CN110567553A - Top seal positioning structure for capacitive liquid level gauge and capacitive liquid level gauge - Google Patents

Abstract

The invention discloses a top sealing and positioning structure for a capacitive liquid level gauge and a capacitive liquid level gauge, wherein the top sealing and positioning structure includes a sealing positioning plug, a first sealing ring and a second sealing ring, and the sealing positioning plug is provided with a Set a fixed first mounting column for the negative tube of the capacitive liquid level gauge and a second mounting column for the positive tube of the capacitive liquid level gauge, the first mounting column and the second mounting column are coaxial The outer wall of the first installation column is provided with a first annular groove and the first mechanical seal structure, the outer wall of the second installation column is provided with a second annular groove and a second mechanical seal structure, and the first sealing ring is embedded In the first annular groove, the second sealing ring is embedded in the second annular groove. The top sealing and positioning structure disclosed by the invention can realize the installation and positioning of the positive tube and the negative tube, meet the concentricity requirements of the positive tube and the negative tube, can realize double sealing of the positive tube and the negative tube, and is simple to manufacture and low in cost.

Description

Top seal positioning structure for capacitive liquid level gauge and capacitive liquid level gauge

technical field

The invention relates to the structural technical field of capacitive liquid level gauges, in particular to a top sealing and positioning structure for capacitive liquid level gauges and the capacitive liquid level gauge.

Background technique

The capacitive liquid level gauge in the prior art includes a positive electrode tube and a negative electrode tube. The positive electrode tube is installed in the negative electrode tube. There is an opening at the bottom of the tank, through which a liquid medium of height H can be filled between the positive tube and the negative tube, and the capacitance formed by the capacitive liquid level gauge will change with the change of the liquid level height H.

In order to facilitate fixing, the top sealing positioning structure and the top of the positive tube, the top mounting flange and the top of the negative tube are generally fixedly connected by welding or extrusion, but this is not easy to disassemble, and its production cost high.

Contents of the invention

The object of the present invention is to provide a top sealing positioning structure and a liquid level sensor for a capacitive liquid level gauge, which aims to solve the gap between the top sealing positioning structure and the top of the positive tube of the capacitive liquid level gauge in the prior art. Generally, they are fixedly connected by welding or extrusion, which will be inconvenient to disassemble, low production efficiency and high production cost.

In order to achieve the above object, the scheme provided by the present invention is:

The invention provides a top sealing and positioning structure for a capacitive liquid level gauge, which is used for installing and fixing the negative and positive tubes of the capacitive liquid level gauge. The top sealing and positioning structure includes a sealing positioning plug, a first sealing ring and a second sealing ring, the sealing positioning plug is provided with a first mounting column for the sleeve fixing of the negative electrode tube and a second mounting column for the sleeve fixing of the positive electrode tube, the first installation The outer diameter of the column is larger than the outer diameter of the second installation column and the first installation column is coaxially arranged with the second installation column, the outer side wall of the first installation column is concavely provided with a first annular groove and The first mechanical seal structure used for the mechanical seal of the negative electrode tube is convexly provided, the outer wall of the second mounting column is concavely provided with a second annular groove and the second mechanical seal used for the mechanical seal of the positive electrode tube is convexly provided structure, the first sealing ring is embedded in the first annular groove, and the second sealing ring is embedded in the second annular groove.

Further, the first mechanical seal structure is a plurality of first annular protrusions protruding from the outer wall of the first mounting column and spaced along the axial direction of the first mounting column; The sealing structure is a plurality of second annular protrusions protruding from the outer wall of the second mounting column and spaced along the axial direction of the second mounting column.

Further, the first annular groove is arranged in the middle of the first mechanical seal structure.

Further, the outer wall of the first installation post away from the end of the second installation post is provided with a first stop protrusion for forming an axial stop for the negative electrode tube.

Further, the side of the first mounting column away from the second mounting column is further provided with a supporting positioning column for fixing the PCB board.

Further, the second annular groove is disposed on a side of the second mechanical seal structure away from the first mechanical seal structure and spaced apart from the second mechanical seal structure.

Further, the outer wall of the end of the second mounting column close to the first mounting column is provided with a second limiting protrusion for axially limiting the positive tube, and the second limiting protrusion The outer diameter is smaller than the outer diameter of the first mounting column.

