JPH0375971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit protection device that protects a load circuit from overcurrent.

[Prior art] As a circuit protection device, the applicant has proposed
In Japanese Patent No. 182634, a movable member made of a magnetic material is attracted by a permanent magnet to a first position in contact with a yoke to close an electric path, and when an overcurrent flows through a coil wound around the yoke, the permanent A method has already been proposed in which the magnetic attraction force of the movable member by a magnet is weakened and the movable member is displaced to a second position separated from the yoke by an urging means to interrupt the electric path.

According to this circuit protection device, a coil is wound around the yoke to generate a magnetic flux in the movable member that resists the magnetic attraction force of the permanent magnet, so the magnetic resistance of the magnetic circuit of the coil is extremely reduced. It can be made smaller and the magnetic material of the yoke and movable parts can be reduced.
BH characteristics can be used efficiently. Therefore, even if the number of turns in the coil is small, a large magnetic flux can be generated by a small increase in current.
The electric circuit can be instantaneously interrupted without variation, thereby improving responsiveness and reliability, and also reducing internal impedance, which has the effect of not having any adverse effect on the load circuit to be protected.

[Problem that the invention seeks to solve]

However, the above-mentioned circuit protection device does not have a function to automatically reset the electric circuit, and once the electric circuit is interrupted due to an overcurrent, the movable member must be manually reset against the energizing means. It is necessary to move it from the second position to the first position and attract and hold it to the yoke using a permanent magnet. For this reason, when applied to a seasoning device such as a laser or a screening device, the electrical circuit is cut off each time a defective product is produced, and the electrical circuit must be manually reset each time, making operation cumbersome. There's a problem.

One possible way to solve this problem is to automatically reset using an electromagnetic solenoid, but in this case, a large drive current of several amperes is required, so it is not energy efficient. So it's not desirable.

This invention was made by focusing on these conventional problems, and provides a circuit that is appropriately configured so that it can automatically reset an electrical circuit that has been cut off due to overcurrent, and consumes less energy. The purpose is to provide a protective device.

[Means and actions for solving problems]

In order to achieve the above object, the present invention provides the first
a movable member made of a magnetic material that can be displaced to a second position; a permanent magnet that magnetically attracts the movable member to the first position; and a permanent magnet that abuts the movable member in the first position of the movable member; a yoke that defines a closed loop magnetic path; a first coil that is wound around the yoke and generates a magnetic flux that resists the magnetic attraction of the movable member by the permanent magnet; a second coil for selectively holding the movable member in the second position; a movable contact that displaces in conjunction with the displacement of the movable member; and a movable contact that displaces in conjunction with the displacement of the movable member. a fixed contact that contacts the movable contact when the movable member is in the first position; and a first switching means that is non-conductive when the movable member is in the first position and conductive when the movable member is in the second position. and an energization detection means for detecting an energization state of a load circuit connected via the first coil, a fixed contact, and a movable contact when the movable member is in a first position; a current source for supplying current to a reset path passing through the second coil and the first switching means; and a second switch provided in the reset path.
and a switch control means for controlling the second switching means based on the output of the energization detection means and a reset signal selectively inputted from the outside, when an overcurrent is applied to the first coil. When the current flows, the movable member is displaced from the first position to the second position to interrupt the electrical path of the load circuit, and the current flows from the current source through the first and second switching means to the second coil. The movable member is held in the second position by the magnetic flux generated by the energizing means and the second coil, and in this state, the switch is controlled by the output of the energization detecting means and the reset signal. said second via means
By making the switching means non-conductive and cutting off the supply of current to the second coil, the movable member is displaced to the first position by the permanent magnet against the energizing means, and the load circuit is The circuit is configured to be able to automatically reset the electrical circuit.

