Capacitive liquid sensor and installation method of capacitive liquid sensor

Abstract

The capacitive liquid sensor (10) comprises a first frame body (301) and a second frame body (302) which are made of metal materials, and a plurality of first electrode plates (401) and second electrode plates (402) which are made of metal plates. The first frame body and the second frame body are respectively provided with a passing part (31) through which the first electrode plate and the second electrode plate pass, 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, face each other and are alternately arranged. In the first electrode plate, the fixing portion of the first electrode plate is fixed to the first housing in a state in which the detection portion of the first electrode plate passes through the passing portions of the first housing and the second housing. In the second electrode plate, the fixing portion of the second electrode plate is fixed to the second housing in a state in which the detection portion of the second electrode plate passes through the second housing and the passing portion of the first housing.

Description

Technical Field

[0001] Embodiments of the present invention relate to a capacitive liquid sensor and a method for installing 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 principle that when a non-conductive liquid enters the space between fixed electrodes, the capacitance between the electrodes changes, and detects the presence or absence of the liquid, the liquid volume, and the mixing ratio of the liquid. As a capacitive liquid sensor, for example, electrode plates are respectively fixed to two conductive pins of an airtight terminal, and the change in the liquid level height in the container is detected based on the change in the capacitance between the electrode plates. Such a liquid sensor is installed, for example, at a position where the entire electrode is in the liquid under normal conditions and the electrode is exposed to the gas when the liquid level drops. Then, the liquid sensor detects the change in the liquid level by utilizing the difference in the dielectric constants of the liquid and the gas.

[0003] However, in the conventional capacitive liquid sensor, the change in capacitance obtained by the presence or absence of the liquid between the electrodes is small, and it is difficult to correctly judge the state of the liquid based on this change in capacitance. In this case, by increasing the area of the electrodes or narrowing the interval 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 is considered.

[0004] Prior Art Documents

[0005] Patent Documents

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

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

[0008] Problems to be Solved by the Invention

[0009] However, in the case where a plurality of electrodes are arranged at a narrow interval, when the support of each electrode is weak, the positional relationship between the electrodes easily changes when an external force is applied to each electrode, which has an adverse effect on the detection characteristics of the liquid sensor. In addition, if the interval between the electrodes is narrowed, when each electrode is exposed from the liquid to the gas, due to the influence of surface tension, etc., liquid droplets and bubbles entering between the electrodes are difficult to discharge from between the electrodes. Thus, the liquid sensor has a problem that even if the gas-liquid state around the electrodes changes, it cannot immediately respond to this change in state.

[0010] This embodiment has been completed in view of the above circumstances, and its object is to provide a capacitive liquid sensor that can highly sensitively detect changes in the state of a liquid by improving the support strength of electrodes and the dischargeability of droplets and bubbles between electrodes in a capacitive liquid sensor having a plurality of electrodes.

[0011] Solution to the problem

[0012] The capacitive liquid sensor of the embodiment includes: a base member; a first conductive terminal pin and a second conductive terminal pin that pass through the base member, are fixed to the base member via a filling material having electrical insulation, and are 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; and a plurality of second electrode plates made of metal plates and connected 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 edge portions of the detection portion, and are formed in a cross shape in which the length direction of the detection portion intersects the protruding direction of the fixing portion, and are arranged facing each other and alternately. In the first electrode plate, in a state where 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, in a state where the detection portion of the second electrode plate passes through the through portions of the second frame and the first frame, the fixing portion of the second electrode plate is fixed to the second frame.

[0013] In addition, the installation method of the capacitive liquid sensor of the embodiment includes the following steps: installing the capacitive liquid sensor on the installation object in a posture where the surface direction of the first frame and the second frame is in the vertical direction and the surface direction of the first electrode plate and the second electrode plate is in the vertical direction. Description of the drawings

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

[0015] Figure 2 is a perspective view showing an example of a capacitive liquid sensor according to an embodiment with each structure disassembled.

