Capacitance measuring structure for three-section capacitance type LNG liquid level sensor

Abstract

The utility model relates to a capacitance measuring structure for a three-section capacitance type LNG liquid level sensor, which comprises an outer pipe and inner pipes, the inner pipes are divided into three sections which are respectively defined as an upper inner pipe, a middle inner pipe and a lower inner pipe, the upper and lower adjacent inner pipes are connected through a middle insulating part, the upper end of the upper inner pipe is provided with an upper insulating part, the lower end of the lower inner pipe is provided with a lower insulating part, and the lower insulating part is connected with the outer pipe. Shielding wire pipes are arranged in the upper inner pipe and the middle inner pipe, and lead wires connected with the inner pipes penetrate through the shielding wire pipes. The lower sides of the upper insulating part and the middle insulating part are respectively provided with a wire pressing plug, and the upper end and the lower end of the shielding wire pipe abut against the corresponding wire pressing plug and the middle insulating part. According to the utility model, the capacitance measurement structure is optimized, and shielding processing is carried out through the traffic jam lead, so that the influence on the measurement result is reduced, and the measurement precision is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to LNG liquid level sensor technical field, concretely relates to a capacitive measuring structure for three-section capacitive LNG liquid level sensor. BACKGROUND

[0002] The working principle of the capacitive liquid level meter is to convert the position change of the measured object into capacitance for measurement. This liquid level meter has the advantages of high resolution and fast dynamic response. With the continuous popularity of capacitive liquid level meters, there is a demand for measuring the liquid level of low-temperature solutions (medium temperature > -200 DEG C) such as liquid nitrogen and LNG in low-pressure environments (<2.5 MPa), especially in LNG storage tank applications. The utility model patent with authorization announcement number CN 217130968 U discloses an LNG cylinder with liquid level self-calibration function, which contains a cylindrical capacitive liquid level meter, including a liquid level meter outer tube and a liquid level meter inner tube. The liquid level meter inner tube is divided into three sections and constitutes three capacitive sensors with the liquid level meter outer tube, i.e. a three-section capacitive LNG liquid level sensor. In practice, it is found that the lead in the liquid level meter simply passes through, and each lead is connected to the corresponding inner tube to realize signal transmission, but the lead part has a certain influence on the measurement accuracy and can reduce the measurement accuracy. UTILITY MODEL CONTENT

[0003] The utility model aims at a capacitive measuring structure for three-section capacitive LNG liquid level sensor, which optimizes the design of the capacitive measuring structure and reduces the influence on the measurement accuracy.

[0004] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0005] The capacitive measuring structure for three-section capacitive LNG liquid level sensor includes an outer tube and an inner tube. The inner tube is provided with three sections, which are defined as upper inner tube, middle inner tube and lower inner tube. The upper and lower adjacent inner tubes are connected through a middle insulating piece. The upper end of the upper inner tube is provided with an upper insulating piece, and the lower end of the lower inner tube is provided with a lower insulating piece. Shielded wire tubes are arranged in the upper inner tube and the middle inner tube, and the lead for connecting the inner tube passes through the shielded wire tube.

[0006] Further, the shielded wire tube adopts a star-shaped fluorine tube.

[0007] Further, the lead of the upper part of the lower inner tube is pressed on the lower side of the middle insulating piece by the wire pressing plug and passes upward from the center hole of the middle insulating piece.

[0008] Further, the lead wire of the upper part of the intermediate inner tube is pressed by the wire pressing plug on the lower side of the intermediate insulating member and passes upward from the central hole of the intermediate insulating member.

[0009] Further, the lead wire part passing through the intermediate insulating member enters the shielded wire tube.

[0010] Further, radial holes are arranged on the outer tube for installing positioning screws, the positions of the radial holes correspond to the positions of the intermediate insulating members, the positioning screws are arranged in groups of three, and one end of the positioning screw is used for abutting against the outer periphery of the intermediate insulating member.

[0011] Further, the upper and lower ends of the outer tube are connected with the upper fixing member and the lower fixing member respectively, and the lower fixing member is used for fixing with the inner wall of the tank body.

[0012] Further, a sliding sleeve is arranged on the outer tube, the sliding sleeve is in sliding cooperation with the outer tube, and the upper end of the sliding sleeve is used for fixing with the inner wall of the tank body.

