Clearance Sensor

Abstract

To provide a clearance sensor capable of suppressing the decrease in reliability during long-term measurement.SOLUTION: The clearance sensor includes; a cylindrical sensing electrode having a detection end face at one end in the axial direction of the central axis; an electrode material that includes a guard electrode and a ground electrode the central axis thereof is coaxial with the detection electrode; an insulating material connecting the detection electrode and the guard electrode, and connecting the guard electrode and the ground electrode; and insulating layers filled between the sensing electrode, the guard electrode, the ground electrode, and the insulating material. The electrode material and the insulating material are locked in at least one of the axial directions of the central axis and the direction around the axis.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a clearance sensor. [Background technology]

[0002] Rotary machines such as axial compressors having a plurality of rotor blades rotating in a cylindrical casing are known. In this type of rotary machine, a tip clearance sensor is provided to measure the tip clearance between the casing and the rotor blades, and the measured tip clearance value is kept appropriate. For this tip clearance sensor, for example, a non-contact sensor such as a capacitance sensor is used (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6431665 Summary of the Invention [Problem to be solved by the invention]

[0004] The clearance sensor described in Patent Document 1 has a triple structure of a detection electrode, a guard electrode, and a ground electrode, which are all coaxial with each other, and an insulating layer is disposed between each electrode. In such a clearance sensor, the insulating layer is attached by, for example, thermal spraying, and the electrodes are assembled while adjusting the fit. As a result, the assembly precision varies greatly, and there is a possibility that reliability will decrease when, for example, the tip clearance as described above is measured for a long period of time.

[0005] The present disclosure has been made in consideration of the above, and has an object to provide a clearance sensor that can suppress deterioration in reliability during long-term measurement. [Means for solving the problem]

[0006] The clearance sensor according to the present disclosure comprises a cylindrical detection electrode having a detection end face at one end side in the axial direction of a central axis, an electrode member including a guard electrode and a ground electrode which are coaxial with the detection electrode, an insulating member which connects the detection electrode to the guard electrode and also connects the guard electrode to the ground electrode, and an insulating layer which is filled between the detection electrode, the guard electrode, the ground electrode, and the insulating member, and the electrode member and the insulating member are engaged in at least one of the axial direction and the direction around the central axis.

[0007] The clearance sensor according to the present disclosure comprises a cylindrical detection electrode having a detection end face at one end side in the axial direction of a central axis, an electrode member including a guard electrode and a ground electrode which are coaxial with the detection electrode, an insulating member which connects the detection electrode to the guard electrode and also connects the guard electrode to the ground electrode, an insulating layer filled between the detection electrode, the guard electrode, the ground electrode and the insulating member, and a cooling flow path which penetrates the electrode member and the insulating member along the axial direction of the central axis. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a clearance sensor capable of suppressing deterioration in reliability during long-term measurement. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of a clearance sensor according to the present embodiment. [Diagram 2] FIG. 2 is a diagram showing another example of the clearance sensor according to the present embodiment. [Diagram 3] FIG. 3 is a diagram showing another example of the clearance sensor according to the present embodiment. [Figure 4] FIG. 4 is a diagram showing another example of the clearance sensor according to the present embodiment. [Diagram 5] FIG. 5 is a diagram showing a configuration along the AA cross section in FIG. [Figure 6] FIG. 6 is a view showing a configuration along the cross section BB in FIG. [Figure 7] FIG. 7 is a diagram showing another example of the clearance sensor according to the present embodiment. [Figure 8] FIG. 8 is a diagram showing a configuration along the CC cross section in FIG. [Figure 9] FIG. 9 is a diagram showing a configuration along the cross section DD in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the clearance sensor according to the present disclosure will be described with reference to the drawings. Note that the present invention is not limited to the embodiment. In addition, the components in the following embodiments include those that are replaceable and easy for a person skilled in the art, or those that are substantially the same.

