Diaphragm-type pressure measuring chamber

Abstract

A diaphragm-type pressure measuring chamber (1) is provided with: a first case (11) which has a first connection part (60) provided to a periphery thereof; a second case (12) which has provided to a periphery thereof a second connection part (70) to be connected to the first connection part (60), and which has a chamber space (13) formed between the first case (11) and the second case; and a flexible dome-shaped diaphragm (15) which partitions the chamber space (13) into a first room (13a) on a blood side and a second room (13b) on a pressure sensor side. The diaphragm (15) has: a flexible film (40) that deforms in a first direction in accordance with the pressure difference between the first room (13a) and the second room (13b); and a support frame (50) that is provided on a periphery of the flexible film (40) and is fixed between the first connection part (60) and the second connection part (70). The support frame (50) has higher rigidity than the flexible film (40).

Description

Diaphragm-type pressure measurement chamber

[0001] The present invention relates to a diaphragm-type pressure measuring chamber for measuring the pressure of blood flowing through a blood circuit.

[0002] Blood purification therapy involves extracorporeally circulating a patient's blood and purifying it during circulation. Dialysis is one example of this type of treatment. In dialysis, blood drawn from the patient is introduced into a dialyzer, where unwanted components in the blood are replaced with useful components in a dialysate and also filtered. The treated blood is then returned to the patient. In dialysis, blood pressure is measured at various points in the blood circuit to prevent damage to useful blood cells and blood aggregation.

[0003] Pressure measurements at various points in a blood circuit are performed, for example, by measuring the air pressure in a drip chamber installed along the circuit. However, there are concerns that contact of blood with air in the drip chamber may lead to problems such as the formation of blood clots or the blood in the drip chamber coming into contact with a pressure sensor. To address this, a chamber device has been proposed in which a flexible diaphragm separates the blood chamber through which the blood flows from the air chamber connected to the pressure sensor (see Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2008-051663

[0005] The chamber of a blood circuit measures low pressures of -300 to 500 mmHg. Therefore, a highly flexible diaphragm is desirable to improve the accuracy of pressure measurement. However, a highly flexible diaphragm is easily deformed and difficult to maintain in a fixed shape, making it difficult to handle. In particular, a chamber device equipped with a dome-shaped diaphragm is assembled by clamping the peripheral edge of the diaphragm between upper and lower cases, but the unstable shape of the diaphragm makes assembly difficult. If the diaphragm becomes wrinkled or distorted during assembly, this could affect the accuracy of pressure measurement.

[0006] Therefore, an object of the present disclosure is to provide a diaphragm-type pressure measurement chamber that is easy to assemble and can be assembled appropriately.

[0007] A diaphragm-type pressure measurement chamber according to a first aspect of the present disclosure is a diaphragm-type pressure measurement chamber for measuring the pressure of blood in a blood circuit, comprising: a first case having a first connection portion provided on its periphery; a second case having a second connection portion connected to the first connection portion provided on its periphery and forming a chamber space between the first case and the second case; and a flexible dome-shaped diaphragm that divides the chamber space into a first chamber on the blood side and a second chamber on the pressure sensor side, wherein the first chamber is formed between the first case and the diaphragm and is connected to a blood flow path in the blood circuit, and the diaphragm has a flexible membrane that deforms in a first direction in response to a pressure difference between the first chamber and the second chamber, and a support frame that is provided on the periphery of the flexible membrane and fixed between the first connection portion and the second connection portion, and the support frame has higher rigidity than the flexible membrane.

[0008] This allows the membrane portion of the diaphragm to be easily deformed while the periphery is less susceptible to deformation, reducing the impact of deformation of the membrane portion on the periphery of the diaphragm. Therefore, a dome-shaped diaphragm with a highly rigid support frame is easy to handle, and even if the dome-shaped membrane portion is deformed during the assembly process, the periphery of the diaphragm maintains a stable shape, allowing it to be properly assembled by sandwiching it between the first case and the second case. This reduces the occurrence of wrinkles and distortions in the dome-shaped diaphragm.

[0009] In the pressure measurement chamber according to the second aspect of the present disclosure, in the first aspect, at least one of the first connection portion and the second connection portion may be provided with an insertion groove into which the support frame is inserted in the first direction.

[0010] As a result, when the diaphragm is fixed between the first case and the second case, the support frame is inserted into the insertion groove of the first case or the second case, so that the diaphragm can be easily positioned relative to the first case or the second case, and the stability of the positional accuracy is improved.

[0011] The pressure measurement chamber according to a third aspect of the present disclosure may be the second aspect, wherein the first connecting portion and the second connecting portion form an accommodation space for accommodating the support frame, and the flexible membrane may form a seal portion that is sandwiched and compressed by the first connecting portion and the second connecting portion. Note that compression may be achieved by sandwiching the surfaces together, but the seal portion can be formed efficiently by providing a compression protrusion on at least one of the first connecting portion and the second connecting portion.

[0012] In this case, the rigidity of the support frame can be increased compared to when the support frame is used as the sealing portion, and the stability of the peripheral edge of the diaphragm can be improved. Furthermore, when the support frame and the flexible membrane are formed by integral molding, stress caused by displacement of the flexible membrane is blocked by the portion of the sealing portion compressed by the first connecting portion and the second connecting portion, and is less likely to be transmitted to the fixed portion between the support frame and the flexible membrane, thereby preventing the fixed portion from peeling off from the support frame.

[0013] A pressure measurement chamber according to a fourth aspect of the present disclosure may be such that, in the third aspect, the first case is engaged with the second case, and the dimension of the storage space in the first direction is formed longer than the dimension of the support frame in the first direction, so that a gap is provided between the first connection portion or the second connection portion and the support frame within the storage space.

[0014] By forming a gap between the first connection part or the second connection part and the support frame in the housing space, it is possible to reduce the risk of the support frame affecting the fastening when fastening the first case to the second case, causing a fastening failure. Note that "fastening" includes physical fitting using unevenness, etc., and fastening using adhesive or integral molding.

[0015] In the pressure measurement chamber according to a fifth aspect of the present disclosure, in the second aspect, the support frame may have a protective portion located radially outward of the flexible membrane.

[0016] This prevents the flexible membrane from rubbing against the wall surface of the insertion groove when the peripheral edge of the diaphragm is inserted into the insertion groove, making it easier to insert the flexible membrane into the insertion groove in an appropriate state.

[0017] A pressure measurement chamber according to a sixth aspect of the present disclosure may be the fifth aspect, wherein the flexible membrane has an embedded portion embedded inside the support frame so that the inner and outer surfaces in the second direction are fixed to the support frame.

[0018] This allows the fixing surface to be enlarged, enabling the support frame to hold the flexible membrane more stably. Also, the exposed area of ​​the flexible membrane at the periphery of the diaphragm can be reduced, reducing the risk of unintended external forces being applied to the flexible membrane.

[0019] A pressure measurement chamber according to a seventh aspect of the present disclosure is the sixth aspect, wherein the protective portion has an extension portion that extends beyond the outer surface of the embedded portion of the flexible membrane in the first direction.

[0020] This prevents the outer edge of the flexible membrane from coming into contact with the bottom or top surfaces of the first connection portion and the second connection portion, thereby reducing the possibility of unintended stress being applied to the outer edge of the flexible membrane during assembly.

[0021] A diaphragm-type pressure measurement chamber according to an eighth aspect of the present disclosure is a diaphragm-type pressure measurement chamber for measuring the pressure of blood in a blood circuit, comprising: a first case having a first connection portion provided on its periphery; a second case having a second connection portion connected to the first connection portion provided on its periphery and forming a chamber space between the first case and the second case; and a flexible diaphragm that divides the chamber space into a first chamber on the blood side and a second chamber on the pressure sensor side, wherein the first chamber is formed between the first case and the diaphragm and is connected to a blood flow path in the blood circuit, and the diaphragm has a surface area larger than the cross-sectional area of ​​the chamber space and has a three-dimensional shape with at least a portion convex in a first direction, and comprises a flexible membrane that deforms in a first direction in response to a pressure difference between the first chamber and the second chamber, and a support frame provided on the periphery of the flexible membrane and fixed between the first connection portion and the second connection portion, wherein the support frame is more rigid than the flexible membrane.

[0022] This makes it easy to handle the diaphragm with its highly rigid support frame, and it can be assembled in the appropriate position by sandwiching it between the first and second cases, which reduces the occurrence of wrinkles and distortions that are unique to three-dimensional diaphragms.

[0023] According to the present disclosure, it is possible to provide a diaphragm-type pressure measurement chamber that is easy to assemble and can be assembled appropriately.

[0024] FIG. 1 is a perspective view showing the configuration of a diaphragm-type pressure measurement chamber according to embodiment 1. FIG. 2 is a longitudinal cross-sectional view of the pressure measurement chamber according to embodiment 1. FIG. 3A is an external perspective view of a diaphragm, and FIG. 3B is a cross-sectional view of the diaphragm. FIG. 4A is an enlarged cross-sectional view of a portion of the diaphragm surrounded by imaginary circle IVA in FIG. 3B, and FIG. 4B is an enlarged cross-sectional view of a portion of the pressure measurement chamber surrounded by imaginary circle IVB in FIG. 2. FIG. 5 is a perspective view showing the configuration of a diaphragm-type pressure measurement chamber according to embodiment 2. FIG. 6 is a longitudinal cross-sectional view of the pressure measurement chamber according to embodiment 2. FIG. 7 is a cross-sectional view of the diaphragm. FIG. 8A is an enlarged cross-sectional view of a portion of the diaphragm surrounded by imaginary circle VIIIA in FIG. 7, and FIG. 8B is an enlarged cross-sectional view of a portion of the pressure measurement chamber surrounded by imaginary circle VIIIB in FIG. 6. FIG. 9 is a cross-sectional view of a diaphragm according to modification 1. FIG. 10A is an enlarged cross-sectional view of a portion of a diaphragm according to Modification 1, and FIG. 10B is an enlarged cross-sectional view of a portion of a pressure measurement chamber to which the diaphragm according to Modification 1 is assembled. FIG. 11 is an enlarged cross-sectional view of a portion of a pressure measurement chamber to which the diaphragm according to Modification 2 is assembled. FIG. 12 is an enlarged cross-sectional view of a portion of a pressure measurement chamber to which the diaphragm according to Modification 3 is assembled. FIG. 13 is a cross-sectional view of a diaphragm according to Modification 4. FIG. 14A is an enlarged cross-sectional view of a portion of a diaphragm according to Modification 4, and FIG. 14B is an enlarged cross-sectional view of a portion of a pressure measurement chamber to which the diaphragm according to Modification 4 is assembled. FIG. 15A is an external plan view showing the configuration of the pressure measurement chamber, FIG. 15B is a cross-sectional view taken along line B-B of FIG. 15A, and FIG. 15C is an enlarged view of a portion of the cross-sectional view of FIG. 15B. Fig. 16A is a perspective view of a diaphragm according to embodiment 3, Fig. 16B is a cross-sectional view of the diaphragm of Fig. 16A taken along line B-B, and Fig. 16C is an enlarged view of a portion of the cross-sectional view of Fig. 16B. Fig. 17 is a schematic diagram showing an example of a molding process for a diaphragm. Figs. 18A to 18D are all external perspective views showing different modified examples of the flexible membrane.

[0025] A diaphragm-type pressure measurement chamber according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the concepts of directions used in the following description are used for convenience of explanation and do not limit the orientation of each disclosed configuration to those directions. Furthermore, the pressure measurement chamber described below is merely one embodiment of the present disclosure. Therefore, the present disclosure is not limited to the following embodiment, and additions, deletions, or modifications to the configuration are possible within the scope of the disclosure.

