Flexible tubes
The present invention relates to a flexible tube with folding bellows and a plurality of convolutes formed in the wall of the tube and the folding bellows has a convolute which has two opposite bending zones and two restricted elongation zones, where the arrangement has the restricted elongation zones between the opposite bending zones, and the height of the external surface of the convolutes in the restricted elongation zones is below the height of the external surface of the convolutes in the bending zones but still above external surface of the tube, and the wall thickness of the flexible tube in at least one restricted elongation zone in at least one convolute, preferably in all convolutes, of the restricted elongation zones of the tube is specifically greater than the wall thickness in the bending zones.
1. A flexible tube having an internal surface and an external surface, with at least one folding bellows extending along at least a portion of the tube, the bellows comprising a plurality of adjacent convolutes formed in the wall of the tube and extending circumferentially around the tube, where the plurality of adjacent convolutes define a plurality of interspersed peaks and valleys transverse to an axial longitudinal direction of the tube, and the external surface between adjoining peaks and valleys is curvilinear in the axial longitudinal direction, wherein at least one convolute has two opposite bending zones and two opposite restricted elongation zones, with the restricted elongation zones between the opposite bending zones, and the height of the external surface of the peak of the at least one convolute in the restricted elongation zones is below the height of the external surface of the peak of the at least one convolute in the bending zones but still above the external surface of the tube, and the at least one convolute has a first wall thickness about the periphery of at least one restricted elongation zone and a second wall thickness about the periphery of the bending zones, wherein the first wall thickness is greater than the second wall thickness.
2. The flexible tube according to claim 1 , wherein the folding bellows has from 2 to 100 convolutes.
3. The flexible tube according to claim 1 , wherein each of the convolutes comprises the two restricted elongation zones and the two opposite bending zones, with the restricted elongation zones being opposite one another and between the bending zones, and the wall thickness of the flexible tube in all of the convolutes of the restricted elongation zones of the tube is specifically greater than the wall thickness in the bending zones.
4. The flexible tube according to claim 1 , wherein the flexible tube has a transition zone between the restricted elongation zones and the bending zones.
5. The flexible tube according to claim 1 , wherein the folding bellows has at least two convolutes, which in turn have two opposite bending zones and two restricted elongation zones, arranged between the bending zones, where the length of the convolutes in the elongation zones increases or decreases in a peripheral direction from a first convolute towards a second convolute.
6. The flexible tube according to claim 1 , wherein flexible tube is composed of a thermoplastic resin.
7. A flexible tube according to claim 1 , wherein the flexible tube has a circular, oval or elliptical cross section.
8. A method of for transporting fluids, comprising:
passing a fluid along the internal surface of the flexible tube according to claim 1 .
9. The method according to claim 8 , wherein the fluid is liquid or air.
10. The method according to claim 9 , wherein the liquid is a liquid coolant or a liquid fuel.
11. The flexible tube according to claim 1 , wherein the first and second wall thickness of the at least one convolute are in a direction transverse to the longitudinal axis of the tube about the periphery of the at least one convolute.
12. The flexible tube according to claim 1 , wherein a cross-section of the apex of the peaks and a cross-section of the base of the valleys in the longitudinal direction of the tube are circular segments.
13. A flexible tube having an internal surface and an external surface, with at least one folding bellows extending along at least a portion of the tube, the bellows comprising a plurality of adjacent convolutes formed in the wall of the tube and extending circumferentially around the tube, with each convolute comprising:
a circumferential peak extending transverse to an axial longitudinal direction of the tube, and
two opposite bending zones and two opposite restricted elongation zones, with the restricted elongation zones circumferentially between the opposite bending zones, wherein the height of the external surface of the peak in the restricted elongation zones is below the height of the external surface of the peak in the bending zones but still above the external surface of the tube, wherein a first wall thickness about a portion of the periphery of the restricted elongation zones is greater than a second wall thickness about a portion of the periphery of the bending zones.
14. The flexible tube according to claim 13 , wherein the first wall thickness and the second wall thickness extend in a radial direction along at least the apex of the peak of the convolute.