Method for controlling compressed air supply system of vehicle and compressed air supply system

Abstract

The invention relates to a method for controlling a compressed air supply system (1) of a vehicle, to which at least one compressed air consumer circuit (V1, V2, V3, V4) is coupled, the compressed air supply system (1) has a compressed air preparation unit (2), an at least partially electronically controllable valve (3) associated with the compressed air preparation unit, an electronic control unit (5), and sensor means (4; 4.1, 4.2, 4.3, 4.4), in which at least one compressed air consumer circuit can be connected to or disconnected from the compressed air supply by means of a control unit by actuating the valve, and in which method leakage monitoring of one or more compressed air consumer circuits is carried out. According to the invention, the detected leakage in one or more compressed air consumer circuits is quantified and an evaluation is carried out on the basis of the detected leakage amount, and the related unsealed compressed air consumer circuit is partially or completely disconnected or kept disconnected from the compressed air supply part on the basis of the evaluation of the leakage amount.

Description

Technical Field

[0001] This invention relates to a method for controlling a compressed air supply facility in a vehicle, wherein at least two compressed air consumer circuits are connected to the compressed air supply facility. The compressed air supply facility includes a compressed air preparation unit, a multi-loop protection valve at least partially electronically controllable and associated with the compressed air preparation unit, an electronic control unit, and sensors suitable for monitoring leaks in the compressed air consumer circuits. The compressed air consumer circuits can be connected to or disconnected from the compressed air supply unit by means of the control unit through the actuation of the multi-loop protection valve. In this method, leak monitoring of the compressed air consumer circuits is performed. Furthermore, this invention also relates to a compressed air supply facility for a vehicle and a vehicle having such a compressed air supply facility. Background Technology

[0002] Electronically controlled compressed air supply systems in vehicles, especially commercial vehicles, typically include a compressed air preparation unit, which comprises an air dryer, a multi-loop protection valve, and an electronic control unit. The control unit is connected to a pressure sensor via sensor wiring to determine the supply pressure in the supply line of the connected compressed air consumer circuit.

[0003] Using a switchable compressor, air is drawn from the environment during transport operation, compressed, and delivered via an air dryer to at least one main supply line. Multiple supply lines leading to compressed air consumer circuits branch off from the main supply line via corresponding overflow valves of a multi-loop protection valve. Each supply line is at least partially connected to a pressure sensor to detect the corresponding supply pressure. In the compressed air supply facility supplying multiple compressed air consumer circuits, the multi-loop protection valve functions to ensure that compressed air generated in the compressed air supply facility is independently transferred to the respective compressed air consumer circuits, and automatically disconnects the faulty consumer circuit from the compressed air supply facility in case of a fault, thereby allowing the remaining consumer circuits to continue to be supplied with compressed air. For this purpose, the interfaces of the consumer circuits are connected via overflow valves arranged within the multi-loop protection valve to the output interface of the air dryer of the compressed air preparation unit or to the supply line of the guiding compressed air for another consumer circuit. The relief valve opens when the pressure on the input side reaches or exceeds the adjusted opening pressure, and closes when the pressure on the output side reaches or falls below the closing pressure related to the opening pressure.

[0004] In addition to the purely pneumatically controlled mechanical function of relief valves, there are also electronically controlled multi-loop protection valves. These electronically controlled multi-loop protection valves can enable the supply of compressed air to the relief valve and / or the flow of compressed air through the relief valve, or can cut off the flow, via electromagnetic valve devices.

[0005] To monitor the proper functioning of the compressed air supply system, and especially the brake circuit of the compressed air braking system, and to maintain this proper functioning for as long as possible, it is important to identify potential leaks within the compressed air supply system or in the connected compressed air consumer circuit as early as possible. While identifying leaks is relatively straightforward during extended periods of vehicle stationary operation, this task is more challenging during running operations due to the opposing effects of compressor operation and compressed air consumption in the compressed air consumer circuit. Several leak monitoring methods are known for identifying leaks in the compressed air supply system or in one of the compressed air consumer circuits. Most of these methods rely on sensing the delivery pressure or supply pressure, or the pressure gradient of the delivery or supply pressure, comparing it to predefined boundary values, and outputting warning signals as necessary based on the comparison results.

[0006] A method for monitoring leaks in a compressed air supply system of a vehicle is known from DE 10 2019 100 788 A1. The compressed air supply system has a compressor connected to the system on the input side and multiple compressed air consumer circuits connected to the system on the output side. In this known method, during operation, the supply pressure in the supply line of at least one compressed air consumer circuit is continuously known using a pressure sensor. A pressure gradient is continuously calculated based on at least two sequentially detected pressure values ​​and the time difference between their detection, and compared with a predefined gradient boundary value, which is defined as a value less than zero. The known method initiates a monitoring period that includes not only multiple transport interruptions of the compressor during which compressed air is drawn from the compressed air consumer circuits, but also multiple transport interruptions during which no compressed air is drawn from the compressed air consumer circuits. During transport interruptions with compressed air consumption, the pressure gradient does not exceed the gradient boundary value. During a transport stoppage with no compressed air consumption, the pressure gradient will exceed the gradient boundary value and become zero, provided there is no leakage in the compressed air supply facility or in one of the compressed air consumer circuits. If the pressure gradient never exceeds the gradient boundary value within a predetermined monitoring period including multiple transport stoppages of the compressor, a leak is inferred and a warning signal is output.

