A calibration method for a fuel measurement system without adding or draining oil after replacing a measurement component

Abstract

The present invention discloses a calibration method for a fuel measurement system without adding or draining fuel after replacing a measurement component. In the state of the airborne fuel tank being empty, a simulation detection tooling is established, and the zero-position capacitance sampling value of the fuel quantity is measured by connecting the simulation detection tooling with the fuel quantity detection device; in the state of the airborne fuel tank being full, the full-position capacitance sampling value of the fuel quantity is detected by the airborne fuel quantity capacitance sensor and the fuel quantity detection device; then, the difference between the full-position capacitance sampling value of the fuel quantity and the zero-position capacitance sampling value of the fuel quantity is calculated to obtain the capacitance calibration difference. Then, after the fuel quantity detection device is replaced, the full-position capacitance calibration value can be obtained by adding the zero-position capacitance calibration value of the fuel quantity detection device and the capacitance calibration difference, avoiding the method of adding or draining fuel to measure the full-position capacitance calibration value, improving the calibration efficiency, and avoiding fuel waste at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel quantity calibration, and particularly relates to a calibration method for a fuel measurement system without refueling and draining after replacing a measurement component. Background Art

[0002] At present, most aircraft fuel measurement systems adopt linear capacitive fuel quantity measurement technology. After the product is installed on the aircraft, due to parameter differences in each link of the fuel quantity sensor signal conversion, the system consistency is poor. It is difficult to completely eliminate the differences in the fuel quantity sensor, the distributed capacitance of the signal transmission cable, and the component parameters in actual engineering applications. Therefore, after the fuel measurement system is installed on the aircraft or after replacing the fuel quantity measurement component of the system, it is necessary to calibrate the fuel measurement system by refueling and draining, that is, to perform a zero position calibration by draining the aircraft fuel tank to an empty fuel state, and to perform a full position calibration by filling the aircraft fuel tank with fuel. Since the fuel measurement system needs to be calibrated by refueling and draining the aircraft every time the fuel quantity measurement component is replaced. This not only has a large workload, but also causes great waste of aircraft fuel during frequent refueling and draining, increases the ground crew work burden, and at the same time increases the preparation time for the aircraft to take off again, affecting the aircraft's attendance rate. Summary of the Invention

[0003] The purpose of the present invention is to provide a calibration method for a fuel measurement system without refueling and draining after replacing a measurement component, obtain a capacitance calibration difference on the basis of ensuring measurement consistency, and then add the capacitance calibration difference to the zero position capacitance calibration value of the fuel quantity detection device to obtain the full position capacitance calibration value of the fuel quantity measurement device, avoiding the need to re-calibrate by refueling and draining after replacing the fuel quantity measurement device.

[0004] The present invention is achieved by the following technical solutions:

[0005] A calibration method for a fuel measurement system without refueling and draining after replacing a measurement component, which is realized based on a fuel quantity measurement device with a built-in digital bridge circuit, includes the following steps:

[0006] Step 1: Make the digital quantities of the measurement bridge arm and the balance bridge arm of the digital bridge circuit in the fuel quantity measurement device consistent;

[0007] Step 2: Establish an analog detection tooling consistent with the airborne fuel quantity capacitance sensor and the airborne fuel quantity measurement cable, connect the analog detection tooling to the fuel quantity measurement device, and collect the fuel quantity zero position capacitance sampling value when the analog detection tooling is located inside the airborne fuel tank with empty fuel;

[0008] Step 3: Inject fuel into the airborne fuel tank to the full position liquid level, and then collect the fuel quantity full position capacitance sampling value output by the airborne fuel quantity capacitance sensor inside the full fuel airborne fuel tank through the fuel quantity measurement device;

[0009] Step 4: Calculate the difference between the full - level capacitance sampling value and the zero - level capacitance sampling value of the fuel quantity to obtain the capacitance calibration difference;

[0010] Step 5: After replacing the measuring component, add the factory zero - level capacitance calibration value of the measuring component to the capacitance calibration difference to obtain the full - level capacitance calibration value of the measuring component.

