Field device housing and field device

Abstract

A metal field device housing is provided with a pulling-in portion on a cylindrical peripheral wall for pulling in a cable having an outer shield, and includes: a first inner surface formed to be away from the opening end surface in an axial direction orthogonal to the opening end surface of the field device housing; a second inner surface formed to be further away from the opening end surface than the first inner surface in the axial direction; and a cable fixing member fixed to the first inner surface and bringing the outer shield of the cable pulled in from the pulling-in portion into contact with the second inner surface.

Description

Technical Field

[0001] The present invention relates to a housing of a field device and a field device.

[0002] This application claims priority based on a Japanese patent application with an application date of October 30, 2020 and an application number of Japanese Patent Application No. 2020-182309, the content of which is incorporated herein by reference. Background Art

[0003] As a type of field device, a vortex flowmeter described in Japanese Unexamined Patent Application Publication No. 2002-107192 is known. The vortex flowmeter includes a container having a cylindrical side wall and a partition wall provided at a central portion of the side wall. The interior of the container is divided by the side wall and the partition wall into a terminal box chamber and an amplifier chamber. A terminal box portion having a signal terminal portion and a power supply terminal portion is provided in the terminal box chamber. An amplifier portion for processing an input signal and a power supply input is provided in the amplifier chamber.

[0004] However, an opening end face of the above-described container is covered with a lid portion. The container and the lid portion are joined by a sleeve. In order to prevent the cable pulling-in port for pulling a cable into the terminal box chamber from overlapping with the fitting portion of the lid portion, the cable pulling-in port of the terminal box chamber is arranged deep away from the opening end face. Conventionally, as a countermeasure against cable noise, the braided shield that serves as an outer shield is disassembled, the shield bare wires are bundled and connected to a connection terminal, and the connection terminal is connected to a grounding portion of the terminal box portion arranged near the opening end. However, this connection method has problems that the terminal processing becomes complicated and requires a large amount of man-hours, and mistakes are likely to occur. Summary of the Invention

[0005] (1) A field device according to an embodiment of the present invention is made of metal, and a pulling-in portion for pulling a cable having an outer shield is provided on a cylindrical peripheral wall, and is characterized by including: a first inner surface formed to be away from the opening end face in an axial direction orthogonal to the opening end face of the housing of the field device; a second inner surface formed to be more away from the opening end face than the first inner surface in the axial direction; and a cable fixing member fixed to the first inner surface and bringing the outer shield of the cable pulled in from the pulling-in portion into contact with the second inner surface.

[0006] (2) For the housing of the field device according to (1) above, an anti-rotation portion for preventing the cable fixing member from rotating may be formed on the first inner surface.

[0007] (3) For the housing of the field device according to (2) above, the anti-rotation portion may protrude from the first inner surface toward the opening end face and have a convex shape that abuts against a side surface of the cable fixing member.

[0008] (4) The on-site equipment housing according to any one of (1) to (3) above may be such that, in a cross-sectional view of the cable, the cable fixing member has at least a second contact point and a third contact point that are in contact with the outer shield across the center line, and the center line passes through the first contact point where the outer shield contacts the second inner surface and the center point of the cable.

[0009] (5) The on-site equipment housing according to (4) above may be formed with: a third inner surface that is formed to be farther from the opening end surface than the second inner surface in the axial direction; a base portion that is formed to project from the third inner surface toward the opening end surface and is provided with the second inner surface.

[0010] (6) The on-site equipment housing according to (5) above may further include: a bottomed cylindrical metal housing that extends in the axial direction; and a lid that is fitted to the metal housing.

[0011] (7) The on-site equipment housing according to (6) above may be such that the metal housing has a peripheral wall and a bottom wall, and a fitting groove for fitting the lid is formed on the outer peripheral surface of the peripheral wall and a flange is provided that is axially opposite to the fitting portion of the lid.

[0012] (8) The on-site equipment housing according to (7) above may be such that a pulling-in portion is provided on the peripheral wall, and the pulling-in portion projects from the peripheral wall on the side closer to the bottom wall than the flange in a tangential direction of the inner peripheral surface of the peripheral wall in a form that does not interfere with the lid fitted to the peripheral wall.

[0013] (9) The on-site equipment housing according to (6) above may further include a terminal box portion that is provided inside the metal housing and is connected to the cable pulled in from the pulling-in portion.