[0026] (Embodiment 1) A pressure measurement chamber 1 according to the present disclosure constitutes part of a blood circuit provided in a dialysis system and measures the pressure of a patient's blood flowing through a blood flow path provided in the blood circuit. The blood circuit includes, for example, a blood removal line, which is a blood flow path that leads the patient's blood out of the body, a filter connected to the blood removal line that transfers specific components from the patient's blood to a dialysate to purify the blood, and a blood return line, which is a blood flow path that returns the purified blood to the patient. In addition, a blood pump is provided midway along the blood removal line to circulate blood through the blood circuit.

[0027] The dialysis system includes a blood circuit and a pressure measurement device. The pressure measurement device includes multiple pressure sensors, each connected to a different point (pressure measurement point) in the blood circuit via a pressure monitor line. The pressure measurement chamber 1 according to the present disclosure is provided between the pressure monitor line and the pressure measurement point in the blood circuit.

[0028] The pressure measurement chamber 1 may be provided midway along a line through which blood flows in the blood circuit so as to constitute a part of that line. Alternatively, the pressure measurement chamber 1 may be provided so as to be connected to another line that branches off from the line through which blood flows in the blood circuit via a drip chamber or the like. In the former case, blood flows into the interior of the pressure measurement chamber 1 (first chamber 13a described below). In the latter case, blood does not generally flow into the interior of the pressure measurement chamber 1, and air in contact with the blood on the blood circuit flows into the interior of the pressure measurement chamber 1.

[0029] [Pressure Measurement Chamber] The configuration of the pressure measurement chamber 1 will be described in detail below. Fig. 1 is a perspective view showing the configuration of the diaphragm-type pressure measurement chamber 1 according to the first embodiment. Fig. 2 is a vertical cross-sectional view of the pressure measurement chamber 1.

[0030] The pressure measurement chamber 1 has a housing 14 in which a first case 11 and a second case 12, both made of resin, are joined together to form a chamber space 13. A flexible diaphragm 15 is provided within the housing 14, and the diaphragm 15 divides the chamber space 13 into a first chamber 13a on the first case 11 side and a second chamber 13b on the second case 12 side. That is, the first chamber 13a and the second chamber 13b are both in contact with the diaphragm 15 and are separated from each other in an airtight and liquid-tight manner by the diaphragm 15. A first port P1 and a second port P2 are formed in the first case 11, and a third port P3 is formed in the second case 12.

[0031] The pressure measurement chamber 1 has a generally circular dome-like outer shape, and its orientation during use is not particularly limited. However, for the sake of convenience, the directions related to the pressure measurement chamber 1 will be defined as follows: the direction in which the second case 12 is located relative to the first case 11 is referred to as "upward," and the opposite direction is referred to as "downward." The direction in which the second port P2 is located relative to the first port P1 is referred to as "forward," and the opposite direction is referred to as "rearward." Furthermore, a direction intersecting both the up-down direction and the front-to-rear direction is referred to as the "left-right direction" when facing forward.

[0032] In addition, in this embodiment, as shown in Fig. 1, a pressure measurement chamber 1 is described as being circular in plan view (when viewed from above) and dome-shaped, bulging upward in an arc-like shape in side view, but the configuration of the pressure measurement chamber 1 is not limited to this. For example, the pressure measurement chamber may be oval in plan view and bulging upward in an arc-like shape in side view. Other shapes are also possible. Furthermore, the attachment positions of the various ports relative to the housing are not particularly limited.

[0033] [First Case] ​​The first case 11 includes a case body 20, to which a first port P1 and a second port P2 are connected. The case body 20 has an opening 21 that opens upward and an inner surface 22 that is recessed downward. The inner surface 22 and the lower surface of the diaphragm 15 form a first chamber (blood side space) 13a, which is the lower space of the chamber space 13. That is, the first chamber 13a is a space formed between the first case 11 and the diaphragm 15 and is a space that communicates with the blood flow path in the blood circuit. The shape of the chamber space 13 when viewed in a plan view along the vertical direction (i.e., the shape of the opening 21) is approximately circular. However, the shape of the chamber space 13 is not limited to this. For example, the shape when viewed in a plan view may be elliptical or other shapes. The shape of the chamber space 13 when viewed in the front-to-back or left-to-right directions is also not particularly limited. For example, a circular shape, an elliptical shape, a rectangular shape, or other shapes may be used as appropriate.

[0034] A first circumferential portion 23 is formed in the opening 21 of the case body 20, expanding in the radial direction from the upper end portion of the inner surface 22 and surrounding the opening 21. The first circumferential portion 23 sandwiches and fixes the diaphragm 15 between itself and a second circumferential portion 33 of the second case 12 (described in detail below).

[0035] A first port P1 is integrally formed at the rear of the case body 20. The first port P1 is tubular, and its internal flow path is connected to the first chamber 13a within the case body 20. A second port P2 is integrally formed at the front of the case body 20. The second port P2 is tubular, and its internal flow path is also connected to the first chamber 13a. The flow paths of the first port P1 and the second port P2 are coaxial with each other and arranged with their centerlines facing the front-to-rear direction. The first port P1 and the second port P2 are connected to the blood flow path of the blood circuit described above. Blood flowing from the upstream side of the blood flow path flows into the first chamber 13a via the first port P1 and then flows out to the downstream side of the blood flow path via the second port P2.

[0036] A groove 25 extending in the front-to-rear direction and recessed from the inner surface 22 is formed in the bottom of the inner surface 22 of the case body 20. This groove 25 extends from the connection point of the first port P1 to the connection point of the second port P2 with the case body 20. Therefore, a space 25a forming a part of the rear side of the groove 25 is interposed between the inner surface 22 and an opening 26a of the first port P1 on the side communicating with the first chamber 13a. In other words, the opening 26a of the first port P1 is recessed from the inner surface 22 of the case body 20 by the amount of the space 25a. Similarly, a space 25b formed by the groove 25 is interposed between the inner surface 22 and an opening 26b of the front second port P2 on the side communicating with the first chamber 13a.

[0037] Due to this groove 25, even if the internal pressure of the first chamber 13a drops and the diaphragm 15 (described later) bends significantly downward, the opening 26a of the first port P1 will not be blocked by the diaphragm 15. The pressure transmitted to the inside of the case body 20 through the first port P1 acts on a wide area of ​​the underside of the diaphragm 15 via spaces such as spaces 25a and 25b formed by the groove 25 (spaces connecting the ports P1 and P2 with the first chamber 13a). Therefore, the pressure measurement chamber 1 allows accurate pressure measurement even in such a situation.

[0038] Note that the configuration that achieves the above-described effects is not limited to the groove 25. For example, instead of or in addition to the groove 25, a protruding rib extending in the front-to-rear direction may be formed on the inner surface 22. Alternatively, instead of or in addition to the groove 25, a plurality of protrusions may be formed on the inner surface 22. That is, it is sufficient to reduce the contact area between the diaphragm 15 and the inner surface 22 of the case body 20 (particularly the area around the opening 26a), and to provide a recess or protrusion on the inner surface 22 to form a space that communicates between the first chamber 13a and the first port P1.

[0039] [Second Case] ​​The second case 12 includes a case body 30, and the third port P3 is connected to the case body 30. The case body 30 is generally dome-shaped and bulges upward, has an opening 31 that opens downward, and an inner surface 32 that is recessed upward. The inner surface 32 and the upper surface of the diaphragm 15 form a second chamber (sensor-side space) 13b, which is the upper space of the chamber space 13.

[0040] A second winding portion 33 is formed in the opening 31 of the case body 30, expanding in the radial direction from the lower end portion of the inner surface 32 and surrounding the opening 31. The second winding portion 33 sandwiches the diaphragm 15 between itself and the first winding portion 23 of the first case 11 (details will be described later).

[0041] A third port P3 is integrally formed in the front portion of the case body 30. A pressure monitor line extending from the pressure measuring device described above is connected to this third port P3. The third port P3 is tubular and extends upward from the outer surface of the case body 30 with its centerline oriented in the vertical direction. The internal passage of the third port P3 communicates with the second chamber 13b inside the case body 30 at an opening 36a at its lower end. Furthermore, a plurality of linear ribs, for example, are formed on the inner surface 32 of the case body 30 to form an air flow path between the inner surface 32 and the diaphragm 15.

[0042] [Diaphragm] The diaphragm 15 includes a flexible membrane 40 that deforms in a first direction in response to the pressure difference between the first chamber 13a and the second chamber 13b, and a support frame 50 that is provided around the flexible membrane 40 and fixed between a first connection portion 60 and a second connection portion 70 (described later). The flexible membrane 40 has a surface area larger than the cross-sectional area of ​​the chamber space 13 and a three-dimensional shape with at least a portion convex in the first direction. The support frame 50 is more rigid than the flexible membrane 40. This allows for ease of handling during assembly. This will be explained in more detail below.

[0043] The diaphragm 15 is a dome-shaped membrane with moderate flexibility that deforms in a vertical direction (first direction) toward either the first chamber 13a or the second chamber 13b in response to the differential pressure between the first chamber 13a and the second chamber 13b (the difference in internal pressure). That is, the direction of deformation of the diaphragm 15 (vertical direction) due to changes in the differential pressure between the first chamber 13a and the second chamber 13b intersects with the direction of fluid flow (front-to-back direction) through the first chamber port P1. The diaphragm 15 includes a flexible membrane 40 and an annular support frame 50 attached to the periphery of the flexible membrane 40. The flexible membrane 40 also includes a dome-shaped membrane portion 41 and an annular flange portion 42 extending outward from the periphery of the membrane portion 41. The support frame 50 is connected to the flange portion 42.

[0044] Although the present embodiment illustrates a hemispherical dome-shaped diaphragm 15, the shape is not limited to this. That is, the dome-shaped diaphragm referred to in the present disclosure may have a rectangular cross section or a shape resembling one side of a doughnut cut horizontally (i.e., a shape resembling one side of a doughnut cut horizontally along a plane perpendicular to the centerline passing through the center hole). The shape of the diaphragm 15 is not limited to a dome, and other shapes may also be used. For example, a spherically wavy flexible membrane with concentric waves in a plan view may be used. The diaphragm 15 may have a ratio H / W of the height dimension H of the membrane portion 41 to the width dimension W of 0.1 or more and 0.6 or less, and more preferably, a ratio H / W of 0.2 or more and 0.5 or less. This allows the amount of displacement of the membrane portion 41 in response to pressure changes to be increased without excessively increasing the height dimension, thereby improving the pressure detection accuracy. With regard to the dimensions W and H, when the membrane portion 41 is convex toward the second chamber 13b, the maximum opening diameter on the first chamber 13a side is the width dimension W, and the maximum height on the first chamber 13a side is the height dimension H. This is the same for the other embodiments and modified examples.

[0045] [Method of Assembling the Pressure Measurement Chamber] The housing 14, which is made up of the first case 11 and second case 12 as described above, and the diaphragm 15 are combined to form the pressure measurement chamber 1. That is, first, the diaphragm 15, which is recessed downward (opens upward), is assembled from above into the first case 11, which has the opening 21 facing upward. At this time, the flange portion 42 of the diaphragm 15 and the underside of the support frame 50 are positioned opposite the first circumferential portion 23 of the first case 11. The first circumferential portion 23 and the support frame 50 are then connected (for example, by adhesive or ultrasonic welding).

[0046] Next, the second case 12 is assembled from above to the first case 11 in this state, with the opening 31 facing downward. At this time, the second circumferential portion 33 of the second case 12 is disposed opposite the flange portion 42 of the diaphragm 15 and the support frame 50. The second circumferential portion 33 and the support frame 50 are then connected (for example, by adhesive bonding or ultrasonic welding).

