JP2015022789A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that heating due to contact resistance may affect the operation of a thermally activated tripping device, and when employing a system for lowering the contact resistance by increasing a point contact pressure in order to suppress the influence, the point contact pressure is applied reversely to the breaking direction of a movable element, thus inhibiting the breaking operation.SOLUTION: A circuit breaker includes a second contactor 2 having a second contact 21 provided detachably for a first contact 11 provided in a first contactor 1, and a make and break mechanism part, including a thermally activated tripping device responding to an overcurrent, that turns one of the first or second contactor so as to break the first and second contact when breaking the circuit. The circuit breaker is further provided with a contact pressure part 12, formed such that the normal direction A1 to the contact surface of the first and second contact and the contact movement direction B for one of the contacts when starting the circuit breaking operation cross each other, that applies a point contact pressure in the normal direction to the contact surface thereof.

Description

  The present invention relates to a circuit breaker having a thermal trip device.

  A conventional circuit breaker includes, for example, a load side connection terminal for connecting a device to be interrupted, a contact for energization and disconnection, and an opening / closing mechanism thereof, as disclosed in Patent Document 1, for example. As shown in Patent Document 2, a thermal trip device for driving an opening / closing mechanism and a power supply side connection terminal for connecting a power supply and the like are provided. An electric circuit connected to the load side connection terminal is formed from the power supply side connection terminal via a thermal trip device / contact. This electric circuit is formed of an alloy such as copper or silver having a sufficiently low electric resistance so as not to consume unnecessary energy in the circuit breaker. However, the electric circuit inside the thermal tripping mechanism needs to bend the bimetal by generating Joule heat, and thus is formed of a metal having a relatively high resistance. The open / close mechanism is configured to reduce the contact resistance when the contact is in contact, so that a certain pressure is applied to the contact during energization, and the contact is quickly released during the shut-off operation. Yes.

JP 2001-229803 A ([0002] to [0023], FIGS. 12 and 14) Japanese Patent No. 4333029 ([0002] to [0006], FIG. 6)

  In the conventional circuit breaker as described above, the Joule heat generated at the contact contact resistance and the electric circuit and the Joule heat generated at the thermal trip part are generated during energization, but the rated current to be interrupted increases. Accordingly, in order to adjust the amount of heat generated in the thermal trip portion, it is necessary to reduce the electrical resistance of the thermal trip portion, and as a result, it approaches the Joule heat generated by the contact contact resistance. Since the heat generated at the contact is transmitted through the electrical path and conducted to the thermal tripping part, as the rated current increases, the influence of the heat generated at the contact increases on the thermal tripping part. Adjustment of the tripping portion becomes difficult, and as a result, there is a problem that the adjustment time of the thermal tripping portion is extended and productivity is not increased. In order to reduce the contact resistance, it is necessary to increase the contact pressure, but the contact pressure application direction and the mover movement direction during the breaking operation are opposite. For this reason, the contact pressure could not be increased beyond a certain level.

  The present invention has been made to solve the above-described problems, and can obtain a circuit breaker capable of increasing contact contact pressure and reducing contact contact resistance without impeding the shut-off operation. The purpose is that.

  The circuit breaker according to the present invention corresponds to an overcurrent, and a second contact having a second contact provided so as to be able to contact and separate with respect to the first contact provided on the first contact. A circuit breaker provided with a thermal trip device and having an opening / closing mechanism for rotating one of the first and second contacts so that the first and second contacts are opened when the circuit is interrupted The normal direction of the contact contact surface between the first contact and the second contact and the contact movement direction of one of the contacts at the start of the circuit breaking operation intersect with each other, and A contact pressure portion for applying contact contact pressure in the normal direction of the contact contact surface is provided.

  According to the present invention, since the contact moving direction at the start of the circuit breaking operation and the normal direction of the contact contact surface intersect each other, the force applied in each direction can be set independently. Therefore, the contact contact pressure can be increased and the contact contact resistance can be reduced without increasing the contact release blocking force in the rotating direction of the contact.

