Air spring with pressure-controlled bellows ventilation

Abstract

Air spring (1) for a motor vehicle, comprising an elastomeric rolling diaphragm (4) which is pressure-tightly attached between two connection parts (2; 3) of the air spring (1), thereby defining a volume-elastic pressure chamber (5) filled with compressed air and the rolling diaphragm (4) rolling down one of the connection parts (2) in the form of a rolling fold (6), wherein a bellows (10) is connected to the two connection parts (2; 3), whereby the rolling diaphragm (4) is protected from contamination by the bellows (10), wherein the bellows (10) defines a volume-variable space (15) which surrounds the rolling diaphragm (4), wherein a first vent opening (11) into the space (15) can be closed by a first check valve (13), and a second vent opening (12) into the space (15) can be closed by a second check valve (14).

Description

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

[0002] Air springs or air struts, which are clamped between the chassis and the body of a motor vehicle and feature a rolling bellows, which in turn is secured between a cover and a rolling piston, are known in a wide variety of designs. 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 concentric rolling piston. To limit expansion, the rolling bellows is enclosed by a sleeve-shaped outer guide.

[0003] DE 10 2013 211 644 A1 discloses an air spring strut for a motor vehicle in which the rolling bellows, in particular its rolling fold, is protected from contamination by a bellows, wherein the bellows is attached on the one hand to a lower end of the outer guide and on the other hand to a lower end of the rolling piston. Due to the spring movement of the air spring, the volume of the space enclosed by the bellows changes, so that a negative pressure can develop in this space, which could cause the bellows to implode or be damaged. Therefore, the air enclosed by the bellows must be exchanged with the ambient air, which, however, contains dirt particles. As a result of this exchange, these dirt particles can enter the interior of the bellows space and damage the rolling fold.For this reason, ventilation openings are used, which are incorporated into the bellows at the top and bottom ends. At the same time, means are used to control the air flow into the bellows, which are intended to direct the sucked-in dirt particles away from the rolled pleat. Furthermore, check valves are used, which are designed, for example, as simple ring-shaped rubber elements and cover the ventilation opening on the inside of the bellows. Furthermore, the use of check valves is suggested, although these are not described in detail.

[0004] It is the object of the invention to provide an air spring for a motor vehicle in which the ventilation of the space surrounding the rolling bellows and delimited by the bellows is improved and the rolling bellows is simultaneously better protected against contamination.

[0005] The object underlying the invention is achieved with an air spring for a motor vehicle according to the features of patent claim 1.

[0006] The air spring is used in the air suspension system of a motor vehicle. When the air spring according to the invention is combined with an integrated shock absorber, it is an air spring strut.

[0007] Preferred embodiments of the invention emerge from the subclaims and from the following description of an embodiment with reference to the figures.

[0008] They show: Fig. 1 an exemplary air spring, Fig. 2 in the cutout a first check valve, and Fig. 3 in the cutout a second check valve.

[0009] The Fig. Figure 1 shows an example air spring 1 with its essential components. The first connecting part for connection to the vehicle body is a rolling piston 2. The second connecting part for connection to a wheel carrier is a cover 3. The air spring 1 shown here is in the so-called "upside-down position." The longitudinal axis of air spring 1 is marked L.

[0010] A rolling bellows 4, clamped pressure-tight between rolling piston 2 and cover 3, defines, with these connecting parts, a volume-elastic pressure chamber 5 filled with compressed air. The tubular rolling bellows 4 is attached at a first end to the rolling piston 2 and at a second end to the cover 3. The rolling bellows ends can be attached either by vulcanization to the connecting parts 2, 3 or the rolling bellows ends can be pressed into the corresponding clamping bases of the connecting parts 2, 3 using clamping rings. In addition, rolling bellows 4 rolls on rolling piston 2, forming an invisible rolling fold. A further fold is formed on the cover 3. Rolling bellows 4 is provided with strength members which run in a cross and / or axial direction.

