Consumer control device and control procedure

Abstract

Consumer control device (1), with a compressed air maintenance device (2) comprising the following components: - a proportional pressure control valve (14) which has a feed inlet (16) and a working outlet (17) and which can be electrically actuated, - a device inlet (6) designed for connection to an external compressed air source (P), which is connected via an inlet channel (11) to the feed inlet (16) of the proportional pressure regulating valve (14), - a device outlet (7) designed for connection to an external consumer device (A), which is connected via an outlet channel (22) to the working outlet (17) of the proportional pressure control valve (14), - Sensor means (20) at least in the form of a flow sensor (25) serving to measure the air flow occurring in the inlet channel (11) and / or outlet channel (22) and an outlet pressure sensor (24) serving to measure the outlet pressure (P2) prevailing in the outlet channel (22), - an internal electronic control unit (26) which is connected to both the proportional pressure control valve (14) and the sensor means (20) via a signal connection and which is designed to generate an electrical pressure control signal for the proportional pressure control valve (14) depending on the state values ​​of the compressed air measured by the sensor means (20), - wherein the proportional pressure control valve (14) can regulate the outlet pressure (P2) prevailing in the outlet channel (22) to different outlet pressure values ​​depending on the electrical pressure control signal applied to it, wherein it can be operated both in a working mode (AM) regulating the outlet pressure (P2) to a working pressure value (P2A) and in a holding mode (HM) regulating the outlet pressure (P2) to a lower holding pressure value (P2H) compared to the working pressure value (P2A), characterized in that - that a shut-off valve (8) connected to the internal electronic control unit (26) via a signal is inserted in the outlet channel (22) between the proportional pressure control valve (14) and the outlet pressure sensor (24), which can be switched by an electrical valve control signal from the internal electronic control unit (26) either into a release position (V1) allowing air to pass through the outlet channel (22) or into a shut-off position (V0) closing off the outlet channel (22), - wherein the internal electronic control unit (26) is designed to automatically switch the shut-off valve (8) from the enabling position (V1) to the shut-off position (V0) during the operating mode (AM) of the proportional pressure control valve (14) if the flow sensor (25) detects an air flow (Q) corresponding to or below a predetermined or predefinable cut-off flow limit (AW) for a predetermined or predefinable limit period (tG), - and wherein the internal electronic control unit (26) is further configured to automatically switch the shut-off valve (8) from the shut-off position (V0) back to the release position (V1) and to put the proportional pressure control valve (14) into holding mode (HM) when the outlet pressure sensor (24) detects an outlet pressure (P2) that is lower than the working pressure value (P2A) and corresponds to a predetermined or predefinable limit pressure value (P2G) during the shut-off position (V0) of the shut-off valve (8).

Description

[0001] The invention relates to a consumer control device with a compressed air maintenance device which has the following components: - a proportional pressure control valve which has a supply inlet and a working outlet and which can be electrically controlled for its operation, - a device inlet designed for connection to an external compressed air source, which is connected via an inlet channel to the supply inlet of the proportional pressure control valve, - a device outlet designed for connection to an external consumer device, which is connected via an outlet channel to the working outlet of the proportional pressure control valve, - sensor means at least in the form of a flow sensor for measuring the air flow occurring in the inlet channel and / or outlet channel and an outlet pressure sensor for measuring the outlet pressure prevailing in the outlet channel, - an internal electronic control unit which is signal-connected to both the proportional pressure control valve and the sensor means and which is designed to generate an electrical pressure control signal for the proportional pressure control valve depending on the state values ​​of the compressed air measured by the sensor means, - wherein the proportional pressure control valve can regulate the outlet pressure prevailing in the outlet channel to different outlet pressure values ​​depending on the electrical pressure control signal applied to it, wherein it can be operated both in a working mode regulating the outlet pressure to a working pressure value and in a holding mode regulating the outlet pressure to a holding pressure value lower than the working pressure value.

[0002] The invention further relates to a method for controlling the compressed air supply to a consumer device by means of a consumer control device which is designed in particular according to the aforementioned type.

[0003] A prior art device designed and usable in the aforementioned sense is known from EP 2 865 899 A1. This device is a consumer control device comprising a compressed air maintenance unit, to whose device outlet a consumer device to be supplied with compressed air can be connected. The compressed air maintenance unit is equipped with a proportional pressure control valve, which can be variably controlled by an internal electronic control unit with an electrical pressure control signal in order to provide a regulated outlet pressure on the outlet side. A flow sensor measures the air flow to the connected consumer device, while an outlet pressure sensor, which is also present, measures the outlet pressure of the compressed air supplied to the consumer device.In the known device, the proportional pressure regulator valve operates flow-dependently, either in a working mode or in a holding mode known as standby mode. In working mode, the connected consumer device is supplied with compressed air, with the outlet pressure corresponding to a working pressure value required for proper operation of the connected consumer device. If the air flow drops to a predefined shut-off flow limit, the proportional pressure regulator is switched to holding mode, in which the outlet pressure is reduced to a reduced holding pressure value, resulting in energy savings.

