JP5584564B2 - breaker - Google Patents

Description

  The present invention relates to a mechanically operated safety device such as a breaker, a thermostat, or a switch that opens and closes a circuit by reversing a thermally responsive element such as a bimetal.

  A battery pack using a secondary battery such as a lithium ion battery is provided with a safety device that shuts down the circuit and prevents ignition or explosion when the temperature rises due to overcharging or the like. For such a safety device, a breaker using the reversal operation of a thermally responsive element such as a bimetal is preferable because it can be repeatedly operated and the accuracy of the operating temperature at which the circuit is shut off at high temperature is good.

  This type of breaker usually uses a movable arm with a movable contact, a fixed base with a fixed contact, a heat-responsive element such as a bimetal that reverses when heat changes, and a thermal element such as a PTC thermistor for self-holding. Built in the case. (See JP 2005-129471, JP 2002-056840, etc.)

  The bimetal reverses as the temperature rises and pushes up the movable arm. The movable contact of the moved movable arm is separated from the fixed contact, and the circuit is interrupted. Here, the PTC thermistor generates heat when a voltage is applied, and the cut-off state continues in a self-holding manner as long as it generates heat.

  When the temperature drops to the return temperature and the bimetal returns to its original shape, the movable contact and the fixed contact come into contact again, and the circuit returns to the conductive state. The breaker is required not only to be in a cut-off state at a predetermined temperature, but also to reliably and quickly reconnect the circuit at a low temperature.

  However, in the conventional design, since the return temperature is determined only depending on the performance unique to the bimetal, it is difficult to return to the conductive state at a desired temperature. Adjustment of the return temperature is generally more difficult than providing the desired operating temperature and is an obstacle to stable production of bimetal. Further, as the size of the battery pack is further reduced, the adjustment of the operating temperature and the return temperature of the breaker, and the degree of freedom of design are being limited more than ever by reducing the size of the parts. Therefore, there has been a demand for a breaker having good temperature accuracy and a simple structure.

JP 2005-129471 A JP 2002-056840 A

  The present invention provides a design for facilitating the setting of the return temperature as expected above in a safety device using an inversion-type thermally responsive element.

  As a result of earnestly examining the design of the breaker in order to solve the above-mentioned problems, the present inventors have raised a protrusion between a specific position of the movable arm and the resin case in the breaker using the reversible thermal responsive element and the movable arm. Thus, the present inventors have found that the return temperature can be stably set by forming the contact structure in the movable arm.

According to a first aspect of the present invention, a movable arm having a movable contact and a thermally responsive element that reversely operates according to a temperature change are built in the case. The thermally responsive element is reversed at a high temperature to push up the movable arm and The breaker separates the movable contact and the fixed contact, returns to the original shape at a low temperature, and contacts the movable contact and the fixed contact, and has the following relationship.
The movable arm has a fixed part fixed to the case, a movable part pushed up by the thermally responsive element, and a bent part formed between the movable contact on the movable part and the fixed part, Furthermore, a substantially flat plate-like flat portion is provided between the bent portion and the fixed portion. The flat part has a contact pressure between the movable arm and the case on the bent part side of the contact point between the thermally responsive element and the movable arm reversed at a high temperature, rather than on the fixed part side. There is a pressing contact that generates

  In the second aspect of the present invention, the pressing contact is present between the movable arm and the case at all times during high temperature and low temperature.

  In the third aspect of the present invention, the pressing contact is composed of a protrusion protruding on the inner side surface of the cover portion of the case and the movable arm.

  In the fourth aspect of the present invention, the pressing contact is constituted by a protrusion raised on the flat portion of the movable arm and the case.

  In the fifth aspect of the present invention, in the step of welding and joining the cover portion of the case to the base portion of the case, by adjusting the thickness of the case, the breaker is disposed between the movable arm and the case. Contact pressure, operating temperature and return temperature are adjusted.

  According to the present invention, it is possible to significantly adjust the temperature characteristics such as the operating temperature and the return temperature of the breaker as follows, not only the characteristics unique to the thermal actuator.

