Pumps – Condition responsive control of pump drive motor – Plural pumps having separate drive motors – supply sources,...
Reexamination Certificate
2002-03-28
2004-11-09
Yu, Justine (Department: 3746)
Pumps
Condition responsive control of pump drive motor
Plural pumps having separate drive motors, supply sources,...
C417S018000, C417S032000, C417S042000, C417S426000, C361S688000, C361S695000, C318S111000
Reexamination Certificate
active
06814546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multifan-equipped apparatus and a method of controlling operation of a fan-unit assembly of the apparatus. More particularly the invention concerns an improvement of the apparatus and method which are suitable for cooling a plurality of electronic devices by a plurality of fan units mounted in a plurality of layers one over another in a chassis of the apparatus.
2. Description of the Related Art
Nowadays electronics manufacturers have made attempts to develop less-powered electronic devices, which work at a low voltage, as demands for saving energy in electronics to assist environmental protection are on the rise. But, it is now harder time to cope with the heat problem of modern electronics (each hereinafter also called the apparatus) because, in the individual apparatus, a multiplicity of electronic devices are mounted in a chassis with high-density, thanks to recent advance of mounting technology. To this end, it is now a common practice to use a cooling fan (hereinafter also called the fan) as an easy and less-expensive measure. Accordingly demand for fan-equipped electronics will increase.
However, it is particularly essential to minimize consumption of power due to installation of the fan as many of electronics manufacturers are reluctant to increase the price of the apparatus only for use of the fan. In the meantime, it is important to secure an adequate degree of cooling performance of the fan.
For efficient operation of the fan, it is preferable to control the fan in rpm (revolutions per minute) in accordance with a current apparatus-environment temperature and a current operating condition of the apparatus. Many of electronic manufacturers incorporate a temperature sensor with the fan (the resulting fan is called the fan unit) so that the fan is autonomically adjusted in rpm, depending on a current temperature detected by the temperature sensor.
It is a common knowledge that the cooling performance (rpm) of every cooling fan unit will become worse as the fan ages. Consequently, for a multifan-equipped apparatus in which a plurality of fan units are mounted within the chassis, some of electronics manufacturers made, upon occurrence of an abnormality in cooling performance (undue lowering of cooling performance) with a certain fan unit, a back-up control on at least one fan unit about the abnormal fan unit, which are normally operating under autonomic control, to increase the current rpm in an attempt to keep necessary performance of the whole cooling system.
Thus according to the last-mentioned conventional technology, it was intended to realize a balance between economical operation of the fan-unit assembly and a cooling redundancy to cope with possible lowering of cooping performance, by adopting the autonomic/back-up control system. This prior art is exemplified by Japanese Patent Laid-Open Publication No. 2000-346512.
FIG. 13
of the accompanying drawings shows a conventional multifan-equipped apparatus in which a plurality of electronic units (electronics) to be cooled are mounted in a chassis
40
, for example, in the form of a multiplayer rack. In
FIG. 13
, three electronic units
10
,
20
,
30
are supported one on each of three layers in the chassis
40
. And three sets of fan units, each set including four fan units
100
-
1
through
100
-
4
,
200
-
1
through
200
-
4
,
300
-
1
through
300
-
4
, are mounted one set under each of the electronic units
10
,
20
,
30
.
In this multi-layer fashion of mounting, because the electronic unit
10
(
20
) is sandwiched between two set of fan units, cooling air for the electronic unit
20
(
30
) disposed leeward of the electronic unit
10
(
20
) would rise somehow due to the heat radiated by the last-named windward electronic unit
10
(
20
).
For this reason, during operation of the fan units
100
-
i
,
200
-
i
,
300
-
i
(i=a natural number selected from 1 through 4) under the above-mentioned autonomic control, the fan operation (rpm) would tend to be staggered between the individual fan units
100
-
i
,
200
-
i
,
300
-
i
would fluctuate due to the difference in temperature between the upper and lower layers within the chassis
40
and the difference in amount of radiated heat of the leeward and windward electronic units
10
,
20
,
30
so that cooling air flows within the chassis
40
would be out of balance, thus impairing the cooling efficiency and increasing noises.
In other words, the temperature detected at and about the leeward fan unit
200
-
i
(
300
-
i
) than that detected at and about the windward fan unit
100
-
i
(
200
-
i
) so that the rpm value fluctuates between the upper and lower fan units as each fan unit is operating under autonomic control in accordance with the respective temperature detected, which would result in an inefficient cooling operation.
To avoid this staggering of rpm between the lower set of fan units
100
-
i
(
200
-
i
) and the upper set of fan units
200
-
i
(
300
-
i
), as shown in
FIG. 14
, all the fan units are individually monitored by a common cooling monitor
50
. And the cooling monitor
50
serves also to adjust the rpm of an individual upper fan unit
200
-
i
(
300
-
i
) to an individual lower fan unit
100
-
i
(
200
-
i
), which is disposed windward of the last-named upper fan unit, so as to keep cooling air flows within the chassis
40
in balance (back-up control).
In this monitoring, the cooling monitor
50
non-interruptedly monitors the current operation statuses (occurrence of an error, mounting/dismounting, current operation mode (autonomic control or back-up control), etc.) of the fan units individually; the individual fan unit
100
-
i
,
200
-
i
,
300
-
i
normally notifies the cooling monitor
50
of the current operation status of itself by a warning (ALM) signal, a dismounting (RMV) signal, a mode (MODE) signal, etc. Now assuming that an abnormality has occurred with a certain fan unit
100
-
i
,
200
-
i
,
300
-
i
or a certain fan unit
100
-
i
,
200
-
i
,
300
-
i
have been dismounted, the cooling monitor
50
makes a back-up control on a nearby fan unit
100
-
j
,
200
-
j
,
300
-
j
(j=a natural number selected from 1 through 4, j≠i) by, for example, increasing the rpm of the last-named nearby fan unit to thereby keep the cooling performance of the whole fan-unit assembly.
In
FIG. 14
, arrow-headed lines are depicted with respect to the fan units
100
-
2
,
200
-
2
(
200
-
2
,
200
-
3
); the arrow-headed lines each indicates the direction in which a warning message is given from an individual fan unit
100
-
2
or
200
-
2
(
200
-
2
or
200
-
3
) to the cooling monitor
50
or the direction in which a back-up-control signal is given from the cooling monitor
50
to a nearby fan unit
200
-
1
or
100
-
2
(
200
-
3
or
200
-
2
). Also the solid arrow-headed line indicates that the warning message is given non-interruptedly, and the dotted arrow-headed line indicates that the back-up-control signal is given only upon occurrence of an error. (Similar lines with respect to the other fan units
100
-
1
(
200
-
1
),
200
-
1
(
300
-
1
),
100
-
3
(
200
-
3
),
200
-
3
(
300
-
3
),
100
-
4
(
200
-
4
),
200
-
4
(
300
-
4
) are omitted here for clarity of illustration.
For economical operation of the fan-unit assembly, the operation of the fan-unit assembly should be controlled preferably in accordance with the current apparatus-environment temperature as demand arises, and ideally linearly with the rise of the temperature. Practically, however, particularly under a sophisticated control environment in which cooling-air flows within the chassis
40
have to be kept in balance (back-up control), the conventional apparatus have no choice to adopt a non-linear and hence stepwise control, in which the rpm of the individual fan unit has to be changed stepwise to a selected one of a plurality of fixed values.
In this stepwise control, as shown in FIG.
15
(B), a threshold value for the rpm of the individual fan should
Fujitsu Ltd.
Katten Muchin Zavis & Rosenman
Sayoc Emmanuel
Yu Justine
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