FLEXIBLE SPRING ELEMENT MADE OF A FIBRE-PLASTIC COMPOSITE MATERIAL

Abstract

A flexible spring element is made of a fiber-plastic composite material and has a cover layer made of a first fiber-plastic composite material on each of two outer sides lying opposite one another. Fibers are aligned parallel relative to one another at least in bundles within the cover layers and run parallel to the outer side associated with the respective cover layer. A curved portion extends where a center plane of the unloaded flexible spring element runs in a curved manner in a longitudinal direction of the flexible spring element. At least one longitudinal portion extends where the center plane of the unloaded flexible spring element has no significant curvature or has a reversal of curvature. In the curved portion the flexible spring element has a spacing extending element arranged between the two cover layers that is made of a different material than the two cover layers.

Claims

1.-8. (canceled)

9. A flexible spring element (1) made of a fiber-plastic composite material (4, 22), comprising two cover layers (2, 3) made of a first fiber-plastic composite material (4) on each of two outer sides (9, 10) lying opposite one another, wherein fibers (5) within the cover layers (2, 3) are aligned parallel relative to one another at least in bundles and run parallel to the outer side (9, 10) associated with the respective cover layer (2, 3); at least one curved portion (13, 14, 25), in which a center plane (8) of the unloaded flexible spring element (1) running with equal spacing between the two cover layers (2, 3) runs in a curved manner in a longitudinal direction (7) of the flexible spring element (1); at least one longitudinal portion (15, 16, 17) in which the center plane (8) of the unloaded flexible spring element (1) either has no significant curvature or has a reversal of curvature, wherein in an intended deflection of the flexible spring element (1), a cover layer portion (18) arranged directed outwardly in the curved portion (13, 14, 25) is subjected to tensile loading and an opposing cover layer portion (19) directed inwardly in the curved portion (13, 14, 25) is subjected to compressive loading, wherein the flexible spring element (1) comprises exclusively the two cover layers (2, 3) in the at least one longitudinal portion (15, 16, 17), and wherein the at least one curved portion (13, 14, 25) the flexible spring element (1) comprises a spacing extending element (20, 21) made of a different material than the two cover layers (2, 3) arranged between the two cover layers (2, 3).

10. The flexible spring element (1) according to claim 9, wherein the material of the spacing extending element (20, 21) is a second fiber-plastic composite material (22) with fibers (23), a length of which is less than 1 mm.

11. The flexible spring element (1) according to claim 10, wherein the fibers (23) in the second fiber-plastic composite material (22) are arranged undirected.

12. The flexible spring element (1) according to claim 10, wherein the second fiber-plastic composite material (22) comprises a matrix plastic material (6) corresponding to the two cover layers (2, 3).

13. The flexible spring element (1) according to claim 9, wherein the center plane (8) in the at least one curved portion (13, 14, 25) of the flexible spring element (1) has a change of direction of more than 150°.

14. The flexible spring element (1) according to claim 9, wherein the flexible spring element (1) comprises at least two curved portions (13, 14, 25) separated from one another by a longitudinal portion (15, 16, 17) and curved in different directions, so that the center plane (8) has an S-shaped progression over these two curved portions (13, 14, 25).

15. The flexible spring element (1) according to claim 9, wherein the first fiber-plastic composite material (4) of the two cover layers (2, 3) comprises fibers (5) oriented unidirectionally in the longitudinal direction (7) of the flexible spring element (1).

16. The flexible spring element (1) according to claim 15, wherein a length of the fibers (5) in a longitudinal direction (7) extends over the entire flexible spring element (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] An exemplary embodiment, which is shown schematically in the drawing, is explained in greater detail below.

[0023] FIG. 1 is a schematic sectional view of a flexible spring element with an S-shaped progression.

[0024] FIG. 2 is a schematic sectional view of the flexible spring element shown in FIG. 1 along a line II-II in FIG. 1.

[0025] FIG. 3 is a schematic sectional view of the flexible spring element shown in FIG. 1 along a line in FIG. 1.

[0026] FIG. 4 is a schematic sectional view of a flexible spring element with several curved portions, which element is intended and suitable for use in a motor vehicle.

[0027] FIG. 5 is a schematic sectional view of a flexible spring element that is differently configured, but likewise provided for use in a motor vehicle.

DETAILED DESCRIPTION

[0028] A flexible spring element 1 depicted in various views in FIGS. 1 to 3 has two cover layers 2, 3, which are each produced from a first fiber-plastic composite material 4. In each of the two cover layers 2, 3, endless fibers 5 are arranged in a matrix plastic material 6 such that the fibers 5 extend in a longitudinal direction 7 over the entire flexible spring element 1. The longitudinal direction 7 corresponds to the progression of a center plane 8, which runs between two outwardly directed outer sides 9, 10 of the two cover layers 2, 3 equally spaced from the two outer sides 9, 10 respectively. In the exemplary embodiment depicted as an example, the progression of the center plane 8 also corresponds to the progression of a neutral fiber, which in the event of an intended force F respectively transverse to the longitudinal direction 7 at both end areas 11, 12 of the flexible spring element is not loaded. It is likewise conceivable, however, that the two cover layers 2, 3, for example, do not have the same thickness, so that the center plane 8 does not necessarily have to correspond to the progression of the neutral fiber.

