JP2018166097A - Thermal protector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal protector which can perform electric conduction compensation so as to prevent the instantaneous interruption of a protecting object device of the thermal protector even when contact points instantaneously separate from each other by receiving external force such as drop impact.SOLUTION: A thermal protector includes: a first lead 12 including a fixed contact point 11; a second lead 14 including a movable contact point 13; a thermally-actuated element 15 which changes its shape depending on the temperature and separates the fixed contact point 11 from the movable contact point 13; a heater element 16 whose electric resistance is small at the normal time, and whose electric resistance suddenly increases when the temperature exceeds the specific temperature, and which holds the shape at the operation of the thermally-actuated element 15 during the desired period; and an insulation case 17 which stores the contact points 11, 13, the thermally-actuated element 15 and the heater element 16; and a lid body 18 which covers the opening of the insulation case 17. The heater element 16 is held in the state of being electrically conductible at all times through the first lead 12 and second lead 14, and is conductively fixed to at least one of the first lead 12 and second lead 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermal protector having an instantaneous interruption protection function.

  2. Description of the Related Art Thermal protectors that use bimetal have been conventionally used in power circuit protection devices such as electric motors and secondary batteries. For such a protection device, a contact open / close type thermal protector is used because of the advantages that high-precision operation setting is possible, the operation temperature can be set relatively freely, and the return operation can be repeatedly performed. As a basic configuration of the thermal protector, a first lead terminal having a fixed contact, a movable contact, a movable arm that presses the movable contact against the fixed contact, and a second electrically connected to the movable arm. Lead terminals, a bimetal that operates the movable arm so as to open and close the fixed contact and the movable contact in accordance with a temperature change, and a housing that houses these members. For example, Patent Document 1 discloses that in a thermal protector (breaker 1) in which a fixed piece 3, a movable piece 2, an inversion-type thermal response element 4, and a PTC element (positive characteristic thermistor 5) are accommodated in a flat case 6. The characteristic thermistor 5 and the thermal responsive element 4 are sandwiched between the fixed piece 3 and the movable piece 2, the thermal responsive element 4 covers the upper surface 53 of the positive characteristic thermistor 5, and one side of the thermal responsive element 4 is reversed. There is disclosed a technique for realizing miniaturization by arranging each member in a stacked manner in a state where it contacts the positive characteristic thermistor 5 and the other surface contacts the movable piece 2.

JP 2005-129471 A JP-A-2005-116511 Japanese Patent Laying-Open No. 2006-091854

  The thermal protector has a movable contact in a casing container provided with a first lead having a fixed contact, a movable arm that presses the movable contact against the fixed contact, and a first electrically connected to the movable arm. Two leads, a thermally responsive element such as a bimetal that operates the movable arm so as to open and close the fixed contact and the movable contact with temperature change, and the second when connected to the first lead and the movable contact and the fixed contact are separated. A heating element such as a PTC element that is energized in contact with the lead to control the return operation of the thermally responsive element is accommodated, and the opening of the housing container is sealed with a lid. However, when a device equipped with a thermal protector falls during operation, the impact force when the bimetal or PTC element collides with the movable arm due to the impact of the fall, and the impact force of the movable arm is the elastic force of the movable arm. There was a fear of instantaneous interruption that the contact point was instantaneously released when the value exceeded the value, and the power supply from the power source was cut off for a very short time (several microseconds to several hundred microseconds). For example, in a small PC or a smart phone, an instantaneous power failure is likely to occur due to an impact when it is dropped during use. The instantaneous interruption has the following adverse effects in portable devices such as small PCs and smartphones. For example, a program running on a computer holds data in a volatile memory that keeps storing only during energization. Therefore, there is a possibility that data may be lost if a power interruption occurs. In addition, although hard disks are non-volatile auxiliary storage devices, they are made precisely so if a momentary interruption occurs during reading or writing, there is a possibility that the recording medium may be damaged due to the arm contacting the recording medium. is there. In the case of a momentary interruption during communication, the connection between the two points at that time is disconnected, and it is often necessary to restart the connection from the handshake procedure in order to resume communication. In the case of a system that does not automatically perform such reconnection processing, the connection is disconnected at the time of the momentary disconnection, and reconnection is not performed, which greatly affects data exchange and the like.