The side view which shows typically the switching part of the circuit breaker by Embodiment 1 of this invention. The top view which shows typically the switching part of the circuit breaker by Embodiment 1 of this invention. FIG. 3 is an enlarged side view for explaining the force applied to the vicinity of the contact point when energized in the opening / closing section shown in FIG. 1 and its direction. FIG. 3 is an enlarged side view for explaining the force applied to the vicinity of the contact point when energized in the opening / closing section shown in FIG. 1 and its direction. The side view which shows typically the switching part of the circuit breaker by Embodiment 2 of this invention. The top view which shows typically the switching part of the circuit breaker by Embodiment 2 of this invention. FIG. 6 is an enlarged side view for explaining the force applied to the vicinity of the contact point during energization in the opening and closing unit shown in FIG. 5 and the direction thereof. FIG. 6 is an enlarged side view for explaining the force applied to the vicinity of the contact point during energization in the opening and closing unit shown in FIG. 5 and the direction thereof. The side view which shows typically the switching part of the circuit breaker by Embodiment 3 of this invention. The top view which shows typically the switching part of the circuit breaker by Embodiment 3 of this invention.

Embodiment 1 FIG.
1 is a side view schematically showing a switching unit of a circuit breaker according to Embodiment 1 of the present invention, and FIG. 2 is a top view schematically showing the switching unit of the circuit breaker according to Embodiment 1 of the present invention. 3 and 4 are enlarged side views for explaining the force applied to the vicinity of the contact point during energization in the opening / closing section shown in FIG. 1 and the direction thereof. In the figure, the circuit breaker is formed integrally with the terminal portion 1a, and has a fixed contact 1 provided with a fixed contact 11, and a movable contact 21 provided so as to be able to contact with and separate from the fixed contact 11. The movable contact 2 provided to rotate about the axis O, the fixed spring 3 for suppressing the swing of the movable contact 2 in the closed state, and the tip of the movable contact 2 are opposed to each other. And an arc extinguishing grid 4 for taking in and cooling an arc generated between the fixed contact 11 and the movable contact 21 at the time of opening, and the like. In this document, the fixed contact 11 corresponds to the first contact, the fixed contact 1 corresponds to the first contact, the movable contact 21 corresponds to the second contact, and the movable contact 2 corresponds to the second contact. The case will be described.

  In order to minimize power loss and heat generation inside the circuit breaker when energized, the fixed contact 1 and the movable contact 2 in the energization path are made of a material having a low resistivity such as copper or an alloy thereof, for example. However, since the movable contact 21 and the fixed contact 11 are kept in contact with each other, they always have a contact resistance generated on the contact surface. Other parts on the electric circuit can reduce heat generation by using materials with low electrical resistance, but Joule heat generated by contact contact resistance may be comparable to the amount of heat generated by the thermal trip device, In this case, the heat generated by the contact contact resistance may be conducted to the thermal trip device and affect the thermal trip operation. For this reason, it is necessary to reduce the contact resistance as much as possible. The contact contact resistance is affected by the contact material resistance, the shape of the contact contact portion, and the contact contact force between the movable contact 21 and the fixed contact 11. In order to reduce the contact contact resistance, it is necessary to use, for example, a silver alloy having a low resistivity as the contact material and to take a contact contact force of a certain level or more between the contacts.

  The fixed contact 11 is fixed to an end portion of the fixed contact 1 opposite to the terminal portion 1a to a contact pressure portion 12 that is bent so as to rise upward in the figure. The contact portion 12 is formed from a bent piece formed so that the end of the stationary contact 1 opposite to the terminal portion 1a of the current flow portion is bent in the direction of the arc extinguishing grid 4 or the arc space. Thus, the fixed contact 11 is held in the direction of the movable contact 21 at the time of closing by the fixed elastic force of the bent piece while holding the fixed contact 11 and constituting the energization path. It has a function of applying contact contact pressure in the line direction A1. The normal direction A1 on the contact contact surface between the fixed contact 11 and the movable contact 21 is set so as to intersect the direction perpendicular to the contact moving direction B at the start of the circuit breaking operation (contact release / contact operation), and It is comprised so that it may become a direction orthogonal to the extending direction C of the axis | shaft O when the movable contact 2 is rotated. Further, when the contact is closed, the stopper 5 for restricting the movable contact 2 from rotating in the clockwise direction from the substantially horizontal position shown in FIG. It is installed at an appropriate position that does not affect the blocking characteristics.

