HK1088568B

HK1088568B - Blood filter device and method for producing the same

Info

Publication number: HK1088568B
Application number: HK06109071.7A
Authority: HK
Inventors: 河原畑茂树; 胜篦丰; 中尾彰多
Original assignee: 株式会社Jms
Priority date: 2003-03-24
Filing date: 2004-03-22
Publication date: 2010-02-19

Description

Blood filter device and method for manufacturing same

Technical Field

The present invention relates generally to a blood filtration device for filtering impurities, thrombus and the like in artificial cardiopulmonary circulation. More particularly, the present invention relates to a blood filtering device and a method of manufacturing the same, which are constructed such that air bubbles in a filter are easily removed.

Background

There is now an increasing trend to introduce blood filtration devices, such as arterial filters, for safety purposes in cardiopulmonary bypass for cardiac surgery including extracorporeal circulation. In order to ensure patient safety, there is a strong need for a blood filter constructed so as to be able to remove minute impurities in the artificial cardiopulmonary circulation, thrombus formed during surgery, or air that has entered or been released from the circulation, so as not to enter the patient.

The filter commonly used in blood filtration devices is a polyester mesh filter with about 20 to 40 μm pores, which is pleated to form a cylindrical shape. For example, japanese patent No.3270193 discloses a sheet-like filter element folded so as to have many pleats, and the pleated filter element is formed into a cylindrical shape in which pleats are radially arranged with apexes disposed on an outer circumferential side and valleys disposed on an inner circumferential side. The cylindrical filter thus formed is disposed in a cylindrical housing. As disclosed in japanese patent nos. 3012692 and 2000-60967A, in the above-structured filter, blood flows into the housing therethrough in the radial direction of the cylindrical filter assembly, which allows dirt, impurities, thrombus, etc. contained in the blood to be effectively removed.

In the above-described filter, blood first flows into the upper portion of the cylindrical filter member, flows through the cylindrical filter member in its radial direction through the outside of the filter member, and then flows out from the lower portion of the cylindrical filter member through the inside of the filter member. In this filter, the surface of the filter element extends vertically. This poses a problem in that air bubbles may remain in the filter during the priming operation when the priming solution flows onto the filter surface. Further, it is not easy to discharge the remaining bubbles. This is because, since the surface of the filter assembly is vertically extended, the air bubbles are not easily discharged from the filter, and thus it takes a long time to completely remove the air bubbles.

More precisely, the air bubbles trapped in the filter can be expelled by an external impact, for example caused by flicking the casing with a finger. In this case, however, although the air bubbles can be temporarily discharged by striking a portion near the position where the air bubbles are attached, the air bubbles are liable to adhere to the adjacent filter pleats again. Therefore, it is difficult to move the bubbles to the vent provided above.

Disclosure of Invention

In order to solve the above problems, it is an object of the present invention to provide a blood filtration device which can effectively remove substances such as impurities, thrombi, etc. in blood and also easily discharge air bubbles remaining in a filter.

The blood filtering device provided by the invention comprises: a housing including a dome-shaped portion forming an upper portion of the housing, a filter holding portion forming a middle portion of the housing, and a bottom portion forming a lower portion of the housing; an inlet provided at a side of the dome-shaped portion to allow blood to flow into the dome-shaped portion horizontally and along an inner wall of the dome-shaped portion; an exhaust port provided at the top of the dome-shaped portion; a filter for filtering impurities in blood, which is provided in the filter holding portion; and a blood outlet port at the bottom, the blood filtration device being configured to allow blood to flow from the inlet port into the dome-shaped portion, through the filter holding portion, and then out of the outlet port, wherein the filter is formed of a sheet-like filter element folded to have a plurality of pleats parallel to each other with a sealing surface connecting tips of the respective pleats being flat, so that the filter has a disk-like shape as a whole, and the filter is configured to partition a cavity of the housing into a cavity of the dome-shaped portion and a cavity of the bottom portion; the pleats are arranged along a chord direction of the filter holding portion; a plurality of support ribs are provided in the filter holding portion at positions corresponding to the end portions of the pleats, and the end portions of the pleats of the filter are inserted between the support ribs.

