System and methods for controlling rotary screw compressors

A method of electronically controlling a plurality of valves of an air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor, comprising the steps of:

• entering an instruction into a multi-modal electronic control apparatus specifying any of at least three pressure control operating modes, said modes including a target pressure mode, a pressure band mode, and a network multiple machine mode;
• if the target pressure mode is selected, automatically varying the output capacity of the compressor using the electronic control apparatus to maintain a specified target air system pressure at said pressure sensor;
• if the pressure band mode is selected, automatically selectively actuating each of said plurality of valves using the electronic control apparatus depending on a relationship between the system pressure measured by said pressure sensor means and a pressure band associated with that valve to maintain system pressure within a predetermined range;
• and
• if the network multiple machine mode is selected, automatically varying the output capacity of the compressor using the electronic control apparatus in response to a value calculated based on pressure measurements reported by a plurality of other electronic control apparatus operating in a network connection with said electronic control apparatus.

A method for electronically controlling a plurality of capacity reduction valves of an air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor and a plurality of similar compressors each having a plurality of capacity reduction valves, comprising the steps of:

• connecting an electronic control apparatus associated with the air compressor to a plurality of other like control apparatus in a peer-to-peer configuration network, each other control apparatus in the network being associated with its own compressor and pressure sensor means;
• using the network, transmitting status information of the electronic control apparatus to said other control apparatus and receiving and storing status information from said other control apparatus, said status information including values measured by said pressure sensor means of each apparatus in the network;
• and;
• automatically varying the output capacity of the compressor by operating the capacity reduction valves therefor in response to a parameter calculated based on a plurality of said values from different points in the network.

A method for electronically controlling a plurality of valves of an air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor, comprising the steps of:

• connecting an electronic control apparatus associated with the compressor to a plurality of other like control apparatus in a peer-to-peer configuration network, each other control apparatus in the network being associated with its own compressor;
• transmitting status information of the electronic control apparatus to said other control apparatus and receiving and storing status information from said other control apparatus;
• receiving a pointer signal from one of said other control apparatus authorizing variation in the output capacity of the compressor, and in response automatically varying the output capacity of the compressor to maintain the desired air pressure in the air system;
• transmitting said pointer signal to another of said other electronic control apparatus if the output capacity of the compressor has been reduced to a predetermined level;
• storing a unique identification code in non-volatile memory to identify an order in which said pointer signal should be transmitted to and from said electronic control apparatus;
• and
• preventing variation in the output capacity of the compressor when said pointer signal has not been received or has been transmitted to another electronic control apparatus.

An electronic control system for a single compressor connected to a pressure system in which pressure is to be maintained within a desired pressure range by varying an output capacity of the compressor, the pressure system having a pressure sensor measuring pressure in the pressure system, and the compressor having a plurality of electrically actuated capacity reduction valves which can be selectively actuated to vary the compressor output capacity, comprising:

• input means for receiving an operator input specifying a loaded pressure and an unloaded pressure, said loaded pressure and said unloaded pressure defining the boundaries of the desired pressure range;
• processing means connected to the input means, the pressure sensor, and the capacity reduction valves, for:
• receiving signals identifying the specified loaded pressure and unloaded pressure;
• storing, for each of a plurality of pressure bands covering at least the desired pressure range, open and close values of each said pressure band, and storing information associating at least one of the capacity reduction valves with each said pressure band;
• receiving a signal from the pressure sensor indicating the pressure measured by the pressure sensor;
• determining for each capacity reduction valve a required valve status specifying whether the capacity reduction valve should be opened or closed, depending on the relationship between the open and close values of the pressure band associated with the capacity reduction valve and the measured pressure;
• and changing the open or closed state of the capacity reduction valves to match the required valve status of the capacity reduction valves;
• and
• dynamic pressure band calculating means associated with the processing means for recalculating the open and close values of each pressure band whenever at least one of the input loaded pressure and input unloaded pressure are changed by the operator, such that the calculated open and close values vary with the loaded pressure and unloaded pressure input by the operator.

An electronic control apparatus for controlling a plurality of valves of a single air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor, comprising:

• pressure sensor means for measuring air pressure in the air system;
• input means for receiving an operator input specifying one of at least three pressure control operating modes, said modes including a target pressure mode, a pressure band mode, and a network multiple machine mode;
• processing means connected to the input means, the compressor, and the pressure sensor means, for receiving the operator input specifying the operating mode, and in response thereto, selectively controlling the valves of the compressor to vary its output capacity such that
• (a) when the target pressure mode is selected, the output capacity of the compressor is varied to maintain a specified target air system pressure at said pressure sensor;
• (b) when the pressure band mode is selected, each of said plurality of valves are selectively actuated depending on a relationship between the system pressure measured by said pressure sensor means and a pressure band associated with that valve to maintain system pressure within a predetermined range;
• and
• (c) when the network multiple machine mode is selected, the output capacity of the compressor is varied in response to a value calculated based on pressure measurements reported by a plurality of other electronic control apparatus operating in the same network multiple machine mode and connected together in a network.

