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Claims  |
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What is claimed is:
1. An electromagnetic contactor for opening or closing a contact by
controlling energization of an electromagnet to move a movable core from a
first position to a second position with respect to a fixed core, the
electromagnetic contactor comprising:
attraction force control means for controlling an integral value of a
current flowing through the electromagnet for a predetermined time so that
velocity in the second position of the movable core becomes zero;
wherein said attraction force control means contains switches and timers
operable to pass current through said electromagnet only during said
predetermined time;
wherein said predetermined time is less than a time needed for said movable
core to move from said first position to said second position; and
wherein said attraction force control means prevents current from passing
through said electromagnet after said predetermined time until said
movable core reaches said second position.
2. An electromagnetic contactor for passing a current through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow by electromagnetic force and opening or closing a
contact, the electromagnetic contactor comprising:
attraction force control means for passing a first current through the
electromagnet for a predetermined time so that velocity in the second
position of the movable core becomes zero and passing a second current
through the electromagnet when said movable core reaches the second
position,
wherein said predetermined time is less than a time needed for said movable
core to move from said first position to said second position; and
wherein said attraction force control means passes the second current to
attract and hold said electromagnet after said predetermined time when
said movable core reaches said second position.
3. An electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a second
position in which a gap to a fixed core is narrow to a first position in
which the gap is wide and opening or closing a contact, the
electromagnetic contactor comprising:
attraction force control means for breaking the current flowing through the
electromagnet and then passing a deceleration current through the
electromagnet for a second predetermined time after a first predetermined
time so that velocity in the first position of the movable core becomes
zero; and
wherein said first predetermined time is less than a time needed for said
movable core to move from said second position to said first position; and
wherein said attraction force control means passes the current through said
electromagnet for the second predetermined time after said first
predetermined time until said movable core is substantially in said first
position.
4. An electromagnetic contactor for passing a current through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow by electromagnetic force and opening or closing a
contact, the electromagnetic contactor comprising:
current control means for controlling the current flowing through the
electromagnet; and
command means for passing a first current through the electromagnet for a
predetermined time by the current control means so that velocity in the
second position of the movable core becomes zero, and then passing a
second current through the electromagnet by the current control means when
the movable core reaches the second position; and
wherein said predetermined time is less than a time needed for said movable
core to move from said first position to said second position; and
wherein said current control means prevents current from passing through
said electromagnet after said predetermined time until said movable core
is substantially in said second position.
5. An electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a second
position in which a gap to a fixed core is narrow to a first position in
which the gap is wide and opening or closing a contact, the
electromagnetic contactor comprising:
current control means for controlling the current flowing through the
electromagnet; and
command means for breaking the current flowing through the electromagnet by
the current control means, then passing a deceleration current through the
electromagnet for a predetermined time by the current control means after
a predetermined lapse so that velocity in the first position of the
movable core becomes zero, and then breaking the deceleration current by
the current control means at the time when the movable core moves to
substantially the first position; and
wherein said predetermined time is less than a time needed for said movable
core to move from said second position to said first position.
6. The electromagnetic contactor as defined in claim 2, wherein said second
current is greater than a holding current value necessary to hold the
movable core in the second position during an initial predetermined time,
and
wherein said second current is equal to the holding current value after the
predetermined time.
7. An electromagnetic contactor for passing a current through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow by electromagnetic force and opening or closing a
contact, the electromagnetic contactor comprising:
current control means for controlling the current flowing through the
electromagnet; and
command means for passing a first current through the electromagnet for a
first predetermined time by the current control means so that velocity of
the movable core becomes zero slightly in front of the second position,
then passing a second current having a value lower than the first current
through the electromagnet for a second predetermined time by the current
control means when the movable core moves slightly in front of the second
position, and then passing a third current through the electromagnet by
the current control means at a time when the movable core reaches the
second position;
wherein said command means prevents current flow through the electromagnet
after said first predetermined time and before said second current passes.