[0011] FIG. 1 is a diagram showing an example of a clearance sensor 100 according to this embodiment. FIG. 1 shows an example of a cross-sectional configuration along a plane passing through a central axis AX. The clearance sensor 100 shown in FIG. 1 is a capacitance sensor. The clearance sensor 100 can be used, for example, when measuring a tip clearance between a casing and a rotor blade of an axial compressor having a plurality of rotor blades that rotate within a cylindrical casing such as a gas turbine. The clearance sensor 100 includes an electrode member 10, an insulating member 20, and an insulating layer 30.

[0012] The electrode member 10 includes a detection electrode 11, a guard electrode 12, and a ground electrode 13. The electrode member 10 is formed using, for example, a metal or an alloy such as stainless steel. The detection electrode 11, the guard electrode 12, and the ground electrode 13 are coaxial with a central axis AX, and are provided in triplicate in the radial direction.

[0013] The detection electrode 11 is a cylindrical electrode centered on the central axis AX. The detection electrode 11 has a detection end face 11a at one end in the axial direction of the central axis AX. Hereinafter, when describing the positional relationship of the clearance sensor 100, the side of the detection end face 11a in the axial direction of the central axis AX may be referred to as the tip side, and the opposite side to the detection end face 11a side may be referred to as the base side. The clearance sensor 100 measures the tip clearance with the detection end face 11a disposed at a corresponding position on the inner circumferential surface of the casing.

[0014] The detection electrode 11 is connected to, for example, an inorganic insulated (MI) cable. The MI cable has a wiring portion 14, a tubular member 15, and a tubular part 16. The MI cable has a triple structure of the wiring portion 14, the tubular member 15, and the tubular part 16, and an insulator such as magnesium oxide is filled between each part. The wiring portion 14 is joined to the detection electrode 11 by welding or the like. The wiring portion 14 is arranged so as to extend from the detection electrode 11 to the other end side in the axial direction of the central axis AX. The wiring portion 14 is connected to a processing device (not shown) or the like. The wiring portion 14 can be arranged on the central axis AX, for example. The tubular member 15 is joined to a guard base 12b (described later) by welding or the like. The tubular part 16 is joined to a ground base 13b (described later) by welding or the like.

[0015] The detection electrode 11 has a recess 11d on the end face 11b on the base end side. The recess 11d has a cylindrical shape hollowed out from the end face 11b toward the tip end side. The inner circumferential surface of the recess 11d is a cylindrical surface. A screw thread 11e is formed on the inner circumferential surface of the recess 11d. The screw thread 11e is formed in a spiral shape on the inner circumferential surface of the recess 11d from the base end side to the tip end side.

[0016] The guard electrode 12 has a cylindrical guard portion 12a centered on the central axis AX and a cylindrical guard base portion 12b centered on the central axis AX. The guard electrode 12 and the detection electrode 11 have the same central axis.

[0017] The guard cylindrical portion 12a surrounds the outer peripheral surface 11c of the detection electrode 11. The guard cylindrical portion 12a is disposed with a predetermined gap between it and the outer peripheral surface 11c of the detection electrode 11. The end face on the tip side of the guard cylindrical portion 12a is flush with the detection end face 11a of the detection electrode 11.

[0018] The guard base 12b is disposed on the other end side in the axial direction of the central axis AX with respect to the detection electrode 11. The guard base 12b is connected to the guard cylindrical portion 12a by, for example, welding.

[0019] The guard base 12b has a recess 12d on the end face 12c on the tip side. The recess 12d has a cylindrical shape hollowed out from the end face 12c toward the base end side. The inner peripheral surface of the recess 12d is a cylindrical surface. A screw thread 12e is formed on the inner peripheral surface of the recess 12d. The screw thread 12e is formed in a spiral shape on the inner peripheral surface of the recess 12d from the tip side to the base end side.

[0020] The guard base 12b has a recess 12g on an end face 12f on the base end side. The recess 12g has a cylindrical shape hollowed out from the end face 12f toward the base end side. The inner peripheral surface of the recess 12g is a cylindrical surface. A screw thread 12h is formed on the inner peripheral surface of the recess 12g. The screw thread 12h is formed in a spiral shape on the inner peripheral surface of the recess 12g from the tip side to the base end side.

