JP4118738B2 - Thermal element and thermo protector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermoprotector for an electronic / electrical device and a thermal element for the thermoprotector.
[0002]
[Prior art]
Elastic stress is used as a thermo protector that detects abnormal heat generation in electronic and electrical equipment, cuts off the equipment from the power supply by cut-off operation based on this detection, prevents the equipment from overheating, and prevents the occurrence of fire. There are stress types and thermal stress types such as bimetal switches.
As the stress type, for example, as shown in FIG. 9A, the elastic metal piece 1 ′ is forcibly bent, and both ends of the bent elastic metal piece 1 ′ are resisted against bending reaction force and a pair of fixed terminals 72 ′. , 72 ′ with a soluble alloy (solder) 2 ′ having a predetermined melting point, the ambient temperature is raised to the melting point of the soluble alloy 2 ′, and the soluble alloy 2 ′ is melted as shown in FIG. As shown in FIG. 2, there is known a method in which the bending stress of the elastic metal piece 1 ′ is released to dissociate the connection between one end of the elastic metal piece 1 ′ and one fixed terminal 72 ′ to cut off the energization.
[0003]
Further, as shown in FIG. 10 (a), a pellet 2 ′ having a predetermined melting point, a seat plate 15 ′, a compression spring 1 ′, and a seat plate 16 from one end side in a metal case 14 ′ having a lead terminal 13 ′ attached to one end. 'Is sequentially accommodated, and the contact 42' whose outer periphery is slidably contacted with the inner surface of the metal case is accommodated, and the lead pin through bushing 17 'is fixed to the other end side of the metal case 14'. A trip spring 18 'is assembled between the lead terminal 13', the metal case 14 ', the contact 42', and the lead pin 41 ', and the ambient temperature is raised to the melting point of the pellet 2'. When the pellet 2 'is melted, the compressive stress of the compression spring 1' is released as shown in FIG. 10B, and the contact 42 'from the tip of the lead pin 41' is released by the compressive stress of the tripping spring 18 '. Release There is also known one that blocks the conduction path at a distance and is called a so-called pellet type thermal fuse.
As described above, a bimetal switch is known as the thermal stress type.
[0004]
[Problems to be solved by the invention]
However, in the stress type shown in FIG. 9, the stress distribution in the soluble alloy (solder) that supports the bending reaction force of the elastic metal piece is complicated, and stress concentration is unavoidable and malfunction due to creep is likely to occur. . In the pellet type shown in FIG. 10, the structure is complicated even if the pellet can be uniformly compressed for pressure equalization by the seat plate, and the disadvantages in terms of downsizing and cost cannot be avoided.
Further, the bimetal type is a return type, and there is a risk that the operating temperature rises with time due to hysteresis as the ON / OFF repetition progresses.
[0005]
An object of the present invention is a composite of an elastic body and a soluble body, and is a thermal element of a type that operates by releasing the stress state of the elastic body by melting the soluble body or a type of thermal element that operates by generation of thermal stress. The purpose is to guarantee long-term stability and to improve the reliability of the operation of a thermo protector using such a thermal element.
[0006]
[Means for solving the problems]
The heat-sensitive element according to claim 1, the porous elastic sheet, or the elastic plate or net-like elastic body having a large number of holes and stress is acting on the porous elastic sheet or the elastic plate having a large number of holes or the net-like shape of the elastic plate. The mesh of the elastic body is deformed, and the hole or the mesh is filled with a soluble material, and a stress commensurate with the stress is generated in the filled soluble material .
[0007]
The heat-sensitive element according to claim 2 is a porous elastic sheet, or an elastic plate or a net-like elastic body having a large number of holes and a tensile stress acting on the porous elastic sheet or an elastic plate having a large number of holes. Alternatively, the mesh of the net-like elastic body is deformed, the hole or the net is filled with a soluble material, and a stress commensurate with the tensile stress is generated in the filled soluble material.
[0008]
The heat-sensitive element according to claim 3 and the heat-sensitive element according to claim 1 or 2, wherein the fusible body is a fusible alloy or a thermoplastic resin.
[0009]
Thermoprotector according to claim 4, having a heat-sensitive element as set forth in any one of claims 1 to 3, characterized in that it operates in the stress release of the elastic body due to melting of the fusible element of the thermosensitive element.
[0010]
The thermo protector according to claim 5 is provided with an insulating film attached to one end of the sheet-like or plate-like thermal element of claim 2, and the insulating film is interposed between the fixed electrode and the movable electrode, The other end of the plate-like thermal element is fixed, and the contact of the electrode is in contact with the hole provided in the insulating film.