In the first aspect of the present invention, the movable arm first has a fixed portion and a movable portion, and then has a bent portion between the movable contact on the movable portion and the fixed portion. A flat portion having a substantially flat plate shape from the portion to the fixed portion, and further, the flat portion is closer to the bent portion than the contact point between the thermally responsive element and the movable arm that is reversed at a high temperature, Since there is a pressing contact that generates contact pressure between the movable arm and the case, the return temperature can be easily adjusted in the breaker, and the size can be easily reduced in response to the downsizing of the battery pack.
Further, the pressing contact generates a contact pressure closer to the end of the movable arm where the movable contact is placed than the one on the fixed portion side of the contact between the thermally responsive element and the movable arm that is reversed at a high temperature. The force due to this contact pressure is transmitted more efficiently. Therefore, the return temperature can be adjusted more easily. In addition, since the pressing contact is disposed on the substantially flat plate-like flat portion of the movable arm, the return temperature can be adjusted more stably and easily than when it is provided at a position other than the flat portion.

  In the second aspect of the present invention, since the pressing contact is present between the movable arm and the case at all times during high temperature and low temperature, the spring force of the movable arm is a contact point during conduction. The spring force of the movable arm is efficiently used to return the original shape of the movable arm and the thermally responsive element when the power is returned to a low temperature that should be turned on again. . Therefore, even in a breaker with a reduced height, the temperature characteristics can be easily adjusted and stabilized, such as enabling quick return operation and long-term durability.

  In the third aspect of the present invention, the pressing contact is composed of a protrusion protruding on the inner side surface of the cover portion of the case and the movable arm, so that the size of the movable arm is not limited. In addition, the structure of the pressing contact can be designed. When the dimension of the movable arm is small, it may be difficult to provide a satisfactory protruding structure for a pressing contact or the like. Furthermore, if the shape of the movable arm is complicated, the spring force of the movable arm is affected, and it may be difficult to predict the adjustment of the operating temperature and the return temperature. Therefore, if the pressing contact is formed by raising a protrusion on the inner side surface of the cover portion, it becomes possible to more easily control the temperature characteristics and stably produce the circuit breaker with a reduced height.

  In the fourth aspect of the present invention, the pressing contact is composed of a protrusion raised on the flat portion of the movable arm and the case, so that depending on the shape of the protrusion, when the movable arm is reversed or the original shape It shows a tendency to increase the shape stability in each state of time. Therefore, it is possible to maintain the accuracy in the temperature characteristics and stably produce even if the size of the parts in the breaker is reduced corresponding to the downsizing of the battery pack.

  In the fifth aspect of the present invention, in the step of welding and joining the cover portion of the case to the base portion of the case, by adjusting the thickness of the case, the breaker is disposed between the movable arm and the case. Since the contact pressure, the operating temperature, and the return temperature are easily and appropriately finely adjusted, even with a low-profile breaker, it is possible to control the temperature characteristics more easily and stably to produce stably.

The conceptual diagram which shows the state at the time of high temperature of embodiment of this invention Sectional drawing which shows one Embodiment which has a press protrusion in the case of this invention Sectional drawing which shows another form of implementation which has a pressing protrusion in the movable arm of this invention

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of an embodiment of the present invention. This is a conceptual diagram showing a state at a high temperature. FIG. 2 is a cross-sectional view showing an embodiment of the present invention, in which a protrusion 8 a is raised on the inner side surface of the cover portion 2 a of the case 2. FIG. 3 is a cross-sectional view showing another embodiment of the present invention, in which a protrusion 8 b is raised on the flat portion 7 d of the movable arm 7. 2 and 3 show a state at a low temperature.

  In FIG. 1, a breaker 1 is configured by enclosing a case 2 with various components such as a fixed base 3, a PTC thermistor 4, a thermally responsive element (bimetal 5), and a movable arm 7. Since the thermally responsive element is usually formed of bimetal, it is hereinafter referred to as bimetal 5. Conventionally, the temperature characteristics such as the return temperature and the operating temperature are determined depending on the material of the bimetal and the movable arm, the mechanical characteristics, etc. In the present invention, the inner surface of the cover portion 2a of the case 2 and the movable arm 7 are used. By the pressing contact 8 that makes contact with each other, the transmission of the restoring force of the movable arm 7 becomes more efficient, and the restoration of the original shape is promoted. Other parts may follow conventional examples as long as there is no particular trouble.

  The case 2 includes a cover part 2a and a base part 2b. The cover portion 2a is formed by insert molding the cover metal portion 2d into the resin portion 2f. The cover metal portion 2d is advantageous for increasing the mechanical strength when the breaker 1 is downsized. The resin part 2f forms a side wall 2e and the like, and provides a fixed part 7e to which the movable arm 7 is attached and a part to which the cover part 2a and the base part 2b are welded. As shown in FIGS. 1 to 3, the inner surface of the cover portion 2a is usually provided with a receiving projection 2c to maintain the inverted state of the movable arm 7 and reduce the burden on the movable arm 7. Sometimes the movable arm 7 comes into contact. A pressing contact 8 is formed on the fixed portion 7e side on the inner surface of the cover portion 2a so as to face the receiving protrusion 2c.