[0021] The ground electrode 13 has a cylindrical ground portion 13a centered on the central axis AX and a cylindrical ground base portion 13b centered on the central axis AX. The central axis of the ground electrode 13 is coaxial with the detection electrode 11 and the guard electrode 12.

[0022] The ground cylinder 13a surrounds the outer peripheral surface of the guard electrode 12. The ground cylinder 13a is disposed with a predetermined gap between it and the outer peripheral surface of the guard electrode 12. The tip end face of the ground cylinder 13a is flush with the detecting end face 11a of the detecting electrode 11 and the tip end face of the guard cylinder 12a.

[0023] The ground base 13b is disposed on the other end side in the axial direction of the central axis AX with respect to the guard electrode 12. The ground base 13b is connected to the ground cylindrical portion 13a by, for example, welding.

[0024] The gland base 13b has a recess 13d on an end face 13c on the tip side. The recess 13d has a cylindrical shape hollowed out from the end face 13c toward the base end side. The inner peripheral surface of the recess 13d is a cylindrical surface. A screw thread 13e is formed on the inner peripheral surface of the recess 13d. The screw thread 13e is formed in a spiral shape on the inner peripheral surface of the recess 13d from the tip side to the base end side.

[0025] The insulating member 20 connects the detection electrode 11 and the guard electrode 12, and connects the guard electrode 12 and the ground electrode 13. The insulating member 20 has a first insulating member 21 and a second insulating member 22. The first insulating member 21 and the second insulating member 22 are formed of an insulator such as ceramics.

[0026] The first insulating member 21 is disposed between the detection electrode 11 and the guard base 12b in the axial direction of the central axis AX. The first insulating member 21 connects the detection electrode 11 and the guard base 12b in the axial direction.

[0027] The first insulating member 21 has a base 21a and protruding portions 21b and 21c. The base 21a is cylindrical and centered on the central axis AX. The protruding portion 21b protrudes from the base 21a toward the tip side. The protruding portion 21c protrudes from the base 21a toward the base end side. The protruding portions 21b and 21c are cylindrical and centered on the central axis AX, and have a smaller diameter than the base 21a, for example. The diameter of the protruding portion 21b is set so that the protruding portion 21b can be inserted into the recess 11d of the detection electrode 11 described above. The outer peripheral surface of the protruding portion 21b is a cylindrical surface. A screw thread 21d is formed on the outer peripheral surface of the protruding portion 21b. The screw thread 21d is formed in a spiral shape from the base end side to the tip side on the outer peripheral surface of the protruding portion 21b so as to be screwed into the screw thread 11e of the recess 11d of the detection electrode 11 described above. The protruding portion 21b is inserted into the recessed portion 11d of the detection electrode 11 with the screw thread 21d and the screw thread 11e being screw-joined to each other. In this manner, the first insulating member 21 is screw-joined to the detection electrode 11.

[0028] On the other hand, the diameter of the protrusion 21c is set so that the protrusion 21c can be inserted into the recess 12d of the guard electrode 12. The outer peripheral surface of the protrusion 21c is a cylindrical surface. A screw thread 21e is formed on the outer peripheral surface of the protrusion 21c. The screw thread 21e is formed in a spiral shape from the base end side to the tip end side on the outer peripheral surface of the protrusion 21c so as to be screw-connected to the screw thread 12e of the recess 12d of the guard electrode 12. The protrusion 21c is inserted into the recess 12d of the guard electrode 12 in a state in which the screw thread 21e and the screw thread 12e are screw-connected. In this manner, the first insulating member 21 is screw-connected to the guard electrode 12.

[0029] The second insulating member 22 is disposed between the guard base 12b and the gland base 13b in the axial direction of the central axis AX. The second insulating member 22 connects the guard base 12b and the gland base 13b in the axial direction.

