BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to a method and an apparatus for controlling
an electric dust collector, and more particularly to a control method and a
control apparatus capable of stopping the operation of an electric dust
collector when an abnormality occurs thereto.
Related Art
In a conventional control apparatus for an electric dust collector,
voltage between one pair of opposing electrodes of the electric dust
collector is detected and an judgment is made as to whether or not the
voltage thus detected is within a predetermined range. If the voltage is not
within the range, the electric dust collector is stopped in operation by
judging that an abnormality has occurred, and a failure is indicated (see
Japanese Utility Model Examined Publication (KOKOKU) No.
45376/95).
The voltage between the opposing electrodes of the electric dust
collector is sometimes departed from the predetermined range for only a
short time. For example, when water drops are deposited on the opposing
electrodes, the voltage between the opposing electrodes is lowered and
departed from the predetermined range. However, this lowering of
voltage between the opposing electrodes occurs for only a short time
during which the water drops still remain deposited. The voltage will
return to its original level when the water drops are evaporated. Even if a
voltage abnormality should occur for only a short time as discussed, the
electric dust collector would be, in most cases, in a normal condition.
However, the conventional control apparatus for an electric dust
collector has such a problem that when the voltage between the opposing
electrodes departs from the predetermined range even instantaneously, it
stops the operation of the electric dust collector by judging the electric dust
collector to be abnormal notwithstanding that the electric dust collector is
in a normal condition.
SUMMARY OF THE INVENTION
The present invention aims at providing a control method and a
control apparatus capable of excluding a short time abnormality of an
electric dust collector from a real abnormality.
The feature of a control method ofthe present invention resides in a
method for controlling an electric dust collector comprising a first step of
judging whether or not the abnormality of the electric dust collector
intermittently occurs a predetermined plurality of times or more during a
predetermined second measuring time; and a second step of performing an
abnormal time procedure with respect to the electric dust collector when
the abnormality continues during the first measuring time.
Preferably, the control method further comprises a third step of
judging whether or not the abnormality of the electric dust collector
intermittently occurs a predetermined plurality of times or more during a
predetermined second measuring time; and a fourth step of temporarily
stopping the supply of a high voltage electric current to the one pair of
opposing electrodes and resuming the supply of a high voltage electric
current to the one pair of opposing electrodes after the passage of a
predetermined first standby time when the judgment in the third step is
affirmative.
The third step may be carried out after the first step is carried out,
or the first step may be carried out after the third step is carried out.
Preferably, the control method further comprises a fifth step of
judging whether or not a phenomenon of the abnormality of the electric
dust collector being intermittently occurred a predetermined plurality of
times or more during the second measuring time, occurs a predetermined
plurality of times; and a sixth step of performing an abnormal time
procedure with respect to the electric dust collector when the judgment in
the fifth step is affirmative.
Preferably, the control method further comprises a seventh step of
judging whether or not an abnormality of the electric dust collector
continuing during the first measuring time occurs for the first time; and an
eighth step of temporarily stopping the supply of a high voltage electric
current to the one pair of opposing electrodes and resuming the supply of a
high voltage electric current to the one pair of opposing electrodes after the
passage of a predetermined second standby time when the judgment in the
seven step is affirmative.
The feature of a control apparatus of the present invention resides
in an apparatus for controlling an electric dust collector comprising
abnormality detecting means for detecting an abnormality of the electric
dust detector having one pair of opposing electrodes supplied with a high
voltage electric current; continuous abnormality judging means for
judging whether or not a detection of the abnormality of the electric dust
collector by the abnormality detecting means continues during a
predetermined first measuring time; and abnormal time procedure means
for performing an abnormal time procedure with respect to the electric
dust collector when the abnormality detecting means makes an affirmative
judgment.
