DE102016219813A1 - Connection of an air spring - Google Patents

Abstract

Connection (1) of an air spring, by means of which an end region of an air spring bellows (8) is fastened to a clamping base (10) of an attachment (7) of the air spring, wherein in the region of the connection (1) a sealing means (4) is provided.

Description

The invention relates to a connection of an air spring according to the preamble of claim 1.

Air spring bellows of air springs are usually attached to a clamping base of an attachment, e.g. a piston or a lid clamped by means of a clamping ring. The internal pressure bellows of an air spring is pulled on the bound bellows depending on the direction and size of the respective operating state of the air spring. The high internal pressure air from the inside of the air spring tries to get between the bellows and the clamping base and to find a way into the environment. If this happens, there will be a leak or leakage. In order to ensure the tightness of the clamping connection, the contact pressure between the bellows and the clamping base on at least one peripheral circumferential line must be greater for all aging and temperature operating conditions than the peak pressure ever occurring in the air spring interior.

This is achieved according to the prior art by the air bag is clamped with the highest possible compression at the terminal base, so that as much clamping pressure in the brand new clamping is present. One problem is that with aging of the high preload materials and associated creep, especially in the elastomer of the bellows, the clamping pressure decreases sharply over time. If further thermal shrinkage processes take place, especially when operating at low temperatures, e.g. minus 30 ° C, the contact pressure of the clamp can locally lower under the existing internal pressure of the air spring and the air spring is leaking and gets into a critical condition.

After DE 10 2008 025 905 A1 For better connection of the attachment of an air spring bellows to an attachment in the contact area, a chemical compound is produced which can be realized by an adhesive. The chemical compound or adhesive is produced between the inside of the bellows and the clamping base with or without simultaneous clamping by a clamping ring. As a result, a residual tightness is to be generated, which prevents the escape of air in the critical state.

In practice it turns out that the bonding of materials from which a clamping base usually consists, e.g. Aluminum alloys, KTL-coated steel, galvanized surfaces, polyamide 6.6, with an elastomer bellows is difficult. In particular, the chemical bond between elastomer and adhesive is problematic due to the complex chemical composition of the elastomer and the high deformations in the interface between the surfaces. On the one hand, the chemical compound can only be made high-strength and durable if the surfaces are clean and free from contamination. However, this is technically difficult to implement with elastomers.

Due to the elastomer production, the bellows surface is exposed to many technical auxiliaries, which must be cleaned before applying the adhesive. This succeeds only very imperfectly. On the other hand, mixing components of the elastomer diffuse outwards during operation (this is a desired process, for example for the aging protection of the elastomer) and thus act in a similar way to surface corrosion, which also deleteriously counteracts many other bonds and thus weakens or destroys the chemical compound during operation.

In order to ensure the above-described disadvantages and the strength of the clamping under load, attention is usually paid to the shape and height of the clamping contour and the highest possible bellows compression. However, even a particular form and height of a clamping contour can not readily provide adequate pressure tightness of the clamping.

It is therefore an object of the invention to provide an improved connection of an air spring bellows with an attachment.

The problem underlying the invention is achieved with the features of the independent claim.

According to the invention, a connection of an air spring is provided, by means of which an end region of an air spring bellows is fastened to a clamping base of an attachment part of the air spring, a sealing means being provided in the region of the connection. Preferably, the attachment is an air spring cover or an air spring piston. In this case, the air bag is preferably jammed with the attachment.

It has proven to be advantageous to use for a pressure-tight connection of an air spring bellows to an attachment no chemical compound by means of an adhesive, but to use a sealant.

It is known to the person skilled in the art that preferably a sealant does not contain a chemical compound enters with the end of the air spring bellows and the clamping base.

Thus, the person skilled in the art also knows that preferably a sealing means enters into a physical connection with the end region of the air spring bellows and the clamping base.

Preferably, the sealant is viscous. A permanently viscous sealant which does not cross-link or chemically bond with the bellows or the clamp bottom is particularly advantageous because it cures by polymerization or crystallization by itself.

Advantageously, the permanent-viscous sealant, in contrast to an adhesive has a self-healing effect. The self-healing of the adhesion is of great importance if the adhesion is interrupted or the surface preparation is insufficient, e.g. Diffuse substances out of the bellows or use surface corrosion on the clamping surface. In that case, a sealant which produces adhesion on a physical basis can, to a limited extent, penetrate the surface contamination, build up a new adhesion to the base material and thus maintain the sealing effect for a longer time. In contrast, a chemically generated compound is not self-healing. If a chemical or adhesive bond is broken, then this is irreversible. Furthermore, a sealant is usually more stable to chemical or physical decomposition than an adhesive.

