A fuel temperature measurement system based on optical fiber

Abstract

The present invention relates to the technical field of fuel temperature measurement, and discloses a fuel temperature measurement system based on optical fiber, comprising: 1. a light source input unit, a plastic optical fiber sensing unit, a photoelectric detector unit, a power feedback unit, and a temperature demodulation unit; the light source input unit is used to input a broad-spectrum light source and generate a broad-spectrum light source signal; the plastic optical fiber sensing unit is used to transmit the broad-spectrum light source signal to the optical fiber temperature sensor; the photoelectric detector unit is used to convert the light intensity signal into a current signal with a linear relationship, and transmit the current signal to the power feedback unit for responding to the range interval of the broad-spectrum light source wavelength and setting a corresponding power linear response interval; the power feedback unit is used to control the input voltage through output feedback; and the temperature demodulation unit is used to collect the voltage signal and calculate the temperature value according to the voltage amplitude.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel temperature measurement, and in particular to an optical fiber-based fuel temperature measurement system for measuring the fuel temperature of an aircraft while ensuring safety in a fuel tank. Background Art

[0002] Current aircraft fuel temperature measurement technology commonly uses thermistor-based temperature sensors, which convert fuel temperature into a resistance signal. The resistance signal's value is then measured to determine the fuel temperature. Since measuring the resistance signal requires a voltage input, inputting the voltage signal into the fuel tank poses a risk and requires high signal isolation protection. Transmission wires and sensors are typically installed in a sealed metal tube and secured within the tank, incurring additional weight. Furthermore, during transmission outside the tank, the resistance signal is susceptible to interference from the aircraft's complex electromagnetic environment, affecting temperature measurements.

[0003] Therefore, the present invention addresses the deficiencies of the above-mentioned prior art and proposes a fuel temperature measurement system that can meet the safety requirements in a fuel tank. Summary of the Invention

[0004] The purpose of the present invention is to provide an optical fiber-based fuel temperature measurement system for measuring aircraft fuel temperature while ensuring safety in fuel tanks. The system is particularly suitable for aircraft fuel temperature measurement technology with high reliability and safety requirements and complex electromagnetic environments.

[0005] The present invention is implemented through the following technical solutions: an optical fiber-based fuel temperature measurement system, comprising a light source input unit, a plastic optical fiber sensing unit, a photodetector unit, a power feedback unit and a temperature demodulation unit;

[0006] A light source input unit is used to input a broad-spectrum light source according to a loss characteristic curve of visible spectrum transmission in plastic optical fiber to generate a broad-spectrum light source signal;

[0007] A plastic optical fiber sensing unit is used to transmit the broadband light source signal to an optical fiber temperature sensor. The optical fiber temperature sensor uses a photometric plastic optical fiber wound into a ring structure. The optical fiber temperature sensor outputs a light intensity signal having a certain relationship with the fuel temperature and transmits the signal to a photodetector unit.

[0008] A photoelectric detector unit is used to convert the light intensity signal into a current signal with a linear relationship, and transmit the current signal to a power feedback unit for responding to the range of wavelengths of the wide-spectrum light source and setting a corresponding power linear response range;

[0009] The power feedback unit is used to control the input voltage through output feedback to ensure that the output dynamic range of the sensor is within the linear range of the detector;

[0010] The temperature demodulation unit is used to collect voltage signals and calculate the temperature value based on the voltage amplitude.

[0011] In order to better implement the present invention, further, the luminescence type plastic optical fiber in the plastic optical fiber sensing unit includes a plastic optical fiber core and an optical fiber cladding;

[0012] The plastic optical fiber core material is PMMA material, and the optical fiber cladding material is fluorine material.

[0013] In order to better implement the present invention, further, the light source input unit includes:

[0014] Selecting a wavelength range A in which the optical fiber material has a stable effect on the light intensity loss according to the transmission loss characteristic curve;

[0015] According to the absorption curve of the visible spectrum in the fuel, the wavelength range B where the fuel absorbs the visible light unstable is filtered out;

[0016] The wavelength range A is a wavelength range of 400nm-600nm, the wavelength range B is a wavelength range of 610nm-620nm, and the peak wavelength of the input broadband light source is 500nm.

[0017] In order to better implement the present invention, further, the photodetector unit includes:

[0018] When the wavelength range A is 400 nm-600 nm, the wavelength responded by the photodetector unit is 400 nm-600 nm, and the corresponding linear response range of the power is set to [0 mW, 60 mW].