The invention also provides a method for manufacturing the blood filtering device with the structure. The method comprises the following steps: forming said filter by folding a sheet-like filter element so as to have a plurality of pleats parallel to each other, with a sealing surface connecting tips of said pleats being flat, so that the filter has a disk-like shape as a whole; disposing the filter in a cavity of the filter holding portion of the housing such that a flat sealing surface extends horizontally, the pleats being arranged in a direction chordally of the filter holding portion; a plurality of support ribs provided in a vertical direction at positions corresponding to end portions of the pleats on an inner side wall of the filter holding portion, the end portions of the pleats of the filter being inserted between the support ribs when the filter is disposed in the cavity of the filter holding portion; and filling a resin in a gap between an inner sidewall of the filter holding portion and an outer peripheral portion of the filter while applying a centrifugal force that is generated by rotating around a center of the filter holding portion and acts horizontally, and then hardening the resin, thereby fixing the filter to the inner sidewall of the filter holding portion with the resin.

Drawings

Fig. 1A is a front view, fig. 1B is a top view, and fig. 1C is a cross-sectional view of a blood filtration device according to an embodiment of the present invention.

Fig. 2 is a perspective view showing how blood flows into the top of the blood filtration device.

Fig. 3A is a perspective view showing a schematic structure of a filter holding portion of the blood filtration apparatus, and fig. 3B is a plan view thereof.

Fig. 4A is a schematic cross-sectional view of an upper half of a housing constituting the blood filtering apparatus, fig. 4B is a bottom view thereof, and fig. 4C is a cross-sectional view taken along line a-a in fig. 4B.

Fig. 5A is a top view and fig. 5B is a cross-sectional view of the lower half of the housing.

FIG. 6 is a perspective view, with portions broken away, of a method of making a blood filtration device according to one embodiment of the present invention.

Fig. 7 is a top view of a blood filtration device according to another configuration of an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

In the blood filtering device according to the present invention, the filter is formed of a sheet-like filter member folded to have a plurality of pleats, the closed surfaces thereof connecting the tips of the respective pleats are flat, which gives the filter a disk-like shape as a whole, and the filter is disposed in the blood filtering device so that the flat closed surfaces extend horizontally. With this structure, air bubbles remaining on the filter surface in the starting operation can be easily removed only by physically knocking the housing, because there is no obstruction both above and below the filter.

The blood filtration device described above may also be configured such that: a gap between the inner side wall of the filter holding portion and the outer peripheral portion of the filter is filled with resin to seal it, and the filter is fixed to the inner side wall of the filter holding portion with the resin. This not only allows the filter to be reliably fixed, but also allows the gap between the inner side wall of the filter holding portion and the outer peripheral portion of the filter to be reliably sealed.

It is preferable that the ratio h/r of the height h of the dome-shaped portion to the inner diameter r of the dome-shaped portion on the side of the filter holding portion is in the range of 0.26 to 1.06. Preferably, the ratio h/r ranges between 0.44 and 0.91. In addition, it is preferable that the ratio of the depth d of the bottom portion to the inner diameter r of the bottom portion on the side of the filter holding portion is in the range of 0.11 to 0.30.

Further, it is preferable that the inner diameter r of the dome-shaped portion on the side of the filter holding portion is 27 to 33mm, and the height h of the dome-shaped portion is 7 to 35 mm. With this structure, it is possible to ensure that a sufficient amount of bubbles are collected. More preferably the height h of the dome-shaped section is 12 to 30 mm. More preferably the depth d of the bottom is 3 to 10 mm. With this structure, it is possible to achieve an appropriate balance between the bubble removing performance and the amount of blood required to fill the blood filtering apparatus. Alternatively, the distance between adjacent pleats of the filter may be set to 1.6 to 3.7mm, and the height of each pleat may be set to 5 to 30 mm. This makes it easy to remove air bubbles after the starting operation.

The filter may be formed of only the filter assembly having a function of filtering foreign substances. The filter holding part can furthermore have a cylindrical cavity which is circular in horizontal cross section. Still further, the outer peripheral length of the inner space of the dome-shaped section decreases toward the tip of the dome-shaped section. It is preferred that the inner surface of the bottom is free of depressions or protrusions.

