JP2014081257A - Sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor device capable of suppressing erroneous detection of a sensor device in the present description.SOLUTION: A sensor device 10 comprises an electrode pair 15 and an electrode pair 17. The electrode pair 15 includes an electrode 12 and an electrode 14 having a surface facing a portion of the surface of the electrode 12. The electrode pair 17 includes the electrode 12 and an electrode 16 having a surface facing a portion that does not face the electrode 14 in the surface of the electrode 12. When being viewed from a cross section orthogonal to a depth direction of an oil pan 4, the area of a gap between the electrode 12 and the electrode 14 is larger than the area of a gap between the electrode 12 and the electrode 16.

Description

  The present specification discloses a sensor device including a liquid level electrode pair for specifying the liquid level and a liquid quality electrode pair for specifying the liquid quality.

  Patent Document 1 discloses a capacitance type level sensor. The level sensor includes a cylindrical outer cylinder and an inner cylinder arranged inside the outer cylinder. A main sensor and a reference sensor made of a conductive material are attached to the outer surface of the inner cylinder. The main sensor and the outer cylinder constitute one electrode pair, and the reference sensor and the outer cylinder constitute another one electrode pair. The electrode spacing in one electrode pair is equal to the electrode spacing in the other electrode pair.

JP-A-5-322629

  In order to increase the sensitivity of the sensor device, it is preferable to narrow the distance between the electrodes in the electrode pair. On the other hand, if the distance between the electrodes in the electrode pair is too narrow, there is a high possibility that the liquid level between the electrodes rises higher than the liquid level of the surrounding liquid due to the surface tension of the liquid, so-called capillary phenomenon. . As a result, the sensor device may be erroneously detected. The present specification provides a technique capable of arranging the electrodes of the liquid level electrode pair and the liquid quality electrode pair at appropriate intervals.

  The technology disclosed in the present specification relates to a sensor device. The sensor device includes a liquid level electrode pair for specifying the liquid level of the liquid in the container, and a liquid for specifying the liquid quality of the liquid in the container. A quality electrode pair. The liquid level electrode pair includes a first electrode and a second electrode having a facing surface facing a part of the surface of the first electrode. The liquid quality electrode pair includes a first electrode common to the liquid level electrode pair, and a third surface having a facing surface facing a portion of the surface of the first electrode not facing the second electrode. Electrodes. When viewed in a cross section orthogonal to the depth direction of the container, the area of the gap between the first electrode and the second electrode is larger than the area of the gap between the first electrode and the third electrode.

  In order to avoid a situation in which the capacitance of the liquid quality electrode pair changes due to a change in the liquid level of the liquid quality, the liquid quality electrode pair is usually used in a state of being totally immersed in the liquid. That is, the liquid electrode pair is used in a state where the liquid is filled between the first electrode and the third electrode. In this state, when the liquid quality is specified using the liquid quality electrode pair, no error occurs due to an increase in the liquid level due to the capillary phenomenon. For this reason, in the sensor device, the distance between the first electrode and the third electrode is relatively small. On the other hand, in the liquid level electrode pair, it is necessary to avoid a situation where the liquid level of the liquid between the first electrode and the second electrode rises due to the capillary phenomenon. For this reason, in the sensor device, the distance between the first electrode and the second electrode is relatively large. According to this configuration, the electrodes of the liquid level electrode pair and the liquid quality electrode pair can be arranged at appropriate intervals.

The schematic block diagram of the sensor system of 1st Example is shown. Sectional drawing of the II-II cross section of FIG. 1 is shown. Sectional drawing of the III-III cross section of FIG. 1 is shown. The schematic longitudinal cross-sectional view of the sensor apparatus of 2nd Example is shown. Sectional drawing of the VV cross section of FIG. 4 is shown. The schematic longitudinal cross-sectional view of the sensor apparatus of 3rd Example is shown. Sectional drawing of the VII-VII cross section of FIG. 6 is shown. The schematic perspective view of the electrode of 4th Example is shown. Sectional drawing of the IX-IX cross section of FIG. 8 is shown. The schematic perspective view of the electrode of a modification is shown.

  The main features of the embodiments described below are listed. Note that the technical elements described below are independent technical elements, and exhibit technical usefulness alone or in various combinations.

(Feature 1) The first electrode may include a cylindrical first tube portion. The 2nd electrode may be provided with the cylindrical 2nd cylinder part arranged in either the inside or the outside of the 1st cylinder part. The 3rd electrode may be provided with the cylindrical 3rd cylinder part arranged in either the inside or the outside of the 1st cylinder part.

  According to this structure, a sensor apparatus can be made small compared with the case where a flat electrode pair is used.

(Feature 2) At least one of the first cylinder part, the second cylinder part, and the third cylinder part may be made of a cylindrical conductive material.

