JPS63174234A - Protector with closed double safety mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is used for a hermetic electric compressor, etc., and is used to protect the windings from burning out when the motor is abnormal, and when the life of the protector is over. In order to prevent damage to the shallow groove [in the sealed dome which has reached abnormally high temperatures such as the above] and to prevent high-pressure gas from destroying the weakest part of the sealed dome and spewing out flames, etc., the contacts of the protector are normally closed. The present invention relates to a sealed protector having a double safety mechanism that interrupts the circuit at a second stage temperature that is a predetermined temperature higher than the first stage temperature at which the circuit is opened.

[Background technology]

Conventionally, hermetic electric compressors compress refrigerant gas such as Freon inside a hermetically sealed dome, send it outside the hermetically sealed dome to perform thermal work, and then return it back inside the hermetically sealed dome to circulate it within the cooling and heating system. , its compression pump is driven by an electric motor.

If a load torque higher than the rotational torque of the motor occurs due to some abnormality and the rotor is restrained, a current several times that of rated operation will continuously flow through the stator windings, causing a A motor protector that opens and closes a pair of contacts using a heat-responsive plate made of pie metal, etc., is placed to open and close the electric circuit so that the heat-resistant temperature of the insulation coating of the motor windings does not exceed the safe upper limit temperature of the first stage. If the load torque falls below the starting torque of the motor, the motor should be operated, and even if there is a problem in which the temperature of the motor etc. rises abnormally due to refrigerant gas leakage, the upper limit temperature of the first stage mentioned above should be exceeded. The contacts of the protector supply power to the motor intermittently to prevent this. However, if the protector is opened and closed many times and reaches the end of its life, the contacts may become welded and released, causing a short circuit and a large current to flow due to insulation deterioration of the motor windings, causing severe damage inside the sealed dome. The temperature became so high that there was a risk that the weakest part of the dome, for example the cluster, which insulates the terminals and keeps them airtight, could come loose, causing flames to burst out and cause a fire. Conventionally, current fuses, etc., have been used in conjunction with this, but as the temperature rises beyond the first stage, the impedance of the motor increases and the current tends to decrease, so current fuses have no practical effect, and temperature fuses However, it has not been possible to obtain a suitable product at a low cost for use inside the dome of a hermetic electric compressor.

[Summary of the invention]

In the sealed double safety device protector of the present invention, if the operating temperature when the thermally responsive plate opens the contact as a normal protective operation is, for example, 180°C, the temperature at the first stage is higher than that, for example, 200°C. It also has a mechanism that opens the switch circuit depending on the set second stage operating temperature, and is usually configured to open at the first stage temperature and open/close at an appropriate return temperature lower than this. ing.

[Embodiments of the invention]

As shown in FIGS. 1 and 2, a relatively thick iron plate is attached to the left open end IA of the container 1, which is formed by deeply drawing an iron plate and has a closed end on the right side, and an oval cross section. The cover plate 2 made of is ring projection welded. As is clear from FIG. 2, approximately in the center of the cover plate 2, a lead pin 3 is hermetically fixed in a through hole zA with a filling material 2B made of an electrically insulating material such as glass. A fixed contact holding plate 4 having a fixed contact 5 having a contact portion made of a material such as silver cadmium oxide fixed near the tip of the lead pin 3 is fixed to the lead pin 3 at the base by a method such as butt welding.

As clearly shown in FIG. 2, support legs 6/6B provided at the base of the support 6 are fixed to the lid plate 2 by a method such as welding. The side opposite to the legs 6A and 6B of the support body, that is, near the right end in the figure, is bent into a U-shape to form a support portion 6C.
Further, a female thread 6D is bored approximately in the center of the support body 6, into which a male thread 7 is inserted. The movable contact 11 that pairs with the fixed contact 5 is fixed to the movable end and is made of a material that deforms due to thermal changes, such as a bimetal. The heat-responsive plate 10 has a connection made of a slightly thick iron plate or the like at its base, that is, the right end in the figure. It is fixed via a piece 9 to a connecting plate 8 made of an elastic elongated leaf spring. The left end of the connecting plate 8 in the figure is fixed to the vicinity of the base of the support 6. As is well known, the thermally responsive plate 10 has a portion 10A formed approximately in the center into a shallow dish shape, and is curved so that its lower surface is concave at room temperature.

The resilient connecting plate 8 exerts a force that constantly presses the base of the thermally responsive plate 1o against the support portion 6C of the support body 6 via the connecting piece 9 by its restoring force, and the end of this connecting plate
The movable plate 10 is fixed to the movable end by applying a predetermined pressure directly or through a heat-resistant electrical insulator (not shown) to slightly deform the curved portion of the heat-responsive plate 10 so as to bend it. By bringing the contact 11 into contact with the fixed contact 5 and applying this contact pressure, the external screw 7 is inserted so as to cause the thermally responsive plate 10 to perform a rapid reversal operation at a predetermined temperature, for example, 180° C. in the first stage, as is well known. Temperature can be calibrated.

