JP3257680B2 - Thermal response switch and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetic compressor for a refrigerator and a thermally responsive switch suitable for protecting an electric motor used in such a compressor from overheating.

[0002]

2. Description of the Related Art A motor used for a hermetic compressor for a refrigerator, for example, is usually operated in a hermetically sealed housing with a refrigerant and lubricating oil circling around the motor.
Moreover, it must be taken into account that the pressure in the sealed housing fluctuates in a very wide range in consideration of the maximum value of the low pressure state and the high pressure state during non-operation or operation. In order to operate accurately in such an atmosphere and to respond to changes in the temperature and current of the windings of the motor and to open the electric circuit in the event of an abnormality and to stop the operation of the motor accurately, It is made an airtight container to prevent the intrusion of refrigerant etc. into the contact part of the switch under such an environment,
The container is required to have sufficient pressure resistance, heat sensitivity, characteristics of distinguishing abnormal current from normal current, small size, large switching capacity, and excellent durability. It has become particularly difficult to provide an inexpensive thermally responsive switch that satisfies the conditions, ensures stable production quality, and is inexpensive.

[0003]

Conventionally, as this type of thermally responsive switch, "thermally responsive switchgear" and "motor protection" described in Japanese Patent Publication Nos. 58-56213 and 62-6294, respectively. In the device, the sealed container of the thermoresponsive switch has sufficient pressure resistance so that the operating characteristics are not affected by severe temperature and pressure changes in the sealed housing containing the compressor including the motor as described above. However, there is a disadvantage that the thickness of the heat-sensitive plate made of bimetal or the like and having the movable contact and the sealed container of the switch including the fixed contact engaged therewith must be extremely large. . Further, since the relative positions of the movable contact and the fixed contact are associated when the switch case is finally sealed as a sealed switch, the confirmation must be performed by means such as X-rays after the sealing. It has a drawback that it cannot be easily performed. Further, the switch performs a repetitive operation of interrupting the energization in response to an abnormal current or an abnormal temperature flowing through the motor and allowing the energization again when the temperature returns to a safe temperature. The contact surface melts and scatters due to the heat generated by the arc between the contacts, and the fine scattered material of the contact material adheres to the surface of the electrical insulator, gradually increasing the electrical insulation distance between the movable contact and the fixed contact. Shrinking and weakening of the dielectric strength is one of the major factors determining its life. One solution is to increase the electrical insulation distance.However, this may lead to an increase in the size of the switch, or may require special heat resistance so that the insulator itself is not destroyed by the heat of the arc. There's a problem. SUMMARY OF THE INVENTION The present invention overcomes these problems, provides a small-sized, easy-to-manufacture, accurate calibration of the operating temperature of the thermally responsive plate, and provides a low-cost, long-life, stable, thermally responsive switch. is there.

[0004]

According to the thermal responsive switch of the present invention, a metal plate is formed by pressing a metal plate into a shape in which a cover constituting one of the containers has a substantially arc-shaped portion at an intermediate portion and both ends are nearly spherical. The sealed container is made of a molded long dome shape with excellent pressure resistance, and a header plate made by punching a metal plate into a flat shape including at least the open end surface to be welded to the open end surface. Be composed. The header plate is provided with a through hole on one side in the longitudinal direction, and a conductor is fixed to the through hole with an electrically insulating filler such as glass, and both ends of the conductor are respectively inside and outside of the airtight container. A predetermined length protrudes from the side. On the other side of the header plate, a fixed contact is provided inside the airtight container.

[0005] A metal heat-sensitive plate support is fixed at one end to a projecting portion of the conductor inside the airtight container along the longitudinal direction of the header plate by welding or the like, and at the other end is heat-resistant such as ceramic. Plate supporting part provided between the position where the calibrating piece of the heat responsive plate support is provided and the position fixed to the electric conductor, further comprising a calibrating piece made of conductive electrical insulating material. One end of a heat-responsive plate that changes the bending direction in a snap at different temperatures by forming a metal plate that is deformed by a change in temperature such as bimetal into a nearly rectangular shape but by drawing the center part into a shallow dish shape A movable contact made of a contact material such as silver or a silver alloy is fixed to the other end of the thermally responsive plate, that is, a side that changes position when the switching operation is performed in a snap manner, and is always fixed to the fixed contact. Arranged to touch To have. After the header plate and the long dome-shaped cover are hermetically fixed at the opening end face by welding or the like, the calibration piece comes into contact with the inner surface of the cover, and the other end of the thermally responsive plate support is attached to the calibration piece. Calibration of the snap-operating temperature of the thermally responsive plate where the movable contact separates from the fixed contact by allowing the contact pressure between the movable contact and the fixed contact to be adjusted by the principle of a roller by displacing the cover through the deformation of the cover This is a thermo-responsive switch characterized in that it can be performed precisely.