Further, the top sealing positioning structure also includes a contact piece and a self-tapping screw, and the sealing positioning plug is provided with a threading hole for passing the electrode lead wire and a positioning hole communicating with the threading hole. The dot piece includes a base plate and side plates arranged on opposite sides of the base plate, the base plate is provided with mounting holes, and the self-tapping screws pass through the mounting holes and then tap into the positioning holes to fix the base plate At the bottom of the sealing positioning plug, the two side plates are stretched apart to abut against the positive tube.

The present invention also provides a capacitive liquid level gauge, including a positive tube, a negative tube, and the above-mentioned top sealing positioning structure, the negative tube is sleeved outside the first installation column, and the negative tube is connected to the first mounting column. The first installation column is interference fit, the positive tube is sleeved outside the second installation column and the positive tube is interference fit with the second installation column, and the contact piece is partially clamped on the second installation column. between the first mounting column and the positive tube.

Further, the capacitive liquid level gauge also includes a PCB board, an electrode lead wire and a conductive sheet, one end of the electrode lead wire is connected to the contact sheet, and the other end is connected to the PCB board after passing through the wire hole , one end of the conductive sheet is electrically connected to the cathode tube, and the other end is connected to the PCB board.

Compared with the prior art, the beneficial effects of the present invention are:

When the top sealing and positioning structure disclosed in the present invention is applied to a capacitive liquid level gauge, between the first installation column and the negative tube, and between the second installation column and the positive tube, the sealing ring is used to seal first, and then the mechanical seal is used to realize double sealing. Sealing, good sealing effect;

The U-shaped contact piece and the self-tapping screw are fastened to the inner wall of the positive tube, so that the concentricity between the positive tube and the negative tube is high, the performance of the capacitive liquid level gauge is excellent, and the measurement accuracy is high;

The entire top sealing positioning structure has a compact overall structure and exquisite design, which can effectively reduce the size of the product and is easy to install. In addition, the top sealing and positioning structure disclosed in the present invention can be formed by injection molding, which is simple to manufacture and can effectively reduce costs.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to the structures shown in these drawings without creative effort.

Fig. 1 is a cross-sectional view after assembly of the top sealing positioning structure, positive tube and negative tube for capacitive liquid level gauge provided by the embodiment of the present invention;

Fig. 2 is a cross-sectional view of the sealing positioning plug provided by the embodiment of the present invention;

Fig. 3 is a cross-sectional view of a contact sheet provided by an embodiment of the present invention;

Fig. 4 is a cross-sectional view of the top of the capacitive liquid level gauge provided by the embodiment of the present invention;

Fig. 5 is a top view of the cathode tube provided by the embodiment of the present invention;

Fig. 6 is a cross-sectional view of the bottom of the capacitive liquid level gauge provided by the embodiment of the present invention.

In the figure: 10, negative electrode tube; 20, positive electrode tube; 30, sealing positioning plug; 31, first mounting column; 311, first annular groove; 312, first mechanical seal structure; 313, first limit protrusion ; 314, support positioning column; 32, second mounting column; 321, second annular groove; 322, second mechanical seal structure; 323, second limit protrusion; 324, card slot; 33, threading hole; 331 , first perforation; 332, second perforation; 34, positioning hole; 40, first sealing ring; 50, second sealing ring; 60, PCB board; 70, contact piece; 71, bottom plate; 711, installation hole; 72, side plate; 80, self-tapping screw; 90, electrode lead wire; 100, conductive sheet; 200, protective cover; 210, cavity; 220, third perforation; 230, top cover; 240, flange plate; 250, 260, exhaust hole; 300, rubber plug; 400, positioning seat; 410, liquid inlet hole; 500, rib plate; 510, opening groove; 600, the third sealing ring.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relationship between the components in a certain posture (as shown in the accompanying drawings). Relative positional relationship, movement conditions, etc., if the specific posture changes, the directional indication will also change accordingly.

It should also be noted that when an element is referred to as being “fixed” or “disposed on” another element, it can be directly on the other element or intervening elements may also exist. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present.

In addition, the descriptions involving "first", "second" and so on in the present invention are only for descriptive purposes, and should not be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In addition, the technical solutions of the various embodiments can be combined with each other, but it must be based on the realization of those skilled in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist , nor within the scope of protection required by the present invention.