[0016] Figure 3 is for an example of a capacitive liquid sensor according to an embodiment fromFigure 1 A view shown in the X3 direction.

[0017] Figure 4 An example of a capacitive liquid sensor for one embodiment is a cross-sectional view shown along Figure 3 the X4-X4 line.

[0018] Figure 5 An example of a capacitive liquid sensor for one embodiment is a cross-sectional view shown along Figure 3 the X5-X5 line.

[0019] Figure 6 An example of a capacitive liquid sensor for one embodiment is a cross-sectional view shown along Figure 3 the X6-X6 line.

[0020] Figure 7 An example of a capacitive liquid sensor for one embodiment is a cross-sectional view shown along Figure 3 the X7-X7 line.

[0021] Figure 8 A view showing an example of an electrode plate of an example of a capacitive liquid sensor for one embodiment.

[0022] Figure 9 An example of a capacitive liquid sensor for one embodiment is a view showing an enlarged Figure 4 portion shown by X9.

[0023] Figure 10 A view showing a first usage example of a capacitive liquid sensor of one embodiment.

[0024] Figure 11 A view showing a second usage example of a capacitive liquid sensor of one embodiment.

[0025] Figure 12 A view conceptually showing the positional relationship between a first electrode plate and a second electrode plate of a capacitive liquid sensor for one embodiment. Detailed Embodiments

[0026] Hereinafter, a capacitive liquid sensor and a method of installing the capacitive liquid sensor according to one embodiment will be described with reference to the drawings. In the following description, the capacitive liquid sensor may 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 the container of a compressor, and can be 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 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, a plurality of electrode plates 40, and two spacers 50.

[0028] The base member 21, the conductive terminal pins 22, and the filling material 23 constitute an airtight terminal 12. The airtight terminal 12 is a structure for installing the liquid sensor 10 in a container of a compressor or the like. The frame 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. Moreover, the connecting member 11 is a structure for electrically connecting and physically connecting each conductive terminal pin 22 to the frame 30.

[0029] In the case of the present embodiment, the specific structures of the two connecting members 11 are different. Among the two connecting members 11, one connecting member 111 is formed to have a thicker plate thickness and higher rigidity, that is, a structure that is not easily deformed, compared with the other connecting member 112. In other words, the other connecting member 112 is formed to have a thinner plate thickness and elasticity, that is, a structure that is easily deformed, compared with the above-mentioned one connecting member 111.

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

[0031] As Figure 5 As shown, the second connecting member 112 can, for example, greatly detour the L-shaped bent portion to extend the overall length, resulting in a structure that is more easily elastically deformed. Thereby, it can be a structure in which the first frame 301 is firmly fixed by the first connecting member 111 with high rigidity, and the strain and dimensional changes generated during welding or the like are elastically absorbed by the second connecting member 112 with high elasticity. As a result, it is possible to suppress the deformation of the frame 30 and the electrode plates 40 caused by assembly errors, stresses during installation, etc., and to suppress the deviation of the characteristics of the liquid sensor 10.

[0032] The base member 21 is made of a metal material and is formed in a shallow cup shape. The conductive terminal pins 22 are made of a conductive member such as metal and are formed, for example, in a cylindrical rod shape. As Figure 4As shown, two conductive terminal pins 22 respectively pass through the hole portions 211 formed at the bottom of the base member 21. The filling material 23 is made of a material with electrical insulation properties such as glass, and can also be called an insulating member. The filling material 23 is filled between the inner side of the hole portion 211 and the conductive terminal pins 22, electrically insulates the conductive terminal pins 22 from the base member 21, and fixes the conductive terminal pins 22 to the base member 21. Thus, the two conductive terminal pins 22 are respectively fixed to the base member 21 in a state of being electrically insulated from the base member 21 and in an airtight and watertight state.