An electronic control apparatus for controlling a plurality of valves of a single air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor and a plurality of other compressors, each with similar valves and an electronic control apparatus therefor, comprising:

• pressure sensor means for measuring a pressure in the air system proximate to an output of the compressor;
• network connection means for connecting the electronic control apparatus to a plurality of other like control apparatus in a peer-to-peer configuration network, each other control apparatus in the network being associated with its own compressor and pressure sensor means;
• status communication means connected to the network connection means for transmitting status information of the electronic control apparatus to said other control apparatus and for receiving and storing status information from said other control apparatus, said status information including values measured by said pressure sensor means of each apparatus in the network;
• processing means connected to the compressor, the pressure sensor means, and the status communication means for controlling the plurality of values for the compressor to vary the output capacity of the compressor in response to a parameter calculated based on a plurality of said values from different points in the network.

An electronic control apparatus for controlling a plurality of valves of an air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor, comprising:

• pressure sensor means for measuring a pressure in the air system;
• network connection means for connecting the electronic control apparatus to a plurality of other like control apparatus in a peer-to-peer configuration network, each other control apparatus in the network being associated with its own compressor;
• status communication means connected to the network connection means for transmitting status information of the electronic control apparatus to said other control apparatus and for receiving and storing status information from said other control apparatus;
• processing means connected to the compressor, the pressure sensor means, and the status communication means for selectively varying the output capacity of the compressor to maintain desired pressure in the air system;
• pointer control means connected to said network connection means for receiving a pointer signal from one of said other control apparatus authorizing said processing means to vary the output capacity of the compressor, for transmitting said pointer sign, at to another of said other electronic control apparatus if the output capacity of the compressor has been reduced to a predetermined level, and for preventing variation in the output capacity of the compressor when said pointer signal has not been received or has been transmitted to another electronic control apparatus;
• and
• storage means for storing a unique identification code in non-volatile memory to identify the order in which said pointer signal should be transmitted to said electronic control apparatus.

A method of electromechanically controlling output capacity of a rotary screw air compressor to maintain desired air pressure in an air system fed by the compressor, comprising the steps of:

• installing a plurality of double acting lift valves in the compressor for selectively reducing capacity of the compressor, said valves being air operated in response to electronic valve control signals to provide both positive opening and positive closing action;
• electronically monitoring operation of the compressor and the pressure in the air system using an electronic control apparatus;
• automatically determining which of said plurality of valves should be open to maintain desired air pressure;
• and
• selectively generating said electronic valve control signals and varying said signals to cause positive opening and positive closing of said double acting lift valves.

An electronic control apparatus for controlling an air compressor to maintain desired air pressure in an air system fed by the compressor, comprising:

• network connection means for connecting the electronic control apparatus to a plurality of other like control apparatus in a peer-to-peer configuration network, each other control apparatus in the network being associated with its own compressor;
• status communication means connected to the network connection means for transmitting status information of the electronic control apparatus to said other control apparatus and for receiving and storing status information from said other control apparatus;
• processing means connected to the compressor and the status communication means for varying the output capacity of the compressor;
• and
• modem means connected to the processing means for transmitting said status information for each connected control apparatus in the network to monitoring station at a location remote from the network.

An electronic control apparatus for controlling a plurality of valves of a single air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor and a plurality of other compressors, each with similar valves and an electronic control apparatus therefor, comprising:

• network connection means for connecting the electronic control apparatus to a plurality of other like control apparatus in a network, each other control apparatus in the network being associated with its own compressor;
• status communication means connected to the network connection means for transmitting status information of the electronic control apparatus to said other control apparatus and for receiving and storing status information from said other control apparatus;
• processing means connected to the compressor and the status communication means for selectively varying the output capacity of the compressor to maintain desired pressure in the air system;
• pointer control means connected to said network connection means for receiving a pointer signal from one of said other control apparatus authorizing said processing means to vary the output capacity of the compressor, for transmitting said pointer signal to another of said other electronic control apparatus if the output capacity of the compressor has been reduced to a predetermined level, and for preventing variation in the output capacity of the compressor when said pointer signal has not been received or has been transmitted to another electronic control apparatus;
• storage means for storing a unique identification code in non-volatile memory to identify the order in which said pointer signal should be transmitted to said electronic control apparatus;
• and
• scheduling means associated with said pointer control means for storing a plurality of sequences of said unique identification codes and automatically selectively activating one of said sequences for pointer signal transmission in the network, with the selection of the sequence dependent on the current time.

A method for electronically controlling a plurality of valves of a single air compressor to vary an output capacity of the compressor to maintain desired air pressure in an air system fed by the compressor, comprising the steps of:

• connecting an electronic control apparatus associated with the compressor to a plurality of other like control apparatus in a network, each other control apparatus in the network being associated with its own compressor feeding said air system;
• transmitting status information of the electronic control apparatus to said other like control apparatus and receiving and storing status information from said other like control apparatus;
• receiving a pointer signal from one of said other like control apparatus authorizing variation in the output capacity of the compressor, and in response automatically varying the output capacity of the compressor by controlling at least one of said plurality of valves to maintain the desired air pressure in the air system;
• transmitting said pointer signal to another of said other like control apparatus if the output capacity of the compressor has been reduced to a predetermined level;
• storing a unique identification code in non-volatile memory to identify an order in which said pointer signal should be transmitted to and from said electronic control apparatus;
• preventing variation in the output capacity of the compressor when said pointer signal has not been received or has been transmitted to another like electronic control apparatus;
• and
• storing a plurality of sequences of said unique identification codes, and selectively activating one of said sequences for pointer signal transmission in the network, with the selection of the sequence dependent on the current time.