Patent Publication Number: US-2022221088-A1

Title: Fluid line having a wave form portion

Description:
The invention relates to a fluid line having a wave form portion according to the preamble of claim  1 . 
     In the case of applications in the automotive industry, e.g. for cooling water or for thermal management of electric vehicles, the pressure loss of the system is critical and must be kept as low as possible. At the same time, the weight should be reduced and the lines should be formed flexibly in order to balance out relative movements between the connecting points and enable easy mounting. Rubber hoses are frequently used in certain conditions, these offering high flexibility and low pressure losses. They, therefore, tend to be heavy and expensive. 
     Extruded plastic tubes are significantly lighter and lower cost. They are typically either smooth, corrugated or partially corrugated. Smooth tubes have low pressure losses, but are relatively stiff, while corrugated hoses have a flexibility which is comparable with that of rubber. However, the gain in flexibility is at the cost of significantly increased pressure losses. The pressure losses can be encouraged by the wave form since a fluid flowing via a wave form cannot follow the waves. This leads to increased friction and turbulence of the fluid flow on the wall so that the fluid flow detaches from the wall. The detachment from the wall facilitates the generation of vortices which bring about a reduction in flow speed. 
     In order to reduce pressure losses, it is known to use hoses which have a wave form only in curve regions, i.e. only in the regions in which flexibility is required. Despite reduced pressure loss in comparison with corrugated hoses, the pressure loss of these hoses is much greater than in the case of rubber hoses. 
     It can therefore be regarded as an object of the invention to provide a fluid line having a wave form portion which further reduces a drop in pressure at the wave form portion. 
     The main features of the invention are indicated in the characterizing part of claim  1 . Configurations are the subject matter of claims  2  to  13 . 
     In the case of a fluid line having a wave form portion, wherein the wave form portion extends at a minimum distance along a longitudinal axis of the fluid line, it is provided according to the invention that the wave form portion has a wave crest element which has a varying distance to the longitudinal axis along a circumferential direction extending around the longitudinal axis of the fluid line, wherein the distance comprises a distance profile in the circumferential direction, wherein the distance profile provides a non-circular contour. 
     With the invention, there is used a wave form portion having wave crest elements for the generation of a curve in the fluid line, where an optimized curve form of the fluid line is provided as a result of the varying distance of the wave crest element to the longitudinal axis along the circumferential direction around the longitudinal axis. The varying distance of the wave crest element in the circumferential direction brings about that the flexibility of the wave form portion varies along the circumferential direction. A circumferential position of the wave crest element which has a large distance to the longitudinal axis of the fluid line brings about high flexibility at this position. A circumferential position of the wave crest element with a small distance to the longitudinal axis brings about low flexibility at this position. The flexibility of the wave form portion can thus be selected locally by means of the distance to the longitudinal axis so that, when generating a curve in the fluid line, optimized flexibility of the wave form portion is provided at the wave form portion for each angle position along the circumferential direction around the longitudinal axis. Higher flexibility can thus be provided, for example, at the circumferential positions of the wave crest element which are provided to form the outer radius of the curve than at the circumferential positions of the wave crest element which form the inner radius. As a result of the locally optimized flexibility of the wave form portion, an optimized curve form can be provided which provides on the inner radius of the curve inside the fluid line a surface with a minimal wave form, i.e. waves with a very small amplitude, or a smooth surface on which the generation of vortices in the flow is reduced. This brings about a reduction or avoidance of a drop in pressure at the curve of the fluid line generated at the wave form portion. 
     The distance of the wave crest element can change continuously along the circumferential direction. 
     A continuous change in flexibility in which the distance is changed continuously along the circumferential direction can thus be provided e.g. between the two circumferential positions which should form the outer and inner radius of a curve on the wave form portion. The flexibility of the wave form portion can thus be adapted evenly more expediently to the curve to be produced of the fluid line so that a drop in pressure is further reduced. 
     In this case, the distance in the circumferential direction can change according to a sine function or according to a square of a sine function. 
     The wave crest element can furthermore extend in the circumferential direction only around a partial circumference of the wave form portion. 
     By means of the partial extension of the wave crest element around the circumference, the increased flexibility can be provided by means of the wave form only at the positions at which increased flexibility is required for stretching of the material. No increased flexibility is e.g. regularly required at the provided inner radius of a curve of the fluid line so that the wave form can be dispensed with at these positions, as a result of which a further reduction in the drop in pressure is brought about. 
