JP2013190347A - Capacitance type liquid level sensor and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost capacitance type liquid level sensor which can easily increase a capacitance change, which is insusceptible to dew condensation, and which is manufactured by an easy method, and a manufacturing method of the sensor.SOLUTION: The capacitance type liquid level sensor includes: a sensor electrode 20 composed of a slender support 21 including a curved part 211 which curves in a width direction of the support and first and second facing parts 212, 213 which integrally extend from both ends of the curved part 211 and which face each other in a longitudinal direction in a manner to leave a space between them, and strip-shaped first and second electrodes 22, 23 arranged on each of the first and second facing parts 212, 213 in their longitudinal directions; and a holder 10 holding the sensor electrode 20 in a manner to make planes of the first and second electrodes 22, 23 parallel. A liquid level is detected by the capacitance between the first electrode 22 and the second electrode 23, which varies according to a liquid level when a longitudinal direction of the sensor becomes perpendicular to a liquid surface.

Description

  The present invention relates to a capacitive liquid level sensor and a method for manufacturing a capacitive liquid level sensor.

  In the manufacturing process of the sensor electrode for detecting the capacitance in the capacitance type liquid level sensor, when measuring a low dielectric constant liquid or measuring the liquid level with high accuracy, the capacitance change is increased. There is a need. The structure of the sensor electrode is preferably a structure using an insulating laminate that is easy to mass-produce and insulates between the electrodes. However, when the capacitance change is increased, the electrode shape becomes complicated or the distance between the electrodes is reduced. It is necessary to shorten the length, and high accuracy is required at the time of manufacturing, which causes an increase in cost. Further, by shortening the distance between the electrodes, the measurement error becomes very large due to the adhesion of the liquid to the electrodes due to condensation or the like.

JP 2005-147779 A

  Accordingly, the present invention provides a capacitance type liquid level sensor that can easily increase the capacitance change, is not easily affected by condensation, is easy to manufacture, and is low in cost, and a method for manufacturing the same. Let it be an issue.

The invention according to claim 1 for solving the above-described problem is as follows.
An elongated support (21), which is curved in the width direction thereof (211), and extends integrally from both ends of the curved portion (211) and is opposed to each other in the longitudinal direction with a space therebetween. A support body (21) having first and second opposing portions (212, 213), and first and second strips arranged in the longitudinal direction of the first and second opposing portions (212, 213), respectively. A sensor electrode (20) comprising a second electrode (22, 23),
A holder (10) for holding the sensor electrode (20) so that the plane of the first electrode (22) and the plane of the second electrode (23) are parallel to each other;
The liquid level is determined by the capacitance between the first electrode (22) and the second electrode (23) that changes in accordance with the liquid level when the longitudinal direction is arranged perpendicular to the liquid level. It is characterized by detecting the level.

  In the first aspect of the present invention, the elongated support body (21) is curved in the width direction (211), and extends integrally from both ends of the curved section (211) and is mutually connected. A support body (21) having first and second facing portions (212, 213) facing each other in the longitudinal direction at intervals, and a longitudinal direction of the first and second facing portions (212, 213), respectively. The sensor electrode (20) comprising the strip-shaped first and second electrodes (22, 23) arranged, and the plane of the first electrode (22) and the plane of the second electrode (23) are parallel to each other. And a holder (10) for holding the sensor electrode (20). The curved sensor electrode (20) has a plane of the first electrode (22) and a plane of the second electrode (23) parallel to each other. It is hold | maintained at a holder (10) so that it may become. Therefore, by changing only the holder (10) that holds the sensor electrode (20), the distance between the electrodes can be freely adjusted, so that it can be adjusted for each liquid to be measured, and is adjusted to the measurement range in the detection circuit. Can be adjusted. Further, by forming the parallel electrodes by curving the sensor electrode (20), the facing area can be increased, and therefore it is not necessary to shorten the distance between the facing first electrode and the second electrode. . If the distance between the electrodes is short, it is easy to be affected by condensation and liquid adhering to the electrode surface. However, by setting the distance between the electrodes to an appropriate length, the influence of condensation and adhering liquid can be reduced.

