JPH11214082A - Ac socket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent in advance the generation of fire, while detecting heat generation due to the tracking phenomenon by embedding a heat detecting element in a surface region between a pair of blade insertion slits, and shielding an external commercial power source in response to the detecting signal. SOLUTION: A heat detecting element 4 such as a thermistor is embedded in a surface region between a pair of blade insertion slits 12 of a casing 11, and a surface of a printed wiring board 6 is provided with a temperature detecting circuit 5. The heat detecting element 4 is connected to the temperature detecting circuit 5, and the temperature detecting circuit 5 is connected to an excitation coil of a circuit breaker 7. When dust 3 is heaped and moisture is absorbed by the dust and the surface current flows between the pair of blades so as to generate the heat, a surface region between the slits 12 is excessively heated, and the heat detecting element 4 indicates a resistance value for resisting the rising temperature. Changed variable of the resistance value is transmitted as the detecting signal to the temperature detecting circuit 5. When the changed variable exceeds a predetermined value, the signal is supplied to the circuit-breaker 7 so as to open the short-circuit between a fixed contact 141 of a blade rest and a fixed contact 151 of an external terminal 15 formed by a short-circuit bar 71.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an AC socket, and more particularly to an AC socket which detects heat generated due to a tracking phenomenon to prevent a fire from occurring.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. FIG.
At the front of the casing 11 of the AC socket 1, A
A pair of blade insertion slits 12 into which the blades 21 of the C plug 2 are inserted are formed. The receiving blade 1 into which the blade 21 is inserted and connected to the blade insertion slit 12.
4 are installed. The blade 21 of the AC plug 2 is inserted into the blade insertion slit 12 and connected to the receiving blade 14. The receiving blade 14 is connected to the external commercial power supply 13 via a power supply line. Here, when the blade 21 of the AC plug 2 is inserted into the blade insertion slit 12 and connected to the receiving blade 14, the blade 21 of the AC plug 2 is connected to the blade 21 and the electric cord 22 connected to the blade 21 of the AC plug 2. Commercial electric power is supplied from the commercial power supply 13 to the electric appliance connected to the end of the electric appliance. Reference numeral 15 denotes an external terminal of the socket.

Incidentally, an AC plug 2 is connected to an AC socket 1.
Is left connected for a long time, dust 3 accumulates in the surface area between the pair of blade insertion slits 12 of the casing 11 depending on the use environment, and moisture is absorbed by the dust 3. . In this case, a surface current flows between the pair of blades 21 via the accumulated and absorbed dust 3. This is called a tracking phenomenon.

[0004]

The area between the pair of insertion slits 12 of the casing 11 is heated by the surface current caused by the tracking phenomenon and generates heat. However, even if a tracking phenomenon occurs, the region between the slits 12 of the casing 11 only generates heat at first, but if the tracking phenomenon persists, this region may cause the region to ignite together with arcing. This needs to be detected at an early stage. However, when the AC socket 1 is used as it is for a long period of time with the AC plug 2 coupled thereto, the surface current of the tracking phenomenon cannot be distinguished from the load current. Therefore, it is difficult to effectively prevent a tracking fire caused by the tracking phenomenon.

SUMMARY OF THE INVENTION The present invention provides an AC socket which solves the above-described problem of detecting heat generated due to a tracking phenomenon and preventing the occurrence of a fire in advance.

[0006]

Means for Solving the Problems Claim 1: Casing 1
The heat detecting element 4 is buried and installed in a surface area between the pair of blade insertion slits 1, and the AC socket 1 that shuts off the external commercial power supply 13 in response to a detection signal of the heat detecting element 4 is configured. Claim 2: In the AC socket described in claim 1, the heat detecting element 4 is buried and installed with its surface exposed at an intermediate point of the surface area between the pair of blade insertion slits 12. Was configured.