8. An electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a second
position in which a gap to a fixed core is narrow to a first position in
which the gap is wide and opening or closing a contact, the
electromagnetic
contactor comprising
current control means for controlling the current flowing through the
electromagnet; and
command means for breaking the current flowing through the electromagnet by
the current control means, then passing a first deceleration current
through the electromagnet for a first predetermined time by the current
control means after a first lapse so that velocity of the movable core
becomes zero slightly in front of the first position, passing a second
deceleration current for a second predetermined time by the current
control means at a time when the movable core moves to slightly in front
of the first position, and then breaking the second deceleration current
by the current control means at a time when the movable core reaches the
first position; and
wherein said command means prevents current flow through the electromagnet
after the current control means breaks the current flowing through the
electromagnet and before said first deceleration current passes.
9. The electromagnetic contactor as claimed in any of claims 4-8, wherein a
command of the command means has a predetermined slope in a rise or a fall
of a current.
10. An electromagnetic contactor for passing a current through an
electromagnet from an AC power source and moving a movable core from a
first position in which a gap to a fixed core is wide to a second position
in which the gap is narrow by electromagnetic force and opening or closing
a contact, the electromagnetic contactor comprising:
phase control means for shifting the AC power source from OFF to ON at a
predetermined voltage phase based on a command from command means; and
command means for turning on the phase control means with a predetermined
voltage phase to apply a voltage to the electromagnet for a predetermined
time so that velocity of the movable core becomes zero at the second
position, and then turning off the phase control means after said
predetermined time;
wherein said predetermined time is less than a time needed for said movable
core to move from said first position to said second position.
11. An electromagnetic contactor for breaking a current through an
electromagnet from an AC power source and moving a movable core from a
second position in which a gap to a fixed core is narrow to a first
position in which the gap is wide and opening or closing a contact, the
electromagnetic contactor comprising:
phase control means for turning on or off the AC voltage applied to the
electromagnet;
command means for turning off the phase control means with a predetermined
voltage phase, then turning on the phase control means when the movable
core is slightly before the first position, then applying a voltage for a
predetermined time to the electromagnet so that acceleration of the
movable core becomes zero, and then turning off the phase control means;
and
wherein said predetermined time is less than a time needed for said movable
core to move from said second position to said first position.
12. An electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow and opening or closing a contact,
wherein the electromagnet comprises a first electromagnet for exciting the
fixed core and a second electromagnet for exciting the movable core,
the electromagnetic contactor comprising:
current control means for controlling the current flowing through the first
and second electromagnets;
switching means for switching electromagnetic force occurring in the
movable core and the fixed core to attraction or repulsion by switching a
direction of the current flowing through the first or second
electromagnet; and
command means for passing a first attraction current through the first and
second electromagnets for a first predetermined time, then passing a first
repulsion current through the first and second electromagnets for a second
predetermined time when the movable core approaches the second position,
and then passing a second attraction current through the first and second
electromagnets when the movable core moves to the second position.
13. An electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a second
position in which a gap to a fixed core is narrow to a first position in
which the gap is wide and opening or closing a contact,
wherein the electromagnet comprises a first electromagnet for exciting the
fixed core and a second electromagnet for exciting the movable core,
the electromagnetic contactor comprising:
switching means for switching electromagnetic force occurring in the
movable core and the fixed core to attraction or repulsion by switching a
direction of the current flowing through the first or second
electromagnet; and
command means for passing a first repulsion current through the first and
second electromagnets for a first predetermined time, then passing a first
attraction current through the first and second electromagnets for a
second predetermined time, and then breaking the first attraction current
when the movable core moves to the first position.
14. The electromagnetic contactor as defined in claim 4, wherein said
second current is greater than a holding current value necessary to hold
the movable core in the second position for an initial predetermined time,
and wherein said second current is equal to the holding current value
after the predetermined time. |
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Claims |
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Description |
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TECHNICAL FIELD
This invention relates to an electromagnetic contactor, and suppresses a
shock by a collision between a movable core and a fixed core occurring in
the case of throwing and releasing the movable core by electromagnetic
force.
BACKGROUND ART
An electromagnetic contactor will be described by FIG. 19. FIG. 19 is a
sectional view showing a configuration of the electromagnetic contactor.
