Ventilation system for modular electronic housing

Claim 2

A ventilation arrangement for a modular enclosure for electronic circuits, comprising in combination: a ventilation fan includng a motor for providing movement of cooing air in said modular enclosure, said motor being operable at at least two speeds including a lower speed and a higher speed wherein said higher speed induces greater air movement than said lower speed; a plurality of modular electronic circuit compartments for housing a corresponding plurality of electronic circuits, each of said modular compartments including an air path for said cooling air moved by said ventilation fan; a plurality of temperature sensing means, one situated in each of said modular compartments, for individually sensing the temperature in each of said compartments as an indication of the temperature of each of said electronic circuits; and speed control means, responsive to each of said temperature sensing means, for causing said motor to operate at said lower speed if the temperature in each of said modular compartments is below a predetermined threshold and for causing said motor to operate at said higher speed if the temperature in any one or more of said modular compartments exceeds said predetermined threshold; whereby, if any one or more of said electronic circuits within said modular compartments require additional ventilation, the speed of operation of said motor is increased to provide the required additional ventilation in all of said compartments.

Claim 3

The apparatus of claim 1, wherein said sensing means includes means for converting a temperature to a D. C. voltage.

Claim 4

The apparatus of claim 2, wherein said sensing means further includes comparing means for comparing said D. C. voltage to a reference voltage in order to determine whether or not the temperature has exceed said predetermined threshold.

Claim 5

The apparatus of claim 3, wherein said comparing means includes a plurality of open collector output comparitors, each of which have their outputs tied together to a common node.

Claim 6

The apparatus of claim 1, further comprising a source of a plurality of D. C. voltages and switching means for switching said plurality of D. C. voltages to said motor in order to establish said higher and said lower speeds.

Claim 7

A ventilation arrangement for a modular enclosure for electronic circuits, comprising in combination: a ventilation fan including a motor for providing movement of cooing air in said modular enclosure, said motor being operable at at least two speeds including a lower speed and a higher speed wherein said higher speed induces greater air movement than said lower speed; a plurality of modular electronic circuit compartments for housing a corresponding plurality of electronic circuits, each of said modular compartments including an air path for said cooling air moved by said ventilation fan; a plurality of temperature sensing means, one situated in each of said modular compartments, for individually sensing the temperature in each of said compartments as an indication of the temperature of each of said electronic circuits, said sensing means including means for converting a temperature to a D. C. voltage; comparing means for comparing said D. C. voltage to a reference voltage in order to determine whether or not the temperature has exceed said predetermined threshold, said comparing means including a plurality of open collector output comparitors, each of which have their outputs tied together to a common node; a source of a plurality of D. C. voltages; speed control means, responsive to said comparing means, for causing said motor to operate at said lower speed if the temperature in each of said modular compartments is below a predetermined threshold, and for causing said motor to operate at said higher speed if the temperature in any one or more of said electronic circuits within said modular compartments exceeds said predetermined threshold so that increased air movement is provided, said speed control means including switching means for switching said plurality of D. C. voltages to said motor in order to cause said motor to operate at said higher and said lower speeds.

Claim 8

A ventilation arrangement for a modular enclosure for electronic circuits, comprising in combination: a ventilation fan including a motor for providing movement of cooing air in said modular enclosure, said motor being operable at at least two speeds including a lower speed and a higher speed wherein said higher speed induces greater air movement than said lower speed; a plurality of modular electronic circuit compartments for housing a corresponding plurality of electronic circuits, each of said modular compartments including an air path for said cooling air moved by said ventilation fan; a plurality of temperature sensing means, one situated in each of said modular compartments, for individually sensing the temperature in each of said compartments as an indication of the temperature of each of said electronic circuits, said sensing means including means for converting a temperature to a D. C. voltage; comparing means for comparing said D. C. voltage to a reference voltage in order to determine whether or not the temperature has exceed said predetermined threshold, said comparing means including a plurality of open collector output comparitors, each of which have their outputs tied together to a common node; a source of a plurality of D. C. voltages; speed control means, responsive to said comparing means, for causing said motor to operate at said lower speed if the temperature in each of said modular compartments is below a predetermined threshold, and for causing said motor to operate at said higher speed if the temperature in any one or more of said electronic circuits within said modular compartments exceeds said predetermined threshold so that increased air movement is provided, said speed control means including switching means for switching said plurality of D. C. voltages to said motor in order to cause said motor to operate at said higher and said lower speeds.

Claim 11

The method of claim 7, wherein said sensing step is carried out by converting said sensed temperature to a signal level and said comparing step is carried out by comparing said signal level with a reference signal level.

Claim 12

The method of claim 7, wherein said increasing step is carried out by increasing a voltage to a motor driving said ventilation fan.

Claim 13

The method of claim 7, wherein said comparing step includes driving a single signal line by a plurality of open collector output comparitors.