KR100586574B1 - Bimetal plate laminated thereon positive temperature coefficient material layer and Device of blocking over current in electrical circuit using the same - Google Patents

Abstract

The present invention relates to a bimetal plate bonded to a positive temperature coefficient (PTC) material layer and an overcurrent blocking device using the same. The bimetal plate according to the present invention includes first and second metal layers having different thermal expansion coefficients and facing each other, and a PTC material layer directly bonded on the first or second metal layers. In addition, the overcurrent blocking device according to the present invention is connected to the electrical circuit between the power supply and the load to block the supply of the overcurrent to the load, the bimetal plate, the upper and lower contacts for performing a switching operation for blocking the overcurrent And overcurrent is generated in the electrical circuit, the contact between the upper contact point and the lower contact point is released due to the bending of the bimetal plate, and thereafter, the PTC material layer generates Joule heat due to leakage current. By continuously maintaining the bent state, it is characterized in that the repetitive trip (cycling trip) phenomenon is essentially blocked.

Description

Bimetal plate laminated thereon positive temperature coefficient material layer and Device of blocking over current in electrical circuit using the same}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a cross-sectional view showing the configuration of an overcurrent blocking device using a conventional bimetal.

Fig. 2 is a circuit diagram showing that an overcurrent blocking device using a conventional bimetal is connected to an electric circuit.

3A and 4A are cross-sectional views showing the configuration of a bimetal plate according to an embodiment of the present invention.

3B and 4B are cross-sectional views showing the operation of the bimetal plate according to the embodiment of the present invention.

5A to 5D are cross-sectional views illustrating a configuration of an overcurrent blocking device according to an embodiment of the present invention.

6A and 6B are circuit diagrams showing that the overcurrent blocking element according to the embodiment of the present invention is connected to an electric circuit.

The present invention relates to a bimetal plate used for overcurrent blocking and an overcurrent blocking device using the same, and more particularly, to a bimetal plate without a repeated tripping phenomenon and an overcurrent blocking device using the same.

Bimetal is a material in which two metals having different thermal expansion coefficients are bonded to each other, and have a characteristic of bending when the temperature is changed due to a difference in relative thermal expansion coefficients of the metals. Accordingly, in recent years, an overcurrent blocking device using a bimetal that senses heat generated by an overcurrent due to a short circuit of an electric circuit and cuts off a current supply flowing from a power supply to a load has been widely used.

Fig. 1 is a sectional view showing a general configuration of a conventional overcurrent blocking device using bimetal, and Fig. 2 is a circuit diagram showing that the overcurrent blocking device is connected to an electric circuit.

1 and 2, the conventional overcurrent blocking device A includes a bimetal plate 40 in which an upper metal 20 and a lower metal 30 having different thermal expansion coefficients face each other and are bonded to each other. And an upper contact 50 bonded to one side of the lower metal 40 of the 40 and a lower contact 60 bonded to the metal lead 70 to make contact with the upper contact 50.

Here, the upper metal 20 has a smaller coefficient of thermal expansion than the lower metal 30. The bimetal plate 40 and the metal lead 70 are connected in series between the power supply 80 and the load 90 of the electric circuit B to be subjected to overcurrent control. In addition, the bimetal plate 40 is in direct contact with a predetermined resistance heating element 100 that generates Joule heat by the current flowing in the electric circuit (B) by the heat generated in the electric circuit (B). It detects and switches.

In the overcurrent blocking device A having the above-described configuration, the bimetal plate 40 maintains its shape when the temperature of the resistance heating element 100 is lower than a predetermined set temperature at which switching operation is required. . Therefore, the electrical contact between the upper contact 50 and the lower contact 60 is not released, and accordingly, in the electric circuit B to which the overcurrent blocking element is connected, the current is normal from the power supply 80 to the load 90. Will be supplied.

On the contrary, when a physical defect such as a short circuit occurs in the electric circuit B, an overcurrent is generated in the electric circuit B. Then, the temperature of the resistance heating element 100 rises higher than a predetermined set temperature at which switching operation is required. Accordingly, the shape of the bimetal plate 40 is bent to form the upper contact point 50 and the lower contact point 60. The contact of the liver is released so that the current supply from the power supply 80 to the load 90 is interrupted.

