BACKGROUND

[0001] Hollow fiber membranes are essential components of artificial lung systems. These hollow fiber mats are required for removing carbon dioxide or for adding oxygen to patient's blood via extracorporeal circulation. Hollow fibers are manufactured in various ways as seen in U.S. 2010/051180 Al, U.S. 4226378, and JP 8299763. The hollow fibers used to construct these mats are delicate. For example, the hollow fibers used in the Hemolung Cartiidge of the Hemolung Respiratory Assist System are composed of polypropylene and are approximately 300 microns in diameter and with a 30 micron wall thickness. Hollow fibers can also be coated with coatings such as siloxane. Problems arise when guiding the hollow fiber into a knitting machine. A variety of tools have been traditionally utilized to guide fibers and yarns into knitting machines. These tools in many cases utilize ceramic wear surfaces which are extremely hard and have low coefficients of fiiction. Metal guides as well as combination ceramic/metal guides have been utilized to insert the hollow fiber into the knitting machine. For example, one type of guide is essentially a tube through which the coated hollow fiber passes, The tube is mounted to an arm which moves back and forth to lay the hollow fiber into position. Despite using ceramic contact surfaces, the tube guide damages the siloxane coating on the hollow fibers. Microscopic analysis shows that siloxane coating had been scrapped off. Also the severe shaip exit angle of the tube caused flattening of the hollow fiber, A guide that utilizes dynamic fiiction and that keeps the hollow fiber aligned without bending as it is being fed into a knitting machine is necessary.

[0002]One attempt to solve the problem of causing damage to the hollow fiber is seen in JP 2008-196066A which describes a guide utilizing dynamic rollers for a Russell knitting machine. A hollow fiber passes through a complex tension apparatus eventually looping over a horizontal roller in a fixed position that feeds the hollow fiber in between the vertical rollers. These vertical rollers are set in parallel, are spaced apart, and are always in a fixed position. The hollow fiber then passes through a pair of closely set rollers that feed into a Russel knitting machine. These rollers move horizontally in the knitting machine via a conveyor belt mechanism. In the extreme horizontal positions the vertical rollers maintain horizontal alignment, but this design does not provide for front to back alignment roller guides. It also has the disadvantage of not providing for a plurality of top entry angles and therefore is not veiy adaptable to other systems. Another disadvantage is that any alteration in hollow fiber feeding process requires manual readjustment. Other yam guides for feeding knitting or spinning machines can be found in U.S. 6182475 Bl, U.S. 6016650, JP 2004-204400, and JP 6093543, but none of these singularly resolve the above discussed issues.

[0003] There is a need for a delicate fiber guide that utilizes dynamic friction and that provides for the horizontal and the front to back positioning of the delicate fiber, keeping it vertically aligned as it is being fed, for example into a knitting machine. There is also a need for a guide that allows for the delicate fiber to be fed from plurality of overhead angles.

SUMMARY

[0004] The present invention is a device for guiding delicate fibers used for making membranes, such as hollow fibers, in an atraumatic way. Damage is prevented by utilizing dynamic friction and by perfectly aligning the delicate fiber. One use for the guide is to feed hollow fibers into any suitable knitting machine, including for example, a rachel knitting machine. The guide comprises a bottom guide and a top guide connected in such a way that they move as singular unit, preferably utilizing a rod and clamp configuration, In a preferred embodiment, the bottom guide feeds directly into a knitting machine and the top guide receives the delicate fiber from a feeding mechanism. In a preferred embodiment, the bottom guide is comprised of a pah of pulley wheels attached to a bottom support. The top guide is comprised of a top support with at least two pahs of rollers vertically arranged in a perpendicular orientation relative to one another. The uppermost rollers align the delicate fiber in a side to side orientation and are spaced apart enough to allow the delicate fiber to be fed from a plurality of angles. The lowermost rollers are perpendicularly oriented relative to the uppermost rollers and align the delicate fiber in the front to back orientation. It is preferred that the lowermost rollers be narrowly spaced apart and it is most preferred that space be aligned over the bottom guide pulley wheels. It is most prefeixed that the top guide only has two pairs of top guide rollers arranged in the manner described above. All rollers and pulleys are smooth and made of lightweight material such as acetal copolymer or titanium. All rollers and pulleys should also be freely rotating. Preferably, the free rotation is enabled by precision ball bearing structures. This virtually eliminates static friction and prevents the coating on the delicate fibers from being scrapped or rubbed off. It is also prefeixed that the top and bottom supports are made of lightweight material such as aluminum or titanium.

