Note: Descriptions are shown in the official language in which they were submitted.
1
PRESSURE ASSISTED CONNECTION FOR A VALVE SHAFT
LCHNICAL FIELD
[0001] This relates generally to control mechanisms for valves, and in
particular, to valve
shaft connections.
BACKGROUND
[0002] Rotary Control Valves are used extensively in various process control
applications.
A shaft is typically fixed to a controlling member using a tapered pin or key
inserted
peipenclicular to the centerline of the shaft. It is desirable in control
valve applications to have
a shaft connection that does not allow any hysteresis. For tapered pin type
connections, the
shaft and controlling member must be assembled as a matched set. A tapered
reamer is used
to machine the con-ect size of taper to match the taper pin. During assembly,
the tapered pin is
forcibly inserted into the tapered hole and effectively wedged in place. A
tapered key uses a
tapered flat surface machined longitudinally onto a round bar creating a half
round tapered
pin. Assembly of the shaft to the controlling member requires the key to be
forcibly inserted
and effectively wedged in place. Both designs rely on the wedging effect of
the key or pin to
stay in place. United States patent no_ 4,768,750 (Wilson) entitled "Valve
joint connection" is
an example of a ball valve that uses a tapered wedge to lock the shaft to the
valve member. It
.. is not uncommon for these types of wedged pins to come loose when subjected
to repeated
cycles especially when torques are higher
SUMMARY
[0003] According to an aspect, there is provided a valve, comprising a
valve closure
member in a valve housing, a shaft having a first end and a second end, the
first end being
received within a shaft-receiving aperture of the valve closure member, and
the second end
extending out of the valve housing, one or more locking apertures defined by a
first portion
formed in an inner surface of the shaft-receiving aperture of the valve
closure member and a
second portion formed in an outer surface of the shaft, the locking apertures
being angled
.. outward from an axis of the shaft and toward the first end of the shaft,
and one or more
locking members, each locking member being inserted into one of the locking
apertures and
engaging the first portion and the second portion of the respective locking
aperture, the
locking member securing the position of the shaft relative to the valve
closure member such
Date Recue/Date Received 2020-12-18
CA 2964618 2017-04-20
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that rotation of the shaft rotates the valve closure member between an open
position and a
closed position and such that internal pressure from within the valve housing
increases the
engagement between the locking members and the locking apertures.
[0004] According to another aspect, the valve may comprise two or more
locking
apertures and two or more locking members.
[0005] According to another aspect, the two or more locking apertures may
be spaced
evenly about a circumference of the shaft.
[0006] According to another aspect, the valve may further comprise a
retainer that
threadably engages the shaft-receiving aperture and retains the first end of
the shaft.
[0007] According to another aspect, the first end of the shaft may have an
outer diameter
that is less than an inner diameter of the shaft-receiving apertures such that
the first end of the
shaft is insertable through the shaft-receiving apertures prior to the locking
members being
inserted into the locking. apertures.
[0008] According to another aspect, the one or more locking apertures may
be
exclusively accessible via an inner cavity of the valve housing when the shaft
is received
within the shaft receiving aperture.
[0009] According to another aspect, the valve closure member may be a ball
valve.
[0010] According to an aspect, there is provided a method of assembling a
valve
comprising inserting a valve closure member into a valve housing, inserting a
first end of a
shaft through the valve housing and the valve closure member such that the
first end is
received within a shaft-receiving aperture of the valve closure member and
such that a second
end of the shaft extends out of the valve housing, and installing one or more
locking members
in one or more locking apertures, each locking aperture being defined by a
first portion
formed in an inner surface of the shaft-receiving aperture of the valve
closure member and a
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second portion formed in an outer surface of the shaft, each locking aperture
being angled
outward from an axis of the shaft and toward the first end of the shaft,
wherein each locking
member engages the first portion and the second portion of the respective
locking aperture to
secure the position of the shaft relative to the valve closure member such
that rotation of the
shaft rotates the valve closure member between an open position and a closed
position and
such that internal pressure from within the valve housing increases the
engagement between
the one or more locking members and the one or more locking apertures.
[0011] According to another aspect, the one or more locking
apertures may comprise two
or more locking apertures and the one or more locking members may comprise two
or more
locking members.
[0012] According to another aspect, the two or more locking
apertures are spaced evenly
about a circumference of the shaft.
[0013] According to another aspect, installing locking
members may further comprise the
step of installing a retainer, the retainer thrcadably engaging the shaft-
receiving aperture and
= retaining the first end of the shaft.