[0033] The two conductive terminal pins 22 are electrically insulated from each other. The two conductive terminal pins 22 are arranged in parallel respectively and extend in the depth direction of the base member 21. Among the two conductive terminal pins 22, a detection unit 13 is connected to one end side. When the liquid sensor 10 is installed in a container of a compressor or the like, the detection unit 13 is located on the inner side of the container. When the liquid sensor 10 is installed in a container of a compressor or the like, among the two conductive terminal pins 22, the other end side is located on the outer side of the container. In the following description, when distinguishing the two conductive terminal pins 22, sometimes one of them is called the first conductive terminal pin 221 and the other is called 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 pins 22. In the following description, when distinguishing the two frames 30, sometimes the frame connected to the first conductive terminal pin 221 is called the first frame 301, and the frame connected to the second conductive terminal pin 222 is called the second frame 302. The first frame 301 and the second frame 302 are formed in the same shape. The whole frame 30 is formed in a rectangular frame shape, that is, a rectangular hole is formed in the central part of the rectangular metal plate. The frame 30 is long in the length direction of the conductive terminal pins 22, and the overall outer shape is formed in a substantially rectangular frame shape. In addition, the two frames 30 are arranged facing each other at a prescribed distance. In this case, the surface direction of the frame 30 is the same as the length direction of the conductive terminal pins 22.

[0035] As Figure 2 , Figure 3 , Figure 6 , and Figure 7 shown, the frame 30 has a through portion 31, a protruding portion 32, and a prescribed portion 33. The through portion 31 is formed in a rectangular hole shape and has the function of allowing a part of the plurality of electrode plates 40 to pass through. The protruding portions 32 are provided on the two edge portions extending in the length direction of the frame 30, that is, the two long side portions on both sides, and are formed in a shape protruding toward the side opposite to the facing frame 30. The protruding portions 32 are long and continuously formed in the length direction of the frame 30. The length dimension of the protruding portions 32 is set to be equal to or greater than the length dimension in the length direction of the through portion 31.

[0036] As Figure 2 shown, etc., the regulating part 33 is provided at both side parts extending in the width direction in the housing 30, that is, the short side parts on both sides, and protrudes outward in both lateral directions of the length direction of the housing 30. In addition, in this specification, when referring to the width direction of a certain structure, the width direction means the direction perpendicular to the length direction of the structure. The regulating part 33 inserts the spacer 50 and has the function of regulating the distance from the opposing housing 30, that is, the function of maintaining the distance from the opposing housing 30 as fixed. In the housing 30, for example, by pressing a metal plate, the through part 31, the protruding part 32, and the regulating part 33 are integrally formed.

[0037] The spacer 50 is configured in a rectangular block shape or a container shape and has two insertion parts 51. The two insertion parts 51 are formed, for example, by elongated rectangular or long hole-shaped holes extending in the width direction of the housing 30 and are arranged in parallel with each other. The regulating part 33 of the housing 30 is inserted into the insertion part 51 and is held. Thereby, the positional relationship between the two housings 30 is regulated. Preferably, the spacer 50 is made of an electrically insulating material such as resin or ceramic that does not cause shape change, deterioration, etc. in the use environment of the liquid sensor 10. In addition, in the present embodiment, although a structure is formed in which a total of two spacers 50 are provided at both ends of the housing 30, as long as the positional relationship between the two housings 30 can be regulated, a structure in which only one spacer 50 is provided on one end side of the housing 30 may also be used. The spacer 50 may also be a structure provided by insert molding in the regulating part 33.

[0038] The housing 30 is electrically and physically connected to the conductive terminal pin 22 via the connecting member 11. The connecting member 11 is formed, for example, by a member having a substantially L-shaped cross section obtained by bending a metal plate. In the connecting member 11, one end is fixed to the housing 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] The electrode plate 40 is made of a thin plate having conductivity such as a metal plate, is provided in the housing 30, and is electrically connected to the conductive terminal pin 22 via the housing 30 and the connecting member 11. In the following description, the electrode plate 40 provided in the first housing 301 may sometimes be referred to as the first electrode plate 401, and the electrode plate 40 provided in the second housing 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 alternately arranged in the length direction of the housing 30, that is, in the length direction of the conductive terminal pin 22. That is, the surfaces of the respective electrode plates 40 are arranged perpendicular to the extending direction of the conductive terminal pin 22.