The invention according to claim 2 for solving the above-described problem is as follows.
The capacitance type liquid level sensor according to claim 1,
The sensor electrode (20) further includes strip-shaped third and fourth electrodes (24, 25),
The third and fourth electrodes (24, 25) are sequentially stacked on the second electrode in an insulated state,
The third electrode (24) has a narrower width than the second and fourth electrodes (23, 25), and is substantially in the center in the width direction of the second and fourth electrodes (23, 25). And is laminated with only the second electrode (23) at the end opposite to the liquid surface side,
The second electrode when the portion of the third electrode (24) that is in a laminated state with only the second electrode (23) and the second electrode (23) are both in the liquid. The dielectric constant of the liquid is detected by a capacitance between the electrode (23) and the third electrode (24).

  In the invention according to claim 2, the sensor electrode (20) further includes strip-shaped third and fourth electrodes (24, 25), and the third and fourth electrodes (24, 25) are: The second electrode (23) is sequentially stacked and insulated from each other. The third electrode (24) is narrower than the second and fourth electrodes (23, 25) and has a second width. In addition, the fourth electrode (23, 25) is disposed substantially at the center in the width direction, and is laminated with only the second electrode (23) at the end opposite to the liquid surface side. Therefore, this portion can be used as a liquid dielectric constant measurement sensor. The third electrode forms the above portion only at the bottom of the liquid level, so that the second electrode (23) and the fourth electrode (25) are the third electrode at a higher liquid level than the above portion. Since the width is wider than (24), the shielding effect is enhanced by connecting the second electrode (23) and the fourth electrode (25) to the ground potential, and at a higher liquid level than the above part. Unaffected by level changes.

  The invention according to claim 3 for solving the above-mentioned problem is characterized in that, in the capacitance type liquid level sensor according to claim 1 or 2, the support (21) has flexibility. .

  In the invention according to claim 3, since the support body (21) has flexibility, the sensor electrode (20) can be easily bent, and the sensor electrode (20) is held by the holder 10. This makes it easier to work.

The invention according to claim 4 for solving the above-described problem is as follows.
The sensor electrode (20) having the first and second electrodes (22.23) and a holder (10) for holding the sensor electrode (20), and changes according to the liquid level of the liquid A capacitance type liquid level sensor manufacturing method for detecting a liquid level by a capacitance between a first electrode (22) and the second electrode (23),
On the elongated flexible support (21), the first and second electrodes (22, 23) for measuring the liquid level in the longitudinal direction are arranged in parallel with each other at a predetermined interval. A sensor electrode production step of producing a sensor electrode (20);
A bending step of bending the sensor electrode (20) so that the first electrode (22) and the second electrode (23) face each other;
Holding the curved sensor electrode (20) with the holder (10) so that the plane of the first electrode (22) and the plane of the second electrode (23) are parallel to each other; It is characterized by including.

  In the invention described in claim 4, the first and second electrodes (22, 23) for measuring the liquid level in the longitudinal direction of the elongated flexible support (21) are predetermined to each other. First and second sensor electrodes (20) arranged in parallel at intervals are produced, the produced sensor electrodes (20) are curved, and the curved sensor electrodes (20) are used to detect capacitance. The capacitance type liquid level sensor is manufactured by holding the two electrodes (22, 23) with the holder (10) so that the planes of the two electrodes (22, 23) are parallel. Therefore, the distance between the electrodes can be adjusted freely by changing only the holder (10) that houses the sensor electrode (20), so that it can be adjusted for each liquid to be measured, and is adjusted to the measurement range in the detection circuit. Can be adjusted. Further, by forming the parallel electrodes by curving the sensor electrode (20), the facing area can be increased, and therefore it is not necessary to shorten the distance between the facing first electrode and the second electrode. . If the distance between the electrodes is short, it is easy to be affected by condensation and liquid adhering to the electrode surface. However, by setting the distance between the electrodes to an appropriate length, the influence of condensation and adhering liquid can be reduced.