[0011] The Fig. The air spring 1 shown in Figure 1 is in a pressurized and operational state. Thus, the rolling bellows 4 is at least partially enclosed by a sleeve-shaped outer guide 8. The outer guide 8 is attached to the rolling bellows 4 by means of a clamping ring 9 located in the pressure chamber 5. The outer guide 8 serves as a support corset and limits the lateral expansion of the rolling bellows 4. The outer side of the rolling bellows 4 essentially rests against the inner side of the outer guide 8, with the rolling fold and fold being exposed in the normal position.

[0012] A bellows 10 is provided to protect the rolling fold 6 and fold 7 from dirt and damage. Bellows 10 is attached to the rolling piston 2 on one side and to the cover 3 on the other. The respective bellows ends are secured via a positive connection with an outward-facing collar of the respective connecting part. Thus, bellows 10 defines a space 15 between the rolling bellows 4, the rolling piston 2, and the cover 3. This space 15 changes in volume during the compression and extension of air spring 1, which is why it must be ventilated.

[0013] To ventilate the space 15 defined by the bellows 10, a first ventilation opening 11 is provided in an upper region of the air spring 1. The first ventilation opening 11 is preferably located in the bellows 10 in a region close to the connection between the bellows 10 and the rolling piston 2. However, the first ventilation opening 11 can also be located in a fastening collar of the rolling piston 2, which leads to the space 15. The first ventilation opening 11 can also be located at a completely different location on the rolling piston 2, as long as a connection to the space 15 exists.

[0014] Furthermore, a second ventilation opening 12 is provided in a lower area of ​​air spring 1. The second ventilation opening 12 is preferably located in the bellows 10 in an area near the connection of the bellows 10 to the cover 3. However, the second ventilation opening 12 can also be located in a fastening collar of the cover 3, which leads to the chamber 15. The second ventilation opening 12 can also be located at a completely different location on the cover 3, as long as a connection to the chamber 15 exists.

[0015] For example, the first ventilation opening 11 is closed by a first check valve 13 and the second ventilation opening 12 is closed by a second check valve 14. The details and functioning of the two check valves 13 and 14 are explained in the following descriptions of the Fig. 2 and Fig. 3 in more detail.

[0016] The first check valve 13 is located essentially outside the bellows 10 or chamber 15. The first check valve 13 is configured such that it opens toward chamber 15 when pressurized. This means that when a negative pressure is present in chamber 15, the first check valve 13 opens, so that ambient air is drawn into chamber 15.

[0017] As the Fig. 2 shows, the first check valve 13 comprises a cylindrical or sleeve-shaped valve housing 16. A pin-shaped or mushroom-shaped closing body 17 is inserted into the valve housing 16 and is acted upon by a closing spring 18. The valve housing 16 comprises a conical valve seat 19 against which the correspondingly conically shaped head of the closing body 17 bears sealingly. Opposite the valve seat 19, the valve housing 16 forms an annular stop against which the closing spring 18 is supported with a first end turn. On the other side, the closing spring 18 comprises a second end turn which is firmly connected to the shaft end of the closing body 17. In this way, the closing body 17 is spring-loaded within the valve housing 16. When a pressure exceeding the spring force of the closing spring 18 is applied, the closing body 17 is lifted from the valve seat 19 so that air can flow into the chamber 15.In addition, the first check valve 13 comprises a pot-shaped valve cover 20, which is pushed over the valve housing 16. The valve cover 20 comprises a number of openings that allow gas to enter and repel dirt particles. The valve cover 20 is connected to the valve housing 16 via two expansion pins. For this purpose, the valve housing 16 rests with a flange on the bellows 10, and in a corresponding manner, the valve cover 20 also comprises a flange opposite the bellows 10. The expansion pins are attached to the flange of the valve housing 16 and are pushed through openings in the flange of the valve cover 20, thereby creating a positive and detachable connection between the valve housing 16 and the valve cover 20.

[0018] Consequently, the first check valve 13 opens when the air spring rebounds and chamber 15 expands. The resulting negative pressure counteracts the spring force of the closing spring 18, so that the closing body 17 is lifted from the valve seat 19, opening the first check valve 13 or the first vent opening 11, and allowing ambient air to flow into chamber 15.