[0014] (10) The on-site equipment housing according to (9) above may further include a terminal box setting surface on which the terminal box portion is provided, and the terminal box setting surface, the first inner surface, the second inner surface, and the third inner surface are surfaces that do not overlap each other in a top view along the central axis of the metal housing and face the opening end surface inside the metal housing.

[0015] (11) The on-site equipment housing according to (5) above may be such that the first inner surface is formed at the front end of the base portion, and the second inner surface is disposed at the same position in the axial direction as the pulling-in port of the pulling-in portion.

[0016] (12) The on-site equipment housing described in the above (5) may be such that the cable fixing member includes: a fixing portion fixed to the first inner surface; a vertically extending portion vertically provided from the fixing portion toward the second inner surface; and a contact portion bent from the vertically extending portion and contacting the outer shield.

[0017] (13) The on-site equipment housing described in the above (12) may be such that the fixing portion is fixed to the first inner surface via bolts.

[0018] (14) The on-site equipment housing described in the above (12) may be such that the vertically extending portion is bent at a right angle with respect to the fixing portion toward the side opposite to the opening end face.

[0019] (15) The on-site equipment housing described in the above (12) may be such that the contact portion includes: a first contact portion bent at a right angle with respect to the vertically extending portion toward the side away from the base portion; and a second contact portion bent at an obtuse angle with respect to the first contact portion toward the side opposite to the opening end face.

[0020] (16) The on-site equipment housing described in the above (15) may be such that the first contact portion has the second contact point and the second contact portion has the third contact point.

[0021] (17) An on-site equipment according to an embodiment of the present invention includes: a detector that outputs a detection result; a converter connected to the detector via a cable; at least one of the detector and the converter has the on-site equipment housing described in any one of the above 1 to 16.

[0022] (18) The on-site equipment described in the above (17) may be such that the detector includes a piping portion through which a fluid flows and a detection portion that detects the flow velocity or flow rate of the fluid.

[0023] (19) The on-site equipment described in the above (18) may be such that the detection portion is disposed inside the piping portion, and a stress detection element for measuring the flow velocity or flow rate of the fluid is provided inside the detection portion.

[0024] (20) In the on-site equipment described in the above (19), the stress detection element detects an alternating lift force acting on the vortex shedding body of the detection portion, measures the frequency of the Karman vortex street, and measures the flow velocity or flow rate of the fluid based on the frequency.

[0025] According to an embodiment of the present invention, in the on-site equipment housing and the on-site equipment where a cable is pulled in from a peripheral wall portion away from the opening end face, a solution for coping with cable noise can be simply implemented without complicated terminal processing.

[0026] Other features and aspects of the present invention will become apparent from the accompanying drawings and the detailed description of the embodiments below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a perspective view of a field device showing one embodiment.

[0028] Figure 2 is a partially cut-away perspective view showing the state in which the lid is removed from the cable connection container of a slave converter in one embodiment.

[0029] Figure 3 is a cross-sectional view of a metal housing along the pulling-in portion in one embodiment.

[0030] Figure 4 is a cross-sectional view of a metal housing along a cable fixing member in one embodiment.

[0031] Figure 5 is Figure 4 an enlarged view of the area A shown.

[0032] Figure 6 is a partially cut-away perspective view showing the state in which the first lid is removed from the cable connection container of a detector in one embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The embodiments of the present invention will be described with reference to preferred embodiments. Those skilled in the art can implement numerous alternative methods using the teachings of the present invention, and the present invention is not limited to the preferred embodiments described herein.

[0034] One embodiment of the present invention is a field device housing and a field device in which a cable is pulled in from a peripheral wall portion far from the opening end face, and a solution for coping with cable noise is simply implemented without complicated terminal processing.

[0035] The field device housing and the field device according to one embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the following, first, an overview of one embodiment of the present invention will be described, and then the detailed content of one embodiment of the present invention will be described.