[0047] In this way, the first case 11 and the second case 12 are bonded or welded to each other at their peripheral portions with the support frame 50 sandwiched therebetween, and the diaphragm 15 is supported between the first case 11 and the second case 12. As a result, a chamber space 13 is formed inside the housing 14, and the chamber space 13 is partitioned by the diaphragm 15 into a first chamber 13a communicating with the first port P1 and the second port P2, and a second chamber 13b communicating with the third port P3.

[0048] The above-described connection methods between the various parts are merely examples and are not intended to be limiting. For example, the connection method between the first winding part 23 and the support frame 50 and the connection method between the second winding part 33 and the support frame 50 are not limited to adhesive or welding, and may be a connection by physical engagement, such as by engaging recesses and protrusions. Alternatively, a gap may be provided to prevent connection (non-engagement). Furthermore, the connection between the first case 11 and the second case 12 is not limited to adhesive or welding, and may be a connection by physical engagement, such as by engaging recesses and protrusions.

[0049] As described above, the pressure measurement chamber 1 can be provided in the blood circuit (blood flow path). In this case, the first port P1 serves as the blood inlet, the second port P2 serves as the blood outlet, and blood flows through the first chamber 13a. The pressure measurement chamber 1 can also be connected to another line (blood flow path) branching off from the blood circuit via a drip chamber. In this case, the first port P1 serves as a connection port to the downstream end of the other line, the second port P2 is closed, and the first chamber 13a communicates with the space occupied by air in contact with the blood in the drip chamber. In either embodiment, the third port P3 is connected to one end of a pressure monitor line, and the other end of the pressure monitor line is connected to a pressure sensor of a pressure measurement device. Therefore, the pressure measurement device measures the pressure in the second chamber 13b via the third port P3. In this way, the first chamber 13a forms a space on the blood side, and the second chamber 13b forms a space on the sensor side.

[0050] [Structure Related to Ease of Assembly] The more flexible the diaphragm 15, the better its responsiveness to the pressure (blood pressure) in the first chamber 13a, improving the accuracy of pressure measurement. On the other hand, the more flexible the material selected for the diaphragm 15, the lower its shape stability (standardization), making assembly less easy. Therefore, the pressure measurement chamber 1 according to the present disclosure has the diaphragm 15 configured from a flexible membrane 40 made of a highly flexible material and a support frame 50 made of a material with higher rigidity than the flexible membrane 40, thereby improving ease of assembly. The following describes such a structure related to ease of assembly.

[0051] Fig. 3A is an external perspective view of the diaphragm 15, and Fig. 3B is a cross-sectional view of the diaphragm 15. Fig. 4A is an enlarged cross-sectional view of a portion of the diaphragm 15 surrounded by an imaginary circle IVA in Fig. 3B, and Fig. 4B is an enlarged cross-sectional view of a portion of the pressure measurement chamber 1 surrounded by an imaginary circle IVB in Fig. 2.

[0052] As shown in Figures 3A and 3B, the diaphragm 15 includes a flexible membrane 40 and a support frame 50, and is generally dome-shaped and rotationally symmetrical with respect to a predetermined imaginary line L extending in the up-down direction. This imaginary line L is a line passing through the center of the dome-shaped membrane portion 41. The "up-down direction" used in the following explanations with reference to Figures 3A, 3B, 4A, and 4B is the same as the "up-down direction" used in the explanations of Figures 1 and 2. However, because the diaphragm 15 is rotationally symmetrical with respect to the imaginary line L as described above, the direction approaching the imaginary line L is also referred to as the "inward" or "inside," and the direction away from the imaginary line L is also referred to as the "outward" or "outside." Furthermore, the direction perpendicular to the up-down direction is referred to as the "horizontal direction," and this horizontal direction also coincides with the inward-outward direction.

[0053] As shown in Figures 3A and 3B, the flexible membrane 40 of the diaphragm 15 has a dome-shaped membrane portion 41 that deforms vertically in response to the pressure difference between the first chamber 13a and the second chamber 13b. The membrane portion 41 has a dome-shaped main body portion 41a with a predetermined thickness and a thin-walled portion 41b that extends upward from the peripheral edge of the open end of the main body portion 41a and is thinner than the main body portion 41a. The thin-walled portion 41b is strip-shaped with a predetermined width and forms a ring shape that wraps around the open end of the main body portion 41a. One widthwise end of the thin-walled portion 41b (the lower end in Figure 3B) is connected to the main body portion 41a, and the other widthwise end (the upper end in Figure 3B) is connected to a flange portion 42. The thickness of the main body portion 41a of the membrane portion 41 can be set appropriately within a range of, for example, 0.2 mm to 1.5 mm. Furthermore, since the thin portion 41b is formed to be even thinner than the main portion 41a, the membrane portion 41 consisting of the main portion 41a and the thin portion 41b is configured to be less likely to elastically return to its original shape when deformed, i.e., it is configured to be more likely to maintain its shape after deformation, as will be described in other embodiments and modified examples below.

[0054] The surface area of ​​the diaphragm 15 is larger than the cross-sectional area of ​​the chamber space 13. For example, the cross-sectional area of ​​the chamber space 13 when cut at the mating surface between the first case 11 and the second case 12 is substantially the same as the area of ​​the opening 21 of the first case 11. On the other hand, the membrane portion 41 of the diaphragm 15 closes all of the openings of the first case 11 and is dome-shaped as described above, so the surface area of ​​the membrane portion 41 is larger than the area of ​​the opening 21 of the first case 11 and therefore larger than the cross-sectional area of ​​the chamber space 13.

[0055] As shown in FIG. 4A , the flange portion 42 has a first portion (seal portion) 43 extending outward from the other end of the thin-walled portion 41 b. The first portion 43 is a substantially horizontal plate-like member that wraps around the thin-walled portion 41 b to form a ring shape. The upper end of a second portion 44 extending vertically is connected to the outer end of the first portion 43. This second portion 44 also wraps around the first portion 43 to form a ring shape. A third portion 45 extending outward is connected to the lower end of the second portion 44. This third portion 45 also wraps around the second portion 44 to form a ring shape. As shown in FIG. 4A , the first portion 43, second portion 44, and third portion 45 all have a crank-shaped cross section.

[0056] An enlarged portion 46 is provided at the outer end of the third portion 45. As an example, the cross section of this enlarged portion 46 has a vertically long rectangular shape with a vertical dimension greater than a horizontal dimension, and the vertical dimension of the enlarged portion 46 is greater than that of the third portion 45. In other words, the enlarged portion 46 is configured to extend upward and downward from the outer end of the third portion 45, and the configuration in which the third portion and the enlarged portion 46 are connected forms a shape similar to a T tilted at 90 degrees.

[0057] Meanwhile, the support frame 50 is annular, and its cross section is a vertically elongated rectangle whose vertical width is greater than its horizontal thickness. More specifically, the support frame 50 has a cross-sectional shape whose vertical dimension is greater than that of the expanded portion 46, and whose horizontal dimension is also greater than that of the expanded portion 46. A portion of the outer side of the third portion 45 and the expanded portion 46 are embedded inside the support frame 50. The vertical dimension of the support frame 50 is smaller than the overall height of the dome-shaped membrane portion 41 of the flexible membrane 40 (the same applies to support frames 50A to 50D described below).

[0058] That is, the support frame 50 has a first space 51 that opens to its inner peripheral surface, and a second space 52 that is provided on the rear side (outside) of the first space 51. The second space 52 has a larger vertical dimension than the first space 51, and when the first space 51 and the second space 52 are combined, their cross-sectional shape forms a T-shape tilted at 90 degrees. The outer portion of the third portion 45 is embedded in the first space 51, and the expanded portion 46 is embedded in the second space 52.

[0059] With this configuration, the flexible membrane 40 and the support frame 50 are in contact with each other in the horizontal direction (inward and outward directions) at some parts, preventing the flexible membrane 40 from slipping out of the support frame 50. Specifically, as shown in Fig. 4A , the wall surface of the support frame 50 that defines the second space 52 has locking surfaces 53 facing outward. These locking surfaces 53 are provided in two locations, one above and one below the first space 51. Meanwhile, the enlarged portion 46 located on the periphery of the flexible membrane 40 has locking surfaces 47 facing inward. These locking surfaces 47 are provided in two locations, one above and one below the third portion 45.

[0060] The engaging surface 53 and the engaged surface 47 face each other horizontally and are in contact with each other. Therefore, even if the flexible membrane 40 is deformed by a pressure difference during pressure measurement and the flange portion 42 is pulled inward, the engaged surface 47 of the flexible membrane 40 is engaged with the engaging surface 53 of the support frame 50, preventing the flexible membrane 40 from detaching from the support frame 50.

[0061] The flexible membrane 40 of the diaphragm 15 as described above is formed of a highly flexible material. Examples of suitable materials include synthetic rubbers such as isoprene rubber or silicone rubber, natural rubber, soft polyvinyl chloride, and thermoplastic elastomers. Furthermore, in terms of physical properties, materials suitable for the flexible membrane 40 include those with a Shore A hardness of 10 or more and less than 80, and more preferably 20 or more and 60 or less. Meanwhile, the support frame 50 of the diaphragm 15 is formed of a material with higher rigidity than the flexible membrane 40. Examples of suitable materials include polyethylene, polycarbonate, polypropylene, hard polyvinyl chloride, and polyester. In addition to these hard resins, metals and ceramics can also be used. Similarly, in terms of physical properties, materials suitable for the support frame 50 include those with a Shore A hardness of 80 or more, and more preferably 90 or more.

[0062] Furthermore, as described above, the diaphragm 15 in which the flexible film 40 and the support frame 50 are made of different materials can be molded in a state in which they are engaged with each other by two-color molding or insert molding. For example, if the flexible film 40 and the support frame 50 are both made of resin, either two-color molding or insert molding may be used, and if the support frame 50 is made of metal or ceramics, insert molding is preferably selected.

[0063] As shown in Figure 4B, in order to clamp the diaphragm 15 as described above, a first connecting portion 60 is provided on the first circumferential portion 23 of the first case 11, and a second connecting portion 70 is provided on the second circumferential portion 33 of the second case 12.

[0064] The first connection part 60 has a first part 61 located at the open end of the case body 20, and this first part 61 has a first surface 61a facing upward. This first surface 61a forms a horizontal plane perpendicular to the up-down direction. A second part 62 recessed downward is provided on the outside of the first part 61, and a first insertion groove 63 recessed further downward is provided on the outside of the second part 62. In addition, an outer peripheral wall 64 extending upward is provided on the outside of the first insertion groove 63.

[0065] The second connection portion 70 has a first portion 71 extending outward from the open end of the case body 30. This first portion 71 has a first surface 71a that faces downward and forms a horizontal plane perpendicular to the up-down direction. The first surface 71a has a larger horizontal dimension than the first surface 61a of the first case 11. Specifically, the inner end of the first surface 61a and the inner end of the first surface 71a are located at approximately the same position, but the outer end of the first surface 71a is located outward from the outer end of the first surface 61a.

[0066] Additionally, a second portion 72 that protrudes downward is provided on the outside of the first portion 71. This second portion 72 faces the outer portion of the second portion 62 of the first case 11 and is located above it. A second insertion groove 73 that is recessed upward is provided on the outside of the second portion 72. This second insertion groove 73 faces the first insertion groove 63 of the first case 11 and is located above it. Furthermore, an outer peripheral wall 74 that extends downward is provided on the outside of the second insertion groove 73. This outer peripheral wall 74 faces the outer peripheral wall 64 of the first case 11 and is located above it.

[0067] A crank-shaped space is formed between the first portion 61 and the second portion 62 of the first connecting portion 60 and the first portion 71 and the second connecting portion 72 of the second connecting portion 70. The crank-shaped portions of the flange portion 42 of the flexible membrane 40, namely, the first portion 43, the second portion 44, and the third portion 45, are sandwiched in this crank-shaped space.