[0019] In order to better implement the present invention, further, the power feedback unit includes:

[0020] The power feedback unit performs a temperature calibration;

[0021] The linear working range of the preset detector is [P1, P2];

[0022] Preset temperature range a, output corresponding temperature sensing characteristic curve b within the preset temperature range;

[0023] Set the temperature range to be measured to [T1, T2], where [T1, T2] includes the preset temperature range a;

[0024] Assume that when the temperature is (T1+T2) / 2, the power received by the detector is X. When X>(P1+P2) / 2, the excitation power is reduced through the power feedback unit to reduce the output power. When X<(P1+P2) / 2, the excitation power is increased through the power feedback unit to increase the output power, so as to ensure that when the temperature is (T1+T2) / 2, the power output is approximately (P1+P2) / 2.

[0025] The power feedback unit performs secondary temperature calibration, which repeats the calibration steps of the primary temperature calibration and determines the preset temperature range b according to the stability of the plastic optical fiber material.

[0026] In order to better implement the present invention, the sensitivity of the optical fiber temperature sensor is further adjusted by adjusting the structure of the sensor optical fiber ring in the optical fiber temperature sensor.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) The optical fiber-based fuel temperature measurement system provided by the present invention can greatly save hardware resources and achieve safety requirements in the fuel tank;

[0029] (2) The present invention can avoid being affected by electromagnetic interference;

[0030] (3) The optical fiber transmission cable in the present invention is much lighter than the electrical signal transmission cable, which can play a role in weight reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described in conjunction with the following drawings and embodiments, and all concepts and innovations of the present invention should be regarded as disclosed contents and the protection scope of the present invention.

[0032] Figure 1 This is a schematic diagram of a range-adaptive capacitance measurement technology in an optical fiber-based fuel temperature measurement system provided by the present invention.

[0033] Figure 2 This is a schematic diagram of the transmission loss characteristic curve of the visible spectrum in a PMMA core plastic optical fiber in an optical fiber-based fuel temperature measurement system provided by the present invention.

[0034] Figure 3 This is a schematic diagram of a curve showing the variation of plastic optical fiber optical power output with temperature in an optical fiber-based fuel temperature measurement system provided by the present invention. DETAILED DESCRIPTION

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and therefore should not be regarded as limiting the scope of protection. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technical personnel in this field without making creative work are within the scope of protection of the present invention.

[0036] Example 1:

[0037] This embodiment is a fuel temperature measurement system based on optical fiber, such as Figure 1 The present invention discloses a range-adaptive aircraft fuel temperature measurement system based on plastic optical fiber. The core of this measurement system lies in its compact and lightweight plastic optical fiber sensing unit, easy installation, real-time response, high efficiency and accuracy, and resistance to electromagnetic interference. It also automatically adapts to the sensing temperature according to the operating environment, maintaining a stable linear output state. The plastic optical fiber-based aircraft fuel temperature measurement system primarily comprises a light source input unit, a plastic optical fiber sensing unit, a photodetector unit, a power feedback unit, and a temperature demodulation unit. The present invention is implemented by the following method: the plastic optical fiber sensing unit is positioned at the bottom of the fuel tank, ensuring that the optical fiber remains continuously immersed in the fuel. The light source input unit inputs a light source, which is modulated by the power feedback unit. The output signal light passes through the plastic optical fiber sensing unit, where it undergoes scattering and absorption effects. The change in fuel temperature is functionally related to the attenuation of light intensity. Finally, the light signal is received by the photodetector unit and converted into a voltage signal. The temperature demodulation unit processes the output temperature signal. The light source input unit generates a light signal, which is then transmitted via the plastic optical fiber sensing unit's optical transmission fiber to a fiber optic temperature sensor. The fiber optic temperature sensor senses the change in fuel temperature and outputs a light signal whose light intensity is proportional to the fuel temperature. This signal is then transmitted via the optical transmission fiber to the photodetector unit. The photodiode in the photodetector unit converts light intensity into a current signal that is linearly proportional to the light intensity. This current signal is converted into a voltage signal by an op amp circuit and transmitted to the temperature demodulation unit. The temperature demodulation unit collects the voltage signal and calculates the temperature value based on the voltage amplitude.

[0038] The signal inside the fuel tank is a light signal, which is highly safe and meets the safety requirements inside the fuel tank. The signal inside the fuel tank is a light signal, which is highly safe and meets the safety requirements inside the fuel tank.

[0039] The temperature demodulation unit can demodulate the voltage output by the photodetector in the photodetector unit into a digital output corresponding to the fuel temperature. Through algorithm optimization, it ensures that when the light source power is adjusted, the system can be adjusted accordingly, and the accurate temperature signal can be demodulated.

[0040] Example 2:

[0041] This embodiment is further optimized based on the first embodiment. The luminescent plastic optical fiber in the plastic optical fiber sensing unit includes a plastic optical fiber core and an optical fiber cladding. The plastic optical fiber core is made of PMMA and the optical fiber cladding is made of fluorine.

