JP2005221494A - Liquid state detecting element, and liquid state detecting sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid state detecting element and a liquid state detecting sensor hardly generating a detection error accompanying the deflection deformation of a film part, and hardly generating a detection error due to a substance other than a measuring objective liquid. <P>SOLUTION: A level detecting element 11 is provided with a reinforcement part comprising a conductive material in the film part 29, and is constituted in particular to arrange a pair of parallel reinforcement parts 25 constituting the reinforcement part 29 along side edges of the film part 29 while sandwiching a pair of detecting electrodes 13, the film part 29 is hardly deflection-deformed thereby along a longitudinal direction, and an inter-electrode distance is difficult to be changed in the detecting electrodes 13. A grounding terminal 26 of the reinforcement part 29 is grounded to a grounding line to narrow a distribution range of lines of electric force coming in and going out into/from the detecting electrodes 13. An electrostatic capacity measured in the paired detecting electrodes 13 is restrained thereby from being varied by an influence of a parasitic capacity of a casing 31, and the detection error of an oil level is thereby restrained from being generated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes a film portion and a pair of detection electrodes, and at least a part of the detection electrodes is immersed in the measurement target liquid, and the measurement target liquid is based on the capacitance between the electrodes in the pair of detection electrodes. The present invention relates to a liquid state detection element for detecting the state of the liquid and a liquid state detection sensor including such a liquid state detection element.

Conventionally, a liquid state detection element and a liquid state detection sensor that include a pair of detection electrodes and detect a liquid state based on a change in capacitance between the electrodes are known.
The liquid state detection element includes, for example, a liquid state detection element configured by forming a pair of detection electrodes on a printed circuit board, and a liquid state detection element configured by sealing a pair of detection electrodes with an insulating film. Yes (see Patent Document 1 and Patent Document 2).

In addition, the liquid state detection element configured using a printed circuit board is not suitable for applications that require downsizing (thinning) because the thickness dimension of the printed circuit board is large. Since the liquid state detection element to be configured has a small thickness dimension, it can be arranged even in a small arrangement space, and can meet the demand for downsizing (thinning).
JP 63-0799016 (printed circuit board 1, detection circuit 5) JP-A-4-258725 (Capacitance type level sensor)

  However, since the insulating film is flexible in nature, its rigidity is very low as compared with the printed circuit board, and if only a pair of detection electrodes is provided as in Patent Document 2, it is bent and deformed in the longitudinal direction. There is a problem that it is likely to occur. In particular, when the liquid state detecting element is attached to an oil tank of an automobile and the liquid state detecting element is used while standing in the oil tank, the bending deformation is easily promoted by the influence of the vibration of the vehicle. When the liquid state detection element (specifically, the insulating film) is deformed, the distance between the detection electrodes arranged in the insulating film changes, and the capacitance change characteristic with respect to the change in the liquid state is In order to show a change characteristic different from the change characteristic in the initial shape before deformation, there is a possibility that an error may occur in the detection result of the liquid state.

  On the other hand, the liquid state detection element is often used in a liquid state detection sensor together with a casing made of resin or the like and a support for supporting the liquid state detection element. This liquid state detection sensor is used for, for example, a use for detecting a liquid level (in other words, a liquid amount), a use for detecting a liquid deterioration state, and the like.

  However, in this liquid state detection sensor, since the casing and the support are arranged around or near the liquid state detection element, the capacitance between the detection electrodes is accurately determined due to the parasitic capacitance of the casing and the support. The measurement is affected and an error occurs in the detection result of the liquid state. Note that the parasitic capacitance of the casing and the support means a capacitance that is excessively generated when measuring the capacitance between the detection electrodes due to the dielectric constant that the material constituting the casing and the support itself can have.

  Therefore, the present invention has been made in view of such problems, and is a liquid state detection element in which a pair of detection electrodes is arranged on a flexible film portion, and a detection error due to the bending deformation of the film portion occurs. It is another object of the present invention to provide a liquid state detection element in which detection errors due to the influence of substances other than the liquid to be measured are unlikely to occur, and to provide a liquid state detection sensor including such a liquid state detection element. .

  In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a film portion made of a flexible insulating material extending in the longitudinal direction and the film portion are arranged in parallel on the same surface and in the longitudinal direction. A pair of detection electrodes extending in the direction, and at least part of the detection electrodes are immersed in the liquid to be measured, and the state of the liquid to be measured is detected based on the capacitance between the electrodes in the pair of detection electrodes The liquid state detecting element includes a reinforcing portion made of a conductive material outside the detection electrode in the film portion, and the reinforcing portion includes a ground terminal portion connected to the ground line, and a pair of A liquid state detection element comprising: a pair of parallel reinforcing portions extending in the longitudinal direction along a side edge of the film portion so as to sandwich the detection electrode.

  In this liquid state detection element, a reinforcing part made of a conductive material is provided in the film part, and in particular, a pair of parallel reinforcing parts constituting the reinforcing part is arranged along the side edge of the film part so as to sandwich the pair of detection electrodes. Therefore, the film portion is difficult to bend and deform in the longitudinal direction, and the distance between the electrodes in the pair of detection electrodes is difficult to change. As described above, since the distance between the electrodes of the detection electrode is less likely to change, it is possible to suppress the change characteristic of the capacitance with respect to the change in the liquid state from being different from the change characteristic in the original shape. A detection error can be prevented from occurring in the state detection.

