Cable type level meter, control method and control module

Abstract

The invention relates to the technical field of material level detection, in particular to a cable type material level meter, a control method and a control module, and aims to solve the problem that an existing material level meter is insufficient in measurement accuracy. In order to achieve the purpose, the control method of the cable type level meter comprises the steps that the basic value of the measured level height is obtained; obtaining the current tension of the detection cable, the basic tension in a self-weight state and an elastic coefficient; the stretching amount of the detection cable is determined according to the current tension of the detection cable, the basic tension in the self-weight state and the elastic coefficient; and determining a correction value of the material level height according to the stretching amount of the detection cable and the basic value of the material level height. The stretching amount of the detection cable is determined according to the current tension of the detection cable, the basic tension in the self-weight state and the elastic coefficient, and the basic value of the material level height is corrected, so that the influence of the force applied to the detection cable by the material on the final measurement result of the material level height is reduced, and the accuracy of the measurement result is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of level detection, and specifically provides a cable type level meter, a control method and a control module. Background Art

[0002] Traditional capacitive level meters include detection probes. As the material level rises, the material covers the detection probe, and the capacitance value between the detection probe and the medium in the circuit (in the case of conductive materials) or the capacitance value between the detection probe and the pipe wall (in the case of insulating materials) increases accordingly. Since the change in material level causes the imbalance of the capacitance bridge, the change in capacitance value depends on the dielectric constant of the material being measured, and then the corresponding signal is output through signal detection and amplification.

[0003] For some working conditions with a large measuring range, a cable-type level meter is used. However, the measurement result of the cable-type level meter is offset during the measurement process, resulting in insufficient measurement accuracy of the existing cable-type level meter.

[0004] Therefore, there is an urgent need for a cable type level meter, a control method and a control module to solve the problem of insufficient measurement accuracy of existing level meters. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem of insufficient measurement accuracy of the existing level meter.

[0006] In a first aspect, the present invention provides a control method for a cable-type level meter, comprising: obtaining a basic value of a measured level height; obtaining a current tension of a detection cable, a basic tension under a deadweight state, and an elastic coefficient; determining a stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under a deadweight state, and the elastic coefficient; determining a correction value of the level height according to the stretching amount of the detection cable and the basic value of the level height.

[0007] In a specific implementation of the control method of the cable type level meter, the stretching amount of the detection cable is determined according to the current tension of the detection cable, the basic tension under its own weight, and the elastic coefficient, including: ∆H=(F1-F2) / k, wherein ∆H is the stretching amount of the detection cable, F1 is the current tension of the detection cable, F2 is the basic tension of the detection cable under its own weight, and k is the elastic coefficient of the detection cable.

[0008] In a specific implementation of the control method of the above-mentioned cable-type level meter, a correction value of the level height is determined according to the stretching amount of the detection cable and the basic value of the level height, including: Hxiu=H0-∆H, wherein Hxiu is the correction value of the level height, H0 is the basic value of the level height, and ∆H is the stretching amount of the detection cable.

[0009] In a specific implementation of the control method of the cable type level meter, obtaining the elastic coefficient of the detection cable includes: obtaining the temperature of the measured medium; and determining the elastic coefficient of the detection cable according to the temperature of the measured medium.

[0010] In a second aspect, the present invention provides a control module of a cable level meter, which is used to implement the control method of the cable level meter, including: a first acquisition unit, which is used to acquire a basic value of the measured level height; a second acquisition unit, which is used to acquire the current tension of the detection cable; a first storage unit, which is used to store the basic tension of the detection cable under its own weight; a second storage unit, which is used to store the elastic coefficient of the detection cable; a first calculation unit, which is used to determine the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under its own weight, and the elastic coefficient; and a second calculation unit, which is used to determine the correction value of the level height according to the stretching amount of the detection cable and the basic value of the level height.

[0011] In a third aspect, the present invention provides a cable-type level meter, comprising: a housing; a detection cable, a first end of the detection cable being disposed in the housing, and a second end of the detection cable extending from the housing; a power supply module for supplying power to the detection cable; and a control module of the above-mentioned cable-type level meter.

[0012] In a specific implementation of the above cable type level meter, the length of the detection cable is 4 meters to 80 meters.

