JPH0445387A - Protection circuit of freezer device - Google Patents

Abstract

PURPOSE:To protect all devices and prevent accident of the devices from occurring by a method wherein an operation of a circuit shielding device is performed by sensing a temperature and a sensing part is fixed to an electric motor for a blower and a timer electric motor or the like, an abnormal increasing of temperature generated when an abnormal high voltage is applied is detected and then the circuit is turned off. CONSTITUTION:When an abnormal high voltage is applied during an operating condition, a winding temperature of an electric motor 4 for a compressor is rapidly increased. The winding temperature is detected by an over-load protection device 5, the circuit is turned off and then an electric motor 4 for the compressor is stopped for its operation. When an abnormal high voltage is applied to a timer electric motor 2 and an electric motor 6 for a blower, an over-current is flowed in a coil and a heating amount is increased more than that obtained by applying a normal voltage, so that a temperature of the coil is substantially higher than the normal one and is stabled. In addition, if an electrical energization is continued, an insulation of the coil is deteriorated by this high temperature and a rare short state is attained. In this case, a temperature fuse 21 closely contacted with and fixed to the surface of the coil of the electric motor 6 for blower is melted and cut by heat of high temperature at the coil. Since the temperature fuse is disposed at the position nearest to the power supply in the electrical circuit, the power supply for all devices constituting a refrigerator is turned off through the melting cut of the temperature fuse.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a protection circuit for a refrigeration system, and particularly relates to a means suitable for protecting a refrigeration system when an abnormally high voltage is suddenly applied. .

[Conventional technology]

A conventional example will be explained with reference to FIG. 4 "Refrigerator Electrical Circuit".

In the figure, 1 is a timer device for defrosting, and 2 is a timer motor. It is equipped with a switching contact 3 and terminals a and b.

Reference numeral 4 denotes a compressor electric motor, which is constructed together with a compressor in a closed container, and is equipped with an automatic return type overload protection device 5 on the outside. A blower motor 6 forms a parallel circuit with the compressor motor 4, and one end thereof is connected to the terminal a of the defrosting timer device 1. 7 is a bimetal thermostat that detects the end of defrosting and shuts off the circuit; one end is connected to the terminal of the defrosting timer device 1, and the other end is connected to one end of the timer motor 2 and one end of the defrosting heater (described later). Connecting. Numeral 8 is a defrosting heater, which is installed at or near the evaporator. Numeral 9 is a temperature fuse, which is connected in series with the defrosting heater 8. 1
0 is a thermostat that controls the operation of the compressor motor 4. When the switching contact 3 of the timer device 1 is connected to the terminal a side, one end of the parallel circuit of the compressor motor 4 and the blower motor 6 is connected to the switching contact 3 of the timer device. The other end is directly connected to the power supply via the thermostat 10,
Connected to power. Also, one end of the defrosting heater 8 is connected to a timer motor 2. to the power supply via the thermostat 10,
The other ends are respectively connected to a power supply via a temperature fuse 9. That is, compressor electric motor 4. Blower electric motor 6
．． Timer motor 2. The defrosting heater 8 is energized for cooling operation, but since the resistance of the defrosting heater 8 is extremely small compared to the coil impedance of the timer motor 2, almost no voltage is applied and no heat is generated. In addition, the defrosting timer device 1
When the switching contact 3 is connected to the terminal side, the parallel circuit of the compressor motor 4 and the blower motor 6 is not operated because one end is disconnected from the power supply. timer motor 2
Since both ends of the defrosting heater 8 are at the same potential through the switching contact 3 and the bimetal thermostat 7, they do not operate, and defrosting is performed by applying power supply voltage to the defrosting heater 8 and generating heat. Additionally, related devices of this type include:
For example, Japanese Utility Model Publication No. 57-1266 can be mentioned.

[Problem to be solved by the invention]

The above-mentioned conventional technology causes various problems when the power supply voltage suddenly becomes abnormally high for reasons to be described later. less than,
Explain why the power supply voltage suddenly becomes abnormally high. Figure 2 shows the three-phase, four-wire system adopted in most foreign countries, and each house is equipped with Al, A2. Arrange H three wires, Al-N, A indoors
2-N line voltage is wired to each room. It is well known that the wiring should be done in consideration of the inputs of the loads 11 to 16 and in such a way that the current flowing through the neutral wire N will be as low as possible. However, during seasons such as summer when power usage increases, an imbalance occurs in the amount of load mentioned above.

