Air suspension system with a rolling piston and an interchangeable shell

Abstract

Air spring device (1) for a motor vehicle, comprising an elastomeric rolling diaphragm (6) which is pressure-tightly attached between an air spring cover (4) and a rolling piston (5), thereby defining a volume-variable pressure chamber (7) filled with compressed air, wherein the rolling piston (5) comprises a replaceable shell (20) on which the rolling diaphragm (6) rolls, forming a rolling fold (8), wherein the replaceable shell (20) comprises a first and second shell section (21; 22) which are connected to each other by means of a first and a second snap connection (25; 26), characterized in that a first groove (23) for the first snap connection (25) and a second groove (24) for the second snap connection (26) are provided on the rolling piston (5), wherein the first snap connection (25) engages positively in the first groove (23) and the second snap connection (26) engages positively in the second groove (24).

Description

[0001] The invention relates to an air spring device for a motor vehicle according to the preamble of claim 1.

[0002] Air spring systems, which are used as air springs or air struts, are clamped between a chassis component and a body section of a motor vehicle. They feature a rolling bellows mounted between a cover and a rolling piston. During operation, the air spring is subjected to internal overpressure, and the rolling bellows rolls during spring movements, forming a rolling fold on the outer surface of the rolling piston. To limit expansion, the rolling bellows is enclosed by a sleeve-shaped outer guide.

[0003] The spring behavior of the air spring can be determined by the surface area of ​​the rolling piston. The spring stiffness is influenced by its shape, or the surface on which the rolling bellows rolls. To avoid having to design and shape each rolling piston for a specific application, a modular design principle has been established. A rolling piston is provided, onto which an interchangeable shell is inserted. The interchangeable shell is detachable and can be provided in a variety of shapes. This allows the desired spring stiffness to be adjusted using a single rolling piston and a variety of interchangeable shells.

[0004] This procedure is known, for example, from document DE 10 2011 085 323 A1. In it, a replacement shell is pushed onto the base body, defining the outer contour of the piston skirt. However, the axial sliding of the replacement shell has proven to be disadvantageous during the assembly process.

[0005] For example, it is more advantageous to mount the interchangeable shell onto the base body from the outside radially. For this purpose, it is known from document JP 2018-100707 A that the interchangeable shell is manufactured from two separate shell parts and then inserted into one another laterally on the base body.

[0006] Therefore, it is an object of the invention to provide an air spring device with a rolling piston and a removable shell, wherein the fastening of the removable shell to the rolling piston is improved.

[0007] The problem underlying the invention is solved by the features of the independent patent claim. Preferred embodiments are set out in the subclaims.

[0008] According to the invention, an air spring device for a motor vehicle is provided, comprising an elastomeric rolling bellows which is fastened in a pressure-tight manner between an air spring cover and a rolling piston, whereby a pressure chamber of variable volume filled with compressed air is delimited, wherein the rolling piston comprises an interchangeable shell on which the rolling bellows rolls to form a rolling fold, wherein the interchangeable shell comprises a first and a second shell piece which are connected to one another by means of a first and a second snap connection, wherein a first groove for the first snap connection and a second groove for the second snap connection are provided on the rolling piston, wherein the first snap connection engages positively in the first groove and the second snap connection engages positively in the second groove.

[0009] Advantageously, the two shell sections of the interchangeable shell are connected by two snap connections and engage positively into specially provided grooves in the rolling piston. This ensures that the interchangeable shell is securely held on the rolling piston. The interchangeable shell can no longer twist on the rolling piston.

[0010] A preferred embodiment provides that the first shell piece has a plurality of engagement wings which are designed to engage in a form-fitting manner in an undercut of the second shell piece. The engagement wings of one shell piece are operatively connected to the undercut of the other shell piece and ensure that the two shell pieces cannot be easily detached. Because the snap connections engage in the grooves, the shell pieces expand radially outwards when pulled off. As a result, the engagement wings of one shell piece engage even more tightly in the undercut of the other shell piece, resulting in an extremely secure form-fitting connection. Since several engagement wings are provided on each joining edge of the shell pieces and each joining edge also has an undercut, the design ensures that the two shell pieces hold each other firmly.

[0011] According to a further preferred embodiment, the snap connections span a respective engagement angle that is greater than the engagement angle of the respective groove. Providing the snap connections with a slightly larger engagement angle than the engagement angle of the grooves also ensures a better hold of the interchangeable shell on the rolling piston.

[0012] The snap connections are preferably axially aligned. This allows the interchangeable shell to be mounted and assembled on the rolling piston from the outside.

[0013] In a further preferred embodiment, a flange is provided on the rolling piston in the circumferential direction for axially supporting the two shell pieces. The flange ensures that the shell pieces do not fall off and are held axially in position.

