Fluid properties sensor

Abstract

To improve the detection accuracy of fluid properties sensors. [Solution] The fluid properties sensor 100 comprises an outer electrode 52 with a bottomed cylindrical tip and an inner electrode 62 having a second body portion 62c with an opening at its tip 62a. The outer electrode 52 has a cylindrical first body portion 52a facing the outer circumferential surface of the second body portion 62c of the inner electrode 62, and a protruding portion 52c formed to project from the bottom surface 52b of the first body portion 52a through the opening 62b to the second body portion 62c of the inner electrode 62, and facing the inner circumferential surface of the second body portion 62c. The first body portion 52a and the second body portion 62c each have radially penetrating holes (first communication hole 53, second communication hole 63), and the fluid to be detected is guided through the holes between the first body portion 52a of the outer electrode 52 and the outer circumferential surface of the second body portion 62c of the inner electrode 62, and between the protruding portion 52c of the outer electrode 52 and the inner circumferential surface of the second body portion 62c of the inner electrode 62.

Description

Technical Field

[0001] The present invention relates to a fluid property sensor.

Background Art

[0002] Patent Document 1 discloses a sensor that is disposed inside a case and has an outer electrode formed in a cylindrical shape and an inner electrode disposed radially inward of the outer electrode and extending in the axial direction of the case, and detects the state of a liquid. The sensor immerses the outer electrode and the inner electrode in the liquid, outputs the electrical parameters of the liquid between the outer electrode and the inner electrode to an external controller as detection values, and the controller calculates the conductivity of the liquid or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a fluid property sensor as described in Patent Document 1, a liquid is guided between a cylindrical outer electrode and a rod-shaped inner electrode, and the electrical parameters of the liquid are detected. In order to improve the detection accuracy of the fluid property sensor, it is preferable that the area where the outer electrode and the inner electrode face each other is large.

[0005] The present invention has been made in view of the above problems, and an object thereof is to improve the detection accuracy of a fluid property sensor.

Means for Solving the Problems

[0006] The present invention relates to a fluid property sensor for detecting the properties of a fluid to be detected, comprising an outer electrode having a bottomed cylindrical tip and a second body having an open tip, and an inner electrode provided inside the outer electrode, wherein the outer electrode has a cylindrical first body facing the outer circumferential surface of the second body of the inner electrode, and a projection formed to protrude from the bottom surface of the first body through an opening into the second body of the inner electrode and facing the inner circumferential surface of the second body of the inner electrode, respectively, and the first body of the outer electrode and the second body of the inner electrode each have holes that penetrate in the radial direction, and the fluid to be detected is guided through the holes between the outer circumferential surface of the first body of the outer electrode and the second body of the inner electrode, and between the projection of the outer electrode and the inner circumferential surface of the second body of the inner electrode.

[0007] In this invention, the outer circumferential surfaces of the main body of the outer electrode and the main body of the inner electrode face each other, and the fluid to be detected is guided between them. At the same time, the protruding portion of the outer electrode and the inner circumferential surface of the main body of the inner electrode face each other, and the fluid to be detected is guided between them. Therefore, by having a protruding portion on the outer electrode, the area in which the outer electrode and the inner electrode face each other can be increased without increasing the size of the outer electrode and the inner electrode, thereby improving the detection accuracy of the fluid property sensor.

[0008] The present invention is characterized in that the bottom surface of the outer electrode and the tip of the inner electrode face each other, and the fluid to be detected is guided between them through a hole.

[0009] In this invention, the bottom surface of the outer electrode and the tip of the inner electrode face each other, and the fluid to be detected is guided between them. Therefore, because the area where the outer electrode and the inner electrode face each other is larger, the detection accuracy of the fluid properties sensor can be further improved.

[0010] The present invention is characterized in that a bottom through-hole is formed in the bottom surface of the first main body portion of the outer electrode, which penetrates in the axial direction.

[0011] In this invention, the fluid to be detected, guided between the outer electrode and the inner electrode, is more easily discharged through the bottom through-hole, thereby improving the detection accuracy of the fluid properties sensor. [Effects of the Invention]

[0012] According to the present invention, the detection accuracy of the fluid property sensor can be improved. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing a fluid property sensor according to an embodiment of the present invention. [Figure 2] This is an exploded perspective view of a fluid property sensor according to an embodiment of the present invention. [Figure 3] This is a perspective view showing the substrate and fixing parts. [Figure 4] This is a perspective view showing the mounting points for the support and fixing parts. [Figure 5] This is a schematic diagram showing the first and second communication holes according to a modified example 4 of the present invention. [Figure 6] This is a schematic diagram showing the first and second communication holes according to a modified example 4 of the present invention. [Modes for carrying out the invention]

[0014] A fluid property sensor 100 according to an embodiment of the present invention will be described with reference to the drawings.

