CN103234603B - Floater mechanism and measurement method used for measuring liquid level of liquid pressure meter - Google Patents

Abstract

The invention relates to a liquid pressure gauge, which belongs to the detection field. A float mechanism for measuring the liquid level position of a liquid pressure gauge, which is set on the liquid surface of a conductive medium of a liquid pressure gauge, and is characterized in that it includes a float and a float stabilization mechanism, and the float includes a float and a "T"-shaped measuring head , the floating body adopts aluminum alloy floating body, the top surface of the "T" shape of the measuring head is a polytetrafluoro diffuse reflection plane, and there are stabilizing grooves protruding from both ends of the floating body, and the stabilizing grooves are set in the container fixed in the liquid pressure gauge On the vertical columns of the left and right stabilizing brackets, the two stabilizing brackets are vertically arranged between the upper and lower planes in the container, the floating body is arranged symmetrically with the center line, and the measuring head is arranged on the symmetrical axis of the center line, The inner wall of the container is coated with Teflon. The float mechanism of the present invention is used on the liquid surface of the liquid press, and the height value of the liquid surface can be obtained very accurately by cooperating with the measuring device, and the accuracy and stability are very good.

Description

Float mechanism and measurement method for liquid level position measurement of liquid pressure gauge

technical field

The invention relates to a liquid pressure gauge, in particular to a float mechanism for liquid level position measurement of the liquid pressure gauge.

Background technique

A liquid pressure gauge is an instrument that uses the height difference of a liquid column to directly measure pressure. Its biggest advantage is that it is intuitive and can maintain a small pressure in a stable state, but the biggest technical difficulty in achieving high-accuracy measurement is the measurement of the liquid level. The traditional method of measuring the liquid level is roughly divided into two types, one is to engrave a scale on the glass tube to visually observe the position of the liquid level in the glass tube, and the other is to adjust the liquid level and observe the cone tip fixed in the container and its The reflection in the liquid surface makes them about to collide, and the position of the cone tip is the position of the liquid surface at this time. As shown in Figure 1, the most typical is a U-shaped tube pressure gauge, and the measurement accuracy is quite low. The method shown in accompanying drawing 2 is relatively accurate. A typical example is a compensating micromanometer. The first disadvantage is that the position of the liquid level is fixed during balance, and the second is that the balance position must be adjusted by visual inspection, which is difficult to carry out automatic control and digital control. communication. In addition to the above two methods, there are still people who use ultrasonic waves to directly measure the liquid level position. Ultrasound is characterized by high frequency, short wavelength, small diffraction phenomenon, and good directionality, which can be directional and propagate as rays. The liquid level height is the product of ultrasonic propagation speed and transmission time, Distance=VT. The measurement principle is to trigger pulse counting when the ultrasonic wave is turned on and stop counting when the return signal is received, as shown in Figure 3. In order to make the measurement more accurate, some constants of ultrasonic transmission can be calibrated with a horizontal fixed distance. Measurement accuracy is possible on the order of a few hundredths of a millimeter. However, if a liquid pressure gauge with water as the medium is used, it corresponds to a pressure of a few tenths of Pa. The stability and accuracy of the measurements are not ideal.

Contents of the invention

The technical problem to be solved by the present invention is to provide a float mechanism for measuring the liquid level position of the liquid pressure gauge, which solves the problem that the liquid level position measurement of the liquid pressure gauge uses human eyes or other methods, the accuracy cannot be guaranteed, and the consistency is very poor Defects.

Technical solutions

A float mechanism for measuring the liquid level position of a liquid pressure gauge, which is set on the liquid surface of a conductive medium of a liquid pressure gauge, and is characterized in that it includes a float and a float stabilization mechanism, and the float includes a float and a "T"-shaped measuring head , the floating body adopts aluminum alloy floating body, the top surface of the "T" shape of the measuring head is a polytetrafluoro diffuse reflection plane, and there are stabilizing grooves protruding from both ends of the floating body, and the stabilizing grooves are set in the container fixed in the liquid pressure gauge On the vertical columns of the left and right stabilizing brackets, the two stabilizing brackets are vertically arranged between the upper and lower planes in the container, the floating body is symmetrically arranged on the center line, and the "T" shaped measuring head is arranged on the center line On the axis of symmetry, the inner wall of the container is coated with Teflon.

