RU2794136C2 - Electric plug - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: in an electrical mains plug with a housing (1) made of electrically insulating material, two contact rods (3) are located parallel to each other, which protrude from the housing (1) on its first side and are connected inside the housing (1) with an electrical conductor (4), which is removed from the body (1) on its second side, and a thermobimetallic element is also provided as a temperature sensor, and the specified thermobimetallic element is an integral part of the thermobimetallic switch (7) associated with at least one of the two contact rods (3).

EFFECT: facilitating the manufacture of a power plug.

14 cl, 7 dwg

Description

The invention relates to a mains plug with a housing made of an electrically insulating material, in which two contact rods are arranged parallel to each other, each of which protrudes from the housing on its first side and inside the housing, is connected or can be connected to an electrical conductor that is brought out or can be removed from the housing on its second side, and in which the sensor is provided. Such a mains plug is known from DE 102015206840 A1. The well-known mains plug refers to a charger for charging an electric or hybrid vehicle battery from an AC source. The charging cable connects the mains plug to the charger. In order to protect against overheating, the mains plug contains a sensor consisting of two contact rods, for example, made of iron, and consisting of four wires made of a metal other than iron, for example, copper-nickel alloy. Each of these copper-nickel wires is soldered to two points on each contact bar that are spaced apart in the longitudinal direction of the contact bar. At distant connection points, an electrical potential difference is created by the Seebeck effect, which depends on the temperature difference between the two connection points. Thus, it is possible to determine the temperature gradient along each contact rod and measure its size. However, the manufacture of such a power plug is complicated; The mains plug loads the copper-nickel wires with full mains voltage and does not allow an absolute temperature measurement in the mains plug, but simply indicates whether there is a temperature gradient or not. This does not allow reliable temperature control because the temperature may be excessively high even if the temperature gradient is not visible.

The object of the present invention is to provide a mains plug which allows temperature control of the mains plug's pin and which is easier to assemble than the mains plug according to DE 102015206840 A1.

According to the invention, this problem is solved using a power plug having the features of paragraph 1 of the claims. Preferred additional embodiments of the invention are the subject matter of the dependent claims. Paragraph 22 of the claims refers to an electrical cable to which a mains plug according to the invention is connected. Claims 23-25 refer to an electrical device that is configured to control at least one thermal bimetallic switch provided in the mains plug and that limits or can limit the power consumption of the electrical device if a predetermined threshold temperature is exceeded. An electrical device may sense a temperature threshold exceeded by the fact that at least one thermobimetal switch reaches or exceeds its switching temperature and, as a result, its switch position changes from "open" to "closed" or from "closed" to "open". ".

The invention has significant advantages:

- The installation of a thermobimetal switch allows a reliable temperature control in the mains plug, which is a measurement of the temperature of the contact rod, when, as provided, the thermobimetal switch is assigned to the contact rod.

- Thermobimetal switches are available in such a small size both in open and closed design, i.e. with a switchgear surrounded by a casing, that they can be easily placed in a commercially available mains plug. Suitable thermobimetallic switches with closed design are disclosed, for example, in DE 10200831389 B3 and DE 10200436367 B4.

- With possible small sizes of thermobimetallic switches, each contact rod can have its own thermobimetallic switch associated with it. This improves the security of the control.

- In any case, the thermobimetal switch can be located in direct contact with the contact rod if it has an electrically non-conductive casing.

The current flowing through the contact rod is not supplied to the thermobimetal switches.

Thermal bimetal switches have a predetermined switching temperature, which is determined by the choice of material for the thermal bimetal and the mechanical design of the switch, and can be adapted to the respective application.

- Exceeding or falling below a predetermined temperature threshold can be simply determined by changing the switching position of the thermobimetal switch from "open" to "closed" or from "closed" to "open".

- The switching position of the thermobimetallic switch can be determined, for example, by applying an electrical test voltage to the connections of the thermobimetallic switch, which causes current to flow only through the thermobimetallic switch when the switch is closed, and the current current can be easily measured. The electrical test voltage may, for example, come from an electrical device that is connected to the electrical network via a mains plug.

- By forming the thermobimetal element in the form of a clip with a latch, it is possible to ensure that the curvature of the thermobimetallic element changes abruptly when the switching temperature is reached, so that the switching temperature can be set within narrow limits.

