A low shear rate measuring device for a rotational viscometer based on a special rotor and infrared photoelectric switch

Abstract

The invention discloses a low shear rate metering device of a rotational viscometer based on a special rotor and an infrared photoelectric switch, comprising a power supply, a single-chip microcomputer controller, a circular grid subdivision unit, a fast Fourier transform subdivision unit, a base vertical bar and a cross bar, the circular grid subdivision unit comprises a motor, a rotating shaft and a rotor, the fast Fourier transform subdivision unit comprises a halogen tungsten lamp light source, a collimating lens, a right angle prism, a focusing lens and a photodetector, the circular grid subdivision unit is arranged on one side of the fast Fourier transform subdivision unit, the vertical bar is fixedly arranged on the base, the cross bar comprises a first cross bar, a second cross bar and a third cross bar, the first cross bar, the second cross bar and the third cross bar are all arranged on the left side of the vertical bar, and the power supply, the photodetector and the motor are all connected to the single-chip microcomputer controller. The invention manufactures a special rotor made of a main material of polypropylene with 40 gears evenly distributed, so that it is attached to the rotor rotating shaft, and the movement of the viscometer rotor rotating shaft drives the rotation of the special rotor.

Description

Technical Field

[0001] The invention relates to the technical field of chemical engineering, and in particular to a low shear rate metering device of a rotational viscometer based on a special rotor and an infrared photoelectric switch. Background Art

[0002] The rotational viscometer is a special instrument used to measure the viscous resistance and dynamic viscosity of liquids. When the rotational viscometer is working, it is necessary to select a suitable rotor or speed. The rotor rotates at a constant speed around the central axis under the power provided by the motor. The rotor will generate a reaction force in the measured fluid due to the viscous resistance. The purpose of measuring the fluid viscosity is achieved through the dynamic balance of torque and fluid viscous resistance. Simply put, the rotational viscometer measures the viscosity of the liquid by rotating the internal rotor to generate shear stress. The faster the rotor rotates, the higher the shear rate generated. When measuring, it is usually necessary to select different speeds to measure the viscosity value at different shear rates. This is because the rheological properties of the liquid are different at different shear rates, which leads to differences in the measurement results at different shear rates. At the same time, the rheological properties of some liquids will change with the change of shear rate. Therefore, it is necessary to adjust the shear rate according to the actual situation and perform multiple measurements to ensure that the measured viscosity value is accurate and reliable.

[0003] When the rotational viscometer uses a low shear rate to test sample viscosity, such as 1 / 1000~200 s -1 ,The test error of the shear rate achieved by conventional ,instruments is large, resulting in inaccurate viscosity results of the ,tested substance under low shear rate conditions. The traceability calibration of ,low shear rate of such instruments has not been solved.

[0004] In view of the above problems, the present invention provides a low shear rate metering device of a rotational viscometer based on a special rotor and an infrared photoelectric switch for achieving accurate tracing of low shear rates. Summary of the invention

[0005] The invention provides a low shear rate metering device of a rotational viscometer based on a special rotor and an infrared photoelectric switch for realizing accurate tracing of low shear rates.

[0006] The purpose of the present invention is to provide a low shear rate metering device of a rotational viscometer based on a special rotor and an infrared photoelectric switch, comprising a power supply, a single-chip microcomputer controller, a circular grid subdivision unit, a fast Fourier transform subdivision unit, a base vertical bar and a horizontal bar, the circular grid subdivision unit comprises a motor, a rotating shaft and a rotor, the fast Fourier transform subdivision unit comprises a halogen tungsten lamp light source, a collimating lens, a right-angle prism, a focusing lens and a photodetector, the circular grid subdivision unit is arranged on one side of the fast Fourier transform subdivision unit, the vertical bar is fixedly arranged on the base, the horizontal bar comprises a first horizontal bar, a second horizontal bar and a third horizontal bar, the first horizontal bar, the second horizontal bar and the third horizontal bar are all arranged on the left side of the vertical bar, and the power supply, the photodetector, the halogen tungsten lamp light source and the motor are all connected to the single-chip microcomputer controller.

[0007] Furthermore, the output shaft of the motor is connected to the rotating shaft, the rotor is sleeved on the rotating shaft, and the motor adopts an L298N module as a driving unit.

[0008] Furthermore, the tungsten halogen light source is fixedly arranged on the first crossbar, the collimating lens is fixedly arranged on the second crossbar, and the right-angle prism, the focusing lens and the photoelectric detector are fixedly arranged on the third crossbar in sequence from left to right.

[0009] Furthermore, the power supply and the single-chip microcomputer controller are integrated in the motor, and the single-chip microcomputer controller adopts an STM32 single-chip microcomputer as a controller.