[0005] Other features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate by way of example the features of the invention,

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is an isometric view of an embodiment of the guide.

[0007] Figure 2 is a front view of an embodiment of the guide moving on a knitting machine.

[0008] Figure 3a depicts a top guide of the present invention.

[0009] Figure 3b is a top view of an embodiment of the top guide.

[0010] Figure 3c is a bottom view of an embodiment of the top guide.

[0011 ] Figure 3d is a back view of an embodiment of the top guide.

[0012] Figure 4a is an exploded view of an embodiment of the guide.

[0013] Figure 4b is a side view of an embodiment of the guide outlining the internal notch in the top support.

[0014] Figure 5 shows an embodiment of the bottom support with an indentation for placement of the pulleys. [0015]Figure 6a illustrates an embodiment of the free rotation components of the uppermost rollers.

[0016] Figure 6b illustrates an embodiment of the free rotation components of pulleys.

DETAILED DESCRIPTION

[0017] Traditionally, several types of yarn guides have been used for guiding fibers. These yarn guides are not always suitable for delicate fibers such as hollow fibers. Hollow fibers can be damaged by bending them to the point that they are flattened, and in some cases by rubbing or scrapping off a coating. In accordance with the present invention, damage is prevented by utilizing dynamic friction in conjunction with aligning the fiber in the side to side and the front to back orientations. Additional advantages of the present invention include the capacity to feed the fiber from plurality of overhead entry angles and the capability of self- adjustment. In accordance with the present invention, at least two pairs of top guide rollers arranged vertically in perpendicular orientation to one another guide the fiber to be aligned with the bottom guide. Any suitable bottom guide is contemplated by the invention, Alignment is achieved by having uppermost rollers that align the fiber in a side to side orientation and that are spaced apart enough to allow the hollow fiber to be fed from a plurality of angles. The lowermost rollers are perpendicularly oriented relative to the uppermost rollers and align the fiber in the front to back orientation. It is preferred that the lowermost rollers be narrowly spaced apart and it is most preferred that they be aligned over a bottom guide that utilizes pulley wheels, It is most preferred that the top guide only has two pairs of top guide rollers arranged in the manner described above. This aiTangement in particular prevents the flattening and the scrapping of delicate hollow fibers while being fed into a knitting machine. Any suitable system in which it is necessary to guide delicate fiber for making a membrane is contemplated by the invention. To understand the invention, it is best to refer to the descriptions of the figures, which are for illustration purposes only. The present invention is not limited to the embodiments described in these figures. [0018] Figure 1 is an isometric view of the delicate fiber guide. Guide 1 is comprised of top guide 2 and bottom guide 3. Top guide 2 is comprised of a freely rotating uppermost pair of rollers 4 and a freely rotating lowermost pair of rollers 5, attached to a top support 6. Bottom guide 3 is comprised of pulleys 7 attached to a support 15. As delicate fiber 8 passes through rollers 4 and rollers 5 down through pulleys 7, it is vertically aligned.

[0019] Figure 2 shows a front view of guide 1 attached to bar 9 of a knitting machine (not shown) and is depict in two positions 10L andlOR. Delicate fiber 8 comes from feeder mechanism 11 (any suitable one is contemplated by invention), passes through and is vertically aligned by top guide 2 and is then fed by bottom guide 3 into the knitting machine to be laid down as the weft fiber in fiber mat 12. Bar 9 represents the horizontal moving component of a knitting machine and movement of bar 9 carries the guide 1 back and forth between the horizontal extreme positions of 10L and 10R. At position 10L, guide 1 has just finished laying down delicate fiber 8 in the light to left direction and is in position to begin laying down the delicate fiber in the left to right direction. As the guide moves from 10L to 10R as depicted by an arrow, the delicate fiber 8 at first passes over roller 4R in the 10L position, as guide 1 moves more central, delicate fiber 8 passes through gap 13 and finally as guide 1 moves into 1 OR position delicate fiber 8 passes over roller 4L. This design allows the feeder mechanism 11 to be fixed in a variety of overhead positions, while keeping delicate fiber 8 aligned horizontally. The size of gap 13 needs to be sufficiently wide to allow for multiple angle entry of delicate fiber 8, but restrictive enough to still allow for horizontal alignment. Delicate fiber 8 then passes through lowermost pair of rollers 5 which are oriented perpendicular to the uppermost rollers and preferably spaced apart the to be aligned with the pulley wheels 7 of bottom guide 3. Pulley wheels 7 are attached to bottom support 15 and are set close together in parallel and so that delicate fiber 8 passes through them essentially vertically and to be taken up by knitting machine and placed in fiber mat 12. Any top guide encompassing the uppermost and lowermost roller arrangement described above is contemplated by invention. For example a plurality of pahs of rollers can be placed in between the above described uppermost and lowermost rollers, or other types of guiding mechanisms can be placed in between them.