[0013] In a specific embodiment of the above cable type level meter, a weight is provided at the second end of the detection cable, and the weight is configured to tension the detection cable by utilizing gravity.

[0014] In a specific embodiment of the above cable type level meter, a tensioning structure is disposed in the housing, and the tensioning structure is configured to tension the detection cable.

[0015] In a specific implementation of the above cable type level meter, at least a portion of the surface of the shell is provided with a heat sink.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: The control method of the cable type level meter provided by the present invention comprises: obtaining the basic value of the measured level height; obtaining the current tension of the detection cable, the basic tension under the deadweight state and the elastic coefficient; determining the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under the deadweight state and the elastic coefficient; determining the correction value of the level height according to the stretching amount of the detection cable and the basic value of the level height. The stretching amount of the detection cable is determined according to the current tension of the detection cable, the basic tension under the deadweight state and the elastic coefficient, and the basic value of the level height is corrected to reduce the influence of the force applied by the material to the detection cable on the final measurement result of the level height, thereby improving the accuracy of the measurement result.

[0017] Furthermore, the elastic coefficient of the detection cable is determined according to the measured medium temperature, thereby reducing the influence of temperature on the stretching of the detection cable and improving the accuracy of the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which: Figure 1 is a flow chart of a control method of a cable type level meter provided by the present invention; Figure 2 It is a cross-sectional view of the cable type level meter provided by the present invention after assembly; Figure 3 It is an exploded schematic diagram of the cable type level meter provided by the present invention.

[0019] Description of reference numerals: 1. Base; 11. Base plate; 12. Fixing plate; 13. Tensioning structure; 14. Protective cover; 2. Upper shell; 3. Lower shell; 31. Cavity; 32. Receiving groove; 33. Heat sink; 34. Insulation tube; 35. Insulation block; 36. Locking piece; 4. Insulation pad; 5. Pad; 6. Screw; 61. Screw sleeve; 7. Detection cable; 71. Weight; 72. Embracing steel pipe. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0021] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0022] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Example

[0023] There are many types of existing level meters, such as capacitive level meters and radio frequency admittance level meters. Capacitive level meters include detection probes. As the material level rises, the material covers the detection probe, and the capacitance value between the detection probe and the medium in the circuit (in the case of conductive materials) or the capacitance value between the detection probe and the pipe wall (in the case of insulating materials) increases accordingly. Since the change in the material level causes the imbalance of the capacitance bridge, the change in capacitance value depends on the dielectric constant of the material being measured, and then the signal is detected and amplified, and finally the corresponding signal is output.

[0024] The measurement principle of the RF admittance level meter is similar to that of the capacitive level meter. The detection probe and the container wall form a two-stage capacitor with a fixed spacing. After the material level in the container covers the detection probe, the insulating material of the detection probe, the medium, and the air above the medium act as the filling between the capacitors. The RF admittance level meter can emit a certain high-frequency radio wave to act on the detection probe. As the level of the medium changes, the electrical parameters (such as capacitance and admittance) between the detection probe and the container wall change, which in turn causes the change of the radio wave acting on the detection probe. According to the change of the radio wave, the level of the medium can be analyzed and calculated. The measurement results of the RF admittance level meter are highly accurate and are not affected by the hanging material on the detection probe.

[0025] The measuring range of the RF admittance level meter depends on the length of the detection conductor in the detection probe. The measuring range of the level meter using a hard conductor as the detection conductor is generally not more than 4 meters. Some schemes use cables as detection conductors to increase the maximum measuring range of the level meter, but the measurement results of this type of level meter often deviate, resulting in low measurement accuracy. After research by the applicant, it was found that the reason for the measurement deviation of the level meter using cables as detection conductors is the stretching and contraction of the cables.

[0026] Based on this, in order to solve the problem of insufficient accuracy of existing level meters, the present invention provides a control method for a cable level meter, such as Figure 1 As shown, the following steps are included: S1. Obtain a basic value of the measured material level height, wherein the basic value of the measured material level height is the material level height measured before correction, without considering the influence caused by the expansion and contraction of the detection cable.

