TWI573988B - Method for measuring level of material by material level measuring apparatus - Google Patents

Description

Method for measuring material height by using material level measuring device

The invention relates to a method for measuring the height of a material level, in particular to a method for measuring the height of a material level by means of a material level measuring device.

Currently, level measurement devices, such as time domain reflectance radar sensors, are widely used for level measurement; however, there are many factors that affect the accuracy of the level measurement device, such as the dielectric constant of the material. Therefore, after the level measuring device is installed, the height of the material level is not accurately measured by the material level measuring device, which is very inconvenient for the user.

In order to improve the disadvantages of the above prior art, the object of the present invention is to provide a method for measuring the height of a material level by using a material level measuring device.

In order to achieve the above object of the present invention, a method for measuring the height of a material level by using a material level measuring device comprises: inserting a probe of a material level measuring device into a material of a container; The measuring device emits an electromagnetic wave signal, and the electromagnetic wave signal is transmitted along the surface of the probe to the material; when the electromagnetic wave signal contacts a surface of the material, a first reflected signal is generated; the first reflected signal is returned along the probe a level sensing circuit transmitted to the level measuring device; generating a second reflected signal when the electromagnetic wave signal contacts a bottom end of the probe; the second reflected signal is transmitted back to the material along the probe a bit sensing circuit; the level sensing circuit calculates a first travel time difference using the first reflected signal; and the level sensing circuit calculates a second travel time difference by using the second reflected signal; The material level sensing circuit calculates a first material level height by using the first travel time difference; the material level sensing circuit uses the second travel time difference and one of the material level sensing circuits to preset an empty barrel The time difference calculates a second level height; the material The sensing circuit calculates a third material level height by using the first material level height and the second material level height; and after the material level sensing circuit calculates the third material level height, the material level sensing circuit transmits The third level is displayed to a display unit for display.

Furthermore, in a specific embodiment, the method for measuring the height of the material level by using the material level measuring device as described above, wherein the third material level height is the first material level height plus the second material level The average of the heights.

Moreover, in a specific embodiment, the method for measuring the height of the material level by using the material level measuring device as described above, wherein the first material level height is equal to the length of the probe minus a first air height; The first air level is equal to the product of the first travel time difference and an air wave speed divided by two.

Furthermore, in a specific embodiment, the method for measuring the height of the material level by using the material level measuring device as described above, wherein a third travel time difference is equal to the second travel time difference value and the preset empty space The difference between the time difference values.

Furthermore, in a specific embodiment, the method for measuring the height of the material level by using the material level measuring device as described above, wherein the second material level height is equal to a product of the third travel time difference value and a wave speed value; The wave speed value is equal to the product of the air wave velocity and a material wave velocity divided by twice the difference between the air wave velocity and the material wave velocity.

Furthermore, in a specific embodiment, the method for measuring the height of the material level by using the material level measuring device as described above further comprises transmitting a plurality of the electromagnetic wave signals for performing multiple measurements, wherein the electromagnetic wave signals have a fixed interval emission time; the material level sensing circuit uses the electromagnetic wave signals to obtain the first material level height and the second material level height; the material level sensing circuit will measure the first material level The height is compared with the second level height and the previous level of the third level to obtain two comparison results; if one of the comparison results is greater than a predetermined value, the comparison is compared The first level height or the second level height which is not greater than the preset value is regarded as the third level height, and the level sensing circuit displays the third level height on the display unit.

Furthermore, in a specific embodiment, the method for measuring the height of the material level by using the material level measuring device as described above, wherein if the comparison results are greater than the preset value, the first measurement is performed. A level height and the second level height are calculated to obtain the third level height; the level sensing circuit displays the third level height on the display unit.

The utility model has the advantages that the height of the material is measured and calculated in different ways, so as to improve the accuracy of the material level measuring device, and the measurement data with low error is selected for reference by the user.

