DE102017215348B4 - Air suspension strut with acoustic bearing - Google Patents

Abstract

Air spring strut (1) for a motor vehicle comprising an air spring (2) with a shock absorber (3) for cushioning and damping vibrations of a motor vehicle chassis, wherein the air spring (2) comprises an air spring cover (4) and a rolling piston (5), wherein a rolling bellows (6) made of elastomer material is clamped in an airtight manner between the air spring cover (4) and the rolling piston (5), wherein the rolling bellows (6) with the air spring cover (4) and the rolling piston (5) delimits a working space (9) filled with compressed air, wherein the air spring cover (4) is connected to a body section (23) of the chassis via an acoustically damping bearing element (20, 21), which comprises an elastomer element (20) and an attachment part (21), wherein the air spring cover (4) comprises a radially circumferential collar (17) on its contact surface (18) facing the body section (23), wherein the collar (17) is axially upper- and is enclosed below and radially outside by the elastomer element (20), characterized in that the attachment part (21) is made in two parts from a first half piece (26) and a second half piece (27).

Description

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

An air suspension strut, such as the one from the DE 198 34 092 A1 is arranged between the vehicle chassis or a wheel carrier and the vehicle body. The air suspension strut usually 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 vehicle body.

The air spring essentially consists of an air spring cover, a rolling piston and a rolling bellows clamped in between in an airtight manner, which defines a working space under air pressure. The rolling bellows is enclosed by a sleeve-shaped external guide and rolls on the concentric rolling piston during compression, forming a rolling fold.

The shock absorber arranged inside the air spring is connected to the wheel carrier on the one hand and is also secured with its piston rod, which can be inserted into the damper tube, via a damper bearing in the air spring cover. The air spring strut is connected to a body section via the air spring cover using appropriate fastening devices.

Stud bolts or screws are used as fastening elements. The stud bolts or screws are provided on the upper contact surface of the air spring cover. The air spring cover therefore rests with its upper contact surface on the body section, so that acoustic noise is transmitted directly into the vehicle body. To avoid this, an acoustically dampening bearing (also called an acoustic bearing) is arranged between the air spring cover and the associated body section, which ensures acoustic decoupling of the unwanted vibrations.

This is what the EN 10 2010 017 084 A1 It is known to provide acoustically dampening materials between the contact surface of the air spring cover and the body section or the strut tower. For example, alternating layers of metals and elastomers are used as additional intermediate components, with hard metal contact surfaces enclosing a body made of insulating material, with through holes being provided for the fastening elements (screws or bolts).

From the US 4 796 870 A an air spring strut is known in which a collar of the air spring cover is enclosed by an insulator axially above and below, as well as radially outside and inside, for acoustic damping. Other air spring struts with such a similar acoustic damping measure are known from JP 2008- 95 798 A and the KR 10 2017 0 006 914 A known.

Another damping measure with axially arranged elastomers is known from the EN 36 05 292 A1 known.

It is an object of the invention to provide an air spring strut in which an advantageous acoustic decoupling is achieved while at the same time sufficiently absorbing tensile and compressive forces.

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

An air spring strut for a motor vehicle is provided, comprising an air spring with a shock absorber for cushioning and damping vibrations of a motor vehicle chassis, wherein the air spring comprises an air spring cover and a rolling piston, wherein a rolling bellows made of elastomer material is clamped in an airtight manner between the air spring cover and the rolling piston, wherein the rolling bellows with the air spring cover and the rolling piston delimit a working space filled with compressed air, wherein the air spring cover is connected to a body section of the chassis via an acoustically dampening bearing element which comprises an elastomer element and an attachment part, wherein the air spring cover comprises a radially circumferential collar on its contact surface facing the body section, wherein the collar is enclosed axially above and below, as well as radially outside by the elastomer element.

The collar is designed with approximately the same diameter as the outer wall diameter of the air spring cover. The collar is thus positioned outwards as part of the body-side contact surface of the air spring cover. The air spring cover, which is in contact with the body section, is advantageously surrounded by the collar from above, below and on the sides by the elastomer or an insulating material, which achieves complete acoustic decoupling of the air spring cover. The top/bottom orientation is determined by the regular installation position of an air spring strut, in which the air spring cover is connected to the body and the shock absorber to the wheel carrier.