〔Example〕

FIG. 1 is a block diagram showing the overall structure of a first embodiment of the present invention. The circuit protector 1 is provided with a U-shaped yoke 2, and a first coil 3 and a second coil 4 are wound around the legs 2a and 2b of the yoke 2, respectively.
A permanent magnet 5 is provided between the yoke 2 and the yoke 2, and the permanent magnet 5 magnetically attracts the movable member 6 made of a magnetic material so that it comes into contact with the open end of the yoke 2. The movable member 6 is provided so as to be displaceable between a first position where it abuts the open end of the yoke 2 and a second position where it is spaced apart from the open end and abuts against the stopper 7.
energizes it to the second position. In addition, the movable member 6
is provided with an actuating piece 9, and a movable contact 10 is provided so as to be driven by the actuating piece 9 in conjunction with the displacement of the movable member 6, and a first fixed contact 11 and a second fixed contact are provided on both sides of the movable contact 10. A fixed contact 12 is provided. In this way, when the movable member 6 is in the first position, the movable contact 10 is connected to the first fixed contact 1.
1, and the movable contact 10 and the second fixed contact 12 constitute a first switching means so that when the movable member 6 is in the second position, the movable contact 10 is in contact with the second fixed contact. Make contact with the contact point 12.

One end of the first coil 3 is connected to the first fixed contact 11, and the other end of the first coil 3 is connected to the movable contact 1.
0, a power supply 13, an energization detection circuit 14, and a load circuit 15 are connected between the first coil 3 and the first
An electric path of the load circuit 15 is formed through the fixed contact 11 and the movable contact 10. Also, the second
One end of the coil 4 is connected to a second fixed contact 12, and the other end of the second coil 4 is connected to a normally closed switching circuit 16 constituting a second switching means.
is connected to one end of the power supply 13 through the movable contact 1.
0, the second fixed contact 12, the second coil 4, and the switching circuit 16 form a reset path electric path, and the switching circuit 16 in this reset path connects the energization detection circuit 1.
The switch control circuit 17 performs control based on the output of the switch 4 and a reset signal from the outside.

Here, the first coil 3 is energized to generate a magnetic flux that resists the magnetic attraction force of the movable member 6 by the permanent magnet 5, and when a current below the rating is flowing in the load circuit 15, the permanent magnet 5 The magnetic attractive force of the first coil 3 is made stronger than the demagnetizing force of the first coil 3 and the biasing force of the biasing means 8, and
When a current exceeding the rating flows, the first coil 3
The biasing force of the biasing means 8 is set to be stronger than the magnetic attraction force of the permanent magnet 5 due to the demagnetizing force. Similarly to the first coil 3, the second coil 4 is energized to generate a magnetic flux that resists the magnetic attraction of the movable member 6 by the permanent magnet 5.
This allows the movable member 6 to be effectively held in the second position.

In the above configuration, when the movable member 6 is in the first position and the movable contact 10 is in contact with the first fixed contact 11 and a current below the rating is flowing in the load circuit 15, the magnetic Since the attractive force is stronger than the demagnetizing force of the first coil 3 and the biasing force of the biasing means 8, the movable member 6 is held in the first position in contact with the yoke 2, and therefore the load circuit 15 is The energized state is maintained effectively. In this state, if the current flowing through the load circuit 15 increases due to a malfunction or the like, the attractive force due to the permanent magnetic force 5 will be reduced by the magnetic flux in the opposite direction from the first coil 3, and if the current value exceeds the rated value, the permanent magnetic force will become permanent. The biasing force of the biasing means 8 becomes stronger than the attractive force of the magnet 5, and as a result, the movable member 6 is displaced to the second position where it comes into contact with the stopper 7, and the electrical path of the load circuit 15 is interrupted, thereby detecting energization. A cutoff signal indicating cutoff of the electric circuit is supplied from the circuit 14 to the switch control circuit 17, and the movable contact 10 contacts the second fixed contact 12 to close the reset passage. A current flows through the coil 4 of No. 2, and a magnetic flux is generated that resists the magnetic attraction force of the movable member 6 by the permanent magnet 5. Therefore, an overcurrent flows through the load circuit 15,
The movable member 6 is displaced to the second position and the load circuit 15
Even if the current path is interrupted, the reset path is simultaneously closed and a current flows through the second coil 4 so as to generate a magnetic flux that resists the magnetic attraction force of the movable member 6 by the permanent magnet 5. The movable member 6 will be effectively held in the second position by the biasing means 8. Note that the current supplied to the second coil 4 at this time is only required to generate a magnetic flux in the yoke 2 that weakens the magnetic attraction force of the movable member 6 by the permanent magnet 5, so the current supplied to the second coil 4 can be extremely small.

