Method for operating a compressed air system

Abstract

The invention relates to a method for operating a compressed air system in a vehicle, wherein the compressed air system has pneumatically operated actuators, switchable pneumatic valves and devices for supplying and preparing compressed air, which are connected to one another via a pneumatic line system, wherein the devices for supplying compressed air comprise at least one compressed air source and a compressed air store, and in the line system a pressure sensor is provided for measuring the pressure, wherein for controlling the compressed air system in an open- and closed-loop manner at least one electronic control device is provided, and the pneumatic valves are actuated in accordance with an algorithm programmed in the control device and in accordance with a switching program specified therein, wherein the algorithm for the switching program is programmed such that depending on the difference between the pressure in the compressed air store and the pressure in the line system, pneumatic valves are actuated to connect the compressed air store to the line system only after pressure equalisation between the pressure in the compressed air store and the pressure in the line system, during which pressure equalisation compressed air from the compressed air source and / or the actuators or devices is introduced into the line system.

Description

[0001] Procedure for operating a compressed air system

[0002] The invention relates to a method for operating a compressed air system in a vehicle, wherein the compressed air system has a plurality of pneumatically operated actuators, switchable pneumatic valves, and further devices for compressed air supply and devices for compressed air treatment, which are interconnected via a pneumatic line system. The devices for compressed air supply comprise at least one compressed air source and a compressed air reservoir. A pressure sensor is present in the line system to measure the pressure. At least one electronic control device is provided for controlling and regulating the compressed air system, and the actuation of the switchable pneumatic valves, devices for compressed air supply, and devices for compressed air treatment takes place according to an algorithm programmed in the control device and a switching program predefined therein, namely according to a so-called switching logic.

[0003] The method according to the invention is preferably usable for operating a compressed air system of a vehicle air suspension, wherein a plurality of air bellows assigned to the respective wheels or axles of the vehicle are provided as actuators, each of which can be connected to the pneumatic line system via a switchable bellows valve. Accordingly, the invention also relates to a vehicle air suspension suitable for implementing the method, an algorithm programmed into a control device of a vehicle control system, and a motor vehicle with such an air suspension.

[0004] Compressed air systems, also known as compressed air supply systems, have various devices for compressed air treatment and compressed air supply and are generally designed as open or closed systems. In open systems, the compressed air system / pneumatic system is supplied with air taken directly from the atmosphere, which is filled via the compressor. Even in an open system, air from a compressed air reservoir is used, for example, to accelerate the filling of the bellows by a compressor. In a closed system, on the other hand, the air to supply the compressed air system is mainly used from a compressed air reservoir in a closed circuit. In this case, compressed air is pumped from the compressed air reservoir into the pneumatic system by a compressor, in particular for filling the bellows of an air suspension system.Similarly, when the bellows are emptied when the vehicle is lowered, the compressed air flows back into the compressed air reservoir with the assistance of the compressor.

[0005] A key element in both systems is therefore a compressed air reservoir. Given the high performance levels typical today, such as electronically controlled air suspension systems for trucks (ECAS - Electronic Controlled Air Suspension), the system must handle significant volumes of air at high pressure.

[0006] If the compressed air reservoir is suddenly connected to the rest of the piping system, for example, to fill the compressed air reservoir with the compressor or to fill the air springs from the compressed air reservoir, this can lead to a sharp noise development due to the sudden pressure change in the system in cases where there is a significant pressure difference between the compressed air reservoir and the piping system. This noise development, known as "boiler impact," is caused by the sudden pressure change and high dynamics / high flow rates creating a pressure wave or pressure surge. This pressure wave is amplified in the relatively large compressed air reservoir by the reservoir wall, which acts as a membrane, and is transmitted into the vehicle as structure-borne and / or airborne noise.

[0007] This unpleasant noise development during filling or venting processes associated with the compressed air storage occurs particularly when unfavorable parameters interact in the design of the overall system and / or in the control system.

[0008] The object of the invention was therefore to provide a method for operating a compressed air system in a vehicle, with the aid of which such noise development, i.e. boiler knocking, can be avoided.

[0009] This object is achieved by the features of the main claim. Further advantageous embodiments are contained in the dependent claims. Also disclosed are a vehicle air suspension system, an algorithm programmed into a control device of a vehicle control system, and a vehicle with such an air suspension system, preferably a commercial vehicle.

[0010] The algorithm for the switching program is programmed in such a way that, depending on the difference between the pressure in the compressed air reservoir and the pressure in the pipe system, pneumatic valves for connecting the compressed air reservoir to the pipe system are only actuated after the control device has initiated pressure equalization between the pressure in the compressed air reservoir and the pressure in the pipe system by actuating switchable pneumatic valves, whereby compressed air from the compressed air source and / or the actuators is introduced into the pipe system for pressure equalization.

[0011] Actuators are drive technology units that convert an electrical signal into mechanical movements or changes in physical quantities such as pressure or temperature and thus actively intervene in the controlled process, such as air bellows in an air suspension system.

[0012] Preferably, one embodiment of the method is usable for operating a compressed air system of a vehicle air suspension, wherein a plurality of air bellows assigned to the respective wheels or axles of the vehicle are provided as actuators, each of which can be connected to the pneumatic line system via a switchable bellows valve. The devices for supplying and processing compressed air comprise at least one electrically driven compressor, a compressed air reservoir connectable to the line system via at least one switchable storage valve, an air dryer, and an air filter. Pressure equalization is achieved by introducing compressed air from the compressor and / or the air bellows into the line system.

