A solenoid valve is described in which both an inlet and an outlet of the valve are sealed when the valve is closed. This double seal compensates for leakage at either the inlet or the outlet by making the other seal more effective in response to the leakage and allows the reversal of the flow direction by simply switching the inlet and outlet connections. The solenoid valve has a valve chamber within the valve body. Inlet and outlet tubes extend through a plate into the chamber. A movable core in the chamber extends into the solenoid coil. The distal end of the core has a silicone rubber plug. Other than when the solenoid is energized, the compressed spring biases the core downward so that the surface of the plug is in sealing engagement with the ends of the tubes. A leak at either end increases the pressure in the chamber, resulting in increased sealing force of the plug

Matsumoto, Yutaka

Woeller, Fritz H.

English

NASA Technical Reports Server

United States Patent [I91 
Woeller et d. 
[54] SELF-COMPENSATING SOLENOID VALVE 
[75] Inventors: Fritz H. Woeller, Boulder Creek; 
Yutaka Matsumoto, San Jose, both of 
Calif. 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[73] Assignee: The United States of America as 
[21] Appl. No.: 795,945 
[22] Filed: Pdov. 7, 1985 
[51] Int. ClP .............................................. F16K 31/02 
[52] U.S. Cl. .......................... 137/614.18; 137/614.11; 
251/129.15; 251/175 
[58] Field of Search ...................... 137/614.1 1, 614.18, 
137/614.19; 25V129.15, 175 
[561 References Cited 
U.S. PATENT DOCUMENTS 
77,517 5/1868 Moore et al. ................... 137/614.11 
504,838 9/1893 Jeannotte ....................... 137/614.11 
2,838,068 6/1958 Ray ............................ 251A29.15 X 
2,908,290 10/1959 Hamilton-Peters et al. ... 137/614.11 
3,082,359 3/1963 Mangiafko et al. ....... 251A29.15 X 
1111 Patent Number: 4,68 1,142 
[45] Date of Patent: Jul. 21, 1987 
3,262,027 7/1966 Zaleske et al. ............. 251A29.15 X 
4,341,241 7/1982 Baker ......................... 251A29.15 X 
Primary Examiner-A. Michael Chambers 
Assistant Examiner-John C. Fox 
Attorney, Agent, or Firm-Darrell G. Brekke; John R. 
Manning; Robert D. Marchant 
[571 ABSTRACT 
Solenoid valve (10) has a valve chamber (18) within 
valve body (12). Inlet and outlet tubes (22) and (24) 
extend through plate (14) into the chamber (18). Mov- 
able core (32) in chamber (18) extends into solenoid coil 
(30). Distal end (38) of core (32) has a silicone rubber 
plug (40). Other than when solenoid (30) is energized, 
compressed spring (48) biases core (32) downward so 
that surface (44) of the plug (40) is in sealing engage- 
ment with ends (26) and (28) of the tubes (22) and (24). 
Any leak at ends (26) and (28) increases pressure in the 
chamber (18), resulting in increased sealing force of the 
plug (40) against the other end (26) or (28). Flow direc- 
tion through the valve (20) is easily reversed by chang- 
ing connections to the tubes (22) and (24). 
5 Claims, 1 Drawing Figure 
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U.S. Patent 
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4,68 1,142 
1 
SELF-COMPENSATING SOLENOID VALVE 
ORIGIN OF THE INVENTION 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- 
factured and used by or for the Government for govern- 
mental purposes without the payment of any royalties 
thereon or therefor. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a solenoid valve with en- 
hanced sealing and opening characteristics. More par- 
ticularly, it relates to such a valve that will utilize any 
inlet or outlet leakage pressure to provide a better outlet 
or inlet seal in a bi-directional manner. Most especially, 
it relates to such a valve suitable for controlling flows in 
gas chromatographs and similar precision applications. 
2. Description of the Prior Art 
A variety of solenoid valve configurations for con- 
trolling fluid flow are known in the art. Representative 
prior art solenoid valve designs are disclosed in the 
following issued U.S. Pat Nos.: 3,878,859, issued April 
22, 1975 to Grob et al. and 4,453,700, issued June 12, 
1984 to Otsuki et al. Other examples of prior art sole- 
noid valves suitable for gas chromatograph and similar 
applications are commercially available from Pyronet- 
ics Division of Parker-Hannifin and from ITT under the 
designation of Microsol. 
Prior art solenoid valve designs provide a single seal 
between their fluid inlet and outlet. If this single seal 
becomes ineffective, fluid flow between the inlet and 
outlet is allowed to take place. Prior art solenoid valves 
