A smoke concentration detection system for cargo hold of civil aircraft based on polarized light

Abstract

The present invention discloses a smoke concentration detection system for a cargo hold of a civil aircraft based on polarized light. It includes an adjustable light emitting module, an adjustable polarized light receiving module, and a logic control and data processing module; the adjustable light emitting module is used to output infrared or blue light signals with variable intensity, which enter the adjustable polarized light receiving module after being scattered by smoke particles; the adjustable polarized light receiving module is used to convert the light signal into an electrical signal and then input it into the logic control and data processing module; the input logic control and data processing module is used to perform data processing on the electrical signal to judge smoke and interference, and at the same time adjust the amplification factor according to the signal intensity of the adjustable polarized light receiving module. The present invention has a wide detection concentration range, good detection concentration continuity, high adjustment accuracy, and reliable alarm.

Description

Technical Field

[0001] The invention belongs to the technical field of civil aircraft measurement and control, and in particular relates to a civil aircraft cargo hold smoke concentration detection system based on polarized light. Background Art

[0002] The high false alarm rate of aircraft cargo hold fires seriously affects civil aviation flight safety. At present, red and blue light dual-wavelength photoelectric smoke detectors are generally used to collect infrared and blue light signal intensities respectively for dual-parameter fitting fire detection and identify interfering particles, which greatly reduces the false alarm rate of the system; however, the smoke concentration range detected by the red and blue light dual-wavelength photoelectric smoke detector is generally between 80% and 100% / ft (light transmittance), and the detection range is narrow. The cargo hold environment is complex, and there are many types of stored goods. The smoke concentration generated by fires in high-altitude, low-pressure and sealed environments is large. When the smoke detector is contaminated or a large-scale fire with high-concentration smoke occurs, the high-concentration smoke can easily cause the smoke detector to be saturated. At this time, the red and blue light dual-wavelength photoelectric smoke detector will enter a single-wavelength working mode, and the system will lose the ability to identify interfering particles, resulting in an increase in the false alarm rate of the smoke concentration detection system. Summary of the invention

[0003] The purpose of the present invention is to provide a smoke concentration detection system for a cargo hold of a civil aircraft based on polarized light. The present invention has a wide detection concentration range, good detection concentration continuity, high adjustment accuracy, and reliable alarm.

[0004] The technical solution of the present invention is: a civil aircraft cargo hold smoke detector anti-false alarm system, including an adjustable light-emitting module, an adjustable polarization light-receiving module, and a logic control and data processing module; the adjustable light-emitting module is used to output infrared or blue light signals with variable intensity, which enter the adjustable polarization light-receiving module after being scattered by smoke particles; the adjustable polarization light-receiving module is used to convert the light signal into an electrical signal and input it into the logic control and data processing module; the input logic control and data processing module is used to perform data processing on the electrical signal to judge smoke and interference, and at the same time adjust the amplification factor according to the signal strength of the adjustable polarization light-receiving module.

[0005] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the adjustable polarized light receiving module includes a phototube L3 for receiving light, the output end of the phototube L3 is connected to the signal positive input end of the amplifier A1, and the output end of the amplifier A1 is connected to the logic control and data processing module; the output end of the amplifier A1 is also connected to the signal positive input end of the amplifier A2, and an adjustable resistor R1 is connected between the signal negative input end and the output end of the amplifier A2, and the adjustable resistor R1 is also connected to the logic control and data processing module, and the output end of the amplifier A2 is connected to the output end logic control and data processing module; the output end of the amplifier A2 is also connected to the signal positive input end of the amplifier A3, and an adjustable resistor R2 is connected between the signal negative input end and the output end of the amplifier A3, and the adjustable resistor R2 is also connected to the logic control and data processing module, and the output end of the amplifier A3 is also connected to the logic control and data processing module.

[0006] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the adjustable light-emitting module includes an infrared adjustment unit T1, a blue light adjustment unit T2, an infrared LED light-emitting tube L1 and a blue light LED light-emitting tube L2; the input end of the infrared adjustment unit T1 is connected to the logic control and data processing module, and the output end is connected to the infrared LED light-emitting tube L1; the input end of the blue light adjustment unit T2 is connected to the logic control and data processing module, and the output end is connected to the blue light LED light-emitting tube L2.

