JP6432906B2 - Thermal trip device for circuit breaker - Google Patents

Description

  The present invention relates to a thermal trip device for a circuit breaker that cuts off a current using a curved bimetal.

  For example, when an overcurrent such as a short circuit current flows in the current path between the power supply side terminal and the load side terminal, the heated bimetal is bent, and the bending deformation of the bimetal acts on the opening / closing mechanism to 2. Description of the Related Art A thermal trip device for a circuit breaker that cuts off a current by opening a pole is generally known.

  Here, as a method of heating the bimetal, there is a direct heating type in which a current flows directly through the bimetal to bend and deform, and a heater that generates heat due to the flow of current is provided. There is a direct heat type that combines the direct heat type and the direct heat type (for example, see Patent Document 1).

  Specifically, as shown in FIG. 1 of Patent Document 1, in the thermal trip device for a direct heat circuit breaker, the upper part of the bimetal is connected to the circuit by a screw or the like via a flexible conductor. The load side terminal fixed to the case of the circuit breaker is connected, and the lower part of the bimetal is connected to the movable contact side. In this device, before the current is interrupted, the load side terminal, the bimetal, and the movable contact are energized, and each component generates heat due to Joule heat, and the temperature rises. At this time, the bimetal is bent due to a difference in linear expansion coefficient between two or more metal plates constituting the bimetal as the temperature rises.

  Further, as shown in FIG. 2 of Patent Document 1, in the thermal trip device of the indirectly heated circuit breaker, the lower part of the bimetal is thermally connected to the bimetal, and the load side terminal and The heater is electrically connected to the power supply side terminal. In this apparatus, before the current is interrupted, the heater generates heat due to Joule heat and the temperature rises. At this time, the temperature of the bimetal rises due to the heat received from the heater and bends.

  Here, for example, in the thermal trip device of the indirectly heated circuit breaker, since the bimetal is composed of a single member, the heat generated by the heater during overcurrent energization is the tip side of the bimetal. It takes time to get to. This may cause a time delay in the thermal tripping operation.

  Therefore, in order to prevent a time delay in the thermal tripping operation during overcurrent energization, thermal tripping of a circuit breaker using a short bimetal and an extension plate attached to the tip of the bimetal as a curved member. A removal device has been proposed (see, for example, Patent Document 2).

  In the thermal trip device for a circuit breaker described in Patent Document 2, a base end portion is fixed to a heater between a heater provided in a current path and a trip bar, and a tip end portion extends to the trip bar side. The bimetal is fixed to the tip of the bimetal and has an extension plate whose free end is located near the trip bar. Overcurrent flows through the current path and the heater generates heat. The free end of the extension plate that is displaced along with the bending deformation of the bimetal distal end is in contact with the trip bar.

  In the thermal trip device of the circuit breaker, when the rated current is energized, the current flowing in the circuit is not interrupted, and when the current flowing in the circuit exceeds the rated current, for example, during overcurrent energization, It is required to cut off the current flowing in the circuit within a predetermined time for each current value of the flowing current. Further, since the curved member needs to be arranged at a position where the curved curved member does not come into contact with the trip bar when the rated current is energized, the bending amount of the curved member when the rated current is energized is required to be substantially unchanged. The

  Here, according to the thermal trip device for a circuit breaker described in Patent Document 2, by adjusting the length of the bimetal and the extension plate that constitute the bending member, the bending member is configured only by the bimetal. It is possible to adjust the interruption time until the circuit current is interrupted for each current value, which could not be realized.

JP-A-4-19938 JP 2010-218765 A

  The thermal tripping device for a circuit breaker varies depending on the application of the object, and the breaking time required when overcurrent is applied. Therefore, in the vicinity of the rated current that determines the initial positions of the bimetal and the trip bar, it is necessary to adjust the cut-off time during overcurrent energization while making the bending amount of the bending member equal.

  However, in the thermal trip device for a circuit breaker described in Patent Document 2 that adjusts the lengths of the bimetal and the extension plate, the bending amount and the breaking time of the bending member when the rated current is applied are kept the same. There is a problem that the interruption time during current application cannot be adjusted. Such a problem occurs not only in the thermal tripping device of the indirectly heated circuit breaker but also in the thermal tripping device of the directly heated type or directly heated circuit breaker.

  The present invention has been made to solve the above-described problems, and the amount of bending of the bending member and the interruption time during energization of the rated current remain the same, depending on the use of the object, during overcurrent energization. It is an object of the present invention to obtain a thermal trip device for a circuit breaker capable of adjusting the breaking time to a desired time.

