METHOD FOR OPERATING A PNEUMATIC SYSTEM

Description

[0001] The invention relates to a method according to the preamble of claim 1 for operating a pneumatic system comprising a compressed air supply system and an air spring system with air springs pneumatically connected to the compressed air supply system, for a vehicle.

[0002] The components of a compressed air supply system are interconnected in such a way that, by controlling the compressed air supply system with a control unit, air can be drawn in from the environment by a compressor, dried by an air dryer, and the dry compressed air can be directed via an air distribution module into a compressed air reservoir and / or into the air springs. A pressure sensor is installed and configured to measure the pressure level in the air distribution module and provide a pressure sensor signal representing the measured pressure level to the control unit. The control unit can adjust the control of the compressed air supply system based on the measured pressure.

[0003] By inflating the air springs, a vehicle can be raised relative to the ground. When compressed air is released from the air springs into the surrounding atmosphere or into the compressed air reservoir, the vehicle can be lowered relative to the ground.

[0004] It is often desirable for a vehicle to be able to be raised and lowered relatively quickly. This is particularly true for off-road vehicles and sport utility vehicles (SUVs) with high-performance engines. It is desirable to equip the vehicle with relatively low ground clearance for high speeds on the road and relatively high ground clearance for off-road use. Furthermore, it is desirable to implement changes in ground clearance as quickly as possible, which increases the demands on the speed, flexibility, and reliability of a compressed air supply system.

[0005] This requires correspondingly high pressures in the compressed air supply system. The requirements for an electronically controlled air suspension ( Electronically Controlled Air Suspension, ECAS (short for ECAS) for a vehicle therefore regularly includes high inlet and outlet airflows combined with high pressures in the compressed air supply system.

[0006] High pressures in the compressed air supply system, however, can result in a high noise level when the system is vented, also known as a venting pop. These noises are generally undesirable for vehicle users and are therefore addressed by manufacturers, for example, through the use of silencers. silencers ) , reduced. Therefore, additional components are regularly installed in vehicles to keep the noise level as low as possible when venting the compressed air supply system.

[0007] Among other things, to reduce the use of additional components such as silencers in the vehicle, it was proposed to reduce the noise level when venting the compressed air supply system by means of suitable control of the compressed air supply system for venting.

[0008] A control system for a compressed air supply for venting an air spring system is described, for example, in WO 2008 / 147850 A1. According to this, to reduce noise when venting a gas spring system, the air spring valves should first be opened, thus pressurizing the air springs. The system should then be allowed to reach an equilibrium pressure, which is comparatively lower. Only when the equilibrium pressure has been reached is the exhaust valve opened and the gas spring system vented. The venting process should then take place at a reduced pressure.

[0009] German patent application DE 10 2016 123 201 A1 describes a process for venting a compressor in at least two steps. This involves directing compressed air from the compressor into at least one air spring of an air spring system and subsequently venting it to the environment. It is proposed that the venting process begin when the compressor reaches its maximum pressure. This supposedly allows for a reduced pressure differential during venting to the environment, for example, approximately 8 bar instead of approximately 18 bar. The advantage of this is said to be that venting to the environment is significantly quieter due to the reduced pressure surge.

[0010] DE 100 04 880 A1 relates to an air suspension system for a motor vehicle with a compressor unit, a storage unit and switching valves, via which the individual air springs of the individual vehicle wheels are supplied with compressed air, wherein a vent line leading into the atmosphere, which can be shut off or opened by a shut-off valve, is provided between the compressor unit and the switching valves, wherein measures can be taken to limit the mass flow of air exiting the vent line in a certain time interval compared to an unlimited state.

[0011] JP2009046027A concerns the provision of an energy-saving and cost-effective air circuit in a vehicle, capable of improving vehicle assembly performance. The air circuit, used to supply and return compressed air to an air spring located between the vehicle body and an axle, includes a conductor rail connecting a compressor, a discharge line, and the compressor's suction side.

[0012] US4799707A relates to a gas suspension system for controlling the body position of a vehicle, in which a controller operates a compressor and control valves to supply compressed air to a high-pressure reservoir. After sufficient air has been supplied to the high-pressure reservoir, the compressor is stopped and the control valves are closed, leaving high-pressure air at the compressor's discharge port. A specially designed connecting control valve is then opened for a predetermined duration to connect the compressor's discharge port to a low-pressure reservoir. This reduces the pressure at the discharge port, thus requiring less torque to start the compressor.

[0013] EP 3 863 870 A1 discloses a method for venting a pneumatic system of a vehicle, a pneumatic system and a vehicle, wherein the pneumatic system comprises an air compressor, a pneumatic circuit, an air pressure management system in conjunction with the air compressor and the pneumatic circuit, and a control unit, wherein when a pressure in the pneumatic circuit reaches the cut-off pressure, the pressure in the pneumatic circuit is reduced to a target pressure and wherein the air compressor is operated at at least one venting rate.

[0014] DE 101 20 220 A1 describes an air supply system for a vehicle air suspension system, wherein the air during system venting, after flowing through the dryer, is directed into the environment or the housing of the compressor without significant deflection.

[0015] DE 10 2017 010 772 A1 relates to a compressed air supply system with a low-pressure storage tank and a high-pressure storage tank for operating a pneumatic system of a vehicle, in particular for supplying a vehicle's air suspension system with compressed air.

[0016] These approaches can still be improved. In particular, it is desirable to ensure a comparatively low venting noise without impairing the functionality of the pneumatic system during venting.

[0017] The invention is based on the objective of providing an improved or at least alternative method for operating a pneumatic system. In particular, the invention is based on the objective of providing a method for operating a pneumatic system that avoids or at least reduces the problems of the prior art.

[0018] Preferably, the invention provides a method for operating a pneumatic system in which a comparatively low venting noise is ensured without excessive impairment of the pneumatic system's functionality during venting. Preferably, excessive overpressure in the air dryer should be efficiently avoided during venting and preferably reduced within a short time. This applies in particular to overpressures above 12 bar or between 12 bar and 18 bar or above.

[0019] The invention is based in particular on the objective of providing a method for efficient pressure management of high pressures, especially in air dryers. The preferred pressure management system should ideally have no effect, or only a limited or acceptable effect, on the driving characteristics of a vehicle.

[0020] This problem is solved by a method of claim 1.

[0021] A method for operating a pneumatic system comprising a compressed air supply system and an air spring system with air springs pneumatically connected to the compressed air supply system for a vehicle, in particular for a passenger car, is proposed.

[0022] The compressed air supply system has a pneumatic main line and an air dryer in the pneumatic main line, and the pneumatic main line has a compressor connection to a compressor and a compressed air supply connection to an air distribution module.

[0023] The air spring system of the pneumatic system has a number of air springs that are pneumatically connected via a gallery of the air spring system.

[0024] In a first embodiment of the invention, the air spring system of the pneumatic system includes the air distribution module. .In an alternative variant according to the invention, the air distribution module is part of the compressed air supply system.

[0025] The compressor of the compressed air supply system can, for example, be designed as a compressor.

[0026] The pneumatic system includes a control unit for controlling the compressed air supply system and the air spring system.

[0027] In this process, the air dryer and the air distribution module represent a pressurized volume.

[0028] In the process, the overpressure volume initially has a pressure, in particular after a filling step of the compressed air supply system, which is greater than a pressure in another part of the compressed air supply system, in particular than a pressure in a compensation volume, namely in a compensation volume comprising at least one air spring and an intermediate storage tank.

[0029] According to the invention, in the method for pressure reduction in the overpressure volume, namely in the air dryer and / or the air distribution module, compressed air is discharged from the overpressure volume into the compensation volume under pressure reduction in the overpressure volume, namely under pressure reduction in the air dryer and under pressure reduction in the air distribution module, wherein compressed air is discharged into a first air spring of the air spring system and into the intermediate storage.

[0030] If, in a final process step, the intermediate storage tank is filled with compressed air from the overpressure volume, particularly after the air springs have been filled, the pressure level for the venting process can be lowered comparatively further, especially below the pressure level of the air springs. This allows the compressed air supply system to be vented with a comparatively lower venting noise level.

[0031] The intermediate storage tank can also be filled in a first process step, particularly before filling the air springs with compressed air from the overpressure volume. This has the advantage that any impact on potential changes in the vehicle's ride height caused by filling the air springs with compressed air from the overpressure volume can be comparatively reduced.

[0032] The invention is based on the understanding that high pressures within a compressed air supply system are necessary to meet the requirements for short response times. However, as a rule, the higher the pressure, the higher the noise level when venting the compressed air supply system. A high noise level is further exacerbated by a comparatively large outlet cross-section, which is necessary to ensure high efficiency of the air dryer.

[0033] The invention is further based on the consideration that silencers often need to be comparatively large in order to effectively reduce the noise level at the outlet. However, large silencers are often difficult to integrate into a vehicle due to their size and also incur additional costs. A solution involving the use of two outlets, each with comparatively smaller cross-sections, is also conceivable to reduce the noise level at the outlet. However, this solution is comparatively complex and expensive.

[0034] The invention is based on the further finding that the pressures in the air dryer and / or the air distribution module are particularly critical for the noise level at the outlet and can often reach up to 18 bar. In contrast, the pressure in the compressed air reservoir is often not critical and can be reduced during the operation of a vehicle, e.g., at high speed and with a correspondingly high noise level in the surrounding area.

[0035] The pressures in the air dryer and / or the air distribution module are particularly critical for the noise level at the outlet, and these pressures typically range between 12 bar and 18 bar. Especially at pressures below 12 bar, it may be sufficient to vent the compressed air supply system without first reducing the pressure, for example, by pressurizing the air springs. Conventional silencers, which are relatively small but sufficient to adequately reduce the noise level at the outlet at this pressure, can be used for venting pressures below 12 bar.

[0036] The invention is also based on the consideration that reducing the pressure in the compressed air supply system by adjusting the system's control can significantly reduce the noise level at the outlet during venting. Therefore, by appropriately controlling the compressed air supply system, it is unnecessary to install additional, comparatively large silencers in the vehicle.

[0037] However, if the compressed air supply system is regulated in such a way that one or more air springs are pressurized with so much compressed air at once that the pressure at the outlet, and thus the noise level during venting, is sufficiently reduced, this can negatively affect the vehicle's handling and be noticeable to the driver. For example, the vehicle may be pressurized with so much compressed air at once that the driver notices the vehicle being lifted relative to the ground. Even while driving, the filling or deflating of the air springs with a comparatively large amount of compressed air can be noticeable to the driver and, for example, cause uncertainty. A noticeable change in a vehicle's handling characteristics can therefore also pose a safety risk.

[0038] Therefore, in the method according to the invention, it is provided that compressed air is discharged either into a first air spring of the air spring system and additionally into the intermediate storage tank in order to reduce the pressure in the overpressure volume.

[0039] If compressed air is also fed into the intermediate reservoir in addition to the air springs, the pressure in the overpressure volume can be reduced even further. In particular, it is possible to lower the pressure in the overpressure volume below the pressure level of the air springs.

[0040] Discharge of compressed air into the intermediate storage tank can be carried out, in particular, as the final process step immediately before venting compressed air from the overpressure volume into the surrounding atmosphere. In this case, the air springs are preferably pressurized with compressed air first, followed by the intermediate storage tank. This makes it possible to further reduce the pressure level at the outlet and to vent the compressed air supply system with an even lower noise level.

[0041] In this process, compressed air can also be initially directed into the intermediate reservoir. The intermediate reservoir is therefore filled before the air springs are filled. After the intermediate reservoir is filled, the remaining compressed air from the overpressure volume can be distributed to one or more of the air springs. This has the advantage that the pressure reduction in the overpressure volume has little or no effect on the vehicle's handling characteristics. In particular, this reduces the vehicle's tendency to rise due to the pressurization of the air springs. This is possible because the pressure in the overpressure volume has already been reduced by filling the intermediate reservoir. Only the remaining compressed air then needs to be distributed to the air springs.

[0042] In a preferred embodiment of the method, the compensation volume comprises the first air spring and the intermediate reservoir a second air spring. In this embodiment, compressed air is preferably supplied sequentially, one after the other, to the first air spring and then to the second air spring.