(Characteristic 3) At least one cylinder part of the first cylinder part, the second cylinder part, and the third cylinder part is made of a cylindrical substrate and a conductive material disposed on the substrate. It may be.

(Characteristic 4) The first electrode is connected to the first flat plate, the second flat plate arranged in parallel with the first flat plate, and the first flat plate and the second flat plate. And a plate. The second electrode may include a third flat plate disposed between the first flat plate and the second flat plate. The third electrode may include a fourth flat plate disposed between the first flat plate and the second flat plate and below the third flat plate.

  According to this configuration, each electrode can be easily manufactured while ensuring the capacitance of the electrode pair.

(First embodiment)
A sensor system 2 shown in FIG. 1 is mounted on an automobile. The sensor system 2 is used to specify the remaining amount of engine oil in the engine (not shown). The sensor system 2 includes a sensor device 10 and a control circuit 50. In FIG. 1, the sensor device 10 is described in a longitudinal sectional view, and the control circuit 50 is described in a circuit diagram.

  The sensor device 10 is disposed in the oil pan 4 of the engine. Engine oil is stored in the oil pan. The sensor device 10 includes three electrodes 12, 14, 16 and a support member 20. Each electrode 12, 14, 16 is made of a conductive material such as a copper alloy. Each electrode 12, 14, 16 may be covered with a protective film made of a material such as polyethylene.

  The electrode 12 has a cylindrical shape. The inner diameter of the electrode 12 is constant in the axial direction. Two electrodes 14 and 16 are arranged inside the electrode 12. The electrode 14 has a cylindrical shape. The electrode 14 is disposed coaxially with the electrode 12. The outer diameter of the electrode 14 is smaller than the inner diameter of the electrode 12 and is constant in the axial direction. The outer peripheral surface of the electrode 14 faces a part of the inner peripheral surface of the electrode 12. One electrode pair 15 is configured by the mutually facing portions of the electrode 12 and the electrode 14. That is, the electrode pair 15 includes the electrodes 12 and 14.

  Below the electrode 14, the electrode 16 is disposed with a gap from the lower end of the electrode 14. The electrode 16 has a cylindrical shape. The electrode 16 is disposed coaxially with the electrodes 12 and 14. The outer diameter of the electrode 16 is constant in the axial direction. The outer diameter of the electrode 16 is smaller than the inner diameter of the electrode 12 and larger than the outer diameter of the electrode 14. The outer peripheral surface of the electrode 16 faces a part of the inner peripheral surface of the electrode 12. The outer peripheral surface of the electrode 16 is opposed to the inner peripheral surface of the electrode 12 below a part of the inner peripheral surface of the electrode 12 opposed to the outer peripheral surface of the electrode 14. That is, the outer peripheral surface of the electrode 16 is opposed to a portion of the inner peripheral surface of the electrode 12 that is not opposed to the outer peripheral surface of the electrode 14. One electrode pair 17 is configured by the mutually facing portions of the electrode 12 and the electrode 16. That is, the electrode pair 17 includes the electrodes 12 and 16.

  As shown in FIG. 2, when viewed in a cross section orthogonal to the axial direction of the electrodes 12, 14, that is, the depth direction of the oil pan 4, the distance between the electrode 12 and the electrode 14, that is, the inner periphery of the electrode 12. The distance between the surface and the outer peripheral surface of the electrode 14 is constant over the entire circumferential length of the electrode 14. The distance between the electrode 12 and the electrode 14 is constant over the entire length of the electrodes 12 and 14 in the axial direction.

  As shown in FIG. 3, when viewed in a cross section orthogonal to the axial direction of the electrodes 12, 16, that is, the depth direction of the oil pan 4, the distance between the electrodes 12 and 16, that is, the inner periphery of the electrode 12. The distance between the surface and the outer peripheral surface of the electrode 16 is constant over the entire circumferential length of the electrode 16. The distance between the electrode 12 and the electrode 16 is constant over the entire axial length of the electrodes 12 and 16.

  Comparing FIG. 2 and FIG. 3, the distance between the electrode 12 and the electrode 14 is larger than the distance between the electrode 12 and the electrode 16. Therefore, the area of the gap between the electrode 12 and the electrode 14 is the area of the gap between the electrode 12 and the electrode 16 in the cross section orthogonal to the axial direction of the electrode 12 or the like at any position in the axial direction of the electrode 12 or the like. Bigger than.

