A magnetohydrodynamic sealed sensor

Abstract

The present invention relates to a magnetofluid-sealed sensor in the field of sensors. On one side of a ceramic substrate, there are provided a first electrode plate, a second electrode plate, a resistance plate, and a plurality of comb-shaped electrode pieces. The resistance plate connects the first electrode plate with the plurality of comb-shaped electrode pieces. External connection parts are respectively provided on the first electrode plate and the second electrode plate for signal input and output. An internal connection part is provided on the second electrode plate, and the shape of the internal connection part corresponds to that of the comb-shaped electrode pieces. A magnetofluid capable of connecting the two is provided between the internal connection part and the end of the comb-shaped electrode piece. A sealing cover plate is provided on one side of the ceramic substrate where the first electrode plate, the second electrode plate, the resistance plate, and the plurality of comb-shaped electrode pieces are located. A through hole for injecting the magnetofluid is provided on the sealing cover plate, and a sealing plug is provided at the position of the through hole. A magnet is provided on the other side of the ceramic substrate corresponding to the position of the magnetofluid. It has good sealing performance and good corrosion resistance. Its production cost is low and its service life is long. It can be used for liquid level detection.

Description

Technical Field

[0001] The present invention relates to a liquid level detection sensor, and particularly to a magnetic fluid sensor for detecting the fuel level in an automotive fuel system or the liquid level of a solution. Background Art

[0002] Due to the differences in fuel quality on the market and the development of various gasoline containing methanol, ethanol, etc., the requirements for the corrosion resistance of the fuel level sensor in various fuel environments are getting higher and higher, and the traditional fuel level sensor can no longer meet the requirements of customers.

[0003] In the Chinese patent database, a thick film resistive liquid level sensor is disclosed, with the publication (announcement) number: CN201269770Y; the publication (announcement) date: July 8, 2009. This device is a sensor device that converts the liquid level into a corresponding resistance value output. It includes a thick film resistor plate, a lever, a slide holder, a float, a conductive spring, a resistor plate holder, a resistor plug-in group, a slide, a contact, a comb-shaped electrode area, a thick film resistor strip, a starting resistor, an output terminal, and an output terminal. Two groups of thick film resistor strips with a common end point and two groups of fan-shaped comb-shaped electrode areas connected thereto are provided on the thick film resistor plate, and the two groups of comb-shaped electrode areas are opposite and arranged in a staggered manner; the slide is in the form of two sets of front and rear, with two slide bodies in each set, and the contact is also in the form of two sets of front and rear, with two contact bodies in each set. The four contact bodies are respectively arranged on the four slide bodies. The float is fixed on the lever, and the lever is fixed to the slide and the slide holder to form a lever mechanism. One output terminal of the slide and the thick film resistor plate is connected together by welding through a conductive spring. In the resistor plate holder, the output terminal, the starting resistor, the two groups of thick film resistors, the two groups of comb-shaped electrodes, the slide, the conductive spring, and the other output terminal are electrically connected in sequence. As the liquid level changes, the float will drive the lever mechanism to rotate around the axis of the slide holder, and the two contacts of the slide in contact with the thick film resistor plate will also rotate around this axis. The two contacts always contact the two groups of comb-shaped electrodes of the thick film resistor plate during the rotation process. As the position changes, the sensor output terminal will output a corresponding resistance value, thereby realizing the detection of the liquid level.

[0004] Its disadvantages are as follows: 1. This fuel level sensor is not a closed structure, and its thick film resistor strip, slide, contact, comb-shaped electrode area, etc. are all exposed to the detection environment, with poor corrosion resistance and relatively poor detection accuracy. 2. To ensure good contact of the electrodes, contacts and comb-shaped electrodes with relatively high precision are required, and the material requirements for the contacts and comb-shaped electrode areas are also very high. Precious metal materials with good electrical conductivity are required, and the cost is relatively high. 3. The contacts and comb-shaped electrodes slide relative to each other during operation, with large wear, easy failure, and short service life. Summary of the Invention

[0005] The object of the present invention is to provide a magnetic fluid sealed sensor with good sealing performance, better corrosion resistance, low production process requirements, which can reduce costs, and at the same time, it has a long service life.

