JPH0677424B2 - Thermostat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is used for the purpose of preventing overheating of heat-generating devices such as hair dryers and tableware dryers or small electric motors used for electric washing machines, electric shutters, etc. The small thermostat used is easy to manufacture and has improved durability of the bimetal.

<Prior Art> Conventionally, there are the following thermostats using a bimetal.

(1) Japanese Patent Publication No. 55-6971, No. 51-5704, No. 51-1
The contact spring itself is made of a bimetal material as shown in Japanese Patent No. 8069. (2) The bimetal is almost parallel to the contact spring as shown in Japanese Patent Publication No. 56-31694 and Japanese Utility Model Publication No. 58-40505. (3) Japanese Patent Publication No. 59-22332 and Japanese Utility Model Publication No. 58-46512, in which a reverse bimetal is interposed between the base for fixing the contact spring and the contact spring. .

By the way, the contact spring was made of bimetal material (1)
In general, the operating temperature at a steady current and the operating time at an overcurrent are set by experiments by appropriately selecting the operating temperature of the bimetal at a no-load current. However, it is difficult to set both the operating temperature at the steady current and the operating time at the overcurrent to desired values due to Joule heat generation of the current flowing in the bimetal.

Further, in the case of the structure (2) in which the bimetal is attached to the contact spring, the bimetal is caulked to the base together with the contact spring, so that the bimetal is subjected to initial stress during caulking. Then, this initial stress causes the temperature setting to change. In order to recycle products that have become defective in the inspection process,
It is inconvenient because the bimetal from which the crimping part has been removed must be replaced.

Further, the case of (3) using the inverted bimetal which is not caulked does not have the above-mentioned problems of temperature characteristic change and bimetal replacement. However, when the effective stroke at the time of reversal is small, there is a drawback that the contacts cause chattering and malfunction.

Therefore, the present applicant previously developed and applied for a thermostat using inverted bimetal with good temperature characteristics (see Japanese Utility Model Publication No. 55-36549). That is, this thermostat has one end in the notch on the one end surface of the ceramic base recess,
The reverse bimetal is positioned so that the other end is supported by the pin implanted on the base surface, and the contact spring is controlled by the reverse operation of the same bimetal piece. A very sensitive response was obtained, which was satisfactory in terms of operation.

In addition, there is also one using an inverted bimetal as disclosed in JP-A-53-68882 (JP-B-56-22094). In this publication, notches are formed on both sides of the inverted bimetal, bimetal guide protrusions are provided on the movable contact plate, and the guide protrusions are inserted into the notches to position the bimetal. .

<Problems to be solved by the invention> However, these are troublesome to manufacture because the grooves and notches formed in the bimetal must be inserted into the pins of the base and the convex portions of the movable contact plate in the manufacturing process. is there. Moreover, because grooves and cutouts are formed in the bimetal,
Due to the notch effect, there is a defect that the bimetal is damaged by cracking from this portion.

In other words, in order to make a thermostat that is easy to manufacture and has good durability, it is possible to easily position and fix the reversal bimetal during manufacturing, and to prevent the position of the reversal bimetal from moving during operation. The shape must be such that cracks due to the notch effect do not occur.

<Means for Solving Problems> Therefore, in order to solve the above-mentioned problems, the thermostat according to the present invention is for a reversing bimetal in which at least four corners of the reversing bimetal to be housed are locked with some play. The storage locking recess is formed on the surface of the heat-resistant insulating base, and the movable contact is fixed to the contact spring that has the movable contact at the tip and the protrusion protruding toward the storage locking recess in the middle part. The other end of the contact spring is arranged on the base so that it can be opened and closed with respect to the contact, and an inverted bimetal without a notch, groove, etc. in the periphery is stored in the storage recess, and the high expansion side is the protrusion of the contact spring. The contact spring is placed between the contact spring and the base, and the contact spring is formed with a locking claw to prevent the inverted bimetal from jumping out from the housing locking recess. It is only necessary to place it in the storage locking recess of the base, and it is also possible to prevent the reverse bimetal from being displaced or jumping out of the thermostat due to the functions of the storage locking recess and the locking claws during operation. Moreover, the inverted bimetal can be used in a simple shape having no notches or grooves in the periphery so that damage due to the notch effect does not occur.

<Example> Next, an example of a thermostat according to the present invention will be described with reference to the drawings. 1 is a base made of a heat-resistant insulating material such as ceramic, and 2 is a substantially hexagonal shape drawn into a curved plate shape. It is an inverted bimetal of No. 1, and no special shape for positioning such as a notch or a groove is formed around it.
Reference numeral 3 denotes a contact spring having a movable contact 4 at one end, a protrusion 5 at an intermediate portion, and a locking claw 6 formed therebetween.

A storage locking recess 7 for locking the storage of the inverted bimetal 2 is formed on the central surface of the base 1. The storage locking recess 7 is shaped so that at least the four corners of the reversing bimetal 2 can be locked so that the reversing bimetal 2 does not move in the front-rear, left-right direction, that is, in the horizontal direction. In the illustrated example, since the inverted bimetal has a substantially hexagonal shape, the storage locking recess 7
Also fits this shape. The storage locking recess 7 is formed to be slightly larger than the size of the reversal bimetal 2 so as not to disturb this movement when the reversal bimetal 2 is reversed, and the reversal bimetal 2 is stored in the storage locking recess 7. If so, allow some play. Reference numeral 8 is a through hole formed in the central portion of the storage locking recess 7 of the base 1,
Ventilation with respect to the inverted bimetal 2 is improved so that a sensitive operation can be obtained.