[0019] The same applies to the second check valve 14, which is based on the Fig. 3. The second check valve 14 is located essentially within the bellows 10 or chamber 15. The second check valve 14 is configured such that it opens when pressurized toward the surroundings of the air spring, i.e., out of chamber 15. This means that when excess pressure is present in chamber 15, the second check valve 14 opens, allowing air to escape from chamber 15 into the surroundings.

[0020] The second check valve 14 also comprises a cylindrical or sleeve-shaped valve housing 16'. A pin- or mushroom-shaped closing body 17' is inserted into the valve housing 16', which is acted upon by a closing spring 18'. The valve housing 16' comprises a conical valve seat 19' against which the correspondingly conically shaped head of the closing body 17' rests in a sealing manner. Opposite the valve seat 19', the valve housing 16' forms an annular stop against which the closing spring 18' is supported with a first end turn. On the other side, the closing spring 18' comprises a second end turn, which is firmly connected to the shaft end of the closing body 17'. In this way, the closing body 17' is spring-loaded within the valve housing 16'. When a pressure exceeding the spring force of the closing spring 18 is applied, the closing body 17' is lifted from the valve seat 19' so that air can flow out of the chamber 15.

[0021] Consequently, the second check valve 14 opens when the air spring compresses and chamber 15 expands. The resulting overpressure counteracts the spring force of the closing spring 18', so that the closing body 17' is lifted from the valve seat 19', opening the second check valve 14 or the second vent opening, and allowing air to flow from chamber 15 into the environment. List of reference symbols 1 air spring 2 first connecting part / rolling piston 3 second connection part / cover 4 rolling bellows 5 Printing room 8 External guide 10 bellows 11 first ventilation opening 12 second ventilation opening 13 first check valve 14 second check valve 15 rooms 16 valve housings 16' valve body 17 locking bodies 17' closing body 18 closing spring 18 closing spring 19 Valve seat 19 Valve seat 20 valve cover L Longitudinal axis QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] DE 10 2013 211 644 A1

[0003]

Claims

[1] Air spring (1) for a motor vehicle, comprising an elastomeric rolling bellows (4) which is fastened in a pressure-tight manner between two connecting parts (2; 3) of the air spring (1), whereby a volume-elastic pressure chamber (5) filled with compressed air is delimited and the rolling bellows (4) rolls on one of the connecting parts (2) to form a rolling fold (6), wherein a bellows (10) is connected to the two connecting parts (2; 3), whereby the rolling bellows (4) is protected from contamination by the bellows (10), wherein the bellows (10) delimits a volume-variable chamber (15) which surrounds the rolling bellows (4), characterized by that a first ventilation opening (11) into the space (15) can be closed by a first check valve (13), and a second ventilation opening (12) into the space (15) can be closed by a second check valve (14). [2] Air spring (1) according to claim 1, characterized bythat the first check valve (13) is designed to open towards the space (15). [3] Air spring (1) according to claim 1 or 2, characterized by that the second check valve (14) is designed to close in the direction of the space (16). [4] Air spring (1) according to claim 2 and 3, characterized by that, with respect to an installation position of the air spring (1) in the motor vehicle, the first check valve (13) is located in an upper region and the second check valve (14) is located in a lower region. [5] Air spring (1) according to one of claims 1 to 4, characterized by that the first ventilation opening (11) with the first check valve (13) is arranged on the bellows (10). [6] Air spring (1) according to one of claims 1 to 5, characterized by that the second ventilation opening (12) with the second check valve (14) is arranged on one of the connecting parts (2; 3). [7] Air spring (1) according to one of claims 1 to 6, characterized by that the first check valve (13) comprises a valve housing (16) which forms a valve seat (19) against which a closing body (19) loaded by means of a closing spring (18) rests in a sealing manner. [8] Air spring (1) according to one of claims 1 to 7, characterized by that the first check valve (13) is arranged substantially outside the space (15). [9] Air spring (1) according to one of claims 1 to 8, characterized by that the second check valve (14) comprises a valve housing (16') which forms a valve seat (19') against which a closing body (19') loaded by means of a closing spring (18') rests in a sealing manner. [10] Air spring (1) according to one of claims 1 to 9, characterized by that the second check valve (14) is arranged substantially within the space (15).

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