[0007] Claim 3: Claims 1 and 2
In the AC socket described in any one of the above, the heat detecting element 4 constitutes one side of the bridge circuit 52 and includes a comparator 51 to which both outputs of the bridge circuit 52 are connected,
A including a circuit breaker 7 responsive to the output of the comparator 51
C socket 1 was constructed. Further, in the AC socket according to any one of claims 1 to 3, the current interrupting portion of the circuit breaker 7 is provided corresponding to both of the power supply lines of the external commercial power supply 13. The AC socket 1 is constructed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the embodiment shown in FIG. In FIG. 1, a blade 2 of an AC plug 2 is provided on a front surface of a casing 11 of the AC socket 1.
A pair of blade insertion slits 12 into which 1 is inserted is formed. The blade insertion slit 12 is provided with a receiving blade 14 into which the blade 21 is inserted and connected. A
The blade 21 of the C plug 2 is inserted into the blade insertion slit 12 and connected to the receiving blade 14. Receiving blade 14
A fixed contact 141 is formed at the tip of. 7 is a circuit breaker. A short-circuit bar 71 is attached and fixed to the tip of the plunger 70 of the circuit breaker 7. Reference numeral 711 denotes a pair of movable contacts attached to the short bar 71. Fifteen
Denotes an external terminal of the AC socket 1, and a fixed contact 151 is formed at an inner end thereof. The short-circuit bar 71 is normally biased outward by a coil spring 72, so that the fixed contact 141 of the receiving blade 14 and the fixed contact 15 of the external terminal 15 are fixed.
1 is short-circuited. Therefore, this AC socket 1
The receiving blade 14 is normally connected to the external commercial power supply 13 via the circuit breaker 7, the external terminal 15, and the conductor. The current breaker, which is a set of the fixed contact 141 and the fixed contact 151 of the circuit breaker 7 and the short-circuit bar 71 for short-circuiting between the fixed contact 141 and the fixed contact 151, is provided on both of the power supply lines of the external commercial power supply 13.

In the above state, when the blade 21 of the AC plug 2 is inserted into the blade insertion slit 12 and connected to the receiving blade 14, the receiving blade 14, the blade 2
Electric power is supplied from the commercial power supply 13 to the electric appliance connected to the distal end of the electric appliance via the electric cord 22 connected to the blade 1 of the AC plug 2 and the AC plug 2. In this embodiment, a thermistor and other heat detecting elements indicated by 4 are buried in the surface area between the pair of blade insertion slits 12 of the casing 11. Reference numeral 6 denotes a printed wiring board, on the surface of which a temperature detecting circuit 5 is attached and fixed. The heat detecting element RX is connected to the temperature detecting circuit 5 via a conducting wire, and the temperature detecting circuit 5 is connected to the exciting coil 73 of the circuit breaker 7 via the printed wiring board 6.

Here, as described in the conventional example, A
If the AC plug 2 is left connected to the C socket 1 for a long period of time, the casing 1
The dust 3 accumulates in the surface area between the pair of blade insertion slits 12 and absorbs moisture, and the dust 3 accumulates and is absorbed by the pair of blades 21 through the accumulated dust 3.
During this time, a surface current flows and the region is heated and generates heat. As described above, the surface area between the pair of blade insertion slits 12 of the casing 11 is heated due to the tracking phenomenon in which the surface current flows between the pair of blades 21 and is buried here when the heat is generated. The heat detecting element RX composed of a thermistor or other heat-sensitive resistor exhibits a resistance value changed in response to the increased temperature. The amount of change in the resistance value of the heat detection element RX is transmitted to the temperature detection circuit 5 as a detection signal, where it is detected.

The temperature detecting circuit 5 supplies to the circuit breaker 7 a detection signal generated when the change in the resistance value of the heat detecting element RX exceeds a predetermined value, assuming that the temperature rise exceeds the predetermined value. The exciting coil 73 of the circuit breaker 7 is set to be excited in response thereto, whereby the coil spring 72 contracts and returns to the original position, and the fixed contact 141 of the receiving blade 14 by the short-circuit bar 71 and the fixed contact of the external terminal 15. Release the short circuit to the H.151. Thus, the connection between AC socket 1 and external commercial power supply 13 is cut off.