[0004] EP 2 728 205 A2 also discloses a consumer control device, which, however, uses a shut-off valve designed as a 2 / 2-way valve instead of a proportional pressure control valve. During normal operation of the consumer control device, the shut-off valve assumes a release position allowing unhindered air passage. If, under certain circumstances, air consumption in the downstream external consumer device or in the duct system leading to this consumer device is to be avoided, the shut-off valve can be switched to a shut-off position preventing air passage. This is particularly true if the connected consumer device is not operated for an extended period of time.

[0005] DE 10 2006 007 103 A1 describes a modular compressed air maintenance device featuring an on-off valve module with an electrically or manually operated shut-off valve device, which can be used to selectively block or open the flow of compressed air through a compressed air duct. A pressure control module is connected downstream of the on-off valve module.

[0006] From DE 20 2006 002 145 U1 a modular compressed air maintenance device is known which has a switch-on module equipped with an electrically or manually actuated shut-off valve device, followed by a pressure booster device with a pressure control unit.

[0007] In a consumer control device known from DE 10 2011 012 558 B3, a 3 / 3-way valve is provided instead of a proportional pressure control valve or a 2 / 2-way shut-off valve, with the aid of which a connected consumer device can not only be separated from an external compressed air source, but if necessary, a consumer-side venting can also be carried out.

[0008] The invention is based on the object of taking measures that enable an energetically favorable and at the same time trouble-free use of a consumer device operated with compressed air.

[0009] This task is solved in a consumer control device of the type mentioned above by - that an electrically controllable shut-off valve is inserted into the outlet channel between the proportional pressure control valve and the outlet pressure sensor, which is signal-linked to the internal electronic control unit and can be switched by an electrical valve control signal from the internal electronic control unit either into a release position that releases the outlet channel for air passage or into a shut-off position that blocks the outlet channel, - wherein the internal electronic control unit is designed such that it can automatically switch the shut-off valve from the release position to the shut-off position during the operating mode of the proportional pressure control valve if the flow sensor detects an air flow corresponding to or below a predetermined or predeterminable cut-off flow limit value over a predetermined or predeterminable limit period, - and wherein the internal electronic control unit is further designed such that it can also automatically switch the shut-off valve back from the shut-off position to the release position and put the proportional pressure control valve into the holding mode if the outlet pressure sensor detects an outlet pressure which is lower than the working pressure value and corresponds to a predetermined or predeterminable limit pressure value while the shut-off valve is in the shut-off position.

[0010] The object is also achieved in a method of the type mentioned at the outset for controlling the compressed air supply to a consumer device by means of a consumer control device by carrying out the following method steps: - the consumer device is supplied with compressed air at an outlet pressure through an electrically controlled proportional pressure control valve and an electrically controlled shut-off valve connected in series downstream of it, - the air flow through the proportional pressure control valve and the shut-off valve to the consumer device is measured, - furthermore, an outlet pressure of the compressed air to be supplied to the consumer device is measured downstream of the shut-off valve, - during a normal operating phase of the consumer control device in which the measured air flow is above a predetermined cut-off flow limit, the proportional pressure control valve is operated in a working mode and the shut-off valve is operated in a release position allowing the passage of air to the consumer device, whereby the proportional pressure control valve delivers compressed air regulated to a predetermined working pressure value to the shut-off valve during the working mode, - during the normal operating phase, the shut-off valve is switched from the release position to a shut-off position preventing air passage if the measured air flow during a predetermined limit period is not higher than a predetermined shut-off flow limit, whereby the consumer control device is then operated in a stand-by operating phase, - during the standby operating phase, the shut-off valve is switched back to the release position and the proportional pressure control valve is operated in a holding mode if the measured outlet pressure drops to a predetermined limit pressure value during the shut-off position of the shut-off valve, which is lower than the working pressure value, whereby the proportional pressure control valve outputs compressed air to the shut-off valve during the holding mode, regulated to a holding pressure value that is lower than the working pressure value.