  The fixed base 3 is a metal part insert-molded on the base portion 2 b of the case 2, and includes a base terminal 3 a that protrudes outside the case 2 and a portion where the fixed contact 3 b inside the case 2 is formed.

  The PTC thermistor 4 is a heating element used to configure a self-holding circuit. Although not shown in FIGS. 2 and 3, it is advantageous from the viewpoint of miniaturization to be placed directly under the movable arm as in FIG.

  The bimetal 5 is reversed at a high temperature, and the contact 6 is configured with the movable arm 7 on the fixed portion 7e side. In the present invention, for ease of design, the bimetal and the movable arm are divided and designed. FIG. 1 shows a state in which the movable arm 7 is pushed up at a high temperature, and the contact 6 on the fixed portion 7e side and another contact 6 'on the other side are generated. 2 and 3 show a state in which the bimetal 5 is restored to its original shape at a low temperature, the movable contact 7b is in contact with the fixed contact 3b, and the breaker 1 is conductive.

  At the contact point 6 between the bimetal 5 and the movable arm 7 at a high temperature, a small protrusion (dowel) can be used for adjusting the temperature characteristic of the breaker 1. Usually, the dowels are formed on the movable arm 7 so as to protrude in a direction facing the bimetal 5. Thus, the movable range of the movable contact 7b is increased, and the electrical characteristics and temperature characteristics of the breaker 1 can be further freely adjusted. The dowels can be formed on the bimetal 5 toward the movable arm 7.

  The movable arm 7 has an arm terminal 7a outside the case 2 and a movable contact 7b inside the case 2 at both ends, and a movable portion 7f and a fixing portion 7e for fixing to the side wall 2e of the case 2 in the middle region. The movable portion 7f is formed with a bent portion 7c and a flat portion 7d in order from the movable contact 7b toward the fixed portion 7e. The movable arm 7 may be formed separately as long as these parts can be electrically connected, and there may be a form in which the fixed portion 7e is not provided, but when there are a plurality of contact separation points, It becomes very cumbersome to adjust the electrical characteristics and temperature characteristics.

  The bent portion 7c is a bend, a mountain fold line or a valley fold line on the movable portion 7f, ensures springiness, and causes the breaker 1 to exhibit stable electrical characteristics when the movable contact 7b and the fixed contact 3b come in contact with each other. . In order to exhibit such a spring property, the bent portion 7c is located between the contact 6 and the contact 6 '. A flat part 7d having a substantially flat plate shape is formed partly or entirely from the bent part 7c to the fixed part 7e, and the pressing contact 8 is formed in a section on the flat part 7d. In order to easily control the temperature characteristics, it is desirable that the flat portion 7d or the inner surface of the cover portion 2a is flat.

  The pressing contact 8 includes a protrusion 8a on the inner surface of the cover portion 2a (FIGS. 1 and 2), a protrusion 8b on the flat portion 7d (FIG. 3), and a clear protrusion. It can be roughly divided into those not shown (not shown). The shape of the pressing contact 8, the protrusion 8a, or the protrusion 8b is not particularly limited as long as it contributes sufficiently to control of the temperature characteristics of the breaker 1. In addition to the form shown in the figure, for example, the bent portion 7c and the flat portion 7d made of a mountain fold line or a valley fold line are formed with a smooth mountain fold apex, and the apex of the mountain fold is directly applied to the inner surface of the cover portion 2a. It is also possible to make it a press contact 8. In addition, from the viewpoint of design freedom, a form in which the protrusion is raised is desirable.

  The region where the pressing contact 8, the protrusion 8a, or the protrusion 8b is configured is an intermediate region between the contact 6 between the bimetal 5 and the movable arm 7 and the bent portion 7c along the flat portion 7d. If the arrangement of the pressing contact 8 is provided on the movable contact 7b side from the bent portion 7c or the fixed portion 7e side from the contact 6, the restoring force of the movable arm 7 is not efficiently exhibited at a low temperature, and a desired return temperature is obtained. Hard to get.

  The shape of the pressing contact 8 may extend directly above the contact 6 between the bimetal 5 and the movable arm 7. However, if the pressing contact 8 is directly above the bent portion 7c, the temperature characteristics may not be stable. Therefore, it is desirable that the area covered by the pressing contact 8 occupies the middle between the contact 6 and the bent portion 7c. Although it is not disturbed that there are protrusions on both the cover portion 2a and the movable arm 7, in this embodiment, it is difficult to stably adjust the temperature characteristics.

