JPH0220701Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electromagnetic direct current detection device for detecting whether a direct current flowing through a coil is less than or equal to a predetermined value.

In order to distinguish and detect whether the direct current is below a predetermined value or above a predetermined value, there is a method in which an auxiliary switch is linked to a movable arm for opening and closing the main contact of an electromagnetic circuit breaker. According to this method, the auxiliary switch can detect that the main contact is opened due to overcurrent or overvoltage, and notify the external circuit. Incidentally, there are cases in which opening and closing of the main contacts is not required, but only detecting whether the current is less than a predetermined value or greater than or equal to a predetermined value is required. In such a case, a method can be considered in which the relationship between the electromagnet and the armature of the electromagnetic circuit breaker is utilized, and the armature is used as an actuator of the auxiliary switch to open and close the contacts.
However, even if the principle of a circuit breaker's electromagnetic operating mechanism is used as is for direct current detection, residual magnetism makes it impossible to operate accurately. That is, when the current detection electromagnet attracts the armature, that is, the actuator of the switch, at a predetermined current value,
The current flowing through the coil due to residual magnetism is
Even if it drops to about 50%, the state where the electromagnet attracts the armature may be maintained. Therefore, the self-restoration becomes inaccurate and cannot be applied to a circuit that must perform self-return immediately when the current becomes less than a predetermined value.

Therefore, an object of the present invention is to provide a DC detection device that can quickly self-reset.

To achieve the above object, the present invention is formed so as to be connected to the path of the current to be detected, and wound so as to generate a magnetic pole having a strength corresponding to the magnitude of the current to be detected. a direct current detection coil and a permanent magnet that has a directionality such that a repulsion occurs between the magnetic pole of the coil and is placed in contact with or close to the magnetic pole of the coil; The permanent magnet has a directionality such that it moves in the direction of the magnetic pole, and when the current flowing through the coil is less than a predetermined value, the permanent magnet is maintained at a first position in contact with or close to the coil, and when the current is equal to or higher than the predetermined value a switch actuating member supporting the permanent magnet with a biasing force having a strength to permit the permanent magnet to be displaced to a second position spaced apart from the magnetic poles of the coil when . A switch that operates on and off according to a change in the position of the actuating member corresponding to the first and second positions of the coil, and notifies an external circuit whether the current flowing through the coil is less than a predetermined value or greater than or equal to a predetermined value. The present invention relates to a DC detector characterized by comprising a contact point.

In the above invention, when the current flowing through the coil is less than a predetermined value, the permanent magnet and the actuating member are moved between the electromagnet formed by the coil and the permanent magnet from the first position to the second position by magnetic repulsion. There is not enough force to displace it to that position. On the other hand, when the current in the coil exceeds a predetermined value, the repulsive force between the electromagnet and the permanent magnet increases, and the permanent magnet and the actuating member change to the second position.

Thereafter, when the current in the coil becomes less than the predetermined value again, the repulsive force between the magnetic pole and the permanent magnet due to the coil becomes weak or becomes zero, and the permanent magnet is returned to the first position by the biasing force of the actuating member. Return to When the permanent magnet is in the second position, since the permanent magnet is spaced apart from the magnetic pole of the coil, there is no interference with return due to attraction due to residual magnetism that occurs in conventional devices. Therefore, the permanent magnet can be quickly and accurately returned from the second position to the first position.

Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

The electromagnetic direct current detecting device shown in FIG. 1 has a direct current detecting coil 1 constituting a current detecting electromagnet, and this coil 1 is wound around a rod-shaped magnetic core 3 having a magnetic pole 2. Further, an L-shaped magnetic frame 4 is provided to form a good magnetic path for the electromagnet. Note that this frame 4 is an electromagnet case 5.
It is also used to attach to. One end and the other end of the coil 1 are connected to terminals 8 and 9 by copper braided wires 6 and 7, respectively.

A current detecting switch 10 for responding to an electromagnet consisting of a coil 1 and a magnetic core 3 is a micro switch, and has an actuator, that is, a plate-shaped switch operating member 11, and a cylindrical permanent member attached to the tip of the operating member 11. A magnet 12 is fixed. This permanent magnet 12 is arranged with a polarity that repels the magnetic pole of an electromagnet consisting of a coil 1 and a magnetic core 2, and is activated by the repulsive force of the electromagnet that occurs when the current flowing through the coil 1 exceeds a predetermined value. The member 11 is magnetized so as to move from a position (first position) shown by a solid line in FIG. 1 to a position (second position) shown by a chain line. As shown in FIG. 2, the actuating member 11 is rotatably supported on a fulcrum 13, and is movable between a first position shown by a solid line in FIG. 1 and a second position shown by a chain line in FIG. Micro switch 10
includes a normally closed contact 14, a normally open contact 15, and a movable contact 16. The normally closed contact 14 is electrically connected to a terminal 17, the normally open contact 15 is electrically connected to a terminal 18, and the movable contact 16 is electrically connected to a common terminal 19. Note that the movable contact 16 is supported by a leaf spring 20 biased upward, and the movable contact 16 is supported by a leaf spring 20 that is biased upward.
1 and the plate spring 20, an interlocking rod 21 is disposed between the interlocking rod 21 and the flange-like portion 22 and the fixing portion 23.
A return spring 24 is arranged between.