     The fluid line can thus have a wave-free wall portion which has along the longitudinal axis a smooth surface, wherein the wave form portion in the circumferential direction comprises a first end region and a second end region, wherein the wave-free wall portion extends between the first and the second end region. 
     By providing the wave-free wall portion, it can be ensured that a smooth wall surface is present in the inner space of the fluid line at the provided inner radius of a curve of the fluid line. Increased friction in the fluid flow on the inner radius of the curve is thus counteracted. In combination with the increased flexibility of the wave form portion at the wave crest elements, the wave-free wall portion is subject, if at all, only to a small change in length along the longitudinal axis. Moreover, the wave-free wall portion is thus not compressed so that the smooth surface of the wave-free wall portion does not have any humps which can regularly be brought about by the compression of materials. This contributes to a further reduction in the drop in pressure in the fluid flow. 
     The wave-free wall portion can be arranged at the minimum distance to the longitudinal axis. 
     The wave-free wall portion thus has the same distance to the longitudinal axis as the further portions of the fluid line which adjoin the wave form portion. 
     In a further example, the wave crest element can have a maximum distance to the longitudinal axis, wherein a position of the maximum distance in the circumferential direction is arranged diametrically opposite a position of the wave form portion which has the minimum distance to the longitudinal axis. 
     Thus, a circumferential position with maximum flexibility and a circumferential position with minimum flexibility lie diametrically opposite one another in the circumferential direction. When generating a curve in the fluid line, as a result of their locally higher flexibility, the circumferential position with the maximum distance to the longitudinal axis is therefore primarily deformed and the circumferential position with the minimum distance to the longitudinal axis is deformed to a small degree or not at all. The distance of the wave-free wall portion can be constant to the longitudinal axis in the circumferential direction. This brings about an optimally formed wall surface on the inner radius of the curve which further reduces vortices and thus a drop in pressure. 
     The wave-free wall portion can furthermore have a neutral axis of the fluid line. 
     No change in length is thus brought about in the wave-free wall portion at the position of the neutral axis of the fluid line when generating a curve. This further brings about that the entire wave-free wall portion is subject to only a small change in length in comparison with the range which the wave crest element has when generating a curve. 
     The wave-free wall portion can, in the circumferential direction, cover an angle in the range between 0° and 180°, preferably between 0° and 120°, further preferably between 0° and 80°. 
     The fluid line can furthermore have at least one wave-free line portion which extends along the longitudinal axis away from the wave form portion. 
     The wave form portion can thus be arranged between wave-free line portions in a targeted manner on a provided curve. 
     The wave form portion can furthermore have a plurality of wave crest elements, wherein in each case a wave trough element which is arranged at the minimum distance to the longitudinal axis is arranged between in each case two wave crest elements. 
     The number of wave crest elements in the wave form portion can be adapted to the length of extent or the bending angle of the provided curve. The larger the bending angle of the provided curve, the more wave crest elements can be used. 
     The fluid line can have a curve in which the wave form portion is arranged. 
     The wave crest element can furthermore be arranged on an outer radius of the curve. 
     The wave form portion can have the minimum distance on an inner radius of the curve across its entire extent along the longitudinal axis. 
    
    
     
       Further features, details and advantages of the invention arise from the wording of the claims and from the following description of exemplary embodiments on the basis of the drawings. In the drawings: 
         FIGS. 1 a, b    show sectional drawings of a schematic representation of a fluid line having a wave form portion; 
         FIG. 2  shows a schematic representation of a fluid line having a bent wave form portion; and 
         FIG. 3  shows a diagram with exemplary profiles of the varying distance along the circumferential direction. 
     
    
    
     A fluid line is represented schematically in  FIG. 1 a    and is referred to in its entirety by the reference number  10 . 
       FIG. 1 a    shows schematic representation of fluid line  10  in a side view. Fluid line  10  extends in the horizontal direction along longitudinal axis  16  and can be formed from an extruded plastic material. Fluid line  10  further comprises a wave form portion  12  which extends at a minimum distance  14  to longitudinal axis  16  along longitudinal axis  16  of fluid line  10 . Wave form portion  12  is arranged between two line portions  28  which do not have a wave form. On the contrary, line portions  28  have a smooth wall. In this case, wave form portion  12  is arranged at a position at which a curve should be produced in fluid line  10 . 
