Method for controlling a compressed air supply system of a 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 connected, wherein the compressed air supply system (1) has a compressed air preparation unit (2), an at least partially electronically controllable valve (3) assigned to the compressed air preparation unit, an electronic control unit (5) and also sensor means (4; 4.1, 4.2, 4.3, 4.4) suitable for leakage monitoring, wherein the at least one compressed air consumer circuit can be connected to or disconnected from the compressed air supply by means of the control unit by actuating the valve, and in which leakage monitoring of the compressed air consumer circuit / s takes place. According to the invention, a detected leak in the / a compressed air consumer circuit is quantified and evaluated according to the determined leakage quantity, and the relevant leaking compressed air consumer circuit is partially or completely disconnected or remains disconnected from the compressed air supply according to the evaluation of the leakage quantity.

Description

[0001] Method for controlling a compressed air supply system of a vehicle and compressed air supply system

[0002] The invention relates to a method for controlling a compressed air supply system of a vehicle, to which at least two compressed air consumer circuits are connected. The compressed air supply system comprises a compressed air treatment unit, an at least partially electronically controllable multi-circuit protection valve assigned to the compressed air treatment unit, an electronic control unit, and also sensor means suitable for leakage monitoring of the compressed air consumer circuits. The compressed air consumer circuits can be connected to or disconnected from the compressed air supply by means of the control unit by controlling the multi-circuit protection valve, and leakage monitoring of the compressed air consumer circuits is carried out. Furthermore, the invention relates to a compressed air supply system of a vehicle and a vehicle having such a compressed air supply system.

[0003] Electronically controllable compressed air supply systems for vehicles, especially commercial vehicles, typically feature a compressed air treatment unit with an air dryer, a multi-circuit protection valve, and an electronic control unit. The control unit is connected via sensor lines to pressure sensors for determining the supply pressures in the supply lines of the connected compressed air consumer circuits.

[0004] Using a switchable compressor, air is sucked in from the ambient air, compressed, and pumped via the air dryer into at least one main supply line. From the main supply line, several supply lines branch off to the compressed air consumer circuits via an overflow valve of the multi-circuit protection valve, each of which is connected to a pressure sensor to determine the respective supply pressure. In a compressed air supply system that supplies several compressed air consumer circuits, the multi-circuit protection valve has the function of independently routing the compressed air generated in the compressed air supply system to the respective compressed air consumer circuits and, in the event of a defective consumer circuit, automatically disconnecting it from the compressed air supply system so that the remaining consumer circuits can continue to be supplied with compressed air.For this purpose, the connections of the consumer circuits are each connected to the outlet connection of the air dryer of the compressed air treatment unit or to a compressed air supply line of another consumer circuit via an overflow valve located within the multi-circuit protection valve. An overflow valve opens when the pressure on the inlet side reaches or exceeds a set opening pressure and closes when the pressure on the outlet side reaches or falls below a closing pressure dependent on the opening pressure.

[0005] Beyond this purely pneumatically controlled mechanical functioning of the overflow valves, electronically controllable multi-circuit protection valves are already known, which can enable or block the supply to the overflow valves and / or the passage of compressed air through the overflow valves via electromagnetic valve means.

[0006] In order to monitor and maintain the functionality of a vehicle's compressed air supply system, and in particular the brake circuits of an air brake system, for as long as possible, it is important to detect any leaks within the compressed air supply system or the connected compressed air consumer circuits at an early stage. While it is relatively easy to detect a leak during a prolonged vehicle standstill, this is comparatively difficult during ferry operation due to the opposing influences of the compressor's delivery operation and the operational compressed air consumption in the compressed air consumer circuits.In order to detect a leak in the compressed air supply system or in one of the compressed air consumer circuits, leakage monitoring methods are known. These methods are usually based on using sensors to determine a delivery or supply pressure or the pressure gradient of a delivery or supply pressure and comparing it with a specified limit value. Depending on the comparison result, a warning signal can be issued if necessary. DE 10 2019 100 788 A1 discloses a method for leak monitoring in a compressed air supply system of a vehicle with a compressor connected to the system on the inlet side and with several compressed air consumer circuits connected to the compressor on the outlet side. In this known method, a supply pressure in a supply line of at least one compressed air consumer circuit is continuously determined using a pressure sensor during ferry operation.A pressure gradient is continuously calculated from at least two consecutively recorded pressure values ​​and the time difference between their recording and compared with a predetermined gradient limit value, which is set to a value less than zero. The known method is based on a monitoring period that includes several delivery pauses of a compressor in which compressed air is taken from the compressed air consumer circuits, as well as several delivery pauses in which no compressed air is taken from the compressed air consumer circuits. During the delivery pauses with compressed air consumption, the gradient limit value is not exceeded by the pressure gradient. During the delivery pauses without compressed air consumption, the gradient limit value is exceeded by the pressure gradient and assumes the value zero, provided there is no leak in the compressed air supply system or in one of the compressed air consumer circuits.If the pressure gradient never exceeds the gradient limit within the specified monitoring period, which includes several compressor delivery pauses, a leak is concluded and a warning signal is issued.