  The electrodes 12, 14, and 16 are supported by the support member 20. The support member 20 is made of resin. The support member 20 includes a lower support portion 22 and an upper support portion 24. The lower support portion 22 includes a base portion 22d and columnar portions 22a, 22b, and 22c. The base 22d has a cylindrical shape. The base portion 22 d is fixed to the oil pan 4 with bolts in a state where the upper surface of the base portion 22 d is in contact with the lower surface of the oil pan 4. Thereby, the sensor device 10 is fixed to the oil pan 4. The base 22 d covers an opening formed in the bottom wall of the oil pan 4. The columnar part 22c protrudes upward from the center part of the upper surface of the base part 22d. The columnar part 22c has a cylindrical shape. The columnar portion 22 c passes through the opening of the oil pan 4 and is disposed in the oil pan 4. The lower ends of the electrodes 12 and 16 are inserted into the columnar portion 22c. Thereby, the columnar portion 22 c supports the electrodes 12 and 16. The columnar part 22b protrudes upward from the center part of the upper surface of the columnar part 22c. The columnar part 22b has a cylindrical shape. The columnar portion 22b is arranged coaxially with the electrode 12 and the like. The columnar portion 22 b is inserted into the electrode 16 and fitted therein, thereby positioning the electrode 16 so as not to move with respect to the support member 20. The columnar portion 22 b reaches the upper end of the electrode 16 from a portion located above the columnar portion 22 c of the electrode 16.

  The columnar part 22a protrudes upward from the upper end of the columnar part 22b. The columnar part 22a has a cylindrical shape. The columnar portion 22a is disposed coaxially with the columnar portion 22b. The columnar portion 22 a is inserted and fitted into the electrode 14, thereby positioning the electrode 14 so as not to move with respect to the support member 20. The columnar portion 22a extends from the lower end of the electrode 14 to the vicinity of the upper end.

  An upper support portion 24 is disposed at the upper end of the columnar portion 22a. The upper support portion 24 includes a columnar portion 24a and a columnar portion 24b. The columnar part 24b has a cylindrical shape. The columnar portion 24b is disposed coaxially with the columnar portions 22a and 22b. The lower end of the columnar part 24b is in contact with the upper end of the columnar part 22a. The columnar portion 24 b is fitted to the electrode 14 at the upper end portion of the electrode 14. A columnar portion 24a is disposed at the upper end of the columnar portion 24b. The columnar part 24a has a cylindrical shape. The columnar part 24a is arranged coaxially with the electrodes 12, 14 and the columnar part 24b. The columnar portion 24 a is fitted to the electrode 12. As a result, the upper ends of the electrodes 12 and 14 are positioned by the upper support portion 24, and the lower ends thereof are positioned by the lower support portion 22. As a result, the three electrodes 12, 14, and 16 are positioned so as not to move relative to each other by the support member 20.

  The support member 20 is provided with a through hole (not shown) for allowing engine oil to flow inside the electrode 12. As a result, the engine oil flows into the gap between the electrode 12 and the electrode 14 and the gap between the electrode 12 and the electrode 16. A through hole or a slit for allowing engine oil to flow into the electrode 12 may be provided in the electrode 12.

  The control circuit 50 is a circuit for controlling the sensor device 10. The control circuit 50 includes an oscillation unit 52 and a calculation unit 54. The oscillation unit 52 supplies a signal (for example, an AC voltage of 10 Hz to 3 MHz) to the sensor device 10. In the modification, the oscillating unit 52 may supply a pulse signal to the sensor device 10. The calculation unit 54 detects a signal supplied from the oscillation unit 52 to the sensor device 10 and specifies the remaining amount of engine oil. The electrode 12 is grounded.

  Specifically, the oscillation unit 52 supplies a signal to the electrode 16. The calculation unit 54 detects a signal supplied from the oscillation unit 52 to the electrode 16. The electrode 16 is located near the bottom surface of the oil pan 4. For this reason, normally, the electrode pair 17 is entirely immersed in the engine oil. As a result, the capacitance of the electrode pair 17 depends on the quality of the engine oil, for example, the degree of deterioration of the engine oil (for example, the degree of oxidation), the component ratio of the engine oil, and the component and amount of foreign matter in the engine oil. Change. For this reason, the signal supplied to the electrode 16 from the oscillation part 52 correlates with the quality of engine oil.

  Next, the calculation unit 54 detects a signal supplied from the oscillation unit 52 to the electrode 14. The length of the electrode pair 15 immersed in the engine oil changes according to the remaining amount of engine oil in the oil pan 4. For this reason, the electrostatic capacitance of the electrode pair 15 changes according to the remaining amount of engine oil. For this reason, the signal supplied to the electrode 14 from the oscillation part 52 correlates with the remaining amount of engine oil. Further, the signal supplied from the oscillating unit 52 to the electrode 14 correlates with the quality of the engine oil, similarly to the signal supplied from the oscillating unit 52 to the electrode 16.

  The arithmetic unit 54 calculates the signal supplied from the oscillating unit 52 to the electrode 14, that is, a value correlated with the capacitance of the electrode pair 15, and the signal supplied from the oscillating unit 52 to the electrode 16, that is, the electrostatic of the electrode pair 17. The remaining amount (that is, the liquid level) of the engine oil is specified using the value correlated with the capacity. The calculation unit 54 specifies the remaining amount of engine oil by a database or a mathematical expression that represents the relationship between each signal that has been obtained in advance by experiment or analysis and the remaining amount of engine oil. Thereby, the calculating part 54 can specify the residual amount of engine oil in consideration of the liquid quality of engine oil.

