Prototype liquid-fuel valve performs on-off and throttling functions in vacuum without component cold-welding or excessive leakage. Valve design enables simple and rapid disassembly and parts replacement and operates with short working stroke, providing maximum throttling sensitivity commensurate with good control

Mcdougal, A. R.

Porter, R. N.

Riebling, R. W.

English

NASA Technical Reports Server

November 1971	 Brief 71-10449 
NASA TECH BRIEF 
NASA Pasadena Office 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Liquid-Fuel Valve with Precise Throttling Control 
A prototype liquid-fuel valve performs on-off and 
throttling functions in a vacuum, without compo-
nent cold-welding or excessive leakage. The valve is 
designed to enable simple and rapid disassembly 
and parts replacement, even when the unit is
the fuel mass flux and mixture ratio across the in-
jector at design values. 
Fuel enters the valve assembly through the inlet 
port and is distributed throughout an annular 
manifold of variable area to maintain full flow at 
Inlet Port 
(Orifice	 Shutoff	
Stem Guide and Shutoff)	 Plug	
Screen 
Throttling Positive
	 I	 j Combination Plug	 Filter S /	 LipperCrush Gasket (Only Sealed Joint) 	 N \	 / Bellows 
Actuator 
Shaft
WflL!ZI.1T 
Swat 
C> 
Lower 
Bellows 
welded into the fuel lines. Seals or potential leak 
paths are minimized, and the valve operates with a 
short working stroke to provide maximum throttling 
sensitivity commensurate with good control. Indi-
vidual injection orifices (not part of the valve), fed 
through tubing connected to the valve ports, provide 
essentially identical flow rates. Operation of the 
valve in this manner should ensure positive control 
of the injector hydraulic system while maintaining
Ports	 Pressure Drop Trimming 
Orifice 
constant velocity. The fuel then passes into and fills 
the internal cavity, including the upper bellows, up-
stream of the positive shutoff plug. The flow inside 
the valve encounters first a conical filter screen and 
then a trimming orifice which adjusts the overall 
valve pressure drop. The support for the filter and 
trimming orifice also serves as a guide for the valve 
stem. The bellows are designed to make the valve 
self-closing; an external force to open or "crack" 
(continued oerieaF( 
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Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
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the valve must be supplied through an actuator 
shaft attached at a point within the body assembly. 
The on-off function is performed by a laminated 
plug (positive shutoff plug) made of alternating lay-
ers of a fluorocarbon polymer and an aluminum 
alloy. Throttling is accomplished by a similar plug 
(attached to the same stem) which progressively 
uncovers the individual valve ports as the valve 
stem moves down. The ports (round holes) are 
arranged in a series of spirals around the circum-
ference of the bore and are individually connected 
to the injector orifices by tubing. Internally, the 
ports are narrow rectangular slots, so that a mini-
mal stem travel can completely open or close each 
port on the outer surface of the valve body. 
The central valve stem, to which the on-off and 
throttling plugs are attached, is fixed to both the 
top and bottom bellows, and the entire assembly 
moves as a unit. The position of the stem (and 
therefore of the plugs) is determined by the external 
actuator. When the valve is open, a constant actua-
tor force is sufficient to hold the stem in any posi-
tion, since the pressure and the bellows spring 
forces are balanced. When the valve is nearly closed, 
the ports are covered (or uncovered, depending on 
the direction of stem travel) one at a time to 
achieve finer throttling at the lowest flow rates. At 
intermediate flow rates, the ports are covered two 
and three at a time; at the highest flow rates, five 
at a time. When the valve is completely closed, the 
top bellows is in compression and the bottom bel-
lows is in tension as a result of the preloads applied 
during assembly. In order to "crack" the .valve 
open, the force applied' by the external actuator 
must exceed the net force tending to hold the valve 
shut.
Notes: 
1. Design of this valve is based on the concept of 
"discrete-element" throttling. With appropriate 
design changes, however, the valve could be 
adapted to a dual-manifold, pressure/area-step 
throttling technique, such as described in SPS 
37-44, Vol. V, p 7, Caltech/JPL, Pasadena, 
California, 91103. 
2. Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP71-10449 
Patent status: 
This invention has been patented by NASA (U.S. 
Patent No. 3,568,447), and royalty-free license 
rights will be granted for its commercial develop-
ment. Inquiries about obtaining a license should be 
addressed to: 
Patent Counsel 
Mail Code I 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Source: R.W. Riebling, A.R. McDougal, and 
R.N. Porter of 
Caltech /JPL 
under contract to 
NASA Pasadena Office.
 
(N P0-10808)
. 
Brief 71-10449	 Category 07


Liquid-fuel valve with precise throttling control

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