[0011]
Thermoprotector according to claim 6 is the thermo-protector according to claim 5, it characterized in that the bimetal movable electrode is used.
[0012]
In the thermoprotector according to claim 7, the fusible alloy piece is connected between the pair of lead conductors or between the electrodes, and the thermosensitive element that shrinks by melting the fusible body of claim 2, the shrinking direction of the fusible alloy piece is It is oriented in the longitudinal direction and bonded to the middle of the soluble alloy piece .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 (a) is a plan view showing an embodiment of the thermal element according to the present invention, FIG. 1 (b) is an enlarged view in the dotted frame of FIG. 1 (a), and FIG. FIG. 2 is a cross-sectional view of FIG.
In FIG. 1, 1 is a perforated elastic plate, 2 is a soluble body filled and solidified in the hole 11 of the perforated elastic plate 1, the perforated elastic plate 1 is in a tensile stress state, and the soluble body 2 is in a compressive stress state. Due to the balance between the tensile stress state and the compressive stress state, the whole is stably held in a planar shape. The size, density, pattern, and the like of the holes are set so that the tensile stress distribution of the perforated elastic plate 1 is made as uniform as possible. Is shifted by a half pitch. The shape of the hole may be a circle, an oval, a triangle, a quadrangle, or the like.
[0014]
The compressive stress [delta] ₂ of the perforated elastic plate 1 of the tensile stress [delta] ₁ and filled fusible second heat-sensitive element, by pulling the perforated elastic plate is stretched by epsilon ₀ in the elastic limit, fusible into a hole in the stretched state , And the tension of the perforated elastic plate is released and the tensile stress δ ₁ and the compressive stress δ ₂ can be obtained from the balance of the forces under the release. The thickness of the plate is equal to the thickness of the filled soluble body, the ratio S ₁ / S ₂ between the cross-sectional area S ₁ of the perforated elastic plate and the cross-sectional area S ₂ of the filled soluble body is S ₁ / S ₂ = n, and the perforated elastic plate When the Young's modulus of E ₁ is E ₁ and the Young's modulus of the filled soluble material is E ₂ ,
δ ₂ = n δ ₁ (1)
[Expression 2]
[1+ (δ ₁ / E ₁ )] = (1 + ε ₀ ) [1− (δ ₂ / E ₂ ) (2)
Is established,
[Equation 3]
δ ₁ = ε ₀ / [(1 / E ₁ ) + (1 + ε ₀ ) (n / E ₂ )] (3)
[Expression 4]
δ ₂ = ε ₀ / [(1 / nE ₁ ) + (1 + ε ₀ ) (1 / E ₂ )] (4)
Given in.
[0015]
Thus, when the fusible body is melted, the Young's modulus E ₂ of the fusible body becomes 0 in the formula (3), the perforated elastic plate becomes the tensile stress δ ₁ to 0, and the perforated elastic plate contracts. Shrinkage rate A is δ ₁ / E ₁ , that is,
A = ε ₀ / [1+ (ε ₀ +1) (nE ₁ / E ₂ )] (5)
Given in.
Therefore, according to the present invention, it is possible to provide a heat-sensitive element that is thermally contracted at a contraction rate A at substantially the melting point of the soluble material.
[0016]
In the present invention, a perforated elastic plate such as a perforated rubber plate, a perforated elastic sheet such as a foamed rubber sheet, or a net of elastic metal wires (a cross point is preferably a rigid joint) can be used as the elastic body. A soluble alloy or thermoplastic resin having a predetermined melting point can be used as the soluble material.
When a fusible alloy is used for the fusible substance, liquefaction starts when the solidus temperature is reached, and the Young's modulus E ₂ decreases rapidly, so that δ ₁ represented by equation (3) can be reduced with high sensitivity. In general, the solidus temperature can be set as the thermal temperature of the present thermal element.
When a thermoplastic resin is used for the fusible body, liquefaction starts when the softening temperature is reached, the Young's modulus E ₂ rapidly decreases, and δ ₁ represented by formula (3) can be reduced with high sensitivity. The softening temperature can be the heat sensitive temperature of the present heat sensitive element.
[0017]
In the embodiment shown in FIG. 1, the center of the distribution of tensile stress acting on the elastic body 1 and the center of the distribution of compressive stress acting on the fusible body 2 are located at the center of the thickness of the thermal element. The force is 0, and a stable flat shape without warping can be maintained.
[0018]
FIG. 2 shows another embodiment of the thermal element according to the present invention.