[0014] Preferably, the rolling piston has a clamping shaft for securing one end of the rolling bellows, with the first and / or second groove extending substantially from the clamping shaft to the flange. An elongated groove enlarges the engagement surface for the snap connection, thus ensuring a better hold of the shell pieces in the groove.

[0015] The rolling piston is preferably made of metal or plastic. The interchangeable shell is preferably made of plastic. A plastic interchangeable shell allows for easy shaping of the rolling surface for the rolling fold and is also elastically deformable so that its shell pieces can be inserted onto the rolling piston or into the grooves.

[0016] If the air spring device according to the invention is combined with an integrated shock absorber, it is an air spring strut in which the interchangeable shell is also used.

[0017] The air spring device is used in an air spring system of a motor vehicle.

[0018] Further preferred embodiments of the invention will become apparent from the following description of an embodiment with reference to the figures.

[0019] They show: Fig. 1 an exemplary air spring device with a rolling piston and a removable shell, Fig. 2 the rolling piston with shell pieces of the interchangeable shell in exploded view, Fig. 3a to d a piece of a shell in various views, and Fig. 4a and b the rolling piston with shell pieces in engagement.

[0020] The Fig. 1 shows an exemplary air spring device 1 comprising an air spring 2 and an integrated shock absorber 3, wherein the air spring 2 comprises an air spring cover 4, a rolling piston 5, and a rolling bellows 6. A shock absorber 3 is provided within the air spring 2, wherein the shock absorber 3 comprises a damper tube 17 and a piston rod 18 that can be inserted into the damper tube.

[0021] Rolling bellows 6 is made of elastomeric material and, together with air spring cover 4 and rolling piston 5, defines a pressure-tight, variable-volume pressure chamber 7 filled with compressed air. For this purpose, the tubular rolling bellows 6 is attached with its upper end to the air spring cover 4 and with its lower end to the rolling piston 5, for example via clamping rings 12 to the connection areas of these air spring connection parts. During relative movements along a longitudinal axis L of the air spring device 1 between the air spring cover 4 and rolling piston 5, the rolling bellows 6 rolls on an interchangeable shell 20, forming a rolling fold 8, which serves as a rolling surface. The interchangeable shell 20 is detachably attached to the rolling piston 5. The shape of the interchangeable shell 20 influences the spring behavior of the air spring 2. In addition, the rolling bellows 6 forms a further fold 9 on the air spring cover 4. Fold 9 acts as a gimbal bearing. Bellows 6 is also provided with embedded reinforcements.Its strength members are arranged in axial and / or cross positions.

[0022] Furthermore, an outer guide 10 is provided that at least partially surrounds the rolling bellows 6. This guide is held in place by a clamping ring 13 attached to the inside of the rolling bellows 6. The outer guide 10 limits the lateral expansion of the rolling bellows 6, especially if it has thin walls.

[0023] The pressure chamber 7 is filled via an air connection on the air spring cover 4. A channel is inserted or drilled into the air spring cover 4, which leads from the air connection into the interior of the air spring 2. Through the air connection, the air spring 2 can be filled with a specific amount of compressed air, which also adjusts its spring force.

[0024] To protect the rolling bellows 6 and, in particular, its rolling fold 8 from contamination, a protective bellows 11 is provided. Its upper end is attached to the lower end of the outer guide 10 and its lower end to the lower end of the rolling piston 5. The protective bellows 11 can be attached by a positive or non-positive fit.

[0025] Air suspension system 1 performs two functions. Air spring 2 generates the load-bearing force, while shock absorber 3 is responsible for linear guidance. This provides suspension and damping for the vehicle. On the one hand, air suspension system 1 is connected to a body section of a vehicle via air spring cover 4, and on the other hand, it can be connected to a wheel carrier of the vehicle via a damper eyelet (not shown) of shock absorber 3. This standard installation position of air suspension system 1 determines the "top / bottom" orientation.

[0026] Rolling piston 5, which is made of metal or plastic, is hollow-cylindrical in shape and is sealingly arranged on a support ring 14 of the damper tube 17. A damper bearing 15 is attached to the upper free end of piston rod 18. Damper bearing 15 comprises an elastomer body into which a support piece is at least partially embedded. The support piece is fixed to the upper end of piston rod 18. Damper bearing 15 is arranged in a bearing recess 16 of the air spring cover 4. Bearing recess 16 of the air spring cover 4 is pot-shaped and provided in a core region of the air spring cover 4. It comprises a side wall and a base. A through-bore for piston rod 18 is provided in the base of bearing recess 16 or of the air spring cover 4.A stop buffer 19 is also arranged beneath the floor to limit the compression travel of the damper tube 17 and reduce the forces introduced into the air spring cover 4 upon impact. The air spring cover 4 is made of a plastic material, e.g., a thermoplastic or a thermoset. A metal version of the air spring cover 4, e.g., aluminum or steel, is also possible.