When the electrical path of the load circuit 15 is cut off, when the cause of the electrical circuit interruption of the load circuit 15 is eliminated and a reset signal is supplied to the switch control circuit 17, the switch is activated based on this reset signal and the cutoff signal from the energization detection circuit 14. A drive signal is supplied from the control circuit 17 to the switching circuit 16, whereby the reset path electrical circuit is cut off in the switching circuit 16. As a result, the movable member 6 which was in the second position is attracted by the magnetic attraction force of the permanent magnet 5 against the urging force of the urging means 8 and is displaced to the first position. contacts the first fixed contact 11 from the second fixed contact 12, and the electric path of the load circuit 15 is automatically reset.

According to this embodiment, the electrical path of the load circuit 15 can be quickly interrupted in the event of an overcurrent, and the interrupted state can be effectively maintained by passing a small current through the second coil 4. By cutting off the supply of current to the coil 4 by the switching circuit 16, the electric path of the load circuit 15 can be automatically reset. Therefore, operability can be improved and energy consumption can be reduced.

2A to 2D show an example of a specific configuration of the circuit protector 1 shown in FIG. 1. FIG. This circuit protector 1 includes a case body 20 made of a non-magnetic and non-conductive material such as plastic, a lid 21 made of the same material as the case body 20, and a U
The character-shaped main yoke 22 and this main yoke 2
a first coil 23 and a second coil 24 wound around each of the legs 22a, 22b of the main yoke 22, a permanent magnet 25 attached between the legs 22a, 22b of the main yoke 22, and a movable member made of a magnetic material. 26
and. The movable member 26 is attached to the case body 20 so as to be changeable between a first position in contact with the open end of the main yoke 22 and a second position away from the open end via a leaf spring 27. Attach the actuating piece 28. Further, a movable contact 30 is provided on the case body 20 so as to be displaced by the movable member 26, and this movable contact 3
The first and second fixed contacts 31 and 32 are provided so as to selectively contact the first fixed contact 30 and the first fixed contact 31 when the movable member 26 is in the first position.
When the movable contact 30 is in the second position,
The fixed contacts 32 are brought into contact with each other.

In this embodiment, in order to give the main yoke 22 a shape that is difficult to magnetically saturate, one leg portion 22 of the main yoke 22 is
Grooves 35a to 35d are formed at both ends covered by the first coil 23 in a. In addition, the leg portion 22a
, one end of the auxiliary yoke 37 is attached with a screw 38 so that the magnetic flux from the first and second coils 23 and 24 passes through.
At the same time, the other end of this auxiliary yoke 37 is extended to a position facing the movable member 26, and a permanent magnet 39 is fixed to this other end.

Connecting pins 41, 42 and 43 are attached to the case body 20, and the first coil 2 is connected to the connecting pin 41.
3, the movable contact 30 is connected to the connecting pin 42, one end of the second coil 24 is connected to the connecting pin 43, the other end of the first coil 23 is connected to the first fixed contact 31, and the movable contact 30 is connected to the connecting pin 43. The other ends of the coils 24 are connected to second fixed contacts 32, respectively. In this way,
As shown in FIG. 1, the power supply 13, the energization detection circuit 14, and the load circuit 15 are connected between the connection pins 41 and 42 to form an electric path for the load circuit 15. During this time, the switching circuit 16 is connected via the power source 13 to form a reset path, and the switching circuit 16 in this reset path is activated by the switch control circuit 17 based on the output of the energization detection circuit 14 and a reset signal from the outside. The drive is controlled by