[0013] In vehicle air suspension systems for trucks, where large quantities of air and high pressure are required to fill the air bellows, the method according to the invention achieves a particularly strong reduction in undesirable noise development due to boiler knocking.

[0014] A development of the method that can be easily implemented with little circuitry effort consists in the fact that, before the compressed air reservoir is filled by the compressor, pressure equalization takes place by first activating the compressor, then measuring the pressure in the line system and only then connecting the compressed air reservoir to the line system via the storage valve when there is a pressure equalization to the pressure in the compressed air reservoir in the latter due to the operation of the compressor.

[0015] Depending on the type and design of the compressed air system, pressure equalization does not necessarily have to be carried out to an absolutely identical value, i.e. a pressure difference of 0 bar. For the method according to the invention, it is essential that any pressure difference AP(2) still existing after pressure equalization is so much smaller than a pressure difference AP(i) existing before pressure equalization between the pressure in the compressed air reservoir (storage pressure) and the pressure in the pipe system (line pressure) that boiler slamming is avoided. To avoid unpleasant pressure surges or boiler slamming, a design of the method is also suitable in which pressure equalization takes place in such a way that the pressure in the pipe system differs from the pressure in the compressed air reservoir (storage pressure) by a maximum of + / - 10%.Occasionally, even a somewhat higher difference is possible, provided that tests show that noise development due to pressure surges / boiler impact does not occur or only occurs within tolerable limits.

[0016] A further development of the method consists in equalizing the pressure by introducing compressed air from at least one air bellows into the line system before measuring the pressure in the compressed air reservoir using a pressure sensor within the line system. Initially, the at least one air bellows is connected to the pneumatic line system via the respective bellows valve. Once the pressure in the line system is close to the pressure in the compressed air reservoir, the bellows valve is closed and the reservoir valve is opened. Such pressure equalization by introducing compressed air from the bellows prevents the often noisy operation of the compressor (compressor operation, compressor running), but must be balanced against the potentially noticeable effect of a slight lowering of the vehicle body supported by the air springs.

[0017] The accumulator pressure is regularly re-measured both for leak detection and during active processes / switching operations in the compressed air system. The last known value for the accumulator pressure can be used as the initial variable for the accumulator pressure before the "re-measurement", whereby it is generally assumed that no leakage is present. A further embodiment of the invention consists in the fact that before the air bellows are filled from the compressed air reservoir, the so-called "overflow", the pressure is equalized by first feeding compressed air from at least one of the air springs into the line system when there is a pressure difference AP(i) between the pressure in the compressed air reservoir (accumulator pressure) and the pressure in the line system (line pressure). The compressed air reservoir is only connected to the line system via switchable valves when the pressure difference AP(i) has been equalized or reduced to a value of AP(2) < AP(i).For the sake of clarity, AP(i) refers to the pressure difference between the accumulator pressure and the line pressure before pressure equalization, while AP(2) represents the pressure difference after pressure equalization between the accumulator pressure and the line pressure. The equalization of the pressure difference or its reduction depends on the pressure available in the air bellows, so that a fixed value for the remaining pressure difference cannot be specified. It is important to bear in mind that the average pressure in the air bellows is assumed to be around 8 bar, while the pressure in the pressure accumulator can reach around 15 bar. It is important, however, that the pressure increase in the line system by releasing pressure medium from the bellows into the line system occurs in such a way that the previously determined pressure difference between the accumulator pressure and the line pressure is as low as possible to avoid boiler shock.

[0018] A further embodiment of the inventive method consists in that, prior to regeneration of the dryer by blowing out compressed air via a release valve, pressure equalization occurs. If there is a pressure difference between the pressure in the compressed air reservoir (storage pressure) and the pressure in the line system (line pressure), compressed air is first fed into the line system from either at least one of the air springs and / or through the compressor. The compressed air reservoir is only connected to the line system via switchable valves and then to the release valve once pressure equalization has occurred between line pressure and pressure in the compressed air reservoir. The method according to the invention makes it possible to avoid boiler slamming or pressure surges even during regeneration, i.e., when the dryer is regularly blown out with dry system air to absorb and remove moisture.For use in the exemplary embodiment of an air suspension described below, in which on the one hand the air bellows and the switchable bellows valves are directly connected to one another in a first pneumatic line system (gallery near the bellows) and on the other hand at least some of the devices for compressed air supply and preparation are provided in a second pneumatic line system (gallery near the accumulator), and in which the gallery near the bellows and the gallery near the accumulator are connected to one another via at least one isolating valve, a further development of the method is suitable in which the pressure in a first line system near the bellows (gallery near the bellows) is measured for regeneration and, if there is a pressure difference between the accumulator pressure and the line pressure, compressed air from the air springs or through the compressor is fed into the line system.

[0019] The pressure equalization during regeneration can then be achieved by the following exemplary sequences of switching operations:

[0020] - Opening the bellows valves and the isolation valve until pressure equalization occurs in the "bellows-near gallery"—determined by measurement (pressure sensor). Then closing the isolation valve, and only then opening the accumulator valve and the release valve, through which the air is released to the atmosphere. Pressure equalization occurs solely through the pressure present in the bellows; while the process is quiet, it is possible for the vehicle to sink (regeneration, switching logic / switching sequence A).

