Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
This invention relates to a valve and more particularly to a
rotary valve having a valve stem sealed by a bellows with the stem end
portions displaced in parallel relationship and rotatable connected to an
actuator having an axis aligned with the lower axis of the valve stem and
offset from the upper axis of the valve stem so that rotation is trays-
milted from the actuator to the valve stem through a pressure boundary
formed by the bellows.
In rotary valves, such as butterfly, ball, plug and the like for
conveyance of fluids and particularly contaminated fluids at high pros-
sure, as well as at substantially reduced pressure or under vacuum condo-
lions, it is preferred to utilize static seals as opposed to packed or
dynamic seals. Packed or dynamic seals are subject to wear and this
results in valve leakage, particularly at the pressure boundary between
the valve stem and the valve member. A commonly used static seal is a
bellows surrounding the valve stem. United States Patents 1,644,825;
2,659,569; 2,659,570 and 3,811,651 disclose valves that utilize a bellows
for sealing around the valve stem between the valve actuator and the valve
member.
Conventionally, a bellows, when used to seal a valve stem, is
bonded or welded to the structure of the valve body that supports the
rotatable valve member at one end and the opposite end to a retainer or
cap that connects the valve stem to the valve actuator. This arrange~Rnt
is illustrated in United States Patent 3,811,651. Because the connections
at the ends of the yellows are stationary, a static seal is formed. It is
known to laterally deflect the valve stem or utilize a crank-like valve
stem and hermetically seal the stem in the bellows. In this manner, the
valve stem connects the actuator to the valve member to produce rotational
cement of the valve member, as illustrated in United States Patents
1,644,825 and 3,811,651.
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~.2~315~
One of the difficulties encountered with bent valve stems
hermetically sealed in a bellows and operated by a crank-like actuator is
binding of the rotatable end of the valve stem positioned in the retainer
or cap within the valve actuator. Particularly in high pressure apply-
cations, the line pressure exerts an upward force upon the valve stem and
the bellows cap tending to laterally displace the valve stem and the
bellows cap. If the upper end of the valve stem and/or bellows cap
becomes laterally displaced with respect to the axis of rotation of the
actuator, frictional contact between the valve stem, bellows cap and the
retainer occurs and inhibits relative rotation between the actuator and
the valve stem. As a result, rotation of the actuator will not produce
rotation of the valve stem or rotation will be obstructed to such an
extent that the valve cannot be positively opened or closed.
While it has been suggested by the prior art devices to use a
bellows to hermetically seal a valve stem, the use of a bellows has only
been applicable as a static seal or an axially movable seal and not as a
rotary seal where the bellows is subjected to torsional loading. There-
fore, there is a need in rotary valves for a rotary seal of a valve stem
by a bellows that is connected to an actuator in a manner to permit
transmission of torque through the bellows to the valve stem while main-
twining a pressure boundary around the valve stem.
In accordance with the present invention, there is provided a
valve that includes a valve body and a passageway extending through the
valve body for the flow of fluid there through. A valve member is post-
toned in the passageway for cement between an open and a closed post-
lion to open and close the passageway. The valve member has an axis.
Actuating means rotatable about an axis coccal aligned with the valve
member axis moves the valve member between the open position and the
closed position. A unitary valve stem extends between the valve member
and the actuating means. The unitary valve stem has a lower end portion
31 Z~5~
in non rotatable engagement with the valve member and an upper end portion
connected to the actuating means for transmission of rotation from the
actuating means to the valve member. The valve stem upper end portion is
displaced from the valve stem lower end portion. m e valve stem lower end
portion has a lower axis aligned with the valve member axis and the
actuating means axis. The valve stem has an upper end portion orbited
- about the valve member axis as the actuating means is rotated to move the
valve member between the open and closed positions. A bearing assembly
retained in the actuating means supports the unitary valve stem upper end
portion for rotation relative to the actuating means. The bearing as-
symbol supports the unitary valve stem upper end portion to maintain the
valve stem upper end portion rotatable relative to the actuating means as
forces are applied to the valve stem. A bellows surrounds the unitary
valve stem. The bellows has a lower end portion and an upper end portion.
Means is provided for connecting the bellows lower end portion to the
valve body to provide a seal arolmd the valve stem lower end portion at
the valve body. The bellows upper end portion is connected to the bearing
assembly to permit relative rotation between the bellows upper end portion
and the actuating means and provide a seal around the valve stem upper end
portion.
A housing rotatable supports the actuating means and is con-
netted to the valve body. The housing encloses the bellows and is sealed
in surrounding relation with the actuating means and is connected to the
valve body to form a chamber around the bellows. The chamber forms a
secondary pressure boundary to back up the primary pressure boundary
provided by the bellows around the stem so that in the event of bellows
failure, the fluid and line pressure is contained within the chamber
formed by the housing.
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The housing and the valve body include cooperating guide means
for aligning the actuating means axis with the valve stem lower axis and
the valve member axis. The actuator is rotatable mounted in the housing.
The actuator includes an enlarged end portion having an axis eccentrically
positioned relative to the actuating means axis. The eke nitric axis of
the enlarged end portion is axially aligned with the valve stem upper end
portion axis. The bearing assembly is received within a recess of the
enlarged end portion. The bearing assembly maintains the valve stem upper
end portion axis parallel to the actuating means axis so that the valve
stem remains freely rotatable relative to the actuating means during
operation of the valve when the valve stem is exposed to the line pros-
sure.
