Capacitive liquid sensor and method of mounting a capacitive liquid sensor

Abstract

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

Description

Technical Field

[0001] The embodiments of the present invention relate to a capacitive liquid sensor and a method for installing the capacitive liquid sensor. Background Technology

[0002] Previously, capacitive liquid sensors have been proposed as a means of detecting non-conductive liquids such as lubricating oil. Capacitive liquid sensors utilize the principle that the capacitance between electrodes changes when a non-conductive liquid enters a spaced area, thereby detecting the presence or absence of liquid, the amount of liquid, and the mixing ratio of the liquid. As a capacitive liquid sensor, for example, electrode plates are fixed to two conductive pins at an airtight terminal, and changes in the liquid level in the container are detected based on the change in capacitance between the electrode plates. Such a liquid sensor is installed, for example, in a position where the electrodes are normally submerged in the liquid, but exposed to gas when the liquid level drops. Then, the liquid sensor detects the change in liquid level by utilizing the difference in dielectric constants between the liquid and the gas.

[0003] However, in conventional capacitive liquid sensors, the change in capacitance obtained by the presence or absence of liquid between the electrodes is minimal, making it difficult to accurately determine the state of the liquid based on this capacitance change. In this case, increasing the electrode area or narrowing the spacing between the electrodes can increase the change in capacitance caused by changes in the state of the liquid. Therefore, a technique to obtain a large capacitance by stacking multiple electrodes with narrow spacing is being considered.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-92491;

[0007] Patent Document 2: Japanese Patent Application Publication No. 09-096618. Summary of the Invention

[0008] The problem the invention aims to solve

[0009] However, when multiple electrodes are arranged with narrow spacing, if the support of each electrode is weak, the positional relationship between the electrodes is prone to change when the electrodes are subjected to external forces, which adversely affects the detection characteristics of the liquid sensor. Furthermore, if the spacing between the electrodes is narrowed, when each electrode is exposed from the liquid to the gas, droplets and bubbles that have entered between the electrodes are difficult to expel due to surface tension and other factors. Thus, the liquid sensor suffers from the problem that it cannot immediately respond to changes in the gas-liquid state surrounding the electrodes.

[0010] This embodiment was made in view of the above situation, and its purpose is to provide a capacitive liquid sensor that can detect changes in the state of 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 capacitive liquid sensor having multiple electrodes.

[0011] Solution for solving the problem

[0012] The capacitive liquid sensor of this embodiment includes: a base member; a first conductive terminal pin and a second conductive terminal pin, which pass through the base member, are fixed to the base member via an electrically insulating filler material, and are electrically insulated from each other; a first frame made of metal and electrically connected to the first conductive terminal pin; a second frame made of metal and electrically connected to the second conductive terminal pin; a plurality of first electrode plates made of metal and fixed to the first frame; and a plurality of second electrode plates made of metal and fixed to the second frame. The first frame and the second frame each have a through-portion through which the first electrode plate and the second electrode plate pass, 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 two edges of the detection portion, formed in a cross shape where the length direction of the detection portion intersects the protruding direction of the fixing portions, and are arranged facing each other alternately. In the first electrode plate, when the detection portion of the first electrode plate passes through the through-portions of the first frame and the second frame, the fixing portion of the first electrode plate is fixed to the first frame. In the second electrode plate, with the detection part of the second electrode plate passing through the through part of the second frame and the first frame, the fixing part of the second electrode plate is fixed to the second frame.

[0013] Furthermore, the installation method of the capacitive liquid sensor in the embodiment includes the following steps: with the face directions of the first frame and the second frame being vertical and the face directions of the first electrode plate and the second electrode plate being vertical, the capacitive liquid sensor is installed on the installation object. Attached Figure Description

[0014] Figure 1 This is a perspective view showing the appearance of an example of a capacitive liquid sensor according to one embodiment.

[0015] Figure 2 This is a perspective view showing the disassembled components of an example of a capacitive liquid sensor according to one embodiment.

[0016] Figure 3 This is an example of a capacitive liquid sensor in one implementation. Figure 1 The diagram shows the X3 direction.