[0010] The present invention has the following advantages: The present invention manufactures a special rotor made of polypropylene as the main material with 40 gears evenly distributed, so that it is attached to the rotor rotating shaft, and the movement of the viscometer rotor rotating shaft drives the rotation of the special rotor. Through this special rotor, the rotation speed of the low shear rate rotor is amplified 40 times. Furthermore, a Fourier transform infrared optical path modulation switch is integrated in the special rotor, and infrared light is irradiated onto the special rotor gear. The Fourier transform principle is used to realize the precise subdivision of the circular grating of infrared light on the gear, and the subdivision ratio can reach 128 times. Based on this, a circular grating subdivision unit and a fast Fourier transform subdivision unit are established to achieve accurate tracing of low shear rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a principle block diagram of the present invention;

[0012] Figure 2 It is a structural schematic diagram of the present invention;

[0013] Figure 3 It is a schematic diagram of a circular grid subdivision unit of the present invention;

[0014] Figure 4 A schematic diagram of a fast Fourier transform subdivision unit of the present invention;

[0015] Figure 5 A top view of the present invention;

[0016] Figure 6 It is the circuit diagram of L298N driver module of the present invention;

[0017] Figure 7 It is a time domain signal diagram of the present invention.

[0018] In the figure: 1. power supply; 2. single-chip microcomputer controller; 3. motor; 4. rotating shaft; 5. rotor; 6. halogen tungsten lamp light source; 7. collimating lens; 8. right-angle prism; 9. focusing lens; 10. photodetector; 11. base; 12. third cross bar; 13. second cross bar; 14. first cross bar; 15. vertical bar. DETAILED DESCRIPTION

[0019] The invention provides a low shear rate metering device of a rotational viscometer based on a special rotor and an infrared photoelectric switch, comprising a power supply 1, a single-chip microcomputer controller 2, a circular grating subdivision unit, a fast Fourier transform subdivision unit, a base 11, a vertical rod 15 and a horizontal rod, wherein the circular grating subdivision unit comprises a motor 3, a rotating shaft 4 and a rotor 5, the fast Fourier transform subdivision unit comprises a halogen tungsten lamp light source 6, a collimating lens 7, a right-angle prism 8, a focusing lens 9 and a photodetector 10, the circular grating subdivision unit is arranged on one side of the fast Fourier transform subdivision unit, the vertical rod 15 is fixedly arranged on the base 11, the horizontal rod comprises a first horizontal rod 14, a second horizontal rod 13 and a third horizontal rod 12, the first horizontal rod 14, the second horizontal rod 13 and the third horizontal rod 12 are all arranged on the left side of the vertical rod 15, and the power supply 1, the photodetector 10, the halogen tungsten lamp light source 6 and the motor 3 are all connected to the single-chip microcomputer controller 2.

[0020] In this embodiment, the output shaft of the motor 3 is connected to the rotating shaft 4, the rotor 5 is sleeved on the rotating shaft 4, and the motor 3 uses the L298N module as a driving unit.

[0021] In this embodiment, the halogen tungsten lamp light source 6 is fixedly disposed on the first crossbar 14, the collimating lens 7 is fixedly disposed on the second crossbar 13, and the right-angle prism 8, the focusing lens 9 and the photodetector 10 are fixedly disposed on the third crossbar 12 in sequence from left to right.

[0022] In this embodiment, the power supply 1 and the single-chip controller 2 are integrated in the motor 3, and the single-chip controller 2 uses an STM32 single-chip microcomputer as a controller.

[0023] In this embodiment, the high-intensity light source emits infrared light that irradiates the tooth surface of the rotor 5, passes through the collimating lens 7, the right-angle prism 8 and the focusing lens 9, and is then captured by the photodetector 10 and converted into a Fourier transform infrared spectrum.

[0024] In the present embodiment, L298N is a motor driver chip having the characteristics of high operating voltage, large output current, strong driving capability, low heat generation, and strong anti-interference capability. It is packaged with 15 pins and can accept standard TTL logic level signals to drive motor 3. The L298N module has two enable control terminals. The circuit working mode can be dynamically adjusted by plugging in the jumper cap on the board without being affected by the input signal. It has a logic power input terminal. At the same time, a Hall encoder is used to measure the displacement of the motor transmission in the motor system, and the rotation speed of the motor 3 is calculated through the displacement. The rotating shaft 4 is connected to the motor 3, and the motor 3 drives the rotating shaft 4 to rotate, and the rotation speed is the same as the actual rotation rate of the rotor 5 in the rotational viscometer. The rotor 5 is a disc-shaped gear with a central hole, made of polypropylene, and has 40 teeth, such as Figure 5 When the motor drives the rotating shaft and rotor at a speed of 1 rps, the gear-like structure of the rotor divides the circumference of the rotor into 40 equal parts. When the rotor rotates one grid, the speed is amplified 40 times, and the calculation formula is: .

