ROLLER CLAMP

Abstract

A roller clamp (1) is provided for regulating the flow of a fluid through an elastically deformable pipe (T), comprising a generally channel-shaped body (2) whose lower wall (4) has a clamping surface (6a, 6b) with a longitudinal groove (7) having a cross-section that decreases in size from an initial end (7a) to a terminal end (7b). The longitudinal groove (7) is distributed asymmetrically with respect to the side walls (5a, 5b) of the body (2).

Description

ROLLER CLAMP FIELD OF INVENTION The present invention relates to roller clamps in particular used in the medical industry to regulate the flow of a fluid through an elastically deformable pipe, for example in infusion / transfusion equipment. More particularly, the invention relates to a roller clamp of the type comprising a generally channel-shaped body having two side walls and a bottom wall defining a clamping surface along at least part of which a longitudinal groove is formed having an initial end and a terminal end. The longitudinal groove has a cross-section that decreases from the initial end to the terminal end, and a roller is rotatably supported by the side walls of the body and can be moved longitudinally in a guided manner along a body substantially parallel to the clamping surface of the bottom wall to progressively restrict, in use, an elastically deformable pipe inserted through the body between the bottom wall of the body and the roller. STATE OF THE ART Roller clamps of the type defined above are known, for example, from documents US 5014962 and US 6129330, in the name of the applicant in question, in which the longitudinal groove formed along the clamping surface of the clamp body has - in cross section - a generally V-shaped or isosceles triangle shape, that is, with oblique side walls diverging from the bottom wall. By using roller clamps made in this way, the flow of a fluid through the elastically deformable pipe is regulated by varying ίΠ / ZZΖηZ / E / YΙΛΙ - 2. Progressively adjust the longitudinal position of the roller along the clamping surface of the lower wall of the body. The minimum flow or zero flow condition corresponds to placing the roller at the terminal end of the longitudinal groove formed along the clamping surface of the lower wall, while the maximum flow condition corresponds to placing the roller at the initial end of the longitudinal groove.Clearly, this is due to the fact that the cross-section of the pipe, clamped and compressed between the roller and the clamping surface portions of the lower body wall, between the longitudinal groove median and the body's side walls, defines a narrow passage or lumen for the fluid. The width of this passage depends on the depth of the longitudinal groove median: the smaller the cross-section of the longitudinal groove median, the smaller the cross-section of the lumen, and vice versa. In other words, the roller positions move progressively toward the terminal end of the longitudinal groove, corresponding to a progressively tighter clamping of the pipe and, consequently, a progressively greater elastic deformation of the pipe. In the roller clamps described in the documents mentioned above, the longitudinal groove extends along a median of the body area, which is centrally located with respect to the clamping surface. Therefore, the lumen of the flexible pipe being clamped—in use—is distributed across the central area of ​​the flexible pipe, that is, between two lateral sections of equal length. The clamping force applied to this section may not be completely uniform, potentially causing some unwanted partial throughflow, albeit to a limited degree. This can result in a limitation of the precision of the flow regulation achieved by the roller clamp. ίΠ / ZZΖηZ / E / YΙΛΙ - 3 US patents 3918675 and 4869721 propose placing the longitudinal groove asymmetrically with respect to the side walls of the body, in an attempt to make the operation of the clamp more precise thanks to more controlled clamping of the pipe inserted—in use—through the body. In both of these prior art solutions, the groove has a U-shaped cross-section that is orthogonal to the bottom wall, in relation to the side walls. Even these solutions have not proven to be more efficient in terms of accuracy in regulating flow through the pipe. SUMMARY OF THE INVENTION The objective of the present invention is to provide a roller clamp of the type specified above that is capable of ensuring a better controlled and more precise, and therefore more efficient, operation. According to the invention, this objective is achieved by the features defined primarily in claim 1 and, secondarily, in the dependent claims. The clamping surface of the clamp body is therefore asymmetrical, consisting of a larger portion along one side of the longitudinal groove (the one furthest from the respective side wall of the body) and a smaller portion along the other side of the longitudinal groove (the one closest to the respective side wall of the body). During operation, the clamping of the tubing by the roller thus occurs asymmetrically, unlike conventional roller clamps, in that a larger portion of the flexible tubing (corresponding to the larger clamping surface) is more completely and securely compressed due to its greater length, while the lumen for the flow of the medical fluid is formed in the other portion. - 4 The remaining portion has a smaller extension of the flexible pipe, thus providing significantly improved regulation accuracy. This accuracy is achieved through the unique and distinct shape of the connection transitions between the longitudinal groove and the clamping surface. One transition (the one with the larger bend radius) facilitates the sliding deformation of the flexible pipe wall, while the other (the one with the smaller bend radius) facilitates complete closure when the pipe is compressed. BRIEF DESCRIPTION OF THE FIGURES The additional features and advantages of the invention will be further detailed from the description that follows, with reference to an embodiment shown in the attached figures, which are provided only as a non-limiting example, where: Figure 1 is a schematic front perspective view of a roller clamp for medical use, which constitutes a modality of the present invention; Figure 2 is a rear perspective view of the roller clamp body; Figure 3 is a side elevation view of the roller clamp body; Figure 4 is a top plan view of the roller clamp body; Figure 5 is a bottom plan view of the roller clamp body; Figure 6 is a front elevation view of the roller clamp body. - 5 Figure 7 is a front view of the roller clamp body, Figures 8, 9 and 10 are cross-sectional views, respectively, according to lines DD, CC and BB of Figure 3, and Figure 11 is a cross-sectional view at a larger scale of line AA of Figure 3 in which the roller or clamp and flexible pipe are also shown. DETAILED DESCRIPTION OF THE INVENTION With reference to the figures, indicated by number 2 is the body of a roller clamp according to the invention, which is shown in its entirety