[0027] In the Fig. 2, rolling piston 5 is provided with an exemplary interchangeable shell 20. Interchangeable shell 20 is a sleeve-shaped part composed of two shell pieces 21 and 22. Interchangeable shell 20 can also be composed of several shell pieces. The inner wall of interchangeable shell 20 rests against rolling piston 5. The outer wall of interchangeable shell 20 represents the rolling surface for the rolling fold of the rolling bellows. Its external shape or design influences the spring behavior of the air spring device.

[0028] The interchangeable shell 20 is divided into the two shell pieces 21 and 22 by a central and axially running cut. This allows the interchangeable shell 20 to be pushed onto the rolling piston 5 from the radial outside. This is easier to assemble than pushing a one-piece interchangeable shell onto the rolling piston 5 from above. However, it is then necessary to firmly connect the two shell pieces 21 and 22 to the rolling piston 5. Snap connections 25 and 26 are provided for this purpose, by means of which the two shell pieces 21 and 22 are pushed together at their axial joining edges 32. Each shell piece 21 and 22 has two joining edges 32 whose shape is complementary to the corresponding joining edge 32 of the other shell piece.

[0029] To ensure better hold of the interchangeable shell 20 or the shell pieces 21 and 22, a first groove 23 and a second groove 24 are provided on the rolling piston 5. Grooves 23 and 24 are axially extending in the rolling piston 5. Grooves 23 and 24 are intended to accommodate the respective snap connection 25 or 26. The first snap connection 25 engages positively in the groove 23. The second snap connection 26 engages positively in the groove 24. In addition, the rolling piston 5 has a flange 27 running in the circumferential direction. Flange 27 is intended to axially support the two shell pieces 21 and 22. The rolling piston 5 also comprises a clamping shaft 28 for fastening one end of the rolling bellows. Preferably, grooves 23 and 24 extend from the clamping shaft 28 to the flange 27. This creates a longitudinal form fit between the groove and the snap connection, which ensures proper anti-twist protection of the interchangeable shell 20 on the rolling piston 5.

[0030] In the Fig. 3a to c, shell piece 21 is shown in various representations. The snap connections are made by an undercut 30 into which engagement wing 29 engages. This is the Fig. 3a at one of the joining edges 32, which show shell piece 21 from above. An engagement wing 29 is provided on the joining edge 32 of shell piece 21. This protrudes radially from the inside to the outside and protrudes slightly. The engagement arm 29 protrudes from a shaped surface 31 of the shell piece 21. This shaped surface 31 has a smaller radius at an imaginary center of the shell piece 21 than the inner wall of the shell piece 21. The shaped surface 31 thus protrudes inward. Furthermore, the undercut 30 is provided on the outer area of ​​the joining edge 32.

[0031] In the Fig. 3b, which shows shell piece 21 in side view, the engagement wing 29, undercut 30 and joining surface 31 are shown again. Only one joining edge 32 has been provided with the corresponding reference numerals for the sake of simplicity. Fig. 3b shows that a plurality of engagement wings 29 are provided on the joining edge 32. These are arranged at certain distances from one another on the joining edge 32. The undercut 30 and the joining surface 31, however, extend over the entire length of the joining edge 32. The undercut 30 is located in the outer region of the joining edge 32, so that the outwardly projecting engagement wings 29 can engage the undercut of the opposite joining edge. On both joining edges 32 of shell piece 21, there is an engagement wing 29 and an undercut 30 each. The same applies to the other shell piece.

[0032] Fig. Figure 3c shows a perspective view of shell piece 21. The shaped surface 31, which is smaller in radius and diameter, is clearly visible at the joining edge 32. The engagement wings 29 protrude from this surface and are designed to engage the undercut of the other shell piece.

[0033] The Fig. Figure 3d shows an alternative engagement wing 29 of the first shell piece 21. Instead of a flat wing, two individual arms are used.

[0034] With the Fig. 4a and b show the operating state when the two shell pieces 21 and 22 are engaged on the rolling piston 5. From above, it can be seen how the first shell piece 21 and the second shell piece 22 are plugged together. On the right side of the Fig. 4a shows the first snap connection 25 and on the left side the second snap connection 26.

[0035] The detail C is shown in the Fig. 4b. On the rolling piston 5, the first shell piece 21 and the second shell piece 22 are connected by means of a first snap connection 25. The first snap connection 25 is positively received in the first groove 23. The positive connection is created by the respective shaped surfaces of the joining edges (both without reference symbols), which are in the Fig. 3a to c. The joining edges and shaped surfaces of the respective shell pieces 21 and 22 abut one another to form the first snap connection 25. Because the joining surfaces have a smaller diameter than the inner wall of the shell pieces 21 and 22 or the interchangeable shell, they protrude into the first groove 23. This creates the positive connection between the first snap connection 25 and the first groove 23.