The upper end portion of the bellows is preferably nominally
welded to the bearing assembly although other conventional sealing methods
are adaptable. Preferably, the bearing assembly includes a bellows cap
positioned in surrounding relation with the upper end of the valve stem
and within the recess of the actuating means enlarged end portion. A
first bearing member supports the bellows cap for relative rotation
between the actuating means enlarged end portion and the bellows cap. A
second bearing member is retained in the bellows cap and is positioned on
the valve stem upper end portion to permit the bellows cap to rotate
relative to the bellows upper end portion.
Torque is transmitted from the actuating means through the
bellows to the valve stem. The first and second bearing members of the
bearing assembly permit axial displacement and withstand axial forces of
the valve stem upper end portion in response to the line pressure exerted
upon the valve stem and prevent lateral displacement of the valve stem
upper end portion. The valve stem upper end portion is maintained in
spaced parallel relation with the actuating means axis to insure relative
rotation between the actuating means and the valve stem.
5~36
Accordingly, the principal object of the present invention is to
provide a rotary valve having a bent valve stem enclosed by a bent bellows
and connected by a bearing assembly to a valve actuator to permit trays-
mission of torque and rotary movement from the actuator through the
bearing assembly and bellows to the valve stem.
A further object of the present invention is to provide, in a
rotary valve, a valve actuator having a rotational axis offset and penal-
lot to the rotational axis of the valve stem where the valve stem is
sealed within a bellows and rotatable supported in the actuator by a
bearing assembly that provides relative rotational movement between the
valve stem and the actuator
Another object of the present invention is to provide a bent
bellows rotary valve mounted in a housing and connected to a valve act-
atop and including a guide means for maintaining the rotational axis of
the actuator aligned with a portion of the valve stem and valve member.
An additional object of the present invention is to provide, in
a rotary valve, a stop mechanism for permitting over travel of the valve
actuator but limiting movement of the valve member between a fully open
and a fully closed position.
These and other objects of the present invention will be more
completely disclosed and described in the following specification the
accompanying drawings and the appended claims.
Figure 1 is a sectional view, in side elevation, of a ball
valve, illustrating a bent valve stem hermetically sealed by a bellows
rotatable supported by the crank arm of a valve actuator.
Figure PA is an enlarged, fragmentary, sectional view of a
connection of the valve stem to the valve member, illustrating a dynamic
seal around the valve stem.
Figure 2 is a top plan view of the valve actuator, illustrating
the crank arm.
so
Figure 3 is a fragmentary view, in side elevation, taken along
the line III-III of Figure 2, illustrating a welded connection of the
bellows -to the valve body to form a hermetically sealed pressure boundary
around the lower end of the valve stem, the details of the connection of
the stem to the actuator being omitted.
Figure 4 is a view similar to Figure 3, illustrating another
embodiment of a stop mechanism for the valve stem.
Figure 5 is an enlarged, fragmentary, sectional view of the
valve stem and surrounding bellows, illustrating plating on the inner
surface of the bellows to reduce bellows wear.
Figure 6 is a fragmentary, schematic view of the bellows sun-
rounding the valve stem, illustrating a further embodiment of plating on
the inner surface of the bellows.
Figures 7 10 are fragmentary, schematic illustrations of various
embodiments for reducing frictional wear of the bellows by contact with
the valve stem.
; Figure 11 is a fragmentary, schematic illustration of a bellows
failure indicator adaptable for use with the present invention.
Referring to the drawings and particularly to Figures 1 and 2,
there is illustrated a valve assembly generally designated by the numeral
10 of the ball type for controlling the flow of fluid, either a liquid or
a gas, through a piping system. The valve assembly 10 includes a valve
body generally designated by the numeral 12 having a pair of conduit
portions 14 and 16 connected by bolts 18 to a central body portion 20.
The conduit portions 14 and 16 are received within a cavity 22 of the
central body portion. Positioned within the cavity 22 and abutting the
adjacent ends of the conduit portions 14 and 16 are valve seats 24. The
valve seats 24 are rigidly positioned in the cavity 22 by the central body
portion 20 and the conduits 14 and 16, thereby forming a valve chamber
generally designated by the numeral 26. Valve chamber 26 communicates
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Sue
with passageways 28 and 30 that extend through the conduit portions
14 and 16 respectively. The passageways 28 and 30 are aligned with the
passageways 32 that extend through the valve seats 24. The conduit
portions 14 and 16 are adaptable for connection to service conduits by any
suitable means, such as threading the service conduit into the end port
lions 14 and 16. In this manner, a continuous passageway is provided
through the valve assembly 10.
A rotatable mounted valve member 34 is connected to a valve stem
36 that is rotated by a valve actuator generally designated by the numeral
38. The valve member 34 illustrated in Figure 1 is characteristic of the
valve member utilized in ball-type valves, but it should be understood, in
accordance with the present invention, that other suitable rotary type
valve members may be utilized, such as a butterfly, plug and the like.
The valve member 34 includes a body portion 40 having an arcuate surface
42. The arcuate surface 42 remains in contact with the valve seats 24 as
the body portion 40 is rotated in the valve chamber 26. The body portion
40 has a through bore 44 movable into and out of alignment with the
passageways 28 and 30 of conduits 14 and 16 and passageway 32 of valve
seats 24 to permit the flow of fluid through the conduit portions 14 and
16 and central body portion 20. Rotation of the valve stem 36 through 90
moves the valve member 34 between the open and closed positions.
