DE29623452U1 - Bendable tube - Google Patents

Description

Applicant: Richard Wolf GmbH
Pforzheimer Strasse 32
75438 Knittlingen

Must not be changed

Bendable tube

The invention relates to a bendable tube, in particular as a shaft for a flexible endoscope.

State-of-the-art fiberscopes have a highly flexible, freely deflectable section at the distal end in order to be able to visually inspect selected tissue areas in a body cavity or the like and/or to treat them using additional auxiliary instruments.

Furthermore, shafts with a flexible section are known for cutting or milling instruments that are effective inside the body in minimally invasive surgery. With the latter, a high level of force transmission should be possible despite the cutting head being angled to the side, since the material to be processed, e.g. bone substance, can be hard and tough under certain circumstances.

The endoscope shaft known from DE-GM 69 38 905 consists of a flexible section of a large number of ring members arranged axially next to one another and connected to one another by an articulated joint. During production, the articulated joints must

between the individual ring sections. Another flexible endoscope shaft known from DE-PS 17 66 209 has cylinder sections loosely arranged on four control wires, ie they do not engage with one another in a form-fitting manner.
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Another flexible endoscope tube arrangement known from DE-PS 18 16 973 consists of tube sections arranged one behind the other, which engage with one another by means of projections and recesses without positive locking, but can be detached from one another.

Finally, DE-OS 24 47 510 discloses a flexible endoscope shaft which has a cylindrical mesh on the outside of which a large number of mutually engaging deflection elements are arranged. Each deflection element has a projection at one end and a recess at the other end.

The disadvantage of all the known flexible shafts mentioned above is that their construction is relatively complex and can only be manufactured in combination with other parts for the intended use.

These well-known, flexible endoscope shafts therefore also have the significant disadvantage that their production is complex and expensive due to their structural design. The production of these well-known, flexible endoscope shafts also has the disadvantage that a large number of individual components must be manufactured and stored.

In an endoscope shaft known from US-PS 51 52 744 and having a flexible section, the elastic deformability of the otherwise rigid shaft is achieved by means of recesses arranged alternately in the wall, which are designed in such a way that the individual sections are materially connected to one another via webs of a certain width. However, there is the

Danger that excessive bending of the flexible section may cause one or more connecting bars to break.

The object of the present invention is to create a bendable tube, in particular as a shaft for a flexible endoscope, which on the one hand avoids the disadvantages of the prior art discussed at the beginning and on the other hand allows simple and therefore economical production. Furthermore, additional means for fixing individual tube sections should be eliminated in order to be able to use the remaining free space within the tube as completely as possible for other channels, optical devices, mechanical devices and the like.

The device-related part of the above task is solved in that the pipe, where it is to be designed to be bendable, is made up of at least two pipe sections that are materially separated from one another by a circumferential separating joint, but are connected to one another in a form-fitting manner at least in the direction of the longitudinal axis of the pipe. The course of the separating joint is chosen in such a way that adjacent pipe sections are materially separated from one another, but are connected to one another in a form-fitting manner.

The bendable pipe according to the invention can be designed to be bent in practically any way depending on the arrangement and design of the joint. The positive connection between adjacent pipe sections ensures that torsional, tensile and bending forces can be reliably absorbed, so that with an appropriate design of the joint, as claimed by way of example in the subclaims and described in the following description, bendable pipes can be used for almost any purpose. With an appropriate design of the positive locking elements, it is possible to enable bending in just one or also in several planes. The bending can also be made possible by rotating the pipe itself.

However, a bendable tube constructed according to the principle of the invention can be used not only as a shaft for a flexible endoscope, but also for numerous other applications. In the field of endoscope technology, such a tube can be used, for example, as a trocar sleeve, which is rigid during the actual piercing process due to the trocar located therein and only becomes flexible after the trocar is removed. Furthermore, such a tube can be used as a reinforcement for a flexible hose on the outside or inside, it can serve as a cardan replacement or can also be designed as a high-frequency electrode. Such a tube can also be used as a chain, namely as a hollow chain. It can also be used as a stent, e.g. as a vascular support, as an esophageal or tracheal support. The flexible tube part formed by tube sections that can be bent relative to one another can be formed by a large number of identical tube sections that engage with one another, which will be particularly advantageous in terms of manufacturing technology and storage. However, different pipe sections can also be combined with one another, not only in terms of the axial length, but also in terms of the design of the form-fitting elements.

