AIR SPRING

Description

[0001] The invention relates to an air spring according to the preamble of claim 1. Furthermore, the invention relates to a seat suspension of a motor vehicle according to claim 10, a cabin mounting of a motor vehicle according to claim 11 and a machine mounting according to claim 12. State of the art

[0002] Air springs are used in a variety of applications. For example, air springs in road or rail vehicles can be installed between the axle and the vehicle chassis, or between the vehicle chassis and the driver's cab, to isolate shocks and vibrations caused by uneven road surfaces. Another application is the vibration-isolated mounting of machinery on air springs. Air springs are often equipped with additional damping devices.

[0003] Damping mechanisms for air springs are known from the state of the art, which fulfil their function using various damping media.

[0004] One option is to connect a hydraulically operated shock absorber in parallel with the air spring. These shock absorbers typically have different damping characteristics in the rebound and compression directions. Thus, the shock absorber can counteract the compression with a low damping force in the compression stage, for example, during wheel compression, while the rebound stage slows down the rebound movement with a greater damping force.

[0005] A disadvantage is that hydraulic dampers, as separate components, incur significant additional costs and also require a lot of installation space. Furthermore, the disposal of the hydraulic fluid at the end of the hydraulic damper's lifespan, as well as the risk of leakage in the event of leaks, is a critical consideration from an environmental and sustainability perspective.

[0006] Another damping mechanism provides that during the compression and rebound of the air spring, as a result of pressure differences, air flows from the pressure chamber of the air spring into another chamber, so that energy is dissipated during the overflow, whereby a damping effect can be achieved.

[0007] WO 2016 168 500 A1 discloses a damping device for an air spring, wherein the damping device comprises an orifice arrangement and a valve. The valve exhibits different flow characteristics depending on the pressure difference between the two volumes, allowing different damping characteristics of the air spring to be achieved in the rebound and compression directions. The damping effect is essentially the thermodynamic energy loss at the orifices and in the throttles.

[0008] When using an orifice plate arrangement, the pressure loss is proportional to the square of the flow volume. The effectiveness of the damping device is thus optimized for a narrow range of vibration amplitudes, which is why the correct dimensioning of the orifice plate cross-section is particularly important and must be determined on a case-by-case basis.

[0009] SU 1 222 930 A2 discloses another damping device for an air spring. SU 1 222 930 A2 discloses an air spring with the features of the preamble of claim 1.

[0010] WO 2017 004 472 A1 discloses a damping mechanism in the form of a coiled air channel through which air flows back and forth between the working volume and the piston. The flow losses of the fluid in the channel cause damping. In addition to damping, absorption effects can also be utilized using the air mass in the channel.

[0011] JP 2008 114681 A discloses another air spring.

[0012] DE 296 20 211 U1 discloses a damping device in which a helical overflow line is arranged between an air spring and a damper pot, connecting them to each other. The flow losses within the overflow line during the overflow of the air volume between the air spring and the damper pot cause damping.

[0013] The disadvantage of the previously introduced state of the art is that no different damping mechanisms can be achieved for the tension and compression directions of the air spring, which does not correspond to the ideal of a vehicle damper. Task

[0014] The invention is based on the object of providing a damping device for an air spring that enables different damping mechanisms for the rebound and compression directions. In particular, low damping forces should preferably be applied during an initial rapid increase. Furthermore, the object is to operate the damping device without environmentally harmful media. Solution to the task

[0015] The solution to this problem is provided by an air spring with the features of the main claim.

[0016] Claim 10 discloses a seat suspension of a motor vehicle with an air spring according to the invention.

[0017] Claim 11 discloses a cabin mounting of a motor vehicle with an air spring according to the invention.

[0018] Claim 12 discloses a machine bearing with an air spring according to the invention.

[0019] Further advantageous developments are disclosed in the dependent claims. Advantages of the invention

[0020] The air spring according to the invention disclosed in claim 1 comprises a flexible bellows made of elastomeric material, a lower connection part and an upper connection part, a hollow body, and a damping device, wherein the bellows, the lower connection part, and the upper connection part form a first pressure chamber. The hollow body forms a second pressure chamber and has the damping device, wherein the damping device has an air duct with a first end and a second end and a baffle. The baffle and the air duct connect the first pressure chamber and the second pressure chamber to one another. The damping device has a Venturi nozzle, wherein the baffle opens into an inflow side of the Venturi nozzle, and the second end of the air duct opens into a vacuum connection of the Venturi nozzle. According to the invention, the air duct is helical.