According to the invention, the attachment is made of two parts, consisting of a first half and a second half. This means that the attachment can be pushed onto the collar of the air spring cover from two sides, creating a solid acoustic decoupling with the body section.

According to a preferred embodiment, the elastomer element has different layer thicknesses in certain areas. The elastomer element can be designed to suit the compressive and tensile forces acting in the air spring cover, for example by specifically selecting thinner or thicker layer thicknesses. Thus, by cleverly selecting the layer thickness, the elastomer can be variably designed to suit different air spring covers.

The elastomer element preferably has a recess whose center lies outside the circle center of the elastomer element. The selected positioning and shape of the recess ensures a uniform pressure moment in the area of the contact surface, particularly in the case of non-concentric air spring covers.

According to a further preferred embodiment, the elastomer element is enclosed axially above and below, as well as radially outside by the attachment. The attachment is provided to further support the acoustic decoupling and to better attach the elastomer element to the air spring cover. This encloses the elastomer element from above, below and to the side. In addition, the enclosing of the collar by the elastomer element and attachment enables good decoupling of transverse forces.

According to a further preferred embodiment, several fastening means are provided on the attachment part for connection to the body section. Providing the fastening means on the attachment part, instead of directly on the contact surface of the air spring cover as is usual, represents an easy-to-install and cost-effective fastening of the air spring cover.

According to a further preferred embodiment, the air spring cover is made up of several parts, at least from an inner damper bearing pot and an outer cover cylinder. The collar is preferably formed by the damper bearing pot or the cover cylinder. The formation of the air spring cover from an inner and an outer cover part provides structural flexibility when designing the air spring cover depending on the available installation space.

According to a further preferred embodiment, the collar is designed as part of the body-side contact surface to transfer pressure forces to the body section. This makes it possible to advantageously direct the pressure forces between the air spring strut and the body section from the damper bearing pot into the body section. In particular, the widely spaced collar provides a large pressure-effective surface for the pressure forces to be transferred.

According to a further preferred embodiment, the collar comprises a surface facing away from the body section, which is designed to absorb tensile forces. The lower surface of the collar enables the tensile forces from the air spring strut to be advantageously directed to the body section via the damper bearing pot. The tensile forces to be transmitted are usually significantly smaller than the compressive forces to be transmitted under dynamic loads, and the smaller lower tensile surface takes this into account sufficiently.

The air spring strut is used in a chassis, preferably in an air suspension system, for a motor vehicle.

Further preferred embodiments of the invention emerge from the subclaims and the following description of embodiments with reference to the figures.

• 1 ein erstes Ausführungsbeispiel einer akustischen Entkopplung,
• 2 ein zweites Ausführungsbeispiel einer akustischen Entkopplung,
• 3 ein Elastomerelement auf einem Luftfederdeckel für ein beispielsgemäßes Luftfederbein in perspektivischer Ansicht,
• 4 das Elastomerelement der 3 auf einem Luftfederdeckel mit Anbauteilen in perspektivischer Ansicht, und
• 5 das Elastomerelement der 3 in der Draufsicht.

Show it

• 1 a first embodiment of an acoustic decoupling,
• 2 a second embodiment of acoustic decoupling,
• 3 an elastomer element on an air spring cover for an exemplary air spring strut in perspective view,
• 4 the elastomer element of the 3 on an air spring cover with attachments in perspective view, and
• 5 the elastomer element of the 3 in the top view.

The 1 shows an air spring strut 1 with the essential components, air spring 2 and shock absorber 3, whereby air spring 2 comprises an air spring cover 4, a rolling piston 5 and a rolling bellows 6 with an outer guide 7 enclosing the latter in the form of a sleeve. Shock absorber 3 is provided within air spring 2, whereby shock absorber 3 comprises a damper tube and a submersible piston rod 12.

Air spring strut 1 fulfils two functional areas, firstly air spring 2 fulfils the load-bearing force generation supply, while shock absorber 3 is responsible for the linear guide. Via several fastening means 22 on the air spring cover 4, air spring strut 1 can be fastened on the one hand to a motor vehicle body and on the other hand via a shock absorber eye (not shown) to a wheel carrier of the motor vehicle chassis, whereby the motor vehicle is sprung and damped.

