U.S. patent application number 10/309941 was filed with the patent office on 2003-06-05 for dispensing apparatus for a fluid.
This patent application is currently assigned to Levitronix LLC. Invention is credited to Schob, Reto.
Application Number | 20030103852 10/309941 |
Document ID | / |
Family ID | 8184289 |
Filed Date | 2003-06-05 |
United States Patent
Application |
20030103852 |
Kind Code |
A1 |
Schob, Reto |
June 5, 2003 |
Dispensing apparatus for a fluid
Abstract
A dispensing apparatus is proposed for a fluid having a supply
tank (2) for the fluid which has an outlet (4) which can be
connected to a pressure line (5) for the fluid (F), and having a
rotary pump (3) which has a rotor (31) for conveying the fluid (F)
into the pressure line, with the rotor (31) for the mixing of the
fluid being arranged directly in the outlet (4) of the supply tank
(2).
Inventors: |
Schob, Reto; (Rudolfstetten,
CH) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Levitronix LLC
Waltham
MA
|
Family ID: |
8184289 |
Appl. No.: |
10/309941 |
Filed: |
December 3, 2002 |
Current U.S.
Class: |
417/410.1 |
Current CPC
Class: |
B24B 57/02 20130101;
F04D 13/16 20130101; B24B 37/04 20130101 |
Class at
Publication: |
417/410.1 |
International
Class: |
F04B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2001 |
EP |
01811180.7 |
Claims
1. A dispensing apparatus for a fluid having a supply tank (2) for
the fluid which has an outlet (4) which can be connected to a
pressure line (5) for the fluid (F), and having a rotary pump (3)
which has a rotor (31) for conveying the fluid (F) into the
pressure line, characterised in that the rotor (3 1) for mixing the
fluid (F) is arranged directly in the outlet (4) of the supply tank
(2).
2 A dispensing apparatus in accordance with claim 1, in which the
rotary pump (3) has an inlet (30) whose opening (B) amounts to at
least thirty percent, in particular at least fifty percent, of the
diameter of the rotor (31).
3. A dispensing apparatus in accordance with claim 1 or claim 2,
having a control unit (12) for the rotary pump (3) which adjusts
the forwarding pressure of the rotary pump (3) via the speed of the
rotor (31).
4. A dispensing apparatus in accordance with any one of the
preceding claims, wherein the rotor (3) is provided in a rotor
housing (312) which forms a part of the wall of the dispensing tank
(2).
5. A dispensing apparatus in accordance with any one of the
preceding claims, wherein the rotor (31) is designed and arranged
such that it extends at least in part into the supply tank (2).
6. A dispensing apparatus in accordance with any one of the
preceding claims, wherein the rotor (31) includes a plurality of
vanes (311) which extend into the supply tank (2).
7. A dispensing apparatus in accordance with any one of the
preceding claims, wherein the rotary pump (3) has a stator (32) to
drive the rotor (31), with the rotor (31) being magnetically
mounted in a contact-free manner with respect to the stator
(32).
8. A dispensing apparatus in accordance with any one of the
preceding claims, wherein the rotary pump (3) is designed as a
bearing-free motor and the rotor (31) as an integral rotor.
9. A dispensing apparatus in accordance with any one of the
preceding claims, wherein the rotor (31) is permanently
magnetic.
10. A dispensing apparatus in accordance with any one of the
preceding claims, wherein guide elements (21) are provided in the
supply tank (2).
11. A dispensing apparatus in accordance with any one of the
preceding claims, having a pressure line (5) which extends from an
outlet (41) of the rotary pump (3) up to an inlet (6) of the supply
tank (2) and has at least one removal point (7).
12. A dispensing apparatus in accordance with any one of the
preceding claims, having means (13, 14, 15) for regulating the
level of the supply tank.
13. Use of a dispensing apparatus in accordance with any one of the
preceding claims for the dispensing of suspensions, in particular
of slurry, especially in a CMP process, or for the dispensing of
photoresist.