Movement of the valve member 34 between the open position, as
illustrated in Figure 1 and the closed position (not shown) is controlled
by orbital movement of the valve actuator 38 about an axis 46 which is
coccal aligned with a lower end portion 48 of the valve stem 36. m e
valve stem lower end portion 48 is nonrotatably connected to the valve
member 34. The valve stem lower end portion 48 and the valve member 34
are rotatable about an axis 50. As seen in Figure 1, axis 50 is coccal
aligned with the actuator axis 46. The valve stem 36 also includes an
upper end portion 52 connected to the valve actuator 38. The valve stem
~Z~95J~~
upper end portion 52 has an axis 54 which is laterally displaced from both
axes 46 and 50. Further, as illustrated in Figure 1, the axis 54 is
parallel to the axes 46 and 50. With this arrangement, the axis 54 is
eccentric to the axes 46 and 50. The valve stem upper end portion
52 is connected to the actuator 38 so that torque is transmitted from
the actuator 38 to the valve stem 36 and the valve member 34.
The valve stem 36 is a unitary member between the end portions
48 and 52 and has a preselected curvature which is a double or reversed
curvature. The valve stem upper end portion 52 is rotatable connected to
the actuator 38 by a bearing assembly generally designated by the numeral
56. A bellows 58 surrounds the valve stem 36 between the upper and lower
end portions 48 and 52. The bellows 58 has a generally cylindrical body
portion 60 unitary in length and comprising a circumferential Corey-
grated, axially extending, relatively thin cylindrical wall. Normally, the
bellows is not bent and, upon installation, bends to follow the shape of
the valve stem. Preferably, the bellows 58 is metallic, impermeable, and
sufficiently flexible to withstand the bending that occurs in operation.
The bellows 58 has a passageway 62 extending between a lower open end
portion 64 and an upper open end portion 66. Preferably, the bellows 58
has an inner diameter positioned closely adjacent to the outer die-
meter of the valve stem 36. In one example, the bellows inner diameter is
removed from the outer diameter of the valve stem by a distance equal to
10% of the valve stem diameter. With this arrangement, the valve stem 36
contacts and supports the bellows 58 to prevent lateral distortion or
"squirming" of the bellows 58 when subjected to internal and external
fluid pressure. The reverse curvature of the valve stem 36 results in
contact of the bellows 58 with the valve stem 36 and curvature of the
bellows 58 conforming to the curvature of the valve stem 36.
The bellows upper end portion 66 is connected to the actuator 38
to permit relative rotation between the actuator 38 and the bellows upper
I
end portion 66 for transmission of torque -from the actuator 38 through the
bellows 58 to the valve stem 36. The bellows upper end portion 66 is
axially aligned with the valve stem upper end portion 52 and is part of a
primary pressure boundary around the valve stem upper end portion 52. The
bellows lower end portion 64 is axially aligned with the valve stem lower
end portion 48 on the axis 50.
The bellows upper end portion 66 is connected, in a manner to be
explained later in greater detail, to the actuator 38 to form a primary
pressure boundary around the valve stem upper end portion 42. The bellows
layer end portion 66 is connected by a weld 67 to a bellows plate 68 to
form a primary pressure boundary around the valve stem lower end portion
48. The bellows plate 68 is suitably sealingly connected to the valve
central body portion 20 to provide a seal around the stem lower end
portion 48 at the point where the stem 36 extends from the central body
portion 20~
The bellows plate 68 includes a bore 69 through which the valve
stem 36 extends. The bore 69 is aligned with a bore 71 through the valve
central body portion 20 that receives the valve stem lower end portion
48. Positioned within the central body portion 20 and the bellows plate
68 is a suitable journal type bearing 70 or bushing. The bearing 70
rotatable supports the valve stem lower end portion 48 within the valve
central body portion 20 and the bellows plate 68.
The bellows plate 68 is suitably connected to the valve central
body portion 20. As illustrated in Figure 1, the bellows plate 68 is
connected by bolts 72 to the central body portion 20. Figures 3 and 4
illustrate an alternate embodiment of the connection of the bellows plate
68 to the central body portion 20. In Figures 3 and 4, the plate 68 is
shown connected by a circumferential weld at 74 on the upper surface of
the valve central body portion 20 around the bellows plate 68. This
arrangement forms a welded hermetic seal at the valve stem lower end
-- 10 --
5~3~
portion 48 for the 90 operation of the valve member 34. A static O-ring
seal 76, shown in Figure 1, is positioned between the bellows plate 68 and
the valve central body portion 20 to provide a seal there between and
around the valve stem lower end portion 48.
