Normally closed-type fluid control valve

An normally closed-type fluid control valve, having a guide standing through a counter member on the side of an upper surface of a valve base is provided with a cylindrical member having an engaging portion at its lower end and movable up and down on an inner the side thereof. Cylindrical member is provided with an actuator therewithin so that the actuator may be held by the cylindrical member. A support member 051452225 is fixed in position by means of the counter member and the guide is inserted into a hole opened at a position below a lower end portion of the actuator. A lower end side of the actuator is engaged with an upper surface of the support member and a pressing spring is interposed between the support member and the engaging portion of the cylindrical member to press a valve body against a valve seat formed in the valve base, whereby closing the said valve so that the pressing spring may be compressed by an output of the actuator during the time when the actuator is acting to separate the valve body from the valve seat, whereby opening the valve.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a normally closed-type fluid control valve 
for controlling a flow rate and a pressure of various kinds of fluid such 
as gases and liquids. 
2. Description of the Prior Art 
This kind of normally closed-type fluid control valve (hereinafter referred 
to as the valve) has been disclosed in for example Japanese Patent 
Application Laid-Open No. Sho 64-55487. It is shown in FIG. 4(A), (B). 
Referring to FIG. 4(A), (B), reference numeral 51 designates a valve base 
comprising an inlet port 52 provided on the left side thereof, a vertical 
passage 53 communicating with said inlet port 52 provided at a center 
thereof, an upward opened fluid chamber 56 housing a diaphragm 55 fixed by 
means of a diaphragm counter member 54 provided in an upper portion 
thereof, an outlet port 57 communicating with said fluid chamber 56 
provided on the right side thereof, an orifice 58 formed in an upper 
portion of said vertical passage 53 and a valve seat 59 formed around said 
valve mouth 58. Reference numeral 60 designates a cylindrical member 
standing on an upper surface of said valve base 51 so as to push down said 
diaphragm counter member 54 from outside of the diaphragm counter member 
54 and it is fixed by means of a cylindrical counter member 62 fixedly 
mounted on said upper surface of the valve base 51 by means of bolts 61. 
Said cylindrical member 60 is provided with a valve rod 63 standing 
therewithin under the condition that a lower end surface of said valve rod 
63 is brought into contact with an upper surface of a central portion of 
said diaphragm 55. And, a pressing spring 65 for energizing the valve rod 
63 downward is provided between an upper stepped portion 64 of the valve 
rod 63 and an upper inner surface of the cylindrical member 60 so that the 
diaphragm 55 may be normally engaged with said valve seat 59 to normally 
close said orifice 58 and thus normally close the valve by pressing the 
valve rod 63 in the direction of the diaphragm 55 by means of said 
pressing spring 65. In addition, the valve rod 63 is provided with a 
through hole (not shown) in a lower portion thereof. A bridge 66 inserted 
through said through hole and placed on an upper surface of the diaphragm 
counter member 54 is provided with a piezostack 67 comprising a large 
number of piezoelements laminated on an upper surface thereof so that the 
valve rod 63 may be lifted by the action of said piezostack, whereby the 
pressing spring 65 is compressed to separate the diaphragm 55 from said 
valve seat 59 and open the orifice 58 and thus the valve is opened. 
In the valve having the above described construction, it is not required to 
provide moving members, such as the pressing spring 65 and an adjustable 
screw 68, within a fluid passage such as the fluid chamber 56, so that an 
effect occurs in that the production of metallic powders resulting from 
the contact among metals in the fluid passage can be prevented and thus an 
inside of the valve base 51 and a fluid can be prevented from being 
contaminated and damaged. 
However, in the above described conventional valve, the piezostack 67 has 
not the so-called closed type construction, so that a problem occurs in an 
insulation. And, a disadvantage occurs in that if it is intended to give 
the piezostack 67 a tightly closed construction, it is large-sized. In 
addition, the pressing spring 65 for energizing downward the valve rod 63 
is provided between said upper stepped portion 64 of the valve rod 63 and 
said upper inner surface of the cylindrical member 60, so that a lead wire 
69 for supplying the piezostack 67 with a voltage can not be taken out 
from above the piezostack 67 but can be taken out from the side portion of 
the piezostack 67. A disadvantage occurs in that an insulating 
construction for taking out said lead wire 69 is complicated and as a 
result this kind of valve is large-sized. 
