JPH0228217B2 - - Google Patents

Description

[Detailed description of the invention] Technical field The present invention relates to a circuit protector.

PRIOR ART A conventional circuit protector is of the oil dump pot type. This oil dart pot-shaped circuit protector consists of a case filled with silicone oil, a coil wrapped around the outer circumference of the case, an electromagnetic pole provided at one end of the case, and a magnetic pole that is magnetically attracted to the case. An electromagnetic tripping device has an electromagnetic tripping device having a movable iron piece that can be displaced as shown in FIG. Due to the action of the magnetic force when the magnetic force flows, the plunger is moved against the braking force of the return spring and silicone oil and brought into contact with the electromagnetic pole, thereby attracting the movable iron piece to the electromagnetic pole and causing the movable iron piece to The movable contact is separated from the fixed contact in conjunction with the displacement of the fixed contact, thereby interrupting the electrical circuit.

However, in this circuit protector, when an overcurrent occurs, the plunger is moved against the braking force of the return spring and silicone oil and comes into contact with the electromagnetic pole, thereby interrupting the electrical circuit. The operating time until the electric circuit is interrupted is long, as shown by curves A and B in FIG. 1, for example, and the variation thereof is large, resulting in poor responsiveness and reliability. In addition, the magnetic resistance of the magnetic circuit through which the magnetic flux from the coil passes is extremely high, and a large magnetic flux density is required to move the plunger against the braking force of the return spring and silicone oil, so the number of turns in the coil is increased. It is necessary to increase the magnetomotive force, which causes an increase in internal impedance, which has a negative effect on the circuit to be protected.

OBJECT OF THE INVENTION An object of the present invention is to solve the various problems mentioned above, to provide a circuit protector that can be constructed easily and inexpensively, has a small internal impedance, and has excellent responsiveness and reliability. be.

Summary of the Invention The circuit protector of the present invention includes a movable member made of a magnetic material that can be displaced to first and second positions for closing and interrupting an electric circuit, and a movable member that magnetically attracts the movable member to the first position. a first permanent magnet; a first yoke that abuts the movable member at a first position of the movable member to define a closed loop magnetic path; a coil that generates a magnetic flux that resists the magnetic attraction force of the movable member by the first permanent magnet; a second permanent magnet that magnetically attracts the movable member to a second position; and the second permanent magnet. and a second yoke connected to the first yoke and facing away from the movable member at the first position of the movable member, the magnetomotive force of the second permanent magnet and the second yoke being coupled to the second yoke. The movable member is configured to act on the magnetomotive force of the coil so that when an overcurrent flows through the coil, the movable member is moved from a first position to a second position to interrupt the electric circuit. That is.

Embodiment FIGS. 2A and 2B are a sectional view and a plan view showing the structure of a circuit protector developed prior to the present invention. The case 1 is made of an insulating material such as plastic, and a pair of external connection terminals 2a and 2b are provided protruding from the case 1. These external connection terminals 2a and 2b are connected to conductive members 3a and 3b, respectively, within the case 1, and are connected to conductive members 3a and 3b, respectively.
One terminal of the cancellation coil 5 wound around the main magnetic circuit 4 is connected to the fixed contact 7 via the conductive leaf spring 6 to the conductive member 3b.

The main magnetic circuit 4 includes a U-shaped yoke 8 and a conductive movable member 9 made of a displaceable magnetic material that selectively connects the open ends of the yoke 8 to define a closed loop magnetic path. , a permanent magnet 10 magnetically attracting the movable member 9 to its open end via the yoke 8.
A canceling coil 5 is wound around the yoke 8. The movable member 9 has one end attached to a conductive member 12 via a conductive leaf spring 11 and is biased in a direction away from the open end of the yoke 8.
A movable contact 13 is attached to the other end, and the movable member 9
The movable contact 13 is configured to come into contact with the fixed contact 7 when the movable contact 13 is in the first position where it comes into contact with the yoke 8 . Further, one end of a reset button 14 made of an insulating material such as plastic is attached to the other end of the movable member 9, and the other end of the reset button 14 is projected through an opening 1a formed in the case 1.

