Air trap chamber and extracorporeal circulation loop

Abstract

An air trap chamber (10) includes a chamber body (12) and a filter (40). An inlet pipe (21) of the chamber body (12) extends into the chamber body (12), and an inlet port (23), which is the end opening of the inlet pipe (21), is disposed on the inner circumferential surface of the chamber body (12). The filter (40) is disposed in the chamber body (12) and covers the outlet port (31) of the chamber body (12). The filter (40) has a cylindrical portion (41) extending around the outlet port (31) in the direction of the central axis of the chamber body (12) and a top (42) covering the upper end of the cylindrical portion (41). On the cylindrical portion (41) of the filter (40), openings (47) are formed in multiple layers along the central axis direction. The circumferential width of the upper opening (47) on the top (42) side of the filter (40) is formed to be greater than the circumferential width of the lower opening (47) on the outlet (31) side.

Description

[0001] This application is a divisional application of application number 201980028250.7 entitled "Air Trap Chamber and Extracorporeal Circulation Circuit", filed on March 15, 2019. Technical Field

[0002] The present invention relates to an air trap chamber and an external circulation loop including the air trap chamber. Background Technology

[0003] For example, in hemodialysis, blood drawn from the patient is sent to an extracorporeal circulation circuit. The extracorporeal circulation circuit includes an arterial side circuit that supplies the drawn blood, a purifier (dialyzer) that cleans the blood from the arterial side circuit, and a venous side circuit that returns the cleaned blood to the patient.

[0004] At least one of the arterial side circuit and the venous side circuit is provided with an air trap chamber for capturing (debubbling) air bubbles in the blood flowing in the circuit. For example, the air trap chamber has an inlet and an outlet at the upper end and an outlet at the lower end.

[0005] In addition, a filter is provided in the air trap chamber to cover its outlet and capture solid objects such as blood clots. For example, Patent Document 1 discloses a filter that has a cylindrical body and a dome-shaped top provided at the upper end of the body.

[0006] Multiple openings are formed on the filter body along the central axis C1 of the cylinder. Regarding these openings, in Patent Document 1, the filter is configured such that the longitudinal width of the upper opening on the top side along the central axis is greater than the longitudinal width of the lower opening on the outlet side. This reduces the resistance (flow resistance) when passing through the (longitudinal) opening on the upper side and suppresses flow stagnation within the air trap chamber.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: U.S. Patent No. 8,500,672. Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] The object of the present invention is to provide an air trap chamber that can reduce the resistance when passing through a filter compared to the past.

[0012] Solutions for solving technical problems

[0013] This invention relates to an air trap chamber. The air trap chamber includes a chamber body and a filter. The chamber body is generally cylindrical, with an inlet tube at one end along its central axis and an outlet at the other end, through which liquid flows downward from the inlet tube to the outlet. The inlet tube extends into the chamber body, and the inlet, as the end opening of the inlet tube, is located circumferentially on the inner circumferential surface of the chamber body. The filter is disposed within the chamber body and covers the outlet of the chamber body. The filter has a cylindrical portion and a top, the cylindrical portion extending around the outlet along the central axis of the chamber body, and the top covering the upper end of the cylindrical portion opposite the lower end of the outlet side of the chamber body. Multiple openings are formed on the cylindrical portion of the filter along the central axis. The circumferential width of the upper opening on the top side of the filter is greater than the circumferential width of the lower opening on the outlet side.

[0014] According to the above structure, since the inlet of the chamber body faces circumferentially on the inner circumferential surface of the chamber body, the flow of liquid flowing in from the inlet becomes a swirling flow along the inner circumferential surface of the chamber body. Generally, the swirling flow slows down closer to its center of rotation; therefore, the flow velocity above the filter (outlet), away from the inner circumferential surface of the chamber body, is relatively slower around the filter. Therefore, as described above, by increasing the circumferential width of the upper opening of the filter in the direction of the swirling flow relative to the circumferential width of the lower opening, resistance during permeation through the upper layer of the filter can be suppressed.