  The electric path at the time of energization is movable contact from the terminal part 1a which is a power source side connection terminal of the fixed contact 1 via the contact pressure part 12 and via the contact contact surface constituted by the fixed contact 11 and the movable contact 21. It passes through the child 2 and is configured to communicate with a thermal tripping device (not shown) to a load side terminal. The coiled fixed spring 3 is opened when the movable contact 2 is opened by an electromagnetic repulsive force in the opening direction acting on the movable contact 2 by a load current in a closed state, mechanical vibration from the outside, or the like. In the first embodiment, the movement of the movable contact 2 is restrained against the counterclockwise rotation, and the biasing force is exerted against the clockwise rotation. A gap is formed between the action point 3 a of the fixed spring 3 and the upper surface of the movable contact 2 so that the movement does not work.

  As shown in an exaggerated shape in FIG. 2, the fixed spring 3 is engaged at both ends with the support member 20 of the movable contact 2, and the action point 3 a is an intermediate portion of the coiled fixed spring 3. It is formed to be pulled out and extended. When the fixed spring 3 forms a gap between the action point 3a and the upper surface of the movable contact 2 in the closed state, a predetermined force is stored in the support member 20 as illustrated in FIG. A locking claw (not shown) that restricts clockwise rotation may be protruded, and the base (the part close to the coil) side of the action point 3a may be locked to the locking claw. Each member shown in FIG. 1 is housed in a housing (not shown). In addition to the above-described members, the movable contact 2 is placed around the axis O when the circuit is interrupted. It also houses an opening and closing mechanism that includes a main spring that rotates clockwise, a link mechanism, and a thermal trip device that detects the overcurrent using a bimetal and operates the opening and closing mechanism. Since it is the same as the conventional ones shown in Patent Documents 1 and 2, etc., illustration and description thereof are omitted.

  Next, the operation of the first embodiment configured as described above will be described with reference to FIGS. During energization, a contact contact force D <b> 1 is applied by the contact pressure unit 12 in order to reduce the contact contact resistance between the movable contact 21 and the fixed contact 11. The contact contact surface is also subjected to an inter-contact frictional force E1 corresponding to the contact contact force D1, and the contact is inadvertently caused by vibration applied to the circuit breaker and electromagnetic force received by the movable contact 2 from the fixed contact 1. The position of the contact in the vertical direction in the figure is fixed in a dynamic balance with the contact release prevention force F and the contact release force G that are forces for releasing the contact. In general, it is known that the electrical resistance of the contact point contact portion is inversely proportional to the 1/3 power of the contact point contact pressure. Therefore, the contact resistance decreases as the contact contact pressure increases.

  The contact friction force E1 that balances the contact release prevention force F or the contact release force G is a value obtained by multiplying the contact contact force D1 by the coefficient of static friction between the contacts. In the conventional example, the contact release preventing force F is set to 6 to 10 N so as not to disturb the blocking operation. However, the first embodiment is set to generate the friction force E1 between the contacts equivalent to this. Yes. In the first embodiment, since the friction coefficient is 0.3 to 0.5, which is the same as that of the silver electrode, the maximum contact contact force D1 is 1 / 0.3 to 1/0. 5, that is, 3.3 times to 2 times can be applied. As a result, the contact contact resistance can be reduced by up to 30%, so that the contact heating value can be reduced by 30%. As a result, the influence of the heat generated at the contact on the thermal tripping mechanism can be reduced.