The entire line including the neutral wire N or the terminal of the neutral wire N becomes overloaded. If this overload condition continues or is repeated, it will lead to disconnection and poor continuity. The voltage between A1-A2 is five times the normal voltage, but when the neutral wire N is disconnected, the voltage applied to each load is between A1-8 and the total impedance of the current load Z1 and A2-8. It is proportionally divided according to the ratio of the total impedance Z2 of the load that is energized. That is, if the normal voltage is E, the voltage across AI-8 is σE-Zl/Z1+22 since the neutral wire N is disconnected.At this time, if the impedance of zl is extremely large compared to 22, For example, in Figure 2, when a refrigerator is connected between AI-8 and multiple room air conditioners are connected between A2-8 and the neutral wire N is in operation, the voltage between If the wire breaks, approximately σ times the normal voltage will be applied to the refrigerator. As a result, the abnormally high voltage far exceeds the protective function of each load, leading to serious accidents. Hereinafter, the state that occurs when an abnormally high voltage is applied to each component of the refrigerator shown in FIG. 4 will be explained. When the thermostat 10 is in a conductive state, the switching contact 3 of the timer device 1
is connected to the terminal a side, the compressor motor 4
When the winding temperature suddenly rises, the overload protection device 5 installed outside the compressor senses this temperature and operates, cutting off the circuit.
Stop driving. But overload protection! ! 5 is a reset type, so when the compressor temperature drops to a certain temperature due to suspension of operation, the power is re-energized. That is, the compressor electric motor 4
Since the starting current is applied and the overload protection device is activated repeatedly until the overload protection device [5] is broken, the compressor motor 4 will burn out if the overload protection device 5 eventually breaks due to contact. Since the blower motor 6 does not have a protection device, an abnormally high voltage is continuously applied to the blower motor 6, resulting in an abnormal rise in temperature of the windings, insulation deterioration, layer short-circuiting, smoke generation, and ignition. The timer motor 2 forms a series circuit with the defrosting heater 8, but since the impedance of the timer motor 2 is extremely large compared to the impedance of the defrosting heater 8, most of the voltage is applied to the timer motor 2. Ru. Therefore, if an abnormally high voltage is applied, an abnormal temperature rise in the windings, insulation deterioration, and layer short circuit will occur, but since the defrosting heater 8 is connected in series to the timer motor 2, the timer motor 2 When the layer short-circuits, the defrosting heater 8 generates heat. At this time, the impedance of the timer motor 2 is equal to zero because of the layer short circuit, and substantially all of the abnormally high voltage is applied to the defrosting heater 8. Therefore, the amount of heat generated is approximately three times the normal amount, causing the ambient temperature to rise rapidly. Note that since a temperature fuse 9 is connected in series to the defrosting heater 8, when the set temperature is reached, the temperature fuse 9 is blown and the defrosting heater 8 stops generating heat. Even if an abnormally high voltage is applied with the contact 3 of the defrosting timer device 1 conducting to the terminal side, the temperature fuse 9 will melt and the defrosting heater 8 will stop generating heat. Applying a voltage that is abnormally high compared to the rated voltage of electrical equipment in this way can cause serious accidents such as destruction of the equipment, but this is especially true for equipment that is installed and operated away from one person's eyes, such as refrigerators and room air conditioners. This is a serious problem since the equipment may cause a fire. Moreover, since abnormal high voltage occurs extremely rarely and is not caused by a defect in the device itself, it is completely difficult to investigate the cause of the accident. In particular, after the neutral wire breakage was repaired and restored, it was almost impossible to prove that the neutral wire was broken, and the equipment itself had to bear the responsibility for the serious accident. For this reason, the cause of the accident could not be identified, and so

Although there were no reports of accidents due to abnormally high voltage, it is thought that the number of accidents mentioned above will gradually increase in the future due to aging of wiring equipment, addition of electrical equipment, etc. In addition, the single-phase three-wire power distribution system shown in Figure 3 is becoming widespread in Japan, but the wiring uses Bl-N and B2-N as normal voltages.
When the wire is disconnected, the voltage between B1 and B2 becomes twice the normal voltage.

This involves the exact same cause of the accident as the Sanwa four-wire system, which is the aging of the equipment.

It can be predicted that abnormally high voltage will occur due to the addition of electrical equipment, etc. Therefore, in response to this situation, a new need has arisen for equipment to be protected by the equipment itself.

The purpose of the present invention is to provide new effects in response to this new need.

[Means to solve the problem]

The above purpose is to place a non-returnable circuit breaker on the electrical circuit closer to the power source than equipment such as compressor motors, blower motors, timer motors, defrost heaters, etc., and to prevent the circuit breaker from operating. In addition to using temperature sensing, the sensing part is an electric motor for the blower.

This can be achieved by attaching a timer to a motor, etc., and detecting an abnormal temperature rise that occurs when an abnormally high voltage is applied, thereby interrupting the circuit.

Generally, in a compression type refrigeration system equipped with an induction motor, there is a large difference in the current flowing into the compressor when the compressor starts up and during normal operation, with the former being several times as large as the latter. Furthermore, even during normal operation, there is a difference in the current value immediately after startup and during stable operation. Furthermore.

During a defrosting operation to remove frost formed on the cooler, and when the operation is stopped, the current flowing into the refrigeration system is not stable and fluctuates greatly. For this reason, it has been extremely difficult to have a self-contained protection device that protects the entire refrigeration system. Therefore, until now it has not been possible to protect the entire refrigeration system from the above-mentioned abnormal high voltage using the protection device built into the refrigeration equipment.1 The present invention provides a protection function for the refrigeration equipment to achieve this objective. It is about providing.

