Title: Flow rate control apparatus
Abstract: A flow rate control apparatus is constructed by integrally assembling a pulsation-attenuating mechanism for balancing a regulated pilot pressure from a pressure-regulating section and a primary pressure of a pressure fluid flowing through a fluid passage to attenuate pressure fluctuation caused by pulsation of the pressure fluid, and a flow rate control mechanism for controlling a flow amount of the pressure fluid flowing through the fluid passage by adjusting a valve lift amount of a valve plug with a linear actuator controlled based on a rotary driving control signal from a controller.
Patent Number: 6,889,706 Issued on 05/10/2005 to Fukano, et al.
| Inventors:
|
Fukano; Yoshihiro (Moriya, JP);
Uchino; Tadashi (Moriya, JP);
Suzuki; Takamitsu (Mitsukaido, JP)
|
| Assignee:
|
SMC Kabushiki Kaisha (Tokyo, JP)
|
| Appl. No.:
|
305189 |
| Filed:
|
November 27, 2002 |
Foreign Application Priority Data
| Dec 04, 2001[JP] | 2001-370480 |
| Jun 14, 2002[JP] | 2002-174209 |
| Current U.S. Class: |
137/487.5; 137/495; 137/554; 137/613 |
| Intern'l Class: |
F16K 047/00; G05D007/06; G05D016/20 |
| Field of Search: |
137/4875,494,495,553,554,556,613
700/282
|
References Cited [Referenced By]
U.S. Patent Documents
| 4299251 | Nov., 1981 | Dugas.
| |
| 4635901 | Jan., 1987 | Pond.
| |
| 4694390 | Sep., 1987 | Lee.
| |
| 5047965 | Sep., 1991 | Zlokovitz.
| |
| 5329966 | Jul., 1994 | Fenimore et al.
| |
| 5460196 | Oct., 1995 | Yonnet.
| |
| 5549137 | Aug., 1996 | Lenz et al.
| |
| 5564677 | Oct., 1996 | Levy et al.
| |
| 5758967 | Jun., 1998 | King.
| |
| 6568416 | May., 2003 | Tucker et al.
| |
| Foreign Patent Documents |
| 0 926 355 | Jun., 1999 | EP.
| |
| 763 215 | Apr., 1934 | FR.
| |
| 40-16934 | Aug., 1965 | JP.
| |
| 62-824112 | Apr., 1987 | JP.
| |
| 06-295209 | Oct., 1994 | JP.
| |
| 10-328321 | Aug., 1998 | JP.
| |
Other References
NOTE: English language abstracts of the above Japanese citations are provided
to serve as partial translations thereof.
|
Primary Examiner: Krishnamurthy; Ramesh
Attorney, Agent or Firm: Guss; Paul A.
Claims
1. A flow rate control apparatus comprising:
a pulsation-attenuating means for balancing a regulated pilot pressure from a
pressure-regulating section and a primary pressure of a pressure fluid introduced
into said flow rate control apparatus and flowing through a fluid passage to attenuate
pressure fluctuation caused by pulsation of said pressure fluid; and
a flow rate control mechanism having a valve plug for opening/closing said fluid
passage, said flow rate control mechanism controlling a flow amount of said pressure
fluid flowing through said fluid passage by adjusting a valve lift amount of said
valve plug with a linear actuator controlled based on a control signal from a control
unit.
wherein said pulsation-attenuating means includes a pressure-regulating section
for regulating a pressure fluid introduced from a pressure fluid supply port to
have a predetermined pressure, and a pulsation-balancing section provided with
a valve member for opening/closing said fluid passage based on said pressure fluid
from said pressure-regulating section, and
wherein said valve member includes a sliding plate arranged displaceably between
a first diaphragm and a second diaphragm, a valve plug connected to said sliding
plate, a seal member attached to an outer surface of said sliding plate, and an
intermediate member provided between said sliding plate and said valve plug.
2. The flow rate control apparatus according to claim 1, wherein said flow rate
control mechanism is provided with a rotation-detecting section for detecting a
displacement amount in an axial direction based on an amount of rotation of a drive
shaft of said linear actuator.
3. The flow rate control apparatus according to claim 1, wherein said pulsation-attenuating
means and said flow rate control mechanism are integrally assembled with a joint
section, and said joint section is provided with said fluid passage for communicating
with a first port disposed on one side of said joint section and a second port
disposed on the other aide of said joint section.