[0027] S2. Obtain the current tension of the detection cable, the basic tension under deadweight, and the elastic coefficient.

[0028] Among them, the basic tension under deadweight state is a preset value, which is measured under normal conditions and stored in the level meter.

[0029] The detection cable is located in the container. The material in the container will exert a force on the detection cable and change the tension of the detection cable, thereby changing the total length of the detection cable and affecting the level meter's detection of the material level. For example, when the material is solid, the drop in the material level will pull the detection cable so that the detection cable is stretched and the tension increases; when the material is liquid, the higher the material level, the greater the buoyancy of the detection cable, the detection cable will contract and the tension will decrease. The current tension of the detection cable can be detected by setting a tension detector in the level meter. The tension detector is connected to the detection cable, and the tension detector is a known technology.

[0030] The elastic coefficient can be a fixed preset value or a floating value related to temperature. In a specific example of the present invention, the temperature of the measured medium is first obtained, and then the elastic coefficient of the detection cable is determined according to the temperature of the measured medium. When the material of the detection cable is determined, the curve graph or functional relationship between the elastic coefficient and the temperature of the detection cable of this material can be measured through experiments, and the curve graph or functional relationship is stored in the level meter or the system connected to the level meter. When the detection cable is in the container, the temperature of the detection cable itself is close to the temperature of the measured medium. According to the curve graph or functional relationship between the elastic coefficient and the temperature of the detection cable, the corresponding elastic coefficient can be obtained according to the temperature of the measured medium, so as to compensate for the offset of the level height measurement value caused by the change of the elastic coefficient with temperature.

[0031] S3. Determine the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under deadweight state, and the elastic coefficient.

[0032] Specifically, ∆H=(F1-F2) / k, where ∆H is the stretching amount of the detection cable, F1 is the current tension of the detection cable, F2 is the basic tension of the detection cable under its own weight, and k is the elastic coefficient of the detection cable.

[0033] S4. Determine a correction value of the material level height according to the stretching amount of the detection cable and the basic value of the material level height.

[0034] Specifically, H 修 =H0-∆H, where H 修 is the correction value of the material level height, H0 is the basic value of the material level height, and ∆H is the stretching amount of the detection cable.

[0035] In summary, the control method of the cable type level meter provided by the present invention has the following beneficial effects: 1. Determine the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under deadweight and the elastic coefficient, and correct the basic value of the material level height to reduce the influence of the force applied by the material to the detection cable on the final measurement result of the material level height, thereby improving the accuracy of the measurement result; 2. Under the premise that the specifications of the detection cable are determined, the elastic coefficient of the detection cable is determined according to the temperature, thereby reducing the influence of temperature on the stretching of the detection cable and improving the accuracy of the measurement results. Example

[0036] The present invention also discloses a control module of a cable level meter for implementing the control method of the cable level meter. The control module comprises a first acquisition unit, a second acquisition unit, a first storage unit, a second storage unit, a first calculation unit and a second calculation unit.

[0037] The first acquisition unit is used to acquire a basic value of the measured material level height.

[0038] The second acquisition unit is used to acquire the current tension of the detection cable.

[0039] The first storage unit is used to store the basic tension of the detection cable under its own weight.

[0040] The second storage unit is used to store the elastic coefficient of the detection cable.

[0041] The first calculation unit is used to determine the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under the deadweight state, and the elastic coefficient.

[0042] The second calculation unit is used to determine a correction value of the material level height according to the stretching amount of the detection cable and a basic value of the material level height. Example

[0043] The present invention also provides a storage medium on which a computer program is stored. When the program is executed by a controller, the control method of the cable type level meter as described above is implemented.

[0044] Of course, the storage medium containing computer executable instructions introduced in this embodiment is not limited to the operations in the control method of the cable level meter in Example 1, and can also execute related operations in the control module of the cable level meter provided in Example 2 of the present invention, and has corresponding functions and beneficial effects. Example

[0045] The embodiment of the present invention provides a cable type level meter, such as Figure 2 and Figure 3 As shown, the cable type level meter comprises a housing, a detection cable 7, a power supply module and a control module as described in the second embodiment. The first end of the detection cable 7 is arranged in the housing, the second end of the detection cable 7 extends from the housing, and the power supply module is used to supply power to the detection cable 7.

