JPH0696649A - Thermal protector for three phase - Google Patents

Abstract

PURPOSE:To provide a thermal protector which is small-sized, easy to be manufactured, and is provided with two pairs of movable contacts and fixed contacts. CONSTITUTION:A thermal protector is provided with fixed contacts respectively connected to two current-carrying pins which are insulatingly fixed to a cover plate 1 for a sealed container. An operating temperature calibration plate 8 in which a pressing part 8F is installed and a thermally-actuated plate support body 9 are fixed to a cover 7. The thermally-actuated plate 11 snappingly operating at a predetermined temperature is inductively fixed to the thermally-actuated plate support body 9. Two movable contacts are fixed to the thermally-actuated plate 11 symmetrically about a center line at the aforementioned fixed contacts so that two pairs are possible to approach to/separate from each other respectively. The pressing part 8F presses a part of the center line on the side which forms a projection at an ordinary temperature, of the thermally-actuated plate 11. A stationary member 6 supports a part in the vicinity of the fixed end on the center line of the thermally-actuated plate 11. Forces applied to the parts between two pairs of the contacts are approximately equal to each other and the contacts are opened/closed simultaneously at predetermined different temperatures. Calibration of the operation temperature is performed by displacing the curved part of the cover 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-phase thermal protector for simultaneously opening and closing the middle point of a three-phase induction motor by Y connection or a similar type of protector suitable for protecting equipment.

[0002]

2. Description of the Related Art Conventionally, as a three-phase thermal protector of this type, there is a "plate-shaped bimetal relay with three contacts" disclosed in Japanese Utility Model Publication No. 31-5747, and Japanese Patent Publication No. 46-3453.
There is a "thermostat switch" etc. shown in No. 2, but in each case it is uneconomical to use 3 movable contacts and 3 fixed contacts each. Further, Japanese Patent Application Laid-Open No. 1-105435, which is filed by the same applicant as the present application, discloses a "three-phase thermal protector" capable of using two moving contacts and two fixed contacts, but the temperature adjusting mechanism is The use of screws requires high processing accuracy, the number of parts is large, and the temperature calibration error is corrected after welding and sealing the board and lid after temperature calibration. There was a drawback that it was impossible to do.

[0003]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned problems and requires a total of four fixed contacts and movable contacts in total of two pairs, which is easy to manufacture in a small size, and the operation of the heat responsive plate. The temperature can be calibrated precisely after it is completed as a closed container, and the heat generating part is installed almost in parallel with the heat responsive plate to prolong the off-time, so that a stable heat responsive switch with long life can be made inexpensive. JP-A-1-105435, which is provided, and has pressure resistance that the airtight container is not deformed by a pressure applied from the outside.
It is intended to provide a novel three-phase thermal protector relating to the improvement of No.

[0004]