[0006] The object of the present invention is achieved as follows: A magnetic fluid sealed sensor includes a ceramic substrate. On one side of the ceramic substrate, there are a first electrode plate, a second electrode plate, a resistance plate, and a plurality of comb-shaped electrode pieces. The resistance plate connects the first electrode plate and the plurality of comb-shaped electrode pieces. External connection parts are respectively provided on the first electrode plate and the second electrode plate for signal input and output. An internal connection part is provided on the second electrode plate. The shape of the internal connection part corresponds to that of the comb-shaped electrode pieces. A magnetic fluid capable of connecting the two is provided between the internal connection part and the ends of the comb-shaped electrode pieces. A sealing cover plate is provided on the side of the ceramic substrate where the first electrode plate, the second electrode plate, the resistance plate, and the plurality of comb-shaped electrode pieces are located. A through hole for injecting magnetic fluid is provided on the sealing cover plate, and a sealing plug is provided at the position of the through hole. A magnet is provided on the other side of the ceramic substrate corresponding to the position of the magnetic fluid.

[0007] When the present invention is in use, the magnet needs to be linked with a float for detecting the liquid level, so that the magnet moves with the change of the liquid level. The external connection parts on the first electrode plate and the second electrode plate are connected to an external circuit for signal input and output. During operation, the magnet drives the magnetic fluid to move. The magnetic fluid is a colloidal solution. Under the action of a magnetic field, this liquid neither settles nor aggregates and has the property of being attracted by the magnet itself. The present invention utilizes the fluidity and conductivity of the magnetic fluid to connect resistors and electrodes at different positions, outputs different resistance values, and corresponds the resistance values to the liquid levels one by one, so as to detect the corresponding liquid levels. Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The first electrode plate, the second electrode plate, the resistance plate, the comb-shaped electrode pieces and the magnetic fluid of the present invention do not contact the liquid to be detected, so it has good corrosion resistance and can be applied to the oil level detection of various automotive fuels. 2. The magnetic fluid is a stable colloid with a simple structure and a long service life. The magnet drives the magnetic fluid to move in a rolling manner, without involving wear problems, and its use reliability is very high. 3. Its production cost is low, without the need for precious metal materials or high-precision contact pieces. This device can be used for liquid level detection, especially suitable for oil level detection in fuel tanks.

[0008] As a further improvement of the present invention, the comb-shaped electrode pieces are distributed in a fan shape, the internal connection part is arranged in an arc shape, and the internal connection part is equidistant from the ends of each comb-shaped electrode piece. This structure enables the magnet to be better connected with the float in the prior art. The float rotates around its rotating shaft, and the magnet can be arranged on the rotating rod of the float. When it moves, the movement trajectory of the magnet is an arc shape, and the movement of the magnetic fluid can better match it.

[0009] As a further improvement of the present invention, the outer connection parts of the first electrode plate and the second electrode plate are arranged to pass through the ceramic substrate, and are hermetically connected between the outer connection parts and the ceramic substrate. This can better achieve the sealing of the first electrode plate, the second electrode plate, the resistance plate, the plurality of comb-shaped electrode pieces and the magnetorheological fluid.

[0010] As a further improvement of the present invention, a groove for the magnetorheological fluid to slide therein is provided on the side of the sealing cover plate facing the ceramic substrate. The setting of the groove restricts the movement of the magnetorheological fluid, enabling it to remain in the groove and move more reliably.

[0011] As a further improvement of the present invention, conductor materials of the same material as the first electrode plate, the second electrode plate and the plurality of comb-shaped electrode pieces are provided around the periphery of the side of the ceramic substrate facing the sealing cover plate. The sealing cover plate is made of a metal material, and the conductor material is printed on the ceramic substrate by SMT process and sintered to connect the sealing cover plate with the ceramic substrate. This structure seals and welds the sealing cover plate to the ceramic substrate, with reliable welding and good sealing, and can be printed on the ceramic substrate simultaneously with the first electrode plate, the second electrode plate and the plurality of comb-shaped electrode pieces.

[0012] As a further improvement of the present invention, the magnetorheological fluid is a ferromagnetic conductive fluid mixed with Fe, Ni, Co nanoparticles as the main components, an organic solvent as the base liquid, and oleic acid as the surfactant. This solution ensures that the magnetorheological fluid has good ferromagnetic effects and also has good conductivity. Description of the Drawings

[0013] Figure 1 is a three-dimensional structural schematic diagram of the magnetorheological fluid closed sensor of the present invention.

