Compressor Reed Valve (6044862)
Inventors: Stanley Schumann, Frank Wallis, Jason Beresik, Ernie Bergman, Deborah Monnin. Issued April 04, 2000 in United States
Scroll Machine with Capacity Modulation (6116867)
Inventors: Frank Wallis, Stan Schumann, Jeff Berning. Issued September 12, 2000 in United States
Scroll Machine with Capacity Modulation (6120255)
Inventors: Stan Schumann, Don Fiegel, Jeff Berning. Issued September 19, 2000 in United States
Scroll Machine with Capacity Modulation (6176686)
Inventors: Frank Wallis, Stan Schumann, Jeff Berning. Issued January 23, 2001 in United States
Air Compressors for Passenger Rail Applications
Published by (Proceedings of the Nineteenth International Compressor Engineering Conference at Purdue)
Authors: Stan Schumann. Published July 14, 2008
Passenger transit rail systems rely on compressed air for brake and suspension systems. These applications pose
design challenges for the compressor system not usually faced by industrial applications. The air supply is packaged
as a self-contained system generally containing a compressor, electric drive motor, air dryer system, and controls.
The air system supplier initially furnishes the system to a car builder under contract to a transit authority. Both the
car builder and the transit authorities publish specifications for package size, materials, and workmanship constraints
making each compressor system custom designed for the application.
General trends in the industry include the extension of overhaul and maintenance on the air system. In order to meet
these new requirements, it was necessary to determine exactly how these systems operate in the field in terms of
running time and cycle rate. To this end, air supply systems were instrumented with simple logging systems to
monitor compressor operation. A summary from field studies from various locations is presented.
Measurement of Orbiting Scroll Motion
Published by (Proceedings of the Twelfth International Compressor Engineering Conference at Purdue)
Authors: Stan Schumann. Published July 19, 1994
In a scroll compressor, the orbit path of the moving scroll is important to ensure an efficient
product. Any deviation from a circle during running indicates a flank separation causing leakage
and a loss of efficiency.
During compressor shutdown, the motion is also important as it is an indication of radial
unloading and the pressure equalization time across the compressor. At startup, the motion
indicates the relative speed of compressor loading and can increase or decrease starting torque
requirements for the compressor.
Unfortunately, the orbit measurement can be difficult to make. This paper describes a method
to measure the orbit using four cantilever beams. By fixing two beams to the bearing housing and
two others to the oldham ring, with proper calibration the orbit can be referenced to the bearing
Evaluation of Residential Heat Pump Operation using a Binned Time Method
Published by (Proceedings of the XVIIIth International Congress of Refrigeration)
Authors: Stan Schumann, Tom Bodey. Published July 10, 1991
The use of data from existing heat pump systems assists in the selection of accelerated testing conditions for a residential heat pump compressor. Data are accumulated into time bins and graphically displayed for easier comprehension
3420 - Real Gas Critical Flow Factors for R-1 2, R-22 and R-502
Published by (ASHRAE Transactions, vol. 96, pt. 2, St. Louis 1990)
Authors: Stan Schumann. Published June 09, 1990
Critical flow devices, either venturis or nozzles operating at choked conditions, are popular as transfer standards and metering devices. Stagnation temperature and pressure upstream of the nozzle determine the flow rate, provided downstream pressure is low enough to ensure choked flow. Such devices are consistent and make excellent transfer standards for many laboratories. Introduces the concept of critical flow devices to the refrigeration industry, as well as provide basic tables for their use.