4. The flow rate control apparatus according to claim 1, wherein said valve member
is displaced by a pressing force of said pressure fluid flowing from said pressure-regulating
section and introduced into a pressure chamber.
5. A flow rate control apparatus comprising:
a pulsation-attenuating mechanism for balancing a regulated pilot pressure from
a pressure-regulating section and a primary pressure of a pressure fluid flowing
through a fluid passage to attenuate pressure fluctuation caused by pulsation of
said pressure fluid;
said pulsation-attenuating mechanism comprising a pulsation-balancing section
provided with a valve member for opening/closing said fluid passage based on said
pilot pressure, said valve member comprising a displaceable sliding plate in contact
with a diaphragm, and a valve plug connected to said sliding plate, and
a flow rate control mechanism having a valve plug for opening/closing said fluid
passage, said flow rate control mechanism controlling a flow amount of said pressure
fluid flowing through said fluid passage by adjusting a valve lift amount of said
valve plug with a linear actuator controlled based on a control signal from a control
unit,
wherein said pressure-regulating section regulates a pressure fluid introduced
from a pressure fluid supply port to thereby supply said pilot pressure having
a predetermined pressure, and
wherein said sliding plate is arranged displaceably between a first diaphragm
and a second diaphragm a seal member is attached to an outer surface of said sliding
plate, and an intermediate member is provided between said sliding plate and said
valve plug.
6. The flow rate control apparatus according to claim 5, wherein said flow rate
control mechanism is provided with a rotation-detecting section for detecting a
displacement amount in an axial direction based on an amount of rotation of a drive
shaft of said linear actuator.
7. The flow rate control apparatus according to claim 5, wherein said pulsation-attenuating
mechanism and said flow rate control mechanism are integrally assembled with a
joint section, and said joint section is provided with said fluid passage for communicating
with a first port disposed on one side of said joint section and a second port
disposed on the other side of said joint section.
8. The flow rate control apparatus according to claim 5, wherein said valve member
is displaced by a pressing force of said pressure fluid flowing from said pressure-regulating
section and introduced into a pressure chamber.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flow rate control apparatus which attenuates
the pulsation of a pressure fluid flowing through a fluid passage and which is
capable of controlling the flow rate of the pressure fluid highly accurately.
2. Description of the Related Art
FIG. 10 shows a conventional flow rate control system for controlling the flow
rate of a fluid flowing through a fluid passage.
The flow rate control system
1 comprises a pump
3 which pumps and
feeds a pressure fluid stored in a tank
2, an opening/closing valve
5
which is connected on the downstream side of the pump
3 via a tube passage
4 and which opens/closes a fluid passage for the pressure fluid fed from
the pump
3, and a flow rate control valve
7 which is connected on
the downstream side of the opening/closing valve
5 via a tube passage
6
and which controls the flow rate of the pressure fluid flowing through the fluid passage.
A flow rate sensor
8, which detects the flow rate of the pressure fluid
flowing through the fluid passage, is provided on the downstream side of the flow
rate control valve
7. The flow rate of the pressure fluid flowing through
the fluid passage is indicated on an indicator
9 based on a detection signal
supplied from the flow rate sensor
8.
An electropneumatic regulator
11 is connected to the flow rate control
valve
7 via a tube passage
12 for regulating the pressure of the
air supplied from a compressed air supply source
10 to provide a predetermined
pilot pressure for a pilot chamber of the flow rate control valve
7. The
electropneumatic regulator
11 controls the air supplied from the compressed
air supply source
10 to have a predetermined pressure based on a control
signal from a controller
13 so that the pressure is provided as a pilot pressure.
The operation of the conventional flow rate control system
1 described
above will be schematically explained. The pressure fluid is stored in the tank
2 and is fed by the pump
3. The pressure fluid is introduced into
the flow rate control valve
7 when the opening/closing valve
5 is
opened. The pilot pressure is regulated to have the predetermined pressure by the
electropneumatic regulator
11, and is introduced into the pilot chamber
of the flow rate control valve
7. The valve opening degree of an unillustrated
valve plug is controlled in the flow rate control valve
7 by balancing the
pilot pressure introduced into the pilot chamber and the pressure (primary pressure)
of the pressure fluid supplied from the opening/closing valve
5.