[0011] In the state of the fuel tank being empty, before the product leaves the factory, a simulated detection tooling is used to simulate the fuel quantity zero - level capacitance sampling value transmitted from the airborne fuel quantity capacitance sensor to the fuel quantity measuring device through the airborne fuel quantity measuring cable, and the fuel quantity measuring device records this fuel quantity zero - level capacitance sampling value. At the same time, the sampling consistency of the digital bridge circuit in the fuel quantity measuring device is controlled, and the sampling value linearity curve of each fuel quantity measuring device is controlled within the standard range where the linearity is less than or equal to 0.5%. After the fuel quantity measuring device is installed on the aircraft, the distributed capacitance generated by the laying path and binding fixation of the airborne fuel quantity measuring cable and the error of the airborne fuel quantity capacitance sensor will cause zero - level sampling error. After the laying path and binding method of the airborne fuel quantity measuring cable are fixed, by actually measuring the capacitance value through the airborne fuel quantity capacitance sensor and performing consistency fitting on the simulated detection tooling, the zero - level sampling error can be eliminated.

[0012] In the state of the fuel tank being full, due to the differences in the fuel quality and environmental temperature on the aircraft, there is a full - level sampling error, which cannot be eliminated and can only be calibrated for the full - level on the aircraft. Since the sampling linearity consistency of the digital bridge circuit in the fuel quantity measuring device is ensured in advance, it can be ensured that when the capacitance increment of the airborne fuel quantity capacitance sensor is the same for different fuel quantity measuring devices, the signal sampling value increments of each fuel quantity measuring device are consistent. Therefore, the capacitance calibration difference can be determined from the zero - level capacitance sampling value and the full - level capacitance sampling value.

[0013] After replacing the fuel quantity detection device, only by adding the zero - level capacitance calibration value determined when the fuel quantity detection device leaves the factory to the capacitance calibration difference, the full - level capacitance calibration value of the fuel quantity detection device can be obtained, thus avoiding the process of re - measuring the full - level capacitance calibration value by adding and discharging fuel in the traditional way.

[0014] To better implement the present invention, further, the specific steps of Step 2 include:

[0015] Step 2.1: Establish a simulated sensor according to the structure of the airborne fuel quantity capacitance sensor, and set an adjustable capacitor in the simulated sensor;

[0016] Step 2.2: Establish a simulated cable according to the layout parameters of the airborne fuel quantity measuring cable, and connect the adjustable capacitor in the simulated sensor to the fuel quantity measuring device through the simulated cable;

[0017] Step 2.3: Place the analog sensor with the built-in adjustable capacitor inside the airborne fuel tank with empty oil, and adjust the capacitance value of the adjustable capacitor until the digital signal of the capacitance value output by the adjustable capacitor collected by the fuel quantity measurement device is consistent with the digital signal of the capacitance value output by the airborne fuel quantity capacitance sensor;

[0018] Step 2.4: Store the digital signal of the capacitance value of the adjustable capacitor at this time as the fuel quantity zero position capacitance sampling value.

[0019] To better implement the present invention, further, an analog output interface is provided on the analog sensor, and the analog output interface is consistent with the output interface of the airborne fuel quantity capacitance sensor.

[0020] To better implement the present invention, further, in step 2.2, the layout parameters of the airborne fuel quantity measurement cable include the cable laying path, the cable binding and fixing position, the cable material, and the cable diameter.

[0021] To better implement the present invention, further, in step 1, the excitation current signals of the measurement bridge arm and the balance bridge arm are adjusted to a unified excitation current value by adjusting the potentiometer.

[0022] To better implement the present invention, further, the excitation current value is 80 mA - 100 mA.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] The present invention pre-calibrates and unifies the excitation currents of the detection bridge arm and the balance bridge arm of the digital bridge circuit in the fuel quantity detection device, thereby ensuring the sampling linear consistency of the digital bridge circuit in the fuel quantity detection device to ensure the consistency of the subsequent detected capacitance values; then, in the state of the airborne fuel tank being empty, a consistent analog detection tooling is established corresponding to the airborne fuel quantity capacitance sensor and the airborne fuel quantity measurement cable, and the analog detection tooling is connected to the fuel quantity detection device to obtain the fuel quantity zero position capacitance sampling value; in the state of the airborne fuel tank being full, the fuel quantity full position capacitance sampling value is obtained by directly connecting the airborne fuel quantity capacitance sensor to the fuel quantity detection device, and then the capacitance calibration difference is calculated through the fuel quantity zero position capacitance sampling value and the fuel quantity full position capacitance sampling value. After replacing the fuel quantity detection device, only by adding the zero position capacitance calibration value of the fuel quantity detection device and the capacitance calibration difference can the full position capacitance calibration value of the replaced fuel quantity detection device be obtained, thereby avoiding the measurement of the full position capacitance calibration value by the method of frequent fuel addition and discharge, greatly improving the calibration efficiency, and at the same time avoiding fuel waste. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the flow steps of the present invention. Detailed Embodiments