[0014] Figure 2 is the front view of the magnetorheological fluid closed sensor of the present invention.

[0015] Figure 3 is Figure 2 the view in the direction of A-A of

[0016] Figure 4 is a planar structural schematic diagram of the present invention with the sealing gland removed.

[0017] Figure 5 is Figure 4 the three-dimensional structural schematic diagram of another angle corresponding to the present invention.

[0018] In the figure, 1 is the sealing gland, 2 is the ceramic substrate, 3 is the magnet, 4 is the groove, 5 is the sealing plug, 6 is the magnetorheological fluid, 7 is the second electrode plate, 7b is the inner connection part, 8 is the resistance plate, 9 is the first electrode plate, 7a, 9a are the outer connection parts, and 10 is the comb-shaped electrode piece. Detailed Embodiments

[0019] As shown in Figures 1-5, a magneto-fluid sealed sensor is provided, which includes a ceramic substrate 2. On one side of the ceramic substrate 2, there are a first electrode plate 9, a second electrode plate 7, a resistance plate 8, and a plurality of comb-shaped electrode pieces 10. The resistance plate 8 connects the first electrode plate 9 with the plurality of comb-shaped electrode pieces 10. External connection parts 7a and 9a are respectively provided on the first electrode plate 9 and the second electrode plate 7 for signal input and output. An internal connection part 7b is provided on the second electrode plate 7. The shape of the internal connection part 7b corresponds to that of the comb-shaped electrode pieces 10. A magneto-fluid 6 that can connect the two is provided between the internal connection part 7b and the end of the comb-shaped electrode piece 10. On one side of the ceramic substrate 2 where the first electrode plate 9, the second electrode plate 7, the resistance plate 8, and the plurality of comb-shaped electrode pieces 10 are provided, there is a sealing cover plate 1. A through hole for injecting the magneto-fluid 6 is provided on the sealing cover plate 1, and a sealing plug 5 is provided at the position of the through hole. On the other side of the ceramic substrate 2, a magnet 3 is provided corresponding to the position of the magneto-fluid 6.

[0020] The comb-shaped electrode pieces 10 are distributed in a fan shape. The internal connection part 7b is arranged in an arc shape, and the internal connection part 7b is equidistant from the ends of the respective comb-shaped electrode pieces 10. This structure enables the magnet 3 to be better connected to the float in the prior art. The float rotates around its rotating shaft, and the magnet 3 can be arranged on the rotating rod of the float. The structure of the float can be as shown in CN201269770Y. When it operates, the movement trajectory of the magnet 3 is an arc shape, and the movement of the magneto-fluid 6 can better match it.

[0021] The external connection parts 7a and 9a of the first electrode plate 9 and the second electrode plate 7 pass through the ceramic substrate 2, and are hermetically connected between the external connection parts 7a, 9a and the ceramic substrate 2. This can better achieve the sealing of the first electrode plate 9, the second electrode plate 7, the resistance plate 8, the plurality of comb-shaped electrode pieces 10, and the magneto-fluid 6.

[0022] On the side of the sealing cover plate 1 facing the ceramic substrate 2, there is a groove 4 in which the magneto-fluid 6 can slide. The setting of the groove 4 restricts the movement of the magneto-fluid 6, enabling it to remain in the groove 4 and move more reliably.

[0023] On the periphery of the side of the ceramic substrate 2 facing the sealing cover plate 1, there is a conductor material of the same material as the first electrode plate 9, the second electrode plate 7, and the plurality of comb-shaped electrode pieces 10. The sealing cover plate 1 is a metal material. The conductor material is printed on the ceramic substrate 2 by SMT process, and the sealing cover plate 1 is reliably hermetically connected to the ceramic substrate 2 through sintering. This structure hermetically welds the sealing cover plate 1 to the ceramic substrate 2, with reliable welding and good sealing, and can be printed on the ceramic substrate 2 simultaneously with the first electrode plate 9, the second electrode plate 7, and the plurality of comb-shaped electrode pieces 10. The resistance sheet is also printed on the ceramic substrate 2 by printing, and overlaps the first electrode plate 9 and the comb-shaped electrode pieces 10, and finally sintered integrally.

[0024] The magnetorheological fluid 6 is a ferromagnetic conductive fluid composed of Fe, Ni, and Co nanoparticles as the main components, an organic solvent as the base liquid, and oleic acid as the surfactant. This solution ensures that the magnetorheological fluid 6 has good ferromagnetic effects and also has good electrical conductivity.