[0007] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the light brightness of the infrared LED light emitting tube L1 and the blue light LED light emitting tube L2 can be adjusted.

[0008] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the infrared adjustment unit T1 and the blue light adjustment unit T2 are both digital chips, which are used to adjust the luminous intensity of the infrared LED light-emitting tube L1 and the blue light LED light-emitting tube L2 respectively.

[0009] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the logic control and data processing module includes a central processor U1; the input signal of U1 includes feedback signal 1, feedback signal 2, and feedback signal 3 respectively from the output ends of amplifiers A1, A2, and A3; the output signal of U1 includes control signal 1, control signal 2, control signal 3, and control signal 4 which respectively control R1, R2, T1, and T2.

[0010] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, L3 is a photoelectric tube with a polarizer.

[0011] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the amplification factors of A2 and A3 are adjusted by corresponding adjustable resistors R1 and R2.

[0012] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the amplification factors of A2 and A3 are both adjusted by digital chips. The adjustment range of A2 amplification factor is an integer multiple of 2 within 1 to 100, and the adjustment range of A3 amplification factor is 1.0 to 9.9 times.

[0013] In the aforementioned civil aircraft cargo hold smoke concentration detection system based on polarized light, the amplifier A1 arranged after the light receiving tube L3 is a radiation follower circuit.

[0014] Compared with the prior art, the present invention is a smoke concentration detection system for the cargo hold of a civil aircraft based on polarized light, belonging to the field of aircraft fire protection technology. The system realizes full-range detection of smoke concentration under polarization state by setting an adjustable light-emitting module, an adjustable polarized light-receiving module, and a logic control and data processing module. The present invention is suitable for the collection and processing of fire smoke signals, and adopts the idea of ​​digital combination regulation. By introducing a feedback signal mechanism, the intensity range of the collected light signal is regulated. On the premise of ensuring that it does not exceed the effective range of the operational amplifier, it has the function of independently regulating the light-emitting and light-receiving intensities, thereby avoiding false alarms caused by maze pollution and smoke concentration saturation. This method has a wide detection concentration range, good detection concentration continuity, high regulation accuracy, and reliable alarm.

[0015] The present invention uses infrared and blue light sources to illuminate smoke and interference particles, and converts light signals through a polarized light receiving module to collect smoke concentration, respectively calculate infrared and blue light smoke concentration increments, and timely discover concentration increment and increment ratio change trends. Smoke particles and interference particles output different signals. The system has high recognition of particle size and shape, and high alarm accuracy.

[0016] The background value of the traditional concentration detection system is a fixed value set at the factory. When the detector maze is contaminated, the background value will continue to increase. When the background value is greater than the smoke concentration of the smoke detection system, the system will report a false alarm. This system aims at the increase in the system detection background value caused by the internal maze contamination of the detector. The system can automatically adjust the intensity of the light module in real time according to the change of the background value, reduce the increase in the background value caused by contamination, and avoid false alarms caused by the background value being greater than the set smoke concentration alarm threshold;

[0017] The background value of the traditional concentration detection system is a fixed value set at the factory. When the detector maze is contaminated, the background value rises to the set threshold, and the smoke detection system reports a cleaning failure and cannot continue to be used. It needs to be returned to the factory for cleaning and maintenance. This system aims at the increase in the system detection background value caused by the internal maze contamination of the detector. The system can automatically adjust the intensity of the light module in real time according to the change of the background value, reduce the increase in the background value caused by the contamination, and the background value can still be kept within the normal use range. The smoke detector can continue to be used, shortening the regular maintenance cycle of the detector, and extending the maintenance interval from 1 year to more than 5 years.