  In addition, since the reinforcing portion is made of a conductive material and includes a grounding terminal portion, by grounding (electrically connecting) the grounding terminal portion to the ground line, the one detection electrode can be connected to the other. The distribution state of the electric lines of force directed to the detection electrode can be changed. In other words, by arranging the reinforcing portion connected to the ground potential on the outer side of the detection electrode in the film portion, electric lines of force that are input and output between the detection electrode and the reinforcing portion are generated. The distribution state can be changed so that the distribution range of the lines of electric force between the detection electrodes is narrowed.

  Thereby, for example, even when the liquid state detection element is disposed inside the casing or when the liquid state detection element is supported by the support, the capacitance between the pair of detection electrodes is not It can suppress that it changes with the influence of the parasitic capacitance of a support body.

  In other words, this liquid state detection element includes a grounded reinforcing portion, so that the capacitance of the detection electrode is easily changed in accordance with a change in the situation (dielectric constant change) in the immediate vicinity of the liquid state detection element. It is difficult for the capacitance of the detection electrode to change in response to a situation change (change in dielectric constant) in the region.

  Thereby, the capacitance of the liquid state detection element is easily changed according to the measurement target liquid arranged in the nearest region, and the detection accuracy of the liquid state can be improved. In addition, since the liquid state detection element is not easily affected by a substance (casing or the like) disposed in a distant area, the parasitic capacitance generated between the detection electrode and a substance other than the other detection electrode is reduced. It is possible to suppress the occurrence of a liquid state detection error. In particular, in the present invention, a pair of parallel reinforcing portions arranged so as to sandwich a pair of detection electrodes for the purpose of preventing the bending deformation of the film portion is connected to the ground potential so as to function as a guard electrode. Thus, the measurement accuracy of the capacitance between the detection electrodes can be increased, and the detection accuracy of the liquid state can be effectively increased.

  The liquid state that can be detected by the liquid state detection element is, for example, dielectric due to a change in properties of the liquid itself, such as a liquid deterioration state (oil deterioration state), a liquid level state (liquid amount), a liquid concentration, or the like. A liquid state in which the capacitance between the detection electrodes changes with a change in the rate or a change in the dielectric constant due to the presence or absence of a liquid can be given.

  Next, in the above-described liquid state detection element, as described in claim 2, the parallel reinforcement portion of the reinforcement portion has a width dimension in the width direction orthogonal to the longitudinal direction larger than the width dimension of the detection electrode. It is good to be formed.

  That is, by ensuring a large width dimension of the parallel reinforcing portions, the physical strength as the reinforcing portion can be increased, and the occurrence of a detection error due to the bending deformation of the film portion can be more appropriately prevented.

  In addition, by ensuring a large width of the parallel reinforcing portions, it is possible to increase the electrical shielding effect against the parasitic capacitance of substances other than the liquid to be measured in the detection electrode, and it is possible to improve the detection accuracy of the liquid state. .

  Next, in the above-described liquid state detection element, as described in claim 3, the reinforcing portion may include a connection reinforcing portion that connects one end portions of the pair of parallel reinforcing portions.

  That is, in addition to the pair of parallel reinforcing portions as the reinforcing portion, by providing a connection reinforcing portion that connects the one end portions of both detection electrodes, it is possible to effectively prevent the film portion from being deformed in the width direction.

  Thereby, it is possible to prevent the distance between the detection electrodes from changing, and the change characteristic of the capacitance between the detection electrodes with respect to the change in the liquid state shows a change characteristic different from the change characteristic in the initial inter-electrode distance. Therefore, it is possible to prevent an error from occurring in the detection result of the liquid state.

Next, in the above-described liquid state detection element, as described in claim 4, the detection electrode and the reinforcing portion may be formed of the same type of conductive material.
In other words, when the detection electrode and the reinforcing part are formed of the same conductive material, the detection electrode forming process and the reinforcing part forming process are performed in separate steps in the manufacturing process of the liquid state detecting element. Instead, in the same process, the detection electrode and the reinforcing portion can be formed simultaneously.

  Next, in the above-described liquid state detection element, as described in claim 5, the liquid state detection element is arranged side by side on the same surface of the film portion, and is arranged at a height different from the arrangement position of the pair of detection electrodes. The pair of parallel reinforcing portions may be disposed so as to sandwich the pair of reference electrodes.

By the way, as a liquid state detection element, a pair of reference electrodes is provided separately from the pair of detection electrodes, and the liquid state is detected based on both the capacitance between the detection electrodes and the capacitance between the reference electrodes. There is. When such a reference electrode is integrally provided on the film portion on which the detection electrode is provided, the capacitance between the reference electrodes is measured when the distance between the reference electrodes changes due to the deformation of the film portion. The accuracy may decrease and an error may occur in the detection accuracy of the liquid state.
On the other hand, in the present invention, the parallel reinforcing portion for suppressing the bending deformation of the film portion is arranged not only to sandwich the pair of detection electrodes, but also to sandwich the pair of reference electrodes. ing. This prevents the interelectrode distance of the reference electrode from changing in addition to the detection electrode, and allows the liquid state to be detected based on the capacitance between the detection electrodes and the capacitance between the reference electrodes. Accuracy can be increased.