In the method of manufacturing a blood filtration device according to the present invention, canning is performed while applying a centrifugal force so that a gap between the inner side wall of the holding part inner cylinder and the outer peripheral part of the filter is sealed with resin. This simultaneously achieves many effects such as the filter pleats being able to adhere to each other, the filter pleats being supported by the filter holding portion, and the like. Therefore, according to the manufacturing method of the present invention, the blood filtration device can be manufactured by an extremely efficient manufacturing process.

In this manufacturing method, it is preferable that vertically extending support ribs are provided on the inner side wall of the filter holding portion at positions corresponding to the respective ends of the pleats, and when the filter is disposed in the cavity of the filter holding portion, the ends of the pleats are respectively inserted into the support ribs so that the filter is temporarily supported by the inner side wall of the filter holding portion.

Further, it is preferable for the case to be formed to have an upper half and a lower half which are required to be connected to each other so that a connection point between the upper half and the lower half of the case is provided in the filter holding portion of the case, the filter is provided on one portion of the upper half or the lower half corresponding to the cavity of the filter holding portion, and the other of the upper half and the lower half is connected to the upper half or the lower half on which the filter is provided, after which sealing and hardening treatment of the resin is performed.

A blood filtration device according to the present invention will be described below with reference to the embodiments of the accompanying drawings.

Fig. 1A is a front view, fig. 1B is a top view, and fig. 1C is a cross-sectional view of the blood filtration device. For example, reference numeral 1 denotes a resin-made case. The housing 1 comprises a dome-shaped portion 2 forming the upper part of the housing, a filter holding portion 3 forming the middle part of the housing, and a bottom portion 4 forming the lower part of the housing. The housing 1 has a circular horizontal cross-section.

An inlet 5 is provided at the side of the dome-shaped part 2 in order to allow blood to flow into the dome-shaped part 2 horizontally and along the inner wall of the dome-shaped part 2. At the top of the dome-shaped part 2 an air outlet 6 is arranged for discharging air, e.g. air bubbles. The bottom 4 is provided with a blood outlet 7. The liquid flowing into the dome-shaped portion 2 from the inlet 5 passes through the filter holding portion 3 and then flows out from the outlet 7. The bottom 4 also has a support portion 4a which is used when the filter device is mounted and is not related to the filtering function.

The dome-shaped section 2 is formed such that its inner diameter decreases toward the top of the dome-shaped section 2. This makes it easy to discharge air bubbles remaining in the blood so that the discharged air bubbles move upward along the inner peripheral surface of the dome-shaped section 2. Further, since the dome-shaped section 2 has a circular horizontal cross section and has the inlet 5 so that blood flows horizontally along the inner wall of the dome-shaped section 2 into the dome-shaped section 2, the blood flowing from the inlet 5 into the dome-shaped section 2 flows along the inner peripheral surface of the dome-shaped section 2 and thus forms a swirling flow as shown by the solid line in fig. 2. The blood flow that becomes a swirling flow gradually slows down. Therefore, as shown by the broken line portion in fig. 2, a portion of the blood whose flow velocity is reduced flows downward, so that the blood gradually flows into the filter holding portion 3. The shape of the dome-shaped portion 2 is not limited to the shape shown in fig. 1A and the like, as long as the dome-shaped portion 2 is formed such that the outer diameter thereof decreases toward the exhaust port 6. For example, the dome-shaped portion 2 may be conical or funnel-shaped.

The filter holding portion 3 has a cylindrical outer shape. As shown in fig. 1C, a filter 8 for filtering impurities remaining in the blood is provided in the filter holding portion 3. As shown in fig. 3A and 3B, the filter 8 is formed by a filter assembly formed by folding a sheet-like screen material so as to have a plurality of pleats 8a whose closed surfaces connecting the tips of the respective pleats 8a are flat, so that the filter 8 as a whole has a disk-like shape. The filter 8 divides the cavity of the housing 1 into a dome-shaped part 2 and two sides of the bottom 4. The respective pleats 8a are arranged in parallel in the direction of the chord of the filter holding portion 3. In fig. 3B, the thick solid line indicates the peak of the wrinkle 8a, and the thin solid line indicates the valley of the wrinkle 8 a. It is to be noted here that although the filter holding portion 3 is shown as a separate cylindrical component in fig. 3A and 3B for the purpose of simple illustration, the filter holding portion 3 is actually formed integrally with the dome-shaped portion 2 or the bottom portion 4.

