GB1583016A

GB1583016A - Fluid separation element

Info

Publication number: GB1583016A
Application number: GB41759/78A
Authority: GB
Original assignee: Baxter Travenol Laboratories Inc
Current assignee: Baxter International Inc
Priority date: 1976-02-13
Filing date: 1977-02-08
Publication date: 1981-01-21
Also published as: DK57477A; IL51345A; NL7701446A; SE7701542L; JPS52101674A; CH612893A5; AU2216877A; ES467473A1; NO770433L; IL51345A0; FR2340892B1; DE2705811A1; IT1104570B; CA1063575A; ES455887A1; FR2340892A1; ES467472A1

Description

(54) FLUID SEPARATION ELEMENT (71) We, BAXTER TRAVENOL LABORATORIES INC., a Corporation organised and existing under the laws of the State of Delaware, United States of America, of One Baxter Parkway, Deerfield, Illinois 60015, United States of America, do hereby declare the invention for which we pray that a Patent may be granted to us and the method by which it is to be performed to be particularly described in and by the followin statement: his invention relates to a fluid separation element in the form of a bundle of hollow filaments (or fibres) for use in a dialyzer.

The present invention provides a fluid separation element for a diffusion device comprising an elongate bundle of hollow, semipermeable filaments, free of direct mechanical attachment to each other, each of said filaments extending lengthwise of the bundle for the entire length of the bundle said filaments being positioned in the bundle so as to define an angle to the longitudinal axis of said filament bundle, said filaments being positioned in crossing, overlying relation with adjoining filaments, and said filaments defining a first set of generally parallel filaments defining a first angular relation to said longitudinal axis, and a second set of generally parallel filaments defining an opposite angular relation to said longitudinal axis, when compared with said first set, and being positioned in the following relationship: a first filament of the first set being overlaid by a first filament of the second set, which first filament of the second set is, in turn, overlaid by a second filament of the second sets is, in turn, overlaid by a second filament of the first set, which second filament of the first set is, in turn overlaid by a second filament of the second set, such relationship continuing throughout the majority of the filaments of the first and second sets to define an interleaving relationship.

Reference is now made to the accompanying drawings, wherein: Figure 1 is a perspective view of one side of a winding machine for making a fluid separation tenement according to the inven tion; Figure 2 is a diagrammatic and perspective view of a drive system of the machine for a take-up reel and filament guide thereof; Figure 3 is a perspective view, partially in section, showing a two-cam system for controlling the movement of the filament guides on each side of the machine; Figure 3A shows an alternative single cam system for controlling the guides; Figure 4 is an enlarged perspective view showing a filament guide assembly; Figure 5 is a side elevational view showing the take-up reel; Figure 6 is a sectional view taken substantially along line 6-6 of Figure 5 and showing a hub-and-locking mechanism for the takeup reel; Figure 7 is a greatly enlarged elevational view showing a portion of the take-up reel; Figure 8 is a view taken substantially along line 8-8 of Figure 7 and showing the filament crossover; Figure 9 is a perspective view showing a split sleeve for use in bundling the filament for cutting into the fibres; and Figure 10 is an end view of the split sleeve with one side opened.

Referring now to Figure 1, the winding machine 10 includes a body 12 on each side of which is provided a winding mechanism.

The body includes a boxlike main section 14 which is supported by a pair of legs 16 and 18. A control console and supply spool mounting section 20 is supported in a cantilever fashion from the back end of the main body section 14.

Two substantially identical winding mechanisms are provided, one on each side of the body. Thus, two winding operations can be performed simultaneously, if desired.

Each winding mechanism includes upper and lower spool support shafts 22 and 24, which extend laterally from the mounting section 20. Two filament supply spools 26 and 28, each having wound thereon a continuous hollow filament, are mounted on the shafts 22 and 24. The filaments 30 and 32 extend from the spools through the filament guide assembly 34 and to the driven take-up reel assembly 36. A protective and transparent case, such as 38, having two access doors 38a and 38b is carried by the main body section so as to enclose the guide assembly and take-up reel.

Drive System The rotation of the take-up reel assembly 36 and movement of the filament guide assembly 34 are controlled by a drive system, which is enclosed with the main body section 14. The system includes an electric motor 40, (Figure 2) which drives both the reel assembly and the guide assembly. The motor speed can be varied between 0-2000 rpm.

