CN112325978B - Resistance type liquid level detection system - Google Patents

Resistance type liquid level detection system Download PDF

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Publication number
CN112325978B
CN112325978B CN202011173103.XA CN202011173103A CN112325978B CN 112325978 B CN112325978 B CN 112325978B CN 202011173103 A CN202011173103 A CN 202011173103A CN 112325978 B CN112325978 B CN 112325978B
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China
Prior art keywords
liquid level
resistor strip
negative electrode
pipe body
strip
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CN202011173103.XA
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CN112325978A (en
Inventor
李�浩
梁波
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Suzhou Beikang Intelligent Manufacturing Co ltd
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Suzhou Beikang Intelligent Manufacturing Co ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/30Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by floats

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Level Indicators Using A Float (AREA)

Abstract

The invention relates to the technical field of liquid level detection and discloses a resistance type liquid level detection system. The liquid level sensor is fixed in a container for containing liquid to be measured, and a positive electrode resistance strip and a negative electrode resistance strip are fixed in a tube body with an opening at one end, and are arranged in parallel at intervals. The slip ring is arranged in the pipe body and comprises two rollers which are respectively arranged at the outer sides of the positive and negative electrode resistor bars, and the two resistor bars are contacted under the extrusion action of the two rollers. The annular floater is sleeved outside the pipe body, slides along the pipe body under the action of buoyancy and drives the roller to slide up and down along the positive and negative electrode resistance strips, and the position of a contact point between the positive and negative electrode resistance strips is changed, so that the resistance value of an internal loop of the liquid level sensor is changed. The current signal output module outputs a corresponding current value according to the resistance value of the liquid level sensor, and the processing module analyzes and processes the current value to obtain a liquid level value, so that the liquid level condition of the liquid to be detected is monitored in real time.

Description

Resistance type liquid level detection system
Technical Field
The invention relates to the technical field of liquid level detection, in particular to a resistance type liquid level detection system.
Background
Currently, sensors available for measuring the liquid level of cryogenic liquids below-150 ℃ are of a few types, and devices which are relatively commonly used in the process of detecting the liquid level of the cryogenic liquids are differential pressure type liquid level sensors and capacitive liquid level sensors. The differential pressure type liquid level sensor detects the height of the liquid level by utilizing the pressure generated by the liquid column, and after the liquid level changes, the pressure difference measured by the differential pressure transmitter also changes, and a linear relation exists between the differential pressure type liquid level sensor and the liquid level sensor. The capacitive liquid level sensor is characterized in that the capacitive liquid level sensor is inserted into a measured medium, the depth of an electrode immersed in the medium changes along with the height of a material level, the medium between the electrodes rises and falls, and the capacitance between two polar plates is necessarily changed, so that the liquid level change can be detected. However, the differential pressure type liquid level sensor has the advantages of complex sampling system, long connecting pipeline, more valves and easy blockage or leakage; one sampling tube needs to be directly led out from the bottom of the container, so that the cold conduction is serious; the time for establishing the stable differential pressure condition under the working conditions of fluid infusion and evacuation is longer, and the recovery time is longer. The capacitance type liquid level meter mainly relies on the capacitance change between two electrodes, so that fog can influence the detection accuracy and is easy to influence the measurement result by surrounding electromagnetic interference.
Disclosure of Invention
Based on this, it is necessary to provide a resistive liquid level detection system for the problem of the lack of a sensor capable of measuring the liquid level of a cryogenic liquid for a long time.
A resistance type liquid level detection system container, which is used for containing liquid to be detected; a liquid level sensor partially located within the container; the liquid level sensor comprises a pipe body with an opening at one end; the positive electrode resistor strip is fixed in the pipe body, and the extending direction of the positive electrode resistor strip is the same as the extending direction of the pipe body; the negative electrode resistor strip is fixed in the pipe body and is parallel to the positive electrode resistor strip; the annular floater is sleeved on the outer surface of the pipe body and can slide along the pipe body under the action of buoyancy force; the slip ring is arranged in the pipe body; the slip ring comprises two rollers which are respectively positioned at the outer sides of the positive electrode resistor strip and the negative electrode resistor strip and roll along the extending direction of the positive electrode resistor strip and the negative electrode resistor strip under the drive of the annular floater, so that the parts of the positive electrode resistor strip and the negative electrode resistor strip positioned between the two rollers are in contact to adjust the resistance of the liquid level sensor; the power supply module is respectively connected with the positive electrode resistor strip and the negative electrode resistor strip and is used for providing voltage for the positive electrode resistor strip and the negative electrode resistor strip; the current signal output module is connected with the liquid level sensor and is used for outputting a corresponding current value according to the change of the resistance value of the liquid level sensor; and the processing module is connected with the current signal output module and is used for processing the current value output by the current signal output module to obtain the liquid level value of the liquid to be detected.