  Next, in order to achieve the above-mentioned object, the invention according to claim 6 is provided with a film portion made of a flexible insulating material extending in the longitudinal direction, and juxtaposed on the same surface of the film portion. A liquid state detecting element having a pair of detection electrodes extending in the longitudinal direction, and a support that supports the liquid state detecting element, and at least a part of the liquid state detecting element is immersed in the liquid to be measured. Thus, at least a part of the detection electrode is immersed in the measurement target liquid, and a liquid state detection sensor that detects the state of the measurement target liquid based on the capacitance between the electrodes in the pair of detection electrodes, The liquid state detection element is constituted by the liquid state detection element according to any one of claims 1 to 5, wherein the support has a support part that supports a front surface and a back surface of the film part, and the film A pair arranged in the section That the parallel reinforcing portion part each of the at least so located on the support portion for supporting the liquid state detecting element, a liquid-state detecting sensor according to claim.

  Since this liquid state detection sensor includes the liquid state detection element described above (in any one of claims 1 to 5) as a liquid state detection element, the liquid state detection element (film portion) is bent. It is possible to exhibit an effect that a detection error due to deformation hardly occurs and a detection error due to the influence of the parasitic capacitance of the support hardly occurs.

  And this liquid state detection sensor has a support part which supports the surface and back surface of a film part as a support body which supports a liquid state detection element, and at least one of each of a pair of parallel reinforcement parts arrange | positioned at a film part. It is characterized in that a support for supporting the liquid state detecting element is provided by arranging the part on the support. In other words, in this liquid state detection sensor, the liquid state is detected between the support portions in a state in which at least a part of each of the pair of parallel reinforcing portions whose rigidity is increased among the liquid state detection elements is arranged on the support portion of the support body. A detection element is interposed.

  From this, the liquid state detection sensor can be used for stable support of the liquid state detection element on the support, and combined with the effect of increasing the rigidity of the film portion by the reinforcing portion, The bending deformation of the detection element can be effectively suppressed. In addition, this liquid state detection sensor has a structure in which the liquid state detection element does not easily drop from the support portion of the support, and can prevent a detection error caused by the drop of the liquid state detection element.

  In addition, as a form which supports the surface and the back surface of the film part of a liquid state detection element with the support part of a support body, for example, a liquid state detection element (film part) from both surfaces of a film surface, while a support part contacts a film part ). As another form, the support portion includes a gap portion having a gap size larger than the thickness size of the liquid state detection element, and the liquid state detection element (film portion) is fitted into the gap portion in the gap portion. An intervening form can also be taken. That is, the support portion of the support body may be in a shape that can limit the movement range of the liquid state detection element to a range in which an error in detection accuracy does not occur, and is not limited to a specific shape.

  Further, in the liquid state detection sensor, as described in claim 7, the support body has an upright pin, and the liquid state detection element has a through hole that penetrates the film portion. The liquid state detecting element may be positioned on the support by inserting a pin into the through hole.

  In this liquid state detection sensor, a pin formed on the support is inserted into a through-hole formed in the film portion so that the liquid state detection element is positioned on the support. The position of the detection electrode can be reliably positioned with respect to the support. Therefore, even when the liquid state detection sensor for supporting the liquid state detection element using the support is mass-produced, the arrangement position of the detection electrode for detecting the liquid state on the support is prevented from varying between individuals. As a result, it is possible to suppress variations in detection accuracy among individual liquid state detection sensors of the same product number.

Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1
In the present embodiment, an oil level sensor 1 that is installed in an oil tank that contains oil and detects an oil level (liquid level) in the oil tank will be described. The oil level varies depending on the amount of oil stored in the oil tank.

FIG. 1 is a partially cutaway sectional view of an oil level sensor 1 showing a part of the internal structure of the oil level sensor 1.
The oil level sensor 1 includes a level detection element 11 having a pair of detection electrodes, and a casing 31 that houses the level detection element 11 and positions the level detection element 11.

  In FIG. 1, a part of the oil level sensor 1 and the level detection element 11 are shown as a cross-sectional view in order to represent an internal structure of a portion of the casing 31 where the level detection element 11 is disposed.

First, the level detection element 11 in the oil level sensor 1 will be described.
FIG. 2 is an explanatory diagram (cross-sectional view) showing the level detection element 11.
The level detection element 11 includes a rectangular film portion 29 made of a flexible insulating material (polyimide or the like) and various electrodes (a pair of detection electrodes) made of a conductive material (copper or the like) embedded in the film portion 29. The electrode 13, the pair of reference electrodes 17, the grounding electrode 27), and the reinforcing portion 21 formed in the outer portion of various electrodes inside the film portion 29. That is, the pair of detection electrodes 13, the pair of reference electrodes 17, the grounding electrode 27, and the reinforcing portion 21 are sealed with two polyimide films, and are configured by laminating two films. Are arranged side by side on the same surface of the film portion 29 to be formed.