The Reel Drive. The motor 40 is connected to the take-up reel through a gear and timing belt system as described hereinafter. The motor 40 is connected to a 5:1, worm-gear-type speed reducer 42 having an output gear 44. A geared output drive timing belt 46 is trained about the gear 44, as well as the driven ear 48, which is mounted on the cross-shaft 50. A counter, take-off gear 52 is mounted on the crossshaft 50 and is connected to a rpm counter 54 by a counter timing belt 56. The gearing system is arranged such that the counter is synchronized with the take-up reel assembly so as to indicate the take-up reel rpm.

A reel drive gear 58 is also mounted to the shaft 50 and is connected to a reel drive shaft 60 by a gear 62 on the shaft 60 and a timing belt 64. The take-up reel assembly 36 is mounted to an end of the shaft 60. Thus the take-up reel is driven: by the motor 40; through the gear reducer 42; through the gear 44, belt 46 and gear 48; through shaft 50; through gear 58, belt 64 and gear 62; and through shaft 60. Through this system the take-up reel can be driven at between 0-400 rpm.

The Guide Drive. The guide assembly 34 is mounted so as to cause the filament to reciprocate or move laterally with respect to the take-up reel assembly 36 at a rate related to the rotation of the take-up reel.

The motor 40 drives the guide assembly. A variable speed control 64 is mounted to the motor 40. The speed control includes a manual speed adjuster 65 and an output gear 66. The speed of the output gear 66 is controllable between 0-400 rpm. A drive timing belt 68 is trained about the output gear 66 and a smaller driven gear 70. For each revolution of the output gear 66, the driven gear 70 revolves 2.25 times, so as to provide a 2.25:1 gear ratio. The driven gear 70 is secured to one end of a shaft 72, which enters a gear box 74. A second aligned shaft 76 exits the gear box and a gear 78 is secured to the outer end of the shaft 76. A rotatable cam drive shaft 80 extends upwardly from the gear box and is driven by the shaft 72. A bevel gear arrangement (not shown) is provided within the gear box for driving the shafts 76 and 80.

Another timing belt 82 is trained about the gear 78 and a gear 84 for driving a second rotatable cam drive shaft 86 and a counter 88, through a gear box arrangement 89, which is similar to that previously described in connection with the gear box 74. The counter 88 is synchronized with the rotation of the shafts g0 and 86, which, in turn, is related to the rate of reciprocation of the guide arm, so that the counter indicates the rate of guide arm reciprocation or oscillation.

Referring now to Figure 3, each of the shafts 80 and 86 carry at their upper end a cam, such as 90 and 92, which controls the reciprocation of the guide assembly 34 and the filaments. A reciprocating control rod 94 extends from within the body 14 through a sidewall 14a and connects at its outer end to the guide assembly 34. At the inner end, the rod 94 includes a cam follower 96, which is biased against the cam 90 by a coiled compression spring 98 that bears against a bearing plate 100 and the cam follower 96.

Rotation of the cam 90 causes the rod 94 to reciprocate. It will be appreciated that the guide arm on the other side of the machine (not shown) is controlled in a similar manner.

With this arrangement the rate of reciprocation of the guide arm can be controlled between 0-900 oscillations per minute.

In the alternative cam construction shown in Figure 3A, there is a single grooved cam 102. Here there is only one drive shaft 80a which drives the single cam, which, in turn, controls the two control rods 93a and 94a.

It will be appreciated that the speed of the cam drive shaft 80 relative to the take-up reel drive shaft 60 can be controlled and adjusted with the speed control adjuster 65.

If no adjustment is made, the ratio of guide arm reciprocation to take-up reel rotation remains constant regardless of the speed of the take-up reel. However, use of the adjuster 65 permits adjustment and control of the ratio of guide arm reciprocation to take-up reel rotation.

Guide Arm Assembly The guide arm assembly 34 is mounted to the outside of sidewall 14a by a vertically adjustable mounting plate 101, a pivotally adjustable side plate 102 and a forwardly and rearwardly adjustable lateral support plate 104. An upper filament sensing switch 106 is mounted to the top side of the plate 104 and a lower filament sensing switch 108 is supported by and is positioned below the plate 104. Each switch includes leaf-like member, such as 110, which is biased toward the filament and which engages and senses the presence of the filament, such as 30. In the event the filament breaks during winding, the member 110 moves upwardly and actuates means (not shown) for disabling the drive system and for applying a controlled braking action to the supply spool shafts and the take-up reel to minimize breakage of filaments on other reels.

