to flow into the container
102
. When the pressure is increased to an adequate level in the entry chamber
130
of the chamber pump
129
, the pumping of the material to be pumped is transferred from the chamber pump
109
to the chamber pump
129
in the manner described above.
The pumping arrangement and its working liquid circuit in the
FIG. 1
are suited for applications requiring a larger pumping capacity and good uniformity of the exit flow, for example, for pumping arrangement which pump a graphite-liquid solution. The working liquid comes from the containers
102
,
122
, from which it is pumped with the standard volume pump
103
,
123
to the entry chamber
110
,
130
of the chamber pumps
109
,
129
. The pump
103
,
123
is operated with a motor
101
,
121
, which in turn is controlled by frequency transformer
140
′. Seat valves
106
,
126
are also controlled with the earlier mentioned control system
140
. The data given by the pressure measuring devices
108
,
128
is utilised in the control of the pumping arrangements A and B, and in the generation of pre-pressurisation in a manner to be presented later.
FIG. 2
presents an advantageous embodiment of the invention which is utilised in applications which require a very precise control of the exit flow of pumping. In the pumping circuit, the material to be pumped (which may be electrostatic painting liquid) is received from the container
237
, from which a material feeding line leads to the exit chamber
212
,
232
of the chamber pump
209
,
229
of the chamber pump arrangement C and D, in a manner presented in conjunction with the explanation to the
FIG. 1
with the exception that there is no separate pump in the line from the storage container
237
to the chamber pumps via the valve
238
, but the material to be pumped is transferred to the exit chamber of the chamber pump with the help of gravity/low pressure via the gravitationally operating non-return valve
216
,
236
. In the working stage of the chamber pump, operation is the same as described in the explanation to the FIG.
1
. The liquid to be pumped flows along the feeding line
217
from the chamber pumps to the operational target.
In the embodiment of the
FIG. 2
, the working liquid circuit is altered as follows in order to achieve a very good pressure control at the exit flow of the pumping arrangement. Parts of the working liquid circuit of the pumping arrangement C and their operation are described in the following. The parts of the pumping arrangement D are corresponding, but its operation takes place in different stages, as presented in the explanation to the FIG.
3
. The working liquid circuit contains the stepping motor with its gearbox
200
and the adjoined tachogenerator
201
, spindle motor
202
with the spindle, spindle position sensor bodies
203
and
204
, piston pump
205
connected to the spindle, seat valve
206
located in the line after the piston pump, working liquid container
207
, pressure measuring device
208
, as well as the entry chamber
210
of the chamber pump
209
. In the embodiment in question, the working liquid is not circulated, but it moves from the piston pump
205
via the seat valve
206
to the entry chamber
210
of the chamber pump
209
during the working stage, and returns when the chamber pump is in the filling stage by altering the direction of motion of the piston in the piston pump which, in turn, is effected by changing the direction of rotation of the spindle motor. The signal received from the tachogenerator
201
is utilised in the control system
240
for the control of the speed and direction of rotation of the stepping motor
200
of the pumping arrangement C. Similarly, the operational position of the valve
206
is controlled with the help of the control system
240
.
In the pre-pressurisation in accordance with the invention, the stepping motor
200
is rotated as long as the desired pressure is achieved in the entry chamber
210
of the chamber pump
209
. Since the stepping motor
200
is stopped, neither the piston of the piston pump
205
is moving, and thus it is possible to maintain the pressure in the entry chamber
210
of the chamber pump
209
at the desired level up to the beginning of the working stage. When necessary, more working liquid may be taken from the container
207
, or also the amount of working liquid may be reduced. The seat valve
206
is also utilised as a removal body for the gas in the working liquid in the manner described in more detail in conjunction with the explanation to FIG.
3
.
The flow channel from the piston pump to the valve is arranged in such a way that during the filling stage of the chamber pump arrangement in question, gas contained in the working liquid will be accumulated in such a part of the seat valve, from which it can be directed to the storage container
207
. When the gas, of which the working liquid may contain several percent, is successfully removed from the working liquid in a controlled manner, the working liquid no longer can be compressed, and thus the pressure control in the entry chamber of the chamber pump is good. With this method, the prevailing pressure differences in the entry chambers of the chamber pumps of the pumping arrangement can be controlled better than with arrangement in accordance with the prior art technology.