However, when the contact between the upper contact 50 and the lower contact 60 is released, the current supply to the resistance heating element 100 is also cut off so that no more Joule heat is generated in the resistance heating element 100. Accordingly, the temperature of the resistive heating element 100 and the bimetal plate 40 making direct contact therewith also drop. As a result, while the shape of the bimetal plate 40 is restored to its original state, an electrical contact is formed between the upper contact 50 and the lower contact 60 again. However, since the factor of overcurrent is not eliminated in the electric circuit B, the temperature of the resistance heating element 100 and the bimetal plate 40 is increased again, and thus the electrical contact between the upper contact 50 and the lower contact 60 is again increased. The contact is released.

Repeated opening and closing of the upper contact 50 and the lower contact 60 is continuously repeated unless the cause of the overcurrent is removed from the electric circuit B, which is called a repeated trip phenomenon. However, when the contact between the upper contact point 50 and the lower contact point 60 is released, sparks and electrical noise are generated between the contact points. Therefore, if a repetitive trip phenomenon occurs, the physical contact of the upper contact point 50 and the lower contact point 60 may occur. There is a problem that is accompanied by deterioration. In addition, when the load 90 supplied with current from the power supply 80 is a noise sensitive device, there is a risk of damage to the device due to repeated tripping.

On the other hand, in addition to the bimetal-based device, there are devices using a PTC material that exhibits positive temperature coefficient (PTC) characteristics. Such devices are commonly referred to as PTC thermistors. The PTC thermistor has a low resistance at room temperature, which allows the current to flow from the power supply to the load. However, if an overcurrent occurs due to a short circuit fault such as a short circuit, the PTC thermistor will suddenly increase in temperature due to the generation of joule heat, and the resistance will increase to several tens of times, preventing the overcurrent from flowing from the power supply to the load. The temperature at which the PTC thermistor's resistance rises to several tens of times is called the overcurrent blocking temperature, and the overcurrent blocking temperature can be easily changed by adjusting the components of the PTC material.

PTC thermistors, however, remain in a high resistance state because the leakage current causes continuous heat generation even after the current is interrupted. Thus, PTC thermistors have the advantage that they do not involve repeated tripping, such as the interruption and energization of current, such as bi-current overcurrent blocking devices.

Accordingly, attempts to apply PTC materials to various switching devices using bimetal have been sought from various angles.

For example, U.S. Patent No. 5,870,014 (hereinafter referred to as' 014 patent) uses a pill made of a PTC material to block current flowing through a coil that drives a compressor motor of a refrigerator using a U-shaped bimetal. Posts a configuration to supply heat to a bi-metal.

However, in the case of the '014 patent, the thermal contact between the PTC fill and the U-shaped bimetal is not precisely defined, so heat transfer cannot be efficiently performed, and the main deformation portion of the U-shaped bimetal during the switching operation is the U-shaped banding. In addition, since there is no direct heat supply to the portion, there is a limit that the repeated trip phenomenon of the bimetal cannot be prevented at the source.

As another example, US Pat. No. 6,503,647 (hereinafter referred to as the '647 patent) discloses a battery protector having a configuration that can supply heat to bimetal using a PTC thermistor in battery protection mode. However, in the case of the '647 patent, the PTC thermistor has to be in point contact with the bimetal to maintain the spring tension of the bimetal, so that heat transfer can not be effectively performed, and the part where the PTC thermistor is in point contact with the bimetal is bimetallic. Since it is not the point at which major deformations occur, there is still a limit to the inherent limitation of bimetallic repeated tripping phenomenon.

Accordingly, an object of the present invention is to provide a bimetal plate having a novel structure and an overcurrent blocking device using the same, which are invented to solve the above-described problems of the prior art, which can fundamentally block the occurrence of a repetitive trip phenomenon.

Bimetal plate according to the present invention for achieving the above technical problem, is used as a switching element for the over-current blocking, the first metal layer and the second metal layer facing each other and having a different coefficient of thermal expansion, and the first And a PTC material layer bonded on the metal layer or the second metal layer.

