DE102020203171A1 - Air suspension strut with a protective bellows for transmitting a torque - Google Patents

Abstract

Air spring strut (1) for a motor vehicle, comprising an air spring (2) with an integrated shock absorber (3) for the suspension and damping of vibrations of a motor vehicle chassis, the air spring (2) comprising an air spring cover (4) and a rolling piston (5), wherein Between the air spring cover (4) and the rolling piston (5) a bellows (6) made of elastomeric material is fastened in a pressure-tight manner, whereby a volume-elastic pressure space (10) filled with compressed air is limited and the bellows (6) forms a roll fold (8) the rolling piston (5) rolls, the shock absorber (3) comprising a damper tube (12) and a piston rod (13) which can be immersed in the damper tube (12), the rolling piston (5) being non-rotatably attached to the damper tube (12) and the Piston rod (13) is connected to a damper bearing (14), the air spring cover (4) being rotatably mounted relative to the damper bearing (14) by means of a pivot bearing (20), a means for torque transmission (7) v is provided, which is coupled on the one hand to the air spring cover (4) and on the other hand to the rolling piston (5) in such a way that when the shock absorber (3) is rotated about a longitudinal axis (L) of the air spring strut (1) one of the rolling piston (5) outgoing torque (M) is transmitted to the air spring cover (4) via the means (7).

Description

The invention relates to an air suspension strut according to the preamble of claim 1.

An air suspension strut, as it is, for example, from the DE 103 20 501 A1 is known, is arranged between the motor vehicle chassis or a wheel carrier and the motor vehicle body. As a rule, the air suspension strut comprises an air spring and a shock absorber. The air spring fulfills the function of cushioning the wheel, while the shock absorber dampens the vibrations of the wheel or the motor vehicle body.

The air spring essentially consists of an air spring cover, a rolling piston and an elastomeric bellows clamped between them in a pressure-tight manner, which delimits a volume-elastic pressure space under compressed air. The rolling bellows is enclosed by a sleeve-shaped external guide and rolls on the rolling piston when it is compressed, forming a roll fold. The shock absorber arranged inside the air spring is connected on the one hand to the wheel carrier and on the other hand is mounted with its piston rod, which can be immersed in the damper tube, in a damper bearing of the air spring cover. The air suspension strut is connected to a body section of the motor vehicle via the damper bearing and corresponding fastening means. In addition, a pivot bearing is provided between the air spring cover and the damper bearing, which is due to the following circumstance.

Wheel-guiding air suspension struts are often used on the front axle of motor vehicles. Due to the fact that the shock absorber is indirectly attached to the wheel, the entire air suspension strut swings when the vehicle wheel is compressed and the shock absorber rotates when the steering movement occurs.

The axis kinematics caused by the operation leads to a torsional load on the bellows. The rolling piston, which is fixed to the shock absorber, absorbs its rotation and rotates relative to the longitudinal axis of the air suspension strut. This consequently leads to a rotation of the rolling piston relative to the air spring cover. The rolling bellows clamped between the air spring cover and the rolling piston consequently experiences a disadvantageous torsional force. The rolling bellows is twisted, which is very damaging, especially in the case of thin-walled and thread-reinforced rolling bellows, and can lead to failure of the air spring strut.

There are various solutions in the prior art to provide torsion compensation. There is another pivot bearing, for example. Also from the DE 10 2009 003 476 A1 famous. A bearing package is described here, which is provided between the upper connection of the rolling bellows on a cover part and the fastening of the damper bearing on the motor vehicle. The rotatable air spring cover reduces the negative effects of twisting on the bellows, but does not prevent them. The rolling piston initiates a rotation in the rolling bellows until the breakaway torque of the bearing assembly is reached. Only then does the torsion of the rolling bellows decrease, whereby it continues to be slightly twisted. Until the breakaway torque is reached and thereafter, the reinforcements of the bellows are stretched in a disadvantageous manner and thus damaged.

Alternatively, the DE 10 2004 048 828 A1 proposed a ball joint which is arranged between the rolling piston and the shock absorber. As a result, the shock absorber is movably supported within the rolling piston and the forces or deflections acting on the shock absorber are not transmitted to the rolling piston. The swivel joint compensates for these movements. Although this prevents the rolling bellows from twisting to some extent, this solution is disadvantageous in terms of its complexity and space requirements.

It is therefore the object of the invention to provide an improved air suspension strut in which torsional forces which disadvantageously act on the rolling bellows are largely reduced or prevented.

The object on which the invention is based is achieved with the features of the independent patent claim. Preferred embodiments emerge from the subclaims.