The invention according to claim 5 for solving the above-described problem is as follows.
In the manufacturing method of the capacitive liquid level sensor according to claim 4,
The sensor electrode manufacturing step further includes:
On the electrode of the second electrode (23), a strip-shaped third electrode (24) narrower than the second electrode (22) and a strip-shaped strip having substantially the same width as the second electrode (23). The fourth electrodes (25) are sequentially stacked in an insulated state while the third electrode (24) is disposed at substantially the center in the width direction of the second and fourth electrodes (23, 25). A stacking arrangement process;
In the end opposite to the liquid surface side of the third electrode (24), the third electrode (24) is laminated with only the second electrode (23), so that the fourth electrode A removing step of removing a part of the electrode (25),
In the bending step, a surface of the second electrode (23) on which the third and fourth electrodes (24, 25) are not stacked is opposed to the first electrode (22). It is characterized in that it is curved.

  In the invention described in claim 5, the sensor electrode manufacturing step further includes a strip-shaped third electrode (24) having a narrower width than the second electrode (22) on the electrode of the second electrode (23). The strip-shaped fourth electrode (25) having the same width as that of the second electrode (23) is arranged at the center of the second and fourth electrodes (23, 25) in the width direction. ), And the third electrode (24) is arranged at the end opposite to the liquid surface side of the third electrode (24), and the second electrode (23). And a removal step of removing a part of the fourth electrode (25) so as to be in a laminated state with only the third electrode), and in the bending step, the third and fourth electrodes in the second electrode (23) The side on which (24, 25) is not laminated is curved so as to face the first electrode (22). More, we are prepared capacitance type liquid level sensor. Therefore, the third electrode (24) part from which a part of the fourth electrode (25) is removed can be used as a liquid dielectric constant measurement sensor. The third electrode (24) forms the above portion only at the bottom of the liquid level, so that the second electrode (23) and the fourth electrode (25) are the first electrode at a higher liquid level than the above portion. Since the width is wider than the third electrode (24), the shielding effect is enhanced by connecting the second electrode (23) and the fourth electrode (25) to the ground potential, and the liquid level is higher than the above portion. Unaffected by level changes in levels.

  Note that the reference numerals in parentheses in the description of the means for solving the above-described problems correspond to the reference numerals of the constituent elements in the description of the mode for carrying out the invention below. It is not intended to limit the interpretation of the claims.

According to the first aspect of the present invention, the elongated support body is curved in the width direction thereof, and extends integrally from both ends of the curved portion, and is opposed to each other in the longitudinal direction at a distance from each other. A sensor electrode comprising: a support body having first and second facing portions; and strip-shaped first and second electrodes respectively disposed in a longitudinal direction of the first and second facing portions; A liquid surface height when the longitudinal direction is arranged perpendicularly to the liquid surface of the liquid, and a holder for holding the sensor electrode is provided so that the plane of the first electrode and the plane of the second electrode are parallel to each other Since the liquid level is detected by the capacitance between the first electrode and the second electrode that changes in accordance with the above, the following effects can be obtained.
(1) A liquid level sensor can be manufactured at low cost.
(2) There are few measurement errors due to the influence of the liquid adhering to the electrode surface.
(3) Since the distance between the electrodes can be freely adjusted, it can be adjusted to an appropriate distance according to the liquid to be measured.

  According to the second aspect of the present invention, the sensor electrode further includes strip-shaped third and fourth electrodes, and the third and fourth electrodes are sequentially insulated from each other on the second electrode. The third electrode is arranged in a stacked manner and has a narrower width than the second and fourth electrodes, and is arranged at substantially the center in the width direction of the second and fourth electrodes, and opposite to the liquid surface side. When the second electrode is laminated with only the second electrode at the end, and the portion of the third electrode that is laminated with only the second electrode and the second electrode are both in the liquid, the second Since the dielectric constant of the liquid is detected by the capacitance between the electrode and the third electrode, in addition to the effect of the invention of claim 1, the liquid level of a plurality of liquids having different dielectric constants is measured. An electrostatic capacitance type liquid level sensor capable of

  According to invention of Claim 3, since a support body has flexibility, a sensor electrode can be bent easily and the operation | work which hold | maintains a sensor electrode with a holder becomes easy.