In the three-phase thermal protector of the present invention, a hermetically sealed container is constituted by a metal cover having a depth shallower than the width of the opening and a lid plate welded to the end face of the opening. It The cover plate is provided with two through holes at predetermined positions, and conductive pins are airtightly fixed to the through holes by an electrically insulating filler such as glass penetrating the cover plate. Fixed contacts are respectively fixed to the conductive pins directly or via fixed contact supports,
The fixed contact support is welded and fixed substantially parallel to the cover plate. One end of an operating temperature calibration plate having a portion in the vicinity of the fixing portion of the cover in the vicinity of the fixing portion and having a shape relatively easy to bend in the direction orthogonal to the plane is welded and fixed, and the operating temperature calibration plate is further attached. One end of a metal-made heat-responsive plate support having elasticity that is highly rigid in the direction along the plane and relatively easily bent in the direction orthogonal to the plane is fixedly attached to the heat-responsive plate support. A heat responsive plate is fixed to the other end of the. The heat-responsive plate is made of a material such as a bimetal that deforms in response to a change in temperature and is formed into a substantially circular shape. Two movable contacts are fixed by welding or the like symmetrically with respect to the center line including the fixed end with the plate support, and the movable contacts are arranged so as to face the fixed contacts and come into contact with or separate from them. . The operating temperature calibration plate is provided with a pressing portion for operating temperature calibration, and the pressing portion presses a portion of the heat responsive plate that is convex at room temperature. A stationary member having sufficient rigidity is disposed on the cover plate so as to come into contact with the vicinity of the fixed end of the thermal responsive plate, and the stationary member thermally responsively moves near the fixed portion of the thermal responsive plate and the thermal responsive plate support. By supporting on the center line of the plate, the heat-responsive plate is constructed so that the pressing force received from the pressing portion is dispersedly supported by the stationary member and the two fixed contacts, and is applied between the two pairs of contacts. The force applied between the contact points is applied through the operating temperature calibration plate by deforming the curved portion of the cover, and the thermal response plate snaps at different predetermined temperatures. When the reversing operation is performed, the two movable contacts are configured to be opened and contacted with the fixed contacts substantially at the same time.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. 1 to 3, the cover plate 1 has an oval planar shape in which both ends of a generally semicircular shape are connected by linear portions, and the thickness thereof is thicker than that of a cover described later. Through holes 2A and 2B are formed at the predetermined positions so as to be positioned symmetrically with respect to the longitudinal centerline of the cover plate 1. In each of the through holes, conductive pins 3A and 3B penetrate the cover plate and are hermetically fixed by fillers 4A and 4B of an electrically insulating material such as glass.
Fixed contacts 5A and 5B made of silver, a silver alloy, or the like are fixed to end surfaces of the conductive pins 3A and 3B, which will be described later inside the closed container.

A stationary member 6 having a portion serving as a support point for a heat responsive plate, which will be described later, is disposed on the inner side of the cover plate 1 which will be described later.

The cover 7 is formed into a long dome shape having a depth smaller than the width of the opening and a flat portion near the center thereof. The cover plate 1 and the opening end surface thereof are ring projection welded. And the like to form an airtight container. An operating temperature calibration plate 8 is welded and fixed to the inside of the closed container of the cover 7. As shown in FIG. 4, the operating temperature calibration plate 8 has ribs 8A to 8D on the entire surface thereof.
Is provided to provide sufficient rigidity, and a narrowed portion 8E is provided in the vicinity of the fixed portion with the cover so as to be easily bent at the time of operating temperature calibration described later. Further, the operating temperature calibration plate 8 is provided with a pressing portion 8F which is cut and raised so as to penetrate through a heat responsive plate support which will be described later and come into contact with a heat responsive plate which will be described later. Further, in the vicinity of the fixed portion of the operating temperature calibration plate 8, the rigidity in the direction along the plane is high, and one end of the metallic heat responsive plate support 9 having elasticity that can be bent relatively easily in the direction orthogonal to the plane. Is fixed. Thermal plate support 9
The hole 9A is formed in the hole, and the pressing portion 8F of the operating temperature calibration plate 8 is provided so as to penetrate the hole 9A.

The other end of the heat responsive plate support 9 is made into a generally circular shape by a material such as a bimetal or a trimetal that deforms in response to a change in temperature through a lug plate 10 for welding, and is drawn into a dish shape. The heat responsive plate 11 is configured to perform a snapping reversal operation at different predetermined temperatures.
Is fixed. Further, the fixed portion between the heat responsive plate 11 and the lug plate 10, the lug plate 10 and the heat responsive plate support 9
Symmetric with respect to the center line on the heat-responsive plate including the fixed part with
Further, two movable contacts 12A and 12B are fixed by welding or the like so as to be able to open and close with the fixed contacts 5A and 5B described above.

The heat responsive plate 11 is adapted to the predetermined operation and return reversal temperature after the movable contacts 12A and 12B and the lug plate 10 are welded after drawing and then aging is performed at, for example, 300 ° C. Is used. The lug plate 10 is necessary in order to prevent this point because when the heat-responsive plate 11 is directly welded after aging, the heat thereof causes some changes in the operating temperature and the returning temperature. However, it is possible to perform aging after welding the heat responsive plate 11 and the heat responsive plate support 9, or the operating temperature and the return temperature when the heat responsive plate 11 is directly welded to the heat responsive plate support 9 after the aging process. The lug plate 10 may be omitted if some variation is not a concern.