[0036] 〔Overview〕

[0037] The vortex flowmeter disclosed in Japanese Patent Application Laid-Open No. 2002-107192 is a measuring instrument that measures the flow velocity and flow rate by measuring the frequency of the Karman vortex street generated from a vortex street generator placed in a pipeline. As a method for detecting the vortex street frequency, there is a stress detection method in which a stress detection element is arranged above or inside the vortex street generator to detect the alternating lift force acting on the vortex street generator, thereby measuring the frequency of the Karman vortex street. The sensor analog signal from the stress detection element is transmitted from the detector to the converter through the sensor wire. The analog signal transmitted to the converter is converted into a digital signal.

[0038] Regarding the vortex flowmeter disclosed in Japanese Patent Application Laid-Open No. 2002-107192, its detector and converter are integrated and is also called an integral type. On the other hand, in a vortex flowmeter, there is also a transfer type in which the detector and the converter are separated and connected via a cable. In order to cope with the cable noise, in this transfer type of vortex flowmeter, it is necessary to perform the above-mentioned cumbersome cable termination processing on both the detector and the converter, which doubles the working time and is particularly prone to errors.

[0039] As a solution to cope with noise without performing cable termination processing, for example, a grounding solution disclosed in Japanese Patent Application Laid-Open No. 2020-107722 is known. This grounding solution exposes the outer shield of the cable and thread-fastens the two ends of the clamp portion crimped to the outer shield to the frame ground wire. In a field device that pulls the cable from a depth far from the opening end face, this solution has a problem that it becomes a thread-fastening operation in the depth and the workability is poor.

[0040] One embodiment of the present invention is an embodiment in which, in a field device housing and a field device, a cable fixing member is fixed to a first inner surface provided at a shallower position from the opening end face, and the outer shield of the cable is pressed against a second inner surface provided deeper than the first inner surface by the cable fixing member to obtain grounding. Thus, it is not necessary to perform cumbersome cable termination processing, and the operation can be performed at a shallower position from the opening end face, so that cable noise can be simply coped with.

[0041] 〔Embodiment〕

[0042] Figure 1 FIG. is a perspective view of a field device 1 showing one embodiment.

[0043] Figure 1 The shown field device 1 is a transfer type vortex flowmeter, and includes a detector 2, a converter 3, and a cable 4. The cable 4 connects the detector 2 and the converter 3. As Figure 1 The shown detector 2 includes a pipe detection unit 10 and a cable connection container 20.

[0044] Among them, in the following description, there is content where an XYZ rectangular coordinate system is set, and the positional relationship of each component is described with reference to this XYZ rectangular coordinate system. The X-axis direction is the direction in which the fluid flows in the pipe detection unit 10. The Z-axis direction is the direction in which the cable connection container 20 is connected to the pipe detection unit 10 in a direction orthogonal to the above X-axis direction. The Y-axis direction is the direction orthogonal to the above X-axis direction and the above Z-axis direction.

[0045] The pipe detection unit 10 includes a cylindrical pipe portion 11 extending in the X-axis direction. At both ends of the pipe portion 11, there are flanges 12 (not shown) that can be connected to external pipes. On the flanges 12, a plurality of connection holes 12a are formed at intervals in the circumferential direction of the central axis of the pipe portion 11. On the circumferential surface of the pipe portion 11, a base portion 13 is erected in the Z-axis direction.

[0046] A fixing block 15 for fixing the detection unit 14 is threadedly fixed to the upper surface of the base portion 13 via a bolt 15a. The detection unit 14 is formed in a rod shape and is inserted into the interior of the pipe portion 11 from the upper surface of the base portion 13 in the Z-axis direction. The detection unit 14 includes a stress detection element (not shown) inside the rod.

[0047] The detection unit 14, through this stress detection element, detects the alternating lift acting on the vortex shedding body of the detection unit 14 arranged inside the pipe portion 11, measures the frequency of the Karman vortex street, and measures the fluid flow velocity and flow rate based on this frequency. Among them, the detection unit 14 may also include sensors that can detect various physical quantities such as, for example, temperature, humidity, pressure, vibration, acceleration, and rotational speed, in addition to detecting the flow velocity and flow rate.

[0048] A bracket 16 having a pair of legs straddling the fixing block 15 is threadedly fastened to the upper surface of the base portion 13 via a bolt 16a. The cable connection container 20 is threadedly fastened to the upper end of the bracket 16 via a bolt 16b. The sensor wire extending from the detection unit 14 (stress detection element) penetrates the bracket 16 and is inserted into the interior of the cable connection container 20.

