CN209844548U - Composite protection device - Google Patents
Composite protection device Download PDFInfo
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- CN209844548U CN209844548U CN201920958897.7U CN201920958897U CN209844548U CN 209844548 U CN209844548 U CN 209844548U CN 201920958897 U CN201920958897 U CN 201920958897U CN 209844548 U CN209844548 U CN 209844548U
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- heat generation
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Abstract
The utility model discloses a composite protective device which has the characteristics of lightning protection, overvoltage and overcurrent protection and low residual voltage, the composite protection device comprises at least one protection unit, each protection unit comprises a piezoresistor, a first thermistor and a second thermistor, the first thermistor and the second thermistor are both positive temperature coefficient thermistors, the two thermistors are positioned at the same side of the piezoresistor, the outer side of the composite type protective device is coated with an insulating material layer or is injected with the insulating material layer, in the composite protection device, besides the normal overcurrent and overvoltage protection function of the two positive temperature coefficient thermistors and the piezoresistor, the thermistor can protect the piezoresistor under the condition of lightning stroke or power frequency overvoltage, further reduces the action of lightning stroke residual voltage, and improves the reliability of the piezoresistor.
Description
Technical Field
The utility model relates to a compound protection device, in particular to compound protection device with lightning protection excessive pressure overcurrent protection function, low residual voltage.
Background
The positive temperature coefficient thermistor and the piezoresistor are used as overcurrent and overvoltage protection devices and widely applied to electronic equipment such as intelligent electric meters, household appliances and the like so as to avoid the damage of a protected circuit caused by abnormal overvoltage or short circuit in an electronic circuit.
With the increasing performance requirements on electronic equipment and the increasing popularization of the electronic equipment as a smart meter for metering, the common positive temperature coefficient thermistor and the piezoresistor as overcurrent and overvoltage protection devices cannot completely meet the requirements of various performances of the electronic equipment. Electronic equipment such as smart meters, household appliances and the like used in China mostly have a normal working range of 220VAC +/-20%, when a ground fault or a wrong wire is connected, voltage of over 380VAC can occur, and in order to ensure that the electronic equipment is not damaged, the conventional piezoresistor and the conventional positive temperature coefficient thermistor are usually adopted as an over-protection device of a power supply in the market at present.
In the use process of a protection device manufactured in the prior art, the defects that the conventional positive temperature coefficient thermistor is difficult to match with a load, the universality is poor, too slow protection response time, even no protection or misoperation, no reduction of lightning stroke residual voltage and the like are easy to occur; in order to ensure that the voltage dependent resistor is not damaged under the power frequency voltage, a product with a high voltage dependent voltage value and a large size is usually selected to improve the reliability, but the problems of high use cost, high lightning residual voltage and the like exist in the protection device.
SUMMERY OF THE UTILITY MODEL
The utility model discloses aim at solving one of the technical problem that exists among the prior art at least, provide a compound protection device.
The utility model provides a composite protection device, the composite protection device comprises at least one protection unit, each protection unit comprises a piezoresistor, a first thermistor and a second thermistor, and the first thermistor and the second thermistor are positive temperature coefficient thermistors; wherein the content of the first and second substances,
the first end of the first thermistor is electrically connected with a first pole of a power supply, and the second end of the first thermistor is electrically connected with the first end of the second thermistor and the first end of the piezoresistor respectively;
the second end of the second thermistor is electrically connected with the first end of the protected circuit;
and the second end of the piezoresistor is respectively used for being electrically connected with the second pole of the power supply and the second end of the protected circuit.
Furthermore, the second end of the first thermistor, the first end of the second thermistor and the first end of the piezoresistor are welded together by tin soldering or bonded together by conductive paste.
Further, the first thermistor and the second thermistor adopt at least one of a positive temperature coefficient ceramic thermistor and a positive temperature coefficient polymer thermistor.
Further, the first thermistor and the second thermistor are located on the same side of the piezoresistor.
Furthermore, an insulating material layer is coated or injected on the outer side of the composite type protection device.
Furthermore, the insulating material layer is made of flame-retardant insulating resin materials or organic polymer insulating materials.
Furthermore, the first thermistor and the second thermistor are both of sheet structures, and the first thermistor and the second thermistor are matched in size and electrical property.
Further, the piezoresistor is a zinc oxide piezoresistor.
Further, the piezoresistor satisfies at least one of the following relations:
10mm≤φpress and press≤20mm；
1mm≤δPress and press≤5mm；
330V≤UPress and press≤820V；
Wherein said phiPress and pressThe diameter of the varistor, deltaPress and pressTo pressThickness of the thermistor, UPress and pressIs the voltage dependent voltage of the voltage dependent resistor.