Therefore, the valve opening degree of the valve plug is adjusted in the
flow rate control valve
7 by balancing the pilot pressure controlled based
on the control signal from the controller
13 and the primary pressure of
the pressure fluid supplied from the opening/closing valve
5. The pressure
fluid is provided after being controlled to have the flow rate corresponding to
the valve opening degree of the valve plug.
The flow rate of the pressure fluid from the flow rate control valve
7
is detected by the flow rate sensor
8, and the detected flow rate is indicated
on the indicator
9.
However, in the conventional flow rate control system
1 described
above, the valve opening degree of the flow rate control valve
7 is controlled
by the pneumatic pressure (pilot pressure) from the electropneumatic regulator
11. Therefore, some dispersion appears in the flow rate due to the delay
of response when the valve opening degree of the unillustrated valve plug is controlled,
and it is difficult to stably control the flow rate.
Further, in the conventional flow rate control system
1, the piping
passages between the fluid-operated apparatuses including, for example, the opening/closing
valve
5, the flow rate control valve
7, and the electropneumatic
regulator
11 are connected by the tube passages
4,
6. Therefore,
piping operation is complicated, installation area is increased, and working space
is increased.
Furthermore, in the conventional flow rate control system
1,
some pressure fluctuation such as pulsation appears in the pressure fluid supplied
from the opening/closing valve
5, for example, resulting from the feeding
operation of the pump. Therefore, it is difficult to stably control the flow rate
by the flow rate control valve
7.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide a flow rate control apparatus
which makes it possible to eliminate any delay of response when the valve opening
degree of a valve plug is controlled, downsize the entire apparatus, and reduce
the installation space.
A principal object of the present invention is to provide a flow rate control
apparatus
which makes it possible to attenuate pressure fluctuation such as pulsation and
stably control the flow rate of a pressure fluid.
The above and other objects, features, and advantages of the present invention
will become more apparent from the following description when taken in conjunction
with the accompanying drawings in which a preferred embodiment of the present invention
is shown by way of illustrative example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is, with partial omission, a vertical sectional view illustrating a flow
rate control apparatus according to an embodiment of the present invention;
FIG. 2 is a partial magnified vertical sectional view illustrating a pulsation-balancing
section of the flow rate control apparatus shown in FIG. 1;
FIG. 3 is a partial magnified vertical sectional view illustrating a flow rate
control mechanism of the flow rate control apparatus shown in FIG. 1;
FIG. 4 shows a block diagram illustrating an arrangement of a flow rate control
system into which the flow rate control apparatus shown in FIG. 1 is incorporated;
FIG. 5 shows a block diagram illustrating an arrangement of an exemplary modified
embodiment of the flow rate control system shown in FIG. 4;
FIG. 6 is, with partial omission, a vertical sectional view illustrating a flow
rate control apparatus according to another embodiment of the present invention;
FIG. 7 is a partial magnified vertical sectional view illustrating a pulsation-balancing
section of the flow rate control apparatus shown in FIG. 6;
FIG. 8 is a see-through perspective view illustrating a plurality of wave-dissipating
projections provided on an inner wall in a fluid passage of the flow rate control
apparatus shown in FIG. 6;
FIG. 9 is a vertical sectional view taken along a line IX—IX shown in
FIG. 6; and
FIG. 10 shows a block diagram illustrating an arrangement of a conventional
flow rate control system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, reference numeral
20 indicates a flow rate control apparatus
according to an embodiment of the present invention.
The flow rate control apparatus
20 comprises a joint section
22
to which unillustrated tubes are detachably connected while being spaced from each
other by a predetermined distance, a pulsation-attenuating mechanism
24
which is provided on one side in the axial direction of the joint section
22,
and a flow rate control mechanism
26 which is provided on the other side
in the axial direction of the joint section
22.
The flow rate control apparatus
20 is constructed by integrally assembling
the joint section
22, the pulsation-attenuating mechanism
24, and
the flow rate control mechanism
26.
The joint section
22 has a first joint body
30 which is provided
with a first port
28 at one end, and a second joint body
34 which
is provided with a second port
32 at the other end. A fluid passage
36
is provided in the first and second joint bodies
30,
34 connected
substantially coaxially by a seal member for communicating with the first port
28 and the second port
32.
Further, the joint section
22 includes inner members
40 and
lock nuts
42. The inner members
40 are engaged with the first port
28 and the second port
32 respectively and are inserted into openings
of the tubes
38. The lock nuts
42 are screwed into screw grooves
engraved at the ends of the first and second joint bodies
30,
34
to retain the liquid-tightness at the connecting portions of the tubes
38 thereby.
