System and method for controlling rotary screw compressors

• US 6,450,771 B1
• Filed: 07/24/2000
• Issued: 09/17/2002
• 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:
  US09/624,083
• Time in Patent Office: 785 Days
• Field of Search: 417/18, 417/280, 417/36, 417/12, 417/53, 417/44.2
• 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. A system for electronically preventing reverse rotation operation in a rotary air compressor connected by a sump to an air pressure system, the system comprising:

a pressure sensor for measuring positive pressure operatively positioned in the sump;

means, operatively connected to the system, for storing a wait time and a predetermined minimum operating pressure value;

means, operatively connected to the system, for receiving an instruction to start the compressor;

means, operatively connected to the receiving means, for detecting the start instruction;

means, operatively connected to the detecting means, for starting the compressor;

means, operatively connected to the storing means, for automatically retrieving the wait time and the predetermined minimum operating positive pressure value;

means, operatively connected to the retrieving means, for automatically waiting until the expiration of the wait time after starting of the compressor and then determining the magnitude of the positive pressure in the sump using the sump pressure sensor; and

means, operatively connected to the compressor, for automatically stopping the compressor if the determined pressure is less than the predetermined minimum operating positive pressure value at the expiration of the wait time.

2. The system of claim 1 further comprising:

means, operatively connected to the stopping means, for providing a reverse rotation indication.

3. A method of electronically preventing reverse rotation operation in a rotary air compressor connected by a sump to an air pressure system, the method comprising the acts of:

operatively positioning a pressure sensor in the sump for measuring positive pressure;

storing a wait time and a predetermined minimum operating pressure value;

receiving an instruction to start the compressor;

after detecting the start instruction, starting the compressor;

automatically retrieving the wait time and predetermined minimum operating positive pressure value;

after waiting until the expiration of the wait time after starting the compressor, determining the magnitude of the positive pressure in the sump using the sump pressure sensor; and

if the determined pressure is less than the predetermined minimum operating positive pressure value at the expiration of the wait time, stopping the compressor.

4. The method of claim 3 further comprising the act of:

providing a reverse rotation indication.