An elongated and swingable guide arm 112 is pivotally mounted at its back end to the support plate 104, forwardly of the switch 106, by a pin 114. The control rod 94 is connected to the arm at a point intermediate the ends of the arm by a universaltype joint 116. The head 112a at the forward end of the guide arm carries upper and lower spring-like filament guides, such as 118, which cooperates with the spring-like filament guides, such as 119, associated with the switches. As the control rod reciprocates, the head 11 2a swings back and forth in a manner controlled by the cam 90.

The Take- Up Reel Assembly The take-up reel assembly 36, as shown in Figures 5 and 6, includes a filament winding plate 120 and a hub-and-locking system 122 for removably securing the plate to the machine.

The Winding Plate. The plate 120 has a large, circular and centrally positioned opening which defines the inner edge 124, and has six support edge carrying sect ions 126, 128, 130, 132, 134 and 13 . Each of the sections are positioned radially outwardly from the center of the plate and equally about the periphery.

A V-shaped filament support assembly, such as 136, is mounted on the plate at each of the support sections, such as 126. Each of the support assemblies, such as 136, includes a pair of outwardly extending U-shaped filament supports 138 and 140, each of which terminates in a lower beveled edge, such as 138a and 140a. Each of the supports, such as 138 and 140, is bolted to the plate through bolt-receiving apertures in the plate 120. As can be seen in Figure 5, the filament support assemblies can be movably positioned in one of three different radial positions. Thus the supports 138 and 140 can be moved from the inner position as shown to an intermediate position at 142 and 144, or to an outer position at 146 and 148.

It will be appreciated that such changes in position can increase or decrease the length of the filament bundles between the sets of supports. For example, by moving the supports radially outwardly, the length of the bundles between the adjacent supports is lengthened. This permits the manufacture of hollow fiber dialyzers of different lengths.

The Hub-and-Locking System. The system 122 for securing the plate 120 to the machine is shown in both Figures 5 and 6.

That system includes a hub assembly 150, which is secured to an end of the winding shaft 60 by a set screw 151. The hub assembly includes a flanged, boss-like member 152 to which a wheel-like support plate 154 is secured. The support plate includes three radial spokes 156, 158 and 160, each of which has an elongated guide slot, such as 162. The outer periphery of the plate is L-shaped in section and defines an axial or laterally-extending shoulder 164 and a circumferential shoulder 166.

The take-up reel winding plate 120 is constructed such that the inner edge 124 can be fitted onto the shoulder 164 with the plate against the circumferential shoulder 166.

This fit prevents radial movement of the reel plate 120 relative to the hub 150. The plate 120 is removably secured in driving relation to the hub assembly by six studs, such as 167a, which extend outwardly from the shoulder 166 and which engage six studreceiving apertures, such as 167b, in the winding plate.

Three generally radially-extending locking arms 168, 170 and 172 are provided to secure the winding plate 120 to the support plate 154 by preventing axial movement of the winding plate with respect to the support plate shoulder 166. The arms are secured at their inner ends to the hub 150 by a pin, such as 174, and a pivotable collar-like member 176. Each arm carries a guide block, such as 178, which moves radially within the slot 162 in the arm. The guide block 178 is secured to the arm and in the slot by a pin 180. Each of the locking arms is of a length such that when the arms are in the extended, radial and locking position, the outer end of the arm is positioned radially outwardly over the shoulder 164 and in overlying relationship to the plate 120. With this construction the arm can lock and hold the take-up plate on the winding machine in fixed relation to the shaft 60.

The collar 176 is pivotable with respect to the shaft 60 and to the support arms, such as 160. As can be seen in Figure 5, a stop pin 182 defines the limits of movement for the collar 176. The collar is held in the locked position by a spring-loaded detent assembly (not shown). In the position shown in Figure 5, in full line, the arms are positioned to lock the plate in position. Pivoting of the collar 176 causes the arms to retract and the guide members, such as 178, slide within the slots 162, until the outer ends of the arms move within the inner edge of the shoulder 164.

With the locking arms retracted, the take-up plate 120 can be removed from the machine by pulling it axially outwardly.