The shape of the inverted thermally responsive plate 10 is as shown by the dotted line in FIG. In the protector of this embodiment, the electric current of the motor is passed from the lead pin 8 to the fixed contact 5 to the movable contact 11-4 to the thermally responsive plate 1.
0→connection piece 9→connection plate 8→support 6 to cover plate 2, and self-heating due to the electrical resistance of this circuit causes a rise in temperature of thermally responsive plate 10.

It goes without saying that this temperature rise is determined by electrical resistance, but it is obvious that the electrical conductivity of the support 6 is negligible compared to the electrical conductivity of the connecting plate, the connecting piece 9, and the thermally responsive plate 10. If the material is made of a very good material, the contact resistance between the support part 6C of the support body 6 and the connection piece 9 fixing the thermally responsive plate and the external thread 7, in addition to the current in the path as described above, It is necessary to prevent the current from being shunted due to contact resistance with the thermally responsive plate on the lower end surface of the board, but this can be done by interposing visible electrically insulating paper with excellent heat resistance at each of the contact parts mentioned above. This can be prevented by letting it happen. When the temperature of the heat-responsive plate 10 rises and becomes the state shown by the dotted line, it naturally cools to about 130°C, for example, and the bending direction returns to the original state shown by the solid line in Figure 1. resume. This kind of repeated operation is well known as a protector, but in this embodiment, the number of times this normal protective operation is repeated is set as a safety standard, for example, 18 days or 10,000 times or more. If the normal protective operation continues, even if the thermally responsive plate reaches the specified operating temperature, there will be slight welding between the movable contacts and the fixed contacts, and the reversing force of the thermally responsive plate will deteriorate, causing the current to drop. The tripping action to cut off the circuit is no longer possible, and the current continues to flow, causing the ambient temperature, including the motor, to continue to rise, causing breakdown of the insulation, shorting the windings, causing a large current to flow, causing a fire inside the sealed dome, and destroying the dome. There is a risk that the weak part of the cluster, which is the weak part of the cluster, may be pierced and flames may blow out to the outside, causing a fire. Therefore, to prevent this from happening, the protector of this embodiment is provided with a support 6 as shown in FIG.
Another holding piece 13 is fixed to the lower surface of the right end support part 6C,
A second heat-responsive plate 12 made in advance to have a temperature of about 200°C at which the holding piece 13 flips a metal plate such as a bimetal so as to knock up the deteriorated thermally-responsive plate 10 from the bottom to the top in the figure. is fixed. The temperature at which the second thermally responsive plate 12 reverses its bending direction as indicated by the dotted line is higher than the operating temperature of the thermally responsive plate 10 during normal operation, and it is not inserted into the circuit through which the motor current directly flows, so it cannot be used except in abnormal situations. Absolutely not working. In other words, since the bending direction does not change and the shape is almost similar to that shown by the solid line, it does not deteriorate and exerts sufficient force in the event of an abnormality. Second thermally responsive plate 1
2 is reversed to the state shown by the dotted line, the bending direction of the normal thermally responsive plate 10 is already in the direction shown by the dotted line, but the movable contact 11 is unavoidably separated from the fixed contact 5 due to the welding force between the contacts. At this time, if the second thermally responsive plate 12 receives an impact force due to the strong reversal movement from below, the welded movable contact 11 will be easily separated from the fixed contact 5 and the current supplied to the motor will be cut off. be done. In addition, if it is possible to provide a diaphragm υ shape designed so that the return temperature of the second thermally responsive plate 12, that is, the temperature at which it reverses from the state indicated by the dotted line to the original bending direction, is a very low temperature, for example, around -30°C, the contact point Even if the return temperature is slightly higher than normal temperature, the cycle of re-energizing the motor is very long, so abnormalities can be noticed and fires can be prevented. The second thermally responsive plate 12 shown here is a dual safety mechanism that responds to the second stage temperature.