According to a preferred embodiment, the glass transition temperature of the sealant is below the operating temperature of the air spring. In this case, the sealant has a higher than average adhesion in the entire temperature range, but especially under cold on. As such sealants, for example, silicone oils, non-crosslinking rubber compounds, e.g. Butyl or natural rubber base or other non-crosslinked polymer composite melts.

According to another preferred embodiment, a chloroprene-based sealant comes into play. Highly crystallizing chloroprene types (for example Pattex) fulfill the requirements particularly advantageously because they crystallize especially under pressure and re-amorphize when exposed to temperature. Upon renewed cooling and pressure, the chloroprene-based sealants recrystallize again.

Advantageously, the crystallization causes an improved strength property of the sealant, wherein the property of the reversibility contributes to a self-healing effect of defects occurring due to stress in the crystallization phase. The utilization of this reversible process thus contributes to the fact that when the cold pressure of the clamping pressure decreases, the sealant develops useful strength properties and supports the weakening clamping.

According to a further preferred embodiment, the sealing means is arranged adjacent to a contact zone of the end region of the air spring bellows with the attachment. This is a particularly effective and easily accessible place for applying the sealant. The prevailing in the inner work dream of the air spring pressure acts directly on the sealant, thus the gap or the contact zone of air spring bellows is sealed to the clamping base of the attachment by the sealant.

According to a further preferred embodiment, the sealing means is arranged in the contact zone between the end region of the air spring bellows and the attachment. Alternatively or additionally, the sealing means may also be provided between the air spring bellows and the clamping base of the attachment, whereby the pressure tightness is additionally enhanced.

According to another preferred embodiment, a supply of the sealant is provided in a groove of the attachment. If a part of the sealant is lost or pressed into the clamping plate, the groove filled with sealing agent, preferably near the clamping base, provides a supply from which further sealing means can flow.

For the purpose of a secure connection with a high contact pressure, according to a further preferred embodiment, the end region of the air spring bellows is clamped to the clamping base of the attachment by means of a clamping ring. For this purpose, the sealant is converted by taking advantage of the physically lower viscosity at high temperatures in a heated state before the air bag is clamped on the clamping ring with the clamping ground.

Use is the connection of an air spring in an air spring system for a motor vehicle.

Further preferred embodiments of the invention will become apparent from the subclaims and the following description of exemplary embodiments with reference to the figures.

Show it

1 an exemplary connection of an air spring,

2a to 2c a Dichtmittelfließverlauf the exemplary compound, and

3a to 3d Various embodiments of a compound of the invention.

In 1 is an exemplary connection 1 an air spring, wherein an end portion of a bellows 8th with an attachment 7 the air spring is connected. attachment 7 may be a lid or piston of the air spring.

At the connection shown 1 is located at a contact zone 2 a part of the clamping ground 10 directly with part of the end portion of the bellows 8th directly to each other. In the further course of the connection 1 there is a gap 3 between clamping reason 10 and bellows 8th because of missing or too little contact pressure between the bellows 8th and clamping reason 10 , Therefore, gap will 3 in another area of the connection 1 with sealant 4 refilled. sealant 4 can completely along the circumferential direction at the connection 1 be provided.

On sealant 4 acts, for example, from the air spring inside the air spring, a differential pressure p, which sealant 4 in gap 3 push, this is through the flow direction 6 shown. At the interface of the sealant 4 is in each case for clamping reason 10 and to the bellows 8th a persistent adhesion 5 effective.

At the surface of the sealant 4 is due to the special way the connection works 1 always only the air pressure, which exceeds the contact pressure between bellows 8th and clamping reason 10 goes out. This will be sealant 4 only exposed to a pressure difference.

In the cold, when sealant 4 is significantly more viscous and only small gaps have to be sealed against the air, is the sealant 4 able to achieve sufficient tightness even at higher applied differential pressures. Here are the main advantages of the sealant 4 against a chemical compound (eg by adhesive or vulcanization) to wear. Due to the persistent good stickiness, the adhesion in conjunction with the stress-relieving viscosity is sufficient in order not to lose contact with the inner side of the bellows or the clamping surface. When loaded by the pressure difference, the sealant deviates from the internal pressure acting in the interior of the material in the leakage and thus presses into the gap 3 ,

The 2a . 2 B and 2c clarify the flow behavior of in 1 described sealant 4 in an open gap between clamping ground 10 and bellows 8th ,

To 2a becomes adjacent to the contact zone between bellows 8th to attachment 7 the sealant 4 intended. Due to the internal pressure of the air spring flows in 2 B sealant 4 further along the contact zone to the terminal ground 10 , In 2c is a sealant 4 flowed in a gap, which due to low contact pressures starting from a clamping ring 9 between attachment 7 and bellows 8th has resulted. This seals sealant 4 this gap particularly effective.

