Technique for sensing altitude from fan speed

Abstract

A DC fan, or lot of DC fans is characterized at a constant voltage to determine the variation of their rotational speed with respect to altitude. Many such DC fans will have a substantially linear response in speed with respect to altitude. From this relationship, a converter is constructed to convert the rotational speed into an altitude. The converter may be a discrete electronic device including a look up table or capable of performing the arithmetic algorithm representing the relationship between fan speed and altitude. Alternatively, the converter may be incorporated into the system to be cooled by the DC fan. For example, it may be a software routine run by the computer that the DC fan is used to cool.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is related to application Ser. No. xx / xxx,xxx entitled, “Utilizing an Altitude Sensor to Control Fan Speed,” filed on or about the same date as the present application, and hereby incorporated herein by reference. Application Ser. No. xx / xxx,xxx discloses and claims a technique utilizing the altitude calculated from the fan speed in a method to set a fan speed sufficient to allow for proper processor thermal margin.FIELD OF THE INVENTION [0002] The present invention relates generally to the field of cooling technologies and more specifically to the field of cooling technologies within a device enclosure where cooling efficiency is related to fan speed and altitude. BACKGROUND OF THE INVENTION [0003] As altitude above sea level increases, atmospheric density decreases. This decrease in atmospheric density is responsible for a reduction in cooling capacity of a fan running at a given speed. Since there is less air at high...

AI Technical Summary

Benefits of technology

The patent describes a method for using DC fans to determine altitude based on their rotational speed. By measuring the speed of multiple fans at different altitudes, a converter is created to convert the speed into altitude. This can be done using a look up table or an arithmetic algorithm. The invention has applications in cooling systems and other fields where accurate altitude measurement is important.

Problems solved by technology

This fact presents a problem for designers looking to characterize system requirements, since a given configuration that works well at sea level, may be sufficiently degraded in cooling capacity at higher altitudes such that some electronic devices may no longer be operating within their thermal design margins.

However, this solution is not optimum for systems operating at sea level, since the same system could operate at a higher frequency at sea level due to the improved air-cooling present at sea level.

While it is certainly possible to require users to input altitude information upon first use of a system, this approach is prone to errors.

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