CN114566954A

CN114566954A - Access protection circuit for two-wire system bathroom heater switch

Info

Publication number: CN114566954A
Application number: CN202210194686.7A
Authority: CN
Inventors: 赵峰
Original assignee: Jiaxing Sunrise Electronic Technology Co ltd
Current assignee: Jiaxing Sunrise Electronic Technology Co ltd
Priority date: 2022-03-01
Filing date: 2022-03-01
Publication date: 2022-05-31

Abstract

The invention discloses an access protection circuit for a two-wire system bathroom heater switch, which comprises: the reverse connection prevention protection circuit is used for preventing reverse connection from damaging a bathroom heater switch during installation; the strong current prevention protection circuit is used for preventing strong current from entering the bath heater switch; the anti-reverse-connection protection circuit is electrically connected with the anti-strong current protection circuit. The access protection circuit for the two-wire system bathroom heater switch is simple in structure and convenient to use, ensures that the input power supply of the bathroom heater switch is still correct when a product is in a reverse connection condition by adopting the rectifier bridge stack, ensures that the product is in a wrong connection condition of strong electricity by matching the self-recovery fuse and the piezoresistor, and protects the strong electricity from entering the bathroom heater switch.

Description

Access protection circuit for two-wire system bathroom heater switch

Technical Field

The invention relates to the technical field of access protection circuits, in particular to an access protection circuit for a two-wire system bathroom heater switch.

Background

The existing two-wire bathroom heater switch usually uses a diode for reverse connection protection, and has two modes of being connected in series on a power circuit and reversely connected in parallel at a power input port. The two protection modes can protect the key switch from being damaged by reverse voltage but the key switch cannot be normally used when the wiring is installed and the reverse power supply is connected, and the key switch needs to be taken down and installed again. This problem is due to the convenience and lower cost of both methods.

The existing two-wire system bathroom heater switch is generally not protected by strong current prevention, which is mainly because the cost of the circuit of the strong current prevention equipment is higher. What prevent strong current protection in some on the market is that the second line weak current bathroom heater switch strong current protection device that uses zener diode cooperation triode drive relay to realize, its cost is higher, and the relay is bulky moreover, is difficult to the installation, places and needs very big installation space in the key switch bottom. The universality is not high, and the equipment can be placed into the bottom shell of the key switch by special design.

Based on the above situation, the present invention provides an access protection circuit for a two-wire system bathroom heater switch, which can effectively solve one or more of the above problems.

Disclosure of Invention

The invention aims to provide an access protection circuit for a two-wire system bathroom heater switch. The access protection circuit for the two-wire system bathroom heater switch is simple in structure and convenient to use, ensures that the input power supply of the bathroom heater switch is still correct when a product is in a reverse connection condition by adopting the rectifier bridge stack, ensures that the product is in a wrong connection condition of strong electricity by matching the self-recovery fuse and the piezoresistor, and protects the strong electricity from entering the bathroom heater switch.

The invention is realized by the following technical scheme:

an access protection circuit for a two-wire bathroom heater switch, comprising:

the reverse connection prevention protection circuit is used for preventing reverse connection from damaging a bathroom heater switch during installation;

the strong current prevention protection circuit is used for preventing strong current from entering the bathroom heater switch;

the anti-reverse-connection protection circuit is electrically connected with the anti-strong current protection circuit.

Preferably, the reverse connection prevention protection circuit is a rectifier bridge stack BD.

Preferably, the anti-strong current protection circuit includes a first self-recovery fuse F1, a second self-recovery fuse F2, and a resistance element;

and a pin 1 of the rectifier bridge stack BD is electrically connected with one end of a first self-recovery fuse F1 and one end of a resistance element respectively, and a pin 2 of the rectifier bridge stack BD is electrically connected with one end of a second self-recovery fuse F2 and the other end of the resistance element respectively.

Preferably, the bridge rectifier stack BD comprises a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4;

the first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are connected in series in sequence.

Preferably, the resistance element is a voltage dependent resistor R1 or a bidirectional TVS diode D5.

Compared with the prior art, the invention has the following advantages and beneficial effects:

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Detailed Description

In order that those skilled in the art will better understand the technical solutions of the present invention, the following description of the preferred embodiments of the present invention is provided in conjunction with specific examples, but it should be understood that the drawings are for illustrative purposes only and should not be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.

Example 1:

as shown in fig. 1, the present invention provides an access protection circuit for a two-wire system bathroom heater switch, comprising:

Further, in another embodiment, the reverse connection prevention protection circuit is a bridge rectifier stack BD.

The full-bridge rectifier bridge stack BD is composed of four diodes and is provided with four leading-out pins. The connection point of the cathodes of the two diodes is Vo + in the picture of the anode of the full-bridge direct current output end, and the connection point of the anodes of the two diodes is Vo-in the picture of the cathode of the full-bridge direct current output end.

Whatever the input power direction, the input power is the same, namely Vo +, Vo-output is fixed in the figure, regardless of the direction of Vin +, Vin-, even if the input port power is exchanged, the output is still unchanged.

Further, in another embodiment, the anti-strong electric protection circuit includes a first self-recovery fuse F1, a second self-recovery fuse F2, a resistance element;

self-restoring fuse:

a self-restoring fuse is an overcurrent electronic protection element, which is made up by using high-molecular organic polymer, under the conditions of high pressure, high temp. and sulfurization reaction, and mixing with conductive particle material, and adopting a special technological process. The traditional fuse overcurrent protection can only protect once and is blown to be replaced, and the self-recovery fuse has the dual functions of overcurrent and overheat protection and automatic recovery.