In the case where the filter 8 is provided in the manner shown in fig. 3A and 3B, a gap between the inner side wall of the filter holding portion 3 and the outer peripheral portion of the filter 8 is filled with a sealing resin 9 to seal it, the sealing resin 9 is composed of, for example, a polyurethane resin, and the filter 8 is fixed to the inner side wall of the filter holding portion 3 by the sealing resin 9. By providing the filter 8 in the above-described manner, as shown in fig. 2, the blood having a reduced velocity flowing into the filter holding portion 3 can flow through the filter 8 without leakage. As a result, only filtered blood flows into the bottom 4.

Furthermore, air bubbles remaining in the filter 8 when the priming solution flows through the filter 8 in the priming operation can be easily discharged from the vent 6 at the top of the dome-shaped section 2 or from the outlet 7 of the bottom section 4 by a vertical tap of the filter 8 from the outside, such as by tapping the bottom section 4 with a finger. More precisely, since the filter 8 is not blocked above and below, the air bubbles exiting from the filter 8 do not adhere to the rest of the filter 8 again, which ensures that the air bubbles can reach the air outlet 6 at the top of the dome-shaped section 2 or reach the outlet 7 on the bottom 4 and exit therefrom.

In addition, in the filter device according to this embodiment, the closed surface connecting the tips of the respective pleats is flat, so that the filter 8 as a whole has a disk-like shape, and due to this structure, the following effect can be obtained. That is, since the filter 8 itself can well maintain its shape, it is possible to form the filter 8 by using only a mesh material as a filter member. In contrast, the conventional structure must use a support net together with the mesh material to maintain the shape of the filter 8. When the filter 8 is formed of only a mesh material without using a support net, air bubbles can be easily removed and pressure loss of blood flow can be reduced.

The bottom 4 provides a reserved space below the filter 8. In practical applications, this allows to reduce the pressure loss of the blood flow through the filter device to a negligible level. The inner surface of the bottom 4 is smooth and free of protrusions or indentations. This allows the blood flowing through the filter holding portion 3 to be guided to the outlet 7 without hindrance. Therefore, formation of substances such as thrombus in the blood flowing through the filter holding portion 3 can be prevented.

When the outlet 7 is provided at the bottommost portion of the bottom portion 4 as shown in fig. 1A, a portion blocking the blood flow is less likely to be formed. Further, as shown in fig. 1B, the outlet 7 may be formed such that it includes a portion extending toward the center of the bottom 4. Alternatively, the outlet 7 may be formed to include a portion extending in a lateral direction of the bottom 4.

As the filter member, it is possible to use a similar material such as a mesh material, a woven or non-woven fabric, or a combination of two or more materials. The filter assembly may be made of polyester, polypropylene, polyamide, fluorocarbon fibers, stainless steel, and the like.

The horizontal cross-section of the housing 1, and in particular of the dome-shaped part 2, is preferably circular, since it is necessary to induce a swirling flow of blood. It is noted here, however, that other shapes, such as oval, can produce the same effect as described above. In the present embodiment, the inner diameter r (see fig. 1C) of the dome-shaped portion 2 on the filter holding portion 3 side is equal to the inner diameter of the sealing resin 9 and the bottom portion 4 on the filter holding portion 3 side, so the inner surface of the housing 1 has no step portion at the edge thereof.

In addition to the above effects, the blood filtering device according to the present embodiment has another advantage in that it can be made smaller than a conventional blood filtering device, while maintaining a satisfactory filtering function in practical use. However, to achieve this, it is necessary to set parameters according to the cavity shape of the housing 1 and the shape of the filter 8 as described below. The parameters that need to be set are as follows: the inner diameter r of the dome section 2, the height h of the dome section 2, and the depth d of the bottom section 4, all shown in FIG. 1C, and the ratio h/r of the height h of the dome section 2 to the inner diameter r of the dome section and the ratio d/r of the depth d of the bottom section 4 to the inner diameter r of the dome section 2.