  In recent years, thermal protectors having a lower resistance and a stable contact resistance value (low contact resistance) are required as the current capacity of mobile devices increases. In the manufacturing process of the thermal protector, as described in, for example, Patent Document 2 and Patent Document 3, a spark is generated by applying an external force such as vibration while energizing the contact to open the contact, thereby generating a contact surface. In some cases, some kind of contact activation treatment such as removal of oxide is performed. Due to such a contact activation processing step, the conventional thermal protector has been a switching operation method in which the contact is normally closed and the built-in PTC element is energized by being opened during operation. In this system, since the power supply is cut off when the contact is momentarily disconnected when the contact is in a closed state, troubles such as unintended device shutdown are likely to occur.

  The present invention provides a thermal protector having a contact breaking mechanism by reversing the thermal response element, and the contact is instantaneously opened in response to an external force such as a drop impact without using a dedicated protection circuit or a dedicated protective device for instantaneous interruption. It is an object of the present invention to provide a thermal protector capable of compensating for energization so that the protected device of the thermal protector will not be momentarily interrupted even if released.

  According to the present invention, the first lead including the fixed contact, the second lead including the movable contact, the thermally responsive element that changes the shape depending on the temperature and separates the fixed contact and the movable contact, and the normal electric resistance A heat generating element that rapidly increases the electrical resistance when the temperature exceeds a specific temperature and maintains the operating shape of the thermal responsive element for a desired period, and an insulating case that accommodates the two contacts, the thermal responsive element, and the heat generating element; And a cover that covers the opening of the insulating case, and the heating element is held in a state in which current can always be passed through the first lead and the second lead, and at least either the first lead or the second lead. There is provided a thermal protector with a momentary break protection function, characterized in that it is conductively fixed to one side. As the fixing means for conductively fixing the heat generating element to the first lead or the second lead, any means can be used as long as it has a fixing force that can withstand the drop impact of the device equipped with the thermal protector and does not lose continuity. For example, there are means such as caulking, welding, joining with solder or brazing material, adhesion with a conductive adhesive, and the like. In the thermal protector with an instantaneous interruption protection function according to the present invention, the contact is normally closed, and at the same time, the heating element is also energized from the first lead and the second lead. Even if a device equipped with a thermal protector under normal conditions receives a drop impact and momentarily opens a closed contact, a heating element with a small resistance value at the normal temperature is in parallel with the contact pair. Since it is connected, the current supply is compensated through the heating element. In addition, even if the thermal protector of the thermal protector detects the temperature overheat and operates normally and the contact is open, the heating element can be energized, but the resistance of the heating element increases as the ambient temperature increases. The value increases and the heater function is exhibited. Therefore, the heating element of the thermal protector of the present invention is placed in a state in which it can be energized from start to finish regardless of whether the contacts are opened or closed. On the other hand, in the conventional thermal protector, the contact is normally closed, but the heating element is not installed in the energized state, and the thermal actuator detects the temperature abnormality and reverses, and the contact is opened. When the state is reached, the first lead and the second lead including the movable contact are connected via the thermally responsive element, and the state is switched to an energized state. In the past, there was no necessity to install the heating element of the thermal protector so that it could be energized at all times, and there was no thermal protector specifically intended for it. The problem of the present invention was not recognized.

  The thermal protector with a momentary break protection function according to the present invention can cover the power supply compensation for momentary breakage with a single heating element without impairing the resistance characteristics of the contacts in the closed state. For example, since it is not necessary to mount both the PTC element for heat generation and the PTC element for current supply compensation, the configuration can be simplified.

The front sectional view of thermal protector 10 with a momentary break protection function concerning the present invention is shown. The thermal protector 10 with a momentary-break protection function which concerns on this invention is shown, and the top view which removed the cover body of the insulation case of FIG. 1, the movable contact, and the thermal responsive element was shown. The equivalent circuit 30 of the thermal protector with a momentary break protection function according to the present invention is shown, in which (a) shows a thermal protector whose contacts are normally closed, and (b) shows that a device equipped with the thermal protector receives a drop impact. The state when the contact is momentarily opened is shown. The front sectional drawing of the thermal protector 40 with a momentary-break protection function which concerns on this invention is shown, (A) is a thermal protector and a heat generating element before attaching the heat generating element 46, (B) is a thermal protector carrying the heat generating element 46. Show. The thermal protector 40 with a momentary-break protection function which concerns on this invention is shown, and the top view which remove | eliminated the cover of the insulation case of FIG. 4, the movable contact, and the thermal responsive element was shown.