According to the resistance type liquid level detection system, the liquid level sensor is arranged in the container to detect the liquid level of the liquid to be detected in real time. The liquid level sensor is characterized in that an anode resistor strip and a cathode resistor strip are fixed in a tube body with an opening at one end of the liquid level sensor, and the anode resistor strip and the cathode resistor strip are arranged in parallel and at intervals. The outer periphery of the pipe body is sleeved with an annular floater, and the annular floater slides along the pipe body under the action of buoyancy. The tube body is internally provided with a sliding ring, the sliding ring comprises two rollers, the two rollers are respectively positioned at the outer sides of the positive electrode resistor strip and the negative electrode resistor strip, and the two rollers are respectively extruded inwards from the outer sides of the positive electrode resistor strip and the negative electrode resistor strip at the same time, so that the parts of the positive electrode resistor strip and the negative electrode resistor strip positioned between the rollers are in contact. Simultaneously, the slip ring rolls along the extending direction of the positive electrode resistor strip and the negative electrode resistor strip under the drive of the annular floater, so that the position of a contact point between the positive electrode resistor strip and the negative electrode resistor strip is changed. After one ends of the positive electrode resistor strip and the negative electrode resistor strip are connected with voltage, the positive electrode resistor strip and the negative electrode resistor strip are contacted with each other under the extrusion action of the roller to form a loop, and the resistance value on the loop is related to the positions of the slip ring and the contact points of the positive electrode resistor strip and the negative electrode resistor strip. After one ends of the positive electrode resistor strip and the negative electrode resistor strip are connected into the power supply module, a loop is formed by connecting the positive electrode resistor strip and the negative electrode resistor strip with the slip ring, and the resistance value on the loop is related to the position of the contact point of the slip ring and the positive electrode resistor strip and the position of the contact point of the negative electrode resistor strip. The current signal output module outputs a corresponding current value according to the change condition of the resistance value in the liquid level sensor, and the processing module carries out real-time processing on the current value, so that the liquid level condition of the liquid level to be detected can be monitored in real time and the liquid level value of the liquid to be detected can be obtained. Because no electronic element exists in the liquid level sensor body, the magnetic component cannot demagnetize at low temperature, and therefore, the resistance type liquid level detection system can be used for accurately measuring the liquid level of the cryogenic liquid for a long time.
In one embodiment, the annular float comprises an annular float housing, which is sleeved outside the tube body, and the annular float housing is provided with a cavity; and the annular magnet is arranged in the cavity of the annular float shell.
In one embodiment, the slip ring further comprises a slip ring main body, wherein the slip ring main body is positioned in the pipe body and is in contact with the inside of the pipe body, and a soft magnetic metal ring is embedded in the slip ring main body; the sliding sleeves are respectively arranged on the opposite side walls of the sliding ring main body, and accommodating cavities are arranged in the sliding sleeves; the elastic devices are respectively positioned in the accommodating cavities of the two sliding sleeves; and the two sliding rods are fixedly connected with one end of the elastic device extending out of the accommodating cavity.
In one embodiment, a sliding groove is formed in the inner wall of the pipe body, the sliding groove extends along the length direction of the pipe body, a first protruding structure is further arranged on the outer side of the slip ring main body, and the first protruding structure is embedded into the sliding groove.
In one embodiment, the slip ring further comprises two non-conductive nonmetal cover plates, the two nonmetal cover plates are respectively fixed at two ports of the slip ring main body, two resistor strip through holes are respectively arranged on the two nonmetal cover plates, and the two resistor strip through holes are arranged at intervals; the positive electrode resistor strip and the negative electrode resistor strip respectively pass through two resistor strip through holes on the two nonmetallic cover plates.
In one embodiment, the liquid level sensor further comprises a cover body covering the opening to form a sealed cavity in the tube body; the positive electrode resistor strip, the negative electrode resistor strip and the slip ring are all positioned in the sealing cavity; one end of the positive terminal penetrates through the cover body and is connected with the positive resistor strip through a flexible wire, and the other end of the positive terminal extends to the upper part of the cover body; and one end of the negative terminal penetrates through the cover body and is connected with the negative resistor strip through a flexible wire, and the other end of the negative terminal extends to the upper part of the cover body.
In one embodiment, the liquid level sensor further comprises a non-conductive nonmetallic floating ring, wherein the non-conductive nonmetallic floating ring is positioned in the pipe body and above the positive resistance strip and the negative resistance strip; one end of each tension spring is connected with the cover body, and the other end of each tension spring is connected with the nonmetal floating ring; the non-conductive nonmetal plate is positioned in the pipe body, is positioned below the positive electrode resistor strip and the negative electrode resistor strip, and forms an accommodating space at the bottom of the pipe body; the uniform ends of the positive electrode resistor strips and the negative electrode resistor strips are connected with the nonmetal plate, and the other ends of the positive electrode resistor strips and the negative electrode resistor strips are connected with the nonmetal floating ring; the balancing weight is positioned in the accommodating space; and the limiting ring is positioned at the periphery of the pipe body and below the positive electrode resistor strip and the negative electrode resistor strip.
In one embodiment, the nonmetallic floating ring and the nonmetallic plate are both provided with nonmetallic wedge blocks which are nonconductive, and when the sliding ring slides to the nonmetallic floating ring or the nonmetallic plate, the nonmetallic wedge blocks block the positive electrode resistor strip and the negative electrode resistor strip from contacting from the middle of the positive electrode resistor strip and the negative electrode resistor strip.
In one embodiment, the slip ring further comprises two non-conductive nonmetallic cover plates respectively fixed at two ports of the slip ring main body; a nonmetallic wedge-shaped block via hole is arranged at the center of each nonmetallic cover plate; the nonmetallic floating ring and the nonmetallic wedge blocks on the nonmetallic plates respectively pass through nonmetallic wedge block through holes on the nonmetallic cover plates.
In one embodiment, a sliding groove is formed in the inner wall of the pipe body, and the sliding groove extends along the length direction of the pipe body; the outer side of the nonmetallic floating ring is also provided with a second protruding structure, and the second protruding structure is embedded into the chute.