The position sensor bodies
213
and
214
of the membrane
211
located in the chamber pump
209
can be realised in a number of different ways. Galvanic, inductive, electrostatic, or also optical identification elements can be connected to the protective pipe
218
,
239
of the measuring body. In one advantageous embodiment, optical identification elements can be used, in which case the membrane pump itself and the material to be pumped can be galvanically separated from the rest of the pumping arrangement. Such applications are, for example, painting methods based on the static electrical charge of the material. With these methods, the charging voltages of the paint material to be used may exceed 100 kV, in which case a galvanic separation of the device is important for operational safety purposes alone.
The pumping arrangements described in
FIGS. 1 and 2
can be connected several pieces to operate in parallel manner. In that case they can be utilised in applications, in which several partial components are mixed into one operational target, or in which the material to be pumped must be sprayed simultaneously on a large surface.
The pre-pressurisation utilised in the pumping arrangement in accordance with the invention, its timing and influence on the exit flow of the pumping arrangement A, B or C, D is presented in the
FIG. 3
by utilising the reference numbering of the pumping arrangement A, B of the FIG.
1
. The time axis used only refers to the sequence of the events, not to the exact duration of different events. For example, the pre-pressurisation used in the pumping arrangement may last only some milliseconds at its shortest, and the actual working stage may last dozens of seconds. The
FIG. 3
shows, in chronological order, the revolutions of the motor NRM
1
of the standard volume pump
103
in the working liquid circuit of the pumping arrangement A, the pressure P
1
of the entry chamber
110
or the chamber pump
109
, the revolutions of the motor NRM
2
of the standard volume pump
123
in the working liquid circuit of the pumping arrangement B, the pressure P
2
of the entry chamber
130
or the chamber pump
129
, and the exit flow F
1
+2 in the line
117
leaving from the pumping arrangement.
The time chart starts with the moment t
1
, in which the chamber pump
129
is responsible for the pumping of the material to be pumped in the pumping arrangement.
In this case, the motor of the standard volume pump
123
is turning with the standard speed NRM
2
in accordance with the set value, as seen in the time chart figure, generating a standard volume flow in the working liquid circuit. The pressure P
2
of the entry chamber
130
or the chamber pump
129
remains at the desired standard level, which leads to a movement by the membrane
131
in a direction which makes the material to be pumped to flow from the exit chamber of the chamber pump
129
to the line
117
.
At the moment t
1
, the filling stage of the other chamber pump
109
has already been completed, and the exit chamber
112
of the chamber pump
109
is full of the material to be pumped. At the moment t
1
, the motor of the standard volume pump
103
is started. The revolutions of the motor NRM
1
are controlled to the desired level, which is lower than the motor revolutions used in the actual working stage. As a result of this measure carried out, the pressure in the entry chamber
110
of the chamber pump
109
is increasing in accordance with the diagram P
1
. At the moment t
2
, the motor of the standard volume pump
103
is stopped, and the diagram shows that the pressure in the entry chamber
110
of the chamber pump
109
remains below the pressure level used in the working stage. Since the pre-pressurisation pressure P
1
(40% to 90% or 95% of the working pressure) remains clearly lower than the pressure used in the actual working stage, which exists in the line
117
due to the working stage of the chamber pump
129
, the non-return valve
115
after the chamber pump
109
does not open during the pressure-pressurisation. In turn, the non-return valve
104
prevents the working liquid from flowing backwards, when the standard volume pump
103
is stopped at the moment t
2
. Thus the pressure can be maintained unchanged in the entry chamber
110
of the chamber pump
109
up to the moment t
3
. In case it is noted that the pressure changes between the moments t
2
and t
3
, it indicates a leakage somewhere in the pumping system which must be found and repaired.
Thus the pressure adjustment also operates as a fault indicator. At the moment t
3
, the chamber pump
129
approaches the end of its working stage. At the moment t
3
, the control system starts the motor of the standard volume pump
103
and controls it to rotate at the speed required by the working stage. Because the pressure existing in the entry chamber
110
of the chamber pump
109
already is almost the pressure required during the working stage, the actual working stage pressure is achieved in a controlled manner and quickly during the time Δt (Δt=t
4
−t
3
), as shown in the diagram P
1
. The time Δt in question can be determined on the basis of the application to be used, starting from 1 ms and lasting up to several seconds. The speed of the pressure control is determined in such a way that the target pressure is achieved quickly and with as little vibration as possible.