[0021] In other words, by arranging the air duct in a spiral or meandering pattern, the effective length of the air duct can be varied within a predetermined installation volume. By varying the effective length, the dissipation of kinetic energy within the air duct can be adapted to the specific application. Consequently, the damping effect of the damping device can be adjusted by varying the effective length of the air duct.

[0022] In other words, the air spring according to the invention comprises two pressure chambers that are separated from each other. The first and second pressure chambers are connected to each other via two openings in the wall of the hollow body, an air duct, and a baffle. The air duct and baffle, together with the Venturi nozzle that connects the air duct and the baffle, form a damping device. More precisely, the baffle opens into the inflow side of the Venturi nozzle, with the second end of the air duct opening into the vacuum port of the Venturi nozzle.

[0023] In one embodiment, the hollow body can be arranged within the volume of the air spring bellows. This can prove advantageous, for example, when using the inventive solution in a bellows air spring, since this way, no additional installation space is required.

[0024] In another embodiment, the hollow body of a rolling bellows air spring can be formed by the piston. This allows existing components of the air spring to be functionally integrated, reducing the number of components and manufacturing effort while maintaining the same space requirements for the air spring.

[0025] The inventive solution enables air damping, eliminating the need for additional damping components and damping media. This can result in space and weight savings, as well as ecological advantages for the spring-damper system, compared to conventional solutions. Furthermore, the use of a Venturi nozzle allows for various damping characteristics to be achieved during the compression and rebound of the air spring and can be adapted to specific applications.

[0026] In principle, all elastomers known to the expert can be used as the material for the bellows.In a preferred embodiment, the elastomer is selected from the group consisting of ethylene-propylene copolymer (EPM) or ethylene-propylene-diene copolymer (EPDM) or nitrile rubber (NBR) or (partially) hydrogenated nitrile rubber (HNBR) or fluororubber (FKM) or chloroprene rubber (CR) or natural rubber (NR) or styrene-butadiene rubber (SBR) or isoprene rubber (IR) or butyl rubber (IIR) or bromobutyl rubber (BIIR) or chlorobutyl rubber (CIIR) or butadiene rubber (BR) or chlorinated polyethylene (CM) or chlorosulfonated polyethylene (CSM) or polyepichlorohydrin (ECO) or ethylene-vinyl acetate rubber (EVA) or acrylate rubber (ACM) or Ethylene acrylate rubber (AEM) or silicone rubber (MQ, VMQ, PVMQ, FVMQ) or fluorinated methyl silicone rubber (MFQ) or perfluorinated propylene rubber (FFPM) or perfluorocarbon rubber (FFKM).

[0027] The rubbers mentioned can be used alone or in a blend.

[0028] According to one aspect, the hollow body is arranged within the first pressure chamber. In other words, the hollow body divides the internal volume of the air spring into a first pressure chamber and a second pressure chamber. This results in a particularly advantageous, very compact design in which the volume of the hollow body and the damping device can be integrated into the existing installation volume of the air spring. This enables the use of the air spring according to the invention in applications that require conventional air springs of the same installation volume.

[0029] According to a further aspect of the present invention, the hollow body is arranged outside the first pressure chamber. In other words, a commercially available air spring can be connected to an additional volume outside the air spring. This advantageously allows existing air spring designs to be expanded with an additional volume and a damping device without redesigning the air spring.

[0030] A further advantageous design is that existing components outside the air spring can be used as additional volume with a damping device. This allows existing components of the air spring to be functionally integrated, reducing the number of components and manufacturing effort while maintaining the same space requirements for the air spring.

[0031] According to a further aspect of the present invention, the air spring is designed as a bellows air spring. The aforementioned advantages of the inventive solution can thus be transferred to a bellows air spring.