Further, the heat responsive plate 11 is supported near the fixed end on the center line thereof at a support point 13 by the tip of the stationary member 6 described above. Although the lug plate 10 is used in this embodiment, it does not affect its effect and operation.

To calibrate the operating temperature, after the airtight container is completed, jigs G1 and G2 for sandwiching the cover plate 1 and the cover 7 as shown in FIG. The curved portion 7A of the cover 7 is crushed and deformed so that the curved direction is reversed as shown by. As a result, the narrow portion 8E of the operating temperature calibration plate 8 is bent and deformed downward in the drawing, and a pressing force is applied to the side of the thermal responsive plate 11 that is convex at room temperature via the pressing portion 8F. This pressing force is supported by the three fixed contacts 5A and 5B and the supporting point 13 at the tip of the stationary member 6, and the contact pressure is increased by the deformation of the cover 1 described above, so that heat is generated at a predetermined operating temperature. The response plate 11 is reversed in a snap manner. At this time, the force of the heat responsive plate support 9 on the heat responsive plate 11 is generated in the vicinity of the fixed end of the heat responsive plate 11 at the bearing point 1
3 is pressed against the tip of the stationary member 6 and its supporting point 13
Therefore, in FIG. 1, a biasing force that tilts clockwise is applied. Therefore, the movable contact can be reliably separated from the fixed contact when the heat responsive plate 11 is reversed, and chattering at the time of separating the movable contact from the fixed contact is eliminated by the snap-like reversing operation of the heat responsive plate. , Can be calibrated to a given operating temperature.

At this time, since the contact points of the fixed contact and the movable contact are positioned symmetrically with respect to the straight line connecting the pressing portion 8F and the support point 13, the reaction force is almost evenly applied to the two movable contacts. As a result, the contacts will open almost simultaneously. Further, since the heat responsive plate 11 is supported via the heat responsive plate support 9 having elasticity that can be bent relatively easily in the direction orthogonal to the plane, the heat responsive plate is inclined due to an error during assembly. Even if there is, the bias of the reaction force exerted between the two contacts can be absorbed by the heat responsive plate support, thus enabling so-called self-centering to make the reaction force almost even.

Further, a pressing portion 8F is provided via the operating temperature calibration plate 8.
Therefore, by adopting a structure that applies a pressing force to the heat responsive plate 11, more precise adjustment can be performed as compared with a case where the operating temperature calibration plate is not used. That is, in this embodiment, as shown in FIG. 5, the portion 8 serving as a fulcrum when the operating temperature calibration plate 8 is bent.
The distance between E and 7A, which is the point of action of the force exerted by the jigs G1 and G2 for temperature control, is the pressing portion 8F and the fulcrum portion 8E.
Since the distance is more than twice as large as the distance between and, the displacement amount of the pressing portion 8F is less than half of the crushing amount of 7A by the principle of the lever and the portion having the pressing portion is directly displaced. A precise temperature calibration becomes possible as compared with. Further, when the crush deforming portion of the cover 7 is located near the contact shown by 7B in FIG. 5, the contact crush distance becomes shorter when the contact is opened as the crushing amount increases. There is a need. If the crushed deformed portion of the cover 7 is located at a position 7A opposite to the contact position, the contact distance can be maintained at an appropriate value regardless of the crush amount of the cover when the contacts are opened. Moreover, the crushed deformed portion 7A is a curved portion having a long dome shape, and the deformation amount by the jig G1 is very small in springback, and the deformed shape of the cover 7 has pressure resistance when pressure is applied from the outside. This is a positionally favorable part where there is almost no loss.

In the three-phase thermal protector constructed as described above, the heat responsive plate 11 snaps suddenly inversion as shown by the dotted line in FIG. Reference numeral 11 is an appropriate position regulated by ribs 8A and 8B provided on the operating temperature calibration plate 8 and simultaneously separates the movable contacts 12A and 12B from the fixed contacts 5A and 5B, and a second predetermined temperature lower than the first temperature. When the temperature reaches, for example, 90 ° C., the coil jumps back to the state shown by the solid line and the contacts are closed at the same time.