According to the invention, an air spring strut for a motor vehicle is provided, comprising an air spring with an integrated shock absorber for the suspension and damping of vibrations of a motor vehicle chassis, the air spring comprising an air spring cover and a rolling piston, a rolling bellows made of elastomeric material being fastened in a pressure-tight manner between the air spring cover and the rolling piston , whereby a volume-elastic pressure space filled with compressed air is limited and the rolling bellows rolls on the rolling piston with the formation of a roll fold, the shock absorber comprising a damper tube and a piston rod immersed in the damper tube, the rolling piston being non-rotatably attached to the damper tube and the piston rod with a Damper bearing is connected, wherein the air spring cover is rotatably supported by means of a pivot bearing with respect to the damper bearing, a means for torque transmission being provided, which on the one hand with the air spring cover and the other on the other hand coupled to the rolling piston in this way is that when the shock absorber is rotated about a longitudinal axis of the air suspension strut, a torque originating from the rolling piston is transmitted via the means to the air suspension cover.

This mechanism advantageously has the effect that no torsional force acts on the rolling bellows. As a result, its reinforcements are not stretched unnecessarily, which increases the service life of the bellows and the entire air suspension strut. In order for the torque transmission mechanism to work properly, the rolling piston must first be firmly connected to the damper tube of the shock absorber so that it cannot twist on the damper tube. For this purpose, the rolling piston can be positively connected to the damper tube in that the damper tube has a nose which engages in a groove in the rolling piston. In addition, the air spring cover must be rotatably mounted so that it absorbs the twisting of the rolling piston and rotates in the same direction. This means that the connection of the rolling bellows to the rolling piston and the connection of the rolling bellows to the air spring cover remain in almost the same position when moving about the axis of rotation. As a result, no adverse torsion acts on the rolling bellows. In contrast to the prior art, the rolling bellows is relieved immediately. He himself does not have to transmit any torque to the rotatably mounted air spring cover.

The means for torque transmission is preferably a protective bellows for protecting the rolling bellows, a multiplicity of stiffening means being provided in the protective bellows. The protective bellows usually present is preferably suitable as a means for torque transmission. This has two functions. In addition to protecting the rolling bellows from contamination, the protective bellows also acts as a power transmission medium. For this purpose, it is advantageous to make the protective bellows stiffened so that it does not buckle when it is twisted.

In order to prevent this, the stiffening means particularly preferably each run in the circumferential direction. They are distributed over the length of the protective bellows and arranged at a distance from one another.

According to a further preferred embodiment, the stiffening means are each arranged in a flank area between a fold valley and a fold tip of the protective bellows. So that the protective bellows does not buckle within its folds, its flank area is stiffened. This allows the torque to be transmitted better.

The stiffening means are preferably a local thickening of the protective bellows material. The stiffening of the protective bellows is achieved through an increased use of material at a defined point. In order to produce locally thicker areas in the material, the injection mold must have a corresponding shape.

Alternatively, the stiffening means are embedded threads or fabrics. Preferably fiberglass. The threads or fabrics are embedded in the material of the protective bellows in an injection molding process. These means also stiffen the protective bellows material.

According to a further preferred embodiment, the protective bellows is fastened with a first end to the air spring cover and with a second end to the rolling piston. So that the torque is effectively transmitted from the roll-off piston through the protective bellows to the air spring cover, it is advisable to fasten the protective bellows with its ends to these two air spring add-on parts.

The first end of the protective bellows is preferably fastened to the air spring cover in a form-fitting and / or force-fitting manner and the second end of the protective bellows is fastened to the rolling piston in a form-fitting and / or force-fitting manner. Preferably, the air spring cover and the rolling piston each have a plurality of axially extending pins and grooves for the form fit, which are arranged alternately in the circumferential direction. In addition, the ends of the protective bellows are preferably fastened with a clamping device for the frictional connection. The ends are placed and braced at the corresponding connection areas on the air spring cover and on the rolling piston. Alternating axially extending pins and grooves represent a specific shape of the wall of the air spring cover or rolling piston, to which the shape of the ends of the protective bellows is matched. The ends of the protective bellows are pushed axially onto the connection areas of the air spring cover and the rolling piston so that the ends rest against them in a form-fitting manner. The form fit ensures that the ends do not twist or slip on the connection areas. In addition, a frictional connection is effected by a clamping device. This also ensures that the ends do not twist and also remain in an axial position.

According to a further preferred embodiment, the turntable is a sliding or roller bearing. The rotational mobility of the air spring cover in relation to the damper bearing is generated by a sliding or roller bearing. An essential requirement of the plain or roller bearing is that it has low friction.