by number 1 in figure 11 and designed particularly for use in the medical field to regulate the flow of an infusion fluid, a transfusion fluid or the like through the elastically deformable tubing, indicated by the letter T in figure 11. In addition to body 2, clamp 1 includes a roller or wheel indicated by number 3 in figure 11, both conveniently made of molded plastic material. Body 2 has a general channel-like shape with a lower wall 4 and two side walls indicated respectively by 5a and 5b. A lower tubular appendage 11, whose function is known, projects from the lower wall 4. The inner face of the lower wall 4, that is, the face facing the inner part of the body 2, has a generally flat surface which will be referred to below as the clamping surface of the roller clamp 1. Along most of this clamping surface, a longitudinal groove 7 is formed which identifies, along the body 2 of the clamp 1, a flow regulation region and divides the clamping surface into two longitudinal portions of clamping surface ίη / ZZΖΠZ / E / YΙΛΙ - 6 indicated with 6a and 6b, one adjacent respectively to the side wall 5a and the other to the side wall 5b. The longitudinal groove 7 formed along the clamping surface of the clamp body 2 has - in cross section - a generally V-shaped or isosceles triangle shape, that is, with the side walls 7h, 7k oblique and diverging from the lower wall 7j of the same. The longitudinal groove 7 extends not centrally, but asymmetrically along the body 2: more specifically, it is closer to the side wall 5b and therefore further from the side wall 5a. As a result, the portion of clamping surface 6a adjacent to the side wall 5a is wider than the portion of clamping surface 6b adjacent to the side wall 5b. The longitudinal slot 7 has an initial end 7a and a terminal end 7b, and its cross-section decreases in size from the initial end 7a to the terminal end 7b. As mentioned, this cross-section of the slot 7 is substantially in the shape of an isosceles trapezoid with a smaller base, which defines the lower wall 7j of the slot, distributed over the bottom, and a larger open base facing upwards. The longitudinal edges of the longitudinal groove 7 are connected to the clamping surface portions 6a, 6b via respective curved edges 7c, 7d. More precisely, these curved edges 7c, 7d are convex and have different radii of curvature: the radius of curvature of the curved surface 7c, which connects the side wall 7h to portion 6a of the adjusting surface, is larger, for example, on the order of 0.3 mm, compared to the radius of curvature of the curved surface 7d, which connects the side wall 7k to portion 6b of the iΠ / ZZΖηZ / E / YILI - 7 regulation surface. The radius of curvature of the curved surface 7d is, for example, on the order of 0.05 mm: therefore, basically this surface 7d has an almost sharp shape. The initial end 7a of the longitudinal groove 7 is conventionally formed frontally with centering bevels 7e, 7f to facilitate the insertion of the flexible pipe T into the body 2 of the clamp 1. The two clamping surface portions 6a, 6b have ribs 8, that is, thin grooves which extend longitudinally to one side of the longitudinal groove 7 and are conveniently distributed in an asymmetrical and differentiated manner, as best seen in Figure 4. Throughout the flow control region, the upper side walls 5a, 5b have respective inner grooves 9 which extend substantially parallel to the clamping surface portions 6a, 6b. The two grooves 9 define respective longitudinal guides in which two axial pins 10 (Figure 11) protrude on opposite sides of the roller 3 and are coupled in a freely rotatable and sliding manner. Roller 3 is therefore longitudinally sliding and rotatable along the guides 9 which, together with the longitudinal groove median 7 and the clamping surface portions 6a, 6b, delimit the flow control region mentioned above. When using the elastically deformable T-tube, normally made of thermoplastic material, it is inserted into the body 2 through its front end corresponding to the initial end 7a of the groove 7, between the clamping surface portions 6a, 6b and the roller 3. The roller 3 can be positioned before the initial end 7a of the longitudinal groove 7, in the area shown in iP / ZZΖ / E / YILI - 8 In Figure 7, the pipe T is basically undeformed, and therefore no flow regulation of the liquid occurs within it. In order to regulate the flow, the roller 3 must move to the initial end 7a and thus move towards the terminal end 7b of the longitudinal groove 7, progressively in the areas shown in Figures 8 to 11. Therefore, the pipe T is progressively elastically deformed until a substantially flat condition is obtained between the roller 3 and the clamping surface portions 6a, 6b, for example, in the condition shown in Figure 11 in which the narrow passage of the lumen P, whose width is directly proportional to the size of the cross-section of the longitudinal groove 7, remains open.In other words, the size of the lumen P, and therefore the flow rate of the liquid through the pipe T, is larger because the roller 3 is positioned at and near the initial end 7a of the median of the longitudinal groove 7, and it progressively decreases as the roller 3 approaches the terminal end 7b. If the roller 3 is moved further beyond the terminal end 7b of the longitudinal groove 7, the pipe T is compressed to a completely flattened condition, and therefore the flow of liquid is interrupted. The presence of the ribs 8 along the clamping surface portions 6a, 6b advantageously prevents the pipe T from moving laterally during the elastic deformation of the pipe carried out by moving the roller 3, also ensuring a more stable fit. Due to the fact that, according to the distinctive feature of the invention, the asymmetrically distributed groove 7 has the generally V-shaped cross-section mentioned above and is connected to the regulating surface 6a, 6b through the curved surfaces 7c, 7d with different curvatures, the pipe T is compressed by the roller 3 against the clamping surface portions 6a, 6b evenly and in an asymmetrical and differentiated manner, as exemplified in the figure - 9 11. Therefore, the predominant portion of the pipe, that is, the portion with the greatest extinction, corresponding to the clamping surface portion 6a, is securely and reliably clamped and closed completely, while the lumen P is located in the smaller portion of pipe T, corresponding to the clamping surface portion 6b. During the elastic deformation of pipe T, the portion corresponding to the larger curved connection surface 7c is easily compressed by sliding over the regulating surface portion 6a, while the portion corresponding to the smaller curved connection surface 7d bends and is restricted against the regulating surface portion 6b. This allows for significantly improved flow control through pipe T. Obviously, the construction details and modalities may vary widely from what has been described and illustrated, without thereby departing from the scope of protection of the invention as defined in the following claims.