A thermal trip device for a circuit breaker according to the present invention is a thermal trip device for a circuit breaker that performs an opening operation of the switching mechanism by contacting a trip bar of the switching mechanism, with one end fixed. A curved member that is heated in response to an overcurrent flowing in the current path of the circuit breaker and whose other end can be displaced toward the trip bar, and the curved member is directly in response to the overcurrent. A first bimetal that is heated, and a second bimetal that is provided in a thickness direction of the first bimetal and in a bending direction of the first bimetal and suppresses the bending of the first bimetal when energized with an overcurrent. An intermediate member made of an insulating material having a constant thickness is provided between the first bimetal and the second bimetal .
Also, a thermal trip device for a circuit breaker that performs an opening operation of the opening / closing mechanism by contacting a trip bar of the opening / closing mechanism, one end of which is fixed, and flows in a current path of the circuit breaker A curved member that is heated in response to an overcurrent and has a second end that is displaceable toward the trip bar, the curved member comprising: a first bimetal that is directly heated in response to the overcurrent; and the first bimetal A second bimetal provided in a direction opposite to the bending direction of the first bimetal in the thickness direction, and the bending amount of the second bimetal alone is the same as that of the first bimetal alone at the same rising temperature. An intermediate member made of an insulating material having a constant thickness is provided between the first bimetal and the second bimetal, which is larger than the bending amount.

According to the thermal trip device for a circuit breaker according to the present invention, it is possible to suppress the diversion from the first bimetal to the second bimetal and to transmit heat equally from the first bimetal to the second bimetal.

It is sectional drawing which shows the circuit breaker provided with the thermal trip apparatus which concerns on this invention. It is a block diagram which shows the thermal trip apparatus of a general indirectly heated circuit breaker. It is a block diagram which shows the thermal trip apparatus of the circuit breaker which concerns on Embodiment 1 of this invention. (A)-(c) is a block diagram which shows the modification of the thermal trip device of the circuit breaker which concerns on Embodiment 1 of this invention. (A)-(c) is a block diagram which shows the modification of the thermal trip device of the circuit breaker which concerns on Embodiment 1 of this invention. It is a block diagram which shows the modification of the thermal trip apparatus of the circuit breaker which concerns on Embodiment 1 of this invention. It is a block diagram which shows the thermal trip apparatus of the circuit breaker which concerns on Embodiment 2 of this invention. It is a block diagram which shows the thermal trip apparatus of the circuit breaker which concerns on Embodiment 3 of this invention. It is a block diagram which shows the thermal trip apparatus of the circuit breaker which concerns on Embodiment 4 of this invention.

  Hereinafter, preferred embodiments of a thermal trip device for a circuit breaker according to the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts will be described with the same reference numerals. .

  In addition, this invention is a direct heating method in which the bimetal is directly energized, a direct heating method in which the bimetal is not directly energized and receives heat from a heater attached to the base of the bimetal, and a combination of the direct heating method and the indirectly heating method. The present invention can be applied to any thermal trip device for any circuit breaker of direct heat type.

  First, prior to the description of the embodiment, referring to FIG. 1 and FIG. 2, a circuit breaker provided with a thermal trip device and a thermal trip of a side-heat and direct-heat type circuit breaker. A general structure of the apparatus will be described.

  FIG. 1 is a cross-sectional view showing a circuit breaker provided with a thermal trip device according to the present invention. In FIG. 1, this circuit breaker includes a stator 1, a mover 2 arranged at a distance from the stator 1, an open / close mechanism 3 that cuts off current by rotating the mover 2, and an open / close A trip bar 4 provided in the mechanism 3 and a thermal trip device 10 for operating the opening / closing mechanism 3 are housed in a case 5.

  The stator 1 is provided with a stationary contact 1a. The movable contact 2 is provided with a movable contact 2a so as to face the fixed contact 1a. The movable contact 2 a comes into contact with the fixed contact 1 a when the movable member 2 is rotated by the opening / closing mechanism 3. When the movable contact 2a and the fixed contact 1a are in contact with each other, the current is flowing in the circuit. FIG. 1 shows a state in which the movable contact 2a is separated from the fixed contact 1a, that is, a cut-off state in which current is cut off.

  The opening / closing mechanism 3 has a handle 3a and a movable arm 3b. Since the opening / closing mechanism 3 is not a main part of the present invention, a detailed illustration thereof is omitted, but for example, a structure in which a link mechanism and a spring are combined. When the handle 3a is rotated counterclockwise, the movable arm 3b is rotated, and accordingly, the movable contact 2a comes into contact with the fixed contact 1a to be energized.