[0007] Furthermore, a method for controlling a compressed air supply facility with multiple compressed air consumer circuits in a vehicle is known from DE 195 15 895 A1. In this method, compressed air can be supplied to the compressed air consumer circuits and compressed air can be drawn from the compressed air consumer circuits for transfer to other compressed air consumer circuits or for regeneration of an air dryer, controlled by a programmable electronic control unit. The electronic control unit monitors the pressure in the compressed air consumer circuits and disconnects the compressed air consumer circuit from the compressed air supply section based on a programmable boundary pressure associated with the circuit, while connecting the corresponding compressed air consumer circuit when the pressure difference is lower than the boundary pressure by a programmed pressure difference.

[0008] Known methods for controlling vehicle compressed air supply or for leak monitoring have drawbacks and therefore require improvement. Therefore, when a specific pressure level is not reached or falls below a certain level in the compressed air consumer circuit, the affected circuit will automatically and permanently disconnect from the compressed air supply via a multi-circuit protection valve and notify the driver. The disadvantage is that the affected compressed air consumer circuit and the connected compressed air consumer may then become unusable unnecessarily until it is taken to a repair shop. Summary of the Invention

[0009] Against this backdrop, the objective of this invention is to provide a method of the type described at the outset for controlling a compressed air supply facility, which enables more reliable and efficient operation of the compressed air supply facility compared to previous methods, from the identification of leaks to their elimination. In particular, this method should be applicable to safety-related compressed air consumer circuits in vehicles. Another objective is to provide a compressed air supply facility suitable for performing this method.

[0010] The solution to this task is achieved using the method and compressed air supply facility characterized by the independent claims. Advantageous designs and improvements of the invention are defined in the dependent claims.

[0011] Therefore, the present invention first relates to a method for controlling a compressed air supply facility for a vehicle, wherein at least two compressed air consumer circuits are connected to the compressed air supply facility, wherein the compressed air supply facility has a compressed air preparation unit, a multi-loop protection valve at least partially electronically controllable associated with the compressed air preparation unit, an electronic control unit, and sensors suitable for monitoring leakage in the compressed air consumer circuits, wherein the compressed air consumer circuits can be connected to or disconnected from the compressed air supply by means of the control unit through the actuation of the multi-loop protection valves, and in this method, leakage monitoring of the compressed air consumer circuits is performed.

[0012] According to the present invention, the method is configured to quantify the identified leakage in the compressed air consumer circuit and evaluate it based on the amount of leakage found, and based on the evaluation of the amount of leakage, to partially or completely disconnect or remain disconnected from the compressed air supply unit of the unsealed compressed air consumer circuit involved.

[0013] This method is particularly advantageous when the compressed air consumer circuit to be evaluated is shut off by at least one associated valve, and the air pressure in the circuit is measured at two consecutive time points during a period in which no compressed air consumption occurs. If the air pressure in the shut-off compressed air consumer circuit still decreases, a leak can be easily and reliably inferred. The method then checks whether the leak is relatively large or relatively small, i.e., what the leakage rate is. The leakage rate can be determined, for example, as a compressed air loss of two liters per minute or, for example, 0.1 × 10⁻⁶ liters per minute. 5 Pressure drop of Pa.

[0014] Therefore, the method according to the invention is based on not only identifying the leak, but also accurately measuring the size of the leak, or the compressed air loss or pressure loss per unit time. This allows for the classification and assessment of the leak's extent or degree of defect.

[0015] Which compressed air losses or pressure losses due to leakage are tolerable in their respective compressed air consumer circuits depends, for example, on the purpose of the compressed air consumer circuit and on the type of vehicle in which the method and apparatus according to the invention are used. Thus, a relatively small pressure loss in a service brake circuit is less tolerable than the same pressure loss in a compressed air consumer circuit supplying an air spring assembly.

[0016] For example, regarding the service brake circuit, to avoid excessive compressed air loss, it can be configured so that the service brake circuit is only shut off relative to the compressed air supply when the leakage detected while the vehicle is stationary exceeds a predetermined lower leakage threshold. The lower leakage threshold could be, for example, 1 liter / minute to 10 liters / minute.

[0017] Furthermore, it can be configured such that, in the event of a leak in the vehicle's service brake circuit, the circuit remains connected to the compressed air supply as long as no other compressed air consumer is active, until a predetermined upper leakage threshold is exceeded. The vehicle's air spring system can, for example, be considered another compressed air consumer. The upper leakage threshold could, for example, be 20 liters per minute. Advantageously, this allows a defective, leaking service brake circuit to continue operating despite relatively high compressed air losses, preferably when all other compressed air consumers in the vehicle are not active (or alternatively, only comfort-related compressed air consumers may be deactivated).

[0018] According to another example, it can be configured such that when leakage in the vehicle's first service brake circuit exceeds a pre-defined leakage threshold, while the vehicle's second service brake circuit has no leakage, the first service brake circuit is disconnected from the compressed air supply only when the vehicle speed is below a pre-defined speed threshold. The speed threshold could be, for example, 30 km / h. Therefore, even with leakage in the first service brake circuit (even if it is only to a small extent), it can still be used to brake the vehicle at relatively high speeds.

[0019] Therefore, each individual compressed air consumer circuit can be assigned boundary values ​​regarding the acceptable leakage rate or the acceptable pressure loss.

