Fuel oil monitoring system
By adopting photoelectric sensing technology and continuous self-test function in fuel level sensors, the problems of low reliability and detection efficiency caused by mechanical component defects in traditional systems are solved, and high-precision fuel monitoring and flight safety guarantees are achieved.
Patent Information
- Application Number
- CN202421307877.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-07
- Publication Date
- 2025-02-14
- Estimated Expiration
- 2034-06-07
AI Technical Summary
Due to the defects of mechanical components, traditional fuel level sensors are difficult to achieve self-test, resulting in low system reliability and detection efficiency.
The photoelectric sensing technology is used in combination with continuous self-test function, and the fuel status is monitored in real time through the probe module and the signal processing module, and the alarm signal is output to achieve self-testing and testing without interruption.
It significantly enhances the monitoring accuracy and reliability of the fuel level sensor, ensures flight safety, optimizes operational efficiency, and realizes maintenance-free self-test function.
Smart Images
Figure CN222481580U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of fuel monitoring, in particular to a fuel monitoring system. Background Art
[0002] As a key component of the aircraft fuel management system, fuel level sensors play a vital role in ensuring flight safety and optimizing operational efficiency. These sensors are responsible for monitoring the fuel inventory in each tank of the aircraft (including the wing tanks), and immediately send an alarm signal to the aircraft's central control system when the fuel level drops to the preset safety lower limit. This process not only involves sending warning information directly to the pilot, but may also trigger automatic fuel management strategies, such as allocating fuel between different tanks to maintain flight stability and safety.
[0003] The minimum fuel level alarm function constitutes the core defense mechanism of the aircraft fuel monitoring system. Its purpose is to identify and respond to the potential risk of fuel shortage in advance, ensuring that pilots have enough time to take necessary measures to prevent potential dangerous situations. The essence of the system design lies in its high reliability and simplicity. Traditionally, a combination of a float with a magnet and a reed switch is often used. Although this solution is reliable, it is limited by the difficulty of implementing self-test (Built-In Test, BIT), which makes it impossible to verify the operating status of the sensor and the effectiveness of the alarm function in real time. In view of this limitation, a new solution that can eliminate the defects of the traditional mechanical components of the system is urgently needed to improve the reliability of the system. Utility Model Content
[0004] The utility model aims to provide a fuel monitoring system, which avoids defects of mechanical parts and enhances the reliability and monitoring accuracy of the fuel level sensor through photoelectric sensing technology and integrated continuous self-checking function.
[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0006] A fuel monitoring system includes a probe module and a signal processing module, wherein the probe module is used to collect fuel data, and the signal processing module is used to monitor the fuel state in real time according to the collected fuel data and output an alarm signal;
[0007] The signal processing module includes a first shift register, a three-bit decoder, a trigger, a second shift register, a logic gate circuit, a digital filter and an emitter follower. One end of the first shift register is connected to the probe module, and the other end is connected to the three-bit decoder, the trigger, the second shift register, the logic gate circuit, the digital filter and the emitter follower in sequence.
[0008] Furthermore, the probe module includes: an optical probe, a controlled current generator and a comparator, the optical probe, the controlled current generator and the comparator are connected in sequence; the optical probe includes an infrared LED light source and a phototransistor, the infrared LED light source is used to emit infrared light to the phototransistor; the phototransistor is used to receive the light source and output a current signal; the phototransistor is within the irradiation range of the infrared LED light source on the inner wall of the oil storage tank, the collector of the phototransistor is connected to the Vcc power supply through a resistor, and the emitter of the phototransistor is grounded;
[0009] The controlled current generator is connected to the positive electrode of the infrared LED light source in the optical probe to supply power to the infrared LED light source, and the negative electrode of the infrared LED light source is grounded;
[0010] The negative electrode of the comparator is connected to the collector of the phototransistor in the optical probe, and the positive electrode of the comparator is connected to the detection voltage; the comparator is used to receive the current signal output by the phototransistor and output a logic signal DET_OUT.