[0030] The second insulating member 22 has a base 22a and protruding portions 22b and 22c. The base 22a is cylindrical and centered on the central axis AX. The protruding portion 22b protrudes from the base 22a toward the tip side. The protruding portion 22c protrudes from the base 22a toward the base end side. The protruding portions 22b and 22c are cylindrical and centered on the central axis AX, and have a smaller diameter than the base 22a, for example. The diameter of the protruding portion 22b is set so that the protruding portion 22b can be inserted into the recess 12g of the guard electrode 12 described above. The outer circumferential surface of the protruding portion 22b is a cylindrical surface. A screw thread 22d is formed on the outer circumferential surface of the protruding portion 22b. The screw thread 22d is formed in a spiral shape from the base end side to the tip side on the outer circumferential surface of the protruding portion 22b so as to be screwed into the screw thread 12h of the recess 12g of the guard electrode 12 described above. The protruding portion 22b is inserted into the recess 12g of the guard electrode 12 with the threads 22d and 12h screwed together. In this manner, the second insulating member 22 is screwed together with the guard electrode 12.

[0031] On the other hand, the diameter of the protrusion 22c is set so that the protrusion 22c can be inserted into the recess 13d of the ground electrode 13. The outer peripheral surface of the protrusion 22c is a cylindrical surface. A screw thread 22e is formed on the outer peripheral surface of the protrusion 22c. The screw thread 22e is formed in a spiral shape from the base end side to the tip end side on the outer peripheral surface of the protrusion 22c so as to be screw-connected to the screw thread 13e of the recess 13d of the ground electrode 13. The protrusion 22c is inserted into the recess 13d of the ground electrode 13 in a state where the screw thread 22e and the screw thread 13e are screw-connected. In this manner, the second insulating member 22 is screw-connected to the ground electrode 13.

[0032] As described above, the electrode member 10 and the insulating member 20 are engaged in at least one of the axial direction and the circumferential direction of the central axis AX by the screw joint between the recess 11d of the detection electrode 11 and the protrusion 21b of the first insulating member 21, the screw joint between the protrusion 21c of the first insulating member 21 and the recess 12d of the guard electrode 12, the screw joint between the recess 12g of the guard electrode 12 and the protrusion 22b of the second insulating member 22, and the screw joint between the protrusion 22c of the second insulating member 22 and the recess 13d of the ground electrode 13.

[0033] The insulating layer 30 is made of, for example, a ceramic insulating adhesive. The insulating layer 30 is filled between the detection electrode 11, the guard electrode 12, the ground electrode 13, and the insulating member 20 (the first insulating member 21 and the second insulating member 22). By disposing the insulating layer 30, it is possible to suppress relative rotational movement in the direction around the central axis AX while insulating the detection electrode 11, the guard electrode 12, and the ground electrode 13. The insulating layer 30 is also disposed so as to fill gaps such as threaded portions between the first insulating member 21 and the detection electrode 11, between the first insulating member 21 and the guard electrode 12, between the second insulating member 22 and the guard electrode 12, and between the second insulating member 22 and the ground electrode 13. This makes it possible to suppress relative rotational movement of each component.

[0034] As described above, the clearance sensor 100 of this embodiment comprises: a cylindrical detection electrode 11 having a detection end face at one end side in the axial direction of the central axis AX; an electrode member 10 including a guard electrode 12 and a ground electrode 13 which are coaxial with the detection electrode 11 and the central axis AX; an insulating member 20 which connects the detection electrode 11 and the guard electrode 12 and connects the guard electrode 12 and the ground electrode 13; and an insulating layer 30 which is filled between the detection electrode 11, the guard electrode 12, the ground electrode 13, and the insulating member 20; and the electrode member 10 and the insulating member 20 are engaged in at least one of the axial direction and the direction around the central axis AX.

[0035] In this configuration, by locking the electrode member 10 and the insulating member 20, it is possible to suppress misalignment between the electrode member 10 and the insulating member 20. Therefore, it is possible to suppress a decrease in reliability in long-term measurement. Furthermore, when performing long-term measurement at high temperatures, such as when measuring the tip clearance between the casing and rotor blades of a gas turbine, it is possible to suppress wear of the insulating member 20 and peeling of the insulating layer 30 caused by thermal expansion difference and vibration, and it is possible to maintain reliability over a long period of time.