[0011] The consumer control device according to the invention contains a compressed air maintenance device that has an electrically controllable proportional pressure control valve, with which the pressure referred to as the outlet pressure of the compressed air to be supplied to a connected external consumer device can be provided in a controlled manner. The compressed air maintenance device has an internal electronic control unit that can supply the proportional pressure control valve with a pressure control signal corresponding to the desired outlet pressure. In this way, the proportional pressure control valve can be selectively set to a working mode and a holding mode, wherein the provided outlet pressure has a working pressure value in the working mode and a holding pressure value that is lower than the working pressure value in the holding mode.Downstream of the proportional pressure control valve is an electrically actuated shut-off valve, which can also be actuated by the internal electronic control unit by supplying it with a corresponding electrical valve control signal. Depending on its position, the shut-off valve can either open an outlet channel connected to the proportional pressure control valve on the output side, allowing air to pass through, or close it to prevent air from passing through. The corresponding switching positions are referred to as the open position and the shut-off position. If the shut-off valve is in the shut-off position, a fluid channel running between it and the connected consumer device is separated from the proportional pressure control valve, and the air volume in the fluid channel is trapped.The current operating mode of the proportional pressure control valve does not affect the air supply to the consumer device when the shut-off valve is in the shut-off position.

[0012] The consumer control device can be operated in a normal operating phase in which the proportional pressure control valve is in the working mode and the shut-off valve is in the release position. The connected consumer device is then continuously supplied with compressed air, the outlet pressure of which corresponds to the working pressure value, which is, for example, 6 bar. If the air demand of the connected consumer device decreases to or below a predetermined or predeterminable limit, known as the shutdown flow limit, for a certain period of time, referred to as the limit period, the shut-off valve is switched to the shut-off position by the internal electronic control unit. The reduced air demand is usually a sign that the consumer device has come to a standstill, meaning that compressed air is no longer required, at least temporarily.In this context, switching to the shut-off position prevents compressed air, which is still at a relatively high working pressure, from being fed into the fluid line leading to the consumer device. The consumer control device is now in a standby operating phase.

[0013] A special feature of the device and method is that the outlet pressure at the consumer device cannot drop completely to atmospheric pressure, even during the standby operating phase. An outlet pressure sensor measuring the outlet pressure downstream of the shut-off valve provides the internal electronic control unit with the current outlet pressure values, so that the internal electronic control unit can switch the shut-off valve back to the release position when the outlet pressure has dropped to a predetermined or preset limit pressure value. At this point at the latest, the internal electronic control unit switches the operating mode of the proportional pressure control valve from work mode to hold mode. The mode change of the proportional pressure control valve to hold mode preferably occurs simultaneously with the shut-off valve switching back to the release position.Thus, the outlet pressure at the external consumer device is now kept constant at the reduced holding pressure value, which is, for example, 3 bar. The associated energy consumption is significantly lower than if the high working pressure value were constantly maintained. At the same time, the consumer device is supplied with a minimum pressure above atmospheric pressure, which prevents malfunctions and, if necessary, facilitates rapid restart of the paused consumer device. The holding pressure value can preferably be variably adjusted by the user of the consumer control device, enabling the best possible adaptation to the connected consumer device. The same applies appropriately to the cut-off flow limit.

[0014] The holding pressure limit may differ from the pressure limit that triggers the shut-off valve to switch. It may, for example, be slightly higher. However, the holding pressure value and the pressure limit are preferably equal.

[0015] In this description and in the claims, the term “flow” is used for simplicity as a substitute for the otherwise correct terms such as “volume flow”, “flow rate” or “flow rate” and refers to a flow quantity per unit of time.

[0016] Advantageous further developments of the invention emerge from the subclaims.

[0017] The shut-off valve is preferably a 2 / 2-way valve. It is preferably of the "normally open" type and spring-loaded into the release position. In particular, it only needs to be actuated with an electrical valve control signal to switch and maintain the shut-off position. This ensures that the air supply to the connected consumer device is not interrupted, even in the event of a malfunction-related failure of the electrical valve control signal.

[0018] The internal electronic control unit is preferably designed such that, when there is an increased air demand from the connected external consumer device, it can switch the proportional pressure control valve, which is currently in hold mode, into the work mode while the working valve remains unchanged in the release position. In this way, the consumer control device can be switched at short notice from the standby operating phase to the normal operating phase, if necessary. If the consumer control device is appropriately equipped, this switching process can be carried out automatically and depending on the flow rate. The air flow measured by the flow sensor can be used as a basis for this. This flow increases as the air demand of the consumer device increases, with the switching to the normal operating phase being commanded by the internal electronic control unit when the measured flow has risen to a switch-on flow limit value.Alternatively or additionally, the consumer control device can also be designed such that the switchover to the normal operating phase can be triggered by an external electrical signal, for example by an external electronic control device controlling the operating sequence of the external consumer device, by a sensor system assigned to the external consumer device and connected to the internal electronic control unit and / or by a simple manual actuation device.

[0019] The outlet pressure sensor is preferably designed separately from the proportional pressure control valve. However, it can also be integrated into the proportional pressure control valve.