According to the invention, a bendable pipe section has at least one nose pointing towards the adjacent pipe section, which engages in a form-fitting manner in a corresponding recess in the adjacent pipe section. To form a flexible pipe, several such bendable pipe sections are required. These pipe sections, which are adjacent to two pipe sections, have at least one nose on one side and a corresponding recess on the other side, as seen in the axial direction of the pipe.

The aforementioned design of a pipe section with at least one nose represents the structural lower limit with regard to the number of noses. In terms of stability and flexibility, it will generally be more advantageous to provide each pipe section with two or more noses that engage in corresponding recesses in the adjacent pipe section. The noses are preferably designed in such a way that

arranged in such a way that a recess is formed between adjacent lugs, into which a lug of the adjacent pipe section can engage. In this way, an intimate interlocking of adjacent pipe sections is achieved in a structurally simple manner. The shape of the individual lugs and corresponding recesses depends on their function. At least one mushroom-shaped lug will have to be provided in order to reliably ensure a positive connection with the adjacent pipe section through a corresponding recess in which this lug lies. The flexibility of the pipe can be determined on the one hand by the shape of the lug and on the other hand by the width of the parting line. In order to enable targeted bending, it is expedient to provide the mushroom-shaped lug with an outer contour that is at least partially circular.

In order to increase the torsional strength of such a pipe and to allow bending, for example, only in one plane, it is advisable to provide one or more rectangular noses in addition to the aforementioned mushroom-shaped noses, which correspond to and engage with rectangular recesses. However, such guide noses do not necessarily have to limit the bending in a specific direction if they are arranged offset from one another in the longitudinal axis of the pipe. The offset can be achieved in a simple way by arranging the recesses on each pipe section offset by a certain angle from the corresponding noses. However, groups of different pipe sections can also be provided which alternately engage with one another.

According to a further development of the invention, by appropriately shaping the noses and recesses, not only can a bendable or flexible pipe be created, but also a pipe whose length can be changed, if a defined play in the axial direction is provided between the noses and recesses that engage with one another in the undercut area. Such axial length compensation can, for example,

This can be useful if the tube is used as a flexible shaft and an axial compensation similar to a spline or the like is required.

In a further development of the invention, the mushroom-shaped noses and correspondingly contoured recesses can be aligned at an angle to the longitudinal axis of the pipe, such that an imaginary axial extension of the noses or recesses extends helically around the pipe. If, in such a design, a defined clearance is provided between the noses and recesses in the area of the undercuts, a rotary movement can be achieved by generating an axial movement by arranging traction means and/or pressure means inside or outside the pipe. The angle of rotation between the beginning and end of the pipe can therefore be controlled in a targeted manner by controlling the axial length of the pipe.

The pipe sections described above for forming the bendable pipe according to the invention can be produced inexpensively in large quantities, for example as injection-molded parts, with the arrangement of lugs and recesses being carried out in such a way that assembly is possible by elastically bending up tongues or recesses.

However, the method for producing such a bendable tube will generally be much more favorable, as it can be used as a flexible endoscope shaft, as a hollow shaft, as a chain, as a flexible trocar, as a stent or the like. Accordingly, a rigid tube is divided into the previously described tube sections by a separation process. In this case, there is no need to assemble the tube sections together. The tube can be subjected to surface treatment before the separation joints are created, which further simplifies production. With a suitable separation process, it will generally not be necessary to subject the individual tube sections to post-processing.