14. Use of a dispensing apparatus in accordance with any one of
claims 1-12 for the determination of the viscosity of a liquid.
15. Use of a dispensing apparatus in accordance with any one of
claims 1-12 for the checking of properties of a fluid, in
particular for the checking of a mix ratio.
Description
[0001] The invention relates to a dispensing apparatus for a fluid
in accordance with the preamble of independent claim 1 and to the
use of such a dispensing apparatus.
[0002] There is a need in a number of industrial processes, for
example in the manufacture of semi-conductors and chips, to
dispense fluids in a controlled manner via nozzles or similar
apparatuses. Chemical-mechanical polishing processes (CMP) such as
are used in the semi-conductor industry can be named as examples
here. In such processes, a suspension usually known as a slurry and
typically made of very fine solid particles and a liquid is applied
to a rotating wafer and there serves for the polishing or lapping
of the very fine semi-conductor structures. Another example is the
application of photo-resist to the wafer.
[0003] A dispensing apparatus suitable for this and known from the
prior art is illustrated in FIG. 1. The dispensing apparatus 1'
includes a supply tank 2' which is filled with the fluid, for
example slurry. The supply tank 2' has an outlet 4' to which a
pressure line 5' is connected which extends via a recirculation
pump R' up to an inlet 6' at the supply tank 2'. Downstream of the
recirculation pump R', a plurality of discharge points 7' are
provided in the pressure line 5' which lead to nozzles or other
apparatuses--usually known as tools--with which the fluid is
applied to the wafers. Each discharge point 7' is provided with a
valve 8' in order to open the flow connection to the respective
apparatus. If all discharge points 7' are closed, the recirculation
pump R' effects only a circulation of the fluid.
[0004] The desired pressure at which the fluid is transported to
the tools through the pressure line 5' and the open discharge
points 7' can be generated by applying pressure to the fluid in the
supply tank 2'. For this purpose, an inlet 10' is provided at the
supply tank 2' through which a pressure medium can be introduced
into the supply tank via a pressure control valve 11', as is
symbolically represented by the arrow G. Usually a gas, e.g.
nitrogen, is used as the pressure medium with which an overpressure
of, for example 0.5 bar, is maintained in the supply tank 2'.
[0005] Such an apparatus, however, has disadvantages. To generate
the overpressure in the supply tank 2', this must be designed
impermeable to gas, which requires quite an apparatus effort.
Moreover, it is not easily possible to fill new fluid into the
supply tank 2' when the level becomes too low. A change in the
pressure in the supply tank 2' and thus a change in the forwarding
pressure is also complicated and time consuming. It is furthermore
possible for the pressure medium (gas) to penetrate the fluid or
enter into a solution in the fluid, which can result in unwanted
changes in the composition of the fluid. A further problem can
occur in suspensions such as slurries or in fluids which tend to
separation or clumping, because the circulation caused by the
recirculation pump R' is as a rule too low to ensure a fluid
movement in the supply tank 2' which is sufficient for a constant
mixing. Additional measures are therefore frequently necessary to
permanently ensure a sufficient movement or mixing of the fluid in
the supply tank 2'.
[0006] Starting from this prior art, it is therefore an object of
the invention to provide a dispensing apparatus for a fluid which
does not have the said disadvantages. The dispensing apparatus
should allow a sufficient mixing of the fluid and its availability
in a pressure line in a simple manner.
[0007] The dispensing apparatus which satisfies this object is
characterised by the features of independent claim 1.
[0008] In accordance with the invention, a dispensing apparatus for
a fluid is therefore proposed having a supply tank for the fluid
which has an outlet which can be connected to a pressure line for
the fluid and having a rotary pump which has a rotor to convey the
fluid into the pressure line, with the rotor being arranged
directly in the outlet of the supply tank for the mixing of the
fluid.
[0009] The rotary pump thus satisfies two functions: on the one
hand, it conveys the fluid into the pressure line (pump function)
and, on the other hand, the arrangement of the rotor directly in
the outlet of the supply tank ensures a good and constant mixing of
the fluid in the supply tank (stirring function). A precipitation
or deposition of particles in suspensions, a clumping or a phase
separation in the fluid can thus be effectively prevented.