     Wave form portion  12  has at least partially a wave-shaped wall portion which has at least one wave crest element  18  which extends between a maximum distance  24  to longitudinal axis  16  and minimum distance  14  to longitudinal axis  16 . Wave form portion  12  comprises according to figure la a plurality of wave crest elements  18  which are separated from one another by wave trough elements  34 . A wave trough element  34  is arranged at minimum distance  14  to longitudinal axis  16 . The number of wave crest elements  18  in wave form portion  12  can be adapted to the length of extent or the bending angle of the provided curve. The larger the bending angle of the provided curve, the more wave crest elements  18  can be used. 
     The at least one wave crest element  18  extends according to  FIG. 1 b    in a circumferential direction  20 , extending around longitudinal axis  16 , of fluid line  10 .  FIG. 1 b    shows a view of fluid line  10  along longitudinal axis  16 . The representation of fluid line  10  corresponds in this case to a section along line A-A from  FIG. 1 a   , wherein longitudinal axis  16  is arranged orthogonally to the sectional surface. 
     Along circumferential direction  20 , wave crest element  18  has a varying distance  22  to longitudinal axis  16 . I.e. if wave crest element  18  is followed along circumferential direction  20 , distance  22  of wave crest element  18  to longitudinal axis  16  changes. Various angle positions of the wave crest element  18  along circumferential direction  20 , which can also be referred to here as circumferential positions, have different distances  22  to longitudinal axis  16 . 
     This brings about that wave crest element  18  is formed to have varying flexibility at the various circumferential positions. The local flexibility of wave crest element  18  can thus be adjusted so that it corresponds to the required local flexibility for generating a curve in fluid line  10 . Regions which are supposed to form an outer radius of the curve have increased flexibility, in which distance  22  are increased in these regions up to maximum distance  24 . The remaining regions in which an inner radius of the curve should be formed have smaller or no increased distances  22  at their circumferential positions. 
     In this case, wave crest element  18  comprises a first circumferential position at which wave crest element  18  has maximum distance  24  to longitudinal axis  16 . The first circumferential position is diametrically opposite a further circumferential position at which wave crest element  18  has minimum distance  14  to longitudinal axis  16 . 
     Wave crest element  18  furthermore extends in circumferential direction  20  only around a partial circumference of wave form portion  12 . In this case, wave crest element  18  comprises a first end region  30  and a second end region  32 . At both end regions  30 ,  32  of wave crest element  18 , varying distance  22  is reduced from maximum distance  24  proceeding in circumferential direction  20  until it corresponds to minimum distance  14  at a circumferential position outside wave crest element  18 . Varying distance  22  consequently increases between the two end regions  30 ,  32  continuously up to maximum distance  24 . A circumferential position with a maximum flexibility and a circumferential position with a minimum flexibility lie diametrically opposite one another in circumferential direction  20 . When a curve  36  is created in fluid line  10 , the flexibility of the circumferential position with maximum distance  24  to longitudinal axis  16  is therefore primarily deformed and the circumferential position with minimum distance  14  to longitudinal axis  16  is deformed to a small degree or not at all. 
     The two end regions  30 ,  32  are connected to one another in circumferential direction  20  outside wave crest element  18  in wave form portion  12  by a wave-free wall portion  26 , which can also be referred to as a smooth region. Wave-free wall portion  26  has in this case a smooth wall which has no waves in a direction along longitudinal axis  16  and in circumferential direction  20 , rather is formed to be smooth. Moreover, wave-free wall portion  26  is arranged at minimum distance  14  from longitudinal axis  16 . The distance of wave-free wall portion  26  to longitudinal axis  16  can furthermore be constant over its entire surface. 
     This brings about that, in order to produce a curve in fluid line  10  after a bending process of the wave form portion  12 , free wall portion  26  provides a non-corrugated edge surface for the fluid flow arranged in fluid line  10  on an inner radius of the curve. A fluid flow will thus only have a low degree of friction and turbulence on the inner radius of the curve. This avoids an interruption in the fluid flow from wave-free wall portion  26  so that vortices and thus a drop in pressure in fluid line  10  are reduced or avoided. 
       FIG. 2  shows fluid line  10 , in the case of which wave form portion  12  is bent and provides a curve  36  in fluid line  10 . Curve  36  has in this case an outer radius  38  and an inner radius  40 . Wave crest elements  18  with wave trough elements  34  therebetween extend in circumferential direction  20  over the region of curve  36  which is arranged on outer radius  38 . The plurality of wave crest elements  18  in interaction with wave trough elements  34  are arranged along outer radius  38  and form along longitudinal axis  16  the wave form of wave form portion  12 . The region around inner radius  40  of curve  36  is free from wave crest elements  18 . 
