阅读说明：本技术 一种油品油位测量系统及方法 (Oil level measuring system and method for oil product ) 是由 杨瑞民 赵玉磊 范晓辉 木子尼·克劳迪奥 于 2021-06-28 设计创作，主要内容包括：一种油品油位测量系统及方法,包括处理器、低通滤波器、采样电阻、传感器、差分采集处理电路、混频模块和A/D转换电路；处理器分为两路,一路连接到混频模块,另一路依次连接低通滤波器、采样电阻和传感器,传感器接地；采样电阻的两端连接差分采集处理电路,差分采集处理电路连接混频模块,混频模块输出端连接A/D转换电路,A/D转换电路连接处理器。本发明通过测量油位传感器的阻抗,可以得到代表当前油位的准确的电容值,相比传统的测量,本发明测量的电容量消除了其中等效电阻的影响,从而提高了测量精度。(A system and a method for measuring oil level of oil product comprise a processor, a low-pass filter, a sampling resistor, a sensor, a differential acquisition processing circuit, a frequency mixing module and an A/D conversion circuit; the processor is divided into two paths, one path is connected to the frequency mixing module, the other path is sequentially connected with the low-pass filter, the sampling resistor and the sensor, and the sensor is grounded; the two ends of the sampling resistor are connected with a differential acquisition processing circuit, the differential acquisition processing circuit is connected with a frequency mixing module, the output end of the frequency mixing module is connected with an A/D conversion circuit, and the A/D conversion circuit is connected with a processor. The invention can obtain the accurate capacitance value representing the current oil level by measuring the impedance of the oil level sensor, and compared with the traditional measurement, the capacitance value measured by the invention eliminates the influence of equivalent resistance in the capacitance value, thereby improving the measurement precision.)

1. An oil level measuring system is characterized by comprising a processor (10), a low-pass filter (12), a sampling resistor (13), a sensor (14), a differential acquisition processing circuit (17), a mixing module (19) and an A/D conversion circuit (21); the processor (10) is divided into two paths, one path is connected to the frequency mixing module (19), the other path is sequentially connected with the low-pass filter (12), the sampling resistor (13) and the sensor (14), and the sensor (14) is grounded; the two ends of the sampling resistor (13) are connected with a differential acquisition processing circuit (17), the differential acquisition processing circuit (17) is connected with a mixing module (19), the output end of the mixing module (19) is connected with an A/D conversion circuit (21), and the A/D conversion circuit (21) is connected with the processor (10).

2. An oil level measuring system according to claim 1, characterized in that the sensor (14) is equivalent to an equivalent resistance (24) and a capacitive reactance (23), the equivalent resistance (24) and the capacitive reactance (23) being connected in parallel.

3. An oil level measuring system according to claim 1, wherein the processor (10) is adapted to generate a TTL excitation signal, and the low pass filter (12) has a limiting frequency which is less than 2 times the frequency of the TTL excitation signal.

4. An oil level measuring system according to claim 1, characterized in that the differential acquisition processing circuit (17) is used for making a vector difference between the signals at the two ends of the sampling resistor (13) to form a sinusoidal signal to be measured.

5. An oil level measuring system according to claim 1, characterized in that the mixing module (19) is used for multiplying the TTL excitation signal (11) and the sinusoidal signal to be measured, and forming an analog quantity signal through a filter circuit in the mixing module (19).

6. An oil level measuring system according to claim 5, characterized in that the filter circuit in the mixer module (19) contains a limiting frequency f₂The filter circuit and the multiplication circuit form a band-pass filter, and the limited frequency range of the band-pass filter is f₁-f₂,f₁+f₂]。

7. An oil level measuring system according to claim 5, characterized in that the analog quantity signal is passed through the multiplying circuit and the filtering circuit of the mixing module (19), and only the constant component after multiplication is retained.

8. An oil level measuring method, based on any one of claims 1 to 7, characterized in that the oil level measuring system comprises the following steps:

the processor (10) sends out a TTL excitation signal (11), and the TTL excitation signal is changed into a same-frequency sinusoidal signal A (15) after passing through a low-pass filter (12); the same-frequency sinusoidal signal A (15) passes through the sampling resistor (13) and the sensor to be tested (14) and then reaches the ground to form a test loop;

signals at two ends of a sampling resistor (13), namely a same-frequency sinusoidal signal A (15) and a same-frequency sinusoidal signal B (16), are converted into a sinusoidal signal to be detected (18) after passing through a differential acquisition processing circuit (17); a sinusoidal signal (18) to be tested passes through a frequency mixing module (19), and outputs an analog quantity signal (20), wherein the analog quantity signal comprises phase information between the sinusoidal signal (18) to be tested and a TTL excitation signal (11) and amplitude information of the sinusoidal signal; the analog quantity signal (20) is converted into a digital signal (22) by an analog-to-digital conversion circuit (21) and sent to the processor (10);

the capacitive reactance (23) of the sensor (14) to be measured represents the height of the liquid level in the oil tank, and the equivalent resistance (24) represents the quality of oil in the oil tank.