[0040] The first electrode plate 401 and the second electrode plate 402 are formed in the same shape. As Figures 6 to 8As shown, the electrode plate 40 has a detection portion 41 and two fixing portions 42. The detection portion 41 is the area shown by the dotted diagonal line in Figure 8 , and the fixing portion 42 is the area shown by the solid grid line. The detection portion 41 occupies most of the electrode plate 40 and is the portion facing the adjacent other electrode plates 40. That is, the detection portion 41 is the overlapping area between the adjacent first electrode plate 401 and the second electrode plate 402. For example, the detection portion 41 is formed in an overall long rectangular shape or a substantially rectangular shape in the direction in which the two frames 30 are arranged.

[0041] The fixing portion 42 is the portion extending from the two edge portions of the detection portion 41, that is, the two end portions of the long side portion. The fixing portion 42 extends in a direction orthogonal to the length direction of the detection portion 41. In the case of the present embodiment, the fixing portion 42 is the non-overlapping area between the adjacent first electrode plate 401 and the second electrode plate 402. The fixing portion 42 is not provided at the end portion in the length direction of the detection portion 41, but is provided in the middle portion in the length direction. The fixing portion 42 is provided at a position offset to one side from the center O in the length direction of the detection portion 41.

[0042] In addition, the electrode plate 40 is formed in a cross shape in which the length direction of the detection portion 41 intersects with the protruding direction of the fixing portion 42. Moreover, in the electrode plate 40, the outer edge portion 411 of the detection portion 41 and the outer edge portion 421 of the fixing portion 42 are formed as arcs of the same circle, that is, formed in an arc shape with the same radius. In the electrode plate 40, for example, by stamping a circular thin plate through pressing or the like, the detection portion 41 and the fixing portion 42 are integrally formed.

[0043] Here, the outer edge portion 411 of the detection portion 41 and the outer edge portion 421 of the fixing portion 42 are composed of arcs of a circle with a radius R centered on the center O. The center O is the center in the length direction and the width direction of the detection portion 41. In this case, the dimension A in the width direction of the detection portion 41 is set to be greater than the value of the radius R, and the dimension B in the width direction of the fixing portion 42 is set to be less than the value of the radius R. Preferably, the width dimension A of the detection portion 41 is in the range of 1.2 to 1.3 times the radius R, and the width dimension B of the fixing portion 42 is in the range of 1 / 4 to 1 / 3 of the radius R.

[0044] The detection portion 41 has an avoidance portion 412. The avoidance portion 412 is provided on the long side portions on both sides of the detection portion 41 and is formed in a shape that makes a part of the long side portion recessed or notched. The avoidance portion 412 has the function of preventing the electrode plate 40 from contacting the frame 30 that is not connected to the electrode plate 40. That is, as Figure 6 shown, the avoidance portion 412 of the first electrode plate 401 has the function of preventing contact with the second frame 302. In addition, as Figure 7As shown, the avoidance portion 412 of the second electrode plate 402 has the function of preventing contact with the first housing 301.

[0045] When each electrode plate 40 is installed on the housing 30, in each electrode plate 40, the region of the detection portion 41 closer to the center O side than the fixing portion 42 passes through the passing portion 31 from the protruding portion 32 side of the housing 30. Moreover, regarding the connection and fixation of the electrode plate 40 to the housing 30, for example, projection welding, spot welding, or seam welding can be performed on the portion where the fixing portion 42 of the electrode plate 40 contacts the housing 30. Thus, the fixing portion 42 is welded and fixed to the housing 30. In addition, brazing or other means can also be used for the connection and fixation of the electrode plate 40 to the housing 30. Furthermore, for example, unevenness for positioning can be provided on the fixing portion 42 of the electrode plate 40 and the housing 30.