[0017] Figure 4 This is an example of a capacitive liquid sensor in one implementation. Figure 3 The cross-sectional view is shown along line X4-X4.

[0018] Figure 5 This is an example of a capacitive liquid sensor in one implementation. Figure 3 The cross-sectional view is shown along line X5-X5.

[0019] Figure 6 This is an example of a capacitive liquid sensor in one implementation. Figure 3 The cross-sectional view is shown along line X6-X6.

[0020] Figure 7 This is an example of a capacitive liquid sensor in one implementation. Figure 3 The cross-sectional view is shown along line X7-X7.

[0021] Figure 8 This is a diagram illustrating an example of an electrode plate for one embodiment of a capacitive liquid sensor.

[0022] Figure 9 This is an enlarged example of a capacitive liquid sensor according to one embodiment. Figure 4 The diagram shown is part of X9.

[0023] Figure 10 This is a diagram illustrating a first example of the use of a capacitive liquid sensor according to one embodiment.

[0024] Figure 11 This is a diagram illustrating a second example of the use of a capacitive liquid sensor according to one embodiment.

[0025] Figure 12 This is a diagram that conceptually illustrates the positional relationship between the first electrode plate and the second electrode plate of a capacitive liquid sensor according to one embodiment. Detailed Implementation

[0026] Hereinafter, a capacitive liquid sensor according to one embodiment and a method for mounting the capacitive liquid sensor will be described with reference to the accompanying drawings. In the following description, the capacitive liquid sensor will sometimes be simply referred to as a liquid sensor.

[0027] Figure 1The liquid sensor 10 shown is installed in a container filled with an electrically insulating liquid, such as a compressor container, and can be used to detect the state of the electrically insulating liquid present in the container, that is, to detect the liquid level and mixing ratio of the lubricating oil and liquid refrigerant in the container. Figures 1 to 4 As shown, the liquid sensor 10 has two connecting members 11, a base member 21, two conductive terminal pins 22, a filling material 23, two frames 30, multiple electrode plates 40, and two spacers 50.

[0028] The base component 21, conductive terminal pins 22, and filler material 23 constitute the airtight terminal 12. The airtight terminal 12 is a structure for mounting the liquid sensor 10 to a container such as a compressor. The frame 30, electrode plate 40, and spacer 50 constitute the detection unit 13. The detection unit 13 is a structure for detecting the state of electrically insulating liquids such as lubricating oil and liquid refrigerant in the compressor. Furthermore, the connecting member 11 is a structure for electrically and physically connecting each conductive terminal pin 22 to the frame 30.

[0029] In this embodiment, the two connecting members 11 have different specific structures. One connecting member 111 is formed to be thicker and more rigid than the other connecting member 112, meaning it is less prone to deformation. Conversely, the other connecting member 112 is formed to be thinner and more elastic than the first connecting member 111, meaning it is more easily deformed.

[0030] In the following description, among the two connecting members 111 and 112, the connecting member with higher rigidity is sometimes referred to as the first connecting member 111, and the connecting member that is more easily deformed is referred to as the second connecting member 112. In addition, in this specification, the terms "first" and "second" are used only for the convenience of distinguishing structures with the same function, and do not indicate the order or superiority of the structures.

[0031] like Figure 5 As shown, the second connecting member 112 can, for example, significantly extend the overall length of the L-shaped bend, making it a structure more prone to elastic deformation. Thus, it becomes a structure where the first frame 301 is firmly fixed by the highly rigid first connecting member 111, and the highly elastic second connecting member 112 elastically absorbs strain and dimensional changes generated during welding, etc. As a result, deformation of the frame 30 and electrode plate 40 caused by assembly errors, stress during installation, etc., can be suppressed, and deviations in the characteristics of the liquid sensor 10 can be suppressed.