[0015] The fluid properties sensor 100 is attached, for example, directly to a fluid pressure device such as a hydraulic cylinder that drives a hydraulic fluid as the working fluid, or to piping connected to the fluid pressure device, and detects the properties of the hydraulic fluid. The fluid to be detected by the fluid properties detection sensor is not limited to hydraulic fluid, but may be various liquids or gases such as lubricating oil, cutting oil, fuel, solvent, or chemicals.

[0016] As shown in Figures 1 and 2, the fluid properties sensor 100 comprises a case 14 and a detection unit 20 housed in the case 14. The fluid properties sensor 100 outputs the detection values ​​detected by the detection unit 20 to an external computer, server, etc. (not shown). Specifically, the detection unit 20 calculates the relative permittivity and conductivity of the hydraulic fluid from the current value between the outer electrode 52 and the inner electrode 62, and outputs these as detection values ​​to the outside.

[0017] The case 14 is made of, for example, metal. The case 14 is formed in a cylindrical shape having a small diameter portion 14a and a large diameter portion 14b. The small diameter portion 14a is provided at the tip of the case 14 (left side in Figures 1 and 2) and is coaxial with the large diameter portion 14b. The outer electrode 52 is attached to the small diameter portion 14a by welding or the like. This makes the outer electrode 52 electrically connected to the case 14. The outer electrode 52 may also be attached to the small diameter portion 14a by screw coupling or press fitting. The inner electrode 62 is insulated and partially housed in the small diameter portion 14a. Specifically, the insulating support portion 70 of the detection unit 20, which will be described later, is housed across the small diameter portion 14a and the large diameter portion 14b, and the inner electrode 62 is held insulated from the case 14 by the support portion 70. This insulates the outer electrode 52 from the inner electrode 62. The large-diameter portion 14b of the case 14 houses the plate 76, substrate 80, and substrate support portion 90 of the detection unit 20, which will be described later. A lid portion 16 is provided at the opening of the large-diameter portion 14b. The lid portion 16 is made of, for example, metal and is fixed to the large-diameter portion 14b by screws 17. The lid portion 16 is provided with a connector (not shown) for electrical connection to the outside.

[0018] The detection unit 20 comprises an outer electrode 52 with a bottomed cylindrical tip, an inner electrode 62 with an open tip 62a provided inside the outer electrode 52, an insulating support portion 70 for insulating the outer electrode 52 and the inner electrode 62 and supporting the inner electrode 62 inside the case 14, a plate 76 as a fixing portion which is fixed to the case 14 and to which the support portion 70 is attached by screws 93 (see Figure 4) as fixing members, and a substrate 80 as a detection portion which is attached to the plate 76 and provided inside the case 14.

[0019] As shown in FIGS. 1 and 2, the outer electrode 52 is provided such that the bottom surface 52b side protrudes from the small-diameter portion 14a of the case 14. The outer electrode 52 has a cylindrical first main body portion 52a facing the outer peripheral surface of the inner electrode 62, and a protruding portion 52c formed to protrude from the bottom surface 52b of the first main body portion 52a. The outer diameter of the first main body portion 52a is formed to be substantially the same as the inner diameter of the small-diameter portion 14a of the case 14, and the axial end portion is attached to the inner peripheral surface of the small-diameter portion 14a by welding or the like. A bottom surface through-hole 52d penetrating axially is formed in a part of the outer peripheral side of the bottom surface 52b. The protruding portion 52c is formed to have a smaller diameter than the inner peripheral surface of the inner electrode 62. The protruding portion 52c protrudes into the inner electrode 62 through the opening 62b of the inner electrode 62 and faces the inner peripheral surface of the inner electrode 62 (see FIG. 1). A circular first communication hole 53 penetrating in the radial direction is formed in the first main body portion 52a of the outer electrode 52. In the present embodiment, the first communication holes 53 are formed at equal intervals with a predetermined angle α (see FIG. 2). In the present embodiment, four first communication holes 53 are formed with an interval of 90 degrees (α = 90°) in the circumferential direction between the centers of each (see FIG. 2).

[0020] As shown in FIG. 1, the inner electrode 62 is provided coaxially with the outer electrode 52, and the tip portion 62a is provided to protrude from the small-diameter portion 14a of the case 14. The inner electrode 62 has a bottomed cylindrical second main body portion 62c, and a mounting portion 62d formed to extend from the bottom surface of the second main body portion 62c to the side opposite to the tip portion 62a and attached to the support portion 70. The second main body portion 62c is provided so as to enter between the first main body portion 52a and the protruding portion 52c of the outer electrode 52. The outer peripheral surface of the second main body portion 62c faces the inner peripheral surface of the first main body portion 52a of the outer electrode 52, the tip portion 62a faces the bottom surface 52b of the first main body portion 52a of the outer electrode 52, and the inner peripheral surface of the second main body portion 62c faces the outer peripheral surface of the protruding portion 52c of the outer electrode 52. A gap is formed between the inner peripheral surface of the first main body portion 52a of the outer electrode 52 and the outer peripheral surface of the second main body portion 62c of the inner electrode 62, and a gap is formed between the outer peripheral surface of the protruding portion 52c of the outer electrode 52 and the inner peripheral surface of the second main body portion 62c of the inner electrode 62. Also, a gap is formed between the bottom surface 52b of the first main body portion 52a of the outer electrode 52 and the tip portion 62a of the inner electrode 62.