[0025] In this embodiment, when the rotor 5 starts to rotate, the single chip controller 2 simultaneously sends a signal to turn on the halogen tungsten lamp light source 6. The halogen tungsten lamp light source 6 emits infrared light, which passes through the collimating lens 7 made of CaF2 material, so that the infrared light beam emitted by the light source becomes parallel light and irradiates the rotor 5. Figure 5 As shown. The gear structure on the rotor 5 is relatively thin, but some infrared light will still be reflected by the rotor 5, and the infrared light passing through the gap of the rotor 5 is reflected by the right-angle prism 8 to the focusing lens 9 made of CaF2 material. The infrared parallel light beam is focused by the focusing lens 9 and then received by the photodetector 10 (model: Finisar XPDV2120R). The infrared spectrum is subjected to fast Fourier transform (FFT) through the photodetector 10. FFT is suitable for processing stable signals, the amount of calculation is less than Fourier transform, and the calculation time is faster. The calculation formula is: , where X(f) is the infrared light frequency domain signal, e -2jπft The continuous period unit, j is the imaginary unit.

[0026] In this embodiment, when the infrared beam passes through a gap on the rotor 5, the time domain signal obtained by the photodetector 10 is as follows: Figure 7 As shown. The frequency of scanning one interval is calculated by fast Fourier transform (FFT) to be 128 Hz. Therefore, the precise subdivision of the intervals on the rotor 5 can also be achieved by using infrared light and FFT. The subdivision ratio is increased by 128 times based on the calculation formula in which the rotation speed is amplified by 40 times. The calculation formula is: , and from the shear rate γ calculation formula, the formula is: , where γ is the shear rate, R is the rotor radius, N is the rotation speed, and s is the relative distance between the rotor and the solution.

[0027] In this embodiment, when the rotor radius and the relative distance between the rotor and the solution remain unchanged, the shear rate is positively correlated with the rotation speed. Therefore, a more accurate shear rate can be obtained by accurately calculating the rotation speed. To simulate the actual situation, the kinematic viscosity of the silicone oil was measured, with 1 s -1 , 0.1 s -1 , 0.01 s -1 , 0.001 s -1 The shear rate was tested, and the shear rate detector of the instrument was compared with the constructed low shear rate metering device. The results are shown in Table 1. The results show that the constructed low shear rate metering device can accurately measure the low shear rate, and at the same time, the measurement accuracy is improved in the range of 56.25~75.51%.

[0028] Table 1 shows the shear rate measurement results.

[0029] Although the specific implementation of the present invention is described in detail in conjunction with the drawings, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

[0030] Table 1 Shear rate measurement results

[0031] Input shear rate / s-1 The instrument comes with a shear rate detector / s-1 Low shear rate metering device based on special rotor and infrared photoelectric switch / s-1 Detection accuracy improved by multiples / % 1 0.9712 0.9874 56.25 0.1 0.0951 0.1012 75.51 0.01 0.0217 0.0145 57.94 0.001 0.0074 0.0029 70.31

Claims

1. A low shear rate metering device of a rotational viscometer based on a special rotor and an infrared photoelectric switch, comprising a power supply, a single-chip microcomputer controller, a circular grid subdivision unit, a fast Fourier transform subdivision unit, a base, a vertical rod and a horizontal rod, Features: The circular grid subdivision unit includes a motor, a rotating shaft and a rotor, the fast Fourier transform subdivision unit includes a halogen tungsten lamp light source, a collimating lens, a right-angle prism, a focusing lens and a photodetector, the circular grid subdivision unit is arranged on one side of the fast Fourier transform subdivision unit, the vertical rod is fixedly arranged on the base, the cross bar includes a first cross bar, a second cross bar and a third cross bar, the first cross bar, the second cross bar and the third cross bar are all arranged on the left side of the vertical rod, the power supply, the photodetector, the halogen tungsten lamp light source and the motor are all connected to the single-chip microcomputer controller, the output shaft of the motor is connected to the rotating shaft, the rotor is sleeved on the rotating shaft, the motor adopts an L298N module as a driving unit, the halogen tungsten lamp light source is fixedly arranged on the first cross bar, the collimating lens is fixedly arranged on the second cross bar, the right-angle prism, the focusing lens and the photodetector are fixedly arranged on the third cross bar from left to right in sequence, and the rotor has a disc-shaped gear with a center hole, which is made of polypropylene and has 40 teeth.

2. A low shear rate measuring device of a rotational viscometer based on a special rotor and an infrared photoelectric switch as claimed in claim 1, Features: The power supply and the single-chip microcomputer controller are integrated in the motor, and the single-chip microcomputer controller adopts an STM32 single-chip microcomputer as a controller.

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