[0036] In the clearance sensor 100 according to this embodiment, the guard electrode 12 has a guard cylindrical portion 12a surrounding the outer circumferential surface of the detection electrode 11 and a guard base portion 12b disposed on the base end side of the axial direction with respect to the detection electrode 11 and connected to the guard cylindrical portion 12a, the ground electrode 13 has a ground cylindrical portion 13a surrounding the outer circumferential surface of the guard electrode 12 and a ground base portion 13b disposed on the base end side of the guard electrode 12 and connected to the ground cylindrical portion 13a, and the insulating member 20 has a first insulating member 21 connecting the detection electrode 11 and the guard base portion 12b in the axial direction and a second insulating member 22 connecting the guard base portion 12b and the ground base portion 13b in the axial direction. Therefore, the base portions of the electrodes constituting the electrode member 10 are connected to each other by the insulating member 20 and the connecting portions are locked, so that positional deviation between the electrode member 10 and the insulating member 20 can be more reliably suppressed.

[0037] In the clearance sensor 100 according to this embodiment, the electrode member 10 and the insulating member 20 are engaged with each other by a screw connection. Therefore, it is possible to suppress misalignment between the electrode member 10 and the insulating member 20 in both the axial direction and the direction around the central axis AX.

[0038] In the example shown in FIG. 1 described above, a configuration in which the electrode member 10 and the insulating member 20 are engaged with each other by screw joint has been described as an example, but the configuration for engaging the electrode member 10 and the insulating member 20 with each other is not limited to screw joint.

[0039] Fig. 2 is a diagram showing another example of the clearance sensor according to the present embodiment. Fig. 2 shows an example of a cross-sectional configuration taken along a plane passing through the central axis AX. For example, as in the clearance sensor 200 shown in Fig. 2, the electrode member 10 and the insulating member 20 may be locked together by inserting a pin between them.

[0040] 2, a pin 41 is disposed between the detection electrode 11 and the first insulating member 21. The pin 41 is disposed so as to penetrate between the outer circumferential surface of the detection electrode 11 and the recess 11d, and to be inserted into the outer periphery of the protruding portion 21b of the first insulating member 21. By disposing the pin 41, movement between the detection electrode 11 and the first insulating member 21 in the axial direction of the central axis AX and in the direction around the axis is restricted.

[0041] Furthermore, a pin 42 is disposed between the guard electrode 12 and the first insulating member 21. The pin 42 is disposed so as to penetrate between the outer circumferential surface of the guard electrode 12 and the recess 12d, and to be inserted into the outer periphery of the protruding portion 21c of the first insulating member 21. By disposing the pin 42, movement between the guard electrode 12 and the first insulating member 21 in the axial direction of the central axis AX and in the direction around the axis is restricted.

[0042] Furthermore, a pin 43 is disposed between the guard electrode 12 and the second insulating member 22. The pin 43 is disposed so as to penetrate between the outer circumferential surface of the guard electrode 12 and the recess 12g, and to be inserted into the outer periphery of the protruding portion 22b of the second insulating member 22. By disposing the pin 43, movement between the guard electrode 12 and the second insulating member 22 in the axial direction of the central axis AX and in the direction around the axis is restricted.

[0043] Furthermore, a pin 44 is disposed between the ground electrode 13 and the second insulating member 22. The pin 44 is disposed so as to penetrate between the outer circumferential surface of the ground electrode 13 and the recess 13d, and to be inserted into the outer periphery of the protruding portion 22c of the second insulating member 22. By disposing the pin 44, movement between the ground electrode 13 and the second insulating member 22 in the axial direction of the central axis AX and in the direction around the axis is restricted.

[0044] The pins 41, 42, 43, and 44 are each arranged in a plurality of positions, for example, in a direction around the central axis AX. The pins 41, 42, 43, and 44 are formed, for example, of a metal or an alloy, similar to the electrode member 10. Note that the pins 41, 42, 43, and 44 may be formed, for example, of an insulator such as ceramics, similar to the insulating member 20.

[0045] As described above, in the clearance sensor 200 according to this embodiment, the electrode member 10 and the insulating member 20 are locked together by inserting the pins 41, 42, 43, and 44. Therefore, it is possible to suppress misalignment between the electrode member 10 and the insulating member 20 in both the axial direction and the direction around the central axis AX.