which allow interchanging of the inlet and outlet con- 
nections are not symmetrical in configuration and there- 
fore do not operate in a symmetrical manner. Many 
prior art solenoid valve designs either will not open or 
will stick open under certain operating conditions. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of this invention to pro- 
vide a solenoid valve incorporating more than one seal 
in its fluid flow path, in which leakage at one seal oper- 
ates to make the other seal more effective. 
It is another object of the invention to provide a 
solenoid valve which is free of sticking under a wide 
variety of operating conditions. 
It is a further object of this invention to provide such 
a solenoid valve that is reliable in operation for an in- 
creased number of operating cycles. 
It is still another object of the invention to provide a 
solenoid valve with symmetrical operation when the 
inlet and outlet connections are interchanged. 
The attainment of these and related objects may be 
achieved through use of the novel solenoid valve herein 
disclosed. A solenoid valve in accordance with this 
invention has a valve body and a valve chamber in the 
valve body. There is a fluid inlet to the valve chamber 
and a fluid outlet from the valve chamber. A resilient 
means seals both fluid inlet and the fluid outlet. A sole- 
noid cail is positioned alongside the valve chamber. A 
movable core is positioned within the solenoid coil. The 
movable core extends into the valve chamber and is 
connected to the resilient sealing means. The fluid inlet 
and the fluid outlet are positioned with respect to the 
resilient sealing means so that movement of the core 
within the solenoid coil moves the resilient sealing 
means into and out of simultaneous sealing engagement 
with both the fluid inlet and the fluid outlet. A means 
biases the resilient sealing means in a given direction 
with respect to the fluid inlet and the fluid outlet, i.e., 
5 the biasing means either urges the resilient sealing 
means away from the fluid inlet and fluid outlet to pro- 
vide a normally open valve, or biases the resilient seal- 
ing means toward the fluid inlet and fluid outlet to 
provide a normally closed valve. 
In operation, the presence of a seal at both the fluid 
inlet and fluid outlet from the valve chamber means that 
leakage at either seal tends to make the other seal more 
effective. As a result, the solenoid valve of this inven- 
tion is operable over a wider range of operating condi- 
l5 tions and is more reliable than prior art solenoid valves. 
The attainment of the foregoing and related objects, 
advantages and features of the invention should be more 
readily apparent to those skilled in the art, after review 
of the following more detailed description of the inven- 
BRIEF DESCRIPTION O F  THE DRAWING 
The sole FIGURE of.drawing is a cross section of a 
10 
2o tion, taken together with the drawing, in which: 
solenoid valve in accordance with the invention. 
DETAILED DESCRIPTION O F  THE 
INVENTION 
25 
Turning now to the sole FIGURE of drawing, there 
3o is shown a solenoid valve 10 in accordance with the 
invention, shown in its open position. Valve body 12 
and plate 14 are fastened together at mating flanges 16 
to form a valve chamber 18. O-ring 20 forms a seal 
between the plate 14 and the valve body 12. Tubes 22 
35 and 24 extend through the plate 14 and terminate in 
ends 26 and 28, respectively, within chamber 18. 
A solenoid coil 30 is mounted on the valve body 12. 
A movable solenoid core 32 within the chamber 18 
extends into the solenoid coil 30. A fured solenoid core 
34 extends from end 36 of the coil 30 toward the mov- 
able core 32 and chamber 18. Enlarged distal end 38 of 
the movable core 32 has a resilient silicone rubber plug 
40 mounted in recess 42 with surface 44 facing the tube 
ends 26 and 28. The tube ends 26 and 28 are beveled at 
45 46 to prevent damage to surface 44 when the plug 40 is 
in sealing engagement against the ends 26 and 28. 
Compressed spring 48 in bore 50 of the movable core 
32 biases the core 32 downward, so that surface 44 of 
the plug 42 is in sealing engagement against the ends 26 
50 and 28 of the tubes 22 and 24, other than when the 
solenoid 30 is actuated. When the solenoid 30 is actu- 
ated, electromagnetic force is applied to the movable 
core 32 to overcome the biasing force of spring 48 and 
move the core 32 upward to the the position shown, 
55 opening the valve 10 by moving the surface 44 away 
from the ends 26 and 28. Fluid may then flow, for exam- 
ple upward in tube 22 to chamber 18, as indicated by 
arrow 52 and downward from chamber 18 through tube 
