Communication device, cooling fan unit, and operation control method for the cooling fan unit
A communication device which has high cooling efficiency and can be reduced in size and weight. The communication device in which a plurality of electronic circuit boards are mounted to a back wiring board (BWB) includes a casing containing the electronic circuit boards as a unit, an intake fan unit for introducing air into the casing to cool the electronic circuit boards, and a discharge fan unit having a plurality of blower fans each arranged such that air intake and discharge directions thereof form an angle of nearly 90 degrees, the blower fans discharging the air introduced into the casing. Combined use of an axial fan and the blower fans permits air to be introduced into and discharged from the casing from rear and front sides, respectively, of the casing, whereby spaces that the fan units occupy in the communication device can be reduced.
1. A cooling fan unit for cooling a plurality of electronic circuit boards electrically connected by a BWB, comprising:
a fan unit casing containing a blower fan;
a control circuit board ranged parallel with the BWB of the cooling fan unit and facing the BWB, for controlling operation of the blower fan; and
a plug-in connector arranged in a predetermined position of the control circuit board such that the plug-in connector is connected to a connector on the BWB when the fan unit casing is mounted to a cooling position of the electronic circuit boards, wherein
the fan unit casing includes a floating plate slidably holding the control circuit board, the floating plate being slid when the fan unit casing is mounted, to permit the plug-in connector of the control circuit board to be positioned with respect to the connector of the BWB.
2. The cooling fan unit according to claim 1 , wherein the fan unit casing contains a plurality of blower fans arranged in a staggered fashion.
3. The cooling fan unit according to claim 1 , wherein the floating plate has guide holes formed in positions corresponding to respective guide pins protruding from the BWB, the control circuit board being brought to a predetermined position by means of the guide holes, to position the plug-in connector with respect to the connector of the BWB.
4. An operation control method for a cooling fan unit having a blower fan which is fitted in a casing containing an electronic circuit board for cooling interior of the casing, comprising the step of:
temporarily increasing starting torque of the blower fan only for a short period of time immediately after operation of the cooling fan unit is started, to cause rotation speed of the blower fan to reach a steady-state value in an early stage after start of the blower fan,
wherein the cooling fan unit comprises a discharge fan unit constituted by the blower fan and an intake fan unit far introducing air into the casing, and the method comprises the step of operating only the intake fan unit only for a short period of time immediately after the operation of the cooling fan unit is started. and starting the blower fan after a predetermined pressure difference is created between inside and outside of the casing.