U.S. patent application number 10/692751 was filed with the patent office on 2004-05-13 for homogenizer.
Invention is credited to Mizobuchi, Shotaro, Tsunofuri, Masahiro, Uesugi, Masakazu.
Application Number | 20040090862 10/692751 |
Document ID | / |
Family ID | 32211968 |
Filed Date | 2004-05-13 |
United States Patent
Application |
20040090862 |
Kind Code |
A1 |
Uesugi, Masakazu ; et
al. |
May 13, 2004 |
Homogenizer
Abstract
A homogenizer is disclosed, which can produce an emulsion with a
grain diameter as extremely fine as approximately 1 .mu.m without
using large-scale equipment such as a high-pressure pump, and in
which a grain diameter distribution of the produced emulsion
exhibits sharp characteristics in the vicinity of a target grain
diameter. A fixed portion and a disc-shaped agitation rotor are
arranged in an opposing manner through a predetermined clearance to
constitute a thrust hydrodynamic bearing, and while supporting a
rotation of the agitation rotor with respect to the fixed portion
by the thrust hydrodynamic bearing, a plurality of mutually
incompatible raw liquids A and B are introduced into the bearing
clearance to be mixed and agitated in the bearing clearance in
accordance with the rotation of the agitation rotor.
Inventors: |
Uesugi, Masakazu;
(Yamanashi-ken, JP) ; Tsunofuri, Masahiro;
(Yamanashi-ken, JP) ; Mizobuchi, Shotaro;
(Yamanashi-ken, JP) |
Correspondence
Address: |
RADER FISHMAN & GRAUER PLLC
LION BUILDING
1233 20TH STREET N.W., SUITE 501
WASHINGTON
DC
20036
US
|
Family ID: |
32211968 |
Appl. No.: |
10/692751 |
Filed: |
October 27, 2003 |
Current U.S.
Class: |
366/331 |
Current CPC
Class: |
B01F 23/41 20220101;
B01F 27/115 20220101; B01F 2035/352 20220101; F16C 17/045 20130101;
B01F 27/2712 20220101; B01F 2215/0427 20130101; F16C 17/04
20130101; B01F 35/30 20220101; F16C 33/107 20130101; B01F 27/2714
20220101; B01F 2215/0431 20130101 |
Class at
Publication: |
366/331 |
International
Class: |
B01F 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2002 |
JP |
2002-326506 |
Claims
What is claimed is:
1. A homogenizer comprising a thrust hydrodynamic bearing
comprising: a fixed portion; and a disc-shaped agitation rotor that
are opposingly arranged through a predetermined bearing clearance,
the thrust hydrodynamic bearing supporting a rotation of the
agitation rotor with respect to the fixed portion, wherein a
plurality of mutually incompatible raw liquids are introduced into
the bearing clearance to be mixed and agitated in the bearing
clearance by a rotation of the agitation rotor.
2. A homogenizer according to claim 1, further comprising a
plurality of grooves arranged radially or spirally along a
circumferential direction on one surface of the agitation rotor
which is opposed to the fixed portion.
3. A homogenizer according to claim 2, wherein the one surface of
the agitation rotor which is opposed to the fixed portion is
divided into three regions of a center circle region, an
intermediate ring region, and an outer ring region, the homogenizer
further comprising: agitation grooves; spiral-shaped pumping
grooves; and introduction ports for the plurality of raw liquids,
the agitation grooves being formed radially on any one of the three
regions and extending in a diameter direction, the pumping grooves
being formed on the other two of the three regions for causing the
plurality of raw liquids in the bearing clearance to flow into the
agitation grooves by the rotation of the rotor, the introduction
ports being formed in the fixed portion at positions opposed to the
pumping grooves of the agitation rotor.
4. A homogenizer according to any one of claims 1 to 3, further
comprising a pressure release port, the pressure release port
communicating with the bearing clearance and connected with a
relief valve for adjusting a pressure in the bearing clearance.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a homogenizer for use, for
example, when mechanically mixing and agitating a plurality of
mutually incompatible liquids to atomize, emulsify, and disperse
the liquids. Particularly, the present invention relates to an
improvement for obtaining a sharp grain diameter distribution in
conformity with a target grain diameter when atomizing the
liquids.
[0003] 2. Description of the Related Art
[0004] In recent years, NO.sub.x and suspended particulate matter
(SPM) such as soot, which are contained in exhaust gas of a diesel
engine, have been a great social problem from a viewpoint of an
environment load. As measures for solving such a problem relating
to the exhaust gas, a diesel engine using water emulsion fuel has
been proposed and brought to a commercial stage. This water
emulsion fuel is fuel prepared by mixing and emulsifying light oil
and water, and it has been reported that amounts of SPM and
NO.sub.x emissions are significantly lowered in the diesel engine
using the fuel.