     Greater flexibility of the material of fluid line  10  by means of wave crest elements  18  is thus provided on outer radius  38  of curve  36  than on inner radius  40  of curve  36 . This brings about that the material on outer radius  38  of curve  36  can be stretched along longitudinal axis  16  without a large degree of effort. By varying distance  22  in circumferential direction  20 , the flexibility of the material which is provided by wave crest elements  18  is reduced up to end regions  30 ,  32  of wave crest elements  18 . 
     As a result of this, the local stretching of wave form portion  12  is likewise reduced at these positions. I.e., along circumferential direction  20 , the material of fluid line  10  is subject to a varying degree of stretching depending on distance  22  of wave crest element  18 . No stretching of the material is performed any more at inner radius  40  of curve  36 . Neutral axis  42  of fluid line  10  is arranged at this position. 
     Wave-free wall portion  26  is neither compressed nor stretched at neutral axis  42 . A slight stretching of wave-free wall portion  26  which is facilitated with the start of end regions  30 ,  32  as a result of the increase in the flexibility of wave form portion  12  is performed in the direction of wave crest elements  18 . 
     As a result of this, vortices in a fluid flow which flows through fluid line  10  and through curve  36  are avoided. As a result of the avoidance of vortices in the fluid flow, a drop in pressure in the fluid flow is furthermore reduced or even avoided. 
       FIG. 3  shows a diagram  44  that plots the difference of the local distance of a circumferential position of a wave crest element  18  to minimum distance  14  against the circumferential angle in circumferential direction  20 . The difference is standardized to the maximum difference, i.e. the difference between maximum distance  24  and minimum distance  14 . The circumferential angle is represented here from 0° to 180°, wherein it is assumed that, in the case of a circumferential angle of 180°, the circumferential position of wave crest element  18  is arranged with maximum distance  24 . The distance profile in circumferential direction  20  provides a non-circular contour. Starting from the 0° position, diagram  44  shows the distance profile in circumferential direction  20  and in the opposite direction to circumferential direction  20 . I.e. that diagram  44  only shows half a rotation around the longitudinal axis in circumferential direction  20  or counter to circumferential direction  20 . 
     A first distance profile  46  of wave crest element  18  in circumferential direction  20  is sinusoidal in this case, wherein the minimum distance is present between an angle range between 0° and 40° and the sinusoidal profile begins from the angle position 40°. I.e. wave-free wall portion  26  or smooth region covers, in circumferential direction  20 , an angle between 0° and 180°, preferably between 0° and 120°, further preferably between 0° and 80°. The maximum of first distance profile  46  is arranged in the case of angle position 180°. 
     A second distance profile  48  has a form which corresponds to the square of a sine. Second distance profile  48  initially rises to a lesser extent than first distance profile  46 . In the case of larger circumferential angles, the gradient of second distance profile  48  is, however, larger than the gradient of first distance profile  46  so that second distance profile  48  at the 180° position also has maximum distance  24 . 
     The two distance profiles  46 , 48  merely show examples of varying distance  22  along circumferential direction  20  of a wave crest element  18 . Other profiles of the distance are consequently not ruled out and can likewise be applied. In particular, in circumferential direction  20 , the angle range of wave-free wall portion  26  or of wave crest element  18  can be formed to be larger or smaller than explained in this exemplary embodiment. 
     The invention is not restricted to one of the embodiments described above, but rather can be modified in various ways. 
     All of the features and advantages which proceed from the claims, the description and the drawing, including constructive details, spatial arrangements and method steps, can be essential to the invention both on their own and in the wide range of combinations. 
     LIST OF REFERENCE NUMBERS 
       10  Fluid line 
       12  Wave form portion 
       14  Minimum distance 
       16  Longitudinal axis 
       18  Wave crest element 
       20  Circumferential direction 
       22  Varying distance 
       24  Maximum distance 
       26  Wall portion 
       28  Line portion 
       30  First end region 
       32  Second end region 
       34  Wave trough element 
       36  Curve 
       38  Outer radius 
       40  Inner radius 
       42  Neutral axis 
       44  Distance/angle diagram 
       46  First distance profile 
       48  Second distance profile