Positive locking check valve for stopping reversed flo

Cahill, N. E.

English

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Please note  t h a t  t h i s  p a t e n t  covers  an  invent ion  made by an 
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Enclosure:  
Copy of Patent  
https://ntrs.nasa.gov/search.jsp?R=19710013230 2020-03-17T02:50:28+00:00Z
ay 21, 1968 JAMES E. WE 
ADMINISTRATOR OF THE NATION 
AERONAUTICS A N D  SPACE 
ADMl NISTRATION 
POSITIYE LOCKING CHECK VALVE 
Filed July 20, 1967 
! 
I 
e Pa 
3,384,111 
~S~~~~ LOCKING C 
James E. Webb, Administrator of the National Aeronau- 
tics and Space Administration, with respect to an in- 
vention of Norbert E. Cahill, Anaheim, Calif. 
Filed July 20, 1967, Ser. No. 655,724 
6 Claims. (C1. 137-496) 
A check valve assembly capable of opening to allow 
flow in one direction and of closing and locking to prevent 
flow in the opposite direction. The valve, by actually lock- 
ing against reverse flow, is extremely stable and will not 
flutter or accidentally unseat under vibrational and/or 
shock loads. Structurally, the valve assembly has a ball 
detent latch which normally locks the valve in a closed 
position. The detent latch is normally held in a latched 
position by the compression spring force of a bellows 
which is attached to the latch and which is positioned to 
be expanded by forward flow through the assembly. Upon 
expansion of the bellows, the valve is unlatched and 
opened for flow. Reverse flow will reseat the valve, col- 
lapse the bellows, and actuate the latch to lock the assem- 
bly in a closed position. 
The invention described herein was made in the per- 
formance of work under a NASA contract and is subject 
to the provision of section 305 of the National Aero- 
nautics and Space Act of 1958, Public Law 85-568 (72 
Stat. 435; 42 U.S.C. 2457). 
Background of the invention 
The present invention relates to a check valve assem- 
bly capable of opening to allow flow in one direction, and 
of closing and locking to prevent flow in the opposite di- 
rection, and one which is extremely stable under vibration, 
acceleration, and shock loads. It also eliminates the tend- 
ency of the valve to flutter at the critical cracking point, 
which is typical of most other types of valves. 
The use of check valves in flow systems to allow flow 
only in one direction is old and well known in the art. 
Typical of such values is one which utilizes a ball-and- 
cage assembly wherein the ball is displaced from its seat 
by forward flow and is neseated by reverse flow. While 
such valves are adequate in some simple flow systems, they 
are inadequate in others. This is due to the fact that the 
valve is held on the seat solely by back pressure of the 
flow, and any vibrations, shock, or the like, may acciden- 
tally unseat the valve to allow back flow which may be 
highly detrimental to the system. 
One well known procedure for alleviating the above 
mentioned problem is to  use a spring to positively bias 
the valve onto its seat. This is satisfactory in many in- 
stancles, but not in all since the force of the spring must 
be such to insure that the normal pressure of the flow will 
open the valve. Where the flow pressure of the system is 
low, the force of the spring is accordingly low and the 
valve is still subject to accidental unseating. Even in high 
pressure systems where a spring having substantial force 
can be used, the possibility still exists that a sudden ac- 
celeration, shock, or harmonic vibrations may temporarily 
unseat the valve. In these instances, the entire flow sys- 
tem may become unbalanced by a back surge of flow. 
An example of such a system is the propellant flow sys- 
tem for a typical rocket motor. It is vitally important to 
prevent back flow of either oxidizer or fuel to the opposite 
component since normally such components are hyper- 
golic and will ignite when mixed. Also, the combustive 
vapors and the like are highly corrosive, and it is undesir- 
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10 
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25 
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40 
45 
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60 
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able to have any back flo f such vapors through the 
system. It is readily apparent that any valves utilized in 
a pressurization and propellant flow system of a rocket 
will very likely be subjected to intense vibrations, shock, 
and acceleration loads during flight operations of the 
rocket, any of which could cause temporary and possibly 
disastrous unseating of the valves. 
Summary 
The present invention provides a check valve which 
readily opens for normal flow, but one which quickly 
closes and locks whenever there is back surge of pres- 
sure. The more the back pressure increases or fluctuates, 
