DE19910128C1 - Flexible protective sleeve for a light guide comprises numerous stiff sleeve sections which interlock with each other - Google Patents

Abstract

A flexible protective sleeve for a light guide (1) comprises numerous stiff sleeves which run in the light guide direction. Each sleeve (4) covers a fraction of the light guide and the sleeve sections are connected so that they can be moved through an angle of 5-15 degrees to each other. One end of each sleeve section locates in the holding section of the adjacent section

Description

The invention relates to a protective cover for light guides, preferably for light Conducting fibers, such as those used in laser technology, in communications technology or in image guidance technology, here for example for endoscopy purposes the.

Especially for the transmission of radiation in the range of IR and UV wavelengths used the light guide as a waveguide or fibers and the latter in turn as a single fibers, can be formed as a fiber bundle or as liquid fibers. For the manufacture come with special materials such as zirconium fluoride, sapphire, chalcoge nid u. a. into consideration. The light guides are due to their geometric shape (schwa cross-section) and the peculiarities of the material are very fragile, d. H. she have a limit bending radius, which is without risk of kinking and thus destruction light guide must not be undercut. In this regard comes the Protective cover, above all, the function to protect the light guide from excessive curvature and to protect against kinking.

In practical use of the light guide, especially for exercise microsurgical operations on the eye, but there is also a requirement for a high flexibility of the light guide including the protective cover, as a sensitive handling of the medical handpiece coupled to the light guide kes must be guaranteed, especially the microsurgical operations require the most unobstructed, extremely precise work possible.

Flexibility therefore also means that the necessary changes in direction of the Handpiece during the operation regardless of the connection of the handpiece the light guide provided with the protective cover only the least resistance  is set so that for the surgeon, for example, even when swiveling the Handpiece by 180 ° and more is hardly noticeable. That sets next the flexibility but also a low weight of the light guide including the Protective cover ahead. Furthermore, the surgeon must be relieved of the worry by his hand movements to accidentally destroy the light guide by kinking it so that he can concentrate on the operation.

Various designs of light guides and Known protective covers, which more or less include the requirements mentioned send meet. For example, DE 43 36 643 A1 describes a light guide, which consists of one or more polymeric optical fibers that are protected are surrounded. This protective cover has the shape of a tube in which the Optical fibers are loosely arranged. The hose consists of a with over lapping band edges to a tube spirally wound metal band and one polymeric coating layer applied to the tube.

Protection against excessive bending is created here by overlapping stops the band edges against each other. Such a protective hose is particularly liable Disadvantage of a relatively high weight due to the use of Metal is due. Another major disadvantage is that with increasing bending or decreasing radius of curvature an increased force effort is required to convert the light guide including the protective cover to bend even smaller radius. That inevitably results from the resilient Property of the spirally wound metal strip that an increasing Ver formation always opposes increasing resistance. It is easy visible that this property is the free manipulation, for example one closed handpiece.

The surgeon, who tries hard, always new the handpiece during the treatment To align, has such a protective cover different from the bending radius to exercise pending forces. It happens very much with a smaller bending radius often for bending and kinking the light guide, since only the bigger one resistance, but no significant bending limitation is noticeable. Those in Grenzra The power to be exercised is perceived differently by the users and can therefore not be used as an overload criterion when bending the protective cover or the light guide apply. The user is not given a clear signal when  the minimum permissible bending radius has been reached and the fiber is kinked threatens.

The utility model DE 298 09 160 U1 describes a protective hose for one Light guide for the transmission of laser energy. This protective tube has one Metal existing inner hose, which is still with a protective braid as well is surrounded by a liquid-tight jacket. The inner tube is from a gap freely coiled stainless steel ribbon and leaves only a curvature of the light Head under relatively high effort, which is also disadvantageously egg high resistance to deformation or high restoring efforts Consequence. Added to this is the relatively high level, due to the metal casing weight, which makes sensitive handling even more difficult. In the Comparison of these properties with the aforementioned requirements clearly that this protective tube is also unsuitable for the purposes of microsurgery is not.

The utility model DE 297 12 789 U1 proposes one from a bundle of flexible optical fibers existing light guides from a flexible metal sheath surrounded, wherein the metal shell is formed from a metal foil. Meet here too likewise the disadvantages already mentioned in detail.