[0046] The housing includes a base body 1, and the base body 1 includes a substrate 11, and the substrate 11 includes a first side and a second side opposite to each other. A fixing plate 12 is fixedly provided on the first side of the substrate 11, and a tensioning structure 13 is provided on the fixing plate 12. The first end of the detection cable 7 is mounted on the tensioning structure 13, and the second end of the detection cable 7 is located on the second side of the substrate 11 after passing through the substrate 11. For example, the tensioning structure 13 includes a tensioning drive and a rotating component or a swinging component. The first end of the detection cable 7 is fixed on the rotating component or the swinging component, and the tensioning drive can drive the rotating component to rotate or drive the swinging component to swing, thereby tensioning the detection cable 7 and keeping the detection cable 7 in a straight state.

[0047] A protective cover 14 is fixedly disposed on the second side of the substrate 11 , and the detection cable 7 passes through and out of the protective cover 14 , so that the protective cover 14 is used to guide and protect the detection cable 7 .

[0048] The shell also includes an upper shell 2 and a lower shell 3. The upper shell 2 is located as a whole on the first side of the substrate 11, and is used to protect the substrate 1 and lead out wires. The lower shell 3 is located as a whole on the second side of the substrate 11. The upper shell 2 and the lower shell 3 are connected to each other (for example, by threaded connection) to form a closed space, which is used to protect the substrate 1 and form a whole.

[0049] The lower shell 3 is provided with a cavity 31 that passes through the lower shell 3 along the axis, the protective cover 14 is located in the cavity 31, and the second end of the detection cable 7 passes through the cavity 31. The lower shell 3 is provided with a receiving groove 32 on the side facing the upper shell 2, and the substrate 11 is located in the receiving groove 32 and is fixedly connected to the bottom of the receiving groove 32 (for example, fixed by screws 6 and screw 6 sets). An insulating pad 4 and a pad 5 are arranged between the substrate 11 and the lower shell 3, wherein the pad 5 plays the role of isolation, insulation and buffering, and the insulating pad 4 mainly plays the role of insulation.

[0050] A heat sink 33 is disposed on the outer periphery of the lower housing 3 to improve the heat dissipation efficiency of the lower housing 3 and reduce the temperature of the lower housing 3 .

[0051] The inner side of the end of the lower shell 3 away from the upper shell 2 forms a first step surface and a second step surface on the circumferential surface of the cavity 31, and the maximum diameter of the first step surface is smaller than the maximum diameter of the second step surface. The end of the lower shell 3 away from the upper shell 2 is provided with an insulation tube 34, an insulating block 35 and a locking piece 36. The insulation tube 34 is attached to the inner surface of the cavity 31, the insulating block 35 abuts against the end of the insulation tube 34 sleeve and is attached to the inner surface of the first step surface, and the locking piece 36 abuts against the end of the insulating block 35 and is clamped or threaded with the second step surface. The detection cable 7 passes through the insulation tube 34, the insulating block 35 and the locking piece 36 in sequence, and the locking piece 36 does not contact the detection cable 7. The insulation tube 34 sleeve can reduce the heat conduction efficiency between the detection cable 7 and the lower shell 3, thereby reducing the temperature of the lower shell 3. The insulating block 35 and the heat-insulating tube 34 can isolate the detection cable 7 from the lower housing 3, preventing the detection cable 7 from contacting the lower housing 3 and affecting the detection result. The locking member 36 is mainly used to limit the insulating block 35 and the heat-insulating tube 34, preventing the insulating block 35 and the heat-insulating tube 34 from coming out. For example, the locking member 36 is an inner nut, which is threadedly connected to the end of the lower housing 3 and abuts against the insulating pad 4.

[0052] The second end of the detection cable 7 is provided with a weight 71, which can use its own gravity to tension the detection cable 7, so that the detection cable 7 remains straight. The second end of the detection cable 7 is also provided with an embracing steel pipe 72, the second end of the detection cable 7 passes through the weight 71, and the embracing steel pipe 72 is fixed to the second end of the detection cable 7, and the weight 71 is limited by the embracing steel pipe 72.

