Safety barrier circuit and explosion-proof system

Abstract

The utility model discloses a guard grating circuit and an explosion-proof system, the guard grating circuit comprises a first current limiting circuit, the first current limiting circuit comprises a first switch tube, the first end of the first switch tube is connected with the input end of the guard grating circuit, and the second end of the first switch tube is connected with the output end of the guard grating circuit; the output current of the safety barrier circuit is controlled; the current detection circuit is arranged between the input end and the output end of the safety barrier circuit so as to detect the output current of the safety barrier circuit; the current detection circuit is connected with the controlled end of the first switch tube, when the current detection circuit detects that the output current is smaller than a first current threshold value, the first switch tube is controlled to be in a conduction state, and when the current detection circuit detects that the output current is larger than a second current threshold value, the first switch tube is controlled to be in an amplification region state; the second current threshold is greater than or equal to the first current threshold. According to the invention, the loading capacity of the guard grating circuit is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of explosion-proof systems, in particular to a safety barrier circuit and an explosion-proof system. Background Art

[0002] According to the two explosion-proof standards GB / T 3836.1-2021 and GB / T 3836.4-2021, in the intrinsically safe explosion-proof system, the lines that supply power or signals from the safe area to the hazardous area need to limit the voltage and current applied to the intrinsically safe circuit through a safety barrier to achieve the purpose of intrinsic safety.

[0003] Conventional current limiting uses power resistors, but when the resistor limits the current, a large voltage drop will be generated. In this solution, when the maximum current allowed by the standard is reached, the voltage output by the safety barrier is 0V. Therefore, the solution of using resistor current limiting will cause the power supply voltage or signal voltage reaching the intrinsically safe product to be low, which cannot meet the normal working voltage requirements of the intrinsically safe product. Utility Model Content

[0004] The main purpose of the utility model is to provide a safety barrier circuit and an explosion-proof system, aiming to solve the problem of how to improve the load carrying capacity of the safety barrier circuit.

[0005] The present application provides a safety barrier circuit, the safety barrier circuit comprising a first current limiting circuit, the first current limiting circuit comprising:

[0006] A first switch tube, wherein a first end of the first switch tube is connected to an input end of the safety gate circuit, and a second end of the first switch tube is connected to an output end of the safety gate circuit to control an output current of the safety gate circuit;

[0007] A current detection circuit, wherein the current detection circuit is arranged between the input end and the output end of the safety gate circuit to detect the output current of the safety gate circuit; the current detection circuit is connected to the controlled end of the first switch tube, and when the current detection circuit detects that the output current is less than a first current threshold, the first switch tube is controlled to be in an on state, and when the current detection circuit detects that the output current is greater than a second current threshold, the first switch tube is controlled to be in an amplification zone state; the second current threshold is greater than or equal to the first current threshold.

[0008] In one embodiment, the first switch tube is a power Darlington tube.

[0009] In one embodiment, the first current limiting circuit further includes:

[0010] A fast conduction circuit, wherein a first end of the fast conduction circuit is connected to a first end of the first switch tube, and a second end of the fast conduction circuit is connected to a controlled end of the first switch tube;

[0011] The controlled end of the fast conduction circuit is connected to the input end of the safety gate circuit, so that when the input end of the safety gate circuit receives an input current, the first end and the second end of the fast conduction circuit are connected to control the first switch tube to be quickly turned on.

[0012] In one embodiment, the fast conduction circuit includes: a first resistor, a second resistor and a second switch tube; wherein,

[0013] One end of the first resistor is connected to the first end of the second switch tube, the other end of the first resistor is connected to the second end of the second switch tube, a common end of the first resistor and the first end of the second switch tube is connected to the first end of the first switch tube, and a common end of the first resistor and the second end of the second switch tube is connected to the controlled end of the first switch tube;

[0014] One end of the second resistor is connected to the input end of the safety gate circuit, and the other end of the second resistor is connected to the controlled end of the second switch tube.

