JP2016177891A - Dc thermosensitive breaker - Google Patents

Abstract

PURPOSE: To provide a breaker which detects an overheat state of a target apparatus, and is capable of breaking a high-voltage direct current and sized smaller than the prior arts.CONSTITUTION: The breaker includes, within a housing container that is formed from an electrical insulation material, a temperature detection part and a contact mechanism which is driven by the temperature detection part and opens contacts. The contact mechanism is structured to simultaneously dissociate a movable contact unit to which a pair of movable contacts 9 are connected in series and integrally. When a thermally-actuated plate 14 that is disposed in the temperature detection part reaches a predetermined temperature, an activation part 13 of a contact mechanism is driven and the contacts are opened. After the contacts are opened by the temperature detection part, the contact mechanism is disabled from being re-connected.EFFECT: The breaker and the temperature detection part are integrated and the breaker is made into a single action type that cannot be operated iteratively, such that the structure of the contact mechanism can be simplified and small-sized. Further, the contact mechanism is structured to simultaneously open the pair of movable contacts that are connected in series, such that a voltage to be applied to one contact can be reduced and an arc during contact opening is unlikely to be continued.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a thermal circuit breaker that is attached to a device that is used in a DC power supply mounted on an automobile and that protects the device by shutting off power to the device in the event of abnormal overheating.

  Various types of thermal switches have been proposed in the past for attachment to automobile accessories. For example, a switch mechanism and a bimetal for driving the switch mechanism are placed in a metal sealed container with good thermal conductivity. There is something stored. (For example, see Patent Document 1)

  In addition, there is a type in which a signal is transmitted to a control circuit at the time of abnormal overheating by attaching this thermal switch to a container of a refrigerant compressor for a car air conditioner, for example. (For example, see Patent Document 2)

  In recent years, with the progress of electrification of automobiles, DC power supplies with higher voltage and higher current than those used in conventional vehicles as accessory devices such as refrigerant compressors and heaters have come to be used. Normally, the energization amount is controlled by a controller, but in the unlikely event the need for a protective device is increasing to cut off the energization.

  For example, when the circuit or heater of the electric compressor mentioned above abnormally overheats for some reason, it is necessary to first cut off the power supply to the target device in order to avoid a danger such as a fire. The above-described conventional thermal switch allows a small current for control to flow, and cannot directly cut off a DC high voltage high current. Therefore, a circuit breaker or a current fuse is used as a device for breaking.

  On the other hand, protection devices such as circuit breakers and current fuses cannot be operated by temperature alone. Therefore, by providing a heat-sensitive switch for short-circuiting the electric circuit on the circuit, when overheating is detected, a device that operates the protection device with a short-circuit current to cut off the power supply to the load has been proposed. (For example, Patent Document 3)

JP 05-101761 A

JP 2002-367495 A

JP 2010-246218 A

  However, when a protective device such as a circuit breaker or a current fuse is activated with a large current that is short-circuited, the short-circuit current flows from the power source through the main circuit, so the fuse provided in the main circuit as well as the circuit of the device where the abnormality occurred The protection device such as Therefore, in an electric vehicle, for example, even when an abnormality occurs in a heater circuit or the like and the energization is interrupted, there is a possibility that all the power is interrupted and suddenly impossible to travel.

  In addition, by using a DC relay that supports high voltage and high current, it becomes possible to operate the relay with a control signal instead of a short-circuit current. There was a problem of becoming complicated. Moreover, since the thing corresponding to a large direct current is enlarged, it is difficult to secure the mounting position in an automobile or the like.

  In addition, unlike an alternating current, a direct current does not generate a zero point of current, so that the arc is difficult to break. Therefore, in order to cut off the large current, there is a problem that the structure of the relay is increased by increasing the distance between the contacts in order to extinguish the arc in a short time. Furthermore, since the surface of the contact surface becomes severely rough due to the arc when the current is interrupted, the life for repeated use becomes very short even if the contact size is increased. Therefore, even if something that has been operated once does not appear to be a problem, a predetermined performance may not be obtained upon reuse. In particular, when contacts with rough surfaces come into contact with each other when reused, the contact resistance becomes high, which may cause welding between the contacts that have become hot due to energization of a large current, causing a problem in protective operation. There is a problem to say. In addition, if the power is turned on again in the energized state, there is a higher possibility that welding will occur due to the arc when the power is turned on. Therefore, there is a demand for a protective device that cannot be used repeatedly after the protective operation so that the desired performance can be obtained in a usable state.