[0020] According to another particularly advantageous improvement of the proposed invention, it can be configured such that, in the event of a relevant emergency or special operating condition of the vehicle, the unsealed, i.e., leaking, compressed air consumer circuit is temporarily reconnected to the compressed air supply facility.

[0021] Therefore, information about the size or degree of defect of a leak can be advantageously used to temporarily reconnect a defective compressed air consumer circuit, which has been disconnected from the compressed air supply due to a leak, to the compressed air supply in an emergency, when the quantified size of the leak allows for and thereby mitigates and / or overcomes the emergency more quickly. Furthermore, by quantifying the leak, energy used for operating the compressor during transport operations can be saved by shutting down or keeping the defective compressed air consumer circuit shut down outside of emergency or special circumstances.

[0022] The control method according to the invention can advantageously utilize existing pressure sensors. Furthermore, this control method can be applied to any compressed air consumer circuit that is electronically controlled by a multi-loop protection valve and is directly or indirectly equipped with a pressure sensor capable of continuously monitoring the pneumatic pressure in the compressed air consumer circuit. The control method is software-based. To operate this control method, only software matching of the existing electronic control unit of the compressed air supply facility with an electronically controllable multi-loop protection valve is required. Therefore, no additional equipment costs are required to apply this control method.

[0023] Advantageously, the method featuring the invention is performed at least after each vehicle restart. This ensures that the proper operational readiness of the compressed air supply system is knowable and guaranteed. However, the sufficient airtightness required for the operation of the compressed air supply system in emergency or special conditions can also be re-verified each time the compressed air consumer requests compressed air in real time.

[0024] In an improved embodiment of the method according to the invention, the method may be performed on the compressed air braking system of a vehicle, wherein, in the event of an emergency braking situation, a compressed air consumer circuit, which is identified as unsealed and disconnected from the compressed air supply and is in the form of a braking circuit, is temporarily reconnected to the compressed air supply system.

[0025] Therefore, this method can improve vehicle safety during emergency braking situations by supplying emergency compressed air to a non-sealed compressed air brake circuit before the vehicle can be taken to a repair shop for maintenance. In such a situation, at least one electrically driven compressor can temporarily provide its maximum possible delivery power, independent of the vehicle's drive motor speed, to effectively operate the service brakes of the defective compressed air brake circuit. The feasibility of emergency compressed air supply can be assessed based on the scale of the leak, or the compressed air loss per unit time. Emergency compressed air supply can be used in brake circuits that have been shut down due to leaks. The compressed air brake circuit in question can then be opened for a limited, relatively short period to support emergency braking and thus enable safer and faster braking.

[0026] Although the present invention is designed particularly for use in compressed air braking systems of vehicles, the method can also be advantageously used in other compressed air consumer circuits, such as in air spring systems for safety-related raising or lowering of the chassis.

[0027] A more specific improvement to the method can be configured such that, with the aid of a control unit and a computer program implemented in the control unit, and with the aid of a pressure sensor device and a multi-loop protection valve connected in a sensing manner to at least one compressed air consumer circuit, the following method steps are performed on the connected compressed air consumer circuit respectively:

[0028] - Measure the current aerodynamic pressure p_t1,act at the first time point t1.

[0029] - Calculate the expected compressed air consumption based on the compressed air consumer at the second time point t2 and the expected aerodynamic pressure p_t2,cal.

[0030] - Measure the current pressure p_t2,act at the second time point t2.

[0031] - Calculate the actual compressed air consumption during the monitoring time period Δt between the first time point t1 and the second time point t2.

[0032] - Compare the expected compressed air consumption with the actual compressed air consumption during the monitoring period Δt between the first time point t1 and the second time point t2.

[0033] - When a difference is found between the expected and actual compressed air consumption, a leak in the compressed air consumer circuit is identified, and the unsealed compressed air consumer circuit involved is disconnected from the compressed air supply facility.

[0034] - In the event of a leak, the leakage rate Q of the unsealed compressed air consumer circuit is determined based on the difference between the expected compressed air consumption and the actual compressed air consumption.

[0035] - When the known leakage rate Q is lower than a pre-defined leakage rate boundary value, the unsealed compressed air consumer circuit involved can be used for relevant emergency or special operating conditions.

[0036] While the application of the method characterized by the present invention is particularly simple when used with a consumer circuit where both the compressed air generator and the compressed air consumer are shut off, according to an embodiment of the method according to the invention, using the method flow just described, the expected compressed air consumption in a closed compressed air consumer circuit over a specific period can be compared with the actual compressed air consumption, and the leakage rate can be determined based on the difference between the mentioned compressed air consumption values. The expected value of compressed air consumption can be determined in advance, for example, during the development and testing of the respective vehicles or during the commissioning of the compressed air supply facility in the vehicle, and stored in the non-volatile memory of the electronic control unit. In this method, the expected information can be retrieved separately or derived in real time from the relevant technical specifications of the compressed air supply facility and / or the compressed air consumer circuit stored in the electronic memory. The actual compressed air consumption value can be calculated based on the pressure gradient measured during the period of interest, and is, for example, the amount of compressed air consumed for operating the brake actuator plus the total compressed air consumption due to leakage.