[0005] This water emulsion fuel is, for example, one prepared in
such a manner that oil and water are mixed at a ratio of 1:1,
followed by atomization of the mixed matter to a grain diameter of
approximately 1 .mu.m, and emulsification thereof. In order to
ensure stable engine combustion, it is important for a grain
diameter distribution to concentrate on a narrow range centered on
1 .mu.m without being expanded to a great extent.
[0006] Conventionally, as an apparatus for mixing and agitating two
mutually incompatible liquids like water and oil, various types of
homogenizers are publicly known, which are frequently used in
production equipment for foods, chemical products, or the like,
experimental plants, etc. Among these homogenizers, a so-called
rotor/stator type homogenizer, a high-pressure homogenizer, and the
like are known as homogenizers suitable for producing
emulsions.
[0007] As the rotor/stator type homogenizer, one whose brand name
is "Megatron (http://www.kinematica.ch/English/)", which is made by
KINEMATICA AG (Switzerland), one whose brand name is "Clearmix
(http:www.organo.co.jp/prod/clearmix/)", which is made by ORGANO
CORPORATION, and the like, are known. Each of these rotor/stator
type homogenizers includes a cylindrical stator fixed inside an
agitation chamber, and a rotor which is accommodated in a hollow of
the stator and imparted with a predetermined number of revolutions
by a motor, the stator and rotor having a plurality of radially
formed flow passages. After being mixed, the two mutually
incompatible liquids are supplied to a hollow of the rotor by a
pump. When the rotor starts to rotate in a state where these
liquids are being supplied, a centrifugal force is applied to the
liquids, which are then ejected from the radial flow passages
formed in the rotor to enter a clearance between the rotor and the
stator, further entering radial flow passages of the stator. The
stator does not rotate but remains stationary, so that when the
rotor starts to rotate, a vortex flow is generated in the liquids
existing in the radial flow passages of the rotor and the stator.
Furthermore, a shearing force in accordance with a rotational speed
of the rotor is applied to the liquids having entered the clearance
between the rotor and the stator. By means of energy of the vortex
flow and shearing force, the two liquids are homogenized and
eventually discharged as an emulsion to the outside through the
radial flow passages formed in the stator.
[0008] In order to homogenize more efficiently, in other words,
atomize the two liquids in this rotor/stator type homogenizer, it
is important to apply a great shearing force to the liquids
introduced into the clearance between the rotor and the stator. For
this purpose, it is important to set the clearance defined between
the inner peripheral surface of the stator and the outer peripheral
surface of the rotor to be small. However, in practice, the
clearance between the stator and the rotor cannot be set very
small, and thus the rotor/stator type homogenizer is not suitable
for producing an extremely fine grained emulsion of which grain
diameter is no more than 1 .mu.m. Meanwhile, in the case of
throwing extremely large energy to the homogenizer by increasing
the number of revolutions of the rotor or in other ways, though a
production of the emulsion with the fine grain diameter can be
expected, the produced emulsion has disadvantages in that the grain
diameter distribution thereof does not exhibit sharp
characteristics and that the grain diameter of the emulsion is
undesirably distributed in a wide range.
[0009] Meanwhile, as the latter high-pressure homogenizer, for
example, one whose brand name is "Nanomizer," which is made by
Nanomizer Corporation, is known. This high-pressure homogenizer
includes a generator in which capillaries having a hole diameter of
approximately 0.25 mm are formed, and a high-pressure pump which
fills, with pressure, the capillaries of the generator with a
liquid. The high-pressure homogenizer is constructed in such a
manner that two liquids to be made into an emulsion are mixed
together and then are passed through the capillaries of the
generator, whereby energy of a shock wave and cavitation is applied
to the liquids in the capillaries, and an emulsion with a fine
grain diameter is obtained due to the energy. This high-pressure
homogenizer has an advantage in that an emulsion with a smaller
grain diameter can be obtained in comparison with the rotor/stator
type homogenizer described above because an amount of the energy
thrown to the liquids per unit area is large. However, the
high-pressure homogenizer has a problem in that there is an upper
limit (approximately 500 cps) to the viscosity of the liquids to be
atomized, and that types of liquids which can be processed by the
high-pressure homogenizer are limited. Moreover, the high-pressure
homogenizer has a problem in that an amount of the liquids, which
can be processed per unit time, is extremely small because the
liquids are passed through the capillaries with an extremely small
inner diameter, and that, in order to increase a throughput, it is
necessary to raise pressure generated by the above-described
high-pressure pump, leading to undesirable enlargement of pump
equipment in scale. Furthermore, though the high-pressure
homogenizer can produce the emulsion with the fine grain diameter
of approximately 1 .mu.m, a grain diameter distribution of the
produced emulsion has a width of approximately 0.5 .mu.m with the
fine grain diameter of 1 .mu.m as the center. Thus, it cannot be
said that the grain diameter distribution exhibits sharp
characteristics.
