Capacitive liquid sensor and method for mounting a capacitive liquid sensor

Abstract

A capacitive liquid sensor (10) includes a first frame (301) and a second frame (302) made of a metal material, and a plurality of first electrode plates (401) and second electrode plates (402) made of metal plates. The first frame and the second frame each have a through portion (31) through which the first electrode plate and the second electrode plate are passed, and are arranged to face each other. The first electrode plate and the second electrode plate have a detection part (41) and two fixing parts (42), are formed in a cross shape, and are alternately arranged facing each other. In the first electrode plate, the fixing part of the first electrode plate is fixed to the first frame in a state where the detection part of the first electrode plate is passed through the through portion of the first frame and the second frame. In the second electrode plate, the fixing part of the second electrode plate is fixed to the second frame in a state where the detection part of the second electrode plate is passed through the through portion of the second frame and the first frame.

Description

Technical Field

[0004] , , , , , , , ,

[0001] Embodiments of the present invention relate to a capacitive liquid sensor and a method for attaching a capacitive liquid sensor.

Background Art

[0002] Conventionally, as a means for detecting a non-conductive liquid such as lubricating oil, a capacitive liquid sensor has been proposed. The capacitive liquid sensor utilizes the fact that when a non-conductive liquid enters between electrodes fixed with a space therebetween, the capacitance between the electrodes changes, and detects the presence or absence of the liquid, the amount of the liquid, and the mixing ratio of the liquid. As a capacitive liquid sensor, for example, electrode plates are fixed to two conductive pins of an airtight terminal, and the change in the liquid level height in a container is detected from the change in the capacitance between the electrode plates. Such a liquid sensor is attached, for example, at a position where the entire electrode is normally located in the liquid and the electrode is exposed into the gas when the liquid level drops. Then, the liquid sensor detects the change in the liquid level due to the difference in the dielectric constant between the liquid and the gas.

[0003] However, in the conventional capacitive liquid sensor, the change in capacitance obtained from the presence or absence of the liquid between the electrodes is small, and it has been difficult to accurately determine the state of the liquid from the change in capacitance. In this case, by increasing the area of the electrode or reducing the distance between the electrodes, the change in capacitance caused by the change in the state of the liquid can be increased. Therefore, a technique for obtaining a large capacitance by laminating a plurality of electrodes at a narrow interval has been considered.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when multiple electrodes are placed at close intervals, if the support for each electrode is weak, the relative positions of the electrodes can easily change when subjected to external forces, negatively affecting the detection characteristics of the liquid sensor. Furthermore, when the electrodes are placed close together, when each electrode is exposed from the liquid to the gas, droplets or bubbles that have entered between the electrodes are difficult to expel due to the effects of surface tension, etc. As a result, the liquid sensor has a problem in that it cannot respond immediately to changes in the gas-liquid state around the electrodes.

[0006] This embodiment has been made in view of the above circumstances, and its purpose is to provide a capacitive liquid sensor that can detect changes in the state of a liquid with high sensitivity by improving the support strength of the electrodes and improving the discharge of droplets and bubbles between the electrodes in a device equipped with multiple electrodes. [Means for solving the problem]

[0007] The capacitive liquid sensor according to this embodiment includes a base member, first conductive terminal pins and second conductive terminal pins that are passed through the base member and fixed to the base member via an electrically insulating filler, and are electrically insulated from each other, a first frame made of a metal material and electrically connected to the first conductive terminal pins, a second frame made of a metal material and electrically connected to the second conductive terminal pins, a plurality of first electrode plates made of a metal plate and connected and fixed to the first frame, and a plurality of second electrode plates made of a metal plate and connected and fixed to the second frame. The first frame and the second frame each have through portions for passing the first electrode plates and the second electrode plates, and are arranged facing each other. The first electrode plates and the second electrode plates each have a detection portion and two fixing portions extending from both edges of the detection portion, and are formed in a cross shape where the longitudinal direction of the detection portion and the protruding direction of the fixing portions intersect, and are arranged alternately facing each other. The first electrode plate is fixed to the first frame with its fixing portion, while the detection portion of the first electrode plate is passed through the through portion of the first frame and the second frame. The second electrode plate is fixed to the second frame with its fixing portion, while the detection portion of the second electrode plate is passed through the through portion of the second frame and the first frame.

