JP2013257963A - Safety device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety device capable of blocking a DC current with stability and with certainty.SOLUTION: A safety device 1 comprises: a temperature fuse 432 arranged between a DC power supply 41 and a resistor 22; and a capacitor 437 and a current fuse 436 connected in parallel to the temperature fuse 432. When the temperature fuse 432 is fused to block a current, a current flowing in the resistor 22 is commutated to the capacitor 437 and the current fuse 436, and then, the current fuse 436 is fused.

Description

  The present invention relates to a safety device that interrupts a direct current when an abnormality occurs.

  Patent Document 1 discloses a circuit breaker device in which a first switch is provided in a main circuit connected in series to a DC power source, and a capacitor and a second switch are provided in a parallel circuit connected in parallel to the main circuit.

  In this circuit breaker, the first switch is opened before the second switch so that the arc current is absorbed by the capacitor, and the second switch is opened during this time to cut off the direct current.

JP 2004-113131 A

  However, in the above prior art, since the first and second switches are opened by sliding the contacts, there may be a stick-slip phenomenon. When this stick-slip phenomenon occurs in the second switch, There is a problem that it is difficult to stably and surely shut off.

  The present invention has been made in view of such a technical problem, and an object of the present invention is to provide a safety device capable of stably and surely interrupting a direct current.

  According to an aspect of the present invention, there is provided a safety device that cuts off a direct current flowing from a DC power supply to a load, a cutoff device disposed between the DC power supply and the load, and a parallel to the cutoff device A capacitor and a current fuse to be connected, and when the interrupting device cuts off the current, the current flowing in the load is commutated to the capacitor and the current fuse, and the current fuse is blown. Safety devices are provided.

  According to the above aspect, since the direct current is interrupted by blowing the current fuse while the capacitor is being charged, the stick-slip phenomenon does not occur, and the direct current can be stably and reliably interrupted. it can.

1 is an overall configuration diagram of a heater device including a safety device according to a first embodiment of the present invention. It is a figure for demonstrating the operation | movement at the time of electric current interruption. It is a figure for demonstrating the operation | movement at the time of electric current interruption. It is a figure for demonstrating the operation | movement at the time of electric current interruption. It is a circuit diagram of the safety device concerning a 2nd embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is an overall configuration diagram of a heater device 1 including a safety device 43 according to the first embodiment of the present invention. The heater device 1 is mounted on an electric vehicle and used for heating the passenger compartment. The heater device 1 includes a heater 2, a heater circuit 3 that circulates hot water, and a power supply circuit 4 that drives the heater 2. Each configuration will be described below.

  The heater 2 is an electric heater (preferably a sheathed heater from the viewpoint of cost) such as a sheathed heater or a PTC heater. The heater 2 includes a warm water tank 21 for storing warm water and a resistor 22 disposed in the warm water tank 21, and heats the warm water in the warm water tank 21 with heat generated when the resistor 22 is energized.

  The heater circuit 3 is a circuit in which the heater 2, the heater core 31, the gas-liquid separator 32, and the electric water pump 33 are connected by a hot water passage 34.

  The heater core 31 is connected to the downstream side of the heater 2 and is disposed in the duct 5 of the air conditioner. When the hot water heated by the heater 2 is passed through the heater core 31, heat exchange is performed between the air flowing in the duct 5 and the hot water, thereby heating the air. The heated air is sent to the passenger compartment through the duct 5, thereby heating the passenger compartment. The air mix door 6 provided at the inlet of the heater core 31 is a door for adjusting the amount of air flowing through the heater core 31.

  The gas-liquid separator 32 is connected to the downstream side of the heater core 31, separates hot water into gas and liquid, and sends only liquid-phase hot water to the electric water pump 33. The reason why gas-liquid separation is performed is that the efficiency of the electric water pump 33 is reduced when water vapor or air enters the electric water pump 33.

  The electric water pump 33 is connected to the downstream side of the gas-liquid separator 32, is driven when the air conditioning apparatus is (heating), and pumps hot water having a lowered temperature to the heater 2.

  The power supply circuit 4 includes a DC power supply 41, a load output limiter (IGBT) 42, a safety device 43, and a control device 44.

  The DC power supply 41 is a high-power battery having an output voltage of 350V.

  The safety device 43 is a device that allows energization of the heater 2 in a normal state but forcibly cuts off energization of the heater 2 in an abnormal state. The abnormal time is, for example, a case where the temperature of the hot water in the hot water tank 21 is higher than the upper limit temperature.