SUMMARY OF THE INVENTION
[0010] The present invention has been made in view of the above
problems, and it is therefore an object of the invention to provide
a homogenizer which can produce an emulsion with a grain diameter
as extremely fine as approximately 1 .mu.m without using
large-scale equipment such as a high-pressure pump, in which a
grain diameter distribution of the produced emulsion exhibits sharp
characteristics in the vicinity of a target grain diameter.
[0011] In order to attain the above object, the homogenizer of the
present invention is one utilizing the construction of a publicly
known thrust hydrodynamic bearing. The thrust hydrodynamic bearing
is one in which a fixed portion and a disc-shaped thrust plate are
arranged to be opposed to each other through a bearing clearance
of, for example, approximately 3 to 10 .mu.m, and a lubricating
fluid such as water and oil is introduced into such a bearing
clearance. The thrust hydrodynamic bearing is constructed such that
the lubricating fluid present in the bearing clearance is
pressurized in accordance with a rotation of the thrust plate,
thereby forming a high-pressure fluid lubricating film between the
fixed portion and the rotating thrust plate. The thrust plate comes
into a floating state with respect to the fixed portion by means of
this fluid lubricating film, and the rotation thereof is supported
in this floating state as it is. In this thrust hydrodynamic
bearing, when the thrust plate rotates, a shearing force is applied
between the lubricating fluid and the thrust plate, and the
lubricating fluid is pressurized by the shearing force while being
taken around a circumferential direction of the thrust plate, and
thus the above-described fluid lubricating film is formed. Hence,
in accordance with the rotation of the thrust plate, the shearing
force is applied to the lubricating fluid present in the bearing
clearance, and energy imparted to the lubricating fluid by the
application of this shearing force can be freely adjusted by
changing a rotational speed of the thrust plate. Moreover, with
regard to the rotational speed, it is possible to impart the thrust
plate with several tens of thousands of revolutions per minute
because the thrust plate is kept in a non-contact state with
respect to the fixed portion. Furthermore, as described above, it
is possible to rotate the thrust plate at high speed in the state
where the bearing clearance of several micrometers is maintained in
the thrust hydrodynamic bearing.
[0012] From the above viewpoints, in the invention of this
application, constructed is a homogenizer for mixing and agitating
a plurality of mutually incompatible raw liquids that are present
in a bearing clearance of a thrust hydrodynamic bearing in
accordance with a rotation of an agitation rotor, in which the
plurality of raw liquids are introduced into the bearing clearance
and the thrust plate is used to serve as the agitation rotor.
[0013] According to the homogenizer as described above of the
present invention, the bearing clearance of the thrust hydrodynamic
bearing is as extremely small as several micrometers. Accordingly,
when the agitation rotor rotates, an extremely large shearing force
is applied to the raw liquids, the raw liquids are atomized by
means of energy imparted thereto by the shearing force, and the
plurality of mutually incompatible liquids can be made into an
emulsion. Moreover, when the agitation rotor is regulated in its
movement in an axial direction, it is possible to maintain the
bearing clearance of the thrust hydrodynamic bearing constant, for
example, at a size of 3 .mu.m or less. Therefore, it also becomes
possible to stably produce an emulsion with a grain diameter of 1
.mu.m or less. Furthermore, the homogenizer to which the structure
of the thrust hydrodynamic bearing is applied in such a manner can
produce the emulsion irrespective of the viscosity of the raw
liquids, and accordingly, it is possible to adapt the homogenizer
to a wide variety of applications. In addition, the homogenizer can
be constructed to be extremely small because accessory equipment
such as a high-pressure pump is not required, and for example, it
also becomes possible to attach the homogenizer as a homogenizer in
line with a variety of devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] In the accompanying drawings:
[0015] FIG. 1 is a cross-sectional view showing a basic
construction of a homogenizer of the present invention;
[0016] FIG. 2 is a plan view showing agitation grooves formed in an
agitation rotor shown in FIG. 1;
[0017] FIG. 3 is a cross-sectional view showing a first embodiment
of a homogenizer to which the present invention is applied;
[0018] FIG. 4 is a view showing pressurization grooves, pumping
groves, and agitation grooves, which are formed on a surface of an
agitation rotor according to the first embodiment;
[0019] FIG. 5 is a cross-sectional view showing a second embodiment
of the homogenizer to which the present invention is applied;
and
[0020] FIG. 6 is a view showing pressurization grooves, pumping
groves, and agitation grooves, which are formed on a surface of an
agitation rotor according to the second embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] A rotor/stator type homogenizer of the present invention
will be described below in detail based on the accompanying
drawings.
[0022] FIG. 1 is a view showing a basic construction of the
homogenizer of the present invention. As shown in this drawing, the
homogenizer of the present invention basically includes a fixed
portion 1, and a disc-shaped agitation rotor 2 arranged to be
opposed to the fixed portion 1, in which a rotation in one
direction is imparted to the agitation rotor 2 by an unillustrated
motor. The agitation rotor 2 and the fixed portion 1 are opposed to
each other, for example, through a bearing clearance of
approximately 5 .mu.m, and they together constitute a thrust
hydrodynamic bearing 3. Both of the agitation rotor 2 and the fixed
portion 1 are formed of a ceramic material and provided with high
abrasion resistance to a high-pressure fluid formed in the bearing
clearance. In addition, introduction ports 4 which communicate with
the bearing clearance are formed in the fixed portion 1, and two
mutually incompatible raw liquids A and Bare introduced from the
introduction ports 4 to the bearing clearance in a premixed
state.
