JP3138122B2 - switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch used for a protection device against overcurrent and overheating in various electric devices, and more particularly to a switch having a very simple structure with a small number of parts and having stable characteristics. For a switch having

[0002]

2. Description of the Related Art Conventionally, as a switch used for an overcurrent protection device in a motor drive power supply or a temperature control of a heater, various configurations such as a bimetal switch and a heat-sensitive reed switch using a heat-sensitive magnetic material have been used. Are known.

[0003] Recently, due to demands for downsizing and cost reduction of devices, these switches are desired to have a simple structure with as few components as possible and to be excellent in mass productivity. Therefore, many electric devices have a small size and a simple structure as compared with the above-mentioned bimetal type switch and the like, and are relatively inexpensive in mass production and PTC (Po) is a low-cost switch.
sitie temperature coeffi
(Japanese Patent Application Laid-Open Nos. 55-82313 and 55-82313).
98801, JP-A-56-32637, JP-A-61-
No. 234502).

[0004] That is, a PTC element is a conductive polymer in which conductive particles such as carbon black are dispersed, has a positive temperature resistance coefficient, and usually has a low electric resistance. When a current flows or the temperature rises, the state shifts to a high electric resistance state. A pair of electrodes is arranged between the electrodes to constitute a switch.

That is, in the configuration shown in FIG. 11, when current is supplied from terminals 3a and 3b connected to plate electrodes 2a and 2b, the conductive particles in the conductive polymer are dense in a normal use state. However, when the overcurrent flows and the temperature of the PTC element 1 rises, the conductive polymer expands and the contact state of the conductive particles in the conductive polymer changes. The electrical resistance rises and eventually PT
The current flowing through the C element 1 is cut off.

[0006]

As described above, the PTC
Switches using elements have a very simple structure and can be miniaturized, so they are used in various electric devices.However, electric switches such as carbon black, whose electric resistance characteristics are dispersed in a conductive polymer, are used. Because of the influence of the dispersion state of the conductive particles, it is difficult to keep the dispersion state of these conductive particles constant on a mass production scale, the characteristics vary greatly, and the current amount during operation can be arbitrarily set. There was a problem that it was difficult to select.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and has a simpler structure than a switch using the above-mentioned PTC element, has a small number of parts, is excellent in mass productivity, and is stable. It is an object of the present invention to provide a switch having characteristics.

[0008]

According to the present invention, as a result of various studies to achieve the above object, a metal plate and members having different thermal expansion coefficients such as synthetic resin are laminated and integrated, and the difference in thermal expansion between them is reduced. It was found that a structure having a switch function can be obtained by utilizing the structure, and in particular, by devising a laminated integrated structure, the difference in thermal expansion was most effectively utilized to achieve the purpose. .

[0009] Namely, the present invention is a pair of metal plates having a plurality of through-holes, the through-hole of the pair of metal plates, each having a large thermal expansion coefficient than the thermal expansion coefficient of the metal plate and electrically Insulating joint members are connected to each other to be laminated and integrated , and each of the pair of metal plates is connected to a power source.
Connected terminals, and the electric current flowing to the metal plate through the terminals
A switch characterized by separating and contacting opposing surfaces of a pair of metal plates based on a thermal expansion difference between a metal plate heated by a flow and a joining member to open and close an electrical connection. Also,
As a preferred configuration, the present invention also proposes a switch in which the joining member is made of a synthetic resin, and a switch in which at least one of a pair of metal plates is made of a clad material in which a plurality of metal plates are pressed and integrated.

[0010]

The operation of the switch according to the present invention will be described with reference to FIGS.
A description will be given based on one embodiment shown in FIG. FIG. 1 is a perspective explanatory view showing an outline of a switch of the present invention, FIG. 2 is a partial longitudinal sectional view in a case where the switch shown in FIG. 1 is in a closed (ON) state, and FIG. 3 is an open state of the switch shown in FIG. It is a partial longitudinal section explanatory view in the case of (OFF) state. Switch 1 shown
0 is a Kovar alloy plate (29Ni-1) having a plurality of through holes 12a and 12b as a pair of metal plates 11a and 11b.
7Co-residual Fe), and are laminated and integrated by a joining member 13 made of epoxy resin filled in the through holes 12a and 12b, respectively.

Further, terminals 15a and 15b for connecting to a power supply (not shown) are fixedly arranged on both main surfaces (upper and lower surfaces in the figure) of the pair of metal plates 11a and 11b. When the pair of metal plates 11a, 11b and the joining member 13 are integrated, as shown in FIG. 2, the pair of metal plates 11a, 11b
The bonding member 13 made of epoxy resin having electrical insulation is not interposed between the opposing surfaces 21a and 21b, and the bonding member 13 is cured and integrated at room temperature.
That is, the opposing surfaces 21 of the pair of metal plates 11a and 11b
a and 21b are integrated in a state where they are in direct contact with each other.