  The pair of detection electrodes 13 are each formed in a long shape, and are arranged in parallel in a state parallel to the longitudinal direction. The pair of detection electrodes 13 arranged in parallel in this way has a characteristic that the capacitance between the electrodes changes according to the dielectric constant of the substance arranged around itself. Therefore, the capacitance between the electrodes of the pair of detection electrodes 13 (hereinafter also referred to as the capacitance of the detection electrode 13) is the ratio of the portion immersed in oil in the longitudinal dimension of the detection electrode 13 (detection). It varies depending on the oil immersion ratio of the electrode 13 for use.

  That is, there is a correlation between the capacitance of the detection electrode 13 and the oil immersion rate of the detection electrode 13, and the oil immersion rate of the detection electrode 13 is determined based on the capacitance of the detection electrode 13. Can be identified. Therefore, the level detection element 11 including the detection electrode 13 can be used for detection of the oil level (liquid level) in the installation region (inside the oil tank).

  The pair of reference electrodes 17 are formed in an elongated shape that is shorter than the detection electrode 13, and on the distal end side (lower side in the figure) of the film electrode 29 with respect to the longitudinal direction. They are arranged in parallel in a parallel state. Like the detection electrode 13, the pair of reference electrodes 17 arranged in parallel as described above has a characteristic that the capacitance between the electrodes changes in accordance with the dielectric constant of the substance arranged around itself. Further, since the reference electrode 17 is formed on the tip side of the detection electrode 13 and is arranged on the bottom side in the oil tank, the reference electrode 17 is arranged at a position where the whole itself is always immersed in oil. For this reason, the capacitance between the electrodes of the pair of reference electrodes 17 (hereinafter also referred to as the capacitance of the reference electrode 17) changes depending only on the dielectric constant of the oil.

  When the oil is deteriorated due to deterioration or when different types of oil are additionally stored, the dielectric constant of the oil changes even at the same oil level. If the oil level is detected based only on the capacity, the detection accuracy is lowered.

  Therefore, in the present embodiment, the capacitance detected using the reference electrode 17 is used as a reference value, and the oil level is detected using both the reference capacitance and the capacitance of the detection electrode 13. I am doing so. Thereby, even when the dielectric constant of the oil changes due to the deterioration of the oil or the like, the oil level can be appropriately detected.

The detection electrode 13 and the reference electrode 17 each have a thickness dimension of 50 [μm] and a width dimension W1 of 2.0 [mm].
The level detection element 11 includes two level lead portions 15 extending from the rear end portions (upper end portions in FIG. 2) of the two detection electrodes 13 toward the rear end of the film portion 29. Two reference lead portions 19 extending from the rear end portions (upper end portions in FIG. 2) of the two reference electrodes 17 to the rear end of the film portion 29 are provided.

  The level lead portion 15 includes a connection terminal portion 16 at its rear end portion, and the reference lead portion 19 includes a connection terminal portion 20 at its rear end portion. When the level detection element 11 is supported by the casing 31, the level lead part 15 and the reference lead part 19 are different from each other in the metal lead member 33 (see FIG. 1). Is connected to various external devices provided outside the oil level sensor 1 through the metal lead member 33.

  The ground electrode 27 is formed on the rear end side (upper side in the drawing) of the detection electrode 13 in the film portion 29 and at a position between the two level lead portions 15. The grounding electrode 27 includes a grounding terminal portion 28 at its rear end. The grounding electrode 27 is connected to the metal lead member 33 (see FIG. 1) when the level detecting element 11 is supported by the casing 31, so that the grounding electrode portion 28 is connected to the metal lead member 33 via the metal lead member 33. Connected to a ground line (ground potential line).

  When the grounding electrode 27 is grounded to the ground line, the capacitance between the electrodes of the pair of level lead portions 15 is reduced. Thereby, when measuring the electrostatic capacitance of the detection electrode 13, it is possible to suppress the electrostatic capacitance of the level lead portion 15 from adversely affecting the stray capacitance.

  The reinforcing portion 21 is made of a conductive material (copper or the like), and is formed on the outer side of the film portion 29 from the detection electrode 13 and the reference electrode 17. The reinforcing portion 21 includes a pair of parallel reinforcing portions 25 arranged in parallel in a state parallel to the longitudinal direction of the detection electrode 13, and a connection reinforcing portion 23 formed on the tip side of the reference electrode 17. And.

  The pair of parallel reinforcing portions 25 are disposed outside the reference electrode 17 and the reference lead portion 19 in the film portion 29. That is, the pair of parallel reinforcing portions 25 extends so as to sandwich the pair of detection electrodes 13, the level lead portion 15, the reference lead portion 19 and the reference electrode 17 and along the side edge of the film portion 29. Has been placed.

In addition, the parallel reinforcement part 25 of the reinforcement part 21 is formed so that the thickness dimension becomes 50 [μm] and the width dimension W2 on the film surface becomes 2.2 [mm].
The connection reinforcing part 23 is formed to extend in the width direction (left and right direction in FIG. 2) on the film surface of the film part 29 so as to connect the tip portions of the pair of parallel reinforcing parts 25 respectively.

  The connection reinforcing portion 23 of the reinforcing portion 21 has a thickness dimension of 50 [μm], and a height dimension W3 in a direction perpendicular to its longitudinal direction on the film surface is 1.0 [mm]. Is formed.