(Effect of this embodiment)
In this embodiment, the electrode pair 17 for specifying the liquid quality of the engine oil is used in a state where it is immersed in the liquid as a whole. That is, the electrode pair 17 is used in a state where the engine oil is filled between the electrode 12 and the electrode 16. For this reason, in the electrode pair 17, an error does not arise by the raise of the liquid level of the engine oil between the electrode 12 and the electrode 16 by a capillary wrinkle phenomenon. In the configuration of this embodiment, the distance between the electrode 12 and the electrode 16 is relatively small. For this reason, the capacitance of the electrode pair 17 varies greatly according to the change in the quality of the engine oil (for example, the degree of deterioration of the engine oil). According to the configuration of this embodiment, by reducing the distance between the electrode 12 and the electrode 16, the sensitivity of the sensor device 10 in the electrode pair 17, that is, the change in the capacitance of the electrode pair 17 with respect to the change in liquid quality. Can be bigger.

  On the other hand, in the electrode pair 15 for specifying the remaining amount of engine oil, the level of the engine oil between the electrode 12 and the electrode 14 needs to be equal to the level of the liquid in the oil pan 4. For this reason, in the electrode pair 15, the rise in the liquid level between the electrode 12 and the electrode 14 due to the capillary wrinkle phenomenon must be avoided. In the configuration of this embodiment, the distance between the electrode 12 and the electrode 14 is larger than the distance between the electrode 12 and the electrode 16. For this reason, the electrode pair 15 can suppress erroneous detection of the remaining amount of engine oil by suppressing the capillary wrinkle phenomenon. In the present embodiment, the electrodes 12, 14, 16 can be arranged at appropriate intervals in accordance with the respective uses of the two electrode pairs 15, 17. As a result, the performance of the sensor system 2 can be improved by changing the distance between the electrodes.

  In this embodiment, the electrodes 12, 14, and 16 have a cylindrical shape. According to this configuration, the sensor device 10 can be made smaller without reducing the capacitance of the electrode pairs 15 and 17 as compared with the case where the electrodes 12, 14 and 16 have a flat plate shape.

(Second embodiment)
The sensor system 2 of the second embodiment includes a sensor device 100 instead of the sensor device 10 as compared to the first embodiment. Since the other configuration is the same as that of the first embodiment, the description thereof is omitted.

  As shown in FIG. 4, the sensor device 100 includes three electrodes 112, 114, and 116, substrates 111 and 113, and a support member 120. The substrate 111 has a cylindrical shape. The substrate 111 is made of a resin such as polyphenylene sulfide. The inner diameter of the substrate 111 is constant in the axial direction. An electrode 112 is disposed on the inner peripheral surface of the substrate 111. The electrode 112 is made of a conductive material such as a copper alloy. The electrode 112 is formed on the entire inner peripheral surface of the substrate 111 in a range not in contact with the support member 120. The electrode 112 is formed in a cylindrical shape. The thickness of the electrode 112 is constant. Therefore, the inner diameter of the electrode 112 is constant in the axial direction.

  Inside the electrode 112, two electrodes 114 and 116 and a substrate 113 are arranged. The substrate 113 has a cylindrical shape. The substrate 113 is disposed coaxially with the substrate 111. The substrate 113 is made of the same resin as the substrate 111. The outer diameter of the substrate 113 is smaller than the inner diameter of the substrate 111 and is constant in the axial direction. Two electrodes 114 and 116 are arranged on the outer peripheral surface of the substrate 113. The two electrodes 114 and 116 are made of the same material as the electrode 112. The electrode 114 is formed in a cylindrical shape. The thickness of the electrode 114 is constant. The outer diameter of the electrode 114 is smaller than the inner diameter of the electrode 112 and is constant in the axial direction. The outer peripheral surface of the electrode 114 is opposed to a part of the inner peripheral surface of the electrode 112. One electrode pair 115 is configured by the mutually facing portions of the electrode 112 and the electrode 114. That is, the electrode pair 115 includes the electrodes 112 and 114.