[0053] In the example disclosed herein, the length of the detection cable 7 can be set to any length between 4 meters and 80 meters. Of course, according to requirements, the length of the detection cable 7 can also be set to more than 80 meters. For example, the detection cable 7 is a steel wire rope.

[0054] In summary, the installation process of the capacitive level meter provided in the embodiment of the present invention is as follows: First, install the detection cable 7 on the base 1, pass the detection cable 7 and the protective cover 14 in the base 1 through the insulating pad 4 and the pad 5, and then assemble the base 1, the insulating pad 4 and the pad 5 into the lower shell 3, and then use screws 6 and screw 6 sets to fix the base 1, the insulating pad 4 and the pad 5 to the lower shell 3.

[0055] Afterwards, the insulation tube 34, 4 insulating pads and the locking piece 36 are inserted from the second end of the detection cable 7, and moved along the detection cable 7 to the cavity 31 of the lower shell 3, so that the end of the insulation tube 34 abuts against the insulating pad 4, and then the locking piece 36 is threadedly connected to the end of the lower shell 3, so that the locking piece 36 abuts against and locks the 4 insulating pads and the insulation tube 34.

[0056] The weight 71 is put on the second end of the detection cable 7 , and then the embracing steel tube 72 is fixed to the second end of the detection cable 7 , and the weight 71 is limited by the embracing steel tube 72 .

[0057] Finally, the upper shell 2 is screwed to the end of the lower shell 3 to form a closed space for protecting the base 1 .

[0058] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A control method for a cable level meter, characterized in that: include: Obtain the basic value of the measured material level height; Obtain the current tension of the detection cable, the basic tension under its own weight, and the elastic coefficient; Determine the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under the deadweight state, and the elastic coefficient; A correction value of the material level height is determined according to the stretching amount of the detection cable and the basic value of the material level height.

2. The control method of the cable type level meter according to claim 1, characterized in that: Determining the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under the deadweight state, and the elastic coefficient includes: ∆H=(F1-F2) / k, wherein ∆H is the stretching amount of the detection cable, F1 is the current tension of the detection cable, F2 is the basic tension of the detection cable under its own weight, and k is the elastic coefficient of the detection cable.

3. The control method of the cable type level meter according to claim 1, characterized in that: Determining a correction value of the material level height according to the stretching amount of the detection cable and the basic value of the material level height includes: H 修 =H0-∆H, where H 修 is the correction value of the material level height, H0 is the basic value of the material level height, and ∆H is the stretching amount of the detection cable.

4. The control method of the cable type level meter according to claim 1, characterized in that: Obtaining the elastic coefficient of the detection cable includes: Obtain the temperature of the measured medium; The elastic coefficient of the detection cable is determined according to the temperature of the measured medium.

5. A control module of a cable level meter, characterized in that: A control method for implementing the cable level meter according to any one of claims 1 to 4, comprising: A first acquisition unit, used for acquiring a basic value of the measured material level height; a second acquisition unit, used to acquire the current tension of the detection cable; A first storage unit is used to store the basic tension of the detection cable under its own weight; A second storage unit, used for storing the elastic coefficient of the detection cable; A first calculation unit, configured to determine the stretching amount of the detection cable according to the current tension of the detection cable, the basic tension under the deadweight state, and the elastic coefficient; The second calculation unit is used to determine a correction value of the material level height according to the stretching amount of the detection cable and the basic value of the material level height.

6. A cable type level meter, characterized in that: include: case; a detection cable, a first end of the detection cable being disposed in the housing and a second end of the detection cable extending from the housing; A power supply module, used to supply power to the detection cable; It also includes a control module of the cable type level meter as claimed in claim 5.

7. The cable type level meter according to claim 6, characterized in that: The length of the detection cable is 4 meters to 80 meters.

8. The cable type level meter according to claim 6, characterized in that: A weight is disposed at the second end of the detection cable, and the weight is configured to tension the detection cable using gravity.

9. The cable type level meter according to claim 6, characterized in that: A tensioning structure is disposed in the housing, and the tensioning structure is configured to tension the detection cable.

10. The cable type level meter according to claim 6, characterized in that: At least a portion of the surface of the housing is provided with a heat sink.

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