In a further embodiment illustrated in Figure PA, a dynamic
O-ring seal 77 is positioned in a recess of the valve central body portion
20 in surrounding and sealing engagement with the valve stem lower end
portion 48. The O-ring seal 77 has an inverted U shape which permits it to
expand outwardly into increased sealing engagement with the valve stem
lower end portion 48 in the event of fluid leakage between the valve seats
24 and the valve member 34. This one way seal prevents flow of fluid
upwardly around the valve stem 36 but allows pressure to escape from the
bellows 58 to the cavity 22. The seal 77 is operable to minimize the
pressure in the bellows to provide a safety margin for the bellows cycle
life. The seal 77 further promotes bellows cycle life by minimizing the
bellows/stem exposure to potentially abrasive or deleterious fluids in the
valve. The one way nature of the seal 77 prevents high pressure from
being trapped inside the bellows if the pressure in the valve decreases.
us illustrated in Figure 1, the actuator 38 includes a crank arm
78 rotatable about the axis 46. The crank arm 78 is rotatable supported
within an actuator housing 80 that is connected by bolts 82 in surrounding
relation with the bellows plate 68 to the upper surface of the valve
central body portion 20. The housing 80 forms a chamber 84 surrounding the
valve stem 35 and the bellows 58 and serves as a secondary pressure
boundary around the valve stem 36 to back up the primary pressure boundary
formed by the bellows 58 around the stem 36. With this arrangement, in the
event of any leakage around the valve stem 36 and through the bellows 58,
the housing 80 will contain the leakage and line pressure within the
chamber 84.
ISLE
A static seal is provided by an O-ring 86 between the flanged
lower end portion of the housing 80 and the upper surface of the valve
central body portion 20. Further, a dynamic seal is provided around the
crank arm 78 by an O-ring 88 retained within a recess of the reduced upper
end portion of the housing 80. The O-ring 88 sealingly engages the outer
surface of the crank arm 78.
Rotation is transmitted to the crank arm 78 by a handle 90 that
is nonrotatably connected to crank arm 78 by a nut and bolt combination
92. m us, turning the handle 90 through a preselected degree of rotation
rotates the crank arm 78 about the rotational axis 46 to orbit the valve
stem upper end portion 52 about the axis 46 and thereby rotate the valve
stem lower end portion 48 about the axis 50 to, in turn, rotate the valve
member 34 between the open and closed positions. The crank arm 78 in-
eludes an enlarged lower end portion 94 offset from the axis 46. The end
portion 94 is rotatable supported within the housing 80 by a bushing type
thrust bearing 96 operable to carry axial and radial thrust loads and
rotatable support the crank arm enlarged end portion 94. The thrust
bearing 96 is also operable to resist axial movement of -the enlarged lower
end portion 94 as the pressure increases within the bellows 58. The
enlarged end portion 94 includes a recess 98 in which the axis of the
recess 98 is aligned with the axis 54 of the stem upper end portion 52.
The recess 98 is offset from the rotational axis 46 of the crank arm 78 so
that the axis of the recess 98 is aligned with the axis 54 and is eccen-
tribally positioned relative to the actuator axis 46.
The bearing assembly 56 is positioned within the recess 98. The
bearing assembly 56 includes a handle bearing portion 100 which is prey-
drably a bushing type journal bearing operable to carry both radial and
thrust loads. The handle bearing 100 is retained within the recess 98 and,
in turn, receives a cup shaped bellows cap 102. The handle bearing 100
Cypriots the bellows cap 102 for rotation relative to the crank arm 78.
- 12 -
1.2~S~6
The bellows cap 102, in turn, receives a stem bearing 104 which is prey-
drably a bushing type journal bearing operable to carry radial loads. The
stem bearing 104 is positioned in surrounding relation with the valve stem
upper end portion 52 and permits the bellows cap 102 to rotate relative to
the valve stem upper end portion 52. The stem bearing 104 is positioned
on a stem shoulder 103 to position the bearing 104 on the stem upper end
portion 52 for axial movement of the bellows cap 102 in response to
upward axial forces exerted on the valve stem 36.
The bellows cap 102 is closed at one end portion to surround and
seal the valve stem upper end portion 52 within the recessed end portion
94 of the crank arm 78. The bellows cap 102 includes a flanged open end
portion positioned opposite the bellows upper end portion 66. The bellows
upper end portion 66 is welded at 106 to the flanged end of the bellows
cap 102. This arrangement permits relative rotation between the crank arm
78 and the bellows cap 102 welded to the bellows upper end portion 66.
Further relative rotation is permitted between the bellows cap 102 and
the valve stem upper end portion 52. By the combination of the thrust and
radial bearings 100 and 104, torque is transmitted from the crank arm 78
to the valve stem 36 as the valve stem upper end portion 52 orbits or
turns about the stationary rotational vertical axis 46 of the crank arm
78.
The welded connection of the bellows upper end portion 66 to the
flanged end of the bellows cap 102 around the valve stem upper end portion
52 hermetically seals the valve stem upper end portion 52 within the
housing 80. The welded connection provided at 106 between the bellows 58
and the bellows cap 102 forms a valve primary pressure boundary to prevent
the escape of line fluid and pressure around the valve stem 36. A second
defy pressure boundary is formed by the O-ring 88 sealingly positioned
between the housing 80 and crank arm 78. Thus, the crank arm 78 and
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3S8~
housing 80 not only function as a means for actuating the valve 10 but
also are operable in combination with O-ring 88 as a dynamic seal to back
up the primary pressure boundary provided by the bent bellows 58.
The housing 80 is operable, in the event of bellows failure or
any leak across the primary pressure boundary, to contain the fluid and
full line pressure within the chamber 84. This arrangement permits high
pressures and hazardous or contaminated fluids to be contained within the
valve assembly 10 and prevents their escape to the environment in the
event of a primary pressure boundary failure. One advantage of the
parallel offset between the axes 46 and 54 is a reduced clearance around
axis 46 for the crank arm 78. This permits the inside diameter of the
housing 80 and, therefore, the size of the chamber 84 to be substantially
reduced while at the same time serve as a back up pressure boundary.
