Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF q~HE INVENq!ION
This invention relates generally as indicated to a
sealed mo~ion transmitter, especially suited for u~e with fluid
power devices and the like, for ~ransferring motion from the
exterior to an enclosed, fluid pressurized portion of the de-
vice with low frictional resistance and low leakage.
The design of fluid power devices frequently requixes
the transfer of motion or movement to an enclosed, fluid pres-
surized portion of the device from the exterior or from anothar
isolated portion of the device. It is desirable that the fric-
tional resistance to such movement ~e kept to a minimum to
reduce the act~ation force necessary to transfer motion, while
at the same time minimizing leakage from the fluid pressurized
portion to the exterior or other isolated portion of the de-
vice.
Heretofore, the most frequently used actuator for
this purpose was a push-pull rod which enters the enclosed,
fluid pressurized portion of the device through an opening which
is sealed with an O-ring or the like. To transer motion to
the enclosed portion of the device, the rod is simply moved
back and forth with the compressed seal wiping the rod as i~
passes therethrough. This requires ~he application of un-
desired hi~h forces to overcome the relatively high frictional
re~istance between the seal and rod. Other known types o
seals have been used to reduce the frictional resistance of
these devices, but usually at a sacrifice in increased leakage,
and~or substantially increased cost and complexity o the
seals. An example of a much more complex seal bet~een two
fluid mediums which allows for pivotal movement of a lever is
shown in U. S. Patent No. 3,721,453.
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SUMMARY OF THE INVENTION
With the..foregoing in mind, it is a principal object
of this invention to provide a sealed motion transmitter ~or
transmitting motion to an enclosed, fluid pressurized portion
of a device from the exterior or another portion of the device
providing a combination of low leakage and low actuation force.
Another object is to provide such a sealed motion
transmitter that is highly reliable and relatively inexpensive
to manufacture.
These and other objects of the present invention may
be achieved by providing a sealed motion transmitter which may
be used in combination with a fluid control device. The housing
of the sealed motion transmitter has an inner chamber adapted
for communication with a pressurized portion of the fluid
control device and an enlarged chamber adjacent the inner
chamber, with a shaft extending into and without the inner ... ^
chamber, respectively. The shaft has an intermediate ball
portion supported by axially spaced apart spherical bearings
in the enlarged chamber adjacent the inner chamber, whereby
one of the shaft ends is movable within the inner chamber and
the other shaft end is movable without the inner chambe.r. Seal
means interposed between the spherical bearings cooperate with
the ball portion of the shaft, the adjacent ends of the
spherical bearings, and the enlarged chamber of the housing
for fluidically isolating the shaft ends.
To the accomplishment of the foregoing and related
ends, the invention, then comprises the features hereinafter
fully described and particularly pointed out in the claims,
the following description and the annexed drawings setting
forth in detail a certain illustrative embodiment of the inven-
tion, this being indicative, however, of but one of the variousways in which the principles of the invention may be employed.
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BRIEF DESCRIPTION OF THE DRAWINGS
In the annexed ~rawings:
Fig~ 1 is a fragmentary sectional view through a
preferred form of sealed motion transmitter constructed in
accordance with this invention shown operatively connected to
a conventional fluid power or control device or the like
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Fig. 2 is an enlargement of the sealed motion trans-
mitter of Fig. l; and
Fig. 3 is an end view of the sealed motion trans-
mitter, as seen from the plane of the line 3-3 of Fig. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in detail to the drawings, and initially
to Fig. 1 thereof, there is illustrated a sealed motion trans-
mitter 10 constructed in accordance with the present invention
operatively connected to a fluid power or control device 11 ox
the like, only a portion of which is shown for exemplary pur-
poses. The sealed motion ~ransmi~ter comprises a housing 12
which may be an integral part of the housing for the fluid
power device 11 as illustrated, or may be a separate unit suit-
ably mounted thereon.