  In the contact release operation, the contact release force G is amplified by a main spring (not shown). The main spring is arranged to quickly move the movable contact 2 in the direction of releasing the contact during the interruption operation, and operates when the interruption is performed. The main spring moves the movable contact 2 against the frictional force E1 between the contacts. However, if the frictional force E1 between the contacts conforms to the first embodiment, the main spring is located between the contacts when the contacts are released. Since the force that must be moved against the frictional force E1 is the same as that in the conventional example, the release operation is not hindered.

As described above, according to the first embodiment, the normal direction A1 of the contact contact surface between the fixed contact 11 and the movable contact 21 and the contact moving direction B at the start of the circuit breaking operation intersect each other in an orthogonal direction. Since the contact pressure portion 12 that provides the contact contact force in the normal direction A1 of the contact contact surface is provided, the force applied in the contact movement direction B of the movable contact 2 at the start of the breaking operation Since the force applied in the normal direction A1 of the contact contact surface can be set independently, the contact contact pressure can be increased without increasing the contact release preventing force F in the operation direction of the movable contact 2. it can. As a result, it is possible to obtain a remarkable effect that the contact contact resistance can be reduced without hindering the interruption operation.
Further, as a result of reducing the contact contact resistance, the influence of the heat generated at the contact point on the thermal tripping portion can be reduced, the adjustment time of the thermal tripping mechanism can be shortened, and the productivity can be improved. In addition, since the normal direction A1 of the contact contact surface is substantially perpendicular to the axis O of the movable contact 2, the contact release mechanism design is not greatly changed, and the interruption operation is not hindered without being interrupted. Can be reduced.

Embodiment 2. FIG.
FIG. 5 is a side view schematically showing the switching part of the circuit breaker according to Embodiment 2 of the present invention, and FIG. 6 is a top view schematically showing the switching part of the circuit breaker according to Embodiment 2 of the present invention. 7 and 8 are enlarged side views for explaining the force applied to the vicinity of the contact when energizing the opening / closing section shown in FIG. 5 and the direction thereof. In the second embodiment, the normal direction A2 of the contact contact surface is set to be slightly inclined according to the spring constant of the contact pressure portion 12 with a larger spring constant than that of the first embodiment. Is. In the figure, the contact pressure part 12 having spring elasticity consisting of a bent piece in the fixed contact 1 is such that the upper end side in the figure has an angle larger in the opening direction with respect to the contact movement direction B at the start of opening. In the example of FIG. 5, the fixed contact 11 is inclined by about 10 °, and the fixed contact 11 having the same shape as that of the first embodiment is similarly inclined corresponding to the inclination angle of the contact pressure portion 12. The inclination angle is not particularly limited, and may be further inclined, for example, as long as the contact movement direction B and the normal direction A2 intersect each other.

  The normal direction A2 of the contact contact surface between the fixed contact 11 and the movable contact 21 is formed to be slightly larger than a right angle with respect to the contact moving direction B at the start of the circuit breaking operation. The normal direction A2 is provided in a direction orthogonal to the extending direction C of the axis O in which the movable contact 2 is rotated. Further, unlike the first embodiment, the fixed spring 3A is engaged with the upper edge of the movable contact 2 even when the movable contact 21 is in contact with the fixed contact 11, and the operating point of the fixed spring 3A is The contact pressure portion 3b is configured to urge the movable contact 2 in the clockwise direction so that a predetermined contact contact pressure is generated in cooperation with the contact pressure portion 12. It should be noted that the stopper 5 shown in FIG. 1 is not necessary and not installed in the second embodiment. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  In the second embodiment configured as described above, as shown in FIGS. 7 and 8, the contact pressure portion 12 and the contact pressure portion 3b of the fixed spring 3A cooperate to apply the contact contact force D2 to the contact contact portion. Giving. Further, although the contact contact resistance E2 itself is slightly increased as compared with the first embodiment, even when the contact wear due to the contact release operation occurs and the contact thickness changes in the direction of decreasing the contact thickness, for example, The fixed contact 11 falls to the movable contact 21 side together with the contact pressure portion 12 as shown by the broken line in FIG. 5, and the component force in the contact moving direction B of the contact contact force D2 is shown in FIGS. As shown by the broken line, it is possible to prevent the contact releasing force G from becoming a blocking force.