  As shown in FIGS. 1 and 2, the thermal protector 10 with an instantaneous interruption protection function according to the present invention has a first lead 12 including a fixed contact 11, a second lead 14 including a movable contact 13, and a shape depending on temperature. The thermal response element 15 that changes the fixed contact 11 and the movable contact 13 to change, and the electrical resistance increases rapidly when the electrical resistance in normal times is small and exceeds a specific temperature, so that the shape of the thermal response element 15 during operation is changed. A heating element 16 that is held for a desired period, an insulating case 17 that houses the fixed contact 11, the movable contact 13, the thermally responsive element 15, and the heating element 16, and a lid 18 that covers the opening of the insulating case 17. The heating element 16 is held in a state in which current can be always passed through the first lead 12 and the second lead 14 and is conductively fixed to at least one of the first lead 12 or the second lead 14. And wherein the Rukoto. The fixing means for conductively fixing the heat generating element 16 to the first lead 12 or the second lead 14 may be any means as long as it has a fixing force enough to withstand the drop impact of the device on which the thermal protector 10 is mounted and not lose continuity. For example, there are means such as caulking, welding, joining with solder or brazing material, and adhesion with a conductive adhesive.

  In the thermal protector with an instantaneous interruption protection function according to the present invention, as shown in the equivalent circuit 30 of FIG. 3, the contact 31 is normally closed, and the heating element 36 also includes the first lead 32 and the second lead 34. It can be energized. And even if the thermal responsive element of a thermal protector operates and the contact 31 is in an open state, the state in which the heating element 36 can be energized is maintained. Therefore, the heating element 36 of the thermal protector according to the present invention is placed in a state where it can be energized from start to finish regardless of the opening / closing operation of the contact 31. As the heating element 36 of the present invention, any element may be used as long as the resistance value is low at a steady temperature and the resistance value increases when a specific temperature is exceeded. For example, a PTC element (positive characteristic thermistor) is preferably used. The thermal protector of the present invention using a PTC element as a heat generating element has a Curie point lower than the operating temperature and has a resistance value extremely low at a temperature below the Curie point. For example, a low resistance value having a room temperature resistance value of about 1/100 of that of the prior art, and approximately 0.1 to 0.9Ω can be suitably used. As a result, when the thermal protector is at a temperature lower than the operating temperature and the contact is in a closed state, even if the mounted mobile device falls during operation and the contact opens momentarily due to the impact Since a PTC element having a low room temperature resistance can form a bypass path, there is no instantaneous interruption. In addition, since the current-carrying compensation is realized by a single heating element, it is excellent in economic rationality. When the thermal responsive element senses a temperature abnormality and reverses, the heat generating element is maintained in a state where it can be energized. However, as the ambient temperature rises, the PTC element exceeds the Curie point, so the resistance value increases. The heater function as a heating element is exhibited.

  As shown in FIGS. 1 and 2, the thermal protector 10 with a momentary break protection function according to the first embodiment of the present invention includes a first lead 12 made of Cu alloy including a fixed contact 11 made of Ag alloy, and a movable contact made of Ag alloy. 13, a Cu alloy second lead 14, a Ni—Cr—Fe alloy high thermal expansion metal material and a Ni—Fe alloy low thermal expansion metal material laminated bimetallic thermoresponsive element 15, and a PTC element heat generation An element 16; a plastic insulating case 17 that houses the fixed contact 11 and the movable contact 13, the thermally responsive element 15 and the heat generating element 16; and a metal lid 18 that covers the opening of the insulating case 17, and generates heat. The element 16 is held in a state in which current can always be passed through the first lead 12 and the second lead 14 and is conductively fixed to the first lead 12 by solder bonding. The PTC element has a room temperature resistance of 0.1Ω and a trip temperature of 85 ° C., the first lead 12 is soldered to the lower surface electrode, and the thermally responsive element 15 is in contact with the upper surface electrode. Further, the movable contact 13 is brought into contact with the thermoresponsive element 15 from above, and the movable contact 13 and the fixed contact 11 are accommodated in the insulating case 17 in a closed state.