[0021] In the second main body portion 62c of the inner electrode 62, a circular second communication hole 63 penetrating in the radial direction is formed. In the present embodiment, the second communication holes 63 are formed at equal intervals with the same predetermined angle α as the first communication holes 53. Specifically, four second communication holes 63 are formed at intervals of 90 degrees in the circumferential direction, similarly to the first communication holes 53 (see FIGS. 2 and 4). Further, the second communication holes 63 are formed to have the same diameter as the first communication holes 53. The inner electrode 62 is positioned and provided such that the second communication holes 63 face the first communication holes 53 of the outer electrode 52 (in other words, the center positions of the first communication holes 53 and the second communication holes 63 coincide). Thereby, the working oil is smoothly guided between the outer electrode 52 and the inner electrode 62. Specifically, through the first communication holes 53 and the second communication holes 63, the working oil is guided between the inner circumferential surface of the first main body portion 52a of the outer electrode 52 and the outer circumferential surface of the second main body portion 62c of the inner electrode 62, between the bottom surface 52b of the outer electrode 52 and the tip portion 62a of the inner electrode 62, and between the protruding portion 52c of the outer electrode 52 and the inner circumferential surface of the second main body portion 62c of the inner electrode 62. Thereby, the inner electrode 62 and the outer electrode 52 are electrically connected, and the relative permittivity and conductivity of the working oil can be detected from the current value between the outer electrode 52 and the inner electrode 62. Details of the method for positioning the inner electrode 62 in the circumferential direction will be described later.

[0022] The attachment portion 62d is formed to have a smaller diameter than the second main body portion 62c, and a male screw portion (not shown) is formed on the outer circumferential surface. The attachment portion 62d is attached to the support portion 70 by being screwed to a female screw portion (not shown) formed on the support portion 70. An annular seal member 30 such as an O-ring is provided at the step portion between the second main body portion 62c and the attachment portion 62d of the inner electrode 62, and the seal member 30 seals between the inner electrode 62 and the support portion 70. Hereinafter, the circumferential direction of the inner electrode 62 will also be simply referred to as the "circumferential direction".

[0023] The support portion 70 is formed of an insulating material such as resin. As shown in Figures 1 to 4, the support portion 70 is formed in a cylindrical shape and is provided across the small diameter portion 14a and the large diameter portion 14b of the case 14 (see Figure 1). The support portion 70 has a cylindrical main body portion 70a to which the inner electrode 62 is attached, a flange portion 70b which is formed to be larger in diameter than the main body portion 70a and attached to the plate 76 (see Figures 1, 2, and 4), and an adjustment hole 73 for adjusting the relative position of the support portion 70 and the inner electrode 62 in the circumferential direction of the inner electrode 62 (see Figures 2 and 4).

[0024] As shown in Figure 1, the main body portion 70a is formed with an outer diameter approximately the same as the inner diameter of the small diameter portion 14a of the case 14, and is inserted into the small diameter portion 14a. A sealing member 31, such as an O-ring, is provided between the outer circumferential surface of the main body portion 70a and the inner circumferential surface of the small diameter portion 14a. A female threaded portion is formed on the inner circumferential surface of the hollow portion 70c of the support portion 70 on the side of the main body portion 70a (left side in Figure 1), and the male threaded portion of the mounting portion 62d of the inner electrode 62 is screw-connected and attached to it. A conductor 78 extending in the axial direction is provided in the hollow portion 70c, with one end of the conductor 78 electrically connected to the inner electrode 62 and the other end electrically connected to the substrate 80. As a result, the inner electrode 62 is electrically connected to the substrate 80 through the conductor 78.

[0025] As shown in Figures 2 and 4, the flange portion 70b is formed in a fan shape with a portion of its circumference missing. An adjustment hole 73 is formed in the flange portion 70b, passing through it axially. The support portion 70 and the inner electrode 62 are fixed to the plate 76 by inserting and fastening a screw 93 through the adjustment hole 73.