  Below the electrode 114, the electrode 116 is disposed at a distance from the lower end of the electrode 114. The electrode 116 is formed in a cylindrical shape. The thickness of the electrode 116 is constant. The electrode 116 is thicker than the electrode 114. The outer diameter of the electrode 116 is constant in the axial direction. The outer diameter of the electrode 116 is smaller than the inner diameter of the electrode 112 and larger than the outer diameter of the electrode 114. The outer peripheral surface of the electrode 116 faces a part of the inner peripheral surface of the electrode 112. The outer peripheral surface of the electrode 116 is opposed to the inner peripheral surface of the electrode 112 below a part of the inner peripheral surface of the electrode 112 opposed to the outer peripheral surface of the electrode 114. That is, the outer peripheral surface of the electrode 116 is opposed to the inner peripheral surface of the electrode 112 that is not opposed to the outer peripheral surface of the electrode 114. One electrode pair 117 is configured by the portions of the electrode 112 and the electrode 116 facing each other. That is, the electrode pair 117 includes the electrodes 112 and 116.

  As shown in FIG. 5, when viewed in a cross section orthogonal to the axial direction of the substrates 111 and 113, that is, the depth direction of the oil pan 4, the distance between the electrode 112 and the electrode 114, that is, the inner periphery of the electrode 112. The distance between the surface and the outer peripheral surface of the electrode 114 is constant over the entire length of the electrode 114 in the circumferential direction. The distance between the electrode 112 and the electrode 114 is constant over the entire axial length of the substrate 111 and the like. Similarly, the distance between the electrode 112 and the electrode 116, that is, the distance between the inner peripheral surface of the electrode 112 and the outer peripheral surface of the electrode 116 is constant over the entire circumferential length of the electrode 116. In addition, the distance between the electrode 112 and the electrode 116 is constant over the entire axial length of the substrate 111 and the like. The distance between the electrode 112 and the electrode 114 is larger than the distance between the electrode 112 and the electrode 116. Therefore, at any position in the axial direction of the substrate 111 or the like, the area of the gap between the electrode 112 and the electrode 114 in the cross section orthogonal to the axial direction of the substrate 111 or the like is the area of the gap between the electrode 112 and the electrode 116. Bigger than.

  The substrates 111 and 113 are supported by the support member 120. The support member 120 is made of resin. The support member 120 includes a lower support part 122 and an upper support part 124. The lower support part 122 includes a base part 122c and a columnar part 122a. The base 122c has a cylindrical shape. The lower surface of the base 122c is in contact with the oil pan. The lower ends of the substrates 111 and 113 are inserted into the base 122c. As a result, the base 122c supports the substrates 111 and 113. The columnar portion 122a protrudes upward from the central portion of the upper surface of the base portion 122c. The columnar part 122a has a cylindrical shape. The columnar portion 122b is arranged coaxially with the substrate 111 and the like. The columnar portion 122a is inserted and fitted into the substrate 113, thereby positioning the substrate 113 so as not to move with respect to the support member 120. The columnar portion 122a extends from the lower end of the substrate 113 to the vicinity of the upper end.

  An upper support portion 124 is disposed at the upper end of the columnar portion 122a. The upper support portion 124 includes a columnar portion 124a and a columnar portion 124b. The columnar part 124b has a cylindrical shape. The columnar part 124b is arranged coaxially with the columnar part 122a. The lower end of the columnar part 124b is in contact with the upper end of the columnar part 122a. The columnar portion 124 b is fitted to the substrate 113 at the upper end portion of the substrate 113. A columnar portion 124a is disposed at the upper end of the columnar portion 124b. The columnar part 124a has a cylindrical shape. The columnar part 124a is arranged coaxially with the columnar part 122a. The columnar part 124 a is fitted to the substrate 111. That is, the support member 120 is in contact with the inner peripheral surface of the substrate 111 at a part of the upper end and a part of the lower end of the substrate 111.

  The upper ends of the substrates 111 and 113 are positioned by the upper support portion 124, and the lower ends thereof are positioned by the lower support portion 122. As a result, the three electrodes 112, 114, and 116 are positioned relatively immovably by the support member 120.

  The support member 120 is provided with a through hole (not shown) for allowing engine oil to flow inside the substrate 111. As a result, the engine oil flows into the gap between the electrode 112 and the electrode 114 and the gap between the electrode 112 and the electrode 116. A through hole or a slit for allowing engine oil to flow into the inside of the substrate 111 may be provided in the substrate 111.

  One terminal 130 is connected to the lower end of the substrate 111. The terminal 130 is connected to the electrode 112 through a conductive wire on the substrate 111. Two terminals 132 and 134 are connected to the lower end of the substrate 113. Each of the terminals 132 and 134 is connected to each of the electrodes 116 and 114 via a conductive wire on the substrate 113.

  Signals are alternately supplied to the electrodes 114 and 116 from the oscillation unit 52 via the terminals 132 and 134. The electrode 112 is grounded.