  On the other hand, a fuse that blows out cannot be used repeatedly due to its structure, but it is difficult to cut off a large current because a zero point of current does not occur in DC current. It is necessary to use a current fuse of a size that cannot be said to be small. Furthermore, even if it is a thermal fuse, it is difficult to make it contact with the protection target apparatus which should detect an overheating state, such as a refrigerant compressor. In addition, a thermal fuse that operates by overheating also has the effect of self-heating due to a large current, and it is difficult to detect only overheating of the device to be protected and operate at a desired temperature.

  Therefore, there is a need for a circuit breaker that integrates a circuit breaker capable of interrupting a DC high voltage and large current and a heat sensitive device so that it cannot be reused after operation.

  Therefore, the direct-current thermal circuit breaker of the present invention has a storage container made of an electrically insulating material, and has a temperature detection unit and a contact mechanism that is driven by the temperature detection unit to open the contacts. The contact mechanism is configured to simultaneously dissociate a movable contact unit in which a pair of movable contacts are connected in series and integrally, and the temperature detection unit is made of a metal cover at one end of the storage container separated from the energized portion. The temperature detection unit is configured to drive the contact mechanism starting unit to open the contact between the contacts when the temperature response plate is deformed and reaches a predetermined temperature according to the temperature. The contact mechanism is a temperature detection unit. It is characterized in that after the contacts are opened by the above, reconnection is impossible.

  In addition, the movable contact unit is held in a state where the contact portions are in contact with each other by the engaging portion while being urged by the spring, and the spring is brought into contact with the contact mechanism by removing the engaging portion of the contact mechanism. And the movable contact unit opens the pair of contacts simultaneously.

  The thermally responsive plate can be in direct contact with the metal cover, or can be in direct contact with the device to be protected through an opening provided in the metal cover.

  Furthermore, a metal guide cap that houses the storage container including the temperature detector of the circuit breaker is attached to the circuit breaker installation section of the protection target device, and the storage container is housed in this guide cap so that the bottom of the guide cap and the circuit breaker The heat-sensitive plate makes direct contact.

  According to the present invention, the circuit breaker that can be operated once is not capable of being repeatedly operated, so that the structure of the contact mechanism can be simplified, and a desired performance can be obtained without requiring a special contact. Further, since the contact mechanism has a structure in which a pair of movable contacts connected in series are opened simultaneously, the voltage applied between one contact can be lowered, and the arc at the time of opening the contact becomes difficult to continue. In addition, the circuit breaker and the temperature detector are integrated, and the temperature detector is composed of a thermally responsive plate placed at a position away from the energizing unit, thereby driving the starter at a predetermined temperature and opening the contacts. Therefore, it can be accurately operated at a predetermined temperature without being affected by the amount of energization.

The perspective view which shows the external shape of an example of the DC thermal circuit breaker of this invention Front view of the DC thermal circuit breaker shown in FIG. Sectional drawing which shows the state before operation | movement of the DC thermal circuit breaker of FIG. Sectional drawing which shows the state after operation | movement of the DC thermal circuit breaker of FIG. An embodiment showing a state in which the direct current thermal circuit breaker of the present invention is attached to a device to be protected Another embodiment showing a state in which the direct current thermal circuit breaker of the present invention is attached to a device to be protected

  Next, an embodiment of the present invention will be described with reference to FIGS. The DC thermal circuit breaker 1 (hereinafter referred to as a circuit breaker) according to the present invention has a temperature detection unit and a contact mechanism that is driven by the temperature detection unit and opens a contact between the storage container made of an electrically insulating material. Have. The storage container includes a base 2 and a cylindrical container 3, and a contact space 4 in which a movable contact described later can move is formed in the storage container. A pair of metal terminal plates 6 each having a fixed contact 5 fixed to the inside of the container are fixed to the outer end surface of the base 2 together with an electrically insulating top cover 7, and only the connection portion including the terminal screw 6A is provided. It is in an exposed state.