  The safety device 43 includes a main circuit 431 connected in series to the DC power supply 41 via the load output limiter 42, and a parallel path 435 connected in parallel to the main circuit 431.

  In the main circuit 431, the temperature fuse 432 and the resistor 22 of the heater 2 are provided in series. The thermal fuse 432 is attached to the upper surface of the hot water tank 21 and is blown when the temperature of the thermal fuse 432 becomes higher than the rated temperature due to the heat received from the hot water in the hot water tank 21.

  In the parallel circuit 435, a current fuse 436 and a capacitor 437 are provided in series. That is, the current fuse 436 and the capacitor 437 are connected in parallel to the temperature fuse 432 and the resistor 22. The current fuse 436 is a fuse that blows when a current exceeding the rating flows. Although not particularly illustrated, the current fuse 436 and the capacitor 437 may be connected to the resistor 22 in series. In this case, the current fuse 436 and the capacitor 437 are connected in parallel to the temperature fuse 432, and the resistor 22 is connected in series to the temperature fuse 432, the current fuse 436 and the capacitor 437.

  The capacity of the capacitor 437 is determined by the fusing time of the thermal fuse 432 (the time required from when the thermal fuse 432 cuts off the current until it is completely blown out), and is required to complete the charging of the capacitor 437 by the DC power supply 41. The time (hereinafter, “charge completion time”) is set to be longer than the fusing time of the thermal fuse 432. Further, the fusing characteristics of the current fuse 436 are set so that the time from when the current fuse 436 is energized until the fusing is shorter than the charging completion time of the capacitor 437.

  The control device 44 includes a controller and an amplifier, acquires the temperature of the hot water from the temperature sensor 45 attached to the hot water tank 21, and the vehicle air conditioner is in the heating operation and the temperature of the hot water is lower than the target temperature. In this case, the load power limiter 42 connects the DC power supply 41 to the main circuit 431 to drive the heater 2. On the contrary, when the temperature of the hot water is higher than the target temperature even when the vehicle air conditioner is not heating or the vehicle air conditioner is in the heating operation, the load power limiter 42 causes the DC power supply 41 to be turned on. Disconnecting from the main circuit 431, the driving of the heater 2 is stopped.

  The heater device 1 is configured as described above, and the heater 2 is driven by the DC power supply 41 during the heating operation of the vehicle air conditioner. When some abnormality occurs in the heater device 1 and the temperature of the hot water in the hot water tank 21 becomes higher than the upper limit temperature, the safety device 43 is activated, the direct current is cut off, and the heater device 1 is forced. Stop.

  2A to 2C are diagrams for explaining the operation of the safety device 43. FIG.

  In a normal state, the resistance of the main circuit 431 is extremely small compared to the resistance of the parallel circuit 435, so that the current from the DC power supply 41 flows to the main circuit 431 side and the parallel circuit 435 side Not flowing.

  When some abnormality occurs in the heater device 1 and the temperature of the hot water in the hot water tank 21 becomes higher than the upper limit temperature and the temperature fuse 432 becomes higher than the rated temperature, the temperature fuse 432 is first blown. As a result, the resistance of the main circuit 431 becomes infinite, and the current is commutated to the parallel circuit 435 side, that is, the capacitor 437 and the current fuse 436, as shown in FIG. 2B. While the capacitor 437 is being charged, no arc current flows between the fused contacts of the thermal fuse 432 on the main circuit 431 side, and the thermal fuse 432 is completely blown out in a time shorter than the charging completion time of the capacitor 437. Therefore, the thermal fuse 432 is surely blown.

  Then, due to the relationship between the capacity of the capacitor 437 and the blowing characteristics of the current fuse 436, the current fuse 436 is blown before the charging of the capacitor 437 is completed (FIG. 2C). As a result, the current flowing through the main circuit 431 and the parallel circuit 435 is interrupted, and the heater device 1 is forcibly stopped.

  Since the contact distance of the current fuse 436 is longer than that of the temperature fuse 432 and silica gel or the like is sealed in the fuse, the occurrence of arc discharge when the current fuse 436 is blown is suppressed, and the current fuse 436 is blown. Is also done reliably.

  As described above, according to the present embodiment, since the direct current is interrupted by blowing the current fuse 436 while the capacitor 437 is charged, the stick-slip phenomenon does not occur, and the direct current is stabilized. Can be reliably shut off.

  Further, since the fusing of the temperature fuse 432 and the current fuse 436 occurs spontaneously and automatically without the control device 44 being involved, an external control device is unnecessary.