Starting from this prior art, the invention is based on the object to develop a protective cover of the type described above so that the sensitive ma nual handling of a connected device, such as a medical Handpiece, is possible. The light guide is used to transmit the radiation energy from the source to the irradiation site, while the protective cover the light guide from mechanical influences and also from inadequate environmental conditions such as inadmissible temperatures or excessive humidity.

According to the invention the object is achieved with a flexible protective cover for Lichtlei ter that from a large number of in the direction of the light guide together row of individual rigid, material-separated sleeves consists of each of which encompasses a fraction of the total length of the light guide and which is articulated are connected to each other so that two adjacent sleeves at an angle α are pivotable against each other from their direction of alignment.  

This ensures on the one hand that the light guide running inside the sleeves against mechanical influences from outside and largely also against impermissible high temperatures and / or humidity values is protected, on the other hand but also an extremely sensitive manipulation, for example one with protection cover or the classified light guide connected medical handpiece possible, since the alignment directions of the individual sleeves are exerted with minimal force are easily changeable or against the slightest resistance, which ever the most varied curvatures of the protective cover as required and handled including the light guide, which is particularly necessary if the end of the protective cover opposite the handpiece with a fixed one Radiation source is coupled and with the handpiece operations performed those who need to change the spatial direction of the handpiece by 180 ° and more other.

The main functional difference from the state of the art, from which to the same as the advantages of the invention are that the protective cover egg deformation to a smaller bending radius no increasing resistance was opposed because the restoring forces that are present in the prior art are missing for example, from the spring action of a spirally wound metal strip give. In the solution according to the invention, the change in the alignment direction has tion of two adjacent sleeves with increasing angle α, which is a measure of the Än change in the direction of alignment, no increase in effort as a result here only the sleeves against each other about a corresponding hinge axis be pivoted. No forces are required to keep the sleeves in place or to keep position to each other, which they took after the change of direction have, since, as shown, there is no restoring force.

Another advantage over the known technical solutions is that that the pivoting of two adjacent sleeves against each other from their Direction of alignment is limited. The pivoting is only possible until the Center axes of the adjacent sleeves by the angle α from their direction of alignment are inclined towards each other; According to the invention, the inclination limitation provides that User a clearly perceptible signal when the minimum allowable bending radius is achieved, as will be shown below, and thus prevents, for example indicate an unintentional kinking of the light guide.  

The incline limitation may also be desired for the following important reason be worth it: The basic shape of the light guide is a "rod", usually with a cylindrical cross cut in which the light is transmitted through total reflection on the inner surface of the jacket becomes. If this "rod" is curved, the angles of incidence on the jacket change inner surface and total reflection are disturbed the more the curvature or the smaller the bending radius becomes. In this respect, the inclination limitation can also do this serve the bending radius of the light guide from a practical point of view limit still acceptable measure.

The specification of the angle α can therefore take into account both the aspect of the buckling and the aperture. In this regard and in connection with the present Er Invention, the angle α is preferably in the range of 5 ° to 20, particularly be preferably to be specified with the value 15 °.

In a preferred embodiment of the invention, two adjacent ones each Sleeves at their mutually facing ends, corresponding to each other, as Ge steer with at least one hinge axis trained locking elements, always the end of one sleeve engages in the end of the adjacent sleeve and the individual sleeves form a composite, also in the direction of the light guide is subject to considerable pressure and train. This will also achieved that the sleeves connected by such a joint with respect their direction of alignment around the at least one hinge axis with uniform force expenditure can be pivoted.

It when the locking elements are designed as ball locking elements is particularly advantageous are, the end of a sleeve a spherical shape and the facing end of the another sleeve has a spherical shape and so two adjacent sleeves are positively connected to each other by a ball joint coupling.

Such a protective cover can be easily produced in any length by adding a sleeve Sleeve is added. The sleeves can be individually prefabricated as mass parts, what means a low cost per sleeve. The sleeves can then be in one due to the predetermined length of the light guide to be coated  are strung together, the spherical shape under slight pressure tion at the end of one sleeve into the dome shape at the end of the next sleeve is pushed and clicks into place.

To limit the angle α by which two adjacent sleeves with respect to their Alignment direction are pivotable against each other, are the invention mutually facing end sections of adjacent sleeves with corresponding Provide abutment surfaces, these abutment surfaces then contacting each other and prevent a further change of direction if the maximum permissible angle α and thus the minimum bending radius of the light guide is reached.

