System and methods for controlling rotary screw compressors

• US 6,533,552 B2
• Filed: 04/23/2002
• Issued: 03/18/2003
• Est. Priority Date: 11/23/1994
• Status: Expired due to Term

• Current Assignee: Quincy Compressor LLC (Atlas Copco AB)
• Original Assignee: Coltec Industries Incorporated (Enpro Industries Incorporated)
• Inventors: Burrell, Paul, Centers, Steven D.
• Primary Examiner(s): Gartenberg, Ehud
• Application Number:
  US10/131,389
• Publication Number:
  US 20020182082A1
• Time in Patent Office: 329 Days
• Field of Search: 417/12, 417/44.2, 417/53, 417/307, 417/26, 417/28, 417/290
• US Class Current: 417/12
• CPC Class Codes: F04B 2205/06 Pressure in a (hydraulic) circuit
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04C 2270/01 Load
• CPC Class Codes: F04C 2270/02 Power
• CPC Class Codes: F04C 2270/18 Pressure
• CPC Class Codes: F04C 2270/19 Temperature
• CPC Class Codes: F04C 2270/56 Number of pump/machine units in operation
• CPC Class Codes: F04C 2270/72 preventing reverse rotation
• CPC Class Codes: F04C 2270/78 Warnings
• CPC Class Codes: F04C 2270/80 Diagnostics
• CPC Class Codes: F04C 2270/86 Detection
• CPC Class Codes: F04C 28/06 specially adapted for stopping, starting, idling or no-load operation
• CPC Class Codes: F04C 28/12 using sliding valves
• CPC Class Codes: F04C 28/24 characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valvesF04C28/10 takes precedence
• CPC Class Codes: G05B 23/0213 Modular or universal configuration of the monitoring system, e.g. monitoring system having modules that may be combined to build monitoring program; monitoring system that can be applied to legacy systems; adaptable monitoring system; using different communication protocols
• CPC Class Codes: G05B 23/0286 Modifications to the monitored process, e.g. stopping operation or adapting control
• CPC Class Codes: G05D 16/2066 using controlling means acting on the pressure source
• CPC Class Codes: G06F 11/006 Identification G06F11/2289 takes precedence
• CPC Class Codes: G06F 11/2294 by remote test
• CPC Class Codes: G06F 11/327 Alarm or error message display
• CPC Class Codes: G07C 3/00 : Registering or indicating the condition or the working of machines or other apparatus, other than vehicles

Abstract

An electronic control system dynamically varies the output capacity of a compressor by controlling plural valves associated with the compressor to provide pressurized air to a distribution system at an appropriate rate. The control system operates in any of three modes for standalone operation, including continuous run, auto/dual pressure band, and target pressure modes. In the first two modes, pressure bands are dynamically calculated based on load and unload values entered by an operator. These electronic control systems can also be connected in a peer-to-peer network to coordinate control of up to 16 compressors feeding the same distribution system, so as to maintain a desired target pressure in the system. A modem connected to the system supports remote diagnostics, monitoring, and control. Specialized startup, operating, and shutdown diagnostic algorithms prevent damage to the compressor and avert unsafe operating conditions.

Claims

1. An electronic control apparatus for protecting an air compressor connected by a sump to an air pressure system, the sump having a pressure sensor measuring pressure in the sump, comprising:

input means for receiving an instruction to start the compressor;

blowdown valve means for releasing pressure from the sump in response to a control signal;

processing means, operatively connected to input means, pressure sensor, and blowdown valve means, for detecting the start instruction and starting the compressor;

storage means for storing a predetermined maximum starting sump pressure value; and

starting prevention means, operatively associated with the processing means, for preventing starting of the compressor against a load by automatically determining pressure in the sump using the sump pressure sensor, and when the determined pressure is greater than the maximum starting sump pressure value, automatically actuating the blowdown valve means to relive the pressure in the sump and delaying starting of the compressor until the pressure in the sump is below the value.

2. A method of electronically protecting an air compressor connected by a sump to an air pressure system, the sump having a pressure sensor measuring pressure in the sump, comprising the acts of:

storing a predetermined maximum starting sump pressure value;

receiving an instruction to start the compressor;

upon receiving the start instruction, automatically determining pressure in the sump using the sump pressure sensor;

when the determined pressure is greater than the maximum starting sump pressure value, automatically actuating the blowdown valve means to relive the pressure in the sump; and

delaying starting of the compressor until pressure in the sump is below the maximum starting sump pressure value to prevent starting of the pressure against a load.