[0010] It is advantageous for the best possible mixing for the
rotary pump to have an inlet whose opening amounts to at least
thirty percent, in particular at least fifty percent, of the
diameter of the rotor.
[0011] A control unit for the rotary pump is preferably provided
which sets the forwarding pressure of the rotary pump via the speed
of the rotor. If the rotary pump is operated in an operating range
with a low efficiency, there is a clear relationship between the
speed of the rotor and the pressure at the outlet of the pump for a
given fluid. This has the big advantage that the pressure at which
the fluid is made available can be set or adjusted easily and in a
very short time. A complex application of pressure to the fluid in
the supply tank is thus no longer necessary.
[0012] With respect to a design which is as simple as possible in
an apparatus aspect, it is advantageous for the rotor to be
provided in a rotor housing which forms part of the wall of the
supply tank.
[0013] The stirring function of the rotor can be positively
influenced when the rotor is designed and arranged such that it
projects at least partly into the supply tank.
[0014] The rotor preferably includes a plurality of vanes which
extend into the supply tank. This can in particular be realised in
that the vanes are oversized, that is much larger, in comparison
with known rotary pumps. The vanes thus also serve, in addition to
generating pressure, as stirring elements which keep the fluid in
the dispensing tank in motion.
[0015] It is also advantageous for the rotary pump to have a stator
for driving the rotor, wherein the rotor is mounted magnetically in
a contact-free manner with respect to the stator. Due to this
measure, no seals are necessary at shaft bearings and the risk of
damage to such seals, for example, by abrasive particles, is
avoided.
[0016] The rotary pump is particularly preferably designed as a
bearing-free motor and the rotor as an integral rotor, because this
represents a very compact and space-saving design.
[0017] In order to further improve the mixing and/or homogenisation
of the fluid in the supply tank, it can be advantageous to provide
guide elements in the supply tank.
[0018] In a preferred use, the dispensing apparatus in accordance
with the invention serves for the dispensing of suspensions, in
particular of slurry, especially in a CMP process, or for the
dispensing of photo-resist.
[0019] Further preferred applications of the dispensing apparatus
in accordance with the invention are the determining of the
viscosity of a liquid and the checking of properties of a fluid, in
particular the checking of the mixing ratio in a fluid which is
composed of a plurality of components.
[0020] Further advantageous measures result from the dependent
claims.
[0021] The invention will be explained in more detail in the
following with reference to embodiments and to the drawing. There
are shown in the schematic drawing:
[0022] FIG. 1: a schematic representation of a known dispensing
apparatus (prior art);
[0023] FIG. 2 a schematic representation of an embodiment of a
dispensing apparatus in accordance with the invention;
[0024] FIG. 3 a variant for a dispensing tank; and
[0025] FIG. 4 a schematic representation of a further embodiment of
a dispensing apparatus in accordance with the invention.
[0026] FIG. 1 shows a dispensing apparatus 1', which represents
prior art and was already explained at the start.
[0027] FIG. 2 shows in a schematic representation an embodiment of
a dispensing apparatus in accordance with the invention which is
designated as a whole with the reference numeral 1. The dispensing
apparatus 1 includes a supply tank 2 for a fluid F which has an
outlet 4. A rotary pump 3 having a rotor 31 is provided in the
outlet 4 and is designed as a centrifugal pump here. The outlet 41
of the rotary pump 3 is connected to a pressure line 5 which
extends from this outlet 41 of the rotary pump 3 via a
pressure-reducing valve 9 up to an inlet 6 of the dispensing tank
2. The pressure line 5 has at least one--here for example
three--discharge points 7 upstream of the pressure line 5 of which
each is connected via a line 71 to an apparatus T for dispensing
the fluid F, for example to a nozzle, or to a tool. A valve 8 is
provided in each line 71 with which the flow connection between the
removal point 7 and the too T can be separately opened or
closed.