[0011] Furthermore, the controlled current generator includes: a ring counter, a current source I L and I H The input of the ring counter is a clock signal. The ring counter includes three pins, corresponding to states S0, S1 and S2 respectively, and forms a measurement cycle through the clock signal; the current source I L and I H , one end is connected to the Vcc power supply, and the other end is connected to the positive electrode of the infrared LED light source through a switch, wherein the pin corresponding to state S1 controls the current source I L The switch is on / off, and the pin corresponding to state S2 controls the current source I H The switch is on / off, and the pin corresponding to state S0 is left floating.
[0012] Furthermore, the first shift register and the second shift register are HC164 shift registers. The first shift register is used to convert the logic signal DET_OUT output by the probe module into a parallel output to a three-bit decoder; the second shift register is used to store the signal output by the three-bit decoder and input it to the logic gate circuit and the digital filter.
[0013] Furthermore, the three-bit decoder model is an HC148 three-bit decoder, which is used to convert the signals output by the first three pins of the first shift register into eight output signals.
[0014] Furthermore, the signals output by the three-bit decoder include output signals of circuits in which the clock signal is not converted normally, fault status signals, and status signals of phototransistors immersed in fuel and not immersed in fuel; fault status signals include LED failure, loss of phototransistor function, missing clock signal, and Vcc power supply interruption.
[0015] Furthermore, the trigger model is an HC273 eight-bit D-type trigger, which is used to capture the signal output by the trigger and store it in the second shift register.
[0016] Furthermore, the logic gate circuit is used to process the signal output by the second shift register; the digital filter is used to eliminate false alarms caused by signal noise, and its effectiveness is controlled by adjusting its clock frequency.
[0017] Furthermore, the emitter follower is also connected to an indicating device.
[0018] Furthermore, the emitter follower is used to convert the received signal into an alarm signal and send it to the indicating device.
[0019] Compared with the prior art, the utility model has the following technical effects:
[0020] The utility model provides a fuel detection system that adopts photoelectric sensing technology and integrated continuous self-test function, which effectively solves the reliability and detection efficiency problems existing in traditional mechanical components and significantly enhances the monitoring accuracy of the fuel level sensor; by real-time monitoring of the fuel inventory in the tank and sending an alarm immediately when the oil level drops to the safe lower limit, the system ensures flight safety and gives pilots sufficient time to take action to prevent potential crises. The triggering of automatic management strategies, such as fuel allocation between different tanks, maintains flight stability, which not only optimizes operational efficiency but also enhances the economy of flight. The photoelectric sensing system realizes maintenance-free, non-interruptible self-test (BIT), ensures real-time verification of sensor status, and improves the reliability of system operation. Through the design of logic gate circuits and anti-jitter filters, the system can quickly identify sensor anomalies such as power failures, short circuits, and photoelectric tube problems, ensuring immediate feedback of faults. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] 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 these drawings without paying creative work.
[0022] Figure 1 is a circuit diagram of the probe module of the system in this embodiment;
[0023] Figure 2 is a possible output signal timing diagram of the probe module of the system in this embodiment;
[0024] Figure 3 It is a schematic diagram of the structure of the signal processing part of the system in this implementation mode.
[0025] In the figure, 1. controlled current generator; 2. optical probe; 3. comparator; 4. first shift register; 5. three-bit decoder; 6. trigger; 7. second shift register; 8. logic gate circuit; 9. digital filter; 10. emitter follower; 11. indicating device; 101. ring counter; 201. infrared LED light source; 202. phototransistor. DETAILED DESCRIPTION
[0026] 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 in 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.
[0027] Figure 1 The overall circuit diagram of the probe module of one embodiment of this embodiment is shown. The probe uses a photoelectric sensor, is connected to a signal processing module, and includes a self-diagnosis function (BIT-built-in test). This configuration not only improves the accuracy of the measurement, but also ensures a high degree of reliability due to the absence of mechanical parts. The probe design provided in this embodiment allows automatic testing (BIT) to be performed without interruption when the system is operating normally.
[0028] like Figure 1 In some possible implementations, the fuel monitoring system probe module includes: an optical probe 2, which includes an infrared LED light source 201 and a phototransistor 202, which are precisely configured at the optimal distance according to actual requirements such as aircraft type and probe size, but must be within the irradiation range of the infrared LED light source 201 on the inner wall of the fuel tank to ensure efficient light transmission and reception. This layout allows the fuel to interact with the light beam between the LED and the phototransistor 202, forming the basis of the detection mechanism.