SUMMARY OF THE INVENTION 
The present invention has been achieved paying attention to the above 
described matters and it is an object of the present invention to provide 
a compact valve not only capable of preventing metallic powders and the 
like from entering a fluid passage but also remarkably simple in 
construction. 
In order to achieve the above described object, a valve according to the 
present invention is characterized in that a guide standing through a 
counter member on the side of an upper surface of a valve base is provided 
with a cylindrical member having an engaging portion at its lower end and 
movable up and down on an inner side thereof. The cylindrical member is 
provided with, an actuator therewithin so that said actuator may be held 
by the cylindrical member, a support member fixed in position by means of 
said counter member and said guide being idly inserted into a hole opened 
at a position below a lower end portion of the actuator, and a lower end 
side of the actuator being engaged with an upper surface of said support 
member and a pressing spring being interposed between the support member 
and said engaging portion of the cylindrical member to always press a 
valve body against a valve seat formed in said valve base, whereby closing 
said valve so that said pressing spring may be compressed by an output of 
the actuator during the time when the actuator is acting to separate said 
valve body from said valve seat, whereby opening the valve. 
In the valve having the above described characteristic construction, 
usually the valve body is pressed against the valve seat by means of the 
pressing spring interposed between the support member and the cylindrical 
member to close an orifice. And, when the actuator acts, the pressing 
spring is compressed by said output of the actuator to separate the valve 
body from the valve seat, whereby opening said orifice. 
And, a mechanism not only contributing to the opening and closing of the 
valve but also preventing excessive sliding or wearing is provided at a 
position distant from a fluid flowing through the valve base, so that very 
small dusts, such as metallic powders, can be prevented from entering said 
fluid. In addition, in the case where the actuator is composed of a 
piezostack, a lead wire for supplying said piezostack with a voltage can 
be taken out from above the piezostack, so that a construction can be 
simplified, for example a compact tightly closed construction can be given 
to the piezostack.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The preferred embodiments of the present invention will be below described 
with reference to the drawings. 
FIG. 1 shows one example of a valve according to the present invention. 
Referring to FIG. 1, reference numeral 1 designates a valve base, a fluid 
passage 4 being formed between an inlet port 2 and an outlet port 3, an 
upper portion of a vertical passage 5 communicating with said inlet port 2 
being formed as an orifice 6, and a circumference of said orifice 6 being 
formed as a valve seat 7. Said valve base 1 is provided with a 
seal-setting member 9 for setting a seal member 8 on an upper surface 
thereof and a counter member 10 is fixedly mounted on an upper portion of 
said seal-setting member 9 by means of a clamping bolt 11. Reference 
numeral 12 designates a valve body opening and closing the orifice 6 and 
comprises a valve head portion 13 brought into contact with and separated 
from said valve seat 7 and a valve rod portion 15 extending upward from 
said valve head portion 13 and inserted into a circular spring-receiving 
portion 14 formed in said counter member 10. A diaphragm 16 is extended 
from an upper surface of the valve head portion 13 to the seal-setting 
member 9 by welding so as to form a leak-tight fluid chamber 17 between 
said diaphragm 16 and said upper surface of the valve base 1. On the other 
hand, a lifting spring 19 is provided between said spring-receiving 
portion 14 and a spring-engaging portion 18 provided in an upper portion 
of said valve rod portion 15 so as to be put on the valve rod portion 15, 
whereby separating said valve body 12 from the valve seat 7 to some 
extent. 
Reference numeral 20 designates a cylindrical guide opened at both ends, 
that is an upper end and a lower end, and screwed on the counter member 
10. A cylindrical member 21 is provided so as to move up and down along 
inner wall surfaces of said guide 20 and the counter member 10. In 
addition, piezostack 22 as an actuator is provided in said cylindrical 
member 21. 
