Composite flame detector capable of realizing adaptive variable gain

Abstract

The utility model relates to a composite flame detector capable of realizing adaptive variable gain, which comprises three infrared pyroelectric sensors, a variable gain amplification circuit, an ultraviolet photoelectric sensor, an ultraviolet control and feedback circuit, an MCU (Microprogrammed Control Unit) control module, a power supply module and a relay output module, the output end of each infrared pyroelectric sensor is connected with the variable gain amplification circuit, the output end of the variable gain amplification circuit is connected with the MCU control module, the output end of the MCU control module is connected with the relay output module, the ultraviolet control and feedback circuit is connected with the MCU control module, the ultraviolet photoelectric sensor is connected with the ultraviolet control and feedback circuit, and the relay output module is connected with the relay output module. And the output end of the power supply module is connected with the infrared pyroelectric sensor, the variable gain amplification circuit, the MCU control module and the relay output module. By adopting the composite flame detector capable of realizing the self-adaptive variable gain, the gain parameter can be adjusted through the MCU to adapt to the field environment, the detection distance is increased, and the anti-interference capability can also be improved at the same time.

Description

Technical Field

[0001] This utility model relates to the field of early fire detection equipment, and more particularly to the field of point flame detectors, specifically referring to a composite flame detector that achieves adaptive variable gain. Background Technology

[0002] Point-type flame detectors are widely used in various industrial sites and are one of the most effective early-stage fire detection devices in many hazardous locations. They are widely used in important fields such as large oil tank farms, coal mines, ships, petrochemical plants, and offshore oil platforms. In particular, the ultraviolet-infrared composite flame detector, by detecting the infrared and ultraviolet light generated in a burning flame, can accurately and quickly identify the fire situation on site and issue an alarm. This allows relevant safety personnel to take appropriate fire-fighting measures and evacuate personnel as quickly as possible. Ultraviolet-infrared composite flame detectors play a very important role in public safety and economic development, and therefore, they have become a popular research product in today's society.

[0003] In a violet-infrared composite flame detector, the crucial components are the infrared pyroelectric and ultraviolet photoelectric sensors, used to detect the infrared and ultraviolet spectra of open flames; these are indispensable components. The amplification circuit of the infrared sensor is a key circuit affecting the detection performance of the flame detector. However, traditional fixed-gain amplification circuits suffer from the following problems:

[0004] 1. When a flame detector detects a small fire in its early stages at a distance, the output signal of the infrared pyroelectric sensor is very small, requiring a large amplification circuit gain to ensure the detection and identification of the small signal.

[0005] 2. In the event of a near-field deflagration, the large infrared signal from a flame detector, especially under high gain conditions, can easily lead to saturation distortion of the processed infrared signal. Similarly, infrared pyroelectric sensors are also prone to generating large saturation distortion signals when subjected to interference from sunlight, radio frequency signals, and high-temperature objects. This makes it difficult to distinguish between interference signals and near-field deflagration signals.

[0006] 3. Traditional gain amplifier circuits cannot simultaneously meet the anti-interference requirements of long-distance small fire detectors and short-distance large fire detectors. Utility Model Content

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite flame detector that achieves adaptive variable gain, which has good integrity, strong anti-interference ability, and wide applicability.

[0008] To achieve the above objectives, the present invention provides an adaptive variable gain composite flame detector as follows:

[0009] The main features of this adaptive variable gain composite flame detector are that the detector includes three infrared pyroelectric sensors, a variable gain amplifier circuit, an ultraviolet photoelectric sensor, an ultraviolet control and feedback circuit, an MCU control module, a power supply module, and a relay output module. The output terminal of each infrared pyroelectric sensor is connected to the variable gain amplifier circuit, the output terminal of the variable gain amplifier circuit is connected to the MCU control module, the output terminal of the MCU control module is connected to the relay output module, the ultraviolet control and feedback circuit is connected to the MCU control module, the ultraviolet photoelectric sensor is connected to the ultraviolet control and feedback circuit, and the output terminal of the power supply module is connected to the infrared pyroelectric sensor, the variable gain amplifier circuit, the MCU control module, and the relay output module.

[0010] Preferably, the three infrared pyroelectric sensors are infrared sensors with wavelengths of 4.3μm, 2.7μm, and 5.0μm, respectively.

[0011] Preferably, the variable gain amplifier circuit includes an LMP7731 low-noise precision amplifier and its peripheral circuits, and an LTC6910 digitally controlled programmable gain amplifier and its peripheral circuits. The input terminal of the LMP7731 low-noise precision amplifier and its peripheral circuits is connected to an infrared pyroelectric sensor, and the output terminal of the LMP7731 low-noise precision amplifier and its peripheral circuits is connected to the LTC6910 digitally controlled programmable gain amplifier and its peripheral circuits. The G0, G1, and G2 pins of the LTC6910 digitally controlled programmable gain amplifier are connected to the MCU control module.