  The base 2 is provided with a through hole in the center, and a pair of movable contacts 9 (only one is shown in FIGS. 3 and 4 because it overlaps the metal bypass plate 8 to connect the pair of fixed contacts). The movable contact unit 10 is fixed. The movable contact unit 10 is fixed integrally with the moving block 11, and is normally held by a locking portion described later, so that the movable contact unit 10 is moved between the two fixed contacts 5 against the repulsive force of the spring 12 disposed on the base 2. Connected.

  In the cylindrical container 3, an L-shaped latch 13 that is an activation part of the contact mechanism is disposed so as to be rotatable around a shaft 13E that is an intermediate point of the L-shape, and the locking part 13A at one end thereof is moved as described above. The movable block and the movable contact unit 10 are held at predetermined positions by being locked to the end face of the block 11 so as not to move. The other passive end 13B faces outward and is arranged so as to move by the operation of a thermally responsive plate described later. In this embodiment, the latch 13 is provided with a protrusion 13C for preventing the return of the moving block.

  On the outer end surface 3A of the cylindrical container 3 that is sufficiently away from the energized part such as a contact mechanism, a thermally responsive plate is set so that a bimetal or the like is drawn into a shallow dish shape as a temperature detecting portion and is reversed at a predetermined temperature 14 is arranged. In this embodiment, a circular bimetal is used for the thermally responsive plate 14 and is fixed by being covered with a metal cover 15 so as to cover the outer end face 3A. A holding spring 16 made of a thin metal plate is disposed on the inner surface of the heat responsive plate 14 so as to press the heat responsive plate with a force that does not substantially affect the operation of the heat responsive plate 14 toward the metal cover 15. By direct contact, the heat received by the metal cover serving as the heat-sensitive surface can be quickly transmitted to the thermal reaction plate. Furthermore, in this embodiment, the metal cover 15 is provided with an opening 15A at the center thereof, and the center of the thermally responsive plate 14 is exposed. Therefore, the thermally responsive plate 14 can be brought into direct contact with a predetermined portion of the device to be protected. Conversely, when it is not desired to expose the thermally responsive plate, the outer end face may be covered with a metal cover having no opening.

  This circuit breaker 1 is arranged so that the thermally responsive plate 14 can reliably pick up heat with respect to a protection target device such as an automotive refrigerant compressor or a hot water heater. For example, the heat responsive plate is attached to a predetermined portion outside the sealed container of the refrigerant compressor. The thermally responsive plate 14 is not directly energized, and is sufficiently separated from the energized part such as the contact mechanism, so that the temperature of the protection target device can be detected more accurately without being affected by the energization amount. Can do.

  In the state before the operation, the circuit breaker 1 is in a state in which the contacts are closed as shown in FIG. 3, and the pair of terminal plates 6 are electrically connected to each other via the respective contacts and bypass plates.

  Next, the protection operation by this circuit breaker will be described.

  When the surface temperature of the device to be protected rises due to some abnormality and the thermally responsive plate 14 reaches a predetermined operating temperature, the bending direction is reversed. In this embodiment, since the reversing operation is performed with a snap action, the heat responsive plate 14 and the latch 13 are not in contact with each other until the operation, so no force is applied to the latch. During operation, the passive end 13B is instantaneously pushed in by the inverted thermal reaction plate. The latch 13 driven by pushing the passive end 13B is rotated about the shaft 13E, and the locking portion 13A is detached from the moving block 11. Therefore, the moving block 11 pushed by the spring 12 starts moving along the guide groove 3B provided inside the cylindrical container, and the movable contact unit 10 fixed integrally with the moving block is detached from the fixed contact. At this time, arc discharge occurs between the contacts, but it is possible to suppress the continuation of the arc by taking a sufficient distance between the contacts and generating arc extinguishing gas by the heat of the arc on the inner surface of the container. Moreover, since two pairs of contacts are arranged in series, the voltage applied between one contact is divided when the contact is opened, and the arc is difficult to continue.