[0049] The cable connection container 20 includes a cylindrical metal housing 21 (field device housing) extending in the Y-axis direction, a first cover body 22 fitted to one end of the metal housing 21 in the Y-axis direction, and a second cover body 23 fitted to the other end of the metal housing 21 in the Y-axis direction. A cable pulling-in portion 24 for pulling the cable 4 is provided at an intermediate position in the Y-axis direction on the metal housing 21 that does not overlap with the first cover body 22 and the second cover body 23.

[0050] The converter 3 includes a cable connection container 30 and a converter body 40. The cable connection container 30 includes a bottomed cylindrical metal housing 31 (field device housing) extending in the X-axis direction and a cover 32 fitted to the open end portion of the metal housing 31 in the X-axis direction. The metal housing 31 has a connection portion 33 that can be connected to the converter body 40. A cable pulling portion 34 (refer to the following Figure 2 ) for pulling the cable 4 is provided on the metal housing 31, which is the same as the above-mentioned pulling portion 24.

[0051] The converter body 40 houses a converter that converts an analog signal output from the detection unit 14 (stress detection element) into a digital signal. The converter body 40 includes a cylindrical metal housing 41 extending in the Y-axis direction, a first cover 42 fitted to one end portion of the metal housing 21 in the Y-axis direction, and a second cover 43 fitted to the other end portion of the metal housing 41 in the Y-axis direction.

[0052] Among them, although a cable pulling portion 44 having the same structure as the above-mentioned pulling portion 24 is provided on the metal housing 41, the cable pulling portion 44 is a cable pulling portion for pulling a cable of an external device (not shown). The analog signal output from the detector 2 is transmitted to the converter 3 through the cable 4, converted into a digital signal inside the converter body 40, and then transmitted from the cable pulling portion 44 to an external device or the like through a cable (not shown). Among them, it is also possible to convert the sensor output into a digital signal on the detector 2 side first and then output it, and perform arithmetic processing on the converter 3 side.

[0053] Figure 2 is a partial cross-sectional perspective view showing a state in which the cover 32 is removed from the cable connection container 30 of the converter 3 according to an embodiment.

[0054] As Figure 2 shown, the cable connection container 30 of the converter 3 includes a bottomed cylindrical metal housing 31 extending in the X-axis direction and a cover 32 covering the open end face 61 of the metal housing 31. In the following, there is a case where the direction (X-axis direction) orthogonal to the open end face 61 of the metal housing 31 is referred to as the axial direction. The axial direction is the direction in which the central axis O1 of the metal housing 31 extends.

[0055] The metal housing 31 includes a peripheral wall 31a and a bottom wall 31b. A fitting groove 31a1 into which the cover 32 is fitted and a flange 31a2 facing the fitting portion of the cover 32 in the axial direction are formed on the outer peripheral surface of the peripheral wall 31a. Among them, the cover 32 can also be attached to the outer peripheral surface of the peripheral wall 31a by screws.

[0056] On the peripheral wall 31a, a pulling-in portion 34 for pulling the cable 4 into the interior of the metal housing 31 is provided. The pulling-in portion 34 protrudes in a substantially tangential direction (Y-axis direction) of the inner peripheral surface of the peripheral wall 31a from the peripheral wall 31a on the side closer to the bottom wall 31b than the flange 31a2 so as not to interfere with the lid body 32 fitted to the peripheral wall 31a. The pulling-in portion 34 is formed with a pulling-in port 34a communicating with the interior of the metal housing 31.

[0057] Inside the metal housing 31, a terminal box portion 50 connected to the cable 4 pulled in from the pulling-in portion 34 and a cable fixing member 70 for fixing the cable 4 to the metal housing 31 are provided. Hereinafter, further referring to Figures 3 to 5 , the internal structure of the metal housing 31 will be described in detail.

[0058] Figure 3 is a cross-sectional view of the metal housing 31 along the pulling-in portion 34 of an embodiment. Figure 4 is a cross-sectional view of the metal housing 31 along the cable fixing member 70 of an embodiment. Figure 5 is Figure 4 an enlarged view of the area A shown in

[0059] As Figure 4 shown, inside the metal housing 31, a terminal box setting surface 62, a first inner surface 63, a second inner surface 64, and a third inner surface 65 are formed stepwise and are spaced apart from the opening end surface 61 in the axial direction (X-axis direction). The terminal box setting surface 62, the first inner surface 63, the second inner surface 64, and the third inner surface 65 do not overlap each other when viewed from above along the central axis O1, and are surfaces inside the metal housing 31 facing the opening end surface 61 side.

