JP2012181062A - Force detector housing case and force measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep accuracy in pressure measurement by discharging residual air in a circumference, while protecting a seal diaphragm.SOLUTION: A force detector housing case 10 for housing a pressure sensor 210 includes: a cylindrical container; a flange part projecting from the container; and a seal diaphragm 244A to be arranged in the container. The force detector housing case includes: a first external case 12 having a bottom part 16 and a sidewall part 18; a pressure introduction hole 22 formed in the bottom part 16; a circular ring 48 to be arranged between the flange part and the bottom part 16 so as to allow the pressure introduction hole 22 to be inside the ring; and a push-in member (a screw-in metal fitting 28) for pressurizing the flange part against the bottom part 16 together with the circular ring 48, and forming a pressure introduction space 26 having the pressure introduction hole 22 with the diaphragm 244A as a part of a boundary. Discharge holes 24 are arranged, which penetrate between the side surface of the sidewall part 18 and the pressure introduction space 26.

Description

  The present invention relates to a force detector housing case and a force measuring device in which a force detector is housed in the force detector housing case, and particularly protects a diaphragm constituting the force detector and reduces the pressure of a liquid with a small error. It relates to measuring technology.

  Conventionally, force detectors that can measure pressure using a piezoelectric vibrator as a pressure-sensitive element are known as a water pressure gauge, a barometer, a differential pressure gauge, and the like. In a force detector using a piezoelectric vibrator, when a pressure in the detection axis direction is applied to the piezoelectric vibrator, the resonance frequency of the piezoelectric vibrator changes, and the force (pressure) applied to the force detector from the change in the resonance frequency. ) Is detected.

Patent Documents 1 and 2 disclose a pressure sensor that detects a difference between a pressure to be measured and a reference pressure.
FIG. 14 is a perspective view of the pressure sensor described in Patent Document 1. 15 shows a cross-sectional view of the pressure sensor according to Patent Document 1. FIG. 15 (a) shows a cross-sectional view with the XZ plane as a cut, and FIG. 15 (b) shows a cross-sectional view with the YZ plane as a cut.

  As shown in FIGS. 14 and 15, in the pressure sensor 210, a diaphragm 244 </ b> A and a diaphragm 244 </ b> B are formed on the end surface of a cylindrical housing 212, respectively. A first outer peripheral portion 216 serving as a flange is formed on the diaphragm 244A side of the housing 212. Further, the diaphragm 244A and the diaphragm 244B are connected by a center shaft 252. Further, one end of the pressure-sensitive element 258 in the longitudinal direction is attached to the housing 212 and the other end is attached to the center shaft 252. Then, the center shaft 252 is displaced in the direction of the resultant force of the pressure received by the diaphragms 244A and 244B. Due to this displacement, the pressure-sensitive element 258 receives a compressive stress or an extension stress from the longitudinal direction, whereby the magnitude relationship and the magnitude (relative pressure) between the pressure received by the diaphragm 244A and the pressure received by the diaphragm 244B can be detected. Therefore, with the above configuration, the pressure of the object to be measured can be detected with reference to the reference pressure environment. A similar configuration is also disclosed in Patent Document 2. In such a pressure sensor for measuring the relative pressure, a configuration for separating the pressure environment of one diaphragm and the pressure environment of the other diaphragm is required.

  FIG. 16 is a schematic diagram of the pressure sensor disclosed in Patent Document 3. In Patent Document 3, a circular ring 306 (O-ring) is sandwiched from both surfaces of an element 304 having a diaphragm 302, and the element 304 is inserted from the normal direction of the element 304 by an outer case 308 and an outer case 310, respectively. It is sandwiched. The circular ring 306 is tightened by the outer case 308, the outer case 310, and the element 304 to sandwich the element 304 having the diaphragm 302. As a result, the inner space 308a on the outer case side 308 of the diaphragm 302 and the inner space 310a on the outer case side 310 are separated from each other.

  The outer case 308 has a pressure introduction hole 308b connected to the inner space 308a, and the outer case 310 has a pressure introduction hole 310b connected to the inner space 310a. Therefore, by connecting the pressure introducing hole 308b and the pressure introducing hole 310b to different pressure environments, different pressure environments are formed on the front and back of the diaphragm 302, and the pressure sensor 300 capable of detecting the differential pressure between the different pressure environments. It has become. Similar techniques are also disclosed in Patent Documents 4 and 5. In Patent Document 6, a flange is sandwiched by using a gasket instead of an O-ring to separate the pressure environment between one surface and the other surface of the element.

  FIG. 17 shows a schematic diagram in which the pressure sensor according to Patent Document 1 is accommodated in the outer case, and FIG. 18 shows a schematic diagram showing a usage pattern of the pressure sensor in Patent Document 1 accommodated in the external case. The pressure sensor disclosed in Patent Document 1 can separate the pressure environments of two diaphragms in the same manner as in Patent Documents 3 to 6.

  That is, the outer case 400 that houses the pressure sensor 210 has a first outer case 402 that has a recess 404a that houses the diaphragm 244A side of the pressure sensor 210, and a second that has a recess 404a that houses the diaphragm 244B side of the pressure sensor 210. And an outer case 404. Here, a pressure introduction hole 402b is formed in the bottom surface of the recess 402a of the first outer case 402, and an opening hole 404b is formed in the recess 404a of the second outer case.

  Furthermore, it has an insertion hole 406a (same as the insertion hole 30 in FIG. 1 described later) having a dimension not less than the diameter of the housing 212 and not more than the diameter of the second outer peripheral portion 218 (flange). is doing. Therefore, the screw fitting 406 has a dimension to be inserted into the housing 212 and to be in contact with the second outer peripheral portion 218. Further, the screw fitting 406 is accommodated in the first outer case 402 and the second outer case 404, and has a male screw portion 406b screwed into the female screw portions 402c and 404c formed on the inner wall of each outer case on the outer side of the side wall. Have. A circular ring 408 (O-ring) is disposed on the surface of the second outer peripheral portion 218 on the diaphragm 244A side, and a circular ring 409 (O-ring) is disposed on the surface of the second outer peripheral portion 218 on the diaphragm 244B side. .

  Then, by screwing the screw fitting 406 into the first outer case 402, the circular ring 408 is pressed against the second outer peripheral portion 218 and the bottom surface of the concave portion 402a of the first outer case 402, and the circular ring 409 is moved to the second outer peripheral portion. The circular ring 408 and the circular ring 409 sandwich the second outer peripheral portion 218 (flange) by being in pressure contact with 218 and the screw fitting 406. Then, the second outer case 404 is screwed into the screw fitting 406.

  With such a configuration, the pressure sensor 210 is externally connected in a state where the pressure introduction space 412 on the first outer case 402 side and the inner space 414 on the second outer case 404 side are separated from each other by the circular ring 408 and the circular ring 409, respectively. It is structured to be stored in the case 400.

  For example, the relative pressure sensor 210 described in Patent Document 1 can be used when detecting the amount of groundwater by detecting the water pressure of the groundwater as shown in FIG. In this case, in the pressure sensor 210 accommodated in the outer case 400, the diaphragm 244A is opened to the groundwater side by introducing groundwater from the pressure introduction hole 402b, and the tube 416 attached to the opening hole 404b of the outer case 400 is used. The diaphragm 244B is opened to the atmospheric pressure side (relay box 418), and the water pressure on the groundwater side is detected by the difference between the two pressures.