[0023] As shown in FIG. 2, spiral-shaped agitation grooves 5 are
defined on one surface of the agitation rotor 2 which is opposed to
the fixed portion 1. Note that FIG. 2 is a plan view and regions of
the agitation grooves 5 are indicated by dots because it is
difficult to discriminate between regions in which the agitation
grooves 5 are defined and other regions. These agitation grooves 5
are formed to have a depth of approximately 5 to 50 .mu.m, and
exert a shearing force to the raw liquids A and B introduced into
the bearing clearance from the introduction ports 4 in accordance
with a rotation of the agitation rotor 2, to mix and agitate the
raw liquids A and B while applying pressure thereto. In addition, a
winding direction of the agitation grooves 5 formed spirally is a
direction of pressuring the raw liquids A and B present in the
bearing clearance from the inside to the outside in a radius
direction with respect to a rotating direction of the agitation
rotor 2, which is indicated by an arrow in FIG. 2. In view of the
above, the introduction ports 4 are defined in the vicinity of a
rotation center of the agitation rotor 2 (positions corresponding
to the introduction ports 4 on the agitation rotor 2 are shown by
broken lines in FIG. 2). Moreover, when the agitation rotor 2
rotates, the raw liquids A and B are naturally aspirated from the
introduction ports 4 to the bearing clearance, and a flow directed
from the inner diameter side to the outer diameter side in the
radius direction is formed in the bearing clearance.
[0024] With the above construction, when the agitation rotor 2
rotates, the raw liquids A and B present in the bearing clearance
are pressurized by the agitation grooves 5, and a high-pressure
fluid lubricating film containing the raw liquids A and B as the
lubricating fluid is formed in the bearing clearance described
above. Thus, the agitation rotor 2 comes into a floating state with
respect to the fixed portion 1, with its rotation being supported
in a non-contact manner with respect to the fixed portion 1. As
described above, the agitation rotor 2 rotates while maintaining
the non-contact state with respect to the fixed portion 1, and
accordingly, rotational resistance is hardly applied to the
agitation rotor 2, except a viscous drag of the lubricating fluid
present in the bearing clearance. Therefore, it is possible to
rotate the agitation rotor 2 at high speed of several tens of
thousands of revolutions per minute. However, as the rotational
speed of the agitation rotor 2 is increased, a correspondingly
larger pressure is generated in the bearing clearance. Accordingly,
in order to maintain the constant bearing clearance between the
agitation rotor 2 and the fixed portion 1 against this pressure, it
is necessary to apply an external force F to the agitation rotor 2
in a rotation axis direction thereof and to balance this external
force F with the pressure of the fluid lubricating film.
[0025] Then, when the agitation rotor 2 rotates at the high speed
as described above, a large shearing force is applied to the raw
liquids A and B aspirated from the introduction ports 4 into the
bearing clearance. By means of the energy of this shearing force,
the raw liquids A and B are atomized while flowing in the bearing
clearance. Finally, the raw liquids A and B are made into an
emulsion and discharged from an outer circumferential edge of the
agitation rotor 2 to the outside of the bearing clearance. In this
case, it is possible to control the grain diameter of the emulsion
by adjusting the size of the bearing clearance between the
agitation rotor 2 and the fixed portion 1. If the bearing clearance
is set at approximately 3 .mu.m, an emulsion with a grain diameter
of 1 .mu.m or less can be obtained. Moreover, an increase in the
rotational speed of the agitation rotor 2 enables the amount of
energy thrown for the atomization to be increased. Hence, it is
possible to adjust the grain diameter of the emulsion also by such
an adjustment of the rotational speed.
[0026] Hence, according to the homogenizer of the present
invention, the raw liquids A and B, which are mutually incompatible
like water and oil, can be mixed to prepare the emulsion. Moreover,
grain diameters of grain drops constituting the emulsion can be
freely adjusted to a target size, and an emulsion having a sharp
grain diameter distribution can be obtained. Moreover, when
rotation of the agitation rotor 2 is started, the raw liquids A and
B are naturally aspirated to the bearing clearance, and
accordingly, a pump which supplies the raw liquids to the
homogenizer is not required, thus making it possible to construct
an extremely simple and compact homogenizer.