[0037] When the known leakage rate is less than a predetermined threshold, it is assumed that the compressed air consumer circuit involved can be advantageously used in emergency or dedicated operating conditions. For example, when one of the brake circuits of the compressed air braking system is identified as unsealed and disconnected from the compressed air supply for this reason, and an emergency braking signal is sent to the electronic control unit (ECU) via, for example, the vehicle's CAN bus network, then if the calculated leakage does not exceed the leakage rate threshold, the ECU can re-open the damaged brake circuit by outputting a control command. This enables a faster and safer braking process.

[0038] In an improved embodiment of the method according to the invention, a lower leakage rate boundary value Q_lim1 is pre-defined. When this lower leakage rate boundary value is exceeded, the unsealed compressed air consumer circuit is disconnected from the compressed air supply unit during normal vehicle operation, and connected to the compressed air supply unit in emergency operation or special operation. An upper leakage rate boundary value Q_lim2 is pre-defined. When this upper leakage rate boundary value is exceeded, the unsealed compressed air consumer circuit is continuously disconnected from the compressed air supply unit.

[0039] As already mentioned, in the method according to the invention, the calculated compressed air consumption is compared with the actual compressed air consumption in the compressed air consumer circuit with a leak, and the leakage rate within a defined time period is calculated based on the difference. If this difference, i.e., the known leakage rate, is greater than a specific lower leakage rate boundary value Q_lim1 pre-defined in the non-volatile data memory of the electronic control unit, the affected consumer circuit is disconnected from the compressed air supply by driving the multi-loop protection valve. Since the compressed air consumer circuit identified as unsealed is only disconnected from the compressed air supply when the known leakage rate exceeds the lower leakage rate boundary value Q_lim1, it is ensured that the compressed air consumer circuit is not unnecessarily disconnected from the compressed air supply even in the case of very small leaks or due to error tolerance in the identification and quantification of leaks.

[0040] The upper leakage rate boundary value Q_lim2 ensures that when the leakage is large enough that opening it would affect the operational safety and / or energy consumption of the compressed air supply facility in an unacceptable manner, the unsealed compressed air consumer circuit that has been disconnected from the compressed air supply unit will not be reopened.

[0041] Furthermore, according to another improvement of the method, it can be set that when the detected leakage of the compressed air consumer circuit exceeds the lower leakage rate boundary value Q_lim1, a first warning signal W1 is output, and when the detected leakage of the compressed air consumer circuit exceeds the upper leakage rate boundary value Q_lim2, a second warning signal W2, different from the first warning signal W1, is output.

[0042] The method according to the invention can also be operated with the same advantages on compressed air supply facilities that do not have multi-circuit protection valves and supply compressed air only to a single compressed air consumer circuit, wherein, according to the method, after a leak is found in the compressed air consumer circuit, the compressed air consumer circuit is disconnected from the compressed air supply unit, and wherein, in emergency or dedicated operating conditions of the vehicle, the single compressed air consumer circuit is reconnected to the compressed air supply facility and supplied with compressed air at least temporarily, despite the presence of a leak.

[0043] Therefore, this method improves vehicle safety in two ways. Firstly, it allows for safer emergency braking until the vehicle can be taken to a repair shop. Secondly, it not only warns the driver of a leak in the compressed air supply system but also indicates the size and significance of the leak. This information will prompt the driver to adjust their braking behavior if necessary and to immediately proceed to a repair shop.

[0044] To address equipment-related tasks, the present invention proposes a compressed air supply facility for a vehicle, connected to at least two compressed air consumer circuits. The compressed air supply facility includes a compressed air preparation unit, a multi-loop protection valve at least partially electronically controllable and associated with the compressed air preparation unit, an electronic control unit, and sensors suitable for monitoring leaks in the compressed air consumer circuits. The compressed air consumer circuits can be independently connected to or disconnected from the compressed air supply facility by means of the electronic control unit through the actuation of the multi-loop protection valve. Furthermore, the electronic control unit has a computer program configured to perform the method according to at least one of the method claims.

[0045] This invention enables, in a compressed air supply system with a controllable multi-loop protection valve, the precise measurement of the leak size or leakage amount per unit time, in addition to leak identification, through additional software functions implemented in the electronic control unit. When the quantified size of the identified leak allows for sufficient measurement for the desired vehicle operation purpose, this information can be advantageously used to temporarily resupply compressed air to a defective compressed air consumer circuit that has been previously disconnected from the compressed air supply unit, in emergency or dedicated operating conditions of the vehicle.

[0046] As already mentioned, the method can also be operated on a compressed air supply facility of a vehicle that connects only one compressed air consumer circuit. This compressed air supply facility includes a compressed air preparation unit, an electronically controllable valve associated with the compressed air preparation unit, an electronic control unit, and sensors suitable for monitoring leaks in the compressed air consumer circuit. The compressed air consumer circuit can be connected to or disconnected from the compressed air supply facility by means of the electronic control unit through the actuation of the valve. The compressed air supply facility is also characterized in that the electronic control unit has a computer program configured to perform the method according to at least one of the method claims.

[0047] Finally, the present invention also relates to a vehicle, such as a commercial vehicle or a passenger vehicle, having a compressed air supply facility constructed according to the device claims and capable of operating to perform the method according to at least one of the method claims. Attached Figure Description

[0048] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings. In the drawings:

[0049] Figure 1The diagram illustrates a schematic structure of a compressed air supply system for a vehicle with an electronically controllable multi-circuit protection valve, which can operate on the compressed air supply system according to the method of the invention.