Please refer to Figures 1 to 6, the embodiment of the present invention provides a top sealing positioning structure for a capacitive liquid level gauge, which is used for the installation and fixing of the negative electrode tube 10 and the positive electrode tube 20 of the capacitive liquid level gauge, Wherein, the positive electrode tube 20 is installed in the negative electrode tube 10, and the top sealing and positioning structure includes a sealing positioning plug 30, a first sealing ring 40 and a second sealing ring 50, and the sealing positioning plug 30 is provided with a sleeve for fixing the negative electrode tube 10. The first installation column 31 and the second installation column 32 for being sleeved and fixed for the positive tube 20, the outer diameter of the first installation column 31 is greater than the outer diameter of the second installation column 32 and the first installation column 31 and the second installation column 32 is coaxially arranged to ensure that the positive electrode tube 20 and the negative electrode tube 10 are also coaxially arranged, and the positive electrode tube 20 and the negative electrode tube 10 do not touch together. Both the positive tube 20 and the negative tube 10 in this embodiment are preferably metal tubes made of aluminum, and of course other metal tubes that can generate capacitance after combination can also be selected.

Please refer to FIGS. 1 to 2 , the outer wall of the first mounting post 31 is concavely provided with a first annular groove 311 and protrudingly provided with a first mechanical seal structure 312 for mechanical sealing of the negative electrode tube 10 , and the outer side of the second mounting post 32 The wall is concavely provided with a second annular groove 321 and protrudingly provided with a second mechanical seal structure 322 for mechanical sealing of the positive electrode tube 20. The first sealing ring 40 is embedded in the first annular groove 311, and the second sealing ring 50 is embedded in the first annular groove 311. It is arranged in the second annular groove 321 to realize the double sealing of the top of the positive tube 20 and the double sealing of the top of the negative tube 10 .

Preferably, the first mechanical seal structure 312 is a plurality of first annular protrusions protruding from the outer wall of the first mounting column 31 and arranged at intervals along the axial direction of the first mounting column 31; the second mechanical sealing structure 322 is a plurality of A second annular protrusion protruding from the outer wall of the second mounting column 32 and arranged at intervals along the axial direction of the second mounting column 32, the first annular protrusion and the second annular protrusion are in the shape of an inverted zigzag after the section, The mechanical seal can prevent external water, dust layer, etc. from entering the negative tube 10 or the positive tube 20 from the top of the capacitive liquid level gauge.

As a preferred embodiment, the first annular groove 311 is arranged in the middle of the first mechanical seal structure 312, and the first sealing ring 40 is also mechanically sealed, so that the sealing positioning plug 30 has oil-proof, waterproof and sealing properties .

As a preferred embodiment, the outer wall of the first mounting post 31 away from the end of the second mounting post 32 is provided with a first stop protrusion 313 for axially limiting the negative tube 10 to prevent the negative tube 10 from being positioned with the seal. Slippage occurs between the plugs 30.

As a preferred embodiment, the side of the first mounting column 31 away from the second mounting column 32 is further provided with a supporting positioning column 314 for fixing the PCB board 60 , so as to facilitate the installation and fixing of the PCB board 60 .

In this embodiment, the second annular groove 321 is disposed on the side of the second mechanical seal structure 322 away from the first mechanical seal structure 312 and spaced from the second mechanical seal structure 322 , since the positive tube 20 is inside the negative tube 10 , the requirements between the positive tube 20 and the sealing positioning plug 30 are reduced, and each sealing ring is preferably made of rubber material, and a double seal of a mechanical gap seal and a rubber elastic seal is used between the second mounting column 32 and the positive tube 20 .

As a preferred embodiment, the outer wall of the second mounting column 32 near the end of the first mounting column 31 is provided with a second limiting protrusion 323 for axially limiting the positive tube 20 , and the second limiting protrusion 323 The outer diameter of the outer diameter is smaller than the outer diameter of the first mounting column 31 to prevent slippage between the positive tube 20 and the sealing positioning plug 30 .