[0046] Fig. 3 is a diagram showing another example of the clearance sensor according to this embodiment. The clearance sensor 300 shown in Fig. 3 has a configuration in which spacer members made of an insulator such as alumina are arranged between the detection electrode 11 and the guard electrode 12, and between the guard electrode 12 and the ground electrode 13. The other configurations are the same as those described above (the configuration shown in Fig. 1).

[0047] As shown in FIG. 3, the spacer member 31 is disposed between the detection electrode 11 and the guard cylindrical portion 12a of the guard electrode 12. The spacer member 31 is, for example, ring-shaped, but is not limited thereto and may be of another shape. By disposing the spacer member 31, misalignment between the detection electrode 11 and the guard cylindrical portion 12a is suppressed. In the configuration shown in FIG. 3, recesses for accommodating the spacer member 31 may be provided on the outer periphery of the detection electrode 11 and the inner periphery of the guard cylindrical portion 12a. In addition, the detection electrode 11 and the guard cylindrical portion 12a may have tapered reduced diameter portions that are reduced in diameter toward the tip side, and the spacer member 31 may be disposed between the reduced diameter portion of the detection electrode 11 and the reduced diameter portion of the guard cylindrical portion 12a. This suppresses misalignment of the spacer member 31.

[0048] The spacer member 32 is disposed between the guard cylindrical portion 12a of the guard electrode 12 and the ground cylindrical portion 13a of the ground electrode 13. The spacer member 32 is, for example, ring-shaped, but is not limited thereto and may be of another shape. By disposing the spacer member 32, misalignment between the guard cylindrical portion 12a and the ground cylindrical portion 13a is suppressed. In the configuration shown in FIG. 3, recesses for accommodating the spacer member 32 may be provided on the outer periphery of the guard cylindrical portion 12a and the inner periphery of the ground cylindrical portion 13a. Alternatively, the guard cylindrical portion 12a and the ground cylindrical portion 13a may have tapered reduced diameter portions that are tapered toward the tip side, and the spacer member 32 may be disposed between the reduced diameter portions of the guard cylindrical portion 12a and the ground cylindrical portion 13a. This suppresses misalignment of the spacer member 32.

[0049] As described above, in the clearance sensor 300 of this embodiment, by disposing the spacer members 31, 32 between the detection electrode 11 and the guard electrode 12, and between the guard electrode 12 and the ground electrode 13, it is possible to suppress misalignment between the detection electrode 11 and the guard cylindrical portion 12a of the guard electrode 12, and between the guard cylindrical portion 12a of the guard electrode 12 and the ground cylindrical portion 13a of the ground electrode 13.

[0050] Fig. 4 is a diagram showing another example of the clearance sensor according to this embodiment. Fig. 5 shows a configuration along the AA cross section in Fig. 4. Fig. 6 shows a configuration along the BB cross section in Fig. 5. The clearance sensor 400 shown in Figs. 4 to 6 is configured to have a cooling flow path. The other configurations are similar to the above-mentioned configuration (the configuration shown in Fig. 2), but are not limited thereto, and may be similar to the configuration shown in Fig. 1.

[0051] 5 and 6, the cooling flow passage 50 penetrates the electrode member 10 and the insulating member 20 along the axial direction of the central axis AX. A plurality of cooling flow passages 50 are arranged on concentric circles centered on the central axis AX when viewed in the axial direction of the central axis AX. Each cooling flow passage 50 is formed linearly along the axial direction of the central axis AX.

[0052] 5 and 6, the cooling flow passage 50 is provided at a position penetrating, for example, the ground base 13b of the ground electrode 13, the base 22a of the second insulating member 22, the guard base 12b of the guard electrode 12, the base 21a of the first insulating member 21, and the detection electrode 11. In this manner, the cooling flow passage 50 is provided in portions of the electrode member 10 and the insulating member 20 that correspond to the respective bases.