[0050] Figure 2 Showing according to Figure 1 A graph showing the time curves of the pressure calculated and measured in the compressed air consumer circuit of the compressed air supply facility, and

[0051] Figure 3 A highly simplified diagram is shown for carrying out the method according to the invention. Detailed Implementation

[0052] thus, Figure 1 A schematic, extremely simplified wiring diagram of a compressed air supply system 1 for a vehicle, such as a commercial vehicle, is shown. The vehicle has a compressed air braking system, in which the connected compressed air consumer circuits V1, V2, V3, and V4 are independently and electronically controlled to connect to and disconnect from the compressed air supply system. Such compressed air supply systems are known in themselves and have been described, for example, in DE 195 15 895 A1 mentioned at the beginning. Therefore, the following description is limited to the essential components of such compressed air supply system 1 for carrying out the method according to the invention.

[0053] Figure 1 The compressed air supply facility 1 of the schematically illustrated motor vehicle includes, as a main structural component, a compressed air preparation unit 2, an electronically controllable multi-loop protection valve 3, and a sensor 4, in the form of a pressure sensor, for monitoring leaks in the compressed air consumer circuits V1, V2, V3, and V4, as well as an electronic control unit 5. The delivery line 6 of the compressed air supply facility 1 is connected to the output side of a compressor 7, which can be driven by a drive motor 8. In this example, the drive motor 8 is an electric motor, which is connected to the electronic control unit 5 via a first electrical line 9 and can be switched by the electronic control unit 5 to turn the compressor 7 on or off. Alternatively, the compressor 7 can be driven by a drive motor (not shown) in the vehicle's drive system via a switching clutch that can be driven electrically, pneumatically, or mechanically.

[0054] During transport operation, compressor 7 draws air from the environment and delivers it as compressed air to transport line 6. Compressed air preparation unit 2 has an air dryer 10, which is pneumatically connected to transport line 6 on the input side. A branch of transport line 6 has an electromagnetic vent valve 11 with an output-side silencer. This vent valve is electrically connected to electronic control unit 5 via a second electrical line 12 and can be switched by electronic control unit 5 to vent air from transport line 6. If necessary, vent valve 11 can be indirectly switched not directly by electronic control unit 5, but indirectly via another pressure-controlled switching valve (not shown) connected in between. Furthermore, in a known configuration, an air filter is pneumatically connected upstream of air dryer 10, and a check valve (not shown) is pneumatically connected downstream of air dryer 10. Additionally, air dryer 10 is connected on the output side to a device (not shown) for regeneration or dehumidification of the moisture absorbed in air dryer 10 using a counter-current method. Such a device is known in itself and is not important to the present invention, so it need not be described further here.

[0055] The transport line 6 is pneumatically connected on the output side to the pneumatic transport channel 13, which will also be described later. Currently, four compressed air consumer circuits V1, V2, V3, and V4 are pneumatically connected to the compressed air supply facility 1. For example, the first compressed air consumer circuit V1 is a first service brake circuit, the second compressed air consumer circuit V2 is a second service brake circuit, and the third compressed air consumer circuit V3 is a trailer and parking brake circuit of a compressed air brake facility (not shown). The fourth compressed air consumer circuit V4 may be an air spring compressed air circuit of an air spring facility (not shown). In addition, other compressed air consumer circuits (not shown) in the form of auxiliary consumer circuits may also be provided.

[0056] Corresponding to the number of connected compressed air consumer circuits, the pneumatic delivery channel 13 in this example is branched into four delivery branches 13.1, 13.2, 13.3, 13.4 to the four electromagnetic pilot valves 15, 16, 17, 18 of the multi-circuit protection valve 3. Each of these pilot valves 15, 16, 17, 18 is electrically connected to the electronic control unit 5 via electrical lines 19, 20, 21, 22. The electronic control unit 5 can individually switch each pilot valve 15, 16, 17, 18 to disconnect or pneumatically connect the corresponding compressed air consumer circuits V1, V2, V3, V4 to the delivery channel 13, and thus to the compressed air supply section. Electromagnetic pilot valves 15, 16, 17, and 18 are pneumatically connected on their output sides to the input ends of relief valves 27, 28, 29, and 30 via their respective supply pressure lines 23, 24, 25, and 26. Relief valves 27, 28, 29, and 30 are pneumatically connected on their output sides to the corresponding compressed air consumer circuits V1, V2, V3, and V4. Furthermore, each of the supply pressure lines 23, 24, 25, and 26 integrates pressure sensors 4.1, 4.2, 4.3, and 4.4 of the pressure sensor device 4. Each pressure sensor 4.1, 4.2, 4.3, and 4.4 is connected to the electronic control unit 5 via its respective electrical lines 31, 32, 33, and 34 to detect the pressure in each compressed air consumer circuit V1, V2, V3, and V4. The pressure in each compressed air consumer circuit V1, V2, V3, and V4 can be continuously known and monitored by the pressure sensor device 4 through the electronic control unit 5.

[0057] During the operation of compressor 7, the generated compressed air flows through compressed air preparation unit 2, and when the solenoid pilot valves 15, 16, 17, and 18 are switched to the open position and the opening pressure exceeds the opening pressure that causes relief valves 27, 28, 29, and 30 to open, it enters each compressed air consumer circuit V1, V2, V3, and V4 via delivery channel 13. The opening pressure can be pre-adjusted mechanically at each of the relief valves 27, 28, 29, and 30.