The air suspension strut is used in an air suspension system of a motor vehicle.

Further preferred embodiments of the invention emerge from the following description of an embodiment with reference to the figures.

• 1 ein beispielsgemäßes Luftfederbein in der Schnittansicht,
• 2 einen Schutzbalg mit Versteifungsmitteln im Detail,
• 3 das beispielsgemäße Luftfederbein in perspektivischer Ansicht,
• 4 eine obere Befestigung des Schutzbalgs, und
• 5 eine untere Befestigung des Schutzbalgs.

Show it

• 1 an exemplary air suspension strut in the sectional view,
• 2 a protective bellows with stiffening means in detail,
• 3 the exemplary air suspension strut in a perspective view,
• 4th an upper attachment of the protective bellows, and
• 5 a lower attachment of the protective bellows.

the 1 shows an example of an air suspension strut 1 consisting of an air spring 2 and an integrated shock absorber 3 , being air spring 2 an air spring cover 4th , a rolling piston 5 and a rolling bellows 6th includes. Inside air spring 2 is shock absorber 3 provided, taking shock absorbers 3 a damper tube 12th and a piston rod that can be immersed in it 13th includes.

Air spring 2 includes bellows 6th made of elastomeric material, with roll bellows 6th with air spring cover 4th and rolling piston 5 a pressure-tight and volume-elastic pressure chamber filled with compressed air 9 limited. A tubular roll bellows is used for this 6th with its upper end on the air spring cover 4th and with its lower end on the rolling piston 5 e.g. via clamping rings 10 attached to the connection areas of these air spring connection parts. With relative movements along a longitudinal axis L. of the air suspension strut 1 between air spring cover 4th and rolling piston 5 rolls bellows 6th with the formation of a roll fold 8th on the rolling surface of the rolling piston 5 away. In addition, roll bellows forms 6th another fold on the air spring cover 4th the end. At the same time is roll bellows 6th provided with embedded reinforcements. In addition, one can use the rolling bellows 6th at least partially enclosing external guide can be provided. The external guide limits the lateral expansion of the bellows 6th .

Rolling piston 5 is hanging on the damper tube 12th of the shock absorber 3 arranged and a lower end of the rolling piston 5 is on the wall of the damper tube 12th attached so that rolling piston 5 opposite damper tube 12th cannot be twisted. The one in damper tube 12th submersible piston rod 13th is with its upper free end in a shock mount 14th stored. Shock mount 14th comprises a first lower bearing part 15th , a second upper bearing part 16 and an elastomer part disposed therebetween 17th . Piston rod 13th becomes by means of a mother 18th on the lower bearing part 15th non-rotatably attached. The lower bearing part 15th is cup-shaped, made of a steel material and has a central through opening for the piston rod 13th on. Upper bearing part 16 is also made of a steel material and designed in the shape of a lid. The rubber ring in between 17th acts as a vibration damper. At the same time is the shock mount 14th effective as a cardan bearing and compensates for pivoting movements of the air spring strut 1 partially off. There piston rod 13th at the same time through an opening in the air spring cover 4th is inserted, pressure space must be 9 be sealed to the outside. There is a radial sealant for this 19th between piston rod 13th and air spring cover 4th intended. For this purpose, a corresponding groove can be made in the opening of the air spring cover 4th be introduced.

So that air strut 1 Can be connected to a body section of the motor vehicle, several fastening means 17th Action. These are in the shock mount 14th let in and are inserted through corresponding openings in the body section and then screwed. On the other hand is air strut 1 Can be connected to a wheel carrier of the motor vehicle via a damper eye (not shown). This regular installation position of the air suspension strut 1 determines the "top / bottom" orientation.

To protect the bellows from soiling 6th and especially its roll fold 8th is a protective bellows 7th intended. This is with its first upper end 21 on the air spring cover 4th and with its second lower end 22nd on the rolling piston 5 attached. It is attached using clamping rings 11 . These cause a frictional connection.

When a front wheel turns in, the air suspension strut experiences 1 an axis kinematics, which leads to a rotation V of the shock absorber 3 leads. In the event of a twist V of the shock absorber 3 or its damper tube 12th the rolling piston rotates 5 with. Because roll bellows too 6th fixed with rolling piston 5 is connected, this is also twisted. About the effect of torsional forces on the bellows 6th to minimize. is a pivot bearing 20th between air spring cover 4th and shock mounts 14th intended. This is to help that roll bellows 6th will not be damaged or torn off. Pivot bearing 20th is a plain or roller bearing. It allows air spring covers 4th around the longitudinal axis L. of the air suspension strut 1 to rotate. Thus, air spring cover can 4th that from the rolling piston 5 outgoing and from the rolling bellows 6th Record the transmitted torque and thus reduce it.