Preferably, the control apparatus further comprises intermittent
abnormality judging means for judging whether or not the abnormality
detecting means intermittently detects the abnormality of the electric dust
collector a predetermined plurality of times or more during a
predetermined second measuring time; and intermittent abnormal time
procedure means for temporarily stopping the supply of a high voltage
electric current to the one pair of opposing electrodes when the
intermittent abnormality judging means makes an affirmative judgment
and resuming the supply of a high voltage electric current to the one pair of
opposing electrodes after the passage of a predetermined first standby
time.
The intermittent abnormality judging means may judge whether or
not the abnormality of the electric dust collector continues during the
predetermined second measuring time after the continuous abnormality
judging means judges whether or not the abnormality of the electric dust
collector intermittently occurs a predetermined plurality of times or more
during the predetermined first measuring time, or it may judge whether or
not the abnormality of the electric dust collector continues during the
predetermined first measuring time after the intermittent abnormality
judging means judges whether or not the abnormality of the electric dust
collector intermittently occurs a predetermined plurality of times or more
during the predetermined second measuring time.
Preferably, the control apparatus may further comprises number of
times judging means for judging whether or not the intermittent
abnormality judging means makes an affirmative judgment a plurality of
times or more; and the abnormal time procedure means carries out the
abnormal time procedure with respect to the electric dust connector when
the number of times judging means makes an affirmative judgment.
Preferably, the control apparatus further comprises first time
abnormality judging means for judging whether or not the affirmative
judgment made by the continuous abnormality judging means is a first
judgment; and first time abnormal time procedure means for temporarily
stopping the supply of a high voltage electric current to the one pair of
opposing electrodes when the first time abnormality makes an affirmative
judgment and resuming the supply of a high voltage electric current to the
one pair of opposing electrodes after the passage of a predetermined
second standby time.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram showing a general construction of one
embodiment of the present invention,
Fig. 2 is an illustration of a flow chart for controlling an electric
dust collector by a control apparatus according to the embodiment of Fig.
1;
Fig. 3 is an illustration showing a flow chart of another
embodiment of the present invention; and
Fig. 4 is an illustration showing a flow chart of still another
embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Embodiments of the present invention will be described hereinafter
with reference to Figs. 1 through 4.
Referring first to Figs. 1 and 2, one embodiment of the present
invention will be described. An electric dust collector 1 to be controlled
by a control apparatus 2 comprises, as in the conventional equivalent
device, a charge unit 11 having one pair of opposing electrodes (not
shown) consisting of a discharge electrode and a counterpart opposing
electrode, and a high voltage power supply circuit 12 for supplying a high
voltage to between the opposing electrodes. The charge unit 11 is
provided with a voltage detecting means 13 for detecting a voltage
between the one pair of opposing electrodes.
The control apparatus 2 judges whether or not an abnormality
occurs to the dust collector 1, based on a detection voltage detected by the
voltage detecting means 13. When the dust collector 1 is in an abnormal
condition, the control apparatus 2 stops the supply of high voltage current
to the opposing electrodes of the charge unit 11 by the high voltage power
supply circuit 12 and resumes the operation later. When the abnormality
of the dust collector 1 continues for a predetermined time, the control
apparatus 2 judges the abnormality as a real abnormality and causes the
buzzer 3 to buzz and an alarm lamp to light up to give a warning to the user
of the electric dust collector 1.
The control operation made by the control apparatus 2 will be
described in detail. The control operation is carried out in accordance with
a program based on the flow chart of Fig. 1. When a predetermined time
has passed after the actuation of the electric dust collector 1, the program
based on the flow chart starts. Those memories related to this program are
all initialized immediately after start of the program.
After the start of the program, it is judged in step S1 whether or not
an abnormality occurs to the electric dust collector 1. This abnormality
judgment is carried out by checking whether or not the voltage between
the one pair of opposing electrodes is within a predetermined range in this
embodiment. The abnormality judgment may be carried out based on an
electric current flowing between the one pair of opposing electrodes or on
an electric power as a product of the voltage and the electric current.
When no abnormality occurs to the electric dust collector 1, the procedure
in step S1 is repeated. That is, it is normally monitored whether or not an
abnormality occurs to the voltage between the opposing electrodes.