According to invention of Claim 4, it is provided with the sensor electrode (20) which has the 1st and 2nd electrode (22.23), and the holder (10) holding this sensor electrode (20), A method of manufacturing a capacitive liquid level sensor that detects a liquid level by a capacitance between a first electrode (22) and a second electrode (23) that change according to a liquid level. The first and second electrodes (22, 23) for measuring the liquid level in the longitudinal direction are arranged in parallel on the elongated flexible support (21) at a predetermined interval from each other in the longitudinal direction. A sensor electrode manufacturing process for manufacturing the sensor electrode (20), a bending process for bending the sensor electrode (20) so that the first electrode (22) and the second electrode (23) face each other, and a bending process. The sensor electrode (20) is connected to the plane of the first electrode (22) and the second electrode (23). Since plane and a holding step of holding in a holder (10) so as to be parallel, the following effects.
(1) The electrode can be manufactured at low cost.
(2) Since the distance between the electrodes can be freely adjusted, it can be adjusted to an appropriate distance according to the liquid to be measured.

  According to the fifth aspect of the present invention, the sensor electrode manufacturing step further includes a strip-shaped third electrode (24) having a narrower width than the second electrode (22) on the electrode of the second electrode (23). And a fourth electrode (25) having a strip shape substantially the same width as that of the second electrode (23), and a third electrode (24) in the center of the second and fourth electrodes (23, 25) in the width direction. ), And the third electrode (24) is arranged at the end opposite to the liquid surface side of the third electrode (24), and the second electrode (23). And a removal step of removing a part of the fourth electrode (25) so as to be in a laminated state with only the third electrode), and in the bending step, the third and fourth electrodes in the second electrode (23) Since the surface on which (24, 25) is not laminated is curved so as to face the first electrode (22), the fourth A third electrode (24) portion by removing a part of the electrode (25) can be used as a dielectric constant measuring sensor of the liquid. The third electrode (24) forms the above portion only at the bottom of the liquid level, so that the second electrode (23) and the fourth electrode (25) are the first electrode at a higher liquid level than the above portion. Since the width is wider than the third electrode (24), the shielding effect is enhanced by connecting the second electrode (23) and the fourth electrode (25) to the ground potential, and the liquid level is higher than the above portion. Unaffected by level changes in levels.

1 shows one embodiment of a capacitive liquid level sensor of the present invention, (A) is a front view, (B) is a longitudinal sectional view in (A), and (C) is a sectional view taken along line II in (A). FIG. 4D is a cross-sectional view taken along line II-II in FIG. It is a figure explaining the preparation process of the sensor electrode of an electrostatic capacitance type liquid level sensor, (A) is a front view, (B) is the III-III sectional view taken on the line in (A). It is a figure explaining the preparation process of the sensor electrode of an electrostatic capacitance type liquid level sensor, (A) is a front view, (B) is the IV-IV sectional view taken on the line in (A). It is a figure explaining the preparation process of the sensor electrode of an electrostatic capacitance type liquid level sensor, (A) is a front view, (B) is the VV sectional view taken on the line in (A), (C) is (A). It is VI-VI sectional view taken on the line.

  FIG. 1 shows a configuration diagram of an embodiment of a capacitive liquid level sensor according to the present invention, where (A) is a front view, (B) is a longitudinal sectional view of (A), and (C) is ( A sectional view taken along the line II in A), and FIG. 4D is a sectional view taken along the line II-II in FIG.

  The capacitive liquid level sensor 1 includes a holder 10 and a sensor electrode 20 accommodated in the holder 10. The holder 10 is made of an insulating resin and includes an elongated cylinder 11 and an upper lid 12 and a lower lid 13 that cover the upper end and the lower end of the cylinder 11. The cylinder 11 has an oval cross section, and slit-like openings 11a and 11b penetrating into the cylinder 11 are formed in the upper and lower parts of the cylinder 11, respectively, and liquid enters and exits from the openings 11a and 11b. Can be done.

  The sensor electrode 20 is composed of four strip-shaped electrodes 22, 23, 24, 25 supported by an elongated insulator 21 as a support. The insulator 21 includes a curved portion 211 that is curved in the width direction, and first and second opposed portions 212 that extend integrally from both ends of the curved portion 211 and are opposed to each other in the longitudinal direction at intervals. 213. Each electrode is made of a strip-shaped conductive material such as stainless steel foil, copper foil, or aluminum foil. The insulator 21 is made of a flexible insulating material such as an insulating film (for example, PVC (polyvinyl chloride), PET (polyethylene terephthalate), PP (polypropylene), polyimide, etc.). The sensor electrode 20 can be produced by a general hot melt laminating method or a laminating method using an adhesive, and can be produced by using a technique such as extrusion molding.