[0046] As Figure 1 , Figure 3 , Figure 4 , and Figure 9 shown, the first electrode plate 401 and the second electrode plate 402 are alternately arranged at equal intervals. In addition, as Figure 9 shown, the distance L1 between the first housing 301 and the second housing 302 is set to be greater than the distance L2 between the adjacent first electrode plate 401 and the second electrode plate 402. In other words, the distance L2 between the adjacent first electrode plate 401 and the second electrode plate 402, that is, the distance between the surfaces, is set to be less than the distance L1 between the first housing 301 and the second housing 302, that is, the distance between the surfaces. In addition, the thickness dimension T1 of the first housing 301 and the second housing 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 considering the thickness of the first electrode plate 401 and the second electrode plate 402 is L2 + T2.

[0047] When the liquid sensor 10 takes, for example, the refrigeration oil, refrigerant, etc. existing inside the compressor as the detection object, it is preferable that the interval L2 between the adjacent first electrode plate 401 and the second electrode plate 402 is set within a range of, for example, 1 mm to 1.8 mm. Thus, the capacitance required for liquid detection can be obtained, and the liquid drainage property between the electrode plates 401 and 402 is good. In addition, it is preferable that the interval L1 between the housings 301 and 302 is set within a range of, for example, 2 mm to 3 mm. Thus, it is possible to suppress the situation where the droplets and bubbles discharged from the electrode plates 401 and 402 to the housing 30 side are retained between the two housings 30 due to the influence of surface tension or the like. As a result, the liquid drainage property of the detection portion unit 13 is good, and the responsiveness of the liquid sensor 10 can be improved.

[0048] While each electrode plate 40 is fixed to one of the two frames 30, it passes through the through portion 31 of the other frame 30 in such a manner that it does not contact the other frame 30 and 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 passes through the through portion 31 of the second frame 302 without contacting the second frame 302 and the second electrode plate 402. Similarly, the second electrode plate 402 is fixed to the second frame 302 and passes through the through portion 31 of the first frame 301 without contacting the first frame 301 and 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 the case of the present embodiment, the number of the first electrode plates 401 is set to be one more than the number of the second electrode plates 402. For example, in the case of the present embodiment, as Figure 2 shown, the number of the first electrode plates 401 is set to six, while the number of the second electrode plates 402 is set to five. Moreover, in the arrangement of the first electrode plate 401 and the second electrode plate 402, the first electrode plates 401 are arranged at both end portions.

[0050] Next, with reference to Figure 10 and Figure 11 , an example of mounting the liquid sensor 10 to the mounting object will be described. The liquid sensor 10 uses, for example, the container 80 of the compressor as the mounting object and is mounted on the container 80 for use. In Figure 10 example, the liquid sensor 10 is directly mounted on the peripheral wall portion of the container 80. Further, in Figure 11 example, 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 portion of the container 80 and is formed in a cylindrical shape protruding outward from the peripheral wall portion of the container 80. In Figure 11 example, the liquid sensor 10 is mounted on the flange portion 81 via the flange cover 82.

[0051] When mounting the liquid sensor 10 on the container 80, the operator mounts the liquid sensor 10 on the container 80 in a posture where the surface direction of the first frame 301 and the second frame 302 faces the vertical direction, and in a posture where the surface direction of the first electrode plate 401 and the second electrode plate 402 faces the vertical direction. That is, the operator mounts the liquid sensor 10 in Figure 1With the arrow D in the vertical direction, the liquid sensor 10 is installed in the container 80. In this case, the two frame bodies 301 and 302 are arranged in the horizontal direction, and the gap between the two frame bodies 301 and 302 is open in the vertical direction. In addition, the two conductive terminal pins 221 and 222 are arranged in the horizontal direction. When the operator installs the liquid sensor 10 in the container 80, for example, the operator can adjust the attitude of the liquid sensor 10 while observing the arrangement of the two conductive terminal pins 221 and 222 so that the two conductive terminal pins 221 and 222 are horizontally arranged.

