U.S. patent number RE30,532 [Application Number 05/964,943] was granted by the patent office on 1981-03-03 for flapper valve with independent spring action.
This patent grant is currently assigned to TRW Inc.. Invention is credited to Spencer P. Buckner.
United States Patent |
RE30,532 |
Buckner |
March 3, 1981 |
Flapper valve with independent spring action
Abstract
An improvement in multi-flapper check valves wherein each
flapper is urged toward closure by an independent spring or
springs, thereby improving the valve response for closure.
Inventors: |
Buckner; Spencer P. (Houston,
TX) |
Assignee: |
TRW Inc. (Cleveland,
OH)
|
Family
ID: |
25509203 |
Appl.
No.: |
05/964,943 |
Filed: |
November 30, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
607339 |
Aug 25, 1975 |
04005732 |
Feb 1, 1977 |
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Current U.S.
Class: |
137/512.1 |
Current CPC
Class: |
F16K
15/038 (20130101); Y10T 137/7839 (20150401) |
Current International
Class: |
F16K
15/03 (20060101); F16K 15/02 (20060101); F16K
015/03 () |
Field of
Search: |
;137/512,512.1,512.15,521,527 ;98/41R,106,107,110-113 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Nilson; Robert G.
Attorney, Agent or Firm: Blackhurst; Daniel G.
Claims
I claim:
1. An improved valve of the type having a body with a fluid flow
conduit therethrough, a valve seat surrounding said flow conduit,
valve members for sealing said fluid flow conduit, stationary shaft
means extending diametrically across said flow conduit for
pivotally supporting said valve members within said body, and
hinges for supporting said valve members on said shaft means,
wherein the improvement comprises at least one separate helical
torsion spring encircling a portion of said shaft means for each
valve member for biasing said valve member toward its closed
position, one leg of which is in contact with said valve member and
the other leg of which is in contact with a stationary stop means,
.Iadd.said stop means comprising a pin member extending
diametrically across said flow conduit parallel to said shaft means
at a location spaced from said valve members to limit movement of
said valve members in an opening direction. .Iaddend.
2. The improved valve of claim 1 in which at least two of said
helical torsion springs have different torsional spring constants.
.[.3. An improved valve of the type having a body with a fluid flow
conduit therethrough, a valve seat surrounding said flow conduit,
valve members for sealing said fluid flow conduit, a shaft for
pivotally supporting said valve members within said body, and
hinges for supporting said valve members on said shaft, wherein the
improvement comprises at least one separate helical torsion spring
wound about said shaft for each valve member, one leg of said
spring being in contact with said valve member and the other leg
being in contact with a stationary stop shaft..]. .[.4. The
improved valve of claim 3 in which at least two of said helical
torsion
springs exert different amounts of force per degree of
deflection..]. 5. An improved valve of the type having a body with
a fluid flow conduit therethrough, a valve seat surrounding said
flow conduit, valve members for sealing said flow conduit, a single
stationary shaft extending diametrically across said flow conduit
for pivotally supporting said valve members within said body, and
hinges for supporting said valve members on said stationary shaft,
wherein the improvement comprises at least one separate helical
torsion spring encircling a portion of said stationary shaft for
each valve member for biasing said valve member toward its closed
position, one leg of which is in contact with said valve member and
the other leg of which is in contact with a stationary stop means,
.Iadd.said stop means comprising a pin member extending
diametrically across said flow conduit parallel to said stationary
shaft at a location spaced from said valve members to limit
movement of said valve members in an opening direction. .Iaddend.
.[.6. An improved valve of the type having a body with a fluid flow
conduit therethrough, a valve seat surrounding said flow conduit,
valve members for sealing said fluid flow conduit, a first single
stationary shaft extending diametrically across said flow conduit
for pivotally supporting said valve members within said body, and
hinges for supporting said valve members on said first stationary
shaft, wherein the improvement comprises at least one separate
helical torsion spring encircling a portion of said first
stationary shaft for each valve member for biasing said valve
member toward its closed position, one leg of which is in contact
with said valve member and the other leg of which is in contact
with a second shaft parallel to said first stationary shaft..].
