JP2008021622A - Plug and power cord with plug - Google Patents

Abstract

An object of the present invention is to provide an insertion plug that prevents abnormal heat generation at an outlet and can be used many times.
The power supply is electrically connected to at least one of a plurality of plug blades. When a predetermined temperature is reached, the power supply to the electrically connected load is cut off, and the cut-off power supply is manually restored. And a lower case 18b for housing the thermostat 17 and a poor contact between the plug blade 11 and a receiving blade (not shown) of the outlet, and an increase in contact resistance. If heat is generated in that part, it is transmitted to the main body of the plug 10, and the built-in thermostat 17 detects the heat and shuts off the power supply to the load, thus reliably preventing abnormal heat generation and fire caused thereby. can do. Further, once the thermostat 17 is operated, it can be manually returned and used again, so that useless repairs and replacement of parts are unnecessary, and it is easy to use.
[Selection] Figure 2

Description

  The present invention relates to an insertion plug attached to a power cord that is connected to an electrical device in a general household and supplies power, and a power cord with an insertion plug.

The plug that is attached to the power cord that supplies power to the electrical equipment is used by plugging it into the outlet of the room, or as the plug is frequently inserted into and removed from the outlet. The contact resistance with the plug blade on the plug side gradually increases. In the case of electrical equipment with a relatively small electrical load, such as radio and audio equipment, the current that flows is small, so this is not a problem. However, heater equipment, heat equipment such as rice cookers, etc., sometimes have a large current exceeding 10A. Therefore, when the contact resistance between the receptacle on the outlet side and the plug blade on the plug side increases, a large amount of Joule heat is generated in that part, and in the worst case, the heat is formed by the resin. The main body of the plug was melted and ignited, which was one of the causes of fire.
In order to solve this, a thermal fuse is connected between one plug blade and a power cord conductor connected to the plug blade, and when the temperature fuse reaches a predetermined temperature, the power cord is connected to the power cord. There is an insertion plug which cuts off energization (for example, refer to patent documents 1 and 2).
FIG. 8 is a partially cutaway plan view of a conventional plug described in Patent Document 1.
In the figure, a conventional plug 1 is connected between a pair of plug blades 2, one conductor 4 of a power cord 3 and one plug blade 2, and melts when reaching a predetermined temperature. A temperature fuse 5 that cuts off current from the blade 2 to the conductor 4, and a plug body with the pair of blades 2, the conductor 4, and the temperature fuse 5 inserted in a mold (not shown). 6 is injection-molded using a plastic material such as vinyl chloride resin to obtain an integrally formed plug 1. Reference numeral 7 denotes a crimp terminal for connecting the core wire 4 a of the conductor 4 and the plug blade 2.
The fusing temperature of the thermal fuse 5 is set to be higher than the molding temperature of the plug body 6 and lower than the ignition temperature of the plug body 6.
The operation and action of the conventional insertion plug configured as described above are as follows.
When the electrical equipment (not shown) to which the power cord 3 is connected is used, if it becomes abnormally high due to poor contact or increased contact resistance between the plug blade 2 and the receptacle blade of the outlet (not shown) Accordingly, when the temperature inside the plug body 6 rises and reaches the set temperature of the thermal fuse 5, the thermal fuse 5 is immediately blown by detecting this, and is connected to one conductor 4 of the power cord 3. Since the energization is cut off, the temperature in the plug main body 6 does not exceed the set temperature of the thermal fuse 5, and it is possible to reliably prevent the occurrence of a fire or the like.
The fusing of the thermal fuse 5 occurs when the temperature in the plug body 6 becomes high. Therefore, the plug body 6 itself is also deformed by high temperature heating, or the plastic layer around the plug blade 2 changes to black. Therefore, the user of the electric device can easily determine that the plug 1 has already been in a state where it cannot be used safely by visually observing the plug body 6.
JP-A-8-37060 JP-A-8-250224