Therefore, when a current is applied to the switch 10 through the terminals 15a and 15b, a predetermined current is not
The state of FIG. 2 is maintained, and the switch is closed (ON). However, when the current flowing through the switch 10 exceeds a certain amount, the joining member (epoxy resin) 13 is heated together with the metal plates 11a and 11b, and their thermal expansion difference (the coefficient of thermal expansion of the metal plates 11a and 11b < Based on the thermal expansion coefficient of the member 13, as shown in FIG.
a, 11b are separated from each other by a gap (L
g) 14 is formed, and as a result, electrical conduction is interrupted. That is, the switch is opened (OFF).

In the above description, the case where the switch 10 is heated by energization has been described.
Are provided, and have the same effect when heated by a rise in the temperature of the atmosphere. That is, it is understood that the switch of the present invention can be used for a protection device or the like against overcurrent or overheating.

The pair of metal plates constituting the switch of the present invention may be made of a material having a smaller coefficient of thermal expansion than that of the joining member disposed in the through hole formed in the metal plate. Well, for example, Al, Cu, Ni,
In addition to a metal plate made of Fe and a metal plate made of an alloy containing these as a main component, an Fe-Ni-Co alloy, Fe-Ni-C
A metal plate made of a low thermal expansion alloy such as an r alloy, an Fe-Ni alloy, and an Fe-Cr alloy, and a metal plate made of a clad material obtained by pressing and integrating a plurality of materials having different thermal expansion coefficients can be applied. . The shape is not limited to a rectangular plate shape as shown in the figure, but is desirably selected in accordance with an arrangement condition such as a disk shape.

The shape of the through-holes formed in these metal plates is not limited to a perfect circular cross section, but may be an elliptical shape, a triangular shape, a short shape, or the like in consideration of workability, joining strength with a joining member, and the like. It is desirable to select various shapes. Also, the size of the through hole not only affects the joining strength with the joining member,
The value of the current flowing through the switch is defined, and it is desirable to select the size of the through hole, that is, the aperture ratio according to the purpose of use.

The configuration for defining the value of the current flowing through the switch according to the present invention includes not only the aperture ratio of the metal plate but also the shape of each of the opposing surfaces of the metal plate being a simple flat surface. It can also be adjusted by forming a plurality of projections or projections on at least one of the opposing surfaces to adjust the size of the contact surface when the switch is closed (ON).

A joining member for laminating and integrating a pair of metal plates is only required to have a coefficient of thermal expansion larger than the coefficient of thermal expansion of each metal plate and be electrically insulating.
Considering the workability when laminating and integrating a pair of metal plates, and the difference in thermal expansion coefficient, etc., a synthetic resin such as an epoxy resin, a phenol resin, a urea resin, a melamine resin, and an ABS resin is preferable. Urethane,
It is also possible to use polyamide, polyimide, rubber and the like.

In order to increase the bonding strength between the pair of metal plates and the bonding member, the shape of the through-hole formed in the metal plate is devised as described above, or the roughness of the inner peripheral surface of the through-hole is increased. For example, as shown in FIG. 4, tapered portions 22a and 22b are formed on the opening side of each through-hole 12, or as shown in FIG. Head 13 having an outer diameter larger than the inner diameter of hole 12
a, 13b, and further, as shown in FIG.
A configuration in which the metal plate covering portions 13c and 13d are formed so as to cover both main surfaces of the pair of metal plates 11a and 11b can be adopted.

FIGS. 7 and 8 show one embodiment of a configuration for adjusting the size of the contact surface of each of the opposing surfaces of the pair of metal plates.
In FIG. 7, a configuration in which a plurality of protrusions 23a, 23b each having a width W is formed on the facing surface of each of the metal plates 11a, 11b, and in FIG. 8, a plurality of protrusions 24a, on each of the facing surfaces of the metal plates 11a, 11b. 24 shows a configuration in which 24b is formed. FIGS. 9 and 10 show one embodiment having a configuration in which a pair of metal plates are each formed as a clad plate.
A configuration in which e-Ni-Co alloy plates 11a and 11b are arranged, and a Cu plate 11a 'and 11b' having a small electric resistance are arranged on the opposing surface side, and a Cu plate 11a 'arranged on the opposing surface side in FIG. 10 further. , 11b 'show a configuration in which a plurality of protrusions 25a, 25b having a width W are formed.

The switch of the present invention is not limited to the configuration of the embodiment described above. The material and shape of the joining member made of a pair of metal plates and a synthetic resin or the like may be selected according to the required switching characteristics. Various configurations can be adopted by selecting dimensions, dimensions, and the like.