JP 2010-019826 A JP 2010-019827 A No. 05-019797 Japanese Utility Model Publication No. 06-046339 Japanese Patent Laid-Open No. 2003-082829 Japanese Patent No. 3693890

  However, in such an outer case 400, the pressure introducing hole 402b is designed to be small in order to avoid the diaphragm 244A from colliding with a stone in the water and being damaged. Accordingly, when the pressure sensor 210 accommodated in the outer case 400 is introduced into the water, it becomes difficult to discharge the air remaining in the pressure introduction space 412 formed between the diaphragm 244A and the first outer case 402. Therefore, since this air serves as a buffer between water and the diaphragm 244A, the water pressure is not directly transmitted to the diaphragm 244A, and it is difficult to accurately measure the water pressure.

  Therefore, the present invention pays attention to the above-mentioned problems, and protects the diaphragm exposed to the liquid of the force detector that measures the pressure, and discharges the air remaining around the diaphragm to enable accurate pressure measurement. It is an object to provide a container housing case and a force measuring device.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following application examples.
[Application Example 1] A container having a cylindrical outer shape, a male screw portion formed along the outer periphery of the side surface of the container, and disposed on the end surface of the container to be displaced inside or outside the container upon receiving a force. A force detector housing case for housing a force detector that detects pressure by displacement of the diaphragm, and a bottom portion facing the diaphragm, and a side wall portion facing the side surface of the container. An outer case, a pressure introducing hole formed in the bottom, and an inner periphery of the side wall, screwed into the male screw, and the diaphragm as a part of the boundary, the pressure introducing And a female screw part that forms a pressure introduction space having a hole, and a discharge hole that penetrates between a side surface of the side wall part and the pressure introduction space is provided.
With the above configuration, the air remaining between the force detector housing case and the force detector can be efficiently discharged, and the pressure of the liquid can be measured with high accuracy.

Application Example 2 A container having a cylindrical outer shape, a flange portion that protrudes to the outer peripheral side of the side surface of the container and is concentric with the outer periphery of the side surface, and an inner side of the container that receives a force and is arranged on an end surface of the container Or a force detector housing case for housing a force detector for detecting pressure by displacement of the diaphragm, and facing a bottom portion facing the diaphragm and a side surface of the container. An outer case having a side wall portion, a pressure introduction hole formed in the bottom portion, and a ring shape, disposed between the flange portion and the bottom portion, and the pressure introduction hole being an inner side of the ring A circular ring arranged in such a manner that the flange portion is pressed against the bottom side together with the circular ring, the diaphragm is part of the boundary in the outer case, and the pressure introduction hole Force detector accommodating case, characterized in that it comprises a pushing member forming a pressure introducing space, a discharge hole penetrating between the side surface and the pressure introduction space of the side wall portion is provided with.
With the above configuration, the air remaining between the force detector housing case and the force detector can be efficiently discharged, and the pressure of the liquid can be measured with high accuracy.

Application Example 3 The force detector housing case according to Application Example 1 or 2, wherein a plurality of the discharge holes are formed so as to be centrosymmetric with respect to the center of the bottom.
With the above configuration, the air remaining in the pressure introduction space between the force detector housing case and the force detector can be discharged evenly.

Application Example 4 The discharge hole penetrates between the side surface of the side wall portion and the inner wall of the pressure introduction hole and merges with the pressure introduction hole to thereby form the side surface of the side wall portion and the pressure introduction space. The force detector housing case according to Application Example 1 or 2, wherein the force detector housing case penetrates between the two.
With the above configuration, air remaining in the pressure introduction space between the force detector housing case and the force detector can be discharged regardless of the shape of the force detector.

Application Example 5 The discharge hole is dug from a position that is a side surface of the bottom portion of the side wall portion to a position that is different from the pressure introduction hole of the bottom portion and that opposes the pressure introduction space. The force detector housing case according to application example 1 or 2, wherein the pressure detector space penetrates to the pressure introducing space in a state of being bent and dug into the introducing space side.
With the above configuration, in the pressure introduction space between the force detector housing case and the force detector, liquid flows in from the pressure introduction hole, while air remaining in the pressure introduction space is discharged to the outside through the discharge hole. The Therefore, since the liquid inflow path and the air discharge path are separated, interference between the inflowing liquid and the discharged air is avoided, and the air remaining in the pressure introduction space is efficiently discharged. Can do.

Application Example 6 The force detector housing according to any one of Application Examples 1 to 5, wherein a plurality of the pressure introduction holes are formed so as to be centrosymmetric with respect to a center of the bottom portion. Case.
With the above configuration, the liquid can be uniformly introduced into the pressure introduction space between the force detector housing case and the force detector, and the air remaining in the pressure introduction space can be efficiently discharged.

[Application Example 7] The force detector housing case according to any one of Application Examples 1 to 5, wherein the pressure introducing hole is covered with a mesh-like net part.
With the above configuration, the diameter of the pressure introduction hole can be designed to be large, and the liquid can be efficiently introduced into the pressure introduction space between the force detector housing case and the force detector while protecting the diaphragm. .

Application Example 8 A concave portion is formed at a position of the bottom portion facing the end surface of the container, and the discharge hole penetrates between a side surface of the side wall portion and a side surface of the concave portion. The force detector housing case according to any one of Examples 2 to 7.
With the above configuration, air is discharged from the side surface of the pressure introduction space between the force detector housing case and the force detector, so that the air remaining in the pressure introduction space can be efficiently discharged.

Application Example 9 The force detector storage case according to Application Example 8, wherein the concave portion has a shape that follows the outer periphery of the end surface of the container and can store the end surface side of the container.
With the above configuration, the volume of the pressure introduction space can be reduced, so that the air remaining in the pressure introduction space can be easily discharged.

[Application Example 10] A force measuring instrument characterized in that the force detector is accommodated in the force detector accommodating case described in any one of Application Examples 1 to 9.
With the above configuration, a force measuring device capable of measuring the accurate liquid pressure by efficiently discharging the air remaining in the pressure introduction space between the force detector housing case and the force detector.

It is a disassembled perspective view of the force detector storage case of 1st Embodiment. It is the perspective view which accommodated the force detector in the force detector accommodation case of a 1st embodiment. It is a partial sectional view of the force detector storage case of the first embodiment. It is sectional drawing which accommodated the force detector in the force detector accommodation case of 1st Embodiment. FIG. 5A shows a pressure introduction hole and a discharge hole formed at the bottom of the force detector housing case of the first embodiment, FIG. 5A is a bottom view of FIGS. 3 and 4, and FIG. 5B is a first modification. FIG. 5C shows a second modification. FIG. 6 is a schematic view in which a mesh-like net is provided in a pressure introduction hole formed in the bottom of the force detector housing case of the first embodiment, FIG. 6 (a) is a bottom view, and FIG. 6 (b) is a cross-sectional view. It is. It is sectional drawing which accommodated the force detector in the force detector accommodation case of 2nd Embodiment. It is sectional drawing of the force detector accommodated in the force detector accommodating case of 3rd Embodiment, Fig.8 (a) is sectional drawing which made XZ surface a cut surface, FIG.8 (b) is a cross section which made YZ surface a cut surface. FIG. It is a partial sectional view of a force detector accommodation case of a 3rd embodiment. It is sectional drawing which accommodated the force detector in the force detector accommodation case of 3rd Embodiment. It is sectional drawing which accommodated the force detector in the force detector accommodation case of 4th Embodiment. It is a disassembled perspective view of the force detector storage case of 5th Embodiment. It is sectional drawing which accommodated the force detector in the force detector accommodation case of 5th Embodiment. FIG. 11 is a perspective view of a pressure sensor according to Patent Document 1 (a cross-sectional view with a YZ plane as a cut surface). FIG. 15A is a cross-sectional view of the pressure sensor according to Patent Document 1, FIG. 15A is a cross-sectional view with the XZ plane as a cut, and FIG. 15B is a cross-sectional view with the YZ plane as a cut. 6 is a schematic diagram of a pressure sensor described in Patent Document 3. FIG. It is the schematic diagram which accommodated the pressure sensor concerning patent documents 1 in the conventional pressure sensor accommodation case. It is the schematic diagram which showed the usage pattern of the pressure sensor of patent document 1 accommodated in the conventional pressure sensor storage case.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. . It is assumed that the X axis, Y axis, and Z axis shown in the figure form an orthogonal coordinate system.