[0015] In one embodiment, the safety gate circuit further includes:

[0016] A second current limiting circuit, wherein the second current limiting circuit and the first current limiting circuit are arranged in series between the input end and the output end of the safety gate circuit; the second current limiting circuit and the first current limiting circuit serve as backup current limiting protection for each other.

[0017] In one embodiment, the safety gate circuit further includes:

[0018] A first voltage limiting circuit, wherein a first end of the first voltage limiting circuit is connected to an input end of the safety gate circuit, and a second end of the first voltage limiting circuit is grounded.

[0019] In one embodiment, the safety gate circuit further includes:

[0020] A second voltage limiting circuit, wherein a first end of the second voltage limiting circuit is connected to an input end of the safety gate circuit, and a second end of the second voltage limiting circuit is grounded; the second voltage limiting circuit and the first voltage limiting circuit serve as backup voltage limiting protection for each other.

[0021] In one embodiment, the first voltage limiting circuit includes:

[0022] A voltage stabilizing diode, wherein a cathode of the voltage stabilizing diode is connected to an input end of the safety gate circuit, and an anode of the voltage stabilizing diode is grounded.

[0023] In one embodiment, the safety gate circuit further includes:

[0024] A fuse circuit, one end of which is connected to the input end of the safety gate circuit, and the other end of which is connected to the input end of the first current limiting circuit; when the output current is greater than a third current threshold, the fuse circuit is blown; wherein the third current threshold is greater than or equal to the second current threshold.

[0025] The present application also proposes an explosion-proof system, which includes the above-mentioned safety barrier circuit.

[0026] The safety gate circuit of the present application is provided with a first current limiting circuit, and the first current limiting circuit includes a first switch tube provided between the input end and the output end of the safety gate circuit. When the output current of the safety gate circuit is less than the first current threshold, the first current limiting circuit controls the first switch tube to be in an on state, thereby reducing the output impedance of the safety gate circuit; when the current is greater than the second current threshold, the internal first switch tube is in an amplified state, limiting the output current, so that the output current is within the limit value. In the present application, the second current threshold is greater than or equal to the first current threshold. Taking the equality of the two as an example, the first current threshold can be the current range required by the standard. In this way, the present application produces an extremely low voltage drop within the current range required by the standard, thereby increasing the number of loads of intrinsically safe products within the maximum allowable current range. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 This is a schematic diagram of an application scenario of an embodiment of a safety barrier circuit of the utility model;

[0029] Figure 2 This is a circuit block diagram of an embodiment of a safety barrier circuit of the utility model;

[0030] Figure 3 This is a circuit diagram of an embodiment of a safety barrier circuit of the present utility model.

[0031] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] In addition, in the present utility model, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0034] Reference Figure 1 , the lines that supply power or signals from the safe area to the hazardous area need to limit the voltage and current applied to the intrinsically safe circuit through a safety barrier to achieve the purpose of intrinsic safety.

[0035] In one application scenario, the safety barrier circuit is applied to fire fighting equipment, the safety zone may include a fire fighting controller 10 and a safety barrier 20; the danger zone may include a plurality of intrinsically safe products 31-33, and illustratively, the intrinsically safe products 31-33 may refer to intrinsically safe detectors.

[0036] Regarding how to reduce the impedance of the safety barrier so that the equipment using the safety barrier can carry more intrinsically safe products, refer to Figure 2 In one embodiment, the safety gate circuit inside the safety gate 20 of the present application includes a first current limiting circuit 21, and the first current limiting circuit 21 includes:

[0037] A first switch tube Q1, wherein a first end of the first switch tube Q1 is connected to an input end of the safety gate circuit, and a second end of the first switch tube Q1 is connected to an output end of the safety gate circuit to control an output current of the safety gate circuit;

[0038] A current detection circuit, the current detection circuit is arranged between the input end and the output end of the safety gate circuit to detect the output current of the safety gate circuit; the current detection circuit is connected to the controlled end of the first switch tube Q1, and when the current detection circuit detects that the output current is less than a first current threshold, the first switch tube Q1 is controlled to be in a conducting state, and when the current detection circuit detects that the output current is greater than a second current threshold, the first switch tube Q1 is controlled to be in an amplification zone state; the second current threshold is greater than or equal to the first current threshold. Exemplarily, the second current threshold is equal to the first current threshold, which serves as a limiting value of the output current.