When an abnormality occurs to the electric dust collector 1, it is
judged in step S2 whether or not the abnormality is an intermittent
abnormality which intermittently occurs a predetermined plurality of
times or more within a predetermined second measuring time. This
judgment is carried out to see whether or not the abnormality is
temporarily occurred due to deposition of water drops, dusts, or the like on
the one pair of opposing electrodes. The length of the second measuring
time and the criteria of the number of occurrence of abnormality for
judging a certain abnormality as an intermittent abnormality are
appropriately established through testing.
If the abnormality occurs to the electric dust collector 1 is not an
intermittent abnormality, it is judged in step S3 whether or not the
abnormality is a continuous abnormality which continuously occurs
within a predetermined first measuring time. This judgement is carried out
to see whether or not the abnormality is continuous and requires repair, as
caused by wire cutting, short circuit, or the like. The length of the first
measuring time is established through testing such that a short time
abnormality caused by water drops, or the like can be excluded. It is
preferred that the length of the first measuring time is equal to the length of
the second measuring time. By doing so, it can simultaneously be judged
after the passage of the first measuring time whether the abnormality is an
intermittent abnormality or a continuous abnormality.
In case the abnormality of the electric dust collector 1 is not a
continuous abnormality, it is merely of an instantaneous nature and not a
real abnormality. Thus, the program returns to step S1. Accordingly, the
control apparatus 2 carries out no procedure with respect to the electric
dust collector 1. The electric dust connector 1 is kept operated in an
ordinary manner.
In case the abnormality of the electric dust collector 1 is a
continuous abnormality, it is of a continuous nature and a real
abnormality. Thus, an abnormal time procedure is carried out by the
control apparatus 2 (step S4). This abnormal procedure is the same as in
the conventional control apparatus. In this embodiment, the abnormal
procedure includes stop of the supply of high voltage electric current to the
one pair of opposing electrodes of the charge unit 11, actuation of the
buzzer 3, and lighting of the alarm lamp 4. Thereafter, the program is
ended, and the control operation carried out by the control apparatus 2
with respect to the electric dust collector 1 is finished.
If it is judged in step S2 that the abnormality occurs to the electric
dust collector 1 is an intermittent abnormality, an intermittent abnormal
time procedure is carried out in steps S5 through S7. That is, in step S5,
the supply of voltage electric current to the one pair of opposing electrodes
is stopped, and the timer is actuated. Then, in step S6, it is judged whether
or not a predetermined first standby time is elapsed after the actuation of
the timer. The length of the first standby time is long enough to remove an
instantaneous abnormality caused by water drops, or the like deposited on
the one pair of opposing electrodes and established through testing. With
the passage of the first standby time, the supply of voltage electric current
is resumed in step S7. Then, the program returns to step S1.
In the above control apparatus 2, since it is judged whether or not
an abnormality is a continuous abnormality only after the abnormality of
the electric dust collector 1 is detected and an abnormal time procedure is
carried out only when the abnormality is a continuous abnormality, it
never happens that an abnormality, which is of the nature to be removed
with the passage of time as in the case where water drops are deposited on
the one pair of opposing electrodes, is judged as a real abnormality.
Accordingly, it can be prevented that the electric dust collector 1 is
stopped in operation notwithstanding that the electric dust collector 1 is in
a normal condition. This makes it possible to reduce the frequency for
collecting the electric dust collector 1 which is not required to be repaired.
In this embodiment, since the supply of high voltage electric
current to the one pair of opposing electrodes is temporarily stopped when
an intermittent abnormality occurs and the supply of high voltage electric
current is resumed after the passage of the predetermined first standby
time, the abnormality is removed within the first standby time. Thus, the
electric dust collector 1 can be prevented from being operated in a state
where an abnormality occurs intermittently and it can be operated only in a
normal condition.
Other embodiments of the present invention will now be described
with reference to Figs. 3 and 4.