Next, the internal configuration of the temperature detection circuit and the circuit breaker will be described with reference to FIG. The temperature detection circuit 5 includes a comparator 51 and a bridge circuit 52 connected to the input terminal. The comparator 51 can be composed of, for example, an operational amplifier. The bridge circuit 52 includes a resistor R
1, the resistor R2, the resistor R3, and the heat detecting element RX have four sides. The resistors R1, R2, and R3 are all fixed resistors. The resistors R1 and R2 are directly connected, and the resistor R3 and the heat detecting element RX are directly connected. These series-connected circuits are connected in parallel to each other to form a bridge circuit 52. Resistance R1
The common connection point of the resistor R2 and the resistor R2 is connected to the non-inverting input terminal of the comparator 51, and the common connection point of the resistor R3 and the heat detecting element RX is connected to the inverting input terminal of the comparator 51. When the surface area between the pair of blade insertion slits 12 of the casing 11 is heated due to the tracking phenomenon and generates heat, the heat detecting element RX including a thermistor or other heat-sensitive resistor changes the resistance changed in response to the increased temperature. Indicates the value,
Due to this change, the bridge circuit 52 loses balance and the comparator 51 generates an output. As a result, the excitation coil 73 of the circuit breaker 7 is driven, and the fixed contact 141 and the fixed contact 15
Shorting bar 71 shorting 1 is tripped via plunger 70.

[0013]

As described above, according to the embodiment of the AC socket of the present invention, when the surface area between the pair of blade insertion slits of the casing is heated due to the tracking phenomenon, and heat is generated, A thermistor or other thermal sensing element, such as a thermal resistor, exhibits a resistance value that changes in response to the increased temperature, causing the bridge circuit to lose balance and the comparator to generate an output. As a result, the exciting coil of the circuit breaker is driven, and the short-circuit bar short-circuiting the fixed contacts between the fixed contacts is tripped via the plunger, so that a further rise in temperature in the area is prevented. Therefore, it is possible to prevent the occurrence of fire due to the tracking phenomenon.

Since a set of a fixed contact and a fixed contact fixed to the circuit breaker and a short-circuit bar for short-circuiting between the fixed contact and the fixed contact is provided for both the power supply line of the external commercial power supply, grounding measures are thorough. That is, depending on the interruption of only one line, the current caused by the tracking phenomenon may be sustained through the earth ground line and a fire may occur.However, by interrupting both the power supply lines from the AC socket, It is also possible to prevent a current caused by the tracking phenomenon from flowing through the grounding wire. This also prevents the risk of fire.

[Brief description of the drawings]

FIG. 1 illustrates an embodiment.

FIG. 2 is a diagram illustrating a temperature detection circuit and a circuit breaker.

FIG. 3 illustrates an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC socket 11 Casing 12 Blade insertion slit 13 External commercial power supply 14 Receiving blade 141 Fixed contact 15 External terminal 151 Fixed contact 2 AC plug 21 Blade 22 Electric cord 3 Dust 4 Heat detection element 5 Temperature detection circuit 51 Comparator 52 Bridge circuit 6 Printed wiring board 7 Circuit breaker 70 Plunger 71 Short-circuit bar 711 Movable contact 72 Coil spring 73 Excitation coil RX Heat detection element

Claims (4)

[Claims] 1. An AC socket, wherein a heat detecting element is buried in a surface area between a pair of blade insertion slits of a casing and an external commercial power supply is shut off in response to a detection signal of the heat detecting element. . 2. The AC socket according to claim 1, wherein the heat detecting element is buried and installed with its surface exposed at an intermediate point of a surface area between the pair of blade insertion slits. socket. 3. The AC socket according to claim 1, wherein the heat detecting element constitutes one side of the bridge circuit, and a comparator to which both outputs of the bridge circuit are connected. A comprising a circuit breaker responsive to an output of the comparator.
C socket. 4. The AC socket according to claim 1, wherein the current interrupting portion of the circuit breaker is provided corresponding to both of the power supply lines of the external commercial power supply. AC characterized by the following
socket.