[0018] The smoke concentration range detected by traditional red and blue light dual-wavelength photoelectric smoke detectors is generally between 80% and 100% / ft (light transmittance). When the smoke concentration exceeds the range of 80% to 100% / ft, the infrared or blue light smoke collection intensity will be saturated, forming a single-wavelength (infrared or blue light) working mode. The system loses the function of distinguishing smoke from interfering particles, causing false alarms. For different smoke concentrations, especially the detector is prone to saturation under high-concentration smoke, the light-collecting and light-emitting modules of the present invention can be adjusted at the same time to expand the collection range of smoke concentrations and achieve full-range continuous smoke detection between 0% and 100% / ft. The system always maintains the red and blue light dual-wavelength detection mode to avoid false alarms caused by saturation. The system false alarm rate is reduced from no more than 5% to no more than 2%.

[0019] The present invention adopts a digital chip to adjust the luminous intensity and the amplification factor of the light receiving module collection amplifier, which can realize automatic adjustment of the amplification factor. Compared with the method of adjusting the amplification factor by switching the fixed value resistor (the fixed value amplification factor is set by welding different resistors before leaving the factory), the smoke concentration collection range can be automatically adjusted, and the real-time performance is good;

[0020] The present invention adopts a digital chip to control the amplification factor of the light receiving module collection amplifier, and can realize continuous adjustment of the amplification factor within 0 to 1000 times, with good continuity and high smoke detection concentration collection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a block diagram of the system composition of the present invention;

[0022] Figure 2 It is the system principle diagram of the present invention;

[0023] Figure 3 The infrared light emitting and receiving module adjustment method under polarization conditions of the present invention;

[0024] Figure 4 The invention discloses a method for adjusting a blue light emitting and receiving module under polarization conditions. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0026] Example 1. See Figure 1 and Figure 2As shown, a smoke concentration detection system for a cargo hold of a civil aircraft based on polarized light includes an adjustable light emitting module, an adjustable polarized light receiving module and a logic control and data processing module; the adjustable light emitting module is used to output infrared or blue light signals with variable intensity, which enter the adjustable polarized light receiving module after being scattered by smoke particles; the adjustable polarized light receiving module is used to convert the light signal into an electrical signal and then input it into the logic control and data processing module; the input logic control and data processing module is used to perform data processing on the electrical signal to judge smoke and interference, and at the same time adjust the amplification factor according to the signal strength of the adjustable polarized light receiving module.

[0027] The adjustable polarization light receiving module includes a light receiving tube L3, an amplifier A1, an amplifier A2, and an amplifier A3; the output end of the light receiving tube L3 is connected to the signal positive input end of the amplifier A1, and the output end of the amplifier A1 is connected to the logic control and data processing module; the output end of the amplifier A1 is also connected to the signal positive input end of the amplifier A2, an adjustable resistor R1 is connected between the signal negative input end and the output end of the amplifier A2, the adjustable resistor R1 is also connected to the logic control and data processing module, and the output end of the amplifier A2 is connected to the output end logic control and data processing module; the output end of the amplifier A2 is also connected to the signal positive input end of the amplifier A3, an adjustable resistor R2 is connected between the signal negative input end and the output end of the amplifier A3, the adjustable resistor R2 is also connected to the logic control and data processing module, and the output end of the amplifier A3 is also connected to the logic control and data processing module.

[0028] The adjustable light-emitting module includes an infrared adjustment unit T1, a blue light adjustment unit T2, an infrared light-emitting tube L1 and a blue light-emitting tube L2; the input end of the infrared adjustment unit T1 is connected to the logic control and data processing module, and the output end is connected to the infrared light-emitting tube L1; the input end of the blue light adjustment unit T2 is connected to the logic control and data processing module, and the output end is connected to the blue light-emitting tube L2.

[0029] The logic control and data processing module includes a central processing unit U1; the input signal of U1 includes feedback signal 1, feedback signal 2, and feedback signal 3 respectively coming from the output ends of amplifiers A1, A2, and A3; the output signal of U1 includes control signal 1, control signal 2, control signal 3, and control signal 4 respectively controlling R1, R2, T1, and T2.

[0030] The adjustable polarization receiving module collects the parameters of the light signal scattered by smoke and interference particles in the polarization state through the photoelectric tube L3, which is a photoelectric tube with a polarizer.