[0026] The adjustment holes 73 are formed in pairs on either side of the main body portion 70a (adjustment holes 73a and 73b). The pair of adjustment holes 73a and 73b are formed in a symmetrical shape on either side of the main body portion 70a. Each of the pair of adjustment holes 73a and 73b consists of multiple holes formed at intervals in the circumferential direction of the inner electrode 62. In this embodiment, as shown in Figure 4, the adjustment holes 73a consist of a first hole 74a, a second hole 74b, a third hole 74c, a fourth hole 74d, and a fifth hole 74e, and the adjustment holes 73b consist of a first hole 75a, a second hole 75b, a third hole 75c, a fourth hole 75d, and a fifth hole 75e. In Figure 4, the hidden third hole 74c, fourth hole 74d, and fifth hole 74e, as well as the screw 93, are shown by dotted lines. Each of the pair of adjustment holes 73a and 73b has an internal threaded portion (not shown) formed on its inner surface, and a screw 93 is fastened to the internal threaded portion. The first hole 74a, second hole 74b, third hole 74c, fourth hole 74d, and fifth hole 74e of adjustment hole 73a are opposite the first hole 75a, second hole 75b, third hole 75c, fourth hole 75d, and fifth hole 75e of adjustment hole 73b, respectively, straddling the central axis of the inner electrode 62. In other words, each of the holes in the pair of adjustment holes 73a and 73b is arranged symmetrically with respect to the central axis of the inner electrode 62. Therefore, bolts can be fastened to the opposing holes of the pair of adjustment holes 73a and 73b, respectively, and the support portion 70 can be fixed to the plate 76 at a position 180 degrees apart.

[0027] Each of the pair of adjustment holes 73a and 73b is formed in a circular shape and is located on the circumference of a single circle concentric with the inner electrode 62. The pair of adjustment holes 73a and 73b are formed over an angular range of a predetermined angle α (in this embodiment, an angular range of 90 degrees), which is the interval between the formation of the first communication hole 53 and the second communication hole 63. Specifically, the angle γ (see Figure 4) between the center of the first hole 74a and the center of the fifth hole 74e, which are the ends of the adjustment hole 73a, is the same as the predetermined angle α. Each of the pair of adjustment holes 73a and 73b is formed at equal intervals in the circumferential direction, and in this embodiment, each of the pair of adjustment holes 73a and 73b consists of five holes. Therefore, the angle β between adjacent holes in the circumferential direction (specifically, the angle between the centers of adjacent holes in the circumferential direction) is one-quarter of angles γ and α. The relative positions of the pair of adjustment holes 73a and 73b into which the screws 93 are fastened determine the relative positions of the support portion 70 and the inner electrode 62 with respect to the plate 76, and as a result, the relative position of the inner electrode 62 with respect to the outer electrode 52 is determined.

[0028] As shown in Figures 1 to 4, the plate 76 is formed in a disc shape and is made of, for example, a highly rigid metal. The plate 76 has a disc portion 76a, a notch 76b formed in a part of the outer edge of the disc portion 76a (see Figures 2 to 4), a plurality of first insertion holes 76c (see Figure 4) through which screws 91 for fixing the plate 76 to the case 14 are inserted, a second insertion hole 76d (see Figures 1 and 3) formed in the center through which a conductor 78 is inserted so as not to conduct electricity, and a third insertion hole 76e (see Figure 3) through which a screw 93 for attaching the support portion 70 to the plate 76 is inserted.

[0029] As shown in Figure 1, the disc portion 76a of the plate 76 is provided in contact with the stepped portion 14c at the boundary between the small diameter portion 14a and the large diameter portion 14b of the case 14. As shown in Figures 2 to 4, the notch 76b is formed to penetrate the disc portion 76a in the axial direction. Through the notch 76b, the connecting portion 79, which is electrically connected to the substrate 80, contacts the case 14, thereby electrically connecting the outer electrode 52 to the substrate 80 through the case 14 and the connecting portion 79. As shown in Figure 4, in this embodiment, four first insertion holes 76c are formed at intervals in the circumferential direction, and screws 91 are inserted through them, aligned with a plurality of fastening holes (not shown) formed in the stepped portion 14c of the case 14. This attaches the plate 76 to the case 14.

[0030] As shown in Figure 3, two third insertion holes 76e are formed on either side of the second insertion hole 76d. The two second insertion holes 76d are formed corresponding to the positions of the pair of adjustment holes 73a and 73b. Specifically, the two second insertion holes 76d are formed concentrically with the inner electrode 62 so as to overlap with one of the pair of adjustment holes 73a and 73b. The support portion 70 and the inner electrode 62 are fixed to the plate 76 by inserting and fastening screws 93 (see Figure 4) through the two second insertion holes 76d and one of the pair of adjustment holes 73a and 73b. A force acts on the inner electrode 62 toward the case 14 due to the pressure of the hydraulic fluid, but because the plate 76 is made of a highly rigid metal, the position of the inner electrode 62 is maintained by the plate 76.

[0031] An L-shaped substrate support portion 90 that supports the substrate 80 is attached to the disc portion 76a by screws 94. This fixes the substrate 80 to the plate 76.