- The thermobimetal switch may have a contact spring, which is made of copper or copper alloy, and which is actuated by a thermobimetallic spring clip with a latch held on the contact spring. However, it is also possible to manufacture the contact spring itself from a thermobimetallic element, so that a separate thermobimetallic element is not required to actuate the contact spring. Thus, this simplified embodiment of the thermobimetal switch is possible, in particular, because the mains current does not flow through the contact spring of the thermobimetallic switch.

- Thermobimetal switches are inexpensive and have a long service life.

- Thermobimetal switches can be prefabricated and inserted into the socket intended for them in the mains plug. Such fastening can be carried out during the manufacture of the mains plug, for example, by forming its casing or its internal structures by injection molding without additional production costs.

- Using the power plug according to the invention, it is possible to register not only the overheating of the power plug itself, but also the overheating of the socket in which the power plug is located. Sockets are more at risk of overheating than mains plugs, in particular due to corrosion of the socket contacts in the socket and the resulting increased contact transfer resistance, as well as due to mechanical deformation of the socket contacts in the socket. Therefore, the power plug according to the present invention is also particularly suitable for preventing overheating in the socket, thereby preventing subsequent damage such as fire.

If the mains plug has only one thermobimetal switch, it can be positioned in such a way that it reacts equally well to the temperature of both contact rods. For this purpose, the thermobimetal switch can be placed in parallel with the two contact rods of the mains plug in the middle between them. As an alternative, the thermobimetal switch can also be arranged transverse to the two contact bars. If the thermobimetal switch has an electrically insulating casing or electrically insulating carrier, it can also be in contact with these two contact bars, which facilitates the transfer of heat from the contact bars to the thermobimetallic switch. However, it is also possible to position a separate thermobimetal switch closer to one contact bar than to the other. This will result in a faster response to the excessive temperature of the nearest contact rod.

Preferably, the mains plug is provided with two thermobimetal switches, each of which is located next to one of the two contact rods. This ensures optimum heat transfer from the contact bars to the thermobimetal switches, since both can be located next to the contact bars, preferably one directly next to one contact bar and the other next to the other contact bar. In addition, excessively high temperatures can only be detected reliably on one of the two contact rods, and the reliability of monitoring is increased since monitoring is also possible in the event of failure of one thermal bimetal switch.

If two thermobimetal switches are provided, they are preferably both positioned between two contact bars of the mains plug, preferably in direct contact with the corresponding contact bar. However, it is also possible to arrange both bimetallic contact switches transverse to the contact bars, preferably in direct contact with the contact bars.

For each thermobimetallic switch in the mains socket, a separate mount can be formed. This is possible, in particular, if the mains plug has a casing consisting of two additional parts made by injection molding of synthetic material, these parts being designed to hold the contact rods in place. This structure can already be formed with thermobimetal switch fixtures without an additional workflow by injection molding, and it only needs to be inserted with thermobimetallic switches to assume a predetermined position.

However, the invention is also suitable for mains plugs, the internal components of which are injection-molded from a synthetic housing material, in particular so as to form a one-piece housing.

Network plugs are known, in the housings of which an electrically insulating cover is provided, under which those points of the contact rods are located, in which they are connected or can be connected to electrical conductors brought out of the second side of the housing. The cover protects these points, for example, from the synthetic material that is used to form the mains plug housing by multi-layer molding of its internal components. The thermobimetallic switch(es) is preferably located at least partially under the cover. If access of the casting mix to the thermobimetallic switches is prevented by a cover, it is even possible to use open thermobimetallic switches in such a mains plug, i.e. unenclosed switches, which can respond to elevated temperatures more quickly than encased switches.

For each thermobimetallic switch, a separate fastening can be provided under the cover. Preferably, the lid itself is configured to include a fastener. Since such a lid is expediently produced by injection molding from synthetic material, the lid can be formed without additional effort by appropriately molding it with suitable fixtures for thermobimetallic switches, into which the thermobimetallic switches need only be inserted, in particular pushed or connected.

The fixtures for the thermobimetal switches preferably protrude from the top side of the lid into the space below the lid; this is the space in which the rear ends of the contact rods are located, protected by a cover.