However, the pivot bearing is sufficient 20th not off to the on roll bellows 6th to completely minimize negative torsional forces. For this reason, a further means is provided according to the example, which a torque M. of rolling piston 5 on air spring cover 4th transmits. As a means of Torque transmission becomes protective bellows 7th used. A large number of stiffening agents are used for this purpose 23 intended. Protective bellows 7th is made of elastomeric material and has a multitude of folds. The folds run in the circumferential direction and form so-called fold valleys 28 and wrinkle tips 29 the end. In the material of the protective bellows 7th become the stiffeners 23 introduced, which also run in the circumferential direction. Stiffening agents 23 are preferred in flanks 30th of the protective bellows 7th between its fold valleys 28 and wrinkle tips 29 arranged. Stiffening agents 23 are designed as a pure local material thickening. Alternatively, stiffeners are used 23 than in the material of the protective bellows 23 embedded threads or tissue formed. By stiffening agents 23 , which essentially over the entire length of the protective bellows 7th are arranged distributed, this has a very high rigidity in the circumferential direction. Due to its folds, however, it retains its elasticity when the air spring strut springs in and out 1 at.

The stiffness of the protective bellows 7th is very important for a twist, because that of the rolling piston 5 outgoing torque should be on air spring cover 4th be transmitted. If damper tube 12th is rotated, the rolling piston rotates 5 with. Protective bellows 7th is with its bottom end 22nd firmly on the rolling piston 5 tied up. Hence the twisting of the rolling piston 5 to a torque M. , whereby the stiffened protective bellows 7th picks up the rotation. Because protective bellows 7th with its upper end 21 also tight with the air spring cover 4th connected and air spring cover 4th is rotatably mounted, the torque M. by means of the protective bellows 7th on air spring cover 4th transferred so that the air spring cover 4th twisted.

This mechanism relieves the load on the rolling bellows 6th which is otherwise adversely affected by torsion. Because of that rolling piston 5 and air spring cover 4th perform an almost identical twist, there is almost no torsional force on the bellows 6th on. This will be the reinforcement of the bellows 6th no longer stretched and its lifespan is increased. Roll bellows also transfers 6th hardly any torque on the air spring cover itself 4th .

the 2 shows in detail a section of the protective bellows 7th with a stiffening agent 23 .

In one flank 30th of the protective bellows 7th between a fold valley and a fold tip is a stiffening agent 23 arranged, which runs in the circumferential direction. Stiffening agents 23 is a local thickening of the material of the protective bellows 7th . Stiffening agents 23 lead to a stiffening of the protective bellows 7th so that it is in the area of its flanks 30th does not buckle. Alternatively, stiffener is used 23 a thread or fabric, which is injection molded in protective bellows 7th is embedded. The thread can consist of glass fibers, for example. They also ensure that the flanks 30th do not bend away when twisting.

3 shows the example of the air suspension strut again 1 in a perspective view. Air strut 1 is fastened via fasteners 17th connected to a connection point of the motor vehicle, so that damper bearings 14th is rotationally fixed with respect to the connection point. Below the shock mount 14th is pivot bearing 20th arranged, by means of which the non-visible air spring cover can be rotated. The upper end of the air spring cover is not visible 21 of the protective bellows 7th with tension ring 11 tightly clamped. Lower end 22nd of the protective bellows 7th is also with a tension ring 11 Tense at the not quite visible rolling piston.

A firm fixation of the protective bellows is required for the transmission of a torque 7th needed. For this purpose, the 4th and 5 special form-fitting between the end of the protective bellows and the connection point is shown.

4th shows the attachment of the upper end 21 of the protective bellows 7th on the air spring cover 4th . Between the air spring cover 4th and the end 21 of the protective bellows 7th there is a form fit by the outer wall of the air spring cover 4th a large number of axially extending pins 24 having. Between two tenons 24 is an axially extending groove 25th . The shaping of the end 21 of the protective bellows 7th is chosen so that its material is in a groove 25th between two tenons 24 intervenes. The shaping of the end 21 of the protective bellows 7th is still designed so that the tenons 24 are covered. Such a form fit is carried out at several points in the circumferential direction. This prevents the protective bellows 7th on the air spring cover 4th slipped in the circumferential direction. In addition, a frictional connection is brought about by the end 21 with a tension ring 11 radially against the wall of the air spring cover 4th is braced.