Description
BACKGROUND OF THE INVENTION
This invention relates to a new and useful improvement in
multi-flapper check valves.
In flapper valves of the design disclosed in Bravo, U.S. Pat. No.
1,238,878 (1917), and improved upon by Wheeler in U.S. Pat. Nos.
3,007,488 (1961), 3,026,901 (1962), 3,072,141 (1963), and 3,074,427
(1963), the two flappers are urged toward their seated positions by
one or more helical springs wound about a shaft, with the two ends
of each spring contacting the two valve flappers respectively.
Thus, both flappers are urged toward their seated position by the
same spring; or, in the case of multiple spring use, each spring
acts upon both flapper elements.
Because of the disparity between the frictional resistances of the
two flappers of the check valve of the Wheeler design, and other
differences in the forces acting on them, there is a tendency for
one of the flappers to close more readily and therefore seat before
the other. When one flapper has seated, and the other flapper has
almost seated, the energy of a spring acting upon both flappers has
been largely dissipated and the torque the spring exerts against
the partially open flapper is relatively low. This can cause the
flapper to hesitate before closing, resulting in possible pressure
surges and hammer.
In Smith, U.S. Pat. No. 3,384,112 (1968), the inventor
interconnected the flappers by a relatively complex gearing
arrangement to promote synchronous flapper closure. The present
invention involves a much less complicated adaptation of the basic
valve structure to improve performance. Additionally, the present
invention, by proper choice of relative spring strengths, allows
for a design in which the flappers close synchronously, or one
flapper closes before the other.
For improved valve response, it is desirable to increase the spring
torque exerted against each flapper element as the flappers closely
approach their seat. Accordingly, it is an object of the present
invention to provide a multi-flapper check valve with improved
valve response.
Another object of this invention is to provide a multi-flapper
check valve wherein total angular spring deflection is reduced.
A further object of this invention is to provide a multi-flapper
check valve wherein higher torque springs may be used to increase
the torque acting upon a flapper when the flapper is near its
seated position.
Yet a further object of this invention is to provide a
multi-flapper check valve wherein each flapper is biased by a
separate spring.
Other objects and purposes of this invention will appear from the
following descriptions, examples, and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the check valve assembly viewed from the downstream
side.
FIG. 2 is an axial section of the check valve assembly taken along
line 2--2 of FIG. 1.
FIG. 3 illustrates the angular deflection of the torsion spring as
used in this novel improvement.
FIG. 4 illustrates the angular deflection of the torsion spring as
used in the prior art.
SUMMARY OF THE INVENTION
In this novel improvement in multi-flapper check valves, each
flapper is biased by one or more springs not acting on any other
flapper. Instead of each of the two legs of the spring acting upon
a separate flapper, as is presently commonly done, only one of the
legs of each spring acts upon a flapper, and the other leg of the
spring is held by a "stop post". Thus, each spring undergoes less
total angular deflection as the flappers move from the closed
position to the open position. Stiffer springs may be used since
less deflection occurs, with the result that greater torque can be
exerted by the spring against the flapper for small angular
deflections of the flapper about its nearly closed position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The basic elements of this novel check valve are shown in FIGS. 1
and 2. A semicircular right flapper 2 and a semicircular left
flapper 3 lie on the body 1 with their straight edges lying along
center rib 4 of the body 1. The hinge pin 7 is inserted through the
hinge pin holes 31 in the body 1, running through the upper body
lug bearing 15, upper right hinge lug 11, upper plate lug bearing
16, upper left hinge lug 12, independent spring 21, independent
spring 22, lower right hinge lug 13, lower plate lug bearing 17,
lower left hinge lug 14, and lower body lug bearing 18. Two hinge
pin retainers 41 inserted into hinge pin holes 31 hold the hinge
pin 7 in place. The stop pin 6 is inserted through stop pin holes
32 in the body 1, running through the hooked leg 24 of spring 21
and the hooked leg 25 of spring 22. Two stop pin retainers 42
inserted into stop pin holes 32 hold the stop pin 6 in place.