[0027] FIG. 3 shows a first embodiment of a homogenizer to which
the present invention is concretely applied. This homogenizer
includes an agitation rotor 10 and a housing 20 which accommodates
this agitation rotor 10. Furthermore, the housing 20 includes a
cylindrical motor housing 22 accommodating a motor 21, a
donut-shaped bearing ring 23 fixed to an inner circumferential
surface of the motor housing 22, a fixed plate (fixed portion) 24
which constitutes a thrust hydrodynamic bearing together with the
agitation rotor 10, a spacer ring 25 which adjusts an interval
between the bearing ring 23 and the fixed plate 24, and an end
plate 26 which closes an open end of the motor housing 22.
[0028] The agitation rotor 10 includes a journal portion 11 as a
main rotation shaft, and a disc-shaped flange portion 12 which
overhangs from one end of the journal portion 11. The agitation
rotor 10 has a longitudinal cross section formed in to an
approximately T shape along a center of a rotation axis, and is
accommodated in the housing 20 in a state where the journal portion
11 is penetrated through the bearing ring 23. On a tip of the
journal portion 11, a motor rotor 21a is fixed, which constitutes
the motor 21 together with a motor stator 21b fixed to the motor
housing 22. A rotation is imparted to the agitation rotor 10 by the
motor 21.
[0029] A bearing clearance of approximately 5 .mu.m is formed
between the outer circumferential surface of the journal portion 11
and the inner circumferential surface of the bearing ring 23. The
bearing ring 23 and the journal portion 11 of the agitation rotor
10 constitute a radial hydrodynamic bearing 27. A supply port 23a
which communicates with the outside of the housing 20 is opened in
the bearing ring 23 in order to introduce a lubricating fluid into
the bearing clearance of the radial hydrodynamic bearing 27. Here,
as the lubricating fluid for the radial hydrodynamic bearing 27,
liquids such as water and oil can be selected as appropriate. On
the outer circumferential surface of the journal portion 11 of the
agitation rotor 10, pressurization grooves 30 with a depth of
approximately 10 to 50 .mu.m, which are repeatedly continuous in
the circumferential direction, are formed at positions opposed to
the inner circumferential surface of the bearing ring 23. When the
agitation rotor 10 rotates, the pressurization grooves 30
pressurize the lubricating fluid present in the bearing clearance
to form a high-pressure fluid lubricating film in the clearance
between the journal portion 11 and the bearing ring 23. Thus, a
rotation of the agitation rotor 10 is supported in a state where
the journal portion 11 is centered on the center of the bearing
ring 23.
[0030] Meanwhile, the spacer ring 25 interposed between the bearing
ring 23 and the fixed plate 24 is formed such that a thickness
thereof in an axial direction is slightly larger than a thickness
of the flange portion 12 of the agitation rotor 10 in the axial
direction. When the flange portion 12 is accommodated between the
bearing ring 23 and the fixed plate 24, the bearing clearances are
defined on both sides of the flange portion 12, and the both front
and back surfaces of the flange portion 12 constitute a pair of
thrust hydrodynamic bearings 31 and 32, together with the bearing
ring 23 and the fixed plate 24. The pair of thrust hydrodynamic
bearings 31 and 32 formed on the both surfaces of the flange
portion 12 regulate a movement of the agitation rotor 10 in the
rotation axis direction in the housing 20.
[0031] In the thrust hydrodynamic bearing 31 located on the
backside of the flange portion 12, spiral pressurization grooves 33
with a depth of approximately 10 to 50 .mu.m, which are repeatedly
continuous in the circumferential direction, are formed on the back
of the flange portion 12. The bearing clearance of this thrust
hydrodynamic bearing 31 communicates with the bearing clearance of
the radial hydrodynamic bearing 27. The lubricating fluid supplied
from the supply port 23a to the bearing clearance of the radial
hydrodynamic bearing 27 flows into the bearing clearance of the
thrust hydrodynamic bearing 31. Here also, a high-pressure fluid
lubricating film is formed in accordance with the rotation of the
agitation rotor 10. Moreover, the lubricating fluid pressurized in
the bearing clearance of the thrust hydrodynamic bearing 31 is
discharged from the outer circumferential edge of the flange
portion 12 of the agitation rotor 10 to the outside of the bearing
clearance. Then, the lubricating fluid is discharged from a
discharge port 25a defined in the spacer ring 25 to the outside of
the housing 20.
[0032] Meanwhile, in the thrust hydrodynamic bearing 32 located on
the front surface side of the flange portion 12, spiral
pressurization grooves 34 with a depth of approximately 10 to 50
.mu.m, which are repeatedly continuous in the circumferential
direction, are also formed on the surface of the flange portion 12.
FIG. 4 is a view showing the surface of the agitation rotor opposed
to the fixed plate. As shown in this drawing, the pressurization
grooves 34 are spirally extended from the rotation center of the
agitation rotor, and an introduction port 24a for the raw liquid A
is opened so as to correspond to the center of the pressurization
grooves 34. When the agitation rotor 10 rotates, the pressurization
grooves 34 aspirate the raw liquid A from the introduction port 24a
into the bearing clearance, and act to pressurize the raw liquid A
toward the outer circumferential edge of the flange portion 12.