[0031] The amplification factors of the adjustable polarization receiving modules A2 and A3 can be adjusted through the corresponding adjustable resistors R1 and R2. The amplification factors of A2 and A3 are both adjusted by digital chips. The adjustment range of the amplification factor of A2 is an integer multiple of 2 within 1 to 100, and the adjustment range of the amplification factor of A3 is 1.0 to 9.9 times.

[0032] The amplifier A1 arranged after the light receiving tube L3 of the adjustable polarization light receiving module is an emitter-follower circuit, which performs signal isolation to ensure the accuracy of the subsequent stage amplification.

[0033] The light-emitting tube of the adjustable polarization light-emitting module is of LED type, wherein the wavelength of L1 is 900-1000nm, and the wavelength of L2 is 400-500nm.

[0034] See also Figure 3 As shown, the method for adjusting the infrared light-emitting and light-receiving modules under polarization conditions to achieve full-range smoke concentration detection is as follows: when the product is powered on, the infrared LED emits light, and the adjustable polarized light-receiving module collects the background concentration value of the detector. When the background value concentration is greater than the preset threshold, the luminous intensity adjustment is started, and U1 outputs control signal 3 to adjust the intensity of the infrared light-emitting signal to reduce the luminous intensity; when the background value concentration is not greater than the set threshold, normal infrared smoke concentration collection is performed, and the smoke concentration is input to U1 through feedback signal 1, and U1 performs data calculation and saturation value comparison. When the collected smoke concentration is saturated, the algorithm outputs control signal 1 to start the first-stage op amp adjustment; the smoke concentration is input to U1 through feedback signal 2, and U1 performs data calculation and saturation value comparison. When the collected concentration is still saturated, the algorithm outputs control signal 2 to start the second-stage op amp adjustment; the smoke concentration is input to U1 through feedback signal 3, and U1 performs data calculation and saturation value comparison. When the collected concentration is still saturated, the algorithm starts the luminous intensity adjustment again.

[0035] See also Figure 4 As shown, the method for adjusting the blue light emitting and receiving modules under polarization conditions to achieve full-range smoke concentration detection is as follows: when the product is powered on, the blue light LED emits light, and the adjustable polarized light receiving module collects the background concentration value of the detector. When the background value concentration is greater than the preset threshold, the luminous intensity adjustment is started, and U1 outputs control signal 4 to adjust the intensity of the blue light luminous signal to reduce the luminous intensity; when the background value concentration is not greater than the set threshold, normal blue light smoke concentration collection is performed, and the smoke concentration is input to U1 through feedback signal 1, and U1 performs data calculation and saturation value comparison. When the collected smoke concentration is saturated, the algorithm outputs control signal 1 to start the first-stage operational amplifier adjustment; the smoke concentration is input to U1 through feedback signal 2, and U1 performs data calculation and saturation value comparison. When the collected concentration is still saturated, the algorithm outputs control signal 2 to start the second-stage operational amplifier adjustment; the smoke concentration is input to U1 through feedback signal 3, and U1 performs data calculation and saturation value comparison. When the collected concentration is still saturated, the algorithm starts the luminous intensity adjustment again.

[0036] Civil aircraft smoke concentration detection system based on polarized light, Figure 3 and Figure 4 The adjustment method is carried out simultaneously, ensuring that the infrared and blue light dual-wavelength smoke concentration increment and increment ratio data are valid and unsaturated, thereby realizing full-range concentration detection of the system.

[0037] Compared with the prior art, the present invention adopts an adjustable light-emitting module and an adjustable light-receiving module, and adopts a digital adjustment circuit to automatically and continuously adjust according to the background value or smoke concentration change, so as to realize the real-time controllable smoke concentration detection range, and the detector has strong adaptability. It avoids false alarms caused by the contamination of the smoke detector maze and the saturation of the smoke detector, and has high reliability; the light intensity of the light-emitting module of the present invention can be automatically and continuously adjusted according to the needs, which is convenient and flexible, and has a large adjustment range; the electrical signal collected by the light-receiving module of this method adopts a digital circuit to adjust the amplification factor, which can be continuously and automatically adjusted according to the needs compared with the traditional fixed amplification factor or the fixed switching gear adjustment using an analog circuit, and has a large adjustment range and high adjustment accuracy; the present invention is provided with a logic control and data processing module, and the light intensity and amplification factor of the smoke detection range are adjusted according to different environments. The control method is intelligent and efficient, and the alarm accuracy is high.