[0007] Furthermore, DE 195 15 895 A1 discloses a method for controlling a compressed air supply system of a vehicle with multiple compressed air consumer circuits. A programmable electronic control unit can control the supply of compressed air to the compressed air consumer circuits and the removal of compressed air from one compressed air consumer circuit for transfer to another compressed air consumer circuit or for the purpose of regenerating an air dryer. The electronic control unit monitors the pressure in the compressed air consumer circuits and disconnects them from the compressed air supply depending on a circuit-dependent, programmable limiting pressure. It connects the respective compressed air consumer circuit when the pressure falls below the limiting pressure by a programmed pressure difference.The known methods for controlling a vehicle's compressed air supply system and for leak monitoring have disadvantages and therefore require improvement. For example, if a certain pressure level is not reached or undershot in a compressed air consumer circuit, the relevant compressed air consumer circuit is automatically and permanently disconnected from the compressed air supply via the multi-circuit protection valve, and the driver is notified. The disadvantage of this is that the relevant compressed air consumer circuit and the connected compressed air consumers may then be unavailable until a workshop visit.

[0008] Against this background, the invention is based on the object of presenting a method for controlling a compressed air supply system of the type mentioned above, which, in the event of a detected leak, enables safer and more efficient operation of the compressed air supply system than previously possible until it is eliminated. In particular, this method should be suitable for use in safety-relevant compressed air consumer circuits of a vehicle. A further object was to present a compressed air supply system suitable for implementing such a method.

[0009] This object is achieved by a method and a compressed air supply system having the features of the independent claims. Advantageous embodiments and further developments of the invention are defined in the associated dependent claims.

[0010] The invention therefore initially relates to a method for controlling a compressed air supply system of a vehicle to which at least two compressed air consumer circuits are connected, wherein the compressed air supply system has a compressed air treatment unit, an at least partially electronically controllable multi-circuit protection valve assigned to the compressed air treatment unit, an electronic control unit and also sensor means suitable for leakage monitoring of the compressed air consumer circuits, wherein the compressed air consumer circuits can be connected to or separated from the compressed air supply by means of the control unit by controlling the multi-circuit protection valve, and in which leakage monitoring of the compressed air consumer circuits takes place.According to the invention, this method provides that a detected leak in a compressed air consumer circuit is quantified and evaluated as a function of the detected leak quantity, and that the leaking compressed air consumer circuit in question is partially or completely separated or remains separated from the compressed air supply as a function of the evaluation of the leak quantity.

[0011] This method is particularly advantageous when the compressed air consumer circuit to be assessed is shut off by at least one associated valve, and the air pressure in this consumer circuit is measured at two consecutive points in time during a period in which no compressed air consumption takes place in this consumer circuit. Should the air pressure in this shut-off compressed air consumer circuit nevertheless decrease, the presence of a leak can be easily and reliably determined. The method then checks whether this leak is comparatively large or comparatively small, i.e., what the leakage quantity is. The leakage quantity can be measured, for example, as a compressed air loss of two liters per minute or as a pressure drop of, for example, 0.1 x 10 5 Pa per minute can be determined.

[0012] The method according to the present invention is based on, in addition to detecting a leak, a precise measurement of the leak size, i.e., the compressed air loss or the pressure loss per unit of time. This allows an existing leak to be classified and evaluated in terms of its size or degree of damage.

[0013] Which leakage-related compressed air losses or pressure losses in the respective compressed air consumer circuit are tolerable depends, for example, on the purpose of this compressed air consumer circuit and the vehicle type in which the method and device according to the invention are used. For example, a comparatively small pressure loss in a service brake circuit will be less tolerable than the same pressure loss in a compressed air consumer circuit supplying an air suspension system.

[0014] For example, to prevent excessive compressed air loss, a service brake circuit can be shut off from the compressed air supply system only when the detected leakage while the vehicle is stationary exceeds a previously defined lower leakage limit. This lower leakage limit can be, for example, between 1 l / min and 10 l / min.

[0015] Furthermore, it can be provided, for example, that in the event of a leak in a service brake circuit of the vehicle, this circuit remains connected to the compressed air supply system until a previously defined upper leakage limit is exceeded, provided no other compressed air consumers are active. The other compressed air consumers can include, for example, the vehicle's air suspension system. The upper leakage limit can be, for example, 20 l / min. This advantageously ensures that the defective service brake circuit with a leak can continue to be used despite a comparatively high loss of compressed air, preferably when all other compressed air consumers of the vehicle are not active. It can also be provided that only comfort-relevant compressed air consumers may not be active.

[0016] According to another example, if a leak in a first service brake circuit of a vehicle exceeds a previously defined leakage limit, and a second service brake circuit of the vehicle does not exhibit a leak, the first service brake circuit is only disconnected from the compressed air supply system when the vehicle speed is lower than a previously defined speed limit. The speed limit may be 30 km / h, for example. Accordingly, despite the leak present there, the first service brake circuit can be used, albeit perhaps to a minor extent, to decelerate the vehicle at comparatively high speeds.

[0017] Accordingly, each individual compressed air consumer circuit can be assigned a limit value with regard to a just-allowable leakage rate or a just-allowable pressure loss.