In order to insert the thermobimetal switches into their respective holders, it is preferable that the holders protruding from the top side of the cover into the space under the cover are open from above, i.e. on the top side of the cover. The thermobimetal switches can then be inserted into their respective holder, optionally before or after applying the cover to the holder, which is made of electrically insulating material and which is preferably provided for the contact rods. Such a holder and its advantages for the rational manufacture of the mains plug are described below.

Preferably, the holders are open on their side facing the nearest contact bar to facilitate heat transfer from the contact bar to the thermobimetal switch. If thermobimetallic switches are used which have a housing, it preferably consists of a ceramic, such as alumina ceramic, because it conducts heat better than synthetic materials. If it is ensured that the body is not in contact with the nearest contact bar, it can also be made from a metal which has the advantage of good thermal conductivity.

If two thermal bimetallic switches are provided in the mains plug, they are preferably connected to a common printed circuit board at the mechanical and electrical level. The common printed circuit board and the two thermobimetal switches thus form a module which facilitates the manufacture of the mains plug according to the invention, because the module can be prefabricated, for example, by the manufacturer of the thermobimetallic switches, so that it only needs to be connected to the fixtures provided for the thermobimetal switches by the mains plug manufacturer . Connection points for signal lines can be provided on the small printed circuit board, through which thermobimetal switches can be connected to an external control device. However, the connecting wires of thermal bimetal switches can be inserted through holes in the printed circuit board, soldered, and then soldered to the signal lines.

If two thermobimetallic switches are provided, then two, three or four signal lines can be provided for them. Two signal lines are sufficient if two thermobimetal switches are connected in series and closed below their switching temperature. With four signal lines, two thermobimetal switches can work independently, and two contact bars can be controlled independently; but this is also possible with only three signal lines if one connection from each thermobimetal switch is connected to a common signal line.

Signal lines can be bundled together with electrical conductors that carry mains current into the sheathed cable. Such cables are as modern as thermobimetal switches and can be used in a power outlet according to the invention.

In particular, in the case of mains plugs, the body of which is made in one piece by injection molding of synthetic material, it is known to use a separate carrier of electrically insulating material for the contact rods. Such a carrier is also called a "bridge" by fork manufacturers. The carrier can be made by injection molding. It is also known to fasten the lid to such a holder, in particular by snapping it into place, wherein the connections of the contact rods are located under the lid. This holder and the attached cover protect the underlying parts of the fork when injection molding the fork. The holder, the terminal pins attached to it, the cable connected to it, and the cover can be prefabricated in the form of a module and supplied to form the plug body by multi-layer molding of the module from synthetic material or to be inserted into a prefabricated plug body. This module can also contain thermal bimetallic switches and a connecting printed circuit board to which the ends of the signal lines are attached. Fasteners for thermobimetallic switches can be made in this module either on the holder or on the cover, which is fixed on the holder. Due to this modularity, the mains plug according to the invention can be efficiently produced with one or two thermobimetal switches. Instead of attaching the ends of the signal line to the printed circuit board in contact with the thermobimetal switches, they can also be attached directly to the electrical connections of the thermobimetal switches. The advantage is that no PCB is needed. To make this possible, it is expedient that the thermobimetal switches, as shown in FIG. 3 and FIG. 4 had connecting wires protruding upward from the cover.

The electrical connecting cable, to which the mains plug according to the invention is connected, can be connected via its conductors carrying the mains current and via the signal conductors coming from the thermobimetal switches directly or via the device plug to the electrical device to be powered from the mains. Such a device preferably has an electrical control device which controls whether the switching position of the thermobimetal switch(es) is open or closed. For this purpose, a test voltage can be applied to the signal lines in an electrical device, and this test voltage causes current to flow through the thermobimetal switch when the thermobimetallic switch is closed, but interrupted when the thermobimetallic switch is open. Thus, the control device in the electrical device can register the position of the thermobimetal switch and, if the registered switch position means that the switching temperature of the thermobimetallic switch has been exceeded, temporarily reduce or interrupt the power consumption of the device, thus preventing or counteracting overheating. Preferably, in such a case, the current in the network is not completely interrupted, but the power consumption of the device is reduced to a value at which, instead, the temperature of the thermobimetallic switch falls below its switching temperature. For this purpose, the electrical device preferably includes a controller that performs appropriate power management.