[0015] Furthermore, in the above invention, a plurality of ribs may be provided on the filter in a circumferential manner, extending in the direction of the central axis. In this case, the plurality of ribs may include a first rib extending from the lower end of the filter to the top of the filter, and a second rib terminating before reaching the top of the filter from the lower end.

[0016] By having a second rib, the circumferential width of the opening above the termination point of the second rib can be increased compared to the circumferential width of the opening below the termination point.

[0017] Furthermore, in the above invention, a plurality of ribs may be provided on the filter in a circumferential manner, extending along the central axis. In this case, the ribs may be formed such that their circumferential width narrows from the bottom of the filter toward the top of the filter.

[0018] By forming a rib shape that narrows at the front end as it faces upward, the circumferential width of the opening at the upper end can be increased compared to the circumferential width of the opening at the lower end.

[0019] Furthermore, the present invention relates to an extracorporeal circulation circuit in which drawn blood is circulated. An air trap chamber, as described above, is connected to the flow path of this extracorporeal circulation circuit.

[0020] Invention Effects

[0021] According to the present invention, the resistance when passing through the filter can be reduced compared to the past. Attached Figure Description

[0022] Figure 1 This is a diagram illustrating the external circulation loop of the air trap chamber according to this embodiment.

[0023] Figure 2 This is a perspective view illustrating the air trap chamber according to this embodiment.

[0024] Figure 3 This is a perspective sectional view illustrating the air trap chamber according to this embodiment.

[0025] Figure 4 This is a diagram illustrating the structure of the cover of the air trap chamber according to this embodiment.

[0026] Figure 5 This is a perspective cross-sectional view illustrating the state of the air trap chamber according to this embodiment when in use.

[0027] Figure 6 This diagram illustrates the overall airflow within the air trap chamber according to this embodiment.

[0028] Figure 7 This is a perspective view illustrating a filter installed in an air trap chamber according to this embodiment.

[0029] Figure 8 This is a perspective cross-sectional view illustrating a filter provided in an air trap chamber according to this embodiment.

[0030] Figure 9 This is a perspective enlarged view illustrating a filter provided in an air trap chamber according to this embodiment.

[0031] Figure 10 This is a perspective view showing another example of a filter provided in an air trap chamber according to this embodiment.

[0032] Figure 11 This is a perspective view showing yet another example of a filter provided in an air trap chamber according to this embodiment.

[0033] Figure 12 This is a perspective view showing a comparative example of the filter.

[0034] Figure 13 This is a diagram illustrating the flow distribution near the filter when using the filter involved in the comparative example.

[0035] Figure 14 This is a diagram illustrating the flow distribution near the filter when using the filter according to this embodiment.

[0036] Figure 15 This is a diagram illustrating the flow distribution near the filter when using another example of the filter involved in this embodiment.

[0037] Figure 16 This is a diagram illustrating the flow distribution near the filter when using a filter according to yet another example of this embodiment.

[0038] Figure 17 This is a perspective view illustrating a filter according to yet another example of this embodiment. Detailed Implementation

[0039] Figure 1 An extracorporeal circulation circuit connected to the air trap chamber 10 according to this embodiment is illustrated. The extracorporeal circulation circuit is, for example, a circuit for hemodialysis, including an arterial side circuit 50, a blood purifier 54, a dialysis device 55, a venous side circuit 51, and a rehydration line 60. Furthermore, the air trap chamber 10 according to this embodiment is connected to an extracorporeal circulation circuit for dialysis treatment, but is not limited to this method. For example, the air trap chamber 10 according to this embodiment can be connected to an extracorporeal circulation circuit capable of circulating and purifying the blood drawn from the patient. For example, the air trap chamber according to this embodiment can be connected to an extracorporeal circulation circuit used in Acetate-Free Biofiltration (AFBF), continuous slow-release hemofiltration therapy, blood adsorption therapy, selective blood cell component removal therapy, simple plasma exchange therapy, double filtration plasma exchange therapy, plasma adsorption therapy, etc. Additionally, the air trap chamber 10 according to this embodiment can be provided on the arterial side circuit 50, venous side circuit 51, and rehydration line 60 of the extracorporeal circulation circuit, described later. In addition, the air trap chamber 10 of this embodiment can be connected to pathways where thrombosis may occur, or in general, to pathways where blood or blood components flow in the extracorporeal circulation loop. Furthermore, the air trap chamber 10 of this embodiment can be connected to pathways where blood or blood components flow in the extracorporeal circulation loop, pathways where saline solution flows, and flow paths in the extracorporeal circulation loop including these pathways.