[0021]

【Example】

Example 1 As shown in FIG. 1, a plurality of through holes 12 each having a hole diameter D of 0.8 mm were formed so that an opening ratio became 34.1%, and each side was 15 mm, and a thickness (t ₁ , t ₂ ) 0 was zero. A pair of square Cu plates 11a, 11b (coefficient of thermal expansion: 160 × 10
^-7 / ° C., 0 to 100 ° C.) into the through hole 12 to form a joining member 13 made of epoxy resin (thermal expansion coefficient: 2.
(6 × 10 ⁻⁴ / ° C., 0-100 ° C.) was cured at room temperature and laminated and integrated to prepare the switch 10 of the present invention. Connect a 3V dry battery between terminals 15a and 15b,
When the lamp was turned on, the switch was placed in the furnace and the temperature in the furnace was raised. That is, the switch is closed (ON)
The state was shifted from the state to the open (OFF) state, and that state was maintained. The same experiment was repeated several times with similar results.

Embodiment 2 As shown in FIG. 9, the width and length are each 10 × outside.
20 mm, the thickness (t _11, t ₂₁₎ the electrical resistance of the 0.425mm high rectangular as an Fe-Ni-Co alloy plate 11a, 11b
(Coefficient of thermal expansion: 12 × 10 ⁻⁷ / ° C., 0 to 100 ° C.), and the width and length are 10 × 20 mm and the thickness (t ₁₂ , t ₂₂ ) is 0.025 mm on the facing surface side. C with small resistance
u plates 11a ', 11b' (coefficient of thermal expansion: 160 × 10 ^-7)
/ ° C, 0 to 100 ° C) and a pair of clad plates (t ₁ = t ₂ = 0.45 mm) having a hole diameter D of 1.
A plurality of through holes 12 each having a diameter of 5 mm have an aperture ratio of 22.4%.
And a joining member 13 made of epoxy resin (thermal expansion coefficient: 2.6 × 10 ⁻⁴ / ° C., 0 to 10) so as to cover both main surfaces of the clad plate together with the inside of the through hole 12.
(0 ° C.), cured at room temperature, and laminated and integrated to prepare a switch of the present invention. Terminals 15a, 15
The DC current was gradually increased while applying a predetermined DC current for a certain period of time between b. When a DC current of 12 V × 20 A was applied, the switch was closed (ON) and opened (OFF) in 15 seconds. ) State and maintained that state.
Similar experiments were repeated several times with similar results.

[0023]

According to the present invention, as is apparent from the above-described embodiment, the switching characteristic with reproducibility, the number of parts is small, and the mass productivity is excellent despite the very simple structure. Moreover, it is possible to provide a switch having stable characteristics.

[Brief description of the drawings]

FIG. 1 is a perspective explanatory view showing an outline of a switch according to an embodiment of the present invention.

FIG. 2 is an explanatory longitudinal sectional view showing a state in which a switch of FIG. 1 is closed (ON).

FIG. 3 is an explanatory longitudinal sectional view showing a state where a switch shown in FIG. 1 is open (OFF).

FIG. 4 is an explanatory longitudinal sectional view showing another embodiment of the present invention.

FIG. 5 is an explanatory longitudinal sectional view showing another embodiment of the present invention.

FIG. 6 is an explanatory longitudinal sectional view showing another embodiment of the present invention.

FIG. 7 is an explanatory longitudinal sectional view showing another embodiment of the present invention.

FIG. 8 is an explanatory longitudinal sectional view showing another embodiment of the present invention.

FIG. 9 is an explanatory longitudinal sectional view showing another embodiment of the present invention.

FIG. 10 is an explanatory longitudinal sectional view showing another embodiment of the present invention.

FIG. 11 is an explanatory longitudinal sectional view showing an outline of a conventional switch.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 PTC element 2a, 2b Plate-shaped electrode 3a, 3b Terminal 10 Switch 11a, 11b Metal plate 11a ', 11b' Cu plate 12, 12a, 12b Through hole 13 Joining member 13a, 13b Head 13c, 13d Metal plate coating part 14 Air gap 15a, 15b Terminal 21a, 21b Opposing surface 22a, 21b Tapered portion 23a, 23b, 24a, 24b, 25a, 25b Projected portion

Claims (3)

(57) [Claims] The method according to claim 1 the metal plate of a pair having a plurality of through-holes,
The through hole of the pair of metal plates, with integrally laminated by a bonding member having each have a large thermal expansion coefficient than the thermal expansion coefficient of the metal plate and electrically insulating arranged communicated, before
A terminal connected to a power supply is arranged on each of the pair of metal plates,
A pair of a pair of metal plates is formed based on a difference in thermal expansion between the metal plate and the joining member heated by a current flowing through the metal plate via the terminal .
A switch that opens and closes an electrical connection by separating and contacting the facing surface . 2. The switch according to claim 1, wherein the joining member is made of a synthetic resin. 3. The switch according to claim 1, wherein at least one of the pair of metal plates is a clad material formed by pressing and integrating a plurality of metal plates.