The pulsation-attenuating mechanism
24 is arranged on the joint section
22 disposed closely to the first port
28. The pulsation-attenuating
mechanism
24 has a housing
46 which is constructed by connecting
a plurality of block members including a bonnet
44 disposed at an upper position.
The air is supplied into the bonnet
44 via a pressure fluid supply port
50 connected to a compressed air supply source
48. A pressure-regulating
section
54 is provided in the bonnet
44 for regulating the pressure
of the air supplied from the pressure fluid supply port
50 to have a predetermined
pressure and flowing the pressure-regulated air to a passage
52.
In the pressure-regulating section
54, the air from the pressure fluid
supply port
50 is supplied to a diaphragm chamber (not shown). The spring
force of a spring member adjusted by an unillustrated pressure-regulating handle
is balanced with the pressing force to press a diaphragm (not shown) by the pressure
of the pressure fluid introduced into the diaphragm chamber. A stem and a valve
plug, which are not shown, are displaced under the bending action of the unillustrated
diaphragm. Accordingly, the pressure of the air supplied from the pressure fluid
supply port
50 can be regulated to have a desired pressure.
On the other hand, a pulsation-balancing section
58 is provided under
the
housing
46 to operate a valve plug
56 for opening/closing the fluid
passage
36 (ON/OFF operation) based on the air from the pressure-regulating
section
54.
As shown in FIG. 2, the pulsation-balancing section
58 is provided with
a pressure chamber
60 into which the air (pilot pressure) from the pressure-regulating
section
54 via the passage
52 is introduced. A valve member
62
facing the fluid passage
36 is displaced by the air introduced into the
pressure chamber
60.
The valve member
62 has a sliding plate
68 which is arranged between
an upper first diaphragm
64 and a lower second diaphragm
66 and which
is displaceable in the vertical direction, a valve plug
56 which is connected
to a lower central portion of the sliding plate
68 by a screw member
70
and which approaches or separates from a seat section
72 formed on the housing
46, a seal member
74 which is attached to an annular groove on the
outer circumferential surface of the sliding plate
68, and an intermediate
member
78 which is interposed between the sliding plate
68 and the
valve plug
56 and which functions as a stopper by contacting an inclined
surface
76 formed on the housing
46.
The first diaphragm
64 is formed of, for example, a rubber material, and
functions to protect the sliding plate
68. The second diaphragm
66
is preferably formed of, for example, a resin material such as polytetrafluoroethylene
(PTFE) to retain the liquid-tightness for the pressure fluid and exclude any liquid pool.
Even if the pressure fluid flowing through the fluid passage
36 undergoes
the pressure fluctuation such as pulsation, the pressure fluctuation of the pressure
fluid flowing through the fluid passage
36 can be attenuated by the pressure
of the air supplied to the pressure chamber
60, and it is possible to flow
the pressure fluid having a substantially constant pressure.
The flow rate control mechanism
26 has a housing
80 which is connected
to the second joint body
34, and a first piston
82 and a second piston
84 which are displaceable in the direction of the arrow X
1 or X
2
along a chamber formed in the housing
80.
As shown in FIG. 3, the first piston
82 is provided with a lower first
protrusion
86a having a large diameter and an upper second protrusion
86b having a small diameter. The lower first protrusion
86a
is slidably inserted into the housing
80. A piston packing
88a
is attached to an annular groove on the outer circumferential surface of the
first piston
82.
The second protrusion
86b of the first piston
82 is engaged
with a recess formed at a lower portion of the second piston
84. A pair
of piston packings
88b,
88c are attached to annular
grooves on the outer circumferential surface of the second piston
84. The
second piston
84 is slidably inserted into the housing
80.
A spring member
90 is interposed between the inside of the second piston
84 and the second protrusion
86b. The first piston
82
and the second piston
84 are urged away from each other by the spring force
of the spring member
90.
A penetrating screw hole
96 is formed at a substantially central portion
of the second piston
84, and is screwed with a drive shaft
92 as
described later on.
A pin member
98 is attached to a groove on the side surface of the second
piston
84 so that the pin member
98 protrudes by a predetermined
length. The pin member
98 is engaged with an engaging groove
100
formed on the side surface of the housing
80. The pin member
98 prevents
the second piston
84 from rotating in the circumferential direction when
the second piston
84 is displaced in the axial direction.