[0068] That is, the first portion (seal portion) 43 of the flexible membrane 40 is sandwiched and compressed between the first portion 61 of the first connecting portion 60 and the inner portion of the first portion 71 of the second connecting portion 70. Furthermore, the second portion 44 of the flexible membrane 40 is sandwiched between the inner portion of the second portion 62 of the first connecting portion 60 and the outer portion of the first portion 71 of the second connecting portion 70. Furthermore, the third portion 45 of the flexible membrane 40 is sandwiched between the outer portion of the second portion 62 of the first connecting portion 60 and the second portion 72 of the second connecting portion 70.

[0069] This improves the positioning accuracy of the diaphragm 15 relative to the first case 11 and the second case 12. Furthermore, the first portion 71 of the second connecting portion 70 is provided with a rib 71b that protrudes downward from the first surface 71a toward the first surface 61a of the first connecting portion 60. Therefore, this rib 71b bites into the upper surface of the first portion 43 of the flexible membrane 40, ensuring sealing performance.

[0070] The first insertion groove 63 of the first connecting portion 60 and the second insertion groove 73 of the second connecting portion 70 are positioned vertically opposite each other, forming a vertically elongated space. The support frame 50 is sandwiched in this vertically elongated space. That is, the support frame 50 fits downward into the first insertion groove 63 and upward into the second insertion groove 73. The first case 11 and the diaphragm 15 are connected to each other by ultrasonic welding or the like between the bottom surface of the first insertion groove 63 and the lower surface of the support frame 50. The second case 12 and the diaphragm 15 are connected to each other by ultrasonic welding or the like between the bottom surface (ceiling surface) of the second insertion groove 73 and the upper surface of the support frame 50.

[0071] 4B , an upwardly protruding rib 63a is provided on the bottom surface of the first insertion groove 63, and the rib 63a is pressed against the support frame 50 when the first case 11 and the diaphragm 15 are connected. Similarly, a downwardly protruding rib 73a is provided on the bottom surface (ceiling surface) of the second insertion groove 73, and the rib 73a is pressed against the support frame 50 when the second case 12 and the diaphragm 15 are connected. This ensures sealing at the connection between the first case 11 and the diaphragm 15 and the connection between the second case 12 and the diaphragm 15. Note that ultrasonic welding may be used between the bottom surface of the first insertion groove 63 and the lower surface of the support frame 50 and / or between the bottom surface (ceiling surface) of the second insertion groove 73 and the upper surface of the support frame 50. In this case, the ribs 63a and 73a form protrusions for welding and are melted by ultrasonic welding to form a welding surface (in this case, the triangular configuration of the ribs 63a and 73a in FIG. 4B disappears after welding).

[0072] Furthermore, a tapered surface 74a is formed at the opening edge of the second insertion groove 73 of the second case 12, that is, in the example of FIG. 4B , at the connection point between the lower surface and inner surface of the outer peripheral wall 74 that defines the second insertion groove 73. This tapered surface 74a is an inclined surface that slopes outward as it extends downward, and the opening area of ​​the second insertion groove 73 increases as it extends downward. Therefore, the support frame 50 can be easily inserted into the second insertion groove 73.

[0073] When assembling the pressure measurement chamber 1 having the above-described configuration, first, the lower part of the support frame 50 of the diaphragm 15 is fitted into the first insertion groove 63 of the first case 11. At this time, the first part 43 of the flexible film 40 of the diaphragm 15 is placed on the first surface 61a, which is the upper surface of the first part 61 of the first case 11. Next, the second case 12 is placed over the pressure measurement chamber 1. At this time, the upper part of the support frame 50 is fitted into the second insertion groove 73 of the second case 12, and as described above, the tapered surface 74a makes fitting easy even when visibility during work is poor.

[0074] In this way, the diaphragm 15 is positioned relative to the first case 11 and the second case 12 by the highly rigid support frame 50. Therefore, high positioning accuracy of the diaphragm 15 relative to the first case 11 and the second case 12 can be ensured. That is, the pressure measurement chamber 1 formed by the first case 11, the second case 12, and the flexible membrane 40 monitors blood pressure by measuring the pressure in the second chamber 13b. In this case, it is preferable that the flexible membrane 40 has a small reaction force associated with deformation and is easily deformed, because the pressure in the first chamber 13a directly becomes the pressure in the second chamber 13b.

[0075] Therefore, it is preferable that the membrane portion 41 of the flexible membrane 40, which deforms in response to pressure, has a surface area larger than the cross-sectional area of ​​the chamber, is formed so that it does not undergo elastic deformation upon deformation and maintains its shape after deformation (it does not return to its pre-deformation shape due to elasticity), and is also thin so that it can deform easily with little pressure. However, the more the reaction force associated with the deformation of the membrane portion 41 of the flexible membrane 40 is reduced and deformation is made easier, the more likely the membrane portion 41 of the flexible membrane 40 itself is to deform due to minute vibrations. As a result, if the diaphragm 15 does not have a highly rigid support frame 50, if a portion of the dome-shaped membrane portion 41 deforms during the process of assembling the flexible membrane 40 to the first case 11 or the second case 12, the deformation will affect the periphery of the flexible membrane 40, causing the flexible membrane 40 to shift from its intended position relative to the first case 11 or the second case 12.

[0076] If a large positional deviation occurs, stress acts unevenly on the flexible membrane 40, causing excessive tension on the dome-shaped membrane portion 41, resulting in wrinkles and distortion. The wrinkles and distortion that occur when the flexible membrane 40 is fixed to the first case 11 and the second case 12 are not eliminated even when the dome-shaped membrane portion 41 deforms in response to pressure, and may affect the deformation performance of the membrane portion 41, such as by generating an unintended reaction force or difficulty in deformation when the membrane portion 41 deforms, and may affect the accuracy of pressure measurement.

[0077] However, as described above, the diaphragm 15 according to this embodiment is provided with a support frame 50 on its periphery that is more rigid than the flexible membrane 40. Therefore, the periphery of the diaphragm 15 disposed within the housing space 98 formed by the first case 11 and the second case 12 is not affected by deformation of the membrane portion 41, has a stable shape, and is less likely to shift position relative to the first case 11 and the second case 12. This makes it possible to prevent wrinkles or distortions from forming in the diaphragm 15 when the diaphragm 15 is assembled to the first case 11 and the second case 12.

[0078] The periphery of the diaphragm 15 is sandwiched and compressed by the first case 11 and the second case 12, thereby making the pressure measurement chamber 1 liquid-tight and airtight. It is preferable to achieve liquid-tight and airtight properties by sandwiching and compressing the flexible membrane 40 between the first case 11 and the second case 12, but liquid-tight and airtight properties may also be achieved by sandwiching and compressing the support frame 50 between the first case 11 and the second case 12. The shape of the support frame 50 is not limited, but it is particularly preferable that the locking surface 53 of the support frame 50 is located inside the locking surface 47 of the flexible membrane 40, and that the locking surface 53 and the locking surface 47 face each other inward and outward (see FIG. 4A ). In this case, the area of ​​the attachment portion between the support frame 50 and the flexible membrane 40 in the inner region of the periphery of the flexible membrane 40 can be increased, and the engaging surface 47 of the flexible membrane 40 faces the engaging surface 53 of the support frame 50 in the direction of removal from the support frame 50 (i.e., inward), so it is effectively prevented from coming off, further preventing the diaphragm from shifting position and the resulting wrinkles and distortions.

[0079] Furthermore, when the support frame 50 is fitted into the second insertion groove 73, the first surface 71a of the second case 12 faces the first surface 61a of the first case 11, and the first portion 43 of the flexible membrane 40 is sandwiched between them. At this time, the rib 71b protruding from the first surface 71a bites into the first portion 43. Therefore, the pressure measurement chamber 1 can ensure high sealing performance between the inside of the chamber space 13 and the outside of the housing 14.

[0080] As described above, the pressure measurement chamber 1 according to the first embodiment is easy to assemble and can be assembled appropriately. Furthermore, since the flexible membrane 40 and the support frame 50 are made of different materials, suitable materials can be selected separately for each component in terms of performance (flexibility and rigidity) and dimensions (thickness, etc.). Note that the above-described configuration is an example and can be modified as appropriate.

[0081] For example, while the configuration shown in the example has the first insertion groove 63 and the second insertion groove 73 for insertion into the support frame 50, a configuration having only one of these may also be used. Furthermore, as described above, the ribs 63a and 73a improve the sealing performance between the flexible membrane 40 and the support frame 50, but these are not essential, and only one of these may be used, or both may be omitted. Furthermore, the first portion 43 of the flexible membrane 40 is configured to ensure sealing performance by having the rib 71b bite into one surface thereof, but in this case, a material with higher rigidity than the flexible membrane 40 may be used for the other surface of the first portion 43. Furthermore, when the sealing performance between the flexible membrane 40 and the support frame 50 is formed using the ribs 63a and 73a, etc., as described above, the sealing performance provided by the first portion 43 of the flexible membrane 40 and the rib 71b may be omitted. In addition, although an example has been given of a configuration in which ribs 71b are provided on the first surface 71a of the first part 71 of the second case 12, instead of or in addition to this, ribs may be provided on the first surface 61a of the first part 61 of the first case 11.

[0082] Furthermore, the tapered surface 74a is not essential. If a tapered surface is provided, it may be provided at the lower end of the inner wall surface of the second insertion groove 73, at the upper end of the inner wall surface of the first insertion groove 63, or at the upper end of the outer wall surface of the first insertion groove 63. Alternatively, a tapered surface may be provided at a connection point between the outer peripheral surface of the support frame 50 and the upper or lower surface, or at a connection point between the inner peripheral surface of the support frame 50 and the upper or lower surface, etc.

[0083] (Embodiment 2) The configuration of a pressure measurement chamber 1A according to embodiment 2 of the present disclosure will be described. Fig. 5 is a perspective view showing the configuration of the pressure measurement chamber 1A. Fig. 6 is a longitudinal cross-sectional view of the pressure measurement chamber 1A. Note that the following mainly describes the configuration of the pressure measurement chamber 1A that is different from the pressure measurement chamber 1 described in embodiment 1. Furthermore, components of the pressure measurement chamber 1A that are similar to those of the pressure measurement chamber 1 will be assigned the same reference numerals, and their description may be omitted.

[0084] The pressure measurement chamber 1A has a housing 14 in which a first case 11 and a second case 12 are joined together to form a chamber space 13. A flexible diaphragm 15 is provided within the housing 14, and the diaphragm 15 divides the chamber space 13 into a first chamber 13a on the first case 11 side and a second chamber 13b on the second case 12 side. Note that the cross-sectional view of Figure 6 shows a configuration in which the diaphragm 15 is housed in a state in which it bulges upward in a convex manner.

[0085] The first case 11 is formed with a first port P1 and a second port P2, and the second case 12 is formed with a third port P3 having a configuration different from that of the third port P3 of the first embodiment. The third port P3 of the second embodiment is provided at the top of the second case 12, extending forward from near the center in the front-to-rear direction. The internal passage of the third port P3 is formed along the front-to-rear direction, similar to the first port P1 and the second port P2. The rear end of this internal passage opens downward near the top of the second case 12 (near the center in the front-to-rear direction and the center in the left-to-right direction) and communicates with the second chamber 13b, and the front end opens forward to the outside near the front of the second case 12.

[0086] Furthermore, unlike the pressure measurement chamber 1, the pressure measurement chamber 1A does not have a groove 25 provided in the bottom of the first case 11. However, the pressure measurement chamber 1A may also have a groove 25 provided in the bottom of the first case 11, or a convex portion may be provided on the inner surface 22 of the first case 11 instead of or in addition to the groove 25.

[0087] In the pressure measurement chamber 1A according to the present disclosure, the diaphragm 15 is also configured with a flexible membrane 40A made of a highly flexible material and a support frame 50A made of a material with higher rigidity than the flexible membrane 40A, thereby improving ease of assembly, etc. The structure related to this ease of assembly will be described below.