  The reinforcing portion 21 includes a grounding terminal portion 26 connected to the ground line at the rear end portion of the parallel reinforcing portion 25. When the level detection element 11 is supported by the casing 31, the grounding terminal portion 26 is connected to the metal lead member 33 (see FIG. 1), so that the reinforcing portion 21 is grounded via the metal lead member 33. Connected to a line (ground potential line).

Next, the casing 31 of the oil level sensor 1 will be described.
In addition, FIG. 3 shows a cross-sectional view of the oil level sensor 1 in FIG. In addition, the cross-sectional view showing the BB cross section of the oil level sensor 1 in FIG. 3 corresponds to the fracture cross-sectional portion in FIG.

  As shown in FIG. 1 and FIG. 3, the casing 31 has an axis line by combining a first semi-cylindrical member 35 and a second semi-cylindrical member 37 made of an insulating synthetic resin (for example, 6-6 nylon). It is formed in a long and substantially cylindrical shape extending in the direction, and includes an internal space 43 for placing the level detection element 11 therein.

  The casing 31 includes a plurality of front end side through holes 39 that communicate from the outside to the internal space 43 on the front end side in the axial direction (the lower side in FIG. 1), and communicates with the internal space 43 at a substantially central portion in the axial direction of the casing 31. A plurality of center side through holes 41 are provided. That is, the casing 31 is configured such that a substance (oil, air, etc.) can move between the outside of the casing 31 and the internal space 43 through the front end side through hole 39 and the center side through hole 41.

  The front end side through-hole 39 and the center side through-hole 41 are provided at positions that do not correspond to the portions around the radial direction of the level detection element 11 in a state where the level detection element 11 is arranged in the casing 31. . This is because the oil entering and exiting the casing 31 does not directly collide with the level detecting element 11, and the occurrence of detection errors due to instantaneous oil level changes due to vibration or the like is prevented.

  Further, the casing 31 has a flange portion 45 extending radially outward and a connector portion 47 to which a device-side connector connected to an external device is connected to the rear end side in the axial direction of the casing 31 (upper side in FIG. 1). It is equipped with. The flange portion 45 is provided to abut the outer surface of the oil tank when the oil level sensor 1 is attached to the oil tank, and to determine the insertion direction position of the oil level sensor 1 (casing 31) in the oil tank. . The connector portion 47 includes a metal terminal that is electrically connected to each metal lead member 33, and a connector frame portion that can be fitted to the device-side connector. It is provided to form a current path from the electrode to the external device.

  Further, as shown in FIG. 3, the casing 31 includes two support portions 49 serving as gap spaces between the first semi-cylindrical member 35 and the second semi-cylindrical member 37. The support portion 49 is formed such that its own gap interval dimension W4 is larger than the thickness dimension of the level detection element 11.

And the level detection element 11 determines the arrangement position in the internal space 43 of the casing 31 by arrange | positioning the both-sides edge part in the own width direction in the support part 49, respectively.
At this time, the casing 31 positions the level detection element 11 in the internal space 43 by disposing at least a part of each of the pair of parallel reinforcing portions 25 of the level detection element 11 on the support portion 49. As a result, the casing 31 can support the high-strength portion (the portion that is difficult to deform) of the level detection element 11 with the support portion 49, and the reinforcing portion 21 is provided to provide a flexible film portion 29. Combined with the effect of increasing the rigidity, it is possible to effectively prevent the deformation of the level detecting element 11 and to prevent the level detecting element 11 from dropping from the support portion 49.

  Since the gap interval dimension of the support part 49 is larger than the thickness dimension of the level detection element 11, the casing 31 is supported in a state where a gap is generated between the inner surface of the support part 49 and the outer surface of the level detection element 11. The level detection element 11 is sandwiched in the thickness direction by the portion 49 and the level detection element 11 is supported in the width direction by the two support portions 49.

  When the oil level sensor 1 is disposed in the oil tank that is the measurement target region, an amount of oil corresponding to the oil level (liquid level) is taken into the internal space 43. At this time, the level detection element 11 is immersed in oil at a rate corresponding to the oil level, and the capacitance of the detection electrode 13 shows a value corresponding to the oil level. Further, the capacitance of the reference electrode 17 shows a value corresponding to the dielectric constant of the oil.

  The level detection element 11 includes a reinforcing portion 21 connected (grounded) to the ground line, so that the parasitic capacitance caused by the casing 31 is larger than the capacitance of the detection electrode 13 and the capacitance of the reference electrode 17. Therefore, when detecting the oil level, it is possible to detect the oil level with high accuracy while suppressing the occurrence of an error.

Then, the external device connected to the oil level sensor 1 executes processing for determining the oil level based on the capacitance of the detection electrode 13 and the capacitance of the reference electrode 17.
Here, when the level detection element 11 is arranged inside the casing 31, an explanatory view schematically showing the distribution state of the lines of electric force that enter and exit the detection electrode 13 is shown in FIG. 4.

  In FIG. 4, the distribution state of the electric lines of force when the reinforcing portion GND is not grounded is shown on the upper side of the figure, and the distribution state of the electric lines of force when the reinforcing portion GND is grounded is shown on the lower side of the figure. In FIG. 4, the lines of electric force are indicated by dotted lines, and the reference lead portion 19 is not shown.

