Spring and method for its manufacture

Abstract

Spring, in particular as a suspension spring for motor vehicles, consisting of a bellows spring provided with open areas (4) in order to reduce the circumferential forces, wherein the bellows spring consists of several meander springs arranged in a circle around a cylindrical cavity (2), wherein the individual meander springs are connected by radially extending and spaced-apart windings (3).

Description

The present invention relates to a spring and a method for its production.Springs, in particular load-bearing springs for motor vehicles, are manufactured, for example, as helical springs, as leaf springs, as meander springs, as bellows springs, etc., from metallic materials or from plastic. These known springs have a number of disadvantages. Thus, metallic springs have a higher weight than plastic springs, but springs made of plastic have high tendencies to settle and creep under load. Leaf springs require a large installation space, which is not available in particular in conventional motor vehicle architectures. Meander springs cannot be designed hollow on the inside, which is why a combined construction with an internal damper cannot be implemented. In bellows springs, stresses occur in the circumferential direction, which can be critical for the operational stability of the spring.Proceeding from this prior art, it is therefore an object of the present invention to provide a spring which combines the advantages of the different types of springs in itself with a small installation space.This object is achieved according to the invention by a spring, in particular a support spring for motor vehicles, comprising a bellows spring which is provided with open regions in order to reduce the circumferential forces, and by a method for producing such a spring.The dependent claims contain advantageous refinements and embodiments of the invention.According to a preferred development, the bellows spring consists of a plurality of meander springs which are arranged in a circle around a cylindrical cavity.According to a preferred embodiment, the individual meandering springs consist of endless fiber-reinforced plastic belts.The fibers of the plastic strips are advantageously aligned mostly in the spring longitudinal direction.According to a preferred development, the individual meander springs are connected by radially extending wraps spaced apart from one another.The spring according to the invention can advantageously be produced by depositing endless fiber-reinforced plastic tapes on a multi-part core and subsequently connecting them by wraps spaced apart from one another.As a result of the configuration according to the invention, the spring has a weight advantage compared to metal springs. Compared to leaf springs, the support spring can be integrated into existing axle concepts. Compared to individual meander springs, the support spring has a cavity which can accommodate a damper element. No circumferential stresses occur with respect to closed bellows springs because the support spring is not closed in the circumferential direction.Further details, features and advantages of the invention are evident from the following description with reference to the drawings. The following are shown: FIG. 1 shows a schematic side view of a spring designed according to the invention, FIG. 2 is a section through the spring constructed according to the invention, FIG. 3 is an enlarged side view of the spring constructed according to the invention, FIG. 4 is a diagram of various spring characteristic curves; and FIGS. 5 to 8 show an illustration of the damage behavior of the spring according to the invention.The spring 1 according to the invention, which can be used in particular as a support spring for motor vehicles, consists of a bellows spring which-as can be seen from FIGS. 1 to 3-is not formed closed in the circumferential direction but rather has open regions 4, by means of which the occurrence of circumferential stresses can be prevented or reduced.The bellows spring can also consist of several meander springs, which are arranged circularly around a cylindrical cavity 2.The individual meander springs are then formed as endless fiber-reinforced plastic belts, the fibers of which are ideally aligned mostly in the spring longitudinal direction.The individual meander springs are connected by wraps 3 spaced apart from each other such that the shape of a bellows is shown in longitudinal section.The spring 1 according to the invention can be produced by depositing endless fiber-reinforced plastic strips on a multi-part core and subsequently connecting them by wraps 3 spaced apart from one another.FIG. 4 shows how the spring characteristic curve of the spring 1 according to the invention can be adapted to different requirements. According to their design, their dimensioning and / or their geometry, the spring characteristic curve can run progressively, degressively or linearly. The spring characteristic curve can be coincident with the spring axis, parallel to the spring axis, or oblique or C- or S-shaped, wherein the spring 1 according to the invention counteracts arising transverse forces.FIGS. 5 to 8 show the behavior of the spring 1 according to the invention in the event of damage. FIG. 5 shows a purely schematic illustration, FIG. 6 a view and FIGS. 7 and 8 a longitudinal section of the spring 1.In Fig. 5, a broken spring 1 is shown at the top in an unloaded state and at the bottom in a loaded state. If a break occurs in the region of a winding 4, the adjoining flanks contact one another in the event of a compressive load, as can be seen at the bottom in FIG. 5.In FIGS. 6 and 7, a view of an unbroken spring 1 on the right can be seen on the left. The spring 1 is shown in the unloaded state. If the spring 1 shown on the left breaks, for example, at the dashed line, the upper part of the spring 1 with the wraps 4.1 and 4.2 slides into the lower part of the spring 1, so that the wrap 4.2 comes to lie close to the wrap 4.3, as can be seen on the right in FIGS. 6 and 7, respectively.In Fig. 8, which shows the spring 1 in loaded condition, a broken spring 1 is seen on the left, and a broken spring 1 on the right. In the loaded state, the individual folds of the bellows are pushed together, as can be seen on the left in FIG. 8. When the spring 1 has broken, the broken part of the bellows remains between the individual folds of the bellows. The individual parts are supported against one another (cf. on the right in FIG. 8 ).In this way, an extraordinarily good fail-safe behavior of the spring 1 according to the invention is achieved. Even in the event of extreme overloading with damage, the integrity and thus the high residual load-bearing capacity are maintained.The foregoing description of the present invention is for illustrative purposes only and is not intended to limit the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.List of reference characters1 Spring 2 Cavity 3 Winding 4 Region

Claims

Spring, in particular as a load-bearing spring for motor vehicles, comprising a bellows spring which is provided with open regions (4) in order to reduce the circumferential forces, wherein the bellows spring comprises a plurality of meander springs which are arranged in a circle around a cylindrical cavity (2), wherein the individual meander springs are connected by radially extending wraps (3) spaced apart from one another.Spring according to claim 1, wherein the individual meander springs consist of endless fibre-reinforced plastic belts.Spring according to claim 2, wherein the fibers of the plastic strips are mostly aligned in the spring longitudinal direction.Method for producing a spring, in particular as a load-bearing spring for motor vehicles, comprising a bellows spring which is provided with open regions (4) in order to reduce the circumferential forces, wherein endless fibre-reinforced plastic tapes are deposited on a multipart core and are subsequently connected by wraps (3) spaced apart from one another.Method according to claim 4, wherein the bellows spring consists of a plurality of meander springs arranged circularly around a cylindrical cavity (2).Method according to claim 4 or 5, wherein the individual meander springs consist of endless fibre-reinforced plastic belts.Method according to claim 6, wherein the fibers of the plastic strips are mostly aligned in the spring longitudinal direction.

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