[0026] Example 1:

[0027] A calibration method for a fuel measurement system without refueling and draining after replacing a measurement component in this example is implemented based on an oil quantity measurement device with a built-in digital bridge circuit, as Figure 1 shown, and includes the following steps:

[0028] Step 1: Make the digital quantity adjustments of the measurement bridge arm and the balance bridge arm of the digital bridge circuit in the oil quantity measurement device consistent to ensure the subsequent sampling consistency of the capacitance value by the digital bridge circuit and reduce the influence brought by the sampling error of the digital bridge circuit.

[0029] Step 2: Establish an analog detection tooling consistent with the airborne oil capacitance sensor and the airborne oil measurement cable, connect the analog detection tooling to the oil quantity measurement device, and collect the oil quantity zero-position capacitance sampling value when the analog detection tooling is inside the airborne fuel tank with empty oil.

[0030] In the state of the airborne fuel tank being empty, the airborne oil capacitance sensor transmits a capacitance signal to the input end of the oil quantity measurement device through the airborne oil measurement cable, and it is converted into a digital quantity signal by the digital bridge circuit in the oil quantity measurement device. According to the actual measurement data of the airborne oil capacitance sensor and the airborne oil measurement cable, an analog detection tooling with consistency is manufactured, the analog detection tooling is connected to the oil quantity measurement device, and a zero-position calibration instruction is sent to the oil quantity measurement device. The data memory inside the oil quantity measurement device records the oil quantity zero-position capacitance sampling values received from the analog detection tooling for each measurement channel.

[0031] Step 3: Inject fuel into the airborne fuel tank until it reaches the full-level liquid surface, and then collect the oil quantity full-level capacitance sampling value output by the airborne oil capacitance sensor inside the full-fuel airborne fuel tank at this time through the oil quantity measurement device.

[0032] Step 4: Calculate the difference between the oil quantity full-level capacitance sampling value and the oil quantity zero-position capacitance sampling value to obtain the capacitance calibration difference.

[0033] Before the aircraft leaves the factory, a full-fuel calibration is carried out. After the airborne system is installed on the aircraft and powered on for inspection, after the system works normally, fuel is added to the airborne fuel tank until it reaches the full-level calibration liquid surface of the airborne oil capacitance sensor. A full-level calibration instruction is sent to the oil quantity measurement device. The data memory inside the oil quantity measurement device records the full-level capacitance sampling values for each measurement channel, and at the same time automatically calculates the calibration differences for each measurement channel. The calibration difference is equal to the difference between the oil quantity full-level capacitance sampling value and the oil quantity zero-position capacitance sampling value. After the full-fuel calibration, the calibration differences of the on-board environment stored in the oil quantity measurement device are uploaded to the system data backup device for backup through an instruction.

[0034] Step 5: After replacing the measurement component, add the factory zero-position capacitance calibration value of the measurement component to the capacitance calibration difference to obtain the full-position capacitance calibration value of the measurement component.

[0035] The oil quantity measurement device has completed zero-position calibration before leaving the factory, and the in-factory zero-position capacitance calibration value can be consistent with the zero-position capacitance calibration value after installation. After replacing the oil quantity measurement device on the aircraft, it is not necessary to perform zero-position calibration again. At the same time, during product debugging, the consistency of the sampling data of the digital bridge circuit in the oil quantity measurement device is ensured, so that under the condition of the same capacitance increment of the on-board oil quantity capacitance sensor, the signal sampling value increments of each oil quantity measurement device are consistent. Therefore, by instructing to download the calibration difference of each measurement channel from the system data backup device to the replaced oil quantity measurement device, and adding it to the zero-position capacitance calibration value of each measurement channel recorded in the internal data memory of the oil quantity measurement device, the full-position capacitance calibration value can be obtained. The function of replacing the oil quantity measurement device and completing the on-board zero-full calibration without the need for aircraft refueling and defueling operations is realized.

[0036] Embodiment 2:

[0037] On the basis of Embodiment 1, this embodiment is further optimized. The specific steps of Step 2 include:

[0038] Step 2.1: Establish a simulated sensor according to the structure of the on-board oil quantity capacitance sensor, and set an adjustable capacitor in the simulated sensor.

[0039] Step 2.2: Establish a simulated cable according to the layout parameters of the on-board oil quantity measurement cable, and connect the adjustable capacitor in the simulated sensor to the oil quantity measurement device through the simulated cable.