In this way, the light guide can not be curved more or the bending radius of the The light guide should not be smaller than the stops allow. The stop faces are molded onto the ends of the sleeves and only require a little extra work wall in the manufacture and no additional effort when joining the Sleeves.

In a particularly preferred embodiment of the invention it is provided that the Sleeves have annular cross sections, the inner diameter of the cross cut, measured in the middle between the two ends of the sleeve, to a game that one smooth movement of the sleeves relative to the light guide enables larger is guided as the cross-sectional dimension of the light guide and the inside through knives are increasingly larger from the center to the two ends.

With the possibility of the relative displacement of the sleeves to the light guide is the Län ensures equilibrium, which is required as soon as the slope of the neighboring Sleeves to each other is changed to the Lichtlei running within the sleeves the desired curvature. The small cross-section ensures diameter in the middle of the sleeves also ensures that the relative mobility of Sleeve and light guide perpendicular to the direction of the light guide on the necessary ge dimension remains limited, while those increasing at the ends of each sleeve Inner diameter ensure that the light guide in the joint axes of two sleeves cannot experience a kink. To that extent is at the sleeve ends between the inside wall of a sleeve and the outer surface of the light guide so much play that the pivoting up to the maximum possible angle α without risk of kinking of the light guide.  

It is also within the scope of the invention that at least two of each other be neighboring sleeves with means for limiting and preventing relative Rotation to each other about their central axes or the optical axis of the light guide are equipped. This advantageously ensures that no torsion from the sleeves forces can be transferred to the light guide and this also against destruction tion is protected by torsional forces.

The means for preventing rotation of two sleeves relative to each other can be designed such that at least one sleeve of two adjacent sleeves a material recess pointing in a radial direction and the other sleeve min at least one corresponding to this and in the material recess of the neighboring th sleeve engaging material survey. This intervention guarantees That is, the orientation of the two adjacent sleeves, based on their twists hung around the central axes, always remains the same. The pivotability of this the two sleeves relative to each other by the angle α in relation to their direction of alignment not affected by this.

Another embodiment variant of the means for limiting or preventing the relative rotation to each other provides that the sleeves from a jacket from a surrounded by flexible material that is welded to the outer circumference of the sleeves, is preferably glued or under tension on its outer circumference catch sits, whereby the relative rotation against each other prevents or at least least is limited.

This coat not only has the advantage of being able to absorb torsional forces and there with the rotation of the sleeves to each other to prevent their central axes, son because he also creates additional mechanical stability and it is possible his upper surface to be equipped with properties that meet certain medical requirements if used appropriately.

So it is often necessary that the outer surface of the jacket hygienically unbe conceivable, also quick and easy to clean and in this respect one if possible must have a smooth surface. It is also often desirable that the coat be unemp is sensitive to disinfectants and must be sterilizable, which Unemp sensitivity to moisture, temperature and sterilization gases.  

In addition, the coat also has the advantage that it also in the direction of Optical fiber can absorb tensile or compressive forces and thus the locking elements, through which the sleeves are connected, relieved. However, the coat must consist of a very soft and flexible material, so the flexibility of the Protective cover remains guaranteed.

In this regard, it has proven useful to use a silicone-coated sheath To manufacture glass silk fabrics. This allows all of the above properties achieve. It is also conceivable to form a multi-layer jacket, in which case the inner layer located between the outer and the circumference of the sleeve absorb the tensile and torrential forces and the outer layer for the medical use should have advantageous surface properties.

In a particularly preferred embodiment of the invention, the means for ver preventing or limiting twisting of two adjacent sleeves against each other provided between all adjacent sleeves except between the first and the second sleeve and / or between the last and the penultimate sleeve (viewed in the direction of the light guide). It is advantageously achieved that only the first sleeve and / or the last sleeve of the protective cover compared to the usual The remaining sleeves can be rotated about the central axis.

In this respect it can be provided that the first and last sleeve of the protective cover is not glued, welded or even frictionally connected to the jacket and also no material elevations and material extending in the radial direction have recesses that are connected to the neighboring sleeve. The Ver rotatability of the first and / or the last sleeve relative to the other sleeves of the Protective cover is desirable, for example, if it has a thread with other light-conducting assemblies, for example on the coupling-in side with the radiation source and decoupling side to be connected to a medical handpiece.