Reducing the inside diameter of housing 80 permits the wall thickness of
housing 80 to be reduced without a decrease in the capability of the
housing 80 to withstand internal pressure. This provides a lighter and
less expensive secondary pressure boundary than otherwise permitted.
The housing 80 maintains the rotational axis of the crank arm 78
aligned with the axis 46 which is, in turn, aligned with the axis 50.
Rotation of the crank arm 78 about the rotational axis 46 is maintained
by the position of a flanged lower end portion 108 of the housing 80
within a recess 110 of the valve central body portion 20. The flanged end
portion 108 is guided into position on the valve central body portion 20
by engagement with the recess 110. Surfaces 112 of the housing end
portion 108 abut the wall of recess 110. In this manner, the housing 80
is precisely located on the central body portion 20 so that the axis of
rotation of the crank arm 78 is maintained in alignment with the axes 46
and 50. The bellows plate 68 is similarly aligned with axes 46 and 50 by
a radially abutting relationship with bearing 70. The bearing 70 is
aligned by a radially abutting relationship with bore 71 which is co-
axially aligned with axes 46 and 50.
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I S 8
Tub operate the valve assembly 10 and Ye the valve member 34
between the open and closed positions within the valve chamber 26, torque
is applied to the handle 90 to rotate the crank arm 78 about the axis 46
to, in turn, orbit the enlarged lower end portion 94 and the valve stem
upper end portion 52 about the axis 46. This initiates turning of the
valve stem lower end portion 48 about the axis 50 and rotation of the
valve member 34 about the axis 50. The bellows cap 102 also orbits with
the valve stem upper end portion 52 about the axis 46. Rotation of the
crank arm 78 is transmitted through the handle bearing 100, the bellows
cap 102 and the stem bearing 104 to the stem upper end portion 52. Thus,
rotation is transmitted by a force eccentrically applied to the stem
upper end portion 52. The valve actuating force is transmitted by torque
applied outside the primary and secondary pressure boundaries through the
bent bellows 58 to the valve member 34.
While the bellows cap 102 orbits around axis 46, it does not
rotate about axis 54. The primary pressure boundary elements including
the bellows 58 and bellows cap 102 are fixed from rotating relative to
axes 46 and 50; however, the bellows 58 flexes, permitting the bellows cap
102 to orbit in an arc around the axis 46. The end portion 94 and valve
stem upper end portion 52 rotate about the axes 46 and 50. The bearings
100 and 104 support the bellows cap 102 for rotation relative to the end
portion 94 and the stem upper end portion 52.
; Further in accordance with the present invention, the thrust
bearing 96, handle bearing 100, and the stem bearing 104 are provided with
sufficient length and structural strength to prevent binding of the
rotational connection of the valve stem upper end portion 52 to the
actuator 38. Thus, the various connecting parts there between are not
laterally displaced from the offset and parallel alignment as above
described. This maintains the actuator axis 46 in spaced parallel rota-
lion to the valve stem upper end portion axis 54.
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:31 2Z~95~36
In operation of the valve assembly 10 with the pressure in
cavity 22 greater than the pressure externally of housing 80, the bellows
58 is internally pressurized and consequently upward thrust forces are
exerted within the bellows upon the bearing assembly 56. However, it
should be understood that the present invention also is operable in low
pressure and vacuum conditions. The combination of the bearings 96, 100
and 104 resists the radial and thrust forces applied from the pressure
within the bellows 58 to maintain relative rotation between the crank arm
78 and the valve stem upper end portion 52. This arrangement of main-
twining the axes 96 and 54 parallel also permits axial movement of the valve stem upper end portion 52 during operation of the valve 10.
Also this arrangement does not exert a biasing force on the bellows 58,
thus there is no "spring back" effect on the bellows 58.
By maintaining the rotational axes 46 and 54 in spaced parallel
relation, a relatively conventional rotatable actuator, such as the handle
90 connected to the crank arm 78, is utilized with the present invention.
The torque applied to the handle 90 is transmitted by the crank arm 78 to
the offset crank art end portion 94 thereby transmitting a force to the
valve stem upper end portion 52 which is offset from the rotational force
transmitted to the crank arm 78. In addition, by providing both the valve
stem 36 and the bellows 58 with a double or reverse curvature, as thus-
treated in Figure 1, the parts connecting the valve stem upper end portion
52 to the actuator 38 are free of inclined or angled surfaces. By main-
twining these connections at either right angles or in spaced parallel
relation, axial movement between the valve stem 36 and the valve actuator
38 is taken up by the bearing assembly 56. The bearing assembly 56
maintains any displacement that occurs in an axial direction. This
eliminates any lateral forces acting on the valve stem upper end portion
52 which would otherwise tend to bind or cock the connection of the valve
stem upper end portion 52 to the crank arm 78 during rotation. In add-
- 16 -
~.~2~5~36
lion, fabrication of these surfaces is less costly because only con-
ventional parallel and perpendicular surfaces are required.
In operation, the bellows 58 is internally pressurized by the
pressure inside cavity 22. As a result, an acoordian, expansion effect
takes place on the bellows and the bellows 58 is urged to expand axially.
