JP3992320B2 - Thermal protector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal thermal protector suitable for protecting a motor used in a hermetic electric compressor, in particular, a three-phase motor from burning.
[0002]
[Prior art]
Conventional thermal protectors of this type (hereinafter referred to as protectors) include, for example, “thermally responsive switch” disclosed in Japanese Patent Application Laid-Open No. 56-130040 and “thermally responsive snap switch” disclosed in Japanese Patent Application Laid-Open No. 62-88232. These protectors are attached to a single-phase electric motor. The central part of the protector is fixed to one end of a thermally responsive plate such as a bimetal drawn into a dish shape, and the other end is fixed to an elastic plate. The pressure between the contacts and the operating temperature are regulated by pressing the vicinity of the center of the convex surface of the thermally responsive plate at a predetermined pressure with the fixed contact and the support part in contact with each other. These protectors are attached to one end of the thermal reaction plate and the surrounding heating element when the current flows between the terminals. The movable contact is separated from the fixed contact and the electric circuit is interrupted.
[0003]
In particular, three-phase protectors include, for example, “three-phase thermal protectors” disclosed in Japanese Patent Application Laid-Open Nos. 57-34623, 1-105435, and 6-96649. In these three-phase protectors, the central part of the three-phase protector is arranged on a substantially circular thermo-responsive plate drawn into a dish shape so that the fixing points of the two movable contacts and the elastic plate are substantially equilateral triangles, The pressure between the contacts and the operating temperature are regulated by pressing the fixed contact and the support part in the vicinity of the center of the convex surface of the thermally responsive plate, that is, in the vicinity of the center of the equilateral triangle described above with a predetermined pressure. It is. These three-phase protectors are attached to the middle point of the so-called Y-connected motor, and when the motor is abnormal, the midpoint is opened by reversing the thermal response plate in the same way as the single-phase protector described above. It is comprised so that the electric circuit between each phase may be interrupted | blocked. In these products, a structure is used in which the thermal reaction plate is operated mainly by using the heat generated by the thermal reaction plate itself by passing an electric current through the thermal reaction plate such as a bimetal. In order to maintain a good balance, a flat plate with a substantially flat vertical and horizontal dimension and a flat cross-sectional shape is used. It is said that.
[0004]
In each of the protectors described above, a structure in which the movable contact is fixed to the free end of the thermally responsive plate and the other end is fixed to the elastic plate prevents unnecessary stress from being applied to the fixing point. This elastic plate also has a role as a heater for supplementing the amount of heat generated by the thermally responsive plate. However, especially when the rated current is large or the operating temperature of the thermally responsive plate is set high, the so-called annealing effect may occur when the elastic plate becomes a high temperature as a heater, and the performance as the elastic plate may deteriorate. There was a problem that it could not be used for a relatively high output. If a rigid heater is used instead of the elastic plate in order to avoid this problem, the operating temperature may change due to an excessive stress applied to the fixing point of the thermally responsive plate.
[0005]
When an elastic plate is used, the three-phase protector corrects the inclination of the thermal response plate by twisting the elastic plate even if the thermal response plate is slightly inclined with respect to the contact point during assembly. Although the pressure between the contacts of a set can be balanced, if such a balancing plate is not held if the thermal plate is held by a rigid body, an individual pressure adjustment mechanism is provided between the contacts or with very high accuracy. It must be assembled so that the two contacts open and close at the same time and have the same contact pressure.
[0006]
Furthermore, the conventional three-phase protector has a shape that is almost equal in vertical and horizontal dimensions using a substantially circular heat-responsive plate. Therefore, especially when attaching to a coil end on a motor winding, so-called coil end, the coil end Since the width of the protector becomes wider than the width, there is a problem that the mounting becomes difficult. Recently, the whole electric compressor tends to be downsized and the diameter of the electric motor tends to be small, and if the width of the protector is made smaller than the width of the coil end with the conventional structure, the whole must be downsized. The current capacity becomes small and the manufacture becomes difficult.
[0007]
Since the conventional three-phase protector has substantially the same vertical and horizontal dimensions, the work of attaching an insulating coating for insulation to the protector has been troublesome. This is because the protector's container is normally a charging part, and when it comes into contact with other conductive parts, it is necessary to cover with an insulating coating such as a polyester tube in order to cause problems such as a short circuit. Usually, a method is adopted in which a polyester tube having an inner circumference slightly larger than the outer circumference of the protector is covered and fixed to the surface of the protector by heat shrinkage. In this case, since the heat shrinkage rate of the polyester film is not so large, the difference between the outer periphery of the protector and the inner periphery of the polyester tube is small. Therefore, if the protector has a flat cross-sectional shape with almost the same vertical and horizontal dimensions as the above-mentioned protector, it is necessary to greatly deform the tube when the protector is inserted into a substantially cylindrical polyester tube, and positioning is difficult and cumbersome and cumbersome. It will take something.
[0008]
In order to solve these problems, the present applicant has proposed a novel thermal protector in Japanese Patent Application No. 8-195634 and Japanese Patent Application No. 8-297543. This thermal protector has two movable contacts attached almost symmetrically with respect to the center of the plate-like diaphragm of the thermal reaction plate. The thermal response plate is made longer than the conventional one and each By arranging the parts so that they are almost stacked in parallel, the overall structure can be elongated compared to a conventional protector with almost the same vertical and horizontal dimensions, making it easy to mount on the coil end of the motor. Become.
[0009]
The conventional protector will be described with reference to FIG. 17 which is a longitudinal sectional view of FIG. 16 and a CC sectional view thereof. The protector 101 forms an airtight container with a metal housing 3 and a cover plate 2, and a heat responsive plate support 110 is connected and fixed to the inside of the housing 3, and the heat responsive plate support 110 is elastic to the heat responsive plate support 110. One end of the plate 11 is fixed. Further, the other end of the elastic plate 11 is fixed with a heat-responsive plate 12 drawn in a shallow dish shape having movable contacts 14 </ b> A and 14 </ b> B via a fixing piece 13. By adopting such a structure, even when the thermally responsive plate 12 is slightly inclined with respect to the contacts at the time of assembly, the elastic plate is twisted to correct the inclination, so that the pressure between the two sets of contacts can be balanced. Further, the elastic plate 11 is applied with a biasing force in a clockwise direction around the fixing piece 13 in FIG. For this reason, when the thermally responsive plate 12 is reversed, this biasing force acts as a pulling force of the movable contacts 14A and 14B, and the movable contacts can be separated from the fixed contacts 8A and 8B.