[0042] This embodiment uses plastic optical fiber. Using plastic optical fiber for sensing is an emerging sensing method. Compared with traditional quartz optical fiber sensing technology, the advantage of plastic optical fiber is that it is cheaper and simpler to operate. It can be calibrated through the feedback system described in this embodiment, making it more suitable for large-scale high-precision measurement and taking into account the adaptability of the use environment.

[0043] Unlike the traditional method of using fiber Bragg grating as a sensitive element for the purpose of measuring oil level, the mechanism of measuring fuel level is to convert the oil level height into pressure. The reflection center wavelength of the fiber Bragg grating changes with the liquid pressure. In this embodiment, the plastic optical fiber is used to measure the oil temperature. The power output of the plastic optical fiber changes with the temperature, thereby performing temperature sensing.

[0044] Plastic optical fiber has the following advantages over quartz optical fiber: the trial production tools are simple, only ordinary tungsten steel blades are needed for cutting, and optical coupling can be completed by plugging the connectors together. There is no need for professional equipment such as cutting knives and welding machines. It is easy to operate and has strong practicality.

[0045] The rest of this embodiment is the same as that of embodiment 1, so it will not be described again.

[0046] Example 3:

[0047] This embodiment is further optimized based on the above embodiment 1 or 2, and the light source input unit includes:

[0048] According to the transmission loss characteristic curve, select the wavelength range A where the optical fiber material has a stable effect on the light intensity loss;

[0049] According to the absorption curve of the visible spectrum in the fuel, the wavelength range B where the fuel absorbs the visible light unstable is filtered out;

[0050] The wavelength range A is 400 nm to 600 nm, the wavelength range B is 610 nm to 620 nm, and the peak wavelength of the input broad spectrum light source is 500 nm.

[0051] In this embodiment, if Figure 2As shown in the figure, the transmission loss characteristic curve of the visible spectrum in the PMMA core plastic optical fiber shows that the optical fiber material has little effect on the light intensity loss in the wavelength range of 400nm-600nm, which is conducive to maintaining a high signal-to-noise ratio. The absorption curve of the visible spectrum in fuel oil shows that in the wavelength range of 610nm-620nm, the absorption of visible light by fuel oil has large fluctuations. Therefore, green light with a peak wavelength of 500nm is selected to ensure that most of the light energy is within the range of 400nm-600nm.

[0052] The rest of this embodiment is the same as that of the above-mentioned embodiment 1 or 2, and thus will not be described in detail.

[0053] Example 4:

[0054] This embodiment is further optimized based on any one of the above embodiments 1-3, and the photodetector unit includes:

[0055] When the wavelength range A is 400 nm-600 nm, the wavelength responded by the photodetector unit is 400 nm-600 nm, and the corresponding linear response range of the power is set to [0 mW, 60 mW].

[0056] By selecting the peak wavelength, interference signals can be largely shielded.

[0057] The rest of this embodiment is the same as any of the above embodiments 1-3, so it will not be repeated here.

[0058] Example 5:

[0059] This embodiment is further optimized based on any one of the above embodiments 1-4, and the power feedback unit includes:

[0060] The power feedback unit performs a temperature calibration;

[0061] The linear working range of the preset detector is [P1, P2];

[0062] Preset temperature range a, output corresponding temperature sensing characteristic curve b within the preset temperature range;

[0063] Set the temperature range to be measured to [T1, T2], where [T1, T2] includes the preset temperature range a;

[0064] Assume that when the temperature is (T1+T2) / 2, the power received by the detector is X. When X>(P1+P2) / 2, the excitation power is reduced through the power feedback unit to reduce the output power. When X<(P1+P2) / 2, the excitation power is increased through the power feedback unit to increase the output power, so as to ensure that when the temperature is (T1+T2) / 2, the power output is approximately (P1+P2) / 2.

[0065] The power feedback unit performs secondary temperature calibration, which repeats the calibration steps of the primary temperature calibration and determines the preset temperature range b according to the stability of the plastic optical fiber material.

[0066] The power feedback unit ensures that the detection power is always in the linear amplification region.

[0067] In this embodiment, the input voltage is controlled by output feedback to ensure that the output dynamic range of the sensor is in the linear region of the detector, thereby ensuring that the temperature sensor has a large measurement range and maintains good sensing characteristics.

[0068] First, assume that the linear working range of the detector is [P1, P2];

[0069] Secondly, the temperature sensing characteristic curve within the range of -55℃ to 70℃ is as follows Figure 3 As shown, the linearity is good and the sensing sensitivity is about 18.9μW / ℃;

[0070] Next, set the temperature range to be measured to be roughly [T1, T2]. The temperature range here does not need to be accurate, it only needs to include the temperature range to be measured;

[0071] Finally, assume that when the temperature is (T1+T2) / 2, the power received by the detector is X. When X>(P1+P2) / 2, the excitation power is reduced through the feedback system to reduce the output power. When X<(P1+P2) / 2, the output is increased through the feedback system to ensure that when the temperature is (T1+T2) / 2, the power output is approximately (P1+P2) / 2.