When some abnormality occurs in the electric motor to be protected and its current increases, heat generation of the heat responsive plate 11 and other members forming each electric path increases, and the operating temperature of the protector is reached to reach the thermal responsiveness. The plate suddenly reverses and separates the contacts, cutting off the power to the motor.

In this embodiment, since the stationary member made of metal is used, the current that should flow to the heat responsive plate support 9 is bypassed through the bearing point 13. However, as in this embodiment, the heating element on the fixed contact side is When there are only conductive pins, the resistance value of the heat responsive plate support is also set low. Therefore, lid plate 1-cover 7 which are all connected by welding or the like
-Operating temperature calibration plate 8-Heat responsive plate support 9-Lug plate 10-Heat responsive plate 11
The contact resistance between the stationary member 6 and the lug plate 10 can be set to a value that does not matter, and most of the heat generation amount is provided by the heat responsive plate 11, so that the operating characteristics thereof are not hindered. Absent. Of course, it is more preferable if the stationary member is made of an electrically insulating material or has a structure in which its contact portion is insulated with ceramics or the like. Further, in this embodiment, the operating temperature calibration plate 8 is cut and raised to form the pressing portion 8F directly, but for the same reason, its operating characteristics are not hindered and the contact thereof is prevented. An electrically insulating material may be used for the portion to electrically insulate the heat responsive plate.

In the three-phase thermal protector according to the present invention, the conductive pins 3A and 3B of the protector and the cover plate 1 are respectively connected to the midpoints of the three windings of the three-phase induction motor in which the windings are Y-connected. However, the heat generated from the electric motor cannot provide sufficient protection in the event of an abnormality, so the heat generated inside the protector affects the heat responsive plate. Further, when the generated heat is not sufficient to protect the electric motor, it is necessary to have a structure in which heat is generated more actively and has a great influence on the heat responsive plate.

Another embodiment for solving the above-mentioned matter will be described with reference to FIG. In FIG. 6, portions corresponding to those in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the lid plate 1 is different from the above-described embodiment in the direction in which the conductive pin 3A (and 3B) is provided.
The positional relationship between right and left has just changed. The fixed contact 5A (and 5B) is a conductive fixed contact support 21.
It is conductively fixed to the conductive pin 3A (and 3B) via A (and 21B). Each fixed contact support is installed so as to be substantially parallel to the cover plate 1. Fixed contact 5
A and 5B are arranged so as to be substantially symmetrical with respect to the center line of the cover plate 1 in the longitudinal direction, and are arranged so as to come into contact with and separate from the movable contacts 12A and 12B of the heat responsive plate 11. . Further, the fixed contact supports 21A and 21B are the heat responsive plate 11
Heat responsive plate 1 so that it can be effectively affected by heat
1 are arranged substantially in parallel. In this embodiment, the fixed contact support is provided with the rib 21A1, but it can be omitted if the fixed contact support has sufficient strength. Further, the stationary member 6 is moved in the fixed position with respect to the cover plate due to the position of the conductive pin and the through hole, but its role and the position of the support point 13 for supporting the heat responsive plate are the same as in the above-mentioned embodiment.

The operating temperature calibration plate 14 has ribs for obtaining rigidity and a portion which is easily bent like the above-described operating temperature calibration plate 8 shown in FIG. Has a shape that does not have. A calibration piece 15, which is a pressing portion made of an electrically insulating material such as ceramics, is provided at a portion corresponding to the cut-and-raised portion of the operating temperature calibration plate 8 described above, and the calibration piece is provided with a hole 9A of the heat-responsive plate support 9. It penetrates and is in contact with the side of the heat responsive plate 11 that is convex at room temperature.

The operation of the thermal protector having such a structure will be described. Since the phase currents of a normal three-phase induction motor are balanced, taking that case as an example, between the conductive pins 3A and 3B of the thermal protector, Between the conductive pin 3A and the cover plate 1,
The current flowing between the conductive pin 3B and the cover plate 1 is the thermal response plate 1 respectively.
The design and selection of the members are performed in consideration of the electric resistance value of the members forming each current path and the degree of thermal influence on the heat responsive plate so that the temperature rises substantially evenly with respect to 1.
That is, the distance between the movable contacts of the heat responsive plate, the distance between each movable contact and the fixed portion between the heat responsive plate support 9 and the heat responsive plate 11, and the heat responsive plate support and the two fixed members as a heating element. It is determined in consideration of the positional relationship between the heat generation amount of the contact support and the heat responsive plate, that is, the thermal influence.