Advantageously, the sleeves made of a plastic with a modulus of elasticity in Range from E = 2,000 MPa to 15,000 MPa, preferably a glass fiber reinforced Po lyamide, particularly preferably a glass fiber reinforced polyamide of the designation PA6GF25.  

The coat should be made of a soft rubber or a very flexible plastic stand. For example, a single sleeve should be 15 mm to 25 mm in length be carried out, the inner diameter at the narrowest point about 4 mm and the outer diameter should be about 8 mm.

The invention will be explained in more detail below using an exemplary embodiment become. Show in the accompanying drawings

Fig. 1 shows a basic arrangement of the solution according to the invention.

FIG. 2 shows a detail A from FIG. 1

Fig. 3 shows the representation of FIG. 2, but with sleeves inclined towards each other

Fig. 4 shows a further embodiment variant of the invention

In Fig. 1 is a laser radiation source 1 is shown which is connected via a flexible light guide 2 with a medical handpiece 3. The laser radiation source 1 is exemplarily equipped with an Er: YAG laser that emits radiation with a wavelength in the range λ = 2.9 μm. The medical handpiece 3 was designed to perform microsurgical interventions in the eye, for example for phacoemulsification. The light guide 2 is to consist, for example, of a single fiber made of quartz glass, the subject matter of the invention not being based on the specified concreteness, but instead of the Er: YAG laser also other technically equivalent radiation sources come into question and as light guides instead of the single fiber made of quartz glass also individual fibers made of zirconium fluoride, sapphire, chalcogenide or the like and furthermore also waveguides, liquid fibers and other flexible light guides can be provided which are adapted to the respective use and are suitable for transmitting the radiation. Furthermore, the invention is not limited to the transmission of radiation energy to a medical handpiece, but other beam-guiding instruments are also conceivable here. Instead of the handpiece, you can also imagine an optical fiber coupling.

Since the medical handpiece 3 must be portable in order to be able to carry out the microsurgical operation and therefore should also be easy and sensitive to handle while the laser radiation source 1 remains in relative rest, the user demands that the light guide 2 be from one Protective cover is ben, which on the one hand does not hinder the desired flexibility, but on the other hand also protects the light guide 2 from external mechanical influences, temperature influences, etc. Above all, this also means that a bending of the light guide 2 by such a small radius is prevented, which would result in the light guide 2 kinking within the protective cover.

According to the invention, a protective cover is provided which consists of a plurality of individual sleeves 4.1 , 4.2 , 4.3 to 4. n arranged in a row in the running direction of the light guide 2 . Each of these individual sleeves 4.1 to 4. n encompasses a section or a section of the total length of the light guide 2 .

During the operation, the position of the handpiece 3 changes in a variety of ways with respect to the laser radiation source 1 which is in relative rest. As a result, the light guide 2 undergoes curvatures which - as can be easily imagined - are not only in the plane of the drawing in FIG. 1.

In Fig. 2 the individual unit A from Fig. 1 is shown enlarged to explain a preferred design variant of the protective cover according to the invention with the help of the two neighboring sleeves 4.3 and 4.4 . It can be seen that the two sleeves 4.3 and 4.4 are connected to one another by latching elements which are designed in the form of a ball joint. The sleeve 4.3 has a dome-shaped recess 5 at its end facing the adjacent sleeve 4.4 , while the sleeve 4.4 is provided with a spherical bead 6 at its end facing the sleeve 4.3 .

Furthermore, it can be seen that the dome-shaped recess 5 is limited by an annular locking edge 7 ge. The diameter of the locking edge 7 is so much smaller than the largest diameter of the spherical bead 6 that, on the one hand, the spherical bead 6 can be snapped into the spherical recess 5 by overcoming the locking edge 7 with little manual effort and, on the other hand, a minimum tensile force is required, to separate both sleeves from each other again.

In this way, the sleeves 4.3 and 4.4 can be easily joined together by hand, and conversely, the two sleeves 4.3 and 4.4 can also be separated from one another if necessary.

In the joined state, the two sleeves 4.3 and 4.4 about the position 8 in the center of the spherical bead 6 and the dome-shaped recess 5 are mutually pivotable GE. The pivoting of the two sleeves 4.3 and 4.4 ge against each other about the position 8 leads to a curvature of the light guide 2 , which is enclosed by the sleeves 4.3 and 4.4 . The position that the two sleeves 4.3 and 4.4 have after this pivoting relative to one another and the curvature of the light guide 2 thus achieved is shown in FIG. 3. The pivoting of the two sleeves 4.3 and 4.4 against each other can take place in the drawing plane of FIG. 3 as well as from the Zei plane, to the extent that this is permitted by the ball joint connection.