However, with the end portions of the bellows 58 axially fixed, the axial
forces acting on the bellows 58 are transmitted from the bellows upper end
portion 66 to the bellows cap 102. The bellows cap 102 is urged upwardly
in a direction parallel to the axis 46. This upward axial force applied
to the bellows cap 102 is taken up by the combination of radial and thrust
bearings, 96, 100 and 104 which provide for limited axial displacement of
the connected parts. Thus, by maintaining the rotational axes I and 54
in spaced parallel relation, any axial forces applied to the valve stem 36
and bellows 58 are taken up by the bearing assembly 56. The pressure
forces are maintained in an axial direction. The valve stem upper end
portion 52 remains rotatable relative to the crank arm 78. Forces acting
in a radial direction are restrained to prevent binding of the relatively
rotating parts.
Internally pressurizing the bellows 58 exerts upward and lateral
forces upon the bellows, generating rubbing or frictional engagement of
the inner surface of the bellows 58 with the outer surface of the valve
stem 36. In view of the fact that the valve stem 36 rotates within the
bellows 58 and contacts the inner surface of the bellows 58, the bellows
58 conforms to the configuration of the valve stem 36. The bent bellows
tends to be naturally unstable and, therefore, subject to distortion. The
instability of the bellows 58 is further compounded by the fact that the
bellows is internally pressurized. The total effect of bending the
bellows and internally pressurizing the bellows is to increase the Eric-
tonal contact of the bellows with the valve stem. Wear of the bellows
can result, thereby reducing the cycle life of the bellows and the
3 ~Z95~36
capability of the bellows to maintain a primary pressure boundary around
the valve stem 36.
As pressure is applied to the inside of the bellows 58, the
bellows will tend to deflect laterally or "squirm". A deficiency with any
bellows, especially an elongated, flexible bellows, is the limited maximum
internal pressure which the bellows can sustain. This is not based on the
bellows wall strength or rupture pressure but upon the "squirm" pressure,
which is lower than the bellows rupture pressure. The "squirm" pressure
is the pressure at which a straight, unsupported bellows deflects when
internally pressurized This action is comparable to a long slender rod
buckling under a compressive load.
To enhance the stability of the initially flexed bellows 58, a
reduced clearance is provided between the valve stem 36 and the bellows 58
to the extent that the bellows 58 is supported substantially along its
flexed length by the valve stem 36. In this manner, the valve stem 36
restrains uncontrolled buckling or "squirm" of the bellows 58. Preferably
the clearance between the outer surface of the valve stem 36 and the inner
surface of the bellows 58 distributes the surface contact between the
bellows and the valve stem over substantially the entire length of the
bellows.
By providing a maximized gradual curvature to the valve stem 36,
as illustrated in Figure 7 and thus to the bellows 58, the amount of
flexing of each bellows convolute is minimized. In the bent portion of
the bellows 58, each convolute is tilted or flexed toward either axis 46
or axis 54. As the bellows orbits around axis 54, each convolute main-
twins the same magnitude of flex but the orientation of flexing rotates to
correspond to the rotation of axis 54. The cyclic flexing of each con-
volume generates fatigue leading to bellows failure. I've internal pros-
sure will additionally influence the flexing cycle life. With the en-
rangement shown in Figure 7, however, the stem 36 and the bellows 58 are
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5B~
formed with a uniform curvature having a radius R in each bent portion, as
diagrammatically illustrated in figure 7. Each bent portion has the
same radius of curvature, R. Preferably, the two bent portions are
uninterrupted so that the reversed curvature has no intermediate straight
section. With this arrangement, the maximum radius of bellows curvature
is used to obtain a preselected offset of axes 50 and 54. Thus, by
maximizing the radius R of bellows curvature, the flex of each bellows
convolute is minimized to increase the cycle life of the bellows 58. The
bellows can withstand higher pressures, and increased torque can be
applied to the valve actuator 38 in the valve assembly 10 having a compact
configuration.
By increasing the area of contact between the valve stem 36 and
the bellows 58, the overall stability of the bellows 58 is increased and
localized distortion or buckling of the bellows at concentrated points is
eliminated. With the present invention, a substantial number of the
convolutions of the bellows 58 are in contact with a valve stem 36,
thereby minimizing buckling of the bellows 58 when internally pressurized.
Because of the relative rotary rubbing motion of the bellows and stem, it
is desirable to minimize the wear and friction between these two parts.
Wear of the bellows is undesirable primarily because the bellows is
relatively thin and only a minor amount of wear will diminish the bellows
wall thickness to a point resulting in bellows failure. Bellows wear is
also accelerated by the friction generated between the stem and bellows
when torque is applied to the stem.
To prevent wear of the bellows 58 by contact with the valve stem
36, the stem 36 is provided with a low friction outer surface or stem
coating. Figures 8-10 illustrate various embodiments of the bent valve
stem having a low friction outer surface adaptable for supporting a
bellows with a minimum of wear in accordance with the present invention.
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Z~:~S~36
As the valve assembly 10 is operated to rotate the valve member
34, the bellows 58 flexes around the valve stem 36 as the stem rotates
within the bellows 58. The bellows 58 does not rotate but the stem 36
rotates relative to the bellows 58. Both the valve stem upper end portion
52 and the bellows upper end portion 66 orbit about the axis 46. The
valve stem upper end portion 52 rotates relative to the valve central body
portion 20 during said orbital movement, but the bellows upper end portion
66 does not rotate during the orbital movement. Subsequently, a rubbing
motion is generated between the valve stem 36 and the bellows 58.