[0021] - Another possible sequence includes: switching on the compressor, opening the isolation valve until pressure equalisation in the "bellows-near gallery" - determined by measurement or depending on the running time of the compressor - then closing the isolation valve and only then opening the storage valve and the discharge valve, through which the air is released to the outside; the vehicle does not sink, but the regeneration process thus developed is noisier (regeneration, switching logic / switching sequence B).

[0022] A further development of the method involves repeating the pressure equalization by introducing compressed air from an air bellows, and introducing compressed air from at least one different air bellow into the line system than the one used for the previous pressure equalization. Since releasing compressed air from an air bellow into the line system can cause the body to sink at the wheel or axle supported by the bellows, this effect can be avoided or at least minimized by appropriately replacing the air bellows intended for introducing compressed air.

[0023] In a further development of the method, when compressed air is introduced from multiple air bellows into the line system, compressed air is first introduced from the air bellows with the lowest bellows pressure, followed sequentially by compressed air from the air bellows with the next highest bellows pressure. This procedure also reduces or prevents the sinking of, for example, a corner of the vehicle, while also providing the highest possible compensating pressure in the line system. If the pressure in two bellows is the same, both are either connected to the line system sequentially using a random function or specified in a predetermined sequence, possibly vehicle-specific.

[0024] In another version of the process, compressed air is pumped into the line system instead of compressed air from one of the air bellows or in addition to it from the compressor. This can shorten or simplify the corresponding pneumatic switching processes or the achievement of pressure levels.

[0025] When filling air bellows from the compressed air reservoir, which is supported by operation of the compressor (compressor-assisted residual pressure utilization from the compressed air reservoir), in the so-called "boost", a different version of the process is used in which pressure equalization occurs when there is an existing pressure difference AP(i) between the pressure in the compressed air reservoir (reservoir pressure) and the pressure in the line system (line pressure), compressed air is first filled into the line system from at least one of the air bellows and / or through the compressor. The air bellows and the compressed air reservoir are only then connected to the line system via switchable valves and compressed air is pumped from the reservoir with compressor support via the line system into the air bellows when the pressure difference AP(i) is equalized or reduced to a value of AP(2) < AP(i).

[0026] The term "compressor support" or the designation / feature "support through compressor operation" means that at least one stage of the compressor is used to achieve an increased flow and / or higher pressure of the medium (air) within the piping system, i.e. to energetically "charge" the pressure medium within the system. In connection with the "boost" switching states and the "reflow" described below, this means that the compressor is then not used to compress "new" air from the atmosphere and pump it into the system, but rather to accelerate / improve the processes within the system. This should not be confused with pre-pressure equalization, in which the compressor can certainly fill the piping system with compressed air, as described above.

[0027] Although compressor support during or for pressure equalization is generally noisier than pressure equalization from the air spring bellows, it reduces the risk of the body sinking at the wheel or axle supported by the bellows.

[0028] A further development of the "boost" process consists in the fact that, after pressure equalization, a connection is established between the air bellows and the compressed air reservoir by opening a separate boost valve and the bellows valves. This type of process or switching sequence is particularly suitable for the exemplary design of an air suspension system described below, in which, on the one hand, the air bellows and the switchable bellows valves are directly connected to one another in a first pneumatic line system (gallery near the bellows), and, on the other hand, the devices for compressed air supply and preparation are provided and connected to one another in a second pneumatic line system (gallery near the reservoir). The gallery near the bellows and the gallery near the reservoir are connected to one another via a separating valve and a further "reflow valve" connected to the boost line, with the pressure sensor located in the gallery near the bellows.

[0029] In the air suspension system described below as an example, the pressure accumulator can be connected to the line system not only via the accumulator valve, but also via a separate "boost valve." When filling air bellows using compressor-assisted residual pressure utilization from the compressed air reservoir, pressure equalization can be achieved using the following exemplary sequences of switching operations / switching sequences: - Switching on the compressor, opening the isolation valve and the reflow valve until pressure equalization in the "boost line" is achieved - determined by measurement or depending on the compressor's running time. Then, opening the "boost valve" provided for the connection to the accumulator and opening the bellows valves, whereby a reflow valve also provided in the described air suspension system is closed beforehand or at the latest at the same time (boost, switching logic / switching sequence A).

[0030] - Another possible sequence includes: switching on the compressor, opening the isolation valve until pressure equalisation in the "bellows-near gallery" - determined by measurement or depending on the running time of the compressor -, then opening the "boost valve" provided for the connection to the storage tank and simultaneously or subsequently opening the bellows valves (boost, switching logic / circuit sequence B),

[0031] - Another possible sequence involves opening the bellows valves and the reflow valve until pressure equalization occurs in the boost line—determined by measurement. Pressure equalization is not achieved by the compressor, but solely by the pressure present in the bellows (quiet, but possible vehicle sinking, boost, switching logic / switching sequence C).

[0032] Further variants of switching sequences for compressor-assisted residual pressure utilization from the compressed air storage are possible, for example the opening of the bellows valves and the isolation valve until pressure equalization in the "bellows-near gallery", after which the bellows valves are closed again and the storage valve is opened (boost, optional switching logic / switching sequence).

[0033] Based on the switching sequence / switching logic described here, it becomes clear once again that before the accumulator is connected to the line system, in this case when the air suspension is switched to boost mode, a sequence of switching operations for valves and units / devices is provided according to the invention, which leads to a prior pressure equalization between the accumulator pressure and the pressure in the line system.