[0032] The substrate 80 is a printed circuit board on which the wiring section is formed. The substrate 80 is attached to the substrate support section 90 by screws 92 and then attached to the plate 76 through the substrate support section 90 (see Figures 1 to 3). An L-shaped conductive connector 79 is provided at the end of the substrate 80 (see Figures 2 to 4). The connector 79 contacts the stepped section 14c of the case 14 through a notch 76b of the plate 76 and is fixed to the stepped section 14c by screws or the like (not shown). As a result, the outer electrode 52 is electrically connected to the substrate 80 through the case 14 and the connector 79. When the outer electrode 52 is grounded, it is not susceptible to external electrical noise, and a cover to protect the outer electrode 52 is not required, thus allowing the fluid property sensor 100 to be miniaturized. The substrate 80 is also electrically connected to the inner electrode 62 through a conductor 78.

[0033] Signals are input to the substrate 80 from the outer electrode 52 and the inner electrode 62. The substrate 80 detects the current flowing between the outer electrode 52 and the inner electrode 62 in a detection circuit (not shown) that is mounted on it. The current value detected by the detection circuit is output as the electrical characteristics of the hydraulic fluid to a control circuit (not shown) mounted on the substrate 80, where the conductivity and relative permittivity of the hydraulic fluid are calculated. The calculated conductivity and relative permittivity of the hydraulic fluid are output to an external computer or server via a connector (not shown), etc.

[0034] In order to smoothly guide the hydraulic fluid between the outer electrode 52 and the inner electrode 62, it is necessary to align the circumferential positions (specifically, the center positions of both) of the first communication hole 53 and the second communication hole 63 of the outer electrode 52 and the inner electrode 62 with each other. In the fluid property sensor 100 of this embodiment, since the inner electrode 62 is attached to the support part 70 by screw coupling, the circumferential position of the inner electrode 62 after screw coupling is not constant, and the circumferential position of the first communication hole 53 of the inner electrode 62 is also not constant. Therefore, the circumferential position of the inner electrode 62 is adjusted using a pair of adjustment holes 73a and 73b of the support part 70 so that the circumferential positions of the first communication hole 53 and the second communication hole 63 are aligned with each other.

[0035] Next, we will explain in detail the method for positioning the inner electrode 62 in the circumferential direction.

[0036] The circumferential positioning of the inner electrode 62 is performed in the state shown in Figure 2, when the outer electrode 52 is attached to the case 14, the inner electrode 62 is screw-connected to the support part 70, and the substrate 80 is attached to the plate 76, with each part forming an assembly. First, the opposing holes of either of the pair of adjustment holes 73a, 73b of the support part 70 (for example, the third hole 74c of adjustment hole 73a and the third hole 75c of adjustment hole 73b as shown in Figure 4) and the two second insertion holes 76d of the plate 76 are overlapped, and screws 93 are inserted and temporarily fastened to create an assembly 95. Then, the temporarily fastened assembly 95 is temporarily placed in the case 14 in the direction in which the plate 76 is attached to the stepped portion 14c of the case 14 (specifically, by aligning the first insertion hole 76c of the plate 76 with the fastening hole of the stepped portion 14c of the case 14). In this state, the circumferential misalignment between the first communication hole 53 of the outer electrode 52 and the second communication hole 63 of the inner electrode 62 is checked. Then, the temporarily fixed assembly 95 is removed from the case 14, the screws 93 are removed to release the temporary fastening, and the support part 70 is rotated according to the circumferential misalignment between the first communication hole 53 and the second communication hole 63 to adjust the circumferential position of the support part 70 and the inner electrode 62.

[0037] Specifically, when screws 93 are inserted into the third hole 74c of adjustment hole 73a and the third hole 75c of adjustment hole 73b and temporarily fastened, if the circumferential position of the first communication hole 53 is shifted by, for example, 45 degrees relative to the second communication hole 63, the support part 70 is rotated 45 degrees clockwise or counterclockwise to align the first hole 74a of adjustment hole 73a and the first hole 75a of adjustment hole 73b, or the fifth hole 74e of adjustment hole 73a and the fifth hole 75e of adjustment hole 73b, with the two second insertion holes 76d. Then, screws 93 are inserted and fastened to create the assembly 95, which is then housed and installed in the case 14. This aligns the circumferential position of the first communication hole 53 and the second communication hole 63. Furthermore, if the circumferential misalignment between the first communication hole 53 and the second communication hole 63 does not align with the positions of the pair of adjustment holes 73a and 73b, and the positions of the first communication hole 53 and the second communication hole 63 cannot be precisely aligned even by rotating the support part 70, the positioning should be adjusted so that the positions of the first communication hole 53 and the second communication hole 63 are as close as possible. Also, if the orientation in which the plate 76 will be attached to the stepped portion 14c of the case 14 is known in advance, it is not necessarily required to temporarily install the assembly 95 into the case 14.