  The present invention is not limited to the embodiment 1 described above, and various other modifications can be made without departing from the spirit of the present invention. For example, it can deform | transform like the thermal protector 40 with a momentary-break protection function of Example 2 shown in FIG. The thermal protector 40 with a momentary break protection function of Example 2 includes a Cu alloy first lead 42 including a fixed contact 41 made of Ag alloy, a Cu alloy second lead 44 including a movable contact 43 made of Ag alloy, and Ni- A heat-responsive element 45 made of a bimetal obtained by laminating a high thermal expansion metal material of Cr—Fe alloy and a low thermal expansion metal material of Ni—Fe alloy, a heating element 46 made of a PTC element, the fixed contact 41 and the movable contact 43 and the heat A plastic insulating case 47 that accommodates the responding element 45 and the heating element 46 and a metal lid 48 that covers the opening of the insulating case 47 are provided. The heating element 46 includes a first lead 42 and a second lead 44. The first lead 42 and the second lead 44 are both conductively fixed by resistance welding. The PTC element has connection leads 49 on the left and right sides of the bottom surface, and the first lead 42 or the second lead 44 is fixed to both connection leads 49 by resistance welding, and is always held in a state where current can be supplied. Since the heating element of Example 2 has connection leads in the horizontal direction, as shown in FIG. 4A, only the heating element can be retrofitted after the contact activation process.

  Here, in order to compare the instantaneous protector resistance of the thermal protector 10 with the instantaneous interruption protection function of the first embodiment of the present invention and the conventional thermal protector, the smartphone equipped with the thermal protector 10 with the instantaneous interruption protection function of the first embodiment. Prepare 25 smartphones and 25 smartphones equipped with conventional thermal protectors. After charging each battery, turn it on and drop it once from the height of 1 meter from the 6th and 4 corners. The number of OFF (instantaneous interruption) occurred was counted. As a result, smartphones using a conventional thermal protector experienced an instantaneous interruption due to a drop impact on 11 of the 250 smartphones. In contrast, none of the smartphones using the thermal protector 10 with the instantaneous interruption protection function of Example 1 had any instantaneous interruption.

  The thermal protector with an instantaneous interruption protection function of the present invention can be used for various power supply protection devices, for example, secondary battery protection devices such as power supply devices and battery packs.

10, 40 ... ・ Thermal protector with instantaneous interruption protection,
30 ... Equivalent circuit,
31 ... Contact,
11, 41... Fixed contact,
12, 32, 42... First lead,
13, 43... Movable contact,
14, 34, 44... Second lead,
15, 45... Thermally responsive element,
16, 36, 46... Heating element,
17, 47... Insulation case,
18, 48... Lid,
49 ··· Connection lead.

Claims (5)

  A first lead that includes a fixed contact, a second lead that includes a movable contact, a thermally responsive element that changes its shape depending on the temperature, and separates the fixed contact and the movable contact; A heating element that rapidly increases the electrical resistance and maintains the operating shape of the thermally responsive element for a desired period, an insulating case that houses the two contacts, the thermally responsive element, and the heating element, and the insulating case And the heating element is held in a state in which current can always be passed through the first lead and the second lead, and the first lead or the second lead. A thermal protector with a momentary break protection function, characterized in that it is electrically conductively fixed to at least one of the above.   2. The thermal protector with an instantaneous interruption protection function according to claim 1, wherein the fixing means for the conductive fixing is selected from the group of caulking, welding, bonding with solder and brazing material, and bonding with a conductive adhesive.   3. The PTC element according to claim 1, wherein the heat generating element is a PTC element having a Curie point lower than an operating temperature and having an extremely low resistance value at a temperature equal to or lower than the Curie point. Thermal protector with instantaneous interruption protection.   4. The thermal protector with an instantaneous interruption protection function according to claim 3, wherein the PTC element has a resistance value in a range of 0.1 to 0.9Ω at a temperature equal to or lower than a Curie point. The thermal protector with a momentary break protection function according to any one of claims 1 to 4, wherein the heat generating element is configured such that only the heat generating element can be retrofitted.

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