[0032] According to a further aspect of the present invention, the air spring is designed as a rolling bellows air spring, in which the lower connecting part is formed by a piston. In this embodiment, the hollow body can be arranged either inside or outside the first pressure chamber. The aforementioned advantages of the inventive solution can thus be transferred to a rolling bellows air spring.

[0033] According to a further aspect of the present invention, the piston is designed as a second pressure chamber. In other words, in this embodiment, the hollow body is arranged outside the first pressure chamber. It is particularly advantageous that the piston simultaneously forms the hollow body, thereby functionally integrating existing components of the air spring and reducing the number of components and manufacturing effort. At the same time, the space required for the air spring remains unchanged.

[0034] According to a further aspect of the present invention, the upper connection part has a connection to the external air supply. This allows the upper connection part to be functionally integrated into the air spring system, thereby reducing the number of components and manufacturing costs. This can generate economic advantages.

[0035] According to a further aspect of the present invention, the air duct is designed in a hose- or tube-shaped manner. One advantage of a round cross-section is that the air duct is particularly flexible.

[0036] According to a further aspect of the present invention, the aperture can be closed by a check valve with a spring-loaded closing element. In other words, the aperture valve can be open when air flows into the second pressure chamber during the compression process. During rebound and a reversal of the flow direction, the valve can be closed, allowing the air to flow back into the first pressure chamber exclusively through the air channel. This allows different damping characteristics to be achieved during the compression or rebound of the air spring, depending on the air flow direction.

[0037] A further embodiment of the present invention discloses a seat suspension of a motor vehicle with an air spring according to the invention. The advantages of the air spring according to the invention explained above can thus be applied to any seat suspension of a motor vehicle.

[0038] A further embodiment of the present invention discloses a cabin suspension of a motor vehicle with an air spring according to the invention. The advantages of the air spring according to the invention explained above can thus be applied to a wide variety of cabin suspensions of a motor vehicle.

[0039] A further embodiment of the present invention discloses a machine mounting with an air spring according to the invention. The advantages of the air spring according to the invention explained above can thus be applied to a wide variety of machine mountings. Explanation of figures

[0040] Various embodiments of the invention are explained in more detail below with reference to the figures. Fig. 1 shows a bellows air spring with a damping device according to the invention within the first pressure chamber in a sectional view. Fig. 2 shows a rolling bellows air spring with a damping device according to the invention outside the first pressure chamber in a sectional view. Fig. 3 shows a damping device according to the invention. Fig. 4a shows the spring height of an air spring on the axle of a vehicle over time. Fig. 4b shows the temporal progression of the pressures within the first and second pressure chamber.

[0041] Fig. 1shows a bellows air spring 1 with a damping device 9 according to the invention within the first pressure chamber 6 in a sectional view. The air spring 1 has a flexible bellows 2, a lower connection part 3 and an upper connection part 4. A rigid-walled hollow body 5 is arranged inside the first pressure chamber 6, which is formed by the flexible bellows 2, the lower connection part 3 and the upper connection part 4. The hollow body 5 is connected to the lower connection part 3. The hollow body 5 divides the interior of the air spring 1 into a first pressure chamber 6 and a second pressure chamber 7. The upper connection part 4 has a connection 8 for the external air supply. The air spring 1 is supplied with air by a compressor via the connection 8.A damping device 9 is arranged inside the hollow body 5, which connects the first pressure chamber 6 and the second pressure chamber 7 to one another, so that the air can flow from one pressure chamber 6, 7 into the other pressure chamber 6, 7 via the damping device 9. The structure of the damping device 9 is described in the description of the . Figure 3 explained in more detail.

[0042] Fig. 2shows a further exemplary embodiment of the air spring 21 according to the invention, wherein a rolling bellows air spring 21 with a damping device 29 according to the invention is arranged outside the first pressure chamber 26. In the illustrated exemplary embodiment, the piston 25 serves as the second pressure chamber 27. The piston 25 is connected to a chassis component and transmits the compression and rebound movements to the air spring 21. The bellows 22 is connected in a gas-tight manner to the upper connection part 24 and the piston 25. The air required for operation can be supplied to the first pressure chamber 26 via the connection to the external air supply 28.

