DD201721A5 - ROLL MEMBRANE TO AIR SPRINGS - Google Patents

Abstract

1. A rolling diaphragm for an air spring constructed as a double cone and providing at least two inserts having mutually crossing fibers, characterised in that in an unpressurised condition the diameters, changing along the generator, proceeding from the lower and upper edge regions of the diaphragm (2), and enlarging to mutually different degrees, define a profile in the form of a doubled truncated cone, and in that the value of the cord angle along the generator of the diaphragm profile changes continuously, the cord angle increasing in both directions from the maximum diameter of the diaphragm.

Description

Rollb al g

Field of application of the invention:

The invention relates to an improved rolling bellows for air springs, which are used for suspension of Fnhrzeughachsen of trucks, buses, semi-trailers and other vehicles.

Characteristic of the known technical solutions:

It is well known that the bellows of an air spring is already burdened by the filling with air. The amount of pressure forming in the air spring is largely determined by the degree of deflection or deflection. During operation, part of the bending and deformation work of the bladder or the hysteresis of the rubber is converted to heat. For this reason, the wall thickness of the bellows is given great importance, since the heat formation due to the bending and deformation work is higher for a thicker wall than for a thinner one.

Another relationship exists between the length dimension or the cross section and the degree of heating. Under the same conditions and at the same internal pressure, a membrane with a smaller diameter,

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or lesser length - i. Heat up more with a smaller airspace.

Of course, the deformation of the air spring bellows is also significantly influenced by the road conditions. The bellows are exposed on roads of average quality per hour to several thousand bounces and rebounds. Statistical studies have shown that the air bellows under variable travel, speed and load conditions, over a distance of 50 000 km 6.5 times 10 folding cycles subject, i. the bellows must endure multiples of this value throughout its lifetime. During rebound and rebound, the strength bearing cord fibers in the bladder wall are subjected to high compressive stress, with the compressive stress on the cord fibers being inherently more critical. It is therefore desirable to reduce the compressive stress to a minimum.

On the other hand, it is well known that one can use an air suspension in addition to the suspension for lifting certain parts of the suspension or the vehicle body. In particular, when a light, shock-sensitive cargo is transported in large quantities and a full load on the vehicle is practically unrealisable, an axle can be raised during operation, whereby almost identical suspension characteristics can be achieved even under extreme springing conditions. In many automobiles, trailers, semi-trailers, etc., the use of air springs came to the fore, since in this way clearly better suspension characteristics could be achieved.

Likewise, the air spring system is advantageously used in silo vehicles, container wagons, etc., since

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Not only improves the quality of the suspension during idling, but the whole vehicle is protected / In addition, a lifting of the wheels in the unloaded state is possible.

During operation of a motor vehicle, extreme suspension states are quite common. Such a condition can be observed when, for example during the ship or rail transport, the air pressure prevailing in the air spring drops to a very low value. This creates a negative curvature on the rolling bellows, which can lead to defective deformations and displacements when the vehicle is set up on the wheels.

A similar critical condition occurs when, for example, for a wheel change, the body must be raised, thereby resulting in the bellows reduced top pressure and a large volume.

It has been found that in extreme cases, the profile of the rolling bellows used previously changed and can be pushed at a repeated load and then easily destroyed.

To counter this deficiency, external stiffeners have already been proposed in the form of a metal shell. However, the solution had not led to the desired results, since the jacket slipped easily and thus could not fulfill its function.

From HU-PS 167 387 a solution is known in which to reduce the destruction process described above fabric inserts are provided which form rhombs with their superimposed fiber systems, wherein at least over a distance of the lateral surface of the zy-

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lindriseheh part of the bellows one or more other inserts are provided / which are attached to the former inserts and their fiber system subdivide the fiber warps mentioned in fiber triangles. This so-called "rolling bellows with belt insert" has a certain stiffness in the mentioned routes, which reduces the extent of the deformation and the defective influences.