[0008] Furthermore, the method for mounting a capacitive liquid sensor according to the embodiment includes the step of mounting the capacitive liquid sensor to the object to be mounted in a position in which the surface direction of the first frame and the second frame is vertical, and the surface direction of the first electrode plate and the second electrode plate is vertical. [Brief explanation of the drawing]

[0009] [Figure 1] A perspective view showing the appearance of an example of a capacitive liquid sensor according to one embodiment. [Figure 2] A perspective view showing an example of a capacitive liquid sensor according to one embodiment, with each component disassembled. [Figure 3] An example of a capacitive liquid sensor according to one embodiment is shown in Figure 1, viewed from the X3 direction. [Figure 4] A cross-sectional view of an example of a capacitive liquid sensor according to one embodiment is shown along the line X4-X4 in Figure 3. [Figure 5] A cross-sectional view of an example of a capacitive liquid sensor according to one embodiment, shown along the line X5-X5 in Figure 3. [Figure 6] A cross-sectional view of an example of a capacitive liquid sensor according to one embodiment, shown along the line X6-X6 in Figure 3. [Figure 7] A cross-sectional view of an example of a capacitive liquid sensor according to one embodiment, shown along the line X7-X7 in Figure 3. [Figure 8] This figure shows an example of an electrode plate for an example of a capacitive liquid sensor according to one embodiment. [Figure 9] An example of a capacitive liquid sensor according to one embodiment is shown in an enlarged view of the portion indicated by X9 in Figure 4. [Figure 10] This figure shows a first example of the use of a capacitive liquid sensor according to one embodiment. [Figure 11] This figure shows a second example of use of a capacitive liquid sensor according to one embodiment. [Figure 12] This diagram conceptually shows the positional relationship between the first electrode plate and the second electrode plate in a capacitive liquid sensor according to one embodiment. [Modes for carrying out the invention]

[0010] The following describes a capacitive liquid sensor according to one embodiment, and a method for mounting the capacitive liquid sensor, with reference to the drawings. In the following description, the capacitive liquid sensor may be simply referred to as the liquid sensor.

[0011] The liquid sensor 10 shown in FIG. 1 is attached to a container filled with an electrically insulating liquid, such as a container of a compressor, and is used to detect the state of the electrically insulating liquid present in the container, that is, to detect the liquid level height and mixing ratio of the lubricating oil and liquid refrigerant in the container. As shown in FIGS. 1 to 4, the liquid sensor 10 includes two connection members 11, a base member 21, two conductive terminal pins 22, a filler 23, two frame bodies 30, a plurality of electrode plates 40, and two spacers 50.

[0012] The base member 21, the conductive terminal pins 22, and the filler 23 constitute an airtight terminal 12. The airtight terminal 12 is a structure for attaching the liquid sensor 10 to a container of a compressor or the like. The frame body 30, the electrode plates 40, and the spacers 50 constitute a detection unit 13. The detection unit 13 is a structure for detecting the state of an electrically insulating liquid such as the lubricating oil and liquid refrigerant of the compressor. And the connection member 11 is a structure for electrically and physically connecting each conductive terminal pin 22 and the frame body 30.

[0013] In the case of this embodiment, the two connection members 11 have different specific structures. Among the two connection members 11, one connection member 111 has a thicker plate thickness and higher rigidity, that is, a structure that is difficult to deform compared to the other connection member 112. In other words, the other connection member 112 has a thinner plate thickness and elasticity, that is, a structure that is easy to deform compared to the above-mentioned one connection member 111.

[0014] In the following description, among the two connection members 111 and 112, the one with higher rigidity may be referred to as the first connection member 111, and the one that is easy to deform may be referred to as the second connection member 112. In this specification, the first and second terms are for conveniently distinguishing configurations with common functions and do not indicate the order or superiority / inferiority of the configurations.

[0015] As shown in FIG. 5, the second connecting member 112 can be configured to have a structure that is more easily elastically deformed by, for example, greatly bypassing the L-shaped bent portion to extend the overall length. Thereby, the first frame body 301 can be firmly fixed by the first connecting member 111 with high rigidity, and the second connecting member 112 with high elasticity can elastically absorb the strain and dimensional changes generated during welding or the like. As a result, deformation of the frame body 30 and the electrode plate 40 due to assembly errors, stress during handling, etc. can be suppressed, and variations in the characteristics of the liquid sensor 10 can be suppressed.