In principle, the joints can be produced using any conceivable cutting method. Particularly for thin-walled pipes, such as those used in endoscope technology, cutting using a laser beam is preferable, as this enables fast and economical production with a joint that does not require any further processing. For thicker-walled pipes, larger

For pipes with a larger diameter, the joint can also be created by milling and, for even larger pipes, by burning. Another separation method is chemical or electrochemical separation. Here, too, post-processing of the joint is generally not necessary.
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The invention is explained in more detail below using embodiments shown in the drawing. They show:

Fig. 1 in side view two connected, by the separation process

pipe sections of a first inventive

embodiment;

Fig. 2 a section through the sections shown in Figure 1 along

the section line H-II;
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Fig. 3a shows a second embodiment of two

Separation process of sections of a flexible shaft in

a first stretched position;

Fig. 3b the embodiment according to Fig. 3a in a second extended

Position,

Fig. 3c shows a variant of this second embodiment in

Representation according to Fig. 3a,
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Fig. 4 shows a third embodiment of two

positively connected sections in longitudinal section,

Fig. 5 the two sections according to Figure 4 in side view,

Fig. 6 the sections according to Figure 4 in the angled state and

Sectional view according to Fig. 4,

Fig. 7 shows a fourth embodiment of

three form-fitting connected sections in the longitudinal

section (section line VII-VII in Fig. 9) in stretched arrangement,

Fig. 8 the design according to Fig. 7 in angled position and representation according to Fig. 7,
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Fig. 9 the design according to Fig. 7 rotated by 90° around the longitudinal axis

Sectional view (section line IX-IX in Fig. 7) and

Fig. 10 the arrangement according to Fig. 7 in angled position and

position according to Fig. 9.

In the cutting process, a separating joint is cut into a rigid pipe in a closed path, preferably using a laser beam. Laser cutting can be used to cut a meandering separating joint, such as the joint 3 shown in Figure 1, into a rigid pipe in such a way that connected pipe sections 1 and 2 are created (only two such pipe sections are shown in Figure 1). It is advantageous that the individual pipe section is already fully processed and assembled when the laser cutting process is completed, i.e. without any further post-processing, and each individual section has a homogeneous wall thickness.

In conjunction with the cross section shown in Figure 2 through the two pipe sections 1 and 2 along the section line II-II shown in Figure 1, it can be clearly seen that the cutting joint 3 visible at the height of the section II-II forms four noses 11 offset from one another by 90° and four recesses 12 also offset from one another by 90° on a pipe section, which essentially have the same mushroom-shaped contour as the noses 11. In each section 1, 2, each nose 11 is opposite a respective recess 12 in the axial direction. The recesses form undercuts of the noses in the circumferential direction. As a result, the individual sections cannot be separated from one another without damage. The degree of flexibility depends on the width of the separating joint 3, the length and the diameter of the individual element.

Of course, the number of lugs 11 and recesses 12 provided on one side is not limited to 4, but at least one lug and one recess must be provided on one side of a pipe section. By using four alternating lugs and recesses, a very good flexible deflection can be achieved in all planes in space.

The joints of a pipe section comprising several sections can also be designed in such a way that lugs and recesses adjacent to one another in the axial direction are offset in the circumferential direction by a certain angular amount.

With the help of the division of a shaft tube shown in Figures 1 and 2, flexible endoscope shafts, flexible trocar sleeves, flexible forceps, flexible techno- and endoscopes as well as, for example, flexible shafts for cardan shafts in bone and cartilage milling machines or the cardan shafts themselves can be manufactured.

In the embodiment shown in Figure 3a, the joint 3' between two adjacent identical pipe sections V,T is designed in such a way that the

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recesses 22 are at a defined distance from one another due to the shape of their undercuts, so that a defined play S in the axial direction is guaranteed. A flexible endoscope shaft designed in this way can therefore be varied in length and is advantageous, for example, in connection with instruments which carry out worm-like movements using alternately inflatable and deflatable ring-shaped cuffs in order to be able to be inserted more easily into the intestine or other body channels with the aid of this instrument movement. Figures 3a and 3b show the two sections Γ and 2' in the two end positions in which the flexible shaft has its shortest and longest length respectively. However, when using such tube sections 1', T shown in Figure 3a, an outer shaft or another suitable guide means may be required to prevent adjacent sections from becoming disengaged, which is possible, for example, when bent. This can also be prevented, for example, by using a short, thin-walled ring cylinder part either outside or inside the interlocking pipe sections.