  FIG. 2 is a configuration diagram showing a thermal trip device of a general indirectly heated circuit breaker. In FIG. 2, this thermal tripping device 10 has a base of a bimetal 21 in which two metal plates having different linear expansion coefficients are bonded to each other in the thickness direction of the metal plate. The member is configured to be attached with a fastener such as a rivet 25. Instead of the bimetal 21, a trimetal obtained by bonding three or more metal plates having different linear expansion coefficients in the thickness direction may be used. Hereinafter, bimetal or trimetal is collectively referred to as bimetal.

  Here, the bimetal 21 is not directly energized, and an overcurrent flows through the heater 24 attached to the base of the bimetal 21, whereby the heater 24 generates heat due to Joule heat. Further, the heat generated by the heater 24 is transmitted to the bimetal 21, so that the bimetal 21 rises in temperature and is bent toward the member having a small linear expansion coefficient.

  Of the two metal plates constituting the bimetal 21, for example, a copper alloy in which nickel, chromium, zinc or the like is combined with copper, or alloy steel is used for the metal plate on the high expansion side. Among the two metal plates constituting the bimetal, alloy steel having a lower linear expansion coefficient than the metal plate on the high expansion side is used for the metal plate on the low expansion side.

  Further, the amount of heat generated in the heater 24 increases according to the square of the current and the first power of the resistance of the heater 24. That is, as the energization current increases, the amount of heat generation increases with the square of the current value, the electrical resistance increases with the temperature rise of the heater 24 itself, and the temperature rise of the heater 24 increases.

  As the rising temperature of the heater 24 increases, the amount of heat transferred to the bimetal 21 also increases, and as the rising temperature of the bimetal 21 increases, the amount of bending also increases. At this time, when the curved bimetal 21 pushes the trip bar 4, the opening / closing mechanism 3 operates, and the movable contact 2a is separated from the fixed contact 1a. Thereby, the electric current in a circuit is interrupted | blocked.

  Therefore, by adjusting the initial positions of the bimetal 21 and the trip bar 4, the presence / absence of a current corporation and the time until interruption are adjusted for each current value. Specifically, it is necessary to design the bending amount of the bimetal 21 to be smaller than the initial distance between the trip bar 4 and the bimetal 21 when the rated current that should not be interrupted is energized. In addition, when an overcurrent is applied to interrupt current, it is necessary to design the bending amount of the bimetal 21 to be larger than the initial distance between the trip bar 4 and the bimetal 21.

  The bending amount of the bimetal 21 can be calculated by the following equation (1). Where D is the bimetal bending amount [mm], K is the bending coefficient [1 / K], ΔT is the rising temperature [K], L beam length [mm], and t is the thickness [mm]. is there.

  According to the above equation (1), the bending amount of the bimetal 21 is proportional to the bending coefficient determined from each metal constituting the bimetal 21 and the first power of the rising temperature of the bimetal 21 and the square of the length of the beam. , Which is inversely proportional to the first power of the thickness. Here, since the allowable temperature of the heater 24 is determined by the material or the like, it is possible to assume a case where the rising temperature of the heater 24 is constant by making the shape and resistance of the heater 24 the same. Thereby, the rising temperature of the bimetal 21 can be determined from the thermal conductivity, heat capacity (specific heat / density) and shape of the bimetal 21.

  In the circuit breaker, when energizing around the rated current, the interruption time required for the thermal trip device is long, so there is sufficient time for the heat generated in the heater 24 to be transmitted to the bimetal 21. Therefore, the temperature of the bimetal 21 hardly generates a temperature difference between the root in contact with the heater 24 and the free end.

  On the other hand, at the time of overcurrent energization, the time until the current is cut off is set to be very short in order to protect the equipment on the load side where the heat generation amount increases. Further, when overcurrent is applied, overcurrent is also applied to the inside of the circuit breaker, so that the temperature of the components of the circuit breaker including the heater 24 rises instantaneously. Accordingly, the temperature of the bimetal 21 in contact with the heater 24 rises according to the thermal resistance and thermal resistance of the used material.

  However, since it takes time for the bimetal 21 to rise in temperature, there is a difference in the rise temperature between the tip that is not in contact with the root that is in contact with the heater 24, and the tip of the bimetal 21 is almost at the time of overcurrent energization. The amount of bending of the entire bimetal 21 is determined by the temperature rise at the base in contact with the heater 24 without the temperature rise.

  Further, the amount of bending of the bimetal 21 can be examined in the same way as the bending of the beam, and when the base of the bimetal 21 is bent, the tip is also bent according to the bending of the base. Here, as it goes to the tip, the deflection angle of the bimetal 21 increases, and the total amount of bending is determined.