In the present embodiment, since the stationary member made of metal is used, the current that should flow to the heat responsive plate support 9 is bypassed through the bearing point 13. However, when protecting a motor with a relatively large current, heat is applied. The resistance value of the response plate support is also set low. Therefore, similarly to the above-described embodiment, the lid plate 1-the cover 7-the operating temperature calibration plate 14-the thermoresponsive plate support 9-the lug plate 10-which are all connected by welding or the like.
The resistance value of the entire path of the heat responsive plate 11 can be set to a value that does not matter with respect to the contact resistance between the stationary member 6 and the lug plate 10 at the bearing point 13 portion, and the operation characteristics thereof are not hindered. Absent. Of course, when protecting an electric motor having a relatively low current value, the stationary member may be made of an electrically insulating material, or the contact portion may be made of a ceramic or the like. For the same reason, the calibration piece 15 can also be made of metal depending on the usage conditions.

The thermal influence of each heat-generating member on the heat-actuating plate also has an important meaning for protection during a phase loss. That is, if the thermal influences of the currents applied to the heat responding plate 11 from the respective members are not balanced, when the three-phase induction motor becomes in the open phase state for some reason, the open phase state is determined by which winding. Depending on whether or not there is a difference in the amount of heat generated and the thermal effect on the thermal response plate, this thermal protector is activated to protect the three-phase induction motor during open-phase protection, overcurrent and overload protection. From a standpoint, it is not desirable. From this point, when the current is applied between the conductive pins 3A and 3B and when the current is applied between the conductive pins 3A (or 3B) and the cover plate 1, the thermal response plate 11 of the thermal protector jumps and flips to move the movable contacts, respectively. It is desired that the operating time until the fixed contact is opened, the return time from the opened state to the closing again, and the maximum non-operating current value that is the maximum current value that does not reach the inversion state are substantially equal.

Therefore, in the present invention, by providing the heat responsive plate support, which is a heat generating member, and the two fixed contact supports substantially parallel to the heat responsive plate, a predetermined relationship between the amount of heat generated and the distance is provided. It is easy to make adjustments so that the thermal influence on the heat-responsive plate is almost the same. Further, since the heat generating member is disposed substantially parallel to and sandwiching the heat responsive plate, the reactivity of the heat responsive plate to heat generation of the heat responsive member is improved, and the heat radiating of the heat responsive plate can be delayed, thereby increasing the operating time. It is possible to increase the ratio of the recovery time to, and thus to prolong the service life.

Next, another embodiment of the present invention will be described with reference to FIGS. 7 to 10, parts corresponding to those in FIGS. 1 to 3 and 6 are designated by the same reference numerals and description thereof will be omitted. In this embodiment, fixed contacts 5A and 5B
Are conductively fixed to the conductive pins 3A and 3B via fixed contact supports 24A and 24B, respectively. Each fixed contact support is provided with openings 24A1 and 24B1 to increase its electric resistance and increase the amount of heat generation. Further, a spacer 22 as a stationary member formed of an electric insulator such as ceramics is arranged between the fixed contact support and the cover plate 1.

The spacer 22 has recesses 22D1 and 22D2 on the side opposite to the side facing the cover plate, and the fixed contact point support members 24A and 24B are arranged in the recesses to fix the spacers. The contact support is positioned, reinforced, and electrically insulated from the cover plate. Further, since the fixed contact support is arranged in the recess, the tracking generated on the surface of the insulating part by the product such as silver oxide generated by the arc generation between the contacts when the contact is opened is prevented. effective. Furthermore, spacer 22
Is a fulcrum 2 on the surface opposite to the fixed contact support holder from the lid plate 1.
Since contact is made only at three points 2A, 22B, and 22C, the contact points are unlikely to be contaminated by the product, and the initial state can always be maintained. Further, a projection 22E is provided on the surface of the spacer facing the heat responsive plate 11, and the tip end thereof abuts the heat responsive plate 11 to form a bearing point 23.