[0028] The outlet 4 is arranged at the base of the dispensing tank
2. The opening of the outlet 4--by which its diameter is meant--is
identical to the opening B of the inlet 30 of the rotary pump 3.
This opening B is larger than half the diameter of the rotor
31.
[0029] In the following, reference will be made by way of example
to an application particularly important for practice, namely that
the dispensing apparatus 1 in accordance with the invention is used
in a CMP process (CMP: chemical-mechanical polishing) in the
semi-conductor industry. In these processes, a suspension known as
a slurry of fine solid particles in a liquid is applied to a
rotating wafer and there serves for the lapping or polishing of the
very fine semi-conductor structures. The fluid F in this example is
the suspension known as a slurry. The apparatuses or tools T each
include a nozzle or another means with which the fluid F can be
applied to the wafer.
[0030] By rotary pumps, which are also known as centrifugal pumps,
there are meant all those pump apparatuses which have a rotor 31 or
an impeller by whose rotation an impulse amount is carried out on
the fluid to be conveyed. The term rotary pump includes in
particular centrifugal pumps, axial pumps and side-passage pumps.
The inlet and the outlet are typically in constant flow connection
in a rotary pump. There are therefore, for example, no valves
provided between the pump inlet and outlet 41.
[0031] In accordance with the invention, the rotor 31 for mixing
the fluid F is arranged directly in the outlet of the supply tank
2. In this embodiment, the rotor 31 for mixing the fluid F projects
at least partly into the supply tank 2. The rotary pump 3 thus does
not only serve for the pumping of the fluid F, but also as an
agitator which mixes the fluid F in the supply tank 2. For this
purpose, the rotor 31 has a plurality of vanes 311 which are
designed much larger than with known rotary pumps of comparable
dimensioning. As FIG. 2 and FIG. 3 also show, the vanes 311 extend
into the supply tank 2 and here (when the rotor 3 is rotating)
provide for a circulation of the fluid as is indicated by the
arrows Z.
[0032] The representation of the vanes 311 in FIG. 2 and FIG. 3 is
naturally only to be understood as an example. The vanes can have
still further necks or larger surfaces or other suitable means in
order to positively influence the stirring function.
[0033] The rotor 31 is arranged in a rotor housing 312 which forms
a part of the wall of the supply tank 2. The rotor housing 312 can
be an integral component of the supply tank 2 or be secured to this
as a separate part.
[0034] The rotary pump 3 further includes a stator 32 having a
stator winding 322 in order to electrically drive the rotor 31.
Furthermore, a control unit 12 is provided which controls and
regulates the rotary pump 3. The stator 32 surrounds the rotor
housing 312. The stator 32 is preferably designed as the stator of
a so-called temple motor. This means (see FIG. 2 and FIG. 3) that
the stator 32 has a plurality of stator teeth connected by a return
yoke, with each stator tooth being formed in an L shape with a
shorter and a longer limb. The longer limb in each case extends
parallel to the axis of rotation of the rotor and the shorter limb
extends radially inwardly towards the axis of rotation. The longer
limbs carry the stator winding 322.
[0035] In particular for such fluids which include solid particles
or which are of high purity, the rotary pump 3 preferably has a
completely magnetically mounted rotor 31, that is the rotor 31 is
magnetically mounted in a contact-free manner with respect to the
stator 32. The absence of mechanical bearings for the rotor 31 has
a plurality of advantages. For instance, the problem is avoided
that abrasive particles can damage mechanical bearings. There is
furthermore no risk of contamination of the fluid by lubricants or
bearing abrasion. Sealing problems are also avoided.
[0036] It is particularly simple from an apparatus aspect and
energetically favourable for the rotor 31 to be permanently
magnetic. For this purpose, the rotor 31 includes a permanent
magnet, for example a permanently magnetic ring 313. This ring 313
is arranged around a central bore 314 which extends along the
desired axis of rotation of the rotor 31 and through said rotor.
The magnetisation of the ring 313 is indicated by the arrows
(without reference numerals) at its interior.