Further, the left and right ends of the floating body are respectively close to the left and right stabilizing brackets arranged in the container.

Further, the floating body is a downward cone.

Further, the container is a sealed container.

Further, a laser displacement gauge is arranged on the container, and cooperates with the float mechanism to measure the liquid level in the container.

Beneficial effect

The float mechanism of the present invention is used on the liquid surface of a liquid press, and the height value of the liquid surface can be obtained very accurately by cooperating with a laser displacement meter or other measuring devices, and the change of the liquid surface height can be observed, which is better than the current direct-viewing method. The accuracy is greatly improved, and even under micro-pressure changes, it can be accurately tested without being affected, and the stability is very good.

Description of drawings

Fig. 1 is a schematic diagram of a measurement method in the prior art.

Fig. 2 is a schematic diagram of another measurement method in the prior art.

Fig. 3 is a schematic diagram of the principle of ultrasonic measurement in the prior art.

Fig. 4 is a schematic diagram of the structure of the present invention.

Fig. 5 is a schematic diagram of the principle of liquid level measurement with the structure of the present invention combined with a laser displacement meter.

Among them: 1-floating body, 2-measuring head, 3-"T"-shaped top surface of the measuring head, 4-stabilizing tank, 5-stabilizing bracket, 6-pressure transmission medium liquid level, 7-container, 8-semiconductor laser, 9-lens in front of laser, 10-collecting lens, 11-CCD array, 12-signal processor, 13-measured object.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention.

In order to solve the detection under the micro pressure situation, a kind of float mechanism is newly designed, and the float mechanism is arranged on the liquid level 6 of the conducting medium in the container 7 of the liquid manometer, and the whole float mechanism includes a float and a float stabilizing mechanism. The float includes a floating body 1 and a "T"-shaped measuring head 2. The floating body 1 is made of an aluminum alloy floating body. The "T"-shaped top surface 3 of the measuring head is a polytetrafluoro diffuse reflection plane. There are stabilizing grooves 4 protruding from both ends of the floating body 1. , the stable groove 4 is set on the vertical columns of the left and right stable brackets 4 fixed in the container 7 of the liquid pressure gauge, and the two stable brackets 4 are vertically arranged between the upper and lower planes in the container 7 , the stable bracket 4 can limit the rotation and swing of the float, see accompanying drawing 4. The laser displacement meter above the container 7 directs the laser beam to the reflection plane of the diffuse reflection surface, and performs distance measurement according to different distances corresponding to different reflection angles. The inner wall of the container 7 of the float mechanism adopts Teflon coating to reduce the adhesion of the inner surface of the container to the medium, so that the adhesion is smaller than the cohesive force between liquid molecules, and the liquid medium is not easy to produce wall hanging phenomenon.

It is worth noting that the development of the float mechanism must ensure that the center of gravity of the float is very consistent with its center position, otherwise the float will tilt and generate friction on the stable support 4 to change the buoyancy balance. Therefore, the floating body 1 is arranged symmetrically with the center line, The "T" shaped measuring head 2 is arranged on the axis of symmetry of the center line.

A laser displacement gauge can be arranged on the container 7, and cooperate with the float mechanism to measure the liquid level in the container. The laser displacement meter uses the measurement principle of optical triangulation (see Figure 5) for measurement, that is, the monochromatic light emitted by the semiconductor laser 8 is focused on the measured object 13 by the lens 9 in front of the laser. The reflected light is collected by the collecting lens 10 and projected onto the CCD array 11; the signal processor 12 calculates the position of the light spot on the CCD array 11 through trigonometric functions to obtain the distance to the object. The figure shows a schematic diagram of the measurement from the initial position to the moving position of the measured object 13 . If the launch plane is deflected, it will inevitably affect the accuracy of position measurement, so the floating state of the float is very important.