[0053] For example, cooling air or the like can be circulated through the cooling flow passage 50. The cooling air can be flowed, for example, from the base end side to the tip end side of the cooling flow passage 50. By circulating the cooling air or the like through the cooling flow passage 50, the portions of the electrode member 10 and the insulating member 20 corresponding to the respective base portions can be efficiently cooled. This makes it possible to suppress a temperature rise in the clearance sensor 400.

[0054] 4 to 6, the case where the electrode member 10 and the insulating member 20 are engaged as shown in Fig. 1 or 2 is described, but the present invention is not limited to this. For example, the electrode member 10 and the insulating member 20 may not be formed, and may be connected by fitting or the like.

[0055] Fig. 7 is a diagram showing another example of the clearance sensor according to this embodiment. Fig. 8 shows a configuration along the CC cross section in Fig. 7. Fig. 9 shows a configuration along the DD cross section in Fig. 7. Clearance sensor 500 shown in Figs. 7 to 9 is configured to be provided with cooling flow passage 51 having a different aspect from the cooling flow passage shown in Figs. 4 to 6 described above. The other configurations are similar to the above configuration (the configuration shown in Fig. 2), but are not limited thereto, and may be similar to the configuration shown in Fig. 1 described above.

[0056] In the examples shown in FIG. 7 to FIG. 9, the cooling flow passage 51 has a straight portion 51a, a converging portion 51b, and an opening 51c. The straight portion 51a extends, for example, inside the ground cylindrical portion 13a of the ground electrode 13 along the axial direction of the central axis AX. As shown in FIG. 7, a flange portion 13g is provided on the outer periphery of the ground cylindrical portion 13a. The tip side of the flange portion 13g of the ground cylindrical portion 13a has a larger diameter than the base end side of the flange portion 13g. The straight portion 51a extends from the end face on the base end side of the flange portion 13g toward the inside of the ground cylindrical portion 13a along the axial direction of the central axis AX. The straight portion 51a is connected to the converging portion 51b at the tip side of the ground cylindrical portion 13a. As shown in FIG. 8, a plurality of straight portions 51a are arranged along the circumferential direction of the ground cylindrical portion 13a. The plurality of straight portions 51a are arranged, for example, at equal pitches in the circumferential direction of the ground cylindrical portion 13a.

[0057] The converging portion 51b extends from the tip side of the gland cylindrical portion 13a toward the inside in the radial direction. As shown in FIG. 7, the converging portion 51b extends in a direction inclined toward the central axis AX from the connecting portion with the straight portion 51a toward the tip side. Also, as shown in FIG. 9, the converging portion 51b extends from the connecting portion with the straight portion 51a toward the tangential direction of the opening 51c when viewed from the axial direction of the central axis AX. By configuring the converging portion 51b to extend toward the tangential direction of the opening 51c when viewed from the axial direction of the central axis AX, the length of the converging portion 51b can be secured compared to the case where the converging portion 51b extends toward the central axis side. Therefore, the cooling efficiency is improved when cooling air is circulated.

[0058] The opening 51c is disposed at the end portion on the tip side of the clearance sensor 500. The opening 51c is formed in an annular shape between the outer periphery of the detection electrode 11 and the guard cylindrical portion 12a of the guard electrode 12.

[0059] For example, cooling air or the like can be circulated through the cooling flow passage 51. The cooling air flows, for example, from the straight portion 51a of the cooling flow passage 51 through the converging portion 51b toward the opening 51c, and is discharged to the outside from the opening 51c. By circulating the cooling air or the like through the cooling flow passage 51, the portions of the electrode member 10 and the insulating member 20 that correspond to the respective base portions can be efficiently cooled. This makes it possible to suppress a temperature rise in the clearance sensor 500.

[0060] 7 to 9, the case where the electrode member 10 and the insulating member 20 are engaged as shown in Fig. 1 or 2 is described, but the present invention is not limited to this. For example, the electrode member 10 and the insulating member 20 may not be formed, and may be connected by fitting or the like.