  The pressing contact 8 can be formed on a member such as the movable arm 7 or the cover metal portion 2d by bending or drawing metal press processing such as a broken line or a protrusion, and is formed by the resin portion 2f. It doesn't prevent it. At this time, the return temperature can be adjusted by the height of the protrusions. Generally, the lower the protrusion, the lower the return temperature, and the higher the protrusion, the higher the protrusion temperature. In order to perform such adjustment more reliably and obtain stable characteristics, the pressing contact 8 continues to exist at both high temperature and low temperature, and the cover portion 2a and the movable arm 7 are always in contact. desirable. A form in which the pressing contact 8 disappears at a low temperature is also possible, but there is a tendency that electrical characteristics become unstable due to long-term use.

  The breaker 1 is completed by joining the cover portion 2a and the base portion 2b. At this time, in the case of a small breaker, it is easy to perform physicochemical bonding by ultrasonic welding, overheating, or the like by the welding bonding operation W rather than by engagement. 1 to 3 exemplify the welding and bonding on the side wall 2e made of resin. In addition, in this step, the contact pressure generated by the pressing contact 8 such as the protrusion 8a or the protrusion 8b can be finely adjusted by appropriately adjusting the force and time required to press the case 2 in the welding operation W. Good temperature characteristics. Furthermore, stable production, yield improvement, and the like can be further facilitated by performing the welding operation W while energizing and evaluating the electrical characteristics. Furthermore, if the change in the thickness of the case 2 at the time of joining is permissible, the burden due to the design change in the previous process of supplying the parts can be reduced, so the location and dimensions of the pressing contact 8 are changed. This increases the degree of freedom in design.

  In general, bimetal tends to have a recovery temperature lower than an operating temperature due to hysteresis. Therefore, the present invention is useful when it is desirable to return to the original shape at a temperature higher than the return temperature inherent to the bimetal or more quickly than the inherent return speed. In the present invention, by providing a contact structure at a specific position of the movable arm and adjusting it appropriately, the temperature characteristics of the breaker can be significantly controlled as compared with the conventional case.

1: Breaker,
2: Case, 2a: Cover part, 2b: Base part, 2c: Receiving protrusion, 2d: Cover metal part, 2e: Side wall, 2f: Resin part 3: Fixed base, 3a: Base terminal, 3b: Fixed contact 4: PTC Thermistor,
5: Bimetal (thermally responsive element),
6: Contact point between bimetal and movable arm at high temperature (fixed part side), 6 ': Contact point between bimetal and movable arm at high temperature (other end)
7: Movable arm, 7a: Arm terminal, 7b: Movable contact, 7c: Bent part, 7d: Flat part, 7e: Fixed part 7f: Movable part,
8: Press contact, 8a: Protrusion (on the inner surface of the cover part), 8b: Protrusion (on the flat part of the movable arm),
W: welding operation,

Claims (5)

A movable arm with a movable contact and a thermally responsive element that reverses when temperature changes are built into the case.
The thermally responsive element is inverted at a high temperature to push up the movable arm to separate the movable contact and the fixed contact, return to the original shape at a low temperature to bring the movable contact and the fixed contact into contact with each other,
The movable arm has a fixed part fixed to the case, a movable part pushed up by the thermally responsive element, and a bent part formed between the movable contact on the movable part and the fixed part,
The movable arm further has a substantially flat plate-like flat portion between the bent portion and the fixed portion,
The flat portion has a contact pressure between the movable arm and the case on the bent portion side of the fixed portion side contact point between the thermally responsive element reversed at a high temperature and the movable arm pushed up. There is a pressing contact that occurs ,
The breaker contact point is located between the contact point on the fixed portion side of the thermoresponsive element and the movable arm and the bent portion without extending directly above the bent portion .   The breaker according to claim 1, wherein the pressing contact is present between the movable arm and the case at all times during high temperature and low temperature.   3. The breaker according to claim 1, wherein the pressing contact is constituted by a protrusion protruding on an inner surface of a cover portion of the case and the movable arm.   3. The breaker according to claim 1, wherein the pressing contact is constituted by a protrusion raised on the flat portion of the movable arm and the case. 4.   5. The contact pressure and operating temperature between the movable arm and the case according to claim 1, wherein in the step of welding and joining the cover portion of the case to the base portion of the case, the thickness of the case is adjusted. A breaker characterized by adjusting the return temperature.

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