Adjustable fan speed

Abstract

A fan assembly includes a fan and a control module. The fan includes an adjustable fan speed. The fan generates a rate of air flow in a direction to cool a power supply unit of an electronic system based on the adjustable fan speed. The control module includes a comparator having a plurality of comparator inputs and a comparator output. The control module communicates with the fan to adjust the adjustable fan speed based on a value provided by the comparator output.

What is claimed is: 
     
         1 . A fan assembly usable with a power supply unit of an electronic system, the fan assembly comprising:
 a fan having an adjustable fan speed, the fan to generate a rate of air flow in a direction to cool the power supply unit, based on the adjustable fan speed; and   a control module including a comparator having a plurality of comparator inputs and a comparator output, the control module to communicate with the fan to adjust the adjustable fan speed based on a value provided by the comparator output.   
     
     
         2 . The fan assembly of  claim 1 , wherein a respective one of the comparator inputs is configured to receive a positive input with a fan input level and another one of the comparator inputs is configured to receive a negative input from the electronic system. 
     
     
         3 . The fan assembly of  claim 2 , wherein the control module is configured to adjust the adjustable fan speed in response to a change in the value of the comparator output. 
     
     
         4 . The fan assembly of  claim 2 , wherein the control module is configured to increase the adjustable fan speed in response to an increase in the value of the comparator output. 
     
     
         5 . The fan assembly of  claim 2 , wherein the control module is configured to decrease the adjustable fan speed in response to a decrease in the value of the comparator output. 
     
     
         6 . The fan assembly of  claim 2 , wherein the control module is configured to change a frequency of a pulse width modulation (PWM) signal to form a changed PWM signal, and provide the changed PWM signal to the fan. 
     
     
         7 . The fan assembly of  claim 2 , wherein the control module is configured to control the fan to generate a rate of air flow in a respective direction based on a change-of-direction condition. 
     
     
         8 . The fan assembly of  claim 7 , wherein the control module is configured to change the direction of the air flow generated by the fan based on the change-of-direction condition. 
     
     
         9 . The fan assembly of  claim 7 , wherein the change-of-direction condition corresponds to a second fan of the electronic system generating a rate of air flow in an opposite direction than the air flow direction generated by the fan. 
     
     
         10 . An electronic system, comprising:
 a plurality of electronic components;   a power supply unit to provide power to the electronic components; and   a fan assembly including a fan and a control module;
 the fan having an adjustable fan speed, the fan to generate a rate of air flow in a direction to cool the power supply unit based on the adjustable fan speed; and 
 the control module including a comparator having a plurality of comparator inputs and a comparator output, the control module to communicate with the fan to adjust the adjustable fan speed based on a value provided by the comparator output. 
   
     
     
         11 . The electronic system of  claim 10 , wherein the fan assembly further comprises:
 a second fan to cool the electronic components, the second fan to generate a rate of air flow in a direction.   
     
     
         12 . The electronic system of  claim 11 , wherein the control module is configured to control the fan to change the direction of air flow generated by the fan based on a respective direction of air flow generated by the second fan. 
     
     
         13 . A method of controlling a fan to cool a power supply unit of an electronic system, the method comprising:
 generating a rate of air flow in a direction by the fan with an adjustable fan speed to cool the power supply unit based on the adjustable fan speed; and   communicating with the fan by a control module including a comparator having a plurality of comparator inputs and a comparator output to adjust the adjustable fan speed based on a value provided by the comparator output such that the control module adjusts the adjustable fan speed in response to a change in the value of the comparator output.   
     
     
         14 . The method of  claim 13 , wherein the communicating with the fan by a control module including a comparator having a plurality of comparator inputs and a comparator output to adjust the adjustable fan speed further comprises:
 increasing the adjustable fan speed in response to an increase in the value of the comparator output; and   decreasing the adjustable fan speed in response to a decrease in the value of the comparator output.   
     
     
         15 . The method of  claim 13 , further comprising:
 controlling the fan by the control module to change the direction of air flow generated by the fan based on a change-of-direction condition.