[0006] By the above-mentioned configuration means, the fixed contacts and the movable contacts are assembled and arranged on the header plate before the final step of forming the closed container, and the mutual positional relationship can be easily confirmed. In addition, the provision of the electrical insulating portion on one side in the longitudinal direction of the header plate and the provision of the fixed contact portion on the other side makes the operation life of the switch advantageous. That is, there is no fear that the electrical insulation distance is reduced by fine contact material scattered from the contact due to heat such as arc generated by opening and closing of the contact, and the fixed contact is attached to the header plate with large heat capacity with good heat conduction This is because the fixed contact whose temperature has risen due to the heat generated at the time of spark of the contact is rapidly cooled. The cover is easy to make because it has a wide open end and is relatively shallow drawn. The open end of the cover is brought into contact with the vicinity of the periphery of the header plate, and the two are air-tightly fixed by a method such as welding. Then, the cover is fixed to the conductor of the thermally responsive plate support via a calibration piece that comes into contact with the inner surface of the cover. When a force is applied to the other end, the thermally responsive plate support is deformed from the vicinity of the root of the fixed one end. The amount is smaller than the amount of movement of the calibration piece due to the amount of deformation of the cover. Accordingly, the operating pressure can be accurately calibrated by gradually adjusting the contact pressure of the movable contact with respect to the fixed contact.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 to 3, a cover 1 formed by, for example, drawing a rolled steel plate by press working is a long dome-shaped shallow container having an open end surface 1A. As shown in FIG. 3, the intermediate portion 1B has at least a substantially arc-shaped portion, and both end portions 1C are formed in a shape close to a sphere. A header plate 2 made by punching a thicker steel plate than the cover 1 is hermetically fixed to the opening end surface of the cover 1 by a method called ring projection welding in a process of sealing the switch. Header plate 2
A through hole 2A is formed in one of the longitudinal directions, that is, on the left side in FIG. 1, and a conductor 3 is provided in the center of the through hole 2A with an electrically insulating filler such as glass, ceramics or synthetic resin. 4 fixed.

For example, when the filler 4 is glass, it is appropriate to use an alloy of nickel and iron so as to form a compression-type seal in consideration of the thermal expansion coefficient of the header plate and the glass. is there. As shown in FIG. 1, the conductor 3 penetrates through the through hole 2A of the header plate 2, and the thermally responsive plate support 5 made of metal is shown in FIG. The left end is conductively fixed by welding or the like.

The thermally responsive plate support 5 has a planar shape as shown in FIG. 2 and, for example, six small welding projections 5A1 to 5A6 are formed at the fixed end 5A at the left end in the drawing. Can be easily and reliably fixed. In the vicinity of the right end, as shown in FIG.
A small hole 5B for positioning is formed. Further, a support portion 5C is formed by cutting and bending by pressing from the vicinity of the central portion of the thermally responsive plate support 5 toward the fixed end 5A, and, for example, six welding projections 5C1 to 5C are provided near the left end of the support portion 5C. 5C6 is formed. Further, as will be described later, a hole 5D is formed in the support portion 5C as necessary to facilitate the convenience of assembling and to improve the characteristics.
In addition, it is preferable to provide a rib 5F for increasing the strength in the longitudinal direction of the thermally responsive plate support 5 as can be fully understood with reference to FIG.

As shown in FIG. 1, an electrically insulating calibration piece 6 such as ceramic has a portion to be inserted into the small hole 5B of the thermally responsive plate support 5, a diameter larger than this portion, and a spherical upper end surface. It has a shape consisting of a head that becomes Of course, the shape of the calibration piece 6 is not limited to this embodiment, and it is easy to have any function as long as it electrically insulates and transmits the displacement force received from the cover 1 to the right end of the thermally responsive plate support 5. Is to be understood.

A metal plate displaced by a change in temperature, such as a bimetal or a trimetal, is punched into a substantially strip shape, and a substantially central portion 7B thereof is drawn into a shallow dish shape to perform a snapping motion. Are six projections 5C provided on the support portion 5C of the thermally responsive plate support 5.
It is fixed by welding with 1 to 5C6. A movable contact 8 having a contact surface made of silver or a silver alloy is fixed to the right end 7C of the thermally responsive plate 7 by welding. Movable contact 8
The fixed contact 9 for contacting or separating from the header plate 2 is fixed to the other side of the header plate 2 in the longitudinal direction, that is, the right side in the figure by welding or the like.