[0038] Thus, in the fluid properties sensor 100 of this embodiment, the outer circumferential surfaces of the first main body portion 52a of the outer electrode 52 and the second main body portion 62c of the inner electrode 62 face each other, and hydraulic fluid is guided between them. At the same time, the protruding portion 52c of the outer electrode 52 and the inner circumferential surface of the second main body portion 62c of the inner electrode 62 face each other, and hydraulic fluid is guided between them. Therefore, by having the outer electrode 52 have the protruding portion 52c, the area in which the outer electrode 52 and the inner electrode 62 face each other can be increased without increasing the size of the outer electrode 52 and the inner electrode 62, thereby improving the detection accuracy of the fluid properties sensor 100.

[0039] Furthermore, in the fluid properties sensor 100 of this embodiment, a bottom through-hole 52d is formed in the bottom surface 52b of the first main body portion 52a of the outer electrode 52, which penetrates in the axial direction. This makes it easier for the hydraulic fluid guided between the outer electrode 52 and the inner electrode 62 to be discharged through the bottom through-hole 52d, thus preventing hydraulic fluid from accumulating between the outer electrode 52 and the inner electrode 62. Therefore, the detection accuracy of the fluid properties sensor 100 can be improved.

[0040] Furthermore, in the fluid properties sensor 100 of this embodiment, the inner electrode 62 is attached to the support portion 70 by screw coupling. In other words, since the inner electrode 62 is not integrally molded with the support portion 70, a dedicated mold for integral molding is not required. Therefore, in the production of fluid properties sensors 100 in small quantities, the preparation of a dedicated mold is not required, thus improving productivity. In addition, in the fluid properties sensor 100, the inner electrode 62 is attached to the support portion 70 by screw coupling, and the support portion 70 is attached to the plate 76 by inserting a screw 93 through the adjustment hole 73, thereby fixing the inner electrode 62 to the case 14. Thus, by adjusting the position through which the screw 93 is inserted in the adjustment hole 73, the circumferential position of the inner electrode 62 can be adjusted, and the position of the second communication hole 63 of the inner electrode 62 can be easily aligned with the position of the first communication hole 53 of the outer electrode 52.

[0041] Furthermore, in the fluid property sensor 100 of this embodiment, a pair of adjustment holes 73a and 73b are formed within the same range as the angle α between the first communication holes 53 of the outer electrode 52. Therefore, when the inner electrode 62 is installed, the circumferential position of the inner electrode 62 can be adjusted within the range of angle α. Since the positional difference between the first communication hole 53 of the outer electrode 52 and the second communication hole 63 of the inner electrode 62 is within angle α, the position of the first communication hole 53 can be aligned with the position of the second communication hole 63.

[0042] According to the above-described embodiment, the following effects are achieved.

[0043] In the fluid properties sensor 100, the outer circumferential surfaces of the first main body portion 52a of the outer electrode 52 and the second main body portion 62c of the inner electrode 62 face each other, and hydraulic fluid is guided between them. Simultaneously, the protruding portion 52c of the outer electrode 52 and the inner circumferential surface of the second main body portion 62c of the inner electrode 62 face each other, and hydraulic fluid is guided between them. Therefore, the area in which the outer electrode 52 and the inner electrode 62 face each other can be increased, thereby improving the detection accuracy of the fluid properties sensor 100.

[0044] In the fluid properties sensor 100, the circumferential position of the inner electrode 62 can be adjusted by adjusting the position through which the screw 93 is inserted in the adjustment hole 73, and the position of the second communication hole 63 of the inner electrode 62 can be easily aligned with the position of the first communication hole 53 of the outer electrode 52.

[0045] Next, modifications of this embodiment will be described. The following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configurations described in the above embodiments, or to combine the configurations described in the following different modifications.

[0046] <Example 1> In the above embodiment, the support portion 70 has a pair of adjustment holes 73a and 73b for adjusting the relative position between the support portion 70 and the inner electrode 62 in the circumferential direction of the inner electrode 62. However, the plate 76 may also have a pair of adjustment holes 73a and 73b. In this configuration, two second insertion holes 76d are formed in the flange portion 70b of the support portion 70.

[0047] <Modification 2> In the above embodiment, each of the pair of adjustment holes 73a and 73b is formed in a circular shape and is formed in multiple locations spaced apart in the circumferential direction. However, the pair of adjustment holes 73a and 73b may each be formed by a single elongated hole extending in the circumferential direction. In this case, a female threaded portion is formed on the inner circumferential surface of the second insertion hole 76d, which is fastened with the screw 93.

[0048] <Variation 3> In the above embodiment, a pair of adjustment holes 73a and 73b are formed within an angle (α) range between the first communication holes 53 of the outer electrode 52. However, the angle range in which the pair of adjustment holes 73a and 73b are formed is not limited to this and may be smaller than the angle (α) between the first communication holes 53. Even with this configuration, the positions of the first communication hole 53 and the second communication hole 63 can be brought closer together, improving the flow of hydraulic fluid between the outer electrode 52 and the inner electrode 62.