(Effect of this embodiment)
In this embodiment, as in the first embodiment, in the electrode pair 117 for specifying the quality of engine oil, the distance between the electrode 112 and the electrode 116 is relatively small. Therefore, by reducing the distance between the electrode 112 and the electrode 116, the sensitivity of the sensor device 100 in the electrode pair 117, that is, the change in capacitance of the electrode pair 117 with respect to the change in liquid quality can be increased. Further, in the electrode pair 115 for specifying the remaining amount of engine oil, the distance between the electrode 112 and the electrode 114 is larger than the distance between the electrode 112 and the electrode 116. Therefore, the electrode pair 115 can suppress erroneous detection of the remaining amount of engine oil by suppressing the capillary wrinkle phenomenon. In the present embodiment, the electrodes 112, 114, and 116 can be arranged at appropriate intervals according to the respective uses of the two electrode pairs 115 and 117. As a result, the performance of the sensor system 2 can be improved by changing the distance between the electrodes.

(Third embodiment)
The sensor system 2 of the third embodiment includes a sensor device 300 instead of the sensor device 10 as compared with the first embodiment. Since the other configuration is the same as that of the first embodiment, the description thereof is omitted. In the present embodiment, the same configurations as those of the sensor device 100 of the second embodiment are denoted by the same reference numerals as those in FIG.

  As shown in FIG. 6, the sensor device 200 includes three electrodes 212, 214, 216, substrates 111, 113, and a support member 120. Two electrodes 214 and 216 are arranged on the inner peripheral surface of the substrate 111. The two electrodes 214 and 216 are made of a conductive material such as a copper alloy. The electrode 214 is formed in a cylindrical shape. The thickness of the electrode 214 is constant. The inner diameter of the electrode 214 is constant in the axial direction.

  An electrode 216 is disposed below the electrode 214 with a gap from the lower end of the electrode 214. The electrode 216 is formed in a cylindrical shape. The thickness of the electrode 216 is constant. The electrode 216 is thicker than the electrode 214. The inner diameter of the electrode 216 is constant in the axial direction and is smaller than the inner diameter of the electrode 214.

  An electrode 212 is disposed on the outer peripheral surface of the substrate 113. The electrode 212 is made of the same material as the electrodes 214 and 216. The electrode 212 is formed in a cylindrical shape. The electrode 212 is formed on the entire outer surface of the substrate 113 excluding the portion where the substrate 113 is inserted into the base portion 122c. The thickness of the electrode 212 is constant. The inner diameter of the electrode 212 is smaller than the inner diameters of the electrodes 214 and 216 and is constant in the axial direction. A part above the inner peripheral surface of the electrode 212 faces the inner peripheral surface of the electrode 214. One electrode pair 215 is configured by the mutually facing portions of the electrode 212 and the electrode 214. That is, the electrode pair 215 includes the electrode 212 and the electrode 214. A part below the inner peripheral surface of the electrode 212 faces the inner peripheral surface of the electrode 216. One electrode pair 217 is configured by the portions of the electrode 212 and the electrode 216 facing each other. That is, the electrode pair 217 includes an electrode 212 and an electrode 216.

  As shown in FIG. 7, when viewed in a cross section orthogonal to the axial direction of the substrate 111 or the like, that is, a cross section orthogonal to the depth direction of the oil pan 4, the distance between the electrode 212 and the electrode 214, that is, the electrode 212. The distance between the outer peripheral surface of the electrode 214 and the inner peripheral surface of the electrode 214 is constant over the entire length of the electrode 214 in the circumferential direction. The distance between the electrode 212 and the electrode 214 is constant over the entire axial length of the substrate 111 and the like. Similarly, the distance between the electrode 212 and the electrode 216, that is, the distance between the outer peripheral surface of the electrode 212 and the inner peripheral surface of the electrode 216 is constant over the entire axial length of the electrode 216. Further, the distance between the electrode 212 and the electrode 216 is constant over the entire axial length of the substrate 111 and the like. The distance between the electrode 212 and the electrode 214 is larger than the distance between the electrode 212 and the electrode 116. That is, at any position in the axial direction of the substrate 111 or the like, the area of the gap between the electrode 212 and the electrode 214 in the cross section orthogonal to the axial direction of the substrate 111 or the like is larger than the area of the gap between the electrode 212 and the electrode 216. large.

  Note that the three electrodes 212, 214, and 216 are positioned so as to be relatively immovable by the support member 120.

  Two terminals 230 and 232 are connected to the lower end of the substrate 111. Each of the terminals 230 and 232 is connected to each of the electrodes 214 and 216 via a conductive wire on the substrate 111. A terminal 234 is connected to the lower end of the substrate 113. The terminal 234 is connected to the electrode 212 through a conductive wire on the substrate 113. Signals are alternately supplied to the electrodes 214 and 216 from the oscillation unit 52 via the terminals 230 and 232. The electrode 212 is grounded.

  With this configuration, the same effects as in the second embodiment can be obtained.

(Fourth embodiment)
The sensor system 2 includes a sensor device 300 of FIG. 8 instead of the sensor device 10 as compared with the first embodiment. The sensor device 300 includes three electrodes 312, 314, and 316 and a support member (not shown). The support member positions the three electrodes 312, 314, 316 so that the three electrodes 312, 314, 316 are relatively immovable.