Further, the first thermistor and the second thermistor both satisfy at least one of the following relations:
2.5mm≤φheat generation≤9mm；
1mm≤δHeat generation≤5mm；
70℃≤THeat generation≤130℃；
15Ω≤RHeat generation≤600Ω；
Wherein said phiHeat generationIs the diameter of the first thermistor and the second thermistor, the deltaHeat generationThe thickness of the first thermistor and the second thermistor, THeat generationIs the Curie temperature of the first thermistor and the second thermistor, RHeat generationIs the resistance of the first thermistor and the second thermistor.
The utility model discloses a compound protection device, piezoresistor and two positive temperature coefficient thermistor in the protection device except playing normal overcurrent overvoltage protection function, wherein first positive temperature coefficient thermistor can protect the piezoresistor under the condition of thunderbolt or power frequency excessive pressure, improves the reliability of piezoresistor; the second positive temperature coefficient thermistor can further reduce the residual voltage of lightning stroke; the piezoresistor is conducted to generate heat under the bearable load and conducts the heat to the positive temperature coefficient thermistor sheet, so that the power frequency overvoltage can be prevented from damaging the circuit, and the overcurrent protection effect is achieved.
Drawings
Fig. 1 is a front view of a composite type protection device according to a first embodiment of the present invention.
Fig. 2 is a side view of the composite type protective device shown in fig. 1.
Fig. 3 is a circuit diagram of a typical application of the composite protection device according to the first embodiment of the present invention.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1, fig. 2 and fig. 3, the composite protection device 100 of the present embodiment includes protection units 110, and the number of the protection units 110 may include only one as shown in fig. 1, and of course, those skilled in the art may design a greater number of protection units 110 according to actual needs. The protection unit 110 includes a varistor 111, a first thermistor 112, and a second thermistor 113, and the first thermistor 112 and the second thermistor 113 are both positive temperature coefficient thermistors. A first end of the first thermistor 112 is electrically connected to the positive electrode of the power supply 200, and a second end of the first thermistor 112 is electrically connected to a first end of the second thermistor 113 and a first end of the varistor 111, respectively. The second end of the second thermistor 113 is electrically connected to the first end of the protected circuit 300. The second end of the voltage dependent resistor 111 is electrically connected to the negative electrode of the power supply 200 and the second end of the protected circuit 300, respectively.
Specifically, as shown in fig. 3, in the composite protection device 100 of the present embodiment, when the voltage of the power supply 200 is in the normal range, the first thermistor 112 and the second thermistor 113 of the composite protection device 100 function as current limiting resistors in the circuit, and the breakdown voltage of the varistor 111 is greater than the normal voltage operating value, so that the composite protection device 100 does not affect the protected circuit 300.
On the contrary, as shown in fig. 3, when the power frequency voltage of the power supply 200 is too high and exceeds the breakdown threshold of the voltage dependent resistor 111 of the composite protection device 100, at this time, the voltage dependent resistor 111 is heated in a fast response, the two positive temperature coefficient thermistors thermally coupled with the voltage dependent resistor are also heated, the current flowing through the two positive temperature coefficient thermistors is rapidly increased due to the breakdown of the voltage dependent resistor 111, the two positive temperature coefficient thermistors generate self-heating and auxiliary heating of the voltage dependent resistor 111, and when the temperature of the positive temperature coefficient thermistors exceeds the curie temperature of the positive temperature coefficient thermistors, the two positive temperature coefficient thermistors rapidly enter a high-resistance state to share most of the voltage value, so that the voltages at the two ends of the voltage dependent resistor 111 and the protected circuit 300.
In addition, as shown in fig. 3, when the circuit 300 to be protected is short-circuited, the current flowing through the two ptc thermistors will increase rapidly and be much larger than the operating current value of the thermistors, and the ptc thermistors with relatively small operating current value will operate preferentially, enter a high-impedance state, reduce the current in the circuit, and protect the power supply 200 and the circuit 300 to be protected.
For another example, as shown in fig. 3, when the composite protection device 100 is subjected to lightning strike pulse overvoltage, the pulse voltage is much greater than the breakdown threshold of the voltage dependent resistor 111, the voltage dependent resistor 111 operates, the sum of the voltage across the second thermistor 113 and the voltage of the protected circuit 300 is equal to the clamping voltage of the voltage dependent resistor 111, and the residual voltage of the protected circuit 300 will be further reduced due to the current-limiting and voltage-dividing effects of the two positive temperature coefficient thermistors.