[0036] Preferably, the two mold surfaces together span a mold engagement angle b that is greater than a mold receiving angle a created by the first groove 23. This ensures a secure hold of the first snap connection 25 in the first groove 23. Preferably, the mold engagement angle b is 90°. Preferably, the mold receiving angle a is 70°.

[0037] The first snap connection 25 is created by the respective engagement arms of the two shell pieces 21 and 22 engaging in the mutual undercut of the two shell pieces 21 and 22. The secure fixation of the interchangeable shell on the rolling piston 5 is achieved by the joining surfaces of the two snap connections. Should one or both shell pieces 21 and 22 move radially outwards due to an external influence, the joining surface located in the groove represents resistance. If, for example, the second shell piece 22 comes loose, the joining surface slides along the inclined surface of the groove and thereby expands the diameter of the second shell piece 22. Due to this diameter expansion, the engagement wings of shell piece 22 engage even more firmly in the undercut of the first shell piece 21, thus preventing the second shell piece 22 from coming loose.This positive locking mechanism holds the two shell pieces 21 and 22 firmly together during operation and simultaneously in position. Vibrations and movements of the air spring during operation are considered external influences. Critical for securing the interchangeable shell to the rolling piston 5 is the fully extended state of the air spring, when the roll fold of the rolling bellows barely covers the interchangeable shell. In this case, the compressive forces of the roll fold only act on the interchangeable shell to a limited extent. Therefore, if the interchangeable shell is free-standing, secure fixation must be ensured. This is achieved by the snap connections in grooves of the rolling piston, as shown in the example.

[0038] The constructive representation of the first snap connection 25 in the first groove 23, which is in the Fig. 4b also applies to the second snap connection 26 in the second groove 24. List of reference symbols 1 air suspension device 2 air springs 3 shock absorbers 4 air spring covers 5 rolling pistons 6 rolling bellows 7 Printing room 8 roll fold 9 folds 10 External tour 11 Protective bellows 12 clamping ring 13 clamping ring 14 Support ring 15 damper bearings 16 Bearing recording 17 Damper tube 18 Piston rod 19 stop buffers 20 interchangeable trays 21 first shell piece 22 second shell piece 23 first groove 24 second groove 25 first snap connection 26 second snap connection 27 Flange 28 clamping shaft 29 intervention wings 30 undercut 31 Form surface 32 joining edge a mold pressure angle b Form mounting angle L Longitudinal axis

Claims

[1] Air spring device (1) for a motor vehicle, comprising an elastomeric rolling bellows (6) which is fastened in a pressure-tight manner between an air spring cover (4) and a rolling piston (5), whereby a volume-variable pressure chamber (7) filled with compressed air is delimited, wherein the rolling piston (5) comprises an interchangeable shell (20) on which the rolling bellows (6) rolls to form a rolling fold (8), wherein the interchangeable shell (20) comprises a first and a second shell piece (21; 22) which are connected to one another by means of a first and a second snap connection (25; 26), characterized by that a first groove (23) for the first snap connection (25) and a second groove (24) for the second snap connection (26) are provided on the rolling piston (5), wherein the first snap connection (25) engages positively in the first groove (23) and the second snap connection (26) engages positively in the second groove (24). [2] Air spring device (1) according to claim 1, characterized by that the first shell piece (21) has a plurality of engagement wings (29) which are designed to engage positively in an undercut (30) of the second shell piece (22). [3] Air spring device (1) according to claim 1 or 2, characterized by that the snap connections (25; 26) span a respective mold engagement angle (b) which is greater than a mold receiving angle (a) of the respective groove (23; 24). [4] Air spring device (1) according to one of claims 1 to 3, characterized by that the snap connections (25; 26) are provided axially aligned. [5] Air spring device (1) according to one of claims 1 to 4, characterized by that a flange (27) is provided on the rolling piston (5) in the circumferential direction for axially supporting the two shell pieces (21; 22). [6] Air spring device (1) according to claim 5, characterized byin that the rolling piston (5) has a clamping shaft (28) for fastening one end of the rolling bellows (6), wherein the first and / or the second (23; 24) groove extend substantially from the clamping shaft (28) to the flange (27). [7] Air spring device (1) according to one of claims 1 to 6, characterized by that the rolling piston (5) is made of a metal or a plastic. [8] Air spring device (1) according to one of claims 1 to 7, characterized by that the interchangeable tray (20) is made of a plastic. [9] Air spring device (1) according to one of claims 1 to 8, characterized by that it comprises an air spring (2) with an integrated shock absorber (3). [10] Motor vehicle comprising an air spring device (1) according to one of the preceding claims.

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