[0043] Figure 3shows the damping device 9 according to the invention, which is arranged in the hollow body 5. The damping device 9 has a hose- or tubular air duct 10, a baffle 11, and a Venturi nozzle 12. The air duct 10 is connected to the first pressure chamber 6 by a first end 13 through the wall of the hollow body 5. The opposite second end 14 of the air duct 10 opens into the vacuum connection 17 of the Venturi nozzle 12. The inflow side 15 of the Venturi nozzle 12 is formed by the baffle 11. The inflow side 15 also has a check valve with a spring-loaded closing element 16.

[0044] During the compression process, the bellows 2, 22 is compressed, so that the pressure in the first pressure chamber 6, 26 increases. As a result of the pressure increase, the check valve 16 opens, so that additional air flows through the orifice 11 from the first pressure chamber 6, 26 into the second pressure chamber 7, 27. This air flow passes through the vacuum connection 17 in the Venturi nozzle 12. This creates a local pressure at the second end 14 of the air duct 10 which is lower than in the second pressure chamber 7, 27. Thus, during the first pressure increase in the second pressure chamber 7, 27, the air duct 10 experiences a higher pressure difference between its ends 13 and 14 than would be the case without the Venturi nozzle 12.The higher pressure difference between the first pressure chamber 6, 26 and the second pressure chamber 7, 27 leads to a higher volume flow per unit of time and thus to a reduction of the peak pressure at maximum deflection, which is equivalent to a softer initial deflection.

[0045] The air damping as an interaction of air duct 10, aperture 11 and Venturi nozzle 12 is shown in the diagrams of the Figures 4a and 4b explained. The diagram Figure 4a represents the spring height of an axle spring over time. Figure 4bshows the temporal progression of the pressures in the first pressure chamber 6, 26 and the second pressure chamber 7, 27. As an example, it is assumed that the air spring 1, 21 in the central position has a height 40 of H = 250 mm and a static operating pressure 41 of p = 6 bar. It is further assumed that, as a result of an obstacle on the road, e.g. a bump, the air spring 1, 21 experiences a very rapid compression 42 in fractions of a second. As a result of the compression 42, the bellows 2, 22 is compressed and the first pressure chamber 6 becomes smaller, which in turn is accompanied by an equally rapid pressure increase 43 within the first pressure chamber 6. At time t = 2s, the maximum point of deflection 44 is H = 150 mm, whereby the maximum pressure with Venturi nozzle 45 in the first pressure chamber 6 reaches p = 12 bar, while when using the Venturi nozzle 12 a maximum pressure 48 of 14.8 bar is reached.

[0046] The subsequent movements represent a decay process at the natural frequency of the air spring suspension. This decay process must be dampened as effectively as possible with the damping device 9, 29 according to the invention, while low damping forces should preferably be applied during an initial rapid increase.

[0047] The reduction of the damper forces during the initial compression is achieved according to the invention by using a Venturi nozzle 12. The pressure increase 43 in the first pressure chamber 6 opens the check valve 16, so that air flows through the orifice 11 from the first pressure chamber 6, 26 into the second pressure chamber 7, 27. This air flow passes through the vacuum connection 17 in the Venturi nozzle 12. This creates a local pressure at the second end 14 of the air duct 10 which is lower than in the second pressure chamber 7, 27. Thus, during the first pressure increase in the second pressure chamber 7, 27, the air duct 10 experiences a higher pressure difference between its ends 13 and 14 than would be the case without the Venturi nozzle 12.The higher pressure difference between the first pressure chamber 6, 26 and the second pressure chamber 7, 27 leads to a higher volume flow per unit of time and thus to a reduction of the peak pressure at maximum deflection, which is equivalent to a softer initial deflection 42.

[0048] In the illustrated embodiment of the damping device 9, 29, the aperture is designed with a large cross-section. This allows a sufficiently large air flow for a large initial deflection 42 and thereby also promotes the generation of a high negative pressure in the Venturi nozzle 12. The diagram in Figure 4balso shows the temporal pressure curve in the second pressure chamber 7, 27 in comparison between the advantageous damping according to the invention by means of a Venturi nozzle 46 and without a Venturi nozzle 47, as well as the temporal pressure increase 43 in the first pressure chamber 6, 26 to a maximum pressure without a Venturi nozzle 48 in comparison to a maximum pressure with a Venturi nozzle 45. For the further oscillation process, the Venturi nozzle 12 in combination with the orifice 11 has no significant influence.