[0052] In the part of the conductive terminal pin 22 that is exposed outside the container 80, for example, it is connected to a signal processing circuit (not shown) via a wire (not shown) or directly. The signal processing circuit determines the state of the liquid based on the change in the capacitance of the detection unit 13 and outputs a signal corresponding to the state. Then, the signal output from the signal processing circuit is sent to, for example, the control device of the compressor where the liquid sensor 10 is installed, and the control device performs the operation control of the compressor corresponding to the state of the liquid based on the signal output from the signal processing circuit.

[0053] According to the embodiment 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 body 301, a second frame body 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 via a filling material 23 having electrical insulation properties. The first conductive terminal pin 221 and the second conductive terminal pin 222 are electrically insulated from each other.

[0054] The first frame body 301 is made of a metal material and is electrically connected to the first conductive terminal pin 221. The second frame body 302 is made of a metal material and is electrically connected to the second conductive terminal pin 222. The plurality of first electrode plates 401 are made of metal plates and are connected and fixed to the first frame body 301. The plurality of second electrode plates 402 are made of metal plates and are connected and fixed to the second frame body 302. That is, each of the first electrode plates 401 and each of the second electrode plates 402 are electrically connected to and physically fixed to the first frame body 301 or the second frame body 302 by welding, brazing, etc.

[0055] The first frame body 301 and the second frame body 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 two edge portions of the detection portion 41. The first electrode plate 401 and the second electrode plate 402 are formed in a cross shape in which the length direction of the detection portion 41 intersects the protruding direction of the fixing portion 42. Moreover, the first frame body 301 and the second frame body 302 are arranged facing each other and alternately.

[0056] In the first electrode plate 401, with the detection part 41 of the first electrode plate 401 passing through the through part 31 of the first housing 301 and the second housing 302, the fixing part 42 of the first electrode plate 401 is fixed to the first housing 301. In the second electrode plate 402, with the detection part 41 of the second electrode plate 402 passing through the through part 31 of the second housing 302 and the first housing 301, the fixing part 42 of the second electrode plate 402 is fixed to the second housing 302. In this case, the respective fixing parts 42 of the first electrode plate 401 and the second electrode plate 402 are connected and fixed to the peripheral edge part of the through part 31 in the first housing 301 or the second housing 302 by welding, brazing, etc., specifically, to the edge part extending in the length direction of the first housing 301 or the second housing 302.

[0057] Thus, the liquid sensor 10 can increase the capacitance by having a plurality of electrode plates 40, and as a result, the sensitivity of the liquid sensor 10 can be improved. In addition, each electrode plate 40 is connected and fixed to the housing 30 by extending two fixing parts 42 in a cross shape with respect to the detection part 41 from two edge parts of the detection part 41, rather than through the end part in the length direction of the detection part 41. Therefore, compared with the case of being supported by the end part in the length direction of the detection part 41, each electrode plate 40 can shorten the distance from the fixing part to the end part of the electrode plate 40, and as a result, the influence of deflection caused by external force can be reduced. Thereby, the change in the distance between the electrode plates 40 can be suppressed, and as a result, the performance of the liquid sensor 10 can be stabilized.

[0058] Furthermore, since the fixing part 42 is structured to extend outward from the two edge sides of the detection part 41, in the operation of welding the fixing part 42 to the housing 30, it is difficult for tools, etc. to interfere with the detection part 41, so a reliable operation can be performed with a simple device.

[0059] In addition, the method of mounting the liquid sensor 10 of the present embodiment to the container 80 includes a step of mounting it to a mounting object such as the container 80 in an attitude where the surface direction of the two housings 30 is in the vertical direction and the surface direction of the detection part 41 of each electrode plate 40 is in the vertical direction.

[0060] By mounting the liquid sensor 10 of the present embodiment on a container 80 or the like as described above, when the position of the liquid level in the container 80 changes and the detection unit 13 moves from the liquid into the gas or from the gas into the liquid, due to the influence of the flow of the liquid around the detection unit 13, gravity, etc., the liquid between the electrode plates 40 flows in a direction along the surface of the electrode plates 40. Thus, it is possible to easily discharge the droplets and bubbles adhering to the electrode plates 40 from between the electrode plates 40. As a result, a liquid sensor 10 that can accurately detect changes in the liquid level can be provided.