  Therefore, as described in Patent Document 2, when there is an extension plate at the tip of the bimetal, compared to the case where there is no extension plate and the length is short, the amount of bending until the bimetal is both is the same, Since the extension plate attached to the upper part of the bimetal also bends due to the bending of the bimetal, the total amount of bending can be increased.

  In addition, the amount of bending increases compared to the case where the tip is made of an extension plate by providing a structure composed only of the bimetal without providing an extension plate at the tip of the bimetal, but the bimetal is, for example, a metal extension plate Compared to the cost. In addition, in the case of using only bimetal, since the bending amount and the cut-off time are uniquely determined from the vicinity of the rated current to the vicinity of the overcurrent, it is not possible to adjust the time until the cut-off with respect to the energized current that differs for each application.

  Next, a thermal trip device for a direct heat circuit breaker will be described. The thermal trip device for a direct-heat circuit breaker is a system in which the bimetal itself generates heat due to Joule heat and the temperature rises by installing the bimetal in the current path.

  In this method, by using a member having a large electric resistance for the bimetal itself, it is not necessary to increase the temperature by transferring heat from other members as in the indirectly heated type, and a short interruption is required during overcurrent energization. Even under conditions, the current can be cut off with good responsiveness.

  Further, a heater with a high calorific value or a member with a large thermal resistance may be installed above and below the bimetal to change the temperature rise of the bimetal. Moreover, since one side of the bimetal is curved, it is connected to a flexible member such as a copper stranded wire.

  In the following embodiments, in order to simplify the description, a direct heating type with a simple structure will be described. However, the present invention is not limited to this, and all circuit breakers in which the bimetal is bent to cut off the current are described. The present invention can be applied to a thermal trip device, and the same applies to an indirectly heated type or an directly heated type.

Embodiment 1 FIG.
FIG. 3 is a block diagram showing a thermal trip device for a circuit breaker according to Embodiment 1 of the present invention. In FIG. 3, this thermal tripping device 10 includes a first bimetal 11 and a second bimetal 12 joined together via an intermediate member 13 to form a curved member, and the root of the curved member is riveted to the heater 14. It is attached at 15 mag. In addition, a copper stranded wire is connected to the tip of the first bimetal 11.

  The second bimetal 12 is provided in the bending direction of the first bimetal 11. In addition, the intermediate member 13 has a constant thickness in order to completely suppress the diversion between the first bimetal 11 and the second bimetal 12 and to equalize the contact state between the first bimetal 11 and the second bimetal 12. An insulating sheet or an insulating film made of resin or the like is preferable.

  Here, the temperature of the first bimetal 11 rises due to heat generated by Joule heat and heat exchange between components attached to the top and bottom of the first bimetal 11. Since the second bimetal 12 is partially connected to the first bimetal 11, the heat generated in the first bimetal 11 is transmitted to the second bimetal 12 by thermal conduction, and the temperature rises and curves.

  Subsequently, the operation of the bimetal will be described for each energization current. First, when the energization current is around the rated current, there is sufficient time for heat to be transferred from the first bimetal 11 to the second bimetal 12, so that the rising temperatures of the first bimetal 11 and the second bimetal 12 are substantially equal, Since the first bimetal 11 and the second bimetal 12 are bent in substantially the same manner, it is possible to obtain substantially the same amount of bending as in the case where the first bimetal 11 is bent.

  On the other hand, when the current is cut off during overcurrent energization, the time until the current is cut off is short, and the influence of the heat generated by the Joule heat of the component alone is greater than the heat exchange with other components. . Therefore, the first bimetal 11 is bent due to a temperature rise due to heat generated by Joule heat. When only the first bimetal 11 is considered, the temperature rises almost the same as in the case of a single bimetal both near the rated current and near the overcurrent, and is displaced so as to obtain the same bending amount.

  On the other hand, as described above, the temperature rise of the second bimetal 12 is mainly due to the transfer of heat from the first bimetal 11, and since the interruption time is short when the overcurrent is applied, the temperature rises almost from the first bimetal 11. Heat is not transmitted and the temperature hardly rises. Therefore, when only the second bimetal 12 is considered, the bending amount is almost zero.

  For this reason, when the overcurrent is applied, the first bimetal 11 tends to bend substantially the same as the case of a single bimetal, but the second bimetal 2 that is not substantially bent in the bending direction of the first bimetal 11 is provided. The bending of the first bimetal 11 is suppressed, and the time until the current is interrupted can be delayed.