[0020] It is advantageous if the compressed air maintenance unit is equipped with an inlet pressure sensor, known as an inlet pressure sensor. This sensor is connected to an inlet channel connected to the inlet of the proportional pressure control valve and measures the prevailing inlet pressure. This allows, for example, continuous monitoring of whether the desired system pressure is present at the correct level on the inlet side. Like the other sensors, the inlet pressure sensor is signal-connected to the internal electronic control unit.

[0021] At this point it should be mentioned that the flow sensor measuring the air flow to the external consumer device is preferably connected to the aforementioned inlet duct, but in principle can also be placed elsewhere and in particular can alternatively be connected to the outlet duct.

[0022] The internal electronic control unit is expediently not only capable of generating the pressure control signal and the valve control signal as required, but is in particular designed so that it can also additionally output at least one electrical diagnostic signal which can be generated with the cooperation of the sensor means, i.e. on the basis of measured values ​​detected by the sensor means.

[0023] For example, a diagnostic signal can be output if the flow sensor and / or a pressure sensor of the compressed air maintenance unit detects compressed air conditions that deviate from the values ​​expected or tolerable during normal operation. Deviating operating conditions can be due, for example, to leaks or malfunctions of components of the connected external consumer device.

[0024] The compressed air maintenance device can be directly equipped with optical display means and / or with acoustic warning means that can be activated on the basis of an electrical diagnostic signal generated by output means of the internal electronic control unit in order to indicate problematic operating conditions directly on site.

[0025] The internal electronic control unit expediently has comparator means in which actual information supplied by the sensor means is comparable with reference information stored in storage means of the internal electronic control unit, wherein the internal electronic control unit also has output means which are designed to output the electrical pressure control signal for the proportional pressure control valve and the electrical valve control signal for the shut-off valve depending on the comparison result of the comparator means.

[0026] The internal electronic control unit is in particular equipped with storage means in which data of various types, in particular measurement, control, diagnostic and / or analysis data, can be stored volatilely and / or remanently, i.e. permanently even in the event of a power failure.

[0027] The compressed air maintenance unit is preferably designed as a modular unit. The functional components of the unit are conveniently grouped into individual modules, which can be combined in various configurations depending on the desired level of equipment.

[0028] The proportional pressure control valve is expediently part of a first valve module, while the shut-off valve is part of a second valve module. The outlet pressure sensor is preferably part of a sensor module, and the internal electronic control unit is preferably part of a control module. The compressed air maintenance unit expediently also has at least one independent communication module equipped with at least one communication interface connected to the internal electronic control unit. In this way, it is also possible, in particular, to network at least one additional compressed air maintenance unit or other fluid power devices with the compressed air maintenance unit of the consumer control device.

[0029] Preferably, the compressed air maintenance device is equipped with one or more communication interfaces to which an external electronic control device, in particular acting as a higher-level control, and / or an electronic information reading device and / or an electronic information input device and / or at least one further external electronic device can be connected.

[0030] At least one communication interface is useful for integrating the compressed air maintenance unit into a modular, internally electrically networked system with a local bus system.

[0031] For example, at least one communication interface is provided, which is designed as a bus interface, particularly for serial data transfer. Such a bus interface can be used to network the internal electronic control unit with other electronic devices via a fieldbus.

[0032] At least one communication interface is conveniently designed as a digital or analog input or as a digital or analog output.

[0033] Communication with external devices is primarily wired, but can also be implemented wirelessly via appropriately designed communication interfaces.

[0034] In bus communication, any bus standards can be implemented.

[0035] At least one communication interface is expediently suitable for bidirectional signal transmission. Furthermore, at least one communication interface is expediently designed for the input and / or output of binary and / or analog signals. Such a communication interface is expediently present in addition to a communication interface designed as a bus interface.

[0036] To influence the operating behavior of the internal electronic control unit and / or the sensor means, the compressed air maintenance unit is expediently equipped with suitable input means. Such input means consist, for example, of at least one button and / or at least one switch. Additionally or alternatively, input means may also be provided to enable purely electrical data and / or signal input, for example, via a special operating device or via an external electronic control device that generally communicates with the compressed air maintenance unit. Such input means consist, in particular, of at least one electrical communication interface.

[0037] The equipment of the compressed air maintenance unit conveniently enables extensive monitoring and diagnostic functions such as comparative measurements, limit value monitoring and automatic and / or user-controlled consumption measurements.

[0038] Functions for measured value compression and data reduction are conveniently integrated into the compressed air maintenance unit, as are functions for measured value analysis or for carrying out statistical functions.

[0039] The integration of the internal electronic control unit into the compressed air maintenance unit has the advantage of enabling autonomous operation of the compressed air maintenance unit without the need for constant signal communication with networked devices or an external electronic control device, which significantly minimizes susceptibility to failure. Nevertheless, bus networking and / or connection to an external electronic control device are naturally advantageous for coordinating the operating behavior with other components of a system.

