Capacitive liquid level sensor

Abstract

The capacitive liquid level sensor comprises an inner electrode metal rod and an outer electrode metal tube which are arranged inside and outside, an annular cavity is formed between the inner electrode metal rod and the outer electrode metal tube, an insulating layer is arranged on the outer ring of the inner electrode metal rod, and the lower end of the annular cavity is sealed through a lower insulating plug. The upper end of the annular cavity is sealed through the upper insulation plug, the upper end and the lower end of the outer electrode metal tube are respectively provided with an exhaust port and a liquid inlet which are communicated with the annular cavity, and the upper end of the outer electrode metal tube is fixedly connected with the junction box. The liquid level height can be displayed in real time, and oil liquid can be supplemented in time. And the height can be reduced according to the depth of the container to meet the measurement of different liquid level heights.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid level sensors, in particular to a capacitive liquid level sensor. Background Art

[0002] At present, a simple mechanical liquid level float switch is usually used in a closed container. It does not have a self-checking function, so it needs to be checked and maintained regularly. At the same time, the float is greatly affected by the viscosity and density of the liquid itself, and the measurement accuracy is poor. It may also cause frequent actions or false actions due to the movement of the liquid surface in the container. Utility Model Content

[0003] The utility model aims at the deficiencies of the prior art and provides a capacitive liquid level sensor.

[0004] The utility model is realized through the following technical scheme, and provides a capacitive liquid level sensor, comprising an inner electrode metal rod and an outer electrode metal tube arranged inside and outside, an annular cavity is formed between the inner electrode metal rod and the outer electrode metal tube, an insulating layer is arranged on the outer ring of the inner electrode metal rod, the lower end of the annular cavity is sealed by a lower insulating plug, the upper end of the annular cavity is sealed by an upper insulating plug, the upper and lower ends of the outer electrode metal tube are respectively provided with an exhaust port and a liquid inlet both connected to the annular cavity, and the upper end of the outer electrode metal tube is fixedly connected to a junction box.

[0005] In this scheme, an insulating layer is provided on the outer ring of the inner electrode metal rod to achieve insulation between the inner electrode metal rod and the outer electrode metal tube, thereby forming a capacitor through the annular cavity in the middle. The liquid level sensor obtains the liquid level through the tiny capacitance changes at different liquid level heights, which is processed by the conversion system and transmitted to the control system through the signal line, thereby realizing liquid level detection.

[0006] As an optimization, the lower end of the junction box is provided with an annular connecting tube, and the upper end of the outer electrode metal tube is inserted into the annular connecting tube. In this solution, the outer electrode metal tube is installed by inserting the upper end of the outer electrode metal tube into the annular connecting tube.

[0007] As an optimization, the outer ring of the annular connecting pipe is threaded with a round nut, and a sealing gasket is provided above the round nut at the bottom of the junction box. During installation, the junction box is located on the upper end surface of the liquid tank, the inner electrode metal rod and the outer electrode metal tube are inserted into the liquid surface through the hole on the liquid tank, and the round nut located below the top plate of the liquid tank is screwed into the annular connecting pipe. After tightening, the top plate of the liquid tank is clamped between the junction box and the annular connecting pipe, thus realizing the installation of the entire liquid level sensor. The sealing gasket improves the sealing effect here

[0008] As an optimization, the upper end of the junction box is bolted with a junction box cover. By opening the junction box cover, installation and maintenance of the internal circuit board can be achieved.

[0009] As an optimization, the insulating layer is a heat shrink tube, so as to achieve an insulating effect.

[0010] As an optimization, the inner electrode metal rod is a round tube and the upper and lower ends are respectively inserted with an upper insulating plug and a lower insulating plug. The inner electrode metal rod is a round tube and is sealed by inserting an upper insulating plug and a lower insulating plug at both ends.

[0011] As an optimization, the upper insulating plug and the lower insulating plug are respectively connected to the inner hole of the outer electrode metal tube through threads, thereby realizing the installation of the upper insulating plug and the lower insulating plug.