[0049] During rebound and extension, the flow direction is reversed. In this direction, the check valve 16 blocks the flow to the orifice 11, and the air flows exclusively through channel 10, creating a strong damping effect.

[0050] During a subsequent compression, the amplitude is already significantly reduced, so that only a small pressure difference exists between the first pressure chamber 6 and the second pressure chamber 7. The smaller pressure difference compared to the initial compression leads to a smaller volume flow through the orifice 11 and thus to a significantly lower influence of the Venturi nozzle 12. As pressure differences decrease, the spring-loaded check valve 16 and thus also the orifice 11 remain closed, so that damping occurs exclusively via the air channel 10. List of reference symbols (part of the description)

[0051] 1Air spring 2Bellows 3Lower connection part 4Upper connection part 5Hollow body 6First pressure chamber 7Second pressure chamber 8Connection to external air supply 9Damping device 10Air duct 11Orifice plate 12Venturi nozzle 13First end 14Second end 15Inlet side 16Spring-loaded closing element 17Vacuum connection 21Air spring 22Bellows 24Upper connection part 25Piston / hollow body 26First pressure chamber 27Second pressure chamber 28Connection to external air supply 29Damping device 40Height of the air spring in the center position 41Static operating pressure 42Compression 43Pressure rise 44Peak compression 45Peak pressure in the first pressure chamber with Venturi nozzle 46Damping characteristic of the second pressure chamber with Venturi nozzle 47Damping characteristic of the second pressure chamber without Venturi nozzle 48Peak pressure in the first pressure chamber without Venturi nozzle

Claims

1. Air spring (1, 21), comprising a flexible bellows (2, 22) made of elastomeric material, a lower connection part (3) and an upper connection part (4, 24), a hollow body (5, 25) and a damping device (9, 29), wherein the bellows (2, 22), the lower connection part (3) and the upper connection part (4, 24) form a first pressure chamber (6, 26), wherein the hollow body (5, 25) forms a second pressure chamber (7, 27) and has the damping device (9, 29), wherein the damping device (9, 29) has an air duct (10) with a first end (13) and a second end (14) and an orifice (11), wherein the orifice (11) and the air duct (10) connect the first pressure chamber (6, 26) and the second pressure chamber (7, 27) to one another, wherein the damping device (9) has a Venturi nozzle (12), wherein the orifice (11) opens into an inflow side (15) of the Venturi nozzle (12), and the second end (14) of the air duct (10) opens into a negative-pressure connection (17) of the Venturi nozzle (12), characterized in that the air duct (10) is helical.

2. Air spring (1, 21) according to Claim 1, characterized in that the hollow body (5, 25) is arranged inside the first pressure chamber (6, 26).

3. Air spring (1, 21) according to Claim 1, characterized in that the hollow body (5, 25) is arranged outside the first pressure chamber (6, 26).

4. Air spring (1) according to Claim 1, characterized in that the air spring (1) is configured as a folding bellows air spring.

5. Air spring (21) according to Claim 1, characterized in that the air spring (21) is configured as a rolling bellows air spring in which the lower connection part (3) is formed by a piston (25).

6. Air spring (21) according to Claim 5, characterized in that the piston (25) is configured as a second pressure chamber (27).

7. Air spring (1, 21) according to one of the preceding claims, characterized in that the upper connection part (4, 24) has a connection (8, 28) for external air supply.

8. Air spring (1, 21) according to one of the preceding claims, characterized in that the air duct (10) is hose-shaped or tubular.

9. Air spring (1, 21) according to one of the preceding claims, characterized in that the orifice (11) can be closed by a check valve having a spring-loaded closing element (16).

10. Seat suspension of a motor vehicle having an air spring (1, 21) according to one of Claims 1 to 9.

11. Cab mounting of a motor vehicle having an air spring (1, 21) according to one of Claims 1 to 9.

12. Machine mounting having an air spring (1, 21) according to one of Claims 1 to 9.