A valve plug
102 made of, for example, a flexible material such as a resin
material or a rubber material is connected to the lower end of the first piston
82. The valve plug
102 is displaced together with the first piston
82. The valve plug
102 comprises a thick-walled section
104a
formed at a substantially central portion, and a thin-walled section
104b
which is formed integrally with the thick-walled section
104a.
The valve plug
102 is formed to be flexibly bendable.
The valve plug
102 opens/closes the fluid passage
36 by separating
from a seat section
106 formed on the second joint body
34 or by
seating on the seat section
106. Further, the valve plug
102 highly
accurately controls the flow rate of the pressure fluid flowing through the fluid
passage
36 based on the valve lift amount of the valve plug
102 (displacement
amount of the valve plug
102 in the axial direction).
A ring-shaped buffer member
108 is provided on the upper surface of the
valve plug
102 for protecting the thin-walled section
104b of
the valve plug
102. The buffer member
108 is made of, for example,
an elastic member such as rubber, and retained by the lower surface of the housing
80.
As shown in FIG. 1, a bonnet
110 is provided on the upper side of the
flow
rate control mechanism
26 and is assembled to an upper portion of the housing
80. A linear actuator
112 and a rotation-detecting section
114
are provided in the bonnet
110. The linear actuator
112 drives the
valve plug
102 by energizing an unillustrated power source. The rotation-detecting
section
114 detects the displacement amount of the valve plug
102
based on the displacement amount of the linear actuator
112.
A connector
120 is arranged closely to the rotation-detecting section
114,
and is used to send a detection signal to a controller
118 via a lead wire
116.
The linear actuator
112 comprises a linear stepping motor which is energized/deenergized
in accordance with a rotary driving control signal (pulse signal) from the controller
118. The linear actuator
112 includes an unillustrated stator and
an unillustrated rotor provided in a casing. The unillustrated rotor is rotated
in a predetermined direction under the action of a magnetically exciting current
supplied from the unillustrated power source.
The drive shaft
92 of the linear actuator
112 is provided displaceably
in the axial direction (direction of the arrow X
1 or X
2) under the
rotary action thereof.
The drive shaft
92 of the linear actuator
112 is provided with
a first shaft section
122 and a second shaft section
124 which are
engraved with screw portions having predetermined pitches, respectively. The diameter
of the upper first shaft section
122 is larger than the diameter of the
lower second shaft section
124.
An unillustrated light-emitting section and an unillustrated light-receiving
section
are disposed at mutually opposing positions while being spaced from each other
by a predetermined distance in the rotation-detecting section
114. An unillustrated
rotor is provided in the rotation-detecting section
114, and is connected
to the drive shaft
92 of the linear actuator
112 to rotate together
with the drive shaft
92. In this arrangement, the emitted light from the
light-emitting element passes through the inside of the rotor, and is received
by the light-receiving element. Accordingly, for example, the angle of rotation
and the number of rotation of the drive shaft
92 of the linear actuator
112 are detected and are sent as detection signals to the controller
118.
The controller
118 calculates the displacement amount of the drive shaft
92 in the axial direction based on the detection signal such as the number
of rotation and the pitch data of the drive shaft
92 of the linear actuator
112. The distance between the valve plug
102 and the seat section
106, i.e., the valve lift amount of the valve plug
102 is calculated
based on the result of the calculation performed by the controller
118.
Therefore, the controller
118 determines the deviation from the
preset lift amount of the valve plug
102 to adjust the lift amount of the
valve plug
102 so that the deviation should be zero. Accordingly, it is
possible to highly accurately control the flow rate of the pressure fluid flowing
through the fluid passage
36.
The flow rate control apparatus
20 according to the embodiment of the
present invention is basically constructed as described above. Next, its operation,
function, and effect will be explained.
As shown in FIG. 4, the pressure fluid stored in the tank
132 is fed to
the joint section
22 of the flow rate control apparatus
20 by pumping
with the pump
130. The pressure fluid is introduced into the pulsation-balancing
section
58 via the first port
28 of the joint section
22.
In the pressure-regulating section
54, the air supplied from the pressure
fluid supply port
50 is introduced into the unillustrated diaphragm chamber.
The spring force of the spring member is balanced with the pressure of the air
introduced into the diaphragm chamber under the bending action of the unillustrated
diaphragm. Accordingly, the air is regulated to have a desired pressure.