The maximum internal pressures of the air spring are always only for a short time (pressure peaks), so that the viscous sealant 4 can withstand this load. Only a long-lasting load by the pressure difference would lead to the flow of the sealant into the clamp into it. During the long-lasting static internal pressure, however, the clamping is tight and no air is applied to the sealant 4 past.

Especially when operating in heat when the sealant 4 becomes less viscous and thus could bridge worse existing column, there is usually no gap between Klemmgrund 10 and bellows 8th which it is to be dense. Because of the thermal expansion of the materials, the gaps which otherwise occur due to thermal shrinkage in the cold are compressed.

Because the sealant 4 good in connection with existing clamping contours of the clamping base 10 can be used, the clamping strength remains determined by the clamping base contouring. Thus, the mentioned disadvantage of weakening the clamping strength is compensated or does not come into play.

3a shows a further embodiment of the connection 1 , where bellows 8th turned over by clamping ring 9 on the clamping ground 10 , For example, an air spring piston 7 , is attached. This is the sealant 4 at the fold of the bellows 8th arranged outside the contact zone. Thus, the internal pressure of the air spring acts on the sealant 4 and seals connection 1 from. Because sealant 4 is constantly exposed to the internal pressure, it can not be pressed into the gap located there because of the contact pressure in the pressure region facing away from the clamping contour and thus remains in place.

3b shows a further embodiment of the connection 1 , where bellows 8th through clamping ring 9 for example, on the clamping base 10 , For example, an air spring cover 7 , is attached. This is the sealant 4 also arranged outside the contact zone. Thus, the internal pressure of the air spring acts on the sealant 4 and seals connection 1 from. Also in this case is the sealant 4 constantly exposed to the internal pressure, but remains in place.

3c shows a further embodiment of the connection 1 , where the bellows 8th through clamping ring 9 on the clamping ground 10 is attached. It is in the terminal ground 10 provided a groove into which the sealant 4 is inserted and thus is the groove with sealant 4 as a storage container.

3d shows another clamp connection 1 , where bellows 8th through clamping ring 9 on the clamping ground 7 is attached and the sealant 4 in the contact zone between bellows 8th and clamping reason 7 is arranged and the pressure tightness of the connection 1 improved.

LIST OF REFERENCE NUMBERS

1

 clamp connection

2

 contact zone

3

 gap

4

 sealant

5

 adhesion

6

 flow direction

7

 attachment

8th

 suspension bellows

9

 clamping ring

10

 clamp base

p

 differential pressure

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008025905 A1 [0004]

Claims (9)

Connection ( 1 ) an air spring, by means of which an end portion of a bellows ( 8th ) to a clamping ground ( 10 ) of an attachment ( 7 ), in particular an air spring cover or an air spring piston, the air spring attached, in particular jammed, is characterized in that in the region of the compound ( 1 ) a sealant ( 4 ) is provided. Connection ( 1 ) according to claim 1, characterized in that the sealing means ( 4 ) is viscous. Connection ( 1 ) according to claim 1 or 2, characterized in that the glass transition temperature of the sealant ( 4 ) is below the operating temperature of the air spring. Connection ( 1 ) according to one of claims 1 to 3, characterized in that the sealing means ( 4 ) based on chloroprene. Connection ( 1 ) according to one of claims 1 to 4, characterized in that the sealing means ( 4 ) adjacent to a contact zone ( 2 ) of the end region of the bellows ( 8th ) with the attachment ( 7 ) is arranged. Connection ( 1 ) according to one of claims 1 to 5, characterized in that the sealing means ( 4 ) in the contact zone ( 2 ) between the end region of the bellows ( 8th ) and the attachment ( 7 ) is arranged. Connection ( 1 ) According to one of claims 1 to 6, characterized in that a supply of sealant ( 4 ) in a groove of the attachment ( 7 ), in particular near the clamping base ( 10 ), is provided. Connection ( 1 ) according to one of claims 1 to 7, characterized in that the end region of the bellows ( 8th ) by means of a clamping ring ( 9 ) on the clamping ground ( 10 ) of the attachment ( 7 ) is jammed. Air spring with a connection ( 1 ) according to one of claims 1 to 8.

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