  The force detector to which the force detector housing case of the first embodiment is applied is the pressure sensor 210 shown in FIGS. Here, after describing the pressure sensor 210 in detail, the force detector housing case 10 of the first embodiment will be described.

  As shown in FIG. 15A, the pressure sensor 210 has a cylindrical shape with the line segment O as the central axis. The pressure sensor 210 forms a container that hermetically seals the inside by the housing 212, the diaphragm 244A, and the diaphragm 244B. And the pressure sensitive element 258, the support shaft 236, the center shaft 252 etc. are provided in the accommodation space of the container provided with the diaphragm 244A and the diaphragm 244B. The pressure sensor 210 is a relative pressure sensor in which the pressure-sensitive element 258 detects a differential force between the pressure received by the diaphragm 244A and the pressure received by the diaphragm 244B. The inside of the container is vacuum sealed.

  The housing 212 includes a circular first end plate 214, a circular second end plate 224, a support shaft 236, and a cylindrical side wall portion 242. The first end plate 214 includes a first outer peripheral portion 216 in contact with the inner wall of the cylindrical side wall portion 242, a second outer peripheral portion 218 in contact with the end portion of the side wall portion 242, the first outer peripheral portion 216 and the second outer peripheral portion. An opening 220 communicating with 218 is formed concentrically. The second outer peripheral portion 218 serves as a flange portion 222 that contacts a circular ring 46 and a circular ring 48 described later on both surfaces thereof.

  Here, the diameters of the second outer peripheral portion 218 and the side wall portion 242 are the same. Therefore, the diameter of the first outer peripheral portion 216 is smaller than the diameter of the second outer peripheral portion 218 by the thickness of the side wall portion 242. Further, the end surface on the −Z-axis side of the second outer peripheral portion 218 is exposed to an environment to be measured for pressure as described later. The diaphragm 244 </ b> A seals the opening 220 at the end of the opening 220 in the −Z-axis direction.

  The second end plate 224 has a diameter whose outer shape is in contact with the inner wall of the side wall 242, and has a recess 226 that is dug from the surface on the + Z-axis side and formed concentrically on the second end plate 224. The opening of the recess 226 is sealed with a diaphragm 244B. Further, a boss portion 228 is formed concentrically with the second end plate 224 on the surface on the −Z-axis side of the second end plate 224, and further, the boss portion 228 and the recess 226 are communicated in the Z-axis direction. An insertion hole 230 through which 252 is inserted is formed.

  The boss portion 228 is a portion to which a pressure sensitive element 258 described later is connected. The boss portion 228 is formed in a circular shape when viewed from the Z-axis direction, but it is desirable that a portion connected to a first base portion 262 of a pressure sensitive element 258 described later be formed in a plane. Of course, the boss portion 228 may be formed in a polygonal shape such as a rectangle as viewed from the Z-axis direction.

  A hole 232 into which the support shaft 236 is fitted is formed on the surface of the first outer peripheral portion 216 of the first end plate 214 facing the second end plate 224, and the surface of the second end plate 224 facing the first end plate 214. In addition, a hole 234 into which the support shaft 236 is fitted is formed. Therefore, the hole 232 and the hole 234 are formed at positions facing each other. Then, the first end plate 214 and the second end plate 224 are connected via the support shaft 236 by fitting the support shaft 236 into the holes 232 and 234.

  The support shaft 236 is a rod-shaped member having a certain rigidity and having a longitudinal direction in the ± Z direction. The support shaft 236 is disposed inside a container including the housing 212, the diaphragm 244A, and the diaphragm 244B. One end of the first end plate 214 is inserted into the hole 232 of the first end plate 214 and the other end is inserted into the hole 234 of the second end plate 224, so that the first end plate 214, the support shaft 236, and the second end plate 224 are connected. To obtain a certain rigidity. Although a plurality of support shafts 236 are used, they are arbitrarily arranged according to the design of the position of each hole.

  A hermetic terminal 238 (see FIG. 15) is attached to the second end plate 224. The hermetic terminal 238 is for applying an alternating voltage to an electrode portion (not shown) of the pressure sensitive element 258 to oscillate the pressure sensitive element 258. The hermetic terminal 238 connects an IC (integrated circuit, not shown) attached to the outer surface of the housing 212 or spaced apart from the housing 212 and the pressure-sensitive element 258 to the wire 240. Can be electrically connected. Although one hermetic terminal 238 is illustrated in FIG. 14, it is assumed that it is attached to the second end plate 224 in accordance with the total number of electrode portions (not shown) of the pressure sensitive element 258.

  The cylindrical side wall portion 242 is formed so that its inner diameter is equal to the diameter of the first outer peripheral portion 216 of the first end plate 214 and the diameter of the second end plate 224. Therefore, the housing 212 and the diaphragm 244A are connected by connecting the end portion of the side wall portion 242 to the second outer peripheral portion 218 and connecting the inner wall of the side wall portion 242 to the outer wall of the first outer peripheral portion 216 and the outer wall of the second end plate 224. The container formed by the diaphragm 244B is sealed. The first end plate 214, the second end plate 224, and the side wall portion 242 are preferably formed of a metal such as stainless steel, and the support shaft 236 is preferably made of ceramic having a certain rigidity and a small thermal expansion coefficient.

  The diaphragms 244A and 244B have one main surface facing the outside of the housing 212 as a pressure receiving surface, and the pressure receiving surface has a flexible portion 248 that is bent and deformed under the pressure of the pressure environment to be measured (for example, liquid). is doing. The flexible portion 248 is bent and deformed so as to be displaced inward or outward (Z-axis direction) of the housing 212, thereby transmitting a compressive force or tensile force along the Z-axis to the pressure-sensitive element 258. . Accordingly, the diaphragms 244A and 244B are located at the center portion 246 that is displaced by the pressure from the outside and the outer periphery of the center portion 246, and the flexible portion 248 that is bent and deformed by the pressure from the outside so that the center portion 246 can be displaced. Have In addition, the diaphragm 244 </ b> A is provided on the outer periphery of the flexible portion 248, and has a peripheral edge 250 connected to the −Z-axis side end of the opening 220 of the first end plate 214. Further, the diaphragm 244B has a peripheral edge 250 that is fixedly bonded to the opening of the recess 226 of the second end plate 224. It is assumed that the peripheral portion 250 is ideally not displaced even when subjected to pressure, and the central portion 246 is not deformed even when subjected to pressure.