[0013] The utility model discloses beneficial effects:

[0014] The lead wire connected with the inner tube passes through the shielded wire tube, the shielded wire tube is made of a tetrafluoroethylene tube or other insulating materials, and the lead wire is shielded. One part of the lead wire is pressed on the lower side of the intermediate insulating member by the wire pressing plug, and another part of the lead wire is pressed on the lower side of the upper and lower insulating members by another wire pressing plug. The wire pressing plug not only makes the lead wire more stable after arrangement, but also is an insulating member and can play a certain shielding effect. The lead wire is shielded by plugging, the influence on the measurement result is reduced, and the measurement precision is improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the appearance diagram of the capacitance measuring structure of the three-section capacitance type LNG liquid level sensor;

[0016] Figure 2 is the partial view of the upper part of the capacitance measuring structure of the three-section capacitance type LNG liquid level sensor;

[0017] Figure 3 is the sectional view of the capacitance measuring structure of the three-section capacitance type LNG liquid level sensor;

[0018] Figure 4 is Figure 3 the schematic view of the middle section of the middle capacitance measuring structure;

[0019] Figure 5 is Figure 3 the schematic view of the upper section of the middle capacitance measuring structure;

[0020] Figure 6 is the perspective view of the shielded wire tube;

[0021] Figure 7 is a perspective view of the upper fixing member;

[0022] Figure 8 is a perspective view of the lower fixing member.

[0023] 1, outer tube; 11, lower fixing member; 111, liquid inlet hole; 112, upper protrusion; 12, upper fixing member; 121, exhaust hole; 122, lower protrusion; 2, sliding sleeve; 21, U-shaped groove; 3, lead sleeve; 41, upper insulating member; 42, middle insulating member; 43, lower insulating member; 5, wire pressing plug; 6, shield tube; 71, upper inner tube; 72, middle inner tube; 73, lower inner tube; 8, positioning screw. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the utility model will be clearly and completely described in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art belong to the protection scope of the utility model.

[0025] Embodiments of the utility model:

[0026] As shown in the drawings, Figures 1-8 The capacitive measuring structure for the three-section capacitive LNG liquid level sensor comprises an outer tube 1 and an inner tube, the inner tube is provided with three sections, which are defined as an upper inner tube 71, a middle inner tube 72 and a lower inner tube 73, the adjacent inner tubes are connected through a middle insulating member 42, the upper end of the upper inner tube 71 is provided with an upper insulating member 41, and the lower end of the lower inner tube 73 is provided with a lower insulating member 43. The adjacent inner tube sections are connected and insulated from each other by using the insulating members.

[0027] The shield tube 6 is arranged in the upper inner tube 71 and the middle inner tube 72, the shield tube 6 adopts a star-shaped PTFE tube, as shown in the drawings, Figure 6 The center of the star-shaped PTFE tube is a through hole penetrating from top to bottom, the outer edge structure of the star-shaped PTFE tube is in contact with the inner walls of the upper inner tube 71 and the middle inner tube 72 to realize stable support. The lead wire connected with the inner tube passes through the shield tube 6, the shield tube 6 adopts a PTFE tube (polytetrafluoroethylene tube), which shields the lead wire. The lead wire is used for transmitting data to collect the liquid level signal, which can be understood as a wire, and although the current is small, it can also affect the measurement result, so the PTFE tube is used for shielding.

[0028] As shown in the drawings, Figures 3 to 5As shown, the upper side of the upper insulation 41 and the lower side of the middle insulation 42 are respectively provided with a wire pressing plug 5, and the upper and lower ends of the shielded wire tube 6 abut against the corresponding wire pressing plug 5 and the middle insulation 42. The lead wire at the upper part of the lower inner tube 73 is pressed by the wire pressing plug 5 against the lower side of the middle insulation 42, and passes through the center hole of the middle insulation 42 upwards, and then passes through the two shielded wire tubes 6 in sequence, and finally passes out from the lead wire sleeve 3 at the upper end of the outer tube 1, and is connected with the transmitter, which is arranged outside the LNG storage tank. The LNG liquid level sensor is arranged inside the LNG storage tank.

[0029] The lead wire at the upper part of the middle inner tube 72 is pressed by the wire pressing plug 5 against the lower side of the middle insulation 42, and passes through the center hole of the middle insulation 42 upwards, and then passes through the upper shielded wire tube 6 upwards.

[0030] When the corresponding lead wire (not shown) is connected with the inner tube, the length of the inner tube welded with the head of the lead wire needs to be stripped of the sheath, shield and insulation, and the head of the lead wire is welded and fixed with the inner tube. In the product assembly, the wire pressing plug 5 is used to press a part of the lead wire against the lower side of the middle insulation 42, so that the lead wire is more stable, and in addition, the wire pressing plug 5 is also an insulation part which can also have a certain shielding effect.

[0031] The lead wire at the upper part of the middle inner tube 72 does not need to pass through the shielded wire tube 6, but is directly pressed by the wire pressing plug 5 against the lower side of the upper insulation 41, and passes through the center hole of the upper insulation 41 upwards, and finally passes out from the lead wire sleeve 3 at the upper end of the outer tube 1. It can be seen that three lead wires pass out from the lead wire sleeve 3. The wire hole of the lead wire sleeve 3 is arranged radially along the outer tube 1.