[0043] The term "sequentially" means that the air springs are pressurized with compressed air from the air dryer and / or the air distribution module immediately one after the other, either individually or in groups of two, i.e., without any further intermediate steps such as additional venting or filling. For example, the air spring valve of the first air spring is opened to pressurize it with compressed air from the air dryer and / or the air distribution module. The air spring valve of this air spring is then closed again. Once the air spring valve of this air spring is closed, the air spring valve of the next air spring is opened to pressurize it with compressed air. This procedure is applied sequentially to each of the air springs to pressurize them individually with compressed air from the air dryer and / or the air distribution module.Therefore, if in the process step air springs are individually supplied with compressed air from the air dryer and / or the air distribution module one after the other, only one of the air springs is supplied with compressed air at any given time and the air spring valves of the other air springs are closed during this time.

[0044] However, if, in this process step, air springs are pressurized with compressed air from the air dryer and / or the air distribution module sequentially in groups of two, two of the corresponding air spring valves of the air springs are opened, and the remaining air spring valves of the other air springs are closed. Only after the two air springs have been pressurized with compressed air from the air dryer and / or the air distribution module and their air spring valves are closed, are the two remaining air springs also pressurized with compressed air from the air dryer and / or the air distribution module. In this process step, only two air springs are pressurized with compressed air at any one time, and the air spring valves of the remaining air springs are closed during this period.

[0045] The first air spring can belong to a first group of air springs. The second air spring can belong to a second group of air springs. Several air springs from one of these groups can also be filled with compressed air simultaneously. A first group could, for example, comprise the air springs of the front axle, and a second group could, for example, comprise the air springs of the rear axle of a vehicle. For instance, the first air spring could be located on the front axle of the vehicle, and the second air spring on the rear axle.

[0046] Alternatively, in this method, groups of at least two air springs could be pressurized with compressed air from the air dryer and / or the air distribution module sequentially. For example, groups of three or four air springs. However, it is preferred that, for example, the air springs of a vehicle's front axle form a first group of air springs and the air springs of a vehicle's rear axle form a second group of air springs. The first group of air springs is not pressurized with compressed air from the air dryer and / or the air distribution module simultaneously, but rather after or before the second group of air springs.

[0047] Advantageous further developments of the invention can be found in the dependent claims and specify in detail advantageous possibilities for realizing the above-explained concept within the scope of the task and with regard to further advantages.

[0048] According to the invention, the intermediate storage unit comprises the compressor and a connecting volume. The connecting volume has a pneumatic return line that connects the reservoir to the compressor via a check valve. The pneumatic return line of the connecting volume, which connects the reservoir to the compressor via a check valve, is in particular an additional pneumatic line beyond the main pneumatic line. For example, compressed air can be supplied to the air springs via the main pneumatic line. To reduce the pressure in the air springs, the check valve can be opened and the compressed air from the air springs can be conveyed via the return line to the outlet or into another volume of the compressed air supply system.

[0049] The gallery can also be designed as part of the air distribution module.

[0050] Alternatively or in addition to filling the air springs with compressed air from the overpressure volume, compressed air can be discharged from the overpressure volume into the compressor.

[0051] Alternatively or additionally to filling the air springs and / or the compressor with compressed air, compressed air can be discharged from the overpressure volume into the connection volume.

[0052] Simply by diverting compressed air only into the compressor or only into the connection volume, the pressure in the overpressure volume can be reduced.

[0053] If discharging compressed air into the compressor and / or the connecting volume is insufficient to reduce the pressure in the overpressure volume by the desired amount, the method may further provide for additionally discharging compressed air into at least one of the air springs. Thus, compressed air may also be additionally discharged into exactly one air spring. This air spring may be the one whose pressure has the smallest pressure difference compared to the pressure in the air dryer. If, again, discharging compressed air into only one of the air springs is insufficient to reduce the pressure in the overpressure volume by the desired amount, it may further be provided that compressed air is discharged into the remaining air springs sequentially, either individually or sequentially in at least two groups of at least two air springs.

[0054] If the compensation volume includes the volumes of more than one component of the pneumatic system, e.g., the first air spring and the compressor, or the first air spring and the connecting volume, or the compressor and the connecting volume, the pressure in the overpressure volume can be reduced even further.

[0055] If the compensation volume includes the volumes of the first air spring, the compressor and the connecting volume, the pressure in the overpressure volume can be reduced even further.

[0056] In this context, the volume of the air springs refers in particular to the volume of the air spring bellows.

[0057] Particularly when the air springs are pressurized with compressed air from the overpressure volume, either individually or in groups of two, the pressure in the overpressure volume can be reduced incrementally over a comparatively longer period. The amount of compressed air by which the pressure in the air dryer and / or the air distribution module is to be reduced is also distributed among the air springs of the air spring system connected to the compressed air supply system, so that not just one air spring has to absorb the entire amount of compressed air. The amount of compressed air per air spring is therefore comparatively small. This method thus allows the pressure in the air dryer and / or the air distribution module to be reduced in such a way that the pressure reduction has no, or at least minimal, effect on the driving characteristics of a vehicle. Driver safety can therefore be increased.Venting compressed air into the compressor and / or the connection volume does not affect the vehicle's driving characteristics, as this neither raises nor lowers the vehicle. Venting compressed air into the compressor and / or the connection volume in addition to the air springs can be particularly useful when a relatively large pressure reduction in the overpressure volume is required in the short term, without significantly affecting the vehicle's driving characteristics.

[0058] The pressure in the air dryer and / or the air distribution module can be reduced, for example, to prevent it from exceeding a critical limit. This protects the air dryer and / or the air distribution module from damage.

[0059] The pressure in the air dryer and / or the air distribution module can also be reduced because the compressed air supply system will subsequently need to be vented. Venting the compressed air supply system then occurs at a comparatively lower pressure at the outlet, resulting in a comparatively lower noise level. This also improves safety and comfort for the driver.

[0060] The compressed air supply system operated according to this method can be an open system or a closed system.

[0061] An open system is characterized by the fact that air is drawn in from the surrounding atmosphere by the compressor and delivered to the vehicle's air springs, for example, to raise the vehicle. In an open system, the compressor primarily draws air from the environment or releases air into the environment. However, even an open system can incorporate a compressed air reservoir, between which compressed air can be exchanged with one or more air springs and / or the compressor for pressure regulation within the compressed air supply system.

[0062] In a closed system, compressed air is circulated back and forth between a compressed air reservoir and the air springs to raise or lower the vehicle. Even in a closed system, it may be necessary to replenish the air supply from an external source. Therefore, a compressed air supply system that is a closed system, or operates as one, typically has an inlet with an inlet valve.

[0063] In both open and closed systems, air flows under pressure through an air dryer when filling the compressed air supply system.

[0064] The method may further provide that, after at least two of the air springs have been pressurized with compressed air, either individually or sequentially in at least two groups of at least two air springs, and / or the compressor and / or the connecting volume, the remaining compressed air from the air dryer and / or the air distribution module is at least partially released to the surrounding atmosphere through the outlet. In particular, the air spring valves are closed before venting. It is also preferred that the compressor is brought to idle before venting. A comparatively low pressure is then present at the outlet, so that venting to the surrounding atmosphere occurs at a comparatively lower pressure. The noise level generated by the venting can therefore be comparatively lower.

[0065] In some variations of the process, compressed air from the overpressure volume is sequentially discharged into the first air spring and the intermediate reservoir, starting with the reservoir. This has the advantage that the pressure in the overpressure volume is already reduced before the air springs are filled. Subsequent filling of the air springs with the remaining compressed air from the overpressure volume can then have a comparatively smaller impact on the vehicle's handling characteristics. The impact on the vehicle's handling characteristics from filling the air springs with compressed air can be further reduced by pressurizing the air springs individually, one after the other.

[0066] It is also possible that the intermediate storage tank is only pressurized with the remaining compressed air from the overpressure volume once the air springs of the air spring system have been fully inflated with compressed air from the overpressure volume. In other words, the air springs are inflated first, and only after this process is complete is the intermediate storage tank filled with the remaining compressed air from the overpressure volume. This allows the pressure level in the overpressure volume to be reduced even below the pressure level of the air springs. Subsequent venting of the compressed air supply system to the environment can then be carried out at a comparatively lower pressure at the outlet. Any noise generated during venting can then be reduced even further.

[0067] Optionally, the compressor can be a two-stage compressor, and the connecting volume can include a compressor line that pneumatically connects the first and second compression stages. The compressor line and the rest of the connecting volume then operate at the pressure generated by the first compression stage. The compressed air supply system, and especially the section after the second compressor stage, operates at a comparatively higher pressure. By filling the connecting volume with compressed air from the overpressure volume, the pressure in the overpressure volume can therefore be reduced.

[0068] Alternatively or additionally, the connection volume can include an auxiliary reservoir pneumatically connected to the return line. An auxiliary reservoir represents an additional volume into which compressed air from the overpressure volume can be discharged to reduce the pressure in the overpressure volume. Thus, an auxiliary reservoir increases the capacity of the connection volume.

[0069] The compressor can be a piston compressor and the process may include the removal of compressed air from the overpressure volume into the compressor, or the removal of compressed air from the overpressure volume into at least one piston volume of a compressor piston and / or into a volume of the crankcase and / or into a motor housing of the compressor.

[0070] If compressed air is to be discharged from the overpressure volume into the connecting volume and into at least one of the air springs, or into the compressor and into at least one of the air springs, it is preferred to first discharge compressed air into the connecting volume and / or into the compressor, and then to discharge the remaining compressed air from the overpressure volume into at least one of the air springs. If the pressure in the overpressure volume has not yet been reduced by the desired amount, it is preferred to then pressurize the remaining air springs with compressed air, either individually or sequentially in groups of at least two. Preferably, the air springs are pressurized with compressed air individually or sequentially in groups of at least two until the pressure in the overpressure volume has been reduced by the desired amount.

[0071] In this method, it is preferred that the air springs are pressurized with compressed air from the overpressure volume if the pressure sensor first measures a pressure in the air distribution module that is higher than 10 bar, particularly higher than 11 bar, preferably higher than 12 bar, and most preferably between 12 bar and 18 bar. Especially when the pressure in the overpressure volume is 10 bar or higher, the pressure at the outlet is regularly so high that a comparatively high noise level is generated when venting the compressed air supply system. It is therefore advantageous, particularly at pressures of 10 bar or more, that the air springs are sequentially pressurized with compressed air from the air dryer and / or the air distribution module, either individually or sequentially in groups of two. The pressure at the outlet can then be reduced to such an extent that the noise level during venting is comparatively low.According to the method, at a pressure of 10 bar or more, the pressure in the air dryer and / or the air distribution module can be sequentially supplied with compressed air from the air dryer and / or the air distribution module, either individually or in groups of two, to prevent the pressure in the air dryer and / or the air distribution module from exceeding a critical value, without the reduction of the pressure having a noticeable effect on the driving characteristics of the vehicle.

[0072] The procedure may further provide that the first and the second air spring are supplied with a predetermined quantity of compressed air and / or for a predefined period of time and / or by a predefined pressure drop in the air distribution module, either individually or sequentially in at least two groups of at least two air springs.

[0073] The specified amount of compressed air can be calculated, for example, from the measured pressure of the pressure sensor and the known air dryer and air distribution module volume, as well as the air spring volume.

[0074] The discharge of compressed air from the overpressure volume according to a predefined pressure drop in the air distribution module can be implemented, for example, by diverting a specific pressure drop in the air distribution module to each air spring. For instance, the pressure in the air distribution module can be measured by a pressure sensor, and each air spring can be filled with compressed air for the duration of a predefined pressure drop. For example, each air spring can be filled with compressed air from the overpressure volume after a pressure drop of 1 bar in the air distribution module.

[0075] A predefined time period for filling an air spring with compressed air can be, for example, between 50 ms and 400 ms, e.g., 100 ms. The specified amount of compressed air can be chosen so that the vehicle is not raised too much when the air springs are pressurized. Alternatively, the amount of compressed air can be chosen so that the vehicle is raised only a comparatively small amount with each successive pressurization of the air springs, so that the lifting does not affect the driving characteristics, or at least has a barely noticeable effect. Filling the air springs with a predetermined amount of compressed air also prevents the vehicle from being abruptly tilted relative to the ground. Instead, the vehicle is raised gradually, or rather, air spring by air spring.The air springs can be pressurized with the specified amount of compressed air as often as necessary until the pressure in the air dryer and / or the air distribution module has been reduced by a certain, specifically predetermined, amount or pressure drop. The sequence in which the air springs are pressurized with the specified amount of compressed air can vary. The air springs can be filled sequentially, for example, all the way around a vehicle. Alternatively, air springs can be pressurized individually and alternately. For example, the two air springs of the front axle can be filled alternately with the specified amount of compressed air to gradually raise the vehicle at the front axle. Similarly, the two air springs of the rear axle can be filled alternately with the specified amount of compressed air to gradually raise the vehicle at the rear axle.