[0032] The base component 21 is made of a metallic material and is formed in a shallow cup shape. The conductive terminal pin 22 is made of a conductive component such as metal, and is formed, for example, in a cylindrical rod shape. Figure 4As shown, two conductive terminal pins 22 pass through holes 211 formed at the bottom of the base member 21. The filler material 23 is made of an electrically insulating material such as glass and can also be called an insulating member. The filler material 23 fills the space between the inside of the hole 211 and the conductive terminal pins 22, electrically insulating the conductive terminal pins 22 from the base member 21 and fixing the conductive terminal pins 22 to the base member 21. Thus, the two conductive terminal pins 22 are fixed to the base member 21 in an electrically insulating state and in an airtight and watertight state, respectively.

[0033] The two conductive terminal pins 22 are electrically insulated from each other. The two conductive terminal pins 22 are arranged in parallel and extend in the depth direction of the base member 21. A detection unit 13 is connected to one end of each of the two conductive terminal pins 22. When the liquid sensor 10 is installed in a compressor container or the like, the detection unit 13 is located inside the container. When the liquid sensor 10 is installed in a compressor container or the like, the other end of each of the two conductive terminal pins 22 is located outside the container. In the following description, when distinguishing between the two conductive terminal pins 22, one will sometimes be referred to as the first conductive terminal pin 221, and the other as the second conductive terminal pin 222.

[0034] The frame 30 is made of a conductive metal material and is electrically connected to the conductive terminal pin 22. In the following description, when distinguishing between the two frames 30, the frame connected to the first conductive terminal pin 221 is sometimes referred to as the first frame 301, and the frame connected to the second conductive terminal pin 222 is sometimes referred to as the second frame 302. The first frame 301 and the second frame 302 are formed with the same shape. The frame 30 is generally formed as a rectangular frame, that is, a rectangular hole is formed in the center of the rectangular metal plate. The frame 30 is longer in the length direction of the conductive terminal pin 22, and its overall shape is generally rectangular. Furthermore, the two frames 30 are arranged facing each other at a predetermined distance. In this case, the face direction of the frame 30 is aligned with the length direction of the conductive terminal pin 22.

[0035] like Figure 2 , Figure 3 , Figure 6 ,as well as Figure 7 As shown, the frame 30 has a through portion 31, a protrusion 32, and a defining portion 33. The through portion 31 is formed into a rectangular hole shape, allowing a portion of the plurality of electrode plates 40 to pass through. The protrusion 32 is provided on two edges extending in the length direction of the frame 30, that is, the long sides on both sides, forming a shape that protrudes to the opposite side of the opposing frame 30. The protrusion 32 is formed continuously and elongatedly in the length direction of the frame 30. The length dimension of the protrusion 32 is set to be greater than or equal to the length dimension of the through portion 31 in the length direction.

[0036] like Figure 2 As shown, the defining portion 33 is provided on both sides of the frame 30 extending in the width direction, that is, on both short sides, and protrudes outwards in the length direction of the frame 30. Furthermore, in this specification, when referring to the width direction for a certain structure, the width direction means the direction perpendicular to the length direction of that structure. The defining portion 33 is inserted into the spacer 50 and has the function of defining the distance from the opposing frame 30, that is, maintaining the distance from the opposing frame 30 at a fixed value. In the frame 30, for example, the through portion 31, the protrusion 32, and the defining portion 33 are integrally formed by pressing a metal sheet.

[0037] The spacer 50 is configured as a rectangular block or container shape, having two insertion portions 51. The two insertion portions 51 are, for example, elongated rectangular or oblong holes extending in the width direction of the frame 30, and are arranged parallel to each other. The designated portion 33 of the frame 30 is inserted into the insertion portions 51 and held in place. This defines the positional relationship between the two frames 30. Preferably, the spacer 50 is made of an electrically insulating material such as resin or ceramic that does not undergo shape changes or deterioration under the operating environment of the liquid sensor 10. Furthermore, although in this embodiment a structure is formed with one spacer 50 at each end of the frame 30, a structure in which the spacer 50 is provided only at one end of the frame 30 is also possible, as long as the positional relationship between the two frames 30 can be defined. The spacer 50 may also be formed in the designated portion 33 using insert molding.