Therefore, the air regulated to have the desired pressure by the pressure-regulating
section
54 is introduced into the pressure chamber
60 of the pulsation-balancing
section
58 via the passage
52. The primary pressure of the pressure
fluid flowing through the fluid passage
36 is balanced with the pressure
of the air introduced into the pressure chamber
60.
If the pressure fluid flowing through the fluid passage
36 undergoes any
pressure fluctuation such as pulsation, the pressure fluctuation of the pressure
fluid flowing through the fluid passage
36 is attenuated by the air supplied
to the pressure chamber
60, and the pressure of the pressure fluid flowing
through the fluid passage
36 can be maintained to be substantially constant.
In other words, if the pressure fluid flowing through the fluid passage
36
undergoes any pressure fluctuation such as pulsation, the pressure fluctuation
of the pressure fluid is transmitted via the second diaphragm
66 to the
sliding plate
68, and the sliding plate
68 is slightly moved up and
down. During this process, buffering action is effected by the air in the pressure
chamber
60 which is provided on the side opposite to the fluid passage
36
with the sliding plate
68 interposing therebetween. Accordingly, the pressure
fluctuation of the pressure fluid is attenuated, and is absorbed suitably.
The pressure fluid from the pulsation-balancing section
58 flows along
the fluid passage
36 and is introduced into the flow rate control mechanism
26. In the flow rate control mechanism
26, the lift amount of the
valve plug
102 for adjusting the distance between the valve plug
102
and the seat section
106 is established by energizing/deenergizing the linear
actuator
112 based on the rotary driving control signal from the controller
118. The valve opening degree of the valve plug
102 is adjusted.
The pressure fluid flowing through the fluid passage
36 is controlled to
have a flow rate corresponding to the valve opening degree of the valve plug
102.
The controller
118 sends an energizing signal to the linear actuator
112
to displace the first and second shaft sections
122,
124 as the drive
shaft
92 of the linear actuator
112 in the direction of the arrow
X
1. Therefore, the first piston
82 and the second piston
84
screwed with the second shaft section
124 in the penetrating screw hole
96 are displaced upwardly by the rotation of the drive shaft
92.
Accordingly, the valve plug
102 is also moved upwardly, and the valve plug
102 is separated from the seat section
106.
The displacement amount of the valve plug
102 in the axial direction is
detected by the rotation-detecting section
114 as the amount of rotation
of the linear actuator
112. The controller
118 controls the linear
actuator
112 so that the valve plug
102 is stopped at a preset position
based on the detection signal (pulse signal) from the rotation-detecting section
114.
The controller
118 counts the pulse signals from the rotation-detecting
section
114 and sends a deenergizing signal to the linear actuator
112
when a preset predetermined number of pulses are counted, so that the driving of
the linear actuator
112 is stopped. The controller
118 can calculate
the displacement amount of the drive shaft
92 from the amount of rotation
such as the number of rotation and the angle of rotation of the drive shaft
92
and the screw pitch of the second shaft section
124 screwed with the second
piston
84. As a result, the lift amount of the valve plug
102 can
be controlled highly accurately, and the flow rate of the pressure fluid corresponding
to the lift amount of the valve plug
102 can be controlled highly accurately.
As described above, in the embodiment of the present invention, the lift amount
of the valve plug
102 is controlled based on the rotary driving control
signal from the controller
118. Therefore, the valve opening degree of the
valve plug
102 can be regulated without any dispersion in response unlike
the conventional art, and it is possible to stably control the flow rate of the
pressure fluid flowing through the fluid passage
36.
In the embodiment of the present invention, the apparatus is constructed, for
example, as if the opening/closing valve
5, the flow rate control valve
7, and the electropneumatic regulator
11, which relate to the conventional
art, are integrally assembled. Therefore, it is unnecessary to perform any piping
operation for connecting the respective fluid-operated apparatuses. There is no
liquid leakage or the like from the piping materials. The entire apparatus can
be downsized, and it is possible to reduce installation space.
Further, as shown in FIG. 5, a flow rate sensor
140 is arranged in
the fluid passage on the downstream side of the flow rate control apparatus
20
to perform the feedback control by sending a sensor detection signal from the flow
rate sensor
140 into the controller
118. Therefore, it is possible
to monitor the flow rate of the fluid flowing through the fluid passage
36
in real time.