[0040] By selecting the appropriate equipment, the compressed air maintenance unit can be configured as a fieldbus-capable system with an electrical interface for system parameterization and the transmission of measurement and control data. Optional features for local operation and visualization, such as an optionally integrated display or a locally connectable display and control unit, are also possible.

[0041] The invention is explained in more detail below with reference to the accompanying drawings, which show: Fig. 1 shows a schematic representation of a preferred structure of the consumer control device according to the invention, and Fig. 2 is a diagram illustrating a preferred mode of operation of a consumer control device and in particular the Fig. 1 illustrated consumer control device.

[0042] The consumer control device 1 contains, as its main component, at least one compressed air maintenance unit 2, preferably designed as a self-supporting structural unit. The latter is expediently modular in design. The compressed air maintenance unit 2 can preferably be functionally expanded by attaching additional maintenance modules, one of which is indicated by a dot-dash line at 3. For example, a filter module and / or an air drying module and / or an air lubricator module can be provided as at least one additional maintenance module.

[0043] The compressed air maintenance unit 2 has a housing 5 that supports and / or accommodates the other components of the compressed air maintenance unit 2. The housing 5 is expediently designed in a modular manner.

[0044] On the outside of the device housing 5 are a device inlet 6 and a device outlet 7, each suitable for establishing a fluid connection. The device inlet 5 is designed to be connected to a compressed air source P via a fluid line referred to as a feed line 12. The image shows the state of such a compressed air source P connected to the device inlet 6.

[0045] The device outlet 7 is designed to connect a fluid line, referred to as the working line 13, leading to an external consumer device A. Shown is a state in which a consumer device A—for example, a machine having several fluid-operated working components, for example, fluid-operated drives—is connected to the device outlet 7.

[0046] The compressed air maintenance device 2 has an electrically controllable proportional pressure control valve 14. This proportional pressure control valve 14 is expediently housed inside the device housing 5 and is preferably a component of a first valve module 14a of the modular compressed air maintenance device 2.

[0047] The proportional pressure control valve 14 has a supply inlet 16 for the inlet of compressed air to be regulated in terms of pressure and a working outlet 17 for the output of compressed air regulated to a predetermined pressure level. It also expediently has a vent outlet 18 communicating with the atmosphere.

[0048] The compressed air maintenance unit has an electrical control input 21 to which an electrical pressure control signal can be fed, which specifies the setpoint for a regulator output pressure that can be tapped at the working output 17.

[0049] The proportional pressure control valve 14 expediently contains a control unit 15 in which an output pressure force based on the regulator output pressure is compared with a variably preset actuating force corresponding to the setpoint. Depending on the force ratio, the working output 17 is connected to the supply input 16 or to the vent output 18. The actuating force results, for example, from a spring whose preload can be changed by an electric motor, from an electromagnetically or electrodynamically generated force, or from a fluidic pressure force. The proportional pressure control valve 14 can, for example, be directly electrically actuated or electropneumatically pilot-controlled. The aforementioned electrical pressure control signal ensures the electrical actuation or control of the control unit 15 and specifies the setpoint.

[0050] The supply inlet 16 is continuously connected to the device inlet 6 via an internal inlet channel 11 of the compressed air maintenance unit 2. The working outlet 17 is connected to the device outlet 7 via an internal outlet channel 22 of the compressed air maintenance unit 2, at which an outlet pressure P2 can be tapped, which corresponds at least to the regulator outlet pressure when the outlet channel 22 is open. Thus, with the working channel 22 open, the proportional pressure control valve 14 is capable of regulating the outlet pressure P2 prevailing at the device outlet 7 to different outlet pressure values ​​depending on the electrical pressure control signal applied to its electrical control input 21.

[0051] When the outlet channel 22 is open, the proportional pressure control valve 14 ensures a constant compressed air connection between the compressed air source P and the consumer device A. In this case, an outlet pressure P2 is made available to the consumer device A at a level regulated to a constant value, regardless of the current air flow.

[0052] The compressed air maintenance device 2 further includes an electrically controlled shut-off valve 8. This shut-off valve 8 is integrated into the outlet channel 22. It has a valve inlet 8b, which is connected to the working outlet 17 of the proportional pressure control valve 14 via an inlet channel section 22a of the outlet channel 22. It also has a valve outlet 8c, which is connected to the device outlet 7 via an outlet channel section 22b of the outlet channel 22.

[0053] The shut-off valve 8 is preferably a switching valve. It can alternatively assume at least two switching positions, one of which is Fig. 1 is the release position shown and the other is a blocking position.