For another example, when the composite protection device 100 is used for a long time, the voltage dependent resistor 111 may be degraded and aged in load performance, at this time, when the voltage dependent resistor 111 receives a normal voltage, the leakage current of the voltage dependent resistor 111 increases to cause self-heating, and at the same time, the two positive temperature coefficient thermistors are assisted to heat, the first thermistor 112 also self-heats due to the increase of the leakage current of the voltage dependent resistor 111, and when the temperature of the first thermistor exceeds the curie temperature of the first thermistor, the first thermistor rapidly enters a high resistance state, the current is greatly reduced, and the first thermistor 112 can share most of the voltage value, thereby ensuring that the voltage dependent resistor 111 is not damaged, and improving the reliability of the whole composite protection device 100.
Specifically, in the present embodiment, as shown in fig. 1 and fig. 2, the second end of the first thermistor 112, the first end of the second thermistor 113, and the first end of the varistor 111 may be soldered or bonded together by using conductive plasma, or may be bonded together by other methods, but the present embodiment is not limited thereto.
Specifically, in the present embodiment, the first thermistor 112 and the second thermistor 113 may be positive temperature coefficient ceramic thermistors, or positive temperature coefficient polymer thermistors, or thermistors made of other materials, but the present embodiment is not limited thereto.
Specifically, in the present embodiment, as shown in fig. 1 and 2, the first thermistor 112 and the second thermistor 113 may be located on the same side of the varistor 111, and thus, the two thermistors are located on the same side of the varistor 111, and the structure of the composite type protection device 100 may be simplified.
Specifically, in this embodiment, in order to insulate the composite type protection device from the outside, the insulating layer may be formed by using a flame-retardant insulating resin material or an organic polymer insulating material on the outside, or may be formed by another method.
Optionally, the first thermistor 112 and the second thermistor 113 are both sheet-shaped structures, and the first thermistor 112 and the second thermistor 113 have matched volumes and matched electrical properties.
Specifically, in the composite protection device of the embodiment, the shapes, the volumes and the electrical performances of the two thermistors are matched, so that the composite protection device is convenient to package firstly, and can simplify the structure of a protection circuit secondly.
Specifically, in this embodiment, the piezoresistor 111 can be a zinc oxide piezoresistor, or a piezoresistor made of another material, but the embodiment is not limited thereto.
Optionally, the varistor 111 satisfies at least one of the following relations:
10mm≤φpress and press≤20mm； (1)
1mm≤δPress and press≤5mm； (2)
330V≤UPress and press≤820V； (3)
Wherein said phiPress and pressIs the diameter of the piezoresistor 111, the deltaPress and pressThickness of the piezoresistor 111, UPress and pressIs the voltage dependent voltage of the voltage dependent resistor 111.
Optionally, the first thermistor 112 and the second thermistor 113 both satisfy at least one of the following relations:
2.5mm≤φheat generation≤9mm； (4)
1mm≤δHeat generation≤5mm； (5)
70℃≤THeat generation≤130℃； (6)
15Ω≤RHeat generation≤600Ω； (7)
Wherein said phiHeat generationThe diameter of the first thermistor 112 and the second thermistor 113 is the value deltaHeat generationThe thickness of the first thermistor 112 and the second thermistor 113, the THeat generationIs the Curie temperature of the first thermistor 112 and the second thermistor 113, RHeat generationIs the resistance of the first thermistor 112 and the second thermistor 113.
The following will explain in detail the preparation method of the composite protection device of the present invention:
adopting a piezoresistor satisfying the formulas (1), (2) and (3) and two positive temperature coefficient thermistors satisfying the formulas (4), (5), (6) and (7), printing a proper amount of solder paste containing 3% of silver on one surface of the piezoresistor by screen printing, and pasting the two positive temperature coefficient thermistors on the same side of the piezoresistor in alignment with a solder paste printing pattern after printing, as shown in figure 1; the piezoresistor and the two thermistors are connected through reflow soldering. Three leads are respectively welded and led out on the electrode on one side of the non-common end of the composite type protective device, and the three leads are in the same direction; and (3) encapsulating a layer of organic silicon resin insulating layer by dip-coating the composite protection device containing three leads, and curing for 2 hours at the maximum temperature of 160 ℃ to obtain the composite protection device.
In order to verify the utility model provides a compound protection device's performance selects the compound protection device sample of making through above-mentioned preparation method, carries out following test to compound protection device sample:
1. testing the voltage-sensitive voltage: when the input voltage between 100 and 200 or between 100 and 300 is 390V +/-10 percent, and the leakage current is less than or equal to 20uA, two thermistors are connected in series between 200 and 300, the resistance value is 160 omega-240 omega, the Curie temperature is 105 +/-10 ℃, and the inactive current is 40mA/60 ℃.