Air spring 2 comprises rolling bellows 6 made of elastomer material, whereby rolling bellows 6 with air spring cover 4 and rolling piston 5 delimits an airtight and volume-elastic working space 9 that can be filled with compressed air. The tubular rolling bellows 6 is attached with its first end to the air spring cover 4 and with its second end to the rolling piston 5, for example via clamping rings 14 to the connection areas of these air spring attachments.

During relative movements along the longitudinal axis of the air spring strut 1 between the air spring cover 4 and the rolling piston 5, the rolling bellows 6 rolls on the rolling piston 5, forming a rolling fold. Furthermore, the rolling bellows 6 forms a cardanic fold 8 on the air spring cover 4, which acts as a cardanic bearing. At the same time, the rolling bellows 6 is provided with embedded strength members.

In particular, with the comfortable axial bellows, i.e. with reinforcements aligned in the axial direction, external guides 7 are used to limit the lateral expansion of the rolling bellows 6. The external guide 7 can be clamped to the rolling bellows 6 by an internal clamping ring 12 provided in the working space 9.

An additional spring 13 is arranged on the underside of the air spring cover 4 facing the shock absorber 3. The additional spring 13 has a through hole for the piston rod 12 and therefore encloses it. When the spring is compressed, the front side of the damper tube moves towards the air spring cover 4, which is why the additional spring 13 serves as a travel limiter and dampens any forces acting on the air spring cover 4.

Air spring cover 4 comprises a cover chamber 10, which is operatively connected to the working chamber 9 of the air spring 2 and thus supports the effective spring effect. Air spring cover 4 is designed in several parts from an inner damper bearing pot 15 and an outer cover cylinder 16, with damper bearing pot 15 and cover cylinder 16 being connected to one another at a contact surface 18 of the air spring cover 4. Damper bearing pot 15 serves to accommodate the shock absorber bearing and cover cylinder 16 forms the cover chamber 10 with its shape and rolling bellows 6 is connected to cover cylinder 16.

Contact surface 18 of the air spring cover 4 faces a body section. Pressure forces emanating from the air spring strut 1 are transferred to the vehicle body via contact surface 18. Contact surface 18 can therefore also be referred to as a pressure-effective surface.

In this embodiment, the damper bearing pot 15 comprises a collar 17, which is formed on the body side so as to extend radially around the outer diameter of the air spring cover 4. As a component of the contact surface 18 of the air spring cover 4, the collar 17 also functions as a pressure-effective surface. Furthermore, the collar 17 comprises a lower surface 19 facing away from the body section.

Collar 17 can, for example, be made from a thick sheet metal. This enables the cost-effective design of the highly stressed, over-encompassing cover collar from the material that already has to be made from thick or reinforced material to support the damper bearing.

For example, collar 17 is enclosed by an insulating material or an elastomer element 20. Elastomer element 20 therefore encompasses collar 17 in the axial direction on the one hand on its lower surface 19 and on the other hand on its upper contact surface 18. Furthermore, collar 17 is also enclosed externally in the circumferential direction by elastomer element 20.

According to the example, elastomer element 20 is additionally enclosed by an attachment part 21. Attachment part 21 comprises elastomer element 20 axially on the one hand directly between the body section and the elastomer side, which is provided on the contact surface 18, and on the other hand, attachment part 21 comprises the elastomer side, which is provided on the lower surface 19 of the collar 17. Furthermore, elastomer element 20 is also enclosed externally in the circumferential direction by attachment part 21.

Due to the fact that the lower surface 19 of the collar 17 is enclosed by the elastomer element 20 and the attachment part 21, wherein the attachment part 21 is connected to the body section by means of fastening means 22, the surface 19 is particularly advantageously provided for the tensile forces of the air spring strut and can therefore also be referred to as a tensile-effective surface.

The advantage of this example and the special positioning of the contact surfaces to the insulation material is that the contact surfaces for decoupling can be designed to be large in size, making optimal use of the usual installation space. In contrast, the design of contact surfaces around a bolt, for example, is very small due to their structure. Small contact surfaces require a harder insulation material and therefore provide a poorer insulation effect.