[0018] According to another particularly advantageous development of the presented invention, it can be provided that the leaking compressed air consumer circuit, i.e., one exhibiting a leak, is temporarily reconnected to the compressed air supply system in a relevant emergency operating situation or special operating situation of the vehicle. Accordingly, the information about the size or damage of a leak can be advantageously used to temporarily reconnect a defective compressed air consumer circuit, previously disconnected from the compressed air supply system due to a leak, to the compressed air supply system in an emergency situation, if the quantified size of the detected leak allows this, thus mitigating the emergency situation and / or resolving it more quickly.In addition, by quantifying leaks, energy can be saved for operating the compressor during conveying operation by closing or remaining closed the defective compressed air consumer circuits outside of emergency or special situations.

[0019] The control method according to the invention can advantageously utilize existing pressure sensors. Furthermore, it can be applied to any compressed air consumer circuit that is electronically controllable by means of a multi-circuit protection valve and is directly or indirectly equipped with a pressure sensor that enables continuous determination of the pneumatic pressure in the compressed air consumer circuit. The control method is software-based. Its operation requires only a software adaptation of an existing electronic control unit of a compressed air supply system with an electronically controllable multi-circuit protection valve. Thus, no additional equipment is required for the application of this control method.

[0020] It is advantageous if the method incorporating the features of the invention is performed at least after each vehicle start-up. This allows the proper operational readiness of the compressed air supply system to be determined and ensured. However, sufficient pressure tightness of the compressed air supply system for its operation in an emergency or special situation can also be verified again each time a compressed air consumer requests compressed air.

[0021] In a further development of the method according to the invention, it can be provided that this is carried out on a vehicle's compressed air brake system, wherein a compressed air consumer circuit in the form of a brake circuit, which has been identified as leaking and disconnected from the compressed air supply, is temporarily reconnected to the compressed air supply system in an emergency braking situation. Accordingly, the method can be used to increase the safety of a vehicle in emergency braking situations by providing an emergency compressed air supply to an otherwise leaky compressed air brake circuit, as long as a workshop has not yet been reached. At least one electrically driven compressor can, regardless of the speed of a vehicle's drive engine, temporarily deliver its maximum possible delivery rate in such a situation in order to effectively actuate the service brake of the defective compressed air brake circuit.Based on the size of the leak, or the compressed air loss per unit of time, it is possible to assess whether an emergency compressed air supply is possible. The emergency compressed air supply can be used in brake circuits that have been closed due to a leak. The affected air brake circuit can then be opened for a limited, relatively short period of time to support emergency braking and thus enable safer and faster braking.

[0022] Although the invention is designed specifically for use in vehicle air brake systems, the method can also be advantageously used in other compressed air consumer circuits, for example, in an air suspension system for the safety-relevant raising or lowering of a chassis.

[0023] According to a more specific development of the method, it can be provided that the following method steps are carried out by means of the control unit and a computer program implemented therein, as well as by means of a pressure sensor device connected to at least one compressed air consumer circuit and the multi-circuit protection valve on the connected compressed air consumer circuit:

[0024] - Measuring the current pneumatic pressure p_t1 ,act at a first time t1 ,

[0025] - Calculating a pneumatic pressure p_t2,cal to be expected based on an expected compressed air consumption of compressed air consumers at a second time t2,

[0026] - Measuring the current pressure p_t2,act at the second time t2,

[0027] - Calculating the actual compressed air consumption in the monitoring period At between the first time t1 and the second time t2, - Comparing the expected compressed air consumption with the actual compressed air consumption in the monitoring period At between the first time t1 and the second time t2,

[0028] - Detection of a leak in a compressed air consumer circuit and isolation of the leaking compressed air consumer circuit from the compressed air supply system in the event of a difference between the expected compressed air consumption and the actual compressed air consumption,

[0029] - Determining a leakage rate Q of the leaking compressed air consumer circuit from the difference between the expected compressed air consumption and the actual compressed air consumption in the event of a detected leak, and

[0030] - Making the leaking compressed air consumer circuit in question available for a relevant emergency operating situation or special operating situation if the determined leakage rate Q falls below a specified leakage rate limit value.

[0031] Although the use of the method incorporating the features of the invention is particularly simple when applied to a consumer circuit that is isolated from both a compressed air generator and a compressed air consumer, the method sequence just described, according to one embodiment of the method according to the invention, can be used to compare an expected compressed air consumption over a specific period of time with an actual compressed air consumption in a closed compressed air consumer circuit, and to determine a leakage rate from the difference between the stated compressed air consumption values. The expected value of the compressed air consumption can be determined in advance in a suitable manner, for example, during the development and testing of the respective vehicle or during the application of the compressed air supply system in the vehicle, and stored in a non-volatile memory of the electronic control unit.The desired information can be retrieved during the process or derived from relevant specifications of the compressed air supply system and / or the compressed air consumer circuits stored in the electronic memory. The actual compressed air consumption value can be calculated from the measured pressure gradient during the period under consideration and is the sum of the compressed air volume consumed, for example, to operate a brake actuator, plus the compressed air consumption via the leak. If the determined leakage rate is less than a specified limit, it is assumed that the compressed air consumer circuit in question can be used advantageously in an emergency or special operating situation.For example, if one of the brake circuits of an air brake system is detected as leaking and has therefore been disconnected from the compressed air supply system, and an emergency braking signal is sent to the electronic control unit, for example, via the vehicle's CAN network, the electronic control unit can reopen the damaged brake circuit by issuing a control command if the calculated leakage does not exceed the leakage rate limit. This enables faster and safer braking.