[0014] According to another aspect, the first end of the shaft may have an
outer diameter
that is less than an inner diameter of the shaft-receiving apertures.
[0015] According to another aspect, the one or more locking
apertures may be
exclusively accessible via an inner cavity of the valve housing when the shaft
is received
within the shaft receiving aperture.
[0016] According to another aspect, the valve closure member
may be a ball valve.
[0017] In other aspects, the features described above may be
combined together in any
reasonable combination as will be recognized by those skilled in the art.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0018] These and other features will become more apparent
from the following
description in which reference is made to the appended drawings, the drawings
are for the
purpose of illustration only and are not intended to be in any way limiting,
wherein:
FIG. 1 is a perspective view of a valve closure member.
FIG. 2 is a side elevation view of the valve closure member of FIG. 1.
FIG. 3 is a top sectional view of the valve closure member of FIG. 1, taken
= through the line A-A of FIG. 2.
FIG. 4 is a front sectional view of the valve closure member of FIG. 1, taken
through line B-B of FIG. 2.
FIG. 5 is a partial side sectional view of a valve closure member in a closed
position within a valve housing.
FIG. 6 is a partial side sectional view of a valve closure member in a closed
position within a valve housing.
= 15
DETAILED DESCRIPTION
[0019] A valve generally identified by reference numeral 10,
will now be described with
reference to FIG. 1 through FIG. 6.
[0020] Referring to FIG. 5, valve 10 is made up of valve closure member 12,
valve
housing 14, and shaft 16. Shaft 16 has a first end 18 and a second end 20,
where first end 18 is
= received within shaft-receiving aperture 22 of valve closure member 12
and second end 20
extends out of valve housing 14. Valve 10 also preferably has packing 23 or
other elements to
prevent leaks, as is known in the art. The design as shown and discussed below
was
developed for use in a ball valve. However, it will be understood that the
design may he
adapted to be used with other types of valves that open and close by rotating
a closure
member using a shaft.
[0021] Referring to FIG. 4, locking apertures 24 are
provided, defined by first portion 26
formed in an inner surface of shaft-receiving aperture 22 and second portion
28 formed in an
outer surface of shaft 16. The number of locking apertures 24 provided will
depending on the
preferences of the user and the requirements of the application. There may be
a single locking
CA 2964618 2017-04-20
aperture 24, however, as shown in FIG. 4, two locking apertures 24 that are
spaced evenly
about a circumference 34 of shaft 16 are preferred. While this design has many
advantages,
there may be more than two apertures 24, and apertures 24 need not be evenly
spaced.
Locking apertures 24 receive locking members 30 such that locking members 30
engage both
5 first and second portions 26 and 28. It has been lbund that a design with
two apertures 24 is
convenient as it balances the design, while minimizing the number of required
parts and
manufacturing requirements.
[0022] Referring to FIG. 3, locking apertures 24 are angled outward from
an axis 32 of
shaft 16 toward first end 18 of shaft 16. Each locking aperture 24 receives a
locking member
30 that is inserted such that it engages first and second portions 26 and of
the respective
locking aperture 24. Locking members 30 secure the position of shaft 16
relative to valve
closure member 12, allowing valve closure member 12 to be rotate between an
open position,
as shown in FIG. 6 and a closed position as shown in FIG. 5 by rotating shaft
16, which
extends out of valve housing 14. To maximize the engagement between apertures
24 and
locking members 30, first and second portions 26 and 28 are preferably of
equal size, such
that locking member 30 is equally engaged by both. This may change, depending
on the
preferences of the user and design requirements, so long as the engagement is
sufficiently
strong to support the engagement between shaft 16 and valve closure member 12.
[0023] Referring to FIG. 3, the internal pressure, represented hy an
arrow, is applied from
within valve housing 14 against first end 18 of shaft 16, which, due to the
angle of locking
apertures 24 and locking members 30, increases the engagement between locking
members
and locking apertures 24. In order to ensure that locking members 30 and shaft
12 do not
25 move into valve closure member 12 during shipping or assembly, or when
internal pressure is
not being applied, valve 10 may also have a retainer 36 that engages shaft
receiving aperture
22 and retains first end 18 of shaft 16. As shown in FIG. 1, retainer 36 may
have threads 38
that engage threads 40 on shaft receiving aperture 22 to install retainer 36.
It will be
understood that retainer 36 may be omitted, or replaced with another design.
