Electronic apparatus

• US 7,551,436 B2
• Filed: 02/02/2007
• Issued: 06/23/2009
• Est. Priority Date: 03/31/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi Communication Technologies, Ltd. (Hitachi, Ltd.)
• Inventors: Miyagawa, Susumu, Asai, Seiji, Kuwaki, Hiroshi, Hata, Koji, Kiyose, Takeshi, Funada, Takashi
• Primary Examiner(s): Gandhi; Jayprakash N
• Assistant Examiner(s): Thomas; Bradley H.
• Application Number:
  US11/701,521
• Publication Number:
  US 20070230123A1
• Time in Patent Office: 872 Days
• Field of Search: 361688-695, 361748-760, 361/724, 622/592, 312/223.2, 211/41.17, 454184-186, 324/502
• US Class Current: 361/695
• CPC Class Codes: H05K 7/20563 within sub-racks for removing heat from electronic boards
• CPC Class Codes: H05K 7/207 Thermal management, e.g. cabinet temperature control

Abstract

In an electronic apparatus in which plural substrates are arranged in a perpendicular direction between plural cooling fans in a lower part of a case and plural temperature sensors in an upper part of the case, any temperature variation by 2° C. in three seconds detected by any one of the temperature sensors is determined to be abnormal, and thermal energy is caused to be discharged from surfaces of substrates on two sides of a flame by raising air flow rates of fans. Expansion of the flame to other substrates is thereby prevented.

Claims

1. An electronic apparatus comprising a plurality of cooling fans arranged in a lower part of a case, a plurality of temperature sensors arranged in an upper part of said case, and a plurality of electronic substrates so arranged between said cooling fans and said temperature sensors as to secure air flow paths, with an ambience test of inserting an ignition source for a certain length of time into the case, characterized in that:

said electronic apparatus having a control unit that measures at predetermined intervals of time the temperature within the case with said temperature sensors, compares the temperature measured the latest time with the temperature measured at the preceding time for each of said temperature sensors and, if a temperature rising rate measured is greater than a predetermined value for one or more of said temperature sensors, and if the temperature measured at the latest time is higher than the temperature measured at the preceding time for each of said one or more temperature sensor(s), increases an air flow rate of said plurality of cooling fans,

wherein said control unit maintains the increased temperatures within the case, which are measured by the temperature sensors, at a temperature of less than the self-igniting point of the electronic substrates, even in the presence of said ignition source.

2. The electronic apparatus according to claim 1, wherein the air flow rate of said cooling fans is increased from a normal range of 0.5 m/s to 0.8 m/s to a range of 1.2 m/s to 1.7 m/s.

3. The electronic apparatus according to claim 1, wherein said control unit increases the air flow rate of said cooling fans and at the same time gives an instruction to cut off power supply to each of said electronic substrates.

4. The electronic apparatus according to claim 1, wherein said predetermined value is 0.625°

C./s.

5. The electronic apparatus according to claim 1, wherein said control unit, after keeping the air flow rate of said plurality of cooling fans increased for a few seconds, again measures the temperature within the ease with said plurality of temperature sensors, and determines whether or not to maintain the increase of the air flow rate of said cooling fans on the basis of the result of the measurement.

6. The electronic apparatus according to claim 1, wherein the air flow rate of said cooling fans is increased at least within 10 seconds after the ignition source is inserted into the case.

7. The electronic apparatus according to claim 1, wherein said control unit is installed in a position isolated from said air flow paths.

8. The electronic apparatus according to claim 1, wherein thermal energy of said ignition source is discharged out of the case by increasing the air flow rate of said plurality of cooling fans thereby to prevent the inside of the case from suffering a spread of burning.

9. The electronic apparatus according to claim 1, wherein said plurality of electronic substrates are made of epoxy and said self-igniting point is 540°

C.

10. The electronic apparatus according to claim 1, wherein said control unit maintains the increased temperatures within the case, which are measured by the temperature sensors, less than or equal to 350°

C., even in the presence of said ignition source.