[0032] In a further development of the method according to the invention, it can be provided that a lower leakage rate limit value Q_lim1 is specified, upon exceeding which a leaky compressed air consumer circuit is separated from the compressed air supply during normal operation of the vehicle and is connected to the compressed air supply in an emergency operating situation or special operating situation, and that an upper leakage rate limit value Q_lim2 is specified, upon exceeding which a leaky compressed air consumer circuit is permanently separated from the compressed air supply.

[0033] As already mentioned, in the method according to the invention, a calculated compressed air consumption is compared with an actual compressed air consumption in a compressed air consumer circuit exhibiting a leak, and a leakage rate for a defined period of time is calculated from the difference. If the difference, i.e., the determined leakage rate, is greater than a specific lower leakage rate limit value Q_lim1, previously defined in a non-volatile data memory of the electronic control unit, the relevant consumer circuit is isolated from the compressed air supply system by activating the multi-circuit protection valve.By only disconnecting a compressed air consumer circuit detected as leaking from the compressed air supply when the determined leakage rate has exceeded a lower leakage rate limit value Q_lim1, it is ensured that a compressed air consumer circuit is not unnecessarily disconnected from the compressed air supply in the event of a very small leak or due to an error tolerance in the detection and quantification of a leak.

[0034] The upper leakage rate limit value Q_lim2 ensures that a leaking compressed air consumer circuit that has already been separated from the compressed air supply is not reopened if the leakage is so large that the opening would have an unacceptable impact on the operational safety and / or energy consumption of the compressed air supply system.

[0035] Furthermore, according to another development of the method, it can be provided that a first warning signal W1 is output when a detected leakage of a compressed air consumer circuit has exceeded the lower leakage rate limit value Q_lim1, and that a second warning signal W2 different from the first warning signal W1 is output when a detected leakage of a compressed air consumer circuit has exceeded the upper leakage rate limit value Q_lim2.

[0036] The method according to the invention can also be operated with the same advantages on a compressed air supply system which does not have a multi-circuit protection valve and supplies only a single compressed air consumer circuit with compressed air, wherein according to the method, after a leak is detected in the compressed air consumer circuit, this is shut off from the compressed air supply, and wherein in an emergency operating situation or special operating situation of the vehicle, this single compressed air consumer circuit is at least temporarily reconnected to the compressed air supply system and supplied with compressed air despite the leakage present there.

[0037] Accordingly, the procedure can improve vehicle safety in two ways. Firstly, the procedure makes emergency braking safer before a workshop can be reached. Secondly, the procedure warns the driver not only of leaks in the compressed air supply system, but also of their size and relevance. This information alerts the driver to adjust their braking behavior if necessary and to visit a workshop immediately.

[0038] To achieve the device-related problem, the invention presents a compressed air supply system for a vehicle, to which at least two compressed air consumer circuits are connected, and which comprises a compressed air treatment unit, an at least partially electronically controllable multi-circuit protection valve assigned to the compressed air treatment unit, an electronic control unit, and also sensor means suitable for leakage monitoring of the compressed air consumer circuits. The compressed air consumer circuits can be connected to or disconnected from the compressed air supply system independently of one another by means of the electronic control unit by controlling the multi-circuit protection valve. Furthermore, the electronic control unit comprises a computer program designed to carry out the described method according to at least one of the method claims.

[0039] The present invention makes it possible, in a compressed air supply system with a controllable multi-circuit protection valve, to perform a precise measurement of the leak size or leakage quantity per unit of time beyond leak detection by implementing an additional software function in an electronic control unit. This information can be advantageously used to temporarily resupply a defective compressed air consumer circuit, previously disconnected from the compressed air supply, with compressed air in an emergency or special operating situation of the vehicle, if the quantified size of the detected leak permits this, i.e., is sufficient for the desired vehicle operational purpose.

[0040] As mentioned, the method can also be operated on a compressed air supply system of a vehicle to which only one compressed air consumer circuit is connected, wherein this compressed air supply system has a compressed air treatment unit, an electronically controllable valve assigned to the compressed air treatment unit, an electronic control unit, and also sensor means suitable for leakage monitoring of the compressed air consumer circuit. The compressed air consumer circuit can be connected to or disconnected from the compressed air supply system by means of the electronic control unit by controlling the valve. This compressed air supply system is also characterized in that the electronic control unit has a computer program designed to carry out the method according to at least one of the method claims, the features of which have been described.