[0040] Blood drawn from the patient is supplied to the arterial side circuit 50. The arterial side circuit 50 is equipped with an arterial side puncture needle 52 and a roller pump 53 from the upstream side. The arterial side puncture needle 52 is inserted into the patient's blood vessel to deliver blood into the tube of the arterial side circuit 50 (blood drawout).

[0041] The roller pump 53 delivers blood from the tube to the blood purifier 54 by circulating the tube from the outside. Furthermore, for example, during priming, priming fluid is sometimes added to the circuit from the venous side circuit, so the roller pump 53 can rotate in both directions.

[0042] The air trap chamber 10 described in this embodiment can also be connected between the arterial side puncture needle 52 and the roller pump 53, and between the roller pump 53 and the blood purifier 54. The structure and function of the air trap chamber 10 will be described later. Furthermore, the air trap chamber 10 in the venous side circuit 51 is an essential structure for reliably removing air bubbles from the blood during blood reinfusion; in contrast, these air trap chambers 10 provided in the arterial side circuit 50 can be arbitrarily arranged.

[0043] A rehydration line 60 is provided between the roller pump 53 of the arterial side circuit 50 and the blood purifier 54. A rehydration bag 57 and a clamp 59 are provided on the rehydration line 60. In addition, an air trap chamber 10 is provided between the rehydration bag 57 and the clamp 59.

[0044] The infusion bag 57 contains physiological saline solution for rehydration. For example, during pre-filling of the extracorporeal circulation circuit, the clamp 59 is in the open state, and physiological saline solution flows from the infusion bag 57 into the extracorporeal circulation circuit. By filling the circuit with physiological saline solution, air bubbles in the circuit are removed. When pre-filling is complete, the clamp 59 switches to the closed state.

[0045] Additionally, after dialysis treatment, in order to return the blood in the circuit to the patient, the clamp 59 is reopened, and the circuit is filled with saline solution from the infusion bag 57. In other words, the blood in the circuit is replaced with saline solution.

[0046] Blood purifier 54 purifies blood delivered from arterial side circuit 50. Blood purifier 54 is a so-called dialyzer, in which dialysate and blood exchange substances via hollow fiber membrane 54A. Blood purifier 54 houses a bundle of multiple hollow fiber membranes 54A (hollow fiber membrane bundles) within a column 54B.

[0047] Column 54B is a cylindrical receiving component, with an inlet side cover 54C mounted at one end along its central axis and an outlet side cover 54D mounted at the other end. The inlet side cover 54C has a blood inlet port 54E that connects to a connector (not shown) at the downstream end of the arterial side circuit 50. The outlet side cover 54D has a blood outlet port 54F that connects to a connector (not shown) at the upstream end of the venous side circuit 51. Blood from the arterial side circuit 50 flows into the interior of the hollow fiber membrane 54A through the blood inlet port 54E.

[0048] A dialysate inlet port 54G is provided on column 54B near the outlet side cover 54D. A dialysate outlet port 54H is provided on column 54B near the inlet side cover 54C. Dialysate is delivered from dialysis apparatus 55 into column 54B via dialysate inlet port 54G. The dialysate and blood undergo mass exchange via hollow fiber membrane 54A, resulting in blood purification. The purified dialysate is returned to dialysis apparatus 55 via dialysate outlet port 54H. The purified blood is delivered to venous side circuit 51 via blood outlet port 54F.

