Browse Prior Art Database

A Real Redundant Fan Module with Alternative Tachometer

IP.com Disclosure Number: IPCOM000182384D
Original Publication Date: 2009-Apr-29
Included in the Prior Art Database: 2009-Apr-29
Document File: 3 page(s) / 70K

Publishing Venue

IBM

Abstract

Today, so-called "redundant fan" is to combine two independent fans in to a single package. On logistic point of view, these two fans are still independent. System still needs signals to control and sense these two independent fans. However, these two fans are just inside the same housing. In this disclosure, a "real" redundant fan module is proposed. "The redundant behavior" will be controlled inside the redundant fan module.

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A Real Redundant Fan Module with Alternative Tachometer

We propose a "real" redundant fan module. The redundant behavior will be controlled inside the redundant fan module. On system point of view, system looks the new redundant fan module as a single fan. Originally, redundant fan requires 6 pin connections. But now, we want to keep 4-pin connection to system, instead, which provide fan-speed sensing, redundant fan feature. The new design could show more fan module status (ok, single fan failed, or both fans failed) than conventional redundant fan does.

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Tachometer Output Algorithm of the New Redundant Fan Module
Behavior of the Tachpin on the new redundant fan module

A controller on the module would send the Tachpin signal to system by this algorithm.

While (true){
if(fan1==ok and fan2==ok)

{tech=avg{fan1_speed, fan2_speed}; // output formula could pre-defined by user
// ex. tech=max{fan1_speed, fan2_speed}
// or it could show alternative fan-speed values by time division modulation (TDM)

else if(fan1==ok and fan2==fail)
{tech=1; // if one of two fans is failed, tech outputs high }

else if(fan1==fail and fan2==ok)
{tech=1; // if one of two fans is failed, tech outputs high }

else
{tech=0; // if two fans are both failed, tech outputs low continue; // back to while (true)
}

}

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