[0041] Finally, the invention also relates to a vehicle, such as a commercial vehicle or a passenger car, with a compressed air supply system, which is constructed as described in accordance with the device claim and is operable to carry out a method according to one of the method claims. The invention is further explained below with reference to an exemplary embodiment shown in the accompanying drawing. The drawing shows

[0042] Fig. 1 shows a schematic structure of a compressed air supply system of a vehicle with an electronically controllable multi-circuit protection valve, on which a method according to the invention can be operated,

[0043] Fig. 2 is a diagram showing the time profiles of a calculated and a measured pressure in a compressed air consumer circuit of a compressed air supply system according to Fig. 1, and

[0044] Fig. 3 shows a highly simplified scheme for carrying out the method according to the invention.

[0045] Fig. 1 shows a highly simplified schematic circuit diagram of a compressed air supply system 1 of a vehicle, for example, a commercial vehicle, with a compressed air braking system, in which the connected compressed air consumer circuits V1, V2, V3, V4 can be connected to and disconnected from the compressed air supply system independently of one another under electronic control. Such a compressed air supply system is known per se and is described, for example, in the aforementioned DE 195 15 895 A1. The following description is therefore limited to the components of such a compressed air supply system 1 that are important for carrying out the method according to the invention.

[0046] The compressed air supply system 1 of a motor vehicle, shown schematically in Fig. 1, has as essential components a compressed air treatment unit 2, an electronically controllable multi-circuit protection valve 3 and sensor means 4 for leakage monitoring of compressed air consumer circuits V1, V2, V3, V4 in the form of a pressure sensor device, as well as an electronic control unit 5. A delivery line 6 of the compressed air supply system 1 is connected to the output side of a compressor 7, which can be driven by a drive motor 8. In the present example, a drive motor 8 is an electrical machine which is connected to the electronic control unit 5 via a first electrical line 9 and can be switched by the latter in order to switch a delivery operation of the compressor 7 on or off.Alternatively, the compressor 7 can be drive-connected to a drive motor in the vehicle's drive train via an electrically, pneumatically, or mechanically controllable clutch (not shown). During delivery operation, the compressor 7 draws in air from the environment and delivers it as compressed compressed air into the aforementioned delivery line 6. The compressed air treatment unit 2 has an air dryer 10, which is pneumatically connected to the delivery line 6 on the inlet side. An electromagnetic vent valve 11 with a silencer on the outlet side branches off from the delivery line 6. This valve is electrically connected to the electronic control unit 5 via a second electrical line 12 and can be switched by the electronic control unit 5 to vent the delivery line 6.If necessary, the vent valve 11 can be switched not directly via the electronic control unit 5, but indirectly via another intermediate pressure-controlled switching valve (not shown). Furthermore, an air filter is pneumatically connected upstream of the air dryer 10 in a conventional design, and a check valve is pneumatically connected downstream (not shown). Furthermore, the air dryer 10 is connected on the outlet side to a device (also not shown) for regenerating or dehumidifying moisture absorbed in the air dryer 10 using a countercurrent process. Such a device is known per se and is not essential to the invention, and therefore need not be described further here.

[0047] The delivery line 6 is pneumatically connected on the output side to a pneumatic delivery gallery 13, which will be described later. In the present case, four compressed air consumer circuits V1, V2, V3, V4 are pneumatically connected to the compressed air supply system 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 system (not shown). The fourth compressed air consumer circuit V4 can be an air spring circuit of an air spring system (not shown). In addition, further compressed air consumer circuits (not shown) can be provided in the form of auxiliary consumer circuits.

[0048] According to the number of connected compressed air consumer circuits, the pneumatic conveyor gallery 13 in the present example branches into four conveyor branches 13.1, 13.2, 13.3, 13.4 to 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 an electrical line 19, 20, 21, 22. The electronic control unit 5 can control each pilot valve

[0049] 15, 16, 17, 18 can be switched individually to separate the respective compressed air consumer circuit V1, V2, V3, V4 from the conveyor gallery 13 and thus from the compressed air supply, or to pneumatically connect it to it. The electromagnetic pilot valves 15, 16, 17, 18 are pneumatically connected on the output side via an assigned supply pressure line 23, 24, 25, 26 to the inlet of a respective overflow valve 27, 28, 29, 30. The overflow valves 27, 28, 29, 30 are pneumatically connected on the output side to the respective compressed air consumer circuit V1, V2, V3, V4. In addition, a pressure sensor 4.1, 4.2, 4.3, 4.4 of the pressure sensor device 4 is integrated into each of the supply pressure lines 23, 24, 25, 26. Each pressure sensor 4.1, 4.2, 4.3, 4.4 is connected to the electronic control unit 5 via an associated electrical line 31, 32, 33, 34 for determining the pressure of each compressed air consumer circuit V1, V2, V3, V4.The electronic control unit 5 can continuously determine and monitor the pressure in each compressed air consumer circuit V1, V2, V3, V4 by means of the pressure sensor device 4.

[0050] During the conveying operation of the compressor 7, the generated compressed air flows through the compressed air treatment unit 2 and reaches the individual compressed air consumer circuits V1, V2, V3, V4 via the conveying gallery 13 when the electromagnetic pilot valves 15,

[0051] 16, 17, 18 are switched to the open position and an opening pressure is exceeded, which opens the overflow valves 27, 28, 29, 30. The opening pressure can be mechanically adjusted in advance individually on each of the overflow valves 27, 28, 29, 30.