In assembling the thermally responsive switch of this embodiment, the conductor 3 is fixed to the center of the through hole 2A of the header plate 2 with the filler 4 and then the fixed contact 9 is fixed to a predetermined position of the header plate.
The fixed-side end of the thermally responsive plate 7 to which the movable contact 8 is fixed is fixed to the support portion 5C of the thermally responsive plate support 5. Next, the fixed end 5A of the thermally responsive plate support 5 is fixed to the conductor 3. In this state, the calibration piece 6 is inserted into the small hole 5B drilled near the free end of the thermally responsive plate support 5 so that the movable contact and the fixed contact are almost lightly contacted or opposed to each other with a very small gap. Check whether it is installed. As can be clearly seen in FIG. 4 in which a part of FIG. 1 is enlarged, the distance D from the upper surface of the thermally responsive plate 7 to which the movable contact 8 is attached to the lower end surface of the calibration piece.
Is within the specified dimensional tolerances. Distance D
Is large, the arc generated when opening and closing the contacts becomes large,
It is not good to be too small. This distance D is slightly reduced by the operation for calibrating the operating temperature, which will be described later, but it is necessary to consider this in advance. Furthermore, when the cover 1 is welded to the header plate, it is checked whether the inner surface of the cover 1 has a slight gap with the upper end surface of the calibration piece 6 or has a size that makes light contact with the upper end surface of the calibration piece 6 in consideration of the fact that the cover becomes shallow due to welding. I do. If these conditions are satisfied, the cover 1 is air-tightly fixed to the header plate 2 by welding.

If the above conditions are not satisfied, the narrowed portion 5E near the fixed end 5A of the thermally responsive plate support 5 and the base of the support portion 5C are deformed to adjust the conditions, and then the cover is formed. 1 is hermetically welded and fixed to the header plate 2. In this case, forming a 5D hole near the root portion facilitates the bending operation.

When the airtight container is completed, as shown in FIG. 4, the jigs G1 and G2 sandwiching the header plate 2 and the cover 1 move the thermally responsive plate 7 at a predetermined operating temperature to a dotted line in FIG. Cover 1 so as to reverse its bending direction as shown in FIG.
Is recessed as shown by the dotted line in FIG. This gives a downward bending deformation to the narrow portion 5E near the fixed end of the thermally responsive plate support 5 via the calibration piece 6, and causes the thermally responsive plate 7 to be displaced clockwise in FIG. give. As a result, the contact pressure between the movable contact 8 and the fixed contact 9 is increased, thereby eliminating the chattering when the thermally responsive plate is inverted at a predetermined operating temperature and the movable contact 8 is separated from the fixed contact. At the same time, it can be calibrated to a predetermined operating temperature.

In the thermal responsive switch constructed as described above, in an atmosphere of a predetermined temperature, for example, 150.degree. C., the thermal responsive plate rapidly jumps and turns as shown by the dotted line in FIG. When the temperature reaches 80 ° C, it jumps back and returns to the state shown by the solid line. 1 to 3
As shown in (1), the lead wires indicated by symbols 10 and 11 are fixed by welding or the like, and connected in series to a circuit for supplying a current to the electric motor. Although an excessive current flows at the time of startup, when the normal startup is completed and the operation state is entered, the current becomes a rated value, so that the temperature of the thermally responsive plate does not rise to a predetermined operating temperature and the thermally responsive switch does not operate. The current flowing through the thermoresponsive switch of this embodiment is a lead wire 10-a conductor 3-a thermoresponsive plate support 5-a thermoresponsive plate 7-a movable contact 8-a fixed contact 9-a header plate 2-a lead wire 11.
However, when the heat generated by the resistance of this circuit causes the heat responsive plate 7 to reach a predetermined temperature, for example, 150 ° C., the position becomes an inverted position as shown by the dotted line in FIG. 1 and the current supplied to the electric motor is cut off. At this time, an arc is generated between the movable contact and the fixed contact, and a part of the movable contact and the fixed contact is melted by Joule heat and arc heat, and a small amount of loss occurs. The fine particles corresponding to the loss are scattered from between the contacts, and when the fine particles reach the surface of the filler 4 insulating between the contacts of the switch, the deterioration of the insulation gradually progresses, and the service life is eventually reached. However, in the present invention, the distance between the contact portion 5 and the filler 4 can be sufficiently set in the longitudinal direction of the switch, which is very advantageous against deterioration of insulation. Further, the heat received by the fixed contacts is conducted to the header plate having a large heat capacity, and the temperature is rapidly lowered, which is advantageous in preventing the wear of the fixed contacts.