[0038] Embodiment 2. A smoke concentration detection system for a cargo hold of a civil aircraft based on polarized light, comprising an adjustable light emitting module, an adjustable polarized light receiving module, and a logic control and data processing module; the adjustable light emitting module is used to output an infrared or blue light signal with variable intensity, which enters the adjustable polarized light receiving module after being scattered by smoke particles; the adjustable polarized light receiving module is used to convert the light signal into an electrical signal and input it into the logic control and data processing module; the input logic control and data processing module is used to perform data processing on the electrical signal to judge smoke and interference, and adjust the amplification factor according to the signal intensity of the adjustable polarized light receiving module.

[0039] The aforementioned adjustable polarization light receiving module includes a phototube L3 for receiving light, the output end of the phototube L3 is connected to the signal positive input end of the amplifier A1, and the output end of the amplifier A1 is connected to the logic control and data processing module; the output end of the amplifier A1 is also connected to the signal positive input end of the amplifier A2, and an adjustable resistor R1 is connected between the signal negative input end and the output end of the amplifier A2, and the adjustable resistor R1 is also connected to the logic control and data processing module, and the output end of the amplifier A2 is connected to the output end logic control and data processing module; the output end of the amplifier A2 is also connected to the signal positive input end of the amplifier A3, and an adjustable resistor R2 is connected between the signal negative input end and the output end of the amplifier A3, and the adjustable resistor R2 is also connected to the logic control and data processing module, and the output end of the amplifier A3 is also connected to the logic control and data processing module.

[0040] The aforementioned adjustable light-emitting module includes an infrared adjustment unit T1, a blue light adjustment unit T2, an infrared LED light-emitting tube L1 and a blue light LED light-emitting tube L2; the input end of the infrared adjustment unit T1 is connected to the logic control and data processing module, and the output end is connected to the infrared LED light-emitting tube L1; the input end of the blue light adjustment unit T2 is connected to the logic control and data processing module, and the output end is connected to the blue light LED light-emitting tube L2.

[0041] The light-emitting tube of the adjustable polarization light-emitting module is of LED type, wherein the wavelength of L1 is 900-1000nm, and the wavelength of L2 is 400-500nm.

[0042] The light brightness of the infrared LED light emitting tube L1 and the blue LED light emitting tube L2 can be adjusted.

[0043] The aforementioned infrared adjustment unit T1 and blue light adjustment unit T2 are both digital chips, which are used to adjust the luminous intensity of the infrared LED light-emitting tube L1 and the blue light LED light-emitting tube L2 respectively.

[0044] The aforementioned logic control and data processing module includes a central processing unit U1; the input signal of U1 includes feedback signal 1, feedback signal 2, and feedback signal 3 respectively coming from the output ends of amplifiers A1, A2, and A3; the output signal of U1 includes control signal 1, control signal 2, control signal 3, and control signal 4 respectively controlling R1, R2, T1, and T2.

[0045] L3 is a photoelectric tube with a polarizer.

[0046] The amplification factors of A2 and A3 are adjusted by the corresponding adjustable resistors R1 and R2.

[0047] The magnification of A2 and A3 are both adjusted by digital chips. The magnification adjustment range of A2 is an integer multiple of 2 within 1 to 100, and the magnification adjustment range of A3 is 1.0 to 9.9 times.

[0048] The amplifier A1 arranged after the light receiving tube L3 is an emitter-follower circuit, which performs signal isolation to ensure the accuracy of the subsequent stage amplification.