[0012] The beneficial effects of the utility model are as follows: the capacitive liquid level sensor of the utility model obtains the liquid level through the tiny capacitance change at different liquid level heights, and transmits it to the control system through the signal line, so as to display the liquid level in real time and facilitate timely replenishment of oil. The height can be reduced according to the depth of the container to meet the measurement of different liquid level heights. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the utility model;

[0014] Figure 2 This is the front view of the utility model;

[0015] Figure 3 This is a front sectional view of the utility model;

[0016] Figure 4 This is a partial enlarged view of the lower insulating plug of the utility model;

[0017] Figure 5 It is a partial enlarged view of the upper insulating plug of the utility model;

[0018] As shown in the figure:

[0019] 1. Outer electrode metal tube, 2. Inner electrode metal rod, 3. Insulation layer, 4. Lower insulation plug, 5. Junction box, 6. Upper insulation plug, 7. Round nut, 8. Sealing gasket, 9. Circuit board, 10. Cable, 11. Junction box cover, 12. Cable connector, 13. Liquid inlet, 14. Exhaust port. DETAILED DESCRIPTION

[0020] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0021] like Figures 1 to 5As shown, a capacitive liquid level sensor of the utility model comprises an inner electrode metal rod 2 and an outer electrode metal tube 1 arranged inside and outside, the inner electrode metal rod 2 and the outer electrode metal tube 1 are arranged concentrically, and the lengths are close or the same. The inner electrode metal rod 2 in this embodiment is a hollow round tube, and the inner electrode metal rod 2 and the outer electrode metal tube 1 are both made of stainless steel tubes. The combination of the inner electrode metal rod 2 and the outer electrode metal tube 1 is called a detection rod.

[0022] An annular cavity is formed between the inner electrode metal rod 2 and the outer electrode metal tube 1. The lower end of the annular cavity is sealed by the lower insulating plug 4, and the upper end of the annular cavity is sealed by the upper insulating plug 6. The upper and lower ends of the inner electrode metal rod 2 are respectively inserted into the upper insulating plug 6 and the lower insulating plug 4. The upper insulating plug 6 and the lower insulating plug 4 are respectively connected to the inner hole of the outer electrode metal tube 1 through threads.

[0023] The upper and lower ends of the outer electrode metal tube 1 are respectively provided with an exhaust port 14 and a liquid inlet 13 both connected to the annular cavity, so that liquid can enter the annular cavity from the liquid inlet 13 at the lower end, and the liquid level in the annular cavity is the same as the liquid level outside.

[0024] In order to prevent the conduction between the inner electrode metal rod 2 and the outer electrode metal tube 1, an insulating layer 3 is provided on the outer ring of the inner electrode metal rod 2, and the insulating layer 3 is a heat shrink tube. Glue is poured on the top of the lower insulating plug 4 to achieve the sealing of the lower end of the annular cavity, and the lower end of the heat shrink tube is buried in the solidified glue to improve the insulation effect.

[0025] The upper end of the outer electrode metal tube 1 is fixedly connected to the junction box 5. Specifically, the lower end of the junction box 5 is provided with an annular connecting tube, and the upper end of the outer electrode metal tube 1 is inserted into the annular connecting tube. The upper end of the upper insulating plug 6 is provided with an annular protrusion, which is located above the annular connecting tube. The annular connecting tube is provided with an inner protrusion. When the outer electrode metal tube 1 and the upper insulating plug 6 are threadedly connected, the inner protrusion is clamped between the annular protrusion and the end face of the outer electrode metal tube 1 to achieve the fixation of the outer electrode metal tube 1.

[0026] In order to realize the connection and installation between the liquid level sensor and the upper end surface of the liquid tank, the outer ring of the annular connecting pipe is threadedly connected with a round nut 7, and the bottom of the junction box 5 is provided with a sealing gasket 8 located above the round nut 7. The upper end panel of the liquid tank is located between the round nut 7 and the sealing gasket 8.