In FIG. 2, B indicates a heat sensitive element body, and a perforated elastic plate, a perforated elastic sheet, a net elastic body 1 or the like 11 or a net is filled with a soluble body 2 such as a soluble alloy or a thermoplastic resin, and solidified. The above-described tensile stress δ ₁ is generated on the plate, the porous elastic sheet or the net-like elastic body 1, and the above-described compressive stress δ ₂ is generated on the fusible body 2. 3 is a fusible alloy sheet piece or a thermoplastic resin sheet piece adhered to one or both sides of the thermosensitive element body B, and is made of the same material as the above-mentioned filled fusible alloy or thermoplastic resin, or its fusible alloy. Also, those having a slightly lower solidus temperature or those having a slightly lower softening point than the thermoplastic resin can be used.
In this alternative embodiment, even if a couple of forces is inherent in the thermosensitive element main body B, the bending rigidity is increased by sticking the fusible alloy sheet piece or the thermoplastic resin sheet piece 3, so that the entire warp is reduced. It can be suppressed well.
[0019]
In the embodiment described above, the tensile stress of the elastic body is supported by the fusible body to generate a compressive stress in the fusible body. However, the elastic body is in a compressive stress state and the compressive stress of the elastic body is supported by the fusible body. It is possible to generate a tensile stress in the fusible body, and to make the elastic body a stress state in the plus direction shear stress and to support the plus direction shear stress of the elastic body with the fusible body to generate a minus direction shear stress in the fusible body. It is.
[0020]
In order to produce the thermosensitive element according to the present invention, (1) a porous alloy sheet, a perforated elastic plate or a net-like elastic body is stretched with a tensile strain ε ₀ within the elastic limit, and a fusible alloy or A method of immersing and impregnating a thermoplastic resin, and cooling and solidifying the impregnated material to release the stretch tension of the elastic body; (2) a sheet-like soluble alloy sheet or a thermoplastic resin on a porous elastic sheet, a perforated elastic plate or a net-like elastic body; A method in which a resin sheet is stacked and heated and rolled, and the elastic body is stretched and melted and impregnated with a soluble body, and the impregnated material is cooled and solidified and released from rolling; (3) perforated elastic sheet, perforated elastic plate or net-like elastic body It is possible to use a method in which a powder of a soluble alloy or a thermoplastic resin is supplied to the resin, and this is heated and rolled to melt and impregnate the soluble material while stretching the elastic material, and the impregnated material is cooled and solidified to be released from rolling. .
[0021]
FIG. 3 is a view showing an embodiment of the thermo protector according to the present invention. FIG. 3 (a) shows a normally on state, and FIG. 3 (b) shows an off operation.
In FIG. 3, 41 is a fixed electrode, 42 is a movable electrode, and 40 is a contact provided on the movable electrode 42. This contact can also be provided on the fixed electrode side. B is a heat-sensitive element according to the present invention, 5 is an insulating film connected to one end of the heat-sensitive element B, and has a hole 51. Normally, as shown in FIG. The other end of the thermal element B is fixed so that the hole 51 can be moved relative to the contact 40 under the thermal contraction B of the thermal element.
[0022]
When the thermal element B is heated by the surrounding temperature rise and reaches the solidus temperature or softening point T ₁ of the fusible body 2, the insulating film 5 is moved toward the fixed electrode 41 as the thermal element B contracts. Accordingly, the hole 51 is moved relative to the contact 40, and as shown in FIG. 3B, the insulating film 5 is locally intervened in the contact 40 and the contact 40 is insulated and turned off. Put into a state.
Thus, in FIG. 3A, when the moving length of the insulating film that can turn off the contact 40, that is, the contraction length of the thermal element B is ΔL and the length of the thermal element B is L, the equation (5) ) Is set so as to satisfy A ≧ ΔL / L, the thermo-protector can be turned off at the device temperature of the temperature T ₁ to cut off the power to the device.
[0023]
The thermo protector according to the present invention is provided on a substrate, sealed with a case, and implemented in the form of a component in which a terminal of a fixed electrode and a terminal of a movable electrode are derived from the case, a form provided directly on a circuit board, etc. In the latter case, the circuit conductor can be used as a fixed electrode.
[0024]
FIG. 4 is a cross-sectional view showing another embodiment of the thermoprotector according to the present invention. FIG. 4 (a) shows a normal on state, and FIG. 4 (b) shows an off operation state.