[0061] Furthermore, each electrode plate 40 is fixed to the frame 30 in a state where the detection unit 41 passes through the through portion 31 of the frame 30. That is, a part of the detection unit 41 is surrounded by the frame 30. Moreover, when the liquid sensor 10 is mounted on a mounting object such as the container 80 with the surface direction of the two frames 30 being vertical and the surface direction of the detection unit 41 of each electrode plate 40 being vertical, there is a contact portion between the fixing portion 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 from the liquid, the droplets and bubbles adhering to the electrode plates 40 gather along the surface of the electrode plates 40 to the lower part in the weight direction, and then flow from the contact portion between the fixing portion 42 and the frame 30 to the frame 30. Thus, it is possible to quickly discharge the droplets and bubbles adhering to the electrode plates 40 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.

[0062] In the electrode plate 40, the outer edge portion 411 of the detection unit 41 and the outer edge portion 421 of the fixing portion 42 are arcs of the same circle and are formed by a part of an arc with a radius R in this case. That is, the outer peripheral portion of the electrode plate 40 is composed of a part of an arc with the same radius R. Thus, when the detection unit 13 is arranged in a cylindrical space or the like, it is possible to ensure a large area for the detection unit 41 and the fixing portion 42 within the range of the contour of the cylindrical space. Moreover, by ensuring a large area for the detection unit 41, a large capacitance can be obtained. In addition, by ensuring a large area for the fixing portion 42, the rigidity of the fixing portion 42 can be improved, and the change in the distance between the electrode plates 40 can be suppressed. As a result, according to the present embodiment, the performance of the liquid sensor 10 can be further improved.

[0063] As Figure 9As shown, the distance L1 between the first housing 301 and the second housing 302 is greater than the distance L2 between the adjacent first electrode plate 401 and the second electrode plate 402. Thereby, it is possible to suppress the liquid moving between the first electrode plate 401 and the second electrode plate 402 from staying in the gap between the two housings 30 due to the influence of surface tension or the like. Thereby, it is possible to more effectively suppress droplets and bubbles from staying between the housing 30 and the electrode plate 40. As a result, the liquid sensor 10 can quickly detect the change in the liquid level and can further improve the responsiveness.

[0064] The thickness dimension T1 of the first housing 301 and the second housing 302 is set to be greater than the thickness dimension T2 of the first electrode plate 401 and the second electrode plate 402. Thereby, the first housing 301 and the second housing 302 can be made thicker and have higher rigidity than the first electrode plate 401 and the second electrode plate 402. Therefore, in the housing 30, even when a plurality of electrode plates 40 are closely arranged, it is possible to suppress flexure due to the weight of each electrode plate 40 or the like and reliably hold each electrode plate 40. Thereby, it is possible to suppress a change in the position of the electrode plate 40 due to deformation of the housing 30 or the like. As a result, the sensitivity and reliability of the liquid sensor 10 can be further improved.

[0065] Among the electrode plates 40, the number of electrode plates 401 fixed to one housing 301 is set to be one more than the number of electrode plates 402 fixed to the other housing 302, and in the arrangement of the electrode plates 40, one more electrode plate 401 is arranged at both end portions. That is, among 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. Moreover, among the electrode plates 40 alternately arranged in the length direction, the electrode plates 401 of the same pole are arranged at both ends. In the case of the present embodiment, the number of the first electrode plates 401 is set to be one more than the number of the second electrode plates 402, and the first electrode plates 401 are arranged at both end portions in the arrangement of the first electrode plates 401 and the second electrode plates 402.

[0066] Thereby, when the first housing 301 fixed with the first electrode plate 401 and the second housing 302 fixed with the second electrode plate 402 are combined with each other to form the detection unit 13, it is possible to suppress the deviation of characteristics due to the deviation of the positional relationship with respect to the length direction of the detection unit 13, that is, the arrangement direction of each electrode plate 40. That is, in the case of observing the combination of the opposing surfaces of the first electrode plate 401 and the second electrode plate 402, by making the electrode plates at both ends the same pole, it is possible to make the number of combinations that are close to each other, that is, the number of combinations that increase the capacitance, and the number of combinations that are away from each other, that is, the number of combinations that decrease the capacitance, the same.