Preferably, the electrode layer is further bonded to the PTC material layer. In addition, it is preferable that the overcurrent blocking temperature due to the resistance increase of the PTC material layer is equal to or higher than the overcurrent blocking temperature due to the bending of the first metal layer and the second metal layer.

The first metal layer may have a larger coefficient of thermal expansion than the second metal layer, or vice versa.

The overcurrent blocking device according to an aspect of the present invention for achieving the above another technical problem is used to cut off the overcurrent supply to the load is connected between the power supply and the load, the first metal layer having a first coefficient of thermal expansion And a second metal layer bonded to the lower portion of the first metal layer with a second thermal expansion coefficient greater than the first thermal expansion coefficient, a PTC material layer bonded on the first metal layer, and bonded on the PTC material layer. Fixed to form an electrode layer for conducting a current flowing from a power supply to the load to the PTC material layer, an upper contact bonded to a lower side of one side of the second metal layer, and a contact capable of opening and closing with the upper contact for overcurrent blocking Characterized in that it comprises a lower contact.

According to another aspect of the present invention, an overcurrent blocking device according to another aspect of the present invention is connected between a power supply and a load, and is used to cut off an overcurrent supply to a load, and includes a first metal layer having a first thermal expansion coefficient. And a second metal layer bonded to the lower portion of the first metal layer with a second thermal expansion coefficient greater than the first thermal expansion coefficient, a PTC material layer bonded on the second metal layer, and bonded on the PTC material layer. A lower portion fixed to form an electrode layer for conducting a current flowing from a power supply to the load to the PTC material layer, an upper contact bonded to a lower side of the electrode layer, and a contact capable of opening and closing operation with the upper contact for blocking an overcurrent It characterized in that it comprises a contact.

The overcurrent blocking device according to another aspect of the present invention for achieving the above another technical problem is used to cut off the overcurrent supply to the load is connected between the power supply and the load, the first having a first coefficient of thermal expansion A PTC material bonded to the second metal layer to expose a metal layer, a second metal layer having a second coefficient of thermal expansion greater than the first coefficient of thermal expansion, and bonded to a lower portion of the first metal layer, and one side of the second metal layer; Layer, an electrode layer bonded on the PCT material layer and electrically connecting a current flowing from the power source to the load to the PTC material layer, an upper contact bonded on the exposed second metal layer, and the upper contact for overcurrent blocking. And a lower contact fixed to form a contact capable of opening and closing operation.

The overcurrent blocking device according to another aspect of the present invention for achieving the above another technical problem is used to cut off the overcurrent supply to the load is connected between the power supply and the load, the first having a first coefficient of thermal expansion A metal layer, a second metal layer bonded to a lower portion of the first metal layer having a second coefficient of thermal expansion greater than the first coefficient of thermal expansion, a PTC material layer bonded to the second metal layer, and bonded onto the PCT material layer An upper contact bonded to an electrode layer for conducting current flowing from a power supply to the load to the PTC material layer, a metal piece extending from one end of the first metal layer and / or the second metal layer, and the upper contact for overcurrent blocking And a lower contact fixed to form a contact capable of opening and closing operation.

Preferably, the first metal layer and / or the second metal layer and the lower contact are connected in series to an electrical circuit formed between the power supply and the load. To this end, the lower contact is preferably fixed to a metal lead connected to the electrical circuit, the metal lead connected to the electrical circuit is preferably bonded to the first metal layer and / or the second metal layer.

Preferably, the electrode layer is connected in parallel with the first metal layer or the second metal layer and the lower contact (bimetal part). To this end, it is preferable that a metal lead is bonded to the electrode layer for making a connection with an electric circuit.

According to the present invention, it is preferable that the overcurrent blocking temperature due to the resistance increase of the PTC material layer is higher than or equal to the overcurrent blocking temperature due to the bending of the first metal layer and the second metal layer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, various equivalents that may be substituted for them at the time of the present application It should be understood that there may be water and variations.

Bimetal plate (C) according to an embodiment of the present invention has a first metal layer 110 having a first coefficient of thermal expansion, and a second coefficient of thermal expansion greater than the first coefficient of thermal expansion, as shown in Figure 3a The second metal layer 120 bonded to the metal layer 110 and the PTC material layer 130 bonded to the first metal layer 110 are provided.