[0088] Fig. 7 is a cross-sectional view of the diaphragm 15. Fig. 8A is an enlarged cross-sectional view of a portion of the diaphragm 15 surrounded by an imaginary circle VIIIA in Fig. 7, and Fig. 8B is an enlarged cross-sectional view of a portion of the pressure measurement chamber 1A surrounded by an imaginary circle VIIIB in Fig. 6.

[0089] As shown in Figure 7, the diaphragm 15 includes a flexible film 40A and a support frame 50A, and is dome-shaped overall, with a structure that is rotationally symmetrical about a predetermined imaginary line L that faces the vertical direction. The flexible film 40A of the diaphragm 15 has a film portion 41 consisting of a dome-shaped main body portion 41a and a thin portion 41b, and a flange portion 42A. Of these, the film portion 41 has the same configuration as the film portion 41 described in the first embodiment. The imaginary line L is a line that passes through the center of the dome-shaped film portion 41.

[0090] The flange portion 42A has an extension portion (seal portion) 80 extending outward from the other end of the thin-walled portion 41b. This extension portion 80 is a substantially horizontal plate-like member that wraps around the thin-walled portion 41b to form a ring. An enlarged portion 81 is provided at the outer end of the extension portion 80. As an example, the cross section of this enlarged portion 81 has a vertically elongated rectangular shape whose vertical dimension is greater than its horizontal dimension, and the vertical dimension of the enlarged portion 81 is greater than the vertical dimension of the extension portion 80. In other words, the enlarged portion 81 extends upward and downward from the outer end of the extension portion 80, and the connection between the extension portion and the enlarged portion 81 forms a shape resembling a T tilted at 90 degrees.

[0091] On the other hand, the support frame 50A is generally annular, and its cross section is a vertically elongated rectangle whose vertical dimension is greater than its horizontal dimension. More specifically, the support frame 50A has a cross-sectional shape whose vertical dimension is greater than that of the enlarged portion 81 and whose horizontal dimension is also greater than that of the enlarged portion 81. A part of the outer side of the first portion 80 and the enlarged portion 81 are embedded inside the support frame 50A.

[0092] That is, the support frame 50A has a first space 82 that opens to its inner peripheral surface, and a second space 83 that is provided on the far side (outside) of the first space 82. The second space 83 has a larger vertical dimension than the first space 82, and when the first space 82 and the second space 83 are combined, their cross-sectional shape forms a T-shape tilted at 90 degrees. The outer portion of the first portion 80 is embedded in the first space 82, and the expanded portion 81 is embedded in the second space 83.

[0093] 8A , the wall surface defining the second space 83 in the support frame 50A has an outwardly facing engaging surface 84. The engaging surface 84 is provided at two locations, one above and one below the first space 82. Meanwhile, the enlarged portion 81 located on the periphery of the flexible membrane 40A has an inwardly facing engaging surface 85. The engaging surface 85 is provided at two locations, one above and one below the first portion 80.

[0094] The engaging surface 84 and the engaged surface 85 face each other horizontally and are in contact with each other. Therefore, even if the flexible membrane 40A is deformed by a pressure difference during pressure measurement and the flange portion 42A is pulled inward, the engaged surface 85 of the flexible membrane 40A is engaged with the engaging surface 84 of the support frame 50A, preventing the flexible membrane 40A from detaching from the support frame 50A. Note that the materials constituting the flexible membrane 40A and the support frame 50A of the diaphragm 15 of the second embodiment are the same as those of the diaphragm 15 of the first embodiment.

[0095] As shown in Figure 8B, in order to clamp and fix the diaphragm 15 as described above, a first connecting portion 60A is provided on the first circumferential portion 23 of the first case 11, and a second connecting portion 70A is provided on the second circumferential portion 33 of the second case 12.

[0096] The first connection portion 60A has an inner peripheral wall 90 located at the open end of the case body 20, an outer peripheral wall 92 located outside the inner peripheral wall 90, and a first insertion groove 91 located between the inner peripheral wall 90 and the outer peripheral wall 92. The inner peripheral wall 90 extends to protrude upward, and its upper end surface 90a forms a horizontal plane perpendicular to the up-down direction. The outer peripheral wall 92 extends to protrude upward, and its upper end is located higher than the upper end of the inner peripheral wall 90. The first insertion groove 91 is formed between the inner peripheral wall 90 and the outer peripheral wall 92 as a space having a substantially rectangular cross section. The first insertion groove 91 is a groove that opens upward and is provided around the opening of the case body 20. The upper end surface of the outer peripheral wall 92 has a protruding portion 92a for welding that protrudes upward. This protruding portion 92a melts during welding to form a welding surface. For ease of understanding, the drawing shows the convex portion 92a in its convex shape before melting.

[0097] The second connection portion 70A has an inner circumferential wall 94 located at the open end of the case body 30, an outer circumferential wall 96 located outside the inner circumferential wall 94, and a second insertion groove 95 located between the inner circumferential wall 94 and the outer circumferential wall 96. The inner circumferential wall 94 extends so as to protrude downward, and its lower end surface 94a forms a horizontal plane perpendicular to the up-down direction and is located opposite the upper end surface 90a of the inner circumferential wall 90. In addition, a rib 94b protruding downward is provided on the lower end surface 94a.

[0098] The outer peripheral wall 96 extends downward, with its lower end positioned at approximately the same height as the lower end of the inner peripheral wall 94 in the vertical direction. A second insertion groove 95 is formed between the inner peripheral wall 94 and the outer peripheral wall 96 as a space having a substantially rectangular cross section. The second insertion groove 95 is a groove that opens downward and runs around the opening of the case body 30. The outer peripheral wall 92 of the first connecting portion 60A and the outer peripheral wall 96 of the second connecting portion 70A each form an opposing wall portion 99. These opposing walls 99 (the outer peripheral wall 92 and the outer peripheral wall 96) face each other in the inward / outward direction as shown in FIG. 8B . This facilitates positioning between the first case 11 and the second case 12.

[0099] While FIG. 8B illustrates a configuration in which the outer peripheral wall 96 of the second connection portion 70A is positioned outward in the inward-outward direction relative to the outer peripheral wall 92 of the first connection portion 60A, this configuration is not limited thereto. For example, the outer peripheral wall 96 of the second connection portion 70A may be positioned inward in the inward-outward direction relative to the outer peripheral wall 92 of the first connection portion 60A. Furthermore, the opposing walls for positioning the first case 11 and the second case 12 are not limited to the configuration of the outer peripheral walls 92, 96 described above. Separately from or instead of the outer peripheral walls 92, 96, opposing walls for positioning the first case 11 and the second case 12 may be provided at any position between them. Furthermore, the opposing walls are not limited to being opposed to each other in the inward-outward direction, but may be opposed in the circumferential direction. Furthermore, the first connection portion 60A and the second connection portion 70A may each have opposing walls that match each other in shape. The first case 11 and the second case 12 may be positioned relative to each other via the support frame 50A. In this case, the contact surfaces between the first case 11 and the support frame 50A form opposing walls, and the contact surfaces between the second case 12 and the support frame 50A also form opposing walls. The configuration of the opposing walls is not particularly limited, and may be, for example, formed by the contact surfaces between a cutout portion and a protrusion that match each other in shape.

[0100] The groove width (horizontal dimension) of the second insertion groove 95 is larger than the groove width of the first insertion groove 91. More specifically, the groove width of the second insertion groove 95 is designed to be approximately the same as the sum of the groove width dimension of the first insertion groove 91 and the horizontal thickness dimension of the lower outer peripheral wall 92. Therefore, when the first case 11 and the second case 12 are assembled so that the inner peripheral wall 90 and the inner peripheral wall 94 face each other, the lower outer peripheral wall 92 fits into the outer portion of the upper second insertion groove 95, and a rectangular storage space 98 is formed by the first insertion groove 91 and the second insertion groove 95. In the pressure measurement chamber 1A, the support frame 50A is accommodated and held in this storage space 98. The storage space 98 has a vertical dimension slightly larger than that of the support frame 50A.

[0101] The procedure for assembling the pressure measurement chamber 1A having the above-described configuration is as follows. First, the diaphragm 15 is attached from above to the first case 11 with the opening 21 facing upward. That is, the flange portion 42A of the diaphragm 15 and the underside of the support frame 50A are arranged to face the first circumferential portion 23 of the first case 11. At this time, the lower portion of the support frame 50A of the diaphragm 15 is fitted into the first insertion groove 91 of the first case 11. In addition, the outer extension portion 80 of the flexible membrane 40A of the diaphragm 15 is placed on the upper end surface 90a of the inner circumferential wall 90 of the first case 11.

[0102] Next, the second case 12 is assembled to the first case 11 from above with the opening 31 facing downward. At this time, the outer peripheral wall 92 of the first case 11 and the support frame 50A are fitted into the second insertion groove 95 of the second case 12. As a result of this assembly, the support frame 50A is accommodated and held within the accommodation space 98 formed by the first insertion groove 91 and the second insertion groove 95. At this time, the outer extension portion (seal portion) 80 of the flange portion 42A of the diaphragm 15 is sandwiched and compressed between the upper end surface 90a of the inner peripheral wall 90 of the first case 11 and the lower end surface 94a of the inner peripheral wall 94 of the second case 12. In addition, a rib 94b protruding from the lower end surface 94a of the inner peripheral wall 94 is fitted into the upper surface of the outer extension portion 80. That is, by fitting the first case 11 and the second case 12 together with the diaphragm 15 sandwiched therebetween, the outer extension portion 80 of the diaphragm 15 is sandwiched between the upper end surface 90a and the lower end surface 94a, and the support frame 50A is fixed between the first connecting portion 60A and the second connecting portion 70A (inside the accommodation space 98 in FIG. 8B ). Note that the support frame 50A may be fixed with a clearance from the first case 11 and the second case 12, or may be sandwiched and sealed by the first case 11 and the second case 12.

[0103] In this state, the first case 11 and the second case 12 are connected by adhesion or welding. For example, the upper end of the outer peripheral wall 92 of the first case 11 and the bottom surface (ceiling surface) of the second insertion groove 95 of the second case 12, which is opposed thereto in the vertical direction, are connected by ultrasonic welding or the like. At this time, the protrusion 92a formed on the upper end surface of the outer peripheral wall 92 melts, welding the first case 11 and the second case 12 to each other. As a result, the first case 11 is locked and fixed to the second case 12.

[0104] The pressure measurement chamber 1A according to the second embodiment has the same effects as the pressure measurement chamber 1 described in the first embodiment. That is, since the diaphragm 15 is composed of a highly flexible flexible film 40A and a support frame 50A made of a material with higher rigidity than the flexible film 40A, the shape stability of the diaphragm 15 is high. Therefore, the assembly is easy and can be properly performed.

[0105] (Variation 1) Variation 1 of the structure relating to ease of assembly will be described. This variation 1 can be applied to, for example, the pressure measurement chamber 1 according to embodiment 1 or the pressure measurement chamber 1A according to embodiment 2. Here, the case where it is applied to the pressure measurement chamber 1A according to embodiment 2 will be described.

[0106] Fig. 9 is a cross-sectional view of the diaphragm 15 according to Modification 1. Fig. 10A is an enlarged cross-sectional view of a portion of the diaphragm 15 according to Modification 1, and Fig. 10B is an enlarged cross-sectional view of a portion of a pressure measurement chamber to which the diaphragm 15 according to Modification 1 is assembled. Note that in the structure according to Modification 1, the configuration other than the diaphragm 15 is the same as the configuration shown in Embodiment 2. Therefore, the following description will focus on the differences between the diaphragm 15 of Embodiment 2 and the diaphragm 15 according to Modification 1.