In order to a curvature of the light guide 2 phase but an acceptable level addition to verhin on which is 4.3 a conical abutment surface 9 and at the 4.3-facing end of the sleeve 4.4 provided the sleeve 4.4 facing end of the sleeve of the sleeve a zy-cylindrical abutment surface 10th As can be seen in Fig. 3, the pivoting of the two sleeves 4.3 and 4.4 against each other is only possible until the cylindrical stop surface 10 comes to rest against the conical stop surface 9 . In this way, excessive curvature of the light guide 2 is prevented according to the invention. For example, the stop surfaces 9 and 10 are dimensioned such that a deflection of the two sleeves 4.3 and 4.4 against each other by a maximum of the angle α = 10 ° is possible. The angle α can of course be designed larger and smaller depending on the design of the formations at the ends of the sleeves 4.3 and 4.4 and of course also in the dependency on the material of the light guide 2 or its minimum permissible radius of curvature.

In Fig. 2 it is also shown that the sleeves 4.3 and 4.4 have at their mutually facing ends from the exactly opposite shape than at their mutually facing ends. Thus, the sleeve 4.3 there has the spherical bead 6 , while the sleeve 4.4 is verses at this point with the dome-shaped recess 5 . This applies in an analogous manner to the conical stop surface 9 , the cylindrical stop surface 10 and, of course, also the locking edge 7 . In this way, it is possible to join sleeves formed in this way in any number n and thus to enclose light guides 2 of any length. A provided with such a protective light guide 2 has the advantage that only a minimal effort to change the direction of the connected handpiece or to bend the Lichtlei age 2 is required and also an overbending of the light guide 2 is prevented with high security.

As can further be seen from FIG. 1, the first sleeve 4.1 and the last sleeve 4 .n can be made to have a greater length than the other sleeves 4.2 to 4. n-1 and it is within the scope of the invention to have the sleeve 4.1 on it to provide the laser radiation source 1 facing end with an optical fiber coupling. This applies analogously to the end of the sleeve 4. N facing the medical handpiece. In addition, it can be provided that the sleeves 4.1 and 4. N only have ends with locking elements at their respective ends facing the adjacent sleeves 4.2 and 4. N - 1 ( the spherical bead 6 or the dome-shaped recess 5 ) are provided.

As can be further seen in FIG. 2 and FIG. 3, the inner diameter of the tubes is 4.3 and 4.4, carried out to a game that enables smooth displacement of the sleeve 4.3 and 4.4 on the light guide 2 is greater than the cross sectional dimension of the light guide 2. In the example shown, the light guide 2 , like the sleeves 4.3 and 4.4, has a circular cross section. Because of this game, it is now possible that the light guide 2 relative to the sleeves 4.3 and 4.4 in the longitudinal direction moves easily while the sleeves 4.3 and 4.4 pivoted against each other who.

In a further preferred embodiment of the invention according to FIG. 4, two material elevations 11 pointing in opposite radial directions are provided on the spherical bead 6 and, corresponding thereto, two material cutouts 12 pointing in the same direction are provided on the spherical recess 5 , which in the case of sleeves 4.3 and 4.4 which are merged into one another interact with each other. By this engagement of projection 11 material and material recess 12 a rotation of the sleeve is 4.3 and 4.4 against each other is prevented around the center axis 13 of the sleeve and the light guide is protected against torsion.

A glass fiber reinforced polyamide of the designation PA6GF25 has proven itself as a material in practical testing for the sleeves, which has an elasticity behavior that allows the joining of two sleeves, as shown in the example of sleeves 4.3 and 4.4 , over the locking edge 7 without any problems.

In a further very preferred embodiment, it is provided that the sleeves 4.1 to 4. n are additionally surrounded with a rubber jacket 14 , which can absorb torsional forces, against which the light guide 2 is to be protected, and is capable of penetrating dust and to prevent moisture to the light guide 2 as much as possible.

Reference list

1

Laser radiation source

2nd

Light guide

3rd

medical handpiece

4.1

. . .