[0012] Preferably, the MCU control module includes a GD32F303CCT6 microcontroller, which is connected to a variable gain amplifier circuit and an ultraviolet control and feedback circuit.

[0013] Preferably, the ultraviolet control and feedback circuit includes an ultraviolet photoelectric sensor UV1, a transistor switch Q1, a transformer T1, a first diode D1, a third diode D3, a third resistor R3, a second resistor R2, a first resistor R1, a fourteenth capacitor C14, a fourth capacitor C4.1, and a fifth capacitor C5.1. The base of the transistor switch Q1 is connected to the input drive UV_C, the emitter is grounded, and the collector is connected to the transformer T1. The anode of the first diode D1 is connected to the collector of the transistor switch Q1, the cathode of the first diode D1 is connected to the power supply, and the anode of the third diode D3 is connected to the transformer T1. The negative terminal of the third diode D3 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the ultraviolet photoelectric sensor UV1. One end of the second resistor R2 is connected to the ultraviolet photoelectric sensor UV1, and the other end outputs a pulse signal UV_O. One end of the first resistor R1 is connected to the ultraviolet photoelectric sensor UV1, and the other end of the first resistor R1 is grounded. The two ends of the fourteenth capacitor C14 are respectively connected to the two ends of the first resistor R1. One end of the fourth capacitor C4.1 is connected to the negative terminal of the third diode D3, and the other end is grounded. One end of the fifth capacitor C5.1 is connected to the second resistor R2, and the other end is grounded.

[0014] This invention utilizes a composite flame detector with adaptive variable gain, solving the problem that infrared sensors, when operating at fixed gain, cannot simultaneously achieve both high detection range and strong anti-interference capability. When the detector is at high gain, it can effectively extract subtle changes in the infrared sensor signal, increasing the alarm range. However, under high gain, encountering large fire signals or strong light / magnetic interference signals can cause the amplified infrared signal to overflow, preventing accurate extraction of infrared characteristic signals. Conversely, when the detector is at low gain, its detection performance decreases, although it still offers high anti-interference capability. Therefore, fixed-gain circuits cannot avoid these shortcomings. In contrast, the variable-gain amplifier circuit, through MCU adjustment of the gain parameters, adapts to the field environment, increasing both detection range and anti-interference capability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the composite flame detector that realizes adaptive variable gain according to this utility model.

[0016] Figure 2 This is a schematic diagram of the variable gain amplifier circuit for realizing the adaptive variable gain composite flame detector of this utility model.

[0017] Figure 3 This is a schematic diagram of the ultraviolet control and feedback circuit of the composite flame detector with adaptive variable gain according to this utility model.

[0018] Figure 4 This is a flowchart illustrating the process of implementing the adaptive variable gain composite flame detector of this invention. Detailed Implementation

[0019] To more clearly describe the technical content of this utility model, the following description is provided in conjunction with specific embodiments.

[0020] This invention discloses an adaptive variable gain composite flame detector, comprising three infrared pyroelectric sensors 101, a variable gain amplifier circuit 102, an ultraviolet photoelectric sensor 103, an ultraviolet control and feedback circuit 104, an MCU control module 105, a power supply module 106, and a relay output module 107. The output of each infrared pyroelectric sensor is connected to the variable gain amplifier circuit, the output of the variable gain amplifier circuit is connected to the MCU control module, the output of the MCU control module is connected to the relay output module, the ultraviolet control and feedback circuit is connected to the MCU control module, the ultraviolet photoelectric sensor is connected to the ultraviolet control and feedback circuit, and the output of the power supply module is connected to the infrared pyroelectric sensor, the variable gain amplifier circuit, the MCU control module, and the relay output module.

[0021] In a preferred embodiment of this utility model, the three infrared pyroelectric sensors are infrared sensors with wavelengths of 4.3μm, 2.7μm, and 5.0μm, respectively.

[0022] In a preferred embodiment of this utility model, the variable gain amplifier circuit includes an LMP7731 low-noise precision amplifier and its peripheral circuits, and an LTC6910 digitally controlled programmable gain amplifier and its peripheral circuits. The input terminal of the LMP7731 low-noise precision amplifier and its peripheral circuits is connected to an infrared pyroelectric sensor, and the output terminal of the LMP7731 low-noise precision amplifier and its peripheral circuits is connected to the LTC6910 digitally controlled programmable gain amplifier and its peripheral circuits. The G0, G1, and G2 pins of the LTC6910 digitally controlled programmable gain amplifier are connected to the MCU control module.

[0023] In a preferred embodiment of this utility model, the MCU control module includes a GD32F303CCT6 microcontroller, which is connected to a variable gain amplifier circuit and an ultraviolet control and feedback circuit.