[0049] During the smoke concentration collection process, first determine whether the background value is greater than the preset threshold. If it is greater than the preset threshold, the intensity of the infrared LED light-emitting tube L1 and / or the blue light LED light-emitting tube L2 is weakened; if it is less than the preset threshold, normal smoke concentration collection is performed; if the smoke concentration is saturated, the adjustable resistor R1 corresponding to the amplifier A2 is used to roughly adjust the light receiving intensity. If the light receiving adjustment still fails to achieve the expected effect, the adjustable resistor R2 corresponding to the amplifier A3 is used to fine-tune the light receiving intensity; if the expected effect is still not achieved after adjusting R1 and R2, the intensity of the infrared light-emitting tube L1 and / or the blue light-emitting tube L2 is weakened again.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A smoke concentration detection system for cargo hold of civil aircraft based on polarized light, characterized in that: It includes an adjustable light-emitting module, an adjustable polarized light-receiving module, and a logic control and data processing module; the adjustable light-emitting module is used to output infrared or blue light signals with variable intensity, which enter the adjustable polarized light-receiving module after being scattered by smoke particles; the adjustable polarized light-receiving module is used to convert the light signal into an electrical signal and then input it into the logic control and data processing module; the logic control and data processing module is used to perform data processing on the electrical signal to judge smoke and interference, and at the same time adjust the amplification factor according to the signal intensity of the adjustable polarized light-receiving module; the adjustable light-emitting module includes an infrared adjustment unit T1, a blue light adjustment unit T2, an infrared LED light-emitting tube L1 and a blue LED light-emitting tube L2; the input end of the infrared adjustment unit T1 is connected to the logic control and data processing module, and the output end is connected to the infrared LED light-emitting tube L1; the input end of the blue light adjustment unit T2 is connected to the logic control and data processing module, and the output end is connected to the blue LED light-emitting tube L2; the light brightness of the infrared LED light-emitting tube L1 and the blue LED light-emitting tube L2 is adjustable; the infrared adjustment unit The node unit T1 and the blue light adjustment unit T2 are both digital chips, which are used to adjust the luminous intensity of the infrared LED light-emitting tube L1 and the blue light LED light-emitting tube L2 respectively; L3 is a phototube with a polarizer; the adjustable polarized light-receiving module includes a phototube L3 for receiving light, the output end of the phototube L3 is connected to the signal positive input end of the amplifier A1, and the output end of the amplifier A1 is connected to the logic control and data processing module; the output end of the amplifier A1 is also connected to the signal positive input end of the amplifier A2, and an adjustable resistor R1 is connected between the signal negative input end and the output end of the amplifier A2, and the adjustable resistor R1 is also connected to the logic control and data processing module, and the output end of the amplifier A2 is connected to the output end logic control and data processing module; the output end of the amplifier A2 is also connected to the signal positive input end of the amplifier A3, and an adjustable resistor R2 is connected between the signal negative input end and the output end of the amplifier A3, and the adjustable resistor R2 is also connected to the logic control and data processing module, and the output end of the amplifier A3 is also connected to the logic control and data processing module.

2. The polarized light-based smoke concentration detection system for cargo compartments of civil aircraft according to claim 1, characterized in that: The logic control and data processing module includes a central processing unit U1; the input signal of U1 includes feedback signal 1, feedback signal 2, and feedback signal 3 respectively from the output ends of amplifiers A1, A2, and A3; the output signal of U1 includes control signal 1, control signal 2, control signal 3, and control signal 4 for controlling R1, R2, T1, and T2 respectively.

3. The civil aircraft cargo hold smoke concentration detection system based on polarized light according to claim 1, characterized in that: The amplification factors of A2 and A3 are adjusted by the corresponding adjustable resistors R1 and R2.

4. The polarized light-based smoke concentration detection system for cargo compartments of civil aircraft according to claim 1, characterized in that: The magnification of A2 and A3 are both adjusted by digital chips. The magnification adjustment range of A2 is an integer multiple of 2 within 1 to 100, and the magnification adjustment range of A3 is 1.0 to 9.9 times.

5. The polarized light-based smoke concentration detection system for cargo compartments of civil aircraft according to claim 1, characterized in that: The amplifier A1 arranged after the light receiving tube L3 is an emitter-follower circuit.

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