[0049] <Modification 4> In the above embodiment, the first communication hole 53 of the outer electrode 52 and the second communication hole 63 of the inner electrode 62 are formed in a circular shape with the same diameter. However, the first communication hole 53 and the second communication hole 63 may be formed as, for example, elongated holes extending in the circumferential direction, or as circular holes in which one has a larger diameter than the other.

[0050] The center positions of the first communication hole 53 and the second communication hole 63 are adjusted by rotating the support part 70 to align the pair of adjustment holes 73a and 73b with the second insertion hole 76d of the plate 76. Since the pair of adjustment holes 73a and 73b are multiple holes formed with an angle β in the circumferential direction, if the center positions of the first communication hole 53 and the second communication hole 63 coincide when the second insertion hole 76d is located between adjacent holes in the circumferential direction of the pair of adjustment holes 73a and 73b, the screw 93 cannot be inserted. In this case, the second insertion hole 76d is aligned with the hole closest to the point where the center positions of the first communication hole 53 and the second communication hole 63 coincide, so the center positions of the first communication hole 53 and the second communication hole 63 are shifted, by up to half of the angle β. In the configuration of the above embodiment, since the first communication hole 53 and the second communication hole 63 are circles with the same inner diameter, even if the first communication hole 53 and the second communication hole 63 are offset by a maximum of β / 2 in the circumferential direction (in other words, offset by an angular range of β in the circumferential direction), the flow of hydraulic fluid between the outer electrode 52 and the inner electrode 62 can be ensured. However, there is a possibility that the first communication hole 53 does not overlap with the second communication hole 63 and the inner electrode 62 in the radial direction. Therefore, it is preferable that the first communication hole 53 and the second communication hole 63 be formed so that they overlap at least a minimum, even if they are offset by a maximum of β / 2 in the circumferential direction. In other words, the first communication hole 53 and the second communication hole 63 are formed so that, when the relative positions of the outer electrode 52 and the inner electrode 62 are adjusted within the range of angle β, the first communication hole 53 and the second communication hole 63 overlap by a predetermined area or more in the radial direction of the inner electrode 62. The "determined area" is the area necessary to guide the hydraulic fluid smoothly between the outer electrode 52 and the inner electrode 62, and can be determined, for example, by experimentation. In this configuration, even if the center positions of the first communication hole 53 and the second communication hole 63 cannot be precisely aligned, they can be positioned so that they overlap by a predetermined area or more, improving the fluidity of the hydraulic fluid between the outer electrode 52 and the inner electrode 62.

[0051] Furthermore, it is more preferable that the first communication hole 53 and the second communication hole 63 are formed such that even if they are offset by up to β / 2 in the circumferential direction, the entirety of one overlaps the other. In the modified examples shown in Figures 5 and 6, the first communication hole 53 is formed as an elongated hole extending in the circumferential direction (see Figure 5) or as a circular hole with a larger diameter than the second communication hole 63 (see Figure 6), and is formed so that even if it is offset by up to β / 2 in the circumferential direction, the entirety of the second communication hole 63 overlaps the first communication hole 53. The first communication hole 53 is formed over an angle β range between adjacent holes in the circumferential direction of the pair of adjustment holes 73a and 73b. Figures 5(a) and 6(a) show a state in which the center positions of the first communication hole 53 and the second communication hole 63 overlap, with the second insertion hole 76d located between adjacent holes in the circumferential direction of the pair of adjustment holes 73a and 73b. Figures 5(b) and 5(c) show the state in which the hole is aligned with the second insertion hole 76d from the state in Figure 5(a), and the second communication hole 63 is shifted by β / 2 in one direction (Figure 5(b)) and the other direction (Figure 5(c)) relative to the first communication hole 53 in the circumferential direction. Similarly, Figures 6(b) and 6(c) show the state in which the second communication hole 63 is shifted by β / 2 in one direction (Figure 6(b)) and the other direction (Figure 6(c)) relative to the first communication hole 53 from the state in Figure 6(a). In this configuration, even if the center positions of the first communication hole 53 and the second communication hole 63 cannot be precisely aligned, the entire second communication hole 63 can be positioned to overlap the first communication hole 53, as shown in Figures 5(b) and 6(b) and 6(c), and the fluidity of the hydraulic fluid between the outer electrode 52 and the inner electrode 62 is improved. In other words, the first communication hole 53 and the second communication hole 63 are formed such that, when the relative positions of the outer electrode 52 and the inner electrode 62 are adjusted within the range of angle β, the entirety of one of the first communication hole 53 and the second communication hole 63 overlaps the other in the radial direction of the inner electrode 62.

[0052] <Modification 5> In the above embodiment, the first communication hole 53 of the outer electrode 52 and the second communication hole 63 of the inner electrode 62 are aligned using the pair of adjustment holes 73a and 73b of the support portion 70. However, the method of aligning the first communication hole 53 and the second communication hole 63 is not limited to the above. Furthermore, the inner electrode 62 does not have to be attached to the support portion 70 by screw coupling or press-fitting, and may be integrally molded and provided on the support portion 70.