On the opposite side of the movable member 9 from the yoke 8, there is an attraction magnetic circuit 15 for moving the movable member 9 to the second position and separating the movable contact 13 from the fixed contact 7.
will be established. This attraction magnetic circuit 15 is connected to the permanent magnet 1
One end of the yokes 17a, 17b is connected to both magnetic poles of the main magnetic circuit 4, and the other ends of the yokes 17a, 17b are made to face the open end of the yoke 8 of the main magnetic circuit 4, and the movable member 9 is connected to the yokes 17a, 17b. It is configured to be magnetically attracted to the other end, ie, the second position. In this example, an auxiliary attraction coil 18 is wound around one yoke 17a of the attraction magnetic circuit 15, and one terminal and the other terminal of the auxiliary attraction coil 18 are wound around the main magnetic circuit 4, respectively. Connect to the other terminal and conductive member 12. In this way, the external connection terminal 2a - the conductive member 3a - the cancellation coil 5 - the suction auxiliary coil 18
- Conductive member 12 - Leaf spring 11 - Movable member - Movable contact 13 - Fixed contact 7 - Leaf spring 6 - Conductive member 3
b- Constructs an electric path passing through the external connection terminal 2b, and when this electric path is closed, the canceling coil 5 generates a magnetic flux that resists the magnetic attraction force of the movable member 9 by the permanent magnet 10, and the attraction auxiliary coil 18 generates a magnetic flux that resists the magnetic attraction force of the movable member 9 by the permanent magnet 10. In addition to generating a magnetic flux that promotes the magnetic attraction force of the movable member 9 by the permanent magnet 16, under the rated current, these canceling coils 5 and the attraction magnetic circuit 1
5. The movable member 9 is moved to the first position by the permanent magnet 10 against the action of the suction auxiliary coil 18 and the leaf spring 11.
The structure is such that the movable contact 13 is brought into contact with the fixed contact 7 by effectively suctioning and holding it at the position.

In the above-described configuration, when an overcurrent exceeding the rated current flows in the electric circuit, the magnetomotive force of the canceling coil 5 and the attraction auxiliary coil 18 increases, and the magnetic attraction force against the movable member 9 weakens in the main magnetic circuit 4. , on the contrary, becomes stronger in the attraction magnetic circuit 15. Moreover, the magnetic circuit of the cancellation coil 5 is
A closed loop magnetic path consisting of a yoke 8 and a movable member 9. Its magnetic resistance is extremely small, and the magnetic path
Since the BH characteristics can be easily selected, a large magnetic flux is generated even if the increase in current is minute, and therefore the magnetic attraction force of the movable member 9 by the permanent magnet 10 is instantly weakened. As a result, the movable member 9 is instantaneously attracted to the yokes 17a and 17b of the attraction magnetic circuit 15 at the second position due to the biasing force of the leaf spring 11, and as a result, the movable contact 13 moves from the fixed contact 7 to As shown by curve C in FIG. 1, they are instantly separated without any variation, and the electric path is interrupted. When the electric circuit is cut off in this way, no magnetomotive force is generated in the canceling coil 5 and the auxiliary attraction coil 18, but the movable member 9 is moved by the biasing force of the leaf spring 11 and the magnetic attraction force of the permanent magnet 16. operatively held in the second position. Further, when the movable member 9 is in the second position and the electric circuit is cut off, the leaf spring 1
By manually moving the movable member 9 to the first position via the reset button 14 against the biasing force of the permanent magnet 16 and the magnetic attraction force of the permanent magnet 16, the movable member 9 is reset and the electric circuit is closed. can be achieved.

According to the circuit protector shown in FIGS. 2A and 2B, the magnetic resistance of the magnetic circuit of the canceling coil 5 and the attraction auxiliary coil 18 can be made extremely small, and the BH of the magnetic material of the yokes 8, 17a, 17b and the movable member 9 Characteristics can be used efficiently. Therefore, even if the number of turns of the canceling coil 5 and the suction auxiliary coil 18 is small, a large magnetic flux can be generated by a small increase in current, so the electric circuit can be instantaneously interrupted without any variation, thereby improving the response. performance and reliability, and
Internal impedance can also be made relatively small.

However, since the circuit protector shown in FIGS. 2A and 2B uses two coils, the cancellation coil 5 and the suction auxiliary coil 18, there are problems in that the circuit configuration becomes complicated and expensive. However, there is a problem that the internal impedance cannot be made sufficiently small.