  Further, when the contact connection operation is performed by the contact pressure portion 3b of the fixed spring 3A, the component force of the contact contact force D2 by the contact pressure portion 12 becomes the reaction force of the contact release preventing force F by the fixed spring 3A. In addition to the frictional force E2 between the contacts, the position of the movable contact 2 can be fixed by the balance between the fixed spring 3A and the contact pressure portion 12 during the contact connection operation. The position can be determined.

Embodiment 3 FIG.
9 is a side view schematically showing an opening / closing part of a circuit breaker according to Embodiment 3 of the present invention, and FIG. 10 is a top view schematically showing the opening / closing part shown in FIG. In the figure, the movable contact 21 is disposed on one side surface of the distal end portion, not on the distal end surface of the movable contact 2 in the rotational radial direction. Then, the fixed contact 11 is, for example, in a position corresponding to a state rotated 90 ° counterclockwise from the position of FIG. 6 according to the second embodiment so as to face the movable contact 21. In the same manner as above, it is fixed to the pressure contact portion 12 provided so as to stand up obliquely upward. In addition, the inclination of the contact pressure part 12 is the normal direction in the contact contact surface of the fixed contact 11 and the movable contact 21 and the contact movement at the start of the circuit breaking operation (contact release / contact operation) as in the first embodiment. You may comprise so that the direction B may mutually cross | intersect an orthogonal direction.

  In the third embodiment, the contact movement direction B at the start of the circuit breaking operation and the normal direction A3 of the contact contact surface are substantially perpendicular to each other as in the first or second embodiment. The movable contact 21 and the fixed contact 11 are arranged so that the extending direction C of the axis O on which the contact 2 is rotated and the normal direction A3 of the contact contact surface are substantially parallel to each other. The angle differs from the case of 2 by 90 °. Further, the fixed spring 3B has a function similar to that of the first embodiment or the second embodiment that applies the contact release preventing force F3 so that the contact is not released to the movable contact 2, and from the asymmetric part of the fixed spring 3B. The contact pressure portion 3c has a function of urging the movable contact 2 toward the contact pressure portion 12 to generate contact contact pressure in cooperation with the contact pressure portion 12.

  When energized, the contact contact force D3 (shown in FIG. 10) that determines the contact contact resistance of the contact spring 12 and the fixed spring 3 for applying a force in the direction of pressing the movable contact 2 toward the fixed contact 11 side. The contact portion 3c is formed so as to be balanced. The electric path at the time of energization passes through the movable contact 2 through the contact contact portion composed of the fixed contact 11 and the movable contact 21 from the terminal portion 1a on the power source side of the fixed contact 1 through the contact pressure portion 12. A thermal trip mechanism (not shown) is connected to a load side terminal. Other configurations are the same as those in the first or second embodiment.

In the third embodiment configured as described above, as in the first or second embodiment, the contact contact force D3 can be increased as compared with the conventional example. Therefore, the contact contact resistance can be reduced, and the contact heat generation amount can be reduced. As a result, the influence on the thermal tripping device can be reduced.
Further, since the direction of the contact contact force D3 and the operation direction at the time of releasing the contact of the movable contact 2 are substantially orthogonal, the force of the fixed spring 3B for fixing the movable contact 2 to the contact contact position, The force generated by the contact pressure portion 3c of the fixed spring 3B constituting the contact contact force D3 can be changed independently. For this reason, since the degree of freedom increases in the selection of the spring constant, an effect of improving the component design margin can be obtained.
Further, since the normal direction D3 of the contact surface is formed substantially parallel to the axis O of the movable contact 2, the contact pressure by the contact portion 12 and the contact release preventing force F3 can be set independently. The effect that design freedom increases is also acquired.