Please refer further to FIG. 3 , the top sealing positioning structure also includes a contact piece 70 and a self-tapping screw 80 , and the sealing positioning plug 30 is provided with a threading hole 33 for passing the electrode lead wire 90 and a positioning hole 34 communicating with the threading hole 33 , the positioning hole 34 extends axially from the bottom of the sealing positioning plug 30, the contact piece 70 is preferably U-shaped, the contact piece 70 includes a bottom plate 71 and side plates 72 located on opposite sides of the bottom plate 71, the second mounting column 32 is provided with a card slot 324 compatible with the side plate 72 on the outer wall of the side away from the first mounting column 31, and the bottom plate 71 is provided with a mounting hole 711, and the self-tapping screw 80 passes through the mounting hole 711 and directly taps into the positioning hole 34 to fix the bottom plate 71 on the bottom of the sealing positioning plug 30. When the self-tapping screw 80 is tightened, the two side plates 72 are stretched to abut the positive tube 20, so that the contact piece 70 is squeezed and deformed, and the deformation increases The frictional force between the sealing positioning plug 30 and the positive tube 20 is used to closely contact the sealing positioning plug 30 with the positive tube 20 to form a good electrical connection. At the same time, in order to facilitate the deformation of the contact piece 70 , the length of the slot 324 in the axial direction of the second mounting column 32 is smaller than the length of the side plate 72 in the axial direction of the second mounting column 32 .

In order to reduce the cost, the threading hole 33 in this embodiment includes a first through hole 331 and a second through hole 332 arranged at an angle with the first through hole 331, the inner diameter of the second through hole 332 is larger than the inner diameter of the first through hole 331, so as to facilitate Threading is smoother in the back, and the electrode leads 90 pass through the first through hole 331 and the second through hole 332 for electrical connection with the PCB board 60 , and the second through hole 332 is coaxially arranged with the positioning hole 34 .

Please refer to Fig. 4 further. The present invention also provides a capacitive liquid level gauge, which includes a positive tube 20, a negative tube 10 and the above-mentioned top sealing positioning structure, and the negative tube 10 is sleeved outside the first mounting column 31. And the negative tube 10 is interference fit with the first mounting column 31, the positive tube 20 is sleeved outside the second mounting column 32 and the positive tube 20 is interference fit with the second mounting column 32, and the contact piece 70 is partially stuck on the first mounting column 32. Between the mounting column 31 and the positive tube 20, the positive tube 20 and the contact piece 70 are stably installed on the first mounting column 31, and can ensure the concentricity of the negative tube 10 and the positive tube 20, reducing the production of the capacitive liquid level gauge cost.

The capacitive liquid level gauge also includes a PCB board 60, an electrode lead 90 and a conductive sheet 100. One end of the electrode lead 90 is connected to the contact sheet 70, and the other end is connected to the PCB board 60 after passing through the mounting hole 711. One end of the conductive sheet 100 It is electrically connected with the cathode tube 10 , and the other end is connected with the PCB board 60 , so as to realize the electrical connection between the cathode tube 10 , the positive tube 20 and the PCB board 60 .

The capacitive liquid level gauge also includes a protective cover 200. The protective cover 200 has a cavity 210 and a third perforation 220 communicating with the cavity 210. The protective cover 200 includes a top cover 230 and a flange sleeved outside the negative electrode tube 10. plate 240, the top cover 230 is installed on the flange plate 240 and surrounds the flange plate 240 to form the cavity 210 and the third through hole 220, the external circuit is electrically connected to the PCB board 60 through the third through hole 220, The PCB board 60, the sealing positioning plug 30, the contact piece 70, the electrode lead 90, the conductive piece 100 and the self-tapping screw 80 are all located in the cavity 210, and the protective cover 200 can effectively prevent the external dust layer or water from entering the PCB board 60 On the other hand, the flange 240 is also provided with a through hole 250 for external screws to pass through, so as to fix the capacitive liquid level gauge on the oil tank.