[0024] In a preferred embodiment of this utility model, the ultraviolet control and feedback circuit includes an ultraviolet photoelectric sensor UV1, a transistor switch Q1, a transformer T1, a first diode D1, a third diode D3, a third resistor R3, a second resistor R2, a first resistor R1, a fourteenth capacitor C14, a fourth capacitor C4.1, and a fifth capacitor C5.1. The base of the transistor switch Q1 is connected to the input drive UV_C, the emitter is grounded, and the collector is connected to the transformer T1. The anode of the first diode D1 is connected to the collector of the transistor switch Q1, and the cathode of the first diode D1 is connected to the power supply. The anode of the third diode D3 is connected to the transformer T1. The circuit is connected to T1. The cathode of the third diode D3 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the ultraviolet photoelectric sensor UV1. One end of the second resistor R2 is connected to the ultraviolet photoelectric sensor UV1, and the other end outputs a pulse signal UV_O. One end of the first resistor R1 is connected to the ultraviolet photoelectric sensor UV1, and the other end of the first resistor R1 is grounded. The two ends of the fourteenth capacitor C14 are respectively connected to the two ends of the first resistor R1. One end of the fourth capacitor C4.1 is connected to the cathode of the third diode D3, and the other end is grounded. One end of the fifth capacitor C5.1 is connected to the second resistor R2, and the other end is grounded.

[0025] In a specific embodiment of this invention, an adaptive variable gain amplifier circuit is provided. Under interference-free conditions, the detector automatically adjusts to a high gain to enhance the flame detection capability of the flame detector, thus meeting the detection performance requirements for early-stage small fires. Under interference or near-field deflagration / ignition conditions, the detector automatically adjusts to a low gain to ensure the integrity of the signal characteristics and improve the detector's anti-interference capability.

[0026] as follows Figure 1 As shown, the adaptive variable gain composite flame detector mainly consists of: three infrared pyroelectric sensors 101, a variable gain amplifier circuit 102, an ultraviolet photoelectric sensor 103, an ultraviolet control and feedback circuit 104, an MCU control module 105, a power supply module 106, and a relay output module 107.

[0027] The three-channel infrared pyroelectric sensor 101 uses three infrared sensors in different wavelength bands: 4.3μm, 2.7μm, and 5.0μm. The 4.3μm and 2.7μm sensors are mainly used for flame infrared spectroscopy detection, detecting the infrared spectra of CO2 and H2O produced after the combustion of hydrocarbon flames. The 5.0μm sensor is used to eliminate infrared interference from other types of fires.

[0028] Variable gain amplifier circuit 102, such as Figure 2The variable gain amplifier circuit 102 consists of an LMP7731 low-noise precision amplifier and an LTC6910 digitally controlled programmable gain amplifier. The LMP7731 performs the first stage of low-gain amplification and bandpass filtering modulation of the infrared sensor signal. The second stage uses the digitally controlled LTC6910 programmable gain amplifier, whose gain can be controlled via pins G0, G1, and G2, with selectable gain values ​​of 0, 1, 2, 5, 10, 20, 50, and 100 (7 levels in total). The bandpass filtering inverting amplifier circuit, composed of the LMP7732 low-noise precision amplifier and resistors and capacitors, has a gain of 10x and a bandpass frequency of 0.33–33 Hz.

[0029] The ultraviolet photoelectric sensor 103 and the ultraviolet control and feedback circuit 104 are assembled from an ultraviolet phototube R2868, an ultraviolet high-voltage drive circuit, and an ultraviolet signal feedback circuit, such as... Figure 3 As shown.

[0030] Figure 3 It includes an R2868 ultraviolet photoelectric sensor UV1, with a 1kHz pulse wave as the input driver UV_C. By controlling the FZT853 switch Q1, the 70:1 transformer T1 outputs a 350V pulse high voltage to drive the ultraviolet phototube. When the ultraviolet phototube receives ultraviolet light of 180-265nm, the ultraviolet phototube is turned on and outputs a pulse signal UV_O.

[0031] The MCU control module uses a GD32F303CCT6 microcontroller, which automatically adjusts the parameters of the variable gain amplifier circuit by analyzing the analog signals from three infrared signal sensors and the feedback signals from the ultraviolet photoelectric sensor to achieve the best signal-to-noise ratio and avoid the problem of high-gain analog signal overflow. Simultaneously, the MCU uses a flame recognition algorithm based on the acquired infrared and ultraviolet signals to determine whether a flame is present and outputs an alarm signal. The software flowchart is shown below. Figure 4 .

[0032] The power supply module 106 provides power to all modules, and the relay module 107 outputs switch alarm signals based on the data analysis results of the MCU.

[0033] This invention improves the infrared amplification circuit into a variable gain amplification circuit, and the detector itself can adjust the gain amplification factor of the infrared sensor through MCU control.

