Latching, fast-acting 2-port poppet valve has been developed for use in gas chromatograph - mass spectrometer combinations. Requisites included positive actuation time, few hundredths of a second, and static force holding valve in position at all times

Conley, J. M.

English

NASA Technical Reports Server

January 1973	 B73-10026 
NASA TECH BRIEF 
NASA Pasadena Office	 CI 
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. 
Magnetic Latching Valve 
The problem: 
To develop a latching, fast-acting 2-port poppet 
valve for use in gas chromatograph—mass spectrom-
eter combinations; a positive actuation time of the 
order of a few hundredths of a second is a prime 
requisite, and a static force must hold the valve in 
position at all times.
Armature
The spring capsule is located in a coupling barrel, 
and it can move freely within the barrel; the capsule 
itself is rigidly attached to the valve poppet stem. An 
extension of the armature shaft, E, acts as a piston 
within the capsule and compresses either of two 
springs. The springs are attached to the two ends of 
the capsule, but not to the armature shaft; in fact, at 
the center of armature travel, the piston end of the 
Actuator	 Spring Capsule	 Valve 
The solution: 
A linear, bistable magnetic actuator which utilizes 
a permanent magnet to hold the poppet in position 
and requires electrical power only for shifting the 
valve poppet from one position to the other. 
How it's done: 
The device shown in the diagram consists of three 
distinct subassemblies, a valve, a spring capsule, and 
a magnetic actuator. The valve is of conventional 2-
port design; the poppet stroke is about 1.5 mm (0.060 
in), and leakage and operational friction is kept to a 
minimum by use of a bellows instead of a packing 
gland.
armature shaft extension has an unloaded clearance 
of about 0.51 mm (0.020 in). Armature motion is re-
stricted so that either spring is compressed 0.25 mm 
(0.01 in) when the poppet is fully open or closed; 
additionally, the springs are selected so that they 
exert a force of about 1.6 kg (3.5 lbs) when compressed 
to this extent. 
The actuator consists of a cylindrical, axially sym-
metric armature of soft iron (or other material of high 
permeability and low coercive force) with a permanent 
magnet of high coercive force, and a cylindrical stator 
of soft iron with end caps of the same material; the 
actuator shaft is made of nonmagnetic metal. Two 
(continued overleaf) 
This document was prepared under the sponsorship of the National' 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19730000026 2020-03-17T06:37:18+00:00Z
actuating solenoids are mounted in the end caps. In 
the diagram, the armature is shown at the limit of its 
travel and at one of its two bistable positions. The 
armature will remain at either end of the stator en-
closure because of the attraction between the perma-
nent magnet in the armature and the soft iron caps of 
the stator. When the armature end is in contact with 
the end cap, the basic flux path is such that the ma-
jority (88%) of the flux lines pass through the contact 
interface parallel to th armature shaft and return via 
the stator shell through cylindrical tab A.The magnetic 
holding force is of the order of 2.7 kg (6 lbs); thus, 
since the spring in the spring capsule exerts a return 
force of 1.6 kg (3.5 ibs), the poppet is held open (or 
closed) by a net force of 1.1 kg (2.5 lbs). 
The actuator is changed over to the other bistable 
position by energizing the solenoids to an extent that 
the effective flux in the armature-stator system is de-
creased and the return force exerted by the spring 
capsule can move the armature away from one end 
cap. The solenoids are energized in series; one coil 
bucks the magnetic flux in the end cap nearest the 
armature and the other coil establishes in the opposite 
end.cap a flux which can attract the armature magnet. 
Referring to the diagram, when the solenoids are en-
ergized, the capsule spring accelerates the armature
away from tab A, breaking the flux path which held 
the armature against the left end cap; the armature 
rapidly moves towards the right end cap and estab-
lishes a new flux path through tab B. When power to 
the solenoids is removed, the armature remains locked 
in its new position. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP 73-10026 
Patent status: 
NASA has decided not to apply for a patent. 
Source: Joseph M. Conley of

Caltech/JPL
under contract to

NASA Pasadena Office

(NPO-11790)
S 
B73-10026	 Category 06


Magnetic latching valve

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