Please refer to Fig. 5 and Fig. 6 further, the capacitive liquid level gauge also includes a rubber plug 300 and a positioning seat 400. A third sealing ring 600 is arranged between them to realize the double sealing of the mechanical gap seal between the bottom of the positive electrode tube 20 and the rubber plug 300 and the elastic seal of the rubber part, so as to prevent the liquid to be measured from entering the positive electrode tube 20, and the positioning seat 400 is simultaneously connected with the positive electrode tube 20. The positive electrode tube 20 and the negative electrode tube 10 are connected to separate the bottoms of the positive electrode tube 20 and the negative electrode tube 10, and at the same time, a liquid inlet hole 410 is provided on the positioning seat 400, so that the liquid enters the outside of the positive electrode tube 20 from the liquid inlet hole 410 wall and the inner wall of the negative tube 10. The capacitance value of the capacitive liquid level gauge in this embodiment has a linear relationship with the liquid height between the positive tube 20 and the negative tube 10 .

At the same time, in order to prevent the negative electrode tube 10 from colliding, a number of reinforcing ribs 500 are protruding from the outer wall of the negative electrode 10, specifically four reinforcing ribs 500, and the protective cover 200 is covered outside the reinforcing ribs 500 by injection molding. . Specifically, the outer wall of the rib plate 500 away from the positive tube 20 is recessed with an opening groove 510, and the opening groove 510 runs through both ends of the rib plate 500 in the axial direction, so there is one at each end of the opening groove 510. Mounting port. The capacitive liquid level gauge of the present invention additionally includes eight self-tapping screws 80, wherein two self-tapping screws 80 pass through the conductive sheet 100 and then tap into the top mounting openings of the two open grooves 510, so that the self-tapping screws 80 can be easily used. Fix the conductive sheet 100; the other two self-tapping screws 80 directly pass through the sealing positioning plug 30 and then tap into the top mounting openings of the other two open grooves 510, relying on the tension force of the self-tapping screws 80 to make the negative electrode tube 10 and the flange The disc 240 is more firmly bonded. The remaining four self-tapping screws 80 pass through the positioning seat 400 and tap into the bottom installation openings of each opening groove 510 , so that the negative electrode tube 10 and the positioning seat 400 are fixed more firmly.

As a preferred embodiment, the upper end of the capacitive liquid level gauge is also provided with a vent hole 260, and the vent hole 260 extends from the outer wall of the flange 240 to the inner wall of the negative electrode tube 10 through the rib plate 500. When the liquid When entering through the bottom liquid inlet 410 of the capacitive liquid level gauge, the gas between the positive tube 20 and the negative tube 10 can be discharged through the exhaust hole 260 to avoid pressure difference.

The installation steps of the capacitive liquid level gauge of the present invention are as follows: the flange plate 240 is injected on the outer wall of the top of the negative electrode tube 10, the first sealing ring 40 is installed in the first annular groove 311, and the second sealing ring 50 is installed in the first annular groove 311. In the second annular groove 321, the self-tapping screw 80 penetrates through the contact piece 70 and partially penetrates into the positioning hole 34. At this time, do not continue to screw the self-tapping screw 80 to avoid deformation of the contact piece 70. 20 is sleeved on the second mounting column 32, the second mechanical seal structure 322 is mechanically sealed by a machine, and then the self-tapping screw 80 is tightened to deform the contact piece 70 so that the positive electrode tube 20 and the first mounting column 31 is more firmly installed, and then the negative tube 10 is sleeved on the second mounting column 32, and the first mechanical sealing structure 312 and the first sealing ring 40 are mechanically sealed by a machine, and then four self-tapping screws 80 are sequentially Install and fix the PCB board 60, the electrode lead 90 and the conductive sheet 100, and then cover the top cover 230 to realize the fixed sealing of the top of the capacitive liquid level gauge; mechanically seal the rubber plug 300 and the bottom of the positive tube 20 with a machine, Then, the positioning seat 400 is installed on the bottom of the negative electrode tube 10 through four self-tapping screws 80 and abuts against the rubber plug 300 to realize the fixed and sealed bottom of the capacitive liquid level gauge.

When the top sealing and positioning structure disclosed in the present invention is applied to a capacitive liquid level gauge, firstly, between the first mounting post 31 and the negative tube 10, and between the second mounting post 32 and the positive tube 20 are all sealed with a sealing ring first and then sealed. A mechanical seal is used to achieve double sealing, and the sealing effect is good; secondly, the U-shaped contact piece 70 and the self-tapping screw 80 are fastened to the inner wall of the positive tube 20, so that the concentricity between the positive tube 20 and the negative tube 10 is high, The capacitive liquid level gauge has excellent performance and high measurement accuracy; moreover, the entire top sealing and positioning structure has a compact overall structure and exquisite design, which can effectively reduce the size of the product and is easy to install. In addition, the top sealing and positioning structure disclosed in the present invention can be molded through injection molding to simultaneously connect the mechanics and electronics among the flange 240, the negative tube 10, the positive tube 20, and the PCB board 60, thus playing a highly comprehensive role. Plastic injection molding with insulating and oil-resistant properties realizes rapid mass production, simple manufacturing, and can effectively reduce costs.

