Cooling Fan Identification via Coded Tachometer Signals
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Solution Overview
Problem
Incorrect cooling fan models are often installed in information handling systems, leading to inaccurate speed control, unnecessary noise, excessive power consumption, and potential system shutdown, due to the lack of reliable identification and communication methods between the fan and the system.
Innovation Solution
A system and method that uses coded power commands through the power wire to enter a command mode and serially coded tachometer readings to communicate fan identification and other information, allowing electronic confirmation of compatibility without additional communication wires, utilizing a system controller to manage fan operations and send escape sequences to initiate communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If part numbers are placed on cooling fans by stickers, then fan identification is provided, but the stickers may fall off, be stuck to incorrect fan types, or be ignored/misread at installation
Solution Approach 1:
The patent replaces the mechanical sticker-based identification system with an electronic communication system. The cooling fan contains an identification register that stores fan type information, which is electronically communicated to the system controller through the existing tachometer wire using coded tachometer readings. This electronic system eliminates the reliability issues of physical stickers while providing accurate, tamper-proof fan identification.
2Reliability
If an incorrect cooling fan model is installed, then the system may overheat and shut down or suffer catastrophic failure, but detecting the incorrect fan before installation is difficult
Solution Approach 1:
The patent implements preliminary verification by having the system controller read and verify fan identification information from the fan's identification register before allowing the fan to operate. The controller compares the identified fan type against the required fan type for that specific system slot, preventing incorrect fans from being installed or operated. This preliminary check avoids the need for post-installation detection and prevents system failures before they occur.
3Ease of operation
If cooling fan speed is controlled by varying power application, then speed control is achieved, but an incorrect fan model will result in inaccurate speed control, excessive noise, and power consumption
Solution Approach 1:
The patent enhances the existing feedback control system by adding fan model identification to the feedback loop. The system controller receives both tachometer readings (fan speed feedback) and fan identification information. This allows the controller to verify that the correct fan model is installed and providing accurate feedback signals, ensuring that speed control commands produce the intended results and preventing harmful effects from incorrect fan operation.
4Adaptability or versatility
If a four-wire configuration with PWM wire is used, then fan speed commands can be sent through PWM wire, but the system still lacks fan identification and compatibility confirmation
Solution Approach 1:
The patent makes the existing tachometer wire serve multiple functions: it continues to provide fan speed feedback while also carrying fan identification information. By encoding fan type information in the tachometer readings, the system extracts additional information from an existing wire without adding complexity or requiring additional wires, achieving multi-functionality of the communication channel.
Data Source
AI summary
An escape sequence coded in power commands from a system controller, such as a BMC, to a cooling fan controller directs the cooling fan to send identification information coded in tachometer readings to the system controller for use by an information handling system. Electronic confirmation of the cooling fan identification ensures compatibility of the information handling system and cooling fan at initial manufacture or subsequent repair. Communication of information over existing power and tachometer wires supports the electronic confirmation without adding additional communication lines. Further, once a communication link is established between an information handling system controller and a cooling fan, other functions are enabled, such as a reflash of the cooling fan controller firmware.