MXPA06010522A - Pneumatic spring u-bellows made of elastomeric material - Google Patents

Abstract

Disclosed are U-bellows for a pneumatic spring, which are made of elastomeric material and comprise a tensile support arrangement that is embedded in the bellows wall (1), extends along the entire length of the bellows, and is composed of rubber-coated cord fabric layers (3, 4). Said U-bellows for a pneumatic spring encompass a non-symmetric tensile support arrangement in which the single outer fabric layer (3) or the several outer fabric layers is/are provided with a stress-elongation behavior that is different from that of the single inner fabric layer (4) or the several inner fabric layers.

Description

PNEUMATIC ELASTOMERIC PRE-ROLLED HOSE FUSE The invention relates to a pneumatic pre-wound hose bellows of elastomeric material for a pneumatic spring with or without external guide, with a stability carrying arrangement embedded in the bellows wall, extending over the entire length thereof, of layers of cord fabric with rubber lining, whose cord threads are arranged in an inclined manner with inverted symmetry with respect to the circumferential direction of the bellows and which in the operating state forms a winding fold that varies with the molding processes. The pre-wound pneumatic hose bellows have been largely accredited, for example, as vehicle damping, in particular for the damping of the axles of the truck and bus wheels. In the foregoing, the pre-wound hose bellows are fixed at one end to a decoiler piston, which is usually made of metal or plastic. In the operating state, the piston moves inside the pre-wound hose bellows, which turns and forms a winding fold that unrolls on the unwinding piston.