In FIG. 19, an electromagnetic contactor 100 comprises a fixed part and a
movable part, and in the fixed part, a base 10 is coupled to a mount 23 by
screws through a trip spring 30 compressed and mounted between a crossbar
2 and the mount 23. A primary fixed contact 25 having a contact 12 and an
auxiliary fixed contact 26 are fixed in the base 10, and a fixed core 20
is held within the mount 23 through a rubber plate 22 for shock
absorption, and an arc box 11 is provided on the base 10. An electromagnet
forms a coil 21 by winding electric wires on a bobbin 24 and is positioned
around a leg part of the fixed core 20.
In the movable part, a movable core 1 is joined to the crossbar 2 held
within the base 10 by a pin 3, and a primary movable contact 4 is fitted
in an upper window of the crossbar 2 through a press spring 5 and a
contact spring 6, and a contact 7 opposite to the primary fixed contact 25
is provided in the primary movable contact 4. An auxiliary movable contact
8 opposite to the auxiliary fixed contact 26 is fitted in a center window
of the crossbar 2 by an auxiliary contact spring 9.
The electromagnetic contactor 100 moves the movable core 1 from a first
position to a second position with respect to the fixed core 20 by turning
on or off excitation of the electromagnet, and in a state in which the
electromagnet is not excited, a position of the movable core 1 in a state
in which a wide gap between suction surfaces of the movable core 1 and the
fixed core 20 is ensured is called a first position (it may be called a
second position), and in a state in which the electromagnet is excited, a
position of the movable core 1 in a state in which the movable core 1
moves with respect to the fixed core 2 to become a narrow gap (including a
contact state of the gap with zero) between the suction surfaces is called
a second position (it may be called a first position). The throwing of the
electromagnetic contactor 100 means that the movable core 1 moves from the
first position to the second position, and the opening of the
electromagnetic contactor 100 means that the movable core 1 moves from the
second position to the first position. Then, in the first position of the
movable core 1, the top of the inverted T-shaped crossbar 2 is contacted
and pressed to the base 10 by the trip spring 30 and so on.
Next, an operation of the electromagnetic contactor 100 configured as
mentioned above will be described by FIG. 19. When a voltage is thrown to
the coil 21 and a current flows, the fixed core 20 is magnetized and
electromagnetic attraction force occurs in a gap g between the fixed core
20 and the movable core 1, and the movable core 1 is attracted to the
fixed core 20 against the trip spring 30 and the contact springs 6, 9 by
the attraction force and moves from the first position to the second
position and also, the contact 7 of the movable contact 4 contacts and
presses to the contact 12 of the fixed contact 25.
On the other hand, when the current of the coil 21 is broken, the fixed
core 20 is demagnetized, so that the movable core 1 is released from
suction and moves from the second position to the first position and also,
the contact 7 and the contact 12 are opened.
However, in the configuration of the above-mentioned electromagnetic
contactor 100, by the throwing or breaking of the current of the coil 21,
the movable core 1 has a high collision speed to the fixed core 2 and
repeats bounce operations for a while. Due to vibration associated with
such a repeat, so-called chattering in which the contact 7 of the primary
movable contact 4 and the contact 12 of the primary fixed contact 25
connect or disconnect for a short time is generated.
Therefore, there were problems that a large shock sound occurs from the
movable core 1, the fixed core 20, the crossbar 2, the base 10, etc. by
the above-mentioned throwing or breaking and dust occurs from the movable
core 1 etc. or repeat shocks are applied to the crossbar 2, the base 10
and so on.
DISCLOSURE OF THE INVENTION
This invention is implemented to solve the problems, and an object of the
invention is to provide an electromagnetic contactor for suppressing a
shock occurring in the case of throwing and opening.
In order to achieve this object, an electromagnetic contactor of a first
aspect is characterized in that in an electromagnetic contactor for
performing switching of a contact by controlling energization of an
electromagnet to move a movable core from a first position to a second
position with respect to a fixed core, there is provided attraction force
control means for controlling an integral value of a current flowing
through the electromagnet so that acceleration in the second position of
the movable core becomes a predetermined value or less.