In the embodiment shown in Fig. 3, the intermittent abnormality
judgment and the continuous abnormality judgment are carried out
reversely in order from that of Fig. 1. That is, in this embodiment, it is
judged first in step S2 whether or not the abnormality is a continuous
abnormality. If it is judged in step S2 that the abnormality is a continuous
abnormality, an abnormal time procedure is carried out in step S4. In
contrast, if it is judged in step S2 that the abnormality is not a continuous
abnormality, it is then judged in step S3 whether or not the abnormality is
an intermittent abnormality. If the abnormality is an intermittent
abnormality, an intermittent abnormal time procedure is carried out in
steps S5 through S7. In contrast, if the abnormality is not an intermittent
abnormality, the program returns to step S1. The judgment as to whether
or not the abnormality is a continuous abnormality, the judgment as to
whether or not the abnormality is an intermittent abnormality, and the
procedures for those occasions, are carried out in the same manner as in
the embodiment of Fig. 1.
In the embodiment shown in Fig. 4, step S3' for judging whether
the judgment for a continuous abnormality in step S3 is the first judgment
or the second judgment afterward is inserted between step S3 for judging
whether or not the abnormality is a continuous abnormality and step S4 for
carrying out the abnormal time procedure.
If it is judged in step S3' that the judgment for continuous
abnormality is the first judgment, the first abnormal time procedure is
carried out. In this embodiment, the same procedure as the intermittent
abnormal time procedure is carried out as the first abnormal time
procedure based on steps S5 through S7. That is, in step S5, the
procedures for stopping the supply of voltage to the one pair of opposing
electrodes and for actuating the timer are carried out. It is judged in step
S6 whether or not the predetermined first standby time (=second standby
time) is passed. After the passage of the second standby time, the supply
of voltage to the one pair of opposing electrodes is resumed in step S7.
Different procedures from the first abnormal time procedure in steps S5
through S7 may be carried out in different steps from steps S5 through S7
inasmuch as the procedure for temporarily stopping the supply of high
voltage electric current to the one pair of opposing electrodes and the
procedure for resuming the supply of high voltage electric current after the
passage of the second standby time are carried out. The length of the
second standby time may be different from the length of the first standby
time.
If it is judged in step S3' that the judgment for a continuous
abnormality is the second time judgment, the program proceeds to step S4
where the abnormal time procedure is carried out.
The judgment as to whether the judgment for a continuous
abnormality is the first time judgment can be carried out by checking
whether the content in a predetermined memory is 0 (first time) or 1
(second time). That is, since the content in a predetermined memory is
cleared to 0 when the procedure in step S3' is executed first, due to
initialization at the starting time of the program, the judgment for a
continuous abnormality is judged to be the first time judgment. After the
first execution of step S3', 1 is written in the predetermined memory
mentioned above. As a consequence, it is judged that the judgment for a
continuous abnormality is performed at least once when the step S3' is
executed second time afterward.
The order for executing steps S2 and S3 may be reversed also in
this embodiment as in the embodiment of Fig. 2.
In this embodiment, since the second standby time is allowed to
pass in the state where the supply of high voltage electric current is
stopped and without immediately judging that the abnormality of the
electric dust collector 1 is a real abnormality when the continuous
abnormality is the first time, it can be prevented that the electric dust
collector 1 is judged to be in an abnormal condition even when a
comparatively long time is required for the voltage between the one pair of
opposing electrodes to return to its normal level as in the case where
comparatively large water drops are deposited on the one pair of opposing
electrodes.
The present invention is not limited to the above embodiments but
many modifications can be made in accordance with necessity. For
example, in the above embodiments, the program returns immediately to
step S1 after the intermittent abnormal time procedures in steps S5 through
S7 are carried out. It is an interesting alternative that a judgment is made
as to whether or not the intermittent abnormal time procedure is carried out
a predetermined plurality of times after step S7, and if the judgment is
affirmative, the abnormal time procedure is carried out but if the judgment
is negative (namely, only when the number of times for carrying out the
intermittent abnormal time procedure does not reach a predetermined
number), the program then returns to step S1.