[0058] Figure 1The wiring shown is illustrative only. Therefore, in an alternative embodiment of the compressed air supply facility (not shown), the delivery pressure can reach the relief valves 27, 28, 29, and 30 directly via another delivery channel. In this embodiment, instead of the delivery pressure via the supply pressure line, the control pressure can be directed to the relief valves 27, 28, 29, and 30 via pilot valves 15, 16, 17, and 18 through an additional control pressure channel. The relief valves 27, 28, 29, and 30 can be switched to the cut-off position by connecting the control pressure at pilot valves 15, 16, 17, and 18, or released by disconnecting the control pressure, to open when the opening pressure is exceeded.

[0059] Regardless, the electromagnetic pilot valves 15, 16, 17, and 18 can, on the one hand, individually distribute the delivery pressure to the connected compressed air consumer circuits V1, V2, V3, and V4, and on the other hand, completely isolate them from the compressed air supply unit. For example, compressed air can be preferentially used to fill each compressed air consumer circuit. Upon detection of a leak, one or more affected compressed air consumer circuits can be completely disconnected from the compressed air supply unit. This ensures a sufficient supply of compressed air to intact compressed air consumer circuits, at least avoiding unnecessary increased energy consumption.

[0060] According to Figure 1 The method according to the invention can be performed on the compressed air supply facility 1. Other compressed air supply facilities known per se are also applicable. The important point is that there are electronically controllable multi-loop protection valves and electronic control units, as well as valves controllable by these electronic control units, suitable for performing leak monitoring in each connected compressed air consumer circuit, and for switching off compressed air consumer circuits identified as defective from the compressed air supply unit when needed, and conversely, for reconnecting compressed air consumer circuits disconnected due to leaks to the compressed air supply unit when needed. Thus, in exemplary embodiment according to... Figure 1 In the method performed on the compressed air supply facility 1, the four connected compressed air consumer circuits V1, V2, V3, and V4 are continuously monitored by means of pressure sensors 4.1, 4.2, 4.3, and 4.4 of the pressure sensor device 4.

[0061] Figure 2 Exemplary illustration in accordance with Figure 1Leakage monitoring is performed on the first service brake circuit V1. The service brake circuit V1 to be monitored is a closed circuit having at least one compressed air consumer of an electro-pneumatically operable brake cylinder in the form of a wheel brake of a vehicle wheel. First, a monitoring period Δt during vehicle operation is pre-defined in the computer program of the electronic control unit 5. Then, at a first time point t1 of the monitoring period Δt, the current pneumatic pressure p_t1,act is obtained. Simultaneously, the expected compressed air consumption of at least one brake cylinder during the monitoring period Δt is calculated based on data stored in the control unit 5 and / or based on data present on the data bus, and the value of the expected pneumatic pressure p_t2,cal at a second time point t2 is determined thereby. At the second time point t2, the current pneumatic pressure p_t2,act is obtained and compared with the calculated value of p_t2,cal.

[0062] according to Figure 2 The current pressure curve p(t)_act deviates from the calculated pressure curve p(t)_cal. Therefore, in the example shown, the actual pressure p_t2,act at the second time point t2 of the pressure detection is Δp lower than the expected pressure p_t2,cal. This indicates a leak in the first service brake circuit V1. Based on the actual pressure p_t2,act at the second time point t2, the actual compressed air consumption during the monitoring period Δt is calculated using an algorithm implemented in a computer program. The leakage rate Q of the compressed air loss is derived from the difference between the calculated and actual compressed air consumption, which can be signaled, for example, in units of m³ / s or liters per second. Thus, the leakage in the first service brake circuit V1 is quantified. In the second part of the method, the known leakage amount is now considered for further processing of the defective service brake circuit V1.

[0063] Figure 3 The method described illustrates the handling procedure performed when the first service brake circuit V1 is not sealed. Therefore, the lower leakage rate boundary value Q_lim1 and the upper leakage rate boundary value Q_lim2 are stored in the memory of the electronic control unit 5. If the known leakage rate Q of the service brake circuit V1 is within a first leakage range Q_0 below the lower leakage rate boundary value Q_lim1, it is assumed to be only a slight leakage, and the service brake circuit V1 remains connected to the compressed air supply facility 1 in an unchanged manner.

[0064] If the known leakage rate Q is within a second leakage range Q_1, defined by a lower leakage rate boundary value Q_lim1 and an upper leakage rate boundary value Q_lim2, it is assumed to be a small leakage that is still tolerable for operational purposes. In this regard, the driver will be informed via a first warning signal W1, which is displayed on a monitor in the driver's cab as a warning message and additionally accompanied by an audible signal. In this case, the service brake circuit V1 is initially disconnected from the compressed air supply by the actuation of the first pilot valve 15 by the electronic control unit 5. If an emergency situation, such as emergency braking, is detected in the electronic control unit 5, for example via the vehicle's CAN data bus, the service brake circuit V1 will be temporarily reconnected to the compressed air supply facility 1 by the actuation of the first pilot valve 15 to support emergency braking and bring the vehicle to a stop more quickly. This emergency compressed air supply can be performed multiple times until the vehicle is sent to a repair shop.