An electromagnetic contactor of a second aspect is characterized in that in
an electromagnetic contactor for passing a current through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow by electromagnetic force and opening or closing a
contact, there is provided attraction force control means for passing a
first current through the electromagnet for a predetermined time so that
acceleration in the second position of the movable core becomes a
predetermined value and passing a second current through the electromagnet
in substantially the second position.
An electromagnetic contactor of a third aspect is characterized in that in
an electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a second
position in which a gap to a fixed core is narrow to a first position in
which the gap is wide and opening or closing a contact, there is provided
attraction force control means for breaking the current flowing through
the electromagnet and then passing a deceleration current through the
electromagnet for a predetermined time so that acceleration in the first
position of the movable core becomes a predetermined value.
An electromagnetic contactor of a fourth aspect is characterized in that in
an electromagnetic contactor for passing a current through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow by electromagnetic force and opening or closing a
contact, there are provided current control means for controlling the
current flowing through the electromagnet, and command means for passing a
first current through the electromagnet for a predetermined time by this
current control means to break the current and then passing a second
current through the electromagnet by the current control means at the time
when the movable core moves to substantially the second position after a
lapse of a predetermined time.
An electromagnetic contactor of a fifth aspect is characterized in that in
an electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a second
position in which a gap to a fixed core is narrow to a first position in
which the gap is wide and opening or closing a contact, there are provided
current control means for controlling the current flowing through the
electromagnet, and command means for breaking the current flowing through
the electromagnet by the current control means and then passing a
deceleration current through the electromagnet for a predetermined time by
the current control means after a predetermined time and breaking the
deceleration current by the current control means at the time when the
movable core moves to substantially the first position.
A value of a second current of an electromagnetic contactor of a sixth
aspect passes a holding current value through an electromagnet by current
control means after passing a current higher than the holding current
value necessary to hold the movable core in a second position through the
electromagnet for a predetermined time by the current control means.
An electromagnetic contactor of a seventh aspect is characterized in that
in an electromagnetic contactor for passing a current through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow by electromagnetic force and opening or closing a
contact, there are provided current control means for controlling the
current flowing through the electromagnet, and command means for passing a
first current through the electromagnet for a predetermined time by this
current control means and then passing a second current having a value
lower than the first current through the electromagnet for a predetermined
time by the current control means at a point in time when the movable core
approaches the second position and then passing a third current through
the electromagnet by the current control means at a point in time when the
movable core moves to substantially the second position.
An electromagnetic contactor of an eighth aspect is characterized in that
in an electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a second
position in which a gap to a fixed core is narrow to a first position in
which the gap is wide and opening or closing a contact, there are provided
current control means for controlling the current flowing through the
electromagnet, and command means for breaking the current flowing through
the electromagnet by the current control means and then passing a first
deceleration current through the electromagnet for a predetermined time by
the current control means after a lapse of a predetermined time and
passing a second deceleration current for a predetermined time by the
current control means at a point in time when the movable core approaches
the first position and then breaking the second deceleration current by
the current control means at a point in time when the movable core moves
to substantially the first position.
A command of command means or electromagnetic force control means of an
electromagnetic contactor of a ninth aspect is characterized by having a
predetermined slope in a rise or a fall of a current.
An electromagnetic contactor of a tenth aspect is characterized in that in
an electromagnetic contactor for passing a current through an
electromagnet from an AC power source and moving a movable core from a
first position in which a gap to a fixed core is wide to a second position
in which the gap is narrow by electromagnetic force and opening or closing
a contact, there is provided phase control means for shifting the AC power
source from OFF to ON at a predetermined voltage phase based on a command
of command means, and the command of the command means turns on the phase
control means for a predetermined time and applies a voltage to the
electromagnet and turns on the phase control means at a point in time when
the movable core reaches substantially the second position after a lapse
of a predetermined time.
An electromagnetic contactor of an eleventh aspect is characterized in that
in an electromagnetic contactor for breaking a current through an
electromagnet from an AC power source and moving a movable core from a
second position in which a gap to a fixed core is narrow to a first
position in which the gap is wide and opening or closing a contact, there
are provided opening signal means for generating an opening signal for
opening the electromagnetic contactor from closing, and phase control
means for shifting the AC power source from ON to OFF at a predetermined
voltage phase based on a command of command means and occurrence of the
opening signal and also turning on or off irrespective of the voltage
phase of the AC power source based on a signal of the command means after
the opening signal occurs, and the command of the command means breaks a
voltage of the electromagnet by the phase control means based on
occurrence of the opening signal of the opening command means and then
applies a voltage to the electromagnet for a predetermined time by the
phase control means after a predetermined time and shifts the phase
control means from ON to OFF at a point in time when the movable core
reaches substantially the first position.