  The material of the diaphragms 244A and 244B is preferably a material having excellent corrosion resistance such as a metal such as stainless steel or ceramic, and may be a single crystal such as crystal or other non-crystalline material. For example, in the case of forming with metal, the metal base material may be formed by pressing, and in the case of forming with crystal, photolithography / etching may be performed so that the flexible portion becomes thinner than other portions.

  The diaphragms 244A and 244B may be coated with a corrosion-resistant film on the surface exposed to the outside so as not to be corroded by liquid or gas. For example, a nickel diaphragm may be coated with a nickel compound, and if the diaphragm is a piezoelectric crystal such as quartz, silicon may be coated. Similarly, when the housing 212 of the pressure sensor 210 is made of metal or the like, the surface thereof may be coated with a nickel compound.

  A center shaft 252 serving as a force transmission means connects the diaphragm 244A and the diaphragm 244B. The center shaft 252 is disposed in the housing 212 and has a longitudinal direction in the Z-axis direction. One end in the longitudinal direction is connected to the central portion 246 of the diaphragm 244A, and the other end is connected to the central portion 246 of the diaphragm 244B. As the material of the center shaft 252, it is preferable to use a ceramic having a certain rigidity and a small thermal expansion coefficient, like the support shaft 236.

  Further, a fixed portion 254 is attached to the center portion of the center shaft 252. The fixing portion 254 has a through hole 256 that is inserted through the center shaft 252 in the Z-axis direction and connected to the center shaft 252. Therefore, the fixed portion 254 is displaced in the Z-axis direction as the center shaft 252 is displaced in the Z-axis direction. The first base 262 of the pressure-sensitive element 258 is connected to the side surface of the boss portion 228, and the second base 264 of the pressure-sensitive element 258 is connected to the side surface of the fixed portion 254. At this time, it is desirable that the portion of the boss portion 228 to which the pressure sensitive element 258 is attached and the portion of the fixed portion 254 to which the pressure sensitive element 258 is attached are arranged so as to form the same plane. Thereby, when attaching the pressure sensitive element 258 to the boss | hub part 228 and the fixing | fixed part 254, the pressure sensitive element 258 is not deformed and the measurement error of the pressure value by the deformation | transformation by this can be suppressed.

  The pressure-sensitive element 258 is formed of a piezoelectric material such as quartz, lithium niobate, or lithium tantalate, and includes a vibrating arm 260 and a first base 262 and a second base 264 formed at both ends thereof. The first base portion 262 is connected to the side surface of the boss portion 228, and the second base portion 264 is connected to the side surface of the fixing portion 254. Therefore, the pressure sensitive element 258 is connected to the housing 212 (container) via the boss portion 228 and connected to the center shaft 252 which is a force transmission means via the fixing portion 254. The pressure-sensitive element 258 has a longitudinal direction (Z-axis direction), that is, a direction in which the first base portion 262 and the second base portion 264 are arranged in the displacement direction (Z-axis) of the center shaft 252, the diaphragm 244A, and the diaphragm 244B. The direction of displacement is a detection axis.

  Further, an excitation electrode (not shown) is formed on the vibrating arm 260 of the pressure-sensitive element 258, and has an electrode portion (not shown) electrically connected to the excitation electrode (not shown). An electrode portion (not shown) of the pressure-sensitive element 258 is electrically connected to an IC (not shown) via a hermetic terminal 238 and a wire 240, and has an inherent resonance due to an AC voltage supplied from the IC (not shown). Vibrates at frequency. The pressure-sensitive element 258 changes its resonance frequency when it receives an extensional stress or a compressive stress from its longitudinal direction (Z-axis direction).

  In the present embodiment, a double tuning fork vibrator can be applied as the vibrating arm 260 serving as a pressure-sensitive portion. The characteristic of the double tuning fork vibrator is that when a tensile stress (elongation stress) or a compressive stress is applied to the two vibrating beams that are the vibrating arms 260, the resonance frequency thereof changes approximately in proportion to the applied stress. There is. The double tuning fork type piezoelectric resonator element has a very large resonance frequency change with respect to elongation / compression stress and a large variable range of the resonance frequency compared to a thickness shear vibrator, etc. It is suitable for a pressure sensor (force detector) that excels. When the double tuning fork type piezoelectric vibrator is subjected to an elongation stress, the resonance frequency of the vibrating arm 260 is increased, and when the compressive stress is applied, the resonance frequency of the vibrating arm 260 is decreased.

  In the present embodiment, not only a pressure-sensitive part having two columnar vibration beams but also a pressure-sensitive part composed of a single vibration beam (single beam) can be applied. If the pressure-sensitive part (vibrating arm) is configured as a single beam type vibrator, the displacement is doubled when subjected to the same stress from the longitudinal direction (detection axis direction), which is higher than in the case of a double tuning fork. It can be set as a sensitive pressure sensor (force detector).

  In the present embodiment, when the pressure applied to the diaphragm 244A is larger than the pressure applied to the diaphragm 244B, the center shaft 252 is displaced in the + Z-axis direction, so that the pressure-sensitive element 258 is compressed in the Z-axis direction. The resonance frequency is lowered due to the stress. On the other hand, when the pressure applied to the diaphragm 244A is smaller than the pressure applied to the diaphragm 244B, the center shaft 252 is displaced in the −Z-axis direction, so that the pressure-sensitive element 258 receives a tensile stress in the Z-axis direction. Therefore, the resonance frequency becomes high.

  Of the above-described piezoelectric materials, quartz having excellent temperature characteristics is desirable for a piezoelectric substrate of a double tuning fork type or single beam type piezoelectric vibrator. When the pressure sensitive element is made of quartz, it is preferable to form it by photolithography / etching as described above.

  In assembling the pressure sensor 210 of the first embodiment, first, the diaphragm 244A is connected to the first end plate 214, and the diaphragm 244B is connected to the second end plate 224 (with hermetic terminal 238). Then, the support shaft 236 is fitted and connected to the hole 232 of the first end plate 214, and one end of the center shaft 252 (with the fixing portion 254) is connected to the central portion 246 of the diaphragm 244A. Then, the center shaft 252 is passed through the insertion hole 230 of the second end plate 224, and the other end of the center shaft 252 is connected to the center portion 246 of the diaphragm 244B. At this time, the support shaft 236 is fitted into the hole 234 of the second end plate 224 to be connected.

  Next, the first base portion 262 of the pressure sensitive element 258 is connected to the side surface of the boss portion 228 of the second end plate 224, and the second base portion 264 is connected to the side surface of the fixing portion 254. Then, an electrode portion (not shown) of the pressure sensitive element 258 and the hermetic terminal 238 are connected by a wire 240.

  Finally, the pressure sensor 210 is constructed by inserting a structure including the above-described components through the cylindrical side wall 242 and connecting the side wall 242 to the first end plate 214 and the second end plate 224. In order to make the inside of the container of the pressure sensor 210 into a vacuum, the above-described structure and the side wall 242 may be attached in a vacuum chamber. Further, a sealing hole (not shown) is formed in the side wall part 242, and after the side wall part 242 is connected, the inside of the container is vacuumed from the sealing hole (not shown), and the sealing hole (not shown) is used as a sealing member. You may seal by (not shown).