[0010]
The lid plate 2 is composed of a metal plate 4 and lead terminal pins 5A and 5B which are airtightly insulated and fixed to the metal plate 4 with a filler 6 such as glass. The lid plate 2 is formed at the inner end of the lead terminal pins 5A and 5B penetrating the metal plate 4. The fixed contacts 8A and 8B are connected and fixed via fixed contact supports 7A and 7B. A metal pressure piece 115 for temperature calibration is fixed to the inside of the housing 3, and the tip 115 </ b> A is in contact with the vicinity of the center of the diaphragm that is convex in the normal state of the thermally responsive plate 12. The protector 101 has its operating temperature calibrated by deforming the vicinity of the pressing piece fixing portion of the housing 3 and adjusting the pressing force to the thermally responsive plate 12. Further, each of the thermally responsive plate support 110 and the fixed contact supports 7A and 7B is a heating element, and each is adjusted so that heat applied to the thermally responsive plate 12 is substantially equal.
[0011]
[Problems to be solved by the invention]
For example, in such a protector, a material having a high specific resistance value such as nickel-chromium alloy or iron-chromium alloy is used as the material of the heat-responsive plate support 110, which is a heat generating portion, in order to increase the amount of heat generated by an internal current. May be used. Here, in the protector 101, the metal pressing piece 115 which is a temperature calibration member is in direct contact with the central portion of the thermally responsive plate 12, so that the bypass current flowing through the pressing piece 115 becomes a problem. . That is, when the resistance value of the thermally responsive plate support 110 is low, the contact resistance between the pressing piece and the thermally responsive plate is sufficiently high so that the bypass current does not flow so much, but the resistance of the thermally responsive plate support 110 is low. When the value is increased, the contact resistance is relatively lowered, so that the current that should flow through the thermally responsive plate support 110 flows as a bypass current through the pressing piece 115, and the resistance value of the thermally responsive plate support 110 is reduced. There was a problem that the increased effect could not be obtained sufficiently.
[0012]
[Means for Solving the Problems]
Therefore, the thermal protector of the present invention has a sealed container composed of a lid plate and a generally long dome-shaped housing, and a fixed contact is provided inside the sealed container of the two lead terminal pins insulated and fixed to the lid plate. Is fixed conductively through a fixed contact support, a pressure piece for operating temperature calibration is fixed to the inner surface of the housing, and a metal heat-sensitive plate support is fixed to the inner surface of the housing. A thermally responsive plate that changes its bending direction in a snap manner according to different temperatures by being drawn into a shallow dish shape is connected and fixed to the plate support through an elastic plate. In this protector, the thermally responsive plate is mounted so that two movable contacts can be opened and closed correspondingly to the fixed contact substantially symmetrically with respect to the center of the dish-shaped diaphragm, and the pressing piece is a normal convex of the thermally responsive plate. The bypass current flowing between the pressing piece and the thermal reaction plate in the vicinity of the center of the diaphragm in a state that does not substantially cause a problem, and at least in the vicinity of the fixing portion between the thermal reaction plate and the elastic plate It is characterized in that the contact is made in such a manner that the bypass current is not substantially problematic. Therefore, the heat-responsive plate support as a heat generating body can surely generate a predetermined heat, and the degree of freedom is widened in selecting the resistance value.
[0013]
Another feature is that an electrical insulator such as polyamide paper is inserted between the pressing piece and the thermally responsive plate.
[0014]
Yet another feature is that the pressing piece has an electric insulator integrally fixed to a metal base portion.
[0015]
Another feature is that an imaginary line connecting each movable contact point from the connection portion between the thermally responsive plate and the elastic plate forms an angle of 90 ° or more, and an approximately isosceles triangle is formed by three points of the connection portion and each movable contact point. Accordingly, the shape of the protector having a shape having relatively equal vertical and horizontal dimensions is made longer than that of the conventional protector, so that the motor can be easily mounted on the winding.
[0016]
Another feature is that a thin material is used to make the fixed contact support as a heating element by placing a positioning member between the metal plate of the cover plate and the fixed contact support to define the distance between them. However, the distance between the metal plate and the fixed contact support is not reduced or the two are not in contact with each other.
[0017]
Still another feature is that a special operation for attaching the positioning member as an insulating plate to the lid plate is eliminated by elastically holding the positioning member between the fixed contact support and the lid plate.
[0018]
Still another feature is that the thermally responsive plate support, the elastic plate, and the thermally responsive plate are substantially parallel to each other, and the thermally responsive plate support and the elastic plate, and the elastic plate and the thermally responsive plate face each other at a predetermined interval. The radiant heat from the thermally responsive plate support is directly applied to the thermally responsive plate through an opening in which the thermally responsive plate support is interposed between the elastic plate and the partial plane of the thermally responsive plate is provided in the elastic plate. It is to have reached.
[0019]
Still another feature is that the thermal reaction plate support, the elastic plate, and the thermal reaction plate are substantially parallel to each other, and the thermal reaction plate support and the elastic plate, and the thermal reaction plate support and the thermal reaction plate are set at predetermined intervals, respectively. The elastic plate is not interposed between the thermal reaction plate support and the thermal reaction plate, and is disposed on the back side of the thermal reaction plate support. This is because the radiant heat reaches the heat responsive plate without being blocked.
[0020]
Another feature is that the position of contact of the pressing piece with the heat-responsive plate is arranged from the center of the plate-shaped diaphragm to the protrusion that is the fixed end of the heat-responsive plate, thereby effectively using the force of the heat-responsive plate. This is because the possibility of using contact welding has been reduced.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on examples with reference to the drawings. The thermal protector 1 according to the first embodiment shown in FIGS. 1 to 7 forms an airtight container with a cover plate 2 and a housing 3. The cover plate 2 is provided with through holes 4A and 4B at both ends of a substantially oval metal plate 4, and conductive lead terminal pins 5A and 5B are hermetically insulated and fixed to the through holes by a filler 6 such as glass. Has been. In the present embodiment, the metal plate 4 of the lid plate 2 has a sufficient thickness, and a flange portion 4C having a small thickness for improving the weldability with the housing 3 is constant on the outer periphery thereof. It is provided so that it may be edged.