FIG. 3 shows the configuration of essential parts of an example of the circuit protector of the present invention which solves this problem. This circuit protector is shown in Fig. 2A,
In the circuit protector shown in B, without using the attraction auxiliary coil 18, one yoke 17b connected to both magnetic poles of the permanent magnet 16 of the attraction magnetic circuit 15 is made to face the movable member 9, and the other yoke 1
7a is connected to the yoke 8 of the main magnetic circuit 4, the canceling coil 5 acts to cancel the attractive force of the movable member 9 by the permanent magnet 10, and the magnetomotive force of the canceling coil 5 is used to cancel the magnetic force of the permanent magnet 16. This is made to act as an attractive force on the movable member 9 together with the magnetic force. In this way, there is no need to use a separate suction auxiliary coil, so it is simple and inexpensive, and the internal impedance can be further reduced. Further, since the main magnetic circuit 4 and the attraction magnetic circuit 15, excluding the movable member 9, can be molded integrally, manufacturing is easy.

Note that the present invention is not limited to the above-mentioned example, and can be modified or changed in many ways. For example, the permanent magnet 10 that constitutes the main magnetic circuit 4
It is not necessary to provide both magnetic poles in contact with the opposite sides of the U-shaped yoke 8, respectively.
A gap is provided between one or both of the magnetic poles and the opposing side of the yoke 8, and a magnetic member of an appropriate thickness is inserted into the gap to adjust the magnetic attraction force of the movable member 9. You can also. Furthermore, the movable member 9 and the movable contact 13 are connected via a suitable interlocking mechanism, and the movable member 9 connects the movable contact 13 to the fixed contact 7 via this interlocking mechanism.
It can also be configured to be moved toward and away from.
Furthermore, in the above-described embodiment, the movable member 9 is biased in the direction in which the movable contact 13 is separated from the fixed contact 7 by the leaf spring 11, the attraction magnetic circuit 15, and the attraction auxiliary coil 18. The biasing means can be configured with any one of the leaf spring 11, the attraction magnetic circuit 15, and the attraction auxiliary coil 18, or can be configured with other members such as a coil spring.

Effects of the Invention As described above, according to the present invention, the movable member is connected to the first yoke connected to the first permanent magnet that magnetically attracts the movable member to the first position. a second permanent magnet that magnetically attracts the movable member to a second position and a second yoke connected to the first yoke; The movable member is spaced and opposed to the second yoke so that the magnetomotive force of the second permanent magnet and the magnetomotive force of the coil are applied to the second yoke.
When an overcurrent flows through the coil, the movable member is moved from the first position to the second position to interrupt the electric path, which is simple and inexpensive, and the magnetic resistance of the coil's magnetic circuit is extremely low. It can be made small and the BH characteristics of the magnetic material of the yoke and movable member can be efficiently utilized. 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, so the electric circuit can be interrupted instantly without variation, thereby improving responsiveness and reliability. Along with being able to
The internal impedance can also be reduced, and there will be no adverse effect on the circuit to be protected.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a comparison of operating times between a conventional circuit protector and a circuit protector according to the present invention;
FIGS. 2A and 2B are a sectional view and a plan view showing the configuration of a circuit protector developed prior to the present invention,
FIG. 3 is a diagram showing the configuration of essential parts of an example of the circuit protector of the present invention. 1... Case, 2a, 2b... External connection terminal,
3a, 3b, 12... Conductive member, 4... Main magnetic circuit, 5... Cancellation coil, 6, 11... Leaf spring, 7... Fixed contact, 8, 17a, 17b... Yoke, 9... ...Movable member, 10, 16...Permanent magnet, 13...Movable contact, 14...Reset button, 1
5... Attraction magnetic circuit, 18... Attraction auxiliary coil.

Claims (1)

[Claims] 1. A movable member made of a magnetic material that can be moved to first and second positions for closing and interrupting an electric circuit, and a first movable member that magnetically attracts the movable member to the first position. a permanent magnet; a first yoke that abuts the movable member at a first position of the movable member to define a closed loop magnetic path; and a permanent magnet that is wound around the yoke and passes through the movable member. a coil that generates a magnetic flux that resists the magnetic attraction force of the movable member by a magnet; a second permanent magnet that magnetically attracts the movable member to a second position; the second permanent magnet and the second permanent magnet; a second yoke connected to the first yoke and facing away from the movable member at the first position of the movable member; A circuit characterized in that the movable member is moved from a first position to a second position to interrupt the electric path when an overcurrent flows through the coil by applying a magnetomotive force. protector.