Drawings
FIG. 1 is a schematic diagram of a resistive liquid level detection system according to an embodiment of the present invention;
FIG. 2 is a front cross-sectional view of a fluid level sensor according to one embodiment of the present invention;
FIG. 3 is a cross-sectional view of the structure of an annular float according to one embodiment of the invention;
FIG. 4 is a cross-sectional view of a slip ring according to one embodiment of the present invention;
FIG. 5 is a schematic top view of a slip ring according to one embodiment of the present invention;
FIG. 6 is a front cross-sectional view of a fluid level sensor according to another embodiment of the present invention;
FIG. 7 is a schematic view of an annular float in a lower limit position according to one embodiment of the present invention;
FIG. 8 is an enlarged schematic view of a nonmetallic wedge block in accordance with one embodiment of the present invention;
FIG. 9 is a schematic diagram of a power module according to an embodiment of the invention;
fig. 10 is a signal processing flow chart of a processing module according to an embodiment of the invention.
Detailed Description
In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. The drawings illustrate preferred embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. 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. The terms "vertical," "horizontal," "left," "right," "upper," "lower," "front," "rear," "circumferential," and the like as used herein are based on the orientation or positional relationship shown in the drawings and are merely for convenience of description and to simplify the description, rather than to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
Fig. 1 is a schematic structural diagram of a resistive liquid level detection system according to an embodiment of the present invention, in one embodiment, the resistive liquid level detection system provided by the present invention includes a liquid level sensor 10, a container 20, a power supply module 30, a current signal output module 40, and a processing module 50. The liquid level sensor 10 is partially located in the container 20, and the container 20 is used for containing liquid to be measured. In this embodiment, the liquid to be measured is a cryogenic liquid. When the cryogenic liquid is injected into the container 20, the annular float 104 with a certain buoyancy on the liquid level sensor 10 slides on the pipe body 101 along with the change of the liquid level, and drives the slip ring 105 in the pipe body 101 to slide on the positive and negative electrode resistance bars, so that the resistance value of the internal loop of the liquid level sensor 10 changes along with the change of the liquid level in the container 20.
The positive output end of the power supply module 30 is connected with the positive resistor strip 102, and the negative output end is connected with the negative resistor strip 103. The power supply module 30 is configured to provide a voltage to the liquid level sensor 10. The current signal output module 40 is connected to the liquid level sensor 10. When the resistance value of the liquid level sensor 10 changes with the change of the liquid level, since the voltage value applied to the liquid level sensor 10 is fixed, the current value outputted by the current signal output module 40 also changes, and the current value outputted by the current signal output module 40 corresponds to the resistance value of the liquid level sensor 10. The processing module 50 is connected to the current signal output module 40, and the processing module 50 receives the current value output by the current signal output module 40 and performs analysis and processing on the current value in real time to obtain a liquid level value of the cryogenic liquid in the container 20.
Fig. 2 is a front cross-sectional view of a liquid level sensor according to one embodiment of the present invention, wherein the liquid level sensor comprises a tube 101, a positive resistive strip 102, a negative resistive strip 103, an annular float 104, and a slip ring 105, and wherein the slip ring 105 comprises two rollers 106. The tube body 101 of the liquid level sensor 10 is a long tube structure with one end open and a hollow inside. The positive electrode resistor strip 102 and the negative electrode resistor strip 103 are both arranged in the pipe body 101, a certain distance is reserved between the positive electrode resistor strip 102 and the negative electrode resistor strip 103, the positive electrode resistor strip 102 and the negative electrode resistor strip 103 are arranged in parallel, and the positive electrode resistor strip 102 and the negative electrode resistor strip 103 are not contacted with each other. The extending direction of the positive electrode resistor bar 102 is the same as the extending direction of the tube body 101, that is, the positive electrode resistor bar 102 and the negative electrode resistor bar 103 are parallel to the tube wall of the tube body 101.
An annular float 104 with buoyancy is sleeved outside the pipe body 101. The outer wall of the pipe body 101 is smooth and unobstructed, and the annular float 104 can slide smoothly between the two end points a-b on the pipe body 101, please refer to fig. 2, where the two end points a and b are located at the upper and lower ends of the pipe body 101 respectively. The annular floater 104 always floats on the surface of the liquid to be detected under the action of the buoyancy, and when the liquid level of the liquid to be detected changes, the annular floater 104 slides up and down on the outer side of the pipe body 101 along with the change of the liquid level.
The slip ring 105 is disposed inside the pipe body 101, and when the annular floater 104 slides, the slip ring 105 inside the pipe body 101 is driven to slide along with the pipe body, that is, the slip ring 105 can also slide smoothly between the two end points a-b inside the pipe body 101. The slip ring 105 includes two rollers 106, and the two rollers 106 are respectively disposed on the outer sides of the positive electrode resistance bar 102 and the negative electrode resistance bar 103. The two rollers 106 move in the extending direction of the positive electrode resistance bar 102 and the negative electrode resistance bar 103 along with the movement of the ring-shaped float 104. The two rollers 106 are always pressed towards the middle of the positive and negative electrode resistance bars respectively at the outer sides of the positive electrode resistance bar 102 and the negative electrode resistance bar 103, so that the positive electrode resistance bar 102 and the negative electrode resistance bar 103 are in contact at the pressing position of the rollers 106.