[0038] The frame 30 is electrically and physically connected to the conductive terminal pin 22 via the connecting member 11. The connecting member 11 is, for example, a member with a roughly L-shaped cross-section obtained by bending a metal plate. Moreover, in the connecting member 11, one end is fixed to the frame 30, for example by welding or brazing, and the other end is fixed to the conductive terminal pin 22, for example by welding or brazing.

[0039] Electrode plate 40 is made of a thin, conductive sheet material such as a metal plate and is disposed in frame 30. It is electrically connected to conductive terminal pin 22 via frame 30 and connecting member 11. In the following description, electrode plate 40 disposed in first frame 301 is sometimes referred to as first electrode plate 401, and electrode plate 40 disposed in second frame 302 is sometimes referred to as second electrode plate 402. First electrode plate 401 and second electrode plate 402 face each other without contacting each other and are alternately arranged in the length direction of frame 30, that is, in the length direction of conductive terminal pin 22. That is, the surface of each electrode plate 40 is arranged orthogonally to the extending direction of conductive terminal pin 22.

[0040] The first electrode plate 401 and the second electrode plate 402 are formed with the same shape. For example... Figures 6 to 8As shown, the electrode plate 40 has a detection section 41 and two fixing sections 42. The detection section 41 is located in... Figure 8 The area shown by the dashed diagonal lines in the middle, and the area shown by the fixed part 42 by the solid grid lines. The detection part 41 occupies most of the electrode plate 40 and is the part facing the other adjacent electrode plates 40. That is, the detection part 41 is the area that overlaps with each other in the adjacent first electrode plate 401 and second electrode plate 402. The detection part 41 is, for example, formed into an elongated rectangular shape or a roughly rectangular shape, facing the direction in which the two frames 30 are arranged.

[0041] The fixing portion 42 extends from both ends of the two edges, i.e., the long side portions, of the detection portion 41. The fixing portion 42 extends in a direction orthogonal to the length direction of the detection portion 41. In this embodiment, the fixing portion 42 is located in the non-overlapping area between adjacent first electrode plates 401 and second electrode plates 402. The fixing portion 42 is not provided at the ends of the detection portion 41 in the length direction, but rather in the middle portion of the length direction. The fixing portion 42 is located at a position offset to one side from the center O in the length direction of the detection portion 41.

[0042] Furthermore, the electrode plate 40 is formed in a cross shape where the length direction of the detection portion 41 intersects the protruding direction of the fixing portion 42. Moreover, in the electrode plate 40, the outer edge 411 of the detection portion 41 and the outer edge 421 of the fixing portion 42 are formed by the same circular arc, that is, by forming arcs of the same radius. In the electrode plate 40, the detection portion 41 and the fixing portion 42 are integrally formed, for example, by stamping a circular thin plate through a pressing process.

[0043] Here, the outer edge 411 of the detection part 41 and the outer edge 421 of the fixing part 42 are formed by an arc of a circle with radius R centered at center O. Center O is the center of the detection part 41 in both the length and width directions. In this case, the width dimension A of the detection part 41 is set to be greater than the radius R, and the width dimension B of the fixing part 42 is set to be less than the radius R. Preferably, the width dimension A of the detection part 41 is in the range of 1.2 to 1.3 times the radius R, and the width dimension B of the fixing part 42 is in the range of 1 / 4 to 1 / 3 of the radius R.

[0044] The detection unit 41 has a clearance portion 412. The clearance portion 412 is provided on both sides of the long side portion of the detection unit 41, and is formed such that a portion of the long side portion is recessed or notched. The clearance portion 412 has the function of preventing the electrode plate 40 from contacting the frame 30, which is not connected to the electrode plate 40. That is, as... Figure 6 As shown, the clearance portion 412 of the first electrode plate 401 has the function of preventing contact with the second frame 302. Furthermore, as... Figure 7As shown, the avoidance portion 412 of the second electrode plate 402 has the function of preventing contact with the first frame 301.