Exemplary embodiments of the invention are shown in the accompanying drawings.

In FIG. 1 is an exploded view of a first exemplary embodiment of a power plug according to the invention,

in fig. 1a shows a perspective view of the outside of the holder of FIG. 1,

in fig. 2 is a perspective view of the internal structure of the mains plug of FIG. 1,

in fig. 3 is an exploded view of a first exemplary embodiment of a power plug according to the invention,

in fig. 4 is a perspective view of the internal structure of the mains plug of FIG. 3,

in fig. 5 is a flowchart explaining the basic procedure for monitoring the temperature of the power plug to ensure that the power plug and the socket where the power plug is connected are not overheated, and

in fig. 6 is an exploded view of a third exemplary embodiment of a power plug according to the invention.

Identical or corresponding parts are designated in exemplary embodiments by the same reference numbers.

The mains plug from Fig. 1 is a "two-prong grounded plug" ("Schuko plug") and has a body 1 which can be injection molded from synthetic material and serves to accommodate the other components of the mains plug. These components include a holder 2, consisting of an electrically insulating synthetic material, into which two contact rods 3 are inserted, parallel to each other, and at the rear end of each contact rod 3, an electrical conductor 4 is connected, carrying the mains current. In addition, two protective contacts 5 are attached to the holder 2, as is usually the case with a two-prong earthed plug, the contacts of which are connected to the protective conductor 24. On the side of the holder 2 facing the inside of the housing 1, the holder 2 is formed so that it contains two fasteners 6, which are located between the contact rods 3 parallel to them. Each of them is used to receive one thermobimetal switch 7, the switchgear of which is located in a housing, which can be a deep-drawn part made of sheet metal, or a molded part made of ceramic or synthetic material. Each of the two connecting wires 8 is led out of the housing of the thermobimetal switch 7. The thermobimetallic switches 7 are pushed into the fixtures 6, with the connecting wires 8 protruding upwards (according to the image in Fig. 1) from the fixture 6. The fixtures 6 are arranged in such a way that they have the smallest possible distance from the nearest contact rod 3 in order to achieve the best heat transfer from it to the adjacent thermobimetallic switch 7. In addition, for this purpose, an opening 9 can be provided in the corresponding adjacent contact rod 3 facing the corresponding fastening 6.

A total of four connecting wires 8 of two thermobimetal switches 7 are connected to four electrical signal lines 10, of which only two signal lines 10 are shown for clarity, and which are assembled together with electrical conductors 4 carrying the power supply and with a protective conductor 24 to form a common cable 11 .

To facilitate the installation and connection of thermobimetallic switches 7, their connecting wires 8 are inserted into the holes of a small printed circuit board 12 and soldered to the traces of the conductors on it. The holes in the printed circuit board 12 and the traces of the conductors on the printed circuit board are not shown in FIG. 1. The two thermobimetal switches 7 and the printed circuit board 12 form a module that is easy to handle, can be prefabricated and can be inserted by its thermobimetal switches 7 into the fixtures 6 as a module. Thereafter, the signal lines 10 may be soldered to the connection wires 8 protruding from the printed circuit board 12, or to the traces of conductors formed on the printed circuit board 12 and leading to the connection wires 8; the conductors 4 can be connected to the contact bars 3 and the protective conductor 24 can be connected to the protective contacts 5.

After connecting the cable 11 to the contact rods 3, to the protective contacts 5 and to the thermobimetal switches 7, the semi-finished assembly shown in FIG. 2. In FIG. 2 shows the position of the lowered in FIG. 1 holes through which the connecting wires 8 of thermobimetallic switches 7 pass. see fig. 1. An assembly consisting of a holder 2 and other components of the mains plug attached to it, including thermobimetallic switches 7, a printed circuit board 12, a cover 16, and also consisting of an end part of the attached cable 11, can be molded from a synthetic material to form a housing 1 In the resulting network plug, housing 1 encloses the node. The contact rods 3 and protective contacts exit the housing 1 from the first, front side 13 of the housing 1. On the second rear side 13 of the housing 1, a bushing 14 is formed, from which the cable 11 is led out.