The ends of the positive electrode resistor strip 102 and the negative electrode resistor strip 103, which are close to the opening of the pipe body 101, are used for being connected with an external power supply, and after the positive electrode resistor strip 102 and the negative electrode resistor strip 103 are connected with the external power supply, an electric signal flows from the end of the positive electrode resistor strip 102, which is close to the opening of the pipe body 101, to the contact point with the negative electrode resistor strip 103, and then is transmitted from the contact point of the positive electrode resistor strip 102 and the negative electrode resistor strip 103 to the end of the negative electrode resistor strip 103, which is close to the opening of the pipe body 101, so that a closed loop is formed. Since the resistance value is related to the length of the resistive material, and when other determinants are unchanged, the resistance value inside the level sensor 10 is only related to the length of the positive and negative resistor strip in the access loop, the resistance value inside the level sensor 10 is determined by the position of the positive and negative resistor strip contact point. When the annular floater 104 drives the slip ring 105 to slide in the pipe body 101 along with the change of the liquid level, the two rollers 106 roll on the positive and negative resistance bars, and the contact point of the positive and negative resistance bars is changed, so that the length of the positive and negative resistance bars connected into the loop is changed, namely the resistance value in the internal loop of the liquid level sensor 10 is changed. Therefore, the resistance value inside the liquid level sensor 10 changes along with the change of the liquid level, and the liquid level of the liquid to be detected can be detected in real time by detecting and analyzing the change of the resistance value of the liquid level sensor 10. Since the body of the liquid level sensor 10 has no electronic component, the magnetic component is not demagnetized at low temperature, and thus the liquid level sensor 10 can be applied to accurately measure the liquid level of cryogenic liquid for a long time.
In one embodiment, the materials of the positive electrode resistor strip 102 and the negative electrode resistor strip 103 are high-resistance alloy materials which can still maintain stable resistance in a cryogenic environment, and have small contact resistance, high chemical stability and good wear resistance. The high resistance alloy material includes, but is not limited to, platinum-based alloys, gold-based alloys, silver-based alloys, palladium-based alloys. In the preparation of the level sensor 10, the positive electrode resistor strip 102 and the negative electrode resistor strip 103 are selected, for example, resistor strips made of platinum rhodium, platinum iridium, platinum copper, gold silver copper, jin Nietong, jin Nie chromium, jin Batie aluminum, silver manganese tin, palladium silver copper, palladium molybdenum, and the like are selected. The material has small contact resistance, high chemical stability and good wear resistance, so that the material can still maintain stable performance for a long time in a cryogenic environment, and the liquid level sensor 10 is ensured not to be damaged due to the cryogenic environment. Therefore, the liquid level sensor 10 can be applied to liquid level detection of cryogenic liquid, can still perform long-time real-time detection in a cryogenic environment, and can realize high-precision detection.
Fig. 3 is a cross-sectional view of the ring-shaped float 104, taken from a cross-sectional view and enlarged, of one embodiment of the present invention, wherein the ring-shaped float 104 includes a ring-shaped float housing 107 and a ring-shaped magnet 108. The annular float housing 107 is sleeved on the periphery of the pipe body 101, and a cavity is formed in the annular float housing 107. The annular float 104 is provided with a cavity, so that the annular float 104 has certain buoyancy, floats on the liquid surface of the liquid to be detected under the action of the buoyancy, and slides on the outer pipe wall of the pipe body 101 along with the change of the liquid surface. A ring magnet 108 is disposed in the cavity of the ring float housing 107, the ring magnet 108 being located within the cavity and extending to the outer surface of the tube 101. The ring magnet 108 has attractive force to the magnetic material, so when the slip ring 105 has the magnetic material, the ring magnet 108 can generate attractive force to the magnetic material in the slip ring 105, thereby driving the slip ring 105 to roll along the extending direction of the positive electrode resistor strip and the negative electrode resistor strip when the ring float 104 slides, and changing the position of the roller 106 for exerting extrusion acting force on the positive electrode resistor strip and the negative electrode resistor strip so as to change the resistance value on a loop formed by the positive electrode resistor strip and the negative electrode resistor strip.
In one embodiment, the ring-shaped float 104 further includes a magnetic ring gland 109, where the magnetic ring gland 109 covers the cavity of the ring-shaped float housing 107, so that a closed cavity is formed in the ring-shaped float housing 107, so that the ring-shaped strong magnet is fixed in the cavity of the ring-shaped float 104, and is prevented from leaking or changing in position under the action of external force, and the measurement of the liquid level sensor 10 is affected.
Fig. 4 is a cross-sectional view of the slip ring 105, which is an enlarged cross-sectional view of the structure of one embodiment of the present invention, wherein the slip ring 105 includes a slip ring body 110 disposed in the pipe body 101 and contacting the inside of the pipe body 101. The slip ring body 110 has a soft magnetic metal ring 111 embedded therein. Since the soft magnetic metal ring 111 is embedded in the slip ring body 110, the slip ring 105 can be attracted by the ring magnet 108, and the slip ring 105 moves with the movement of the ring float 104 under the action of magnetic force. Because the soft magnetic metal ring 111 made of soft magnetic material is embedded in the slip ring main body 110, most of the magnetic field can be shielded by the slip ring main body 110 to prevent the positive and negative resistance strips in the pipe body 101 from being magnetized after long-term use, thereby prolonging the service life of the device of the liquid level sensor 10 and ensuring the accuracy of the liquid level measurement to be measured.