[0045] When each electrode plate 40 is installed on the frame 30, in each electrode plate 40, the region of the detection section 41 that is closer to the center O than the fixing section 42 passes through the through section 31 from the protrusion 32 side of the frame 30. Furthermore, regarding the connection and fixation between the electrode plate 40 and the frame 30, the portion of the electrode plate 40 that contacts the frame 30 can be welded, for example, by projection welding, spot welding, or seam welding. Thus, the fixing section 42 is welded and fixed to the frame 30. Alternatively, the connection and fixation between the electrode plate 40 and the frame 30 can also be achieved by brazing or other means. Furthermore, for example, positioning protrusions or recesses can be provided on the fixing section 42 of the electrode plate 40 and the frame 30.

[0046] like Figure 1 , Figure 3 , Figure 4 ,as well as Figure 9 As shown, the first electrode plate 401 and the second electrode plate 402 are arranged alternately at equal intervals. Furthermore, as... Figure 9 As shown, the distance L1 between the first frame 301 and the second frame 302 is set to be 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, that is, between their surfaces, is set to be less than the distance L1 between the first frame 301 and second frame 302, that is, between their surfaces. Furthermore, the thickness T1 of the first frame 301 and the second frame 302 is set to be greater than the thickness T2 of the first electrode plates 401 and the second electrode plates 402. In this case, the distance between the centers of the first electrode plates 401 and the second electrode plates 402 is considered to be L2 + T2.

[0047] When the liquid sensor 10 detects substances such as refrigeration oil or refrigerant present inside a compressor, the distance L2 between adjacent first electrode plates 401 and second electrode plates 402 is preferably set to a range of, for example, 1 mm to 1.8 mm. This provides the capacitance required for liquid detection and ensures good drainage between electrode plates 401 and 402. Furthermore, the distance L1 between frames 301 and 302 is preferably set to a range of, for example, 2 mm to 3 mm. This suppresses the retention of droplets and bubbles discharged from electrode plates 401 and 402 between the two frames 30 due to surface tension and other factors. As a result, the detection unit 13 has good drainage, improving the responsiveness of the liquid sensor 10.

[0048] Each electrode plate 40 is fixed to one of the two frames 30 and passes through the through portion 31 of the other frame 30 without contacting the other frame 30 or the electrode plate 40 fixed to the other frame 30. That is, the first electrode plate 401 passes through the through portion 31 of the second frame 302 without contacting the second frame 302 or the second electrode plate 402. Similarly, the second electrode plate 402 passes through the through portion 31 of the first frame 301 without contacting the first frame 301 or the first electrode plate 401.

[0049] The first electrode plate 401 and the second electrode plate 402 can be configured in the same number or 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, such as Figure 2 As shown, the number of first electrode plates 401 is set to 6, while the number of second electrode plates 402 is set to 5. Moreover, 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.

[0050] Next, also refer to Figure 10 and Figure 11 A mounting example of the liquid sensor 10 relative to a mounting object will be described. For example, the liquid sensor 10 is mounted on a compressor container 80. Figure 10 In this example, the liquid sensor 10 is directly mounted on the peripheral wall of the container 80. Furthermore, in... Figure 11 In this example, the liquid sensor 10 is mounted on the flange 81 of the container 80. The flange 81 is provided on the peripheral wall of the container 80 and is formed as a cylindrical portion protruding outward from the peripheral wall of the container 80. Figure 11 In this example, the liquid sensor 10 is mounted on the flange portion 81 via the flange cover 82.

[0051] When installing the liquid sensor 10 onto the container 80, the operator positions the liquid sensor 10 with the faces of the first frame 301 and the second frame 302 facing vertically, and with the faces of the first electrode plate 401 and the second electrode plate 402 also facing vertically. That is, the operator positions the liquid sensor 10 in the container 80 with the faces of the first electrode plate 401 and the second electrode plate 402 facing vertically. Figure 1Arrow D indicates that the liquid sensor 10 is installed in the container 80 in a vertical orientation. In this case, the two frames 301 and 302 are arranged horizontally, and the gap between the two frames 301 and 302 is open in the vertical direction. Furthermore, the two conductive terminal pins 221 and 222 are arranged horizontally. When installing the liquid sensor 10 in the container 80, the operator can, for example, observe the configuration of the two conductive terminal pins 221 and 222 while aligning them horizontally, thereby adjusting the orientation of the liquid sensor 10.