[0034] The medium flow inverse to the “boost” is the so-called “reflow”, namely a filling of the compressed air reservoir from the air bellows, which is supported by the operation of the compressor (compressor-supported residual pressure utilization from the air bellows).With this "reflow", a further development of the process is used in which pressure equalization takes place before filling by measuring the pressure in the line system and, if there is a pressure difference AP(i) between the pressure in the compressed air reservoir (accumulator pressure) and the pressure in the line system (line pressure), compressed air from at least one of the air springs and / or through the compressor is first filled into the line system and the compressed air reservoir and the air bellows are only connected to the line system and compressed air from the air bellows is pumped with compressor support via the line system into the compressed air reservoir when the pressure difference AP(i) is equalized or reduced to a value of AP(2) < AP(i).

[0035] A further development of the method consists in that, after pressure equalization, a connection is made between the air spring bellows and the compressed air reservoir by opening the reservoir valve, a separate reflow valve connecting the compressed air reservoir to the first line system near the bellows (gallery near the bellows), and by opening the bellows valves.

[0036] The latter two embodiments of the process are particularly suitable for use in the exemplary design of an air suspension system described below, with a gallery near the bellows and a gallery near the accumulator separated by a separating valve. Pressure equalization during "reflow" can then be achieved using the following exemplary sequences of switching operations:

[0037] - Switching on the compressor, opening the isolation valve until pressure equalisation in the "bellows-near gallery" - determined by measurement or depending on the running time of the compressor -, then closing the isolation valve and opening the storage valve simultaneously with or after opening the bellows valve(s), whereby the reflow valve is open (reflow, switching logic / circuit sequence A),

[0038] - Another possible sequence includes: opening the bellows valves and the isolation valve until pressure equalization occurs in the "bellows-near gallery"—determined by measurement, then closing the isolation valve and opening the reflow valve and the storage valve. Pressure equalization is not achieved by the compressor, but only by the pressure present in the bellows (reflow, switching logic / switching sequence B, quiet, but the vehicle may sink). A further development of the process involves using one of the following values ​​as the line pressure:

[0039] - either a pressure in the pipe system measured at a previous point in time in a first pipe system close to the bellows and / or in a second pipe system close to the accumulator (pipe pressure),

[0040] - or a stored old value of the pressure in the pipe system,

[0041] - or a fixed value for the pressure in the pipe system, preferably a value of < 2 bar.

[0042] Another development of the method consists in the fact that, when the pressure in the compressed air reservoir (storage pressure) and the pressure in the line system (line pressure) are equalized by compressor operation, the line pressure that can be achieved by compressor operation is determined using tables stored in the algorithm for the correlation between compressor running time and line pressure.

[0043] A further embodiment of the method consists in the storage pressure being specified as a fixed value by the algorithm, preferably as an empirically determined average value. This procedure simplifies the circuit sequence, as does another embodiment of the method, which consists in the fact that, when pressure equalization between the storage pressure and the pressure in the line system occurs through compressor operation, the line pressure achievable through compressor operation can be achieved using compressor running times stored in the algorithm, and the compressed air storage is only connected to the line system via switchable valves once the running times have been reached. In contrast to the above-mentioned determination based on tabular values, at least feedback of the running times is required here.

[0044] The term "gallery," often used in technical jargon to describe a section of a compressed air system, is not always precisely and unambiguously defined. It is used both for parts of the piping system related to the compressed air supply and the reservoir, and for parts of the piping system that solely contain the actuators, in this case the air springs. Depending on the design and structure of the compressed air system, not only the "boost line" and associated components can be made accessible for pressure equalization, but also other parts of the piping system, such as the direct connecting line between the individual air spring bellows or between the associated bellows valves, known as the "near-bellows gallery." For this purpose, the algorithm provides appropriate valve switching sequences.

[0045] In the vehicle air suspension systems shown below in the exemplary embodiments, the line system and the valve arrangement are designed in such a way that the boost line is identical to the reflow line at least in some areas, which simplifies the structure of the entire compressed air system with a two-stage compressor.

[0046] The method according to the invention for operating a compressed air system is particularly effective for preventing boiler hammer in conjunction with a vehicle air suspension system. The air spring bellows and the switchable bellows valves are interconnected in a first pneumatic line system (gallery near the bellows), while the devices for compressed air supply and treatment are provided in a second pneumatic line system (gallery near the accumulator), and the first and second pneumatic line systems are interconnectable via at least one switchable pneumatic valve designed as a separation valve. The pressure sensor is arranged in the first pneumatic line system (gallery near the bellows).

[0047] Preferably, a further valve (reflow valve) connected in parallel is arranged to connect the gallery near the bellows and the gallery near the accumulator, and a valve (boost valve) connected in parallel to the accumulator valve is provided to connect the accumulator to the piping system.

[0048] The invention also relates to a vehicle air suspension with a control device in which an algorithm for carrying out a switching program according to the method according to the invention is programmed, to such an algorithm and to a vehicle, in particular a commercial vehicle with such a vehicle air suspension.

[0049] The invention will be explained in more detail using an exemplary embodiment. Fig. 1 shows a schematic diagram of the assignment of a compressed air system operating according to the method according to the invention for operation in a vehicle,

[0050] Fig. 2 the pneumatic circuit diagram of a compressed air system of a

[0051] Vehicle air suspension, here in boost mode, namely filling of air bellows by means of compressor-assisted residual pressure utilization from the compressed air reservoir,

[0052] Fig. 3 the pneumatic circuit diagram of a compressed air system of a

[0053] Vehicle air suspension, here in reflow mode, namely filling the compressed air reservoir by means of compressor-assisted residual pressure utilization from air bellows.