[0052] The circuit shown in Fig. 1 is only an example. In an alternative embodiment of a compressed air supply system (not shown), the delivery pressure can reach the overflow valves 27, 28, 29, 30 directly via a different delivery gallery. In this embodiment, a control pressure can be supplied to the overflow valves 27, 28, 29, 30 via the pilot valves 15, 16, 17, 18 via an additional control pressure gallery instead of the delivery pressure via supply pressure lines. The overflow valves 27, 28, 29, 30 can then each be switched to a blocking position by switching the control pressure at the pilot valves 15, 16, 17, 18, or released for opening when the opening pressure is exceeded by switching off the control pressure.The electromagnetic pilot valves 15, 16, 17, and 18 enable individual distribution of the delivery pressure to the connected compressed air consumer circuits V1, V2, V3, and V4, as well as complete isolation from the compressed air supply. For example, individual compressed air consumer circuits can be filled with compressed air on a priority basis. If a leak is detected, the defective compressed air consumer circuit(s) in question can be completely isolated before the compressed air supply. This ensures a sufficient compressed air supply to the intact compressed air consumer circuits. At the very least, unnecessarily increased energy consumption is avoided.

[0053] The method according to the invention can be carried out on the compressed air supply system 1 according to Fig. 1. Other known compressed air supply systems are also suitable. It is only important that an electronically controllable multi-circuit protection valve and an electronic control unit as well as valves that can be controlled thereby are present, which are suitable for carrying out leakage monitoring in each connected compressed air consumer circuit and, if necessary, for switchably disconnecting a compressed air consumer circuit identified as defective from the compressed air supply and, conversely, for reconnecting a compressed air consumer circuit that has been disconnected due to a leak to the compressed air supply if necessary. Accordingly, in the method carried out as an example on the compressed air supply system 1 according to Fig. 1, the four connected compressed air consumer circuits V1, V2, V3, V4 are monitored by means of the pressure sensors 4.1, 4.2, 4.3, 4.4 of the pressure sensor device 4 is constantly monitored.

[0054] Fig. 2 shows an example of leakage monitoring on the first service brake circuit V1 according to Fig. 1. The service brake circuit V1 to be monitored is a closed circuit with at least one compressed air consumer in the form of an electro-pneumatically actuated brake cylinder of a wheel brake of a vehicle wheel. First, a monitoring period Δt is specified in a computer program of the electronic control unit 5 during vehicle operation. Subsequently, the current pneumatic pressure p_t1,act is determined at the first time t1 of the monitoring period Δt. At the same time, an expected compressed air consumption of the at least one brake cylinder in the monitoring period Δt is calculated from data stored in the control unit 5 and / or from data available on a data bus, and from this the value of an expected pneumatic pressure p_t2,cal at the second time t2 is determined.At the second time t2, the current pneumatic pressure p_t2,act is determined and compared with the calculated value of the pneumatic pressure p_t2,cal.

[0055] According to Fig. 2, the current pressure curve p(t)_act deviates from the calculated pressure curve p(t)_cal. Accordingly, in the example shown, the actual pressure p_t2,act is lower than the expected pressure p_t2,cal by a difference Ap at the second time t2 of pressure detection. This indicates a leak in the first service brake circuit V1. From the actual pressure p_t2,act at the second time t2, the actual compressed air consumption in the monitoring period Δt is calculated using a calculation algorithm implemented in the computer program. The difference between the calculated and actual compressed air consumption results in a leakage rate Q of a compressed air loss, which can be expressed, for example, in units of m 3 / s or liters per second. This quantifies the leakage in the first service brake circuit V1. In a second part of the procedure, the determined leakage quantity is used for further treatment of the defective service brake circuit V1.

[0056] Fig. 3 shows the procedure according to the method in the case of a leaky first service brake circuit V1. Accordingly, a lower leakage rate limit value Q_lim1 and an upper leakage rate limit value Q_lim2 are stored in a memory of the electronic control unit 5. If the determined leakage rate Q of the service brake circuit V1 lies below the lower leakage rate limit value Q_lim1 in a first leakage range Q_0, a minor leak is assumed, and the service brake circuit V1 remains connected to the compressed air supply system 1 in an unchanged manner.

[0057] If the determined leakage rate Q lies within a second leakage range Q_1, which is limited by the lower leakage rate limit Q_lim1 and the upper leakage rate limit Q_lim2, a smaller leak is assumed that is still tolerable for an operationally relevant purpose. The driver is informed of this by a first warning signal W1, which appears, for example, as a warning message on a display in the driver's cab and is also signaled acoustically. In this case, the service brake circuit V1 is initially disconnected from the compressed air supply by actuating the first pilot valve 15 by the electronic control unit 5.In the event of an emergency situation, such as emergency braking, which is detected in the electronic control unit 5, for example, via a vehicle's CAN data bus, the service brake circuit V1 is temporarily reconnected to the compressed air supply system 1 by activating the first pilot valve 15 to support the emergency braking and bring the vehicle to a stop more quickly. Such an emergency compressed air supply can be performed several times until a workshop visit is necessary.