[0022]
The housing 3 is made of a metal plate that is thinner than the lid plate 2, and has a dome shape with a flat surface 3A on the upper surface as shown in the perspective view of FIG. 4 and the plan view of FIG. From the intermediate part of the flat part 3A, a calibration part 3B which is deformed in an operating temperature calibration described later is provided so as to protrude sideways in the same plane as the flat part 3A as shown in FIG. Therefore, the planar shape of the housing 3 is a shape in which the side having the calibration part 3B is slightly swollen as shown in FIG. The above-mentioned airtight container is configured by abutting the opening end portion of the housing 3 with the flange portion 4C at the peripheral edge portion of the cover plate and airtightly fixing by ring projection welding or the like.
[0023]
One end of a fixed contact support 7A, 7B is fixed to each end of the lead terminal pins 5A, 5B inside the sealed container by a method such as welding, and the other fixed contact support 7A, 7B is fixed to the other end. 8A and 8B are fixed. In the present embodiment, it is preferable that the surfaces of the fixed contacts 8A and 8B that are in contact with the movable contacts are plastically deformed into a planar shape by pressing or the like after being fixed to at least the fixed contact support, and the heights thereof are made uniform. By doing so, the heights of the two fixed contacts before temperature calibration are aligned with high accuracy for each product, and the temperature calibration work becomes easy. Further, if the contact surfaces of the fixed contacts 8A and 8B with the movable contacts are flat, even if the contact positions of the movable contacts 14A and 14B described later are slightly shifted in the horizontal direction, they are in contact as in the case of curved contact points. Since the pressure does not change, a protector with more stable performance can be obtained.
[0024]
In this embodiment, an insulating plate made of ceramics or the like is mounted between the fixed contact supports 7A and 7B and the metal plate 4 as positioning members 9A and 9B for defining the distance between the two. Yes. Further, in this embodiment, the positioning members 9A and 9B are elastically sandwiched by the fixed contact supports, respectively, to facilitate the work necessary for fixing the non-metallic positioning member to the lid plate 2. Further, by selecting a material such as alumina having good thermal conductivity for the positioning members 9A and 9B, heat can be quickly released to the metal plate 4 from the fixed contact heated by an arc or the like generated when the contact is opened. The temperature can be lowered, the arc can be quickly terminated as well as the fixed contact is consumed, and the life of the protector can be extended.
[0025]
Furthermore, by adopting a structure that conducts the heat of the contact and the fixed contact support to the housing through the positioning member, the difference between the amount of heat generated inside the protector and the amount of heat released to the outside of the protector at the current value at which continuous operation is possible. Therefore, even if the continuous operation current value is increased, the temperature of the thermally actuated body does not change much, and the maximum limit operation current value (U.T.C.) can be increased compared to the conventional one. . In addition, when the electric motor rotor is constrained, the heat generation amount is sufficiently large compared to the heat dissipation amount when the current is excessive. Even if the structure is short and the heat of the contact and the fixed contact support is conducted to the housing through the positioning member, the time until the contact is opened (Short Time Trip: S / T) is not so long, and the protector is quickly activated when overcurrent occurs. Works. In this way, by selecting a positioning member having a good thermal conductivity, the current value and rated operating current value at which the time (S / T) until the contact is opened is set to a predetermined time, for example, 10 seconds, at room temperature. (UTC) can be brought close to each other, and the driving performance of the electric motor can be sufficiently brought out.
[0026]
As shown in FIG. 5, the positioning members 9A and 9B have portions in contact with the lead terminal pins so that the fixed contact supports 7A and 7B can be inserted from the side after being fixed to the lead terminal pins 5A and 5B. Although it is U-shaped, for example, the fixed contact support may be fixed to the lead terminal pin after a positioning member provided with a through hole is inserted into the lead terminal pin. Further, the positioning members 9A and 9B ensure electrical insulation between the fixed contact supports 7A and 7B and the metal plate 4, and when the both fixed contact supports are relatively thin so as to be heating elements, Although it is necessary to define the position of the fixed contact even if the rigidity is lowered, for example, a rib etc. is formed on the fixed contact support body so that the rigidity is sufficient and the insulation distance from the metal plate is set to a necessary dimension. If set, the positioning members 9A and 9B can be omitted.
[0027]
A thermally responsive plate support 10 is fixed to the inner surface of the housing 3. The thermally responsive plate support 10 is a metal plate having sufficient rigidity, and is fixed by welding and fixing the fixed portions 10A bent at the both ends to the fixing portions 3C located near the both ends of the housing 3. It is supposed to be a supporting structure. Further, the intermediate portion 10B has a detoured shape so as not to interfere with a temperature adjusting mechanism which will be described later, and is also provided with a slight step to avoid interference with an elastic plate which will be described later. Furthermore, the thermally responsive plate support 10 is configured such that the overall shape is symmetrical with respect to the intermediate portion 10B. Needless to say, this portion may have any shape as in the embodiment as long as it has a through hole in the central portion to avoid interference with the operating temperature calibration pressing piece 15.
[0028]
The reason why the fixing portions 10A of the thermoresponsive plate support 10 are provided at both ends is a portion that is less affected by deformation even if the calibration portion 3B is deformed in a temperature adjustment operation described later by providing a sufficient distance from the calibration portion 3B. This is to fix the thermally responsive plate support to the surface. In addition, by setting the fixed portion 10A at two positions on both ends of the thermally responsive plate support 10, the thermally responsive plate support is supported in a cantilever shape even if the fixed portion is slightly displaced for some reason. This is because there is an advantage that the amount of displacement of the intermediate portion 10B to which an elastic plate, which will be described later, is fixed can be reduced.
[0029]
The intermediate portion 10B of the thermally responsive plate support is formed by an elastic plate 11 having a substantially oval shape and having an open side surface of an annular plate having an opening portion 11D at the center portion. It is fixed. Although both end portions 11B and 11C of the elastic plate 11 are separated in the embodiment, an annular elastic plate may be used without separation. In the embodiment, by providing the opening 11D, the heat-responsive plate support 10 serving as a heating element and the heat-responsive plate 12 described later are directly opposed through the opening 11D. Further, the elastic plate 11 gives the thermal reaction plate a clockwise biasing force centered on the fixing piece 13 shown in FIG. 2, and requires flexibility to control the balance action of the movable contact of the thermal reaction plate. The area is not large, and depending on the material, there is a problem that the characteristics as a protector change when the temperature becomes high due to the energizing current, and the characteristics as a protector change. A metal plate is preferred. For example, the use of a clad material produced by bonding a copper plate having a low specific resistance and a steel plate having excellent spring properties is more preferable as an elastic plate that suppresses heat generation.