[0049] In the venous side circuit 51, purified blood is reinfused into the patient via the venous side puncture needle 56. In order to remove (de-bubble) air bubbles from the blood during reinfusion, an air trap chamber 10 is provided in the venous side circuit 51.

[0050] Figure 2 The air trap chamber 10 according to this embodiment is illustrated. Additionally, Figure 3 An illustrative perspective sectional view of an air trap chamber 10 is shown. The air trap chamber 10 includes a chamber body 12 and a filter 40.

[0051] It should be noted that during dialysis treatment, the air trap chamber 10 is used in an upright configuration with the upper side of the paper facing upwards and the lower side facing downwards. Hereinafter, unless otherwise stated, the position and structure of each component will be described based on this upright configuration.

[0052] The chamber body 12 is generally cylindrical in shape, and has an inlet tube 21 and an outlet 22 at one end (upper end) along its central axis C1. Additionally, an outlet 31 is provided at the other end (lower end) along the central axis C1. That is, within the chamber body 12, liquid (blood, saline solution, etc.) flows downwards from the inlet tube 21 to the outlet 31. Furthermore, regarding the central axis C1, if the central axes of the cover 20 and the housing 30, which are components of the air trap chamber 10, are offset, the central axis C1 can be the central axis C1 of the housing 30, which occupies most of the volume of the chamber body 12.

[0053] The chamber body 12 may be composed of, for example, a cover 20 and a housing 30. The cover 20 and the housing 30 are obtained, for example, by injection molding resin. The cover 20 is the upper part of the chamber body 12 and is a U-shaped part with an inlet pipe 21 and an exhaust port 22.

[0054] Figure 4 A perspective sectional view of the cover 20 is shown. The cover 20 includes a cover body 25, a flange 27, and an inlet tube 21. The upper end of the cover body 25 is a cylindrical shape closed by an upper wall 25A, and the lower end is connected to the flange 27. The vent 22 extends through the upper wall 25A in the thickness direction.

[0055] Furthermore, the inlet tube 21 extends from the upper wall 25A into the interior of the cover body 25, i.e., the interior of the chamber body 12. An inlet port 23 is then formed at the lower end of the inlet tube 21. Thus, by providing the inlet port 23 below the upper wall 25A, when the air trap chamber 10 is provided in the venous side circuit 51, air bubbles within the chamber body 12 are prevented from escaping through the inlet tube 21 to the upstream side of the venous side circuit 51.

[0056] That is, for example, when the inlet 23 is located on the lower surface of the upper wall 25A, i.e., at the same height as the exhaust port 22, air bubbles in the chamber may not enter the exhaust port 22 but move to the inlet 23 and escape directly to the upstream side of the venous side circuit 51. Therefore, in the air trap chamber 10 according to this embodiment, the inlet 23 is lowered to the interior of the chamber to prevent air bubbles from mixing into the upstream side of the venous side circuit 51.

[0057] Furthermore, the inlet 23 is provided along the inner circumferential surface 26 of the cover body 25, and its opening faces the circumferential direction of the inner circumferential surface 26. For example, a lower wall 21A is formed at the lower end of the inlet tube 21, and its side is cut off to form the inlet 23. For example, the inlet 23 is oriented parallel to the tangential direction of the inner circumferential surface 26. In addition, the cut surface 21B of the inlet 23 is formed to be radially parallel to the inner circumferential surface 26.

[0058] The inlet 23 is located on the inner circumferential surface of the cover body 25, so that the flow of liquid (blood, saline, etc.) flowing out of the inlet 23 becomes a swirling flow along the inner circumferential surface 26. The liquid flow in the air trap chamber 10 becomes a swirling flow, thereby suppressing the retention of liquid in the air trap chamber 10 compared to the case where no specific flow is formed.