Ordinarily, the installed check valve is oriented with the rib 4 in
a vertical position.
While the specific embodiment shown only uses one spring for each
flapper, it is expressly understood that more than one spring may
be used for each flapper. Moreover, while only helical torsion
springs are shown, it is expressly understood that any torsion
spring or torque producing means may be substituted. Since this
novel design permits the use of shorter, stiffer (higher torque)
springs, the ability to use multiple springs is enhanced.
As is shown in the comparison of FIGS. 3 and 4, the total angular
deflection of the independent spring used in this novel design is
considerably less than that of a non-independent spring. Referring
to FIG. 4, the conventional spring is "preloaded" such that usually
it is bent approximately 180.degree. (90.degree. for each end) from
its unstressed position when the flappers are closed. This biases
the flappers toward the closed position even when nearly closed or
even seated. When both flappers are fully open, the spring has been
deflected approximately an additional 170.degree., for a total
angular deflection of approximately 350.degree. (175.degree. for
each end of the spring).
In this new design, the springs may each be preloaded about
50.degree. to 80.degree. or less from their unstressed positions,
as is shown in FIG. 3. This reduced angular preloading of each
spring is made possible because: (1) each spring acts upon only one
flapper, and need be preloaded less than a single spring acting on
both flappers; and (2) the use of stiffer springs reduces the
required angular deflection for a specific amount of torque to be
preloaded. When a flapper is in its fully open position, its spring
is deflected approximately an additional 85.degree., for a total
angular deflection of about 135.degree. to 165.degree., as compared
with the 350.degree. angular deflection of the spring in a
conventional design.
A further advantage of the novel independent spring design is that
the characteristics of each spring may be tailored to compensate
for any non-uniform or assymetrical response of the flappers. As
discussed earlier, the two flappers may require different amounts
of force to close because of inequalities in frictional forces or
other forces acting upon them. Quite typically, one of the flappers
will be more difficult to close because of additional frictional
resistance acting upon it. In a conventionally designed check
valve, this results in the other flapper closing first, and the
practically exhausted spring then acting upon only the nearly
closed flapper. This hesitation in complete valve closure can
result in allowing the flow through the check valve to reverse
before the slower flapper has seated, thereby causing the flapper
to slam shut with a resulting pressure surge. However, when
independent springs are used, a higher torque spring may be used to
act upon the flapper having more frictional resistance, thereby
providing that flapper with additional closing force and higher
torque acting upon it when nearly closed. By proper design of the
relative strengths of the springs, the valve can be made wherein
the flappers close synchoronously, or one flapper closes slightly
before the other.
Also, since each independent spring undergoes less total angular
deflection, the springs may typically be shorter than those of the
conventional design, thereby allowing more springs to be used. The
use of multiple independent springs for each flapper may be
desirable, for in a valve of such design one or more springs would
continue to provide biasing torque to the flapper should one of the
springs acting on that flapper fail.
The use of stiffer or higher torque springs acting on the flappers
increases the angular acceleration of the flapper toward the seat.
The greater the angular acceleration, the faster the valve
response. If the movement of the flapper plates matches the
deceleration of the fluid flow through the check valve, pressure
surges and "hammer" can be minimized. However, if insufficient
torque acts on the flapper plate, the valve will still be partially
opened when the rate of flow has gone to zero and the direction of
flow starts to reverse. Some backflow will then occur, resulting in
a pressure surge and hammer when the valve finally closes. Since
stiffer springs may be used in this novel design because of the
reduced total angular deflection of the spring between the open and
closed positions, more torque can be exerted by the spring against
the flapper plate. The increased torque acting upon each flapper
enables the flapper to close more quickly and will improve valve
performance.
* * * * *