  As shown in FIG. 4, in the reinforced portion GND non-ground state, the electric lines of force entering and exiting from the detection electrode 13 are distributed over a wide range, and there is a portion that penetrates the casing 31. On the other hand, in the grounded state of the reinforcing portion GND, a part of the electric lines of force entering and exiting from the detection electrode 13 enters and exits the grounded reinforcing portion 21, thereby reducing the distribution range of the electric lines of force. The electric field lines do not penetrate the casing 31.

  As described above, since the lines of electric force do not penetrate the casing 31, it is possible to suppress the capacitance of the detection electrode 13 from being affected by the dielectric constant of the casing 31, and the parasitic capacitance due to the casing 31. Can be suppressed.

  As described above, the level detection element 11 of the present embodiment includes the reinforcing portion 21 and has a high strength. Therefore, the film portion 29 is hardly bent and deformed, and the distance between the pair of detection electrodes 13 and The distance between the electrodes of the pair of reference electrodes 17 is not easily changed. As described above, since the interelectrode distance of the detection electrodes is difficult to change, the change characteristic of the capacitance with respect to the change of the oil level becomes different from the change characteristic in the initial shape of the level detection element 11. It is possible to suppress the occurrence of detection error in oil level detection.

  In addition, since the reinforcing portion 21 is made of a conductive material (copper) and includes a grounding terminal portion 26, by grounding (electrically connecting) the grounding terminal portion 26 to the ground line, The distribution state is changed so that the distribution range of the electric lines of force from the detection electrode 13 to the other detection electrode 13 and the distribution range of the electric lines of force from the one reference electrode 17 to the other reference electrode 17 are narrowed. it can.

  Thereby, even when the level detection element 11 is disposed inside the casing 31, the capacitance between the electrodes in the pair of detection electrodes 13 and the capacitance between the electrodes in the pair of reference electrodes 17 are It can suppress that it changes with the influence of the parasitic capacitance of the casing 31. FIG.

  Therefore, the level detection element 11 of the present embodiment is unlikely to cause a detection error due to bending deformation, and a liquid state detection element that hardly causes a detection error due to the influence of a substance (casing 31) other than oil that is a liquid to be measured. Become.

  Further, since the width dimension W2 of the parallel reinforcing portion 25 is larger than the width dimension W1 of the detection electrode 13 and the reference electrode 17, the level detecting element 11 can secure a larger strength as the reinforcing portion 21, and the film portion. It is possible to more appropriately prevent occurrence of a detection error due to the bending deformation of 29.

  Note that the parallel reinforcing portion 25 can obtain an electrical shielding effect even when the width dimension is smaller than that of the detection electrode 13, and suppresses the influence of the parasitic capacitance of the casing 31 to reduce detection errors. The effect of doing can be obtained.

  Further, in the level detection element 11, the detection electrode 13, the reference electrode 17 and the reinforcing portion 21 are all made of copper, and are made of the same type of conductive material. Therefore, in the manufacturing process of the level detecting element 11, the forming process (etching process or printing process) of the detection electrode 13 and the reference electrode 17 and the forming process (etching process or printing process) of the reinforcing portion 21 are performed separately. It can be performed in the same process, not in the process.

  As a result, a plurality of processes in the manufacturing process of the level detection element 11 can be integrated into one process, the number of processes can be reduced, and the manufacturing efficiency of the level detection element 11 can be improved.

  In the present embodiment, the level detection element 11 corresponds to the liquid state detection element recited in the claims. The casing 31 corresponds to the support described in the claims.

[Embodiment 2]
Next, the oil level sensor 100 according to the second embodiment will be described. As shown in FIG. 6, this oil level sensor 100 is used by being attached to an oil tank bottom LT of an automobile engine such that its axis AX coincides with the vertical direction V and its tip is vertically upward. Used to detect the level of oil OL in the oil tank.

  As shown in FIGS. 5 and 6, the oil level sensor 100 includes a resin base member 121 and a substantially cylindrical sensor cap 111 disposed so as to protrude from the base member 121. Yes. The sensor cap 111 having a hollow structure surrounds a level detection element 131 having a pair of detection electrodes 133 and the like provided in the film portion 132 and a support 180 for supporting the level detection element 131 in the vertical direction. doing. A communication hole 115 for circulating the surrounding oil OL into and out of the sensor cap 111 is formed at the base end of the sensor cap 111, and a communication hole 113 for venting air is formed at the distal end. Yes.

  The base member 121 supports the support body 180 and the sensor cap 111. The oil level sensor 100 is attached to the oil tank by fixing the base member 121 to the oil tank bottom LT with these being inserted into the oil tank (see FIG. 6).

  In the oil level sensor 100 according to the second embodiment, first, the level detection element 131 will be described with reference to FIGS. 7 (a) and 7 (b). As shown in FIG. 7A, the level detecting element 131 has a relatively wide first rectangular portion 132h and a tapered shape in order from the base end (lower end in the drawing) to the tip end (upper end in the drawing) in the longitudinal direction. The film portion 132 has a shape in which the trapezoidal tapered portion 132p and the relatively narrow second rectangular portion 132n are connected. In addition, the film part 132 is formed from the flexible polyimide like the said Embodiment 1. FIG.