[0030]
The thermally responsive plate 12 is such that a member that is deformed by heat, such as a bimetal or a trimetal, is drawn into a shallow dish shape, etc., so as to suddenly reverse and return suddenly at a predetermined temperature. The two movable contacts 14A and 14B are fixed substantially symmetrically with respect to the center of the plate-like diaphragm at both ends in the longitudinal direction, and substantially connected portions between the thermally responsive plate and the elastic plate 11 on one central side. It is the shape which provided 12 A of protrusion parts used as a fixing | fixed part. A fixed piece 13 is attached to the protruding portion 12A by welding or the like, and in this state, the thermally responsive plate 12 is subjected to a drawing process or the like in a dish shape so as to reverse and return at the predetermined temperature. Further, the fixing piece 13 and the elastic plate 11 are fixed by welding or the like. Therefore, the thermally responsive plate is hardly affected by heat or stress generated when the thermally responsive plate 12 is connected and fixed to another member, in the embodiment, an elastic plate, and the operation temperature adjusted in advance is hardly changed. When the thermal reaction plate 12 is fixed to another member such as an elastic plate, a fixed piece is used in order to prevent a change in the operating temperature of the thermal reaction plate from becoming a problem. 13 can be omitted.
[0031]
Further, the fixed positions of the movable contacts 14A and 14B are set so that an imaginary line connecting the movable contacts from the projecting portion 12A serving as the connecting portion forms an angle of 90 ° or more, and the projecting portion 12A and the movable contacts 14A and 14B are connected to each other. Three points form an isosceles triangle. By adopting such a positional relationship, the shape of the thermally responsive plate can be elongated in the width direction, for example, approximately oval, and as a result, the shape of the protector can be elongated to facilitate mounting on the winding of the motor. Is.
[0032]
The thermally responsive plate 12 is connected and fixed to both end portions 11B and 11C of the elastic plate 11 through fixing pieces 13. The fixing piece 13 is fixed by a method such as welding with a projection 12A of a thermally responsive plate at a central plane portion and an elastic plate 11 at the end surfaces of welded portions 13A and 13B extending in the longitudinal direction at both ends thereof. The thermally responsive plate support 10, the elastic plate 11, and the thermally responsive plate 12 are arranged substantially parallel to each other, and the cover plate 2 and the fixed contact supports 7A and 7B are also substantially parallel. The movable contacts 14A and 14B are opposed to the fixed contacts 8A and 8B, respectively, and are configured to be able to open and close the electric circuit by being separated from and brought into contact with each other in accordance with the reversal and return of the thermally responsive plate 12. Further, since the thermal reaction plate 12 is elastically held by the elastic plate 11, the thermal reaction plate 12 is attached to the thermal reaction plate 12 with a slight inclination, so that even if the contact pressure varies between the two sets of contacts, the thermal reaction plate 12 is elastic. The plate 11 is bent and the contact pressure between the two contacts can be made substantially the same.
[0033]
One end of the pressing piece 15 as a temperature adjusting mechanism in the longitudinal direction is fixed to the inner side surface of the calibration part 3B provided in the housing 3 by a welding part 15C. This pressing piece 15 is made of a metal having sufficient rigidity, and on the center line that symmetrically divides the movable contact to the convex surface at the normal temperature of the thermally responsive plate 12, as shown in FIG. The part 15B is in contact with or close to almost the entire surface, and a predetermined pressing force is applied by a method as described later.
[0034]
In the present embodiment, an insertion piece 16, which is an electrical insulator, is sandwiched between the pressing piece 15 and the thermally responsive plate 12 in order to prevent a bypass current from flowing through the pressing piece. The material of the insert piece 16 is preferably a flexible material having sufficient electrical insulation, heat resistance and strength, such as polyamide paper, but it does not hinder the operation of the thermally responsive plate 12. Not as long.
[0035]
The insertion piece 16 of the present embodiment has, for example, a T-shaped planar shape, and one side 16A is assembled into a space surrounded by the heat-responsive plate 12, the elastic plate 11, and the welded portions 13A and 13B of the fixing piece 13 during assembly. The position is determined by insertion. Further, by making the insertion piece 16 wider at the other end with respect to the insertion end like a T-shape, the insertion piece is not inserted deeper than necessary. Further, by fixing the heat-responsive plate support 10 to the housing 3 after insertion, the other end of the insert piece is positioned between the heat-responsive plate or the like and the housing. Even if the above treatment is not performed, the inserted piece does not shift to a position beyond the contact with the housing 3, and therefore does not fall off completely. A flexible one is suitable for the insertion piece 16, and it is preferable not to affect the operation of the thermally responsive plate or the like even if it comes into contact with the housing 3.
[0036]
The calibration of the operating temperature of the protector 1 is performed after the airtight container is completed, and the calibration part 3B of the housing 3 is crushed by jigs G1 and G2 that sandwich the metal plate 4 of the cover plate 2 and the housing 3 as shown in FIG. Deformed. In this embodiment, the jig G2 receives almost the entire circumference of the flange portion 4C of the cover plate 2, and the jig G1 presses and deforms the calibration portion 3B in the direction of arrow G, thereby displacing the pressing piece 15 and its tip portion 15A. A pressing force is applied to the side of the thermally responsive plate 12 that protrudes at room temperature via the. This pressing position is an intermediate point between the movable contacts 14A and 14B, and the pressing force is supported by the fixed contacts 8A and 8B via these movable contacts 14A and 14B. The contact pressure is increased and appropriately adjusted by the deformation operation of the housing 3 so that the thermal reaction plate 12 is adjusted so as to reverse the bending direction in a snap manner as shown in FIG. 3 at a desired operating temperature.