First, the ratio h/r is preferably in the range of 0.26 to 1.06. If the ratio h/r is less than 0.26, the angle between the inner wall surface of the dome-shaped section 2 and the horizontal plane is too small to sufficiently remove bubbles. On the other hand, if the ratio h/r is larger than 1.06, the amount of liquid required to fill the dome-shaped portion 2 is too large. More preferably, the ratio h/r is in the range of 0.44 to 0.91.

The ratio d/r is preferably in the range of 0.11 to 0.30. If the ratio d/r is less than 0.11, the angle between the inner wall surface of the bottom part 4 and the horizontal plane is too small to remove the bubbles sufficiently. On the other hand, if the ratio d/r is greater than 0.30, the amount of liquid required to fill the bottom 4 is too large.

Further, the inner diameter r of the dome-shaped section 2 may be set to 27 to 33mm and the height h of the dome-shaped section 2 may be set to 7 to 35mm from the viewpoint of the amount of collection of bubbles. By setting the inner diameter r and the height h of the dome-shaped section 2 within these ranges, it is possible to achieve a bubble collection amount of at least 5mL at a blood flow rate of 1.5L/min, as required in practical applications. It is more preferable to set the height h within 12 to 30 mm. It should be noted here that the "bubble collection amount" is defined herein as the amount of bubbles to be trapped and accumulated in the dome-shaped section 2 filtered out by the filter 8 when the liquid for measuring the amount is supplied to the filter device. The method of measuring the bubble collection amount will be described below. The advantageous effects of the bubble collection amount obtained by setting the parameters described above will be described below.

First, as a prerequisite for setting the above parameters, an ideal filtration membrane will be described. The blood filter widely used for infants needs to have a maximum blood flow rate of 1.5L/min in practical applications. In order to limit the pressure loss at this blood flow rate to a negligible level in practical applications, the total area of the perforations in the mesh material used as the filter element needs to be sufficient 8cm2 or more.

On the other hand, the screen material generally has a uniform size of pores sufficient for 20 to 40 μm, and its desired porosity is 16 to 28%. When the porosity is less than 16%, the pressure loss of the blood fluid is too large. On the other hand, when the porosity is more than 28%, the screen material cannot remove impurities, thrombi, etc. of 40 μm or more, which is a filtering function required in practical use. In order to allow a total aperture area of 8cm as mentioned above in the screen material sufficient to satisfy the above porosity range²Or larger, the area of the screen material, i.e. the filter membrane, needs to be 29cm²To 50cm²Within the range. These values are multiplied by a safety factor of 1.5 to account for variations in the operating conditions of the filter device. Therefore, the area of the screen material (filtration membrane) needs to be 44cm²To 75cm²Within the range of (1).

When the filtration membrane area is decreased within the above range, the parameters that allow the filtration apparatus of the present embodiment to obtain a satisfactory bubble collection amount in practical use are experimentally examined. As a result of experiments to determine the inner diameter r and the height h of the dome-shaped part 2 which allow the filter device to collect 5mL or more of air bubbles at a blood flow rate of 1.5L/min, we found that, as described above, the inner diameter r should be between 27 and 33mm and the height h should be between 7 and 20 mm.

The amount of trapped bubbles was measured in the following manner. As a liquid for measuring the amount of air bubbles collected, citrated bovine blood (37 ℃, Ht.: 35%, T.P.: 6g/dL) was supplied to the filtration device shown in FIG. 1. Ht. denotes the hematocrit and T.P. denotes the total amount of protein in the plasma. The bubbles were added to the liquid at an addition rate of 2mL/min before supplying the liquid to the filtration apparatus. While detecting the presence of bubbles in the liquid flowing out of the outlet 7, the liquid is continuously supplied to the filter device until bubbles of 40 μm or more are detected. At the moment when the bubbles are detected to be 40 μm or more, the total amount of bubbles (volume under atmospheric pressure) accumulated in the dome-shaped section 2 is also detected, and the thus obtained measurement value is regarded as the amount of bubbles collected. When the area of the filtration membrane and the inner diameter r and the height h of the dome-shaped section 2 satisfy the above-described ranges, the volume of the filtration apparatus of the present embodiment can be reduced to about half of the volume of the conventional filtration apparatus.