the tighter the valve will seat. By positively locking in a 
closed position, the valve is virtually unaffected by shock 
loads, or the like, and will not accidentally unseat or flut- 
ter as do most known prior art check valves. 
Structurally, the preferred embodiment comprises a 
body having an inlet and an outlet. A valve is slidably 
mounted in the body which cooperates with a seat in the 
body to block flow through the body whenever the valve 
is in a closed position. A spring is positioned in the body 
to normally bias the valve to a closed position. Slidably 
mounted in the valve is a plunger which cooperates with 
ball detent means to normally latch the valve in said 
closed position. The plunger is held in a normal latched 
position by the compressive force of a bellows which is 
attached to the plunger. The bellows is positioned to be 
expanded by regular flow through the valve and upon ex- 
pansion will move the plunger to release the ball detent 
means and allow the valve to open. A back surge of pres- 
sure will reseat the valve, collapse the bellows, and re- 
latch the ball detent means. 
The actual construction, operation, and the apparent 
advantages of the invention will be better understood by 
referring to the drawings in which like numerals identify 
like parts and in which: 
Brie] description of the drawings 
FIG. 1 is a cross-sectional view of the valve assembly 
in accordance with the present invention showing said 
assembly in a closed and latched position; and 
FIG. 2 is a partial cross-sectional view of the valve as- 
sembly showing said assembly in an opened and unlatched 
position. 
Description of the preferred embodiment 
Referring more particularly to the figunes, check valve 
assembly comprises an elbow-shaped body 11 having an 
inlet 12 and an outlet 13. Formed integrally within body 
11 is spider cage 14 which has openings 115 (only one is 
shown in cross-sectional view) therethrough which com- 
municate the inlet and outlet to establish flow through the 
body. Spider 14 has a central bore 16 therethrough in 
which stem 21 of valve 20 is slidably mounted. Valve 20 
is flared at the low8er end of stem 21 to form flange 22. 
A sealing means 23 is provided around the upper periph- 
ery of flange 22 which cooperates with valve seat 24 to 
effectively block flow through outlet 13 whenever valve 20 
is in a closed position. 
Stem 211 has an axial passage 25 therethrough in which 
plunger 26 is slidably mounted. Plunger 26 has a reduced 
portion 27 at  one end and a disk-like portion 28 at the 
other. A flexible bellows 29 is bonded or otherwise se- 
cured at  one end to flange 22 of valve 20, and at its other 
end to portion 28 of plunger 26. Bellows 29 has a natural 
compressive force which causes the bellows to collapse 
when in a deflated condition. Ports 30 are provided in 
flange 22 to establish communication between openings 15 
and the interior of bellows 29 for a purpose that will be 
explained below. 
Positioned within holes 3 which are drilled in stem 
3,384, 
3 
are ball detents 32. The diameter of detents 32 is such 
that when plunger 26 is in the position shown in FIG. 1, 
the detents will extend outward through holes 31 to con- 
4 and to latch stem 21 with respect to spider 
14. Detents 32 are held in place by retainer 33. Spring 34 5 
is positioned between valve 20 and recessed cover 35 to 
normally bias valve 20 to a closed position. 
The operation of valve assembly BO is as follows: with 
valve assembly in the closed and locked position as shown 
in FIG. 1, the fluid to be controlled is admitted to assem- 
0 through inlet 22. Flow will pass through openings 
15 in spider 14 and will normally be blocked by valve 20. 
However, flow will occur through ports 30 in flange 22 
and will pass into bellows 29 to expand same. Bellows 29, 
upon expanding, will move plunger 26 downward until re- 15 
duced portion 2'7 of plunger 26 registers with holes 31 
in stem 21. In this position, the cam-like surface of spider 
14 will allow balls 32 to move down into contact with 
reduced portion 27 of plunger 26 and out of contact with 
spider 14, thereby releasing stem 21 for movement. Pres- 20 
sure of the flow will now act on flange 22 to move valve 
20 against the bias of spring 34 to unseat sealing means 
23 and allow flow through outlet 13. 
With bellows 29 in an expanded position, valve 20 is 
free to function as a normal check valve with the valve 25 
being controlled by spring 34, as is well known in the art. 
However, upon an increase in downstream pressure such 
as may be encountered by a back surge of flow, or the 
like, spring 34 will immediately close valve 20 and the 
increased pressure will collapse bellows 29. This moves 30 
plunger 26 upward to re-engage balls 30 with spider 14 
to  thereby positively lock valve 20 in a closed position. 
As long as the downstream pressure is equal to or 