[0029] The circuit in the drawings of this embodiment is only one connection method, and the specific connection is not limited. As long as it is a connection method that can realize all the functions described in this embodiment, it is within the disclosure scope of this embodiment.
[0030] In some specific embodiments, the infrared LED light source 201 is powered by a controlled current generator 1, which includes a ring counter 101, the input of the ring counter 101 is a clock signal, and the ring counter 101 includes three pins, which correspond to three states (S0, S1, and S2), which are interconnected through internal logic to form a measurement cycle. The controlled current generator 1 circuit also includes current sources IL and IH, the current source IL is set to a low current, and the current source IH is set to a high current. One end of the current source is connected to the power supply (Vcc), and the other end is respectively provided with a switch, and the other end of the switch is connected to the infrared LED light source 201. The pin of the state S1 of the ring counter 101 controls the switch on / off of the current source IL, and the pin S2 controls the switch on / off of the current source IH. In this embodiment, the collector of the phototransistor 202 is connected to the power supply through a resistor, and the emitter is grounded. The collector of the phototransistor 202 is also connected to the negative electrode of a comparator 3, and the positive electrode of the comparator 3 is connected to the detection voltage, and the logic signal "DET_OUT" is output.
[0031] The specific principle of the optical probe 2 described in this embodiment is as follows: when the infrared LED light source 201 is powered on, the infrared LED acts as a light source to emit light, and the light will pass through the space where the probe is located (which may be fuel or air). The phototransistor 202 is located on the light path, and its function is to sense the change in light intensity and then convert it into an electrical signal. The conductivity of the phototransistor 202 will change with the amount of light received. If the probe is not immersed in fuel (i.e., in the air, "dry" condition), most of the light emitted by the infrared LED will directly irradiate the phototransistor 202, so that the amount of light received by the phototransistor 202 is large, and the conductivity of the phototransistor 202 will increase. This effect is converted into a logic signal "DET_OUT" by a comparator 3 connected to the phototransistor 202. When the sensor is completely or partially immersed in fuel, the fuel will absorb or scatter infrared light, so that the amount of light reaching the phototransistor 202 is reduced. This will cause the conductivity of the phototransistor 202 to decrease; at this time, the comparator 3 outputs a low current ("wet").
[0032] When the rising edge of the clock signal arrives, the ring counter 101 performs a measurement cycle according to three states (S0, S1, S2), during which three different current levels are provided, as shown in Table 1:
[0033] Table 1 Current level configuration table
[0034] S0 S1 S2 0mA <![CDATA[I L mA]]> <![CDATA[I H mA]]>
[0035] To ensure accurate detection, the current intensity (calibrated as I H and I L), the load resistor connected to the phototransistor 202, and the threshold of the comparator 3 all need to be properly selected. The design intention is that when the phototransistor 202 is not immersed in the fuel but exposed to the air, the DET_OUT signal will be set to a high current (H) during the sequence states S1 and S2. Based on this logic, Table 2 details the expected states of DET_OUT and their corresponding activation conditions in three consecutive stages (S0, S1, S2).
[0036] Table 2
[0037] Status Number S0,0mA <![CDATA[S1,I L mA]]> <![CDATA[S2,I H mA]]> state 0 L L L LED failed or not turned on Failure (FAIL) 1 L L H Sensor in fuel 2 L H L Impossible conditions 3 L H H Sensor not in fuel 4 H L L Impossible conditions 5 H L H Impossible conditions 6 H H L Impossible conditions 7 H H H Detector short circuit Failure (FAIL)
[0038] The “impossible conditions” in Table 2 are obviously physically impossible to occur, because DET_OUT cannot be active when the LED current is zero, nor can it be active when the current I L It is in the active state, and then the current I H When higher, it is inactive.
[0039] Figure 2 The time diagram of the events that may occur physically is shown. The curve shows the change of LED current. In the curve, the horizontal axis represents time and the vertical axis represents the current value. The curve consists of three line segments, representing three different current states: IH (high current), IL (low current) and 0mA (no current). The text below the curve explains the states corresponding to these three current states: AIR (air), FUEL (fuel), LED FAIL (LED failure), DET OPEN (detector open) and DET SHORT (detector short circuit). Figure 2 The lower part of the table lists the corresponding relationship between the Det_Out signal and the state. The left side shows the value of the Det_Out signal, which is divided into two states: L (low current) and H (high current).