[0076] Instead of or in addition to the specified compressed air volume, a predefined time period can also be used for which the air springs are pressurized individually or in groups of two. The specified time period for which an air spring valve is open and the air spring is filled accordingly can also determine the amount of compressed air with which an air spring is to be filled. Controlling the compressed air volume based on the predefined time period is a particularly simple way of limiting the amount of compressed air for a specific air spring.

[0077] Optionally, the first and second air springs can be pressurized with compressed air from the overpressure volume, either individually or sequentially in at least two groups of at least two air springs, based on a measured pressure drop in the air distribution module, a known air dryer volume, air distribution module volume, and the air spring volume of the air springs, and / or an adaptively defined time interval. Pressurizing the air springs with compressed air from the overpressure volume according to an adaptively defined time interval includes controlling the compressed air supply system based on, for example, a measured pressure drop in the air distribution module, a known air dryer volume, an air distribution module volume, and / or the air spring volume of the air springs.

[0078] The system may include provisions for specifying or predefining the compressed air volume and / or duration for one or more air springs depending on the vehicle speed. For example, it may be advantageous to specify or predefine a comparatively small compressed air volume and / or a comparatively short duration when the vehicle is traveling at a comparatively high speed, e.g., more than 80 km / h, 100 km / h, or 130 km / h. Conversely, if the vehicle is traveling at a comparatively lower speed, e.g., less than 80 km / h or 50 km / h, a comparatively larger compressed air volume and / or a comparatively longer duration can be specified or predefinitely.

[0079] It is also conceivable that the compressed air volume and / or duration and / or the predefined pressure drop in the air distribution module for one or more air springs is specified or predefined depending on the diameter of a throttle in the air dryer. The larger the throttle, the greater the compressed air volume and / or duration could be.

[0080] The method may include the provision that the amount of compressed air and / or the duration of compression differs for at least two of the air springs. For example, the amount of compressed air and / or the duration of compression can be selected such that pressurizing the air springs with compressed air has little or no noticeable effect on the vehicle's handling characteristics. The amount of compressed air and / or the duration of compression can also be selected such that the orientation of the vehicle's underbody relative to the ground remains unchanged. In particular, at least two of the air springs can be pressurized with different amounts of compressed air and / or for different durations such that the orientation of the vehicle's underbody relative to the ground remains parallel to the ground during and / or after the air springs are pressurized with compressed air.

[0081] The method may additionally or alternatively provide that the compressed air quantity and / or the duration for at least one of the air springs is determined based on a relative pressure difference between the pressure in the at least one air spring and the pressure in the air dryer and / or the pressure in the air distribution module. However, it is generally preferred that a small quantity of compressed air is discharged into one of the air springs during each inflation process, so that the inflation of the air spring does not negatively affect the vehicle's driving characteristics. For example, a pressure difference between one or more of the air springs and the air dryer and / or the air distribution module can be detected. Based on the detected pressure difference, a control system for supplying the air springs with compressed air from the air dryer and / or the air distribution module can then be adjusted.It can be advantageous to supply the air spring with the highest pressure differential to the air dryer and / or air distribution module with a higher volume of compressed air and / or for a longer duration, so that the pressure in this air spring equals the pressures in the other air springs. For example, the volume of compressed air and / or the duration can be selected for each air spring such that the relative pressure differential between the pressure in the respective air springs and the pressure in the air dryer and / or pressure in the air distribution module is essentially identical for each air spring.However, it can also be advantageous if the pressure difference between the air springs of the front axle of a vehicle and the air dryer and / or the air distribution module is greater than the pressure difference between the air springs of the rear axle of a vehicle and the air dryer and / or the air distribution module, or vice versa. The amount of compressed air supplied and / or the duration for which at least one of the air springs is pressurized, based on a relative pressure difference between the pressure in the at least one air spring and the pressure in the air dryer and / or the pressure in the air distribution module, can, for example, be determined by a control unit according to these specifications.

[0082] The process can optionally include the option of pressurizing a volume of the compressor, e.g., a piston volume, with a predetermined quantity of compressed air and / or for a predefined duration and / or for a predefined pressure drop within the overpressure volume using compressed air from the air dryer and / or the air distribution module. If, in addition to the air springs, a volume of the compressor is pressurized with a predetermined quantity of compressed air and / or for a predefined duration using compressed air from the air dryer and / or the air distribution module, the pressure in the air dryer and / or the air distribution module can be further reduced. Subsequent venting of the compressed air supply system can thus further reduce the noise level generated during venting.If, in addition to the air springs, a volume of the compressor is supplied with a predetermined amount of compressed air and / or compressed air from the air dryer and / or the air distribution module for a predefined period of time, this has the further advantage that not all the excess compressed air has to be discharged into the air springs alone, so that the vehicle has to be raised comparatively less in order to reduce the pressure in the air dryer and / or the air distribution module by a certain amount.

[0083] Furthermore, or alternatively, the procedure may provide that the compressed air supply system includes an additional storage tank, and that, in addition to the air springs, the additional storage tank is supplied with a predetermined quantity of compressed air and / or compressed air from the air dryer and / or the air distribution module for a predefined period of time.

[0084] The auxiliary reservoir is, in particular, part of the connection volume and is preferably pneumatically connected to the return line. The auxiliary reservoir can, in particular, be an independent component of the compressed air supply system, which, as an additional component, is connected to the other components of the compressed air supply system via pneumatic connections. An auxiliary reservoir generally allows for greater flexibility in distributing excess compressed air among the components of the compressed air supply system. With an auxiliary reservoir, it is particularly possible that not all of the excess compressed air is distributed to the air springs, but rather that a portion of this excess compressed air is diverted to the auxiliary reservoir. The amount of compressed air consumed by the air springs can then be comparatively lower.Reducing the compressed air in the air dryer and / or the air distribution module can therefore have a comparatively smaller impact on the driving characteristics of a vehicle, e.g. because the vehicle is raised comparatively less.

[0085] Preferably, in this method, compressed air from the air dryer and / or the air distribution module is first directed to the air spring whose pressure has the smallest pressure difference compared to the pressure in the air distribution module. The air spring with the smallest pressure difference to the pressure in the air distribution module is, in particular, the first air spring.

[0086] For example, the pressure in the air springs can be detected by appropriately arranged additional pressure sensors and the detected pressures can be made available to a control unit.

[0087] If compressed air from the air dryer and / or the air distribution module is first directed to the air spring whose pressure has the smallest difference compared to the pressure in the air distribution module, it can be achieved, in particular, that the air springs are pressurized with only comparatively small amounts of compressed air. This has the advantage that the vehicle is raised by a comparatively small amount. Therefore, raising the vehicle has no effect, or at least only a negligible effect, on its handling characteristics. Pressurizing the air spring with the smallest pressure difference compared to the pressure in the air distribution module first has the further advantage that the vehicle is not, or at least hardly, tilted relative to the ground.

[0088] If compressed air from the air dryer and / or the air distribution module is first directed into the air spring whose pressure has the smallest difference between the pressures in the other air springs and the pressure in the air distribution module, then in a subsequent step, the next remaining air spring with the smallest pressure difference compared to the pressure in the air distribution module can be pressurized with compressed air. If excess compressed air from the air dryer and / or the air distribution module still needs to be distributed to the air springs, this process can be continued air spring by air spring until the pressure in the air dryer and / or the air distribution module has been reduced by the desired amount or pressure drop.

[0089] If compressed air from the air dryer and / or the air distribution module is first directed into the air spring with the highest pressure relative to the other air springs, the pressure in this air spring can be equalized. Any potential pressure imbalance between the air springs will then not be exacerbated, but rather reduced. Alternatively, the process can be carried out sequentially, starting with the air spring with the highest pressure relative to the other air springs, until a specific quantity of compressed air has been discharged from the air dryer and / or the air distribution module into the air springs.If the process begins with the air spring whose pressure is greatest compared to the pressures in the other air springs, it can be achieved that, after a certain amount of compressed air has been discharged into the air springs, the maximum pressure difference between one of the air springs and the air dryer and / or the air distribution module has been reduced.

[0090] In particular, if in the process compressed air from the air dryer and / or the air distribution module is first directed into the air spring whose pressure has the smallest pressure difference compared to the pressure in the air distribution module, the compressed air from the air dryer and / or the air distribution module can be discharged into the air springs one after the other, starting with the air spring whose pressure has the smallest pressure difference compared to the pressure in the air distribution module or whose pressure is greatest compared to the pressure in the other air springs.

[0091] For example, compressed air from the air dryer and / or the air distribution module can first be directed to the air spring whose pressure has the smallest pressure difference compared to the pressure in the air distribution module, and then to the remaining air spring whose pressure has the smallest pressure difference compared to the pressure in the air distribution module, or whose pressure is the second highest compared to the pressures in the remaining air springs, and finally, compressed air from the air dryer and / or the air distribution module can be directed to the remaining air spring whose pressure has the smallest pressure difference compared to the pressure in the air distribution module.and compressed air from the air dryer and / or the air distribution module is finally discharged into the remaining air spring that has not yet been pressurized with compressed air.

[0092] In this process, a sequence is determined based on the smallest pressure difference in which the air springs are individually pressurized with compressed air. Determining the sequence based on the smallest pressure difference has the advantage that a vehicle is lifted with comparatively low acceleration. This means that the vehicle's handling characteristics are not affected, or at least only minimally affected, by the lifting process. It also prevents the vehicle from being tilted excessively relative to the ground, which can also negatively impact its handling.

[0093] In this process, it can be advantageous if the air springs are successively pressurized with a predetermined quantity of compressed air and / or compressed air from the air dryer and / or the air distribution module, in the same sequence determined by the smallest pressure difference to the pressure in the air distribution module. This pressurization can be carried out in the same order. In particular, the air springs can be individually pressurized with compressed air in the defined sequence until the pressure in the air dryer and / or the air distribution module has been reduced by a specific amount. The amount by which the pressure in the air dryer and / or the air distribution module is to be reduced can, for example, be determined such that, after pressurizing the air springs, the pressure in the air dryer and / or the air distribution module is below a predefined limit.For example, a limit value can be set to indicate the pressure at which damage to the air dryer and / or the air distribution module and / or other components or pneumatic lines of the compressed air supply system is to be expected. The limit value can also be set to indicate the pressure at which the compressed air supply system can be vented without generating a noise level exceeding a specified sound level.

[0094] The procedure can further stipulate that a compressed air quantity is individually specified for the first air spring and / or the intermediate storage tank, for example, for each of the air springs, and that the compressed air supply system is controlled by the control unit so that compressed air is supplied to the respective air springs in the specified quantity. A compressed air quantity can be individually defined for each of the air springs. The compressed air quantity for each air spring can be determined based on the pressure present in the respective air spring. For example, the pressure in each of the air springs can be measured, and a compressed air quantity can be individually specified for each air spring based on the measured pressures. After a certain period of time has elapsed or after a specific action, e.g.,By opening or closing an air spring valve, the compressed air volume for one or more of the air springs can be individually readjusted. This allows the compressed air volume to be set individually for each air spring, depending on the situation, making the process particularly efficient.

[0095] In addition to or as an alternative to individually specifying a compressed air quantity, the method can provide that a time period is individually specified for the first air spring and / or the intermediate storage tank, for example, for each of the air springs, and that the compressed air supply system is controlled by the control unit so that compressed air is discharged into the respective air springs for the specified time period. The individually specified time period can be chosen, in particular, so that each air spring is filled with a specific quantity of compressed air. For example, the individually specified time period for each air spring can be set so that all air springs have a similar pressure after being filled with compressed air. The time period can also be individually specified for the air springs so that the two air springs of the front axle of a vehicle have a different pressure than the two air springs of the rear axle of the vehicle, e.g.,B. higher or lower pressure.