  FIG. 1 is an exploded perspective view of the force detector housing case of the first embodiment. FIG. 2 shows a perspective view in which the force detector is accommodated in the force detector accommodating case of the first embodiment. FIG. 3 shows a partial cross-sectional view of the force detector housing case of the first embodiment. Further, FIG. 4 shows a cross-sectional view in which the force detector is accommodated in the force detector accommodating case of the first embodiment.

  The force detector housing case 10 for housing the pressure sensor 210 includes a first outer case 12, a second outer case 34, and a screw fitting 28, and has a cylindrical shape centered on the line segment O, similar to the pressure sensor 210. is doing. A circular ring 46 (O-ring) is disposed on the surface in the + Z-axis direction of the flange portion 222 of the pressure sensor 210, and a circular ring 48 (O-ring) is disposed on the surface in the −Z-axis direction (FIG. 12). reference). The screw fitting 28 (pushing member) and the circular rings 46 and 48 serve as fixing means for fixing the pressure sensor 210 in the force detector housing case 10. By adopting such a fixing means, the pressure environment in which the diaphragm 244A is in contact with the other part of the pressure sensor 210 can be separated from the other parts of the pressure sensor 210 with a simple configuration, and pressure can be introduced between the force detector housing case 10 and the pressure sensor 210. The pressure (force) in the space 26 can be measured.

  The first outer case 12 has a recess 14 that accommodates the diaphragm 244A side of the pressure sensor 210, and a female that is formed along the inner periphery of the first outer case 12 and that is screwed into the screw fitting 28 in the opening of the recess 14. A screw portion 20 is formed.

  A pressure introducing hole 22 penetrating in the Z-axis direction is formed at the center of the bottom 16 of the first outer case 12. Further, a discharge hole 24 penetrating from the side surface of the side wall portion 18 of the first outer case 12 and the side surface of the bottom portion 16 to the side wall of the pressure introduction hole 22 is formed.

  The second outer case 34 has a recess 36 that accommodates the diaphragm 244B side of the pressure sensor 210. In addition, the second outer case 34 is formed with an internal thread portion 40 that is formed along the inner periphery of the second outer case 34 and that is screwed into the screw fitting 28. Further, an open hole 38 is formed in the center of the recess 36 of the second outer case 34. The open hole 38 is connected to a hollow tube 42.

  The screw fitting 28 is a pushing member that pushes the container (flange portion 222) of the pressure sensor 210 together with the circular ring 46 and the circular ring 48 into the bottom portion 16 side. The screw fitting 28 has an insertion hole 30 (see FIG. 1) having a dimension not less than the diameter of the side wall portion 242 and not more than the diameter of the flange portion 222, and is inserted into the side wall portion 242 and on the surface on the + Z axis side of the flange portion 222. It has a cylindrical shape that can contact. The screw fitting 28 is accommodated in the first outer case 12 and the second outer case 34, and a male screw portion 32 that engages with the female screw portions 20 and 40 formed on the inner wall of each outer case has an outer periphery of the side wall 28a. It is formed along. Here, when the male screw portion 32 is screwed into the female screw portions 20 and 40, there is no leakage of liquid or gas between the male screw portion 32 and the female screw portions 20 and 40.

  The circular ring 46 is a ring-shaped elastic body having an inner diameter that follows the outer periphery of the side wall 242, and the circular ring 48 is a ring-shaped elastic body having the same inner diameter as the circular ring 48. Here, the diameters (thicknesses) of the circular cross sections of the circular ring 46 and the circular ring 48 coincide with each other.

  In the above configuration, the screw fitting 28 is brought into contact with the outer case (first outer case 12) by screwing the male screw portion 32 into the female screw portion 20. Then, by the above-described screwing, the circular ring 46 disposed on the flange portion 222 comes into contact. The screw fitting 28 receives a drag force from the circular ring 46 by advancing the screwing. However, the screw fitting 28 receives the reaction force from the outer case (first outer case 12), so that the flange portion 222 is connected to the circular ring 46 and the circular ring. 48 can be pressed against the bottom 16 side. Therefore, the circular ring 46 is pressed against the surface on the + Z-axis side of the flange portion 222 and the surface on the −Z-axis side of the screw fitting 28. The circular ring 48 is brought into pressure contact with the surface on the + Z-axis side of the bottom portion 16 and the surface on the −Z-axis side of the flange portion 222, and is compressed and deformed.

  Then, by pressure contact with the flange portion 222 and the bottom portion 16 of the circular ring 48, the pressure introduction space having the pressure introduction hole 22 and the discharge hole 24 with the first outer case 12, the pressure sensor 210 (diaphragm 244A), and the circular ring 48 as a boundary. 26 is formed. Further, the inner space 44 having the open hole 38 with the second outer case 34, the screw fitting 28, the pressure sensor 210 (diaphragm 244B), and the circular ring 46 as a boundary by pressure contact with the flange portion 222 of the circular ring 46 and the screw fitting 28. Is formed. Therefore, the pressure environment of the diaphragm 244A and the diaphragm 244B can be separated by the circular ring 46 and the circular ring 48.

  Therefore, for example, by opening one end of the tube 42 (see the tube 416 in FIG. 16) under a reference pressure environment (for example, atmospheric pressure), the second outer case 34, the pressure sensor 210, and the circular ring 46 are formed. The internal space 44 and the diaphragm 244B can be exposed to a reference pressure environment (for example, atmospheric pressure). In this case, a wire (not shown) may be connected to the hermetic terminal 238 exposed to the outside of the pressure sensor 210, and inserted into the open hole 38 and the tube 42 and connected to the IC (not shown).

  On the other hand, by exposing the pressure introduction hole 22 and the discharge hole 24 to the measured pressure environment, the first outer case 12, the pressure sensor 210, the pressure introduction space 26 formed by the circular ring 48, and the diaphragm 244A are measured pressure. Can be exposed to the environment (eg water pressure).

  FIG. 5 shows a pressure introduction hole and a discharge hole formed at the bottom of the force detector housing case of the first embodiment. FIG. 5 (a) is a bottom view of FIGS. 3 and 4, and FIG. The first modified example, FIG. 5C shows a second modified example. FIG. 6 is a schematic view in which a mesh-like net is provided at the pressure inlet formed at the bottom of the force detector housing case of the first embodiment. FIG. 6 (a) is a bottom view and FIG. b) is a sectional view.

  As shown in FIG. 5A, the pressure introducing hole 22 is formed at a position that becomes the center of the bottom portion 16. The discharge hole 24 is formed so as to form a cross with the pressure introduction hole 22 as the center when viewed from the Z-axis direction.

  Further, as shown in the first modification of FIG. 5B, two pressure introduction holes 22 are formed, and the discharge holes 24 are formed so as to form two crosses around the pressure introduction holes 22. it can.

  Further, as shown in the second modified example of FIG. 5C, four pressure introduction holes 22 are formed, and the discharge holes 24 are formed so as to form four crosses around the pressure introduction holes 22. Can do.

  As shown in FIG. 5, the pressure introducing hole 22 is preferably formed at a position that is symmetrical with respect to the center of the bottom portion 16. Thereby, the liquid is uniformly introduced into the pressure introduction space 26 between the force detector housing case 10 and the pressure sensor 210 (diaphragm 244A), and the air remaining in the pressure introduction space 26 is efficiently discharged. The pressure of the liquid can be accurately measured. Similarly, the discharge hole 24 is preferably formed at a position that is centrosymmetric with respect to the center of the bottom portion 16. The air remaining in the pressure introducing space 26 (air remaining around the diaphragm 244A) can be efficiently discharged without unevenness.