Further, the heat received by the movable contact is absorbed by the thermally responsive plate, and the temperature of the thermally responsive plate is not lowered for a certain period of time after the current stops flowing. Extend the off-time until reaching 80 ° C. This has the advantage of extending the life of such automatically responsive switches. Of course, it is also advantageous as an action of suppressing a rise in the temperature of the motor to be protected. Also, a hole formed in the support portion 5C provided in the thermally responsive plate support 5.
When the temperature of the thermally responsive plate is radiated from the thermally responsive plate support 5 via the conductor 3 by 5D, the spot where the hole 5D is drilled has a high temperature due to the increased electric resistance. And a reduction in the heat conduction cross-sectional area is advantageous in that the temperature of the thermally responsive plate becomes difficult to escape due to a synergistic effect, and a long time until the operation is restored after the operation is maintained.

[0017]

As described above, according to the present invention, since the fixed contacts and the movable contacts are assembled and arranged on the header plate before the final step of forming the closed container, the mutual positional relationship can be confirmed. Easy. The sealed container is very pressure-resistant, and the distance between the contact and the electrical insulation can be increased. There is an effect that it hardly adheres to the surface of the electrically insulating filler.

Further, the heat received by the movable contact is absorbed by the thermally responsive plate, and there is an effect that the temperature of the thermally responsive plate is not lowered for a certain period of time after the current stops flowing, and reaches a temperature at which it is automatically restored. Extend the off-time before doing so. Also, when the temperature of the thermally responsive plate is radiated from the thermally responsive plate support via the conductor by the hole formed in the support portion provided in the thermally responsive plate support, the hole is pierced. The synergistic effect of the high temperature spot due to the increased electrical resistance and the reduced heat conduction cross-sectional area makes it difficult for the temperature of the thermally responsive plate to escape and the time it takes to return after operation This is advantageous in that it is kept long. These facts are advantageous in extending the life of such a thermally responsive switch that repeats itself. Further, the heat received by the fixed contacts is conducted to the header plate having a large heat capacity, and the temperature is rapidly lowered, which is advantageous in preventing the wear of the fixed contacts.

In the calibration of the operating temperature, after a closed container is constituted by the cover and the header plate, a force is applied to the other end of the thermally responsive plate support which is not fixed to the conductor through a calibration piece which comes into contact with the inner surface of the cover. As a result, the thermally responsive plate support is deformed from the vicinity of the root of one end to which the thermally responsive plate is fixed. Less than the displacement of the calibration strip by volume. Accordingly, the operating pressure can be accurately calibrated by gradually adjusting the contact pressure of the movable contact with respect to the fixed contact.
As described above, according to the present invention, it is easy to manufacture a small-sized, highly accurate calibration of the operating temperature of the thermally responsive plate, and it is possible to provide a low-cost stable thermally responsive switch with a long life.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a thermally responsive switch of the present invention.

FIG. 2 is a view of the heat-responsive switch of FIG.
-A section arrow view

FIG. 3 is a view B of the thermoresponsive switch of FIG. 1 with only the cover cut off;
-B sectional view

FIG. 4 is a partially enlarged view of FIG. 1;

[Explanation of symbols]

 1: Cover 2: Header plate 3: Conductor 4: Filler 5: Thermal response plate support 6: Calibration piece 7: Thermal response plate 8: Movable contact 9: Fixed contact

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Isao Toho 178 Kita, Kasumigaoka-cho, Owariasahi-city, Aichi Prefecture (72) Inventor Hideki Koseki 40-2, Oyama-Nishi, Minamiyama, Fuso-cho, Niwa-gun, Aichi Prefecture (56) References Akira Tokubo 62-6294 (JP, B2) JP-B-58-56213 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01H 37/00-37/56

Claims (3)