[Effect]

By installing the temperature sensing part of the circuit breaker in the part where the temperature rises the most when abnormally high voltage is applied, such as the blower motor, it is possible to reliably interrupt the circuit when the temperature rises above the set temperature. can. In addition, since it is a non-returnable circuit breaker device, even if the temperature of the device drops due to power cutoff, abnormally high voltage will not be reapplied, making it safe. Furthermore, by appropriately setting the sensed temperature, it is possible to reuse the timer motor and the blower motor. Naturally, serious accidents such as smoke generation and ignition can be prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. still,
Figure 1 shows the electrical circuit of a refrigerator. Reference numeral 4 denotes a compressor electric motor, which is formed together with the compressor in a closed container, and is equipped with an automatic return type overload protection device 5 on the outside. Reference numeral 6 denotes a blower motor that stirs cold air in the refrigerators, and forms a parallel circuit with the compressor motor 4. Reference numeral 1 denotes a defrosting timer device, which includes a timer motor 2, a switching contact 3, and terminals a and b.

8 is a defrosting heater installed at or near the evaporator. 7 is a bimetal thermostat that detects the end of defrosting and shuts off the defrosting circuit. -9 is a temperature fuse, which causes the defrosting heater 8 to continue generating heat even after defrosting has been completed due to failure such as contact welding of the bimetal thermostat 7, and when the temperature rises abnormally, it melts and stops generating heat, causing surrounding parts to melt and smoke. etc. will be prevented. 10 is a thermostat that senses the temperature inside the refrigerator and controls the operation of the compressor motor. Reference numeral 21 denotes a circuit breaker consisting of a temperature fuse, which is closely attached to the coil of the blower motor and installed at the position closest to the power source in the electric circuit 1.

When the switching contact 3 of the defrosting timer device 1 is electrically connected to the terminal a side, temperature dust inside the refrigerator is detected and the electric circuit is electrically connected.
The compressor electric motor 4 repeats operation and interruption by the operation of the shutoff thermostat 10 to perform a cooling operation. Since the blower electric motor 6 constitutes a parallel circuit with the compressor electric motor 4, it operates in synchronization with the compressor electric motor 4. Further, the timer motor is similarly operated in synchronization with the compressor motor 4. When an abnormally high voltage is applied in this operating state, the winding temperature of the compressor motor 4 rises rapidly. The overload protection device 5 senses the winding temperature and cuts off one circuit to stop the operation of the compressor motor 4.

Incidentally, since the overload protection device W15 is a reset type, the circuit returns to conduction as time passes and the temperature decreases. In other words, overload protection! The timer motor 2. is repeatedly energized and cut off until 5 is destroyed. The blower motor 6 does not have an overload protection device, so if an abnormally high voltage is applied, an overcurrent will flow through the coil and the amount of heat generated will be higher than when normal voltage is applied, so the temperature of the coil will be much higher than normal. The coil's insulation deteriorates due to this high temperature when the current is turned on and stabilized.

A layer short occurs, but the temperature fuse 21, which is closely attached to the surface of the coil of the blower motor 6, melts due to the heat generated by the high temperature of the coil. Since the temperature fuse is placed in the position closest to the power source in the electric circuit 1, blowing the temperature fuse can cut off the power to all the devices that make up the refrigerator. Therefore, there is no damage to the blower motor, timer motor, or compressor motor, and it can be determined that the abnormally high voltage is the cause of the melting of the temperature fuse 21.

〔Effect of the invention〕

According to the present invention, when an abnormally high voltage is applied to the refrigerator,
In order to prevent serious accidents such as layer short circuits, smoke emitting ignition, etc., which are sure to occur, the circuit breaker can be activated and the power supply can be cut off at the stage of heat generation temperature rise in the process leading to the accident, so all the equipment that makes up the refrigerator can be protected and accidents can be prevented.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a refrigerator that is an embodiment of the present invention.
2 and 3 are wiring system diagrams of the present invention, and FIG. 4 is an electric circuit diagram of a conventional refrigerator.

Claims (1)

[Claims] 1. In a refrigeration system equipped with an electric circuit that controls the cooling operation of a compressor using a blower, a temperature controller, etc., a circuit breaker is disposed at a position closest to the power supply side of the electric circuit. . A protection circuit for a refrigeration system, characterized in that the entire circuit breaker device or the sensing portion is attached to another device constituting the electric circuit. 2. A protection circuit for a refrigeration system according to claim 1, wherein the circuit breaker is activated by temperature sensing. 3. A protection circuit for a refrigeration system according to claim 1, wherein the circuit interrupting device is of a non-returnable type. 4. A protection circuit for a refrigeration system according to claim 1, wherein the circuit breaker is embedded in, in close contact with, or thermally adjacent to, an electromagnetic induction coil of a rotating device or the like constituting the electric circuit.