Object of the invention:

By the invention, the indicated shortcomings are eliminated and proposed an improved rolling bellows, which has a longer life without a separate jacket or an additional belt with improved spring properties, V "'- - .. .V ''.' . ''''.'..;",. :. : '"·

Explanation of the essence of the invention;

The invention has for its object to develop a rolling bellows for air springs, in the cord structure, the tensile stress dominates and the compressive stress is reduced to a minimum. Another task is to avoid damaging the bellows at low pressures.

The essence of the invention is that a mutual support effect is achieved by modifying the profile of the bellows in the form of a double cone, wherein the resulting Kordwinkel stiffen the bellows and protect against deformation. The invention eliminates the existing deficiencies of the prior art. Compared with known diagonal transverse reinforcement air bellows, a rubber bellows with much more advantageous characteristics is proposed.

3590A

With respect to solutions with an outer support, the proposal according to the invention represents a much more contemporary version. According to the invention, air spring bellows, which are provided with a vulcanized, peripheral outer reinforcement, are developed further and their spring parameters are improved.

Embodiment;

The invention will be explained in more detail below using an exemplary embodiment. In the accompanying drawing

   '.' '- -. ''. '. "/

shows: '\

1 to 3: profiles of previously known, commonly used rolling bellows,

Fig. 4: the rolling bellows according to the invention.

The solution shown in Fig. 1 shows a rolling bellows, which is provided with a jacket. The height H of the cylindrical bellows is less than or equal to the diameter D, i. the ratio is H / D

^ 1, preferably 0.65-1

In this solution, the cord reinforcement consists of at least two intersecting inserts. The diameter of the bellows changes during the suspensions such that it remains constant in the section under the jacket, whereas in the sections without reinforcement one increase can be observed. The Kordwinkel the inserts in the vulcanized bellows is between 40 ° and 50 °.

The rolling bellows shown in Fig. 1 is only limited use and is used exclusively in buses. The disadvantage of this solution is that in

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the rebound (unloaded) condition of the coat often slips, whereby both the bellows and the cladding is destroyed. "'', ·.: ". ^: '· ^: ". - .; . ''. ^: ;. V -.-, '.-.;: ..

Fig. 2 shows a cylindrical or optionally one-sided, conically shaped rolling bellows, in which the cord fibers are arranged below an equilibrium angle. The length H of the cylindrical (or one-sided conical) rolling bellows 2 is equal to or exceeds the diameter D, i.

H = d or H = 1-2 D. The angles of the rolling bellows profile are,

^ _z ^ ⁹⁰ °:; '':'.'"'-''":''

or Y ₁ = 90 ° and

ί ;; = 85-75 °. : / ';' \\ . - ^{::: y} '. . '

In this case too, the cord reinforcement used consists of at least two interleaving inserts, the cord fibers enclosing the longitudinal axis at an angle under load and under pressure, under which the diameter can only change to a slight extent.

This training is much better than the solution shown in FIG. But even with this design, it comes in the unloaded state to suppressions.

In Fig. 3, the solution according to the aforementioned HU-PS 167 387 is shown. In this rolling bellows, the ratio of the height H to the average diameter D is the same.

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^H 7 ^D average; ^{H / D} average ⁼ ° ^'65 " ² '

1 ⁼

The stiffening in section 1 has succeeded in reducing the displacement. However, a complete elimination could not be achieved. Thus, this, quite advantageous solution still has the disadvantage that the sucking in the rebound in the unloaded state could not be eliminated. As a result, the rolling bellows can be damaged at a line in the region of the vulcanized belt ends, at which the tension accumulates.

There is also known a rubber bellows profile in which the flange of the bellows flexes outwards and is inextricably linked to the gripping metal structure. Also in this case, the functional range of the bellows is designed cylindric. The known disadvantages could not be eliminated here.