A calibration piece 15, which is a pressing portion penetrating the heat responsive plate support from the operating temperature calibration plate 14, is brought into contact with the center line of the heat responsive plate 11 to apply a pressing force. In the present embodiment, this calibration piece is made of an electrically insulating material such as ceramics, and has a structure that surely prevents a bypass current from the operating temperature calibration plate to the thermal response plate.

The method of calibrating the operating temperature is the same as that of the above-described embodiment, so a detailed description thereof will be omitted, but the thermal responsive plate 1 is calibrated by the operating temperature via the operating temperature calibration plate 14 and the calibration piece 15.
The pressing force applied to 1 is distributed and supported between two pairs of contact points and at three points, namely, a support point 23 with the protrusion 22E of the spacer.

In a thermal protector having a structure like that of the present invention, it is common practice to reduce the cross-sectional area of the portion that becomes the electric path to increase the electric resistance in order to increase the amount of heat generation. However, in this case, the movable contact and the fixed contact are welded and the heat-responsive plate is not welded in a state where the strength cannot be designed sufficiently by thinning the plate in order to increase the electric resistance value of the heat-responsive plate support 9, for example. At the time of reversing, even if the welding is comparatively mild, the contacts are not separated and the fixed end side of the heat responsive plate, that is, the portion indicated by the symbol F in FIGS. 1, 6 and 7 moves upward. Sometimes. Further, when the welding force is higher, the fixed end side of the heat responsive plate may move similarly without separating the contacts even if the heat responsive plate support 9 has a normal strength.

This is because when the heat responsive plate support 9 has sufficient strength, the heat responsive plate support causes the heat responsive plate to become a solid line or a dotted line in FIGS. 1 and 7 due to the aforementioned biasing force with respect to the heat responsive plate. Since the pressing is performed as shown in the drawing, even when the movable contact and the fixed contact are welded, the contacts can be separated as long as the biasing force of the heat responsive plate support exceeds the strength of the welding. However, as described above, when the strength of the heat responsive plate support 9 cannot be sufficiently designed by thinning the heat responsive plate support 9, the strength of the welding exceeds the biasing force of the heat responsive plate support 9 and the welding is relatively light. Even in this case, the contact points do not separate, and the heat responsive plate fixed part side operates.

This will be described with reference to FIG. 11. In the figure, when the diaphragm center 102 of the heat responsive plate 101 is pressed by the pressing portion, the supporting points 103A and 104A of the movable contact points 103 and 104 with the fixed contact point and the stationary member. When the three support points 105 in contact with the tip are equidistant, the reaction forces applied to the three points have equal values, and the operating conditions at the time of reversing the heat responsive plate are the same. However, in reality, since the biasing force for pressing in the opposite direction to the reversing direction is applied to the fixed end 106 near the outside of the supporting point 105 by the heat responsive plate support, the diaphragm center 102 and the supporting point 105 at the time of reversing, The heat responsive plate 101 held at three points of the fixed end 106 has movable contacts 103, 1
Move 04. In this case, when welding occurs at the movable contact 103 (or 104), if the biasing force of the heat responsive plate support exceeds the strength of the welding, the welding is separated and the contacts are opened. Otherwise, the fixed ends 106 move without separating the contacts. Further, as described above, if the strength of the heat responsive plate support cannot be designed sufficiently by reducing the plate thickness of the heat responsive plate support, the contacts will not be separated even by lighter welding.

Therefore, in the embodiment of the present invention, the pressing point of the thermal responsive plate by the pressing portion is set to be a portion closer to the fixed end of the thermal responsive plate from the center of the plate-shaped diaphragm, so that the bearing point on the fixed end side is reached. The reaction force can be made higher than the reaction force applied to the movable contact, and compensates for the biasing force even when the heat responsive plate support is thinned to increase the electric resistance value and has a low strength shape. The pressing force can be applied to the fixed end side, and the movable contact and the fixed contact can be reliably separated.