I The friction generated between the valve stem 36 and the bellows
58 can also be reduced by the application of a wear resistant stem coating
or stem plating. For example, as illustrated in Figure 8, a wear nests-
lent material, such as a plastic material in the form of a sleeve 118 is
molded in surrounding relation with the embodiment of a valve stem 120
having a reduced outer diameter and enlarged shoulder end portions 122 and
124 for receiving the sleeve 118. Preferably, the sleeve 118 is molded or
bonded to the outer surface of the valve stem 120. Most preferably, the
sleeve 118 is fabricated of a material which is deformable or resilient in
order to reduce the friction between the bellows and the sleeve 118.
A further embodiment of a wear resistant surface around the
valve stem is illustrated in Figure 9, in which a valve stem 126 is
surrounded by a plurality of resilient rings 128 fabricated of a suitable
deformable material, such as plastic. In one embodiment, the rings 128
are split and if. another embodiment, the rings 128 are unitary. The rings
128 are arranged in a stacked relation on the stem 126. The bellows (not
shown) engages the rings 128 which serve to reduce the friction generated
between stem 126 and the bellows.
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.
So;
Figure 10 illustrates another embodiment of a valve stem 130
having a wear resistant plating 132 deposited thereon for supporting the
bellows with a minimum of wear of the valve stem 130. In this manner, the
plating 132 provides a build-up of metal on the valve stem 130 which
conforms to the bent configuration of the valve stem. Further, the
plating 132 may be fabricated of a material that is softer than the
material of the bellows so that the plate 132 wears and not the bellows
around the plate 132. The plating 132 in another embodiment is a material
harder than the material of the bellows so that frictional forces and wear
of the bellows 58 and plating 132 is reduced.
Another approach to preventing wear of the bellows by frictional
engagement with the valve stem is to plate the inner surface of the
bellows. Figure 6 illustrates a bellows 134 positioned in surrounding
relation with a valve stem 136. The bellows 134 includes an inner surface
which is built up by the addition of plating 138 formed integral with the
bellows 134. m e plating 138 may be fabricated of either a material
softer than the material of the valve stem 136 or harder than the material
of the valve stem 136.
As is well known, a bellows is formed of a plurality of con-
volitions 140. Because of the nature of plating irregular surfaces specifically the inner surface of the bellows convolutions 140, an in-
creased material thickness is formed on the sharply curved inner surfaces
where wear of the convolutions 140 is the sty severe. Thus, by plating
the inner surface of the bellows, a maximum plating thickness is provided
where the wear is the greatest, i.e. at the convolutions where the bellows
rubs against the valve stem.
In accordance with the present invention, the convoluted struck
lure of the bellows may be designed to reduce the wear of the bellows due
to frictional engagement with the valve stem. Referring to Figure 5,
there is illustrated a valve stem 142 surrounded by a bellows generally
designated by the numeral 144. The bellows 144 is fabricated of a pro-
selected material, such as metal, and includes a plurality of convolutions
146 having a preselected radii. Each convolution 146 includes horizon-
tally extending surfaces 148 formed integral with vertically extending
sections 150 to thereby connect adjacent convolutions The vertically
extending sections or flats 150 between the convolutions 146 have an inner
surface positioned opposite the outer surface of the valve stem.
A suitable wear resistant material 152, as illustrated in Figure
5, may be bonded or secured to the inner surfaces of the vertically
extending sections 150. In this manner, the arcuately shaped convolutions
146 are moved from contact with the valve stem and the sections 150 that
extend in an axial direction parallel to the axis of the valve stem are
the only sections of the bellows 134 engage able with the valve steno m e
parallel alignment of the sections 150 with the axis of the valve stem 142
minimizes wear of the bellows by distributing frictional engagement of the
valve stem 142 with the bellows 144 over a greater surface area of the
bellows, i.e. over the wear resistant sections 150.
Figure 7 illustrates bearing support of the valve stem 36 by a
plurality of ball bearings generally designated by the numerals 114 and
116 positioned in surrounding relation with the valve stem end portions 48
and 52. The bellows (not shown in Figure 7) is positioned in surrounding
relation on the stem 36. The ball bearings 114 and 116 can be used in lieu
of bearings 70 and 104 illustrated in Figure 1. In a similar manner,
thrust or radial ball bearings can be used in lieu of bearings 96 and 100
in Figure 1. The ball bearings 114 and 116 function as rotational wear
resistant devices operable to reduce friction. As further illustrated in
Figure 7, the valve stem upper end portion 52 does not require a stem
shoulder to maintain the ball bearings 114 in place.
Now referring to Figures 2 and 3, there is illustrated a first
embodiment of apparatus for limiting rotation of the valve actuator 30 to
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~95~?~
move the valve member 34 between the open and closed positions in the
valve chamber 26. Figures 2 and 3 schematically illustrate the crank arm
78 with the details of the connection of the valve Stern 36 and the bellows
58 to the crank arm 78 omitted to more clearly illustrate a valve stop
mechanism generally designated by the numeral 154. In the embodiment
shown in Figures 2 and 3, the valve stop mechanism 154 is operable to
limit rotation of the actuator 38 and the valve stem 36 to 90 rotation
between the open and closed positions.
