FLOATING SEAL FOR FLUIDIC DEVICES

JOINT ETANCHE FLOTTANT POUR DISPOSITIF FLUIDIQUES

English Abstract

ABSTRACT
A floating seal fluidic device is disclosed comprised
of a housing, a connector which has a nozzle extending through
the housing and which forms a clearance with the housing, a
diaphragm stretched around the circumference of the connector
and having a bead which lies within the clearance wherein the
connector, the housing and the bead are so dimensioned that,
without fluid being supplied to the nozzle, the bead within the
clearance is floating, with fluid being supplied to the nozzle,
the bead is forced into the clearance between the connector
and the housing to provide the seal.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fluidic device comprising:
a housing;
connector means mounted within said housing in a
manner to provide a clearance therebetween,
said connector means having a nozzle
exteriorly of said housing; and,
a diaphragm mounted within said housing and having
a bead around the circumference of one end of
said diaphragm, said bead positioned within
said clearance between said connector means
and said housing to form an expandable fluid
chamber with said connector means, such that
when fluid is supplied to said nozzle, and to
said chamber, the fluid will force said bead
into sealing relation with said housing and
said connector means,
said connector means, said housing and said bead
being so dimensioned that, without fluid
supplied to said nozzle, said connector means
and said diaphragm with said bead are
floating with respect to said housing.
2. The device of claim 1 wherein said bead has a
first circumference and said connector means has a second
circumference, said first circumference being less than said
second circumference to form an interference fit between
said diaphragm bead and said connector means to prevent
fluid leaking from said housing upon small pressures of
fluid being supplied to said chamber.

3. The device of claim 2 comprising an actuator stem,
motion imparting means responsive to motion of said dia-
phragm for imparting said motion to said stem, said stem
extending through said housing.
4. The device of claim 3 wherein said motion
imparting means comprises a cup-shaped member.
5. A fluidic device comprising:
a housing having a first circumference and an end
having an opening therethrough of a second
circumference less than said first circumfer-
ence;
connector means mounted within said housing and
having a third circumference less than said
first circumference but greater than said
second circumference and providing a clear-
ance between said housing and said connector,
said connector means having a nozzle
exteriorly of said housing; and,
a diaphragm mounted within said housing and having
a bead around the circumference of one end of
said diaphragm, the circumference around said
one end of said diaphragm being slightly
smaller than the third circumference of said
connector means, said bead positioned within
said clearance between said connector means
and said housing to form an expandable fluid
chamber with said connector means, such that
when fluid is supplied to said nozzle, and to
said chamber, the fluid will force said bead
into sealing relation with said housing and
said connector means,

said connector means, said housing and said bead
being so dimensioned that, without fluid
supplied to said nozzle, said connector means
and said diaphragm with said bead are
floating with respect to said housing.
6. The device of claim 5 comprising an actuator stem,
and motion imparting means responsive to motion of said dia-
phragm for imparting said motion to said stem, said stem
extending through said housing.
7. The device of claim 6 wherein said motion
imparting means comprises a cup-shaped member.
8. The device of claim 7 further comprising a biasing
spring for biasing said stem into said housing to a first
deenergized position, said spring being insufficient to com-
press said bead between said housing and said connector
means.
9. A fluid actuator comprising:
a housing:
connector means mounted within said housing in a
manner to provide a clearance therebetween,
said connector means having a nozzle
exteriorly of said housing;
a diaphragm mounted within said housing and having
a bead around the circumference of one end of
said diaphragm, said bead positioned within
said clearance between said connector means
and said housing to form an expandable fluid
chamber with said connector means, such that
when fluid is supplied to said nozzle, and to
said chamber, the fluid will force said bead