Here, the electrode layer 140 is preferably bonded on the PTC material layer 130. The electrode layer 140 performs a function of energizing the current flowing in the electric circuit that is subject to overcurrent control to the PTC material layer 130. The bimetal plate C is thermally expanded as shown in FIG. 3B due to a difference in thermal expansion coefficient between the first metal layer 110 and the second metal layer 120 when the Rm temperature rises higher than a predetermined set temperature for the switching operation. The coefficient is bent toward the first metal layer 110 having a relatively small coefficient. Preferably, the overcurrent blocking temperature due to the resistance increase of the PTC material layer 130 is equal to or higher than the overcurrent blocking temperature due to the bending caused by the temperature increase of the first metal layer 110 and the second metal layer 120. .

The first metal layer 110 may be made of an alloy of nickel and iron, and the second metal layer 120 may be an alloy of copper and zinc, nickel; manganese; And alloys of iron, nickel; molybdenum; And alloys of iron, or manganese; nickel; And an alloy of copper. The PTC material layer 130 may be formed of a conductive composite in which carbon black or metal flake and a peroxide crosslinking agent are mixed with low density polyethylene (LDPE) or high density polyethylene (HDPE), or a ceramic based on barium titanate, and the electrode layer 140 may be composed of an electrode material for a PTC thermistor in which Zn, In, etc. are added to Ag, nickel or aluminum. However, the technical scope of the present invention is not limited to the above, and thus, the materials constituting the first metal layer 110 and the second metal layer 120, the PTC material layer 130, and the electrode layer 140 may be modified in various ways. Of course it is possible.

Meanwhile, in the modification of the bimetal plate according to the present invention, the PTC material layer 130 and the electrode layer 140 may be bonded to the lower portion of the second metal layer 120 as shown in FIG. 4B. Even in this case, when the temperature of the bimetal plate C rises above a predetermined set temperature for the switching operation, the bimetal plate C is bent in the direction of the first metal layer 110 as shown in FIG. 4B.

Next, a preferred embodiment of the overcurrent blocking device according to the present invention using the bimetal plate C having the above-described configuration will be described in detail. Here, the overcurrent blocking device of the present invention is connected in advance between the power supply and the load is used for the purpose of blocking the overcurrent supply to the load.

5A schematically shows the configuration of an overcurrent blocking device according to an embodiment of the present invention. Referring to the drawings, the overcurrent blocking device D has a first metal layer 110 having a first thermal expansion coefficient, a second thermal expansion coefficient greater than the first thermal expansion coefficient, and a lower portion of the first metal layer 110. PTC current layer 130 bonded to the second metal layer 120, the PTC material layer 130 bonded on the first metal layer 110, and the PTC material layer 130 and flowing from the power supply to the load An electrode layer 140 for energizing the material layer 130, an upper contact 150 bonded to a lower side of the second metal layer 120, and an opening / closing operation with the upper contact 150 to block overcurrent It has a bottom contact 160 fixed to form a possible electrical contact. Here, the types of materials constituting the first metal layer 110 and the second metal layer 120, the PTC material layer 130, and the electrode layer 140 have already been described with reference to the bimetal plate C according to the present invention. Since it was mentioned above, the description is abbreviate | omitted here.

The first metal layer 110 and / or the second metal layer 120 and the lower contact 160 are preferably connected in series to an electric circuit formed between a power supply and a load. To this end, the overcurrent blocking device D of the present invention further includes a metal lead 170 for connecting the lower contact 160 to an electric circuit, and the lower contact 160 is connected to the metal lead 170. Can be fixed. In the overcurrent blocking device (D) of the present invention, a metal lead (not shown) connected to an electric circuit may be bonded to the first metal layer 110 and / or the second metal layer 120.

The electrode layer 140 is preferably connected in parallel with the first metal layer or the second metal layer and the lower contact (bimetal part). To this end, a metal lead (not shown) may be bonded to the electrode layer 140 to form a connection with an electric circuit.