[0065] Conversely, if the known leakage rate Q is within a third leakage range Q_2 exceeding the upper leakage rate boundary value Q_lim2, the leakage is assumed to be unmanageable. The service brake circuit V1 will be permanently disconnected from the compressed air supply due to the actuation of the first pilot valve 15. The driver will receive a corresponding second warning signal W2, which informs the driver, in the form of an optical and acoustic warning message, that repairs should be taken to a repair shop as soon as possible.

[0066] Reference numerals (part of the specification)

[0067] 1 Compressed air supply facilities

[0068] 2 Compressed air preparation unit

[0069] 3. Multi-circuit protection valves, valves

[0070] 4. Sensors and pressure sensor devices used for leak monitoring

[0071] 4.1 First pressure sensor

[0072] 4.2 Second pressure sensor

[0073] 4.3 Third pressure sensor

[0074] 4.4 Fourth Pressure Sensor

[0075] 5 Electronic Control Unit

[0076] 6. Pneumatic transport lines

[0077] 7. Air compressor

[0078] 8 drive motors

[0079] 9 First power line

[0080] 10 Air dryers

[0081] 11. Vent valve

[0082] 12 Second power line

[0083] 13. Pneumatic transport channel

[0084] 13.1 First transport branch

[0085] 13.2 Second Transport Branch

[0086] 13.3 Third Transport Branch

[0087] 13.4 Fourth Transport Branch

[0088] 15. Electromagnetic first pilot valve

[0089] 16 Electromagnetic second pilot valve

[0090] 17. Electromagnetic third pilot valve

[0091] 18. Electromagnetic fourth pilot valve

[0092] 19 Third Power Line

[0093] 20 Fourth Power Line

[0094] 21. Fifth power line

[0095] 22. Sixth power line

[0096] 23 First Supply Pressure Line

[0097] 24 Second Supply Pressure Line

[0098] 25 Third Supply Pressure Line

[0099] 26. Fourth Supply Pressure Line

[0100] 27 First relief valve

[0101] 28 Second relief valve

[0102] 29 Third relief valve

[0103] 30 Fourth relief valve

[0104] 31. Seventh power line

[0105] 32. Eighth power line

[0106] 33 Ninth Power Line

[0107] 34. Tenth power line

[0108] p Pneumatic pressure in the compressed air consumer circuit

[0109] p_t1,act is the current aerodynamic pressure at the first time point.

[0110] p_t2,act is the current aerodynamic pressure at the second time point.

[0111] p_t2,cal is the expected pressure at the second time point calculated.

[0112] Δp pressure difference

[0113] p(t)_act Current pressure curve

[0114] The expected pressure curve calculated by p(t)_cal

[0115] Q Leakage rate

[0116] Q_0 First Leakage Range

[0117] Q_1 Second Leakage Range

[0118] Q_2 Third Leakage Range

[0119] Leakage rate boundary value under Q_lim1

[0120] Q_lim2 upper leakage rate boundary value

[0121] t time

[0122] Δt monitoring time period

[0123] t_1 is the first time point in the monitoring period.

[0124] t_2 is the second time point in the monitoring period.

[0125] V1 First Compressed Air Consumer Circuit, First Service Brake Circuit

[0126] V2 Second Compressed Air Consumer Circuit, Second Service Brake Circuit

[0127] V3 Third Compressed Air Consumer Circuit, Trailer and Parking Brake Circuit

[0128] V4 Fourth Compressed Air Consumer Circuit, Air Spring Circuit

[0129] W1 First Warning Signal, Warning Message

[0130] W2 Second Warning Signal, Warning Message

Claims

1. Method for controlling a compressed air supply installation (1) of a vehicle, to which at least two compressed air consumer circuits (V1, V2, V3, V4) are coupled, wherein, The compressed-air supply facility (1) has a compressed-air production unit (2), an at least partially electronically controllable multi-circuit protection valve (3) associated with the compressed-air production unit (2), an electronic control unit (5), and sensor means (4; 4.1, 4.2, 4.3, 4.4) suitable for monitoring the compressed-air consumer circuits (V1, V2, V3, V4) for leaks, wherein the compressed-air consumer circuits (V1, V2, V3, V4) can be connected or disconnected from the compressed-air supply by actuation of the multi-circuit protection valve (3) by means of the control unit (5), and in the method, monitoring the compressed-air consumer circuits (V1, V2, V3, V4) for leaks is carried out, characterized in that a detected amount of leakage in a compressed-air consumer circuit (V1, V2, V3, V4) is quantified and evaluated in dependence on the amount of leakage identified, and in dependence on the evaluation of the amount of leakage, the compressed-air consumer circuit (V1, V2, V3, V4) in question is disconnected or remains disconnected from the compressed-air supply facility (1) partially or completely.

2. The method of claim 1, wherein, In the service brake circuit of the vehicle, the service brake circuit is disconnected from the compressed-air supply facility (1) only when a detected leakage in the vehicle at rest exceeds a predefined lower leakage limit value.

3. The method of claim 1, wherein, In the event of a leakage in the service brake circuit of the vehicle, the service brake circuit remains connected to the compressed-air supply facility (1) as long as no other compressed-air consumer is active, until a predefined upper leakage limit value is exceeded.

4. The method of claim 1, wherein, When a leakage in a first service brake circuit of the vehicle exceeds a predefined leakage limit value, and a second service brake circuit of the vehicle has no leakage, the first service brake circuit is disconnected from the compressed-air supply facility (1) only when the vehicle speed is below a predefined speed limit value.

