Solenoid operated valve in a control system powered by direct current issued to accurately measure the valve travel. This system is currently in operation with a 28-vdc power system used for control of fluids in liquid rocket motor test facilities

Gillett, J. D.

English

NASA Technical Reports Server

Oscill ograph 
Fuel Valve Travel 
Lead Valve Power 
December 1966	 Brief 66-10568 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Monitoring Circuit Accurately Measures Movement of Solenoid Valve 
Valve
Valve First Motion 
The problem: 
To accurately measure the valve travel of solenoid 
operated valves, which are generally hermetically 
sealed. Valve opening times can be established only 
by inference from the rate of change of the pressure 
levels in various portions of the fluid system in which 
they are employed. When such valves are used for 
metering or critical operational sequencing, inferred 
values of travel time are not sufficiently accurate for 
reliable control, due to the influence of system volume 
and pipe size on the rate of change of pressure. 
The solution: 
A solenoid operated valve in a control system 
powered by direct current. The valve travel can be 
reliably monitored through accurate measurement of 
the rate of change of the solenoid operating current. 
This current level is a direct function of the position 
of the solenoid armature in relation to the coil. 
Absolute values of current will be found to vary
over a wide range; however, the characteristic shape 
of the current vs time plot is found to be similar for 
practically all dc solenoids. 
How it's done: 
A small resistor with sufficient capacity to match 
the solenoid maximum current requirement is inserted 
in series with the solenoid coil. The voltage drop 
across this resistor is the input to a solid-state ampli-
fier. The amplifier output drives a galvanometer in a 
recording oscillograph operating at approximately 
10 inches/second. By recording several valves on the 
same oscillograph, both valve opening time and 
sequence of operations are critically measured. 
Notes: 
1. This system is currently in operation with a 28-vdc 
power system used for control of fluids in liquid 
rocket motor test facilities. In this application, the 
the sequencing of various flows is critical to the 
± 10-millisecond level.
(continued overleaf) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19660000566 2020-03-11T17:44:22+00:00Z
Inquiries concerning this invention may be di- 	 Patent status: 
rected to:
	 Inquiries about obtaining rights for the commercial 
Technology Utilization Officer	 use of this invention may be made to NASA, Code 
Marshall Space Flight Center 	 GP, Washington, D.C. 20546. 
Huntsville, Alabama 35812 	 Source: J. D. Gillett 
Reference: B66-10568	 of North American Aviation Inc., 
under contract to 
Marshall Space Flight Center 
(M-FS- 1829) 
Brief 66-10568	 Category 01


Monitoring circuit accurately measures movement of solenoid valve

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