However, in such a configuration of the conventional plug 1, once the temperature fuse 5 is blown, the plug body 6 is also thermally deformed and cannot be used again. In the case of being integrally molded, both must be replaced, and the repair cost is high, and the cause of the thermal deformation of the plug body 6 or the melting of the internal temperature fuse 5 is old due to the large contact resistance. In spite of being on the outlet side having the receiving blade, there is a problem that it is misunderstood that the power cord 3 is on the electric device side to which the power cord 3 is connected, and the device manufacturer is chased by the correspondence.
In order to prevent thermal deformation of the plug body 6, the plug body 6 may be formed of a material having excellent heat resistance. However, this increases the manufacturing cost of the plug 1, and the thermal fuse 5. Even if it operates, that is, it blows, it cannot be determined from the outside, so it is misunderstood that the equipment has failed, and wasteful inspection and repair are performed.
Furthermore, the plug 1 can be assembled so that the thermal fuse 5 can be replaced. However, unlike a general current fuse that can be easily replaced, the thermal fuse 5 senses temperature and operates. For this reason, depending on the mounting method, the temperature cannot be detected properly, and there is a risk that it will not operate at an important point. Therefore, it is not preferable from the viewpoint of safety for a general user to replace the thermal fuse 5. That is, even if the plug 1 is assembled and the thermal fuse 5 can be replaced, it is necessary to repair by the expert after all, so there is a problem that the repair cost is increased.
The present invention solves the above-mentioned conventional problems, and prevents abnormal heat generation at the outlet portion to surely prevent a fire, and even if it generates heat at the outlet portion and operates, it can be easily restored many times. An object of the present invention is to provide an easy-to-use plug and a power cord with a plug.

In order to solve the conventional problem, the plug of the present invention is electrically connected to a plurality of plug blades and at least one of the plug blades, and is electrically connected when a predetermined temperature is reached. A thermostat that cuts off the power supply to the load and manually restores the power supply that was once cut off, and the load side of the plug blade and a case that houses the thermostat. If the heat is generated in that part due to poor contact with the receiving blade or increased contact resistance, it is transmitted to the plug body, and the built-in thermostat detects the heat and shuts off the power to the load. Therefore, abnormal heat generation and fire due to it can be surely prevented. In addition, once the thermostat is activated, it can be manually restored, so after replacing the outlet that caused the heat, the plug can be used again, making it easy to use. is there. Further, if the return button for manually returning the thermostat protrudes during operation (when power is cut off), it can be easily determined from the outside that the thermostat has been operated, and the usability can be further improved.
Moreover, the power cord with an insertion plug of the present invention is provided with the insertion plug according to any one of claims 1 to 4 at one end of the power cord. Prevents poor contact with the blade and fires caused by abnormal heat generation due to increased contact resistance, and facilitates maintenance that does not require repair or replacement of the plug even if the thermostat operates. A power cord with a plug can be provided.

  The plug and the power cord with the plug of the present invention prevent abnormal heat generation at the outlet and reliably prevent a fire, and even when the thermostat operates and easily recovers from it It is easy to use and can be used many times.