At the moment t
4
, the pressure of the entry chamber
110
of the chamber pump
109
is at the desired pressure level of the working stage. At the same moment t
4
, the control system starts to slow down the revolutions of the standard volume pump
123
. At the moment t
5
, the standard volume pump
103
rotates at the set speed generating the standard volume flow within the working liquid circuit from the pump
103
to the entry chamber
110
of the chamber pump
109
. At the moment t
6
, the standard volume pump
123
stops, which at the moment t
7
results in the decrease of the pressure in the exit chamber
132
of the chamber pump
129
and the gravitational non-return valve
135
closes and the pumping work is transferred for the chamber pump
109
, because the non-return valve
115
has opened. In the time frame t
5
to t
11
, the chamber pump
109
continues to the working stage. At the same time, the chamber pump
129
is in the filling stage, in which the exit chamber
132
of the chamber pump
129
is filled with the material to be pumped. Between the moments t
8
and t
9
, the entry chamber
130
of the chamber pump
129
is subject to pre-pressurisation in the same manner as it was carried out with the chamber pump
109
during the moments t
1
and t
2
. At the moment t
9
, the pre-pressurisation is completed and the standard volume pump
123
is stopped. At the moment t
10
, the standard volume pump
123
is started, in order to be able to transfer the pumping work back to the chamber pump
129
. From this point onwards, the operation is repeated with the pumping arrangement B in the same way as it is described for the pumping arrangement A to take place during the moments t
3
to t
11
.
The embodiment described by the
FIG. 2
follows the same time chart as the embodiment of the
FIG. 1
, however with the following exceptions. In
FIG. 3
, the pump revolutions described stand for the working stage revolutions of the two spindle motors
200
,
220
operating the piston pump. Moreover, the cylinder, flow line and valve
206
,
226
of the piston pump
205
,
225
have been arranged so that the line directing to the valve from the working cylinder of the piston pump is constantly rising. Thus the gas mixed with the working liquid is collected in the valve
206
,
226
, from where it can be removed at the beginning of both the filling stage and the pre-pressurising stage t
1
to t
2
to the container
207
,
227
. When the gas has been successfully removed to the container
207
,
227
, the channel leading to the container is closed. Otherwise, the filling stage of the pumping arrangement, the pre-pressurisation of the entry chamber and the working stage follows one another according to the explanation to the pumping arrangement in accordance with the FIG.
1
.
The control system
140
,
240
relating to the pumping arrangement not only takes care of the control of the motors and valves of the pumps, but also of the storing and processing of the data received from pressure measurements. The control system gives an alarm, in case the pressure behaviour of the pumping arrangement changes during the operation in some way. Thus it is possible to anticipate and prevent the operation of a pumping arrangement about to get broken. This way it is also possible to prevent the manufacture of products with poor quality, and to reduce additional costs occurring in the manufacturing process.
In the above, some very advantageous embodiments of the invention have been described. For a person skilled on the art, it is clear that also other types of solutions can be realised in the framework of this invention idea and of the patent claims. For example, the pumping arrangement can be utilised as a casting machine for a casting piece requiring several partial components.
Claims
- 1. A method for pumping a material with a first diaphragm pump having an entry chamber that receives a working liquid and a pumping chamber that receives the material to be pumped, where the entry chamber and the pumping chamber are separated by a movable membrane, the method comprising the steps of:increasing a pressure in the entry chamber and the pumping chamber during a filling stage when the pumping chamber is not pumping the material to be pumped by pumping the working liquid into the entry chamber until the pressure in the entry chamber reaches a predetermined pre-pressure that is less than a working pressure of the entry chamber; and after the filling stage, further increasing the pressure in the entry chamber and the pumping chamber to the working pressure during a working stage when the pumping chamber is pumping the material to be pumped from the pumping chamber by pumping the working liquid into the entry chamber.
- 2. The method of claim 1, further comprising the step of maintaining the pressure in the entry chamber at the pre-pressure after the filling stage until the step in which the pressure in the entry chamber is further increased.
- 3. The method of claim 1, further comprising the step of not pumping the working liquid into the entry chamber after the filling stage until the step in which the pressure in the entry chamber is further increased.
- 4. The method of claim 1, wherein the pre-pressure is 40% to 95% of the working pressure.
- 5. The method of claim 1, wherein the pre-pressure is maintained in the entry chamber for a period of 1 ms to 10,000 ms.
- 6. The method of claim 1, further comprising the steps of pumping the material with a second diaphragm pump that operates the same as the first diaphragm pump and whose output is connected to an output from the first diaphragm pump, wherein the filling stage of the second diaphragm pump is during the working stage of the first diaphragm pump and the filling stage of the first diaphragm pump is during the working stage of the second diaphragm pump.