In FIG. 4, 41 is a fixed electrode and 42 is a movable electrode. B is a heat sensitive element according to the present invention, 5 is an insulating film connected to one end of the heat sensitive element B, and a contact material 400 is fixed to the insulating film 5 in a normal state, as shown in FIG. The insulating film 5 is interposed between the electrodes 41 and 42 so that the contact material 400 contacts the electrodes 41 and 42, the other end of the thermal element B is fixed, and the contact material is contracted under the contraction of the thermal element B. The contraction rate A of the thermal element shown in Formula (5) is set so that 400 can escape from between the electrodes 41 and 42.
Therefore, when the thermal element B is heated by the surrounding temperature rise and reaches the solidus temperature or the softening point T ₁ of the fusible body 2, the thermal element is contracted toward the fixed electrode 41, and accordingly (( As shown in (b), the contact material 400 is detached from between the electrodes 41 and 42, the contact 400 is insulated by the insulating film 5 and turned off, and the power supply to the device is cut off.
[0025]
FIG. 5 is a cross-sectional view showing another embodiment of the thermoprotector according to the present invention, which is a bimetal type. FIG. 5 (a) shows a switch-on state and FIG. 5 (b) shows a switch-off state. FIG. 5C shows the operation lock state.
In FIG. 5, reference numeral 41 denotes a fixed electrode. Reference numeral 42 denotes a movable electrode, which uses a bimetal. Reference numeral 40 denotes a contact provided on the movable electrode 2 and can be provided on the fixed electrode side as described above. B is a heat sensitive element according to the present invention, 5 is an insulating film connected to one end of the heat sensitive element B, and has a hole 51. In normal times, a film portion in the vicinity of the hole 51 is interposed between both electrodes 41 and 42, The contact 40 is brought into contact with the hole 51, the other end of the thermal element B is fixed, the hole 51 is removed from the contact 40 under the contraction of the thermal element B, and the contact 40 is insulated by the intervention of an insulating film. It is.
[0026]
In FIG. 5, it is assumed that the bimetal movable electrode 42 is set to be turned on / off at a temperature lower than the operating temperature T ₁ of the thermal element B. However, in the bimetal switch, when the cumulative number of on / off operations increases, there is a risk that the operating temperature is shifted to a higher temperature than the original operating temperature. Therefore, in the thermo protector shown in FIG. 5, the thermal element B is contracted under the temperature T ₁ and the contact 40 can be insulated by the intervention of the insulating film 5 as shown in FIG. It can be substantially lock the on-off operation at high temperatures T ₁ than the original operating temperature of the bimetal 42.
[0027]
FIG. 6 is a drawing showing another embodiment of the thermo protector according to the present invention. FIG. 6 (a) shows a normal on state, and FIG. 6 (b) shows an off operation state. Yes.
In FIG. 6, reference numeral 41 denotes a fixed electrode. Reference numeral 42 denotes a movable electrode, which is composed of a laminated body of the thermal element B and the thin metal plate 6 according to the present invention, and is bent outwardly by contraction of the thermal element B. Reference numeral 40 denotes a contact material provided on the fixed electrode 41, and may be provided on the movable electrode 42 side.
[0028]
In this laminate, if the thickness of the thin metal plate 6 is h, the elastic modulus is e, the thickness of the thermal element is t, the elastic modulus is E, and the contraction rate is a, the laminate 42 (movable) due to the contraction of the thermal element B The bending radius r of the electrode) is e >> E, t >> h,
[Formula 6]
r = t [{(E / e) + (h / t) ³ } {(t / h) + (e / E)}] / (6a) (6)
If the bending radius of the bending deformation of the movable electrode 42 necessary for detaching the movable electrode 42 from the fixed electrode 1 is r, the shrinkage rate A of the thermal element at the temperature T ₁ is expressed by Equation 6 below. It is set so as to satisfy a satisfying a.
Therefore, when the heat-sensitive element due to the temperature rise of the ambient is heated to a temperature T _1, as shown in (b) of FIG. 6, the movable electrode 42 and desorbed by the OFF state from the fixed electrode 41 by the bending deformation The
[0029]
FIG. 7 shows an embodiment different from the above of the thermo protector according to the present invention.
In FIG. 7, C is a fuse element in which the thermal element B according to the present invention is bonded to the middle of the fusible alloy piece 3, and the thermal element B alone is the liquidus temperature or softening point of the above-mentioned filled solidified soluble body. It shrinks at T ₁ , and the solidus temperature of the fusible alloy piece 3 is made approximately equal to the liquidus temperature or softening point T ₁ of the filled solidified soluble body of the thermal element B. Reference numerals 71 and 71 denote a pair of flat lead conductors, which are joined to each end of the fusible alloy piece 3 of the fuse element C. Reference numeral 8 denotes a protective case.