The above is only a preferred embodiment of the present invention, and does not therefore limit the patent scope of the present invention. Under the inventive concept of the present invention, the equivalent structural transformation made by using the description of the present invention and the contents of the accompanying drawings, or direct/indirect use All other relevant technical fields are included in the patent protection scope of the present invention.

Claims (10)

1. A top sealing and positioning structure for a capacitive liquid level meter is used for installing and fixing a cathode tube and an anode tube of the capacitive liquid level meter and is characterized in that the top sealing and positioning structure comprises a sealing and positioning plug, a first sealing ring and a second sealing ring, the sealing and positioning plug is provided with a first installation column for fixing a cathode tube sleeve and a second installation column for fixing an anode tube sleeve, the outer diameter of the first installation column is larger than that of the second installation column, the first installation column and the second installation column are coaxially arranged, a first annular groove is concavely arranged on the outer side wall of the first installation column, a first mechanical sealing structure for mechanical sealing of the cathode tube is convexly arranged, a second annular groove is concavely arranged on the outer side wall of the second installation column, and a second mechanical sealing structure for mechanical sealing of the anode tube is convexly arranged, the first sealing ring is embedded in the first annular groove, and the second sealing ring is embedded in the second annular groove.

2. The top seal positioning structure of claim 1, wherein the first mechanical seal structure is a plurality of first annular protrusions protruding from the outer sidewall of the first mounting post and spaced apart from each other in the axial direction of the first mounting post; the second mechanical sealing structure is a plurality of second annular bulges which are convexly arranged on the outer side wall of the second mounting column and are arranged at intervals along the axial direction of the second mounting column.

3. The top seal positioning structure of claim 1, wherein the first annular groove is provided in a middle portion of the first mechanical seal structure.

4. The top seal positioning structure of claim 1, wherein an outer side wall of one end of the first mounting post, which is far away from the second mounting post, is provided with a first limiting protrusion for axially limiting the cathode tube.

5. The top seal positioning structure of claim 3, wherein a side of the first mounting post remote from the second mounting post is further provided with a support positioning post for fixing a PCB.

6. The top seal positioning structure of claim 1, wherein said second annular groove is provided on a side of said second mechanical seal structure remote from said first mechanical seal structure and spaced from said second mechanical seal structure.

7. The top seal positioning structure of claim 5, wherein the outer side wall of the second mounting column near one end of the first mounting column is provided with a second limiting protrusion for axially limiting the positive tube, and the outer diameter of the second limiting protrusion is smaller than that of the first mounting column.

8. The top seal positioning structure according to claim 1, further comprising a contact piece and a tapping screw, wherein the seal positioning plug is provided with a threading hole for passing an electrode lead and a positioning hole communicated with the threading hole, the contact piece comprises a bottom plate and side plates arranged on two opposite sides of the bottom plate, the bottom plate is provided with a mounting hole, the tapping screw penetrates through the mounting hole and then taps into the positioning hole to fix the bottom plate at the bottom of the seal positioning plug, and the two side plates are spread to abut against the anode tube.

9. a capacitance type liquid level meter comprises an anode tube, a cathode tube and the top sealing and positioning structure as claimed in claim 8, wherein the cathode tube is sleeved outside the first mounting column and is in interference fit with the first mounting column, the anode tube is sleeved outside the second mounting column and is in interference fit with the second mounting column, and the contact point piece is partially clamped between the first mounting column and the anode tube.

10. The capacitive liquid level gauge according to claim 9, further comprising a PCB, an electrode lead and a conductive sheet, wherein one end of the electrode lead is connected to the contact sheet, the other end of the electrode lead passes through the threading hole and is connected to the PCB, one end of the conductive sheet is electrically connected to the cathode tube, and the other end of the conductive sheet is connected to the PCB.