[0052] The portion of the conductive terminal pin 22 exposed outside the container 80 is connected, for example, via a wire (not shown) or directly to a signal processing circuit (not shown). 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. Then, the signal output from the signal processing circuit is sent to a control device, such as a compressor, on which the liquid sensor 10 is installed. The control device performs compressor operation control based on the signal output from the signal processing circuit, corresponding to the state of the liquid.

[0053] According to the embodiments described above, the liquid sensor 10 includes 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 pass through the base member 21 and are fixed to the base member 21 by an electrically insulating filler material 23. The first conductive terminal pin 221 and the second conductive terminal pin 222 are electrically insulated from each other.

[0054] The first frame 301 is made of metal and is electrically connected to the first conductive terminal pin 221. The second frame 302 is made of metal 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 is electrically connected to and physically fixed to the first frame 301 or the second frame 302 by welding, brazing, or other methods.

[0055] 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 the two 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 length direction of the detection portion 41 intersects the protruding direction of the fixing portion 42. Moreover, the first frame 301 and the second frame 302 are arranged facing each other and alternately.

[0056] In the first electrode plate 401, with the detection portion 41 of the first electrode plate 401 passing through the through portion 31 of the first frame 301 and the second frame 302, the fixing portion 42 of the first electrode plate 401 is fixed to the first frame 301. In the second electrode plate 402, with the detection portion 41 of the second electrode plate 402 passing through the through portion 31 of the second frame 302 and the first frame 301, the fixing portion 42 of the second electrode plate 402 is fixed to the second frame 302. In this case, each fixing portion 42 of the first electrode plate 401 and the second electrode plate 402 is connected and fixed to the periphery of the through portion 31 in the first frame 301 or the second frame 302 by welding, brazing, or the like; specifically, it is connected and fixed to the edge of the first frame 301 or the second frame extending in the length direction.

[0057] Therefore, by having multiple electrode plates 40, the capacitance of the liquid sensor 10 can be increased, thereby improving the sensitivity of the liquid sensor 10. Furthermore, each electrode plate 40 is connected and fixed to the frame 30 by extending two fixing portions 42 from the two edges of the detection portion 41 in a cross-shaped manner relative to the detection portion 41, rather than through the longitudinal end of the detection portion 41. Therefore, compared to the case where the electrode plate is supported through the longitudinal end of the detection portion 41, the distance from the fixing portion to the end of the electrode plate 40 can be shortened, thereby reducing the effects of deflection caused by external forces. This suppresses changes in the distance between the electrode plates 40, resulting in stable performance of the liquid sensor 10.

[0058] Furthermore, since the fixing part 42 is a structure that extends outward from both sides of the detection part 41, tools and the like are unlikely to interfere with the detection part 41 during the welding of the fixing part 42 to the frame 30, so reliable operation can be performed with a simple device.

[0059] Furthermore, the method of mounting the liquid sensor 10 of this embodiment onto the container 80 includes a step of mounting the sensor onto the container 80 or other mounting object in an orientation in which the plane directions of the two frames 30 are vertical and the plane directions of the detection portions 41 of each electrode plate 40 are vertical.

[0060] By mounting the liquid sensor 10 of this embodiment onto a container 80 or the like as described above, changes in the liquid level within the container 80 can cause the detection unit 13 to move from the liquid to the gas, or from the gas to the liquid. Due to the influence of the surrounding liquid flow, gravity, etc., the liquid between the electrode plates 40 flows in the direction along the surface of the electrode plates 40. This allows droplets and bubbles adhering to the electrode plates 40 to be easily discharged 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.