In order to measure absolute pressure and vacuum, the float mechanism must be completely sealed. The sealing mechanism is divided into three parts: one is the embedded annular rubber gasket seal of the upper cover, the second is the pressure vacuum seal of the pressure interface, and the third is the optical isolation seal between the laser displacement gauge and the mechanism.

In actual measurement, the measured value D ₀ of the laser displacement meter when there is no pressure difference is taken as the zero position, and the reading D _x of the laser displacement meter during measurement after pressurization is a relative reading, and the actual liquid level position D is:

D = D _x -D ₀ ----------- (1)

Considering the temperature change in the measurement process, the actual liquid level position must also be corrected by the temperature of the medium density. Let the initial state medium density be ρ ₀ , and the temperature function of the medium density be ξ(t), then the working state medium density for

${\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; \&Integral;</span>}_{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; \&xi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; dt</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

According to Archimedes' law, the buoyancy is equal to the weight of the displaced liquid, and according to the principle of static balance, the buoyancy is equal to the gravity of the float, and the actual liquid level position can be deduced

${\mathrm{<span\; class="notranslate">\; D.</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 4</span>}\frac{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; \&pi;d</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In the formula: d is the outer diameter of the float; V ₀ is the initial volume of the float immersed in the medium.

The actual liquid level change value can be calculated by formulas (2) and (3).

According to the current technical level of the laser displacement meter, its position measurement uncertainty can reach 7μ (k=2), and the measurement range is 10mm.

This scheme develops the floating mechanism in the movable container and the fixed container in the high-precision liquid pressure gauge. The laser displacement meter is set above the container 7, and the laser beam is used to measure the distance to the reflection plane of the diffuse reflection surface. The float mechanism is simple in structure, novel in design, and realizes high-precision measurement. Compared with the original compensation pressure gauge, it not only expands the measurement range but also improves the measurement uncertainty, and the measurement data is directly in digital form, which can be introduced into the automatic micro-pressure measurement system as an important part of automatic measurement, making the detection equipment practical Stronger, more suitable for the requirements of actual micro-pressure measurement.

Claims (3)

1. A float mechanism for measuring the liquid level position of a liquid pressure gauge, which is arranged on the liquid surface of the transmission medium of the liquid pressure gauge, and is characterized in that: it includes a float and a float stabilization mechanism, and the float includes a floating body and a "T" shape The measuring head, the floating body adopts aluminum alloy floating body, the top surface of the "T" shape of the measuring head is a polytetrafluoro diffuse reflection plane, and the two ends of the floating body have protruding stabilizing grooves respectively, and the stabilizing grooves are set in the container fixed on the liquid pressure gauge On the vertical columns of the left and right stabilizing brackets in the container, the two stabilizing brackets are vertically arranged between the upper and lower planes in the container, the floating body is arranged symmetrically with the center line, and the "T" shaped measuring head is arranged here On the symmetrical axis of the center line, the inner wall of the container is coated with Teflon, and the left and right ends of the floating body are respectively close to the left and right stable brackets arranged in the container, the floating body is a downward cone, and the container is a sealed container. 2. The float mechanism for measuring the liquid level position of a liquid manometer according to claim 1, characterized in that: a laser displacement gauge is arranged on the container to cooperate with the float mechanism to measure the liquid level in the container. 3. A method for measuring the liquid level position of a liquid manometer using a float mechanism as claimed in claim 1, characterized in that: the float mechanism is arranged in the liquid container of the liquid manometer, and the top of the liquid container On the surface, a laser displacement meter is arranged above the float mechanism. The laser displacement meter adopts optical triangulation method, and uses the PTFE diffuse reflection plane of the float mechanism as the measured object for displacement measurement, and combines the conduction medium and the float mechanism. The height position of the liquid surface is obtained by calculating the parameters.