In this circuit protector 1, the movable member 2
6 is in the first position, when the movable contact 30 is in contact with the first fixed contact 31 and a current below the rating is flowing through the load circuit 15 (see Fig. 1), the permanent magnet 25 causes the movable member to 26 to main yoke 22
Since the magnetic force attracted by the movable member 26 is stronger, the movable member 26 is held in the first position in contact with the main yoke 22, and therefore the energized state of the load circuit 15 is effectively maintained. In this state, when the current flowing through the load circuit 15 increases due to a malfunction or the like, the attractive force of the permanent magnet 25 decreases due to the magnetic flux in the opposite direction from the first coil 23, and if the current value exceeds the rated value, The attraction force generated between the permanent magnet 39 and the movable member 26 increases rapidly, and the attraction force becomes larger than the attraction force of the movable member 26 to the main yoke 22 by the permanent magnet 25. As a result, the movable member 26 is attracted and held by the permanent magnet 39 at a second position spaced apart from the main yoke 22, and the movable contact 30 is thereby moved closer to the first fixed contact 3.
1 and contacts the second fixed contact 32, current flows through the second coil 24, and a cutoff signal is supplied from the energization detection circuit 14 to the switch control circuit 17 as explained in FIG. .

Here, the main yoke 22 and the movable member 26
Even if the current flowing through the first coil 23 increases significantly and exceeds the rated current, the main yoke 2
The main yoke 22 and the movable member 2 have grooves 35a to 35d, and have a shape in which a demagnetizing field is formed in these grooves, making it difficult to be magnetically saturated.
6 is not magnetized by the magnetic flux caused by sudden changes in the current flowing through the first coil 23. Therefore, the movable member 26 is quickly and reliably separated even when a relatively small overcurrent flows through the first coil 23 or when an extremely large overcurrent flows. In this way, the load circuit 15 is protected from overcurrent by quickly interrupting the electrical path of the load circuit 15 in the event of an overcurrent, and this interrupted state is made effective by passing a small current through the second coil 24 of the reset path. to hold.

Thereafter, as explained in FIG. 1, by eliminating the cause of the disconnection of the electrical path in the load circuit 15 and supplying a reset signal to the switch control circuit 17, this reset signal and the disconnection signal from the energization detection circuit 14 are combined. Based on this, a drive signal is supplied from the switch control circuit 17 to the switching circuit 16, whereby the electric circuit of the reset path is cut off in the switching circuit 16, and the movable member 26 in the second position is moved by the magnetic attraction of the permanent magnet 25. The movable contact 30 is moved to the first position to bring the second fixed contact 32 into contact with the first fixed contact 31, thereby automatically resetting the electric path of the load circuit 15.

FIG. 3 shows a second embodiment of the invention. In this embodiment, the second coil 4 is connected to the movable member 6.
The movable member 6 is wound around the yoke 45 at the second position side, and one end thereof is connected to the second fixed contact 12 and the other end is connected to the power supply 13 via the normally closed switching circuit 16. At the same time, by opening the switch of the switching circuit 16 by the switch control circuit 17, the movable member 6 is displaced to the first position by the attractive force of the permanent magnet 5, and the load circuit is moved to the first position. 15 electric circuits are automatically reset, and the other configurations are the same as in the first embodiment. Therefore, the same effects as in the first embodiment can be obtained.

FIG. 4 shows a third embodiment of the invention. In this embodiment, a third coil 46 is wound around the leg 2b of the yoke 2 in FIG. Connect and move the movable member 6
is held in a second position by a second colui 4;
At the time of reset, the switching circuit 16 is turned off by the switch control circuit 17, and the switching circuit 47 is turned off.
By turning on, the third coil 46 generates a magnetic flux that promotes the attractive force of the permanent magnet 5.The other configuration is the same as that of the second embodiment. Therefore, according to this embodiment, in addition to the effects of the first embodiment, the reset speed for moving the movable member 6 from the second position to the first position can be made faster. Note that in this embodiment, one end of the third coil 46 may be connected to the movable contact 10.

FIG. 5 shows a fourth embodiment of the invention. In this embodiment, the first coil 3 is wound around the legs 2a and 2b of the yoke 2 in the second embodiment.
Consisting of two coils 3-1 and 3-2,
Connect these in parallel or series to create a permanent magnet 5.
The other configuration is the same as that of the second embodiment. Therefore, in this embodiment as well, the same effects as in the first embodiment can be obtained.