[0029] The center plane 8 has an S-shaped progression. The flexible spring element 1 has two curved portions 13, 14 with a curved progression varying by approximately 180°, which portions are arranged respectively between two longitudinal portions 15, 16, 17. The two end areas 11, 12 are each formed by a longitudinal portion 15, 17, in which the flexible spring element 1 has an approximately linear progression of the center plane 8. Likewise formed between the two curved portions 13, 14 is a longitudinal portion 16, in which the center plane 8 runs approximately linearly and has a curvature reversal from the first curved portion 13 to the second curved portion 14.

[0030] In the longitudinal portions 15, 16 and 17, the two cover layers 2, 3 lying directly adjacent to one another are connected to one another, as depicted schematically in FIG. 3. The fibers 5 embedded into the matrix plastic material 6 of the cover layers 2, 3 run substantially parallel to the respective outer sides 9, 10 of the pertinent cover layer 2, 3 and extend in a longitudinal direction 7 over the entire flexible spring element 1. The orientation of the individual fibers 5 is accordingly perpendicular to the image plane in the sectional view depicted in FIG. 3 and runs within the image plane in the sectional view depicted in FIG. 1. In the event of a force F acting as intended on the flexible spring element, the fibers 5 are subjected to tensile loading substantially along the outer side portions 18 directed outwardly in the curved portion 13, 14 and subjected to compressive loading along the outer side portions 19 directed inwardly in the curved portion 13, 14.

[0031] A spacing extending element 20, 21 is formed in each of the two curved portions 13, 14. The spacing extending element 20, 21 produces a greater spacing between the outwardly directed outer side portions 18 and the inwardly directed outer side portions 19 of the two cover layers 2, 3 within the curved portions 13, 14 and thereby produces advantageous spring properties of the flexible spring element 1 in the region of the relevant curved portion 13, 14.

[0032] The two spacing extending elements 20, 21 have an approximately crescent-shaped design. The spacing extending element 20, 21 arranged in the respective curved portion 13, 14 between the two cover layers 2, 3 here has a continuously varying thickness in the longitudinal direction, so that the spacing extending element 20, 21 becomes continuously thicker starting out from a first end that tapers to a point and has a maximum thickness in a central area, to taper increasingly towards the opposing second end and likewise to taper to a point again. In this way abrupt thickness changes in the flexible spring element 1, which according to experience can lead to loading peaks and often extremely high and if applicable excessive loading during an intended use of the flexible spring element 1, can be avoided. The two spacing extending elements 20, 21 do not necessarily have to be configured symmetrically to the center plane 8.

[0033] Each of the two spacing extending elements 20, 21 is made of a second fiber-plastic composite material 22. The second fiber-plastic composite material 22 has the same matrix plastic material 6 as the first fiber-plastic composite material 4, so that the spacing extending elements 20, 21 are bonded substance-to-substance and homogeneously to the two adjacent cover layers 2, 3 without the mechanical strength of the flexible spring element 1 forming any impairing boundary surfaces between the spacing extending elements 20, 21 and the adjacent cover layers 2, 3.

[0034] Arranged in the matrix plastic material 6 of the second fiber-plastic composite material 22 are short fibers 23 of a preferably uniform length of between 1 mm and 5 mm. The short fibers 23 are oriented undirectedly in the spacing extending elements 20, 21, so that a substantially homogeneous distribution and a distribution oriented in all directions of the short fibers 23 is present in the matrix plastic material 6 of the second fiber-plastic composite material 22.

[0035] The dimensions of the spacing extending elements 20, 21 are dimensioned in particular with regard to the respective thickness transversely to the progression of the center plane 8 in such a way that the flexible spring element 1 has advantageous spring properties within the envisaged area of the force normally occurring and damage to the flexible spring element 1 is largely excluded. At the same time, the cover layers 2, 3 are also dimensioned so that an intended use of the flexible spring element 1 is possible beyond the envisaged duration of use and yet the minimum material is expended for the cover layers 2, 3 and the spacing extending elements 20, 21, so that the flexible spring element 1 has advantageous spring properties with a particularly low own weight.

[0036] In FIGS. 4 and 5, a flexible spring element 1 is depicted respectively with more than two, or with four curved portions 24 in total. The individual curved portions 24 are each arranged between longitudinal portions 15, 16, 17 adjoining on both sides. Each of the flexible spring elements 1 shown by way of example in FIGS. 4 and 5 has several flexible spring portions configured in an S-shape and passing into one another. Arranged in each of the four curved portions 24 is a spacing extending element 25, which consists of the second plastic material 22 with the short and undirected fibers 23, which are embedded into the matrix plastic material 6.

[0037] The individual spacing extending elements 25 do not have to have a corresponding shape. On the contrary, the individual spacing extending elements 25 are adapted to the progression 7 of the respective flexible spring element 1 or to the progression 7 of the pertinent curved portion 24.

[0038] In the exemplary embodiment depicted in FIG. 4, the two end areas 11, 12 are oriented approximately parallel to one another and run in opposed directions, wherein an intended force predetermined by the definition of the flexible spring element 1 acts perpendicularly on the two end areas 11, 12. In the exemplary embodiment depicted in FIG. 5, the two end areas 11, 12 are likewise oriented parallel to one another and likewise run in opposed directions, but an intended force acts approximately in the direction predetermined by the orientation of the end areas 11, 12 or oriented in parallel to the two end areas 11, 12.