into sealing relation with said housing and
said connector means;
shaft means having a first end abutting said dia-
phragm and a second end extending through
said housing; and,
biasing means for biasing said shaft and said dia-
phragm into a first position when said fluid
has not been supplied to said nozzle,
said connector means, said housing, said bead and
said biasing means being so dimensioned that,
without fluid supplied to said nozzle, said
connector means and said diaphragm with said
bead are floating with respect to said hous-
ing.
10. The actuator of claim 9 wherein said housing has a
first circumference and an end with an opening therethrough
having a second circumference less than said first circum-
ference and wherein said connector means has a third circum-
ference less than said first circumference but greater than
said second circumference with said nozzle extending through
said opening.
11. The actuator of claim 10 wherein said bead of said
diaphragm has a circumference slightly less than said third
circumference of said connector means such that an interfer-
ence fit is formed when said diaphragm is stretched over
said connector means to prevent leakages for small input
pressures to said chamber.

12. The actuator of claim 11 wherein said shaft means
comprises a cup-shaped member abutting said diaphragm and a
shaft abutting said cup-shaped member and extending through
said housing.
13. The actuator of claim 12 wherein said housing has
a cap at a second end, said shaft extending through said cap
and said biasing means extending between said cap and said
cup.

Description

FLOATING SEAL FOR FLUIDIC DEVICES
BACKGROUND OF THE IN~ENTION
This invention relates ~o ~loating seal~ for fluidic
devices and, particularly, to pneumatic actuators having a
diaphragm forming the seal between the actuator housing and
the air chamberO
Many prior art diaphragm devices have taken advantage
of their existing diaphragms to seal in the fluid to which the
diaphragms are responsiveO l'he seals are provided by compressing
the bead around the circum~erence of the diaphragm against the
device housing to insure that the fluid being sealed into the
fluid chamber defined by the diaphragm cannot escape from the
housing around the beadO This compression is applied to the
bead either by tightening a nu~ which presses the bead against
the housing or by using a spring or other suitable biasing means
to press the bead against the housing. Because a mechanism is
reguired to compress the bead against the device housing in these
prior art devices, assembly of such devices has proven to be more
complicated and costly than necessary. The present invention
reduces the complexity and cost of assembly of the device by
dispensing with the compressing mechanism and rather compressing
the bead against the housing by use of the 1uid which is supplied
to the ~luidic device. In this arrangement, the diaphragm and
the bead o the diaphragm are allowed to float in the housing
when no 1uid is supplied to the device.
SU~A~Y OF THE INVENTION
A fluidic device is provided ha~ing a housing, a
connector mounted within the housing having a nozzle extending
through the housing, the connector ~orming a clearance between
it and the housing, and a diaphragm mounted within the housing
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forming a fluid chamber within the device and haviny a bead
around the circumEerence of one end of the diaphragm, the bead
being positioned within the clearance between the connector and
the housing such that when fluid is supplied through the nozzle
to the fluid chamber, the fluid will force the bead into the
cl~arance to seal in the fluid within the fluid chamber formed
by the diaphragm. The connector, the housiny and the bead are
so dimensioned that, without fluid supplied to the nozzle, the
bead within the clearance is floating.
BRIEF DESCRIPTION OF ~HE DRAWINGS
These and other features and advantages will become
apparent from a detailed consideration of the drawings in which:
Figure 1 is a sectional view of a pneumatic actuator,
in its de-energization state, incorporating the invention;
: 15 ~i-gure 2 shows the device of Figure 1 in its energized
state; and,
Figure 3 is an end view of the housing of Figure 1.
DETAILED DESCRIPTION OF THE INVENTION
The fluidic device 10 shown in Figures 1 and 2 comprises
cylindrical cup-shaped housing 11 having its bottom 12 rolled
under and cut out leaving a plurality of burrs 13 and a ~ircular