In the current detection device configured as described above,
When the current flowing through the coil 1 is zero or less than a predetermined value, the magnetic flux of the permanent magnet 12 overcomes the magnetic flux of the electromagnet and no electromagnet is substantially formed, or even if an electromagnet is formed, the permanent magnet 12 and Since the repulsive force is weak, no force is generated to overcome the clockwise biasing force of the actuating member 11 provided by the spring 24 and the leaf spring 20 and move the permanent magnet 12 to the second position. Therefore, the permanent magnet 12 is kept in contact with or close to the magnetic pole 2, the movable contact 16 and the normally closed contact 14 are kept in the on state, and the normally open contact 15 is kept in the off state.

On the other hand, when the current in the coil 1 exceeds a predetermined value due to a load short circuit or the like, a magnetic flux is generated from the electromagnet that overcomes the magnetic flux of the permanent magnet 12, and the permanent magnet 12 is moved to the second position against the biasing force of the actuating member 11. A magnetic pole 2 is formed that can obtain a repulsive force that can move the magnetic pole to a position of . As a result, the normally closed contact 14 is turned off, the normally open contact 15 is turned on, and the terminal 17 is set to 1.
A notification device such as a lamp or a detection circuit connected to the coil 8 detects that a current exceeding a predetermined value flows through the coil 1 due to a load short circuit or the like. When the current in the coil 1 becomes less than the predetermined value again, the permanent magnet 12 is hardly affected by the residual magnetism, and when the current decreases slightly below the predetermined value, the permanent magnet 12 and the actuating member 11 switch to the second state. It becomes impossible to hold the position. This causes contact 15 to turn off quickly,
It is possible to detect that the overcurrent condition has been resolved.

As is clear from the above, according to the DC current detection device of this embodiment, the magnetic flux caused by the electromagnet and the magnetic flux caused by the permanent magnet 12 are magnetically compared, and the repulsive force between the electromagnet and the permanent magnet 12 is determined to be a constant value. In this case, since the actuating member 11 is configured to be in the second position, it becomes less susceptible to the influence of residual magnetism, and it becomes possible to quickly achieve self-return.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be further modified. For example, as shown in FIG. 3, a contact point 25 is provided directly on the right end of the switch operating member 11,
When the current in the coil 1 increases to a predetermined value or more and the permanent magnet 12 is repelled, the switch actuating member 11 rotates counterclockwise around the fulcrum 13, and the contact 25
The contact 26 may be turned on. In addition, the spring 24 in FIG. 1 is omitted, and the leaf spring 2
The biasing force may be applied only by 0. Further, the actuating member 11 is formed of a plate spring, and the actuating member 11
It may have its own biasing force. Also,
A configuration may also be adopted in which no biasing force is applied to the actuating member 11. Further, the actuating member 11 may be moved up and down without rotating. Further, in order to easily change the detected current value, a tap may be provided on the coil 1 to change the ampere/turn. Of course, it can also be applied to DC voltage detection.
Moreover, without providing the magnetic core 3 at the entire center of the coil 1,
It may be provided only in a portion facing the permanent magnet 12. Alternatively, the magnetic core 3 may be a combination of a fixed core and a moving core, so that the moving core gradually approaches the fixed core due to overcurrent, and the maximum magnetic flux is generated when the moving core approaches the fixed core. That is, a delayed response core configuration may be used. Further, the magnetic core 3 may be omitted and the magnet may be formed by only the coil 1 or in combination with the frame 4.

[Brief explanation of the drawing]

Fig. 1 is a partially longitudinal front view showing a direct current detection device according to an embodiment of the present invention, Fig. 2 is a plan view of the switch operating member shown in Fig. 1, and Fig. 3 is a modification of the switch operating member. It is a front view. In addition, in the symbols used in the drawings, 1 is a current detection coil, 2 is a magnetic pole, 3 is a magnetic core, 4 is a frame, 10 is a switch, 11 is a switch operating member,
12 is a permanent magnet.

Claims (1)

[Claims for Utility Model Registration] For direct current detection, which is formed so as to be connected to the path of the current to be detected and is wound so as to generate a magnetic pole having a strength corresponding to the magnitude of the current to be detected. a permanent magnet having a direction such that repulsion occurs between the coil and the magnetic pole of the coil, and which is placed in contact with or close to the magnetic pole of the coil; and the permanent magnet is oriented in the direction of the magnetic pole of the coil. and when the current flowing through the coil is less than a predetermined value, the permanent magnet is kept in a first position in contact with or close to the coil;
actuation of a switch supporting said permanent magnet with a biasing force having a strength to allow said permanent magnet to be displaced to a second position spaced from the magnetic poles of said coil when said current is above a predetermined value; member, and is turned on and off by changes in the position of the actuating member corresponding to the first and second positions of the permanent magnet, and the current flowing through the coil is less than a predetermined value or more than a predetermined value. A direct current detector characterized in that it is equipped with a switch contact for notifying an external circuit of the current condition.