[0020] Though the invention contemplates any suitable top support design in a top guide that utilizes the roller arrangement described above, Figure 3 depicts several views of a preferred embodiment of a top guide. The top guide 20 depicted in figure 3a with top support 21 works well with rachel knitting machine, but can be utilized on any suitable machine. Figure 3b is top view of the top guide clearly showing the gap 22 between uppermost rollers 23. Figure 3c is a bottom view clearly showing the narrow gap 24 between lowermost rollers 25.

[0021] Though the invention contemplates any suitable means for connecting the top guide and bottom guide so that they move as one entity, Figure 4 shows a preferred embodiment of the rod/clamp style connecting means and the preferred top guide 20 that attaches to a bar in a rachel knitting machine. This design enables to the top guide to be set at a plurality of vertical angles. Figure 4a is exploded view depicting top support 21, clamp 32, rod 33 and bottom guide 34. Top support 21 contains top support circular notches 35. Clamp 32 with circular clamp notch 36 attaches to a top end 37 of rod 33 and bottom guide 34 attaches to a bottom end 38 of rod 33. Figure 4b shows side view of top guide 20 with internal notch 39 is outlined. Internal notch 39 in top support 21 is comprised of a diagonal supporting wall 40, opening 26 on top of top support 21 (figure 3a), opening 27 on bottom of top support 21 (figure 3b) and opening 28 on back of top support 21 (figure 3d). Clamp 32 and rod 33 are placed within internal notch 39. Clamp circular notch 36 matches up with top support circular notches 35 at a plurality of angles allowing top guide 20 to sit at a plurality of angles in relation to bottom guide 34 while still being able to align delicate fiber 41 in the horizontal and front to back directions.

[0022] Figure 5 depicts a preferred embodiment of bottom support 42. On the side where the pulleys 43 are attached there is an indentation 44. This allows for more precise vertical alignment of the delicate fiber to be fed into a knitting machine.

[0023] Rollers and pulleys are to be freely rotating allowing for only dynamic and not static friction. Preferred embodiments rollers and pulley wheels utilize precision ball bearings for free rotation. Most preferred are double-shielded bearings with an extended inner ring. Figure 6a depicts free rotation components of the top guide rollers. Cylinder 45 rotates around axel 46 using ball bearing 47. Figure 6b depicts the free rotation components of the pulley wheels. Pulley wheel 48 rotates around axle 49 utilizing ball bearing 50. It is preferred that pulley wheels be the smallest diameter so that it does not flatten the hollow fiber with at least a 20:1 ratio with the diameter of the hollow fiber.

[0024] The preferred material for all parts is to be as lightweight and as smooth as possible. It is preferred that the top guide rollers be made out of acetal copolymer. It is preferred that the pulley wheels are made of titanium. It is also preferred that the top and bottom supports be made out of aluminum or titanium or alloys thereof.

[0025] Though ideally the feeding and knitting of a hollow fiber should be a smooth and steady process, the constant movement can cause alterations. The atraumatic fiber guide design allows the hollow fiber alignment to be maintained, without having to stop and adjust. The atraumatic fiber guide described can be used with multiple machine designs that use overhead feeders.

[0026] The foregoing description merely illustrates the invention is not intended to be limiting. It will be apparent to those skilled in the art that various modifications can be made without departing from the inventive concept.

Accordingly it is not intended that the invention be limited except by the appended claims.