In FIG. 1a shows a modified version of the holder 2 with contact bars 3 and protective contacts 5 attached to it. In this case, the latter elements are connected to each other on the side facing outward to the mains plug via a conductive bridge 23.

The exemplary embodiment of FIG. 3 and 4 differs from the exemplary embodiment of FIG. 1 and 2 in that the fasteners 6 for the thermobimetal switches 7 are made not on the holder 2, but on the cover 16. Thus, the thermobimetallic switches 7 are first attached to the cover 16 and then together to the holder 2, or are pushed into the fasteners 6 after the cover 16 snaps onto the holder 2. In this case, the printed circuit board 12 rests on the cover 16 and closes it from above. The mounts 6 for the thermobimetal switches 7 protrude from the upper side of the cover 16 into the space between the holder 2 and the cover 16 where, as in the first exemplary embodiment, they pass between the two contact rods 3 as close as possible to the respectively nearest contact rod 3.

The connecting wires 8 of the thermobimetal switches 7 protrude upward from the cover 16 and are connected, as in the first exemplary embodiment, to a printed circuit board 12, which is also located above and preferably on the cover 16.

The assembly consisting of a holder 2 with contact rods 3 and protective contacts 5, as well as a cover 16 snapped onto the holder 2 with thermobimetal switches 7 inserted into it and connected by means of a printed circuit board 12, can be prefabricated, connected to the cable 11 and then The end of the cable 11 which faces away from the mains plug can either be directly connected to an electrical device or provided with a plug for the device.

In the exemplary embodiments of FIG. 1, 2, 3 and 4, only two of the four signal lines 10 for the two thermobimetal switches 7 are shown for clarity.

The exemplary embodiment of FIG. 6 is different from the embodiment of FIG. 3 and 4 in that there is no printed circuit board 12. Instead of four signal lines, only two signal lines 10 are provided, one of which is connected to a thermobimetallic switch 7. Two thermobimetallic switches 7 are electrically connected in series using a metal pin 25. It follows that through two signal lines 10 the exceeding of the switching temperature of one thermobimetallic switch or another thermobimetallic switch or both thermobimetallic switches 7 can be signaled, for example, by the fact that a low quiescent current flows through the signal lines when the thermobimetallic switches 7 are closed below their switching temperature, and by that when the switching temperature is exceeded, one or both thermobimetallic switches 7 open and the quiescent current is interrupted.

An assembly inserted into the body 1 or molded from a synthetic material to form the body 1 can be manufactured in a very rational manner. The fixtures 6 for the thermobimetal switches 7 can be made without any additional operation during molding, in particular during the injection molding of the insulating cover 16. The thermobimetal switches 7 can be inserted into the fixtures 6 before or after attaching the cover 16 to the holder 2; they can be electroconductively connected via pin 25 before or after insertion into fixtures 6 so that the system of cover 16 and attached thermal bimetal switches 7 can be prefabricated and used as a module. Ultimately, the thermobimetal switches 7 stuck in the cover 16 can be connected to the signal lines 10 either before or after applying the cover 16 to the holder 2.

Therefore, the power plug structure according to the invention can be flexibly assembled using various assembly methods.

The power plug temperature control method can be explained based on the flowchart of FIG. 5. In FIG. 5 schematically shows a mains plug 17 which is connected to a mains socket 18. From the mains plug a cable 11 leads to an electrical device 19 which is a consumer for the power supply. In the example shown, it is upstream of consumer 20. Device 19 comprises a control device 21 which applies a test voltage to two thermobimetal switches 7. Assuming the thermobimetal switches 7 are designed to be open below their switching temperature and closed above their switching temperature , the control device does not detect the flow of current on the signal lines while the thermobimetal switches 7 are open, because their temperature is lower than the switching temperature. However, if the temperature rises above their switching temperature, at least one thermobimetal switch closes, which the monitoring device registers from the current currently flowing through the signal lines. After that, the control device 21 then starts, for example, a current switch 22, which reduces or interrupts the electric current flowing to the consumer 20 until the temperature of the thermobimetal switch (s) in the mains plug 17 again drops below its (their) temperature switching. Preferably, the power supply to the consumer 20 is not completely cut off, but is reduced until the temperature of the thermobimetallic switch(s) 7 is below its (their) switching temperature again. Thus, the current switch 22 and the control device 21 are interconnected to form a control circuit.