[0037]
Here, since the rear end 15B side, which is one end in the longitudinal direction of the pressing piece 15, is fixed to the calibration unit 3B, the amount of deformation of the calibration unit 3B in the operation temperature calibration operation is small even if the amount of deformation is small. The displacement of the tip portion 15A which is the end is enlarged by the lever principle and becomes a sufficient value. Further, as described above, since the fixed portion 10A of the thermally responsive plate support 10 is fixed to the fixing portions 3C located near both ends of the housing 3, the calibration portion 3B near the center is slightly deformed in the operation temperature calibration operation. But it will not be affected. Therefore, the deformation of the thermally responsive plate support 10 is substantially absent. At this time, the elastic plate 11 is applied with a biasing force in the clockwise direction around the fixing piece 13 in FIG. Therefore, when the thermally responsive plate 12 is reversed, it can be surely tilted in that direction to separate the movable contact from the fixed contact, and when the movable contact is separated from the fixed contact by the snap inverting operation of the thermally responsive plate. Chattering can be eliminated and calibrated to a predetermined operating temperature.
[0038]
The protector 1 configured as described above is moved from the fixed contacts 8A and 8B to the movable contacts 14A and 14B when the heat-responsive plate 12 snaps and snaps in a desired first temperature, for example, at 130 ° C. as shown in FIG. Are simultaneously released, and when a predetermined second temperature lower than the first temperature, for example, 90 ° C. is reached, sudden jumping is resumed to return to the state shown in FIG. 1 and the contacts are simultaneously closed.
[0039]
If such a protector is used for a long period of time, the contact surface may be roughened due to an arc or the like generated when the contact is opened or closed, causing welding. Usually, if the welding is mild, it is released by the reversing movement of the thermally responsive plate and the pulling force applied by the elastic plate.
[0040]
In the present embodiment, as shown in FIG. 2, the pressing piece 15 abuts in the vicinity of the center of the diaphragm of the thermally responsive plate 12 at the front end portion 15A, and the thermally responsive plate extends from the front end portion 15A to the rear end portion 15B. It was comprised so that it might contact | abut or adjoin. In this way, the thermally responsive plate 12 is attached to the fixed portion of the fixed piece 13 that is in the vicinity of the fixed portion between the thermally responsive plate 12 and the elastic plate 11 at the time of inversion shown in FIG. Further movement is prevented by contacting the end 15B. In this way, at the normal time, the movable contact side of the thermally responsive plate 12 moves more greatly, and the distance between the contacts can be increased. Further, even when light welding occurs between the contacts, the projecting portion 12A to which the fixing piece 13 is fixed contacts the pressing piece rear end portion 15B, so that the acting force when the thermally responsive plate 12 is reversed is the movable contact 14A. 14B, the force at the time of reversal becomes a force for effectively separating the contacts, and the contacts can be reliably separated.
[0041]
The protrusion 12A of the heat responsive plate 12 and the pressing piece rear end 15B are in contact with each other with a very weak force from the normal time, or close so that they can be contacted when the heat responsive plate 12 is reversed, The proximity distance is preferably a position where the protrusion 12A can come into contact when it is assumed that the movable contact point of the thermally responsive plate is fixed, in particular, a distance of ½ or less of the movement amount when the protrusion 12A is reversed. .
[0042]
In the present embodiment, the end face of the pressing piece 15 is substantially flat and the rear end is in contact with or close to the heat responsive plate 12. However, the shape is not limited to this, and the heat responsive is shown. For example, a pressing piece 35 shown in FIG. 12 may be used as long as the front end of the plate comes into contact with the normal convex side of the plate in the vicinity of the center of the diaphragm and comes close to or comes into contact at least in the vicinity of the fixed portion between the thermally responsive plate and the elastic plate. It is good also as a shape which provided the processus | protrusion in the front-end | tip part 35A and the back end part 35B.
[0043]
Further, even if the pressing piece is L-shaped as shown in FIG. 17, there is little difference in height between the front end portion and the rear end portion, and the protrusion 12 </ b> A is formed at the rear end portion of the pressing piece when the thermally responsive plate 12 is reversed. What is necessary is just to contact | abut. As a specific example, like the pressing piece 45 shown in FIG. 8, the height h1 of the pressing piece front end portion 45A with respect to the back surface is compared with the height h2 of the rear end portion 45B. It is preferable that it is 1/20 or less with respect to the distance from the center to the tip of the protrusion. According to experiments, when the distance from the center of the diaphragm of the thermally responsive plate to the tip of the protrusion is about 8.5 mm, the effect is recognized when the difference in height between the tip of the pressing piece and the rear end is 0.4 mm or less. It was.
[0044]
In the first embodiment, a metal piece is used as the pressing piece, and the insertion piece 16 is sandwiched between the heat-responsive plate. For this reason, it is possible to prevent the current that should flow to the thermal plate support from bypassing the contact portion between the pressing piece and the thermal plate.For example, when the protector is used for an electric motor having a low rated current value, the amount of heat generated inside the protector is reduced. In order to increase the amount of heat generation, the amount of heat generation can be reliably increased by increasing the resistance value of the thermally responsive plate support serving as a heat generating portion. In other cases, it is further preferable to insulate the contact portion between the pressing piece and the thermally responsive plate with an electrical insulator. Furthermore, in this embodiment, an example in which an insertion piece having sufficient strength, heat resistance, and flexibility, such as polyamide paper, is used as an electrical insulator has been described as an example, but it is arranged so as not to hinder the operation of the thermal reaction plate and the like. Various heat resistant resins and ceramics may be used if provided.
[0045]
Furthermore, by using an electrical insulator or a high-resistance material as at least a part of the pressing piece so that the bypass current flowing between the pressing piece and the thermally responsive plate does not substantially become a problem, It is possible to omit the use of an insertion piece such as For example, a functionally gradient material in which metal and ceramics are combined in the pressing piece may be used. The pressing piece will be described with reference to FIG. The pressing piece 55 is a functionally graded material having one surface as a metal base layer 55A and the other surface as an electric insulator layer 55B made of ceramics such as alumina. In the intermediate layer 55C, the mixing ratio of the ceramic and the metal changes stepwise. Since the pressing piece 55 is not energized between the upper and lower ends in the drawing when resistance welding is performed, the energizing electrode is brought into contact with the side portion of the metal layer 55A and is pressed by the pressing electrode from above and below at the welding portion 55D. It is welded to the housing.