[0054] Where appropriate, English terms are included, as they are preferred in technical jargon today. In the figures, identical or similar elements may be referenced with the same reference numerals. To clarify the invention, it is advantageous to view the figures together.

[0055] Fig. 1 shows a basic representation of the assignment of a compressed air system 100 operating according to the method according to the invention for operation in a vehicle 200, namely here for operation in a commercial vehicle 200'. The individual devices, units, and functions of the compressed air system 100 are represented by conventional pneumatic symbols and other technical symbols, essentially correspond to the two representations in Figs. 2 and 3, and are described in detail below.

[0056] The compressed air system 100 shown in Fig. 1 differs only slightly from the illustrations in Figs. 2 and 3. Firstly, in Fig. 1, actuators 41-44 are shown in a general "black box" representation, while in Figs. 2 and 3, actuators are shown in the form of symbolically indicated air springs with air bellows 1-4. Secondly, in Figs. 2 and 3, some line sections are drawn thicker to clarify special circuit variants / circuit sequences, as also explained in detail below.

[0057] The compressed air system shown in Figs. 2 and 3 is intended for operating a vehicle air suspension 300 in a vehicle 200, 200'. For the sake of simplicity, the vehicle air suspension 300 is represented only by a dashed line surrounding the compressed air system.

[0058] As can also be seen in Fig. 2 and 3, several air bellows 1-4 assigned to the respective wheels 201 or axles 202 of the vehicle 200, 200' are provided there as actuators, wherein in Fig. 1 to 3, in order to clarify the features of the operation of the compressed air system that are essential to the invention, a sufficiently known representation of structural details of a vehicle air suspension has been omitted.

[0059] The compressed air system illustrated in Figs. 2 and 3 and intended for operating a vehicle air suspension 300 interacts with a control device 30 in which an algorithm for executing a switching program according to the method according to the invention is programmed. The control device 30 is in turn integrated into a vehicle control system 400, shown in principle in Fig. 1 , wherein the control device 30 and the vehicle control system 400 are connected to the compressed air system in a known manner by appropriate electrical lines or wireless communication for the purpose of interaction. For the sake of clarity, the control device 30 and the vehicle control system 400 are indicated only by dot-dash lines.

[0060] Figs. 2 and 3 each show the pneumatic circuit diagram of a compressed air system for a vehicle air suspension. As mentioned above, the individual devices, units, and functions are represented by pneumatic symbols and other technical symbols, and two different circuits / circuit sequences are illustrated. In such a compressed air system, the advantages of the method according to the invention, namely the prevention of boiler shock, are particularly evident.

[0061] Fig. 2 shows the circuit of the compressed air system in a so-called boost mode, in which the air bellows 1 to 4 are filled from the compressed air reservoir 9, whereby the filling of the air bellows 1 to 4 is supported by operation of the compressor 15, thus showing the circuit with a so-called compressor-supported residual pressure utilization from the compressed air reservoir 9.

[0062] Fig. 3 shows the circuit in reflow mode, a circuit with a medium flow that is reversed to the "boost" with respect to the compressed air reservoir, in which the compressed air reservoir 9 is filled from the air bellows 1 to 4, whereby the filling of the compressed air reservoir 9 is supported by the operation of the compressor 15, thus showing the circuit with a so-called compressor-assisted residual pressure utilization from the air bellows 1 to 4.

[0063] For clarity, the flow lines / line sections that determine the boost mode or reflow mode are drawn thicker in Fig. 2 and 3.

[0064] Starting with the right side of the pneumatic circuit diagram underlying the respective analysis in Figs. 2 and 3, the actuators are the air bellows 1 to 4, in which a pressure of 50 prevails and which can be connected to a so-called bellows-near gallery 5 via the respective bellows valves 1a to 4a. The bellows-near gallery 5 is the part of the line system that establishes a direct, closest connection between the air bellows and bellows valves.

[0065] The gallery 5 near the bellows is connected to the rest of the piping system via two additional valves, namely a separation valve 6 and a reflow valve 7. A pressure sensor 8 is also provided on or in the gallery 5 near the bellows. It is arranged here between the bellows valves 1a to 4a and the valves 6 and 7, respectively. Upon pressure measurement, it transmits an electrical signal corresponding to the pressure 80 in the piping system to the control device 30.

[0066] The switchable and controllable devices, valves, sensors, actuators, drives, etc. of the compressed air system are, where possible and necessary, connected to the control unit 30 using appropriate electrical cables or wireless communication in a known manner. For the sake of clarity, this is indicated here only by a dot-dash line, which encompasses the corresponding devices but is not to be considered exhaustive.

[0067] The pneumatic circuit diagram also shows a compressed air reservoir 9, in which a pressure of 90 prevails. The compressed air reservoir 9 is connected via a reservoir valve 10 and a boost valve 11 connected in parallel to it to a line system comprising the pressure supply line 12 (pressure line) and the overflow line 13. The overflow line 13 is used in both boost mode and reflow mode and is then referred to as a boost line or reflow line, respectively, whereby its flow direction remains the same. The bellows valves 1a to 4a, the isolating valve 6, the reflow valve 7, the reservoir valve 10, the boost valve 11, and the outlet valve 22 are solenoid valves that are actuated by the control device 30 and the algorithm programmed therein. This list is not exhaustive; other valves and units can also be actuated by the control device 30.