By the invention, the disadvantages of the known solutions are eliminated by the fact that the diameter of the bellows in the ground state, i. without overpressure, constantly changing along the outer jacket. Starting from the lower or upper flange of the bellows, the diameters differ from each other, constantly increasing and defining the profile of a double truncated cone.

The reinforcements of the bellows according to the invention consist of at least two inserts containing intersecting fibers, wherein the value of the cord angle along the bellows outer sheath constantly changes. from

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 ..largest. Starting diameter, where the cord angle is 25 to 40 °, et changes in one direction to 40 to 45 °, and in the other direction to 50 to 60 °. The cord angle is understood to mean an angle between the tangent of a selected point, a plane passing through the bellows and a plane perpendicular to the main axis of rotation of the bellows, and the cord fibers.

The solution according to the invention is shown in the unloaded state in FIG.

Starting from the upper and lower flange, the diameter of the bellows increases toward the middle up to a common maximum diameter. The height H of the rolling bellows according to the invention is suitably about 0.5 to 2.5 D max. Between the two flanges, the diameter takes the edge value D max. on. The conicity of the two truncated cones is different. The angle X ·, of the upper section

is 1 to 5, while the ο-the lower portion is between 2 to 10 °;

= 2 JT ₁ -;

The rolling bellows invention is made of natural or synthetic Katuschuk. The reinforcement is rayon, polyamide, glass or steel fiber. >

The bellows profile described above and the angular value of the reinforcing inserts changing along the outer jacket influence the function of the rolling bellows in a simple but advantageous manner. The fatigue of the reinforcement is reduced, at the same time the resistance to adverse influences in extreme conditions is increased, with all the advantages mentioned being achieved without additional inserts or a reinforcing jacket and without increasing the wall thicknesses.

Claims (4)

'»- 235 90α Erf'ndurigsanspr-: 1. Rolling bellows for air springs, characterized in that .ausgehend from the lower and upper chute of the rolling bellows (2) The bellows diameter along the generatrix is constantly changing in such a way that it increases to the center to different degrees and determines the profile of a double truncated cone and the bellows expediently has at least two inserts containing intersecting fibers, the value of Kordwinkels along the generatrix of the bellows profile also constantly changes. 2. rolling bellows according to item 1, characterized in that the cord angle starting from the maximum diameter, where it is 25 to 40 ° increases in one direction to 40 to 50 °, and in the other direction to 50 to 60 · 3. Rolling bellows according to item 1 or 2, characterized in that between a straight line which is tangent to the largest bellows diameter and parallel to the central axis of the bellows and an extension of the frustoconical outer shell enclosed angle) / ·, or Jj ₂ in the upper portion of Balges) f ^ = 1-5 and in the lower section V ₁ = 2-10 ° or i. ₂ «2 Jf ₁ to ί _λ μ V ₂ . 4. rolling bellows according to item 1 to 4, characterized in that the height of the bellows is 0.5 to 2.5 diameters and the ratio between height (H) and diameter (D) H f D. HienüL pages Zeidmungen - 11 - - 'jar - 235 9 04 7 Under pressure and during the suspension process, the diameter increases only to a certain extent. On the non-rolling surface, the increase in the diameter is smaller. In the rebound condition, the position is more stable. Damaged displacements, deformations do not occur. Another advantage of the invention Rollbalges is that the adverse compressive stress are significantly reduced, since in the first row, the tensile stress dominates. Furthermore, the wall thickness of the bladder (compared with the known solutions) is lower, which avoids the heating caused by the pressure and pressure deformation and their harmful effects. As a result of the fact that the diameter of the bellows and the cord angles in the reinforcing inserts, starting from the largest diameter, change asymmetrically in both directions, an extremely favorable reinforcement is achieved. With the help of the invention, the field of application of the air spring can be extensively extended. Equipped with the rolling bellows invention air spring can be used in various types of motor vehicles from buses to semi-trailers. It ensures optimum suspension, self-oscillation and lever action without the need for a separate jacket, belt or other additional element. -10 -