[0096] If, in the process, the air springs are successively supplied with compressed air from the air dryer and / or the air distribution module in at least two groups of at least two air springs, it is particularly preferred that the group of two air springs comprises the two air springs of a front axle or the two air springs of a rear axle of the vehicle.

[0097] In this method, it is further preferred that the pneumatic system is controlled by the control unit in such a way that the compressor stores a portion of the compressed air during venting through the outlet, so that the actual amount of compressed air released to the environment is comparatively lower.

[0098] For example, during compressed air venting, the compressor can store some of the compressed air within its own volume. If the compressor is a piston compressor, for instance, it could store some of the compressed air in the volume of one or more pistons, thus reducing the amount of compressed air actually released into the environment. Specifically, compressed air is then released into the environment at a comparatively smaller pressure difference between the outlet pressure and the ambient pressure. Because the amount of compressed air actually released into the environment is comparatively lower, the noise level generated during venting can also be further reduced.

[0099] Exemplary embodiments of the invention are now described below with reference to the drawings and comparison with the prior art, which is also partially illustrated. These exemplary embodiments are not necessarily to scale; rather, where explanatory, the drawings are presented in a schematic and / or slightly distorted form. For further details regarding the teachings directly apparent from the drawings, reference is made to the relevant prior art. It should be noted that numerous modifications and changes concerning the form and details of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, the drawings, and the claims can be essential for the further development of the invention, both individually and in any combination.Furthermore, the invention encompasses all combinations of at least two of the features disclosed in the description, the drawing, and / or the claims. The general idea of ​​the invention is not limited to the exact shape or detail of the preferred embodiment shown and described below, nor is it limited to an object that would be restricted compared to the object claimed in the claims. For specified dimensioning ranges, values ​​lying within the stated limits are also disclosed as limit values ​​and may be used and claimed as desired. For the sake of simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar functions. Further advantages, features, and details of the invention will become apparent from the following description and with reference to the drawing; this is shown in: . Fig. 1A: Schematic representation of a compressed air supply system pneumatically connected to an air spring system, in which the inlet and outlet are implemented separately; Fig. 1B: Schematic representation of a compressed air supply system pneumatically connected to an air spring system, in which the inlet and outlet are implemented via a common connection; Fig. 1C: Schematic representation of a pneumatic system comprising a compressed air supply system and an air spring system, wherein the air springs of the air spring system are used as a compensation volume; Fig. 1D: Schematic representation of a pneumatic system comprising a compressed air supply system and an air spring system, wherein the return line with auxiliary reservoir and the compressor are used as a compensation volume; Fig. 1E: Schematic representation of a pneumatic system comprising a compressed air supply system and an air spring system, wherein a first air spring and the return line with auxiliary reservoir are used as a compensation volume; Fig.Fig. 2: Schematic flowchart for a method for operating a compressed air supply system; Fig. 3: Diagram showing the quantity of compressed air discharged to the surrounding atmosphere versus the pressure at the outlet for different throttle diameters of the air dryer; Fig. 4: Schematic flowchart for a method for operating a compressed air supply system in which compressed air is discharged into the air springs; Fig. 5A: Schematic diagram of a compressed air supply system pneumatically connected to an air spring system, implemented as an open system; Fig. 5B: Schematic diagram of the [unclear] in [unclear]. Fig. 5A The compressed air supply system shown, in which the diversion of compressed air into the air springs is depicted; Fig. 5C: schematically the in Fig. 5A und Fig. 5B The compressed air supply system shown, in which a venting of the compressed air supply system into the surrounding atmosphere is depicted; Fig. 5D: schematically the in Fig. 5A bis Fig. 5C Fig. 6A: a compressed air supply system shown, in which venting to the surrounding atmosphere is depicted, wherein during venting a portion of the compressed air is stored in the compressor; Fig. 6A: a compressed air supply system represented by circuit symbols, which is pneumatically connected to air springs of an air spring system via air spring valves; Fig. 6B: the in Fig. 6A The compressed air supply system shown, with the reservoir valve open to divert compressed air into the rest of the compressed air supply system; Fig. 6C: the one shown in Fig. 6A and Fig. 6B The compressed air supply system shown, wherein the air spring valve of a first air spring is open to divert compressed air into the first air spring; Fig. 6D: shown in Fig. 6A bis Fig. 6C The compressed air supply system shown, wherein the air spring valve of a second air spring is open to divert compressed air into the second air spring; Fig. 6E: shown in Fig. 6A bis Fig. 6D The illustrated compressed air supply system, wherein the air spring valve of a third air spring is open to divert compressed air into the third air spring; Fig. 6F: shown in Fig. 6A bis Fig. 6E The illustrated compressed air supply system, wherein the air spring valve of a fourth air spring is open to divert compressed air into the fourth air spring; Fig. 6G: the one shown in Fig. 6A bis Fig. 6F Figure 7: a compressed air supply system shown, wherein all air spring valves are closed and a relay valve and a valve for filling the auxiliary reservoir are open; Figure 8: a logic circuit diagram representing a sequence for filling the compressed air reservoir with compressed air from the surrounding atmosphere; Figure 9: a schematic representation of a compressed air supply system pneumatically connected to an air spring system, implemented as a closed system and featuring an auxiliary reservoir; Figure 9A: a schematic representation of a compressed air supply system pneumatically connected to an air spring system, implemented as a closed system, in which the compressor features an auxiliary reservoir; Figure 9B: a schematic representation of the compressed air supply system shown in Figure 9B. Fig. 9A The compressed air supply system shown, in which the diversion of compressed air from the surrounding atmosphere into the compressed air reservoir is depicted; Fig. 9C: schematically the in Fig. 9A and Fig. 9B The compressed air supply system shown, in which the diversion of compressed air into the auxiliary storage tank is indicated; Fig. 9D: schematically the in Fig. 9A bis Fig. 9C The depicted compressed air supply system shows a venting point for the air dryer.

[0100] Fig. 1A The figure schematically shows a compressed air supply system 102 pneumatically connected to an air spring system 121, in which a compressor connection 1 and an outlet 3 are implemented separately from each other.

[0101] The compressed air supply 102 and the air suspension system 121 are components of a vehicle 101 and can be used, for example, to raise or lower the vehicle 101 relative to the ground. The compressed air supply system 102 and the air suspension system 121 together form a pneumatic system 103.

[0102] The compressed air supply system 102 comprises a compressor connection 1 and a compressed air supply connection 2. A pneumatic main line 131 with an air dryer 110 extends between compressor connection 1 and compressed air supply connection 2. The compressed air supply system 102 further comprises a compressor 106 pneumatically connected to compressor connection 1, which serves to draw in and compress air 51 from the surrounding atmosphere 50 and to convey the compressed air 52 via compressor connection 1 to the air dryer 110. In this embodiment, the compressor 106 is designed as a compressor. The air dryer 110 is configured to dry the air 51 drawn in from the surrounding atmosphere 50 and to convey it via compressed air supply connection 2 to an air distribution module 108. The air dryer 110 is also pneumatically connected to an outlet 3, through which the compressed air supply system 102 can be vented.

[0103] The air distribution module 108 is part of the air spring system 121. The air distribution module 108 includes a pressure sensor 116 for detecting the pressure level in the air distribution module 108. The air distribution module 108 serves to forward compressed air 54 to the gallery 129.

[0104] The compressed air supply system 102 also includes a control unit 100 for controlling the compressed air supply system 102. The control unit 100 is connected to the pressure sensor 116 of the air distribution module 108 via a data connection 55. A pressure sensor signal, representing the level of a detected pressure, can be transmitted from the pressure sensor 116 to the control unit 100 via the data connection 55. The control unit 100 is also connected to the compressor 106 via a control line 56 to control the compressor 106. For example, the control unit 100 can control the compressor 106 based on the pressure level detected by the pressure sensor 116, which was transmitted from the pressure sensor 116 to the control unit 100 via the data connection 55 using a pressure sensor signal.

[0105] The air suspension system 121 comprises four air springs 118, 120, 122, 124, which can be filled with compressed air 54 via the gallery 129 to raise the vehicle 101 relative to the ground. When compressed air 54 is discharged from the air springs 118, 120, 122, 124 into the compressed air supply system 102, the vehicle 101 is lowered relative to the ground. The four air springs 118, 120, 122, 124 can be used as a compensation volume 113 to reduce overpressure in the air dryer 110. Thus, compressed air 52 from the air dryer 110, which represents an overpressure volume 109, can be discharged into the compensation volume 113 to reduce the pressure in the overpressure volume 109. It is preferred if the air springs 118, 120, 122, 124 are filled with compressed air from the overpressure volume 109 one after the other or in groups of two air springs 118, 120, 122, 124.It is particularly preferred if the air springs 118, 120, 122, 124 are each pressurized with a comparatively small quantity of compressed air in a single filling step. It can be advantageous if each of the air springs 118, 120, 122, 124 is pressurized with a comparatively small quantity of compressed air in several filling steps. The air springs 118, 120, 122, 124 can thus be pressurized with compressed air several times in a specific sequence, either individually or in groups of two. This prevents the vehicle from being lifted abruptly. Should the pressure reduction in the overpressure volume 109 be insufficient, compressed air from the overpressure volume 109 can be additionally discharged into an intermediate storage tank 107. In this case, the intermediate storage tank 107 is formed by the compressor. However, other components of the compressed air supply system 102 can also be used as intermediate storage 107.The intermediate storage unit 107 then forms the compensation volume 113 together with the air springs 118, 120, 122, 124.

[0106] It is possible that during the operation of the compressed air supply system 102, the air springs 118, 120, 122, and 124 are first pressurized with compressed air, and then, in a final step immediately before the compressed air supply system 102 is vented, the intermediate storage tank 107 is filled with compressed air from the overpressure volume 109. This allows a pressure level to be reached in the overpressure volume 107, and especially at the outlet of the compressed air supply system 102, that is below the pressure level of the air springs 118, 120, 122, and 124. Venting of the compressed air supply system 102 to the environment can then take place at an even further reduced pressure at the outlet. This venting of the compressed air supply system 102 then results in a comparatively even lower noise level.

[0107] The air springs 118, 120, 122, 124 are pneumatically connected to the air distribution module 108 via the air spring valves 126, 128, 130, 132 and via the gallery 129. With the air spring valves 126, 128, 130, 132 open, the air springs 118, 120, 122, 124 can be filled or emptied with compressed air 54 accordingly.

[0108] Fig. 1B Figure 1 schematically shows a compressed air supply system 102' pneumatically connected to an air spring system 121', in which no separate pneumatic line is provided for the outlet 3'. The compressed air supply system 102' and the air spring system 121' together form a pneumatic system 103'.

[0109] The in relation to Fig. 1A The compressed air supply system 102 described differs in particular from the compressed air supply system 102' in that no separate pneumatic line is provided for outlet 3' in the compressed air supply system 102.

[0110] Accordingly, the air dryer 110' of the compressed air supply system 102' is pneumatically connected to the compressor 106' and the air distribution module 108'. The compressor 106' is in turn pneumatically connected to the compressor port 1' and the outlet 3' via a pneumatic line. Air 51' drawn in from the surrounding atmosphere 50' by the compressor 106' is directed via a compressor port 1' to the air dryer 110' and dried by it. The compressed air is then conveyed by the air dryer 110' as dry compressed air 52' ​​via the compressed air supply port 2' to the air distribution module 108' of the air spring system 121'.

[0111] The air suspension system 121' comprises the air springs 118', 120', 122', 124', which can be pressurized with compressed air 52' ​​by opening the respective air spring valves 126', 128', 130', 132' in order to raise the vehicle 101'. The air springs 118', 120', 122', 124' can be used as a compensating volume 113' to reduce the pressure in the air dryer 110', which represents an overpressure volume 109'. If the pressure in the air dryer 110' needs to be reduced even further, an intermediate reservoir 107' of the compressed air supply system 102' can also be used as a compensating volume 113' in addition to the air springs 118', 120', 122', 124'. The compressor 106' of the compressed air supply system 102' can be used as an intermediate storage unit 107', for example.