The action principle of the self-recovery fuse is dynamic balance of energy, current flowing through the self-recovery fuse generates heat to a certain degree (the self-recovery fuse has resistance values) due to the relation of current heat effect, all or part of the generated heat is dissipated to the environment, and the temperature of the self-recovery fuse element can be increased without the dissipated heat.

The temperature is lower during normal operation, and the generated heat and the dissipated heat reach balance.

The self-healing fuse element is in a low resistance state, the self-healing fuse does not operate, and when the current flowing through the self-healing fuse element increases or the ambient temperature rises, the self-healing fuse remains inactive if a balance of generated heat and dissipated heat is reached.

When the current or ambient temperature increases again, the self-healing fuse reaches a higher temperature.

If the current or the ambient temperature continues to increase again, the generated heat is larger than the heat emitted, so that the temperature of the self-recovery fuse element increases suddenly, at this stage, a small temperature change can cause a great increase in the resistance value, at this time, the self-recovery fuse element is in a high-resistance protection state, the current is limited by the increase of the impedance, and the current drops suddenly in a short time, so that the circuit equipment is protected from being damaged, and the self-recovery fuse element in the changing state can be in an action state (high resistance) all the time as long as the heat generated by the applied voltage is enough to the heat emitted by the self-recovery fuse element.

The self-healing fuse is automatically restored when the applied voltage is removed.

Further, in another embodiment, the bridge rectifier stack BD includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4;

Further, in another embodiment, the resistive element is a voltage dependent resistor R1 or a bidirectional TVS diode D5.

Example 2:

the reverse connection prevention protection circuit is used for avoiding damage to the bathroom heater switch caused by reverse connection during installation;

The resistance element is a piezoresistor R1.

The voltage dependent resistor is a short for voltage sensitive resistor, and is a nonlinear resistor element. The resistance of the varistor is related to the magnitude of the voltage applied across it, and when the voltage applied to the varistor is within its nominal value, the resistance of the resistor assumes an infinite state with almost no current passing through it. When the voltage at the two ends of the piezoresistor is slightly larger than the nominal voltage, the piezoresistor is quickly broken down and conducted, the resistance value of the piezoresistor is quickly reduced, and the resistor is in a conducting state. When the voltage is reduced to be lower than the nominal voltage, the resistance value of the voltage-sensitive resistor starts to increase again, and the voltage-sensitive resistor returns to a high-resistance state.

The operation principle of the voltage dependent resistor is that when the voltage applied to the voltage dependent resistor is lower than its threshold value, the current flowing through it is extremely small, which corresponds to a resistor with infinite resistance. That is, when the voltage across it is below its threshold, it behaves as an open-state switch.

When the voltage across the varistor exceeds its threshold, the current flowing through it increases sharply, corresponding to a resistance of infinitesimal magnitude. That is, when the voltage applied to it is above its threshold, it behaves as a closed-state switch.

Example 3:

The resistive element is a bidirectional TVS diode D5.

The working principle of one embodiment of the invention is as follows:

an access protection circuit for a two-wire system bathroom heater switch is characterized in that in normal work, Vin + and Vin-input weak current passes through self-recovery fuses F1 and F2 and a voltage dependent resistor R1, the current and voltage are in the normal working range of a device, and the device is protected from action, so that the weak current is accessed to the bathroom heater switch after passing through a rectifier bridge stack BD. Due to the effect of the rectifier bridge stack BD, the directions of the power supply voltages connected into the bathroom heater switch are kept consistent.

When the zero live wire is connected with Vin + and Vin-and is connected with the mains supply, the piezoresistor R1 acts rapidly, the resistance value is changed from infinity to be close to infinity within ns-level time, the current flowing through the self-recovery fuse F1 and the current flowing through the self-recovery fuse F2 are increased rapidly, and the self-recovery fuse element enters a high-resistance protection state, which is equivalent to an open circuit state, so that the mains supply is not connected with the bathroom heater switch.

According to the description of the present invention and the accompanying drawings, those skilled in the art can easily manufacture or use the access protection circuit for the two-wire system bathroom heater switch of the present invention and can produce the positive effects described in the present invention.

Unless otherwise specified, in the present invention, if there is an orientation or positional relationship indicated by terms of "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, rather than to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore, the terms describing orientation or positional relationship in the present invention are for illustrative purposes only, and should not be construed as limiting the present patent, specific meanings of the above terms can be understood by those of ordinary skill in the art in light of the specific circumstances in conjunction with the accompanying drawings.

Unless expressly stated or limited otherwise, the terms "disposed," "connected," and "connected" are to be construed broadly and encompass, for example, being fixedly connected, detachably connected, or integrally connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all simple modifications and equivalent variations of the above embodiments according to the technical spirit of the present invention are included in the scope of the present invention.

Claims

1. An access protection circuit for a two-wire system bathroom heater switch, characterized in that: the method comprises the following steps:

2. The access protection circuit for the two-wire bathroom heater switch of claim 1, wherein: the reverse connection prevention protection circuit is a rectifier bridge stack BD.

3. The access protection circuit for the two-wire bathroom heater switch of claim 2, wherein: the strong current prevention protection circuit comprises a first self-recovery fuse F1, a second self-recovery fuse F2 and a resistance element;

4. The access protection circuit for the two-wire bathroom heater switch of claim 1, wherein: the rectifier bridge stack BD comprises a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4;

5. The access protection circuit for the two-wire bathroom heater switch of claim 3, wherein: the resistance element is a voltage dependent resistor R1 or a bidirectional TVS diode D5.