Method and apparatus for variable frequency controlled compressor and fan

Abstract

The present invention provides a variable frequency controlled refrigerant compressor in a dehydrator for compressed air or other cases. In particular, the present invention detects changes in a demand on the pneumatic air supply by monitoring a pressure of a refrigerant system associated with the air supply. Based on the changes in the refrigerant system pressure, a motor speed controller generates and sends a control signal to the variable speed compressor to adjust the speed of the variable speed compressor based on the demand in the air supply.

1 . An apparatus for controlling the operating speed of at least one condenser fan motor in a refrigerated gas drying system having changing demand or a gas supply, the apparatus comprising: 
 a demand sensor capable of sensing changes in the demand on the gas supply and generating a change in demand signal; and    a fan speed controller that receives the change in demand signal to generate a condenser fan speed signal, wherein the fan speed controller is adapted to send the condenser fan speed signal to the at least one condenser fan to change the speed of the at least one condenser fan such that the speed of the at least one condenser fan is based on the sensed demand.    
   
   
       2 . The apparatus of  claim 1  wherein the demand sensor senses condensing pressure.  
   
   
       3 . A refrigerated gas drying system, comprising: 
 a refrigerant circuit having an evaporator, at least one variable speed compressor, and a condenser;    a gas supply demand sensor adapted to sense changes in a demand on a gas supply circuit; and    a motor speed controller for receiving the sensed changes in the demand of the gas supply and supplying a motor speed control signal to the at least one variable speed compressor to control the speed of the compressor based on the demand on the air supply.    
   
   
       4 . The refrigerated gas drying system of  claim 3  wherein the gas is air.  
   
   
       5 . The refrigerated gas drying system of  claim 3  wherein the motor speed control signal is supplied to a condenser fan motor to control the speed of the condenser fan motor based on the demand on the air supply.  
   
   
       6 . The refrigerated air drying system of  claim 3  wherein the demand sensor generates a demand signal and sends the demand signal to the motor speed controller.  
   
   
       7 . The refrigerated air drying system of  claim 3 , further comprising at least one non-variable speed compressor such that the motor speed controller turns on the at least one non-variable speed compressor when demand on the air supply is greater than a capacity of the variable speed compressor.  
   
   
       8 . The refrigerated air drying system of  claim 7  wherein a capacity of the at least one non-variable speed compressor is approximately one-half the capacity of the variable speed compressor.  
   
   
       9 . The refrigerated gas drying system of  claim 3 , further comprising at least one unload device such that the motor speed controller de-energizes the at least one unload device when demand on the gas supply is greater than a capacity of the variable speed compressor with the at least one unload device energized.  
   
   
       10 . The refrigerated gas drying system of  claim 9  wherein a capacity with the at least one unload device energized is approximately one-third the total capacity of the variable speed compressor.  
   
   
       11 . The refrigerated air drying system of  claim 3 , further including at least a second variable speed compressor.  
   
   
       12 . The refrigerated air drying system of  claim 11  wherein a capacity of the at least one variable speed compressor is approximately equal to a capacity of the at least a second variable speed compressor.  
   
   
       13 . A motor speed control system for a heat exchanger system having a pump with a pump motor, a fan with a fan motor, and a demand sensor, the motor speed control system comprising: 
 a pump motor speed controller adapted to receive the sensed demand, the pump motor speed controller determines a pump motor speed based on the sensed demand and generates a pump motor speed signal, wherein the pump motor speed controller is adapted to send the pump motor speed signal to the pump motor so that the pump motor speed corresponds to the sensed demand; and    a fan motor speed controller adapted to receive the sensed demand, the fan motor speed controller determines a fan motor speed based on the sensed demand pressure and generates a fan motor speed signal, wherein the fan motor speed controller is adapted to send the fan motor speed signal to the fan motor so that the fan motor speed corresponds to the sensed demand.    
   
   
       14 . The system according to  claim 13  wherein the pump motor speed controller is adapted to receive the sensed demand from the fan motor speed controller.  
   
   
       15 . The system according to  claim 13  wherein the fan motor speed controller is adapted to receive the sensed demand from the pump motor speed controller.  
   
   
       16 . The system according to  claim 13  wherein the pump motor speed is controllable between a pump motor minimum speed and a pump motor maximum speed.  
   
   
       17 . The system according to  claim 16  wherein the fan motor speed is controlled independent the pump motor speed.