[0067] For example, as Figure 12As shown, when the second housing 302 provided with the second electrode plate 402 is displaced relative to the first housing 301 provided with the first electrode plate 401 in the direction indicated by the hollow arrow, that is, to the right in the drawing plane, the distance indicated by arrow X becomes smaller and the distance indicated by arrow Y becomes larger. In this case, among the adjacent electrode plates 401 and 402, the capacitance between the surfaces separated by the distance of arrow X increases, and the capacitance between the surfaces separated by the distance of arrow Y decreases.

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

[0069] In contrast, if the electrode plates 40 of the same polarity are arranged at both ends, the number of arrow X and arrow Y is the same, so the change amount of the total capacitance of the detection unit 13 as a whole becomes smaller. Therefore, according to the present embodiment, even when there are deviations in the positional relationship, that is, the distance and inclination, with respect to the arrangement direction of each electrode plate 40, the change in the total capacitance of the detection unit 13 as a whole can be suppressed. As a result, according to the present embodiment, the deviation of characteristics caused by positional deviation during assembly or the like can be suppressed.

[0070] (Modification example)

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

[0072] In the above, although the connection member 11 for connecting the conductive terminal pins 22 to the housing 30 is exemplified by processing a metal plate, when the detection unit 13 is fixed using a member different from the connection member 11, the connection member 11 can also be composed of, for example, a flexible wire or a plastically deformable member.

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

[0074] In addition, the airtight terminal 12 and the detection unit 13 may also adopt a detachable structure. For example, when the space where the liquid sensor 10 can be installed is limited, it is sometimes preferable to first install the airtight terminal 12 on the wall surface of the container and then install the detection unit 13. In such a case, it may also be configured that the airtight terminal 12 and the detection unit 13 are detachable, that is, the conductive terminal pin 22 and the housing 30 are detachable.

[0075] One embodiment described above 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 changes can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the present invention, and are included in the present invention described in the scope of the claims and its equivalent scope.

Claims

1. A capacitive liquid sensor, comprising: 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 a filling material having electrical insulation properties, and are electrically insulated from each other; A first housing, which is made of a metallic material and is electrically connected to the first conductive terminal pin; A second housing, which is made of a metallic material and is electrically connected to the second conductive terminal pin; A plurality of first electrode plates, which are made of metal plates and are connected and fixed to the first housing; and A plurality of second electrode plates, which are made of metal plates and are connected and fixed to the second housing, The first housing and the second housing respectively have through portions through which the first electrode plates and the second electrode plates pass, and are arranged facing each other, The first electrode plates and the second electrode plates respectively have a detection portion, and two fixing portions extending from two edge portions of the detection portion, and are formed in a cross shape in which the length direction of the detection portion intersects the protruding direction of the fixing portion, and are arranged facing each other and alternately, In the first electrode plate, in a state where the detection portion of the first electrode plate passes through the through portions of the first housing and the second housing, the fixing portion of the first electrode plate is fixed to the first housing, In the second electrode plate, in a state where the detection portion of the second electrode plate passes through the through portions of the second housing and the first housing, the fixing portion of the second electrode plate is fixed to the second housing.

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

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

4. The capacitive liquid sensor according to claim 1, wherein The thickness dimensions of the first housing and the second housing are set to be greater than the thickness dimensions of the first electrode plates and the second electrode plates.

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

6. An installation method of a capacitive liquid sensor, for installing the capacitive liquid sensor according to claim 1 on an installation object, comprising: A step of installing the capacitive liquid sensor on the installation object in a posture where the surface directions of the first housing and the second housing are in the vertical direction and the surface directions of the first electrode plates and the second electrode plates are in the vertical direction.

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