The first invention is electrically connected to the plurality of plug blades and at least one of the plug blades. When a predetermined temperature is reached, the power supply to the electrically connected load is cut off and once cut off. With a thermostat that manually restores the energization, and the load side of the plug blade and a case that houses the thermostat, poor contact between the plug blade of the plug and the receptacle of the outlet, contact When heat is generated in that part as resistance increases, it is transmitted to the plug body, and the built-in thermostat detects the heat and shuts off the load, thus preventing abnormal heat generation and fire due to it. can do. In addition, once the thermostat is activated, it can be manually restored, so after replacing the outlet that caused the heat, the plug can be used again, making it easy to use. is there. Further, if the return button for manually returning the thermostat protrudes during operation (when power is cut off), it can be easily determined from the outside that the thermostat has been operated, and the usability can be further improved.
The second invention is particularly the thermostat of the first invention, wherein the temperature of the conductor built in the case and supplying power to the load is detected. When heat is generated at the outlet, the heat is transferred to the case. The temperature of the internal temperature rises so that the thermostat can detect the heat.In addition, by detecting the temperature of the conductor with the thermostat, the heat generated between the plug blade and the receptacle of the outlet is heated. Since it is quickly transmitted to the thermostat through the plug blade and conductor with excellent conductivity, the temperature can be detected earlier and the current can be cut off more safely.
In the third invention, in particular, the thermostat of the first invention detects the temperature of the inner wall of the case blade side of the case, and the wall of the case blade side of the case always faces and contacts the outlet. Therefore, when heat is generated at the outlet, the heat is transferred to the wall on the case blade side of the case, but the heat is transferred directly to the thermostat, so that heat detection is performed quickly and accurately, and the power supply is safely cut off. I can do it.
In the fourth aspect of the invention, in particular, the insertion plug of any one of the first to third aspects is provided with a receiving blade that receives a plug blade of an external insertion plug, and the insertion plug functions as a branch outlet. Since it has a built-in thermostat that prevents abnormal heat generation at the outlet, you can connect plugs that do not have a built-in safety device such as a conventional thermal fuse. Electrical equipment can also be used with confidence.
5th invention provides the insertion plug of any one of Claims 1-4 in the end of a power cord, and contact between the plug blade of an insertion plug, and the receptacle blade on the outlet side A power cord with a plug that is easy to maintain and that does not require repair or replacement of the plug even if the thermostat operates, as well as to prevent fires caused by defects or abnormal heat generation due to increased contact resistance. Can be provided.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.
(Embodiment 1)
FIG. 1 is a perspective view of a power cord with an insertion plug to which an insertion plug according to the first embodiment of the present invention is connected, and FIG. 2A is a plan view showing an internal configuration of the insertion plug. b) is a side view of the plug blade of the plug, FIG. 3C is a front view of the plug blade, and FIG. 3 is a partial enlarged cross-sectional view of the thermostat mounting portion of the plug.
1 to 3, the plug 10 according to the present embodiment is connected to a pair of plug blades 11 inserted into an outlet (not shown) provided on a wall or the like and a load such as an electric device (not shown). A pair of terminal portions 14 to which a conductor 13 of a power cord 12 that supplies power is screwed, a conductor A15 that electrically connects one terminal portion 14 and one plug blade 11, and the other through a conductor B16 The manual return type thermostat 17 is electrically connected between the terminal portion 14 of the plug blade 11 and the other plug blade 11. The load side (power cord 12 side) of the plug blade 11, the terminal portion 14, and the conductor A 15 are provided. The conductor B16 and the thermostat 17 are built in a case 18 composed of an upper case 18a and a lower case 18b.
As shown in FIGS. 2 and 3, the thermostat 17 has a pair of terminal 1 plates 7a to which the conductor B16 is connected, a fixed terminal (not shown) connected to one of the terminal plates 17a, and the other of the terminal plates 17a. A thermostat case 17b for storing a connected movable terminal (not shown) and a disc-shaped bimetal 17c made of a metal material so that heat can be easily detected are stored and caulked to the outer periphery of the thermostat case 17b. 17d and a return button 17e.
In the present embodiment, the upper case 18a is provided with an opening 18c through which the tip of the return button 17e passes.
Usually, the bimetal 17c built in the thermostat 17 is convexly curved downward, and the fixed terminal and the movable terminal are in contact (conduction). When the ambient temperature rises and the temperature of the cap 17d rises and the temperature of the inside bimetal 17c reaches a predetermined temperature, the bimetal 17c reverses upward and the movable terminal is fixed in conjunction with the operation. The switch is separated from the terminal to cut off energization, and the return button 17e projects upward from the opening 18c. Then, when the return button 17e is pushed downward after the temperature of the bimetal 17c is lowered, the bimetal 17c reverses convexly downward, the fixed terminal and the movable terminal come into contact again, and are electrically connected.
In the present embodiment, as shown in FIG. 3, a part of each of the conductor A15 and the conductor B16 is sandwiched between the cap 17d and the lower case 18b of the thermostat 17, and the conductor A15 and the conductor B16 are held by the cap 17d. The temperature can be detected directly.
The operation and action of the plug 10 in the present embodiment configured as described above are as follows.