- 7. A pump for pumping a material, comprising:two diaphragm pumps that each have an entry chamber that receives a working liquid and a pumping chamber that pumps the material to a common outlet, where the entry chamber and the pumping chamber are separated by a movable membrane; and a controller that increases a pressure in the entry chamber of one of said two pumps until reaching a predetermined pre-pressure less than a working pressure of the pump while the other of said two pumps is pumping the material from the respective pumping chamber to the common outlet at the working pressure.
- 8. The pump of claim 7, wherein said controller maintains the pressure in the entry chamber at the pre-pressure until the pressure in the entry chamber is further increased to the working pressure.
- 9. The pump of claim 7, wherein said controller stops pumping the working liquid into the entry chamber after the pre-pressure has been reached until the pressure in the entry chamber is further increased to the working pressure.
- 10. The pump of claim 7, wherein said controller controls the pre-pressure to 40% to 95% of the working pressure.
- 11. The pump of claim 7, wherein said controller maintains the pre-pressure in the entry chamber for a period of 1 ms to 10,000 ms.
- 12. The pump of claim 7, further comprising separate non-return valves between the pumping chamber of each of said two pumps and said common outlet.
- 13. The pump of claim 12, wherein said non-return valves permit flow of the material from said two pumps to said common outlet at the working pressure but not at the pre-pressure.
- 14. A pump for pumping a material, comprising:a first diaphragm pump having a first entry chamber that receives a working liquid and a first pumping chamber that receives the material, said first entry chamber and said first pumping chamber being separated by a first movable membrane; a second diaphragm pump having a second entry chamber that receives a working liquid and a second pumping chamber that receives the material, said second entry chamber and said second pumping chamber being separated by a second movable membrane; a common outlet connected to said first and second pumping chambers; and a controller that (a) increases a pressure in said first entry chamber and said first pumping chamber during a first filling stage when said first pumping chamber is not pumping the material and said second pumping chamber is pumping the material by pumping the working liquid into said first entry chamber until the pressure in said first entry chamber reaches a predetermined pre-pressure that is less than a working pressure, (b) after the first filling stage, further increases the pressure in said first entry chamber and said first pumping chamber to the working pressure during a first working stage when said first pumping chamber is pumping the material from said first pumping chamber to said common outlet by pumping the working liquid into said first entry chamber, (c) increases a pressure in said second entry chamber and said second pumping chamber during a second filling stage when said second pumping chamber is not pumping the material to be pumped during said first working stage by pumping the working liquid into said second entry chamber until the pressure in said second entry chamber reaches a predetermined pre-pressure that is less than the working pressure, and (d) after the second filling stage, further increases the pressure in said second entry chamber and said second pumping chamber to the working pressure during a second working stage when said second pumping chamber is pumping the material from said second pumping chamber to said common outlet by pumping the working liquid into said second entry chamber.
- 15. The pump of claim 14, wherein said controller maintains the pressure in said first entry chamber at the pre-pressure until the pressure in said first entry chamber is further increased to the working pressure, and maintains the pressure in said second entry chamber at the pre-pressure until the pressure in said second entry chamber is further increased to the working pressure.
- 16. The pump of claim 14, wherein said controller stops pumping the working liquid into said first entry chamber after the pre-pressure has been reached until the pressure in said first entry chamber is further increased to the working pressure, and stops pumping the working liquid into said second entry chamber after the pre-pressure has been reached until the pressure in said second entry chamber is further increased to the working pressure.
- 17. The pump of claim 14, wherein said controller controls the pre-pressure to 40% to 95% of the working pressure.
- 18. The pump of claim 14, wherein said controller maintains the pre-pressure in said first and second entry chambers for a period of 1 ms to 10,000 ms.
- 19. The pump of claim 14, further comprising a first non-return valve between said first pumping chamber and said common outlet and a second non-return valve between said second pumping chamber and said common outlet.
- 20. The pump of claim 19, wherein said first and second non-return valves permit flow of the material to said common outlet at the working pressure but not at the pre-pressure.
Priority Claims (1)
Number |
Date |
Country |
Kind |
990780 |
Apr 1999 |
FI |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/FI00/00297 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/61945 |
10/19/2000 |
WO |
A |
US Referenced Citations (7)
Foreign Referenced Citations (2)
Number |
Date |
Country |
2257481 |
Jan 1993 |
GB |
61291781 |
Dec 1986 |
JP |