[0060] The terminal box setting surface 62 is formed to be closest to the opening end surface 61. As Figure 3 shown, the terminal box portion 50 is screwed to the terminal box setting surface 62 via bolts 51. As Figure 4 shown, a cavity portion 31A is formed directly below the terminal box portion 50. The cavity portion 31A communicates with a connection passage 33a inside the connection portion 33. The terminal box portion 50 is connected to the converter body 40 side via a cable (not shown) passing through the cavity portion 31A and the connection passage 33a.

[0061] The first inner surface 63 is provided to be farther from the opening end surface 61 than the terminal box setting surface 62. The cable fixing member 70 is screwed to the first inner surface 63 via bolts 80.

[0062] The second inner surface 64 is provided to be farther from the opening end surface 61 than the first inner surface 63. The cable 4 pulled in by the pulling-in portion 34 is pressed against the second inner surface 64 by the cable fixing member 70.

[0063] The third inner surface 65 is arranged to be further away from the opening end face 61 than the second inner surface 64. As Figure 3 shown, a base portion 64A that protrudes from the third inner surface 65 toward the opening end face 61 and is provided with the second inner surface 64 is formed in the metal housing 31. The second inner surface 64 is arranged at a position substantially the same as the draw-in port 34a of the draw-in portion 34 in the X-axis direction. Among them, as Figure 2 shown, the first inner surface 63 is formed at the front end of the base portion 64A.

[0064] As Figure 5 shown, the cable 4 includes a plurality of inner cables 4a, a central tensile strength member 4b arranged at the center of the plurality of inner cables 4a, an outer shield 4c surrounding the outside of the plurality of inner cables 4a, and a sheath 4d covering the outside of the outer shield 4c. As Figure 3 shown, the sheath 4d of the part of the cable 4 placed on the second inner surface 64 is removed from the front part thereof, and the outer shield 4c is exposed.

[0065] Moreover, the outer shield 4c of the part of the cable 4 in front of the second inner surface 64 is removed, and the plurality of inner cables 4a are separated and connected to the terminal box portion 50. The roots of the plurality of inner cables 4a are bundled together by a crimping cap 4e. The outer shield 4c is, for example, a braided shield formed by braiding metal wires. In addition, the outer shield 4c may also be formed by spirally winding a metal tape or by cigarette-rolling a metal tape.

[0066] As Figure 5 shown, the cable fixing member 70 includes a fixing portion 71 fixed to the first inner surface 63, a vertical portion 72 vertically provided from the fixing portion 71 toward the second inner surface 64, and a contact portion 73 bent from the vertical portion 72 and in contact with the outer shield 4c. The cable fixing member 70 can be formed, for example, by bending a substantially rectangular metal plate into a crank shape. In addition, the cable fixing member 70 may also be a resin molding member.

[0067] The fixing portion 71 is fixed to the first inner surface 63 via a bolt 80. In the metal housing 31, a rotation prevention portion 66 that prevents the cable fixing member 70 from rotating is formed on the first inner surface 63. The rotation prevention portion 66 protrudes from the first inner surface 63 toward the opening end face 61 and has a convex shape that abuts against the side surface of the fixing portion 71. The rotation prevention portion 66 is provided at a portion corresponding to the step portion between the terminal box setting surface 62 and the first inner surface 63.

[0068] The vertical portion 72 is bent at a substantially right angle with respect to the fixing portion 71 toward the side opposite to the opening end face 61 (the angle between the vertical portion 72 and the fixing portion 71 is approximately 90°). Although the vertical portion 72 does not contact the metal housing 31, it may also contact the metal housing 31.

[0069] The contact portion 73 has a first contact portion 73a that is bent at a substantially right angle (the angle with the vertical portion 72 is approximately 90°) toward the side surface away from the base portion 64A with respect to the vertical portion 72, and a second contact portion 73b that is bent at a substantially obtuse angle (the angle with the first contact portion 73a is approximately 135°) with respect to the first contact portion 73a toward the side opposite to the opening end surface 61.