When the plug blade 2 of the plug 10 is inserted into an outlet and power is supplied to the electrical equipment via the power cord 12, the gap between the plug blade 11 and the receptacle on the outlet side (not shown) is If contact failure occurs or the contact resistance between the plug blade 11 and the receptacle on the outlet side is large, the portion generates heat due to Joule heat. Part of the generated heat warms the entire outlet, which is transmitted to the case 18 of the plug 10 inserted into the outlet, and the ambient temperature in the case 18 rises. Further, part of the heat is transmitted to the conductor A15 and the conductor B16 through the plug blade 11 having good heat conductivity, and similarly, the ambient temperature in the case 18 is raised and detected by the cap 17d.
As described above, the temperature of the cap 17d rises due to the heat from the conductor A15 and the conductor B16 in contact with the cap 17d of the thermostat 17 in addition to the increase in the ambient temperature in the case 19, and the temperature reaches a predetermined temperature (operating temperature). When the temperature reaches, the thermostat 17 operates to cut off the power supply to the conductor B16, that is, the power supply to the electrical equipment is cut off, the current stops flowing, and the heat generation between the plug blade 11 and the receptacle on the outlet side stops. And can prevent fires from occurring.
Usually, since the outlet and the outlet cover (not shown) are made of resin, the heat generated at the outlet is hardly transmitted to the case 18. Therefore, if the operating temperature of the thermostat 17 is set high, the outlet and the outlet cover may melt before the thermostat 17 operates (cuts off power). On the other hand, if the operating temperature of the thermostat 17 is set low, when the load current of the electrical equipment used temporarily increases in addition to the high atmospheric temperature in summer, the temperature at the outlet rises and the thermostat 17 malfunctions. Sometimes. Therefore, as a result of examining various usage conditions, it was found that it is desirable to set the operating temperature of the thermostat 17 to 70 to 90 ° C. In the present embodiment, the operating temperature of the thermostat 17 is set to 80 ° C.
As described above, according to the present embodiment, when a contact failure between the plug blade 11 of the plug-in plug 10 and the receptacle of the outlet or an increase in contact resistance occurs, the load is energized. Therefore, abnormal heat generation and fire due to it can be surely prevented. Also, even if the thermostat 17 once operates, after the temperature has dropped, it can be manually restored by pressing the return button 17e. Therefore, after replacing the outlet that caused the heat generation, the plug 10 is again connected. It can be used and is easy to use.
Since the return button 17e protrudes when the thermostat 17 is operated, it can be easily determined from the outside that the thermostat 17 has been operated, and it is obvious that the cause of abnormal heat generation is on the outlet side. Therefore, there is no misunderstanding that the electrical equipment has failed.
Further, since the thermostat 17 detects the temperatures of the conductors A15 and B16 that are built in the case 18 and supply power to the load, the heat generated between the plug blade 11 and the receptacle blade is generated. Since the heat is transmitted quickly to the cap 17d of the thermostat 17 through the plug blade 11, the conductor A15, and the conductor B16 having excellent heat conductivity, the temperature can be detected earlier, and the energization can be cut off more safely.
In the above embodiment, the conductor A15 and the conductor B16 are arranged between the cap 17d of the thermostat 17 and the lower case 18b. However, as shown in FIG. 4, the bottom surface of the cap 17d faces the plug blade 11 side of the lower case 18b. In the present embodiment, in the present embodiment, the temperature of the inner wall of the lower case 18b may be directly detected by being brought into close contact with the bottom surface of the lower case 18b, so that the heat transferred from the outlet portion to the case 18 can be quickly obtained. Therefore, it becomes possible to detect with high accuracy, and it is possible to safely cut off the energization.
Moreover, in the said embodiment, although demonstrated based on the heat_generation | fever by the contact resistance between the receptacle blade and the plug blade 11 of the insertion plug 10, between the receptacle blade and the plug blade 11 of the insertion plug 10 was demonstrated. Even if the contact state of the battery is completely normal, if an abnormality occurs on the electrical equipment to be used and an excessive current flows, it will be inserted into the receptacle of the outlet compared to the case where the normal rated current is flowing. Heat generation between the plug blade 11 of the plug 10 and at each electrical connection in the case 18 of the plug 10 suddenly increases and the ambient temperature in the case 18 rises, so the thermostat 17 detects it. In this way, since the power supply to the electric device is cut off, the electric device can be protected.
(Embodiment 2)
FIG. 5 is an overall perspective view of the plug according to the second embodiment of the present invention, FIG. 6A is a plan view showing the internal configuration of the plug, and FIG. It is AA sectional drawing of). The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof is omitted.
In the first embodiment, the power cord with an insertion plug in which the power cord 12 is attached to the insertion plug 10 has been described as an example, but the insertion plug 20 in the present embodiment is shown in FIGS. Thus, a pair of plug blades 11 inserted into an outlet (not shown) and a plug blade of an external plug 21 provided at the tip of a conventional power cord 3 connected to an electric device (not shown) A receiving blade 22 that receives 21a, a conductor A15 that electrically connects one receiving blade 22 and one plug blade 11, and a gap between the other receiving blade 22 and the other plug blade 11 via a conductor B16. A thermostat 17 that is electrically connected is provided, and a plurality of slits 23 through which the plug blades 21a of the external plugs 21 are inserted are provided in the upper case 18a. The configuration, operation, and action of the thermostat 17 are the same as those in the first embodiment, and a description thereof will be omitted.
Since the plug 20 in the present embodiment is configured as described above, the thermostat 17 that functions as a branch outlet and prevents abnormal heat generation at the outlet itself is built in. Plug-ins that do not have built-in safety devices such as thermal fuses can be connected, so you can use already purchased electrical equipment with peace of mind.
In addition, as shown in FIG. 7, you may make it attach the said insertion plug 20 which has the receiving blade 22 which receives the plug blade 21a of the external insertion plug 21 to the power cord 12 connected to the electric equipment. By doing so, the plug 20 can be made even easier to use.