[0040] Step 2.3: Place the simulated sensor with the built-in adjustable capacitor inside the on-board fuel tank with empty fuel, and adjust the capacitance value of the adjustable capacitor until the capacitance value digital signal output by the adjustable capacitor collected by the oil quantity measurement device is consistent with the capacitance value digital signal output by the on-board oil quantity capacitance sensor.

[0041] Step 2.4: Store the capacitance value digital signal of the adjustable capacitor at this time as the oil quantity zero-position capacitance sampling value.

[0042] Furthermore, an analog output interface is provided on the simulated sensor, and the analog output interface is the same as the output interface of the on-board oil quantity capacitance sensor.

[0043] Furthermore, in Step 2.2, the layout parameters of the on-board oil quantity measurement cable include the cable laying path, the cable binding and fixing position, the cable material, and the cable diameter.

[0044] Other parts of this embodiment are the same as those of Embodiment 1, so they will not be elaborated here.

[0045] Embodiment 3:

[0046] On the basis of the above Embodiment 1 or 2, this embodiment is further optimized. In step 1, the excitation current signals of the measurement bridge arm and the balance bridge arm are adjusted to the same excitation current value by adjusting the potentiometer.

[0047] Furthermore, the excitation current value is 80 mA - 100 mA.

[0048] Other parts of this embodiment are the same as those of the above Embodiments 1 - 3, so they will not be elaborated here.

[0049] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A calibration method for a fuel measurement system without adding or draining oil after replacing a measurement component, which is implemented based on an oil quantity measurement device with a built-in digital bridge circuit. Characterized in that: It includes the following steps: Step 1: Make the digital quantities of the measurement bridge arm and the balance bridge arm of the digital bridge circuit in the oil quantity measurement device consistent. Step 2: Establish an analog detection tooling that is consistent with the airborne oil capacitance sensor and the airborne oil measurement cable, connect the analog detection tooling to the oil quantity measurement device, and collect the oil quantity zero-position capacitance sampling value when the analog detection tooling is inside the airborne fuel tank with empty oil. Specifically, it includes: Step 2.1: Establish an analog sensor according to the structure of the airborne oil capacitance sensor, and set an adjustable capacitor in the analog sensor. Step 2.2: Establish an analog cable according to the layout parameters of the airborne oil measurement cable, and connect the adjustable capacitor in the analog sensor to the oil quantity measurement device through the analog cable. Step 2.3: Place the analog sensor with the built-in adjustable capacitor inside the airborne fuel tank with empty oil, and adjust the capacitance value of the adjustable capacitor until the capacitance value digital signal output by the adjustable capacitor collected by the oil quantity measurement device is consistent with the capacitance value digital signal output by the airborne oil capacitance sensor. Step 2.4: Store the capacitance value digital signal of the adjustable capacitor at this time as the oil quantity zero-position capacitance sampling value. Step 3: Inject fuel into the airborne fuel tank until it reaches the full-level liquid surface, and then collect the oil quantity full-position capacitance sampling value output by the airborne oil capacitance sensor inside the airborne fuel tank with full oil through the oil quantity measurement device. Step 4: Calculate the difference between the oil quantity full-position capacitance sampling value and the oil quantity zero-position capacitance sampling value to obtain the capacitance calibration difference. Step 5: After replacing the measurement component, add the factory zero-position capacitance calibration value of the measurement component to the capacitance calibration difference to obtain the full-position capacitance calibration value of the measurement component.

2. A calibration method for a fuel measurement system without adding or draining oil after replacing a measurement component according to claim 1. Characterized in that: An analog output interface is provided on the analog sensor, and the analog output interface is consistent with the output interface of the airborne oil capacitance sensor.

3. A calibration method for a fuel measurement system without adding or draining oil after replacing a measurement component according to claim 2. Characterized in that: In step 2.2, the layout parameters of the airborne oil measurement cable include the cable laying path, the cable binding and fixing position, the cable material, and the cable diameter.

4. A calibration method for a fuel measurement system without adding or draining oil after replacing a measurement component according to any one of claims 1-3. Characterized in that: In step 1, the excitation current signals of the measurement bridge arm and the balance bridge arm are adjusted to a unified excitation current value by adjusting the potentiometer.

5. A calibration method for a fuel measurement system without adding or draining oil after replacing a measurement component according to claim 4. Characterized in that: The excitation current value is 80 mA - 100 mA.

Images