Considering that, in addition to the parameters described above, the depth d of the bottom 4 needs to be in the range 3 to 10mm in terms of the quantity of blood required to fill the hemofiltration device. The reason for this is as follows: first, in order to easily discharge air bubbles in the blood flowing from the outlet 7 of the bottom portion 4 into the filter device, the depth d thereof needs to be at least 3 mm. In addition, when treating infants, the depth needs to be no greater than 10mm in order for the amount of blood required to fill the hemofiltration device to not exceed the required 15 mL.

Further, as parameters regarding the pleats of the filter 8, the pitch of two adjacent pleats and the height of each pleat are set within a specific range to easily remove air bubbles. It is desirable to have a spacing between two adjacent pleats of 1.6 to 3.7mm and a height of each pleat of 5 to 30 mm. When the distance between two adjacent pleats is less than 1.6mm, air bubbles are not easily removed. On the other hand, when the distance between two adjacent pleats is greater than 3.7mm, it is difficult to obtain a sufficient area of the filtration membrane. When the height of each pleat is less than 5mm, it is difficult to obtain a filter membrane of sufficient area. On the other hand, when the height of each pleat is greater than 30mm, the volume of the filter-holding portion 3 is also increased accordingly, which may result in an increase in the amount of blood required to fill the hemofiltration device.

Next, a method of manufacturing the filter device according to the present embodiment will be described with reference to fig. 4A to 4C, fig. 5A, 5B, and fig. 6. Fig. 4A is a cross-sectional view showing the upper half 1a of the housing constituting the blood filtering apparatus, fig. 4B is a bottom view thereof, and fig. 4C is a cross-sectional view taken along line a-a in fig. 4B. Fig. 5A is a cross-sectional view of the lower case half 1B, and fig. 5B is a top view thereof. Note here that only fig. 4C shows the filter 8 and the sealing resin 9.

These drawings show substantially the same structure as described above, but the support ribs 10 that temporarily support the filter 8 are also shown in these drawings (see fig. 4A to 4C). In the upper half 1a and the lower half 1b of the housing, a holding-portion inner cylinder 3a and a holding-portion outer cylinder 3b for constituting the filter holding portion 3, respectively, are formed. The upper half portion 1a and the lower half portion 1b are joined together by fitting the holding-portion inner cylinder 3a into the holding-portion outer cylinder 3b, thereby obtaining a single-element housing.

As shown in fig. 4A to 4C, the upper half 1a has a support rib 10 therein. The support ribs 10 are provided on the inner peripheral wall of the holding portion inner cylinder 3a by forming grooves in portions of the inner peripheral wall corresponding to the ends of the respective pleats 8a of the filter 8. The grooves formed by the support ribs 10 have a depth corresponding to the height of the support ribs 10.

In the holding portion inner cylinder 3a of the upper half 1a, a pair of notches 11a are also formed. In the holding-portion outer cylinder 3b of the lower half 1b, through-holes 11b are formed at positions corresponding to a pair of notches 11a formed in the holding-portion inner cylinder 3 a. When the upper half portion 1a is fitted into the lower half portion 1b, the notch 11a communicates with the through hole 11b, thereby forming a hole passing through the peripheral wall of the holding-portion inner cylinder 3a and the peripheral wall of the holding-portion outer cylinder 3 b. The reason for providing these holes will be explained below.

In the manufacture of the blood filtration device, the upper half 1a and the lower half 1b of the housing and the filter 8 are first formed in the manner described above. Next, as shown in fig. 4C, the filter 8 is disposed in the cavity of the holding portion inner cylinder 3a of the housing upper half 1a so that the flat sealing surface extends horizontally. At this time, the end of each pleat of the filter 8 is inserted between the two support ribs 10, so that the filter 8 is temporarily supported by the inner side wall of the holding-portion inner cylinder 3 a.

Thereafter, the upper half 1a and the lower half 1b are joined together by fitting the holding-portion inner cylinder 3a into the holding-portion outer cylinder 3b, whereby the single-element housing 1 is obtained.