(57) [Claims] 1. A long dome-shaped cover made of metal, a header plate welded to an open end face of the cover to form a closed container, and the header plate has a planar shape of the long dome-shaped cover.
Becomes the opening end surface shape from at least include the shape and metal plate, through hole is provided at one of the longitudinal direction of the header plate, both surfaces direction to the through hole conductive material penetrates the header plate <br / Each of the conductors projecting a predetermined length and airtightly fixed by an electrically insulating filler material such as glass, One end of the thermally responsive plate support is fixed along the longitudinal direction of the header plate, and a calibration piece formed of a heat-resistant electrically insulating material is provided between the other end of the thermally responsive plate support and the cover. The thermal responsive plate support is further provided with a thermal responsive plate support at a portion closer to the fixed portion with the conductor than the calibration piece insertion position, Deforms in response to temperature changes such as bimetal That it is made of a material and one longitudinal end of the thermally responsive plate to vary the snap to the bending direction in accordance with the different temperatures by molded stop the central dished are fixed, the other end i.e. snap thermally responsive plate Electrical contact material on the end that moves during the dynamic movement
The movable contact is provided so as to come into contact with or separate from a fixed contact fixed to the other side in the longitudinal direction of the header plate, and the cover is deformed by an external force. As a result, the contact between the conductor fixing portion of the thermally responsive plate support and the thermally responsive body support portion is deformed via a calibration piece inserted between the other end of the thermally responsive plate support and the cover. A thermoresponsive switch characterized in that it is possible to precisely adjust the contact pressure between the movable contact and the fixed contact, and to calibrate the operating temperature at which the movable contact is separated from the fixed contact at a predetermined temperature. 2. A long dome-shaped cover made of metal, a header plate welded to an open end surface of the cover to form a closed container, and the header plate has a planar shape of the long dome-shaped cover.
It has a shape including at least the shape of the open end face and is made of a metal plate thicker than the cover. A through hole is provided in one of the longitudinal directions of the header plate, and a conductor is provided in the through hole. Penetrating its both sides
Each of the conductors projecting a predetermined length in the direction is hermetically fixed by an electrically insulative filler such as glass, and the conductor protruding into the inside of the closed container formed by the header plate and the cover is made of metal. One end of the thermally responsive plate support is fixed along the longitudinal direction of the header plate, and a calibration piece formed of a heat-resistant electrically insulating material is provided between the other end of the thermally responsive plate support and the cover. is inserted so as to be positioned, they are further provided with a supporting portion of the thermally responsive plate portion near the fixing portion of said conductor by the calibration piece mounting position is in thermally responsive plate support, the support portion And in the vicinity thereof, a portion having a reduced cross-sectional area, less likely to generate heat conduction, and a portion easily heated, and the supporting portion is made of a material such as a bimetal which is deformed in response to a change in temperature and is formed at the center thereof. in that the molded aperture in the dish-shaped the Varies depending on the temperature at one longitudinal end of the thermally responsive plate to vary the snap to curve direction is secured, the electrical contacts at the other end i.e. the end to move during the snap movement of the thermally responsive plate I
A movable contact made of a material is provided; a fixed contact is fixed to the other longitudinal side of the header plate; the fixed contact is disposed so as to contact or separate from the movable contact; Is deformed by an external force to deform between the conductor fixing portion of the thermally responsive plate support and the thermally responsive plate support portion via the calibration piece inserted between the other end of the thermally responsive plate support and the cover. As a result, it is possible to precisely adjust the contact pressure between the movable contact and the fixed contact, and to calibrate the operating temperature at which the movable contact is separated from the fixed contact at a predetermined temperature. 3. A metal long dome-shaped cover, and a metal plate header whose planar shape at least includes the open end surface shape of the long dome-shaped cover to be welded to the open end surface of the cover. It has a plate, a through hole provided on one longitudinal header plate, double-sided direction conductors through the header plate in the through hole
A material that protrudes a predetermined length from each other and is hermetically fixed with an electrically insulating filler such as glass, a fixed contact is fixed at a predetermined position on the other side in the longitudinal direction, and a material such as a bimetal that deforms in response to a change in temperature. The center of the plate is drawn in the shape of a dish and the bending direction is changed at the time of snapping according to different temperatures, and a movable contact is fixed to one end in the longitudinal direction. The other end of the thermally responsive plate is made of metal. fixed to the support portion of the thermally responsive plate arranged in thermally responsive plate support, the fixed contact and the movable contact is confronted with the end portion of the heat responsive plate support
A step of sticking to the conductor so that the planar positional relationship as to the steps of attaching a calibration strip in the vicinity of the free end of the thermally responsive plate support, or a predetermined dimension fixed contact and the movable contact is in contact with After the step of ensuring that the distance between the thermoresponsive plate and the calibration piece is within a predetermined dimensional tolerance, and then the step of ensuring or adjusting the distance between the thermally responsive plate and the calibration piece, the cover is hermetically welded and fixed to the header plate. A method of manufacturing a thermally responsive switch for calibrating an operating temperature including a step of forming an airtight container and deforming a cover.