[0107] As shown in Figure 9, the diaphragm 15 includes a flexible film 40B and a support frame 50B, and is dome-shaped overall, with a structure that is rotationally symmetrical about a predetermined imaginary line L that faces the up-down direction. The flexible film 40B of the diaphragm 15 has a film portion 41 consisting of a dome-shaped main body portion 41a and a thin portion 41b, and a flange portion 42B. Of these, the film portion 41 has the same configuration as the film portion 41 described in the first and second embodiments. The imaginary line L is a line that passes through the center of the dome-shaped film portion 41.

[0108] The flange portion 42B has an extension portion (seal portion) 100 that extends outward from the other end of the thin-walled portion 41b. This extension portion 100 is a substantially horizontal plate that wraps around the thin-walled portion 41b to form a ring. A protruding portion 101 extends downward from the undersurface of the outer portion of the extension portion 100. In other words, this protruding portion 101 is provided on the side of the flange portion 42B that is closest to the first case 11. In addition, an engaged portion 102 extends upward from the upper surface of the outer end of the extension portion 100.

[0109] The cross-sectional shape of the downwardly extending convex portion 101 is a vertically elongated rectangle whose vertical dimension is greater than its horizontal dimension, and the lower end 101a is arc-shaped so as to bulge downward. The upwardly extending engaged portion 102 is also a vertically elongated rectangle whose vertical dimension is greater than its horizontal dimension. The engaged portion 102 is smaller than the convex portion 101 in both horizontal and vertical dimensions. The outer peripheral surface of the engaged portion 102 is flush with the outer peripheral surface of the convex portion 101, and the inner peripheral surface of the engaged portion 102 forms an inward-facing engaged surface 102a.

[0110] On the other hand, the support frame 50B is generally annular, and its cross section is an inverted U-shape (i.e., an inverted U-shape), and is provided on the side of the flange portion 42B opposite the convex portion 101 and closer to the second case 12 (i.e., the upper side). Specifically, the support frame 50B has an inner frame 104, an outer frame 106, and an engagement groove 105 located between them. The inner frame 104 has a rectangular cross section and contacts the upper surface of the extension portion 100 and the inner peripheral surface of the engaged portion 102 (i.e., the engaged surface 102a). The surface of the inner frame 104 that contacts the engaged surface 102a forms an outward-facing engaging surface 104a.

[0111] The outer frame 106 has a rectangular cross section, and a tapered surface 106a is formed where its lower surface and outer surface connect. This tapered surface 106a slopes upward from the inside to the outside. The outer frame 106 contacts the outer peripheral surface of the flange portion 42B, i.e., the outer peripheral surface of the ridge portion 101 and the outer peripheral surface of the engaged portion 102. The engagement groove 105 is formed between the inner frame 104 and the outer frame 106, and has a space with a rectangular cross section that roughly matches the shape of the engaged portion 102.

[0112] The diaphragm 15 according to Modification 1 is sandwiched and fixed between the first connecting portion 60A of the first case 11 and the second connecting portion 70A of the second case 12 in the same manner as described in Embodiment 2. At this time, the outer extension portion (sealing portion) 100 of the diaphragm 15 is sandwiched and compressed between the inner circumferential wall 90 of the first case 11 and the inner circumferential wall 94 of the second case 12, and the rib 94b bites into the upper surface of the outer extension portion 100. This seals the inside and outside of the housing 14.

[0113] Furthermore, when the diaphragm 15 according to the first modification is sandwiched between the first case 11 and the second case 12, the lower end 101a of the convex portion 101 is pressed against the bottom surface of the first insertion groove 91. The convex portion 101 is part of the flexible membrane 40B and is made of a material that is less rigid and more flexible than the support frame 50B. Therefore, the pressed convex portion 101 deforms and tightly contacts the bottom surface of the first insertion groove 91 over a wide area, improving the sealing performance between the inside and outside of the housing 14. Furthermore, because the convex portion 101 is in contact with the first insertion groove 91 (i.e., the first case 11), it particularly contributes to improving the airtightness and liquidtightness of the first chamber 13a. This effectively prevents leakage of blood flowing through the first chamber 13a.

[0114] On the other hand, the diaphragm 15 according to Modification 1 includes a highly rigid support frame 50B, and therefore, similar to Embodiments 1 and 2, the shape stability of the diaphragm 15 is high and assembly is easy. Also, as described above, the tapered surface 106a is provided on the outer side of the lower end of the support frame 50B. Therefore, when assembling the diaphragm 15 to the first case 11, the support frame 50B can be easily fitted into the first insertion groove 91. In this respect as well, the structure according to Modification 1 is designed to improve assembly.

[0115] (Variation 2) In Variation 1, the inside and outside of the pressure measurement chamber are sealed at two locations, the rib 94b and the convex portion 101, but this is not limiting. Fig. 11 is an enlarged cross-sectional view of a portion of the pressure measurement chamber of Variation 2. As shown in Fig. 11, the pressure measurement chamber of Variation 2 does not include the rib 94b, unlike the configuration of Variation 1. Even with this configuration, the lower end 101a of the convex portion 101 is pressed against the bottom surface of the first insertion groove 91, ensuring sealing of the inside and outside of the pressure measurement chamber.

[0116] Furthermore, in the pressure measurement chamber of Modification 2, the convex ridge portion 101 has an even larger inner-outer dimension than the configuration of Modification 1. As a result, when the diaphragm 15 is sandwiched between the first case 11 and the second case 12, the convex ridge portion 101 is compressed in the vertical direction, expanding the inner-outer dimension. As a result, the lower end 101a of the convex ridge portion 101 is pressed against the bottom surface of the first insertion groove 91, and the inner end surface 101b of the convex ridge portion 101 is also pressed against the outer end surface 90b of the inner circumferential wall 90 of the first case 11. Therefore, even without the rib 94b, reliable sealing can be achieved at two locations.

[0117] (Variation 3) In Variation 1, the convex rib portion 101 is provided on the lower side close to the first case 11, and the support frame 50B is provided on the upper side close to the second case 12, but this is not limiting. Fig. 12 is an enlarged cross-sectional view of a portion of the pressure measurement chamber of Variation 3. Unlike the pressure measurement chamber of Variation 1, the pressure measurement chamber of Variation 3 is configured such that the convex rib portion 101 is provided on the upper side close to the second case 12, and the support frame 50B is provided on the lower side close to the first case 11. The other configurations are the same as those of Variations 1 and 2.

[0118] In the case of Modification 3, the upper end 101c of the convex portion 101 is in close contact with the bottom surface (ceiling surface) of the second insertion groove 95 over a wide area. Therefore, the sealing between the inside and outside of the housing 14 is ensured at two locations: the rib 94b and the upper end 101c of the convex portion 101. Furthermore, Modification 3 improves the ease of assembly of the pressure measurement chamber. That is, when the diaphragm 15 is placed (assembled) in the first case 11, the highly rigid support frame 50B of the diaphragm 15 is placed in the first insertion groove 91 of the first case 11. Therefore, the diaphragm 15 can be easily and stably positioned relative to the first case 11.

[0119] 12, the rib 94b may be omitted, as described in Modification 2. Alternatively, the rib 94b may be omitted and the dimensions of the convex portion 101 in the inner and outer directions may be increased so that the convex portion 101 comes into contact with the second insertion groove 95 at two points, the upper end and the inner end face.

[0120] (Modification 4) Modification 4 of the structure relating to ease of assembly will be described. This modification 4 can also be applied to, for example, the pressure measurement chamber 1 according to embodiment 1 or the pressure measurement chamber 1A according to embodiment 2. Here, the case where it is applied to the pressure measurement chamber 1A according to embodiment 2 will be described.

[0121] Fig. 13 is a cross-sectional view of the diaphragm 15 according to Modification 4. Fig. 14A is an enlarged cross-sectional view of a portion of the diaphragm 15 according to Modification 4, and Fig. 14B is an enlarged cross-sectional view of a portion of a pressure measurement chamber to which the diaphragm 15 according to Modification 4 is assembled. Note that in the structure according to Modification 4, the configuration other than the diaphragm 15 is the same as the configuration shown in Embodiment 2. Therefore, the following description will focus on the differences between the diaphragm 15 of Embodiment 2 and the diaphragm 15 according to Modification 4.

[0122] 13, the diaphragm 15 includes a flexible film 40C and a support frame 50C, and is dome-shaped overall, with a structure that is rotationally symmetrical with respect to a predetermined imaginary line L that faces the up-down direction. The flexible film 40C of the diaphragm 15 has a film portion 41 consisting of a dome-shaped main body portion 41a and a thin portion 41b, and a flange portion 42C. Of these, the film portion 41 has the same configuration as the film portion 41 described in the first and second embodiments and the first modification. The imaginary line L is a line that passes through the center of the dome-shaped film portion 41.

[0123] The flange portion 42C has an extension portion (seal portion) 110 extending outward from the other end of the thin-walled portion 41b. This extension portion 110 is a substantially horizontal plate that wraps around the thin-walled portion 41b to form a ring. An enlarged portion 111 is provided at the outer end of the extension portion 110. This enlarged portion 111 is a vertically elongated rectangle whose vertical dimension is greater than its horizontal dimension, and each corner is chamfered into an arc. The cross-sectional dimensions of this enlarged portion 111 are substantially the same as the rectangular storage space 98 created when the first case 11 and the second case 12 are assembled. Strictly speaking, the size of this enlarged portion 111 is slightly smaller in both length and width than the storage space 98.

[0124] On the other hand, the support frame 50C is generally annular, and its cross section is a vertically elongated rectangle whose vertical dimension is greater than its horizontal dimension. The cross-sectional dimensions of the support frame 50C are smaller than the enlarged portion 111 of the flange portion 42C in both the vertical and horizontal directions. The support frame 50C is embedded within the enlarged portion 111. That is, as shown in the cross-sectional view of FIG. 14B , the support frame 50C is surrounded by the enlarged portion 111 in all directions, including inward, outward, upward, and downward.

[0125] The diaphragm 15 according to the fourth modification is sandwiched and fixed between the first connecting portion 60A of the first case 11 and the second connecting portion 70A of the second case 12 in the same manner as described in the second embodiment. At this time, the outer extension portion (sealing portion) 110 of the diaphragm 15 is sandwiched and compressed between the inner circumferential wall 90 of the first case 11 and the inner circumferential wall 94 of the second case 12, and the rib 94b bites into the upper surface of the outer extension portion 110. This seals the inside and outside of the housing 14. With the outer extension portion 110 of the diaphragm 15 sandwiched in this manner, the support frame 50C is accommodated and fixed between the first connecting portion 60A and the second connecting portion 70A (in the accommodation space 98 in FIG. 14B ). The expanded portion 111 may be fixed with a clearance from the first case 11 and the second case 12, or may be sandwiched and sealed between the first case 11 and the second case 12. In this case, the rib 94b may be omitted.

[0126] Furthermore, the diaphragm 15 according to Modification 4 includes a highly rigid support frame 50C, which provides the diaphragm 15 with high shape stability and excellent assembly ease, similar to Embodiments 1 and 2 and Modifications 1 to 3. Furthermore, as described above, the corners of the enlarged portion 111 of the flange 42C are rounded. This makes it easier to fit the enlarged portion 111 of the flange 42C into the first insertion groove 91 when assembling the diaphragm 15 to the first case 11, and also makes it easier to fit the enlarged portion 50C into the second insertion groove 95 when covering the second case 12. In this respect as well, the structure according to Modification 4 is designed to improve assembly ease.

[0127] (Embodiment 3) The configuration of a pressure measurement chamber 1B according to embodiment 3 of the present disclosure will be described. Fig. 15A is an external plan view showing the configuration of the pressure measurement chamber 1B, Fig. 15B is a cross-sectional view taken along line B-B in Fig. 15A, and Fig. 15C is an enlarged view of a portion of the cross-sectional view in Fig. 15B. Note that the following description will mainly focus on the configuration of the pressure measurement chamber 1B that differs from the pressure measurement chamber 1A described in embodiment 2.