An electromagnetic contactor of a twelfth aspect is characterized in that
in an electromagnetic contactor for breaking a current flowing through an
electromagnet from a power source and moving a movable core from a first
position in which a gap to a fixed core is wide to a second position in
which the gap is narrow and opening or closing a contact, the
electromagnet consists of a first electromagnet for exciting the fixed
core and a second electromagnet for exciting the movable core, and there
are provided current control means for controlling the current flowing
through the first and second electromagnets, switching means for switching
electromagnetic force occurring in the movable core and the fixed core to
attraction or repulsion by switching a direction of the current flowing
through the first or second electromagnet, and command means for passing a
first attraction current through the first and second electromagnets for a
predetermined time in an attraction direction of the movable core and the
fixed core by the current control means and the switching means and then
passing a first repulsion current through the first and second
electromagnets for a predetermined time in a repulsion direction of the
movable core and the fixed core by the current control means and the
switching means at a point in time when the movable core approaches the
second position and then passing the second attraction current through the
first and second electromagnets in an attraction direction of the movable
core and the fixed core by the current control means and the switching
means at a point in time when the movable core moves to substantially the
second position.
An electromagnetic contactor of a thirteenth aspect is characterized in
that in an electromagnetic contactor for breaking a current flowing
through an electromagnet from a power source and moving a movable core
from a second position in which a gap to a fixed core is narrow to a first
position in which the gap is wide and opening or closing a contact, the
electromagnet consists of a first electromagnet for exciting the fixed
core and a second electromagnet for exciting the movable core, and there
are provided switching means for switching electromagnetic force occurring
in the movable core and the fixed core to attraction or repulsion by
switching a direction of the current flowing through the first or second
electromagnet, and command means for passing a first repulsion current
through the first and second electromagnets for a predetermined time in a
repulsion direction of the movable core and the fixed core by the current
control means and the switching means and then passing a first attraction
current through the first and second electromagnets for a predetermined
time in an attraction direction of the movable core and the fixed core by
the current control means and the switching means and then breaking the
first attraction current at a point in time when the movable core moves to
substantially the first position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is the entire block diagram of an electric portion of an
electromagnetic contactor which is one embodiment of this invention.
FIG. 2 is an internal circuit diagram of a command generation part shown in
FIG. 1.
FIG. 3 is a time chart showing waveforms of each part with respect to an
operation of the electromagnetic contactor by FIG. 1.
FIG. 4 is a time chart showing waveforms of each part based on experiment
with respect to an operation of the electromagnetic contactor by FIG. 1.
FIG. 5 is an internal circuit diagram of a command generation part showing
another embodiment of this invention.
FIG. 6 is a time chart showing waveforms of each part with respect to an
operation of an electromagnetic contactor by FIG. 5.
FIG. 7 is an internal circuit diagram of a command generation part showing
the other embodiment of this invention.
FIG. 8 is a time chart showing waveforms of each part with respect to an
operation of an electromagnetic contactor by FIG. 7.
FIG. 9 is a time chart of each part in the case of a change in a power
voltage.
FIG. 10 is an internal circuit diagram for limiting a slope of a command
signal of a command generation part according to the other embodiment of
this invention.
FIG. 11 is a time chart showing waveforms of each part with respect to an
operation of an electromagnetic contactor by FIG. 10.
FIG. 12 is the entire block diagram of an electric portion of an AC drive
type electromagnetic contactor showing the other embodiment of this
invention.
FIG. 13 is an internal circuit of a synchronizing signal generation part
shown in FIG. 12.
FIG. 14 is a time chart showing waveforms of each part with respect to an
operation of an electromagnetic contactor by FIG. 12.
