Load Bearing Direct Drive Fan System With Variable Process Control

Abstract

The present invention is directed to a load bearing direct-drive system for driving a fan in a cooling system such as a wet-cooling tower, air-cooled heat exchanger, HVAC system, hybrid cooling tower, mechanical tower or chiller system. The present invention includes a variable process control system that is based on the integration of key features and characteristics such as tower thermal performance, fan speed and airflow, motor torque, fan pitch, fan speed, fan aerodynamic properties, and pump flow. The variable process control system processes feedback signals from multiple locations in order to control a high torque, low variable speed, load bearing motor to drive the fan.

What is claimed is: 
     
         1 . A heating ventilation and air-conditioning system (HVAC) comprising:
 a condenser coil;   a fan;   a variable speed, load bearing permanent magnet motor comprising a casing having an interior, a stator and rotor located in the interior of the casing for creating flux, and a rotatable shaft connected to the fan, the motor comprising a bearing system for bearing fan loads and enabling the variable speed, load bearing motor to rotate the fan in a forward direction or reverse direction, wherein rotation of the fan causes air-flow through the condenser coil, the bearing system comprising a spherical roller thrust bearing for absorbing the thrust loads resulting from the weight of the fan and the airflow produced by rotation of the fan, a cylindrical roller bearing for opposing the radial loads at the thrust end of the rotatable shaft, and a tapered roller output bearing for opposing the reverse thrust loads resulting from reverse rotation of the fan and yaw loads; and   a device to generate electrical signals that cause rotation of the rotatable shaft of the motor in order to rotate the fan.   
     
     
         2 . The heating ventilation and air-conditioning system according to  claim 1  further comprising a first bearing housing for housing the tapered roller output bearing and a second bearing housing for housing the cylindrical roller bearing and the spherical roller thrust bearing. 
     
     
         3 . The heating ventilation and air-conditioning system according to  claim 2  further comprising a first seal to isolate the first bearing housing from the interior of the casing and a second seal to isolate the second bearing housing from the interior of the casing. 
     
     
         4 . The heating ventilation and air-conditioning system according to  claim 3  wherein the motor further comprises a motor shaft seal in tandem with the first and second seals. 
     
     
         5 . The heating ventilation and air-conditioning system according to  claim 4  wherein the motor shaft seal comprises a bearing isolator. 
     
     
         6 . The heating ventilation and air-conditioning system according to  claim 1  wherein the motor comprises a load bearing permanent magnet motor. 
     
     
         7 . The heating ventilation and air-conditioning system according to  claim 1  wherein the motor includes at least one sensor for measuring vibrations and outputting signals representing the measured vibrations. 
     
     
         8 . The heating ventilation and air-conditioning system according to  claim 7  wherein the motor includes at least one temperature sensor to measure the temperature of the interior of the casing. 
     
     
         9 . The heating ventilation and air-conditioning system according to  claim 7  wherein the motor includes at least one temperature sensor positioned on the stator to measure the temperature of the stator. 
     
     
         10 . The heating ventilation and air-conditioning system according to  claim 7  further comprising a signal processor for processing the signals outputted by the at least one vibration sensor. 
     
     
         11 . The heating ventilation and air-conditioning system according to  claim 1  wherein the motor further comprises:
 at least one vibration sensor positioned within the interior of the casing; 
 at least one temperature sensor positioned within the interior of the casing; 
 an internal wiring network within the interior of the casing and electrically connected to the at least one vibration sensor and the at least one temperature sensor; 
 a signal connector attached to the casing and electrically connected to the internal wiring network; and 
 external wires connected to the signal connector for routing sensor signals to an external signal processing resource. 
 
     
     
         12 . The heating ventilation and air-conditioning system according to  claim 1  wherein the device to generate electrical signals comprises a variable frequency drive device. 
     
     
         13 . The heating ventilation and air-conditioning system according to  claim 1  wherein the device to generate electrical signals comprises a variable speed drive device. 
     
     
         14 . The heating ventilation and air-conditioning system according to  claim 1  wherein the motor is oriented such that the rotational shaft of the motor is vertically oriented. 
     
     
         15 . The heating ventilation and air-conditioning system according to  claim 1  wherein the motor is oriented such that the rotational shaft of the motor is substantially horizontal. 
     
     
         16 . The heating ventilation and air-conditioning system according to  claim 1  wherein the motor is oriented such that the rotational shaft is oriented at an angle. 
     
     
         17 . A heating ventilation and air-conditioning system (HVAC) comprising:
 a condenser coil;   a fan;   a variable speed, load bearing permanent magnet motor comprising a casing having an interior, a stator and rotor located in the interior of the casing for creating flux, and a rotatable shaft connected to the fan, the motor comprising a bearing system for bearing fan loads and enabling the variable speed, load bearing motor to rotate the fan in a forward direction or reverse direction, wherein rotation of the fan causes air-flow through the condenser coil, the bearing system comprising a spherical roller thrust bearing for absorbing the thrust loads resulting from the weight of the fan and the airflow produced by rotation of the fan, a cylindrical roller bearing for opposing the radial loads at the thrust end of the rotatable shaft, and a tapered roller output bearing for opposing the reverse thrust loads resulting from reverse rotation of the fan and yaw loads, said motor further comprising at least one vibration sensor positioned within the interior of the casing, at least one temperature sensor positioned within the interior of the casing, an internal wiring network within the interior of the casing and electrically connected to the at least one vibration sensor and the at least one temperature sensor, a signal connector attached to the casing and electrically connected to the internal wiring network, and external wires connected to the signal connector for routing sensor signals to a signal processing resource; and   a device to generate electrical signals that cause rotation of the rotatable shaft of the motor in order to rotate the fan.