[0037] A particularly preferred rotary pump is disclosed, for
example, in EP-A-0 819 330 or U.S. Pat. No. 6,100,618. This rotary
pump has a so-called integral rotor and is designed as a
bearing-free motor. The term integral motor is to be understood
such that the pump rotor and the rotor of the motor driving the
pump are identical. The rotor 31 operates both as a rotor of the
motor drive and as a rotor of the pump. The term bearing-free motor
is to be understood such that the rotor is mounted in a completely
magnetic manner, with no separate magnetic bearings being provided.
The stator 32 is both the stator of the electrical drive and the
stator of the magnetic bearing. For this purpose, the stator
winding 322 includes a drive winding of the polar pair number p+1.
It is thus possible both to drive the rotor 31 and to mount it
magnetically in the stator in a completely contact-free manner.
Reference is made to the documents already cited with respect to
further details of such a rotary pump.
[0038] During operation, the stator winding 322 controlled by the
control unit 12 generates a drive rotary field which applies a
torque onto the rotor 31 and sets this into motion. Furthermore,
the control winding of the stator winding 322 generates a magnetic
control field with which the position of the rotor 31 can be
regulated with respect to the stator 32.
[0039] The fluid F is sucked through the inlet 30 of the rotary
pump 3 and conveyed through the outlet 41 into the pressure line 5
by the rotation of the rotor 31 and the fluid is available there
under the forwarding pressure, for example 0.5 bar up to 1 bar. A
small part of the fluid F flows through the bore 314 (as the double
arrow at the lower end of the bore 314 in accordance with the
illustration indicates in FIGS. 2 and 3) and thus ensures that the
rotor 31 is relieved with respect to the axial thrust.
[0040] Depending on which of the valves 8 is or are opened, the
fluid F reaches the individual tools T through the lines 71 from
the pressure line 5. The rest of the fluid F, which is not
dispensed to the tools T, enters back into the supply tank 2 via
the pressure reducing valve 9 and the inlet 6, whereby a
recirculation of the fluid F and thus a mixing in the supply tank 2
is realised.
[0041] In addition to this pump function, the rotary pump 3 also
directly produces a mixing of the fluid F in the supply tank 2,
because the vanes 311 projecting into the supply tank 2 act as
stirring tools and mix the fluid 2 in the supply tank 2.
[0042] Since in this embodiment of the dispensing apparatus 1 in
accordance with the invention (FIG. 2), unlike known dispensing
apparatuses (FIG. 1), the forwarding pressure is generated by the
rotary pump 3 and not by applying pressure to the fluid by a gas G,
a much simpler design results. Moreover, the supply tank 2 does not
have to be designed impermeable to gas, which makes a simpler
refilling possible. In addition, there is no risk that the gas G
service as a pressure medium will contaminate the fluid F in the
supply tank 2.
[0043] The control unit 12 quite particularly preferably adjusts
the forwarding pressure of the rotary pump 3 via the speed of the
rotor 31, which will be explained in the following.
[0044] In European patent application No. 01810790.4 of the same
applicant, it is proposed to operate a rotary pump at an efficiency
which is much smaller than the maximum efficiency of the rotary
pump, for example at the most 20 percent of the maximum
efficiency.
[0045] The term efficiency is to be understood as the hydraulic
efficiency of the rotary pump, that is the ratio of hydraulic
performance (conveying performance) of the pump and mechanical
performance for the drive of the rotor (without any friction losses
which may be present in bearings or similar).
[0046] In European patent application No. 01810790.4, whose
contents are herewith incorporated into the present application, it
is explained that there is a clear relationship for such operating
ranges of the rotary pump 3, in which the efficiency is clearly
below the maximum efficiency, between the speed of the pump rotor
and the forwarding pressure (delivery head) and also between the
speed and the volume flow (flow). In these operating ranges, the
forwarding pressure is approximately proportional to the square of
the speed of the rotor. This opens up the possibility of setting or
regulating the forwarding pressure directly and without an
additional pressure measurement via the speed of the rotor 31.