As described above, the crank arm 78 includes the enlarged end
portion 94 which is eccentrically positioned relative to the rotational
axis 46 of the crank arm 78. Thus, the enlarged end portion 94 has a
peripheral surface positioned closely adjacent to the inner surface of the
actuator housing 80. The stop mechanism 154 includes a pair of pretty-
baronesses 156 that are secured to and extend inwardly from the wall of the
housing 80. The protuberances 156 are positioned at an elevation on the
housing 80 so that they project inwardly and oppositely of the periphery
of the enlarged end portion 94. When the handle 90 is turned, the en-
tanged end portion 94 contacts the protuberances 156 obstructing further
rotation of the crank arm 78 and the valve stem 36.
Preferably, the protuberances 156 are spaced on the housing 80
to permit unobstructed rotation of the crank arm 78 through a 90 angle.
When the handle is rotated to the extent that the enlarged end portion 94
is moved into abutting relation with the protuberance 158, the valve
assembly 10 is in the closed position. Accordingly, rotation of the
handle 90 in the opposite direction moves the enlarged end portion 94 out
of contact with the protuberance 156 and toward and eventually into
contact with the protuberance 156. Rotation of the handle 90 in this
direction moves the valve member 34 from the open position illustrated in
Figure 1 to a closed position where the valve member 34 blocks flow
through the valve chamber 26.
- 23 -
In order to insure that the through bore 44 of the valve body 40
is aligned with the passageways 28 and 30 to open the valve 10, the
protuberance 156 must be located at the selected Fount on the interior
wall of the housing 80 where contact of the protuberance with the enlarged
end portion 94 corresponds to the position where the bore 44 is aligned
with the passageways 28 and 30. Also, the protuberance 158 must be
positioned at the point on the interior wall of the housing 80 where, when
contacted by the enlarged end portion 94, the solid faces of the valve
member 34 have been moved into a position within the chamber 26 obstruct
tying flow between the passageways 28 and 30. In this manner, the valve
member 34 is limited to rotation through 90 where the end points of
rotation of the valve member 34 correspond to the open and closed post-
lions of the valve.
Now referring to Figure 4, there is illustrated another embody
immunity of a valve stop mechanism generally designated by the numeral 160
for limiting rotation of the valve stem 36 to, in turn, control rotation
of the valve member 34 and assure that the valve member is positively
moved between the open and closed positions. The valve stop mechanism 160
illustrated in Figure 4 includes an annular recess 162 formed in the
bellows plate 68 in surrounding relation with the valve stem lower end
portion 142. The bellows plate 68 is sealingly engaged to the valve
central body portion 20 by the circumferential weld 74 that extends
completely around the periphery of the bellows plate 68 or any other
suitable static seals. To limit the valve stem 36 to 90 rotation, a pair
of stop pins 164 (only one of which is illustrated in Figure 4) extends
upwardly from the valve central body portion 20 into the annular recess
162. Secured to and extending outwardly from the valve stem 36 is a pin
166. The pin 166 has a length which permits the pin 166 to extend out-
warmly from the stem 36 a distance greater than the spacing of the stop
pin 164 from the stem 36.
- 24 -
Lo S~36
The stop pins 164 are precisely located on the central body
portion 20 within the annular recess 162 so that when the pin 166 is in
contact with either stop pin 164, the valve member 34 is either in the
open or closed position. The pin 166 engaging the pin 164, as shown in
Figure 4, corresponds to the open position of the valve. Depending on the
design clearances between the several actuator parts, significant "play"
may exist between the handle 90 and the valve member 34. This results in
greater than 90 rotation of the handle 90, such as 100 rotation, to move
the valve member 34 between the open and closed positions. However, the
handle 90 is turned until rotation is obstructed by contact with the roll
pin 166 with either one of the stop pins 164. Thus, the handle 90 is not
limited to precisely 90 rotation and "play" may occur in the handle as
the valve member 34 is positively rotated through 90 into and out of the
open and closed positions of the valve. The operator may find that
between the open and closed positions of the valve, the handle 90 rotates
through an angle greater than 90. However, the end limits of rotation of
the valve stem 36 precisely locate the valve member 34 in either the open
or closed position.
Now referring to Figure 11, there is schematically illustrated
another embodiment of the stem housing 80 which surrounds the bellows 58
and the valve stem 36. As illustrated in Figures 1, 3 and 4, the housing
80 forms the chamber 84 around the bellows 58. The chamber 84 serves as a
secondary pressure boundary to back up the primary pressure boundary
provided by the bellows 58 around the valve stem 36. In operation, the
chamber 84 is not pressurized unless the primary pressure boundary pro-
voided by the bellows 58 fails. Therefore, a bellows failure indicator
generally designated by the numeral 168 in Figure 11 is provided on the
housing 80 to sense a pressure buildup within the chamber 84. A buildup
of pressure within the chamber 84 indicates failure of the bellows 58
to prevent fluid leakage around the valve stem 36. The bellows failure
- 25
I
indicator 16~ preferably includes a pressure yuage, a pressure switch, or
any other device operable to indicate that the bellows 58 has failed and
fluid is leaking between the bellows 58 and the valve stem 36. The
indicator 168 is suitably connected to the housing 80. An opening 170
through the housing permits the indicator 168 to be exposed to the pros-
sure conditions within the chamber 84.
According to the provisions of the patent statutes, I have
explained the principle, preferred construction and mode of operation of
my invention and have illustrated and described what I now consider to
represent its best embodiments. However, it should be understood that,
within the scope of the appended claims, the invention may be practiced
otherwise than as specifically illustrated and described.
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