Technical Field

The invention relates to the field of liquid level measurement design, in particular to a system and a method for measuring oil level of an oil product.

Background

The residual oil quantity in the oil tank of the airplane is an important index for evaluating the cruising ability of the airplane and ensuring the flight safety, and the flight quality and the safety of the airplane can be improved by accurately measuring the residual oil quantity in the oil tank in real time in the flight process. The early-stage fuel measuring system of the airplane adopts a consumption meter sensor measuring technology, namely the fuel measuring system is arranged on a fuel supply pipeline to measure the fuel consumption; the second generation fighter plane in English, American and other countries adopts an analog oil quantity measuring device, namely, a capacitance type liquid level sensor is used for measuring the oil quantity in an oil tank; third generation aircraft widely adopt a measurement system combining oil quantity and consumption; at present, the fourth generation aircraft generally adopt a digital fuel oil measuring system. With the development of various technologies, digitization, intellectualization and integration become the main development trend of the future aircraft fuel measurement system.

The sensors currently used in aircraft fuel measurement systems are still capacitive fuel level sensors, which can be divided into two types: one is a fully immersed sensor, i.e. completely immersed in the fuel, and the other is a non-fully immersed sensor, i.e. the capacitance measuring module is placed outside the fuel tank.

At present, in order to reduce the imported energy and power consumption and ensure the safety of the fully-immersed sensor, a special capacitance measuring chip such as a CAV414 is generally adopted, however, the chip does not have a mature domestic product at present, so that the product of the type does not have complete independent intellectual property rights. Although the non-fully-immersed sensor does not strictly limit the introduced energy and power consumption, the flange plate is required to be used for installation, the flange plate and the measuring module are arranged outside the oil tank, and each oil quantity sensor is required to be provided with an installation hole in the wall of the oil tank, so that the whole structure of the oil tank can be greatly damaged for a medium-sized airplane needing to be provided with dozens of oil quantity sensors. Therefore, there is a need for a fuel level sensor that is fully immersed and does not rely on foreign chips.

In addition, at present, no matter the fuel quantity sensor is fully immersed or not, the fuel quantity sensor can only measure the residual fuel quantity in the fuel tank, and the quality of the fuel oil cannot be reflected at the same time. In the prior art, the functions of oil level height measurement and low oil level alarm are integrated, and the function of measuring the quality of fuel oil is not included. As solid impurity particles and moisture are possibly accumulated in the fuel tank along with the increase of the flight time of the airplane, the quality of fuel is influenced, and the quality of the fuel influences the flight quality to a certain extent, so that the fuel quality is necessarily monitored while the fuel quantity in the fuel tank of the airplane is measured.

Disclosure of Invention

The invention aims to provide an oil level measuring system and method for oil products, so as to solve the problems.

In order to achieve the purpose, the invention adopts the following technical scheme:

an oil level measuring system of oil products comprises a processor, a low-pass filter, a sampling resistor, a sensor, a differential acquisition processing circuit, a frequency mixing module and an A/D conversion circuit; the processor is divided into two paths, one path is connected to the frequency mixing module, the other path is sequentially connected with the low-pass filter, the sampling resistor and the sensor, and the sensor is grounded; the two ends of the sampling resistor are connected with a differential acquisition processing circuit, the differential acquisition processing circuit is connected with a frequency mixing module, the output end of the frequency mixing module is connected with an A/D conversion circuit, and the A/D conversion circuit is connected with a processor.

Further, the sensor is equivalent to an equivalent resistor and a capacitive reactance which are connected in parallel.

Further, the processor is configured to generate a TTL excitation signal, and the low pass filter has a limiting frequency that is less than 2 times the frequency of the TTL excitation signal.

Furthermore, the differential acquisition processing circuit is used for making a vector difference on signals at two ends of the sampling resistor to form a sinusoidal signal to be detected.

Furthermore, the frequency mixing module is used for multiplying the TTL excitation signal and the sine signal to be measured, and forming an analog quantity signal through a filter circuit in the frequency mixing module.

Further, the filter circuit in the mixer module has a limiting frequency f₂The filter circuit and the multiplication circuit form a band-pass filter, and the limited frequency range of the band-pass filter is f₁-f₂,f₁+f₂]。

Furthermore, after the analog quantity signal passes through a multiplication circuit and a filter circuit of the mixing module, only the constant component after multiplication is reserved.

Further, the oil level measuring method of the oil product comprises the following steps:

the processor sends out TTL excitation signals, and the TTL excitation signals are changed into same-frequency sinusoidal signals A after passing through a low-pass filter; the same-frequency sinusoidal signal A passes through a sampling resistor and a sensor to be tested and then reaches the ground to form a test loop;

sampling signals at two ends of a resistor, namely a same-frequency sinusoidal signal A and a same-frequency sinusoidal signal B, and converting the signals into sinusoidal signals to be detected after passing through a differential acquisition processing circuit; the sinusoidal signal to be tested passes through the frequency mixing module and outputs an analog quantity signal, wherein the analog quantity signal comprises phase information between the sinusoidal signal to be tested and a TTL excitation signal and amplitude information of the sinusoidal signal to be tested; the analog quantity signal is converted into a digital signal by an analog-to-digital conversion circuit and sent to the processor.

