Method and apparatus for controlling air-conditioning systems

• US 4,136,732 A
• Filed: 04/19/1977
• Issued: 01/30/1979
• Est. Priority Date: 02/26/1976
• Status: Expired due to Term

• Current Assignee: Ranco Incorporated of Delaware (Schneider Electric SE)
• Original Assignee: Ranco, Inc. (Schneider Electric SE)
• Inventors: Attridge, Russell G. Jr., Demaray, Merlin E.
• Primary Examiner(s): Myhre, Charles J.
• Assistant Examiner(s): LaTulip, Margaret
• Application Number:
  US05/788,834
• Time in Patent Office: 651 Days
• Field of Search: 165/16, 165/22, 165/27, 165/14, 236/44 C, 236/49, 62/89
• US Class Current: 165/216
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/46 Improving electric energy efficiency or saving
• CPC Class Codes: F24F 11/76 by means responsive to temperature, e.g. bimetal springs
• CPC Class Codes: F24F 11/88 Electrical aspects, e.g. circuits
• CPC Class Codes: F24F 2011/0002 for admittance of outside air
• CPC Class Codes: F24F 2011/0006 using low temperature external supply air to assist cooling
• CPC Class Codes: F24F 2110/10 Temperature
• CPC Class Codes: F24F 3/0527 in which treated air having differing temperatures is conducted through independent conduits from the central station to various spaces to be treated, i.e. so-called "multi-Zone" systems F24F3/0525 takes precedence
• CPC Class Codes: G05D 23/1912 whose output amplitude can take more than two discrete values
• CPC Class Codes: G05D 23/1934 each space being provided with one sensor acting on one or more control means
• CPC Class Codes: G05D 23/20 with sensing elements having variation of electric or magnetic properties with change of temperature G05D23/13 takes precedence
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor

Abstract

An air conditioning system controlled for automatically heating and/or cooling a multiple zone building is disclosed wherein each zone includes a zone temperature responsive load transmitter. Each load transmitter produces an output command signal for controlling operation of damper units and heating and cooling equipment. The command signal configuration is modified to avoid operation of heating and cooling equipment throughout a relatively wide "no load" band of zone temperatures centered around the zone set point temperature. The command signal is highly responsive to sensed zone temperature changes beyond the no load band so that the zone temperature tends to be maintained in the no load band.

An alternative system is disclosed in which no load bands occur at two distinct command signal values and operation of damper units is effected when the command signal value shifts between the no load band values.

Claims

1. In an air conditioning system wherein heating and cooling means are employed to alter air temperature in a zone and a temperature responsive control system governs operation of the heating and cooling means, the zone temperature control system comprising:

(a) sensor means for sensing zone air temperature conditions;

(b) command signal generator means connected to said sensor means for producing a command signal which is variable throughout first and second value ranges as a function of sensed temperature conditions;

(c) controller means connected to said signal generator means for effecting operation of the heating and cooling means, said controller means responsive to command signal values in said first range to control operation of one of said heating and cooling means and responsive to command signal values in said second range to control the other of said heating and cooling means; and

,

(d) command signal modifier means rendered effective between said first and second command signal value ranges to substantially prevent said command signal from changing value in response to changes in sensed zone temperature conditions between first and second predetermined temperature condition levels, said controller means maintained ineffective to operate either said heating means or said cooling means when zone temperature condition levels are between said first and second levels.

2. The system claimed in claim 1 wherein said command signal modifier means includes switching means effective to establish first and second constant predetermined command signal values when the zone temperature conditions are between said predetermined levels, said switching means effective to establish said first predetermined command signal value in response to command signal variations from said first value range toward said second value range, said switching means effective to establish said second predetermined command signal value in response to command signal variations from said second toward said first value range.

3. In a forced air multiple zone air conditioning system having heating equipment for heating air supplied to the zones, cooling equipment for cooling air supplied to the zones and air damper units for controlling air flow to the zones via the heating and cooling equipment, a control system comprising:

(a) zone temperature condition sensing means for producing a zone condition signal;

(b) command function generator means for producing a variable value command signal in response to varying zone condition signals;

(c) controller means for governing operation of said heating and cooling equipment in response to the command signal, said controller means operating said heating equipment during a first command signal value range and operating said cooling equipment during a second command signal value range;

(d) said damper units connected to said command function generator for altering air flow in said air conditioning system in response to command signal value changes in a third value range between said first and second value ranges, said damper units effective to alter air flow compatibly with operation of said heating equipment as the command signal values approach said first range of values and effective to alter air flow compatibly with operation of said heating equipment as the command signal values approach said second range of values;

(e) said command function generator means comprising a command signal generator and a command signal modifier, said command signal modifier rendered effective at a command signal value between said first and second value ranges and coacting with said command signal generator to substantially prevent said command signal value from changing throughout a predetermined range of sensed zone temperatures.