[0068] A two-stage compressor 15 driven by an electric motor 14 is shown on the left side of the circuit diagram. The control unit 30 also controls the electric motor and thus the compressor 15. Also visible in the piping system are an air dryer 16, a filter 17, and other valves and throttles, namely the check valves 18, 19, the throttles 20, 21, the outlet valve 22, and the pilot-operated valve 23, which is connected to a control pressure line 24. The piping system is connected to the environment via the outlet or inlet 25.

[0069] Pressure supply line 12, overflow line 13, compressor 15, air dryer 16, check valves 18, 19, throttles 20, 21, as well as the switchable solenoid valve 22 and the pilot-operated valve 23 can be considered to belong to the part of the pneumatic piping system referred to as the accumulator-near gallery, which essentially contains the compressed air supply devices. However, the definition of the term "accumulator-near gallery" is not entirely clear in the technical field and can encompass different devices and valves in different compressed air systems, as already mentioned above.

[0070] Fig. 2 now shows, by way of example, which lines and system components in such a vehicle air suspension system are affected when carrying out the method according to the invention for preventing boiler hammer in boost mode, and which steps are required for this. When filling air suspension bellows using compressor-assisted residual pressure utilization from the compressed air reservoir, in the case shown here, the two air suspension bellows 3 and 4, which belong to an axle 202, are to be filled quickly, thus lifting the axle 202. The flow in boost mode from the pressure accumulator 9 into the air suspension bellows 3 and 4 is represented by the arrows in Fig. 2, and the affected lines / line components through which air flows in boost mode are shown in thicker lines in Fig. 2 for clarity.The control device 30, applying the algorithm, first switches on the electric motor 14, thereby driving the compressor 15, which fills the line system with air and increases the pressure there. The isolation valve 6 and the reflow valve 7 are opened, and the pressure 80 in the line system 5 is measured via the pressure sensor 8. The accumulator valve 10 and the boost valve 11 remain closed until pressure equalization in the boost line occurs, i.e., until the pressure in the line system is equal to or close to the accumulator pressure / pressure in the compressed air accumulator. The pressure 90 in the compressed air accumulator 9 (accumulator pressure) is either a fixed pressure 90, possibly known from the last measurement, or a pressure 90 specified as an average value by the algorithm.

[0071] Boost mode is then started after pressure equalization is achieved. The "boost valve" 11, intended for connection to the reservoir, and the bellows valves 3a and 4a are opened, with the reflow valve 7 being closed beforehand or at the latest simultaneously. Due to the prior pressure equalization, no boiler hammer occurs when the boost valve 11 opens, and the air bellows 3 and 4 can be filled from the compressed air reservoir 9 with compressor assistance, as illustrated by the arrows in Fig. 2.

[0072] Fig. 3, in contrast, shows which lines and system components are affected when carrying out the method according to the invention in reflow mode, and which steps are required. When filling the compressed air reservoir by means of compressor-assisted residual pressure utilization from the air bellows, in this case, the two air bellows 3 and 4, which belong to an axis 202, are to be vented into the reservoir, thus lowering the axis 202. The flow of the air medium from the air bellows 3 and 4 into the pressure reservoir 9 in reflow mode is represented by the arrows in Fig. 3, and the affected lines / line sections through which air flows in reflow mode are also drawn in thicker lines in Fig. 3 for clarity.

[0073] In this case, pressure equalization before initiating reflow mode is not achieved by the compressor, but by the pressure 50 present in the bellows, which can be done very quietly. For this purpose, in the reflow mode shown in Fig. 3, the bellows valves 3a and 4a as well as the isolation valve 6 are opened until pressure equalization occurs in the gallery 5 near the bellows, with the pressure 80 in the line system being measured by the pressure sensor 8. After that, the isolation valve 6 is closed, the reflow valve 7 and the storage valve 10 are opened, and the reflow mode is started.

[0074] Due to the previous pressure equalization, no boiler impact occurs when the storage valve 10 is opened and the compressed air storage 9 can then be filled with compressor support from the air bellows 3 and 4, as shown in principle by the arrows in Fig. 3.

[0075] Reference symbol (part of the description)

[0076] 1 - 4 air spring bellows

[0077] 1 a - 4a bellows valve, solenoid valve

[0078] 5 gallery close to the bellows (part of the piping system)

[0079] 6 Isolation valve, solenoid valve

[0080] 7 Reflow valve, solenoid valve

[0081] 8 Pressure sensor

[0082] 9 compressed air storage

[0083] 10 Storage valve, solenoid valve

[0084] 11 Boost valve, solenoid valve

[0085] 12 Pressure supply line (Pressure Line)

[0086] 13 Overflow line (Boost Line / Reflow Line)

[0087] 14 Electric motor / compressor drive

[0088] 15 two-stage compressor

[0089] 16 air dryers

[0090] 17 filters

[0091] 18, 19 Check valve

[0092] 20, 21 Throttle

[0093] 22 Exhaust valve, solenoid valve

[0094] 23 pilot-operated valve

[0095] 24 Control pressure line

[0096] 25 Outlet / Inlet

[0097] 30 Control device

[0098] 41 -44 pneumatically operated actuator

[0099] 50 Bellows pressure, pressure in the air spring bellows

[0100] 80, 80', 80" Pressure in the pipe system 90, 90', 90" Pressure in the compressed air reservoir