[0112] The compressed air supply system 102' comprises a control unit 100', which is connected via a data link 55' to a pressure sensor 116' of the air distribution module 108'. The pressure sensor 116' is configured to measure the pressure level in the air distribution module 108' and to transmit a pressure sensor signal, representing the measured pressure level in the air distribution module 108', to the control unit 100' via the data link 55'. The control unit 100' is connected to the compressor 106' via a control line 56' for the purpose of controlling the compressor 110'. The control of the compressor 106' by the control unit 100' can be carried out based on the pressure level in the air distribution module 108' measured by the pressure sensor 116'.

[0113] Fig. 1C , Fig. 1D and Fig. 1E Figure 1 schematically shows a pneumatic system 150 in different operating situations. The pneumatic system 150 comprises a compressed air supply system 152 and an air spring system 154. The compressed air supply system 152 and the air spring system 154 are controlled by a control unit 155.

[0114] The compressed air supply system 152 has an inlet and an outlet, which are implemented by a common compressed air valve 156. Air 162 is drawn in from the environment 160 by a compressor 158, compressed, and then conveyed as compressed air 164 to an air dryer 166. The air dryer 166 dries the compressed air. The air dryer 166 is located in a pneumatic main line 168, which extends between a compressor connection 170 and a compressed air supply connection 172. The air dryer 166 is connected to the compressor 158 via the compressor connection 170. The air dryer 166 is connected to the air spring system 154 via the compressed air supply connection 172. Compressed air 174, dried by the air dryer 166, is conveyed to the air spring system 154 via the compressed air supply connection 172.

[0115] Compressed air 174, which is routed to the air spring system 154, is forwarded via an air distribution module 176 to a gallery 178. A pressure sensor 180 is arranged in the air distribution module 176, which measures the pressure in the air distribution module 176.

[0116] The compressed air 174 is distributed via gallery 178 to the air springs 182, 184, 186, 188 of the air spring system 154. For this purpose, the air spring valves 190, 192, 194, 196 of the air springs 182, 184, 186, 188 are opened.

[0117] To fill the air springs 182, 184, 186, 188 with compressed air 174, the compressed air valve 156 is closed and the compressor 158 is set to idle.

[0118] To vent the air springs 182, 184, 186, 188, the corresponding air spring valves 190, 192, 194, 196 and a check valve 198 are opened. Compressed air 174 then flows back to the compressor 158 via a return line 200. The return line 200 is a pneumatic line provided in addition to the main pneumatic line 168. An auxiliary accumulator 202 is pneumatically connected to the return line 200, in which compressed air 174 can be stored for pressure reduction in the rest of the compressed air supply system 152.

[0119] To vent the compressed air supply system 152, the compressed air valve 156 is opened so that compressed air 174 can be discharged into the environment 160.

[0120] In Fig. 1C Figure 1 shows an operating situation in which air dryer 164 and air distribution module 180 form an overpressure volume 204. Pressures of up to 18 bar can occur in this overpressure volume 204 during operation of the pneumatic system 150. To reduce the overpressure in the overpressure volume 204 without having to vent to the surroundings 160, the overpressure is to be discharged into a compensation volume 206. In the operating situation of the Fig. 1C The compensating volume 206 is formed by the air springs 182, 184, 186, 188. To reduce the pressure in the overpressure volume 204, compressed air 174 is distributed sequentially, either individually or in groups of two, to the air springs 182, 184, 186, 188. It is preferred that the compressed air 174 is first discharged into the air spring 182, 184, 186, 188 that has the smallest pressure difference compared to the pressure 174 in the air distribution module 176.

[0121] Compressed air 174 can advantageously be additionally discharged into an intermediate storage tank 208. This is particularly advantageous if the pressure reduction in the air springs 182, 184, 186, 188 cannot be carried out sufficiently or quickly enough. The intermediate storage tank 208 comprises a connection volume. This connection volume can be formed by the return line 200 alone or by the return line 200 and an optionally advantageous additional storage tank 202. The additional storage tank 202 can be present and pneumatically connected to the return line 200 in a switchable manner; for example, via a pneumatic switching valve (not explicitly shown here), a check valve, or another suitable pneumatic actuator. The additional storage tank 202 can also be provided as a free pneumatically accessible component and, for example, pneumatically connected to the return line 200 via a suitable throttle.The intermediate storage tank 208 can be formed not only by the connection volume but also by the volume of the compressor 158, i.e., in addition to the return line 200 and the optional auxiliary storage tank 202; thus, it can comprise the return line 200, the optional auxiliary storage tank 202, and the compressor 158. In principle, the connection volume can therefore be understood as the pneumatic connection (possibly with an additional available volume) between the check valve 198 and the compressor 158; in particular, the connection volume comprises the return line 200 and the optional auxiliary storage tank 202. The intermediate storage tank 208 can be formed by the connection volume alone, by the volume or part of the volume of the compressor 158, or by a combination thereof.These variants of the intermediate storage 208, in particular of the connection volume, can be provided for the further development of the concept of the invention independently of the embodiment described here by way of example, and in particular also in the other embodiments described in this application.

[0122] The compensation volume 206 can also be used, as in Fig. 1D As shown, only the intermediate storage volume 208 and not the air springs 182, 184, 186, 188 are included. Alternatively, the compensation volume 206 may not include all of the air springs 182, 184, 186, 188, for example, only one or two of the air springs 182, 184, 186, 188. For example, as shown Fig. 1E An operating situation in which the compensating volume 206 is formed by an intermediate storage tank 208 and only one air spring 182, wherein the intermediate storage tank 208 comprises only a connecting volume formed by the return line 200 and the additional storage tank 202. These variants of the compensating volume 206 can be provided for further development of the concept of the invention independently of the embodiment described here by way of example, and in particular also in the other embodiments described in this application.

[0123] Fig. 2 Figure 1 schematically shows a flowchart for a known method for operating a compressed air supply system. This method allows, in particular, the pressure at the outlet of the compressed air supply system to be reduced, enabling venting of the system at a comparatively lower pressure. Because venting occurs at a lower pressure, the noise level generated during venting is also comparatively lower.

[0124] In this process, a compressor in the compressed air supply system is first brought to idle (step S1), and the outlet valve of one of the compressed air supply system's outlets is closed (step S2). With the compressor idling and the outlet valve closed, the air spring valves are opened (step S3). Opening the air spring valves allows compressed air to flow from the compressed air supply system into the air springs of a pneumatic air spring system connected to the compressed air supply system. An equilibrium pressure is then established in the compressed air supply system, which is comparatively lower than the pressure that existed in the compressed air supply system before the air spring valves were opened (step S4). Once an equilibrium pressure has been established in both the compressed air supply system and the air spring system, the air spring valves are closed again (step S5).In this process, all the air spring valves are opened and closed simultaneously. This raises the vehicle in one step by pressurizing the air springs with compressed air, which can negatively affect the vehicle's handling characteristics.

[0125] After the air spring valves have been closed again, the outlet valve is opened (step S6) to vent the compressed air supply system at a comparatively lower pressure at the outlet.

[0126] Fig. 3 Diagram 300 shows the quantity of compressed air 302 released to the surrounding atmosphere as a function of the pressure at the outlet 304 for different throttle diameters of an air dryer.

[0127] In Diagram 300 shows three curves 306, 308, 310, which relate the increase in the compressed air quantity 302 to the pressure 304 at the outlet for different throttle diameters of an air dryer.

[0128] All three curves 306, 308, 310 show a linear relationship between the amount of compressed air delivered 302 as a function of the pressure at the outlet 304.

[0129] Curve 306 represents the linear relationship between the amount of compressed air delivered 302 as a function of the pressure at the outlet 304 for a throttle diameter of 3.6 mm.

[0130] Curve 308 represents the linear relationship between the amount of compressed air delivered 302 as a function of the pressure at the outlet 304 for a throttle diameter of 2.0 mm.

[0131] Curve 310 represents the linear relationship between the amount of compressed air delivered 302 as a function of the pressure at the outlet 304 for a throttle diameter of 1.5 mm.

[0132] In The diagram also symbolically represents the increase in noise level at the outlet by an arrow 312. Arrow 312 indicates that, correspondingly, with an increasing volume of compressed air 302 discharged at a correspondingly high pressure at the outlet 304, the noise level at the outlet also increases when venting a compressed air supply system, and in particular the air dryer and / or the air distribution module of the compressed air supply system.

[0133] The depicted pressure range of 4 bar to 20 bar can be divided into two partial pressure ranges, with the first partial pressure range 314 representing the range from 4 bar to 12 bar and the second partial pressure range 316 representing the range from 12 bar to 20 bar. Particularly in the partial pressure range between 12 bar and 20 bar, venting the compressed air supply system results in a comparatively high noise level. It is therefore preferable not to vent the compressed air supply system if the pressure at the outlet is within this second partial pressure range 316.Should the pressure at the outlet be within the second partial pressure range 316, and it is nevertheless necessary to vent the air dryer and / or the air distribution module to reduce the pressure there, it is therefore preferred to divert compressed air from the air dryer and / or the air distribution module into the air springs of an air spring system in order to reduce the pressure in the air dryer and / or the air distribution module to such an extent that the pressure at the outlet is within the first partial pressure range 314. As soon as the pressure at the outlet is within the first partial pressure range 314, the compressed air supply system can be vented without generating a noise level that exceeds a critical, e.g., predefined, limit value.

[0134] Fig. 4 The diagram schematically shows a flowchart for a method of operating a compressed air supply system in which compressed air is discharged sequentially, either individually into air springs or sequentially in groups of two air springs.

[0135] In the procedure, the compressor of the compressed air supply system is first brought to idle (step T1) and the outlet valve of the compressed air supply system is closed (step T2).

[0136] By means of a control unit, e.g. the control unit of the compressed air supply system, a quantity of compressed air and / or a duration of time is specified or defined (step T3) with which or for which the air springs of an air spring system are to be supplied with compressed air from the air dryer and / or the air distribution module of the compressed air supply system.

[0137] In a first alternative of the procedure, the air springs of the air spring system are successively supplied with compressed air from the air dryer and / or the air distribution module.

[0138] Accordingly, the air spring valve of a first air spring is opened, and the first air spring is pressurized with a specified quantity of compressed air and / or for a predefined duration (step T4). After filling with compressed air, the air spring valve of the first air spring is closed, and the air spring valve of a second air spring is opened (step T5) to fill this second air spring with compressed air. A specific quantity of compressed air and / or duration can also be individually specified or predefined for the second air spring. With the air spring valve of the second air spring closed, a third air spring in the air spring system is pressurized with compressed air by opening the air spring valve of this third air spring (step T6). A specific quantity of compressed air or a predefined duration can also be specified for the third air spring.The air spring valve of the third air spring is then closed again and the air spring valve of the fourth air spring of the vehicle is opened to fill it with compressed air (step T7), e.g. with a predetermined amount of compressed air and / or for a predefined period of time.

[0139] Should the amount of compressed air discharged from the air dryer and / or air distribution module into the air springs be insufficient to reduce the pressure in the air dryer and / or air distribution module by the desired amount, the air springs can be refilled with a predetermined amount of compressed air and / or for a predefined period of time until the pressure at the outlet of the compressed air supply system reaches a specific value (step T8). This allows the pressure at the outlet to be successively reduced in numerous steps until it falls below a certain, e.g., predetermined, limit value. This limit value is specifically designed to ensure that only a low noise level is generated when venting the compressed air supply system.

[0140] After the air springs have been filled with compressed air and all air spring valves are closed, the compressor of the compressed air supply system can be reactivated (step T9) and the outlet valve opened (step T10). The compressed air supply system is then vented. During this process, some of the compressed air that would otherwise be released into the surrounding atmosphere is stored in the activated compressor, further reducing the amount of compressed air actually released into the atmosphere.

[0141] Additionally, the process can include repeatedly opening and closing the compressed air supply system's outlet valve during venting, for example at a predetermined frequency, so that the compressed air is released into the surrounding atmosphere in several stages. This can further reduce the noise level generated during venting.

[0142] In a second alternative of the procedure, the air springs of the air spring system are filled with compressed air in groups of two. Accordingly, the air spring valves of two air springs are opened simultaneously (step T11), while the two air spring valves of the two remaining air springs are closed. Subsequently, the two remaining air springs are pressurized with compressed air, while the two air spring valves of the already filled air springs remain closed (step T12).