  Further, in FIG. 5, the discharge hole 24 penetrates between the side surface of the side wall portion 18 and the inner wall of the pressure introduction hole 22 and merges with the pressure introduction hole 22, whereby the side surface of the side wall portion 18 and the pressure introduction space 26. It is the structure which penetrates between. Thereby, air remaining in the pressure introduction space 26 between the force detector housing case 10 and the pressure sensor 210 (air remaining around the diaphragm 244A) is discharged regardless of the shape of the pressure sensor 210 on the diaphragm 244A side. The pressure of the liquid can be measured with high accuracy.

  Then, as shown in FIG. 6B, the diameter of the pressure introduction hole 22 is formed so as to be smaller than the inner diameter of the circular ring 48 in plan view from the Z-axis direction. The net part 23 may be provided. The net part 23 has a large number of holes through which liquid or air can be inserted without passing through a solid (for example, a stone in water) to be measured for pressure. The mesh portion 23 is attached to the pressure introduction hole 22 by preparing a mesh portion having a diameter larger than the diameter of the pressure introduction hole 22 and bending the circumference of the mesh portion to one side so that the pressure introduction hole 22 has substantially the same diameter. What is necessary is just to form the welding margin 23a formed in the circular part which has, and its periphery, and to connect this welding margin 23a and the inner wall of the pressure introduction hole 22 by welding. Accordingly, the diameter of the pressure introduction hole 22 can be designed to be large, and the pressure introduction space 26 between the force detector housing case 10 and the pressure sensor 210 (diaphragm 244A) can be efficiently formed while protecting the diaphragm 244A. Liquid can be introduced.

  The pressure introduction hole 22 is formed at a position that fits inside the circular ring 48 in plan view so as to penetrate the bottom surface of the bottom 16 of the first outer case 12 and the pressure introduction space 26. The pressure introduction hole 22 and the discharge hole 24 can be formed by drilling.

  The first outer case 12, the second outer case 34, the screw fitting 28, and the mesh portion 23 are preferably formed of stainless steel or the like, and the surface is coated with a corrosion-resistant film so as not to be corroded by liquid or gas. May be. For example, if these are made of metal, a nickel compound may be coated.

  FIG. 7 shows a cross-sectional view in which the force detector is accommodated in the force detector accommodating case according to the second embodiment. The force detector housing case 50 according to the second embodiment is basically similar to the first embodiment, but the discharge hole 52 is a pressure introduction space in a plan view from a position that is the side surface of the bottom portion 16 of the side wall portion 18. It is different in that it is dug up to a position facing 26 and bent to the pressure introduction space 26 side so as to penetrate to the pressure introduction space 26. That is, the discharge hole 52 is formed so as to reach a position different from the pressure introduction hole 22 formed in the bottom portion 16. In this case, the discharge hole 52 drills the horizontal hole 54 from a position that is the side surface of the bottom 16 of the side wall portion 18 to a position that opposes the pressure introduction space 26 in plan view (up to a position that is inside the circular ring 48 in plan view). The vertical hole 56 is dug by drilling from the position facing the end of the horizontal hole 54 on the concave portion 14 (see FIG. 1 and FIG. 3) side of the bottom 16, and the horizontal hole 54 and the vertical hole 56. It is formed by connecting.

  With the above configuration, in the pressure introduction space 26 between the force detector housing case 50 and the pressure sensor 210, liquid (water) flows from the pressure introduction hole 22, while air remaining in the pressure introduction space 26 discharges the discharge hole 52. It is discharged outside via Therefore, since the liquid inflow path and the air discharge path are separated, interference between the inflowing liquid and the discharged air is avoided, and the air remaining in the pressure introduction space 26 (the periphery of the diaphragm 244A) Can be discharged efficiently.

  FIG. 8 shows a cross-sectional view of the force detector accommodated in the force detector housing case of the third embodiment. FIG. 8 (a) is a cross-sectional view with the XZ plane as a cut, and FIG. 8 (b) is a YZ plane. Sectional drawing made into the cut end is shown. FIG. 9 shows a partial cross-sectional view of the force detector housing case of the third embodiment. Further, FIG. 10 shows a sectional view in which the force detector is accommodated in the force detector accommodating case of the third embodiment.

  The pressure sensor 211 (force detector) to which the force detector housing case of the third embodiment is applied is basically the same as the pressure sensor 210, but is around the second outer peripheral portion 218 and the first outer periphery. A difference is that a flange portion 223 is formed concentrically with the second outer peripheral portion 218 at a position on the portion 216 side. The thickness of the flange portion 223 in the Z-axis direction is thinner than the thickness of the second outer peripheral portion 218 in the Z-axis direction. Therefore, there is a step in the Z-axis direction between the end surface on the −Z-axis side of the second outer peripheral portion 218 and the end surface on the −Z-axis side of the flange portion 223, and the end surface on the −Z-axis side of the second outer peripheral portion 218 is The flange portion 223 protrudes in the −Z-axis direction from the end surface on the −Z-axis side. The circular ring 66 abuts on the surface of the flange portion 223 on the + Z axis side, and the circular ring 68 abuts on the surface of the flange portion 223 on the −Z axis side.

  On the other hand, the force detector housing case 60 of the third embodiment is basically similar to the first embodiment, but as shown in FIGS. 9 and 10, is a surface of the bottom portion 16 on the diaphragm 244A side. A recess 62 is formed at a position inside the circular ring 68 in plan view from the Z-axis direction, and the discharge hole 64 is different in that it penetrates between the side surface of the side wall portion 18 and the side surface of the recess 62. Accordingly, air is discharged from the side surface of the pressure introduction space 26 between the force detector housing case 60 and the pressure sensor 211, so that the air remaining in the pressure introduction space 26 can be efficiently discharged.

  Furthermore, in this embodiment, the recessed part 36 is different by the point which can accommodate the diaphragm 244A side of the container of the pressure sensor 211, ie, the 2nd outer peripheral part 218. FIG. For this reason, the recess 36 is formed so that its inner diameter is larger than the diameter of the second outer peripheral portion 218. Then, as shown in FIG. 10, the end surface on the −Z-axis side of the second outer peripheral portion 218 is positioned on the −Z-axis side from the surface on the + Z-axis side of the bottom portion 16, and the −Z-axis side of the second outer peripheral portion 218 is a concave portion. It becomes the form which went into 36. Thereby, since the volume of the pressure introduction space 26 can be reduced, the air remaining in the pressure introduction space 26 (air remaining around the diaphragm 244A) can be easily discharged.

  The circular ring 66 and the circular ring 68 have the same cross-sectional diameter, but in the present embodiment, the diameters of the second outer peripheral portion 218 and the side wall portion 242 are the same. The inner diameters of the circular rings 68 also coincide with each other.