Operation 0 the Winding Machine As can be seen from the drawings, the two spools of hollow filaments are mounted on the shafts 22 and 24 and each filament is guided through the guide assembly 34 and started on the take-up reel 36. The machine is actuated so that the motor rotates the take-up reel assembly 36. As this occurs, the take-up reel draws filament from the supply reel through the guide assembly. The action of the cams, such as 90, causes the guide arm 112 to oscillate or move laterally, inwardly and outwardly as the take-up reel rotates. The cam is designed in a manner such as to provide an even distribution of the filament on the guides. The shape of the cam cooperates in preventing build-up of filament at the edges of the guide by increasing the arm speed at each end of the oscillation. Furthermore, the cam prevents closepacking of the filament windings and causes the filament which is being wound to crossover the previous winding of the filament.

This crossover is diagrammatically shown in Figure 8 where it can be seen that an upper filament winding 190 crosses over a lower filament winding 192.

It has also been found that the use of the two reels is beneficial from the point of view that a sufficient quantity of filament is supplied so as to continuously feed the take-up reel and thereby avoid the need to stop the winding operation and start a second spool.

This stopping has been found to be detrimental to the efficiency of the dialyzer since undesirablv large flow channels may be formed where one spool ended and the other began. It is believed that the channel may be formed as a result of differences in filament tension at the end of the first spool and at the beginning of the second spool.

During winding it has been found to be desirable to rotate the take-up reel at a speed greater than the speed at which the guide arm oscillates. In one particular operation the take-up reel is driven at 200 rpm and the guide arm is oscillated at 160 oscillations (i.e. 320 traverses) per minute.

It will be appreciated that as the geometry of the take-up reel, for example the size and diameter of the take-up reel, changes that the oscillations of the guide arm must also change in order to effectuate proper crossover.

Once the filaments are wound on the take-up reel and the bundles are of a sufficient size for use in hollow fiber dialyzers, the winding operation is stopped.

Preparation of fiber Bundles An elongated split case 200 as shown in Figure 9 is used in forming the fiber bundles from the filaments and for removing the bundles from the take-up reel. The split case includes an upper semi-cylindrical member 202 and a lower cylindrical member 204, which are joined by a pair of flexible hinges 206 and 208. As can be seen in Figure 10, the sections can be opened and positioned and clamped about the wound bundles of the filament.

Referring now to Figure 7, once the members are in position, they tightly grasp the bundles of filament therebetween and the filament may then be cut at either end of the case so as to form open-ended filament lengths and permit removal of the bundles from the reel. The cutting converts the continuous filament to the individual hollow filaments used in the dialyzer. After cutting and removal, the individual bundles are then treated and formed into the hollow filament dialyzers.

The filaments are semi-permeable and free of direct mechanical attachment to each other in the bundle. As is apparent from Figure 8, each of the filaments extends lengthwise of the bundle for the entire length of the bundle at an angle to the longitudinal axis of the bundle. The filaments 190 form a first set of parallel filaments and the filaments 192 form a second set of parallel. The filaments of the first set are positioned in crossing, overlying relation with the filaments of the second set and define an opposite angular relation to the longitudinal axis when compared with the filaments of the second set. As is clear from Figure 8, a first filament 190a of the first set is overlaid by a first filament 192a of the second set, which filament 192a is, in turn, overlaid by a second filament 190b of the first set, which filament 190b is, in turn, overlaid by a second filament 192b of the second set. Such relationship continues throughout the majority of the filaments of the first and second sets to define an interleaving relationship.

Production of a fluid separation element using the method described above is described in co-pending patent application no. 53982/77 (serial no. 1 583 015).