[0070] As Figure 5 shown, in the cross-sectional view of the cable 4, the contact portion 73 has at least a second contact point P2 and a third contact point P3 that sandwich the center line L and are in contact with the outer shield 4c. The center line L passes through the first contact point P1 where the outer shield 4c contacts the second inner surface 64 and the center point O of the cable 4. Specifically, the first contact portion 73a has the second contact point P2. And the second contact portion 73b has the third contact point P3. That is, the cable 4 is fixed at three points.

[0071] The second inner surface 64 has a flat portion 64a parallel to the opening end surface 61 and an inclined surface portion 64b that warps upward from the flat portion 64a to the opening end surface 61. Among them, the inclined surface portion 64b can be either an inclined surface or a curved surface. The inclined surface portion 64b has the first contact point P1. Assuming that the first contact point is on the flat portion 64a of P1, the circular cable 4 can move arbitrarily left and right by the pressing of the cable fixing member 70. On the other hand, since the first contact point P1 is on the inclined surface portion 64b, the moving direction of the cable 4 is restricted to one direction, so that the cable 4 can be stably pressed. Among them, when a concave curved surface is formed on either the contact portion 73 or the second inner surface 64 and the other is a plane, the left and right movement of the cable 4 can be suppressed even with two-point contact.

[0072] In the field device 1 with the above structure, as Figure 2 shown, the cable fixing member 70 is fixed to the first inner surface 63 provided at a shallow position from the opening end surface 61 of the metal housing 31, and the outer shield 4c of the cable 4 is pressed to the second inner surface 64 provided at a deeper position than the first inner surface 63 by the cable fixing member 70 to obtain grounding. Thus, there is no need to perform cumbersome terminal processing of the cable 4, and the installation operation of the cable fixing member 70 can be carried out at a shallow position from the opening end surface 61, so that a solution for coping with the noise of the cable 4 can be simply implemented.

[0073] Thus, according to the above-described embodiment of the present invention, in the metal housing 31 of the field device 1 where the cable drawing-in portion 34 for drawing in the cable 4 having the outer shield 4c is provided on the cylindrical peripheral wall 31a, a first inner surface 63 is formed which is axially spaced apart from the opening end surface 61 in a direction orthogonal to the opening end surface 61 of the metal housing 31, and a second inner surface 64 is formed which is axially further away from the opening end surface 61 than the first inner surface 63. The metal housing 31 includes a cable fixing member 70 that is fixed to the first inner surface 63 and brings the outer shield 4c of the cable 4 drawn in from the drawing-in portion 34 into contact with the second inner surface 64. By adopting such a structure, in the field device 1 where the cable 4 is drawn in from a portion of the peripheral wall 31a far from the opening end surface 61, a solution for dealing with the noise of the cable 4 can be simply implemented without complicated terminal processing.

[0074] Moreover, in the present embodiment, as Figure 5 shown, an anti-rotation portion 66 for preventing the rotation of the cable fixing member 70 is formed on the first inner surface 63 in the metal housing 31. According to such a structure, rotation of the cable fixing member 70 about the bolt 80 can be suppressed. Thereby, the cable fixing member 70 can stably press the cable 4.

[0075] Moreover, in the present embodiment, the anti-rotation portion 66 has a convex shape that protrudes from the first inner surface 63 toward the opening end surface 61 and abuts against the side surface of the cable fixing member 70. According to such a structure, rotation of the cable fixing member 70 can be suppressed with a simple structure by the side surface of the cable fixing member 70 abutting against the convex anti-rotation portion 66.

[0076] Moreover, in the present embodiment, in a cross-sectional view of the cable 4, the cable fixing member 70 includes at least a second contact point P2 and a third contact point P3 that sandwich the center line L and are in contact with the outer shield 4c. The center line L passes through the first contact point P1 where the outer shield 4c contacts the second inner surface 64 and the center point O of the cable 4. According to such a structure, the cable 4 can be stably fixed at three points. Among them, if the cable 4 can be fixed at at least three points, the cable 4 can also be fixed at four or more points.