Note that this invention is not limited only to the embodiments described above, and numerous modifications and changes are possible. For example, in the circuit protector 1 shown in FIGS. 2A to 2D, four grooves 35a to 35d are formed in one leg 22a of the main yoke 22 to give the main yoke 22 a shape that is less susceptible to magnetic saturation. , the number of grooves may be arbitrary, and the grooves may be formed at any position on the other leg 22b or the part connecting both legs, and the shape is not limited to grooves, for example, it may be formed partially. Make it spherical, etc.
It can be formed arbitrarily, and the movable member 26 can be similarly formed in place of the main yoke 22 or together with the main yoke 22 to have a shape that is less susceptible to magnetic saturation. Further, it is also possible to eliminate such a configuration in which the shape is difficult to be magnetically saturated. Furthermore, in the circuit protector shown in FIG. 2, an auxiliary yoke 37 is connected to the main yoke 22, and a permanent magnet 39 is attached to this auxiliary yoke 37.
is attached to urge the movable member 26 in the direction away from the main yoke 22. However, instead of using such an auxiliary yoke 37 and the permanent magnet 39, a spring or the like can be used to force the movable member 26 away from the main yoke 22. It may also be energized in the direction of Furthermore, in the above embodiment, the power supply for the load circuit is shared to supply current to the reset path having the second coil, but separate power supplies are used for the load circuit and the reset path. Good too. Furthermore, in the above-described embodiment, the first switching means in the reset passage was composed of a movable contact and a second fixed contact, but this first switching means uses a non-contact switch, which is connected by a movable member. It can also be configured to be driven by

〔Effect of the invention〕

As described above, according to the present invention, the electrical path of the load circuit can be quickly interrupted in the event of an overcurrent, and the interrupted state can be effectively maintained by passing a small current through the second coil. By cutting off the supply of current to the second coil, the electrical path of the cut-off load circuit can be automatically reset. Therefore, operability can be improved, and
This has the effect of requiring less energy consumption.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG.
In the figures, A to D are diagrams showing an example of a specific configuration of the circuit protector shown in FIG. 1, and FIG.
FIG. 4 is a diagram showing the third embodiment, and FIG. 5 is a diagram showing the fourth embodiment. 1...Circuit protector, 2...Yoke, 3...
First coil, 4... Second coil, 5... Permanent magnet, 6... Movable member, 7... Stopper, 8...
energizing means, 9... operating piece, 10... movable contact, 1
DESCRIPTION OF SYMBOLS 1... First fixed contact, 12... Second fixed contact, 13... Power supply, 14... Energization detection circuit, 15
...Load circuit, 16...Switching circuit, 17
...Switch control circuit.

Claims (1)

[Scope of Claims] 1. A movable member made of a magnetic material that can be displaced to a first and a second position; a permanent magnet that magnetically attracts the movable member to the first position; a first movable member of the movable member; a yoke that comes into contact with the movable member at a position to define a closed-loop magnetic path; and a first yoke that is wound around the yoke and generates a magnetic flux that resists the magnetic attraction of the movable member by the permanent magnet. a coil; a biasing means for biasing the movable member to a second position; a second coil for selectively holding the movable member in the second position; a fixed contact that is in contact with the movable contact when the movable member is in the first position; and a fixed contact that is non-conducting when the movable member is in the first position and is in a second position. a first switching means that conducts at a certain time; and an energization device that detects the energization state of a load circuit connected via the first coil, fixed contact, and movable contact when the movable member is in a first position. sensing means; a current source for supplying current to a reset path passing through the second coil and first switching means with the movable member in a second position; a second current source provided in the reset path; a switching means; and a switch control means for controlling the second switching means based on the output of the energization detection means and a reset signal selectively inputted from the outside, and the switch control means controls the second switching means based on the output of the energization detection means and a reset signal selectively inputted from the outside, and when an overcurrent flows through the first coil. When the movable member is moved from the first position to the second position, the electric path of the load circuit is cut off, and the current is supplied from the current source to the second coil through the first and second switching means. A current is applied to hold the movable member in the second position by the magnetic flux generated by the energizing means and the second coil, and in this state, the switch control means is activated by the output of the energization detecting means and a reset signal. through the second
By making the switching means non-conductive and cutting off the supply of current to the second coil, the movable member is displaced to the first position by the permanent magnet against the energizing means, and the load circuit is A circuit protection device characterized in that it is configured to automatically reset an electric circuit.