For the preferable operation of the overcurrent blocking device of the present invention, the overcurrent blocking temperature at which the resistance of the PTC material layer 130 rises is greater than the overcurrent blocking temperature due to the bending of the first metal layer 110 and the second metal layer 120. The same is preferable.

Meanwhile, in the overcurrent blocking device D of the present invention, the bonding position of the PTC material layer 130 and the type of the material layer to which the upper contact 150 is bonded may be variously modified. For example, the PTC material layer 130 and the electrode layer 140 are bonded to the bottom of the second metal layer 120 and the upper contact 150 is bonded to one side of the electrode layer 140 as shown in FIG. 5B. Can be. As another example, the PTC material layer 130 and the electrode layer 140 are bonded to the lower portion of the second metal layer 120 except for the point where the upper contact 150 is bonded as shown in FIG. 5C, and the upper contact point. 150 may be bonded on the second metal layer 120 to which the PTC material layer 130 and the electrode layer 140 are not bonded. As another example, as illustrated in FIG. 5D, the metal fragment 180 is bonded to one end of the first metal layer 110 and the second metal layer 120, and the PTC material layer 130 and the electrode layer 140 are bonded to each other. Silver may be bonded on the second metal layer 120, and the upper contact 150 may be bonded to a lower portion of the metal fragment 180.

FIG. 6A shows in more detail an electrical circuit in which the overcurrent blocking element D of the present invention is connected between a power supply 190 and a load 200. For convenience of description, the first metal layer 110, the second metal layer 120, the upper contact 150, and the lower contact 160 shown in FIGS. 5A to 5D are referred to as 'bimetal parts D1'. The PTC material layer 130 and the electrode layer 140 are referred to as 'PTC thermistor portion D2'. In addition, it is noted that the nodes E and F shown in Fig. 6A represent the points at which the bimetal portion D1 and the PTC thermistor portion D2 are connected to the electric circuit.

As shown in FIG. 6A, the bimetal part D1 is a node via a metal lead (not shown) fastened to the lower contact 160 and the first metal layer 110 and / or the second metal layer 120. It is connected in series to E and F. The PTC thermistor portion D2 is not connected to a separate node in the electrical circuit shown in FIG. 6A but is connected in parallel with the bimetal portion D1 in series with an electrical circuit formed between a power supply and a load.

Next, the operation of the overcurrent blocking device D according to the present invention will be described in detail with reference to the above-described circuit diagram shown in FIG. 6A.

Referring to FIG. 6A, when an overcurrent is generated in an electric circuit, the temperature of the bimetal part D1 rises to an operating temperature due to heat generated by self resistance. Then, the electrical contact of the bimetal part D1 is released, so that the overcurrent is not applied to the load 200.

On the other hand, when the temperature of the bimetal part D1 rises, the temperature of the PTC thermistor part D2 also rises together. This is because the bimetal portion D1 and the PTC thermistor portion D2 make direct contact with each other, and the PTC thermistor portion D2 generates its own heat. When the electrical contact is released due to the rise in the temperature of the bimetal portion D1, the resistance of the PTC thermistor portion D2 increases sufficiently with the increase in temperature. Accordingly, in the PTC thermistor unit D2, Joule heat due to leakage current is continuously generated, and thus the temperature reaches the overcurrent cutoff temperature, and the heat generated in this process is conducted to the bimetal portion D1, thereby causing the bimetal portion D1. ) Keeps electrical contact released. This contact release state is preferably maintained when the overcurrent cutoff temperature of the PTC thermistor portion D2 is greater than or equal to the operating temperature of the bimetal portion D1.

Due to the heat transfer mechanism as described above, it is possible to fundamentally prevent the occurrence of a trip phenomenon in which the bimetal part D1 is repeatedly opened and closed, and furthermore, the noise generated between the contact and the deterioration of the contact due to the repeated opening and closing of the bimetal part D1. It can prevent the damage of the load by

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto, and the technical spirit of the present invention and the following will be understood by those skilled in the art to which the present invention pertains. Various modifications and variations are possible, of course, within the scope of equivalents of the claims to be described.