  The moving block 11 reaches the inner end surface 3C of the cylindrical container and stops. In this embodiment, as described above, the protrusion 13C for preventing the return of the moving block is provided on the latch 13. The moving block 11 gets over from the slope side where the projection 13C has an obtuse angle while bending the tongue 13D at the tip of the latch 13 during movement. If the moving block 11 abuts against the inner end surface 3C of the cylindrical container while maintaining its momentum, it may bounce back and reconnect the contact, but at this time, the slope of the protrusion 13C has an acute angle. Since it abuts, it cannot move any further. In this way, reconnection between the contacts due to the rebound of the moving block 11 is prevented, and after the circuit breaker has been operated once, it cannot be restored manually and is not reconnected.

  Therefore, it is possible to prevent reconnection of the contact whose surface has been roughened by a strong arc during the interruption operation. This ensures that only the circuit breaker that has not been operated is used, and it is possible to prevent a situation such as a deterioration in the protection performance due to the reuse or malfunction due to welding of the contacts.

  In addition, since it is not necessary to provide a return lever or the like, the entire apparatus can be reduced in size. Furthermore, since no reconnection is required, the contact material does not necessarily require a special metal or the like for DC switching or arc countermeasures, so that manufacturing becomes easier. Moreover, since the heat-sensitive plate and metal cover which are heat sensitive parts are sufficiently away from the conductive part, the heat sensitive parts can be brought into direct contact with the device to be protected.

  In the embodiment, the latch is provided with a protrusion for detent of the moving block and the movable contact unit. However, a similar protrusion may be provided in the storage container, or the moving block is prevented from being rebounded instead of the detent. A buffer portion may be provided. Further, by inserting a shielding plate between the movable contact and the fixed contact when opened, it is possible to prevent the movable contact unit from rebounding and to quickly interrupt the arc generated between the contacts.

  Next, attachment of this circuit breaker to the protection target device will be described with reference to FIG. The protection target device 21 is a refrigerant compressor for an air conditioner, and an electric motor 21B and a compressor (not shown) are arranged inside the sealed container 21A, and the inside of the sealed container is a refrigerant passage. The circuit breaker 1 is attached so that an end surface as a temperature detecting portion thereof is in contact with a non-penetrating attachment hole 21 </ b> C provided outside the sealed container. As described above, the circuit breaker 1 is provided with the opening on the end surface of the cover, so that the thermally responsive plate can be brought into contact with the bottom surface of the mounting hole 21C of the hermetic container. In this case, the thermal response plate, which is a temperature detection element, can directly respond to the thinned portion of the sealed container, so that it can respond quickly to temperature changes. However, if airtightness in the switch is required, the opening It is also possible to make a metal cover without any.

  In this embodiment, the circuit breaker 1 is fixed by a leaf spring 22 having one end fixed on a sealed container. The bottom of the mounting hole 21C is made thinner than the other part of the container so that the internal refrigerant temperature can be quickly transmitted to the circuit breaker 1. In the embodiment, a temperature sensor 23 such as a thermistor is disposed in the mounting hole 21C together with the circuit breaker 1, so that in normal operation, the operation is controlled based on the temperature state of the device to be protected, and in the case of abnormal overheating, the circuit breaker is operated. 1 can reliably cut off the energization.

  Next, another mounting example will be described with reference to FIG. The protection target device 41 in FIG. 6 is a liquid circulation heater used in an electric vehicle or the like, and a liquid serving as a heat medium enclosed in a sealed circulation path is heated by the electric heater 41B. The air flowing through the room is heated by a heat exchanger that passes through.