[0054] In the release position, the shut-off valve 8 opens a fluid connection between the inlet channel section 22a and the outlet channel section 22b, allowing air to pass through the outlet channel 22. In the shut-off position, the outlet channel 22 is blocked, preventing fluid from passing between the inlet channel section 22a and the outlet channel section 22b.

[0055] The respective switching position of the shut-off valve 8 can be specified by means of an electrical valve control signal that can be supplied to the shut-off valve 8 at an electrical control input 19. The shut-off valve 8 expediently has an electrically actuated drive device 9 that can be electrically actuated by means of the electrical valve control signal. The drive device 9 is, for example, of an electromagnetic type. The shut-off valve 8 is preferably a solenoid valve.

[0056] The shut-off valve 8 is expediently a 2 / 2-way valve. It is, in particular, of a monostable design and preloaded by spring means 10 into a switching position acting as the home position. This home position is present in particular when no electrical valve control signal is present at the electrical control input 19 of the shut-off valve 8. By applying the electrical valve control signal, a switching force can be generated that switches the shut-off valve 8 into the second switching position, overcoming the spring force of the spring means 10, and holds it in this second switching position until the electrical valve control signal is removed again.

[0057] Preferably, the shut-off valve is of the "Normally Open" type, with the basic position specified by the spring means 10 being the release position. Should the electrical valve control signal fail due to a malfunction, this results in the shut-off valve 8 assuming the release position, ensuring a compressed air supply to the consumer device A.

[0058] The shut-off valve 8 is expediently a component of a second valve module 8a of the modular compressed air maintenance unit 2. It is expediently detachably attached to the first valve module 14a equipped with the proportional pressure control valve 14.

[0059] The compressed air maintenance device 2 is equipped with sensor means 20 for detecting several state variables of the compressed air in the system.

[0060] The sensor means 20 contain a flow sensor 25 designed to measure the air flow Q of the compressed air flowing from the compressed air source P to the consumer device A. It is irrelevant at which point along the duct the flow measurement takes place. For example, the flow sensor 25 is connected to the inlet duct 11, but it could also be connected to the outlet duct 22.

[0061] The sensor means 20 also include a pressure sensor connected to the outlet channel 22 and therefore referred to as the outlet pressure sensor 24, which detects the outlet pressure P2 prevailing in the outlet channel section 22b and thus also the outlet pressure at the device outlet 7. The shut-off valve 8 is arranged in the outlet channel 22 between the proportional pressure control valve 14 and the outlet pressure sensor 24.

[0062] The outlet pressure sensor 24 is expediently part of a first sensor module 24a of the compressed air maintenance device 2, which is attached to the second valve module 8a on the side facing away from the first valve module 14a. The device outlet 7 is expediently located on the first sensor module 24a.

[0063] The flow sensor 25 is expediently a component of a second sensor module 25a of the compressed air maintenance device 2. The second sensor module 25a is expediently attached to the first valve module 14a on the side facing away from the second valve module 8a. The device inlet 6 is preferably located on the second sensor module 25a.

[0064] Optionally and preferably, the sensor means 20 also contain a further pressure sensor connected to the intake channel 11 and therefore referred to as the intake pressure sensor 31. The intake pressure sensor 31 is capable of measuring the air pressure prevailing in the intake channel 11, which is consequently also referred to as the intake pressure.

[0065] The compressed air maintenance device 2 contains an internal electronic control unit 26, preferably housed inside the device housing 5, which is equipped with at least one microprocessor or microcontroller. For simplicity, it will be referred to hereinafter as the "internal control unit 26." The internal control unit 26 is preferably a component of a control module 26a of the compressed air maintenance device 2.

[0066] The internal control unit 26 takes over the electrical control of the proportional pressure control valve 14 and the shut-off valve 8, taking into account the measured values ​​supplied to it by the sensor means 20.

[0067] The internal control unit 26 is signal- and electrically connected via internal electrical signal lines 27 of the compressed air maintenance unit 2 to the electrical control input 21 of the proportional pressure control valve 14, to the electrical control input 19 of the shut-off valve 8, to the flow sensor 25, to the outlet pressure sensor 24, and to the optional inlet pressure sensor 31. The internal control unit 26 can receive electrical pressure measurements and flow measurements from the sensor means 20 and can output an electrical pressure control signal to the proportional pressure control valve 14 and an electrical valve control signal to the shut-off valve 8. Preferably, the internal control unit 26 can also output electrical diagnostic signals, which will be discussed later.

[0068] References to “one” electrical pressure control signal and “one” electrical valve control signal should be understood to mean that each may also refer to multiple signals.

[0069] The proportional pressure control valve 14 can be operated in two different operating modes, between which it can be switched. One operating mode is a working mode that is set when the consumer device A is in operation and in which the outlet pressure P2 can be regulated to a predetermined and, in particular, variably preset working pressure value P2A, for example, to 6 bar. This desired working pressure value P2A is stored as a reference value in the internal control unit 26 and can conveniently be entered and / or modified externally as needed for the specific application.