The detailed description and the technical description of the present invention are to be understood as the

Please refer to FIG. 1 , which is a flow chart of a method for measuring the height of a material level by using a material level measuring device according to the present invention. Please also refer to FIG. 2a at the same time, which is a schematic diagram of one part of the method for measuring the height of the material level by using the material level measuring device; and also referring to FIG. 2b, which is a method for measuring the material level height by using the material level measuring device. Another part of the schematic.

A method for measuring the height of a material level by using a material level measuring device, comprising:

Step S02: Inserting a probe 14 of a level measuring device 10 into a material 30 of a container 20.

Step S04: The material level measuring device 10 emits an electromagnetic wave signal (ie, a detection signal), and the electromagnetic wave signal is transmitted along the surface of the probe 14 in the direction of the material 30.

Step S06: A first reflection signal is generated when the electromagnetic wave signal contacts a surface of the material 30.

Step S08: The first reflected signal is transmitted back along the probe 14 to a level sensing circuit 12 of the level measuring device 10.

Step S10: A second reflection signal is generated when the electromagnetic wave signal contacts the bottom end of the probe 14.

Step S12: The second reflected signal is transmitted back to the level sensing circuit 12 along the probe 14.

Step S14: The level sensing circuit 12 calculates a first travel time difference t1 using the first reflected signal (detailed later).

Step S16: The level sensing circuit 12 calculates a second travel time difference t2 (described in detail later) by using the second reflection signal.

Step S18: The level sensing circuit 12 calculates a first level height using the first travel time difference t1 (detailed later).

Step S20: The material level sensing circuit 12 calculates a second material level height by using the second travel time difference t2 and one of the material level sensing circuits 12 to preset the empty space travel time difference t3. Said).

Step S22: The level sensing circuit 12 calculates a third level height using the first level height and the second level height (described in detail later).

Step S24: After the level sensing circuit 12 calculates the third level height, the level sensing circuit 12 transmits the third level to a display unit 40 for display.

After the electromagnetic wave signal contacts the surface of the material 30, a portion of the electromagnetic wave signal is reflected from the surface of the material 30 to generate the first reflected signal, and the remaining electromagnetic wave signals penetrate the material 30 along the probe. The surface is transferred until it contacts the bottom end of the probe, and then the remaining electromagnetic wave signals are reflected from the bottom end of the probe 14 to generate the second reflected signal.

The above-mentioned step S14 will be described in detail; please refer to FIG. 1 and FIG. 2a again.

Lm represents the material height of the material 30; Lt represents the probe length of the probe 14 (i.e., the depth of the container 20); Lt-Lm is equal to the air height of the container 20.

The first travel time difference t1 is equal to twice the first time t01; the first time t01 is equal to the air height Lt-Lm divided by an air wave speed Vair, and the air wave speed Vair is a constant c, that is, the electromagnetic wave The speed along which the signal passes along the probe 14 and through which the medium is air.

The above can be expressed in the following formula:

T1 = t01 + t01 = [ (Lt-Lm) / Vair ] + [ (Lt-Lm) / Vair ] = 2 * (Lt-Lm) / Vair

The above-mentioned step S16 will be described in detail; please refer to FIG. 1 and FIG. 2a again.

The second travel time difference t2 is equal to the first travel time difference t1 plus a second time t02; the second time t02 is equal to the material height Lm divided by a material wave speed Vm, and the material wave speed Vm is equal to The constant c is divided by the square root of a dielectric coefficient ε of the material 30, i.e., the velocity at which the electromagnetic wave signal travels along the probe 14 and through the material 30.

The above can be expressed in the following formula:

T2 = t01 + t01 + t02 + t02 = [ 2 ( Lt – Lm ) / Vair ] + ( 2 * Lm / Vm )

The following step S18 will be described in detail; the first level height is calculated from the first travel time difference t1; according to the above formulas, the first level height is equal to the probe length Lt of the probe 14. Subtracting a first air height, that is, a height of the electromagnetic wave signal from the transmitting end to the surface contacting the material 30, the first air height being equal to the first travel time difference t1 and an air wave speed The product of Vair is divided by two.