  The electrode 22 is disposed on the facing portion 212, and the electrodes 23, 24, and 25 are stacked on the facing portion 213. The electrode 24 is sandwiched between the electrode 23 and the electrode 25. The electrodes 22 and 23 have the same width, the electrode 25 has approximately the same width as the electrodes 22 and 23, and the electrode 24 is narrower than the electrodes 22, 23, and 25. The electrode 22 is an electrode for measuring the liquid level, and the electrode 24 is an electrode for measuring the dielectric constant of the liquid. The liquid level is detected based on the capacitance between the electrode 22 and the electrode 23, and the dielectric constant of the liquid is detected based on the capacitance value between the electrode 24 and the electrode 23.

  2-4 is a figure which shows the preparation processes of a sensor electrode. First, a sensor electrode having the configuration shown in FIG. 2 is manufactured. Note that here, a case of manufacturing by a laminating method using an adhesive will be described.

  First, strip-like electrodes 22 and 23 are arranged in parallel in the longitudinal direction on a single thin insulating film, and are bonded together using an adhesive. Next, a second insulating film having a size slightly larger than the electrode 23 is placed on the electrode 23 and bonded with an adhesive. Next, the electrode 24 is disposed on the second insulating film at a substantially central position in the width direction of the electrode 23 and bonded with an adhesive. Next, a third insulating film having the same size as the second sheet is placed on the electrode 24 and bonded with an adhesive. Next, the electrode 25 is arranged on the third insulating film in accordance with the width of the electrode 23 and bonded with an adhesive. Next, the fourth insulating film 2 having the same size as the first sheet is placed on the electrode 22 and the third insulating film and bonded together with an adhesive.

  The sensor electrode 20 before processing produced in this way has a strip-like flexible insulator 21 and strip-like electrodes 22 and 23 arranged in parallel at intervals in the longitudinal direction, On the electrode 23, the electrodes 23 and 25 are sequentially laminated and arranged in an insulated state.

  Next, the unprocessed sensor electrode 20 produced by the above method is processed so as to have the shape shown in FIG. That is, the insulator 21 from the vicinity of the upper end of the sensor electrode 20 to the upper end is peeled and removed, a part of the electrodes 22, 23, 24, 25 is exposed, and the exposed electrode portions are respectively connected to the lead terminals 22a, 23a, 24a, And it cuts into the shape used as 25a (not shown) (it exists behind 24a). Further, a part of the electrode 25 and the insulator 21 from the vicinity of the lower end of the sensor electrode 20 to the lower end are peeled off and removed. Since a part of the electrode 25 is peeled off by this removal, the electrode 24 is formed in a layered state only with the electrode 23.

  Next, as shown in FIG. 4, the sensor electrode 20 processed into the shape shown in FIG. 3 is bent in a U shape so that the electrode 22 and the electrode 23 face each other.

  Next, as shown in FIG. 1, the sensor electrode 20 bent as shown in FIG. 4 is inserted into the cylinder 21 of the holder 10, and the outer periphery of the sensor electrode 20 is arranged along the inner wall of the cylinder 21. The At this time, the sensor electrode 20 is accommodated so that the plane of the fixed electrode 22 and the plane of the electrode 23 are parallel. After the sensor electrode 20 is received, the lower lid 13 is fitted by fitting the lower end of the sensor electrode 20 into the U-shaped concave portion of the lower lid 13 and fitting the lower end of the cylinder 11 into the oval concave portion of the lower lid 13. The lead terminals 22a to 25a that are fixed to the cylinder 11 and project from the upper part of the sensor electrode 20 are passed through the U-shaped through-holes of the upper lid 12 and exposed to the outside. The upper lid 13 is fixed to the cylinder 11 by fitting the upper end of the cylinder 11. In this way, a capacitive liquid level sensor in which the sensor electrode 20 is held by the holder 10 is completed.