In the embodiment shown in Fig. 3c, not only is an axial play S provided between the rear grips, which positively connect adjacent pipe sections in the longitudinal direction of the pipe, but in addition the noses 23 and the corresponding recesses 24 are inclined with respect to the longitudinal axis 5 of the pipe, such that an imaginary extension 6 of these noses 23 or recesses 24 helically travels around the pipe. In such an arrangement, the axial play S serves less as a length compensation, similar to a serration or the like, but rather to generate a rotary movement. If the pipe sections are moved from the shortest end position shown in Fig. 3c to the longest end position, in which the lateral projections of the lugs 23 rest against those of the recesses 24, then the pipe is bent around its longitudinal axis 5, specifically between the end pipe sections. This bending around the longitudinal axis 5 can be used to produce a targeted

Rotary movement can be used if appropriate tension and/or pressure means are provided inside or outside the tube. With such an arrangement, for example, an instrument can be rotated inside a shaft without a rotary movement being required for control. The parting line 3'c is therefore arranged obliquely to the axis 5 in relation to the parting line 3' in the area of its longitudinal extension.

Figures 4 to 6 show two identical pipe sections 1", 2" of a third embodiment that engage in one another in a form-fitting manner and are cut from a rigid pipe using the method. Both pipe sections 1", 2" have two first lugs 31 with a part-circular contour that are formed in an axial direction and are arranged offset by 180° from one another in the circumferential direction. In the same axial direction, the pipe sections have second lugs 33 with a rectangular contour that are also arranged offset by 180° in the circumferential direction and are each offset by 90° from the first part-circular lugs 31. Furthermore, both pipe sections 1", 2" have recesses 34, 35 between the first part-circular lugs 31 and the second rectangular lugs 33, as well as a lug 32 arranged between the two recesses, which can also be omitted if the lugs 31, 33 are dimensioned accordingly. The recess 34 undercuts the first lugs 31. In the other axial direction, both pipe sections 1", 2" have first recesses 36 with a partially circular contour, which are axially opposite the first lugs 31. Furthermore, both pipe sections 1", 2" have second rectangular recesses 37 opposite the rectangular second lugs 33, as well as additional recesses 38 receiving the lugs 32.

As Figure 6 shows, the two sections 1" and 2" can be angled towards each other, whereby the part-circular first lugs 31 of the second section 2" can be positively pivoted in the part-circular first recesses 36 of the first section 1" and the second lugs 33 can be pivoted in the rectangular recesses 37 without these being able to come out of engagement.

A flexible shaft section provided with tube sections 1", 2" according to Figures 4 to 6 can be used, for example, for a distally controllable end part in flexible techno- and endoscopes when bending in only one plane is desired.
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The design variant shown in Figures 7 to 10 differs from that shown in Figures 4 to 6 in that the recesses of a pipe section are not axially aligned with the corresponding noses of the same pipe section, but are offset by 90° from one another, so that successive pipe sections can always be bent alternately in different planes.

In Figures 7 to 10, the adjacent pipe sections are designated with Γ" and 2'", whereby three pipe sections are shown in each case. Each pipe section has two essentially rectangular noses 43 on the left-hand side in the figures, which are arranged offset by 180° from one another. Partially circular noses 41 are offset by 90°. Between the noses 41 and 43, noses 42 are arranged, which can be omitted if appropriately dimensioned in accordance with the noses 32 of the third embodiment. Recesses 44 are formed between the noses 41 and 42, and recesses 45 between the noses 42 and 43.

On the right side in Figures 7 to 10, the pipe sections have essentially rectangular noses 50 and pairs of noses 49 arranged between them.