Next, as shown in fig. 6, the housing 1 in which the filter 8 is disposed is set in the rotating jig 12. The rotating jig 12 has a cavity 12a, and the cavity 12a has a predetermined shape for supporting the housing 1. When the rotary jig 12 rotates, the housing 1 rotates together with the rotary jig 12. In the upper half of the rotary jig 12, there is a resin reservoir 13 containing a sealing resin such as a polyurethane resin, and a resin supply tank 14 extends from the resin reservoir 13 to the side of the holding portion outer cylinder 3 b. The sealing resin supplied to the side surface of the holding portion outer cylinder 3B enters the cavity of the holding portion inner cylinder 3B through the notch 11a and the through hole 11B (see fig. 4A to 4C and fig. 5A and 5B).

When the rotary jig 12 rotates, the filter device is controlled by a centrifugal force generated by horizontal rotation and movement around the center of the filter holding portion 3 a. The result is that the sealing resin overflows from the resin reservoir 13 to be supplied into the holding-portion inner cylinder 3a through the resin supply groove 14, so that the space between the inner side wall of the holding-portion inner cylinder 3a and the outer peripheral portion of the filter 8 is filled with the resin. The filter 8 may be fixed to the inner side wall of the holding-portion inner cylinder 3a by the sealing resin 9 by hardening the resin filling the gap, as shown in fig. 1C.

When potting is carried out while applying centrifugal force so that the gap between the inner side wall of the holding portion inner cylinder 3a and the outer peripheral portion of the filter 8 is filled with resin, the following six effects can be obtained simultaneously:

(1) maintaining the pleated shape of the filter 8;

(2) the pleats of the filter 8 are supported by the filter holding portion 3;

(3) the support ribs 10 are embedded in the resin;

(4) the upper half 1a and the lower half 1b of the case are combined with each other;

(5) the gap between the inner side wall of the filter holding portion 3 and the outer peripheral portion of the filter 8 is sealed; and

(6) the flow-through passage is allowed to have a cross section such that there is no step at the boundary between the filter holding portion 3 and the dome-shaped portion 2 or at the boundary between the filter holding portion 3 and the bottom portion 4.

Therefore, this manufacturing method can manufacture the filter device in extremely simple steps, and thus can effectively reduce the manufacturing cost. In addition, the effect described in (3) contributes to improvement of the bubble removal performance. Also, by the effect described in (6), the inner wall surface of the housing can be smoothed, which contributes to prevention of thrombus formation and to improvement of the bubble removal performance.

It should be noted here that, in the above-described manufacturing step, it is not always necessary to provide the support ribs 10 to allow the filter 8 to be temporarily supported by the inner side walls of the holding portion inner cylinder. Other structures also enable the filter 8 to be temporarily supported by the inner side wall of the holding portion inner cylinder 3 a.

In addition, the method of folding the filter 8 is not limited to the method shown in fig. 3A and 3B, in which the pleats 8a are arranged in parallel in the direction of the chord of the filter holding portion 3, but may be folded as shown in fig. 7. More specifically, in the filter 15 shown in fig. 7, the pleats 15a are arranged so as to extend radially from the center of the filter holding portion 3. Even if the pleats 12a are configured as described above, the same effects as described above can be obtained.

Although the filter 8 is folded to have a plurality of pleats, the present invention is not limited thereto. For example, the filter shown in fig. 3A and 3B or fig. 7 may be formed by folding the filter element into a corrugated form having peaks and valleys.

Industrial applications

According to the blood filtering device of the present invention, foreign substances, thrombi, etc. in blood can be reliably removed, and air bubbles adhering to the surface of the filter can be easily removed by physical impact caused by knocking the housing from the upper or lower portion of the housing.