[0039] Reference Figure 3 In this embodiment, the first switch tube Q1 can be a triode, a MOS tube or other transistors with two states of conduction and amplification.

[0040] In this embodiment, the current detection circuit can be implemented using a current detection chip, an operational amplifier chip, or a transistor and a resistor. Figure 3 As shown, the first switch tube Q1 is an NPN type switch tube, and the third switch tube Q3 and the third resistor form a current detection circuit. When the output result (current) of the current detection circuit is less than the current threshold (the first current threshold), the output result (current) controls the output current of the first switch tube Q1, and when the output result (current) of the current detection circuit is greater than the current threshold (the second current threshold), the first switch tube Q1 is in an amplification state, and the output result (current) controls the output current of the first switch tube Q1 to limit the output current of the first switch tube Q1.

[0041] The safety gate circuit of the present application is provided with a first current limiting circuit 21, and the first current limiting circuit 21 includes a first switch tube Q1 provided between the input end and the output end of the safety gate circuit. When the output current of the safety gate circuit is less than the first current threshold, the first current limiting circuit 21 controls the first switch tube Q1 to be in an on state, thereby reducing the output impedance of the safety gate circuit; when the current is greater than the second current threshold, the internal first switch tube is in an amplified state, limiting the output current, so that the output current is within the limit value. In the present application, the second current threshold is greater than or equal to the first current threshold. Taking the equality of the two as an example, the first current threshold can be the current range required by the standard. In this way, the present application uses electronic current limiting technology to produce an extremely low voltage drop within the current range required by the standard, thereby increasing the number of loads of intrinsically safe products within the maximum allowable current range.

[0042] Reference Figure 3 In one embodiment, the first switch tube Q1 may be a power Darlington tube, and for example, may be an NPN Darlington tube. Using a power Darlington tube can increase the amplification factor.

[0043] In this embodiment, since the junction capacitance of the control end of the power Darlington transistor is large, in order to realize the rapid opening of the first switch tube Q1 (power Darlington transistor), the first current limiting circuit 21 of this embodiment further includes: a fast conduction circuit, wherein the first end of the fast conduction circuit is connected to the first end of the first switch tube Q1, and the second end of the fast conduction circuit is connected to the controlled end of the first switch tube Q1;

[0044] The controlled end of the fast conduction circuit is connected to the input end of the safety gate circuit, so that when the input end of the safety gate circuit receives an input current, the first end and the second end of the fast conduction circuit are connected to control the first switch tube Q1 to be turned on quickly.

[0045] In this embodiment, the fast conduction circuit can quickly lower the voltage of the controlled terminal of the first switch tube Q1 (power Darlington tube), quickly discharge the charge of the junction capacitor, and realize the fast conduction of the first switch tube Q1. Figure 3 In one embodiment, the fast conduction circuit includes: a first resistor R1, a second resistor R2 and a second switch tube Q2; wherein, one end of the first resistor R1 is connected to the first end of the second switch tube Q2, the other end of the first resistor R1 is connected to the second end of the second switch tube Q2, the common end of the first resistor R1 and the first end of the second switch tube Q2 is connected to the first end of the first switch tube Q1, and the common end of the first resistor R1 and the second end of the second switch tube Q2 is connected to the controlled end of the first switch tube Q1; one end of the second resistor R2 is connected to the input end of the safety gate circuit, and the other end of the second resistor R2 is connected to the controlled end of the second switch tube Q2.

[0046] In this embodiment, the first resistor R1 is arranged between the first end and the controlled end of the first switch tube Q1. However, due to the large junction capacitance of the control end of the first switch tube Q1 (power Darlington tube), the first resistor R1 is insufficient to quickly turn on the first switch tube Q1 (power Darlington tube). In this embodiment, the fast conduction circuit adds a second switch tube Q2. When the input end of the safety gate circuit receives a signal / current, the second switch tube Q2 is quickly turned on, thereby bypassing the first resistor R1, and realizing the fast turn-on of the first switch tube Q1 (power Darlington tube).