[0059] A flange 27 is attached to the lower end of the cover body 25. The inner diameter of the flange 27 is larger than the inner diameter of the cover body 25 (expanded diameter). (See reference...) Figure 3 The flange 32 of the housing 30 is inserted into the flange 27. For example, an adhesive is sealed between the inner peripheral surface of the flange 27 of the cover 20 and the outer peripheral surface of the flange 32 of the housing 30 to bond the cover 20 and the housing 30 together.

[0060] The housing 30 is a generally cylindrical component with a flange 32 formed at the upper end and a discharge tube 33 formed at the lower end. For example, the inner diameter of the flange 32 can be the same as that of the cover body 25 (see reference). Figure 4 The inner diameters of the two are equal.

[0061] The inner diameter of the housing 30 narrows at the bottom to connect with the outlet tube 33. An outlet port 31 is formed at the lower end of the outlet tube 33 and is connected to the tube of the venous side circuit 51 by adhesive or the like. Additionally, a filter 40 is provided to cover the outlet tube 33. Its detailed structure will be described later.

[0062] Figure 5 The state of the air trap chamber 10 during dialysis treatment is illustrated. The air trap chamber 10 can be a so-called gas-free chamber, where the interior space of the chamber body 12 is filled with liquid (blood, saline, etc.), as shown by the dashed shaded line in the figure.

[0063] Thus, with the chamber body 12 filled with liquid, the liquid then flows in through the inlet 23. As described above, since the inlet 23 is located on the inner circumferential surface 26 of the cover 20 and faces circumferentially, the flow of liquid flowing in through the inlet 23 is as follows: Figure 6 As shown, the fluid becomes a swirling flow along the inner circumferential surface 26. The fluid inside the chamber body 12 remains in a swirling flow state, while being delivered from the outlet 31 to the venous side circuit 51 via the filter 40.

[0064] It should be noted that the flow velocity decreases closer to the center of vortex. Therefore, compared to the flow near the inner circumferential surface of the chamber body 12, the liquid further away from this inner circumferential surface, in other words, above the filter 40 disposed on the vortex axis, has a relatively low velocity (low flow rate). As will be described later, in the air trap chamber 10 according to this embodiment, the circumferential opening width above the filter 40 is increased compared to the circumferential opening width below. As a result, the permeation resistance (flow resistance) when passing through the upper opening is reduced, and the retention of low-flow-rate liquid is suppressed.

[0065] Figure 7 The filter 40 according to this embodiment is illustrated. Additionally, Figure 8 A perspective sectional view of filter 40 is shown. Filter 40 is disposed within chamber body 12 covering outlet 31 to capture solid objects such as blood clots in the blood. Filter 40 is, for example, obtained by injection molding resin. Filter 40 is formed such that its length in the longitudinal direction (axial direction) is less than the distance between inlet 23 and outlet 31. Filter 40 has, for example, a cylindrical body and a dome-shaped top disposed at the upper end of the body, and as... Figure 8 As shown, the interior is hollow. Additionally, the lower end is open. The filter 40 includes a cylindrical portion 41, a top portion 42, and a fixing portion 43.

[0066] The fixing part 43 is the lower end of the filter 40 and is embedded in the outlet pipe 33 of the chamber body 12. For example, Figure 3 As shown, the upper end of the outlet tube 33 is a tapered shape with an inner diameter that narrows as it moves upward, and the outer peripheral surface of the fixing part 43 is formed into a corresponding tapered shape (inverted tapered shape).

[0067] When installing the filter 40 on the chamber body 12, the filter 40 is inserted into the chamber from the outlet 31 with the top 42 as the front end. Then, a tube (not shown) coated with solvent (adhesive) is pushed between the conical inner circumferential surface of the outlet tube 33 and the conical outer circumferential surface of the fixing part 43 to position the filter 40. During this positioning, the tube is bonded to the inner circumferential surface of the outlet tube 33 by the solvent. In this way, the tube seals the housing 30 and the filter 40 together.