  The electrode 312 includes three flat plates 312a to 312c. Each flat plate 312a-312c has a rectangular shape. In the modification, at least one of the three flat plates 312a to 312c may have another shape such as an ellipse, and the thickness may not be constant.

  The flat plates 312a, 312b, and 312c have the same shape. The flat plates 312a, 312b, and 312c are located at the same position in the vertical direction, that is, in the depth direction of the oil pan 4. The flat plates 312a and 312c are arranged in parallel with a space therebetween. The flat plates 312a and 312c are connected by a flat plate 312b. The flat plate 312b is orthogonal to the flat plates 312a and 312c. The flat plate 312b is coupled over the entire length of one side in the vertical direction of the flat plate 312a. The flat plate 312b is coupled over the entire length of one side of the flat plate 312c in the vertical direction.

  In the modification, the flat plate 312b may not be orthogonal to the flat plates 312a and 312c. Further, the flat plate 312b may not be rectangular, and may be a curved plate, for example. Further, the flat plate 312b may intermittently couple one side in the vertical direction of the flat plates 312a and 312c.

  Two electrodes 314 and 316 are disposed between the flat plate 312a and the flat plate 312c. The electrode 314 has a rectangular flat plate. The electrode 314 is disposed in parallel with the flat plates 312a and 312c. One side of the electrode 314 is disposed on the same plane as one side of the flat plates 312a and 312c, and the other side of the electrode 314 is opposed to the flat plate 312b with a gap. One surface of the electrode 314 is opposed to the flat plate 312a. The other surface of the electrode 314 is opposed to the flat plate 312c. One electrode pair 315 is configured by the portions of the electrode 312 and the electrode 314 facing each other. That is, the electrode pair 315 includes the electrodes 312 and 314.

  Below the electrode 314, an electrode 316 is disposed at a distance from the lower end of the electrode 314. The electrode 316 has a rectangular flat plate. The electrode 316 is disposed in parallel with the flat plates 312a and 312c. One side of the electrode 316 is disposed on the same plane as one side of the flat plates 312a and 312c, and the other side of the electrode 316 is opposed to the flat plate 312b with a gap. One surface of the electrode 316 is opposed to the flat plate 312a. The other surface of the electrode 316 is opposed to the flat plate 312c. The electrode 312 and the electrode 316 facing each other constitute one electrode pair 317. That is, the electrode pair 317 includes the electrodes 312 and 316.

  As shown in FIG. 9, the thickness of the electrode 316, that is, the length in the direction perpendicular to the flat plates 312a and 312c of the electrode 316 is the thickness of the electrode 314, that is, the length in the direction perpendicular to the flat plates 312a and 312c of the electrode 314. Bigger than that. The center of the electrode 316 in the thickness direction is located on the same plane as the center of the electrode 314 in the thickness direction. The centers of the electrodes 314 and 316 in the thickness direction are located at the centers of the gaps between the flat plates 312a and 312c. For this reason, the gap between the electrode 314 and the flat plate 312a is equal to the gap between the electrode 314 and the flat plate 312c. Similarly, the distance between the electrode 316 and the flat plate 312a is equal to the distance between the electrode 316 and the flat plate 312c. The distance between the electrode 314 and the flat plate 312a and the distance between the electrode 314 and the flat plate 312c are larger than the distance between the electrode 316 and the flat plate 312a and the distance between the electrode 316 and the flat plate 312c. Note that the distance between the flat plate 312b and the electrode 314 is equal to the distance between the flat plate 312b and the electrode 316. The area of the gap between the electrode 312 and the electrode 314 in the vertical direction of the electrodes 312, 314, 316, that is, in the cross section perpendicular to the depth direction of the oil pan 4 is at any position in the vertical direction of the electrodes 312, 314, 316. Is larger than the area of the gap between the electrode 312 and the electrode 316.

  Signals are alternately supplied to the electrodes 314 and 316 from the oscillating unit 52 via terminals (not shown). The electrode 312 is grounded.

  According to this configuration, the sensitivity of the sensor device in the electrode pair 317 can be increased as in the first to third embodiments. Further, the electrode pair 315 can suppress erroneous detection of the remaining amount of engine oil by suppressing the capillary wrinkle phenomenon. In the present embodiment, the respective electrodes 312, 314, 316 can be arranged at appropriate intervals according to the respective uses of the two electrode pairs 315, 317. As a result, the performance of the sensor system 2 can be improved by changing the gap between the electrodes.