This thermoprotector, when the ambient temperature is raised to approximately T _1, a result of the heat-sensitive element B is contracted with fusible alloy piece 3 is melted, soluble between the lead conductor 71 and the heat-sensitive element B The alloy piece part 30 is pulled and cut, leading to a cut-off operation.
[0030]
FIG. 8 shows another embodiment of the thermoprotector according to the present invention, in which a pair of electrodes 72, 72 are provided on an insulating substrate 81, and a lead conductor (a round wire can be used) 71 is provided on each electrode 72. Each end of the fusible alloy piece 3 of the fuse element C in which the heat sensitive element B according to the present invention is bonded to the middle of the fusible alloy piece 3 is joined to each electrode 72, and a protective cover 82 is covered on the substrate 81. The operating mechanism is substantially the same as the embodiment shown in FIG.
[0031]
【The invention's effect】
According to the heat sensitive element of the present invention, in the element that supports the stress of the elastic body in the stress state with the fusible body, releases the stress state of the elastic body by melting the fusible body, and performs the heat sensitive operation by deformation of the elastic body at that time, Since the stress distribution of the fusible body that balances the elastic body stress can be made sufficiently uniform, the creep of the fusible body can be well suppressed and the thermal operation can be stabilized.
In particular, in the heat sensitive element according to the second aspect, since the center of stress of the elastic body and the center of stress of the fusible body can be substantially matched to eliminate generation of couples, a compact form without warping can be achieved.
In the thermo protector according to the present invention, the thermal element is used, and the operation can be stabilized due to the thermal element.
In particular, in the heat sensitive element of claim 6, even if the on / off temperature of the bimetal movable electrode is repeated and the on / off temperature is shifted to a high temperature side due to hysteresis, the heat sensitive element according to the present invention is turned off. Since it can be locked, the safe operation of the bimetal switch can be guaranteed.
[Brief description of the drawings]
FIG. 1 is a drawing showing an embodiment of a thermal element according to the present invention.
FIG. 2 is a drawing showing another embodiment of the thermal element according to the present invention other than the above.
FIG. 3 is a view showing an embodiment of a thermo protector according to the present invention.
FIG. 4 is a view showing an embodiment different from the above of the thermo protector according to the present invention.
FIG. 5 is a view showing an embodiment different from the above of the thermo protector according to the present invention.
FIG. 6 is a drawing showing an embodiment different from the above of the thermo protector according to the present invention.
FIG. 7 is a view showing an embodiment different from the above of the thermo protector according to the present invention.
FIG. 8 is a view showing an embodiment different from the above of the thermo protector according to the present invention.
FIG. 9 is a view showing a conventional thermo protector.
FIG. 10 is a drawing showing another conventional thermo protector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Elastic body 2 Soluble body B Thermal element 3 Soluble body piece 41 Fixed electrode 42 Movable electrode 40 Contact 400 Contact material 5 Insulating film 51 Hole 6 Metal thin plate

Claims (7)

Stress is acting on the porous elastic sheet, or the elastic plate or net-like elastic body having a large number of holes, and the holes of the porous elastic sheet or the elastic plate having a large number of holes or the mesh of the net-like elastic body are deformed. The heat-sensitive element is characterized in that a soluble material is filled in the holes or meshes, and a stress commensurate with the stress is generated in the filled soluble material . The tensile stress acts on the porous elastic sheet, or the elastic plate or net-like elastic body having a large number of holes, and the holes of the porous elastic sheet or the elastic plate having a large number of holes or the mesh of the net-like elastic body are deformed. The heat-sensitive element is characterized in that a soluble material is filled in the hole or mesh, and a stress commensurate with the tensile stress is generated in the filled soluble material. The heat-sensitive element according to claim 1 or 2, wherein the fusible body is a fusible alloy or a thermoplastic resin. A thermo protector comprising the thermal element according to any one of claims 1 to 3, and operating by releasing stress of an elastic body by melting a soluble body of the thermal element. An insulating film is attached to one end of the sheet-like or plate-like thermal element according to claim 2, and the other end of the sheet-like or plate-like thermal element is interposed between the fixed electrode and the movable electrode. Is fixed, and the contact of an electrode is contacted in the hole provided in the said insulating film, The thermo protector characterized by the above-mentioned. The thermoprotector according to claim 5, wherein a bimetal is used for the movable electrode. A fusible alloy piece is connected between a pair of lead conductors or between electrodes, and the heat-sensitive element shrinks by melting the fusible body according to claim 2, the shrinking direction is directed to the longitudinal direction of the fusible alloy piece. A thermo protector characterized by being bonded in the middle of an alloy piece .

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