[0068] Top 42 is the upper end of filter 40 and is formed in a generally dome shape (hemispherical). That is, the upper end of cylindrical portion 41, in other words, the end opening of chamber body 12 opposite to the lower end of outlet 31, is covered by top 42. Figures 7-9 In the example shown, although no opening is provided at the top 42, the present invention is not limited to this method and an opening can be provided at any location.

[0069] The cylindrical portion 41 extends around the outlet 31 of the chamber body 12 and in the direction of the central axis C1 of the chamber body 12. The cylindrical portion 41 includes a first rib 44, a second rib 45 extending in the direction of the central axis C1, and a blade 46 extending in the circumferential direction.

[0070] The blade 46 is an annular component extending circumferentially, and has multiple layers along the central axis of the cylindrical portion 41. For example, in Figure 7 , Figure 8 It has 32 layers of blades. Furthermore, in Figure 7 , Figure 8 In the example shown, 32 layers are used to ensure the resolution of the attached diagram, but it can also be configured with more layers. For example, blade 46 can have more than 10 layers, such as 40 layers of blade 46.

[0071] The first rib 44 is a skeleton component that extends from the lower end of the filter 40, i.e., the fixing part 43, to the upper end of the filter 40, i.e., the top 42. For example, four first ribs 44 are provided around the central axis of the cylindrical part 41 and at 90° intervals along the circumference.

[0072] The second rib 45 is a skeleton component that reinforces the first rib 44, and terminates before reaching the upper end of the filter 40, i.e., the top 42, from the lower end of the filter 40, i.e., the fixing part 43. For example, in Figure 7 In the example shown, the 28th layer, which is 87.5% (7 / 8) of the total number of layers (32) of blade 46 from the bottom, is connected to the upper end of the second rib 45. In other words, the opening 47 of the fourth layer, which is 12.5% ​​(1 / 8) of the total number of layers of blade 46 from the top, is widened.

[0073] For example, four second ribs 45 are provided circumferentially at 90° intervals around the central axis of the cylindrical portion 41, offset from the first rib 44 by 45°. In addition, for example, the upper ends of the four second ribs 45 are connected to the 28th layer of blades 46 from the bottom.

[0074] The first rib 44 and the second rib 45, which extend along the central axis of the cylindrical portion 41, intersect with the multi-layered blades 46, which extend circumferentially, thereby forming a multi-layered opening 47 on the cylindrical portion 41 of the filter 40 along the central axis C1 of the chamber body 12 (see reference). Figure 9 ).

[0075] The opening 47 is formed such that the central axial length of the cylindrical portion 41, i.e., the opening height H1, is less than the circumferential length, i.e., the opening width W1. That is, it is configured such that the distance between adjacent blades 46, 46 in the height direction is less than the distance between adjacent first rib 44, second rib 45 in the circumferential direction.

[0076] When the opening 47 is designed in this so-called horizontally elongated manner, the minimum diameter of solid matter in the blood that the filter 40 can capture depends on the opening height H1 of the opening 47. For example, the opening height H1 of the opening 47 is 0.2 mm or more and 0.4 mm or less, preferably 0.35 mm.

[0077] Reference Figure 9 In the filter 40 of this embodiment, the second rib 45 terminates before reaching the top 42. As a result, the circumferential width W2 of the upper opening 47 on the top 42 side of the opening 47 of the filter 40, specifically the opening 47 above the termination of the second rib 45, is formed to be larger than the circumferential width W1 of the lower opening 47 (W2>W1).

[0078] Specifically, in the region below where the second rib 45 extends, the circumferential width W1 of the opening 47 is defined by the interval between the first rib 44 and the second rib 45 adjacent to it in the circumferential direction. For example, it becomes an opening 47 with an opening angle of 45° relative to the central axis of the cylindrical portion 41.