The same type of form and force fit also takes place on the rolling piston 5 how it the 5 can be found. The end 22nd of the protective bellows 7th engages positively in a groove 27 between the tenons 26th of the rolling piston 5 a so that protective bellows 7th cannot be turned off.

To the end 22nd of the protective bellows 7th Securing against pulling off in the axial direction causes the clamping ring 11 the additional frictional connection. This frictional connection is supported by a groove that runs all the way around in the rolling piston 5 is introduced and in which clamping ring 11 the material of the protective bellows 7th and at the same time partially seated in the groove. This will cause the end to be pulled off axially 22nd effectively prevented.

List of reference symbols

1

Air strut

2

Air spring

3

Shock absorbers

4th

Air spring cover

5

Rolling piston

6th

Rolling bellows

7th

Protective bellows

8th

Roll fold

9

Printing room

10

Clamping ring

11

Tension ring

12th

Damper tube

13th

Piston rod

14th

Shock mount

15th

first bearing part

16

second bearing part

17th

Elastomer part

18th

mother

19th

sealant

20th

Pivot bearing

21

first protective bellows legend

22nd

second protective bellows legend

23

Stiffening agents

24

Cones

25th

groove

26th

Cones

27

groove

28

Faltental

29

Wrinkle tip

30th

Flank

L.

Longitudinal axis

M.

Torque

V

Twist

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 10320501 A1 [0002]
• DE 102009003476 A1 [0006]
• DE 102004048828 A1 [0007]

Claims (12)

Air spring strut (1) for a motor vehicle, comprising an air spring (2) with an integrated shock absorber (3) for the suspension and damping of vibrations of a motor vehicle chassis, the air spring (2) comprising an air spring cover (4) and a rolling piston (5), wherein Between the air spring cover (4) and the rolling piston (5) a bellows (6) made of elastomeric material is fastened in a pressure-tight manner, whereby a volume-elastic pressure space (10) filled with compressed air is limited and the bellows (6) forms a roll fold (8) the rolling piston (5) rolls, the shock absorber (3) comprising a damper tube (12) and a piston rod (13) which can be immersed in the damper tube (12), the rolling piston (5) being non-rotatably attached to the damper tube (12) and the Piston rod (13) is connected to a damper bearing (14), the air spring cover (4) being rotatably mounted relative to the damper bearing (14) by means of a pivot bearing (20), characterized in that a means for rotating torque transmission (7) is provided, which is coupled on the one hand to the air spring cover (4) and on the other hand to the rolling piston (5) in such a way that upon rotation (V) of the shock absorber (3) about a longitudinal axis (L) of the air spring strut (1) a torque (M) emanating from the rolling piston (5) is transmitted to the air spring cover (4) via the means (7). Air suspension strut (1) Claim 1 , characterized in that the means for torque transmission is a protective bellows (7) for protecting the rolling bellows (6), a plurality of stiffening means (23) being provided in the protective bellows (7). Air suspension strut (1) Claim 2 , characterized in that the stiffening means (23) each run in the circumferential direction. Air suspension strut (1) Claim 2 or 3 , characterized in that the stiffening means (23) are each arranged in a flank region (30) between a fold valley (28) and a fold tip (29) of the protective bellows (7). Air suspension strut (1) according to one of the Claims 2 until 4th , characterized in that the stiffening means (23) are a local thickening of the protective bellows material. Air suspension strut (1) according to one of the Claims 2 until 4th , characterized in that the stiffening means (23) are embedded threads or fabrics. Air suspension strut (1) according to one of the Claims 2 until 6th , characterized in that the protective bellows (7) is fastened with a first end (21) on the air spring cover (4) and with a second end (22) on the rolling piston (5). Air suspension strut (1) Claim 7 , characterized in that the first end (21) of the protective bellows (7) is attached positively and / or non-positively to the air spring cover (4), and that the second end (22) of the protective bellows (7) positively and / or non-positively is attached to the rolling piston (5). Air suspension strut (1) Claim 8 , characterized in that the air spring cover (4) and the rolling piston (5) each have a plurality of axially extending pins (24; 26) and grooves (25; 27) for the form fit, which are arranged alternately in the circumferential direction. Air suspension strut (1) Claim 8 or 9 , characterized in that the ends (21, 22) of the protective bellows (7) are fastened for the frictional connection with a clamping device (11). Air suspension strut (1) according to one of the Claims 1 until 10 , characterized in that the rotary arm (20) is a sliding or roller bearing. Motor vehicle with an air spring strut (1) according to one of the preceding claims.

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