5. The method of claim 1, wherein, In the event of a relevant emergency operating condition or a special operating condition of the vehicle, a compressed-air consumer circuit (V1, V2, V3, V4) that is not sealed and has been disconnected from the compressed-air supply is temporarily connected again to the compressed-air supply facility (1).

6. The method according to any of the preceding claims, characterized in that, The method is carried out on a compressed-air brake facility of a vehicle, wherein, in the event of an emergency braking condition, a compressed-air consumer circuit (V1, V2, V3) in the form of a brake circuit that has been identified as not sealed and has been disconnected from the compressed-air supply is temporarily connected again to the compressed-air supply facility (1).

7. The method according to any of the preceding claims, characterized in that, By means of the control unit (5) and a computer program implemented in the control unit, and by means of a pressure sensor device (4) connected in a sensing manner to at least one compressed-air consumer circuit (V1, V2, V3, V4) and the multi-circuit protection valve (3), the following method steps are carried out on the connected compressed-air consumer circuits (V1, V2, V3, V4) respectively: - a current pneumatic pressure (p_t1,act) is measured at a first point in time (t1), - calculating a compressed-air consumption to be expected based on a compressed-air consumer at a second point in time (t2) a pneumatic pressure to be expected (p_t2, cal) at the second point in time (t2), - measuring a current pressure (p_t2, act) at the second point in time (t2), - calculating an actual compressed-air consumption in a monitoring period (Δt) between the first point in time (t1) and the second point in time (t2), - comparing the compressed-air consumption to be expected and the actual compressed-air consumption in the monitoring period (Δt) between the first point in time (t1) and the second point in time (t2), - in the event of a difference between the compressed-air consumption to be expected and the actual compressed-air consumption, identifying a leak in a compressed-air consumer circuit (V1, V2, V3, V4) and disconnecting the involved non-sealed compressed-air consumer circuit (V1, V2, V3, V4) from the compressed-air supply installation (1), - in the event of a leak being identified, determining a leak rate (Q) of the non-sealed compressed-air consumer circuit (V1, V2, V3, V4) from the difference between the compressed-air consumption to be expected and the actual compressed-air consumption, and - when the determined leak rate (Q) is below a pre-defined lower leak rate limit (Q_lim1), making the involved non-sealed compressed-air consumer circuit (V1, V2, V3, V4) available for a relevant emergency operating condition or a special operating condition.

8. The method according to any of the preceding claims, characterized in that, A pre-defined lower leak rate limit (Q_lim1) is exceeded when a non-sealed compressed-air consumer circuit (V1, V2, V3, V4) is disconnected from the compressed-air supply in normal operation of the vehicle and connected to the compressed-air supply in an emergency operating condition or a special operating condition, and a pre-defined upper leak rate limit (Q_lim2) is exceeded when the non-sealed compressed-air consumer circuit (V1, V2, V3, V4) is permanently disconnected from the compressed-air supply.

9. The method according to any of the preceding claims, characterized in that, A first warning signal (W1) is output when a leak in a compressed-air consumer circuit (V1, V2, V3, V4) is identified which exceeds a first lower leak rate limit (Q_lim1), and a second warning signal (W2) which is different from the first warning signal (W1) is output when a leak in a compressed-air consumer circuit (V1, V2, V3, V4) is identified which exceeds an upper leak rate limit (Q_lim2).

10. The method according to any of the preceding claims, characterized in that, The method is operated on a compressed-air supply installation which has no multi-circuit protection valve and which supplies compressed air to only one compressed-air consumer circuit, wherein, after a leak in this compressed-air consumer circuit has been ascertained, this compressed-air consumer circuit is shut off from the compressed-air supply, and wherein, in an emergency operating condition or a special operating condition of the vehicle, this one compressed-air consumer circuit is at least temporarily connected again to the compressed-air supply installation and supplied with compressed air, despite the leak.

11. Compressed air supply installation (1) for a vehicle, to which at least two compressed air consumer circuits (V1, V2, V3, V4) are coupled, and which has a compressed air production unit (2), an at least partially electronically controllable multi-circuit protection valve (3) which is associated with the compressed air production unit (2), an electronic control unit (5) and sensor means (4; 4.1, 4.2, 4.3, 4.4) which are suitable for leak monitoring of the compressed air consumer circuits (V1, V2, V3, V4), wherein The compressed air consumer circuits (V1, V2, V3, V4) can be connected to or disconnected from the compressed air supply installation (1 ) by means of the electronic control unit (5) by actuation of the multi-circuit protection valve (3) independently of one another, characterized in that the electronic control unit (5) has a computer program which is configured to carry out the method according to at least one of the method claims.

12. Compressed air supply installation (1) for a vehicle, with only one compressed air consumer circuit (VI) coupled to the compressed air supply installation, and with a compressed air production unit (2), an electronically controllable valve (3) associated with the compressed air production unit (2), an electronic control unit (5) and sensor means (4) suitable for leak monitoring of the compressed air consumer circuit (VI), wherein The compressed air consumer circuit (V1 ) can be connected to or disconnected from the compressed air supply installation (1 ) by means of the electronic control unit (5) by actuation of the valve (3), characterized in that the electronic control unit (5) has a computer program which is configured to carry out the method according to at least one of the method claims.

13. Vehicle, for example utility vehicle or passenger vehicle, having a compressed air supply installation (1 ) which is constructed according to the apparatus claim and can be operated for carrying out the method according to any one of the method claims.

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