[0070] Another operating mode of the proportional pressure control valve 14 is a holding mode, in which the outlet pressure P2 can be regulated to a holding pressure value P2H that is lower than the working pressure value P2A. This holding pressure value P2H is, for example, 3 bar. The desired holding pressure value P2H is also stored as a reference value in the internal control unit 26 and can conveniently be entered and / or modified externally as needed for specific applications.

[0071] The respective operating mode of the proportional pressure control valve 14 can be specified by the electrical pressure control signal supplied by the internal control unit 26.

[0072] The compressed air maintenance device 2 is expediently equipped with an electrical interface, referred to below as the first communication interface 28 for ease of differentiation, which enables signal communication between the internal control unit 26 and an external electronic control device 23. The latter is expediently a component of the consumer control device 1, but is arranged, in particular, remotely from the compressed air maintenance device 2. The electronic control device 23 expediently serves to operationally control the consumer device A. A schematically indicated signal connection 23a is provided for this purpose.

[0073] The first communication interface 28 is arranged, in particular, on an outer side of the device housing 5 and is expediently connected to the internal control unit 26 via internal electrical conductors 32. The first communication interface 28 is preferably electromechanical and, in particular, designed as a plug-in interface or plug-in connection device, so that a signal cable 33 (only schematically indicated) can be connected, in particular detachably, to establish a connection to the external electronic control device 23.

[0074] The first communication interface 28 is preferably a bus interface capable of transmitting serial bus signals between the internal control unit 26 and the external electronic control device 23. The external signal cable 33, like the internal electrical conductors 32, can be implemented in the form of a serial bus system.

[0075] Alternatively, the first communication interface 28 can also be designed as a wireless interface, in particular to enable communication with the external electronic control device 23 via radio signals. The first communication interface 28 is expediently located on the control module 26a.

[0076] The internal control unit 26 preferably has electronic storage means 34, comparator means 35 and output means 36. In the storage means 34, for example, pressure values ​​relating to the outlet pressure measured by the outlet pressure sensor 24, further flow values ​​of the flow rate detected by the flow sensor 25 and, if appropriate, also pressure values ​​relating to the inlet pressure measured by the inlet pressure sensor 31 can be stored as reference information and preferably also as actual information.

[0077] In particular, a switch-off flow limit value AW, a limit pressure value P2G and a holding pressure value P2H can be stored in the storage means, which can be used for an advantageous operation of the consumer control device 1.

[0078] The comparator means 35 are capable of comparing stored reference information with, in particular, temporarily stored or directly measured actual information. The output means 36 are capable of outputting the electrical pressure signal for the proportional pressure control valve 14 and the electrical valve control signal for the shut-off valve 8 depending on the comparison result determined by the comparator means 35.

[0079] Preferably, the output means 36 are also capable of outputting at least one electrical diagnostic signal that can be used in another way.

[0080] The electrical pressure control signal for the proportional pressure control valve 14 is output during a normal operating phase of the consumer control device 1 based on a comparison of the measured air flow Q with the cut-off flow limit value AW. Based on this comparison, the proportional pressure control valve 14 is switched from the working mode to the holding mode.

[0081] This occurs automatically without external intervention by the electrical pressure control signal generated based on the comparison result.

[0082] In an optional embodiment of the consumer control device 1, a switch-on flow limit value EW can also be stored in the storage means 34. Based on a comparison of the measured air flow with the stored switch-on flow limit value EW, an electrical pressure control signal can be generated that switches the proportional pressure control valve 14 back from the holding mode to the working mode.

[0083] Preferably, the output means 36 of the internal control unit 26 also output an electrical diagnostic signal to the first communication interface 28, from where it can be transmitted to the external electronic control device 23 for further processing as required.

[0084] At least one electrical diagnostic signal can also be fed to optionally present optical display means 37 of the compressed air maintenance device 2 in order to visualize it in any desired manner.

[0085] The compressed air maintenance device 2 can further be equipped with acoustic warning means 38, indicated only by dashed lines, for example a buzzer, so that an acoustic warning signal can be emitted on site upon receipt of a corresponding electrical signal.

[0086] During its operation, the internal control unit 26 can receive and process measurement signals originating from the sensor means 20 as actual information. In this way, the internal control unit 26 receives time-dependent current values ​​of the air flow Q and the outlet pressure P2, as well as, if applicable, the inlet pressure, as actual information. The internal control unit 26 can be configured to output this actual information electrically or visually at the first communication interface 28 and / or at the optical display means 37.