  In the third embodiment, it has been described that the pressure sensor 211 is accommodated in the force detector accommodating case 60. However, the pressure sensor 210 described in the first embodiment and the like is also accommodated in the force detector accommodating case 60 of the present embodiment. be able to. In this case, the second outer peripheral portion 218 does not enter the recess 36, but the side surface of the recess 36 serves as the discharge hole 64, so that even if the pressure sensor 210 is stored in the force detector storage case 60, the pressure introduction space The air remaining in 26 can be discharged efficiently. Further, the pressure introduction hole 22 shown in FIGS. 5 and 6 can be applied to this embodiment. Further, although the discharge hole 64 is not directly connected to the pressure introduction hole 22, as shown in FIG. 5, the side surface of the side wall 18 is symmetric with respect to the center of the bottom 16 in a plan view (radial). A plurality of recesses 36 can be formed between the side surfaces of the recess 36.

  In FIG. 11, it is sectional drawing which accommodated the force detector in the force detector accommodating case of 4th Embodiment. A pressure sensor 211a (force detector) that is an application target of the force detector housing case of the fourth embodiment is basically similar to the pressure sensor 210, but around the second outer peripheral portion 218, there is a male screw portion. 218a is formed. Correspondingly, in the force detector housing case 70 of the fourth embodiment, on the bottom 74 side of the inner wall of the side wall portion 76 of the first outer case 72, a female screw portion 78 that is screwed into the male screw portion 218a is formed. Has been. A male screw portion 80 is still formed outside the opening of the first outer case 72, and a female screw portion 84 is formed inside the opening of the second outer case 82. Therefore, in the fourth embodiment, a male screw portion 218a formed on the side surface of the container of the pressure sensor 211a and a female screw formed inside the side wall portion 76 of the first outer case 72 and screwed with the male screw portion 218a. The portion 78 serves as a fixing means for fixing the pressure sensor 211 a to the force detector housing case 70.

  The second outer peripheral portion 218 and the bottom portion 74 can be brought into contact with each other. In this case, the pressure introduction space 86 having the pressure introduction hole 22 is formed with the diaphragm 244A and the bottom portion 74 as a boundary. The male screw portion 218a and the female screw portion 78 are sufficiently airtight and the male screw portion 80 and the female screw portion 84 are sufficiently airtight, and the pressure introducing space 86 and the diaphragm 244B having the diaphragm 244A as a part of the boundary are provided. The internal space 88 as a part of the boundary is spatially separated.

  With such a configuration, the pressure environment where the diaphragm 244A is in contact with a simple configuration is separated from the other portions of the pressure sensor 211a, and the pressure introduction space 86 between the force detector housing case 70 and the pressure sensor 211a is separated. Can be measured. Furthermore, since the volume of the pressure introduction space 86 can be reduced, the air remaining in the pressure introduction space 86 (air remaining around the diaphragm 244A) can be easily discharged.

  Further, the fixing means (circular ring 46, circular ring 48, screw fitting 28, male screw part 218a, female screw part 78) of the present embodiment is the pressure introduction hole described in the first embodiment and the second embodiment. 22 and the discharge hole 24 can be applied. However, the pressure introducing hole 22 is formed at a position inside the peripheral edge of the diaphragm 244A in plan view, and the end of the horizontal hole 54 and the vertical hole 56 shown in FIG. 7 are positioned inside the peripheral edge of the diaphragm 244A in plan view. It is necessary to form the discharge hole 24 so that

  FIG. 12 is an exploded perspective view of the force detector housing case of the fifth embodiment, and FIG. 13 is a cross-sectional view of the force detector housing case of the fifth embodiment. The force detector housing case 90 of the fifth embodiment includes a first outer case 92, a second outer case 96, a push-in fitting 102, a circular ring 46 (FIG. 13), and a circular ring 48 (FIG. 13). The pressure sensor 211 of the embodiment (which may be the pressure sensor 210 of the first embodiment, etc.) is accommodated as a force detector.

  The first outer case 92 and the second outer case 96 form the outer shape of the force detector housing case 90, and have structures similar to the first outer case 12 and the second outer case 34 of the third embodiment, respectively. Have. That is, the first outer case 92 is similar to the first outer case 12 of the third embodiment in that the concave portion 14 (FIG. 12), the bottom portion 16, the side wall portion 18, the pressure introduction hole 22, the concave portion 62, and the discharge hole 64 (see FIG. 13). Similarly to the second outer case 34 of the third embodiment, the second outer case 96 has a recess 36 (FIG. 12) and an open hole 38, and the tube 42 (FIG. 13) is connected to the open hole 38. . On the other hand, unlike the first outer case 12, the first outer case 92 has a female screw portion 94 that is screwed into the second outer case 96 at a position that becomes the opening of the recess 14. Unlike the second outer case 34, the second outer case 96 has a male screw portion 98 that is screwed into the first outer case 92 at a position that becomes the opening of the recess 36.

  The push-in fitting 102 has a cylindrical shape. Further, the diameter of the outer periphery of the side surface 104 is designed to be smaller than the inner diameter of the recess 14 of the first outer case 92 and the recess 36 of the second outer case 96. An insertion hole 106 (FIG. 12) that penetrates the push-in fitting 102 concentrically from the Z-axis direction has an inner diameter that is larger than the outer periphery of the side wall portion 242 of the pressure sensor 211 and smaller than the outer diameter of the flange portion 223. . Therefore, the pressure sensor 211 can be inserted into the insertion hole 106 from the diaphragm 244A side of the pressure sensor 211, and the surface on the + Z-axis side of the flange portion 223 and the end surface 108 on the −Z-axis side of the push-in fitting 102 can contact each other. It becomes. Incidentally, as shown in FIG. 13, the side wall portion 242 of the pressure sensor 211 is inserted through the circular ring 46, and the −Z axis side of the circular ring 46 is in contact with the surface of the flange portion 223 on the + Z axis side. Therefore, the −Z-axis side end face 108 of the push-in fitting 102 abuts on the + Z-axis side of the circular ring 46, and the circular ring 46 is the + Z-axis side face of the flange portion 223 and the −Z-axis end face of the push-in fitting 102. 108. The circular ring 48 is inserted from the diaphragm 244A side of the pressure sensor 211, and is sandwiched between the −Z-axis side surface of the flange portion 223 and the + Z-axis side surface of the bottom portion 16.

  As shown in FIG. 13, the length A of the push-in fitting 102 in the Z-axis direction is such that the first outer case 92 and the second outer case 96 are screwed together while the pressure sensor 211, the circular ring 46, and the circular ring 48 are accommodated. The upper end portion 100 of the second outer case 96 is longer than the distance B between the surface on the −Z axis side of the upper end portion 100 of the second outer case 96 and the upper end of the circular ring 46 on the + Z axis side. It is designed to be shorter than the distance (C−D) obtained by subtracting the thickness D of the flange portion 223 in the Z-axis direction from the distance C between the −Z-axis side surface and the + Z-axis side surface of the bottom portion 16. Further, the end surface 110 on the + Z-axis side of the push-in fitting 102 abuts on the −Z-axis side surface of the upper end portion 100 of the second outer case 96.