[0101] 100 compressed air system

[0102] 200, 200' vehicle

[0103] 201 bike

[0104] 202 Axis

[0105] 300 vehicle air suspension

[0106] 400 Vehicle control

[0107] AP(i) Difference between the pressure in the compressed air reservoir and the pressure in the pipe system before pressure equalization

[0108] AP(2) Difference between the pressure in the compressed air reservoir and the pressure in the pipe system after pressure equalization

Claims

Patent claims 1 . Method for operating a compressed air system (100) in a vehicle (200), - wherein the compressed air system (100) comprises a plurality of pneumatically operated actuators (41-44), switchable pneumatic valves (1a-4a, 6, 7, 10, 11, 22) as well as compressed air supply devices (9-13, 14-21, 23-25) and compressed air treatment devices (16, 17), which are connected to one another via a pneumatic line system (5, 12, 13), - wherein the compressed air supply devices (9-13, 14-21, 23-25) comprise at least one compressed air source (15) and one compressed air reservoir (9), and a pressure sensor (8) for measuring a pressure (80) in the line system (5, 12, 13) is provided in the line system (5, 12, 13), - wherein at least one electronic control device (30) is provided for controlling and regulating the compressed air system (100), and the actuation of the switchable pneumatic valves (1a-4a, 6, 7, 10, 11, 22), devices for compressed air supply (9-13, 14-21, 23-25) and devices for compressed air preparation (16, 17) takes place according to an algorithm programmed in the control device (30) and a switching program (switching logic) predefined therein, characterized in that the algorithm for the switching program is programmed such that, depending on the difference between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13), actuation of pneumatic valves (10, 11) for connecting the compressed air reservoir (9) to the line system (5, 12, 13) only takes place after a time determined by the control device (30) by actuating switchable pneumatic valves (1a-4a, 6, 7, 10, 11 ,22) initiated pressure equalization between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system takes place, wherein compressed air from the compressed air source (15) and / or the actuators (41-44) is introduced into the line system (5, 12, 13) for pressure equalization.

2. Method according to claim 1 for operating a compressed air system (100) in a vehicle air suspension (300) of a vehicle (200), wherein several actuators assigned to the respective wheels (201) or axles (202) of the vehicle (200) are used as actuators. Air bellows (1-4) are provided, each of which can be connected to a pneumatic line system (5) via a switchable bellows valve (1a-4a), and the devices for compressed air supply (9-13, 14-21, 23-25) and compressed air preparation (16, 17) comprise at least one electrically driven compressor (15), a compressed air accumulator (9) that can be connected to the line system (5, 12, 13) by at least one switchable accumulator valve (10), an air dryer (16), and an air filter (17), and the pressure equalization takes place by introducing compressed air from the compressor (15) and / or the air bellows (1-4) into the line system (5, 12, 13).

3. Method according to claim 2, in which, before the compressed air reservoir (9) is filled by the compressor (15), pressure equalization takes place in that the compressor (15) is activated, the pressure (80) in the line system (5, 12, 13) is then measured and the compressed air reservoir (9) is only connected to the line system (5, 12, 13) via the storage valve (10) when there is a pressure equalization to the pressure (90) in the compressed air reservoir (9) in the latter as a result of the operation of the compressor (15).

4. Method according to claim 3, in which pressure equalization takes place such that the pressure (80) in the line system (5, 12, 13) differs by at most + / -10% from the pressure (90) in the compressed air reservoir (9).

5. Method according to claim 2, wherein, before carrying out a measurement of the pressure (90) in the compressed air reservoir (9) with a pressure sensor (8) within the line system (5, 12, 13), pressure equalization takes place by introducing compressed air from at least one air bellows (1-4) into the line system (5, 12, 13), wherein firstly the at least one air bellows (1-4) is connected to the pneumatic line system (5, 12, 13) via the respective bellows valve (1a-4a) and after reaching a pressure (80) in the line system (5, 12, 13) which approximates the pressure (90) in the compressed air reservoir (9), the bellows valve (1a-4a) is closed and the reservoir valve (10) is opened.

6. Method according to claim 2, wherein, before filling the air spring bellows (1-4) from the compressed air reservoir (9), pressure equalization is carried out by first feeding compressed air from at least one of the air springs (1-4) into the line system (5, 12, 13) when there is a pressure difference AP(i) between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13) and the compressed air reservoir (9) is only connected to the line system (5, 12, 13) via the reservoir valve (10) when the pressure difference AP(i) is equalized or reduced to a value of AP(2) < AP(i).

7. Method according to claim 2, in which, before regeneration of the dryer (16) by blowing out compressed air via a discharge valve (23), the pressure equalization takes place in that, when there is a pressure difference between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13), compressed air is first passed from either at least one of the air springs (1-4) and / or through the compressor (15) into the line system (5, 12, 13) and the compressed air reservoir (9) is only connected to the line system (5, 12, 13) via switchable valves (10) and therefrom to the discharge valve (23) when there is a pressure equalization between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13).

8. Method according to one of claims 2 to 7, wherein, when the pressure equalization is repeated by introducing compressed air from an air bellows (1-4), compressed air from at least one other air bellows (1-4) is fed into the line system (5, 12, 13) than in the case of a preceding pressure equalization.