It should be noted that within the scope of the present invention, a part or all of each embodiment can be freely combined, or each embodiment can be appropriately modified or omitted. For example,
1) In Embodiments 1 and 2, the pressure contact portion 12 is configured on the fixed contact 11 side, but an element corresponding to the pressure contact portion 12 is interposed between the movable contact 21 at the distal end portion of the movable contact 2. Even if configured in this way, the same effect can be obtained.
2) In Embodiment 3, the contact contact force D3 is generated by the balance of the force of the contact pressure part 12 and the contact pressure part 3c of the fixed spring 3B, but the contact pressure of the contact pressure part 12 or the fixed spring 3B Only one of the portions 3c can generate contact contact pressure.
3) In Embodiments 1 to 3 and 1) and 2), the contact pressure portion 12 is directly connected to the fixed contact 11, but it does not necessarily have to be fixed directly. A similar effect can be obtained by providing a spring that applies a contact pressure independently of the child 1 and pressing the stationary contact 1 with this spring.
4) In Embodiments 1 to 3 and 1) to 3), the fixed spring 3 is a coil spring, and the contact pressure portion 12 that functions as a contact pressure adjusting spring is a leaf spring. However, it is not always necessary to do so. For example, a coil spring or a leaf spring can be used. Further, the spring can be substituted with another elastic material such as a heat-resistant resin.
5) In Embodiments 1 to 3 and 1) to 4), the case where the first contact is the fixed contact 11 attached to the fixed contact 1 has been described. However, the present invention is not limited thereto. Even if the first contact point and the second contact point that are slidably opposed to each other are rotated, the normal direction of the contact contact surface and the circuit breaking operation Since the operation direction of the second contact point at the start can be formed substantially vertically and the contact pressure part for applying the contact contact force in the normal direction of the contact contact surface can be provided. The same effects as 1 to 3 and 1) to 3) can be obtained.
In addition, various modifications and changes can be made within the scope of the present invention, such as the shape and structure of the fixed contact 1, the movable contact 2, or the fixed spring 3 (3A, 3B), the construction method of the contact pressure portion 12, and the like. is there.

  DESCRIPTION OF SYMBOLS 1 Fixed contact, 1a Terminal part, 11 Fixed contact, 12 Contact pressure part, 2 Movable contact, 20 Support member, 21 Movable contact, 3, 3A, 3B Fixed spring, 3a Action point, 3b, 3c Contact pressure part, 4 Arc extinguishing grid, 5 stopper, A1, A2, A3 Normal direction, B contact moving direction, C extending direction, D1, D2, D3 contact contact force, E1, E2 contact friction force, F contact release prevention force, G Contact release force, O axis.

Claims (5)

  A second contact having a second contact provided detachably with respect to the first contact provided on the first contact, and a thermal trip device corresponding to overcurrent; A circuit breaker comprising an opening / closing mechanism for rotating one of the first and second contacts so that the first and second contacts are opened when the circuit is interrupted. Of the contact point between the first contact point and the second contact point, and the contact moving direction of one of the contact points at the start of the circuit breaking operation intersect with each other, and the contact point in the normal direction of the contact point contact surface A circuit breaker comprising a contact pressure portion for applying a contact pressure.   The contact pressure portion is formed of a bent piece formed by bending a current passing portion in one of the first contactor and the second contactor. The circuit breaker according to claim 1, wherein one of the contacts is provided.   The extending direction of the bent piece is open with respect to the tangential direction in the closed state in the rotation trajectory of the contact provided on the other contact of the first contact and the second contact. The circuit breaker according to claim 2, wherein the circuit breaker is inclined so that an angle increases in a polar direction.   The normal direction of the contact contact surface and the direction of the rotation axis of one of the first contactor and the second contactor are formed to be orthogonal to each other. The circuit breaker according to any one of claims 1 to 3.   The normal direction of the contact point contact surface and the direction of the rotation axis of the first contactor and the second contactor are formed so as to be parallel to each other. The circuit breaker according to claim 3.

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