In this arrangement, the controller
118 compares the preset flow rate
data
with the sensor detection signal from the flow rate sensor
140 to adjust
the valve lift amount of the valve plug
102 so that the difference therebetween
should be zero. Accordingly, it is possible to highly accurately control the flow
rate of the fluid actually flowing through the fluid passage
36.
Next, a flow rate control apparatus
150 according to another embodiment
of the present invention is shown in FIGS. 6 to
9. The constituent components
that are the same as those of the flow rate control apparatus
20 according
to the embodiment described above shown in FIG. 1 are designated by the same reference
numerals, detailed explanation of which will be omitted.
The flow rate control apparatus
150 according to the another embodiment
comprises a plurality of wave-dissipating projections (projections)
177a
to
177f which are provided on the inner wall of the fluid passage
36 disposed closely to the first port
28 and which protrude by predetermined
lengths from the inner wall surface toward the internal center of the fluid passage
36.
As shown in FIGS. 8 and 9, the plurality of wave-dissipating projections
177a
to
177f have substantially trapezoidal shapes with their widths
being gradually widened from the inner wall of the fluid passage
36 toward
the center of the fluid passage
36. Each of the plurality of wave-dissipating
projections
177a to
177f has a curved section
179
with a chamfered end and a slightly depressed recess
181. The plurality
of wave-dissipating projections
177a to
177f are arranged
while being spaced from each other by predetermined distances helically in the
clockwise direction on the inner circumferential wall surface of the fluid passage
36.
In this arrangement, as shown in FIG. 9, the first wave-dissipating projection
177a disposed most closely to the first port
28 is inclined
by a predetermined angle in the direction of the arrow A, the second wave-dissipating
projection
177b is inclined by a predetermined angle in the direction
of the arrow B, the third wave-dissipating projection
177c is inclined
by a predetermined angle in the direction of the arrow C, the fourth wave-dissipating
projection
177d is inclined by a predetermined angle in the direction
of the arrow D, the fifth wave-dissipating projection
177e is inclined
by a predetermined angle in the direction of the arrow E, and the sixth wave-dissipating
projection
177f is inclined by a predetermined angle in the direction
of the arrow F. The number of the plurality of wave-dissipating projections
177a
to
177f is not limited to six. A desired number of the wave-dissipating
projections may be set corresponding, for example, to the bore diameter and the
flow passage length of the fluid passage
36.
If any pulsation appears in the pressure fluid flowing through the fluid passage
36, the pulsating pressure fluid collides with the plurality of wave-dissipating
projections
177a to
177f. The pulsation energy included
in the pressure fluid can be dispersed and dissipated by the plurality of wave-dissipating
projections
177a to
177f.
Therefore, even if the pressure fluid flowing through the fluid passage
36 undergoes the pressure fluctuation such as pulsation, the pressure fluid
collides with the plurality of wave-dissipating projections
177a to
177f protruding on the inner wall of the fluid passage
36,
and the pulsation energy is attenuated. Further, the pulsation energy of the pressure
fluid flowing through the fluid passage
36 is attenuated by the pressure
of the air supplied to the pressure chamber
60. Thus, the pressure fluid
flows while being kept at a substantially constant pressure.
In the other embodiment, if the pressure fluctuation such as pulsation appears
in the pressure fluid flowing through the fluid passage
36, the pulsating
pressure fluid collides with the inclined surfaces of the plurality of wave-dissipating
projections
177a to
177f respectively. The pulsation
energy included in the pressure fluid is dispersed by the plurality of wave-dissipating
projections
177a to
177f. Accordingly, the pulsation
energy can be smoothly dissipated.
As described above, in the other embodiment, even if the pressure fluid flowing
through the fluid passage
36 undergoes the pressure fluctuation such as
pulsation, the pressure fluid collides with the plurality of wave-dissipating projections
177a to
177f protruding on the inner wall of the fluid
passage
36, and the pulsation energy is attenuated. Further, the pulsation
energy of the pressure fluid flowing through the fluid passage
36 is attenuated
by the pressure of the air supplied to the pressure chamber
60. Thus, the
pressure fluid flows while being kept at a substantially constant pressure.
As a result, in the other embodiment, the pressure fluctuation such as pulsation
of the pressure fluid can be smoothly attenuated by a simple structure such as
the plurality of wave-dissipating projections
177a to
177f
protruding from the inner wall of the fluid passage
36 as the pulsation-attenuating
mechanism
24. Therefore, it is possible to avoid increasing the size of
the entire apparatus, thereby avoiding the increase in production cost.
*