  As mentioned above, although embodiment of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

(Modification)
(1) In the first embodiment, the electrode 12 and the like are cylindrical. However, the electrode 12 or the like may be a polygonal cylinder such as a rectangle or a hexagon in cross section, or may be an elliptical cylinder or the like. In addition, cuts such as openings and slits may be formed in a part of the electrode 12 and the like. Further, the thickness of the electrode 12 and the like may not be constant. The same applies to the substrate 111 and the like in the second and third embodiments.

(2) Moreover, the electrodes 14 and 16 etc. arrange | positioned inside the electrode 12 etc. do not need to be cylindrical. That is, the electrodes 14, 16 and the like may be solid, for example, cylindrical. The same applies to the substrate 113 and the like disposed inside the substrate 111 and the like in the second and third embodiments.

(3) In said 1st Example, the sensor apparatus 10 is provided with the three 1st-3rd electrodes 12-16. However, the number of electrodes provided in the sensor device 10 may be three or more. In this case, three or more electrode pairs may be provided. For example, the sensor device 10 may further include an electrode pair for specifying the temperature of the engine oil, that is, one or more electrodes. The same applies to the sensor device 100 and the like in the second and third embodiments.

(4) In the fourth embodiment, the sensor device 300 includes the electrodes 312, 314, and 316. However, as shown in FIG. 10, the sensor device 300 may include an electrode 412 instead of the electrode 312. The electrode 412 may be a rectangular flat plate arranged in parallel with the electrodes 314 and 316. In this case, the distance between the electrode 314 and the electrode 412 may be larger than the distance between the electrode 316 and the electrode 412. Note that the thickness of the electrode 316 may be equal to the thickness of the electrode 314. One electrode pair 415 may be configured by the portions of the electrode 412 and the electrode 314 facing each other. The electrode pair 415 may include electrodes 412 and 314. Similarly, one electrode pair 417 is configured by the portions of the electrode 412 and the electrode 316 facing each other. The electrode pair 417 may include electrodes 412 and 314.

(5) In each of the above embodiments, the sensor device 10 or the like is used to specify the remaining amount of engine oil in the oil pan 4. However, the sensor device disclosed in this specification may be used to specify the remaining amount of fuel in the fuel tank in which the fuel supplied to the internal combustion engine is stored, in addition to the remaining amount of engine oil. In general, the sensor device disclosed in the present specification can be used when the liquid level of the liquid in the container is to be specified.

(6) In each of the above embodiments, the distance between the two electrodes 12 and 14 facing each other is constant. However, the distance between the two electrodes 12 and 14 facing each other need not be constant. For example, the electrode 14 may have an elliptic cylinder shape. In this case, a part of the interval between the two electrodes 12 and 14 may be narrower than the interval between the two electrodes 12 and 16. Even in this case, the area of the gap between the electrode 12 and the electrode 14 is larger than the area of the gap between the electrode 12 and the electrode 16 when viewed in a cross section orthogonal to the depth direction of the oil pan 4. Each electrode 12 or the like may be formed.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: sensor system, 4: oil pan, 10: sensor device, 12, 14, 16: electrode, 15, 17: electrode pair, 20: support member, 50: control circuit, 300: sensor device, 312, 314, 316 : Electrode, 312a, 312b, 312c: flat plate, 315, 317: electrode pair

Claims (5)

A liquid level electrode pair for specifying the liquid level of the liquid in the container;
A liquid quality electrode pair for specifying the liquid quality of the liquid in the container,
The liquid level electrode pair includes a first electrode and a second electrode having a facing surface facing a part of the surface of the first electrode,
The liquid quality electrode pair includes a first electrode common to the liquid level electrode pair, and a third surface having a facing surface facing a portion of the surface of the first electrode not facing the second electrode. An electrode,
When viewed in a cross section perpendicular to the depth direction of the container, the area of the gap between the first electrode and the second electrode is larger than the area of the gap between the first electrode and the third electrode. apparatus. The first electrode includes a cylindrical first tube portion,
The second electrode includes a cylindrical second tube portion disposed on either the inside or the outside of the first tube portion,
2. The sensor device according to claim 1, wherein the third electrode includes a cylindrical third cylindrical portion disposed on either the inner side or the outer side of the first cylindrical portion.   The sensor device according to claim 2, wherein at least one of the first cylindrical portion, the second cylindrical portion, and the third cylindrical portion is made of a cylindrical conductive material.   At least one cylindrical portion of the first cylindrical portion, the second cylindrical portion, and the third cylindrical portion is made of a cylindrical substrate and a conductive material disposed on the substrate. Item 4. The sensor device according to Item 2 or 3. The first electrode is
A first flat plate;
A second flat plate arranged parallel to the first flat plate at a distance;
A connection plate connecting the first flat plate and the second flat plate,
The second electrode is
A third flat plate disposed between the first flat plate and the second flat plate;
The third electrode is
The sensor device according to claim 1, further comprising a fourth flat plate disposed between the first flat plate and the second flat plate and below the third flat plate.

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