[0027] The inner electrode metal rod 2 and the outer electrode metal tube 1 are connected to the circuit board 9 through flexible cables respectively. The structure of the electrode metal rod and the circuit board is separated, which can avoid the weak vibration being transmitted to the circuit board during use, causing the capacitance change.

[0028] The circuit board 9 is connected to the outside through cables, and a cable connector 12 is installed on the side of the junction box 5 .

[0029] The upper end of the junction box 5 is bolted with a junction box cover 11, which is convenient for installation and maintenance of the internal circuit board 9.

[0030] The working principle is based on the flat plate capacitor formula c=εs / d, where ε is the dielectric constant, which is fixed for a certain medium; d is the distance between the two conductor planes, which is also fixed in this design, that is, the distance between the measuring rod and the electrode; s is the area, that is, length x width. If the probe rod is unfolded into a plane, the circumference of the rod is the width, and the length of the probe rod is the length. Therefore, based on the measured C, the other quantities are fixed, and the length of the probe rod can be obtained. When the lower end of the probe rod is inserted into diesel, that is, in the actual use scenario, the measured capacitance will change, which will also correspond to the change in the length of the probe rod.

[0031] The use of the utility model:

[0032] During installation, the junction box 5 is located on the upper end surface of the liquid tank, the inner electrode metal rod 2 and the outer electrode metal tube 1 are inserted into the liquid surface through the hole on the liquid tank, and the round nut 7 located below the top plate of the liquid tank is screwed into the annular connecting tube. After tightening, the top plate of the liquid tank is clamped between the junction box 5 and the annular connecting tube, thus realizing the installation of the entire liquid level sensor. The sealing gasket 8 improves the sealing effect here.

[0033] The liquid level sensor obtains the liquid level through the tiny capacitance changes at different liquid level heights, which is processed by the conversion system and transmitted to the control system through the signal line.

[0034] Of course, the above description is not limited to the above examples. The technical features not described in the present invention can be achieved by or by adopting the existing technology, which will not be repeated here. The above embodiments and drawings are only used to illustrate the technical scheme of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that the changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not deviate from the purpose of the present invention and should also fall within the scope of protection of the claims of the present invention.

Claims

1. A capacitive liquid level sensor, characterized in that: The invention comprises an inner electrode metal rod (2) and an outer electrode metal tube (1) arranged inside and outside, an annular cavity is formed between the inner electrode metal rod (2) and the outer electrode metal tube (1), an outer ring of the inner electrode metal rod (2) is provided with an insulating layer (3), the lower end of the annular cavity is sealed by a lower insulating plug (4), and the upper end of the annular cavity is sealed by an upper insulating plug (6), the upper and lower ends of the outer electrode metal tube (1) are respectively provided with an exhaust port (14) and a liquid inlet (13) both of which are connected to the annular cavity, and the upper end of the outer electrode metal tube (1) is fixedly connected to a junction box (5).

2. A capacitive liquid level sensor according to claim 1, characterized in that: The lower end of the junction box (5) is provided with an annular connecting tube, and the upper end of the outer electrode metal tube (1) is inserted into the annular connecting tube.

3. A capacitive liquid level sensor according to claim 2, characterized in that: The outer ring of the annular connecting pipe is threadedly connected with a round nut (7), and the bottom of the junction box (5) is provided with a sealing gasket (8) located above the round nut (7).

4. A capacitive liquid level sensor according to claim 1, characterized in that: The upper end of the junction box (5) is bolted to a junction box cover (11).

5. A capacitive liquid level sensor according to claim 1, characterized in that: The insulating layer (3) is a heat shrink tube.

6. A capacitive liquid level sensor according to claim 1, characterized in that: The inner electrode metal rod (2) is a round tube, and the upper and lower ends thereof are respectively inserted into an upper insulating plug (6) and a lower insulating plug (4).

7. A capacitive liquid level sensor according to claim 1, characterized in that: The upper insulating plug (6) and the lower insulating plug (4) are respectively connected to the inner hole of the outer electrode metal tube (1) via threads.

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