greater than the upstream pressure, valve 20 will remain 
in a locked condition, thereby eliminating a possible ac- 35 
cidental unseating or fluttering of the valve due to vibra- 
tions, shock, or acceleration loads. Although a particular 
embodiment of the subject invention has been illustrated 
and described, the disclosure is intended to cover all 
changes and modifications therein which do not constitute 40 
departure from the spirit and scope of the invention. 
What is claimed and desired to be secured by Letters 
Patent is: 
1. A check valve assembly highly stable under vibra- 
tional or shock loads comprising: 
a body having an inlet and an outlet, said body having 
valve seat means between said inlet and said outlet; 
resiliently biased valve means movably mounted in said 
body and cooperable with said valve seat means to 
open said valve assembly against the resistance of 5o 
said bias for forward fluid flow and to close said 
assembly under the influence of said bias when said 
fluid flow stops or reverses; 
latch means on said valve means to positively lock said 
valve means on said seat means to prevent reverse 55 
flow through said valve assembly; and 
release means on said valve means to release said latch 
means to unlock said valve means to allow forward 
flow through said valve assembly. 
2. A check valve assembly as set forth in claim B 
a valve having a stem which is slidably mounted in said 
body, said valve being movable from an open posi- 
tion when said valve is away from said seat means to 
a closed position when said valve is in contact with 65 
said seat means. 
45 
wherein said valve means comprises: 
3. A check valve assembly as set forth in claim 2, 
wherein said stem of said valve has an axial bore there- 
throngh and wherein said latch means comprises: 
111 
a plunger slidably mounted in said valve, said plunger 
having a reduced portion at one end thereof; 
a plurality of detents movably mounted in respective 
openings through said stem into said bore, said open- 
ings being positioned on said stem so that said plunger 
will normally engage said detents to hold said detents 
in contact with said body to thereby lock said valve 
when said valve is in a closed position, and so that 
said detents will disengage said body to release said 
valve whenever said reduced portion of the plunger 
is moved adjacent said detents. 
4. A check valve assembly as set forth in claim 3, 
expandable means connected to said valve and said 
plunger so that expansion of said expandable means 
will move said plunger relative to said valve to re- 
lease said detents; and 
passage means in said valve for fluidly communicating 
said inlet with said expandable means so that forward 
flow through said valve assembly will normally ex- 
pand said expandable means. 
5. A check valve assembly as set forth in claim 4, 
a flexible bellows normally in a deflated position. 
6. A check valve assembly highly stable under vibra- 
a body having an inlet and an outlet and a spider 
element having passages therethrough to establish 
flow through said body and a central bore there- 
through; 
valve means having a stem slidably mounted in said 
central bore of said spider, said stem having an axial 
passage therethrough and a plurality of openings 
through the wall thereof; 
seal means on said valve means which engage said 
spider to block flow when said valve is in a closed 
position; 
means in said body normally biasing said valve means 
to a closed position; 
a plunger slidably mounted in said axial passage of said 
stem and having one end extending from said passage; 
said plunger having a reduced portion at  its other end; 
ball detents, one loosely positioned in each of said 
openings in said stems, said opening being positioned 
on said stem so that said plunger will normally en- 
gage said detents to hold said detents in contact with 
said spider element to thereby lock said valve when 
said valve means is in a closed position and so that 
said detents will disengage said spider to release said 
valve means whenever said reduced portion of sailla 
plunger is moved adjacent said detents; and 
a bellows connected at one of its ends to said valve 
means and at its other end to said plunger, said valve 
means having passages therein to communicate flow 
through said inlet to the interior of said bellows so 
that normal flow will expand said bellows to release 
said ball detents. 
wherein said release means comprises: 
wherein said expandable means comprises: 
tional or shock loads comprising: 
References Cited 
UNITED STATES PATENTS 
1,461,010 7/1923 Amdursky _ _ _ _ _ _ _ _ _ _  1 3 7 4 6 7  
2,525,487 10/1950 Johnson _ _ _ _ _ _ _ _ _ _ _ _  137-467 
3,263,698 811966 Siggelh -___________ 137-467 
WILLIAM F. O'DEA, Primary Examiner. 
H. W. WEAIUEY, Assistant Examiner. 


Positive locking check valve Patent

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