[0047] Reference Figure 2 and Figure 3 In order to further improve the safety of the safety gate circuit, in one embodiment, the safety gate circuit further includes:

[0048] The second current limiting circuit 22 is arranged in series with the first current limiting circuit 21 between the input end and the output end of the safety gate circuit; the second current limiting circuit 22 and the first current limiting circuit 21 serve as backup current limiting protection for each other. When one of them fails, the other can still perform current limiting protection, thereby improving the safety of the safety gate circuit.

[0049] The structure of the second current limiting circuit 22 can be the same as or different from that of the first current limiting circuit 21, as long as current limiting is achieved. In this embodiment, the structure of the second current limiting circuit 22 can be the same as that of the first current limiting circuit 21. The specific working principle and structure can refer to the first current limiting circuit 21, which will not be repeated here.

[0050] In this embodiment, the first current limiting circuit 21 and the second current limiting circuit 22 serve as backup for each other, thereby improving the safety of the safety barrier circuit.

[0051] Reference Figure 2 and Figure 3 In order to further improve the safety of the safety gate circuit, in one embodiment, the safety gate circuit further includes:

[0052] A first voltage limiting circuit 23, wherein a first end of the first voltage limiting circuit 23 is connected to an input end of the safety gate circuit, and a second end of the first voltage limiting circuit 23 is grounded;

[0053] A second voltage limiting circuit 24, wherein a first end of the second voltage limiting circuit 24 is connected to an input end of the safety gate circuit, and a second end of the second voltage limiting circuit 24 is grounded;

[0054] The second voltage limiting circuit 24 and the first voltage limiting circuit 23 serve as backup voltage limiting protection for each other. When one of them fails, the other can still perform voltage limiting protection, thereby improving the safety of the safety barrier circuit.

[0055] In this embodiment, the first voltage limiting circuit 23 can be implemented using a voltage stabilizing diode, such as Figure 3 As shown, the first voltage limiting circuit 23 includes a first voltage stabilizing diode D1 to achieve voltage stabilization of the positive input terminal IN+; and a second voltage stabilizing diode D2 to achieve voltage stabilization of the negative input terminal IN-. The second voltage limiting circuit 24 may also include a third voltage stabilizing diode D3, which together with the first voltage stabilizing diode D1, achieves backup voltage limiting protection for the positive input terminal IN+, thereby improving the safety of the safety gate circuit.

[0056] In this embodiment, the voltage regulator diode may be a Zener diode.

[0057] Reference Figure 3 In one embodiment, the safety gate circuit further includes:

[0058] A fuse circuit 25, one end of which is connected to the input end of the safety gate circuit, and the other end of which is connected to the input end of the first current limiting circuit 21; when the output current is greater than a third current threshold, the fuse circuit 25 is blown; wherein the third current threshold is greater than or equal to the second current threshold.

[0059] In this embodiment, the fuse circuit 25 includes a first fuse and a fourth resistor, which are arranged in series between the first end of the first switch tube Q1 and the positive input terminal IN+ of the safety gate circuit. In this way, when the first voltage regulator diode D1 of the first voltage limiting circuit 23 fails due to short circuit, the first fuse can be blown, thereby achieving a protective effect.

[0060] Similarly, the fuse circuit 25 includes a second fuse and a fifth resistor, which are arranged at the negative input terminal IN- of the safety gate circuit. In this way, when the second voltage regulator diode D2 of the first voltage limiting circuit 23 fails due to short circuit, the second fuse can be blown, thereby achieving a protective effect.

[0061] In addition, in this embodiment, since the breaking capacity of the first fuse and the second fuse cannot meet the target requirement (for example, 1500A), adding the fourth resistor and the fifth resistor can effectively reduce the breaking capacity parameters of the fuse circuit 25.