The slip ring 105 further comprises two sliding sleeves 112, an elastic means 113 and two sliding bars 114. The two sliding sleeves 112 are respectively fixed on opposite side walls inside the slip ring main body 110, the two sliding sleeves 112 are oppositely arranged, a certain accommodating cavity is formed in each sliding sleeve 112, and the two elastic devices 113 are respectively positioned in the two accommodating cavities. The two sliding rods 114 are fixedly connected with one ends of the elastic devices 113 extending out of the accommodating cavity. The elastic device 113 may be sleeved on the sliding rod 114 or disposed at one end of the sliding rod 114. In this embodiment, the elastic device 113 is a spring, and the spring is always in a compressed state. The spring in the compressed state is used for providing elastic force for the two rollers 106, so that the two rollers 106 continuously squeeze from the outer sides of the positive and negative electrode resistor strips to the inner sides, the two resistor strips are contacted at the squeezing positions of the rollers 106, and the conductive stability is improved. The two rollers 106 are respectively and fixedly connected to opposite side walls inside the slip ring main body 110 through the sliding rods 114, and the positive electrode resistor strip 102 and the negative electrode resistor strip 103 are positioned between the two rollers 106. The elastic component in the slip ring 105, which is composed of the roller 106, the elastic device 113 and the sliding rod 114, ensures that the positive and negative electrode resistor bars can be extruded to make the two resistor bars contact, and simultaneously has certain flexibility, and the two rollers 106 can roll along the outer sides of the positive and negative electrode resistor bars.
Fig. 5 is a schematic top view of a slip ring according to an embodiment of the present invention, in which the slip ring 105 further includes two non-metal cover plates 117 made of non-conductive non-metal materials, and each of the two non-metal cover plates 117 is fixed to two ports of the slip ring main body 110, and two resistor strip vias 118 are respectively disposed on each of the two non-metal cover plates 117. The two resistor bar through holes 118 are spaced apart by a certain distance, and the distance between the two resistor bar through holes 118 is the same as the distance between the positive resistor bar 102 and the negative resistor bar 103. The positive electrode resistor bar 102 and the negative electrode resistor bar 103 respectively pass through two resistor bar through holes 118 on two nonmetal cover plates 117. Since the two resistor bar through holes 118 on the nonmetal cover 117 are spaced apart, and the positive resistor bar 102 and the negative resistor bar 103 respectively pass through two different through holes, the two resistor bar through holes 118 can space the positive resistor bar and the negative resistor bar at a set position, so that the positive resistor bar and the negative resistor bar are prevented from contacting at a part except the extrusion point of the roller 106 to the two resistor bars.
Fig. 6 is a front cross-sectional view of a liquid level sensor according to another embodiment of the present invention, wherein in one embodiment, a chute 115 is provided on the inner wall of the tube body, and the chute 115 extends along the length direction of the tube body 101, from the nozzle to the bottom of the tube body. Referring to fig. 5, a first protrusion structure 116 is further disposed on the outer side of the slip ring main body 110, and the first protrusion structure 116 is embedded in the chute 115. The first protruding structure 116 has a shape and a size matching the slot size of the chute 115, and the first protruding structure 116 can be just embedded in the chute 115 and can slide freely in the chute 115 along the track defined by the chute 115. The first protrusion structure 116 may be used to prevent the soft magnetic outer ring from rotating when sliding inside the tube 101, thereby affecting the level measurement accuracy of the level sensor 10.
In one embodiment, the fluid level sensor 10 further includes a cover 119, a positive terminal 120, and a negative terminal 121. The cover 119 is made of non-conductive non-metal material and covers the opening of the pipe body 101, and the cover 119 is connected with the pipe orifice of the pipe body 101 in a sealing manner, so that the inside of the pipe body 101 is sealed to form a sealing cavity in the pipe body 101. The positive electrode resistor bar 102, the negative electrode resistor bar 103 and the slip ring 105 are all located in the sealed cavity. One end of the positive terminal 120 penetrates through the cover 119 and is connected with the positive resistor strip 102 via a flexible wire, and the other end of the positive terminal 120 extends above the cover 119 for accessing an external circuit. One end of the negative terminal 121 penetrates through the cover 119 and is connected with the negative resistor strip 103 via a flexible wire, and the other end of the negative terminal 121 extends above the cover 119 for accessing an external circuit.
When the liquid level sensor 10 is used for measuring the liquid level of the liquid to be measured, an operating power supply needs to be input to the liquid level sensor 10. The positive electrode terminal 120 is connected with a positive electrode output end of an external power supply, the negative electrode terminal 121 is connected with a negative electrode output end of the external power supply, the external power supply is connected through a positive electrode terminal and a negative electrode terminal, working voltage is transmitted to the positive electrode resistance strip and the negative electrode resistance strip through flexible wires, and the positive electrode resistance strip and the negative electrode resistance strip are contacted with each other in the pipe body 101 to form a closed loop. Because the resistance value of the resistor is related to the length of the resistor material, when the liquid level of the liquid to be measured changes, the contact positions of the positive and negative resistor strips which are mutually contacted under the extrusion action of the roller 106 also change, and the length of the positive and negative resistor strips which are connected into the closed loop changes, so that the resistance value of the liquid level sensor 10 changes along with the change of the liquid level, and the liquid level information of the liquid to be measured can be obtained by analyzing and processing the resistance value of the change of the liquid level sensor 10.