[0128] The pressure measurement chamber 1B has a housing 14 in which a first case 11 and a second case 12 are joined together to form a chamber space 13. A flexible diaphragm 15 is provided within the housing 14, and the diaphragm 15 divides the chamber space 13 into a first chamber 13a on the first case 11 side and a second chamber 13b on the second case 12 side. The cross-sectional view of Figure 15B shows a configuration in which the diaphragm 15 is housed in a state where it bulges upward in a convex shape.

[0129] The first case 11 is formed with a first port P1 and a second port P2 similar to those in embodiment 2, and the second case 12 is formed with a third port P3 similar to those in embodiment 2. The flow paths of these two ports, the first port P1 and the second port P2, are coaxial with each other, and the center lines pass through the center CP of the chamber space 13 and are oriented in the front-to-rear direction.

[0130] However, the first port P1 and the second port P2 may be provided with their axial positions offset to the left or right, or their axial positions may intersect or be provided parallel to each other.

[0131] Incidentally, in the pressure measurement chamber 1B according to the present disclosure, the diaphragm 15 is also configured with a flexible membrane 40D made of a highly flexible material and a support frame 50D made of a material more rigid than the flexible membrane 40D, thereby improving ease of assembly. The structure related to this ease of assembly will be described below. In order to support the diaphragm 15, the housing 14 has a first connecting portion 60A provided on the first winding portion 23 of the first case 11 and a second connecting portion 70A provided on the second winding portion 33 of the second case 12.

[0132] The configurations of the first connecting portion 60A and the second connecting portion 70A are the same as those described in embodiment 2. That is, as shown in Fig. 15C , the first connecting portion 60A has an inner circumferential wall 90, an outer circumferential wall 92, a first insertion groove 91, an upper end surface 90a, a protrusion 92a, etc., and the second connecting portion 70A has an inner circumferential wall 94, an outer circumferential wall 96, a second insertion groove 95, a lower end surface 94a, a rib 94b, etc. Details of these configurations have been described in embodiment 2 and are therefore omitted here (see also Figs. 8B , 10B , 11 , 12 , and 14B ).

[0133] Fig. 16A is a perspective view of diaphragm 15 according to embodiment 3, Fig. 16B is a cross-sectional view of diaphragm 15 of Fig. 16A taken along line B-B, and Fig. 16C is an enlarged view of a portion of the cross-sectional view of Fig. 16B. This diaphragm 15 includes a flexible membrane 40D and a support frame 50D. Flexible membrane 40D has a membrane portion 41 consisting of a dome-shaped main body portion 41a and a thin portion 41b, and a flange portion 42D. Of these, membrane portion 41 has the same configuration as membrane portion 41 described in embodiments 1 and 2.

[0134] The flange portion 42D has an extension portion (seal portion) 120 extending outward from the other end of the thin-walled portion 41b. This extension portion 120 is a substantially horizontal plate that wraps around the thin-walled portion 41b to form a ring. An enlarged portion 121 is provided at the outer end of the extension portion 120. This enlarged portion 121 has a lower enlarged portion 122 that extends downward from the lower surface 120d of the outer end of the extension portion 120 and wraps around the outer end, and an upper enlarged portion (embedded portion) 123 that similarly extends upward from the upper surface 120u of the outer end of the extension portion 120 and wraps around the outer end.

[0135] The thickness of the lower expansion portion 122, which is the dimension between the inner surface 122a close to the imaginary line L and the outer surface 122b far from the imaginary line L, is substantially constant from the top to the bottom, and the cross section thereof has a rectangular shape with substantially constant vertical and thickness dimensions. In addition, both the inner surface 122a and the outer surface 122b are parallel to the imaginary line L and form surfaces that are substantially perpendicular to the lower surface 120d of the extension portion 120.

[0136] The upper expansion portion 123 has a cross section that is approximately wedge-shaped. Specifically, the upper expansion portion 123 has an inner inclined surface 123a that extends upward and outward from the upper surface 120u of the extension portion 120, and an outer inclined surface 123b that extends upward and outward from the outer end surface of the extension portion 120. The inner inclined surface 123a has a larger inclination angle with respect to the upper surface 120u of the extension portion 120 than the outer inclined surface 123b. Therefore, the inner inclined surface 123a and the outer inclined surface 123b are connected at their upper ends to form an upper end portion 123c of the upper expansion portion 123. This upper end portion 123c is located further outward than the outer end of the extension portion 120 (i.e., it overhangs).

[0137] The upper expanded portion 123 forms an embedded portion that is embedded in the support frame 50D. That is, the upper expanded portion 123, located at the outer end of the flange portion 42D of the flexible membrane 40D, is embedded inside the support frame 50D so that the inner inclined surface 123a, which is the inner surface in the inward / outward direction (second direction), and the outer inclined surface 123b, which is the outer surface, are fixed to the inner inclined surface 136a and the outer inclined surface 136b of the support frame 50D, respectively (see FIG. 16C ). This ensures a large area for the fixing surface between the flexible membrane 40D and the support frame 50D, and the flexible membrane 40D is stably held by the support frame 50D.

[0138] The inner inclined surface 136a of the support frame 50D forms the locking surface, the inner inclined surface 123a of the flexible membrane 40D forms the locked surface, the inner inclined surface 123a is located outside the inner inclined surface 136a, and the inner inclined surfaces 136a, 123a are located opposite each other in the inward and outward directions. In this way, the inner inclined surface 136a of the support frame 50D corresponds to the locking surface 53 of the first embodiment, and the inner inclined surface 123a of the flexible membrane 40D corresponds to the locked surface 47 of the first embodiment, and the same functions and effects as those of the first embodiment are achieved.

[0139] The upper and lower ends of the expanded portion 121, including the upper expanded portion (embedded portion) 123, are closed by the support frame 50D. Specifically, the protective portion 139 of the support frame 50D has an upper extension 139u that extends upward in the up-down direction (first direction) beyond the outer surface (upper surface) of the expanded portion 121, and a lower extension 139d that extends downward beyond the outer surface (lower surface) of the expanded portion 121. This prevents the outer peripheral edge of the flexible membrane 40D from contacting the wall surfaces of the first insertion groove 91 and the second insertion groove 95 during assembly.

[0140] On the other hand, the support frame 50D is generally annular, and its cross section is generally rectangular and open downward and inward, and is provided so as to cover the enlarged portion 121 of the flange portion 42D. More specifically, the support frame 50D has an inner surface 130 and an outer surface 131 that extend in the vertical direction, an upper surface 132 that connects the upper end of the inner surface 130 with the upper end of the outer surface 131, and a lower surface 133 that extends inward from the lower end of the outer surface 131, with an opening 134 formed between the inner surface 130 and the lower surface 133. The connecting portions between the inner surface 130 and the upper surface 132, the connecting portions between the outer surface 131 and the upper surface 132, and the connecting portions between the outer surface 131 and the lower surface 133 are all rounded.

[0141] The opening 134 of the support frame 50D has a lower surface 135 that extends outward from the lower end of the inner surface 130 and follows the upper surface 120u of the extension portion 120. The opening 134 also has an inner inclined surface 136a that extends upward and outward from the outer end of the lower surface 135, and an outer inclined surface 136b that extends downward and inward from the upper end of the inner inclined surface 136a. Of these, the inner inclined surface 136a follows the inner inclined surface 123a of the upper expanded portion 123, and the outer inclined surface 136b follows the outer inclined surface 123b of the upper expanded portion 123. Furthermore, the opening 134 has a first inner surface 137 that extends downward from the lower end of the outer inclined surface 136b and follows the outer surface 122b of the lower expanded portion 122 of the extending portion 120, and a second inner surface 138 that extends so as to connect the lower end of the first inner surface 137 with the inner end of the lower surface 133. Of these, the first inner surface 137 extends in the vertical direction and follows the outer surface 122b of the lower expanded portion 122. In addition, the second inner surface 138 forms an inclined surface that extends downward and outward from the lower end of the first inner surface 137.

[0142] In the support frame 50D, the portion of the flexible membrane 40D located outside the enlarged portion 121 of the flange portion 42 (i.e., the portion between the first inner surface 137, the second inner surface 138, and the outer inclined surface 136b and the outer surface 131) forms a protective portion 139. This protective portion 139 prevents the flexible membrane 40D from rubbing against the wall surface of the first insertion groove 91 or the second insertion groove 95 when the diaphragm 15 is inserted into the accommodation space 98. Note that in the diaphragms shown in the embodiments and modified examples already described, the portion of the support frame located outside the enlarged portion forms a protective portion, and provides the same effect as described above.

[0143] The flexible membrane 40D is connected to the support frame 50D by fitting the expanded portion 121 into an opening 134 that opens downward and inward in the support frame 50D. Meanwhile, the upper expanded portion 123 of the flexible membrane 40D forms a retaining portion 140 that prevents the flexible membrane 40D from slipping out of the opening 134 of the support frame 50D. That is, the outer inclined surface 123b of the upper expanded portion 123 of the flexible membrane 40D and the outer inclined surface 136b of the opening 134 of the support frame 50D engage (contact) in the vertical direction, thereby preventing the flexible membrane 40D and the support frame 50D from separating from each other.

[0144] As shown in FIG. 15C , the diaphragm 15 is supported inside the support frame 50D by sandwiching and compressing the outer extension portion (seal portion) 120 of the flange 42D between the upper end surface 90a of the first connection portion 60A of the first case 11 and the rib 94b on the lower end surface 94a of the second connection portion 70A of the second case 12. Meanwhile, the vertical dimension of the accommodation space 98 is longer than the vertical dimension of the support frame 50D. Therefore, the support frame 50D is accommodated in the accommodation space 98 formed by the first insertion groove 91 of the first connection portion 60A and the second insertion groove 95 of the second connection portion 70A, and is loosely fitted with a gap in the vertical direction. This allows the diaphragm 15 to be sandwiched (supported) between the first case 11 and the second case 12 in an airtight and liquid-tight manner.

[0145] The inward / outward dimension of the storage space 98 is longer than the inward / outward dimension of the support frame 50D, and the support frame 50D is loosely fitted into the storage space 98 with a gap in the inward / outward direction. This facilitates insertion of the support frame 50D into the storage space 98. While FIG. 15C illustrates an example in which the storage space 98 has gaps on both the upper and lower sides of the support frame 50D, this configuration is not limited thereto. For example, the support frame 50D may contact the inner bottom surface of the second insertion groove 91 due to its own weight, resulting in a gap only on the upper side of the support frame 50D. Furthermore, a configuration in which the vertical gap dimension (the sum of the upper gap and the lower gap) relative to the support frame 50D (the sum of the inner gap and the outer gap) is larger than the vertical gap dimension (the sum of the inner gap and the outer gap) is preferred.

[0146] (Diaphragm Molding Procedure) The above-described diaphragm 15 can be produced by, for example, two-color injection molding. FIG. 17 is a schematic diagram showing an example of a molding process for the diaphragm 15. As shown in FIG. 17, in the first step, a lower mold 150 and a first upper mold 151 are joined from above and below to form a cavity C1. A first resin is then injected into this cavity C1 to mold the flexible film 40D. For example, a first gate is provided at a position corresponding to the uppermost portion of the dome-shaped film portion 41, and the first resin is injected through this first gate.