The stability carrier arrangement absorbs the forces generated by the overpressure in the pneumatic pre-wound hose bellows. In the case of pneumatic pre-wound hose bellows, the cord fabric layer preferably consists of fully synthetic fibers, such as polyamide. With the cord threads the so-called cord fabric is formed, which comprises in the direction of the warp of numerous parallel contiguous cord threads, which are fastened loosely in the direction of the weft by a few thin threads at great distances. This layer of cord fabric is coated with a suitable rubber mixture, such as a polychloroprene mixture, and after oblique cutting, it is incorporated with two, four or six layers in the pneumatic pre-wound hose bellows, so that threads are in cross. Depending on the type of pneumatic spring, the cord threads of both cord fabrics in each case form a winding angle of approximately 40 ° to 80 ° with respect to the circumferential direction. In the foregoing, for profitable series production it is important that the angles of all fabric layers have inverted symmetry to the circumferential direction. That is, if a woven layer forms with the circumferential direction an angle of, for example, 60 °, also the layer of fabric that crosses the previous one must form an angle of 60 ° with the circumferential direction, forming the first angle of winding clockwise and the second winding angle, in a clockwise direction from the circumferential direction. Normally, the pre-wound pneumatic hose bellows for road vehicles are produced with two intersecting layers of fabric, in order to achieve a high flexibility of the pre-wound pneumatic hose bellows wall. Due to the increasing payloads of the vehicles and the decreasing installation spaces, at present the pneumatic springs must withstand increasing pressures, for example, in the range of around 10 bar and more. In order to withstand the high operating pressures, it would be conceivable to place four or six layers of cord fabric on the bellows wall. However, due to the small constitution of the pneumatic pre-wound hose bellows, the reinforcing stability carrier arrangement must be very thin, since an extremely small unwinding radius must be achieved. Due to the distance of the fabric layers in the outer fabric layer, a higher tensile stress is generated in the unwinding radius than in the inner tissue layer. In case of high pressures, the above can produce, for example, in a two-layer stability carrying arrangement, which the entire load of the pneumatic spring is only loaded by the external tissue layer and the inner tissue layer no longer cooperates. This implies a severe reduction of the bursting pressure of the bellows and a considerable reduction in the service life. German Patent DE 44 23 601 C2 discloses a pneumatic pre-wound hose bellows in which the service life would be improved by the use of a stability carrier arrangement with three layers of fabric. The configuration of these three layers of fabric is symmetrical to the center of the stability carrier arrangement. The central woven layer has a stability 'corresponding to the sum of both stabilities of the outer fabric layers, the external fabric layers being arranged symmetrically to the central layer and having the same stability carriers. With the use of three layers of fabric, the bonding surface between the rubber layers and the fabric is expanded, resulting in a longer service life. However, with this configuration the disadvantage mentioned at the beginning is not eliminated in that the outer fabric layer undergoes a greater elongation with the flexure of the bellows in the winding fold than the internal layers and, thus, must absorb proportionally more strength. Therefore, the invention is based on the object of providing a pneumatic pre-wound hose bellows having a stability carrying arrangement with winding angle of the fabric layers of inverted symmetry to the circumferential direction, in which the layers of The fabric undergoes a homogenous stress on the winding fold even under high operating pressures. Said objective is achieved when the pneumatic pre-wound hose bellows has an asymmetric stability carrying arrangement in which the external tissue layer or the various outer tissue layers have a different force-elongation behavior than the inner tissue layer or several layers of internal tissue. This configuration has the advantage that each layer of fabric of the bellows can be adjusted optimally to the respective operation requirement in the winding fold of the pneumatic pre-wound hose bellows. In one embodiment of the invention, the stability carrying arrangement has two distinct tissue layers. This configuration has the advantage that the wall of the pneumatic pre-wound hose bellows can be made very thin and flexible and, thus, the life of the bellows is improved. In another embodiment of the invention, the fabric layers of the stability carrying arrangement of the pneumatic pre-wound hose bellows have different yarn materials. In the above it is advantageous that if a highly resistant yarn is used for the outer fabric layer, the yarn strengths of both layers are approximately equal. With this, a particularly thin bellows wall can also be achieved. In another embodiment of the invention, the fabric layers of the stability carrying arrangement have different thicknesses of yarn. In this configuration it is advantageous that for both fabric layers the same material can be used, whereby for both layers the same conditions of adhesion between the yarns and the rubber material surrounding them can be adjusted. The configuration according to the invention of the stability carrying arrangements ensures that the fabric layers can be optimally adjusted to each other. Depending on the application, more rigid or flexible bellows walls of different thickness can be made with symmetrical winding angle of the fabric layers. With this, a long service life can be achieved even under high operating pressures. The invention is illustrated in more detail below with the help of the drawing. The figure shows a section of a pneumatic bellows wall 1 formed as a winding fold of a pneumatic pre-wound hose bellows. Said wall 1 has an outer covering rubber layer 2, an outer fabric layer 3, a layer of internal fabric 4 and an inner rubber layer 5. The fabric layers 3 and 4 are in each case coated on the inside and on the inside. outside with a rubber adhesion layer 6. All the mentioned layers 2 to 6 are fixedly vulcanized to each other. Due to the use of another material, the outer fabric layer 3 has a greater elongation than the inner tissue layer 4, said elongation being designed in such a way that the outer tissue layer 3 and the inner tissue layer 4 absorb during the operation the same request in the winding fold, the outer fabric layer 3 being more elongated than the inner tissue layer 4. By using a yarn material with greater elongation in the external woven layer 3 compared to the inner tissue layer 4, the first it can lengthen further and thus reach the largest necessary length in the winding fold for the outer layers of the bellows wall 1, with the same load absorption as the inner fabric layer 4. In the foregoing, the rubber adhesion layers 6 vulcanized together provide the necessary cohesion of the fabric layers 3 and 4. Thus, the stability carrying arrangement according to the invention of the pneumatic bellows wall 1 in the winding fold homogeneously distributes the load to be carried in the layers of woven 3 and 4, which produces a higher burst pressure and a longer service life.

List of references 1 Wall of a pneumatic pre-wound hose bellows 2 External covering rubber layer 3 External woven layer 4 Internal fabric layer 5 Internal rubber layer 6 Rubber adhesion layer eleven They present different yarn materials. A pneumatic pre-wound hose bellows according to claims 1 to 3, characterized in that the fabric layers (3, 4) of the stability carrying carrier of the pneumatic pre-wound hose bellows have different thread thicknesses.

Claims (3)

1. A pre-wound pneumatic hose bellows made of elastomeric material, with a stability carrying device embedded in the bellows wall (1), extending over the entire length thereof, of layers of woven cord (3, 4) with lining rubber, whose cord threads are arranged with an inclination in inverted symmetry with respect to the circumferential direction of the bellows, and which in the operating state forms a winding fold that varies with the molding processes, characterized in that the hose bellows The pneumatic winding has an asymmetric stability carrier arrangement, in which the external fabric layer (3) or the various outer fabric layers have a different force-elongation behavior than the inner fabric layer (4) or the various layers of fabric. internal

2. A pneumatic pre-wound hose bellows according to claim 1, characterized in that the stability carrying arrangement has two distinct layers of fabric (3, 4).

3. A pre-wound pneumatic hose bellows according to claims 1 and 2, characterized in that the fabric layers (3, 4) of the stability carrying carrier of the pneumatic pre-wound hose bellows