Contra-rotating axial fan system and transmission for dry and evaporative cooling equipment

Abstract

A contra-rotating fan system for evaporative cooling equipment and air-cooled heat exchangers. The system can include a first axial fan disposed in an air conduit of an evaporative equipment unit, a second axial fan disposed in the air conduit and arranged coaxially with the first fan, a transmission for driving the first axial fan and the second axial fan and a motor for driving the transmission, wherein the direction of rotation of the first axial fan is opposite to the direction of rotation of the second axial fan.

What is claimed is: 
     
         1 . A contra-rotating fan system for evaporative cooling equipment, comprising:
 an evaporative cooling equipment unit enclosure having evaporation fill therein;   an air conduit coupled to the unit enclosure and having a narrower width than the unit enclosure;   a first axial fan disposed in the air conduit;   a second axial fan disposed in the air conduit and arranged coaxially with the first fan, walls of the air conduit closely enclosing the tips of the first axial fan and the second axial fan;   a power transmission structure configured to drive the first axial fan and the second axial fan,   wherein the power transmission structure comprises (a) a lower drive unit having a first drive assembly with a first predetermined drive ratio and (b) an upper drive unit having a second drive assembly with a second predetermined drive ratio,   wherein the first drive assembly comprises a center pinwheel driver, an outer pinwheel receiver, and a plurality of intermediate pinwheels,   wherein the lower drive unit is operatively coupled to a motor, the lower drive unit being configured to
 (1) drive the upper drive unit, and 
 (2) rotate the first axial fan at a first speed of rotation in a first direction; and 
   a motor for driving the power transmission structure, the motor, and the power transmission structure driving the first axial fan and the second axial fan with at least one speed configured to (i) maintain airflow through the air conduit at a minimum value necessary to maintain an endothermic process of evaporative cooling, and (ii) maintain static pressure within the unit enclosure at a minimum value necessary to move air through the unit enclosure at the minimum value of airflow;   wherein the direction of rotation of the first axial fan is opposite to the direction of rotation of the second axial fan.   
     
     
         2 . The fan system of  claim 1 , wherein the speed of rotation of the first axial fan is different from the speed of rotation of the second axial fan. 
     
     
         3 . The fan system of  claim 1 , wherein the air conduit comprises an air discharge conduit. 
     
     
         4 . The fan system of  claim 1 , wherein the air conduit comprises an air-intake conduit. 
     
     
         5 . The fan system of  claim 1 , wherein the conduit has an internal width, and wherein at least the first axial fan has a blade width which is no less than about 90% of the conduit internal width. 
     
     
         6 . The fan system of  claim 1 , wherein the power transmission structure comprises at least one shaft disposed in the enclosure and in the air conduit. 
     
     
         7 . The fan system of  claim 1 , wherein the at least one shaft comprises two shafts. 
     
     
         8 . An evaporative cooling equipment unit, comprising:
 an evaporative cooling equipment unit enclosure;   at least one air conduit coupled to the enclosure, the at least one air conduit being narrower than the unit enclosure;   a first axial fan disposed in the at least one air conduit;   a second axial fan disposed in the at least one air conduit and arranged coaxially with the first fan, walls of the at least one air conduit closely enclosing the tips of the first axial fan and the second axial fan;   a motor; and   a transmission structure operatively coupled to the motor, to the first axial fan, and to the second axial fan,   wherein the transmission structure drives the first axial fan in an opposite direction of rotation to the second axial fan, and   wherein the motor and the transmission structure drive the first axial fan and the second axial fan with at least one speed configured to (i) maintain airflow through the at least one air conduit at a minimum value necessary to maintain an endothermic process of evaporative cooling, and (ii) maintain static pressure within the unit enclosure at a minimum value necessary to move air through the unit enclosure at the minimum value of airflow.   
     
     
         9 . The evaporative cooling equipment unit of  claim 8 , wherein the speed of rotation of the first axial fan is different than the speed of rotation of the second axial fan. 
     
     
         10 . The evaporative cooling equipment unit of  claim 8 , wherein the transmission structure comprises (a) a lower drive unit having a first drive assembly with a first predetermined drive ratio, and (b) an upper drive unit having a second drive assembly with a second predetermined drive ratio,
 wherein the first drive assembly comprises a center pinwheel driver, an outer pinwheel receiver, and a plurality of intermediate pinwheels, and   wherein the lower drive unit is operatively coupled to a motor, the lower drive unit being configured to (1) drive the upper drive unit, and (2) rotate the first axial fan at a first speed of rotation in a first direction.   
     
     
         11 . The evaporative cooling equipment unit of  claim 8 , wherein the transmission structure comprises:
 a first output shaft coupled to the first axial fan and driven in a first direction; and   a hub operatively coupled to the first output shaft and the second axial fan, the hub adapted to drive the second axial fan in a direction opposite to the first direction.   
     
     
         12 . The evaporative cooling equipment unit of  claim 8 , wherein the motor is directly coupled to the transmission structure. 
     
     
         13 . The evaporative cooling equipment unit of  claim 8 , wherein the at least one air conduit comprises an air discharge conduit. 
     
     
         14 . The evaporative cooling equipment unit of  claim 8 , wherein the at least one air conduit comprises an air intake conduit. 
     
     
         15 . The evaporative cooling equipment unit of  claim 8 , wherein the transmission structure comprises at least one shaft disposed in the enclosure and in the air conduit. 
     
     
         16 . An evaporative cooling equipment contra-rotating fan system, comprising:
 an evaporative cooling equipment unit enclosure;   an air conduit coupled to the enclosure and being narrower than the unit enclosure;   a first axial fan and a second axial fan disposed inside the air-restricted conduit and arranged coaxially with respect to each other, walls of the conduit closely enclosing the tips of the first axial fan and the second axial fan;   a transmission structure for driving the first axial fan and the second axial fan in opposite rotational directions, the transmission structure having first and second shafts respectively coupled to the first and second axial fans and extending from the enclosure into the air conduit; and   means for driving the transmission to (i) maintain airflow through the air conduit at the minimum value necessary to maintain an endothermic process of evaporative cooling, and (ii) maintain static pressure within the unit enclosure at a minimum value necessary to move air through the unit enclosure at the minimum value of airflow.   
     
     
         17 . The evaporative cooling equipment contra-rotating fan system of  claim 16 , wherein the transmission structure comprises (a) a lower drive unit having a first drive assembly with a first predetermined drive ratio, and (b) an upper drive unit having a second drive assembly with a second predetermined drive ratio,
 wherein the first drive assembly comprises a center pinwheel driver, an outer pinwheel receiver, and a plurality of intermediate pinwheels; and   wherein the lower drive unit is operatively coupled to a motor, the lower drive unit being configured to (1) drive the upper drive unit, and (2) rotate the first axial fan at a first speed of rotation in a first direction.   
     
     
         18 . The evaporative cooling equipment contra-rotating fan system of  claim 17 , wherein the second drive assembly comprises a center pinwheel receiver and a second plurality of intermediate pinwheels. 
     
     
         19 . The evaporative cooling equipment contra-rotating fan system of  claim 17 , wherein said first plurality of intermediate pinwheels and said second plurality of intermediate pinwheels are configured to rotate at the same rotation per minute. 
     
     
         20 . The evaporative cooling equipment contra-rotating fan system of  claim 17 , wherein each of said first plurality of intermediate pinwheels is operatively coupled to a corresponding one of said second plurality of intermediate pinwheels.