LIST OF REFERENCES

1. body

2 holder

3 contact rods

4 conductor

5 protective contacts

6 mounts

7 thermobimetal switches

8 connecting wires

9 hole in 6

10 signal lines

11 cable

12 PCB

13 first side 1

14 sleeve

15 second side 1

16 cover

17 mains plugs

18 power plug socket

19 electrical device

20 consumer

21 control devices

22 current key

23 bridge

24 protective conductor

25 pin

Claims (15)

1. Electric mains plug with a housing (1) made of electrically insulating material, in which two contact rods (3) are located parallel to each other, each of which protrudes from the housing (1) on its first side and is connected or can be connected inside body (1) with an electrical conductor (4), which is withdrawn or made with the possibility of being removed from the body (1) on its second side, in which a sensor is provided, and the sensor is a temperature sensor, namely a thermobimetallic element that is an integral part of a thermobimetallic switch (7) connected to at least one of two contact rods (3), while two contact rods (3) are attached to a separate holder (2) made of electrically insulating material, with a separate holder (2) located in the housing (1 ), characterized in that an electrically insulating cover (16) is provided in the body (1) of the plug, and under the specified cover (16) there are those points of the contact rods (3) in which they are connected or made with the possibility of connection with electrical conductors (4) , withdrawn from the second side of the housing (1), wherein the specified cover (16) is attached to a separate holder (2) and the specified cover (16) is made so that it contains a fastener (6) for a thermobimetallic switch (7). 2. Mains plug according to claim 1, in which two thermobimetallic switches (7) are provided in the housing (1), and a fastening (6) is provided for each of the two thermobimetallic switches (7). 3. Mains plug according to claim 2, in which one of the two thermobimetallic switches (7) is located closer to the first of the two contact rods (3) than to the second of the two contact rods (3), and the other of the two thermobimetallic switches (7 ) is closer to the second contact rod (3) than to the first contact rod (3). 4. Power plug according to any one of claims 1 to 3, in which one or two thermobimetallic switches (7) are located next to at least one of the two contact rods (3) or between two contact rods (3). 5. Mains plug according to any one of claims 1 to 4, in which the thermobimetallic switch (s) (7) is (are) located at least partially under the cover (16). 6. Mains plug according to any one of claims 1 to 5, in which the mount(s) (6) protrudes(s) from the top side of the cover (16) into the space under the cover (16). 7. Mains plug according to claim 6, in which the fastening(s) (6) are open(s) in the direction of the top so that it is possible to push the thermobimetallic switch(s) (7) from above into the space under the cover (16). 8. Mains plug according to any one of claims 1 to 7, in which the thermobimetallic switch (s) (7) has (have) connecting wires (8) protruding upward from the cover (16). 9. Power plug according to any one of claims 1 to 8, in which the thermobimetallic switch (s) (7) has (have) a metal casing that does not come into contact with the nearest of the two contact rods (3). 10. Power plug according to any one of claims 1 to 9, in which the cover (16) is attached to a separate holder (2) by snapping it onto it. 11. Electrical connecting cable (11) to which is connected the mains plug according to any one of claims 1 to 10, and in which, in addition to the electrical conductors (4) coming from the contact rods (3) and the protective conductor (24) provided if necessary, the signal lines (10) connected to the thermobimetal switch(es) (7) pass. 12. An electrical device configured to be connected to a power source by means of a connecting cable (11) according to claim 11, characterized in that it has an electrical control device (21) configured to control whether the thermal switch(es) is (are) ) (7) open or closed. 13. Electrical device according to claim 12, characterized in that the control device (21) is designed in such a way that after registering the position of the thermobimetallic switch (7), caused by exceeding its switching temperature, it temporarily reduces or interrupts the power consumption of the device (19, 20) . 14. An electrical device according to claim 13, characterized in that it comprises a controller designed in such a way that, after registering an excess of the switching temperature of the thermobimetallic switch (7), by the control device (21) and thus, when triggered, it reduces the power consumption until until none of the thermobimetal switches (7) are in their switching position, which was assumed when their switching temperature was exceeded.

Images