[0061] Furthermore, each electrode plate 40 is fixed to the frame 30 with the detection unit 41 passing through the through portion 31 of the frame 30. That is, a portion of the detection unit 41 is surrounded by the frame 30. Moreover, when the liquid sensor 10 is installed on a container 80 or other mounting object with the planes of the two frames 30 in a vertical direction and the planes of the detection units 41 of each electrode plate 40 in a vertical direction, there is a contact portion between the fixing portion 42 of the electrode plate 40 and the frame 30 below the gravity direction of the electrode plate 40. Therefore, when the detection unit 13 is exposed from the liquid, droplets and bubbles attached to the electrode plate 40 accumulate along the surface of the electrode plate 40 below the gravity direction, and then flow from the contact portion between the fixing portion 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, thereby further improving the detection accuracy and response speed of the liquid sensor 10.

[0062] In the electrode plate 40, the outer edge 411 of the detection section 41 and the outer edge 421 of the fixing section 42 are arcs of the same circle, formed by a portion of an arc with radius R. That is, the outer periphery of the electrode plate 40 is formed by a portion of an arc with the same radius R. Therefore, when the detection unit 13 is arranged in a cylindrical space, the area of ​​the detection section 41 and the fixing section 42 can be ensured to be large within the contour of the cylindrical space. Furthermore, by ensuring a large area of ​​the detection section 41, a large capacitance can be obtained. In addition, by ensuring a large area of ​​the fixing section 42, the rigidity of the fixing section 42 can be improved, 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.

[0063] like Figure 9As shown, the distance L1 between the first frame 301 and the second frame 302 is greater than the distance L2 between adjacent first electrode plates 401 and second electrode plates 402. This prevents liquid moving from between the first electrode plates 401 and second electrode plates 402 towards the frame 30 from becoming trapped in the gap between the two frames 30 due to surface tension and other factors. Consequently, the trapping of droplets and bubbles between the frames 30 and electrode plates 40 can be more effectively suppressed. As a result, the liquid sensor 10 can rapidly detect changes in the liquid level, further improving its responsiveness.

[0064] The thickness T1 of the first frame 301 and the second frame 302 is set to be greater than the thickness T2 of the first electrode plate 401 and the second electrode plate 402. This allows the first frame 301 and the second frame 302 to be thicker and more rigid than the first electrode plate 401 and the second electrode plate 402. Therefore, even when multiple electrode plates 40 are closely arranged in the frame 30, deflection due to the weight of each electrode plate 40 can be suppressed, and each electrode plate 40 can be reliably held in place. This suppresses changes in the position of the electrode plates 40 caused by deformation of the frame 30, thereby further improving the sensitivity and reliability of the liquid sensor 10.

[0065] In the electrode plates 40, the number of electrode plates 401 fixed to one frame 301 is set to be one more than the number of electrode plates 402 fixed to another frame 302, and in the arrangement of the electrode plates 40, one more electrode plate 401 is arranged at each end. 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 another pole. Moreover, in each electrode plate 40 arranged alternately in the length 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 the second electrode plates 402, the first electrode plates 401 are arranged at both ends.

[0066] Therefore, when the first frame 301, on which the first electrode plate 401 is fixed, and the second frame 302, on which the second electrode plate 402 is fixed, are combined to form the detection unit 13, deviations in characteristics caused by deviations in the positional relationship relative to the length direction of the detection unit 13, i.e., the arrangement direction of each electrode plate 40, can be suppressed. That is, when observing the combination of the facing surfaces of the first electrode plate 401 and the second electrode plate 402, by making the electrode plates at both ends have the same pole, the number of combinations that are close to each other, i.e., increase the capacitance, can be consistent with the number of combinations that are far apart, i.e., decrease the capacitance.

[0067] For example, Figure 12As shown, when the second frame 302, on which the second electrode plate 402 is disposed, is offset relative to the first frame 301, on which the first electrode plate 401 is disposed, in the direction indicated by the hollow arrow (i.e., to the right of the plane of the paper), the distance indicated by arrow X decreases, and the distance indicated by arrow Y increases. In this case, among adjacent electrode plates 401 and 402, the capacitance between the surfaces farther away from the surface by the distance indicated by arrow X increases, and the capacitance between the surfaces farther away from the surface by the distance indicated by arrow Y decreases.