[0016] The base member 21 is made of a metal material and is formed in a shallow cup shape. The conductive terminal pin 22 is made of a member having conductivity such as metal, and is formed, for example, in a cylindrical rod shape. As shown in FIG. 4, the two conductive terminal pins 22 are respectively passed through the hole portions 211 formed at the bottom of the base member 21. The filling material 23 is made of a material having electrical insulation such as glass, and can also be referred to as an insulating member. The filling material 23 is filled between the inside of the hole portion 211 and the conductive terminal pin 22, electrically insulates the conductive terminal pin 22 and the base member 21, and fixes the conductive terminal pin 22 to the base member 21. Thereby, the two conductive terminal pins 22 are fixed to the base member 21 in a state of being electrically insulated from the base member 21 respectively and in an airtight and watertight state.

[0017] The two conductive terminal pins 22 are electrically insulated from each other. The two conductive terminal pins 22 are arranged in parallel with each other and extend in the depth direction of the base member 21. The detection unit 13 is connected to one end side of the two conductive terminal pins 22. The detection unit 13 is located on the inner side of the container when the liquid sensor 10 is attached to a container of a compressor or the like. The other end side of the two conductive terminal pins 22 is located on the outer side of the container when the liquid sensor 10 is attached to a container of a compressor or the like. In the following description, when distinguishing the two conductive terminal pins 22, one may be referred to as the first conductive terminal pin 221 and the other may be referred to as the second conductive terminal pin 222.

[0018] The frame 30 is made of a conductive metal material and is electrically connected to the conductive terminal pins 22. In the following description, when distinguishing between the two frame 30s, the one connected to the first conductive terminal pin 221 may be referred to as the first frame 301, and the one connected to the second conductive terminal pin 222 may be referred to as the second frame 302. The first frame 301 and the second frame 302 are formed in the same shape. The frame 30 is formed in the shape of a rectangular frame, with a rectangular hole formed in the center of a rectangular metal plate as a whole. The frame 30 is elongated in the longitudinal direction of the conductive terminal pins 22 and is formed in the shape of a roughly rectangular frame as a whole. The two frame 30s are arranged facing each other at a predetermined distance apart. In this case, the plane direction of the frame 30 coincides with the longitudinal direction of the conductive terminal pins 22.

[0019] As shown in Figures 2, 3, 6, and 7, the frame 30 has a through portion 31, a protruding portion 32, and a defined portion 33. The through portion 31 is formed in the shape of a rectangular hole and has the function of passing a portion of the multiple electrode plates 40 through. The protruding portion 32 is provided on both edges of the frame 30 that extend in the longitudinal direction, i.e., on both long sides, and is formed in a shape that protrudes toward the opposite side from the opposing frame 30. The protruding portion 32 is formed to be long and continuous in the longitudinal direction of the frame 30. The length dimension of the protruding portion 32 is set to be greater than or equal to the length dimension of the through portion 31 in the longitudinal direction.

[0020] As shown in Figure 2, the defining portion 33 is provided on both sides of the frame 30 that extend in the width direction, i.e., on both short sides, and protrudes outward on both sides in the longitudinal direction of the frame 30. In this specification, when a certain configuration is referred to as the width direction, the width direction means the direction perpendicular to the longitudinal direction of that configuration. The defining portion 33 is inserted into the spacer 50 and has the function of defining the distance to the opposing frame 30, that is, the function of maintaining a constant distance to the opposing frame 30. The frame 30 is formed by, for example, press-forming a metal plate, in which the through portion 31, the protruding portion 32, and the defining portion 33 are integrally formed.

[0021] The spacer 50 is configured in a rectangular block or container shape and has two insertion parts 51. The two insertion parts 51 are, for example, elongated rectangular or elongated hole shapes extending in the width direction of the frame 30 and are arranged parallel to each other. The defined part 33 of the frame 30 is inserted into and held in the insertion parts 51. This defines the positional relationship between the two frame bodies 30. Preferably, the spacer 50 is made of an electrically insulating material such as resin or ceramic that does not change shape or deteriorate in the operating environment of the liquid sensor 10. In this embodiment, a total of two spacers 50 are provided, one at each end of the frame body 30, but it is also acceptable to provide the spacer 50 only on one end of the frame body 30, as long as it can define the positional relationship between the two frame bodies 30. The spacer 50 may also be provided in the defined part 33 by insert molding.

[0022] The frame 30 is electrically and physically connected to the conductive terminal pins 22 via the connecting member 11. The connecting member 11 is made of, for example, a metal plate bent into a roughly L-shape. One end of the connecting member 11 is fixed to the frame 30 by, for example, welding or brazing, and the other end is connected to the conductive terminal pins 22 by, for example, welding or brazing.