[0079] In contrast, the circumferential width W2 of the opening 47 above the blade 46, which terminates at the second rib 45, is defined by the interval between adjacent first ribs 44, 44 in the circumferential direction. For example, it becomes an opening 47 with an opening angle of 90° based on the central axis of the cylindrical portion 41.

[0080] Thus, by employing a structure in which the circumferential width W2 of the upper opening 47 of the filter 40 is larger than the circumferential width W1 of the lower opening 47, the flow resistance of relatively low-velocity liquids (blood and saline) flowing into the upper opening 47 can be reduced, and stagnation can be prevented. In particular, by making the expansion direction of the opening 47 circumferential along the swirling flow direction, the flow resistance can be effectively reduced.

[0081] It should be noted that the openings 47 can also be formed by setting the total opening area A1 of multiple openings 47 with an opening width of W2 relative to the total area A of all openings 47 of the filter 40, with A1≥0.15A.

[0082] Figure 10 , Figure 11 Other examples of the filter 40 involved in this embodiment are shown (first other example and second other example). Figure 10 The first other example shown involves filter 40 that makes the termination position of the second rib 45 greater than... Figure 7 The example is further down. Specifically, at the end of the second rib 45, the upper end of the second rib 45 is connected to the 24th layer of blades 46 from the bottom, which is equivalent to 75% (3 / 4) of the total number of layers (32 layers). In other words, the opening 47 of the 8th layer, which is equivalent to 25% (1 / 4) of the total number of layers of blades 46 from the top, is widened.

[0083] in addition, Figure 11 The second other example shown involves a filter 40 that makes the termination position of the second rib 45 more than... Figure 10 The first other example is further down. Specifically, at the end of the second rib 45, the upper end of the second rib 45 is connected to the 16th layer of blades 46 counting from the bottom, which is equivalent to 50% (1 / 2) of the total number of layers (32 layers). In other words, the opening 47 of the 16th layer, which is equivalent to 50% of the total number of layers of blades 46 counting from the top, is widened.

[0084] In these first other examples and second other examples, the filters 40 also relate to... Figure 7 Similarly, the circumferential width of the upper opening 47 is increased compared to the circumferential width of the lower opening 47. Therefore, the flow resistance of liquid flowing above the filter 40 at a relatively low velocity through this widened opening 47 can be reduced.

[0085] use Figures 12-16 This embodiment explains the effect of the filter 40 in reducing flow resistance. First, Figure 12A filter 80 is illustrated as a comparative example. In this example, the second rib 45, like the first rib 44, extends from the lower end of the cylindrical portion 41 to the upper end, that is, from the fixing portion 43 to the top 42. In the filter 80 involved in this comparative example, the dimensions of all openings 47, including the circumferential width, are uniformly formed.

[0086] exist Figures 13-16 The fluid analysis results for the filter 40 according to this embodiment and the filter 80 according to the comparative example are shown in the diagram. Furthermore, during the fluid analysis, the total area of ​​the openings 47 of all filters was made equal. For example, the total area of ​​the openings 47 was set to 115 mm² for all filters.

[0087] also, Figure 13 The fluid analysis results for filter 80 involved in the comparative example are shown. Figure 14 Showing targets Figure 7 Fluid analysis results for filter 40 (upper layer 12.5% ​​widening) are shown. Figure 15 Showing targets Figure 10 Fluid analysis results of filter 40 (upper layer 25% widening) shown in (first other example). Figure 16 Showing targets Figure 11 Fluid analysis results for filter 40 (upper layer 50% widening) shown in (Second Other Example).

[0088] exist Figures 13-16 In all the analysis results, examples are shown of dividing the filter 40 and its surrounding area according to flow rate [m³ / s]. Here, the higher the flow rate, the smaller the spacing of the shaded lines. For further clarity, the area with the lowest flow rate is marked with a dashed shaded line.