A part-circular recess 46 is formed between two lugs 49, a rectangular recess 47 is formed between two adjacent lugs 50. The part-circular recesses 46, which are offset by 180° from one another, serve to accommodate the lugs 41 of the adjacent pipe section on the right. This connection between the lugs 41 and the recesses 46 forms a joint function around the common center axis of the lugs 41. In addition, these form-locking elements ensure a form-locking in the direction of the longitudinal

axis 5 of the pipe or pipe section. The rectangular noses 43 together with the rectangular recesses 47 form guides which increase the torsional rigidity of the pipe in the stretched and bent state.

Because the recesses 46 corresponding to the lugs 41 or the recesses 47 corresponding to the lugs 43 of the same pipe section are offset by 90° from one another, this results in an alternating bendability in one plane and then in a plane offset by 90°, whereby, with a sufficient number of pipe sections, a pipe is created that is flexible in all directions and has a high level of inherent stability with a compact structure. The larger bending radius of the pipe that may result in one plane compared to the third embodiment (Fig. 4 to 6) can be at least partially compensated for by shortening the pipe sections, as is possible due to the offset arrangement of recesses and lugs.

All of the above-described embodiments have in common that the parting line responsible for the mobility of the individual pipe sections is cut out of a rigid shaft pipe using a laser beam cutting process. Of course, the invention is not limited to the embodiments described with reference to Figures 1 to 10. If, for example, the parting line is designed in such a way that it cuts out oblique pipe sections rather than straight pipe sections from the rigid shaft, this can be used to specify an orientation of the flexible mobility of the shaft section or a specific curvature of the same.

Furthermore, pipe sections according to Figure 1 can be combined with those according to Figure 3a or Figures 4 to 10 in a movable shaft part.

Claims (11)

Expectations 1. Bendable tube, in particular as a shaft for a flexible endoscope, which consists of tube sections (1, 2) connected to one another in a form-fitting manner, characterized in that it is manufactured directly from a substantially rigid tube by the production of completely circumferential separating joints (3). 2. Pipe according to claim 1, characterized in that a pipe section (1) has at least one nose (11) pointing towards the adjacent pipe section (2), which engages in a form-fitting manner in a corresponding recess (12) of the adjacent pipe section (2). 3. Pipe according to one of the preceding claims, characterized in that a pipe section (1) has at least two, preferably four, noses (11) pointing towards the adjacent pipe section (2) and that a recess (12) is formed by the space formed between two adjacent noses (11) of the same pipe section. 4. Pipe according to one of the preceding claims, characterized in that a nose (11) has a rounded mushroom-shaped, preferably approximately partially circular, outer contour. 5. Pipe according to one of the preceding claims, characterized in that a pipe section (I") has four or more lugs (31 - 33) pointing towards the adjacent pipe section (2"). 6. Pipe according to one of the preceding claims, characterized in that a nose (33, 40) has a rectangular outer contour. 7. Pipe according to one of the preceding claims, characterized in that a pipe section (1") has two noses (31) of part-circular contour arranged offset by 180° on one side and two noses (33) of rectangular contour arranged offset by 90° therefrom, as well as correspondingly shaped recesses (35, 36) on the other side. 8. Pipe according to one of the preceding claims, characterized in that the lugs (49, 50) on one side of a pipe section (&Ggr;") are arranged offset by an angle with respect to the corresponding recesses (44, 45) on the other side of this pipe section (&Ggr;"). 9. Pipe according to one of the preceding claims, characterized in that the lugs (21) and the associated recesses (22) have a distance (s) in the region of their rear engagements. 10. Pipe according to one of the preceding claims, characterized in that the lugs (23) and the associated recesses (24) are designed and arranged such that their imaginary longitudinal axis (6) extends helically around the longitudinal axis (5) of the pipe. 11. Pipe section for forming a bendable pipe according to one of the preceding claims, characterized in that at least one nose (11) is provided on one end face and at least one recess (12) is provided on the other end face for the positive reception of a nose.