In the 2 An alternative design of the collar 17 is shown in the cutout of the air spring strut. Depending on the requirements of the air spring cover 4, the collar 17 can also be made of the material of the cover cylinder 16.

In the 3 a special form of the elastomer element 20 is shown with a non-concentric air spring cover 4. The design of the insulation material or elastomer element 20 is provided in such a way that no uneven pressure moment arises in the event of axial deformation. This is achieved by providing the elastomer element 20 with a smaller contact surface or with a smaller layer thickness of the undeformed insulation material in the radially outwardly displaced contact surface between the body section and the air spring cover 4.

4 shows the example of the encompassing attachment part 21, which is made up of two parts, a first half-piece 26 and a second half-piece 27. Attachment part 21 can therefore be opened, since an axial division is provided. This simplifies the assembly of the acoustic bearing, as the encompassing attachment part 21 is not deformed during assembly. Half-pieces 26, 27 are pushed together from the side and it is advantageously used that they are held in position during installation with the body section by fastening means 22, comprising elastomer 20.

5 shows elastomer element 20 in plan view, wherein elastomer element 20 has a larger inner non-concentric recess 25 and a smaller hole 24 in an edge region. Hole 24 and two semicircular edge regions of recess 25 are provided for the fastening means.

List of reference symbols

1

Air suspension strut

2

Air spring

3

Shock absorbers

4

Air spring cover

5

Rolling piston

6

Roll bellows

7

Outdoor tour

8th

Cardanic fold

9

working space

10

Lid space

11

Inner clamping ring

12

Damper rod

13

Additional spring

14

Clamp ring

15

Damper bearing pot

16

Cover cylinder

17

collar

18

Contact surface

19

lower surface

20

Elastomer element

21

Attachment

22

Fastener

23

Body section

24

Hole

25

Recess

26

first half

27

second half

Claims (10)

Air spring strut (1) for a motor vehicle, comprising an air spring (2) with a shock absorber (3) for cushioning and damping vibrations of a motor vehicle chassis, wherein the air spring (2) comprises an air spring cover (4) and a rolling piston (5), wherein a rolling bellows (6) made of elastomer material is clamped in an airtight manner between the air spring cover (4) and the rolling piston (5), wherein the rolling bellows (6) with the air spring cover (4) and the rolling piston (5) delimits a working space (9) filled with compressed air, wherein the air spring cover (4) is connected to a body section (23) of the chassis via an acoustically damping bearing element (20, 21), which comprises an elastomer element (20) and an attachment part (21), wherein the air spring cover (4) comprises a radially circumferential collar (17) on its contact surface (18) facing the body section (23), wherein the collar (17) is axially upper- and is enclosed below and radially outside by the elastomer element (20), characterized in that the attachment part (21) is made in two parts from a first half piece (26) and a second half piece (27). Air suspension strut after Claim 1 , characterized in that the elastomer element (20) has different layer thicknesses in some regions. Air suspension strut after Claim 1 or 2 , characterized in that the elastomer element (20) has a recess (25) whose center lies outside the circle center of the elastomer element (20). Air suspension strut according to one of the Claims 1 until 3 , characterized in that the elastomer element (20) is partially enclosed above and below, as well as radially outside by the attachment part (21). Air suspension strut according to one of the Claims 1 until 4 , characterized in that fastening means (22) for connection to the body section (23) are provided on the attachment part (21). Air suspension strut according to one of the Claims 1 until 5 , characterized in that the air spring cover (4) is formed in several parts at least from an inner damper bearing pot (15) and an outer cover cylinder (16). Air suspension strut after Claim 6 , characterized in that the collar (17) is formed by the damper bearing pot (15) or the cover cylinder (16). Air suspension strut according to one of the Claims 1 until 7 , characterized in that the collar (17) is designed as a part of the body-side contact surface (18) to transmit compressive forces to the body section (23). Air suspension strut according to one of the Claims 1 until 8th , characterized in that the collar (17) comprises a surface (19) facing away from the body section (23) which is designed to absorb tensile forces. Chassis for a motor vehicle, in particular an air suspension system, with an air suspension strut (1) according to one of the Claims 1 until 9 .

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