[0077] Moreover, in the present embodiment, as Figure 3 shown, a third inner surface 65 is formed on the metal housing 31 which is axially further away from the opening end surface 61 than the second inner surface 64, and a base portion 64A that protrudes from the third inner surface 65 toward the opening end surface 61 and is provided with the second inner surface 64. According to such a structure, by providing the base portion 64A starting from the third inner surface 65 and forming the second inner surface 64 to be approximately the same depth as the cable inlet 34a of the cable 4, the outer shield 4c of the cable 4 can be pressed against the second inner surface 64 to obtain grounding without forcibly bending the cable 4.

[0078] In addition, as Figure 6 shown, the cable connection container 20 of the detector 2 is connected to the metal housing 21 of the container 20, which also has substantially the same structure as the above-mentioned metal housing 31.

[0079] Figure 6 FIG. is a partial cross-sectional perspective view showing a state in which the first lid 22 is removed from the cable connection container 20 of the detector 2 according to an embodiment.

[0080] As Figure 6 shown, the cable connection container 20 of the detector 2 includes a cylindrical metal housing 21 extending in the Y-axis direction. An engaging groove 21a1 into which the first lid 22 is fitted and a flange 21a2 opposing the engaging portion of the first lid 22 in the Y-axis direction are formed on the peripheral wall 21a of the metal housing 21.

[0081] Hereinafter, there is a case where the direction (Y-axis direction) orthogonal to the opening end face 91 of the metal housing 21 is referred to as the axial direction. The axial direction is the direction in which the central axis O2 of the metal housing 21 extends. Inside the metal housing 21, a first inner surface 92 and a second inner surface 93 are formed away from the opening end face 91 in the axial direction (Y-axis direction). The first inner surface 92 and the second inner surface 93 do not overlap each other in a plan view along the central axis O2, and are surfaces facing the opening end face 91 side inside the metal housing 21.

[0082] The terminal box portions 50A and 50B are provided on the first inner surface 92, and the fixing portion 71 of the cable fixing member 70 is fixed by screwing via a bolt 80. The second inner surface 93 is provided to be farther from the opening end face 91 than the first inner surface 92. The second inner surface 93 becomes the inner wall surface of the drawing-in port 24a for drawing the cable 4 into the metal housing 21. Among them, the terminal box portions 50A and 50B may also be fixed to a surface closer to the opening end face 91 than the cable fixing member 70 and include the above-mentioned anti-rotation portion 66. In addition, the terminal box portions 50A and 50B themselves may also serve as a check member for the cable fixing member 70.

[0083] In the above structure, the cable fixing member 70 can also be fixed to the first inner surface 92 provided at a shallow position from the opening end face 91 of the metal housing 21, and the outer shield 4c of the cable 4 is pressed against the second inner surface 93 provided deeper than the first inner surface 92 by this cable fixing member 70 to obtain grounding. Thus, it is not necessary to perform complicated terminal processing of the cable 4, and the installation operation of the cable fixing member 70 can be performed at a shallow position from the opening end face 91, so that a solution for coping with the noise of the cable 4 can be simply implemented.

[0084] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. The various shapes and combinations of the respective structural components shown in the above embodiments are merely examples, and various changes can be made based on design requirements and the like without departing from the gist of the present invention.

[0085] For example, in the above embodiment, the structure of having a detector 2 that outputs a detection result and a converter 3 connected via the detector 2 and a cable 4, and both the detector 2 and the converter 3 having a metal field device housing (metal housings 21, 31) including the above-described cable fixing member 70 has been described. However, it may also be a structure in which either the detector 2 or the converter 3 has a metal field device housing including the above-described cable fixing member 70.

[0086] For example, in the above embodiment, the cable 4 is circular in a cross-sectional view, but it may also be quadrilateral or other polygons, elliptical or other special shapes, etc.

[0087] In this specification, terms indicating directions such as front, rear, upper, lower, right, left, vertical, horizontal, longitudinal, transverse, row, and column all refer to these directions in the device of the present invention. Therefore, these terms in the specification of the present invention should be interpreted relatively in the device of the present invention.

[0088] The expression "configured to..." is used to represent a configuration, element, or part of a device configured to achieve the functions of the present invention.

[0089] Moreover, expressions showing functional limitations in the claims should include all structures that can be used to achieve the functions included in the present invention.

[0090] The term "unit" is used to represent a part of a structural element, unit, hardware, or software written to achieve a desired function. A typical example of hardware is a device or a circuit, but it is not limited to these.