[0023] The electrode plate 40 is made of a thin conductive plate material such as a metal plate, and is provided on the frame 30. It is electrically connected to the conductive terminal pin 22 via the frame 30 and the connecting member 11. In the following description, the electrode plate 40 provided on the first frame 301 may be referred to as the first electrode plate 401, and the electrode plate 40 provided on the second frame 302 may be referred to as the second electrode plate 402. The first electrode plate 401 and the second electrode plate 402 face each other without contact and are arranged alternately in the longitudinal direction of the frame 30, that is, in the longitudinal direction of the conductive terminal pin 22. That is, the surfaces of each electrode plate 40 are arranged perpendicular to the extending direction of the conductive terminal pin 22.

[0024] The first electrode plate 401 and the second electrode plate 402 are formed to the same shape. As shown in Figures 6 to 8, the electrode plate 40 has a detection section 41 and two fixing sections 42. The detection section 41 is the area indicated by the dashed diagonal line in Figure 8, and the fixing sections 42 are the areas indicated by the solid shaded line. The detection section 41 occupies most of the electrode plate 40 and is the part that faces the other adjacent electrode plate 40. That is, the detection section 41 is the area that overlaps with the adjacent first electrode plate 401 and second electrode plate 402. The detection section 41 is formed, for example, in a long rectangular or substantially rectangular shape in the direction in which the two frame bodies 30 are lined up.

[0025] The fixing portion 42 is the portion that extends from both edges of the detection portion 41, i.e., both ends of the long side portion. The fixing portion 42 extends in a direction perpendicular to the longitudinal direction of the detection portion 41. In this embodiment, the fixing portion 42 is a region that does not overlap with the adjacent first electrode plate 401 and second electrode plate 402. The fixing portion 42 is provided not at the end of the detection portion 41 in the longitudinal direction, but in the middle of the longitudinal direction. The fixing portion 42 is provided at a position offset to one side from the longitudinal center O of the detection portion 41.

[0026] Furthermore, the electrode plate 40 is formed in a cross shape where the longitudinal direction of the detection unit 41 and the protruding direction of the fixing unit 42 intersect. The outer edge 411 of the detection unit 41 and the outer edge 421 of the fixing unit 42 of the electrode plate 40 are formed by the same circular arc, that is, by the same radius. The electrode plate 40 is formed integrally with the detection unit 41 and the fixing unit 42 by, for example, punching out a thin circular plate using a press.

[0027] Here, it is assumed that the outer edge 411 of the detection unit 41 and the outer edge 421 of the fixing unit 42 are formed by the arc of a circle with radius R centered at center O. Center O is the center of the detection unit 41 in both its longitudinal and widthwise directions. In this case, the widthwise dimension A of the detection unit 41 is set to a value greater than the radius R, and the widthwise dimension B of the fixing unit 42 is set to a value less than the radius R. Preferably, the width dimension A of the detection unit 41 is within the range of 1.2 to 1.3 times the radius R, and the width dimension B of the fixing unit 42 is within the range of 1 / 4 to 1 / 3 of the radius R.

[0028] The detection unit 41 has a relief portion 412. The relief portion 412 is provided on the long sides of the detection unit 41 and is formed in a shape in which a part of the long side is recessed or cut out. The relief portion 412 has the function of preventing contact between the electrode plate 40 and the frame 30 to which the electrode plate 40 is not connected. That is, as shown in Figure 6, the relief portion 412 of the first electrode plate 401 has the function of preventing contact with the second frame 302. Also, as shown in Figure 7, the relief portion 412 of the second electrode plate 402 has the function of preventing contact with the first frame 301.

[0029] When attaching each electrode plate 40 to the frame 30, the portion of the detection section 41 on the side of the center O closer to the fixing section 42 of each electrode plate 40 is passed through the through section 31 from the side of the protruding section 32 of the frame 30. The electrode plate 40 and the frame 30 are then connected and fixed by methods such as projection welding, spot welding, or seam welding at the point where the fixing section 42 of the electrode plate 40 and the frame 30 come into contact. This welds and fixes the fixing section 42 to the frame 30. Brazing or other methods may also be used to connect and fix the electrode plate 40 and the frame 30. In addition, the fixing section 42 of the electrode plate 40 and the frame 30 may be provided with, for example, protrusions and indentations for positioning.