24, as indicated by arrow 54. Since ends 26 and 28 of the 
60 tubes 22 and 24 are sealed in the same manner when the 
valve 10 is closed, the fluid flow path in the valve 10 
may be changed by switching the inlet and outlet con- 
nections to the tubes 22 and 24 with symmetrical opera- 
tion of the valve 10. 
Because an increase in pressure within chamber 18 
will cause the plug 40 to press against ends 26 and 28 
with greater force, leakage of fluid from either end 26 
or 28 into chamber 18 will tend to cause a more effec- 
65 
4,68 1,142 
3 
tive sealing of the surface 44 against the other end 28 or 
26. The valve 10 is therefore self compensating for leaks 
in a bi-directional manner. In practice, the double seal 
incorporated in this valve is capable of providing posi- 
tive valve closure at fluid pressures up to at least about 5 
1500 kilopascals (217 psi). 
As shown, there is a sufficient lateral clearance 56 
between the movable core 32 and the chamber 18 so 
that the movable core 32 is free to move sideways in 
operation of the valve 10. Providing such freedom of 10 
sideways movement helps to prevent the valve IO from 
sticking in either its open or closed position over a wide 
variety of pressure and flow conditions through the 
tubes 22 and 24. 
the art that a novel solenoid valve capable of achieving 
these stated objects of the invention has been provided. 
The bi-directional sealing action of this valve means 
that leaks at either the inlet or outlet from the valve are 
self compensating. The valve may be connected to 20 
allow symmetrical flow through the valve in either 
direction. The configuration of the valve allows it to 
operate under a wide variety of different fluid pressure 
and flow conditions without sticking. While the valve 
as described is especially adapted for precision supply 25 
of gas flows in gas chromatographs, valves in accor- 
dance with the invention are useful in a wide variety of 
other gas and liquid flow enviroments as well. 
It should further be apparent to those skilled in the art 
that various changes in form and details of the invention 30 
as shown and described may be made. It is intended that 
such changes be included within the spirit and scope of 
the claims appended hereto. 
It should now be readily apparent to those skilled in 15 
What is claimed is: 
1. A solenoid valve comprising a valve body, a valve 35 
chamber in said valve body, first and second fluid pas- 
sages providing an inlet to said valve chamber and an 
outlet from said valve chamber, both of said first and 
4 
second passages being configured to serve bi-direction- 
ally and symmetrically as either the inlet or the outlet, 
resilient means for sealing said first and second passages, 
a solenoid coil positioned alongside said valve chamber, 
a movable core positioned within said solenoid coil, said 
core extending into said valve chamber and being con- 
nected to said resilient sealing means, said first and 
second passages terminating in coplanar ends of the 
same configuration facing said resilient sealing means so 
that movement of said core within said solenoid coil 
moves said resilient sealing means into and out of simul- 
taneous, separate sealing engagement with said first and 
second passages, and means positioned halfway along 
said resilient sealing means between the ends of said first 
and second passages for biasing said resilient sealing 
means in a given direction with respect to said first and 
second passages, said core being positioned within said 
solenoid coil with sufficient clearance and said valve 
chamber being configured to allow spontaneous align- 
ment of said sealing means with respect to the ends of 
said first and second passages to make hermetic contact 
between said sealing means and the one of said first and 
second passages serving as the outlet by pivoting said 
core within said solenoid coil. 
2. The solenoid valve of claim 1 in which said first 
and second passages comprise first and second tubes 
extending through a wall of said valve body, said first 
and second tubes terminating in laterally adjacent ends. 
3. The solenoid valve of claim 2 in which said resil- 
ient sealing means comprises a body of silicone rubber 
having a surface facing the ends of said first and second 
tubes. 
4. The solenoid valve of claim 3 in which the ends of 
said first and second tubes are bevelled. 
5. The solenoid valve of claim 2 in which said biasing 
means biases said resilient sealing means against the 
ends of said first and second tubes. * * * * *  
40 
50 
55 
40 
65 


Self-compensating solenoid valve

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