  Further, the configuration of the safety device 43 is simple, and a high degree of layout freedom can be realized and the cost of the device can be reduced.

Second Embodiment
FIG. 2 is a circuit diagram of the safety device 43 according to the second embodiment.

  The safety device 43 according to the second embodiment includes a bimetal switch 433 in the main circuit instead of the thermal fuse 432.

  The bimetal switch 433 includes a bimetal 4331 installed on the upper surface of the hot water tank 21 and a contact 4332 that opens and closes in response to deformation of the bimetal 4331. The critical temperature of the bimetal 4331 is set so that the bimetal 4331 is deformed when the temperature of the hot water in the hot water tank 21 becomes higher than the upper limit temperature.

  The capacitance of the capacitor 437 is set according to the opening time of the bimetal switch 433 (the time required from when the current is cut off until it is fully opened), and the charging completion time of the capacitor 437 is opened. It is set to be longer than the extreme time.

  As a result, the current flows to the main circuit 431 side in the normal state, but when the temperature of the hot water in the hot water tank 21 becomes higher than the upper limit temperature, the bimetal switch 433 is opened, and the current is commutated to the parallel circuit 435 side. While 437 is being charged, no arc current flows between the contacts of the bimetal switch 433 on the main circuit 431 side. Then, the current fuse 436 is blown until the charging of the capacitor 437 is completed, the current flowing through the main circuit 431 and the parallel circuit 435 is cut off, and the heater device 1 is forcibly stopped.

  Also according to the second embodiment, as in the first embodiment, the stick-slip phenomenon does not occur, and the direct current can be stably and reliably interrupted. The point that an external control device is unnecessary and the point that the device configuration is simple are the same as in the first embodiment.

  As mentioned above, although embodiment of this invention was described, the said embodiment showed only a part of application example of this invention, and is not the meaning which limits the technical scope of this invention concretely of the said embodiment. .

  For example, in the above embodiment, the thermal fuse 432 or the bimetal 4331 is installed on the upper surface of the hot water tank 21, but these are installed near the resistor 22 in the hot water tank 21 and directly from the resistor 22 or a heat transfer bracket or the like. Therefore, the safety device 43 may be activated and cut off the direct current when the temperature of the resistor 22 itself becomes higher than the upper limit temperature.

  Further, instead of the temperature fuse 432 or the bimetal switch 433 provided in the main circuit 431, a float switch that opens when the water level of the hot water tank 21 becomes lower than a predetermined level may be provided.

  Moreover, although this embodiment demonstrated the case where the heater 2 was used for heating operation, the scene where the heater 2 is used is not specifically limited. For example, the heater 2 may be driven together with an evaporator for cooling during a temperature control operation in an intermediate temperature range (10 to 20 °).

41 DC power supply 22 Resistance (load)
43 Safety device 432 Thermal fuse (breaking device)
436 Current fuse 437 Capacitor 433 Bimetal switch (breaker)

Claims (8)

A safety device that cuts off direct current flowing from a DC power supply to a load,
A shut-off device disposed between the DC power source and the load;
A capacitor and a current fuse connected in parallel to the breaker;
When the interruption device cuts off the current, the current flowing through the load is commutated to the capacitor and the current fuse, and the current fuse is blown.
A safety device characterized by that. The safety device according to claim 1,
The time from the start of energization to the current fuse until the current fuse blows is shorter than the time until the capacitor is completely charged by the DC power supply,
A safety device characterized by that. The safety device according to claim 1 or 2,
The shut-off device and the load are connected in series,
The capacitor and the current fuse are connected in parallel to the breaker and the load;
A safety device characterized by that. The safety device according to claim 1 or 2,
The shut-off device and the load are connected in series,
The capacitor and the current fuse are connected in series to the load;
A safety device characterized by that. The safety device according to any one of claims 1 to 4,
The interrupting device is a thermal fuse that blows by receiving heat from the load directly or indirectly,
A safety device characterized by that. The safety device according to any one of claims 1 to 4,
The shut-off device is a bimetallic switch that opens directly by receiving heat from the load directly or indirectly,
A safety device characterized by that. The safety device according to claim 6, wherein the bimetal switch includes a bimetal that deforms by receiving heat from the load directly or indirectly, and a contact that opens by receiving the deformation of the bimetal.
A safety device characterized by that. The safety device according to any one of claims 1 to 4,
The load is a resistance of a heater that heats hot water in the hot water tank,
The shut-off device is a switch that opens when the amount of hot water in the hot water tank drops to a lower limit value,
A safety device characterized by that.

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