[0030] As shown in Figures 1, 3, 4, and 9, the first electrode plate 401 and the second electrode plate 402 are arranged alternately at equal intervals. Also, as shown in Figure 9, the distance L1 between the first frame 301 and the second frame 302 is set to a value greater than the distance L2 between adjacent first electrode plates 401 and second electrode plates 402. In other words, the distance L2 between adjacent first electrode plates 401 and second electrode plates 402, i.e., between their surfaces, is set to a value less than the distance L1 between first frame 301 and second frame 302, i.e., between their surfaces. Furthermore, the thickness dimension T1 of the first frame 301 and the second frame 302 is set to be greater than the thickness dimension T2 of the first electrode plate 401 and the second electrode plate 402. In this case, the distance between the centers of the first electrode plate 401 and the second electrode plate 402, taking into account their thicknesses, is L2 + T2.

[0031] When the liquid sensor 10 is used to detect, for example, refrigerant oil or refrigerant present inside a compressor, it is preferable to set the distance L2 between adjacent first electrode plates 401 and second electrode plates 402 to within a range of, for example, 1 mm to 1.8 mm. This allows for obtaining the capacitance necessary for liquid detection and improves the drainage between electrode plates 401 and 402. Furthermore, it is preferable to set the distance L1 between frames 301 and 302 to within a range of, for example, 2 mm to 3 mm. This prevents droplets and bubbles discharged from electrode plates 401 and 402 towards the frame 30 from remaining between the two frames 30 due to surface tension and other factors. As a result, the drainage in the detection unit 13 is improved, and the responsiveness of the liquid sensor 10 can be enhanced.

[0032] Each electrode plate 40 is fixed to one of the two frames 30 and passed through the through portion 31 of the other frame 30 in a manner that it does not come into contact with the other frame 30 or the electrode plate 40 fixed to the other frame 30. That is, the first electrode plate 401 is fixed to the first frame 301 and passed through the through portion 31 of the second frame 302 in a manner that it does not come into contact with the second frame 302 or the second electrode plate 402. Similarly, the second electrode plate 402 is fixed to the second frame 302 and passed through the through portion 31 of the first frame 301 in a manner that it does not come into contact with the first frame 301 or the first electrode plate 401.

[0033] The first electrode plates 401 and the second electrode plates 402 can be configured in the same number, or they can be configured in different numbers. In this embodiment, the number of first electrode plates 401 is set to be one more than the number of second electrode plates 402. For example, in this embodiment, as shown in Figure 2, the number of first electrode plates 401 is set to 6, while the number of second electrode plates 402 is set to 5. In the arrangement of the first electrode plates 401 and the second electrode plates 402, the first electrode plates 401 are arranged at both ends.

[0034] Next, with reference to Figures 10 and 11, examples of mounting the liquid sensor 10 to the mounting target will be described. The liquid sensor 10 is used by being mounted on, for example, the container 80 of a compressor. In the example in Figure 10, the liquid sensor 10 is directly mounted on the peripheral wall of the container 80. In the example in Figure 11, the liquid sensor 10 is mounted on the flange portion 81 of the container 80. The flange portion 81 is provided on the peripheral wall of the container 80 and is formed in a cylindrical shape that protrudes outward from the peripheral wall of the container 80. In the example in Figure 11, the liquid sensor 10 is mounted on the flange portion 81 via a flange cover 82.

[0035] When attaching the liquid sensor 10 to the container 80, the worker attaches the liquid sensor 10 in a position where the surfaces of the first frame 301 and the second frame 302 face vertically, and the surfaces of the first electrode plate 401 and the second electrode plate 402 face vertically. That is, the worker attaches the liquid sensor 10 to the container 80 in a position where arrow D in Figure 1 is vertical. In this case, the two frames 301 and 302 are aligned horizontally, and the gap between the two frames 301 and 302 is open vertically. Also, the two conductive terminal pins 221 and 222 are aligned horizontally. When attaching the liquid sensor 10 to the container 80, the worker can adjust the position of the liquid sensor 10 by, for example, observing the arrangement of the two conductive terminal pins 221 and 222 so that the two conductive terminal pins 221 and 222 are aligned horizontally.

[0036] A signal processing circuit (not shown) is connected to the portion of the conductive terminal pin 22 that is exposed to the outside of the container 80, either via an electric wire (not shown) or directly. The signal processing circuit determines the state of the liquid based on the change in capacitance of the detection unit 13 and outputs a signal corresponding to that state. The signal output from the signal processing circuit is then transmitted to a control device, for example, a compressor to which the liquid sensor 10 is attached, and the control device controls the operation of the compressor according to the state of the liquid based on the signal output from the signal processing circuit.