[0147] Next, in the second step, the lower mold 150 and the flexible membrane 40D are released from the first upper mold 151 and rotated. During this release, the lower mold 150 and the first upper mold 151 are vertically spaced apart. In the next third step, the second upper mold 152 is brought into contact with the lower mold 150 from above and below so as to sandwich the flexible membrane 40D therebetween, forming a cavity C2. A second resin is injected into this cavity C2 to form the support frame 50D. For example, one or more second gates (four gates equally spaced circumferentially in FIG. 16A ) are provided at positions corresponding to the upper surface 132 of the support frame 50D, and the second resin is injected through these second gates. Finally, the lower mold 150 and the second upper mold 152 are vertically spaced apart, and the diaphragm 15 is released.

[0148] Here, the outer inclined surface 123b of the upper expanded portion 123 of the flexible membrane 40D forms an undercut shape relative to the first upper mold 151. However, because the flexible membrane 40D has low hardness and flexibility, the first upper mold 151 can be easily released in the second step. Meanwhile, because the outer inclined surface 123b forms an undercut shape, the flexible membrane 40D and the support frame 50D engage with each other to prevent separation. The flexible membrane 40D can be made of, for example, an elastomer resin. The support frame 50D can be made of, for example, polypropylene (PP) or polyvinyl chloride (PVC).

[0149] As shown in FIG. 16C , the second inner surface 138 of the support frame 50D forms an inclined surface. This second inner surface 138 forms a draft angle between the lower mold 150 and the first upper mold 151 (see the first step in FIG. 17 ). This facilitates smooth release of the first upper mold 151 in the second step. Also, as shown in FIG. 16A , four recesses 132a are formed on the upper surface 132 of the support frame 50D, evenly spaced circumferentially. These recesses 132a form sunken seats corresponding to the second gates through which the second resin is injected in the third step. That is, after the second upper mold 152 is released, burrs remain on the upper surface 132 of the support frame 50D in the areas corresponding to the second gates. The sunken seats, or recesses 132a, provide a space for burrs and prevent them from coming into contact with the outside.

[0150] While the upper expanded portion 123 shown in FIG. 16C has a wedge-shaped cross section, this is not limited thereto and may be, for example, a plate-like shape with a constant thickness, or may have other shapes. Furthermore, while the upper expanded portion 123 is illustrated as having a shape extending upward and outward, this is not limited thereto and may be, for example, a shape extending upward and inward. Even when the upper expanded portion 123 has a shape extending upward and inward, the upper expanded portion 123 still functions as the retaining portion 140. Furthermore, as shown in FIG. 16A , a recess 132a is provided on the top surface 132 of the support frame 50D as a sink seat, but the recess 132a may be omitted. Furthermore, the lower expanded portion 122 of the expanded portion 121 may be omitted from the perspective of retaining the expanded portion 121.

[0151] As can be seen from the above, when the diaphragm 15 is formed by injection molding, it is preferable that the opening 134 in the support frame 50D that engages with the flexible membrane 40D opens downward. This allows the mold release direction during molding to be limited to the vertical direction, simplifying the molding process. Furthermore, it is preferable that the portion of the flexible membrane 40D that engages with the support frame 50D (the aforementioned retaining portion 140) has an undercut shape when viewed from the vertical direction. This allows the undercut portion to engage with the support frame 50D in the vertical direction, the same as the opening direction of the opening 134, and function as a retaining portion (separation).

[0152] While the above description illustrates a configuration in which the opening 134 of the support frame 50D opens downward and the upper expanded portion 123 of the flexible membrane 40D has an undercut shape, a configuration in which the above configurations are reversed may also be used. That is, the pressure measurement chamber 1B may be configured such that the diaphragm 15 is sandwiched between the first case 11 and the second case 12 in an upside-down state. Furthermore, in the molding procedure for the diaphragm 15, the movement direction when separating the lower mold 150 from the first upper mold 151 or the second upper mold 152 has been described as being vertical. However, this is not limited thereto, and the molds may be moved in other directions, such as horizontally. Furthermore, when separating the molds, it is sufficient that the lower mold 150 and the first upper mold 151 or the second upper mold 152 move relative to each other. For example, the first upper mold 151 or the second upper mold 152 may be moved relative to the lower mold 150, as opposed to the above description.

[0153] (Variation 5) In the pressure measurement chamber 1B according to embodiment 3, resin is injected from above to simplify the two-color molding process of the diaphragm 15. In this case, when the second resin is injected from above in the third step, there is a possibility that the injected second resin will hit and deform the upper expanded portion 123 of the flexible membrane 40D molded in the first step. If the upper expanded portion 123 deforms during the injection of the second resin, the second resin may flow unexpectedly, potentially resulting in molding defects such as residual air. In Variation 5, four types of flexible membrane configurations (variations) that prevent such molding defects are disclosed with reference to FIGS. 18A to 18D. Note that only the configurations that differ from the flexible membrane 40D described above will be described below; the other configurations are the same as those of the flexible membrane 40D.

[0154] 18A has cutouts 160 formed in parts of the upper expanded portion 123. These cutouts 160 are located at positions corresponding to the second gates (i.e., four locations corresponding to the recesses 132a of the support frame 50D), and the upper expanded portion 123 is not formed in the portion of the extension portion 120 of the flange portion 42D where the cutouts 160 are located. As a result, in the third step, the second resin does not directly come into contact with the upper expanded portion 123 immediately after being injected from the second gate, preventing deformation of the upper expanded portion 123.

[0155] 18B shows a flexible membrane 40D2 in which the upper expansion portion 123 is formed around the entire circumference, and ribs 161 extending inward from the upper expansion portion 123 are provided at positions corresponding to the second gates (four positions in this example). The ribs 161 connect the inner inclined surface 123a of the upper expansion portion 123 to the upper surface 120u of the extension portion 120, and are not connected to the membrane portion 41. The inclusion of such ribs 161 improves the strength of the upper expansion portion 123, preventing deformation even when the injected second resin directly hits it. Note that if the ribs 161 can sufficiently ensure the strength of the upper expansion portion 123, the ribs 161 may be positioned circumferentially offset from the positions corresponding to the second gates.

[0156] The flexible membrane 40D3 shown in Fig. 18C has a configuration in which ribs 162 having a similar configuration to the ribs 161 in Fig. 18B are additionally provided. As such, the number of ribs may be the same as or different from the number of second gates. By increasing the number of ribs beyond the number of second gates as in the example of Fig. 18C, the strength of the upper expansion portion 123 can be further improved, and deformation thereof can be more reliably prevented.

[0157] The flexible membrane 40D4 shown in Figure 18D has a rib 163, which is configured by extending the rib 161 in Figure 18B further inward. That is, the rib 163 connects the inner inclined surface 123a of the upper expansion portion 123, the upper surface 120u of the extension portion 120, and the upper surface of the membrane portion 41 (the surface facing the second chamber 13b). This increases the length of the connecting edge of the rib 163, allowing for more solid support of the upper expansion portion 123. This improves the strength of the upper expansion portion 123 and prevents deformation. Note that Figure 18D shows an example in which the same number of ribs 163 as the number of second gates are provided, but this is also just one example, and fewer or more ribs 163 may be provided.

[0158] The flexible membrane disclosed in each of the above-described embodiments and modifications preferably does not elastically return to its original state after displacement. That is, it displaces vertically depending on the pressure difference between the first chamber (blood chamber) 13a and the second chamber (air chamber) 13b, and maintains the displaced posture when the pressure difference is zero. For example, when the pressure in the second chamber 13b becomes lower than that of the first chamber 13a, the membrane portion 41 of the flexible membrane becomes convex toward the second chamber 13b. Even if the pressure difference between the first chamber 13a and the second chamber 13b becomes zero in this state, the membrane portion 41 maintains its convex shape toward the second chamber 13b. Similarly, when the pressure in the first chamber 13a becomes lower than that of the second chamber 13b, the membrane portion 41 of the flexible membrane becomes convex toward the first chamber 13a. In this state, even if the pressure difference between the first chamber 13a and the second chamber 13b becomes zero, the membrane portion 41 maintains its shape convex toward the first chamber 13a.

[0159] Such a flexible membrane preferably has, for example, the following properties: That is, of the first port P1 and the second port P2 that communicate with the first chamber 13a, the first port P1 is closed, and the second port P2 is connected to a pressure sensor via a tube. This tube is branched midway and connected to an air syringe. The second chamber 13b is left open to the atmosphere. In this state, when air is injected using the air syringe, the pressure at which the membrane portion 41 begins to displace is measured using a pressure sensor. The flexible membrane according to the present disclosure preferably has a pressure measured using this method of 10 kPa or less, and more preferably 5 kPa or less. For example, a membrane molded from an elastomer resin can be suitably used as such a flexible membrane.

[0160] The present disclosure can be suitably applied to a diaphragm-type pressure measurement chamber for measuring the pressure of blood flowing through a blood circuit.

[0161] REFERENCE SIGNS LIST 1 Pressure measurement chamber 11 First case 12 Second case 13 Chamber space 13a First chamber 13b Second chamber 14 Housing 15 Diaphragm 40 Flexible membrane 41 Membrane portion 42 Flange portion 50 Support frame 60 First connection portion 63 First insertion groove 70 Second connection portion 73 Second insertion groove 101 Convex portion

Claims

1. A diaphragm-type pressure measurement chamber for measuring the pressure of blood in a blood circuit, comprising: a first case having a first connection portion provided on its periphery; a second case having a second connection portion provided on its periphery and connected to the first connection portion, and forming a chamber space between the first case and the second case; and a flexible dome-shaped diaphragm dividing the chamber space into a first chamber on the blood side and a second chamber on the pressure sensor side, the first chamber being formed between the first case and the diaphragm and communicating with a blood flow path in the blood circuit, the diaphragm having a flexible membrane that deforms in a first direction in response to the pressure difference between the first chamber and the second chamber, and a support frame provided on the periphery of the flexible membrane and fixed between the first connection portion and the second connection portion, the support frame being more rigid than the flexible membrane.

2. A diaphragm-type pressure measurement chamber as described in claim 1, wherein at least one of said first connection portion and said second connection portion is provided with an insertion groove into which said support frame is inserted in said first direction.

3. A diaphragm-type pressure measurement chamber as described in claim 2, wherein the first connection portion and the second connection portion form an accommodation space for accommodating the support frame, and the flexible membrane is formed with a seal portion that is clamped and compressed by the first connection portion and the second connection portion.

4. A diaphragm-type pressure measurement chamber as described in claim 3, wherein the first case is engaged with the second case, and the dimension of the storage space in the first direction is formed longer than the dimension of the support frame in the first direction, thereby providing a gap between the first connection portion or the second connection portion and the support frame within the storage space.

5. The diaphragm type pressure measurement chamber according to claim 2, wherein the support frame has a protective portion located radially outward of the flexible membrane.

6. A diaphragm-type pressure measurement chamber according to claim 5, wherein the flexible membrane has an embedded portion embedded inside the support frame so that the inner and outer surfaces in the second direction are fixed to the support frame.

7. A diaphragm-type pressure measuring chamber according to claim 6, wherein the protective portion has an extension portion that extends beyond an outer surface of the embedded portion of the flexible membrane in the first direction.

8. A diaphragm-type pressure measurement chamber for measuring the pressure of blood in a blood circuit, comprising: a first case having a first connection portion provided on its periphery; a second case having a second connection portion connected to the first connection portion provided on its periphery and forming a chamber space between the first case and the second case; and a flexible diaphragm dividing the chamber space into a first chamber on the blood side and a second chamber on the pressure sensor side, the first chamber being formed between the first case and the diaphragm and communicating with a blood flow path in the blood circuit, the diaphragm having a surface area larger than the cross-sectional area of ​​the chamber space and a three-dimensional shape at least a portion of which is convex in a first direction, a flexible membrane that deforms in a first direction in response to a pressure difference between the first chamber and the second chamber, and a support frame provided on the periphery of the flexible membrane and fixed between the first connection portion and the second connection portion, the support frame having higher rigidity than the flexible membrane.