In the storage locking recess 7 of the base 1, the inverted bimetal 2 is arranged so that the high expansion coefficient side 9 contacts the projection 5 of the contact spring 3 and the low expansion coefficient side 10 contacts the base 1 surface. is there.
Since the storage locking recess 7 is matched with the shape of the inverted bimetal 2, the positioning can be accurately performed by simply dropping the reverse bimetal 2 into the storage locking recess 7 during manufacturing.

A rivet hole 11 for attaching the contact spring 3 is formed at one end of the base 1, and a terminal plate 13 having a fixed contact 12 is provided at the other end. The contact spring 3 is caulked by the conductive rivet 14, and the terminal plate 15 is also caulked by the same rivet 14 on the side opposite to the contact spring 3 to ensure the continuity between the contact spring 3 and the terminal plate 15. ing.

In the illustrated example, the locking claw 6 of the contact spring 3 is formed by cutting a part of the contact spring 3 into a rectangular shape on three sides and bending the remaining one side. In this way, the locking claw can be easily formed, but it may not be necessary in some cases. When the inverted bimetal 2 is inverted and the contact spring 3 is deformed so that the movable contact 4 is separated from the fixed contact 12, the locking claw 6 is provided with the inverted bimetal 2 on the base 1.
It is to prevent the lower end 16 of the locking claw 6 from being lower than the upper surface 17 of the storage locking recess 7 even when the contact spring 3 is deformed. There is a need. In addition, the locking claw 6 may be formed on the side of the contact spring where the rivet 14 is fixed or on the side of the contact spring. It may be provided at a required location depending on the shape of the inverted bimetal 2 used and the depth of the storage locking recess 7.

As shown in the drawing, in the storage locking recess 7 of the base 1, the locking pawl 6 of the contact spring 3 is locked one step further than the storage locking recess 7 so as not to interfere with the operation of the inverted bimetal 2 in the normal state. The groove 18 for the claw 6 may be formed in advance. With this arrangement, since the position of the reversing bimetal 2 is regulated by the storage locking recess 7, the locking claw 6 will not rotate when the movable claw 6 and the fixed contact 12 are in contact with each other. Since it does not come into contact with 2, it effectively obstructs the operation of the inverted bimetal 2.

In some cases, if the contact spring 3 is made of a material having a large electric resistance, the reversal bimetal 2 can be operated not by the ambient temperature but by the heat generation of the overcurrent.

<Operation> Then, the thermostat of the present invention is attached to a device,
Connect wires to terminals 13 and 15 and apply current. In a normal state, current flows in the order of terminal 15 → contact spring 3 → moving contact 2 → fixed contact 12 → terminal 13. When the temperature exceeds the set temperature, the reversal bimetal 2 operates to separate the movable contact 4 from the fixed contact 12 and open the electric circuit. Inverted bimetal 2
The position is regulated horizontally by the storage locking recess 7, and the projection 5 of the contact spring 2 and the locking claw 6 are moved vertically.
Since the reverse bimetal 2 is not locked to the base 1 as in the conventional case, the reverse bimetal 2 does not jump out from the base 1.

<Effects of the Invention> As described above, according to the thermistor of the present invention, since the storage locking recesses are formed in the base such that the four corners of the inverted bimetal are locked with some play,
The inverted bimetal can be easily stored at a predetermined position during manufacturing, the manufacturing process can be simplified, and the position of the inverted bimetal does not shift due to the action of the storage locking recess and the locking claw during operation. By devising the storage locking recess and locking claw, it is not necessary to provide a notch or groove around the reversal bimetal, so that the shape of the reversal bimetal can be made a highly durable shape, which is extremely effective.

[Brief description of drawings]

FIG. 1 shows an embodiment of a thermostat according to the present invention. FIG. 1 is an exploded perspective view, FIG. 2 is a plan view, FIG. 3 is a sectional view taken along line AA of FIG. 1, and FIG. Bottom view, FIG. 5 is an explanatory view showing the normal operating state, FIG. 6 is a plan view of the base, FIG. 7 is a sectional view taken along the line BB of FIG. 6, FIG. 8 is a plan view of the inverted bimetal, and FIG. 9 is It is a side view of an inversion bimetal. DESCRIPTION OF SYMBOLS 1 ... Base 2 ... Reverse bimetal 3 ... Contact spring 4 ... Movable contact 5 ... Protrusion 6 ... Locking claw 7 ... Storage locking recess 8 ... Through hole 9 ... High expansion rate side 10 ... Low expansion rate side 11 ... Rivet hole 12 ... Fixed contact 13,15 ... Terminal plate 14 ... Rivet 16 ... Locking claw bottom 17 ... Storage locking recess upper surface 18 ... Groove

Claims (4)

[Claims] 1. A storage locking recess for a reverse bimetal is formed on the surface of a heat-resistant insulating base such that at least the four corners of the stored reverse bimetal are locked with a slight amount of play. The other end of the contact spring is arranged on the base so that the movable contact can be opened and closed with respect to the fixed contact, and the contact spring having a protrusion protruding in the middle toward the storage locking recess is arranged around the base. Inverted bimetal without cutouts or grooves is placed between the contact spring and the base so that the high expansion coefficient side comes into contact with the protruding portion of the contact spring in the storage locking recess, and the inverted bimetal is stored in the contact spring. A thermostat, characterized in that a locking claw is formed so as to prevent the locking claw from jumping out. 2. The thermostat according to claim 1, wherein the engaging claw of the contact spring is formed so that a part of the contact spring is bent. 3. The thermostat according to claim 1, wherein the center of the inverted bimetal housing locking recess of the base is a through hole. 4. The thermostat according to claim 1, wherein a groove for a locking claw of the contact spring is formed in the housing locking recess of the base.