That is to say, the cylindrical member 21 is not only opened in an upper 
portion thereof but also provided with an engaging portion 23 formed on 
the side of a lower end thereof and said engaging portion 23 is held by 
the valve rod portion 15 of said valve body 12 through a ruby sphere 24. 
And, the cylindrical member 21 is provided with two holes 25 opened face 
to face in a lower portion of a side surface thereof, a support member 26 
being idly inserted through said holes 25 so as to project from the holes 
25 at end portions thereof, and said support member 26 being fixed in 
position by means of the guide 20 screwed on the counter member 10 and the 
counter member 10, as shown in FIG. 2. 
Referring to FIG. 1 again, reference numeral 28 designates a pressing 
spring interposed between a spring-receiving portion 29 formed on an upper 
surface of the engaging portion 23 and a spring-receiving portion 30 
formed on a lower surface of the support member 26 for always energizing 
the engaging portion 23 downward to press the valve body 12 against the 
valve seat 7 against an energizing force of said lifting spring 19, 
whereby normally closing the orifice 6 by the valve head portion 13. And, 
said piezostack 22 is held by the support member 26 through a ruby sphere 
31 at a lower end portion thereof and held by an opened degree-regulating 
member 32 screwed on an outer circumference of an upper portion of the 
cylindrical member 21 at an upper end thereof. Reference numeral 33 
designates a lead wire for applying a voltage and reference numeral 34 
designates a clamping nut. 
And, in said valve having the above described construction, the valve body 
12 is pressed toward the valve seat 7 against said upward energizing force 
of the lifting spring 19 by an energizing force of said pressing spring 28 
interposed between the support member 26 and the engaging portion 23 of 
the cylindrical member 21, so that the orifice 6 is closed by the valve 
rod portion 15 to close the valve, in the usual time when no voltage is 
applied to the piezostack 22. 
And, upon applying a voltage to the piezostack 22, the piezostack 22 
expands in an up and down direction but the lower end side of the 
piezostack 22 is held by the support member 26, so that said expansion 
produces an upward force, which lifts the cylindrical member 21 through 
said opened degree-regulating member 32, and as a result the pressing 
spring 28 is compressed to stretch the lifting spring 19. Thus, the valve 
body 12 is separated from the orifice 6 by the upward energizing force to 
open the valve. 
In the valve having the above described construction, portions contributing 
to the opening and closing of the valve body 12 and sliding and wearing 
with said opening and closing actions are not provided in said passages, 
through which a fluid passes, so that there is not the possibility that 
very small dusts, such as metallic powders, are mixed in said fluid and 
the fluid is leaked outside. And, the construction is simplified on the 
whole and an area of portions brought into contact with the fluid is 
reduced and thus the members above the diaphragm 16 are prevented from 
being eroded and deteriorated even though the fluid is an aggressive gas 
and the like. In addition, since said lead wire 33 for supplying the 
piezostack 22 with a voltage can be taken out from above the piezostack 
22, for example a compact tightly closed construction can be given to the 
piezostack 22, that is the construction can be simplified to small-size 
the valve of this type. 
FIG. 3 shows an example of a valve according to another preferred 
embodiment of the present invention. Referring to FIG. 3, reference 
numeral 35 designates a valve body comprising a thin-walled (for example 
about 0.2 mm thick) elastic portion 37 formed on a circumference of a 
valve head portion 36 and an engaging portion 38 engaged with an upper 
surface of a valve base 1 outside of said elastic portion 37 and fixedly 
held by a counter member 10. A lifting spring 40 is screwed on a valve rod 
portion 39 extending upward from said valve head portion 36. Other 
constructions are quite same as in FIG. 1. In addition, reference numeral 
41 designates a spring-engaging member and reference numeral 42 designates 
a sealing member. 
Also in this preferred embodiment, it goes without saying that similar 
effects to those in the preferred embodiment shown in FIG. 1 can be 
obtained. 
The present invention is not limited by the above described respective 
preferred embodiments. For example, a thermal driving-type actuator may be 
used in place of the piezostack 22. 
Since the present invention has the above described construction, not only 
there is not the possibility that metallic powders and the like enter the 
fluid passage but also the compact valve remarkably simple in construction 
can be obtained.