  In this way, the bending member is composed of two bimetals, one of the first bimetals 11 is used as a current energizing path, and the other second bimetal 12 is provided in the bending direction of the first bimetal 11 so that the vicinity of the rated current is obtained. It is possible to delay the cut-off time at the time of overcurrent energization while making the amount of bending equal to the case of one bimetal. Further, by fixing the first bimetal 11 to the heater 14 with the rivet 15, the heat transfer is suppressed at the fixing portion, and the interruption time during overcurrent energization can be further delayed.

  Next, a case where the shape of the second bimetal 12 is changed will be described with reference to FIGS. 4 (a) to (c), FIGS. 5 (a) to (c) and FIG. 6 are configuration diagrams showing modifications of the thermal trip device for the circuit breaker according to Embodiment 1 of the present invention. is there.

  Here, in order to simplify the explanation, a case is considered where the attachment position and the length of the second bimetal 12 are changed when the physical property values of the first bimetal 11 and the second bimetal 12 are made equal. In order to further simplify the description, it is assumed that the temperature of the first bimetal 11 is uniform.

  4 to 6, when the rated current is energized, the first bimetal 11 and the second bimetal 12 have substantially the same rising temperature regardless of the mounting position and length of the second bimetal 12. A bending amount equivalent to that of a single bimetal is obtained.

  In addition, when bimetal is bent at the root side, it bends to the tip with its inclination, so it is more effective to suppress the bending amount at the root side than the case where the bending amount at the tip side is suppressed. large. For this reason, as shown in FIGS. 4A to 4C, the first bimetal 12 is attached to the lower portion of the first bimetal 11 as much as possible, that is, near the start point of bending, so that the first bi-metal 12 is attached at the first overcurrent. The amount of bending of the bimetal 11 can be greatly reduced.

  Further, as shown in FIGS. 5A to 5C, as the length of the second bimetal 12 is increased, the range in which the bending amount of the first bimetal 11 can be suppressed increases. It is possible to further reduce the amount of bending.

  That is, the amount of bending of the first bimetal 11 can be further suppressed by attaching the second bimetal 12 as large as possible to the base. Therefore, it is possible to obtain the necessary blocking time by determining the bimetal attachment position and length in accordance with the blocking time required for each application of the object.

  Moreover, as shown in FIG. 6, the number of the second bimetals 12 is not limited to one, and a plurality of second bimetals 12 may be attached in accordance with the cutoff time required for each use of the object. . Further, each of the plurality of second bimetals 12 may have a different length.

  The intermediate member 13 provided between the first bimetal 11 and the second bimetal 12 is made of an insulating material or the like so that no shunting or the like occurs when the first bimetal 11 and the second bimetal 12 come into contact with each other. Has been. Moreover, since the intermediate member 13 bends with the bimetal as the temperature rises, it is desirable that the intermediate member 13 be a flexible member such as a rubber sheet, resin, or FRP.

  In addition, since the intermediate member 13 is made of a material that can be electrically insulated, no shunting or the like occurs when the first bimetal 11 and the second bimetal 12 come into contact with each other. It is possible even if it is not. Further, the first bimetal 11 and the second bimetal 12 may be directly joined without sandwiching the intermediate member 13.

  Further, by changing the size and material of the intermediate member 13, it becomes possible to increase the heat capacity, suppressing the temperature rise of the first bimetal 11 during overcurrent energization without changing the amount of bending during energization of the rated current, It is possible to reduce the amount of bending of the first bimetal 11 and suppress the transfer of heat to the second bimetal 2.

  Moreover, you may use the 1st bimetal 11 and the 2nd bimetal 12 from which curvature amount mutually differs at the same raise temperature. Here, when the second bimetal 12 is made of the same material and shape as those of the single bimetal described above, the first bimetal 12 is bent when the amount of bending of the second bimetal 12 is the same as that of the single bimetal. It is assumed that a member having a small bending coefficient is selected so that the bending amount of 11 is small.

  According to this configuration, when the rated current is energized, the second bimetal 12 receives heat from the first bimetal 11 and rises in temperature, and the second bimetal 12 has a larger bending amount than the first bimetal 11 and the bending amount is suppressed. Therefore, the current is cut off only by the bending of the second bimetal 12, and a bending amount equivalent to that of a single bimetal is obtained.

  On the other hand, at the time of overcurrent energization, the second bimetal 12 hardly receives heat from the first bimetal 11 and does not increase in temperature, so the cutoff time is determined by the curvature of the first bimetal 11. By making the bending coefficient a small member, the amount of bending of the first bimetal 11 is suppressed, and the time until blocking increases.