According to an aspect of the present invention, since a repeated trip phenomenon does not occur by bonding a PTC material layer to a bimetal plate used for overcurrent blocking, it is possible to prevent damage to the load due to deterioration of the contact and noise.

According to another aspect of the present invention, since the PTC material layer forms a direct contact interface with the bimetal, if an overcurrent occurs in the electric circuit, rapid and rapid connection is transferred from the PTC material layer to the bimetal. Accordingly, high reliability of the overcurrent blocking device can be ensured.

Claims (13)

In the bimetal plate used for the switching element for blocking the overcurrent, A bimetal plate comprising a first metal layer and a second metal layer which face each other with different coefficients of thermal expansion and are bonded to each other, and a PTC material layer bonded on the first metal layer or the second metal layer. The method of claim 1, The bimetal plate further comprises an electrode layer bonded on the PTC material layer. The method of claim 1, And the overcurrent blocking temperature due to the resistance increase of the PTC material layer is higher than or equal to the overcurrent blocking temperature due to the bending of the first metal layer and the second metal layer. In the over-current blocking element is connected between the power supply and the load and used to cut off the over-current supply to the load, A first metal layer having a first coefficient of thermal expansion; A second metal layer bonded to a lower portion of the first metal layer and having a second thermal expansion coefficient greater than the first thermal expansion coefficient; A PTC material layer bonded on the first metal layer; An electrode layer bonded on the PTC material layer and configured to conduct current flowing from a power supply to a load to the PTC material layer; An upper contact bonded to a lower side of one side of the second metal layer; And And a lower contact fixed to form a contact capable of opening and closing operation with the upper contact to block an overcurrent. In the over-current blocking element is connected between the power supply and the load and used to cut off the over-current supply to the load, A first metal layer having a first coefficient of thermal expansion; A second metal layer bonded to a lower portion of the first metal layer and having a second thermal expansion coefficient greater than the first thermal expansion coefficient; A PTC material layer bonded on the second metal layer; An electrode layer bonded on the PTC material layer and configured to conduct current flowing from a power supply to a load to the PTC material layer; An upper contact bonded to a lower side of one side of the electrode layer; And And a lower contact fixed to form a contact capable of opening and closing operation with the upper contact to block an overcurrent. In the over-current blocking element is connected between the power supply and the load and used to cut off the over-current supply to the load, A first metal layer having a first coefficient of thermal expansion; A second metal layer bonded to a lower portion of the first metal layer and having a second thermal expansion coefficient greater than the first thermal expansion coefficient; A PTC material layer bonded to the second metal layer to expose one side of the second metal layer; An electrode layer bonded on the PCT material layer and configured to conduct current flowing from a power supply to a load to the PTC material layer; An upper contact bonded to the exposed second metal layer; And And a lower contact fixed to form a contact capable of opening and closing operation with the upper contact to block an overcurrent. In the over-current blocking element is connected between the power supply and the load and used to cut off the over-current supply to the load, A first metal layer having a first coefficient of thermal expansion; A second metal layer bonded to a lower portion of the first metal layer and having a second thermal expansion coefficient greater than the first thermal expansion coefficient; A PTC material layer bonded to the second metal layer; An electrode layer bonded on the PCT material layer and configured to conduct current flowing from a power supply to a load to the PTC material layer; An upper contact bonded to a metal piece extending from one end of the first metal layer or the second metal layer; And And a lower contact fixed to form a contact capable of opening and closing operation with the upper contact to block an overcurrent. The method according to any one of claims 4 to 7, And the first metal layer or the second metal layer and the bottom contact are connected in series to an electric circuit formed between the power supply and the load. The method of claim 8, And the lower contact is fixed to a metal lead connected to the electric circuit. The method of claim 8, And the metal lead connected to the electric circuit is bonded to the first metal layer or the second metal layer. The method of claim 8, And the electrode layer is connected in parallel with the first metal layer or the second metal layer and the lower contact. The method of claim 11, And the metal lead is bonded to the electrode layer to form a connection with an electric circuit. The method according to any one of claims 4 to 7, The overcurrent blocking temperature due to the resistance increase of the PTC material layer is higher than or equal to the overcurrent blocking temperature due to the bending of the first metal layer and the second metal layer.

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