[0058] However, if the determined leakage rate Q lies within a third leakage range Q_2, which exceeds the upper leakage rate limit Q_lim2, it is assumed that the leakage is unmanageable. The service brake circuit V1 is permanently disconnected from the compressed air supply by activating the first pilot valve 15. The driver receives a corresponding second warning signal W2, which informs the driver in the form of a visual and acoustic warning that a visit to the workshop is required as soon as possible.

[0059] Reference symbol (part of the description)

[0060] 1 compressed air supply system

[0061] 2 compressed air treatment unit

[0062] 3 multi-circuit protection valve, valve

[0063] 4 Sensor means for leakage monitoring, pressure sensor device

[0064] 4.1 First pressure sensor

[0065] 4.2 Second pressure sensor

[0066] 4.3 Third pressure sensor

[0067] 4.4 Fourth pressure sensor

[0068] 5 Electronic control unit

[0069] 6 Pneumatic conveying line

[0070] 7 Compressor

[0071] 8 Drive motor

[0072] 9 First electrical line

[0073] 10 air dryers

[0074] 11 vent valve

[0075] 12 Second electrical line

[0076] 13 Pneumatic conveyor gallery

[0077] 13.1 First funding branch

[0078] 13.2 Second funding branch

[0079] 13.3 Third funding branch

[0080] 13.4 Fourth funding branch

[0081] 15 First electromagnetic pilot valve

[0082] 16 Second electromagnetic pilot valve

[0083] 17 Third electromagnetic pilot valve

[0084] 18 Fourth electromagnetic pilot valve

[0085] 19 Third electrical line

[0086] 20 Fourth electrical line

[0087] 21 Fifth electrical line

[0088] 22 Sixth electrical line

[0089] 23 First supply pressure line

[0090] 24 Second supply pressure line

[0091] 25 Third supply pressure line

[0092] 26 Fourth supply pressure line 27 First overflow valve

[0093] 28 Second overflow valve

[0094] 29 Third overflow valve

[0095] 30 Fourth overflow valve

[0096] 31 Seventh electrical line

[0097] 32 Eighth electrical line

[0098] 33 Ninth electrical line

[0099] 34 Tenth electrical line p Pneumatic pressure in a compressed air consumer circuit p_t1 ,act Current pneumatic pressure at a first point in time p_t2,act Current pneumatic pressure at a second point in time p_t2,cal Calculated expected pressure at a second point in time Ap Pressure difference p(t)_act Current pressure curve p(t)_cal Calculated, expected pressure curve

[0100] Q leakage rate

[0101] Q_0 First leakage area

[0102] Q_1 Second leakage area

[0103] Q_2 Third leakage area

[0104] Q_lim1 Lower leakage rate limit

[0105] Q_lim2 Upper leakage rate limit t time

[0106] At Monitoring period t_1 First time of the monitoring period t_2 Second time of the monitoring period

[0107] V1 First compressed air consumer circuit, first service brake circuit

[0108] V2 Second compressed air consumer circuit, second service brake circuit

[0109] V3 Third compressed air consumer circuit, trailer and parking brake circuit

[0110] V4 Fourth compressed air consumer circuit, air spring circuit

[0111] W1 First warning signal, warning message

[0112] W2 Second warning signal, warning message

Claims

Patent claims 1. Method for controlling a compressed air supply system (1) of a vehicle, to which at least two compressed air consumer circuits (V1, V2, V3, V4) are connected, wherein the compressed air supply system (1) comprises a compressed air treatment unit (2), an at least partially electronically controllable multi-circuit protection valve (3) assigned to the compressed air treatment unit (2), an electronic control unit (5) and also sensor means (4; 4.1, 4.2, 4.3, 4.4), wherein the compressed air consumer circuits (V1, V2, V3, V4) can be connected to or separated from the compressed air supply by means of the control unit (5) by controlling the multi-circuit protection valve (3), and in which leakage monitoring of the compressed air consumer circuits (V1, V2, V3, V4) takes place, characterized in that a detected leakage in a compressed air consumer circuit (V1, V2, V3, V4) is quantified and assessed as a function of the detected leakage quantity, and in that the leaking compressed air consumer circuit (V1, V2, V3, V4) in question is partially or completely separated or remains separated from the compressed air supply system (1) as a function of the assessment of the leakage quantity.

2. Method according to claim 1, characterized in that in the case of a service brake circuit of the vehicle, this is only separated from the compressed air supply system (1) when the detected leakage, when the vehicle is stationary, exceeds a previously defined lower leakage limit value.

3. Method according to claim 1, characterized in that in the event of a leak in a service brake circuit of the vehicle, this remains connected to the compressed air supply system (1) until a previously defined upper leakage limit value is exceeded, provided that no other compressed air consumers are active.

4. Method according to claim 1, characterized in that when a leak in a first service brake circuit of a vehicle exceeds a previously defined leakage limit value and a second service brake circuit of the vehicle has no leak, the first service brake circuit is only then disconnected from the compressed air supply. system (1) is disconnected when the vehicle speed is less than a previously defined speed limit.