[0047] The exact mathematical relationship between the forwarding
pressure and the speed, which naturally also depends on the
properties of the fluid F, does not need to be known. It is only
important that this relationship is biunique for such operating
ranges in which the rotary pump 3 operates at a very low
efficiency. For example, calibration measurements are carried out
in advance in order to determine the pressure/speed curve. This
curve can then be stored in a memory of the control unit 12 as a
mathematical function, e.g. a polynomial approximation, or as an
electronic look-up table. During the operation of the rotary pump
3, the associated speed for the desired forwarding pressure is then
looked up in the look-up table. The desired forwarding pressure can
then be realised by setting the corresponding speed.
[0048] The biunique relationship between the speed and the
forwarding pressure or between the speed and the volume flow
naturally also depends on the fluid F to be conveyed, in particular
also on its viscosity. In the already cited European application
No. 01810790.4, it is therefore proposed to use the biunique
relationship which exists in operating ranges with very low degrees
of efficiency to determine the viscosity or the dynamic viscosity
of the fluid. Reference is made in this respect to the explanations
in this European patent application. In basically the same manner,
the dispensing apparatus 1 in accordance with the invention can
also be used in order to determine or monitor the properties of the
fluid F such as its viscosity or also its density or other
parameters which can be derived therefrom. The possibility is thus
opened up of additionally carrying out a quality control of the
fluid online or inline with the dispenser apparatus 1 in accordance
with the invention.
[0049] The determination of the viscosity of the fluid F takes
place by means of the motor current with which the rotation of the
rotor 31 is driven. The motor current is directly a measure of the
torque with which the rotor 31 is driven. In particular in the case
of the preferred aspect of the rotary pump as a bearing-free motor,
no mechanical bearing friction is present due to the magnetic
mounting of the rotor so that the torque with which the rotor is
driven coincides in very good approximation with the torque
transmitted to the fluid.
[0050] Due to the very low efficiency with which the rotary pump 1
is operated in the operating state described here, practically the
whole torque and thus the mechanical performance which the impeller
or the rotor 31 transmits to the fluid is converted into liquid
friction losses. The torque of the rotor 1 is thus directly a
measure for the viscosity, more precisely for the dynamic viscosity
of the fluid, because the mechanical performance of the rotor 31 is
almost completely converted into friction losses of the fluid.
[0051] As already mentioned, the torque which the rotor transmits
onto the liquid substantially, that is except for mechanical
friction losses, corresponds to the drive torque with which the
rotor is driven. This applies in particular to magnetically mounted
rotors. The drive torque is again given by the motor current which
drives the rotor. The motor current is understood to be the
torque-forming portion of the current, also known as the armature
current, in the electrical drive. The armature current is in
particular a very good measure for the torque with which the rotor
is driven in field-oriented three-phase motors.
[0052] There is thus a direct connection between the motor current
with which the pump is driven and the viscosity of the fluid in the
operating range in which the rotary pump 3 only operates at a
fraction of its maximum efficiency. The dynamic viscosity of the
fluid to be conveyed can thus be determined in a simple manner and
online by a measurement of the motor current.
[0053] In basically the same manner, other properties of the fluid,
for example its density or the mixing ratio of two components of
the fluid F can also be determined when the rotary pump 3 is
operated in such operating states in which it has a very low
efficiency.
[0054] Particularly with regard to the quality monitoring or the
determination of parameters of the fluid F, it can be advantageous
for a temperature sensor 315 (see FIG. 3) to be provided, for
example at the outside of the rotor housing 312, with which the
temperature of the fluid F can be detected.
[0055] In such operating regions in which the rotary pump 3 only
operates at a fraction of its maximum efficiency, the forwarding
pressure at which the fluid F is made available in the pressure
line 5 can therefore be set and regulated directly by the control
unit 12 via the speed of the rotor 31. An extremely fast electrical
or electronic adjustment of the forwarding pressure can thus be
realised. The forwarding pressure can be regulated, for example, in
time intervals of less than 100 milliseconds.
