High-precision metering device for flow measurement and flowmeter calibration

Abstract

The invention discloses a high-precision metering device for flow measurement and flowmeter calibration, and belongs to the technical field of test and measurement. The device comprises an oil collecting tank, a metering oil tank and a control assembly, the metering oil tank is connected with the oil collecting tank through a pipeline, a flowmeter and an oil pump are arranged on the pipeline, the oil pump is located between the flowmeter and the oil collecting tank, and a heating assembly and a liquid level detection assembly are arranged in the metering oil tank. The control assembly is electrically connected with the oil pump, the flow meter, the heating assembly and the liquid level detection assembly. Flow measurement is achieved by dividing the reduction amount of the lubricating oil in the metering oil tank by the duration, it can be guaranteed that the reduction amount of the lubricating oil in the metering oil tank can be measured as long as the measurement duration is enough, the flow can be measured, measurement of micro flow is achieved, and practicability is high. The flow value measured by the metering oil tank is high in credibility and precision, can be used as a reference to effectively detect the measurement precision of the flowmeter, and can be quickly replaced and mounted on site and instantly verified, so that the test cost is greatly saved.

Description

Technical Field

[0001] The invention relates to a high-precision metering device for flow measurement and flow meter calibration, belonging to the technical field of test measurement. Background Art

[0002] Aircraft engine lubricating oil accessories are very critical parts of the engine. When the engine is running, the main shaft bearings, gears and other parts will generate a lot of heat and metal chips due to relative rotation, which is not conducive to the normal operation of bearings and gears. Therefore, it is required that the lubricating oil in the bearings and gears be kept circulating to lubricate the rotating parts and take away the heat and metal chips, which is extremely important to ensure the normal operation of the transmission system and the normal service life of the rotating parts.

[0003] In the aircraft engine accessory transmission system, the lubricating oil accessories are composed of a booster pump and a return oil pump. The booster pump is responsible for delivering the lubricating oil in the main oil tank to each lubrication point, and then the return oil pump is used to pump the lubricating oil from the lubrication point back to the main oil tank to form a lubricating oil cycle. The performance of the lubricating oil accessories determines the stability of the engine in high-altitude and long-duration operations. For this reason, it is necessary to carry out lubricating oil accessory performance tests to study the performance of the lubricating oil pump. During the test, it is necessary to study the performance of the pump at different speeds and different air pressures, and the flow value, as a specific parameter reflecting the performance of the lubricating oil pump, is the main object of the test study.

[0004] In order to accurately monitor the flow value, a flow meter is required for measurement, but the flow meter has a certain range. For a small flow less than the lower limit of the range, the flow meter cannot be accurately measured, and the flow meter needs to be regularly inspected to determine whether its measurement accuracy is distorted. The device of the present invention can replace the flow meter, accurately measure the small flow at a low speed of the lubricating oil pump, and can also be used to calibrate the flow meter. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a high-precision metering device for flow measurement and flow meter calibration.

[0006] The present invention is achieved through the following technical solutions:

[0007] A high-precision metering device for flow measurement and flow meter calibration comprises an oil collecting tank, a metering oil tank and a control component. The metering oil tank is connected to the oil collecting tank via a pipeline. The pipeline is provided with a flow meter and an oil pump, and the oil pump is located between the flow meter and the oil collecting tank. A heating component and a liquid level detection component are provided in the metering oil tank. The control component is electrically connected to the oil pump, the flow meter, the heating component and the liquid level detection component.

[0008] The pipeline is provided with a valve A, and the valve A is located between the flow meter and the metering oil tank.

[0009] The heating component is an electric heater.

[0010] The liquid level detection component is a liquid level gauge.

[0011] The liquid level gauge is a differential pressure liquid level gauge.

[0012] The control component is a computer.

[0013] A breathing valve is arranged on the top of the metering oil tank.

[0014] A refueling pipe is connected to the middle of the metering oil tank, one end of the refueling pipe is communicated with the inside of the metering oil tank, and the other end is arranged upward.