[0143] It is preferred that a group of two air springs comprises the two air springs of a front axle or a rear axle of a vehicle. According to this second alternative of the method, for example, the two air springs of the front axle of the vehicle can first be pressurized with compressed air and subsequently the two air springs of the rear axle, or vice versa.

[0144] Even if the air springs are supplied with compressed air in groups of two, it is preferred if the air springs are supplied with a predetermined amount of compressed air and / or for a predefined period of time.

[0145] After the air springs have been filled with compressed air once in groups of two, they can be filled again, e.g., with a specified amount of compressed air and / or for a predefined duration (step T13). The air springs can be repeatedly pressurized with compressed air until the pressure at the outlet falls below a certain, particularly critical, limit.

[0146] Once the pressure at the outlet has fallen below the limit value, the compressed air supply system can be vented as described above by performing steps T9 and T10.

[0147] Alternatively or additionally to sequentially filling the air springs individually or in groups of two, the method can include the discharge of compressed air into the compressor and / or a connecting volume. If compressed air is additionally discharged into the compressor and / or the connecting volume, the pressure in the air dryer can be reduced even further, and the compressed air supply system can be vented with an even lower noise level.

[0148] Fig. 5A Figure 1 schematically shows a compressed air supply system 502 pneumatically connected to an air spring system 521, which is implemented as an open system.

[0149] The compressed air supply system 502 comprises an inlet 511 and an outlet, which are connected via a common port. The compressed air supply system 502 also includes an air dryer 510 and a compressor 506. When the compressor 506 draws in air from the surrounding atmosphere 550, this air flows through the inlet 511 and through the air dryer 510. The air dried by the air dryer 510 is compressed by the compressor 506 and conveyed as compressed air via a pneumatic main line 507 to the air distribution module 508 of the air spring system 521.

[0150] The air distribution module 508 includes a pressure sensor 516, which detects the pressure level within the air distribution module 508. The pressure sensor 516 is connected to the control unit 500 of the compressed air supply system 502 via a data connection 551. A pressure sensor signal can be transmitted from the pressure sensor 516 to the control unit 500 via the data connection 551. This pressure sensor signal specifically represents the pressure level detected by the pressure sensor 516. The control unit 500 is also connected to the compressor 506 via control lines 555, enabling the control unit 500 to control the compressor 506 using transmitted control commands. Specifically, the control unit 500 can control the compressor 506 based on the pressure level detected by the pressure sensor 516 within the air distribution module 508.

[0151] The air distribution module 508 comprises five 2 / 2-way solenoid valves. One of these 2 / 2-way solenoid valves is connected to a compressed air reservoir 515 of the compressed air supply system 502. Compressed air can be temporarily stored in the compressed air reservoir 515 and used as needed, e.g., for filling air springs.

[0152] The remaining four 2 / 2-way solenoid valves are assigned as air spring valves to the four air springs 518, 520, 522, 524 of the air spring system 521.

[0153] By means of the air distribution module 508, compressed air can be discharged from the compressor 506 via the pneumatic main line 507 into the air springs 518, 520, 522, 524 by opening the air spring valves.

[0154] Two of the air springs 518, 522 are located on the front axle 534 of the vehicle 503 and the other two air springs 522, 524 are located on the rear axle 536 of the vehicle 503.

[0155] Fig. 5B schematically shows the in relation to Fig. 5A The compressed air supply system 502 described. Additionally, in Fig. 5B Arrows indicate the diversion of compressed air 552 into the air springs 518, 520, 522, 524.

[0156] As in the one relating to Fig. 4 In the described procedure, the compressed air is not distributed to the air springs 518, 520, 522, 524 simultaneously. Instead, the compressed air 552 is distributed individually to the air springs 518, 520, 522, 524 sequentially. In particular, each of the air springs 518, 520, 522, 524 is supplied with a predetermined quantity of compressed air and / or for a predefined duration, sequentially.

[0157] According to the one shown here Fig. 5B First, the air spring 518, located on the right side of the front axle 534 in the direction of travel of the vehicle 503, is pressurized with compressed air. Then, the air spring 522, located on the left side of the front axle 534 in the direction of travel of the vehicle 503, is pressurized with compressed air 552. Alternatively, both air springs of the front axle 518 and 522 could also be pressurized with compressed air 552 simultaneously, i.e., as a group of two air springs.

[0158] After the air springs 518, 522 of the front axle 534 have been pressurized with compressed air 552, the air springs 520, 524 of the rear axle 536 are pressurized with compressed air 552. For example, as in the Fig. 5B As shown, first the air spring 524, located on the left side of the rear axle 536 in the direction of travel of the vehicle 503, is pressurized with compressed air 552. Then the air spring 520, located on the right side of the rear axle 536 in the direction of travel of the vehicle 503, is pressurized with compressed air 552.

[0159] Alternatively, the two air springs 520, 524 of the rear axle 536 can also be simultaneously pressurized as a group of two air springs 520, 524 with compressed air 552.

[0160] If the air springs 518, 520, 522, 524 are pressurized with compressed air 552 in groups of two air springs 518, 520, 522, 524, this is done sequentially. For example, first the two air springs of the front axle 518, 522 could be pressurized with compressed air 552 and then the two air springs 522, 524 of the rear axle 536, or vice versa. Even when the air springs 518, 520, 522, 524 are supplied with compressed air 552 in groups of two air springs 518, 520, 522, 524, a quantity of compressed air is preferably specified and / or a duration of time is defined with which or for which the air springs 518, 520, 522, 524 are supplied with compressed air.

[0161] Fig. 5C schematically shows the with reference to Fig. 5A und Fig. 5B described compressed air supply system 502 with the difference that in the Fig. 5C Arrows indicate the venting of the compressed air supply system 502 into the surrounding atmosphere 550.

[0162] To vent the compressed air supply system 502, the air spring valves are closed. Then, the outlet valve of outlet 512 is opened to vent the compressed air supply system 502.

[0163] The compressor 506 can be activated to store some of the compressed air, so that effectively less compressed air 552 is released into the surrounding atmosphere 550.

[0164] A corresponding operational situation exists in Fig. 5D shown. Fig. 5D schematically shows the in relation to the Fig. 5A bis Fig. 5C described compressed air supply system 500.

[0165] During the venting of the compressed air supply system 500, the compressor 506 is activated to store some of the compressed air 552. In The surrounding atmosphere 550 will then release a correspondingly smaller amount of compressed air 552', so that the noise level generated when venting the compressed air supply system 500 can be further reduced.

[0166] Optionally, the outlet valve of outlet 512 can be opened and closed several times in succession, so that the compressed air 552 is released into the surrounding atmosphere 550 in comparatively smaller quantities each time.

[0167] Fig. 6A Figure 1 shows a schematic representation of a compressed air supply system 600, which is pneumatically connected via air spring valves 602, 604, 606, 608 to air springs 610, 612, 614, 616 of an air spring system 618. The air spring valves 602, 604, 606, 608 are designed as 2 / 2-way solenoid valves and are part of an air distribution module 620.

[0168] The air distribution module 620 also includes a pressure sensor 622 for detecting the level of pressure in the air distribution module 620 and a gallery 627 for distributing the compressed air to the air spring valves 610, 612, 614, 616.

[0169] The air distribution module 620 includes another 2 / 2-way solenoid valve, which is a reservoir valve 624. A compressed air reservoir 626 is connected to the reservoir valve 624 and can be filled with compressed air via this reservoir. Compressed air can also be drawn from the compressed air reservoir 626 and, for example, supplied to the air springs 610, 612, 614, and 616. By filling the air springs 610, 612, 614, and 616 with compressed air, the vehicle can be raised relative to the ground.

[0170] The compressed air supply system 600 further comprises a compressor 628, which includes an electric motor 630 that can, for example, drive pistons to compress intake air. During operation, compressed air is then discharged from the compressor 628 via an air dryer 632 and a pneumatic main line 633 to the air distribution module 620. Thus, the compressed air dried by the air dryer 632 is distributed via the air distribution module 620 to the air springs 610, 612, 614, 616, and the compressed air reservoir 626. The compressor 628 draws air from the surrounding atmosphere through an inlet 636 equipped with a filter. The filter prevents the compressor 628 from becoming contaminated by particles.

[0171] The compressed air supply system 600 further comprises a relay valve 634 pneumatically connected to the compressor 618 and the air dryer 632. The relay valve 634 is in turn pneumatically connected to an outlet 638, which is equipped with silencers. The silencers prevent the noise level from exceeding a predetermined limit when venting the compressed air supply system 600.

[0172] The compressed air supply system 600 also includes an additional storage tank 639, which can be pressurized with compressed air via a valve 640 to further reduce the pressure in the air dryer 632. A check valve 641 is also provided. The compressed air supply system 600 also features throttles 642 and 643.

[0173] Fig. 6B bis Fig. 6G show the in relation to Fig. 6A The described compressed air supply system 600 is shown in different operating situations.

[0174] In Fig. 6B is the in relation to Fig. 6A The compressed air supply system 600 is shown, with the reservoir valve 624 of the compressed air reservoir 626 open to divert compressed air into the rest of the compressed air supply system 600. Opening the reservoir valve 624 can cause the pressure in the rest of the compressed air supply system 600 to increase. It is then desirable to reduce the pressure in the rest of the compressed air supply system 600 again, e.g., by venting the compressed air supply system 600 through the outlet 638. However, if the pressure in the compressed air supply system 600 is comparatively high, e.g., between 12 bar and 20 bar, it is preferred that the pressure at the outlet 638 be reduced before venting to prevent a comparatively high noise level during venting.

[0175] One way to reduce the pressure at outlet 638 is to successively fill the air springs 610, 612, 614, 616 of the air spring system 618 with compressed air from the air dryer 632 and / or the air distribution module 620.

[0176] The sequential filling of the air springs 610, 612, 614, 616 of the air spring system 618 is described in the Fig. 6C bis Fig. 6F shown.

[0177] In Fig. 6C is the one in relation to the Fig. 6A and Fig. 6B The described compressed air supply system 600 is shown, wherein the air spring valve 604 of a first air spring 612 is open to divert compressed air into the first air spring 612. The first air spring 612 is located in a vehicle on the right-hand side of the front axle in the direction of travel.

[0178] Fig. 6D shows the in relation to the Fig. 6A bis Fig. 6C The described compressed air supply system 600 is shown in an operating situation in which the air spring valve 602 of a second air spring 610 is open to divert compressed air into the second air spring 610. The second air spring 610 is located on the left side of the front axle of a vehicle in the direction of travel.

[0179] Fig. 6E shows the in relation to the Fig. 6A bis Fig. 6D The described compressed air supply system 600 is shown in another operating situation in which the air spring valve 608 of a third air spring 616 is open to divert compressed air into the third air spring 616. The third air spring 616 is located in a vehicle on the right-hand side of the rear axle in the direction of travel.

[0180] In Fig. 6F is the one in relation to the Fig. 6A bis Fig. 6E The described compressed air supply system 600 is shown in a further operating situation in which the air spring valve 606 of a fourth air spring 614 is open to divert compressed air into the fourth air spring 614. The fourth air spring 614 is located on the left side of the rear axle in a vehicle in the direction of travel.

[0181] As from the Fig. 6C bis Fig. 6F As can be seen, in any given operating situation only one of the air spring valves 602, 604, 606, 608 is open at any given time, while the remaining air spring valves 602, 604, 606, 608 are closed. The air springs 610, 612, 614, 616 are therefore sequentially supplied with compressed air from the air dryer 632 and / or the air distribution module 620.

[0182] Each of the air springs 610, 612, 614, 616 is filled with a predetermined amount of compressed air and / or for a predefined period of time.

[0183] The excess compressed air from the air dryer 632 and / or the air distribution module 620 is thus distributed in portions to the air springs 610, 612, 614, and 616. The air springs 610, 612, 614, and 616 are supplied with compressed air sequentially until the excess compressed air from the air dryer 632 and / or the air distribution module 620 has been distributed to the air springs. The amount of excess compressed air is determined by the amount by which the pressure in the air dryer 632 and / or the air distribution module 620 must be reduced so that the pressure at the outlet 638 does not result in a noise level exceeding a predetermined limit when the compressed air supply system 600 is vented into the surrounding atmosphere.