[0034] The detector uses an adaptive software algorithm to analyze the real-time infrared signal value of each channel and, combined with the pulse count fed back by the ultraviolet photoelectric sensor, can automatically adjust the gain of the infrared sensor to adapt to the field environment.

[0035] For the specific implementation scheme of this embodiment, please refer to the relevant descriptions in the above embodiments, which will not be repeated here.

[0036] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0037] It should be noted that in the description of this utility model, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this utility model, unless otherwise stated, "a plurality of" means at least two.

[0038] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] This invention utilizes a composite flame detector with adaptive variable gain, solving the problem that infrared sensors, when operating at fixed gain, cannot simultaneously achieve both high detection range and strong anti-interference capability. When the detector is at high gain, it can effectively extract subtle changes in the infrared sensor signal, increasing the alarm range. However, under high gain, encountering large fire signals or strong light / magnetic interference signals can cause the amplified infrared signal to overflow, preventing accurate extraction of infrared characteristic signals. Conversely, when the detector is at low gain, its detection performance decreases, although it still offers high anti-interference capability. Therefore, fixed-gain circuits cannot avoid these shortcomings. In contrast, the variable-gain amplifier circuit, through MCU adjustment of the gain parameters, adapts to the field environment, increasing both detection range and anti-interference capability.

[0040] In this specification, the present invention has been described with reference to specific embodiments thereof. However, it will be apparent that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the specification and drawings should be considered illustrative rather than restrictive.

Claims

1. A compound flame detector implementing adaptive variable gain, characterized by, The detector includes three infrared pyroelectric sensors, a variable gain amplifier circuit, an ultraviolet photoelectric sensor, an ultraviolet control and feedback circuit, an MCU control module, a power supply module, and a relay output module. The output terminal of each infrared pyroelectric sensor is connected to the variable gain amplifier circuit, the output terminal of the variable gain amplifier circuit is connected to the MCU control module, the output terminal of the MCU control module is connected to the relay output module, the ultraviolet control and feedback circuit is connected to the MCU control module, the ultraviolet photoelectric sensor is connected to the ultraviolet control and feedback circuit, and the output terminal of the power supply module is connected to the infrared pyroelectric sensor, the variable gain amplifier circuit, the MCU control module, and the relay output module.

2. The compound flame detector implementing adaptive variable gain according to claim 1, wherein, The three infrared pyroelectric sensors are infrared sensors with wavelengths of 4.3μm, 2.7μm, and 5.0μm, respectively.

3. The compound flame detector implementing adaptive variable gain according to claim 1, wherein, The variable gain amplifier circuit includes an LMP7731 low-noise precision amplifier and its peripheral circuits, and an LTC6910 digitally controlled programmable gain amplifier and its peripheral circuits. The input terminal of the LMP7731 low-noise precision amplifier and its peripheral circuits is connected to an infrared pyroelectric sensor, and the output terminal of the LMP7731 low-noise precision amplifier and its peripheral circuits is connected to the LTC6910 digitally controlled programmable gain amplifier and its peripheral circuits. The G0, G1, and G2 pins of the LTC6910 digitally controlled programmable gain amplifier are connected to the MCU control module.

4. The composite flame detector with adaptive variable gain according to claim 1, characterized in that, The MCU control module includes a GD32F303CCT6 microcontroller, which is connected to a variable gain amplifier circuit and an ultraviolet control and feedback circuit.

5. The compound flame detector that implements adaptive variable gain according to claim 1, wherein, The ultraviolet control and feedback circuit includes an ultraviolet photoelectric sensor UV1, a transistor switch Q1, a transformer T1, a first diode D1, a third diode D3, a third resistor R3, a second resistor R2, a first resistor R1, a fourteenth capacitor C14, a fourth capacitor C4.1, and a fifth capacitor C5.

1. The base of the transistor switch Q1 is connected to the input drive UV_C, the emitter is grounded, and the collector is connected to the transformer T1. The anode of the first diode D1 is connected to the collector of the transistor switch Q1, and the cathode of the first diode D1 is connected to the power supply. The anode of the third diode D3 is connected to the transformer T1. The negative terminal of diode D3 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the ultraviolet photoelectric sensor UV1. One end of the second resistor R2 is connected to the ultraviolet photoelectric sensor UV1, and the other end outputs a pulse signal UV_O. One end of the first resistor R1 is connected to the ultraviolet photoelectric sensor UV1, and the other end of the first resistor R1 is grounded. The two ends of the fourteenth capacitor C14 are respectively connected to the two ends of the first resistor R1. One end of the fourth capacitor C4.1 is connected to the negative terminal of the third diode D3, and the other end is grounded. One end of the fifth capacitor C5.1 is connected to the second resistor R2, and the other end is grounded.

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