[0046]
Since the pressing piece 55 has a contact surface with the thermally responsive plate as the electric insulator layer 55B, no bypass current flows even if it directly contacts. Further, the electrical insulator layer 55B does not necessarily need to be a complete insulator. If the resistance value is sufficiently high with respect to the thermally responsive plate support and the bypass current does not cause a problem, the electrical insulator layer 55B has conductivity. May be.
[0047]
Further, as the pressing piece, an electric insulator fixed to a metal base by bonding or mechanical means may be used. This example will be described with reference to FIG. The pressing piece 65 includes a metal base 65A and an electric insulator 65B such as ceramics. The base 65A is provided with a groove along the longitudinal direction of one end thereof, and the electric insulator 65B is fitted so that its side surface is higher than the base. In the embodiment, so-called caulking is performed on both side surfaces 65A1 of the base 65A, and the electrical insulator 65B is mechanically fixed so as not to drop off. This pressing piece 65 can also be fixed to the housing by the welded portion 65D of the metal base 65A, and since the electrical insulator 65B is in contact with the thermally responsive plate, no bypass current flows even if it is in direct contact. .
[0048]
In this case, a non-conductive ceramic such as alumina is preferable as the electrical insulator. However, a conductive ceramic having a relatively high specific resistance value, such as barium titanate or boron nitride (BN), is preferable. ), Non-oxidizing ceramics such as silicon carbide (SiC) can also be used. In addition, so-called engineering plastics or the like may be used for those having a low operating temperature, and in this case, a metal base and an electrical insulator can be integrally formed.
[0049]
This protector 1 can be connected to the midpoint of the Y connection of the three-phase motor. That is, in the case of Y connection, the lead terminal pins 5A and 5B and the metal plate 4 (or the housing 3) are respectively connected to the coil ends that are the midpoints of the electric motor. If any abnormality occurs in the motor to be protected and its current increases, the heat generated by the members that form each circuit path increases, the protector reaches the operating temperature, the heat-responsive plate suddenly reverses, and the two contacts are separated. Shut off the power to the motor. Here, the resistance value, that is, the calorific value, is different between when the thermally responsive plate 12 itself is energized through the movable contacts 14A and 14B and when it is energized through each movable contact and the fixed piece 13. ing. Therefore, in the present embodiment, in order to make the operating conditions uniform between the phases of the three-phase power source, the resistance values of the fixed contact supports 7A and 7B and the heat-responsive plate support 10 which are heat-generating members, and the heat-generating members and the heat-sensitive plates. By adjusting the heat exchange relationship with each other, the temperature rise conditions of the thermally responsive plate 12 when energizing each electric circuit can be adjusted so as to be substantially uniform.
[0050]
As described above, in the present invention, in the conventional protector, the contact and the fixing portion are arranged so as to be substantially equilateral triangles, and the electric paths on the thermal reaction plate are made to be substantially equidistant. The heat generating plate itself compensates for the unbalanced heat generation with another heating element, and is substantially balanced. Furthermore, since an electrical insulator such as the insertion piece 16 is inserted into the contact portion between the thermal reaction plate 12 and the pressing piece 15 for insulation, the resistance value of the heating element, particularly the thermal reaction plate support 10 is selected. Increases freedom.
[0051]
In addition, it is possible to make the positional relationship between the movable contact and the fixed part on the thermally responsive plate an approximately right-angled isosceles triangle or an obtuse angle isosceles triangle, and each component is overlapped substantially parallel to this thermally responsive plate. Accordingly, the overall structure can be made elongated compared to a protector having a shape having substantially the same vertical and horizontal lengths, and mounting on the windings of the motor is facilitated. Furthermore, although the planar shape of the protector 1 of the present embodiment is a shape in which the side having the calibration portion is slightly swollen, the shape of the outer peripheral portion of the fixed winding of the motor to which the protector is mounted is included including the curved shape on the bulging side. By making it match, the mounting work on the motor winding becomes easier.
[0052]
Further, the contact position of the tip 15A of the pressing piece 15 of the protector 1 of the embodiment with the thermally responsive plate 12 is the center of the plate-like drawing process, which is substantially the center between the movable contacts 14A and 14B. Experiments have shown that the possibility of contact welding can be reduced by setting the abutment position from the center of the plate-shaped diaphragm to the protrusion near the fixed end of the thermally responsive plate. In this way, by setting the contact position of the pressing piece to the heat-responsive plate from the center to the center of the drawing process and closer to the protrusion that is the fixed end of the heat-driven plate, the contact of the heat-responsive plate can be used effectively. The possibility of welding can be reduced.
[0053]
Next, a second embodiment will be described. In the first embodiment, the elastic plate located between the heat-responsive plate support and the heat-responsive plate, which is a heat generating element, has a structure that partially shields the heat-sensitive plate support and the heat-sensitive plate. Therefore, the efficiency of heat transfer to the heat responsive plate may be insufficient. In this case, it is only necessary to increase the amount of heat generated by the thermally responsive plate support. However, it is difficult to take a method of reducing the cross-sectional area because some strength is required for its role, and it is also necessary to deal with changes in the material There are limitations due to weldability and other factors. Therefore, in the protector 21 of the second embodiment shown in FIGS. 11 to 13, the elastic plate 31 is provided with the heat responsive plate support to improve the heat exchange relationship between the heat responsive plate support and the heat responsive plate. The heat-responsive plate support that is configured to pass between the housing 30 and the housing 3 and that is a heat generating member is directly opposed to the heat-responsive plate.
[0054]
In the protector 21 shown in FIGS. 11 to 13, the same reference numerals are given to the same parts as those in the above-described embodiment, and the detailed description thereof will be omitted. The thermoresponsive plate support 30 is fixed to the housing 3 by fixing portions 30A provided at both ends. Further, the intermediate portion 30B has a detoured shape so as not to interfere with the pressing piece 35, and is provided with a slight step so as to protrude toward the housing, contrary to the above-described embodiment, in order to avoid interference with the elastic plate 31. It has been. The elastic plate 31 having an overall width selected so as not to interfere with the pressing piece 35 is fixed to the intermediate portion 30B by welding or the like so as not to interfere with the pressing piece 35. The thermally responsive plate 12 is fixed to the other end of the elastic plate via a fixing piece 13.