Claims

1. A roller clamp for regulating fluid flow through an elastically deformable pipe, comprising a generally channel-shaped body having two side walls and a bottom wall defining a clamping surface along at least part of which a longitudinal groove is formed having a bottom wall, side walls, an initial end and an end and having a cross-section that decreases in size from the initial end to the end, and a roller rotatably supported by the side walls of the body and longitudinally movable in a guided manner within the body substantially parallel to the clamping surface to clamp, in use, an elastically deformable pipe inserted through the body between the bottom wall and the roller, wherein the longitudinal groove is distributed asymmetrically with respect to the side walls of the body,characterized in that the side walls of the longitudinal groove are - in a self-known manner - diverging obliquely from the lower wall, and wherein the longitudinal groove is connected to the clamping surface through curved edges having different radii of curvature, the radii of curvature of the curved surface distributed over the side of the longitudinal groove that is closer to the side wall of the body are smaller than the radius of curvature of the curved surface distributed over the side of the longitudinal groove that is farther from the other side wall of the body.

2. The roller clamp according to claim 1, characterized in that the clamping surface has ribs extending longitudinally to one side of the longitudinal groove.

3. The roller clamp according to claim 2, - 11, characterized in that the ribs are asymmetrical.

4. The roller clamp according to one or more of the preceding claims, characterized in that the initial end of the longitudinal groove is formed with centering bevels for inserting the flexible pipe into 5 the body of the clamp.

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