WHAT WE CLAIM IS: 1. A fluid separation element for a diffusion device comprising an elongate bundle of hollow, semi-permeable filaments, free of direct mechanical attachment to each other, each of said filaments extending lengthwise of the bundle for the entire length of the bundle, said filaments being positioned in the bundle so as to define an angle to the longitudinal axis of said filament bundle, said filaments being positioned in crossing, overlying relation with adjoining filaments, said filaments defining a first set of generally parallel filaments defining a first angular relation to said longitudinal axis, and a second set of generally parallel filaments defining an opposite angular relation to said longitudinal axis, when compared with said first set, and being positioned in the following relationship: a first filament of the first set being overlaid by a first filament of the second set, which first filament of the second set is, in turn, overlaid by a second filament of the first set, which second filament of the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. started on the take-up reel 36. The machine is actuated so that the motor rotates the take-up reel assembly 36. As this occurs, the take-up reel draws filament from the supply reel through the guide assembly. The action of the cams, such as 90, causes the guide arm 112 to oscillate or move laterally, inwardly and outwardly as the take-up reel rotates. The cam is designed in a manner such as to provide an even distribution of the filament on the guides. The shape of the cam cooperates in preventing build-up of filament at the edges of the guide by increasing the arm speed at each end of the oscillation. Furthermore, the cam prevents closepacking of the filament windings and causes the filament which is being wound to crossover the previous winding of the filament. This crossover is diagrammatically shown in Figure 8 where it can be seen that an upper filament winding 190 crosses over a lower filament winding 192. It has also been found that the use of the two reels is beneficial from the point of view that a sufficient quantity of filament is supplied so as to continuously feed the take-up reel and thereby avoid the need to stop the winding operation and start a second spool. This stopping has been found to be detrimental to the efficiency of the dialyzer since undesirablv large flow channels may be formed where one spool ended and the other began. It is believed that the channel may be formed as a result of differences in filament tension at the end of the first spool and at the beginning of the second spool. During winding it has been found to be desirable to rotate the take-up reel at a speed greater than the speed at which the guide arm oscillates. In one particular operation the take-up reel is driven at 200 rpm and the guide arm is oscillated at 160 oscillations (i.e. 320 traverses) per minute. It will be appreciated that as the geometry of the take-up reel, for example the size and diameter of the take-up reel, changes that the oscillations of the guide arm must also change in order to effectuate proper crossover. Once the filaments are wound on the take-up reel and the bundles are of a sufficient size for use in hollow fiber dialyzers, the winding operation is stopped. Preparation of fiber Bundles An elongated split case 200 as shown in Figure 9 is used in forming the fiber bundles from the filaments and for removing the bundles from the take-up reel. The split case includes an upper semi-cylindrical member 202 and a lower cylindrical member 204, which are joined by a pair of flexible hinges 206 and 208. As can be seen in Figure 10, the sections can be opened and positioned and clamped about the wound bundles of the filament. Referring now to Figure 7, once the members are in position, they tightly grasp the bundles of filament therebetween and the filament may then be cut at either end of the case so as to form open-ended filament lengths and permit removal of the bundles from the reel. The cutting converts the continuous filament to the individual hollow filaments used in the dialyzer. After cutting and removal, the individual bundles are then treated and formed into the hollow filament dialyzers. The filaments are semi-permeable and free of direct mechanical attachment to each other in the bundle. As is apparent from Figure 8, each of the filaments extends lengthwise of the bundle for the entire length of the bundle at an angle to the longitudinal axis of the bundle. The filaments 190 form a first set of parallel filaments and the filaments 192 form a second set of parallel. The filaments of the first set are positioned in crossing, overlying relation with the filaments of the second set and define an opposite angular relation to the longitudinal axis when compared with the filaments of the second set. As is clear from Figure 8, a first filament 190a of the first set is overlaid by a first filament 192a of the second set, which filament 192a is, in turn, overlaid by a second filament 190b of the first set, which filament 190b is, in turn, overlaid by a second filament 192b of the second set. Such relationship continues throughout the majority of the filaments of the first and second sets to define an interleaving relationship. Production of a fluid separation element using the method described above is described in co-pending patent application no. 53982/77 (serial no. 1 583 015). WHAT WE CLAIM IS:

1. A fluid separation element for a diffusion device comprising an elongate bundle of hollow, semi-permeable filaments, free of direct mechanical attachment to each other, each of said filaments extending lengthwise of the bundle for the entire length of the bundle, said filaments being positioned in the bundle so as to define an angle to the longitudinal axis of said filament bundle, said filaments being positioned in crossing, overlying relation with adjoining filaments, said filaments defining a first set of generally parallel filaments defining a first angular relation to said longitudinal axis, and a second set of generally parallel filaments defining an opposite angular relation to said longitudinal axis, when compared with said first set, and being positioned in the following relationship: a first filament of the first set being overlaid by a first filament of the second set, which first filament of the second set is, in turn, overlaid by a second filament of the first set, which second filament of the

first set is, in turn overlaid by a second filament of the second set, such relationship continuing throughout the majority of the filaments of the first and second sets to define an interleaving relationship.

2. A fluid separation element according to claim 1, wherein the bundle is enclosed within an elongate split cylindrical case to clamp and retain the bundle along its length.

3. A dialyzer incorporating a fluid separation element according to claim 1 or 2.