[0184] Fig. 6G shows the in relation to the Fig. 6A bis Fig. 6F The described compressed air supply system 600 operates in a situation where all air spring valves 602, 604, 606, and 608 are closed, and the relay valve 634 and the valve 640 for filling the auxiliary reservoir 639 are open. Since the excess compressed air was distributed to the air springs 610, 612, 614, 616, and the auxiliary reservoir 639 before venting, a comparatively low pressure is present at the outlet 638, so that venting the compressed air supply system 600 does not result in a noise level exceeding a predetermined limit.

[0185] Fig. 7 The diagram shows a logic circuit illustrating the sequence of steps for filling a compressed air reservoir using a compressor. Filling the reservoir involves transferring compressed air from an air dryer, partially into the air springs of an air spring system. First, the inlet valve is opened for 0.3 to 0.5 seconds (step L1), allowing air from the surrounding atmosphere to enter the compressed air supply system. The inlet valve then remains open for another 0.2 to 0.5 seconds (step L2). During this time, the compressor is activated (step L3) to draw in air from the surrounding atmosphere. Steps L2 and L3 begin simultaneously. However, the compressor remains activated even after the inlet valve closes.

[0186] After the inlet valve is closed for a duration of 0.5 to 7 seconds, a booster valve is activated (step L4) to increase the air volume in the compressed air supply system. While the booster valve is activated, the compressor also remains activated. Furthermore, the compressor remains activated for approximately 0 to 0.5 seconds after the booster valve closes. The compressor then idles. When the compressor is idling, after a duration of 0 to 0.5 seconds, the air spring valve of the air spring located on the left side of the front axle (in the direction of travel) opens (step L5). This air spring valve remains open for a duration of 0.1 to 3 seconds. The duration for which the air spring is pressurized with compressed air can be a predefined time.After the air spring valve of this air spring has closed, the air spring valve of the air spring located on the right side of the front axle (in the direction of travel) is subsequently opened (step L6). The air spring located on the right side of the front axle is pressurized with compressed air for a period of 0.1 seconds to 3 seconds.

[0187] The duration for which each of the two air springs of the front axle is pressurized with compressed air can vary.

[0188] According to the logic diagram shown here, only the air springs of the vehicle's front axle are pressurized with compressed air. Alternatively or additionally, the two air springs of the rear axle could also be pressurized with compressed air. Alternatively again, the air springs of the front axle and / or the air springs of the rear axle could be pressurized with compressed air simultaneously, i.e., in groups of two.

[0189] After the air spring valve of the air spring located on the right side of the front axle has been closed again, the outlet valve of the compressed air supply system is opened after a period of 0 seconds to 0.5 seconds (step L7).

[0190] By diverting compressed air into the two air springs of the vehicle's front axle, the pressure at the outlet valve can be reduced accordingly. Bleeding the compressed air system is then possible at a comparatively lower pressure, resulting in a correspondingly lower noise level during bleeding.

[0191] Fig. 8 schematically shows a pneumatically connected compressed air supply system 802 with an air spring system 821, which is implemented as a closed system and has an additional storage tank 838.

[0192] The compressed air supply system is part of a vehicle 803.

[0193] The compressed air supply system 802 comprises an inlet 811 and an outlet 812 with a filter 813 for filtering the intake air 850. For intake of air 850, the compressed air supply system 802 includes a compressor 806. The air 850 is compressed by the compressor 806 and, as compressed air 851, is forwarded to the air dryer 810 of the compressed air supply system 802.

[0194] The dry compressed air 852 from the air dryer 810 is conveyed to the air distribution module 808 via a pneumatic main line 840. A check valve 862 is provided in the pneumatic main line 840. The pneumatic main line 840 is also pneumatically connected to a relay valve 807 via a check valve 864 and throttles 860 and 866. The air distribution module 808 comprises four air spring valves 826, 828, 830, and 832. The air distribution module 808 also includes a pressure sensor 816 for measuring the pressure level within the air distribution module 808. The air distribution module 808 is connected to the air springs 818, 820, 822, and 824, respectively, via the air spring valves 826, 828, 830, and 832. By opening the air spring valves 826, 828, 830, 832, the air springs 818, 820, 822, 824 of the air spring system 821 can be supplied with compressed air from the compressed air supply system 802, e.g. to raise the vehicle 803 relative to the ground.

[0195] To divert compressed air 852 into the air distribution module 808, an upstream separation valve 817, designed as a 2 / 2-way solenoid valve, is opened.

[0196] Additionally or alternatively, the compressed air 852 could also be discharged into a compressed air reservoir 815 of the compressed air supply system 802 by opening a reservoir valve 819.

[0197] Compressed air 852, which is to be conveyed from the air distribution module 808 back towards the outlet 812, flows through a check valve 823, which is also designed as a 2 / 2-way solenoid valve. The compressed air 852 flowing through the check valve 823 can be discharged into the compressed air reservoir 815 via a booster valve 825. The compressed air 852 flowing through the check valve 823 enters a connecting volume 842, which has a pneumatic return line 844 that connects the air distribution module 808, and in particular its reservoir, to the compressor 806 via the check valve 823. The connection volume 842 further includes a compressor line 846, which pneumatically connects a first compression stage 848 of the compressor 808 with a second compression stage 853 of the compressor 808.The connecting volume 840, during operation, has the pressure of the first compressor stage 848, which is lower than the pressure in the rest of the compressed air supply system 802, namely the pressure of the second compressor stage 850. The pressure in the air dryer 810 can therefore be effectively reduced by discharged compressed air at the pressure of the second compressor stage 853 into the connecting volume 840. The connecting volume 840 can be used to reduce the pressure in the air dryer, either additionally or alternatively, to discharge compressed air into the air springs and / or into the compressor itself, e.g., into a piston volume of the compressor.

[0198] The connection volume 842 additionally features an auxiliary reservoir 838 into which compressed air can be discharged. By discharging the compressed air 852 into the auxiliary reservoir 838, the pressure at the outlet 812 can be further reduced. For venting the compressed air supply system 802, it also includes an outlet valve 809 and a relay valve 807, both designed as 2 / 2-way solenoid valves. Venting of the compressed air supply system 802 can then take place at a comparatively lower pressure.

[0199] Fig. 9 Figure 1 schematically shows a pneumatically connected compressed air supply system 902 to an air spring system 900, which is implemented as a closed system and has a connection volume 941 comprising a return line 942, an auxiliary reservoir 904 and a compressor line 944 between a first compressor stage 948 and a second compressor stage 955 of a two-stage compressor 906. The return line 942 extends from a check valve 938 to the compressor 906.

[0200] The compressed air supply system 902 comprises an inlet 911 and an outlet 912. Furthermore, the compressed air supply system 902 includes a compressor 906 with a brushless DC motor 907, an auxiliary storage tank 904, and an air dryer 910. The air dryer 910 is connected to an air distribution module 929 via a pneumatic main line 954 and a separation valve 984, using a throttle 914 with a diameter of 1.2 mm. The pneumatic main line 954 also includes a throttle 886. A check valve 988 and another throttle 990 are also integrated into the pneumatic main line 954. The compressed air supply system 902 includes an outlet valve 915, which is designed as a 2 / 2-way solenoid valve. The compressed air supply system 902 also includes a reservoir valve 934, through which a compressed air reservoir 917 can be filled with compressed air. The compressed air reservoir 917 can also be filled with compressed air via a boost valve 936.The compressed air supply system 902 also includes a separation valve 940, through which dry compressed air can be discharged into an air distribution module 929 of the compressed air supply system 902. To empty the air distribution module 902, the outlet valve 915 of the compressed air supply system 902 is opened.

[0201] The air distribution module 929 comprises four air spring valves 926, 928, 930, 932 through which compressed air from the compressed air supply system 902 can be supplied to the air springs 918, 920, 922, 924 of the air suspension system 900 of a vehicle. The air spring module 929 also includes a pressure sensor 916, which can detect the pressure level in the air distribution module 929.

[0202] To further reduce the pressure at outlet 911, compressed air can be discharged into the air springs 918, 920, 922, 924 and / or into the connecting volume 940. The connecting volume 940 also includes a piston volume of the compressor 906, which is accordingly designed as a piston compressor.

[0203] To vent the compressed air supply system 902, and in particular the air dryer 910 and / or the air distribution module 929, the air spring valves 926, 928, 930, 932 are closed and the compressor 906 is set to idle. Then the outlet valve 915, which is designed as a 2 / 2-way solenoid valve, is opened.

[0204] Fig. 9B schematically shows the with reference to Fig. 9A described compressed air supply system 902, wherein in the Fig. 9B The direction of flow of compressed air is indicated by arrows.

[0205] In the operation of the compressed air supply system 902, air 951 is first drawn in from the surrounding atmosphere 950 by the compressor 906 and compressed by the compressor 906. A portion of the compressed air is discharged into the connecting volume 940, so that the pressure in the connecting volume 940 is two bar. The remaining compressed air is routed as compressed air 952 to the air dryer 910. The air dried by the air dryer is discharged as dry compressed air 953 into the compressed air reservoir 917. For this purpose, the reservoir valve 934 is opened.

[0206] Since the pressure in the air dryer 910 is 18 bar, the compressed air supply system 902 cannot be vented without generating a noise level above a critical limit.

[0207] In Fig. 9C is schematically the in relation to Fig. 9A and 9B The described compressed air supply system 902 is shown, wherein in the Fig. 9C The direction of flow of compressed air is indicated by arrows when compressed air is temporarily stored in the connection volume 940 to reduce the pressure at the outlet 911.

[0208] Since the pressure in the air dryer 910 is particularly critical when venting the compressed air supply system 902, the pressure in the air dryer 910 is preferably reduced. In contrast, the pressure in the compressed air reservoir 917 is generally less critical during venting.

[0209] Accordingly, to reduce the pressure in the air dryer 910, the reservoir valve 934 is closed and the separation valve 940 is opened instead. Dry compressed air 953 then flows into the air distribution module 929. Since the air spring valves 926, 928, 930, and 932 are closed, the air springs 918, 920, 922, and 924 are not filled with compressed air. Instead, the check valve 938 is opened, allowing the compressed air to flow through the air distribution module and be discharged into the connection volume 940.

[0210] The connection volume 940 is then pressurized with compressed air, so that in the example shown here, the pressure in the connection volume 940 increases from 2 bar to 10 bar. As a result, the pressure in the air dryer 910 drops accordingly from 18 bar to 10 bar, thus falling below a critical limit, which could be, for example, 11 bar or 12 bar.

[0211] Fig. 9D schematically shows the with reference to Fig. 9A bis Fig. 9C described compressed air supply system 900, wherein in the Fig. 9D Arrows indicate the direction of compressed air flow during the venting of the compressed air supply system 902 and, in particular, the air dryer 910. After reducing the pressure in the air dryer 910 to 10 bar by pressurizing the connection volume 940 with compressed air, the compressed air supply system 902 can now be vented at a comparatively lower pressure.