4th

n sleeves

5

dome-shaped recesses

6

spherical bead

7

Locking edge

8th

position

9

conical stop surface

10th

cylindrical stop surface

11

Material collection

12th

Material recess

13

Center axis

14

coat

Claims (12)

1. Flexible protective cover for light guide ( 1 ), consisting of a large number of individual rigid, material-separated sleeves ( 4.1... 4. n) lined up in the direction of travel of the light guide ( 1 ), each of which is a fraction of the total length of the light guide ( 1 ) encompasses and is articulated so that two adjacent sleeves ( 4.3 , 4.4 ) can be pivoted against each other by an angle α from their direction of alignment, with two adjacent sleeves ( 4.3 , 4.4 ) corresponding to each other at their mutually facing ends , Have joints designed as joints with at least one hinge axis and always the end of a sleeve ( 4.4 ) engages in the end of the adjacent sleeve ( 4.3 ) so that the individual sleeves ( 4.3 , 4.4 ) form a composite that extends in the direction of the Light guide ( 1 ) can be subjected to considerable pressure and train and the light guide is right relative to the sleeves ( 4.1 . , , 4. n) in the axial direction and in the region of the joints in the radial direction. 2. Protective cover according to claim 1, characterized in that the latching elements are designed as ball joints, the end of one sleeve ( 4.4 ) having a spherical shape ( 6 ) and the facing end of the other sleeve ( 4.3 ) having a spherical shape ( 5 ) and so each two adjacent sleeves ( 4.3 , 4.4 ) are positively connected to each other by a ball joint coupling. 3. Protective cover according to claim 2, characterized in that the mutually facing end portions in adjacent sleeves ( 4.3 , 4.4 ) are equipped with corresponding stop surfaces ( 9 , 10 ) for limiting the angle α. 4. Protective cover according to claim 3, characterized in that by the stop surfaces ( 9 , 10 ) the angle α is preferably limited to values from 5 ° to 20 °, particularly preferably to the value 15 °. 5. Protective cover according to one of the preceding claims, characterized in that the sleeves ( 4.1... 4. n) have annular cross sections, the inner diameter of the cross section in the middle between the two ends of the sleeves ( 4.1... 4. n ) by a game that allows the sleeves ( 4.1... 4. n) to move freely relative to the light guide ( 1 ), is larger than the cross-sectional dimension of the light guide ( 1 ) and the inside diameter from the center to both ends are increasingly larger. 6. Protective cover according to one of the preceding claims, characterized in that in at least two adjacent sleeves ( 4.3 , 4.4 ) means for preventing or limiting rotation against each other about their central axes ( 13 ) are provided. 7. Protective cover according to claim 6, characterized in that of the adjacent sleeves ( 4.3 , 4.4 ) a sleeve at least one in the radial direction material recess ( 12 ) and the other sleeve at least one corresponding thereto and in the material recess ( 12 ) of the adjacent sleeve ( 4.4 ) engaging material elevation ( 11 ), whereby the rotation against each other is prevented. 8. Protective cover according to claim 6, characterized in that the adjacent sleeves ( 4.3 , 4.4 ) are surrounded by a jacket ( 14 ) made of a flexible material which is welded, preferably glued, to the outer circumference of the sleeves ( 4.3 , 4.4 ) sits under friction on its outer circumference, thereby preventing or at least limiting twisting against each other. 9. Protective cover according to one of claims 6 to 8, wherein the means for preventing or limiting rotation against each other between all adjacent sleeves ( 4.1... 4. n), except between the first ( 4.1 ) and second ( 4.2 ) and / or between the last ( 4th n) and penultimate ( 4th n - 1) sleeve, are provided. 10. Protective cover according to one of the preceding claims, characterized in that the first ( 4.1 ) and / or the last sleeve ( 4. n) only at the end of the respective adjacent sleeve ( 4.2 or 4. n - 1) facing the Features according to one of claims 2 to 5 and at the end facing away from the respective adjacent sleeve ( 4.2 or 4. n - 1) has coupling elements for connection to other light-conducting assemblies. 11. Protective cover according to one of the preceding claims, characterized in that the sleeves ( 4.1... 4. n) made of a plastic with a modulus of elasticity in the range of E = 2,000 to 15,000 MPa, preferably a glass fiber reinforced polyamide, particularly preferably a glass fiber reinforced polyamide the designation PA6GF25. 12. Protective cover according to claim 11, characterized in that the jacket ( 14 ) consists of rubber or plastic.