9. Method according to one of claims 2 to 8, wherein when introducing compressed air from a plurality of air bellows (1-4) into the line system (5, 12, 13), compressed air is first introduced from the air bellows (1-4) which has the lowest bellows pressure (50) and subsequently and sequentially compressed air is introduced from the air bellows (1-4) with the next highest bellows pressure (50).

10. Method according to one of claims 2 to 9, wherein instead of compressed air from one of the air bellows (1-4) or in addition thereto, compressed air is filled into the line system (5, 12, 13) by the compressor (15). 11 . Method according to claim 2, wherein, before filling air bellows (1-4) from the compressed air reservoir (9), which is supported by operation of the compressor (15), a pressure equalization takes place in that, when there is a pressure difference AP(i) between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13), compressed air is first filled into the line system from at least one of the air bellows (1-4) and / or through the compressor (15) and the air bellows (1-4) and only then are the air bellows (1-4) and the compressed air reservoir (9) connected to the line system (5, 12, 13) and compressed air from the Compressed air reservoir (9) is pumped into the air bellows (1-4) via the line system (5, 12, 13) with the support of the compressor (15) when the pressure difference AP(i) is equalized or reduced to a value of AP(2) < AP(i).

12. Method according to claim 11, wherein after pressure equalization a connection between air spring bellows (1-4) and compressed air reservoir (9) is made by opening a separate boost valve (11) connecting the compressed air reservoir (9) to the line part (13) and opening the bellows valves (1a-4a).

13. Method according to claim 2, wherein, before filling the compressed air reservoir (9) from the air bellows (1-4), which is supported by operation of the compressor (15), a pressure equalization takes place in that, when there is a pressure difference AP(i) between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13), compressed air is first filled from at least one of the air springs (1-4) and / or through the compressor (15) into the line system (5, 12, 13) and the air bellows (1-4) and the compressed air reservoir (9) are only then connected to the line system (5, 12, 13) and compressed air is conveyed from the air bellows (1-4) with support by operation of the compressor (15) via the line system (5, 12, 13) into the compressed air reservoir (9) when the pressure difference AP(i) has fallen to a value of AP(2) < AP(i) is balanced or reduced.

14. Method according to claim 13, wherein after pressure equalization, a connection between air spring bellows (1-4) and compressed air reservoir (9) is established by opening the reservoir valve (10) and a separate reflow valve (7) connecting the compressed air reservoir (9) to the first line system (5) near the bellows and by opening the bellows valves (1a-4a).

15. Method according to one of claims 2 to 14, in which the pressure (80) in the line system (5, 12, 13) is based on one of the following values: - either a pressure (80) in the line system (5, 12, 13) measured in a first line system (5) close to the bellows and / or in a second line system (12, 13) close to the accumulator, - or a stored old value (80') of the pressure (80) in the pipe system (5, 12, 13), - or a fixed value (80") for the pressure (80) in the pipe system (5, 12, 13), preferably a value of < 2 bar.

16. Method according to one of claims 2 to 15, in which, when the pressure is equalized between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13) by operation of the compressor (15), the pressure (80) in the line system (5, 12, 13) that can be achieved by operation of the compressor (15) is determined using tables stored in the algorithm for the correlation between the running time of the compressor (15) and the pressure (80) in the line system (5, 12, 13).

17. Method according to one of claims 2 to 16, wherein the pressure (90) in the compressed air reservoir (9) is predetermined as a fixed value (90'), preferably as an average value (90"), by the algorithm.

18. Method according to one of claims 2 to 17, wherein, when the pressure is equalized between the pressure (90) in the compressed air reservoir (9) and the pressure (80) in the line system (5, 12, 13) by operation of the compressor (15), the pressure (80) in the line system (5, 12, 13) that can be achieved by operation of the compressor (15) can be achieved on the basis of running times of the compressor (15) stored in the algorithm, and the compressed air reservoir (9) is only connected to the line system (5, 12, 13) via switchable pneumatic valves (1a-4a, 6, 7, 10, 11) when the running times of the compressor (15) have been reached.

19. Vehicle air suspension (300) with a control device (30) in which an algorithm for carrying out a switching program is programmed according to a method according to claims 2 to 18, in which the air spring bellows (1-4) and the switchable bellows valves (1a-4a) are connected to one another in a first line system (5) near the bellows, while the devices for supplying compressed air (9-13, 14-21, 23-25) and devices for preparing compressed air (16, 17) are provided in a second line system (12, 13, 24) near the accumulator, and the first line system (5) near the bellows and the second line system (12, 13, 24) near the accumulator are connectable to one another via at least one switchable pneumatic valve (6) designed as a separating valve (6), wherein the pressure sensor (8) is arranged in the first line system (5) near the bellows.

20. Vehicle air suspension according to claim 19, in which a further valve (7) connected in parallel to the isolating valve (6) is arranged for the connection between the first line system (5) near the bellows and the second line system (12, 13, 24) near the accumulator, and for the connection of the accumulator (9) with the second line system (12, 13, 24) near the accumulator A further valve (11) connected in parallel to the storage valve (10) is provided in the line system (12, 13, 24). 21 . An algorithm programmed into a control device (30) of a vehicle control system (400) for executing a switching program according to a method according to claims 2 to 18.

22. Vehicle (200), in particular commercial vehicle (200'), with a vehicle air suspension (300) according to claim 19 or 20.

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