Compressor raises pressure of gases from low ambient supply during space experiments by a system of low weight, size, and power input. Dc rotary-torque motor and ball-screw drive shaft activate first and second stage of compressor, utilizing inertia forces to operate check valves

Huniu, S.

Wang, W. S.

Wright, H. W., Jr.

English

NASA Technical Reports Server

Check 
Valves ri
Pressure 
Switch Reversing 
Switch 
May 1972	 B72-10210 
NASA TECH BRIEF 
Ames Research Center
	 -4r 
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. 
Two-Stage Coaxial Gas Compressor 
The problem: 
To raise the pressure of gases from a low ambient 
supply during space experiments by a system of low 
weight, size, and power input. 
I
switch, pressure switch, and associated valves. The 
DC torque motor, located centrally between the first 
and second-stage cylinders, simultaneously drives the 
two pistons by a hollow ball-screw shaft. Stroke re-
versal is accomplished by reversing the direction of 
rotation of the motor with a DPDT switch. 
The solution: 
Utilize a DC rotary-torque motor and a ball-screw 
drive shaft to activate the first and second stage of 
a miniaturized light-weight compressor, utilizing in-
ertia forces to operate check valves. 
How it's done: 
The two-stage gas-compressor assembly depicted 
in the diagram consists of an inlet filter, first- and 
second-stage pumps, DC motor, plenum, reversing
During the compression stroke, a negative pressure 
is created in the chamber behind the first-stage pis-
ton, allowing the atmosphere to enter the chamber 
through the inlet. During the suction stroke, atmos-
pheric gas enters the compression chamber through 
a large check valve located on the face of the piston. 
The compression stroke then forces the gas through 
a second check valve located at the center of the 
piston, and the gas is transferred through the center 
of the ball-screw into the second-stage cylinder. The 
(continued overleaf) I
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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=19720000210 2020-03-17T03:33:45+00:00Z
high pressure gas is then pumped into the plenum 
by the second-stage piston via the outlet check valve 
located at the end of the second-stage cylinder.
VE 
PISTC
The check valves are supported by flat flexure 
plates with essentially zero, static spring loads. Pis-
ton movement actuates the check valves by utiliza-
tion of the inherent forces developed by differential 
pressure and inertia. The low cracking pressure (vir-
tually zero) is important for proper operation of the 
first-stage suction stroke because of the low ambient 
pressure differential available at the pump inlet. 
Notes: 
1. Lightweight and small size are attactive features 
for utility of the device in portable refrigeration 
systems or general laboratory apparatus requiring 
high compression-ratio pumps. 
2. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B72-10210 
Patent status: 
No patent action is contemplated by NASA. 
Source: William S. Wang, Harvey W. Wright, Jr., 
and Sam Huniu of
TRW Systems Group, TRW, Inc.
under contract to
Ames Research Center 
(ARC-10426) 
B72-10210	 Category 06


Two-stage coaxial gas compressor

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