  As described above, the capacitive liquid level sensor according to the present invention produces the sensor electrode 20 shown in FIG. 2 using, for example, a laminating method using an adhesive, and processes the produced sensor electrode 20. A sensor electrode manufacturing process for manufacturing the sensor electrode shown in FIG. 3, a bending process for bending the sensor electrode 20 shown in FIG. 3 as shown in FIG. 4, and a sensor electrode 20 bent as shown in FIG. As shown in FIG. 1, it is produced through a holding step of receiving and holding it in the holder 10.

  The sensor electrode manufacturing step further includes a strip-shaped third electrode 24 having a narrower width than the second electrode 23 and a strip-shaped strip having substantially the same width as the second electrode 23 on the electrode of the second electrode 23. A stacking step of sequentially stacking the fourth electrode 25 in a mutually insulated state while disposing the third electrode 24 at substantially the center in the width direction of the second and fourth electrodes 23, 25; A removal step of removing a part of the fourth electrode 25 so that the third electrode 24 is in a laminated state only with the second electrode 23 at the end opposite to the liquid surface side of the electrode 24. In the bending step, the surface of the second electrode 23 on the side where the third and fourth electrodes 24 and 25 are not laminated is curved so as to face the first electrode 22.

  The completed capacitive liquid level sensor 1 has a lower lid 13 located at the bottom of a tank (not shown) for containing liquid, and the longitudinal direction of the sensor electrode 20 is perpendicular to the liquid level. Used so that it is fixed.

  When the capacitance type liquid level sensor 1 is used, the electrodes 22 and 23 of the sensor electrode 20 increase or decrease in the portion immersed in the liquid following the liquid height, thereby the capacitance type liquid level. The sensor 1 can detect a change in capacitance between the electrode 22 and the electrode 23 corresponding to the liquid level of the liquid and obtain a detection output corresponding to the liquid level. The capacitance is determined by C = ε × S / d, where ε is the dielectric constant of the liquid, S is the area of the electrode, and d is the distance between the electrodes. Further, when the portion of the electrode 24 that is in a laminated state with only the electrode 23 and the electrode 23 are both in the liquid, the capacitance between both electrodes is detected, and the detection output corresponding to the dielectric constant of the liquid You can also get

  As described above, since the sensor electrode 20 is bent, the electrode 22 and the electrode 23 are held by the holder 10 so that the electrode 22 and the electrode 23 face each other and the plane of the electrode 22 and the plane of the electrode 23 are parallel to each other. The electrode 23 can be used as a liquid level sensor, and a part of the electrode 25 is peeled off so that a portion where the electrode 24 is laminated only with the electrode 23 is generated. Can be used as a dielectric constant measuring sensor. The electrode 24 forms the above portion only at the bottom of the liquid level, and the electrode 23 and the electrode 25 are sufficiently wider than the electrode 24 at a higher liquid level than the above portion. If the is connected to the ground potential, the shielding effect is enhanced and it is not affected by the level change at the liquid level higher than that of the exposed portion. Further, when the electrode 23 and the electrode 25 are connected to the ground potential, the lead terminal 23a and the lead terminal 25a are connected in common, whereby a three-terminal capacitance type liquid level sensor can be obtained.

  Furthermore, as shown in FIG. 4, the sensor electrode 20 is curved and the electrodes 22 and 23 are made to face each other, whereby parallel electrodes can be formed, and the liquid level can be measured with high accuracy. Since the area S can be increased by forming the parallel electrodes, it is not necessary to shorten the distance between the electrodes 22 and 23 facing each other. If the distance between the electrodes is short, it is easy to be affected by condensation and liquid adhering to the electrode surface. However, by setting the distance between the electrodes to an appropriate length, the influence of condensation and adhering liquid can be reduced.

  Further, since the sensor electrode 20 has a curved structure, the distance between the electrodes can be adjusted freely by changing only the holder 10 to be used. Therefore, the sensor electrode 20 can be adjusted for each liquid to be measured, and the measurement range in the detection circuit. It can be adjusted to suit.

  As described above, one embodiment of the present invention has been described. However, the present invention is not limited to this, and various modifications and applications are possible.