[0040] like Figure 3 The signal processing part of the fuel monitoring system described in this embodiment includes two shift registers: a first shift register 4 and a second shift register 7, specifically an HC164 shift register, which is used to convert the input signal into a parallel output. It has 8 output pins, each pin corresponds to a binary bit. When the rising edge of the clock signal arrives, the input signal is captured by the shift register and stored in the internal register. Then, these signals are output in parallel to the next stage.
[0041] The input of the first shift register 4 is the DET_OUT logic signal output by the fuel probe part and the clock cycle signal.
[0042] The three-bit decoder 5 is specifically a HC148 three-bit decoder. This decoder is used to input the signals output by the first three pins of the first shift register 4 and convert them into 8 output signals. When the three input signals are combined, the decoder can represent 8 different states. Only one of the output pins of the decoder will output a high current, and the rest will output a low current. The output signal corresponds to the input signal of the decoder.
[0043] The trigger 6, specifically an HC273 eight-bit D trigger, is used to store state information. When the rising edge of the clock signal arrives, the signal output by the trigger 6 will be captured and stored in the second shift register 7. Then, these signals will be released at the beginning of the next clock cycle. In short, in this embodiment, the trigger 6 is used to transfer the signal output by the decoder to the second shift register 7.
[0044] In some specific implementations, the probe further includes a logic gate circuit 8 and an anti-shake digital filter 9 .
[0045] The emitter follower 10 is used to drive the signal output by the logic gate. In addition, in the present embodiment, since the output state of the emitter follower 10 can directly reflect the working state (on or off) of the phototransistor 202, when a fault occurs in the power circuit (such as loss of Vcc, damage to the LED or the phototransistor 202, clock problem, etc.), the emitter follower 10 will ensure that a low current signal is output, so that the system can quickly identify these fault conditions and respond.
[0046] The specific models described in this embodiment are all one of some possible implementation methods. The specific models can be selected according to needs. As long as the devices can achieve the above functions, they are within the scope of the disclosure of this embodiment.
[0047] The specific interaction process of the above units is as follows:
[0048] The signal of DET_OUT first enters a serial input / parallel output shift register as a control input, and then the output of the first three positions of the register is sent to the decoder. According to the encoding rules shown in Table 2, the decoded output "0" and "7" represent that the system is in an abnormal or "fault" state, while the decoded output "3" specifically indicates that the probe is not immersed in fuel, that is, it is in an air environment. The output result of the decoder is recorded in another register in real time and remains unchanged during the next measurement period containing 4 cycles. The output of the register is "0" and "7", and the output signal of the circuit whose clock signal is not normally converted is processed by the logic gate circuit 8 to generate a "fault" signal.
[0049] On the other hand, the register output "3" indicates the "probe not immersed" state and "1" indicates the "probe immersed in fuel", which is then fed into an "anti-shake" digital filter 9. The digital filter 9 is used to eliminate signal noise. The specific principle is that once a single "not immersed" signal is received, a "low fuel" signal is immediately output; to clear this alarm, multiple "immersion" state confirmations must be received in succession, reflecting a high tolerance design for false alarms. The effectiveness of the filter can be optimized by adjusting its operating clock frequency (the recommended range is 0.1Hz to 1Hz).
[0050] In this embodiment, the "fault" and "low fuel" alarm signals in the system are generated by the "emitter follower 10", and this design increases the system's high sensitivity to power supply anomalies. Specifically, once the Vcc power supply fails or the voltage is reset, the emitter follower 10 will output a low current signal to ensure that any potential faults, including LED failure (short circuit or open circuit), loss of function of the phototransistor 202 (which may also be short circuit or open circuit), clock signal loss (no pulse conversion) and Vcc power supply interruption, can be reported promptly and clearly, realizing the self-diagnosis function (BIT-built-in test), thereby improving the overall reliability and safety of the system.
[0051] Finally, the signals such as "fault", "low fuel", "immersion (normal fuel)" etc. generated by the emitter follower 10 are sent to the external indication device 11. The indication device 11 is not limited in form and may include sound and light alarms, indicator lights, and digital displays. Any device that can transmit information to the operator is within the scope of the disclosure of this embodiment.