[0025] The magnetorheological fluid is injected through the through-hole. During use, the magnet 3 is linked with the float for detecting the liquid level, so that the magnet 3 moves as the liquid level changes. The external connection parts 7a and 9a on the first electrode plate 9 and the second electrode plate 7 are connected to an external circuit for signal input and output. During operation, the magnet 3 drives the magnetorheological fluid 6 to move. The magnetorheological fluid 6 is a colloidal solution. Under the action of a magnetic field, this liquid neither settles nor aggregates and has the property of being attracted by the magnet 3 itself. The present invention utilizes the fluidity and electrical conductivity of the magnetorheological fluid 6 to connect the resistors and electrodes at different positions, output different resistance values, and correspond the resistance values to the liquid levels one by one, so as to detect the corresponding liquid levels.

[0026] Its beneficial effects are as follows: 1. The first electrode plate 9, the second electrode plate 7, the resistor plate 8, the comb-shaped electrode piece 10, and the magnetorheological fluid 6 of the present invention do not contact the liquid to be detected, so it has good corrosion resistance and can be applied to the oil level detection of various automotive fuels. 2. The magnetorheological fluid 6 is a stable colloid with a simple structure and a long service life. The magnet 3 drives the magnetorheological fluid 6 to move in a rolling manner, without involving wear problems, and its use reliability is very high. 3. Its production cost is low, without the need for precious metal materials or high-precision contact pieces.

[0027] The present invention is not limited to the above embodiments. Based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and deformations to some of the technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of the present invention. For example, the magnet is not limited to being connected to the rotating rod of the float, and the float can also move linearly up and down, so that the magnet moves linearly, and the corresponding comb-shaped electrode piece and the internal connection part are arranged linearly. The sealing cover plate and the ceramic substrate can also be sealed by rubber, soldering, etc.

Claims

1. A magneto-fluidic closed sensor, comprising a ceramic substrate, on one side of which there are provided a first electrode plate, a second electrode plate, a resistance plate and a plurality of comb-shaped electrode pieces. The resistance plate connects the first electrode plate to the plurality of comb-shaped electrode pieces, and external connection parts are respectively provided on the first electrode plate and the second electrode plate for signal input and output. It is characterized in that: An inner connection part is provided on the second electrode plate. The shape of the inner connection part corresponds to that of the comb-shaped electrode piece, and a magnetorheological fluid capable of connecting the two is provided between the inner connection part and the end of the comb-shaped electrode piece. A sealing cover plate is provided on one side of the ceramic substrate provided with the first electrode plate, the second electrode plate, the resistance plate and a plurality of comb-shaped electrode pieces. A through hole for injecting the magnetorheological fluid is provided on the sealing cover plate, and a sealing plug is provided at the position of the through hole. A magnet is provided on the other side of the ceramic substrate corresponding to the position of the magnetorheological fluid.

2. The magnetohydrodynamic sealed sensor according to claim 1, characterized in that: The comb-shaped electrode pieces are distributed in a fan shape, the inner connection part is arranged in an arc shape, and the inner connection part is equidistant from the ends of the respective comb-shaped electrode pieces.

3. A magnetic fluid sealed sensor according to claim 1 or 2, characterized in that: The outer connection parts of the first electrode plate and the second electrode plate penetrate through the ceramic substrate, and the outer connection parts are hermetically connected to the ceramic substrate.

4. A magnetic fluid sealed sensor according to claim 1 or 2, characterized in that: A groove in which the magnetorheological fluid can slide is provided on the side of the sealing cover plate facing the ceramic substrate.

5. A magnetic fluid sealed sensor according to claim 1 or 2, characterized in that: A conductor material of the same material as the first electrode plate, the second electrode plate and the plurality of comb-shaped electrode pieces is provided on the periphery of the side of the ceramic substrate facing the sealing cover plate. The sealing cover plate is made of a metal material, and the conductor material is printed on the ceramic substrate by SMT technology and sintered to connect the sealing cover plate to the ceramic substrate.

6. A magnetohydrodynamic sealed sensor according to claim 1 or 2, characterized in that: The magnetorheological fluid is a ferromagnetic conductive fluid mixed with Fe, Ni, Co nanoparticles as the main components, an organic solvent as the base liquid, and oleic acid as the surfactant.

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