[0015] The metering oil tank is also connected to the bottom of the oil collecting tank through an oil replenishing pipe, and an oil replenishing pump and a valve B are provided on the oil replenishing pipe, and the oil replenishing pump is located between the valve B and the metering oil tank.

[0016] The metering oil tank is provided with a pressure sensor and a temperature sensor.

[0017] The beneficial effects of the present invention are:

[0018] 1. The flow measurement is achieved by dividing the reduction in the lubricating oil in the metering tank by the time, which eliminates the conversion error of the flowmeter eddy current signal-electrical signal and has high credibility. In addition, as long as the measurement time is long enough, the reduction in the lubricating oil in the metering tank can be measured, and the flow can be measured, thus realizing the measurement of tiny flow, which is highly practical.

[0019] 2. This device can measure a wide range of flow rates with high measurement accuracy. The computer stores the average volume flow calculation formula, which can realize automatic flow calculation. It is easy to use, fast and efficient.

[0020] 3. When the flow meter is connected, the flow value measured by the metering tank can be compared with the reading of the flow meter at different oil pump speeds to determine whether the accuracy of the flow meter is reliable and to verify whether the measurement accuracy of the flow meter is distorted. If distorted, the flow meter can be corrected to achieve the purpose of calibrating the flow meter.

[0021] 4. The flow value measured by the metering oil tank is highly reliable and accurate, and can be used as a benchmark to check the measurement accuracy of the flow meter. It can be quickly replaced on site and verified immediately, greatly saving the test cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention.

[0023] In the figure: 1-oil collecting tank, 2-pipeline, 3-oil pump, 4-flow meter, 5-valve A, 6-metering oil tank, 7-heating component, 8-filling pipe, 9-breathing valve, 10-liquid level detection component, 11-control component, 12-oil supply pipe, 13-valve B, 14-oil supply pump. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0025] like Figure 1 As shown, a high-precision metering device for flow measurement and flow meter calibration described in the present invention includes an oil collecting tank 1, a metering oil tank 6 and a control component 11. The metering oil tank 6 is connected to the oil collecting tank 1 through a pipeline 2. A flow meter 4 and an oil pump 3 are provided on the pipeline 2, and the oil pump 3 is located between the flow meter 4 and the oil collecting tank 1. A heating component 7 and a liquid level detection component 10 are provided in the metering oil tank 6. The control component 11 is electrically connected to the oil pump 3, the flow meter 4, the heating component 7 and the liquid level detection component 10. In order to solve the problem that when the flow meter 4 measures a small flow, the flow value cannot be accurately measured because the flow value is lower than the lower limit of the flow meter 4, the present invention first starts the heating component 7 through the control component 11 to heat the lubricating oil in the metering oil tank 6. After the temperature of the lubricating oil in the metering oil tank 6 rises to the required value, the speed of the oil pump 3 is set and the oil pump 3 is started through the control component 11. At the same time, the timing is performed through the control component 11, and the liquid level of the lubricating oil in the metering oil tank 6 is detected by the liquid level detection component 10. After the oil pump 3 is running, the lubricating oil in the metering oil tank 6 is extracted. After the oil pump 3 has been running stably for a period of time, the reduction in lubricating oil in any period of time can be calculated in combination with the inner cavity cross-sectional area of ​​the metering oil tank 6 and the change in its internal liquid level. Then, the average volume flow rate can be calculated by dividing the reduction in lubricating oil in the period by the length of the period. When the flow meter 4 is connected, the flow value measured by the metering tank 6 can be compared with the reading of the flow meter 4 at different oil pump 3 speeds to determine whether the accuracy of the flow meter 4 is reliable and to verify whether the measurement accuracy of the flow meter 4 is distorted. If distorted, the flow meter 4 is corrected to achieve the purpose of calibrating the flow meter 4.

[0026] The pipeline 2 is provided with a valve A5 , which is located between the flow meter 4 and the metering oil tank 6 .

[0027] The heating component 7 is an electric heater.