Specifically, in the thrust hydrodynamic bearing 32, it is the raw
liquid A that serves as the lubricating fluid. In addition, the
pressurization grooves 34 also function as pumping grooves, which
aspirate the raw liquid A into the housing 20 and then send out the
liquid toward the outer circumferential edge of the flange portion
12.
[0033] Moreover, on the surface of the flange portion 12, pumping
grooves 35, which are also spiral-shaped, are formed repeatedly in
the circumferential direction so as to surround the pressurization
grooves 34 from the outside with respect to the radius direction.
At a position of the fixed plate 24 which is opposed to the pumping
grooves 35, an introduction port 24b for the raw liquid B is
opened. The pumping grooves 35 are formed to have a depth of
approximately 20 to 100 .mu.m, which is larger than the depth of
the pressurization grooves 34. The pumping grooves 35 act to
aspirate the raw liquid B from the introduction port 24b into the
bearing clearance when the agitation rotor 10 rotates and to send
out this raw liquid B and the raw liquid A sent by the
pressurization grooves 34 toward the outer circumferential edge of
the flange portion 12 while agitating the both raw liquids.
[0034] Furthermore, on the surface of the flange portion 12, radial
agitation grooves 36 are repeatedly formed in the circumferential
direction so as to surround the pumping grooves 35 from the outside
with respect to the radius direction. These agitation grooves 36
are open to the outer circumferential edge of the flange portion
12. The raw liquids A and B flowing in the clearance between the
flange portion 12 and the fixed plate 24 toward the outer
circumferential edge of the flange portion 12 by means of actions
of the pressurization and pumping grooves 34 and 35 are flown into
the agitation grooves 36 eventually. Then, the raw liquids A and B
are discharged from the agitation grooves 36 toward the outside in
the radius direction by means of a centrifugal force.
[0035] In such a way, the raw liquids A and B are aspirated into
the clearance between the flange portion 12 of the agitation rotor
10 and the fixed plate 24, and flow toward the outer
circumferential edge of the flange portion 12 in accordance with
the rotation of the agitation rotor 10. In this process, the raw
liquids A and B are imparted with a large shearing force due to the
rotations of the pumping grooves 35 and agitation grooves 36, and
are agitated while being atomized by means of the energy of this
shearing force. Thus, the raw liquids A and B are formed into a
homogenized emulsion, and are discharged from the agitation grooves
36 to the outer circumferential edge of the flange portion 12. The
emulsion discharged from the agitation grooves 36 stays in a
collection chamber 37 formed between the spacer ring 25 and the
flange portion 12 of the agitation rotor 10, and then discharged
from an ejection port 25b opened in the spacer ring 25 to the
outside of the housing 20.
[0036] In the homogenizer of this embodiment thus constructed, the
clearance between the flange portion 12 of the agitation rotor 10
and the fixed plate 24 serves as the bearing clearance of the
thrust hydrodynamic bearing 32, and in general, it is possible to
set the bearing clearance of the thrust hydrodynamic bearing at
about several micrometers. Accordingly, it is also possible to set
the clearance between the flange portion 12 and the fixed plate 24
at several micrometers. Therefore, when the agitation rotor 10 is
rotated, a large shearing force can be applied to the raw liquids A
and B flowing in the clearance, and an emulsion with a small grain
diameter can be produced efficiently.
[0037] In the case where the thrust hydrodynamic bearings 31 and 32
are provided on the front and back of the flange portion 12 of the
agitation rotor 10 as in this embodiment, the flange portion 12 is
naturally positioned in the axial direction between the bearing
ring 23 and the fixed plate 24 such that the pressures of the
lubricating fluids pressurized in the bearing clearances of the
respective thrust hydrodynamic bearings become equal to each other.
In the case of this embodiment, the pressurization grooves 33 of
the thrust hydrodynamic bearing 31 are provided outside the journal
portion 11 of the agitation rotor 10, and rotate at peripheral
speed faster than that of the pressurization grooves 34 of the
thrust hydrodynamic bearing 32, which are spirally extended from
the rotation center of the agitation rotor. Accordingly, the
dynamic pressure of the lubricating fluid, which is generated in
the bearing clearance of the thrust hydrodynamic bearing 31,
becomes naturally larger than that in the bearing clearance of the
thrust hydrodynamic bearing 32. Therefore, even if the thickness of
the spacer ring 25 in the axial direction is set larger than the
thickness of the flange portion 12, the bearing clearance of the
thrust hydrodynamic bearing 32 on the front surface side of the
flange portion 12 can be maintained to be small. For example,
suppose a case where dimensions are set as: 40 mm for an outer
diameter of the flange portion 12; 20 mm for an outer diameter of
the pressurization grooves 34; 40 mm for an outer diameter of the
pressurization grooves 33; 22.5 mm for an outer diameter of the
journal portion 11; and 20 .mu.m for a sum of the bearing
clearances of the front and back of the flange portion 12, which
are defined by the spacer ring 25. In this case, when the agitation
rotor 10 is rotated at 50,000 rpm, the bearing clearance of the
thrust hydrodynamic bearing 31 becomes 16 .mu.m, and the bearing
clearance of the thrust hydrodynamic bearing 32 becomes 4 .mu.m.