2. Connecting the composite protection device into a protected circuit according to the diagram shown in FIG. 3, wherein the protected circuit works normally when the normal input voltage of a power supply end is 220VAC +/-20%; when the input voltage of the power supply end is 380VAC, the composite protection device enters a protection state, the voltage at two ends of the protected circuit reaches 180 VAC-250 VAC, and the load works normally; when the input power supply voltage is 220VAC +/-20%, and the load is in short circuit, the composite protection device enters a protection state, the current in the line is reduced to be within 10mA, and the power supply is protected without abnormality.
It is to be understood that the above embodiments are merely exemplary embodiments that have been employed to illustrate the principles of the present invention, and that the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (10)
1. A composite protection device is characterized by comprising at least one protection unit, wherein each protection unit comprises a piezoresistor, a first thermistor and a second thermistor, and the first thermistor and the second thermistor are both positive temperature coefficient thermistors; wherein the content of the first and second substances,
the first end of the first thermistor is electrically connected with a first pole of a power supply, and the second end of the first thermistor is electrically connected with the first end of the second thermistor and the first end of the piezoresistor respectively;
the second end of the second thermistor is electrically connected with the first end of the protected circuit;
and the second end of the piezoresistor is respectively used for being electrically connected with the second pole of the power supply and the second end of the protected circuit.
2. A composite protective device as claimed in claim 1, wherein the second end of the first thermistor, the first end of the second thermistor and the first end of the varistor are soldered together by soldering or bonded together by conductive paste.
3. A composite protective device according to claim 1, wherein the first thermistor and the second thermistor are at least one of a positive temperature coefficient ceramic thermistor and a positive temperature coefficient polymeric thermistor.
4. A composite protective device according to any of claims 1 to 3, wherein the first thermistor and the second thermistor are located on the same side of the varistor.
5. A composite protective device according to any of claims 1 to 3, characterized in that the outer side of the composite protective device is coated or injection moulded with a layer of insulating material.
6. A composite protective device according to claim 5, wherein the insulating material layer is made of a flame retardant insulating resin material or an organic polymer insulating material.
7. A composite protective device according to any of claims 1 to 3, wherein the first thermistor and the second thermistor are both in a sheet-like configuration, and the first thermistor and the second thermistor are volume-matched and electrical properties-matched.
8. A composite protective device according to any of claims 1 to 3, wherein the varistor is a zinc oxide varistor.
9. A composite protective device according to any of claims 1 to 3, wherein the varistor satisfies at least one of the following relationships:
10mm≤φpress and press≤20mm；
1mm≤δPress and press≤5mm；
330V≤UPress and press≤820V；
Wherein said phiPress and pressThe diameter of the varistor, deltaPress and pressIs the thickness of the varistor, UPress and pressIs the voltage dependent voltage of the voltage dependent resistor.
10. A composite type protection device according to any one of claims 1 to 3, wherein each of the first thermistor and the second thermistor satisfies at least one of the following relationships:
2.5mm≤φheat generation≤9mm；
1mm≤δHeat generation≤5mm；
70℃≤THeat generation≤130℃；
15Ω≤RHeat generation≤600Ω；
Wherein said phiHeat generationIs the diameter of the first thermistor and the second thermistor, the deltaHeat generationThe thickness of the first thermistor and the second thermistor, THeat generationIs the Curie temperature of the first thermistor and the second thermistor, RHeat generationIs the resistance of the first thermistor and the second thermistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920958897.7U CN209844548U (en) | 2019-06-25 | 2019-06-25 | Composite protection device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920958897.7U CN209844548U (en) | 2019-06-25 | 2019-06-25 | Composite protection device |
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| CN209844548U true CN209844548U (en) | 2019-12-24 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110212509A (en) * | 2019-06-25 | 2019-09-06 | 厦门市三宝盈科电子有限公司 | A kind of compound protection device |
| CN112114601A (en) * | 2020-07-20 | 2020-12-22 | 南京弘图华智科技有限公司 | Self-resistance heating forming intelligent temperature detection control system and control method thereof |
-
2019
- 2019-06-25 CN CN201920958897.7U patent/CN209844548U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110212509A (en) * | 2019-06-25 | 2019-09-06 | 厦门市三宝盈科电子有限公司 | A kind of compound protection device |
| CN112114601A (en) * | 2020-07-20 | 2020-12-22 | 南京弘图华智科技有限公司 | Self-resistance heating forming intelligent temperature detection control system and control method thereof |
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