In one embodiment, as shown in fig. 6, the liquid level sensor 10 further includes a nonmetallic floating ring 122, a plurality of tension springs 123, a nonmetallic plate 124, a counterweight 125, and a stop collar 126. The non-metallic floating ring 122 and the non-metallic plate 124 are each made of a non-conductive non-metallic material. The nonmetallic floating ring 122 is located in the sealed cavity of the pipe body 101, and is located above the positive electrode resistor strip 102 and the negative electrode resistor strip 103, and is near the opening of the pipe body 101. One end of each of the plurality of tension springs 123 is connected with the cover body 119, and the other end of each of the plurality of tension springs 123 is connected with the nonmetallic floating ring 122, namely the cover body 119 is connected with the nonmetallic floating ring 122 through the plurality of tension springs 123. The nonmetallic floating ring 122 can slide smoothly inside the pipe body 101 under the elastic force of the tension spring 123. In this embodiment, the number of the tension springs 123 is 2 or more.
The nonmetallic plates 124 are disposed inside the pipe body 101 and below the positive electrode resistive strip 102 and the negative electrode resistive strip 103. The non-metal plate 124 is fixed to the bottom of the pipe body 101, and forms an accommodating space at the bottom of the pipe body 101. The positive electrode resistor bar 102 and the negative electrode resistor bar 103 are connected at one end to the nonmetallic plate 124, and connected at the other end to the nonmetallic floating ring 122. The balancing weight 125 is arranged in the accommodating space, the balancing weight 125 is placed in the accommodating space to accommodate the balancing weight 125, and the position of the balancing weight 125 can be prevented from being displaced in the process of installing, moving and the like of the liquid level sensor 10, so that the liquid level sensor 10 is prevented from affecting other structures and functions in the pipe. The balancing weight 125 is disposed at the bottom of the pipe 101 and can be used to make the bottom of the liquid level sensor 10 sink into the measured liquid, and make the bottom of the liquid level sensor 10 always keep vertical in the measured liquid in a manner of bottom sinking during the liquid level measurement process.
The positive electrode resistor bar 102 and the negative electrode resistor bar 103 are both fixed on the nonmetallic floating ring 122 at one end, and are both fixed on the nonmetallic plate 124 at the other end. Since the nonmetallic floating ring 122 is fixed on the cover 119 by the tension spring 123, the positions of the cover 119 and the nonmetallic plate 124 are fixed, and the tension spring 123 has an elastic force, and after the tension spring 123 is connected with the nonmetallic floating ring 122, the tension spring 123 can exert a tensile force on the nonmetallic floating ring 122. The non-metal floating ring 122 may freely slide inside the pipe body 101, so that the non-metal floating ring 122 may drive one end of the positive and negative electrode resistor strip connected thereto to tighten in the direction of the cover 119 under the action of the tension spring 123. And because the other end of the positive and negative resistance bar is fixed on the nonmetal plate 124 at the bottom of the tube body 101, the positive and negative resistance bar is always subjected to a tensile force, so that the positive and negative resistance bar is always kept in a tensioning state. The positive and negative electrode resistor bars are always kept in a tensioning state, so that the contact between the positive and negative electrode resistor bars is always kept to be highly reliable, poor contact between the positive and negative electrode resistor bars is prevented, and the stability of a connecting passage between the positive and negative electrode resistor bars is affected.
Fig. 7 is a schematic structural diagram of an annular float in a lower limit position according to an embodiment of the present invention, a limiting ring 126 is further disposed on the periphery of the tube 101, and the limiting ring 126 is disposed at the bottom of the tube 101 and below the positive resistance strip 102 and the negative resistance strip 103, so as to block the annular float 104 from falling out of the bottom of the tube 101. When the liquid level sensor 10 moves to the bottom of the pipe body 101, the motion of continuing to move downwards is limited by the limiting ring 126, so that the annular float 104 is prevented from falling off from the bottom, normal use of the liquid level sensor 10 is ensured, the step of sleeving the annular float 105 on the pipe body 101 is not required to be additionally added by a user due to falling off, the use convenience of the liquid level sensor 10 is improved, and the use feeling of the user is improved.
Fig. 8 is an enlarged schematic view of a nonmetallic wedge block according to an embodiment of the present invention, in one embodiment, nonmetallic wedge blocks 127 are disposed on the nonmetallic floating ring 122 and nonmetallic plate 124, and the nonmetallic wedge blocks 127 are made of nonconductive nonmetallic materials. Shown in fig. 7 is the non-metallic wedge block 127 secured to the non-metallic plate 124. When the slip ring 105 slides to the position of the nonmetallic floating ring 122 or the nonmetallic plate 124, the nonmetallic wedge block 127 blocks the positive electrode resistance strip 102 and the negative electrode resistance strip 103 from contacting from the middle of the positive electrode resistance strip 102 and the negative electrode resistance strip 103. The nonmetallic floating ring 122 is located at the upper limit position of the annular float 104 and the slip ring 105, and the nonmetallic plate 124 is located at the lower limit position of the annular float 104 and the slip ring 105. When the ring-shaped floater 104 and the slip ring 105 move to the upper and lower limit, the nonmetal wedge block 127 is blocked between the positive electrode resistance bar 102 and the negative electrode resistance bar 103, separates the positive electrode resistance bar from the negative electrode resistance bar to prevent the positive electrode resistance bar from contacting, cuts off a loop between the positive electrode resistance bar 102 and the negative electrode resistance bar 103, and is used for indicating that the liquid level to be measured reaches the detection limit of the liquid level sensor 10.