The housing 12 includes an interior chamber 14 in
which a ball shaft or movable member 15 is in~ermediately mounted
for pivotal movement by a pivot-seal structure 16. One end of
the shaft 15 forms an inner arm 17 that is free to move in an
inner portion 18 of the interior chamber 14. This inner portion
18, which may com~unicate directly wi~h the 1uid pre~surized
portion 19 of the fluid power device 11, is desirably generally
cylindrical, or if greater movement is desired, it may be
~apered as shown by the phantom lines 20 in Fig. 2 so that the
diameter of the inner portion of the interior chamber increases
away from the pivot-seal structure 16. The other end of the
shaft 15 forms an outer arm 21 at the opposite side of the
pivot-seal structure from the inner portion and either projects
outwardly of the exterior of the housing or to another portion
of the fluid control device.
As shown in ~ig. 1, the distal end 22 o the
inner ~rm 17 may be rounded or ball shaped and disposed in a
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bore 23 in an actuator arm, piston rod or other movable member
24 of the fluid power device. The actuator arm 24 may be gene-
rally constrained for linear movement in a plane generally
perpendicular to the longitudinal axis of the shaf~ 15. The
outer arm 21 may be suitably connected to linkages or to another
actuator, not shown.
As best seen in Fig. 2~ the pivot-seal structure 1~
comprises spaced-apar~ inner and outer spherical bearings 25 and
26, respectively, ~he spherical bearing surfaces 28 and 29 of
which support the intermediate spherical portion 27 of the shaft
15. To allow for greater pivotal movement of the shaft, the
re~pective edges 30 and 31 of the inner a~d outer bearings adja-
cent the bearing surfaces may be beveled as shown.
The bearings are preferably made of a suitable plastic,
for example, Torlon #4301 polyamide-imi~e, manufactured by
Amoco Chemical Corporation. However, it should be understood
that numerous other plastics and coated metals may also be used.
To prevent leakage of fluid from the pressurized por-
tion of the device, the seal 32 is interposed in the space 33
between the spherical bearings 25, 26. The seal 32 comprises a
ring which conorms to the periphery of the spherical portion
27 of the shat adjacent thereto and fluidically separates the
respective ends o the shaft. Preferably, the ring seal 32 is
made of an elastomeric material, and is either in the form of a
conventional O-ring or more preferably a "quadl' ring seal which
provides low friction combined with negligible leakage. How-
ever, various other types of seals or packings may also be used.
The bearings and seal are contained in an enlarged
cylindrical portion 34 of the interior chamber 14 adjacent the
inner portion 18 thereof, which forms a sho~lder 35 at the
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intersection of the two portions. The enlarged por~ion 34
opens outwardly ~rom the shoulder 3S to the exterior of the
housing 12 so tha~ the bearings 25, 26 and saal 32 may be readily
assembled therein. A cover 36 secured to the exterior of the
housing by means of screws 37 or the like retains the bearings
and seal in the desired assembled relation within the enlarged
portion 34. An opening 38 is provided in the cover through
which the shaft outer arm portion 21 projects, with the size of
the opening being sufficient to allow for adequate movement of
the outer arm.
To eliminate axial play of the ball sha~t, the bear-
ings 25, 26 are desirably preloaded by means of a wave spring
washer 39 or the like disposed between the inner bearings 25 and
shoulder 35.
As will be apparent, the sealed motion transmitter
conveys motion, applied at substantially right angles to the
shaft center line, to an enclosed, fluid pressuriæed portion of
the device from the exterior thereof, or vice versa, with low
frictional resistance and low leakage. Thus, for example,
~0 movement of the outer arm will result in similar but mirrored
movement of the inner arm which in turn effects linear movement
of the actuator arm 24. In similar fashion, movement of the
arm 24 will effect movement of the outer arm and linka~es con-
nected thereto. It will also be appreciated that the transmitter
may be used in various other ways ~o e~fec~ more complex move-
ments as the shaft is not limited to pivotal movement in only
one plane.
Although the invention has been shown and described
with respect to a preferred embodiment, it is obvious that
equivalent alterations and modifications will occur to others
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skilled in the art upon the reaaing ana unaerstanding of the
specification. The present invention includes all such equi-
valent alterations and modifica~ions, and is limited only by
the scope of the claims.