[0055]
Here, the elastic plate 31 is connected between the housing 3 and the thermally responsive plate support 30. Therefore, since the heat-responsive plate support 30 that is a heat generating member is directly opposed to the heat-responsive plate 12, the heat-responsive plate support is provided even when the resistance value of the heat-sensitive plate support, that is, the amount of heat generated cannot be increased. It becomes easy for heat from the heat to be transmitted, and the response of the protector to the overcurrent between the phases of the three-phase power supply can be made uniform.
[0056]
As described above, the pressing piece 35 has a shape in which protrusions that come into contact with the thermally responsive plate are provided at the front end portion and the rear end portion thereof, and is fixed to the inside of the calibration portion 3B of the housing 3 by welding or the like. The movable contact points 14A and 14B of the thermally responsive plate 12 are in contact with the vicinity of the center of the diaphragm on a center line that symmetrically divides, and the rear end portion 35B is in the vicinity of the protrusion 12A that is a fixed portion between the thermally responsive plate 12 and the elastic plate 11. It is close. When the thermally responsive plate 12 is reversed, the protrusion 12A comes into contact with the pressing piece rear end portion 35B to suppress the movement of this portion. Therefore, the amount of movement caused by the reversing force of the thermally responsive plate is reliably applied to the movable contacts 14A and 14B, and the reversing force effectively acts as a contact opening force. Can be separated.
[0057]
The attachment of the protector of the present invention described above to the motor winding will be described with reference to FIGS. One end of each of the lead wires 51A, 51B, 51C is connected and fixed to the lead terminal pins 5A, 5B and the metal plate 4 of the protector 1, respectively. The other ends of these lead wires are connected to respective phase windings of an electric motor, which will be described later. The protector 1 is covered with an insulating coating 52 such as polyester or polyamide, and is fixed by a method such as heat shrinkage or ultrasonic welding. In the present invention, the entire protector can be formed into an elongated shape while having a structure as a three-phase thermal protector, so that even when a heat-shrinkable tube such as a polyester tube is used as an insulation coating, the protector is inserted into the tube. The work becomes easier and the workability is improved as compared with a conventional protector having a wide shape.
[0058]
As shown in FIG. 15, the protector 1 thus covered with the insulation coating has the upper surface of the housing 3 in close contact with the coil end 61A of the electric motor 61, and the side of the housing 3 that has the bulge extends along the outer periphery of the coil end 61A. It arrange | positions so that it may be fixed with a tied string etc. This motor 61 is a Y-connected three-phase motor. As described above, the other ends of the lead wires 51A, 51B, 51C are connected to the respective phase windings of the motor, and the protector 1 opens and closes the midpoint of the motor. Has been.
[0059]
When mounted in this way, the width of the protector is wider than the width of the coil end in the case where the shape is almost the same in vertical and horizontal dimensions using a substantially circular thermal reaction plate like the conventional three-phase protector. As a result, there is a problem that the mounting becomes difficult. However, in the present invention, it is easier to make the width of the protector equal to or thinner than the width of the winding in order to be elongated and fit along the arc shape of the coil end of the motor stator winding in comparison with the conventional protector. Easy installation on the coil end of the motor.
[0060]
【The invention's effect】
The thermal protector of the present invention abuts on the side where the pressing piece is normally convex on the side of the thermally responsive plate in a state in which bypass current flowing between the pressing piece and the thermally responsive plate is not substantially problematic in the vicinity of the center of the throttle. As a result, the heat-responsive plate support as a heating element can surely generate a predetermined amount of heat, and the degree of freedom is widened in selecting the resistance value.
[0061]
In addition, a bypass that flows between the pressing piece and the thermal reaction plate by inserting an electrical insulator or a high resistance material as an insertion piece or the like between the contact portions of the pressing piece and the thermal reaction plate, or by being fixed integrally with the pressing piece. A state where the current does not substantially become a problem can be obtained.
[0062]
In addition, the thermal protector of the present invention is used to calibrate the operating temperature of a protector whose overall structure is also elongated by making the thermally responsive plate elongated in the horizontal direction compared to a protector having a shape having substantially the same vertical and horizontal dimensions. Even when the contact is welded, the pressing piece of the heat-sensitive plate is brought close to or in contact with at least the fixed portion between the heat-responsive plate and the elastic plate to prevent the force at the time of reversing the heat-sensitive plate from acting on the movable contact portion side. It can be used effectively as a force to open the contact. In addition, by adopting such a structure, even when the pulling force provided by the elastic plate cannot be set very large due to the structure, even when the force due to welding exceeds the pulling force, the force at the time of reversal of the thermally responsive plate is If the welding force between the contacts is superior, the contacts can be surely separated.
[0063]
In addition, by inserting a positioning member for defining the distance between the metal plate of the lid plate and the fixed contact support, even if the thickness of the fixed contact support is reduced in order to obtain a heating element The tip can be reliably held at a predetermined position, the voltage resistance between the metal plate and the fixed contact support can be ensured, and the amount of heat generated by the fixed contact support by the current can be increased.
[0064]
Furthermore, the structure in which the positioning member is elastically sandwiched between the fixed contact support and the cover plate facilitates the mounting of the positioning member and also conducts heat from the contact and the fixed contact support well to the housing. A direction in which the current value with the predetermined time being the time until the contact is opened (S / T) at the time of excessive current and the maximum limit operating current value (UTC) are fully exhibited. It has the feature that comes close to.
[0065]
Further, the heat responsive plate support, the elastic plate, and the heat responsive plate are arranged so as to be parallel to each other and face each other at a predetermined interval, and the heat responsive plate support is partially flat with the elastic plate interposed therebetween. By adjusting the heat exchange relationship between the thermally responsive plate support and the thermally responsive plate so as to face each other directly from the opening provided on the elastic plate, the fixed contact support or the thermally responsive plate support that is a heating element is adjusted. It can be adjusted so as to substantially equalize the temperature rise conditions of the thermally responsive plate at the time of energizing each electric path that passes.
[0066]
Further, the thermal reaction plate support, the elastic plate, and the thermal response plate are arranged so as to be substantially parallel to each other and face each other at a predetermined interval, so that the elastic plate is not interposed between the thermal reaction plate support and the thermal reaction plate. It is not possible to set the resistance value of the heat responsive plate support high by arranging it on the back side of the heat responsive plate support so that the radiant heat from the heat responsive plate support reaches the heat responsive plate without being blocked. Even in this case, the temperature rise conditions of the thermal reaction plate when energizing each electric path passing through the fixed contact support or the thermal response plate support, which is a heating element, can be adjusted so as to be substantially uniform.