[0212] To vent the system, the outlet valve 915 is opened, allowing compressed air 953 to flow through it. By venting the compressed air supply system 902, the pressure in the air dryer 910 drops accordingly from 10 bar to 0 bar, i.e., to the pressure of the surrounding atmosphere 950. Reference symbol list [part of the description]

[0213] 1, 1'Compressor connection 2, 2'Compressed air supply connection 3, 3'Outlet 50, 50'Ambient atmosphere 51, 51'Intake air 52, 52'Compressed air 53, 53'Compressed air 54, 54'Compressed air 55, 55'Data connection 56, 56'Control line 100, 100'Control unit 101, 100'Vehicle 102, 102'Compressed air supply system 103, 103'Pneumatic system 106, 106'Compressor 107, 107'Intermediate storage 108, 108'Air distribution module 109, 109'Overpressure volume 110, 110'Air dryer 111, 111'Inlet valve 112, 112'Exhaust valve 113, 113'Compensation volume 116, 116'Pressure sensor 118, 120, 122, 124, 118', 120', 122', 124'Air springs 121, 121'Air spring system 126, 128, 130, 132, 126', 128', 130', 132'Air spring valves 129Gallery 131Main pneumatic line 150Pneumatic system 152Compressed air supply system 154Air spring system 155Control unit 156Compressed air valve 158Compressor 160Ambient 162Air 164Compressed air 166Air dryer 168Main pneumatic line 170Compressor connection 172 Compressed air supply connection 174 Dried compressed air176 Air distribution module 178 Gallery 180 Pressure sensor 182, 184, 186, 188 Air springs 190, 192, 194, 196 Air spring valves 198 Non-return valve 200 Non-return line 202 Auxiliary reservoir 204 Overpressure volume 206 Compensation volume 208 Intermediate reservoir 300 Diagram 302 Amount of compressed air released to the surrounding atmosphere 304 Pressure at the outlet 306, 308, 310 Curves 312 Arrow 314 First partial pressure range 316 Second partial pressure range 500 Control unit 502 Compressed air supply system 503 Vehicle 506 Compressor 507 Main pneumatic line 508 Air distribution module 510 Air dryer 511 Inlet 512 Outlet 515 Compressed air reservoir 516 Pressure sensor 518, 520, 522, 524 Air springs 521 Air spring system 534 Front axle 536 Rear axle 550 Ambient atmosphere 551 Data connection 552 Compressed air 552' Reduced compressed air quantity 555 Control line 580 Pressure of the air spring which has the smallest pressure difference to the pressure in the air distribution module compared to the pressures in the other air springs 582, 584, 586 Other air springs600 Compressed air supply system 602, 604, 606, 608 Air spring valves 610, 612, 614, 616 Air springs 618 Air spring system 620 Air distribution module 622 Pressure sensor 624 Reservoir valve 626 Compressed air reservoir 627 Gallery 628 Compressor 630 Electric motor 632 Air dryer 633 Main pneumatic line 634 Relay valve 636 Inlet 638 Outlet 639 Auxiliary storage 640 Valve 641 Check valve 642, 643 Throttle 802 Compressed air supply system 803 Vehicle 806 Compressor 808 Air distribution module 810 Air dryer 811 Inlet 812 Outlet 813 Filter 815 Compressed air reservoir 816 Pressure sensor 817 Separation valve 818, 820, 822, 824 Air springs 819 Reservoir valve 821 Air spring system 823 Check valve 825 Booster valve 826, 828, 830, 832 Air spring valves 838 Auxiliary reservoir 840 Main pneumatic line 842 Connection volume 844 Return line 846 Compressor line 848 First compression stage 850 Intake air 851 Compressed air 852 Compressed air 853 Second compression stage 860 Throttle 862 Check valve 864 Check valve 866 Throttle 900 Air spring system902 Compressed air supply system 904 Auxiliary storage tank 906 Compressor 907 DC motor 910 Air dryer 911 Inlet 912 Outlet 914 Throttle 915 Outlet valve 916 Pressure sensor 917 Compressed air reservoir 918, 920, 922, 924 Air springs 929 Air distribution module 926, 928, 930, 932 Air spring valves 934 Reservoir valve 936 Boost valve 938 Check valve 940 Separation valve 941 Connection volume 942 Check line 944 Compressor line 948 First compressor stage 950 Ambient atmosphere 951 Air 952 Compressed air 953 Dry compressed air 954 Pneumatic main line 955 Second compressor stage 960 Predefined pressure drop 962 Pressure in at least one air spring 964 Pressure level in the air distribution module 980 Pressure at the outlet 982 Pressure in the surrounding atmosphere 984 Separation valve 886 Throttle 988 Check valve 990 Throttle S1 Bring compressor to idle S2 Close outlet valve S3 Open air spring valves S4 Set equilibrium pressure S5 Close air spring valves S6 Open outlet valve T1 CompressorBring to idle T2 Close exhaust valve T3 Specify compressed air quantity and / or duration T4 Pressurize first air spring T5 Pressurize second air spring T6 Pressurize third air spring T7 Pressurize fourth air spring T8 Re-inflate air springs T9 Activate compressor T10 Open exhaust valve T11 Pressurize two air springs T12 Pressurize the other two air springs T13 Re-inflate air springs L1 Open inlet valve L2 Keep inlet valve open L3 Activate compressor L4 Activate booster valve L5 Pressurize one air spring for a predefined duration L6 Pressurize one air spring for a predefined duration L7 Open exhaust valve

Claims

1. Method for operating a pneumatic system (103, 103', 150) having a compressed-air supply system (102, 102', 152, 502, 600, 802, 902) and, pneumatically connected to the compressed-air supply system (102, ..., 902), an air spring system (121, 121', 154, 521, 618, 821, 900) of a vehicle (101, 101', 503, 803), wherein - the compressed-air supply system (102, ..., 902) has a pneumatic main line (168) and an air dryer (110, 110', 166, 510, 632, 810, 910) in the pneumatic main line (168), and the pneumatic main line (168) has a compressor port (1, 170) to a compressor (106, 106', 158, 506, 628, 806, 906) and has a compressed-air supply port (2, 172) to an air distributor module (108, 108', 176, 508, 808, 929), wherein the air distributor module (108, 108', 176, 508, 808, 929) is part of the compressed-air supply system (102, 102', 152, 502, 600, 802, 902) or the air spring system (121, 121', 154, 521, 618, 821, 900), and wherein - the air spring system has a number of air springs (118, 120, 122, 124, 118', 120', 122', 124',182, 184, 186, 188, 518, 520, 522, 524, 610, 612, 614, 616, 818, 820, 822, 824, 918, 920, 922, 924) which are pneumatically connected via a gallery (129, 178) of the air spring system (121, ..., 900), and wherein - the pneumatic system (103, 103, 150') has a control unit (100, 100', 155, 500) for controlling the compressed-air supply system (102, ..., 902) and the air spring system (121, ..., 900), and wherein in the method the air dryer (110, ..., 910) and the air distributor module (108, ..., 929) represent an overpressure volume (109, 109', 204), wherein - the overpressure volume (109, 109', 204) initially has a pressure (174) greater than a pressure in another part of the compressed-air supply system (152), namely in an equalization volume (113, 133', 206), having at least a first air spring (118, ..., 924) and an intermediate storage (107, 107', 208), wherein in the method compressed air (52, 52', 53, 53', 54, 54', 174, 552, 851, 852, 952, 953) from the overpressure volume (109, 109', 204) is discharged into the equalization volume (113, 133', 206), reducing pressure in the overpressure volume (109, 109', 204), namely reducing pressure in the air dryer (110, ..., 910) and reducing pressure in the air distributor module (108, ..., 929), - wherein compressed air (52, ..., 953) is discharged, a) into the first air spring (118, ..., 924) of the air spring system (121, ..., 900) and into the intermediate storage (107, 107', 208), characterized in that the intermediate storage (107, 107', 208) comprises the compressor (106, ..., 906) and a connecting volume (842, 941), wherein the connecting volume (842, 941) has a pneumatic return line (844, 942) which connects the gallery (129, 627) to the compressor (106, ..., 906) via a check valve (823, 938).

2. Method according to claim 1, characterized in that the equalization volume (113, 133', 206) comprises the first air spring (118, ..., 924) and the intermediate storage (107, 107', 208) comprises a second air spring, and compressed air is discharged temporally successively individually into the first air spring (118, ..., 924) and subsequently into the second air spring (118, ..., 924).

3. Method according to claim 1, characterized in that compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is discharged temporally successively into the first air spring (118, ..., 924) and the intermediate storage (107, 107', 208) starting with the intermediate storage (107, 107', 208).

4. Method according to at least one of claims 1 to 2, characterized in that compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is admitted initially to the air springs (118, ..., 924) of the air spring system and, only after the air springs (118, ..., 924) have been filled with compressed air, the remaining compressed air from the overpressure volume (109, 109', 204) is discharged into the intermediate storage (107, 107', 208).

5. Method according to at least one of the preceding claims, characterized in that after pressure has been reduced in the overpressure volume (109, 109', 204), the remaining compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is released at least partially through an outlet (112, ..., 912) to the surrounding atmosphere (50, ..., 950).

6. Method according to at least one of the preceding claims, characterized in that the connecting volume (842, 941) comprises an additional storage (202, 838, 904) which is pneumatically connected to the return line (844, 942).

7. Method according to any of the preceding claims, characterized in that compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is admitted to the equalization volume (113, 133', 206) if before pressure has been reduced in the overpressure volume (109, 109', 204) a pressure sensor (116, ..., 916) measures a pressure (964) in the air distributor module (108, ..., 929) which is more than 10 bar, in particular more than 11 bar, preferably more than 12 bar, and particularly preferably between 12 bar and 18 bar.

8. Method according to claim 2, characterized in that a specified compressed-air quantity (52, ..., 953) is admitted temporally successively individually to each of the first and the second air spring (118, ..., 924) and / or compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is admitted to each thereof for a predefined time period (L5, L6) and / or at a predefined pressure drop (960) in the air distributor module (108, ..., 929).

9. Method according to claim 8, characterized in that the time period (L5, L6) and / or the compressed-air quantity (52, ..., 953) established for the first and the second air spring (118, ..., 924) is different.

10. Method according to at least one of claims 8 or 9, characterized in that the compressed-air quantity (52, ..., 953) and / or the time period (L5, L6) for at least one of the first and second air springs (118, ..., 924) is established on the basis of a relative pressure difference (962, 964) between the pressure (962) of the at least first and / or second air spring (118, 120, 122, 124) and the pressure (964) in the air dryer (110, ..., 910) and / or pressure (964) in the air distributor module (108, ..., 929).

11. Method according to claim 2, characterized in that compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is admitted temporally successively individually to each of the first and the second air spring (118, ..., 924) on the basis of a measured pressure drop in the air distributor module (108, ..., 929), of a known air dryer volume, of an air distributor module volume, and of an air spring volume of the air springs (118, ..., 924) and / or of an adaptively established time interval.

12. Method according to at least one of the preceding claims, characterized in that the first air spring (118, ..., 924) has a pressure (580) which in comparison with the pressures (582, 584, 586) in the other air springs (118, ..., 924) has the smallest pressure difference (580, 552) from the pressure (552) in the air distributor module (108, ..., 929).

13. Method according to at least one of the preceding claims, characterized in that compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is discharged temporally successively individually into each of the air springs (118, ..., 924) beginning with the air spring (118, ..., 924) the pressure (580) of which in comparison with the pressures (582, ... 586) in the other air springs (118, ..., 924) has the smallest pressure difference (580, 582) from the pressure in the air distributor module (108, ..., 929).

14. Method according to claim 13, characterized in that according to the sequence of the air springs (118, ..., 924) that was ascertained using the smallest pressure difference (552, 580, ..., 586) from the pressure (552) in the air distributor module (108, ..., 929), compressed air (52, ..., 953) from the overpressure volume (109, 109', 204) is admitted to the air springs (118, ..., 924) again in the same sequence temporally successively in a or the specified compressed-air quantity (52, ..., 953) and / or to each thereof for a or the predefined time period (L5, L6) and / or at a predefined pressure drop (960) in the air distributor module (108, ..., 929).

15. Method according to any of the preceding claims, characterized in that for the first air spring (118, ..., 924) and / or the intermediate storage (107, 107', 208) a compressed-air quantity (52, ..., 953) is individually specified and the compressed-air supply system (102, ..., 902) is actuated by the control unit (100, 100', 500) such that compressed air (52, ..., 953) is discharged into the first air spring (118, ..., 924) and / or the intermediate storage (107, 107', 208) at the respectively specified compressed-air quantity (52, ..., 953).

16. Method according to any of the preceding claims, characterized in that for the first air spring (118, ..., 924) and / or the intermediate storage (107, 107', 208) a time period (L5, L6) is individually specified and the compressed-air supply system (102, ..., 902) is actuated by the control unit (100, 100', 500) such that compressed air (52, ..., 953) is discharged into the first air spring (118, ..., 924) and / or the intermediate storage (107, 107', 208) for the respectively specified time period (L5, L6).

17. Method according to at least one of the preceding claims, characterized in that the compressed-air supply system (102, ..., 902) is actuated by the control unit (100, 100', 500) such that the compressor (106, ..., 906) stores a portion of the compressed air while compressed air (52, ..., 953) is vented through the outlet (112, ..., 912), such that compressed air (52, ..., 953) is released to the surrounding atmosphere (50, ..., 950) at a comparatively lower pressure difference (980, 982) between a pressure (980) at an outlet (112, ..., 912) and a pressure (982) in the surrounding atmosphere (50, ..., 950).