  In the film portion 132, various electrodes (a pair of detection electrodes 133 and a pair of reference electrodes 139) made of a conductive material (such as copper) and a reinforcing portion 137 disposed on the outer portions of the various electrodes. And have. That is, the pair of detection electrodes 133, the pair of reference electrodes 139, and the reinforcing portion 137 are sealed by two polyimide films, and the two films are laminated and bonded via the epoxy resin paste EP. Are arranged side by side on the same surface of the film portion 132 (see FIG. 7B).

  The pair of detection electrodes 133 is configured to extend in the longitudinal direction of the film part 132 and is disposed on the second rectangular part 132n and the taper part 132p of the film part 132. Note that one of the pair of detection electrodes 133 is linear, and the other is U-shaped. One of the pair of detection electrodes 133 is connected to a first electrode terminal 141 formed in a square shape via a first electrode connection line 142, and the other is a second electrode formed in a square shape. The electrode terminal 143 is connected via the second electrode connection line 144.

In addition, a pair of comb-like reference electrodes 139 are arranged on the base end side of the detection electrode 133 in the film portion 132 so as to face each other so as to mesh with each other. Has been. One of the pair of reference electrodes 139 is connected to a first reference electrode terminal 145 formed in a square shape via a first reference electrode connection line 146, and the other is similarly formed in a square shape. The second reference electrode terminal 147 is connected to the second reference electrode terminal 147 through a second reference electrode connection line 148.
The principle of detecting the oil level using both the capacitance measured by the pair of detection electrodes 133 and the capacitance measured by the pair of reference electrodes 139 is described in the first embodiment. This is the same as described in.

  The reinforcing portion 137 is made of a conductive material (such as copper), and is formed on the outer side of the film portion 132 from the pair of detection electrodes 133 and the pair of reference electrodes 139. Further, the reinforcing portion 137 includes a pair of parallel reinforcing portions 151 arranged in parallel in a state parallel to the longitudinal direction of the detection electrode 133, and a connection reinforcing portion formed on the tip side of the detection electrode 133. 153. The pair of parallel reinforcing portions 151 includes a pair of detection electrodes 133, first and second electrode terminals 141 and 143, first and second electrode connection lines 142 and 144, a pair of reference electrodes 139, and first and second reference electrode terminals 145. 147 and the first and second reference electrode connection lines 146 and 148. Moreover, the connection reinforcement part 153 is formed so that it may extend in the width direction of the film part 132 so that the front-end | tip part of a pair of parallel reinforcement part 151 may be connected, respectively.

  The reinforcing portion 137 has a grounding terminal 155 connected to a ground line formed in a square shape, and the rear ends of the pair of parallel reinforcing portions are connected to the grounding terminal 155, respectively. When the level detecting element 131 is assembled to the base member 121, the grounding terminal 155 is connected to the wiring member 161, and the reinforcing portion 137 is connected to the ground line (ground potential line through the wiring member 161 when in use. ).

Here, an elliptical through-hole 171 which is long in the longitudinal direction is provided in a portion located in the vicinity of the tip of the film portion 132 in the center in the width direction. The upper through-hole 171 is for positioning the film part 132 and holding the film part 132 so that the tip side does not float when the film part 132 is assembled to a support member 180 described later. Further, the tapered portion 131h is also provided with a circular through hole 173 for positioning the film portion 132.
In addition, in the level detection element 131 concerning this Embodiment 2, since the effect by providing the said reinforcement part 137 is the same as that of Embodiment 1 mentioned above, it abbreviate | omits.

Next, the support 180 in the oil level sensor 100 according to the second embodiment will be described with reference to FIG. FIG. 8 shows a state in which the level detection element 131 is assembled to the support 180, but in order to make the configuration of the support 180 easy to understand, the detection electrode 133 and the reinforcing portion 137 of the level detection element 131 are shown. The illustration of various conductors such as is omitted.
The support 180 is made of 66 nylon and has a frame shape that approximates its planar shape so that the periphery of the film portion 132 can be supported. The support 180 protrudes inward from the left and right frame portions 189 and supports a support portion 181, an upper support pin 183, a center support pin 185, which alternately support the front and back surfaces near the side edges of the film portion 132. A lower holding part 187 is included.

  The support 180 supports the film part 132 in a form in which the film part 132 is alternately sandwiched between a plurality of support parts 181 formed along the longitudinal direction. Furthermore, the support 180 is caulked by ultrasonic welding after the upper support pin 183 and the center support pin 185 are inserted into the upper through hole 171 and the center through hole 173 of the film part 132, respectively. The entire film portion 132 is supported by sandwiching the base end of the film portion 132 with the sandwiching portion 187. In order to support the level detection element 131 (film part 132) on the support body 180, although not shown, at least one of each of the pair of parallel reinforcing parts 151 provided on the film part 132 on each support part 181. The dimensions of the support 141 and the level detection element 131 are appropriately adjusted so that the portions are arranged (stradded).