The above can be expressed in the following formula:

The first level height = Lm = Lt - ( t1 * Vair / 2 )

Lt, t1 and Vair are known, so the first level height can be determined.

The above-described step S20 will be described in detail; please refer to FIG. 1 and FIG. 2b again. The second level height is calculated from the second travel time difference t2 and the preset empty travel time difference t3.

It can be seen from Fig. 2a that t2 = [ 2 ( Lt – Lm ) / Vair ] + ( 2 * Lm / Vm )

It can be seen from Fig. 2b that Lt = t3 * Vair / 2

So, t3 = 2 * Lt / Vair

So t2 – t3 = [ 2 ( Lt – Lm ) / Vair ] + ( 2 * Lm / Vm ) – ( 2 * Lt / Vair )

T2 – t3 = ( 2 * Lt / Vair – 2 * Lm / Vair ) + ( 2 * Lm / Vm ) – ( 2 * Lt / Vair )

T2 – t3 = ( – 2 * Lm / Vair ) + ( 2 * Lm / Vm )

( t2 – t3 ) * Vm * Vair = ( – 2 * Lm * Vm ) + ( 2 * Lm * Vair )

( t2 – t3 ) * Vm * Vair = ( Vair – Vm ) * 2 * Lm

( t2 – t3 ) * Vm * Vair / [ 2 * ( Vair – Vm ) ] = Lm

Herein, the second level height is equal to a product of a third travel time difference and a wave speed value; the third travel time difference is equal to the second travel time difference t2 and the preset empty barrel travel time difference The difference of the value t3, the wave speed value being equal to the product of the air wave velocity Vair and the material wave velocity Vm divided by twice the difference between the air wave velocity Vair and the material wave velocity Vm.

That is, the second level height = Lm = ( t2 - t3 ) * Vm * Vair / [ 2 * ( Vair – Vm ) ]

T2, t3, Vm and Vair are known, so the second level height can be determined.

The above step S22 will be described in detail; the third level height is equal to the average of the first level height and the second level height.

The above can be expressed in the following formula:

The third level height = (the first level height + the second level height) / 2 = { Lt - ( t1 * Vair / 2 ) + ( t2 – t3 ) * Vm * Vair / [ 2 * ( Vair – Vm ) ] } / 2

In another embodiment of the present invention, in step S22, the level sensing circuit 12 transmits a plurality of the electromagnetic wave signals for multiple measurements, and the electromagnetic wave signals have a fixed interval emission time; The measuring circuit 12 obtains the first level height and the second level height by using the electromagnetic wave signals, and the first level height and the second level measured by the level sensing circuit 12 The height is respectively compared with the third level height of the previous measurement to obtain two comparison results, and if the comparison result has one of the comparison results being greater than a preset value, the comparison result is not greater than The first level height or the second level height of the preset value is regarded as the third level height, and the level sensing circuit 12 displays the third level height on the display unit 40; The comparison results are all greater than the preset value, and the first level height and the second level height are calculated to obtain the third level height, and the level sensing circuit 12 The third level height is displayed on the display unit 40.

Furthermore, the comparison result may be a value obtained by subtracting the height of the first material level and the height of the second material level from the height of the third material level respectively; or the comparison result may be the height of the first material level, The value obtained after the second level height is respectively divided by the third level height.

Furthermore, the level measuring device 10 can be, for example, but the invention is not limited to a time domain reflection radar sensor.

Furthermore, in order to increase the usability of the level measuring device 10, the level measuring device 10 further includes a time-expanding circuit 16 (as shown in FIGS. 2a and 2b); the time-expanding circuit 16 will take a time difference. The amount of change in value (i.e., t1 - t2) is multiplied by a gain value such that the unit of the amount of change in the travel time difference is amplified from microseconds to milliseconds; thereby, the usability of the level measuring device 10 is increased.

The utility model has the advantages that the height of the material is measured and calculated in different ways, so as to improve the accuracy of the material level measuring device, and the measurement data with low error is selected for reference by the user.