Claims

1. A blood filtration device comprising:

a housing including a dome-shaped portion forming an upper portion of the housing, a filter holding portion forming a middle portion of the housing, and a bottom portion forming a lower portion of the housing;

an inlet provided at a side of the dome-shaped portion to allow blood to flow into the dome-shaped portion horizontally and along an inner wall of the dome-shaped portion;

an exhaust port provided at the top of the dome-shaped portion;

a filter for filtering impurities in blood, which is provided in the filter holding portion; and

a blood outlet located at the bottom,

the blood filtration device is configured to allow blood to flow from the inlet into the dome-shaped portion, through the filter retaining portion, and out the outlet,

wherein said filter is formed of a sheet-like filter element folded to have a plurality of pleats parallel to each other with a sealing surface connecting top ends of the respective pleats being flat, so that the filter has a disk-like shape as a whole, and the filter is disposed to partition a cavity of said housing into a cavity of said dome-shaped portion and a cavity of said bottom portion;

the pleats are arranged along a chord direction of the filter holding portion;

a plurality of support ribs are provided in the filter holding portion at positions corresponding to the end portions of the pleats, and the end portions of the pleats of the filter are inserted between the support ribs.

2. A blood filtering device according to claim 1, wherein a space between an inner side wall of the filter holding portion and the filter peripheral portion is filled with a resin to be sealed, and the filter is fixed to the inner side wall of the filter holding portion by the resin.

3. A blood filtering device according to claim 1 or 2, wherein a ratio h/r of a height h of the dome-shaped portion on the side of the filter holding portion to an inner diameter r of the dome-shaped portion is in the range of 0.26 to 1.06.

4. A blood filtration device according to claim 3, wherein the ratio h/r is in the range of 0.44 to 0.91.

5. A blood filtering device according to claim 1 or 2, wherein a ratio d/r between a depth d of the bottom portion on the side of the filter holding portion and an inner diameter r of the bottom portion is in a range of 0.11 to 0.30.

6. A blood filtering device according to claim 1 or 2, wherein the inner diameter r of the domed portion on the side of the filter holding portion is 27 to 33mm, and the height h of the domed portion is 7 to 35 mm.

7. A blood filtration device according to claim 6, wherein the height h of the dome-shaped portion is 12 to 30 mm.

8. A blood filtration device according to claim 6, wherein the depth d of the bottom is 3 to 10 mm.

9. A blood filtration device according to claim 6, wherein the distance between adjacent pleats of the filter is 1.6 to 3.7mm and the height of each pleat is 5 to 30 mm.

10. The blood filtering device according to claim 1 or 2, wherein the filter is constituted only by a filter assembly having a function of filtering foreign substances.

11. A blood filtering device according to claim 1, wherein the filter holding portion has a cylindrical cavity whose cross section in the horizontal direction is circular.

12. A blood filtration device according to claim 1, wherein the outer circumference of the inner space of the dome decreases toward the top of the dome.

13. A blood filtration device according to claim 1, wherein the bottom portion is free of depressions and protrusions on an inner surface thereof.

14. A method for manufacturing a blood filtering device,

the blood filtering device includes:

an exhaust port provided at the top of the dome-shaped portion;

a blood outlet located at the bottom,

a blood filtration device configured to allow blood to flow from said inlet into said dome-shaped portion, through said filter retaining portion, and out said outlet;

the method comprises the following steps:

forming said filter by folding a sheet-like filter element so as to have a plurality of pleats parallel to each other, with a sealing surface connecting tips of said pleats being flat, so that the filter has a disk-like shape as a whole;

disposing the filter in a cavity of the filter holding portion of the housing such that a flat sealing surface extends horizontally, the pleats being arranged in a direction chordally of the filter holding portion;

a plurality of support ribs provided in a vertical direction at positions corresponding to end portions of the pleats on an inner side wall of the filter holding portion, the end portions of the pleats of the filter being inserted between the support ribs when the filter is disposed in the cavity of the filter holding portion; and

the filter is fixed to the inner side wall of the filter holding portion by filling a space between the inner side wall of the filter holding portion and the outer peripheral portion of the filter with a resin while applying a centrifugal force that is generated by rotating around the center of the filter holding portion and acts horizontally, and then hardening the resin.

15. The method of claim 14, wherein, to form the housing, an upper half and a lower half are provided, which need to be connected to each other such that the connection point between the upper half and the lower half is located inside the filter support portion,

the filter is placed in a portion of one of the upper half and the lower half corresponding to the cavity of the filter holding portion, and the other of the upper half and the lower half is connected to the upper half or the lower half where the filter holding portion is located, and then,

sealing with a resin and hardening it.