[0037] According to the embodiment described above, the liquid sensor 10 comprises a base member 21, a first conductive terminal pin 221, a second conductive terminal pin 222, a first frame 301, a second frame 302, a plurality of first electrode plates 401, and a plurality of second electrode plates 402. The first conductive terminal pin 221 and the second conductive terminal pin 222 are passed through the base member 21 and fixed to the base member 21 via an electrically insulating filler 23. The first conductive terminal pin 221 and the second conductive terminal pin 222 are electrically insulated from each other.

[0038] The first frame 301 is made of a metal material and is electrically connected to the first conductive terminal pin 221. The second frame 302 is made of a metal material and is electrically connected to the second conductive terminal pin 222. Multiple first electrode plates 401 are made of metal plates and are connected and fixed to the first frame 301. Multiple second electrode plates 402 are made of metal plates and are connected and fixed to the second frame 302. That is, each first electrode plate 401 and each second electrode plate 402 are electrically connected to and physically fixed to the first frame 301 or the second frame 302, respectively, by welding, brazing, etc.

[0039] The first frame 301 and the second frame 302 each have a through portion 31 through which the first electrode plate 401 and the second electrode plate 402 pass, and are arranged facing each other. The first electrode plate 401 and the second electrode plate 402 each have a detection portion 41 and two fixing portions 42 extending from both edges of the detection portion 41. The first electrode plate 401 and the second electrode plate 402 are formed in a cross shape where the longitudinal direction of the detection portion 41 and the protruding direction of the fixing portion 42 intersect. The first frame 301 and the second frame 302 are arranged alternately facing each other.

[0040] The first electrode plate 401 has its detection portion 41 passed through the through portion 31 of the first frame 301 and the second frame 302, and its fixing portion 42 is fixed to the first frame 301. The second electrode plate 402 has its detection portion 41 passed through the through portion 31 of the second frame 302 and the first frame 301, and its fixing portion 42 is fixed to the second frame 302. In this case, the fixing portions 42 of the first electrode plate 401 and the second electrode plate 402 are connected and fixed to the edges of the first frame 301 or the second frame 302 around the through portion 31, specifically to the edges of the first frame 301 or the second frame that extend in the longitudinal direction, by welding, brazing, or the like.

[0041] According to this, the liquid sensor 10 can increase its capacitance by having multiple electrode plates 40, and as a result, the sensitivity of the liquid sensor 10 can be increased. Furthermore, each electrode plate 40 is connected and fixed to the frame 30 not at the longitudinal end of the detection unit 41, but by two fixing parts 42 that extend in a cross shape from both edges of the detection unit 41 relative to the detection unit 41. Therefore, the distance from the fixing part to the end of each electrode plate 40 can be shortened compared to when each electrode plate 40 is supported at the longitudinal end of the detection unit 41, and as a result, the effects of deflection due to external forces can be reduced. This suppresses changes in the distance between the electrode plates 40, and as a result, the performance of the liquid sensor 10 can be made more stable.

[0042] Furthermore, since the fixing portion 42 extends outward from both edges of the detection portion 41, tools and the like are less likely to interfere with the detection portion 41 during welding work between the fixing portion 42 and the frame 30, thus enabling reliable work with a simple device.

[0043] Furthermore, the method for attaching the liquid sensor 10 of this embodiment to the container 80 includes the step of attaching it to the container 80 or other mounting target in a position where the plane direction of the two frame bodies 30 is vertical and the plane direction of the detection portion 41 of each electrode plate 40 is vertical.

[0044] By attaching the liquid sensor 10 of this embodiment to a container 80 or the like as described above, when the liquid level in the container 80 changes and the detection unit 13 moves from liquid to gas, or from gas to liquid, the liquid between the electrode plates 40 can be made to flow along the surface of the electrode plates 40 due to the influence of the liquid flow around the detection unit 13 and gravity. This makes it easier to discharge droplets and bubbles adhering to the electrode plates 40 from between the electrode plates 40. As a result, a liquid sensor 10 capable of accurately detecting changes in the liquid level can be provided.

[0045] Furthermore, each electrode plate 40 is fixed to the frame 30 with the detection unit 41 passing through the through-part 31 of the frame 30. That is, a part of the detection unit 41 is surrounded by the frame 30. When the liquid sensor 10 is mounted on a container 80 or the like in a position where the planes of the two frame bodies 30 are vertical and the plane of the detection unit 41 of each electrode plate 40 is vertical, there is a contact area between the fixing part 42 of the electrode plate 40 and the frame 30 below the electrode plate 40 in the direction of gravity. Therefore, when the detection unit 13 is exposed to liquid, droplets and bubbles attached to the electrode plate 40 will travel along the surface of the electrode plate 40 and collect downward in the direction of gravity, and then flow from the contact area between the fixing part 42 and the frame 30 to the frame 30. As a result, droplets and bubbles attached to the electrode plate 40 can be quickly discharged from between the electrode plates 40, and as a result, the detection accuracy and response speed of the liquid sensor 10 can be further improved.