However, the above is only a preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the equivalent changes and modifications made by the scope of the present invention should still be covered by the patent of the present invention. The scope of the scope is intended to protect. The invention may be embodied in various other modifications and changes without departing from the spirit and scope of the inventions. It is intended to fall within the scope of the appended claims. In summary, it is known that the present invention has industrial applicability, novelty and advancement, and the structure of the present invention has not been seen in similar products and public use, and fully complies with the requirements of the invention patent application, and is filed according to the patent law.

10‧‧‧Level measuring device

12‧‧‧Level sensing circuit

14‧‧‧ Probe

16‧‧‧Time-expanding circuit

20‧‧‧ container

30‧‧‧Materials

40‧‧‧Display unit

Lt‧‧‧ probe length

Lm‧‧‧ material height

S02～S24‧‧‧Steps

t1‧‧‧First time difference

t2‧‧‧Second time difference

t3‧‧‧Preset empty bucket travel time difference

T01‧‧‧First time

T02‧‧‧ second time

1 is a flow chart of a method for measuring the height of a material level by using a material level measuring device according to the present invention.

Figure 2a is a partial schematic view of a method for measuring the height of a fill level using a level measuring device.

Figure 2b is a schematic illustration of another portion of the method of measuring the fill level using a level measuring device.

S02~24‧‧‧Steps

Claims (7)

A method for measuring a height of a material level by using a material level measuring device, comprising: a. inserting a probe of a material level measuring device into a material of a container; b. transmitting a electromagnetic wave signal by the material level measuring device The electromagnetic wave signal is transmitted along the surface of the probe toward the material; c. generating a first reflected signal when the electromagnetic wave signal contacts a surface of the material; d. the first reflected signal is transmitted back to the probe along the probe a level sensing circuit of the level measuring device; e. generating a second reflected signal when the electromagnetic wave signal contacts a bottom end of the probe; f. the second reflected signal is returned to the rod along the probe a material level sensing circuit; g. the material level sensing circuit calculates a first travel time difference using the first reflected signal; h. the material level sensing circuit uses the second reflected signal to calculate a second walk The time difference value; i. the material level sensing circuit calculates a first material level height by using the first travel time difference; j. the material level sensing circuit uses the second travel time difference and the material sense One of the measurement circuits presets a difference in the travel time of the empty bucket to calculate a second material level height; k. the material level The measuring circuit calculates a third material level height by using the first material level height and the second material level height; and l. the material level sensing circuit calculates the third material level height, the material level sensing circuit The third level height is transmitted to a display unit for display. The method for measuring the height of a material level as described in claim 1, wherein the third material level height is an average of the first material level height plus the second material level height. The method for measuring the height of a material level as described in claim 1, wherein the first material level height is equal to the length of the probe minus a first air height; the first air height is equal to the first travel time The product of the difference and an air wave velocity is divided by two. For the method for measuring the height of the material level as described in claim 1, wherein the third travel time difference is equal to the difference between the second travel time difference and the preset empty travel time difference. The method for measuring the height of a material level as described in claim 4, wherein the second material level height is equal to a product of the third travel time difference value and a wave speed value; the wave speed value is equal to the air wave speed and a material The product of the wave velocity is then divided by twice the difference between the air wave velocity and the material wave velocity. The method for measuring the height of the material level as described in claim 1 further comprises transmitting a plurality of the electromagnetic wave signals for performing a plurality of measurements, wherein the electromagnetic wave signals have a fixed interval emission time; the material level sensing The circuit uses the electromagnetic wave signals to obtain the first material level height and the second material level heights; the material level sensing circuit measures the first material level height and the second material level height The third level heights of the first measurement are respectively compared to obtain two comparison results. When one of the comparison results is greater than a preset value, the comparison result is not greater than the comparison result. The first level height or the second level height of the preset value is regarded as the third level height, and the level sensing circuit displays the third level height on the display unit. For the method for measuring the height of the material level as described in claim 6, if the comparison results are greater than the preset value, the height of the first material level and the height of the second material level are measured. After calculating to obtain the third level height, the level sensing circuit displays the third level height on the display unit.