  For example, in the above embodiment, a part of the electrode 25 is peeled off in order to make a part of the electrode 24 that is in a laminated state only with the electrode 23, but instead, a part of the electrode 23 is peeled off. Also good.

  In the above embodiment, the electrodes 24 and 25 are stacked on the electrode 23. Instead, the electrodes 24 and 25 are stacked on the electrode 22. Also good.

  Alternatively, the sensor electrode may be configured such that only the first and second electrodes are omitted, and the third and fourth electrodes are omitted. In this case, in addition to being used as a capacitance type liquid level sensor dedicated to one type of liquid whose dielectric constant is known in advance, a member for measuring the dielectric constant of the liquid may be separately provided.

  Although not shown in the above embodiment, terminal fittings may be connected to the lead terminals 22a, 23a, 24a, and 25a, respectively.

  Furthermore, in the above embodiment, the holder is formed in a cylindrical shape, but any shape may be used as long as the shape of the sensor electrode can be held in a desired curved shape, for example, only a plurality of bands and upper and lower lids. Also good.

DESCRIPTION OF SYMBOLS 1 Capacitance type liquid level sensor 10 Holder 20 Sensor electrode 21 Insulator (support)
211 bending portion 212 facing portion 213 facing portion 22 electrode (first electrode)
23 electrode (second electrode)
24 electrodes (third electrode)
25 electrodes (fourth electrode)

Claims (5)

An elongated support body, a curved portion curved in the width direction thereof, and first and second opposed portions that extend integrally from both ends of the curved portion and are opposed to each other in the longitudinal direction at intervals. A sensor electrode comprising: a support body having: and strip-shaped first and second electrodes respectively disposed in the longitudinal direction of the first and second opposing portions;
A holder for holding the sensor electrode so that the plane of the first electrode and the plane of the second electrode are parallel,
Detecting the liquid level by the capacitance between the first electrode and the second electrode, which varies according to the liquid level when the longitudinal direction is arranged perpendicular to the liquid level. Capacitance type liquid level sensor. The capacitance type liquid level sensor according to claim 1,
The sensor electrode further includes strip-shaped third and fourth electrodes,
The third and fourth electrodes are sequentially stacked on the second electrode in an insulated state,
The third electrode has a narrower width than the second and fourth electrodes, and is disposed at substantially the center in the width direction of the second and fourth electrodes, and is opposite to the liquid surface side. In a laminated state with only the second electrode in the part,
When the portion of the third electrode that is in a stacked state with only the second electrode and the second electrode are both in the liquid, the second electrode and the third electrode A capacitance type liquid level sensor, wherein the dielectric constant of the liquid is detected by a capacitance between them. The capacitance type liquid level sensor according to claim 1 or 2,
The capacitance type liquid level sensor, wherein the support is flexible. A sensor electrode having first and second electrodes and a holder for holding the sensor electrode, and electrostatic between the first electrode and the second electrode changing according to the liquid level of the liquid A method of manufacturing a capacitive liquid level sensor that detects a liquid level by a capacity,
Sensor electrode production for producing a sensor electrode in which first and second electrodes for measuring the liquid level in the longitudinal direction are arranged in parallel at predetermined intervals on an elongated flexible support body Process,
A bending step of bending the sensor electrode so that the first electrode and the second electrode face each other;
A holding step of holding the curved sensor electrode with the holding tool so that the plane of the first electrode and the plane of the second electrode are parallel to each other. Manufacturing method of surface level sensor. In the manufacturing method of the capacitive liquid level sensor according to claim 4,
The sensor electrode manufacturing step further includes:
On the electrode of the second electrode, a strip-shaped third electrode having a narrower width than the second electrode, and a strip-shaped fourth electrode having the same width as the second electrode, the second and second electrodes A laminated arrangement step of sequentially arranging the third electrodes in an insulated state while arranging the third electrodes at substantially the center in the width direction of the four electrodes;
A removal step of removing a part of the fourth electrode so that the third electrode is in a laminated state only with the second electrode at the end opposite to the liquid surface side of the third electrode. Including
In the bending step, the surface of the second electrode on the side where the third and fourth electrodes are not stacked is bent so as to face the first electrode. Method for manufacturing a liquid level sensor.

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