[0091] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other changes can be made without departing from the gist of the present invention. The present invention is not limited by the above description and is only limited by the appended claims.

Claims

1. A housing for a field device, which is made of metal and has a pulling-in portion provided on a cylindrical peripheral wall for pulling in a cable having an outer shield, characterized in that, Comprises: A first inner surface formed to be axially away from the opening end face of the field device housing and orthogonal to the opening end face; A second inner surface formed to be axially further away from the opening end face than the first inner surface; A cable fixing member fixed to the first inner surface and bringing the outer shield of the cable pulled in from the pulling-in portion into contact with the second inner surface, In a cross-sectional view of the cable, the cable fixing member has at least a second contact point and a third contact point that are in contact with the outer shield across the center line, and the center line passes through the first contact point where the outer shield contacts the second inner surface and the center point of the cable.

2. The field device housing according to claim 1, wherein, An anti-rotation portion for preventing the rotation of the cable fixing member is formed on the first inner surface.

3. The field device housing according to claim 2, wherein, The anti-rotation portion protrudes from the first inner surface toward the opening end face and has a convex shape that abuts against the side surface of the cable fixing member.

4. The field device housing according to claim 1, wherein, Comprises: A third inner surface formed to be axially further away from the opening end face than the second inner surface; A base portion formed to protrude from the third inner surface toward the opening end face and provided with the second inner surface.

5. The field device housing according to claim 4, wherein, Further comprises: A bottomed cylindrical metal housing extending in the axial direction; A cover body fitted to the metal housing.

6. The field device housing according to claim 5, wherein, The metal housing has a peripheral wall and a bottom wall, An engaging groove for fitting the cover body and a flange opposed to the engaging portion of the cover body in the axial direction are formed on the outer peripheral surface of the peripheral wall.

7. The field device housing according to claim 6, wherein, The pulling-in portion is provided on the peripheral wall, The pulling-in portion protrudes from the peripheral wall on the bottom wall side closer to the bottom wall than the flange in a direction tangential to the inner peripheral surface of the peripheral wall in a form that does not interfere with the cover body fitted to the peripheral wall.

8. The field device housing according to claim 5, wherein, Further comprises a terminal box portion provided inside the metal housing and connected to the cable pulled in from the pulling-in portion.

9. The field device housing according to claim 8, wherein, Further comprises a terminal box setting surface provided with the terminal box portion, The terminal box setting surface, the first inner surface, the second inner surface, and the third inner surface are surfaces that do not overlap each other in a top view along the central axis of the metal housing and face the opening end face inside the metal housing.

10. The field device housing according to claim 4, wherein, The first inner surface is formed at the front end of the base portion, The second inner surface is disposed at the same position in the axial direction as the pulling-in port of the pulling-in portion.

11. The field device housing according to claim 4, wherein, The cable fixing member comprises: A fixing portion fixed to the first inner surface; The hanging part is vertically arranged from the fixed part to the second inner surface; The contact part is bent from the hanging part and contacts the outer shield.

12. The field device housing according to claim 11, wherein, The fixed part is fixed to the first inner surface via bolts.

13. The field device housing according to claim 11, wherein, The hanging part is bent at a right angle relative to the fixed part to the opposite side of the opening end face.

14. The field device housing according to claim 11, wherein, The contact part includes: The first contact part is bent at a right angle relative to the hanging part to the side away from the base part; The second contact part is bent at an obtuse angle relative to the first contact part to the opposite side of the opening end face.

15. The field device housing according to claim 14, wherein, The first contact part has the second contact point, The second contact part has the third contact point.

16. A field device, characterized in that, Comprises: A detector that outputs a detection result; A converter that is connected to the detector via a cable; At least one of the detector and the converter has the field device housing according to any one of claims 1 to 3.

17. The field device according to claim 16, wherein, The detector has a piping part for fluid flow and a detection part for detecting the flow rate or flow volume of the fluid.

18. The field device according to claim 17, wherein, The detection part is arranged inside the piping part, A stress detection element for measuring the flow rate or flow volume of the fluid is provided inside the detection part.

19. The field device according to claim 18, wherein, The stress detection element detects the alternating lift acting on the vortex shedding body of the detection part, measures the frequency of the Karman vortex street, and measures the flow rate or flow volume of the fluid according to this frequency.

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