5. Method according to claim 1, characterized in that the leaking compressed air consumer circuit (V1, V2, V3, V4) is temporarily reconnected to the compressed air supply system (1) in a relevant emergency operating situation or special operating situation of the vehicle.

6. Method according to one of the preceding claims, characterized in that it is carried out on a compressed air brake system of a vehicle, wherein a compressed air consumer circuit (V1, V2, V3) in the form of a brake circuit, which is detected as leaking and separated from the compressed air supply, is temporarily reconnected to the compressed air supply system (1) in an emergency braking situation.

7. Method according to one of the preceding claims, characterized in that by means of the control unit (5) and a computer program implemented therein and by means of a pressure sensor device (4) connected to at least one compressed air consumer circuit (V1, V2, V3, V4) and the multi-circuit protection valve (3) on the connected compressed air consumer circuit (V1, V2, V3, V4) the following method steps are carried out: - Measuring the current pneumatic pressure (p_t1 ,act) at a first time (t1), - Calculating a pneumatic pressure (p_t2,cal) to be expected based on an expected compressed air consumption of compressed air consumers at a second time (t2), - Measuring the current pressure (p_t2,act) at the second time (t2), - Calculating the actual compressed air consumption in the monitoring period (At) between the first time (t1) and the second time (t2), - comparing the expected compressed air consumption with the actual compressed air consumption in the monitoring period (At) between the first time (t1) and the second time (t2), - detecting a leak in a compressed air consumer circuit (V1, V2, V3, V4) and isolating the leaking compressed air consumer circuit (V1, V2, V3, V4) from the compressed air supply system (1) in the event of a difference being determined between the expected compressed air consumption and the actual compressed air consumption, - Determine a leakage rate (Q) of the leaking compressed air consumer circuit (V1, V2, V3, V4) from the difference between the expected compressed air consumption and the actual compressed air consumption when a leak is detected, and - Making the leaking compressed air consumer circuit in question available (V1, V2, V3, V4) for a relevant emergency operating situation or special operating situation if the determined leakage rate (Q) falls below a specified leakage rate limit value.

8. Method according to one of the preceding claims, characterized in that a lower leakage rate limit value (Q_lim1) is specified, upon which a leaky compressed air consumer circuit (V1, V2, V3, V4) is separated from the compressed air supply during normal operation of the vehicle and is connected to the compressed air supply in an emergency operating situation or special operating situation, and in that an upper leakage rate limit value (Q_lim2) is specified, upon which a leaky compressed air consumer circuit (V1, V2, V3, V4) is constantly separated from the compressed air supply when exceeded.

9. Method according to one of the preceding claims, characterized in that a first warning signal (W1) is output when a detected leakage of a compressed air consumer circuit (V1, V2, V3, V4) has exceeded the first lower leakage rate limit value (Q_lim1), and in that a second warning signal (W2) different from the first warning signal (W1) is output when a detected leakage of a compressed air consumer circuit (V1, V2, V3, V4) has exceeded the upper leakage rate limit value (Q_lim2).

10. Method according to one of the preceding claims, characterized in that it is operated on a compressed air supply system which does not have a multi-circuit protection valve and supplies only a single compressed air consumer circuit with compressed air, wherein after a leak is detected in the compressed air consumer circuit, this is shut off from the compressed air supply, and wherein in an emergency operating situation or special operating situation of the vehicle, this single compressed air consumer circuit is at least temporarily reconnected to the compressed air supply system and supplied with compressed air despite the leak present there.

11. Compressed air supply system (1) of a vehicle, to which at least two compressed air consumer circuits (V1, V2, V3, V4) are connected, and which comprises a compressed air treatment unit (2), an at least partially electronically controllable multi-circuit protection valve (3) assigned to the compressed air treatment unit (2), an electronic control unit (5) as well as for leakage monitoring of the compressed air consumer circuits (V1, V2, V3, V4) has suitable sensor means (4; 4.1, 4.2, 4.3, 4.4), wherein the compressed air consumer circuits (V1, V2, V3, V4) can be connected to or separated from the compressed air supply system (1) independently of one another by means of the electronic control unit (5) by controlling the multi-circuit protection valve (3), characterized in that the electronic control unit (5) has a computer program which is designed to carry out the method according to at least one of the method claims.

12. Compressed air supply system (1) of a vehicle, to which only one compressed air consumer circuit (V1) is connected, and which has a compressed air treatment unit (2), an electronically controllable valve (3) assigned to the compressed air treatment unit (2), an electronic control unit (5) and also sensor means (4) suitable for leakage monitoring of the compressed air consumer circuit (V1), wherein the compressed air consumer circuit (V1) can be connected to or separated from the compressed air supply system (1) by means of the electronic control unit (5) by controlling the valve (3), characterized in that the electronic control unit (5) has a computer program which is designed to carry out the method according to at least one of the method claims.

13. Vehicle, such as a commercial vehicle or passenger car, with a compressed air supply system (1) which is constructed according to the device claim and operable to carry out a method according to one of the method claims.

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