  In the above configuration, as shown in FIG. 13, the first outer case 92 and the second outer case 96 are screwed together while the pressure sensor 211, the circular ring 46, the circular ring 48, and the push-in fitting 102 are accommodated. Then, the + Z-axis side end face 110 of the push-in fitting 102 and the −Z-axis side face of the upper end portion 100 of the second outer case 96 come into contact with each other, so that the push-in fitting 102 advances toward the circular ring 46. The pushing metal fitting 102 abuts against the circular ring 46, so that the pushing metal fitting 102 receives a drag force from the circular ring 46 side (the circular ring 46, the flange portion 223, the circular ring portion 48, and the bottom portion 16). To communicate. However, the push-in fitting 102 receives a reaction force resulting from this drag force from the upper end portion 100. Therefore, the pushing metal fitting 102 pushes the flange portion 223 together with the circular ring 46 and the circular ring 48 toward the bottom portion 16 side. The circular ring 48 is sandwiched between the bottom portion 16 and the flange portion 223 and is compressed and deformed in the Z-axis direction. The circular ring 46 is also sandwiched between the push-in fitting 102 and the flange portion 223 and is compressed and deformed in the Z-axis direction. Thereby, the pressure introduction space 26 having the pressure introduction hole 22 is formed with the diaphragm 244A, the circular ring 48, and the bottom portion 16 as boundaries, and the internal space 44 and the pressure environment on the second outer case 34 side are separated.

  In addition, by accommodating the force detector in the force detector housing case according to any embodiment, the air remaining in the pressure introduction space between the force detector housing case and the force detector can be efficiently discharged. A pressure measuring device capable of measuring an accurate liquid pressure can be constructed.

10 ......... Force detector housing case, 12 ......... First outer case, 14 ......... Recess, 16 ......... Bottom portion, 18 ......... Side wall portion, 20 ......... Female thread portion, 22 ......... Pressure introduction hole, 23... Net part, 24 ... Discharge hole, 26 ... Pressure introduction space, 28 ... Screw fitting, 28a ... Side wall, 30 Insertion hole, 32 Male thread part 34 ......... Second outer case 36 ......... Recessed part 38 ......... Open hole 40 ... Female thread part 42 ... Tube 44 ... Internal space 46 ... ... Circular ring, 48 ... ... Circular ring, 50 ... ... Force detector housing case, 52 ... ... Discharge hole, 54 ... ... Horizontal hole, 56 ... ... Vertical hole, 60 ... ... Force detector housing case, 62 ......... Recess, 64 ......... Discharge hole, 66 ......... Circular ring, 68 ......... Circular ring, 70 ......... Force detector housing case 72 ......... First outer case, 74 ......... Bottom part, 76 ......... Side wall part, 78 ......... Female thread part, 80 ......... Male thread part, 82 ......... Second outer case, 84 ... ... Female screw part, 86 ......... Pressure introduction space, 88 ... ... Internal space, 90 ... ... Force detector housing case, 92 ... ... First outer case, 94 ... ... Female screw part, 96 ... ... Second outer case, 98 ......... Male thread part, 100 ......... Upper end part, 102 ......... Push-in metal fitting, 104 ...... Side, 106 ......... Insertion hole, 108 ......... End face, 110 ... ...... End face 210... Pressure sensor 211... Pressure sensor 211 a ...... Pressure sensor 212 …… Housing 214 …… First end plate 216 …… First outer peripheral portion 218 ...... Second outer peripheral part, 218a ......... Male thread part, 220 ......... Opening part, 222 ......... F Flange portion, 224 ......... second end plate, 226 ......... concave portion, 228 ......... boss portion, 230 ......... insertion hole, 232 ......... hole, 234 ......... hole 236: Support shaft, 238 ... Hermetic terminal, 240: Wire, 242 ... Side wall, 244A, 244B ... Diaphragm, 246 ... Center, 248 ... Flexible , 250... Peripheral part, 252... Center shaft, 254... Fixing part, 256... Through hole, 258 ..... Pressure-sensitive element, 260. Base of 264 ......... Second base, 300 ......... Pressure sensor, 302 ......... Diaphragm, 304 ...... Element, 306 ......... Round ring, 308 ......... Outer case, 308a ......... Inside Space, 308b ……… Pressure introduction hole , 310... External case, 310 a... Internal space, 310 b ... Pressure introducing hole, 400 ... External case, 402 ... First external case, 402 a ... Recess, 402 b ... Pressure Introducing hole, 402c ......... Female threaded portion, 404 ......... Second outer case, 404a ......... Recessed portion, 404b ......... Open hole, 404c ......... Female threaded portion, 406 ......... Screw fitting, 406a ... ...... Insertion hole, 406b ......... Male thread portion, 408 ......... Round ring, 410 ......... Flange portion, 412 ......... Pressure introduction space, 414 ......... Internal space, 416 ......... Tube, 418 ... ...... Relay box.

Claims (10)

A container having a cylindrical outer shape, a male screw portion formed along the outer periphery of the side surface of the container, and a diaphragm that is disposed on an end surface of the container and receives a force to be displaced inside or outside the container. A force detector housing case for housing a force detector for detecting force by displacement of the diaphragm,
An outer case having a bottom portion facing the diaphragm and a side wall portion facing the side surface of the container;
A pressure introducing hole formed in the bottom;
A female screw part formed along the inner periphery of the side wall part, screwed into the male screw part, the diaphragm as a part of the boundary, and forming a pressure introducing space having the pressure introducing hole;
A force detector housing case, wherein a discharge hole penetrating between a side surface of the side wall portion and the pressure introducing space is provided. A container having a cylindrical outer shape, a flange portion that protrudes to the outer peripheral side of the side surface of the container and is concentric with the outer periphery of the side surface, and is disposed on the end surface of the container and receives the force to displace inside or outside the container. A force detector housing case for housing a force detector for detecting force by displacement of the diaphragm,
An outer case having a bottom portion facing the diaphragm and a side wall portion facing the side surface of the container;
A pressure introducing hole formed in the bottom;
A circular ring having a ring shape, disposed between the flange portion and the bottom portion, and disposed so that the pressure introducing hole is inside the ring;
A pressing member that presses the flange portion together with the circular ring to the bottom side, and that forms a pressure introducing space having the pressure introducing hole, with the diaphragm being a part of the boundary in the outer case;
A force detector housing case, wherein a discharge hole penetrating between a side surface of the side wall portion and the pressure introducing space is provided. The discharge hole is
3. The force detector housing case according to claim 1, wherein a plurality of the force detector housing cases are formed so as to be centrosymmetric with respect to a center of the bottom portion. The discharge hole is
By passing between the side surface of the side wall portion and the inner wall of the pressure introduction hole and joining the pressure introduction hole, the side wall portion penetrates between the side surface of the side wall portion and the pressure introduction space. The force detector housing case according to claim 1 or 2. The discharge hole is
The side wall part is dug up to a position that is different from the pressure introduction hole in the bottom part and opposite the pressure introduction space, and is bent and dug into the pressure introduction space side. The force detector housing case according to claim 1 or 2, wherein the pressure introduction space penetrates to the pressure introduction space. The pressure introducing hole is
6. The force detector housing case according to claim 1, wherein a plurality of the force detector housing cases are formed so as to be symmetrical with respect to a center of the bottom.   The force detector housing case according to claim 1, wherein the pressure introducing hole is covered with a mesh-like net part. A recess is formed at a position facing the end surface of the container at the bottom,
The discharge hole is
The force detector housing case according to any one of claims 2 to 7, wherein the case penetrates between a side surface of the side wall portion and a side surface of the concave portion.   The force detector housing case according to claim 8, wherein the concave portion has a shape following the outer periphery of the end surface of the container, and can accommodate the end surface side of the container.   The force detector is accommodated in the force detector housing case according to any one of claims 1 to 9.

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