Further, as a result of the experiment, the range of this pressing point is closer to the fixed end of the heat responsive plate than the center by the distance of the center of the dish-shaped diaphragm of the heat responsive plate to the distance of about ¼ of the total length of the heat responsive plate. It was found that there is no influence on the calibration of the operating temperature if the range (range indicated by symbol P in FIG. 11) is set. With such a structure, when the heat-responsive plate support is thinned to increase the electric resistance value and is welded when it has a low-strength shape, the contact between the contacts can be opened with the conventional structure. This makes it possible to more reliably separate the movable contact and the fixed contact even in the case of relatively heavy welding that could not be separated. Also, of course, it does not affect the calibration of the operating temperature.

Further, by setting the pressing point by the pressing portion within the range as described above, it is possible to facilitate the so-called automatic alignment described above. In other words, since the pressing point by the pressing portion, which is the fulcrum, is apart from both contact points, which are the points of action of the reaction force,
Not only the torque due to the twist around the X-axis shown in FIG. 1 but also the torque due to the twist around the Y-axis is generated, so that it is possible to more easily adjust the bias of the reaction force due to the bending of the heat responsive plate support.

Further, by separating the pressing point from the position of the contact, it is possible to increase the distance between the contacts when the contacts are opened, and thus it is possible to increase the electric breakdown voltage between the contacts.

[0035]

As described above, according to the three-phase thermal protector of the present invention, the number of parts is smaller than that of the conventional one, the assembling is easy, and the operating temperature calibration after completion of the closed container is completed with high accuracy. Will be possible. Further, it is possible to provide a three-phase thermal protector that operates under substantially the same condition regardless of the connection even when there is a phase loss and that reliably separates the contacts even when the contacts are welded.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a three-phase thermal protector of the present invention.

2 is a sectional view of the three-phase thermal protector of FIG. 1 taken along the line AA.

3 is a cross-sectional view of the three-phase thermal protector of FIG. 1 taken along the line BB.

FIG. 4 is an example of a thermoresponsive plate support of the present invention.

5 is a diagram showing an operating temperature calibration method for the three-phase thermal protector of FIG.

FIG. 6 is a vertical sectional view of another embodiment of the present invention.

FIG. 7 is a vertical sectional view of another embodiment of the present invention.

8 is a cross-sectional view taken along the line CC of the three-phase thermal protector of FIG.

9 is a sectional view of the three-phase thermal protector of FIG. 7 taken along the line DD.

10 is a sectional view of the three-phase thermal protector of FIG. 7 taken along the line EE.

FIG. 11 is a diagram showing a force applied to the heat responsive plate and its position.

[Explanation of symbols]

 1 Cover Plates 2A, 2B Through Holes 3A, 3B Conductive Pins 4A, 4B Filling Material 5A, 5B Fixed Contact 6 Stationary Member 7 Covers 8, 14 Operating Temperature Calibration Plates 8F, 15 Pressing Section 9 Thermal Response Plate Support 11 Thermal Response Plate 12A, 12B movable contact 13, 23 support point 21A, 21B, 24A, 24B fixed contact support 22 stationary member (spacer)

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[Procedure amendment]

[Submission date] June 19, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Touhou 178 North Kasumigaoka-cho, Owariasahi-shi, Aichi (72) Inventor Hideki Ozeki Minamiyama, Fuyama-cho, Niwa-gun, Aichi 40-2 Oyama Nishi 40-2

Claims (5)