[0046] The electrode plate 40 is formed by the outer edge 411 of the detection unit 41 and the outer edge 421 of the fixing unit 42 being part of a circular arc, in this case, a part of a circular arc with radius R. That is, the outer periphery of the electrode plate 40 is composed of a part of a circular arc with the same radius R. This allows for a larger area of ​​the detection unit 41 and the fixing unit 42 within the contour of the cylindrical space when the detection unit 13 is placed in a cylindrical space. By securing a larger area for the detection unit 41, a large capacitance can be obtained. Furthermore, by securing a larger area for the fixing unit 42, the rigidity of the fixing unit 42 can be improved, thereby suppressing changes in the distance between the electrode plates 40. As a result, according to this embodiment, the performance of the liquid sensor 10 can be further improved.

[0047] As shown in Figure 9, the distance L1 between the first frame 301 and the second frame 302 is greater than the distance L2 between the adjacent first electrode plate 401 and the second electrode plate 402. This prevents liquid that has moved from between the first electrode plate 401 and the second electrode plate 402 towards the frame 30 from remaining in the gap between the two frames 30 due to the effects of surface tension, etc. This further effectively suppresses the accumulation of droplets and bubbles between the frame 30 and the electrode plates 40. As a result, the liquid sensor 10 can quickly detect changes in the liquid level and further improve its responsiveness.

[0048] The thickness dimension T1 of the first frame 301 and the second frame 302 is set to be greater than the thickness dimension T2 of the first electrode plate 401 and the second electrode plate 402. This makes the first frame 301 and the second frame 302 thicker and more rigid than the first electrode plate 401 and the second electrode plate 402. As a result, even when multiple electrode plates 40 are arranged closely together, the frame 30 is prevented from bending due to the weight of each electrode plate 40, and each electrode plate 40 can be securely held. This prevents the position of the electrode plates 40 from changing due to deformation of the frame 30, and as a result, the sensitivity and reliability of the liquid sensor 10 can be further improved.

[0049] In this embodiment, the number of electrode plates 401 connected and fixed to one frame 301 is set to be one more than the number of electrode plates 402 connected and fixed to the other frame 302, and in the arrangement of the electrode plates 40, one extra electrode plate 401 is arranged at both ends. That is, in each electrode plate 40, the number of electrode plates 401 constituting one pole is set to be one more than the number of electrode plates 402 constituting the other pole. Furthermore, in each electrode plate 40 arranged alternately in the longitudinal direction, electrode plates 401 of the same pole are arranged at both ends. In this embodiment, the number of first electrode plates 401 is set to be one more than the number of second electrode plates 402, and in the arrangement of the first electrode plates 401 and second electrode plates 402, the first electrode plates 401 are arranged at both ends.

[0050] According to this, when constructing a detection unit 13 by combining the first frame 301 to which the first electrode plate 401 is fixed and the second frame 302 to which the second electrode plate 402 is fixed, it is possible to suppress variations in characteristics due to misalignment of the positional relationship with respect to the longitudinal direction of the detection unit 13, that is, the direction in which each electrode plate 40 is aligned. In other words, when considering the combination of opposing surfaces of the first electrode plate 401 and the second electrode plate 402, by making the electrode plates at both ends the same polarity, it is possible to match the number of combinations in which they move closer to each other, i.e., combinations in which capacitance increases, with the number of combinations in which they move further apart, i.e., combinations in which capacitance decreases.

[0051] For example, as shown in Figure 12, if the second frame 302 on which the second electrode plate 402 is provided is shifted relative to the first frame 301 on which the first electrode plate 401 is provided in the direction indicated by the white arrow, i.e., to the right on the paper, the distance indicated by arrow X becomes smaller and the distance indicated by arrow Y becomes larger. In this case, the capacitance between adjacent electrode plates 401 and 402 that are separated by the distance indicated by arrow X increases, and the capacitance between adjacent electrode plates that are separated by the distance indicated by arrow Y decreases.

[0052] In this configuration, where the first electrode plates 401 and the second electrode plates 402 are arranged alternately, if the number of first electrode plates 401 and second electrode plates 402 is equal, then the first electrode plates 401 will be placed at one end and the second electrode plates 402 will be placed at the other end. In this case, the number of arrows X and Y shown in Figure 12 will be different. Consequently, if the positional relationship between the first frame 301 on which the first electrode plates 401 are provided and the second frame 302 on which the second electrode plates 402 are provided shifts, the total capacitance of the entire detection unit 13 will also change.