[0089] Reference Figures 13-16 This means that the area with the lowest flow rate is located above filters 40 and 80. Therefore, from... Figures 13 to 16 It can be understood that as the number of layers in which the circumferential width of the opening 47 is widened increases, the area with the lowest flow rate becomes smaller. Thus, in this embodiment, in the region above the relatively low flow rate filter 40, by increasing the circumferential width of the opening 47 compared to the circumferential width of the opening 47 in the layer below it, the flow resistance is reduced, and as a result, liquid retention in the air trap chamber 10 can be suppressed.

[0090] <Another example of a filter>

[0091] Figure 17 This illustrates yet another example (a third other example) of the filter 40 involved in this embodiment. In this example, with Figure 7Similarly, the first rib 44 and the second rib 45 both extend along the central axis of the cylindrical portion 41, and multiple first ribs 44 and second ribs 45 are provided circumferentially. However, compared with... Figure 7 The difference is that both the first rib 44 and the second rib 45 extend from the lower end of the cylindrical portion 41 to the upper end. That is, the first rib 44 and the second rib 45 extend from the fixing portion 43 to the top 42. Moreover, the first rib 44 and the second rib 45 are formed into a gradually narrowing shape as the circumferential width narrows from the lower end (fixing portion 43) of the filter 40 toward the upper end (top 42).

[0092] By adopting such a gradually narrowing shape, the spacing between adjacent first ribs 44 and second ribs 45 widens as the flow progresses upwards. That is, the circumferential width of the opening 47 increases as the flow progresses upwards. According to this structure, in the upper region of the relatively low-flow filter 40, the circumferential width of the opening 47 is larger than the circumferential width of the opening 47 in its lower layer. Therefore, the flow resistance of liquid through this upper region can be reduced, and liquid retention within the air trap chamber 10 can be suppressed.

[0093] Explanation of reference numerals in the attached figures

[0094] 10 Air trap chamber, 12 Chamber body, 20 Cover, 21 Inlet tube, 22 Exhaust port, 23 Inlet port, 25 Cover body, 26 Inner circumferential surface of cover body, 30 Shell, 31 Outlet port, 33 Outlet tube, 40 Filter, 41 Cylindrical part, 42 Top, 43 Fixing part, 44 First rib, 45 Second rib, 46 Blade, 47 Opening, 50 Arterial side circuit, 51 Venous side circuit, 54 Blood purifier, 55 Dialysis device.

Claims

1. An air trap chamber comprising, a chamber body which is substantially cylindrical in shape, has an inlet pipe at one end in the direction of the central axis of the chamber body and an outlet at the other end, and in which liquid flows downward from the inlet pipe to the outlet, the inlet pipe is provided extending into the chamber body, and an inlet opening as an end portion of the inlet pipe is provided toward the inner circumferential surface of the chamber body in the circumferential direction, a filter covering the outlet is provided in the chamber body, the filter is formed with a cylindrical portion and a top portion, the cylindrical portion is provided extending around the outlet and in the direction of the central axis of the chamber body, the top portion covers the upper end of the cylindrical portion opposite the lower end of the outlet side of the chamber body, on the cylindrical portion of the filter, openings are formed in a plurality of layers in the direction of the central axis, the height of the openings being less than the circumferential length; the circumferential width of the openings of the upper layer on the top portion side of the filter is formed to be greater than the circumferential width of the openings of the lower layer on the outlet side; on the filter, a plurality of ribs extending in the direction of the central axis are provided along the circumferential direction, the plurality of ribs including first ribs and second ribs, both the first ribs and the second ribs extending from the lower end of the filter to the top portion; the ribs are formed with a circumferential width that narrows as it goes from the lower end of the filter toward the top portion of the filter, so that the spacing between adjacent first ribs and second ribs gradually widens as it goes upward.

2. An extracorporeal circulation circuit in which the air trap chamber of claim 1 is connected to the flow path of the extracorporeal circulation circuit that circulates blood drawn out.

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