  As shown in FIGS. 5 and 6, a wiring board 163 is provided inside the base member 121, and the electrode terminals 141, 143, 145, 147, 155 of the level detection element 131 and the wiring board 163 are separated from each other. It is electrically connected via the wiring member 161. Further, the base member 121 has a connector part 123, the connector terminal 165 provided in the connector part 123 and the wiring board 163 are electrically connected, and the connector terminal 165 is connected to an external device (not shown). The

As mentioned above, although embodiment of this invention was described, this invention can take a various aspect, without being limited to the said Embodiment 1,2.
For example, the dimensions of the detection electrode, the reference electrode, and the reinforcing portion are not limited to the above numerical values, and can be appropriately set according to various conditions such as a detection target and an installation environment.

  Moreover, the liquid used as a measuring object should just be a liquid with a dielectric constant different from air, and is not restricted to the oil mentioned above, For example, gasoline, water, etc. can be mentioned.

Further, the liquid state detection element is limited to a configuration in which two sets of detection electrodes (a pair of detection electrodes 13 and a pair of reference electrodes 17) are integrally provided in one film portion, like the level detection element 11 described above. It will never be done. For example, a first liquid state detection element including a pair of detection electrodes 13 and a second liquid state detection element including a pair of reference electrodes 17 are formed using separate film portions, respectively, and the first liquid state detection element is formed. The liquid state (oil level) can also be detected using the element and the second liquid state detection element.
Moreover, the material which comprises a reinforcement part is not restricted to copper, For example, 42Ni-Fe alloy, stainless steel, etc. can also be used.

It is a partially broken sectional view of the oil level sensor concerning Embodiment 1. FIG. 3 is an explanatory diagram illustrating a level detection element according to the first embodiment. It is sectional drawing showing the AA view cross section in the oil level sensor of FIG. It is explanatory drawing which represented typically the distribution state of the electric force line | wire which goes in and out of a detection electrode, when a level detection element is arrange | positioned inside a casing. It is a front view of the oil level sensor concerning Embodiment 2. It is explanatory drawing of the state which attached the oil level sensor concerning Embodiment 2 to the oil tank of a motor vehicle engine. FIG. 4 is an explanatory diagram of a level detection element according to a second embodiment, where (a) is a plan view of the level detection element, and (b) is an exploded sectional view (BB sectional view) of the level detection element. It is a perspective view which shows the state which assembled | attached the level detection element to the support body concerning Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 ... Oil level sensor 11, 131 ... Level detection element, 13, 133 ... Detection electrode, 17, 139 ... Reference detection electrode, 21, 137 ... Reinforcement part, 23, 153 ... Connection reinforcement part, 25, 151 ... Parallel reinforcement part, 26, 155 ... Grounding terminal part, 29, 132 ... Film part, 31 ... Casing (support), 43 ... Internal space, 49, 181 ... Support part, 111 ... Sensor cap, 171 ... Upper part Through-holes 171, 173... Central portion through-hole, 180... Support, 183... Upper support pin, 185.

Claims (7)

A film portion made of a flexible insulating material extending in the longitudinal direction;
A pair of detection electrodes that are arranged in parallel on the same surface of the film portion and extend in the longitudinal direction,
A liquid state detection element for detecting a state of the measurement target liquid based on a capacitance between the electrodes in the pair of detection electrodes, wherein at least a part of the detection electrode is immersed in the measurement target liquid;
Outside the detection electrode of the film portion, provided with a reinforcing portion made of a conductive material,
The reinforcing part is
A grounding terminal connected to the ground line;
A pair of parallel reinforcing portions extending in the longitudinal direction along the side edges of the film portion so as to sandwich the pair of detection electrodes,
A liquid state detecting element characterized by the above. The parallel reinforcing portion of the reinforcing portion is formed such that a width dimension in a width direction orthogonal to the longitudinal direction is larger than a width dimension of the detection electrode.
The liquid state detecting element according to claim 1. The reinforcing portion includes a connection reinforcing portion that connects one end portions of the pair of parallel reinforcing portions,
The liquid state detecting element according to claim 1, wherein the liquid state detecting element is a liquid state detecting element. The detection electrode and the reinforcing portion are formed of the same type of conductive material;
The liquid state detection element according to claim 1, wherein the liquid state detection element is a liquid state detection element. A pair of reference electrodes arranged in parallel on the same surface of the film portion and at a height different from the position where the pair of detection electrodes are disposed, and the pair of parallel reinforcing portions are the pair The reference electrode is also sandwiched between,
The liquid state detection element according to claim 1, wherein: A liquid state detection element comprising: a film portion made of a flexible insulating material extending in the longitudinal direction; and a pair of detection electrodes arranged in parallel on the same surface of the film portion and extending in the longitudinal direction;
A support for supporting the liquid state detection element,
At least a part of the liquid state detection element is immersed in the liquid to be measured, so that at least a part of the detection electrode is immersed in the liquid to be measured, and the capacitance between the electrodes in the pair of detection electrodes A liquid state detection sensor for detecting the state of the liquid to be measured based on
The liquid state detection element includes the liquid state detection element according to any one of claims 1 to 5,
The support has a support part that supports the front surface and the back surface of the film part, and at least a part of each of the pair of parallel reinforcing parts provided in the film part is disposed on the support part in the liquid state. Supporting the sensing element;
A liquid state detection sensor. The support has an upright pin, the liquid state detection element has a through-hole penetrating the film portion, and the liquid state detection is performed by inserting the pin into the through-hole. The liquid state detection sensor according to claim 6, wherein an element is positioned on the support.