cutout 14 as shown in Figure 3. A generally cup-shaped connector
15 has bead 16 at one end of the generally cup-shaped diaphragm 17
stretched over i~s circumference. After the diaphragm has been
stretched over connector 15, connector 15 is inserted through
opening 14 at end 12 of cylinder 11 such that bead 16 lies within
: clearance 18 formed between cylinder 11 and connector 15 as shown.
: Connector 15 has an annular recess 19 around its circumference
to form an annular tab 20 therearound. As the connector 15 is
inserted through opening 14 of end 12, burrs 13 of cylindrical
housing 11 snap over annular tab 20 of connector 15 and into
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recess l9.
The burrs :l3 of hous.iny 11 and the tab 20 of connector
15 are provided to prevent the connector 15 from being pushed
into housing 11 wh~n the piping is pushed onto nozzle 21 during
installation. ~owever, connector 15, end 12 of housing 11 and
bead 16 of diaphragm 17 are so formed that the connector 15 and
diaphragm 17 together with bead 16are 10ating inside the
housing 11; that is, there is no ~orce a~lied aqainst the
connector 15 to compress bead 16 between connector 16 and
housing 11. By allowiny ~e connector 15 and diaphragm 17 to
~ float within housing ll, the assembly of khe deviae 10 is made
,, . ~,
much less complicated and has eliminated the need for a separate
bead compressing device.
As fluid is supplied through nozzle 21 of connector
15 to chamber 40 formed by diaphragm 17, chamber 40 expands and
the fluid within diaphragm 17 forces bead 16 into clearance 18
formed between connector lS and housing 11.
It may be found that, for small input pressures to
nozzle 21, the pressure within chamber 40 is inadequate to force
bead 16 into the clearance sufficiently ~o form a fluid tight
seal; that is, when the input pressure isI~ess than 2 psi, for
example, a small leak may occur around bead 16. It has been
found that, when the input pressure exceeds 2 psi, there is
sufficient pressure within chamber 40 to force bead 16 into
clearance 18 to seal off any leakage. Thus, in order to prevent
leakage for input pressures less than 2 psi, for example, it
may be necessary to make the circumference of diaphragm 17 at
bead 16 slightly smaller than the circumference of connector 16
so that the diaphragm 17 must be stretched over connector 15
during assembly. Thus, an interference fit is formed between
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diaphragm 17 and connector 15 such that, at low input pressures,
or example, below 2 psi, the pressure within diaphragm 17 is
insufficient to move bead 16 away from connector 15.
To complete the assembl.y of the device 10, cup 30
is inserted lnto the housing 11 and against diaphragm 17 to
roll back diaphragm 17 as shown in Figure 1. A first biasing
spring 31 operates between a spring support 32 and a spring pad
33 attached to shaft 34. A second bi.asing spring 35 operates
between spring support 32 and end cap 36. End.cap 36 is roll
staked at 37 to cylindrical housing 11 and shaft 34 extends
therethrough. Biasing springs 31 and 35 bias shaft 34, cup 30
and diaphragm 17 to a de-energized position with no fluid supplied
at nozzle 21. This position of de-energization is insufficient,
however, to place an~ compression upon the bead 16 in clearance
18 between connector 15 and housing 11. Indeed, after final
assembly, connector 15 and diaphragm ].7 are.floating in the
housing 11 which means that there are no forces, in the de-
energization state of device 10l acting against bead 16.
In prior art devices, it was thought necessary to
provide some means to compress bead 16 into clearance 18 between
housing 11 and connector 15. In one such device, the biasing
spring 31 was made suficiently large to force cup 30 against
diaphragm 17, diaphragm 17 against connector 15 and connector 15
toward housing 11 to compress bead 16 into clearance 18. In
another device, a tightening nut was provided to draw connector
15 towards housing 11 as it was tightened to thus compress bead 16.
The present device 10 is much simpler to assemble
than prior art devices. There are no nuts to tighten in order
to compress bead 16 into clearance 18 and there are no tight
biasing springs to force the bead 16 into clearance 18 and at
the same time impede assembly by making it necessary to fight
the force of the springs.
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