[0072] After another temperature calibration, it can meet the requirements of accurate measurement in the range of -80℃ to 100℃ (the measurement range is determined by the stability of the plastic optical fiber material). The use of this feedback system can ensure that the temperature sensor has a large measurement range and maintains good sensing characteristics.

[0073] The rest of this embodiment is the same as any of the above embodiments 1-4, so it will not be repeated here.

[0074] Example 6:

[0075] This embodiment further optimizes any of the above embodiments 1-5 by adjusting the structure of the fiber optic sensor ring to adjust the sensitivity of the fiber optic temperature sensor. In this embodiment, the optical fiber is wound into a ring structure with a diameter greater than 10 times the diameter of the optical fiber. The ring structure can have multiple turns to increase sensing sensitivity.

[0076] Plastic optical fiber temperature sensors can meet the temperature detection requirements of general application environments ranging from -80°C to 100°C, and have characteristics such as high sensitivity and easy operation. When the resolution cannot meet the requirements, the sensitivity can be increased by adjusting the structure of the sensor's optical fiber ring to increase the sensing resolution.

[0077] The rest of this embodiment is the same as any of the above embodiments 1-3, so it will not be repeated here.

[0078] The above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention fall within the scope of protection of the present invention.

Claims

1. A fuel temperature measurement system based on optical fiber, characterized in that: The system comprises a light source input unit, a plastic optical fiber sensing unit, a photodetector unit, a power feedback unit, and a temperature demodulation unit. The light source input unit is used to input a broad-spectrum light source according to a loss characteristic curve of visible spectrum transmission in the plastic optical fiber to generate a broad-spectrum light source signal. A plastic optical fiber sensing unit is configured to transmit the broadband light source signal to a fiber optic temperature sensor. The fiber optic temperature sensor utilizes a photometric plastic optical fiber wound into a ring-shaped structure. The fiber optic temperature sensor outputs a light intensity signal having a certain relationship between light intensity and fuel temperature, and transmits the signal to a photodetector unit. The photodetector unit is configured to convert the light intensity signal into a current signal having a linear relationship, and transmit the current signal to a power feedback unit, which responds to the wavelength range of the broadband light source and sets a corresponding power linear response range. The power feedback unit is used to control the input voltage through output feedback to ensure that the output dynamic range of the sensor is within the linear range of the detector; the temperature demodulation unit is used to collect voltage signals and calculate the temperature value based on the voltage amplitude; The luminescence-measuring plastic optical fiber in the plastic optical fiber sensing unit comprises a plastic optical fiber core and an optical fiber cladding; The plastic optical fiber core material is PMMA material, and the optical fiber cladding material is fluorine material; The light source input unit includes: selecting a wavelength range A in which the fluctuation of the optical fiber material on the light intensity loss is stable according to the transmission loss characteristic curve; According to the absorption curve of the visible spectrum in the fuel, the wavelength range B where the fuel absorbs the visible light unstable is filtered out; The wavelength range A is a wavelength range of 400nm-600nm, the wavelength range B is a wavelength range of 610nm-620nm, and the peak wavelength of the input broadband light source is 500nm.

2. The optical fiber-based fuel temperature measurement system according to claim 1, characterized in that: The photodetector unit includes: When the wavelength range A is 400nm-600nm, the wavelength responded by the photodetector unit is 400nm-600nm, and the corresponding linear response range of power is set to [0mW, 60mW].

3. The optical fiber-based fuel temperature measurement system according to claim 1, characterized in that: The power feedback unit includes: The power feedback unit performs a temperature calibration; the linear operating range of the detector is preset to [P1, P2]; the temperature range a is preset, and the corresponding temperature sensing characteristic curve b is output within the preset temperature range; the temperature range to be measured is set to [T1, T2], and [T1, T2] includes the preset temperature range a; when the temperature is (T1+T2) / 2, the power received by the detector is X. When X>(P1+P2) / 2, the excitation power is reduced through the power feedback unit to reduce the output power. When X<(P1+P2) / 2, the excitation power is increased through the power feedback unit to increase the output power, so as to ensure that when the temperature is (T1+T2) / 2, the power output is approximately (P1+P2) / 2; the power feedback unit performs a secondary temperature calibration, which repeats the calibration steps of the primary temperature calibration and determines the preset temperature range b according to the stability of the plastic optical fiber material.

4. The optical fiber-based fuel temperature measurement system according to claim 1, characterized in that: The sensitivity of the optical fiber temperature sensor is adjusted by adjusting the structure of the sensor optical fiber ring in the optical fiber temperature sensor.

Images