Thus, while avoiding as much as possible a solid contact of the
agitation rotor 10 with the fixed plate 24 and the bearing ring 25
at the time of starting the rotation of the agitation rotor 10, the
clearance between the fixed plate 24 and the flange portion 12 can
be set extremely small at the time of a steady rotation of the
agitation rotor 10. Accordingly, it is possible to efficiently
apply the sharing force to the raw liquids A and B introduced into
the clearance described above.
[0038] Moreover, in the case of this homogenizer, the grain
diameter of the emulsion prepared by the rotation of the agitation
rotor 10 depends on the size of the clearance between the flange
portion 12 and the fixed plate 24. Accordingly, it is very
convenient if the size of the clearance can be arbitrarily
controlled, because this allows the grain diameter of the emulsion
itself to be also controlled to some extent.
[0039] For this purpose, in the homogenizer of the first
embodiment, which is shown in FIG. 3, pressure release ports 23b
and 24c, which communicate with the bearing clearances of the
thrust hydrodynamic bearings 31 and 32, respectively, are provided.
Moreover, relief valves (not shown) are provided in the pressure
relief ports 23b and 24c to control the pressures in the bearing
clearances, thus making it possible to adjust the position of the
flange portion 12 in the rotation axis direction between the
bearing ring 25 and the fixed plate 24. Thus, it is possible to
substantially distribute the grain diameter of the prepared
emulsion in the vicinity of the target grain diameter.
[0040] In the homogenizer of the first embodiment, the
pressurization grooves 34, the pumping grooves 35, and the
agitation grooves 36 are formed separately from one another on the
surface (surface opposed to the fixed plate) of the flange portion
12. However, as long as a sufficient shearing force can be imparted
to the raw liquids A and B aspirated between the flange portion 12
and the fixed plate 24, and as long as the flange portion 12 can be
kept in a non-contact state with respect to the fixed plate 24,
there is no problem in forming only the spiral-shaped agitation
grooves 5 on the surface of the flange portion 12, as shown in FIG.
1. However, in order to efficiently perform the respective
functions, namely, the aspiration of the raw liquids A and B, the
function as the thrust hydrodynamic bearings, and the mixing and
agitation of the raw liquids A and B, it is possible to divide the
surface of the flange portion 12 into three regions of a center
circle region, an intermediate ring region, and an outer ring
region, and to form grooves with shapes optimal for the respective
regions as in this embodiment.
[0041] FIG. 5 is a view showing a second embodiment of the
homogenizer to which the present invention is concretely applied.
This homogenizer also has approximately the same structure as that
of the homogenizer of the first embodiment, and mixes and agitates
the raw liquids A and B in the bearing clearances of the thrust
hydrodynamic bearings. However, in the second embodiment,
arrangements and patterns of pressurization grooves 43, pumping
grooves 44, agitation grooves 45, and the like, which are defined
in a flange portion 42 of an agitation rotor 40, are different from
those of the first embodiment. Note that the same reference
numerals as those of the first embodiment are added to the same
constituents as those of the first embodiment in FIG. 5, and
detailed description thereof is omitted.
[0042] Defined on the surface (opposed surface to the fixed plate
24) of the flange portion 42 of the agitation rotor 40 are the
pressurization grooves 43 which pressurize the raw liquid A as the
lubricating fluid, the pumping grooves 44 which aspirate the raw
liquid B into a clearance between a fixed plate 50 and the flange
portion 42, and the agitation grooves 45 which mix and agitate the
raw liquids A and B. As shown in FIG. 6, the pressurization grooves
43 are located on the outer diameter side than the agitation
grooves 45 and the pumping grooves 44, and formed spirally to have
a depth of approximately 10 to 50 .mu.m. In accordance with a
rotation of the agitation rotor 40, the pressurization grooves 43
pressurize the raw liquids A toward a rotation center of the
agitation rotor 40, thereby forming a high-pressure fluid
lubricating film between the fixed plate 50 and the flange portion
42. Thus, the rotation of the agitation rotor 40 is supported in a
state where the agitation rotor 40 is kept in a non-contact state
with respect to the fixed plate 50. Moreover, an introduction port
50a for the raw liquid A is opened at a position of the fixed plate
50 which is opposed to the pressurization grooves 43, and the raw
liquid A is aspirated therethrough to the clearance between the
fixed plate 50 and the flange portion 42 in accordance with the
rotation of the agitation rotor 40.
