Automatic control system for ceiling fan based on temperature differentials

Abstract

A fan includes a hub, several fan blades, and a motor that is operable to drive the hub. A motor controller is in communication with the motor, and is configured to select the rate of rotation at which the motor drives the hub. The fan is installed in a place having a floor and a ceiling. An upper temperature sensor is positioned near the ceiling. A lower temperature sensor is positioned near the floor. The temperature sensors communicate with the motor controller, which includes a processor configured to compare substantially contemporaneous temperature readings from the upper and lower temperature sensors. The motor controller is thus configured to automatically control the fan motor to minimize the differences between substantially contemporaneous temperature readings from the upper and lower temperature sensors. The fan system may thus substantially destratify air in an environment, to provide a substantially uniform temperature distribution within the environment.

1 - 20 . (canceled) 
     
     
         21 . A fan system installed in a location having a floor and a ceiling, the fan system comprising:
 a rotatable hub;   a plurality of fan blades secured to the hub;   a motor in communication with the hub, wherein the motor is operable to drive the hub at a selectable rate of rotation;   a motor controller in communication with the motor, wherein the motor controller  is configured to select the rate of rotation at which the motor drives the hub;   an upper temperature sensor positioned near the ceiling, wherein the upper temperature sensor is configured to sense the temperature of air near the ceiling, wherein the upper temperature sensor is in communication with the motor controller; and   a lower temperature sensor positioned near the floor, wherein the lower temperature sensor is configured to sense the temperature of air near the floor, wherein the lower temperature sensor is in communication with the motor controller;   wherein the motor controller is configured to automatically adjust the rate of rotation at which the motor drives the hub from a first non-zero rate of rotation to a second non-zero of rotation based at least in part on differences between temperatures communicated from the upper temperature sensor and temperatures communicated from the lower temperature sensor.   
     
     
         22 . The fan system of  claim 21 , wherein the motor controller is configured to compare temperatures communicated from the upper temperature sensor to temperatures communicated from the lower temperature sensor. 
     
     
         23 . The fan system of  claim 22 , wherein the motor controller is configured to automatically adjust the rate of rotation at which the or drives the hub to minimize differences between temperatures communicated from the upper temperature sensor and temperatures communicated from the lower temperature sensor. 
     
     
         24 . The fan system of  claim 21 , wherein the motor controller comprises a processor and a variable frequency drive. 
     
     
         25 . The fan system of  claim 24 , wherein the upper temperature sensor and the lower temperature sensor are coupled with the processor, wherein the processor is coupled with the variable frequency drive, wherein the variable frequency drive is coupled with the motor. 
     
     
         26 . The fan system of  claim 24 , wherein the processor comprises a Proportional, Integral, Derivative (PID) controller. 
     
     
         27 . The fans systems of  claim 26 , wherein the PID is associated with a set value (SV) of zero. 
     
     
         28 . The fan system of  claim 27 , wherein the PID is further associated with a process variable (PV), wherein the process variable represents the difference between a temperature sensed by the upper temperature sensor and a temperature substantially contemporaneously sensed by the lower temperature sensor. 
     
     
         29 . The fan system of  claim 28 , wherein the PID is configured to process errors between the SV and PV values through a PI loop logic. 
     
     
         30 . The fan system of  claim 21 , wherein the motor controller is configured to provide a first mode of operation and a second mode of operation, wherein the first mode of operation includes a first upper limit on the rate of rotation at which the motor drives the hub, wherein the second mode of operation includes a second upper limit on the rate of rotation at which the motor drives the hub, wherein the second upper limit is higher than the first upper limit. 
     
     
         31 . The fan system of  claim 30 , wherein the first mode of operation further includes a first lower limit on the rate of rotation at which the motor drives the hub, wherein the second mode of operation further includes a second lower limit on the rate of rotation at which the motor drives the hub, wherein the second lower limit is higher than the first lower limit. 
     
     
         32 . A method of operating a fan comprising the steps of:
 providing a fan in a location having a floor and a ceiling, said fan comprising:
 a rotatable hub; 
 a plurality of fan blades secured to the hub; 
 a motor in communication with the hub, wherein the motor is operable to drive the hub at a selectable rate of rotation; and 
 a motor controller in communication with the motor, wherein the motor controller is configured to select the rate of rotation at which the motor drives the hub; 
   providing an upper temperature sensor for sensing a temperature near the ceiling and a lower temperature sensor for sensing a temperature near the floor;   receiving an upper temperature reading from the upper temperature sensor and a lower temperature reading from the lower sensor; and   adjusting the rate of rotation at which the motor drives the hub from a first non-zero rate of rotation to a second non-zero rate of rotation based at least in part on differences between the upper and the lower temperatures.   
     
     
         33 . The method of  claim 32 , further including the step of:
 automatically placing the motor controller in one of a first mode or second mode, wherein the motor controller is placed in the first mode when the lower temperature is below a first temperature, and wherein the motor controller is placed in the second mode when the lower temperature is above the first temperature; and   wherein the adjusting step comprises adjusting the rate or rotation to a first speed in the first mode and a second speed in the second mode, wherein the first speed is slower than the second speed.   
     
     
         34 . The method of  claim 33 , wherein the adjusting step further includes automatically adjusting the rate of rotation to minimize differences between subsequent temperature readings from the upper and lower temperature sensors. 
     
     
         35 . The method of  claim 34 , further comprising the steps of:
 continuously receiving temperature readings from the upper temperature sensor;   continuously receiving temperature readings from the lower temperature sensor; and   continuously adjusting the rate of rotation at which the motor drives the hub based at least in part on differences between the continuously received temperature readings from the upper and lower temperature sensors.   
     
     
         36 . The method of  claim 32 , further comprising the steps of:
 providing a humidity sensor for sensing a relative humidity;   receiving a relative humidity reading from the humidity sensor; and   adjusting the rate of rotation at which the motor drives the hub based further at least in part on the humidity reading.