[0053] In contrast, if electrode plates 40 of the same polarity are arranged at both ends, the number of arrows X and Y will be the same, so the change in the total capacitance of the entire detection unit 13 will be small. Therefore, according to this embodiment, even if there is a shift in the positional relationship, i.e., distance or tilt, of each electrode plate 40 with respect to the direction of arrangement, it is possible to suppress a change in the total capacitance of the entire detection unit 13. As a result, according to this embodiment, it is possible to suppress variations in characteristics due to positional shifts during assembly, etc.

[0054] (modified version) The distance L1 between the two frames 30, the spacing L2 between each electrode plate 40, and the number and size of each electrode plate 40 are not limited to those described above, and can be adjusted as appropriate depending on the properties of the liquid to be detected and the required sensitivity. In the above example, a metal plate was used as the connecting member 11 that connects the conductive terminal pin 22 and the frame 30. However, if the detection unit 13 is fixed using a member other than the connecting member 11, the connecting member 11 may be made of, for example, a flexible wire or a plastically deformable member. Furthermore, the liquid sensor 10 of this embodiment is not limited to detecting the liquid level of lubricating oil or liquid refrigerant by arranging the detection unit 13 near the gas-liquid interface inside the compressor. For example, the detection unit 13 can always be placed in a gas or liquid to detect phenomena that cause a change in dielectric constant between the electrode plates 40, such as detecting the mixing ratio of lubricating oil and liquid refrigerant.

[0055] Furthermore, the airtight terminal 12 and the detection unit 13 may be configured to be detachable. For example, if the space available for mounting the liquid sensor 10 is limited, it may be preferable to attach the airtight terminal 12 to the wall of the container beforehand, and then attach the detection unit 13. In such cases, the airtight terminal 12 and the detection unit 13 may be configured to be detachable, that is, the conductive terminal pin 22 and the frame 30 may be configured to be detachable.

[0056] The embodiment described above is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

Claims

1. Base member and A first conductive terminal pin and a second conductive terminal pin are passed through the base member, fixed to the base member via an electrically insulating filler, and electrically insulated from each other. A first frame made of a metal material and electrically connected to the first conductive terminal pin, A second frame made of a metal material and electrically connected to the second conductive terminal pin, A plurality of first electrode plates, made of metal plates and connected and fixed to the first frame, A plurality of second electrode plates, made of metal plates and connected and fixed to the second frame, Equipped with, The first frame and the second frame each have a passage for the first electrode plate and the second electrode plate, and are arranged facing each other. The first electrode plate and the second electrode plate each have a detection portion and two fixing portions extending from both edges of the detection portion, and are formed in a cross shape where the longitudinal direction of the detection portion and the protruding direction of the fixing portions intersect, and are arranged alternately facing each other. The first electrode plate is fixed to the first frame with the fixing portion of the first electrode plate while the detection portion of the first electrode plate is passed through the through portion of the first frame and the second frame. The second electrode plate is fixed to the second frame with the fixing portion of the second electrode plate fixed to the second frame, with the detection portion of the second electrode plate passing through the through portion of the second frame and the first frame. Capacitive liquid sensor.

2. The first electrode plate and the second electrode plate are formed by the same circular arc at the outer edge of the detection portion and the outer edge of the fixing portion. The capacitive liquid sensor according to claim 1.

3. The distance between the first frame and the second frame is greater than the distance between adjacent first electrode plates and second electrode plates. The capacitive liquid sensor according to claim 1.

4. The thickness dimensions of the first frame and the second frame are set to be greater than the thickness dimensions of the first electrode plate and the second electrode plate. The capacitive liquid sensor according to claim 1.

5. The number of electrode plates connected and fixed to one frame of the first electrode plate and the second electrode plate is set to be one more than the number of electrode plates connected and fixed to the other frame, and the portions at both ends of the arrangement of the first electrode plate and the second electrode plate are arranged with one more electrode plate. The capacitive liquid sensor according to claim 1.

6. A mounting method for attaching the capacitive liquid sensor described in claim 1 to an object to be mounted, The process includes mounting the capacitive liquid sensor to the object to be mounted in a position in which the surface directions of the first frame and the second frame are vertical, and the surface directions of the first electrode plate and the second electrode plate are vertical. Installation method for capacitive liquid sensors.

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