[0067]
In addition, in order to prevent the pressing piece from coming into contact with the opposite side of the projection due to an error in assembly, the contact position of the pressing piece with the heat-responsive plate is changed from the center of drawing to the fixed end of the heat-responsive plate. By setting it closer to the protruding portion, the force of the thermally responsive plate can be used effectively and the possibility of contact welding can be reduced.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an example of a thermal protector according to the present invention.
FIG. 2 is a cross-sectional view of the thermal protector of FIG.
3 is a longitudinal sectional view showing a contact open state of the thermal protector of FIG. 1. FIG.
4 is a perspective view of the thermal protector of FIG. 1. FIG.
5 is an exploded perspective view of the thermal protector of FIG. 1 with a housing removed. FIG.
6 is a plan view of the thermal protector of FIG. 1. FIG.
7 is a side view of the thermal protector of FIG. 1. FIG.
FIG. 8 shows an example of a pressing piece used in the present invention.
FIG. 9 shows another embodiment of the pressing piece used in the present invention.
FIG. 10 shows another embodiment of the pressing piece used in the present invention.
FIG. 11 is a sectional view of another embodiment of the thermal protector of the present invention.
12 is a cross-sectional view of the thermal protector of FIG. 11 taken along the line B-B.
13 is a perspective view for explaining the internal structure of the thermal protector of FIG.
14 is a perspective view showing a state in which the thermal protector of FIG. 1 is covered with an insulating coating.
15 is a perspective view showing a mounting state of the thermal protector of FIG. 1. FIG.
FIG. 16 is a longitudinal sectional view of an example of a conventional thermal protector.
17 is a cross-sectional view of the thermal protector of FIG. 16 taken along the line CC.
[Explanation of symbols]
1,21: Thermal protector
2: Lid plate
3: Housing
4: Metal plate
5A, 5B: Lead terminal pin
6: Filler
7A, 7B: Fixed contact support
8A, 8B: Fixed contact
9A, 9B: positioning member
10, 30: Thermally responsive plate support
10A, 30A: fixed part
10B: Intermediate part
11, 31: elastic plate
11A: Intermediate part
11B, 11C: both ends
11D: opening
12: Thermally responsive plate
12A: Protrusion (connection part)
13: Adhering piece
14A, 14B: movable contact
15, 35, 45, 55, 65: Pressing piece (temperature adjustment mechanism)
15A, 35A, 45A: the tip of the pressing piece
15B, 35B, 45B: rear end of pressing piece
16: Insertion piece (electrical insulator)

Claims (9)

A lid plate in which through holes are provided in the vicinity of both ends in the longitudinal direction of the metal plate, and conductive lead terminal pins are hermetically penetrated and fixed to these through holes by an electrically insulating filler,
A generally long dome-shaped housing that is hermetically sealed with an open end face hermetically welded to the peripheral edge of the lid plate,
A fixed contact is conductively fixed to the inside of the sealed container of each lead terminal pin via a fixed contact support,
A pressure piece for operating temperature calibration is fixed to the inner surface of the housing by a method such as welding,
Further, the metal heat-responsive plate support is fixed to the inner surface of the housing at two locations with a sufficient interval in the longitudinal direction so as not to interfere with the pressing piece,
The heat-responsive plate support is electrically conductively connected and fixed via an elastic plate, and the heat-responsive plate that changes the bending direction in a snap manner according to different temperatures by being drawn into a shallow dish shape.
The thermally responsive plate is mounted so that two movable contacts can be opened and closed correspondingly to the fixed contact, approximately symmetrically with respect to the center of the plate-like diaphragm.
The pressing piece abuts in the vicinity of the center of the diaphragm on the normally convex side of the thermal reaction plate in a state in which bypass current flowing between the pressing piece and the thermal reaction plate does not substantially cause a problem, and at least the thermal reaction plate and In proximity to the elastic plate and in the vicinity of the fixed part, or in a state where the aforementioned bypass current is not substantially problematic,
By applying an external force from the outer surface side to deform the vicinity of the pressing piece fixing part of the housing, and adjusting the pressing force to the thermally responsive plate by the pressing piece, the contact pressure between the movable contact and the fixed contact is adjusted and adjusted at a predetermined temperature. The thermal protector is characterized in that the operating temperature can be calibrated so that the movable contact is separated from the fixed contact. The thermal protector according to claim 1, wherein an electrical insulator is inserted between contact portions of the pressing piece and the thermally responsive plate. The thermal protector according to claim 1, wherein the pressing piece has an electric insulator integrally fixed to a metal base portion. An imaginary line connecting each movable contact point from the connection portion between the thermally responsive plate and the elastic plate forms an angle of 90 ° or more, and an approximately isosceles triangle is constituted by three points of the connection portion and each movable contact point. The thermal protector of any one of Claim 1 thru | or 3.   The positioning member for prescribing the distance between the metal plate of the lid plate and the fixed contact support is disposed. Thermal protector.   6. The thermal protector according to claim 5, wherein the positioning member is elastically held between the fixed contact support and the cover plate. The thermally responsive plate support, the elastic plate, and the thermally responsive plate are substantially parallel to each other , and are disposed so that the thermally responsive plate support and the elastic plate, and the elastic plate and the thermally responsive plate face each other at a predetermined interval , The thermal reaction plate support is such that the radiant heat from the thermal response plate support reaches the thermal response plate directly through the opening provided in the elastic plate with the elastic plate in between the partial plane of the thermal response plate. The thermal protector of any one of Claims 1 thru | or 6 characterized by the above-mentioned. The thermally responsive plate support, the elastic plate, and the thermally responsive plate are substantially parallel to each other , and the thermally responsive plate support and the elastic plate, and the thermally responsive plate support and the thermally responsive plate face each other at a predetermined interval. Arranged and the elastic plate is not interposed between the thermal reaction plate support and the thermal reaction plate, and is disposed on the back side of the thermal reaction plate support, so that the radiant heat from the thermal reaction plate support is blocked. The thermal protector according to any one of claims 1 to 6, wherein the thermal protector is not reached.   9. The contact position of the pressing piece with the heat responsive plate is arranged from the center of the plate-shaped diaphragm to the protrusion portion which is the fixed end of the heat responsive plate. The thermal protector according to item.

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