FIG. 15 is a front view providing an electromagnet for a movable core and a
fixed core of an electromagnetic contactor in the other embodiment of this
invention.
FIG. 16 is a block diagram showing an electric portion of an
electromagnetic contactor by FIG. 15.
FIG. 17 is an internal circuit diagram of a command generation part shown
in FIG. 16.
FIG. 18 is a time chart showing waveforms of each part with respect to an
operation of an electromagnetic contactor by FIG. 14.
FIG. 19 is a sectional view of an electromagnetic contactor.
BEST MODE FOR CARRYING OUT THE INVENTION
Next, in this invention, embodiments will be described as follows.
First Embodiment
An embodiment of this invention will be described with reference to FIGS. 1
and 2. FIG. 1 is a block diagram showing the entire connection showing one
embodiment of this invention, and FIG. 2 is a detailed internal circuit of
a command generation part shown in FIG. 1. In FIGS. 1 and 2, there are
provided a switching signal part 314 for generating a signal for throwing
or opening a current of an electromagnet 301 (coil 21) of an
electromagnetic contactor 100 shown in FIG. 19 by a switch 314S, and an
attraction force control part 303 acting as attraction force control means
for controlling electromagnetic attraction force of the electromagnet 301
by controlling an integral value of the current flowing through the
electromagnet 301 by a switching signal from the switching signal part
314.
The attraction force control part 303 comprises a command generation part
400 acting as command means for generating an attraction command value 407
which becomes a command for controlling the current of the electromagnet
301 by the switching signal of the switching signal part 314, a current
control part 401 for controlling the current flowing through the
electromagnet 301 by a command signal from the command generation part
400, a switch part 403 for performing ON-OFF control of the current
flowing through the electromagnet 301 by the command signal, and a DC
power source 402 connected to outputs of the current control part 401 and
the switch part 403.
The command generation part 400 comprises a timer TU1 for generating a
pulse for passing a strong acceleration current E1 acting as a first
acceleration current for time U1 by an ON (closing) signal of a switch
3045, a timer TU4 for generating a lag signal U4 of a steady-state current
E6 by ON of the switch 304S, a timer TU7 for generating a lag signal U7 of
a strong deceleration current E7 by an inversion signal in which an OFF
(opening) signal of the switch 304S is inverted by a NOT circuit 414, and
a timer TU8 for generating a pulse with time U8 based on a signal of the
timer TU7.
It is constructed so that by connecting outputs of switches 421, 426, 427
for connecting command values of each command part SE1, SE6, SE7 to
outputs based on each output signal of each the timer TU1, TU4, TU8, the
command values of each the command part SE1, SE6, SE7 are inputted to the
current control part 401 acting as current control means as an attraction
force command value 407 and also the output signals of each the timer TU1,
TU4, TU8 are inputted to the switch part 403 as a switch control signal
408 through an OR circuit 413.
In the current control part 401, the attraction force command value 407 is
connected to a plus input terminal of an amplifier 440 and a minus input
terminal is connected to an output of a current detector 406 for detecting
a current flowing through the electromagnet 301 and an output of the
amplifier 440 is connected to an input of a current control element 441
such as MOSFET for controlling the current flowing through a coil 301 of
the electromagnet and one end of the output is connected to one end of the
electromagnet 301 and the other end of the output is connected to the
power source 402, and the current control part 401 is constructed so that
the attraction force command value 407 and a detection value 491 are
compared by the amplifier 440.
That is, when a voltage of the attraction force command value 407 is added
to an input of the amplifier 440 in the current control part 401, since
the current control element 441 conducts and a current flows from the
power source 402 to the electromagnet 301 and the current detector 406
detects the current and the amplifier 440 operates so as to equalize the
detection value 491 (voltage value) to the attraction force command value
407, it is constructed so that a current proportional to the attraction
force command value 407 flows in the current of the electromagnet 301.
The switch part 403 comprises a driving circuit 462 for inputting a signal
of the switch control signal 408 and a current control element 461 capable
of controlling a current of MOSFET etc. in which a gate is connected to an
output of this driving circuit 462, and it is constructed so that the
current control element 461 is connected in series with the electromagnet
301 and the power source 402 and the current control element 461 is turned
on or off by an ON-OFF signal of the switch control signal 408.