[0043] The above-described pumping grooves 44 are formed spirally
from a rotation center on a surface of the flange portion 42 to an
outer diameter thereof. The depth of the pumping grooves 44 is
approximately 10 to 50 .mu.m, and the pumping grooves 44 are formed
to be deeper than the pressurizing grooves 43. The pumping grooves
44 pressurize the raw liquid B to the outer diameter side of the
flange portion 42 in accordance with the rotation of the agitation
rotor 40. An introduction port 50b for the raw liquid B is opened
at a position of the fixed plate 50 which is opposed to the pumping
grooves 44, that is, at a position opposed to the rotation center
of the agitation rotor 40. When the agitation rotor 40 rotates, the
raw liquid B is aspirated from the introduction port 50b into the
clearance between the fixed plate 50 and the flange portion 42 by
means of an aspiration force generated by the pumping grooves
44.
[0044] Meanwhile, the above-described agitation grooves 45 are
formed radially between the pressurization grooves 43 and the
pumping grooves 44, and a depth thereof is approximately 20 to 100
.mu.m. Hence, to the agitation grooves 45, the raw liquid A is
flown from the outer diameter side thereof, and the raw liquid B is
flown from the inner diameter side thereof. In accordance with the
rotation of the agitation rotor 40, the raw liquids A and B are
mixed and agitated in the clearance between the flange portion 42
and the fixed plate 50. Moreover, in the flange portion 42, through
holes 46 are defined so as to correspond to outermost diameter
positions of the agitation grooves 45, and the raw liquids A and B
mixed and agitated in the agitation grooves 45 are adapted to pass
through the through holes 46 to flow toward the backside of the
flange portion 42.
[0045] Another agitation grooves 47 are radially formed on the
backside (surface opposed to the bearing ring 23) of the flange
portion 42. The raw liquids A and B fed with pressure through the
through hole 46 from the front surface side of the flange portion
42 to the backside thereof are flown into these second agitation
grooves 47, and then are discharged from the agitation grooves 47
to the outside thereof in the radius direction by means of the
centrifugal force.
[0046] The raw liquids A and B are aspirated into the clearance
between the flange portion 42 of the agitation rotor 40 and the
fixed plate 50 in this way. In accordance with the rotation of the
agitation rotor 40, the raw liquids A and B flow toward the outer
circumferential edge of the flange portion 42. In this process, the
raw liquids A and B are imparted with a large shearing force by
means of the rotation of the first agitation grooves 45 provided on
the front surface side of the flange portion and the rotation of
the second agitation grooves 47 provided on the backside thereof.
The raw liquids A and B are agitated while being atomized by means
of the energy of this shearing force. Thus, the raw liquids A and B
are made into a homogenized emulsion and discharged from the second
agitation grooves 47 to the outer circumferential edge of the
flange portion 42. The emulsion discharged from the agitation
grooves 47 stays in a collection chamber 37 defined between the
spacer ring 25 and the flange portion 42 of the agitation rotor 40,
and then discharged from an ejection port 25b opened in the spacer
ring 25 to the outside of the housing 20.
[0047] Then, also in this homogenizer of the second embodiment, the
clearance between the flange portion 42 of the agitation rotor 40
and the fixed plate 50 serves as the bearing clearance of the
thrust hydrodynamic bearing, and in general, it is possible to set
the bearing clearance of the thrust hydrodynamic bearing at about
several micrometers. Accordingly, it is also possible to set the
clearance between the flange portion 42 and the fixed plate 50 at
several micrometers. Therefore, when the agitation rotor 40 is
rotated, a large shearing force can be applied to the raw liquids A
and B flowing in the clearance, and an emulsion with a small grain
diameter can be produced efficiently.
[0048] Particularly, in this homogenizer of the second embodiment,
the peripheral speed of the pressurization grooves 43 in the thrust
hydrodynamic bearing 32 is faster than that of the pressurization
grooves 33 in the thrust hydrodynamic bearing 31. Accordingly, the
clearance between the flange portion 42 and the bearing ring 23
tends to become smaller than the clearance between the flange
portion 42 and the fixed plate 50. Therefore, after the raw liquids
A and B are agitated and mixed by the first agitation grooves 45 to
be made into an emulsion, the emulsion sent from the first
agitation grooves 45 to the second agitation grooves 47 can be
further atomized, leading to such an advantage that an emulsion
with a small grain diameter can be stably prepared by the agitation
performed in two steps.
[0049] As described above, according to the homogenizer of the
present invention, the bearing clearance of the thrust hydrodynamic
bearing into which the raw liquids are introduced is as extremely
small as several micrometers, and when the agitation rotor rotates,
an extremely large shearing force is applied to the raw liquids.
This shearing force makes it possible to prepare an emulsion with a
grain diameter as extremely fine as approximately 1 .mu.m.
Moreover, the grain diameter distribution of the produced emulsion
becomes one exhibiting sharp characteristics in the vicinity of the
target grain diameter. Furthermore, because the thrust hydrodynamic
bearing itself exerts a function as a pump, large-scale equipment
such as a high-pressure pump can be eliminated, thus making it
possible to provide an extremely compact homogenizer with a simple
structure.
* * * * *
References