  As described above, the plug according to the present invention prevents abnormal heat generation at the outlet portion and surely prevents a fire, and also easily recovers even if the thermostat operates due to heat generation at the outlet portion. It can be used many times and can be used widely for various connectors with plug blades, power adapters, and charging adapters.

The perspective view of the power cord with an insertion plug which connected the insertion plug in Embodiment 1 of this invention (A) Plan view showing the internal configuration of the plug, (b) Side view of the plug blade of the plug, (c) Front view of the plug blade Partial enlarged sectional view of the thermostat mounting part of the plug Partial expanded sectional view which shows the other attachment example of the thermostat of the same plug Whole perspective view of the insertion plug in Embodiment 2 of this invention (A) The top view which shows the internal structure of the plug, (b) AA sectional drawing of (a) A perspective view showing an example of another plug Partial cutaway plan view of a conventional plug

Explanation of symbols

10, 20 Plug 11 Plug blade 12 Power cord 13 Conductor 15 Conductor A (conductor)
16 Conductor B (conductor)
17 Thermostat 18 Case 18a Upper case 18b Lower case 22 Receiving blade

Claims (5)

A plurality of plug blades and at least one of the plug blades are electrically connected. When a predetermined temperature is reached, the power supply to the electrically connected load is cut off, and once cut off the power supply is manually restored. An insertion plug comprising: a thermostat to be operated; and a case for housing the load side of the plug blade and the thermostat. The plug according to claim 1, wherein the thermostat detects the temperature of a conductor built in the case and supplying power to a load. The insertion plug according to claim 1, wherein the temperature of the inner wall on the plug blade side of the case is detected by a thermostat. The insertion plug according to any one of claims 1 to 3, further comprising a receiving blade for receiving a plug blade of an external insertion plug. The power cord with an insertion plug which has the insertion plug of any one of Claims 1-4 in one end.

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