In one embodiment, as shown in fig. 5, the slip ring 105 further includes two nonmetallic cover plates 117 made of nonconductive nonmetallic materials, and respectively fixed at two ports of the slip ring main body 110, and a nonmetallic wedge-shaped block via hole 128 is disposed at the center of the two nonmetallic cover plates 117. When the annular float 104 and the slip ring 105 move to the upper and lower limit positions, that is, when the annular float 104 and the slip ring 105 move to the vicinity of the position of the nonmetallic floating ring 122 or the nonmetallic plate 124, the nonmetallic wedge 127 on the nonmetallic floating ring 122 or the nonmetallic plate 124 passes through the nonmetallic wedge via 128 and is blocked between the positive electrode resistance bar 102 and the negative electrode resistance bar 103, and the two resistance bars are separated to prevent the positive electrode resistance bar and the negative electrode resistance bar from contacting.
In one embodiment, referring to fig. 6, a chute 115 is provided on the inner wall of the tube 101, and the chute 115 extends along the length direction of the tube 101 from the nozzle to the bottom of the tube. A second protruding structure (not shown) is further provided on the outer side of the nonmetallic floating ring 122, and the second protruding structure is embedded in the chute. The second protrusion is shaped and sized to match the slot size of the chute 115, and is capable of being snugly embedded within the chute 115 while being free to slide in the track defined by the chute 115. The second protrusion structure is disposed on the outer side of the non-metal floating ring 122, and is used for limiting the moving track of the non-metal floating ring 122, so as to prevent the non-metal floating ring 122 from rotating in the horizontal direction, thereby affecting the liquid level measurement of the liquid level sensor 10.
In one embodiment, the sealed cavity is filled with an inert gas. The inside of the sealed cavity formed by the airtight connection of the tube body 101 and the cover 119 is filled with an inert gas. The inert gas may be used to ensure that the physical characteristics of the metal components within the tube 101 remain stable for a long period of time, so as to ensure that the liquid level sensor 10 is capable of performing long-term measurements on cryogenic liquids, while ensuring measurement accuracy under long-term measurements. The inert gas includes, but is not limited to, helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the like.
In one embodiment, when the liquid level sensor 10 is installed in the container 20, the cover 119 at the top of the liquid level sensor 10 may be fixed to a top plate inside the container 20, so as to prevent the liquid level sensor 10 from rotating due to vortex caused by liquid injection when the liquid level sensor 10 injects the liquid to be measured into the container 20, thereby affecting the detection accuracy of the liquid level detection.
After the level sensor 10 is fixed to the top of the container 20, a part of the body of the level sensor 10 is inserted into the container 20. The output end of the power supply module 30 is connected to the positive electrode terminal 120 and the negative electrode terminal 121, respectively, so that the positive and negative electrode resistance bars contacting each other inside the tube body 101 form a closed loop. When the liquid to be measured is injected into the container 20, the annular float 104 outside the pipe body 101 floats on the liquid surface of the liquid to be measured, and the annular float 104 is driven to correspondingly rise and fall by the rise and fall of the liquid surface. Simultaneously, the annular floater 104 drives the slip ring 105 to slide together under the action of magnetic force, so that the two rollers 106 slide on the positive and negative resistance bars, the length of the positive and negative resistance bars connected into a loop is changed, and the resistance value in the loop is correspondingly changed. The current signal output module 40 outputs a current value corresponding to the resistance value according to a change in the internal resistance value of the liquid level sensor 10. The processing module 50 calculates the current value to obtain a level value of the liquid to be measured in the container 20.
Fig. 9 is a schematic structural diagram of a power supply module according to an embodiment of the present invention, in which the power supply module 30 includes a power supply module 310 and a voltage stabilizing module 320. The power module 310 is used to provide the voltage required for the operation of the level sensor 10. The input end of the voltage stabilizing module 320 is connected with the output end of the power module 310; the positive output end of the voltage stabilizing module 320 is connected with the positive terminal 120, and the negative output end of the voltage stabilizing module 320 is connected with the negative terminal 121, so that the positive and negative resistor strips contacting with the inside of the tube 101 form a closed loop. The voltage stabilizing module 320 is configured to stabilize the voltage provided by the power module 310 and provide the voltage to the positive electrode resistor strip 102 and the negative electrode resistor strip 103, so as to ensure the stability of the output of the liquid level sensor 10 during the liquid level detection.