[0032] As shown in Figure 4 , the outer tube 1 is provided with a radial hole for installing a positioning screw 8, and the position of the radial hole corresponds to the position of the middle insulation 42. The positioning screw 8 is in a group of three, and one end of the positioning screw 8 is used to abut against the outer periphery of the middle insulation 42. By designing the positioning screw 8, the three inner tubes have better coaxiality.

[0033] As shown in Figure 1 , 7 and 8, the upper and lower ends of the outer tube 1 are respectively connected with an upper fixing part 12 and a lower fixing part 11, and the lower fixing part 11 is used to be fixed with the inner wall of the tank body of the LNG storage tank. The upper fixing part 12, the lower fixing part 11 and the outer tube 1 are stainless steel parts and can be welded. The upper fixing part 12 has a through hole penetrating from top to bottom, which can be used for the lead wire to pass upwards, and the lower part of the upper fixing part 12 has a downward lower protrusion 122 for the upper insulation 41 to be sleeved and assembled. The lower fixing part 11 has an upward upper protrusion 112 for the lower insulation 43 to be sleeved and assembled.

[0034] The upper fixing part 12 is also provided with an exhaust hole 121, so that there is no pressure difference between the sensor and the inside of the storage tank.

[0035] The lower fixing part 11 is provided with a plurality of liquid inlet holes 111, and the medium solution enters the sensor through the liquid inlet holes 111. The height of the medium solution inside the sensor changes with the change of the height of the medium solution in the storage tank. With the change of the height of the medium solution, the capacitance values of the three capacitors formed between the three inner tubes and the outer tube 1 change in real time. The program obtains the current real-time liquid level height value by processing the three groups of data. How to calculate the capacitance is a prior art and will not be described in detail.

[0036] As shown in Figure 1 and 2 , the outer tube 1 is provided with a sliding sleeve 2, the sliding sleeve 2 is in sliding fit with the outer tube 1, and the upper end of the sliding sleeve 2 is used for being fixed with the inner wall of the tank body of the LNG storage tank. One side of the sliding sleeve 2 is provided with a U-shaped groove 21, which is used for giving way to the lead sleeve 3 when the sliding sleeve 2 slides upward. By arranging the sliding sleeve 2, the axial length of the LNG liquid level sensor has a certain variable, which better adapts to the internal space of the LNG storage tank and reduces the manufacturing precision requirement of the axial length of the LNG liquid level sensor.

Claims

1. A capacitance measuring structure for a three-section capacitive LNG level sensor, comprising an outer tube, an inner tube, the inner tube being provided with three sections, respectively defined as an upper inner tube, a middle inner tube, and a lower inner tube, characterized in that: The upper and lower inner tubes are connected by an intermediate insulation member, the upper end of the upper inner tube is provided with an upper insulation member, the lower end of the lower inner tube is provided with a lower insulation member, the upper and intermediate inner tubes are provided with shielded wire tubes, and the lead wires connected to the inner tubes pass through the shielded wire tubes.

2. Capacitance measuring structure for a three-section capacitive LNG level sensor according to claim 1, characterized in that: The shielded wire tube is a star-shaped Teflon tube.

3. The capacitance measuring structure for a three-section capacitive LNG level sensor according to claim 1, characterized in that: The lead wires of the upper part of the lower inner tube are pressed by the wire pressing plug on the lower side of the intermediate insulation member and pass upward from the center hole of the intermediate insulation member.

4. The capacitance measuring structure for a three-section capacitive LNG level sensor according to claim 1, characterized in that: The lead wires of the upper part of the intermediate inner tube are pressed by the wire pressing plug on the lower side of the intermediate insulation member and pass upward from the center hole of the intermediate insulation member.

5. Capacitance measuring structure for a three-section capacitive LNG level sensor according to claim 1 or 4, characterized in that: The lead wire part passing through the intermediate insulation member enters the shielded wire tube.

6. The capacitance measuring structure for a three-section capacitive LNG level sensor according to claim 1, characterized in that: The outer tube is provided with radial holes for installing positioning screws, the positions of the radial holes correspond to the position of the intermediate insulation member, the positioning screws are in groups of three, and one end of the positioning screw is used for abutting against the outer periphery of the intermediate insulation member.

7. The capacitance measuring structure for a three-section capacitive LNG level sensor according to claim 1, characterized in that: The upper and lower ends of the outer tube are connected to upper and lower fixing members respectively, and the lower fixing member is used for fixing with the inner wall of the tank body.

8. Capacitance measuring structure for a three-section capacitive LNG level sensor according to claim 7, characterized in that: The outer tube is provided with a sliding sleeve, the sliding sleeve is in sliding cooperation with the outer tube, and the upper end of the sliding sleeve is used for fixing with the inner wall of the tank body.

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