[0053] <Variation 6> In the above embodiment, the inner electrode 62 has a bottomed cylindrical second body portion 62c and a mounting portion 62d that extends from the bottom surface of the second body portion 62c to the side opposite to the tip portion 62a and is attached to the support portion 70. However, the inner electrode 62 may be formed as a bottomed cylindrical shape having only the second body portion 62c. In this configuration, the second body portion 62c is attached to the support portion 70.

[0054] The configuration, operation, and effects of the embodiment of the present invention configured as described above will be summarized below.

[0055] A fluid property sensor 100 for detecting the properties of a target fluid comprises an outer electrode 52 having a bottomed cylindrical tip and a second body portion 62c having an opening at the tip 62a, and an inner electrode 62 provided inside the outer electrode 52, wherein the outer electrode 52 has a cylindrical first body portion 52a facing the outer circumferential surface of the second body portion 62c of the inner electrode 62, and the inner electrode 62 is formed to protrude from the bottom surface 52b of the first body portion 52a through the opening 62b into the second body portion 62c of the inner electrode 62, The electrode 62 has a protrusion 52c facing the inner circumferential surface of the second body portion 62c, and holes (first communication hole 53, second communication hole 63) that penetrate radially are formed in the first body portion 52a of the outer electrode 52 and the second body portion 62c of the inner electrode 62, respectively, and the fluid to be detected is guided through the holes between the outer circumferential surface of the first body portion 52a of the outer electrode 52 and the second body portion 62c of the inner electrode 62, and between the protrusion 52c of the outer electrode 52 and the inner circumferential surface of the second body portion 62c of the inner electrode 62.

[0056] In this configuration, the outer circumferential surfaces of the first main body portion 52a of the outer electrode 52 and the second main body portion 62c of the inner electrode 62 face each other, and the fluid to be detected is guided between them. At the same time, the protruding portion 52c of the outer electrode 52 and the inner circumferential surface of the second main body portion 62c of the inner electrode 62 face each other, and the fluid to be detected is guided between them. Therefore, by having the outer electrode 52 have the protruding portion 52c, the area in which the outer electrode 52 and the inner electrode 62 face each other can be increased without increasing the size of the outer electrode 52 and the inner electrode 62, thereby improving the detection accuracy of the fluid property sensor 100.

[0057] Furthermore, in the fluid properties sensor 100, the bottom surface 52b of the outer electrode 52 and the tip portion 62a of the inner electrode 62 face each other, and the fluid to be detected is guided between them through the hole.

[0058] In this configuration, the bottom surface 52b of the outer electrode 52 and the tip 62a of the inner electrode 62 face each other, and the fluid to be detected is guided between them. Therefore, since the area where the outer electrode 52 and the inner electrode 62 face each other is larger, the detection accuracy of the fluid property sensor 100 can be further improved.

[0059] Furthermore, in the fluid properties sensor 100, a bottom through-hole 52d is formed in the bottom surface 52b of the first main body portion 52a of the outer electrode 52, which penetrates in the axial direction.

[0060] In this configuration, the fluid to be detected, guided between the outer electrode 52 and the inner electrode 62, is more easily discharged through the bottom through-hole 52d, thereby improving the detection accuracy of the fluid properties sensor 100.

[0061] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. [Explanation of Symbols]

[0062] 52…Outer electrode, 52a…First body part, 52b…Bottom surface, 52c…Protrusion, 52d…Bottom surface through hole, 53…First connecting hole (hole), 62…Inner electrode, 62a…Tip end, 62b…Opening, 62c…Second body part, 63…Second connecting hole (hole), 100…Fluid properties

Claims

1. A fluid properties sensor for detecting the properties of a target fluid, The tip has a bottomed cylindrical outer electrode, It has a second main body portion with an opening at the tip, and an inner electrode provided inside the outer electrode, The outer electrode is, The inner electrode comprises a cylindrical first main body portion facing the outer circumferential surface of the second main body portion, The inner electrode has a projection that extends from the bottom surface of the first main body through the opening and protrudes from the second main body of the inner electrode, and has a projection that faces the inner circumferential surface of the second main body of the inner electrode, A fluid properties sensor characterized in that the first main body of the outer electrode and the second main body of the inner electrode each have holes that penetrate in the radial direction, and the fluid to be detected is guided through these holes between the outer peripheral surface of the first main body of the outer electrode and the second main body of the inner electrode, and between the protruding portion of the outer electrode and the inner peripheral surface of the second main body of the inner electrode.

2. A fluid property sensor according to claim 1, A fluid properties sensor characterized in that the bottom surface of the outer electrode and the tip of the inner electrode face each other, and the fluid to be detected is guided between them through the hole.

3. A fluid property sensor according to claim 1, A fluid properties sensor characterized in that a bottom through-hole is formed in the bottom surface of the first main body portion of the outer electrode, which penetrates in the axial direction.

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