[0052] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.
[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.
Claims
1. A fuel monitoring system, characterized in that: It includes a probe module and a signal processing module. The probe module is used to collect fuel data. The signal processing module is used to monitor the fuel status in real time according to the collected fuel data and output an alarm signal. The signal processing module comprises a first shift register (4), a three-bit decoder (5), a trigger (6), a second shift register (7), a logic gate circuit (8), a digital filter (9) and an emitter follower (10); one end of the first shift register (4) is connected to the probe module, and the other end is connected to the three-bit decoder (5), the trigger (6), the second shift register (7), the logic gate circuit (8), the digital filter (9) and the emitter follower (10) in sequence.
2. A fuel monitoring system according to claim 1, characterized in that: The probe module comprises: an optical probe (2), a controlled current generator (1) and a comparator (3), wherein the optical probe (2), the controlled current generator (1) and the comparator (3) are connected in sequence; the optical probe (2) comprises an infrared LED light source (201) and a phototransistor (202), wherein the infrared LED light source (201) is used to emit infrared light to the phototransistor (202); the phototransistor (202) is used to receive the light source and output a current signal; the phototransistor (202) is within the irradiation range of the infrared LED light source (201) on the inner wall of the oil storage tank, the collector of the phototransistor (202) is connected to a Vcc power supply through a resistor, and the emitter of the phototransistor (202) is grounded; The controlled current generator (1) is connected to the positive electrode of the infrared LED light source (201) in the optical probe (2) and is used to supply power to the infrared LED light source (201); the negative electrode of the infrared LED light source (201) is grounded; The negative electrode of the comparator (3) is connected to the collector of the phototransistor (202) in the optical probe (2), and the positive electrode of the comparator (3) is connected to the detection voltage; the comparator (3) is used to receive the current signal output by the phototransistor (202) and output a logic signal DET_OUT.
3. A fuel monitoring system according to claim 2, characterized in that: The controlled current generator (1) comprises: a ring counter (101), a current source I L and I H The input of the ring counter (101) is a clock signal. The ring counter (101) includes three pins corresponding to states S0, S1 and S2 respectively, and forms a measurement cycle through the clock signal; the current source I L and I H , one end is connected to the Vcc power supply, and the other end is connected to the positive electrode of the infrared LED light source (201) through a switch, wherein the pin corresponding to the state S1 controls the current source I L The switch is on / off, and the pin corresponding to state S2 controls the current source I H The switch is on / off, and the pin corresponding to state S0 is left floating.
4. A fuel monitoring system according to claim 1, characterized in that: The first shift register (4) and the second shift register (7) are HC164 shift registers. The first shift register (4) is used to convert the logic signal DET_OUT output by the probe module into a parallel output to a three-bit decoder (5); the second shift register (7) is used to store the signal output by the three-bit decoder (5) and input it to a logic gate circuit (8) and a digital filter (9).
5. A fuel monitoring system according to claim 1, characterized in that: The three-bit decoder (5) is a HC148 three-bit decoder, which is used to convert the signals output by the first three pins of the first shift register (4) into eight output signals.
6. A fuel monitoring system according to claim 5, characterized in that: The signals output by the three-bit decoder (5) include an output signal of a circuit in which the clock signal is not converted normally, a fault state signal, and a state signal of the phototransistor (202) being immersed in fuel or not immersed in fuel; the fault state signal includes LED failure, loss of function of the phototransistor (202), clock signal loss, and Vcc power supply interruption.
7. A fuel monitoring system according to claim 1, characterized in that: The trigger (6) is an HC273 eight-bit D-type trigger, which is used to capture the signal output by the trigger (6) and store it in the second shift register (7).
8. A fuel monitoring system according to claim 1, characterized in that: The logic gate circuit (8) is used to process the signal output by the second shift register (7); the digital filter (9) is used to eliminate false alarms caused by signal noise, and its effectiveness is controlled by adjusting its clock frequency.
9. A fuel monitoring system according to claim 1, characterized in that: The emitter follower (10) is also connected to an indicating device (11).
10. A fuel monitoring system according to claim 9, characterized in that: The emitter follower (10) is used to convert the received signal into an alarm signal and send it to the indicating device (11).