[0028] The liquid level detection component 10 is a liquid level meter.

[0029] The liquid level gauge is a differential pressure liquid level gauge, which is used to detect the liquid level in the metering oil tank 6 .

[0030] The control component 11 is a computer.

[0031] In order to improve the measurement accuracy of the metering oil tank 6, the errors in the calculation time and the calculated volume are required to be as small as possible. The time is timed by a computer, and the time from the start of measurement to the end of measurement is automatically calculated with an accuracy of 0.01s. The reduction in the lubricating oil in the metering oil tank 6 is calculated by combining the liquid level difference measured by the liquid level gauge and the cross-sectional area of ​​the inner cavity of the metering oil tank 6. In order to further improve the measurement accuracy of the liquid level in the metering oil tank 6, a differential pressure transmitter is used in conjunction with a differential pressure liquid level gauge to measure the liquid level difference.

[0032] A breathing valve 9 is provided on the top of the metering oil tank 6. The breathing valve 9 is used to balance the air pressure inside and outside the metering oil tank 6, ensuring the accuracy of the liquid level detection component 10 in measuring the lubricating oil level in the metering oil tank 6. During the test, if it is necessary to detect the pressure change in the metering oil tank 6, the breathing valve 9 is closed before the test to keep it in a closed state.

[0033] A refueling pipe 8 is connected to the middle of the metering oil tank 6 , one end of the refueling pipe 8 is communicated with the inside of the metering oil tank 6 , and the other end is arranged upward.

[0034] The metering oil tank 6 is also connected to the bottom of the oil collecting tank 1 through an oil replenishing pipe 12. An oil replenishing pump 14 and a valve B13 are provided on the oil replenishing pipe 12, and the oil replenishing pump 14 is located between the valve B13 and the metering oil tank 6. When the amount of lubricating oil in the metering oil tank 6 is low, the valve B13 is opened and the oil replenishing pump 14 is started to pump the lubricating oil in the oil collecting tank 1 into the metering oil tank 6, so as to replenish the lubricating oil in the metering oil tank 6.

[0035] The metering oil tank 6 is provided with a pressure sensor and a temperature sensor. The pressure sensor is used to detect the internal air pressure of the metering oil tank 6, and the temperature sensor is used to detect the temperature of the lubricating oil in the metering oil tank 6.

[0036] The high-precision metering device for flow measurement and flow meter calibration described in the present invention has the following usage process:

[0037] Fill the metering tank 6 with lubricating oil, heat the lubricating oil in the metering tank 6 to the required temperature through the electric heater, set the speed of the oil pump 3 through the computer and start the oil pump 3, and the lubricating oil in the metering tank 6 will be pumped by the oil pump 3. It is necessary to calculate the average volume flow rate q of any period during the operation of the oil pump 3 v When the differential pressure transmitter measures the differential pressure change value during this period of time, and converts it into the liquid level difference through the relationship. The amount of lubricating oil flowing out during this period of time is calculated by the liquid level difference and the inner diameter of the metering oil tank 6. The average volume flow rate q during this period of time can be obtained by dividing the amount of lubricating oil by the duration. v , the calculation formula is as follows:

[0038]

[0039] Wherein, d is the inner diameter of the metering oil tank 6, ΔH is the liquid level difference, Δτ is the duration of the calculated time period, ΔP is the pressure difference in the metering oil tank 6, and ρ is the density of the lubricating oil.

[0040] Obviously, the measured average volume flow rate q v The measurement accuracy is directly related to the measurement accuracy of the inner diameter, differential pressure, lubricating oil density and time of the metering oil tank 6. The straight section of the metering oil tank 6 is made of thick-walled pipe with a surface roughness grade of 3.2, a roundness and straightness grade of 7, a roundness processing accuracy of 0.05mm, and a straightness of 0.1mm.

[0041] The inner diameter of the metering oil tank 6 is measured by an inner diameter micrometer, and the measurement accuracy can reach 0.01mm. The maximum error of the inner diameter is the processing error of 0.05mm, and the ratio of the inner diameter to the diameter of the metering oil tank 6 is ±0.015%.