The capacitive reactance of the sensor to be measured represents the height of the liquid level in the oil tank, and the equivalent resistance represents the quality of oil in the oil tank.

Compared with the prior art, the invention has the following technical effects:

the invention can obtain the accurate capacitance value representing the current oil level by measuring the impedance of the oil level sensor, compared with the traditional measurement, the capacitance value measured by the invention eliminates the influence of equivalent resistance in the capacitance value, thereby improving the measurement precision;

according to the invention, the equivalent resistance can be obtained by measuring the impedance of the fuel level sensor, so that the oil quality of the fuel in the fuel tank, including cooling water generated by icing of the fuel tank, metal chips and other impurities mixed in the fuel tank can be judged, and the more the impurities are, the worse the oil quality of the fuel in the fuel tank is, the smaller the equivalent resistance is.

According to the invention, the oil level is measured, and meanwhile, the quality information of the fuel in the current fuel tank can be obtained, so that the calculation accuracy of the remaining fuel use time is greatly improved;

the invention can obtain the quality information of the oil in the current oil tank while measuring the oil level, thereby achieving the purpose of cleaning impurities in the oil tank in a planned way.

Drawings

Fig. 1 is a schematic diagram of the patent.

List of reference numerals

10 a processor; 11 TTL excitation signals; 12 a low-pass filter; 13 sampling a resistor; 14 a sensor to be tested; 15 same-frequency sinusoidal signals A; 16 same-frequency sinusoidal signals B; 17 a differential acquisition processing circuit; 18 sine signals to be detected; 19 a frequency mixing module; 20 analog quantity signals; 21 analog-to-digital conversion circuit; 22 a digital signal; 23 sensor capacitance; 24 sensor resistance; 25 a microprocessor.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

fig. 1 includes a processor 10, wherein the processor 10 sends a TTL excitation signal 11, which is converted into an intra-frequency sinusoidal signal a15 after passing through a low-pass filter 12.

Specifically, the method comprises the following steps:

the device comprises a processor 10, a low-pass filter 12, a sampling resistor 13, a sensor 14 to be tested, a differential acquisition processing circuit 17, a mixing module 19 and an A/D conversion circuit 21; the processor 10 is divided into two paths, one path is connected to the frequency mixing module 19, the other path is sequentially connected with the low-pass filter 12, the sampling resistor 13 and the sensor 14, and the sensor 14 is grounded; the two ends of the sampling resistor 13 are connected with a differential acquisition processing circuit 17, the differential acquisition processing circuit 17 is connected with a frequency mixing module 19, the output end of the frequency mixing module 19 is connected with an A/D conversion circuit 21, and the A/D conversion circuit 21 is connected with the processor 10.

The same-frequency sinusoidal signal A15 passes through the sampling resistor 13 and the sensor 14 to be tested and then reaches the ground to form a test loop.

The sensor 14 to be measured consists of a sensor capacitor 23 and a sensor resistor 24, the size of the sensor capacitor 23 represents the height of the liquid level in the oil tank, and the size of the sensor resistor 24 represents the quality of the oil in the oil tank.

Signals at two ends of the sampling resistor 13, namely a same-frequency sinusoidal signal A15 and a same-frequency sinusoidal signal B16 are converted into a sinusoidal signal 18 to be detected after passing through the differential acquisition processing circuit 17.

The sinusoidal signal 18 to be measured passes through the frequency mixing module 19, and outputs a path of analog quantity signal 20, where the analog quantity signal includes phase information between the sinusoidal signal 18 to be measured and the TTL excitation signal 11 and amplitude information of the analog quantity signal.

The analog signal 20 is converted into a digital signal 22 by an analog-to-digital conversion circuit 21 and sent to the processor 10.

The size of the sinusoidal signal 17 to be measured depends on the sizes of the same-frequency sinusoidal signal A15 and the same-frequency sinusoidal signal B16.

The size of co-frequency sinusoidal signal A15 and co-frequency sinusoidal signal B16 depends on the relative sizes of sampling resistor 13 and the sensor 14 to be tested.

The relative sizes of the sampling resistor 13 and the sensor to be tested 14 depend on the actual impedance of the sensor to be tested.

The actual impedance of the sensor to be tested depends on the changes caused by the changes in the external oil level of the sensor.

In the embodiment of fig. 1, the processor 10, the differential acquisition processing circuit 17, the mixing module 19, and the analog-to-digital conversion circuit 21 may be implemented by separate hardware circuits, or may be integrated into the microprocessor 25.