  Further, when the first bimetal 11 is made of the same material and shape as those of the single bimetal described above, the second bimetal 12 is obtained when the bending amount of the first bimetal 11 is made equal to that of the single bimetal 11. The bending coefficient and the thickness of the first bimetal 11 may be increased at the same ratio, so that the bending amount is the same as that of a single bimetal when the rated current is applied.

  With this configuration, when the rated current is applied, the bending is performed in the same manner as in the case of one bimetal, but when the overcurrent is applied, the second bimetal 12 does not rise in temperature and the bending of the first bimetal 11 is suppressed. Therefore, the amount of suppression increases as the thickness increases, and the time required to shut off can be extended.

  That is, by designing the second bimetal 12 so as to obtain the same bending amount as the first bimetal 11 when the rated current is passed, the first bimetal 11 and the second bimetal 12 are one bimetal when the rated current is passed. Similarly, the second bimetal 12 bends and suppresses the bending of the first bimetal 11 during overcurrent energization. At this time, since the thickness of the second bimetal 12 is thicker than that of a single bimetal, the effect of suppressing the bending amount is great, and the interruption time can be extended. At this time, the curvature coefficient of the second bimetal 12 may be made smaller than that in the case of one bimetal, and the thickness may be reduced in accordance with the required cutoff time.

As described above, according to the first embodiment, one end is fixed, the curved member that is heated according to the overcurrent flowing through the current path of the circuit breaker and the other end can be displaced toward the trip bar is The first bimetal that is directly heated in response to the overcurrent and the second bimetal that is provided in the thickness direction of the first bimetal and suppresses the bending of the first bimetal when overcurrent is applied.
Therefore, the cut-off time at the time of overcurrent energization can be adjusted to a desired time depending on the use of the object while keeping the bending amount and cut-off time of the bending member at the time of rated current energization equal.

  Specifically, the thermal trip device for a circuit breaker according to Embodiment 1 of the present invention includes a first bimetal 11 that bears a main curve for interrupting current during overcurrent conduction, and a first bimetal 11. The second bimetal 12 disposed at a position to suppress the bending of the first metal 12, the heater 14 that is connected to the first bimetal 11 at the root and rises in temperature when energized, and the first bimetal 11 is pressed to be provided inside the circuit breaker. And a trip bar 4 for operating a current interrupting mechanism.

  Moreover, the 1st bimetal 11 which bears main curvature is installed on an electricity supply path | route, and it heat | fever-generates by own Joule heat. The first bimetal may be provided outside the energization path, energized by a heater provided at the lower or upper portion of the first bimetal, and the first bimetal may be bent due to the temperature rise from the heater.

  Here, the bending member is provided with a plurality of bimetals, and each bimetal is constituted by a bimetal whose physical property value is adjusted, such as a bending coefficient and shape, that is, length and thickness. It is also possible to adjust the fixing position of the first bimetal 11 and the second bimetal 12. Accordingly, it is possible to adjust the bending amount and the cut-off time at the time of overcurrent energization without substantially changing the bending amount and the cut-off time at the time of energization near the rated current.

  In addition, when the rated current is applied, both the first bimetal 11 and the second bimetal 12 rise in temperature and bend. In addition, when the overcurrent is applied, the temperature of the first bimetal 11 rises and bends, but heat is not transmitted to the second bimetal 12, and since the temperature rise is small, the first bimetal 11 does not substantially bend. The blocking time can be adjusted by 12 being suppressed.

  Note that the thermal trip device for a circuit breaker described in Patent Document 2 has a very large reduction amount of the absolute value of the bending amount compared to the circuit breaker in which the bending member is composed of only bimetal. Since the current flowing in the circuit is not interrupted when the current is applied, and the current flowing in the circuit exceeds the rated current, the current is interrupted. There is a problem that there is.

  In addition, variations in the physical property values of the parts that make up the circuit breaker, and variations in the breaking time caused by processing and manufacturing errors, etc., have a greater effect than breakers in which curved members are made of only bimetal. Therefore, there is a problem that the allowable range is narrow and adjustment is very difficult.

  In addition, in the thermal trip device for a circuit breaker described in Patent Document 2, when trying to obtain a bending amount equivalent to that of a circuit breaker in which a bending member is configured only by a bimetal, the bimetal and the extension plate It is necessary to make the length longer than that described in Patent Document 2. For this reason, there is a problem in that it affects the shape of the entire circuit breaker and restricts the structure.