[0061] Furthermore, the clearance sensor may have both the cooling flow passage 50 of the clearance sensor 400 shown in Figures 4 to 6 and the cooling flow passage 51 of the clearance sensor 500 shown in Figures 7 to 9. This allows the clearance sensor to be cooled from its outer periphery to its inside, thereby improving cooling efficiency. [Explanation of symbols]

[0062] 10 Electrode material 11 Detection electrode 11a Detection end face 11b,12c,12f,13c end face 11c Outer surface 11d, 12d, 12g, 13d recess 11e,12e,12h,13e,21d,21e,22d,22e Thread 11f,12i,13f Reduced diameter part 12 Guard electrode 12a Guard cylinder 12b Guard base 13 Ground electrode 13a Gland Cylinder 13b Ground base 13g Flange part 14 Wiring section 15 Tubular members 16 Tubular parts 20 Insulating material 21 First insulating member 21a,22a base 21b, 21c, 22b, 22c protrusion 22 Second insulating member 30 Insulating layer 31, 32 Spacer member 41,42,43,44 pin 50,51 Cooling channel 51a Straight section 51b Focusing part 51c opening 100,200,300,400,500 Clearance Sensor AX center axis

Claims

1. an electrode member including a cylindrical detection electrode having a detection end face at a tip end side, which is one end side in an axial direction of a central axis, and a guard electrode and a ground electrode, the central axis of which are coaxial with the detection electrode; an insulating member that connects the detection electrode and the guard electrode and connects the guard electrode and the ground electrode in the axial direction; an insulating adhesive that is provided separately from the insulating member and that is filled between the detection electrode, the guard electrode, the ground electrode, and the insulating member; Equipped with the guard electrode has a guard cylindrical portion surrounding an outer circumferential surface of the detection electrode, and a guard base portion disposed on a base end side of the detection electrode opposite a tip end side in the axial direction and connected to the guard cylindrical portion, the ground electrode has a ground cylindrical portion surrounding an outer circumferential surface of the guard electrode, and a ground base portion disposed on the other end side of the guard base portion in the axial direction and connected to the ground cylindrical portion, the detection electrode has a detection base end side end surface having a first recess on a base end side in the axial direction, the guard base has a guard tip end face facing the detection base end face at a tip end side in the axial direction and having a second recess, and a guard base end face facing the gland base at a base end side in the axial direction and having a third recess, the gland base has a gland tip end surface facing the guard base end surface and having a fourth recess on a tip side in the axial direction, the insulating member includes a first insulating member that connects the detection electrode and the guard base in the axial direction, and a second insulating member that connects the guard base and the ground base in the axial direction, the first insulating member has a first protruding portion protruding toward a tip end side in the axial direction and a second protruding portion protruding toward a base end side in the axial direction, and connects the detection electrode and the guard base in a state in which the first protruding portion is inserted into the first recess and the second protruding portion is inserted into the second recess; the second insulating member has a third protruding portion protruding toward a tip end side in the axial direction and a fourth protruding portion protruding toward a base end side in the axial direction, the third protruding portion being inserted into the third recess, and the fourth protruding portion being inserted into the fourth recess to connect the guard base and the gland base, The electrode member and the insulating member are engaged with each other in at least one of the axial direction and the circumferential direction of the central shaft. Clearance sensor.

2. The electrode member and the insulating member are engaged with each other by screw connection. The clearance sensor of claim 1 .

3. The electrode member and the insulating member are locked together by inserting a pin between them. The clearance sensor according to claim 1 or 2.

4. A ring-shaped spacer member made of an insulator is provided separately from the insulating member and the insulating adhesive and is disposed at least one between the detection electrode and the guard electrode and between the guard electrode and the ground electrode. The clearance sensor according to claim 1 .

5. a cooling passage extending through the electrode member and the insulating member along the axial direction of the central axis; The clearance sensor according to claim 1 .

6. The cooling passages are arranged on a plurality of concentric circles centered on the central axis when viewed in the axial direction of the central axis. The clearance sensor according to claim 5 .

7. The cooling flow passage is formed linearly along the axial direction of the central axis. The clearance sensor according to claim 6.

8. The cooling flow passages are formed so as to converge from the outer side to the inner side in the radial direction with respect to the central axis toward the detection end side. The clearance sensor according to claim 6.

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