Incidentally, diodes 404, 405 are connected between plus and minus
terminals of the power source 402 and terminals of the electromagnet 301
and in the case that the command value 407 of the command generation part
400 decreases and the switch part 403 becomes OFF, when an overvoltage
occurring between the terminals of the electromagnet 301 becomes higher
than a voltage of the power source 402, a current flows and regenerates to
the power source 402 and also the current is reduced speedily.
A throwing and opening operation of the electromagnetic contactor
constructed as mentioned above will be described by FIGS. 1 to 3. FIG. 3
is a time chart showing operations of each part of the electromagnetic
contactor and in FIG. 3, (a) shows a signal of the switch 304S and (b)
shows a current waveform flowing through the electromagnet 301 and (c)
shows a moving curve of a movable core 1 and (d), (g), (i), (j) show
operating time of each the timer and (m) shows a time value of each point.
First, an operation in the case of throwing will be described. At time T1,
when the switch 304S becomes ON, a pulse with time U1 is generated through
the timer TU1 and also the switch 421 becomes ON and the command part SE1
is set to the attraction force command value 407 and the pulse with time
U1 is provided to the current control part 401. The current control part
401 turns on the current control element 441 through the amplifier 440. At
the same time, an output signal (high) of the timer TU7, the timer TU8
through the NOT circuit 414 is provided to the OR circuit 413 and the
switch signal 408 from the OR circuit 413 is provided to the driving
circuit 462 and the current control element 461 is turned on.
Therefore, a strong acceleration current E1 acting as a first current with
a pulse shape flows through the electromagnet 301, and strong attraction
force occurs between a movable core 1 and a fixed core 20, and the movable
core 1 does not move at a point in time of numeral 310 shown in FIG. 3(c)
and starts acceleration from a point in time of numeral 311 after a while,
and a speed increases and at numeral 312 of time T2 after a lapse of time
U1, the switch 421 becomes OFF and an attraction force command becomes OFF
and the current control part 401 becomes OFF to break the strong
acceleration current E1.
By the break, the movable core 1 approaches against repulsion of a trip
spring 30 etc. in a direction of the fixed core 20 under inertia, and the
speed becomes zero at a position of numeral 313 of second position time T5
which is a position reaching the fixed core 20 just.
Here, in the movable core 1, a speed Vs of numeral 312 is determined so
that the speed of the position of numeral 313 which is a second position
becomes zero, and in order to set electromagnetic attraction force for
obtaining the speed Vs of numeral 312, a value of the strong acceleration
current E1 and the time U1, namely an integral value of the strong
acceleration current E1 is set. Therefore, since the integral value of the
strong acceleration current E1 may be set (controlled), a waveform of the
strong acceleration current E1 does not need to be a pulse shape.
After a lapse of time U4 since the switch 304S became ON, namely at numeral
313, an output of the timer TU4 becomes ON and the switch control signal
408 which is an output of the OR circuit 413 becomes ON to turn on the
switch part 403, and also the switch 426 of the command generation part
400 becomes ON and when the command part SE6 is set to pass a suction
current E6 acting as a second current through the electromagnet 301 via
the current control part 401, the movable core 1 is already present in a
position (second position) of a narrow gap with respect to the fixed core
20, so that the movable core 1 is sucked and held to the fixed core 20.
Here, since the suction current E6 maybe a holding current in which the
movable core 1 maintains a state of suction to the fixed core 20 in the
second position, even in case of a considerably low current compared with
the strong acceleration current E1, the movable core 1 can be sucked and
the suction current E6 is continuously supplied while the switch 304S has
been turned on. Incidentally, unless the suction current E6 is passed
through electromagnet 301, the movable core 1 moves away from the fixed
core 20 as shown by numeral 314.
Therefore, after the suction current E6 is passed through the electromagnet
301 by predetermined time after turning on the switch 304S, the speed of
the movable core 1 becomes substantially zero at a point in time when the
movable core 1 reaches the fixed core 20, and the movable core 1 passes
the suction current E6 in a position of numeral 313 to hold the movable
core 1 in the second position, so th | | |