  Further, in the thermal trip device for a circuit breaker described in Patent Document 2, in order to make the bending amount of the bending member equal to the bending amount of the bimetal formed of a single member, the temperature at which the bimetal is bent It is also conceivable to increase the amount of bending during energization in the vicinity of the rated current by increasing the value of the current.

  However, in order to increase the temperature of the bimetal, it is necessary to increase the electrical resistance of the member that overheats the bimetal and to change the temperature to a higher allowable temperature. For this reason, there is a problem that the thermal tripping device for the circuit breaker is increased in cost and attention must be paid to the surrounding environment in which the circuit breaker is used.

  On the other hand, according to the thermal trip device for the circuit breaker according to the first embodiment of the present invention, the second bimetal 11 suppresses the bending of the first bimetal in the bending direction of the first bimetal 11 when overcurrent is applied. A bimetal 12 is provided. As a result, the amount of bending and the interruption time during energization of the overcurrent can be adjusted, so that the bimetal and the trip bar can be easily adjusted. Further, since the amount of bending of the entire bending member can be ensured, it is not necessary to increase the allowable temperature of the heater, and there is no restriction on the structure, thereby preventing an increase in cost.

Embodiment 2. FIG.
In the first embodiment, it has been described that the second bimetal 12 is provided in the bending direction of the first bimetal 11. In the second embodiment, a configuration in which the amount of bending is changed by providing the second bimetal 12 in a direction opposite to the bending direction of the first bimetal 11 will be described.

  FIG. 7 is a configuration diagram showing a thermal trip device for a circuit breaker according to Embodiment 2 of the present invention. In FIG. 7, the bimetal to be energized is referred to as the first bimetal 11 as in the first embodiment, and the bimetal that is not energized is referred to as the second bimetal 12. The second bimetal 12 is provided in a direction opposite to the bending direction of the first bimetal 11.

  Here, the amount of bending of the first bimetal 11 and the second bimetal 12 is designed so that the second bimetal 12 is larger when the rising temperature is the same. Here, to simplify the explanation, it is assumed that only the curvature coefficient is changed, and the curvature coefficient of the second bimetal 12 is larger than the curvature coefficient of the first bimetal 11.

  According to this configuration, as in the first embodiment, during overcurrent energization, almost no heat is transmitted to the second bimetal 12, so the second bimetal 12 is not bent, and the first bimetal 11 is caused by Joule heat. Since it generates heat and curves as the temperature rises, the cutoff time is determined only by the curvature of the first bimetal 11. At this time, in order to delay the interruption time at the time of overcurrent energization, a member having a small curvature coefficient may be used for the first bimetal 11.

  In addition, when the rated current is applied, heat is transferred from the first bimetal 11 to the second bimetal 12, the temperature rises of the first bimetal 11 and the second bimetal 12 are substantially equal, and the second bimetal 2 having a large curvature coefficient is the first. Press bimetal 11. Therefore, the amount of bending near the rated current is determined by the bending of both the first bimetal 11 and the second bimetal 12.

  In order to make the amount of bending in the vicinity of the rated current equal to that of a single bimetal, the second bimetal 12 is made of a material having a large bending coefficient, so that the second bimetal 12 alone is assumed. The amount of bending is larger than that of a single bimetal, and the amount of bending when the first bimetal 11 alone is assumed is smaller than that of a single bimetal. As a result, the bending of the second bimetal 12 is reduced. Therefore, it is possible to obtain the same amount of bending as in the case of a single bimetal.

  Further, according to the configuration of the thermal trip device for the circuit breaker according to the second embodiment of the present invention, when the overcurrent is applied, the bending amount of the bending member is determined by the bending of only the first bimetal 11, and therefore the same. The amount of bending obtained over time is reduced, and it is possible to greatly extend the interruption time when energizing an overcurrent as compared with a single bimetal structure.

Embodiment 3 FIG.
FIG. 8 is a block diagram showing a thermal trip device for a circuit breaker according to Embodiment 3 of the present invention. In FIG. 8, when attaching the first bimetal 11 to the heater 14 or joining the second bimetal 12 or the intermediate member 13 to the first bimetal 11, solder or solder 17 is used. In the third embodiment, at least one of the fixed portions of the first bimetal 11 and the second bimetal 12 is brazed or soldered.

  According to this configuration, the fastener shown in FIG. 3, for example, the rivet 15 is not required, and the first bimetal 11 and the second bimetal 12 are fixed by fixing the bimetals with the solder or solder 17 having high thermal conductivity. Therefore, it is possible to suppress variations among products when heat generated in the first bimetal 11 is transmitted to the second bimetal 12.