Fig. 10 is a signal processing flow chart of a processing module according to an embodiment of the present invention, in which the processing module 50 performs a signal processing process through the following functional units when processing the current signal output by the current signal output module 40. After the liquid level sensor 10 outputs the changed current value to the processing module 50 through the current signal output module 40, the primary filtering unit in the processing module 50 performs the first filtering on the current value to eliminate the larger interference signal in the current value. And amplifying the current value after the first filtering by a signal amplifying unit to realize signal enhancement. And then, carrying out secondary filtering on the enhanced current value through a secondary filtering unit, further eliminating interference signals and improving the stability of output signals. And performing data conversion on the current value subjected to the second filtering through an I-V conversion module, and converting the changed current value into a changed voltage value. The converted voltage value is converted into a digital voltage value through an ADC conversion circuit, and is sent into a microprocessor, and the digital voltage value is calculated, analyzed and processed by the microprocessor to obtain a liquid level value.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. A resistive liquid level detection system, comprising:
a container for holding a liquid to be measured;
a liquid level sensor partially located within the container; the liquid level sensor comprises a pipe body with an opening at one end; the positive electrode resistor strip is fixed in the pipe body, and the extending direction of the positive electrode resistor strip is the same as the extending direction of the pipe body; the negative electrode resistor strip is fixed in the pipe body and is parallel to the positive electrode resistor strip; the annular floater is sleeved on the outer surface of the pipe body and can slide along the pipe body under the action of buoyancy force; the slip ring is arranged in the pipe body; the slip ring comprises two rollers which are respectively positioned at the outer sides of the positive electrode resistor strip and the negative electrode resistor strip and roll along the extending direction of the positive electrode resistor strip and the negative electrode resistor strip under the drive of the annular floater, so that the parts of the positive electrode resistor strip and the negative electrode resistor strip positioned between the two rollers are in contact to adjust the resistance of the liquid level sensor;
the power supply module is respectively connected with the positive electrode resistor strip and the negative electrode resistor strip and is used for providing voltage for the positive electrode resistor strip and the negative electrode resistor strip;
the current signal output module is connected with the liquid level sensor and is used for outputting a corresponding current value according to the change of the resistance value of the liquid level sensor;
the processing module is connected with the current signal output module and is used for processing the current value output by the current signal output module to obtain the liquid level value of the liquid to be detected;
the liquid level sensor further includes:
the cover body covers the opening to form a sealed cavity in the pipe body; the positive electrode resistor strip, the negative electrode resistor strip and the slip ring are all positioned in the sealing cavity;
a non-conductive nonmetallic floating ring which is positioned in the pipe body and above the positive electrode resistance strip and the negative electrode resistance strip;
one end of each tension spring is connected with the cover body, and the other end of each tension spring is connected with the nonmetal floating ring.
2. The resistive liquid level detection system of claim 1 wherein the annular float comprises:
the annular float shell is sleeved on the outer periphery of the pipe body and is provided with a cavity;
and the annular magnet is arranged in the cavity of the annular float shell.
3. The resistive liquid level detection system of claim 1 or 2, wherein the slip ring further comprises:
the slip ring main body is positioned in the pipe body and is contacted with the inside of the pipe body, and a soft magnetic metal ring is embedded in the slip ring main body;
the sliding sleeves are respectively arranged on the opposite side walls of the sliding ring main body, and accommodating cavities are arranged in the sliding sleeves;
the elastic devices are respectively positioned in the accommodating cavities of the two sliding sleeves;
and the two sliding rods are fixedly connected with one end of the elastic device extending out of the accommodating cavity.
4. The resistive liquid level detection system according to claim 3, wherein a chute is provided on an inner wall of the pipe body, the chute extends along a length direction of the pipe body, a first protrusion structure is further provided on an outer side of the slip ring body, and the first protrusion structure is embedded in the chute.
5. The resistive liquid level detection system according to claim 3, wherein the slip ring further comprises two non-conductive nonmetallic cover plates respectively fixed at two ports of the slip ring main body, two resistor strip through holes are respectively arranged on the two nonmetallic cover plates, and the two resistor strip through holes are arranged at intervals; the positive electrode resistor strip and the negative electrode resistor strip respectively pass through two resistor strip through holes on the two nonmetallic cover plates.
6. The resistive liquid level detection system of claim 1, wherein the liquid level sensor further comprises:
one end of the positive terminal penetrates through the cover body and is connected with the positive resistor strip through a flexible wire, and the other end of the positive terminal extends to the upper part of the cover body;
and one end of the negative terminal penetrates through the cover body and is connected with the negative resistor strip through a flexible wire, and the other end of the negative terminal extends to the upper part of the cover body.
7. The resistive liquid level detection system of claim 6, wherein the liquid level sensor further comprises:
the non-conductive nonmetal plate is positioned in the pipe body, is positioned below the positive electrode resistor strip and the negative electrode resistor strip, and forms an accommodating space at the bottom of the pipe body; the uniform ends of the positive electrode resistor strips and the negative electrode resistor strips are connected with the nonmetal plate, and the other ends of the positive electrode resistor strips and the negative electrode resistor strips are connected with the nonmetal floating ring;
the balancing weight is positioned in the accommodating space;
and the limiting ring is positioned at the periphery of the pipe body and below the positive electrode resistor strip and the negative electrode resistor strip.
8. The resistive liquid level sensing system of claim 7, wherein the non-metallic floating ring and the non-metallic plate are each provided with a non-conductive non-metallic wedge block that blocks contact between the positive resistive strip and the negative resistive strip from therebetween when the slip ring is slid to the non-metallic floating ring or the non-metallic plate position.
9. The resistive liquid level detection system of claim 8, wherein the slip ring further comprises two non-conductive, non-metallic cover plates secured to two ports of the slip ring body, respectively; a nonmetallic wedge-shaped block via hole is arranged at the center of each nonmetallic cover plate; the nonmetallic floating ring and the nonmetallic wedge blocks on the nonmetallic plates respectively pass through nonmetallic wedge block through holes on the nonmetallic cover plates.
10. The resistive liquid level detection system according to claim 9, wherein the inner wall of the tube body is provided with a chute extending in the length direction of the tube body; the outer side of the nonmetallic floating ring is also provided with a second protruding structure, and the second protruding structure is embedded into the chute.
CN202011173103.XA 2020-10-28 2020-10-28 Resistance type liquid level detection system Active CN112325978B (en)

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