Another embodiment of the invention is shown in FIG. 3, which differs from that shown in FIGS. 1 and 2 by a dual safety mechanism responsive to the second stage temperature. Since the other parts are understood to indicate animals such as monsters with the same symbols as in FIG. 1, their explanation will be omitted. The symbol 14 in FIG. 3 is a bullet plate made of steel or the like, and its right end 14A is fixed to the inner surface of the container 1 by a method such as welding. υThe shape of the bullet plate 14 in a normal free state. is shown by a dotted line, and is forcibly deformed in an elastic region as shown in the figure, and is fixed to the inner surface of the container 1 by soldering to the easy-melting metal 15, which is an alloy of tin and lead that melts at 20°C. It is. Therefore, as mentioned above, when the normal operation of the protector exceeds its life cycle, the movable contact 1
When the fixed contact 1 is not opened from the fixed contact 5, the temperature of the Tekta container 10 decreases due to the rise in ambient temperature.When the temperature of the easily melted metal 15 reaches, for example, 200°C, it becomes soft and cannot resist the restoring force of the resilient plate 14. Since there is no restraint, the resilient plate 14 can forcibly push the thermally responsive plate 1o upward to separate the movable contact 11 from the fixed contact 5.

Next, a third embodiment will be explained with reference to FIG.

In this embodiment, unlike the one shown in FIG. 1, the fixed contact plate to which the fixed contact 5 is fixed has a double safety mechanism in which it separates in response to the second stage temperature.

The other parts have the same symbols as in Figure 1 and are omitted because they do not seem to require explanation, but the double safety mechanism shown by symbols 12 and 13 in Figure 1 can be omitted in this embodiment. be. In FIG. 4, the fixed contact plate 16 is composed of three parts, each of which is designated by the symbols 16φA, 16B, and 16C. The symbol 160 is made of, for example, a steel plate.The fixed contact 5 is welded to the position where the symbol 160 is made, for example.
It is formed by soldering with an alloy of tin and lead that has a softening temperature of 0°C. After being formed in this way, the portion 16A is fixed to the lead pin 3 by spot welding or the like. As is well known, this spot welding process is instantaneous welding using a capacitor-type discharge, and is capable of fixing easily melted metal parts without softening them. In this embodiment, if the thermally responsive plate 10 exceeds its normal opening/closing life, the movable contact 11 and the fixed contact 5 will be welded together and cannot be removed, causing the ambient temperature including the motor to increase. When the temperature of the fixed contact plate 16 reaches 200°C, the portion 16
The easy-to-melt metal layer 16D between A and 16B and the easy-to-melt metal J116E between parts 16B and 160 are softened and lifted and separated as shown in FIG. 5 to cut off the current and allow the equipment to cool naturally. Even if the thermally responsive plate 10 returns to its original state, the portion 16B of the fixed contact plate 16 will be missing and the protector will not become energized again and the intended purpose will be achieved. be done. Also, the symbol 1 indicates the part of the easily melted metal.
Even if it is composed of the entire part shown in 6B! If the design is possible without problems such as air resistance, the fixed contact plate 16 should be placed in the portion 16A.
and 160 are made of iron, copper, or a cladding material thereof, and a portion corresponding to the length of 16B between them is fixed with an easily melted metal. In this way, when the easily melted metal part softens and separates, there is no possibility that the easily melted metal part will liquefy due to the sparks generated when the current is cut off, become fine particles, and then turn the protector energized again, thus serving as a double safety mechanism. Achieve.

〔Effect of the invention〕

A sealed type protector for a motor that is used under high pressure and in a special atmosphere such as Freon gas can be added with a small number of parts to prevent the motor from overheating when the contact closes and the life of the protector part is over. As long as the insulating material is not destroyed by the temperature rise, the motor current tends to decrease due to the temperature vs. resistance characteristics of the copper wire, and as the temperature rises, the conventional current fuse cannot prevent fires due to burnout. This is a very effective safety device that completely covers the shortcomings of

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention, and FIG.
A cross-sectional view taken along line nn in the figure, and FIGS. 3 and 4 are longitudinal cross-sectional views according to another embodiment, respectively. 5 and 6 are partial views illustrating the state of the mechanism that operates according to the second stage temperature of the embodiment shown in FIG. 4. FIG. ■・・・Bottomed container, 2・・・・・・・・・
・・Lid plate, 5・・・・・・・・・・Fixed contact,
10......Thermal response plate, 11...
・・・・・・・・・Movable contact, 12/14/15/16
D・16E・・・・・・・・・Mechanism that deforms at the second stage temperature.

Claims (1)

[Claims] A movable contact is driven by a heat-responsive plate that deforms depending on temperature, such as a bimetal, in a metal sealed container, and is normally separated from a fixed contact paired with the movable contact at the first stage temperature, and then restarted at a lower return temperature. In a protector that opens and closes so that both contacts are brought into contact, when the contacts are welded, the driving force of the thermally responsive plate makes it impossible to separate the contacts, resulting in an increase in temperature of equipment such as electric motors to be protected. When the temperature of the protector advances and reaches a predetermined second stage temperature exceeding the normal operating temperature, the member to which the movable contact or the fixed contact is welded is deformed in accordance with the second stage temperature to complete the electric circuit. A sealed type protector with a double safety mechanism, which is characterized by having a mechanism for opening it.