Embodiment 4 FIG.
FIG. 9 is a block diagram showing a thermal trip device for a circuit breaker according to Embodiment 4 of the present invention. In FIG. 9, a heat capacity body 18 having a heat capacity is attached to a fixed portion between the first bimetal 11 and the second bimetal 12 or a side surface of the bimetal.

  In this configuration, the heat capacity body 18 may be a resin material such as PET (polyethylene terephthalate) or PP (polypropylene), but by using the heat capacity body 18 made of a metal having high thermal conductivity such as Cu or Al, The heat capacity of the bending member can be increased without greatly changing the thermal resistance. Therefore, when the rated current is energized for a long energization time, the temperature rises almost the same as when the heat capacity body 18 is not used, and the amount of bending and the time until interruption are not substantially changed.

  On the other hand, at the time of overcurrent energization, by using the heat capacity body 18 particularly near the root, it is possible to suppress the temperature rise, and it is possible to delay the amount of bending and the time until interruption. Further, when it is desired to greatly delay the time until the interruption, it is possible to cope by changing the size or material of the heat capacity body 18.

  Moreover, since the effect is acquired even if the heat capacity | capacitance body 18 is attached to the side surface of a bimetal, you may change an arrangement position and a shape with respect to the interruption | blocking time at the time of the overcurrent energization requested | required. At this time, the heat capacity body 18 may use not only a metal having high thermal conductivity such as Cu or Al but also a resin material such as PET or PP.

  According to this configuration, the heat capacity body 18 that has been conventionally designed by changing the material and shape in consideration of the entire energizing portion including the heater 14 is arranged at a suitable position of the bending member. The cut-off time can be adjusted not only when energizing overcurrent but also when energizing near the rated current.

  9 shows a case where one heat capacity body 18 is arranged on the second bimetal 12, a plurality of heat capacity members 18 may be used depending on the required cut-off time and amount of bending, or may be attached to the first bimetal 11. . The fixing method of the heat capacity body 18 is not limited to fixing with the rivet 15 but may be fixing by brazing or soldering.

  DESCRIPTION OF SYMBOLS 1 Stator, 1a Fixed contact, 2 Movable element, 2a Movable contact, 3 Opening / closing mechanism, 3a Handle, 3b Movable arm, 4 Trip bar, 5 Case, 10 Thermal trip device, 11 1st bimetal, 12 1st 2 bimetals, 13 intermediate members, 14 heaters, 15 rivets, 16 copper stranded wire, 17 wax or solder, 18 heat capacity body.

Claims (7)

A thermal tripping device for a circuit breaker that performs an opening operation of the switching mechanism by contacting a trip bar of the switching mechanism,
One end is fixed, heated according to an overcurrent flowing in the current path of the circuit breaker, and the other end includes a bending member that can be displaced toward the trip bar,
The bending member is
A first bimetal heated directly in response to the overcurrent;
It provided a thickness direction of the first bimetal bending direction of the first bimetal, have a, a second bimetal suppress the bending of the first bimetal when over-current energization,
An intermediate member made of an insulating material having a constant thickness is provided between the first bimetal and the second bimetal.
Thermal trip device for circuit breakers. A thermal tripping device for a circuit breaker that performs an opening operation of the switching mechanism by contacting a trip bar of the switching mechanism,
One end is fixed, heated according to an overcurrent flowing in the current path of the circuit breaker, and the other end includes a bending member that can be displaced toward the trip bar,
The bending member is
A first bimetal heated directly in response to the overcurrent;
A second bimetal provided in the thickness direction of the first bimetal and in a direction opposite to the bending direction of the first bimetal,
At the same temperature rise, the bending amount of the second bimetal alone is larger than the bending amount of the first bimetal alone,
An intermediate member made of an insulating material having a constant thickness is provided between the first bimetal and the second bimetal.
Thermal trip device for circuit breakers. Said first bimetal, said current path constitutes a, and thermally activated tripping of the circuit breaker according to claim 1 or 2 is heated by the current flowing in itself device. A heater formed in the current path;
The thermal trip device for a circuit breaker according to claim 1 or 2 , wherein the first bimetal is heated by receiving heat generated by a current flowing through the heater, the one end being fixed to the heater. The thermal trip device for a circuit breaker according to any one of claims 1 to 4 , wherein the first bimetal is fixed by a fastener. The thermal trip device for a circuit breaker according to any one of claims 1 to 4 , wherein the first bimetal is fixed by soldering or soldering. The thermal trip device for a circuit breaker according to any one of claims 1 to 6 , wherein the bending member is provided with a heat capacity body that absorbs heat transmitted to the bending member.

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