  Normally, the heater output is controlled so that the liquid serving as the heat medium becomes a predetermined temperature or less. However, if the liquid is reduced or removed for some reason, the heater becomes hot and ignites. there is a possibility. Especially when used in automobiles, the heater has a high heat generation capability because it is required to quickly warm the room in winter. Therefore, detection and control may not be able to sufficiently catch up with a sudden overheating in an air-opened state in the case of attachment through a closed container as shown in FIG. Therefore, in this embodiment, the sealed container 41A is provided with a through hole 41C, and a metal guide cap 42 provided with a cylindrical storage portion for mounting a circuit breaker is welded to a flange provided on the opening side thereof. It is fixed in an airtight manner. The guide cap 42 is formed into a cylindrical shape that can accommodate the circuit breaker 1 by pressing a metal plate or the like, and can be made thinner than directly processing the sealed container 41A. Further, in the embodiment, the outer peripheral surface 42A of the guide cap storage portion is arranged so as not to directly contact the inner peripheral surface of the through hole 41C of the sealed container.

  The circuit breaker 31 is provided with a mounting portion 31A extending outward from the base. The mounting portion 31A is fixed to the sealed container 41A with a bolt 31B. At this time, the breaker 31 is housed in the housing portion of the guide cap 42 so that the end surface of the breaker is in contact with the bottom surface of the guide cap.

  Since the guide cap 42 is made of a thin metal plate, the temperature of the heat medium can be quickly transferred to the heat actuating body on the end face of the circuit breaker. On the other hand, by providing a gap between the outer peripheral surface 42A of the storage portion of the guide cap 42 and the inner peripheral surface of the sealed container through hole 41C, the heat of the end surface of the guide cap is not easily transmitted to the sealed container, and the thermal response of the circuit breaker Get better. Further, by making the guide cap face or contact the vicinity of the electric heater 42B, the overheated state of the heater can be quickly transmitted by the temperature detection unit of the circuit breaker. Therefore, it is possible to obtain an appropriate protection operation against a rapid temperature rise caused by an empty state. As an optimum embodiment, by setting the operating temperature of the thermoactuator to a temperature exceeding the boiling point of the liquid serving as the heat medium, accidents such as ignition from the air circulation state of the liquid circulation heater can be prevented.

  In this embodiment, it goes without saying that a temperature sensor for control can be arranged in the guide cap as in the above-described example.

1: DC thermal breaker 2: Base (storage container)
3: Cylindrical container (storage container)
4: Contact space 5: Fixed contact 6: Terminal plate 7: Top cover 8: Bypass plate 9: Movable contact 10: Movable contact unit 11: Moving block 12: Spring 13: Latch 13A: Locking part 13B: Passive end 13C: Protrusion 14: Thermally responsive plate 15: Metal cover 15A: Opening 16: Holding spring

Claims (5)

Have a storage container made of electrically insulating material,
In the storage container, a temperature detection unit and a contact mechanism that is driven by the temperature detection unit to open the contacts are provided.
This contact mechanism is configured to simultaneously dissociate a movable contact unit in which a pair of movable contacts are connected in series and integrally,
The temperature detector is fixed to one end of the storage container away from the energized part by a metal cover,
This temperature detection part is to open the gap between the contacts by driving the starting part of the contact mechanism when the thermal reaction plate is deformed according to the temperature and reaches a predetermined temperature.
A direct current thermal circuit breaker characterized in that the contact mechanism is made non-reconnectable after the contacts are opened by the temperature detector. In the contact mechanism, the movable contact unit is held by a locking part provided on the starting part so as to be in a state where the contacts are in contact with each other against urging by a spring,
The temperature detection unit drives the starting unit and removes the locking unit from the contact mechanism, whereby the spring drives the contact mechanism and the movable contact unit opens the pair of contacts simultaneously. A thermal circuit breaker for direct current described. The direct current thermal circuit breaker according to claim 1 or 2, wherein the thermally responsive plate is in direct contact with a metal cover. The thermal cover for DC according to any one of claims 1 to 3, wherein the metal cover has an opening, and the thermally responsive plate can directly contact the device to be protected through the opening. A metal guide cap that holds the storage container including the temperature detector of the circuit breaker is attached to the circuit breaker installation part of the protection target device.
5. The DC thermal circuit breaker according to claim 4, wherein the receiving container is placed in the guide cap so that the bottom surface of the guide cap and the thermally responsive plate of the circuit breaker are in direct contact with each other.

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