Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2000-07-27
2002-05-28
Derakshani, Philippe (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S129100, C251S129170, C251S129180
Reexamination Certificate
active
06394415
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fluid control valve and fluid supply/exhaust system. In greater detail, the present invention refers to a fluid control valve, and a fluid supply/exhaust system, in which a member “a” is made unitary with a rod shaped shaft which applies pressure to a valve holder and is moved upwardly and downwardly by a coil using electromagnetic induction, and thereby, the portion between the valve seat and the valve holder is opened and closed. The fluid control valve and fluid supply/exhaust system of the present invention is chiefly used in semiconductor manufacturing apparatuses.
2. Description of the Related Art
Conventionally, fluid control valves which controlled fluids flowing through the valve body by means of opening and closing a portion between a valve body by means of opening and closing a portion between a valve seat and a valve holder using a drive unit and valve holders comprising a diaphragm and a diaphragm holder, and were of the following types:
One type having a rotating mechanism unit which is manually operated, in which a valve rod is moved upwardly and downwardly using the rotational movement of the rotating mechanism unit, and the portion between the valve seat and the diaphragm is opened and closed (hereinbelow, this type of fluid control valve is referred to as a manual valve (not shown in the figures));
A second type having a gas filling and discharge mechanism, in which the valve rod is moved upwardly and downwardly using a difference in pressure in this gas, and the portion between the valve seat and the diaphragm is opened and closed (hereinbelow, this type of fluid control valve is referred to as an air pressure valve, (FIG.
4
)); and
A third type having a mechanism which is subject to electromagnetic induction using a coil, wherein an iron core and plunger are installed at separate locations using this mechanism, and in concert with this, a bubble disc affixed to a plunger is moved upwardly and downwardly, and a portion between the bubble disk and a valve seat is opened and closed (hereinbelow, this type of fluid control valve is referred to as an electromagnetic valve (FIG.
5
)).
Hereinbelow, the method of opening and closing the valve in electromagnetic valves and air pressure valves, which are referred to as automatic valves, will be explained.
FIG. 4
is a schematic cross sectional view of an air pressure valve of a type in which the open and closed state of the valve is normally closed; the state is depicted in which the valve is closed. The opening and closing operation of the value is given below.
(Closed to Open Operation)
As a result of filling an instrumentation gas input port
01
with an instrumentation gas by means of an instrumentation gas changeover switch (not shown), an actuator
402
pushes upward, and simultaneously therewith, a rod shaped valve rod
403
which is affixed to actuator
402
is pushed upward, so that the diaphragm
404
, which is pushed against by valve rod
403
, separates from valve seat
405
, and the fluid output port
407
.
(Open to Closed Operation)
As a result of ceasing the filling of the instrumentation gas input port
401
with the instrumentation gas by means of the instrumentation gas change over switch (not shown), the actuator
402
, and the rod shaped valve rod
403
which is affixed to the actuator
402
, are pushed downward as a result of the force of spring
408
, and diaphragm
404
is pushed by valve rod
403
and diaphragm
404
comes into contact with valve
405
, and the flow of the fluid from fluid input port
406
to fluid output port
407
is halted.
FIG. 5
is a schematic cross section view of an electromagnetic valve in which the valve state is normally closed; the state is depicted in which the valve is closed. The opening and closing operation of the valve is as follows.
(Closed to Open Operation)
As a result of inputting electricity from terminal
501
and causing a current flow in coil
502
, electromagnetic induction is set up in coil
502
, and the iron core
503
affixed to the case and plunger
504
come into contact, and along with this, the valve disk
505
which is affixed to plunger
504
is pushed upward, so that the valve disk
505
and the valve seat
506
are separated, and fluid flows from valve input port
507
to valve output port
508
.
(Open to Closed Operation)
By cutting off the flow of current to coil
502
, the magnetic field of coil
502
is eliminated, and the plunger
504
which was in contact with iron core
503
separates therefrom, and as a result, the valve disk
505
which was affixed to plunger
504
is pushed downward by the force of a screw
509
, so that valve disk
505
and valve seat
506
come into contact, and the flow of fluid from fluid input port
507
to fluid output port
508
is stopped.
However, it has been discovered by the present inventors that these valves exhibit the following problems with respect to the response time (i.e., the amount of the time required from the state in which the valve was closed to that in which it is opened).
(1) In the case of the manually operated valve, the time required to rotate the handle is the response time, so that there are differences produced depending on the individual operators, and it is extremely difficult to stably conduct the opening and closing operation of the valve in less than, for example, 100 msec, and as the number of valves to be operated increases, it is not merely the case that the time required increases, but it is also possible to make mistakes in the order of operation and to cause counter flow and the like.
(2) The air pressure valve, which is also termed an automatic valve, has a structure which is highly airtight, and can be easily controlled so long as the fluid pressure is 10 kg/cm
2
or less. However, in the air pressure valve, the time required for the charging and discharging of the gas into the drive unit occupies approximately 90 percent of the response time, so that the opening and closing operation of the valve is slow, at several tens of milliseconds, and as a result of the length of the instrumentation tube which supplies the gas, or the pressure at which the gas is supplied, the response time of the valves may differ. As a result, irregularities are produced in the operational order of the valves and the actual operating order, and there are cases in which counter flow is produced.
(3) As a method of eliminating the problems in (2) above, a method has been employed in which the length of each instrumentation tube and the gas pressure within each instrumentation tube is set to the same value.
However, in, for example, fluid control devices for semiconductor manufacturing apparatuses and the like, in those apparatuses which employ a large number of fluid control valves, electromagnetic valves and the like are employed in order to charge and discharge gas in the drive units of the air pressure valves; however, because the distances between the electromagnetic valves and the air pressure valves differ for each instrumentation tube, it is necessary to arrange the lengths of each instrumentation tube to the fluid control valve which is at the greatest distance. For this reason, storage space is required in the fluid control valve for unnecessary instrumentation tubes, and with respect to the entirety of the fluid control device, as well, it is only possible to construct a system in which the rate is determined by the fluid control valve having the longest response period.
(4) As described above, electromagnetic valves are preferentially employed in the charging and discharging of gas in the drive units of the air pressure valves. In particular, as can be understood from the structure, the valves can be rapidly opened and closed within a few milliseconds. However, as is clear from this use, the structure is such as to permit gas leakage, and furthermore, there is a large amount of dead space within the valves. For this reason, such valves are not suited for uses such as the precise control of t
Dohi Ryosuke
Fukuda Hiroyuki
Ikeda Nobukazu
Nishino Kouji
Ohmi Tadahiro
Bonderer David A.
Knuth Randall J.
Ohmi Tadahiro
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