[0056] FIG. 4 illustrates a further embodiment which is in
particular suitable for such applications in which the viscosity of
the fluid or other of its properties are to be determined. In the
following, only the differences with respect to the embodiment in
accordance with FIG. 2 will be dealt with. The reference numerals
have the meaning already introduced.
[0057] In this embodiment, means are provided to regulate the level
of the dispensing tank 2. These means include a tank 13, a
connection line 14, which connects the tank 13 to the dispensing
tank 2, and a constant gas volume 15, which is provided in the
dispensing tank 2. This gas volume 15 can naturally also be zero.
The purpose of these means 13, 14, 15 is to keep the level in the
dispensing tank 2 constant. The tank 13 has a variable level; it
can also be refilled. If now fluid F is taken out of the dispensing
tank 2 by means of the rotary pump 3, then fluid flows after it
from the tank 13 through the connection line 14. In this way, a
constant level FS can be regulated in the dispensing tank 2.
[0058] The level regulation in the dispensing tank 2 is in
particular advantageous when the viscosity or other properties of
the fluid F are to be determined or monitored with the dispensing
apparatus 1 of the invention. It is namely ensured by the constant
level FS in the supply tank 2 that always just as much fluid F or
liquid (that is the same amount) is subjected to stirring power in
the dispensing tank 2. This stirring power is therefore
particularly a good measure for the specific liquid friction and
thus represents an exact measure for the viscosity. A much more
precise determination of the viscosity or other properties of the
fluid is thus made possible.
[0059] It is furthermore possible--as is indicated in FIG. 4--that
the supply tank 2 is fed with two--for example,
different--components such as liquids and/or gases, namely with a
first component which flows from the tank 13 through the connection
line 14 into the supply tank, and with a second component which
flows through a further line 16 from a further tank (not
shown).
[0060] The supply tank 2 then serves as a mixing tank in which the
two components are mixed to form the fluid. In basically the same
manner as was explained for the viscosity, the mixing ratio of the
two components can be monitored or checked by the dispensing
apparatus 1 of the invention.
[0061] Furthermore, FIG. 4 shows another variant for the aspect and
the arrangement of the rotor 31. Here, the rotor 31 is designed and
arranged such that its vanes 311 do not extend into the dispensing
tank 2. The opening B or the diameter B of the inlet 30 here also
amounts to more than fifty percent of the diameter of the rotor 31
in order to achieve a good mixing.
[0062] FIG. 3 shows another variant for the supply tank 2. The
reference symbols have the same meaning which was explained with
respect to FIG. 2. In this variant, the rotor housing 312 at the
base of the supply tank 2 and the vanes 311 have been somewhat
modified. Moreover, static guide elements 21 are provided in the
supply tank 2. These have the effect of guiding the fluid currents
generated by the rotary pump 3 further upwards (in accordance with
the illustration with respect to FIG. 3), as is indicated by the
arrows with the reference symbol Z. In particular with larger
supply tanks 2, it can be ensured by such a measure that the
constant mixing of the fluid F covers the total supply tank 2 and
does not remain limited locally to the vicinity of the rotor 3.
[0063] The dispensing apparatus 1 in accordance with the invention
is advantageous in particular for such fluids F which incline to
clumping, phase separation, precipitation or deposition of
particles, for example for suspensions, especially for slurry
solutions. The fluid F located in the supply tank 2 remains in
movement due to the recirculation and the stirring effect produced
directly by the rotor 31 so that a constant mixing takes place.
[0064] The dispensing apparatus 1 in accordance with the invention
is naturally not limited to the application described here, namely
to the conveying of a slurry suspension or to CMP processes. It is
also generally suitable, among other things, for the conveying of
suspensions, emulsions, paints, foodstuffs (e.g. juices or
concentrates).
[0065] A particular advantage is the combination of pump function
and stirring function, with the forwarding pressure being able to
be adjusted and regulated in a very simple manner and extremely
rapidly in an electronic manner.
* * * * *