[0024] While the angle of locking apertures 24 and locking members 30 act
to lock shaft
16 relative to valve closure member 12, shaft 16 is designed such that first
end 18 may be
6
installed from the outside of valve housing 14 with valve closure member 16
positioned
within valve housing 14. In particular, first end 18 of shaft 16 is sized such
that the outer
diameter is less than the inner diameter of shaft receiving aperture 22. This
allows first end
18 of shaft 16 to be inserted through shaft-receiving aperture 22 prior to
locking members 30
being inserted into locking apertures 24. Locking apertures 24 are accessible,
and preferably
exclusively accessible, via inner cavity 42 of the valve housing 14 when first
end 18 of shaft
16 is received within shaft receiving aperture 22. In this way, shaft 16 may
be inserted into
valve closure member 12 from the outside, and then secured in place by
installing locking
members 30, which are angled to reduce the likelihood of a loose connection.
Placing locking
apertures 24 and locking members 30 in this manner may allow for locking
members 30 to be
secured such that they cannot fall out of place while shaft 16 is in place.
This placement of
locking members 30 relative to shaft 16 may also prevent shaft 16 from being
able to be
forced out of shaft-receiving aperture 22 when pressure is applied within
valve housing 14.
This may further serve to prevent shaft 16 from being launched out of valve
housing 14 when
high pressures are involved.
[0025] A method of assembling valve 10 will now be described. Valve
closure member
12 is inserted into valve housing 14, and first end 18 of shaft 16 is inserted
through valve
housing 14 and valve closure member 12 such that first end 18 of shaft 16 is
received within
shaft-receiving aperture 22 of valve closure member 12, and such that second
end 20 of shaft
16 extends out of valve housing 14. Locking members 30 are installed in the
one or more
locking apertures 24. Referring to FIG. 5, it can be seen that the size and
shape of locking
apertures 24 may be such that locking members 30 may only be inserted from
inner cavity 42
of valve housing 14. Once inserted, locking members 30 engage first portion 26
and second
portion 28 of respective locking apertures 24 to secure the position of shaft
16 relative to
valve closure member 12 such that rotation of shaft 16 rotates valve closure
member 12
between an open position, as shown in FIG. 6, and a closed position, as shown
in FIG. 5, and
such that internal pressure from within valve housing 14 increases engagement
between
locking members 30 and locking apertures 24 to prevent a loose connection.
Installing
locking members 30 may further have the step of installing retainer 36 to
retain first end 18 of
shaft 16, such as by threadably engaging shaft-receiving aperture 22.
Date Recue/Date Received 2020-08-25
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[0026] In some
embodiments, first portion 26 of locking aperture 24 may be two radiused
slots machined 180 degrees apart into shaft-receiving aperture 22 of valve
closure member 12.
Second portion 28 of locking apertures 24 may be two identical radiused slots
machined
longitudinally along the center line of shaft 16 such that they form a
cylindrical aperture when
combined. Other cross-sectional shapes may also be used, although a circular
cross-section is
preferred. The depth of these slots may change along their length to create a
taper. The slots
may be identical and designed to allow use of two simple round pins as locking
members 30.
The taper of the radiused slots may be designed so that the interior pressure
that naturally
tends to move shaft 16 outward from valve closure member 12 will tighten the
connection
between shaft 16 and valve closure member 12 to remove any hysteresis when
rotating the
shaft. In particular, while a loose fitting connection may have some range of
movement in
shaft 16 prior to movement of valve closure member 12, the tightened
connection will result
in movement of shaft 16 and valve closure member 12 occurring together. The
use of tapered
slots equally engaged with shaft 16 and closure member 12 may also facilitate
a strong,
uniform connection. Preferably, slots are shallow to minimize the reduction in
the cross
section of shaft 16, allowing for high yield strength to be maintained. The
wedging effect of
the connection may also allow for the entire length and diameter of each
locking pin 30 to be
engaged to distribute torque loads evenly and create a unified connection.
Retainer 36 may be
used to stop shaft 16 from sliding inward when valve 10 is not under pressure,
such as during
shipping or transportation.
[0027] In this patent
document, the word "comprising" is used in its non-limiting sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
possibility that more than one of the elements is present, unless the context
clearly requires
that there be one and only one of the elements.
[0028] The scope of
the following claims should not be limited by the preferred
embodiments set forth in the examples above and in the drawings, but should be
given the
broadest interpretation consistent with the description as a whole.