[0042] The differential pressure value is measured by a differential pressure level gauge, and the measurement accuracy is consistent with the accuracy of the differential pressure level gauge, which is ±0.075%.

[0043] The density value of the lubricating oil can be converted according to the measured current lubricating oil temperature. The data shows that the density of the lubricating oil is P=A-0.6T, and the temperature measurement accuracy is ±1°C. When the room temperature is 20°C, the density error is: ±0.07%.

[0044] The error accuracy of the duration is 0.1s. Taking 20s as the benchmark, the duration error is ±0.5%.

[0045] The comprehensive measurement error of the metering oil tank 6 is approximately: ±0.7%, which is lower than 1% and meets the requirements.

[0046] In addition, the volume measurement accuracy of the metering tank 6 can be calibrated by using the flow meter 4 on the pipeline. The volume measurement accuracy can reach ±0.5%, and the duration measurement error is ±0.5%. The comprehensive average volume flow rate q v The error is ±0.7%.

[0047] In summary, the measurement accuracy of the metering oil tank 6 is ±0.7%.

[0048] The metering oil tank 6 can measure the working condition of small flow rate. Under the working condition of small flow rate, as long as the measuring time is long enough, it can be ensured that the reduction amount of lubricating oil in the metering oil tank 6 can be measured, and the flow rate can be measured.

[0049] When the flow rate is large, it is necessary to ensure that the stable measurement time is not less than 20 seconds. When the effective volume of lubricating oil in the metering oil tank 6 is completely sucked out within 20 seconds, the maximum measurable flow rate is estimated to be about 288L / min.

[0050] The technical parameters of the flow measurement of the metering oil tank 6 are obtained, the measuring range is 1-288L / min, and the measuring accuracy is ±0.7%.

[0051] In addition, the flow meter 4 can be calibrated through the metering oil tank 6. When the flow meter 4 is connected, the flow value measured by the metering oil tank 6 can be compared with the reading of the flow meter 4 at different oil pump 3 speeds to determine whether the accuracy of the flow meter 4 is reliable and to verify whether the measurement accuracy of the flow meter 4 is distorted. If distorted, the flow meter 4 is corrected to achieve the purpose of calibrating the flow meter 4.

Claims

1. A high-precision metering device for flow measurement and flow meter calibration, characterized in that: The invention comprises an oil collecting tank (1), a metering oil tank (6) and a control component (11); the metering oil tank (6) is connected to the oil collecting tank (1) via a pipeline (2); a flow meter (4) and an oil pump (3) are provided on the pipeline (2); the oil pump (3) is located between the flow meter (4) and the oil collecting tank (1); a heating component (7) and a liquid level detection component (10) are provided in the metering oil tank (6); and the control component (11) is electrically connected to the oil pump (3), the flow meter (4), the heating component (7) and the liquid level detection component (10).

2. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: The pipeline (2) is provided with a valve A (5), and the valve A (5) is located between the flow meter (4) and the metering oil tank (6).

3. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: The heating component (7) is an electric heater.

4. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: The liquid level detection component (10) is a liquid level meter.

5. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: The liquid level gauge is a differential pressure liquid level gauge.

6. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: The control component (11) is a computer.

7. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: A breathing valve (9) is provided on the top of the metering oil tank (6).

8. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: A refueling pipe (8) is connected to the middle of the metering oil tank (6), one end of the refueling pipe (8) is communicated with the inside of the metering oil tank (6), and the other end is arranged upward.

9. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: The metering oil tank (6) is also connected to the bottom of the oil collecting tank (1) via an oil replenishing pipe (12); an oil replenishing pump (14) and a valve B (13) are provided on the oil replenishing pipe (12); and the oil replenishing pump (14) is located between the valve B (13) and the metering oil tank (6).

10. The high-precision metering device for flow measurement and flow meter calibration according to claim 1, characterized in that: The metering oil tank (6) is provided with a pressure sensor and a temperature sensor.

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