[0068] Here, in the structure where the first electrode plate 401 and the second electrode plate 402 are alternately arranged, when the number of first electrode plates 401 and second electrode plates 402 is the same, a first electrode plate 401 is arranged at one end and a second electrode plate 402 is arranged at the other end. In this case, Figure 12 The number of arrows X and Y shown is different. Therefore, when the positional relationship between the first frame 301 with the first electrode plate 401 and the second frame 302 with the second electrode plate 402 shifts, the total capacitance of the detection unit 13 as a whole also changes.

[0069] In contrast, if electrode plates 40 with the same polarity are arranged at both ends, then the number of arrows X and Y is the same, thus reducing the change in the total capacitance of the detection unit 13 as a whole. Therefore, according to this embodiment, even if there is a deviation in the positional relationship, i.e., the distance or tilt, relative to the arrangement direction of each electrode plate 40, it is possible to suppress changes in the total capacitance of the detection unit 13 as a whole. As a result, according to this embodiment, deviations in characteristics caused by positional deviations during assembly can be suppressed.

[0070] (Modified Example)

[0071] In addition, the distance L1 between the two frames 30, the interval L2 between each electrode plate 40, and the number and size of each electrode plate 40 are not limited to the above, and can be appropriately adjusted according to the properties of the liquid being detected and the required sensitivity.

[0072] In the above example, although a metal plate was used as a connecting member 11 to connect the conductive terminal pin 22 to the frame 30, when a different component than the connecting member 11 is used to fix the detection unit 13, the connecting member 11 may also be made of, for example, a flexible wire or a plastically deformable component.

[0073] Furthermore, the liquid sensor 10 of this embodiment is not limited to detecting the liquid level of lubricating oil or liquid refrigerant by placing the detection unit 13 near the gas-liquid boundary inside the compressor. For example, the detection unit 13 can always be placed in a gas or liquid to detect the mixing ratio of lubricating oil and liquid refrigerant, and to detect the phenomenon of changes in dielectric constant between the electrode plates 40.

[0074] Furthermore, the airtight terminal 12 and the detection unit 13 can also be detachable. For example, when space is limited for installing the liquid sensor 10, it is sometimes preferable to pre-install the airtight terminal 12 on the wall of the container before installing the detection unit 13. In such cases, the airtight terminal 12 and the detection unit 13 can be detachable, that is, the conductive terminal pin 22 and the frame 30 can be detached.

[0075] The above-described embodiment is presented as an example and is not intended to limit the scope of the invention. This new embodiment can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its variations are included within the scope and spirit of the invention, and are included within the scope of the invention and its equivalents as described in the patent claims.

Claims

1. A capacitive liquid sensor, comprising: Base components; A first conductive terminal pin and a second conductive terminal pin pass through the base member, are fixed to the base member via an electrically insulating filler material, and are electrically insulated from each other; The first frame, which is made of metal, is electrically connected to the first conductive terminal pin. The second frame, which is made of metal, is electrically connected to the second conductive terminal pin. Multiple first electrode plates, which are made of metal plates, are connected and fixed to the first frame by welding or brazing. Multiple second electrode plates, which are made of metal plates, are fixed to the second frame by welding or brazing; and A spacer, made of electrically insulating material, is disposed at the ends of the first frame and the second frame, defining the distance between the first frame and the second frame. The first frame and the second frame each have a through portion through which the first electrode plate and the second electrode plate pass, 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 the two edges of the detection portion, forming a cross shape in which the length direction of the detection portion intersects the protruding direction of the fixing portions, and are arranged facing each other and alternately. In the first electrode plate, with the detection portion of the first electrode plate passing through the through portions of the first frame and the second frame, the fixing portion of the first electrode plate is fixed to the first frame. In the second electrode plate, when the detection part of the second electrode plate passes through the through part of the second frame and the first frame, the fixing part of the second electrode plate is fixed to the second frame.

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

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

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

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

6. A method for installing a capacitive liquid sensor, comprising installing the capacitive liquid sensor of claim 1 onto an object, comprising: The process of installing the capacitive liquid sensor onto the mounting object with the faces of the first frame and the second frame in a vertical orientation and the faces of the first electrode plate and the second electrode plate in a vertical orientation.

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