[Claims] 1. A closed container constituted by a metal cover having a depth shallower than the width of the opening and a cover plate welded to the end face of the opening, and the cover plate has two through holes at predetermined positions. Conductive pins penetrate through the cover plate and are airtightly fixed to the through holes by an electrically insulating filling material, and fixed contacts are conductively connected to the conductive pins, respectively, and the cover is provided. One end of an operating temperature calibration plate, which has a shape that is relatively easy to bend, is welded and fixed to the inside of the closed container near the fixing portion with the cover, and the operating temperature calibration plate has high rigidity in the direction along the plane. One end of a metallic heat responsive plate support having elasticity that can be bent relatively easily in a direction orthogonal to the plane is fixed, and the other end of the heat responsive plate support is subjected to temperature change such as bimetal. One end of the heat responsive plate that deforms according to welding, etc. Is fixed electrically conductively, and the heat responsive plate has a shallow dish-shaped portion substantially at the center and is configured to perform a snap reversal operation at different predetermined temperatures and is fixed to the heat responsive plate support. Two movable contacts are fixed by welding or the like symmetrically with respect to the center line including the fixed end, and the movable contacts are arranged so as to come into contact with or separate from the fixed contacts in two pairs. The operating temperature calibration plate is provided with a pressing portion penetrating the heat responsive plate support, and the pressing portion presses a portion of the heat responsive plate that is convex at room temperature and on the center line including the fixed end. Then, a stationary member having sufficient rigidity is arranged on the cover plate, and the stationary member supports the vicinity of the fixed end of the heat responsive plate on the center line to receive the heat responsive plate via the pressing portion of the heat responsive plate. The pressing force is distributed to the stationary member and the two fixed contacts. It is, and the force exerted between the contacts of the two pairs are configured so as to be substantially equal,
The force applied between the contacts is applied through the operating temperature calibration plate by deforming the curved portion of the cover,
A three-phase thermal protector configured such that at a different predetermined temperature, the heat responsive plate snaps back and returns, and the two movable contacts open and close with the fixed contacts almost at the same time. 2. The three-phase type according to claim 1, wherein the fixed contacts are conductively connected to the conductive pins through the fixed contact supports, and the fixed contact supports are welded and fixed substantially parallel to the cover plate. Thermal protector. 3. A closed container composed of a metal cover having a depth shallower than the width of the opening and a cover plate welded to the end face of the opening, and the cover plate has through holes at predetermined positions. Conductive pins penetrate through the cover plate and are hermetically fixed to the through holes by electrically insulating fillers in the through holes, and fixed contact supports having fixed contacts are fixed to the conductive pins. A stationary member made of an electrically insulating material is arranged between the fixed contact support and the cover plate, and is fixed substantially parallel to the cover plate. The stationary contact member is reinforced and supported by the stationary member, and the cover is a closed container. One end of an operating temperature calibration plate, which has a shape that is relatively easy to bend, is welded and fixed to the inside of the portion where the cover is fixed to the cover, and the operating temperature calibration plate has high rigidity in the direction along the plane and is orthogonal to the plane. It is relatively easy to bend in the direction One end of a heat-responsive plate support made of metal having elastic elasticity is fixed, and one end of a heat-responsive plate, such as a bimetal, which is deformed in response to temperature change is welded to the other end of the support. And the like, and the heat responsive plate has a shallow dish-shaped portion in the center so as to perform a snap reversal operation at different predetermined temperatures. Two movable contacts are fixed by welding or the like symmetrically with respect to a center line including the fixed end fixed, and the movable contacts are respectively fixed to the fixed contacts by two.
The operating temperature calibration plate is provided with a pressing portion penetrating through the heat responsive plate support member so as to come in contact with or separate from each other, and the press portion is convex at room temperature of the heat responsive plate. On the center line including the fixed end, and by supporting a portion of the stationary member near the fixed end of the heat responsive plate on the center line by the part of the stationary member, the heat responsive plate receives through the pressing portion. The pressing force is distributed and supported by the stationary member and the two fixed contacts, and the forces applied between the two pairs of contacts are substantially equal, and the force applied between the contacts is the cover. It is given through the operating temperature calibration plate by deforming the curved part of the, and at a different predetermined temperature, the thermal responsive plate snaps the reverse return operation, and the two movable contacts almost simultaneously open and close with the fixed contact. Three-phase sir configured to Le protector. 4. The three-phase thermal protector according to claim 2, wherein the fixed contact support and the heat responsive plate support are arranged so as to substantially face and parallel to the plane of the heat responsive plate. 5. The pressing position of the heat responsive plate by the pressing portion is set to approximately 4 from the center of the shallow dish-shaped molding portion to the entire length of the heat responsive plate.
The three-phase thermal protector according to any one of claims 1 to 4, wherein the pressing force is applied to a range closer to the fixed end than the center by a length of one-half.