[0062] Reference Figure 2 and Figure 3 In one embodiment, the safety barrier circuit further includes:

[0063] The anti-reverse circuit 26 includes two fourth diodes D4 connected in series in the loop. When the input power or signal is reversely connected, the two fourth diodes D4 play a reverse cutoff role, thereby improving the safety of the circuit.

[0064] The present application also proposes an explosion-proof system, which includes the above-mentioned safety barrier circuit. Since the explosion-proof system includes the above-mentioned safety barrier circuit, it has the technical effects of the above-mentioned embodiments.

[0065] The above description is only an optional embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A safety barrier circuit, characterized in that: The safety gate circuit includes a first current limiting circuit, and the first current limiting circuit includes: A first switch tube, wherein a first end of the first switch tube is connected to an input end of the safety gate circuit, and a second end of the first switch tube is connected to an output end of the safety gate circuit to control an output current of the safety gate circuit; A current detection circuit, wherein the current detection circuit is arranged between the input end and the output end of the safety gate circuit to detect the output current of the safety gate circuit; the current detection circuit is connected to the controlled end of the first switch tube, and when the current detection circuit detects that the output current is less than a first current threshold, the first switch tube is controlled to be in an on state, and when the current detection circuit detects that the output current is greater than a second current threshold, the first switch tube is controlled to be in an amplification zone state; the second current threshold is greater than or equal to the first current threshold.

2. The safety gate circuit according to claim 1, characterized in that: The first switch tube is a power Darlington tube.

3. The safety gate circuit according to claim 2, characterized in that: The first current limiting circuit further includes: A fast conduction circuit, wherein a first end of the fast conduction circuit is connected to a first end of the first switch tube, and a second end of the fast conduction circuit is connected to a controlled end of the first switch tube; The controlled end of the fast conduction circuit is connected to the input end of the safety gate circuit, so that when the input end of the safety gate circuit receives an input current, the first end and the second end of the fast conduction circuit are connected to control the first switch tube to be turned on quickly.

4. The safety gate circuit according to claim 3, characterized in that: The fast conduction circuit comprises: a first resistor, a second resistor and a second switch tube; wherein, One end of the first resistor is connected to the first end of the second switch tube, the other end of the first resistor is connected to the second end of the second switch tube, a common end of the first resistor and the first end of the second switch tube is connected to the first end of the first switch tube, and a common end of the first resistor and the second end of the second switch tube is connected to the controlled end of the first switch tube; One end of the second resistor is connected to the input end of the safety gate circuit, and the other end of the second resistor is connected to the controlled end of the second switch tube.

5. The safety gate circuit according to claim 1, characterized in that: Also includes: The second current limiting circuit is connected in series with the first current limiting circuit and is arranged between the input end and the output end of the safety gate circuit. The second current limiting circuit and the first current limiting circuit serve as backup current limiting protection for each other.

6. The safety gate circuit according to any one of claims 1 to 5, characterized in that: Also includes: A first voltage limiting circuit, wherein a first end of the first voltage limiting circuit is connected to an input end of the safety gate circuit, and a second end of the first voltage limiting circuit is grounded.

7. The safety gate circuit according to claim 6, characterized in that: Also includes: A second voltage limiting circuit, wherein a first end of the second voltage limiting circuit is connected to an input end of the safety gate circuit, a second end of the second voltage limiting circuit is grounded, and the second voltage limiting circuit and the first voltage limiting circuit serve as backup voltage limiting protection for each other.

8. The safety gate circuit according to claim 6, characterized in that: The first voltage limiting circuit comprises: A voltage stabilizing diode, wherein a cathode of the voltage stabilizing diode is connected to an input end of the safety gate circuit, and an anode of the voltage stabilizing diode is grounded.

9. The safety gate circuit according to claim 1, characterized in that: Also includes: a fuse circuit, one end of which is connected to the input end of the safety barrier circuit, and the other end of which is connected to the input end of the first current limiting circuit; When the output current is greater than a third current threshold, the fuse circuit is blown; wherein the third current threshold is greater than or equal to the second current threshold.

10. An explosion-proof system, characterized in that: Comprising the safety barrier circuit as described in any one of claims 1-9.

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