[0087] During operation of the consumer control device 1, the internal control unit 26 can expediently generate at least one electrical diagnostic signal from a comparison between measured actual information and stored reference information, which provides information about the energy situation of the connected consumer device A.

[0088] For example, to monitor the air flow Q, actual information on the air flow Q can be recorded only once or multiple times, whereby actual information can be recorded multiple times, in particular at regular intervals.

[0089] The diagram below shows the Fig. 2 explains a preferred method sequence for controlling the compressed air supply to the consumer device A using the exemplary consumer control device 1. The diagram has three sections shown one above the other, with the uppermost section illustrating the course of the outlet pressure P2 over time t, the lower section illustrating the air flow Q over time t, and the middle section illustrating the switching position VA of the shut-off valve 8 over time t.

[0090] The illustrated process sequence begins with a normal operating phase NBP of the consumer control device 1. During this normal operating phase NBP, the proportional pressure control valve is in the AM operating mode and the shut-off valve 8 is in the release position V1. Accordingly, compressed air with a certain air flow rate Q, which may fluctuate, flows through the compressed air maintenance unit 2 to the external consumer device A, which has a corresponding air consumption. The outlet pressure P2 of the compressed air supplied to the consumer device A corresponds to the working pressure value P2A set by the proportional pressure control valve 14.

[0091] At least during the normal operating phase NBP, the air flow Q is continuously measured by the flow sensor 25 and transmitted as actual information to the internal control unit 26. There, a constant comparison with the stored switch-off flow limit value AW takes place. If the flow sensor 25 detects a reduced flow value corresponding to or below the switch-off flow limit value over a predetermined and, in particular, externally predeterminable limit period tG, this is interpreted to mean that there is no longer any operationally relevant air consumption by the consumer device A. The internal control unit 26 thus generates a valve control signal fed to the shut-off valve 8, by which the shut-off valve 8 is switched from the release position V1 to the shut-off position V0.This initiates a standby operating phase SBP of the consumer control device 1, in which the output channel section 22b of the outlet channel 22 is separated from the pressure source P and the compressed air located in the channel system between the shut-off valve 8 and the consumer device A is trapped. This saves energy during an operational break of the consumer device A.

[0092] As long as the shut-off valve 8 assumes the shut-off position V0 during this standby operating phase SBP, the pressure setting of the proportional pressure control valve 14 is essentially irrelevant. However, as long as the outlet pressure P2 detected by the outlet pressure sensor 24 is above the limit pressure value P2G, it is advantageous to leave the proportional pressure control valve 14 in the AM operating mode.

[0093] In particular, depending on the quality of the duct network connected to the shut-off valve 8 and the presence or absence of still active small consumers of the consumer device A, during the standby operating phase SBP, either no pressure drop occurs or a greater or lesser pressure drop occurs in the outlet duct section 22b blocked off from the device inlet 6. The duration of the air shut-off by the shut-off valve 8 also influences the magnitude of the pressure drop.

[0094] If the outlet pressure P2 drops during the standby operating phase SBP to the specified limit pressure value P2G, which is shown in the upper section of the diagram of the Fig. 2 is visualized by a falling characteristic curve branch 52, the shut-off valve 8 is switched back to the release position V1 by the internal control unit 26. This occurs, for example, by removing the electrical valve control signal that was present until then due to the force predominant spring means 10. As a result, the outlet channel 22 is again free for compressed air to flow through.

[0095] When the shut-off valve 8 is switched back from the shut-off position V0 to the release position V1, the proportional pressure control valve 14 is switched from the AM operating mode to the HM holding mode by the internal control unit 26. If the internal control unit 26 is programmed to switch the proportional pressure control valve 14 to the holding mode at the end of the normal operating phase NBP, the corresponding switching when the limit pressure value P2G is reached is omitted.

[0096] Thus, the remaining section of the standby operating phase SBP runs with the shut-off valve 8 in the release position V1 and with the proportional pressure control valve 14 in the holding mode HM. This prevents the supply line to the consumer device A or the consumer device A itself from becoming depressurized. A minimum air pressure is constantly present, which corresponds to the holding pressure value P2H specified by the proportional pressure control valve 14. In the upper section of the diagram of the Fig. 2 this is visualized by a horizontal characteristic curve branch 53.

[0097] This prevents impairments or damage to consumer device A due to insufficient pressure. Compared to a situation in which the outlet pressure P2 is maintained at the working pressure value P2A, significant energy savings are also achieved.

[0098] Preferably, the holding pressure value P2H provided by the proportional pressure control valve 14 during the holding mode corresponds to the limit pressure value P2G that causes the shut-off valve 8 to switch from the release position V1 to the shut-off position V0. However, different pressure settings can also be made.

[0099] When the consumer device A returns to normal compressed air demand, for example, because the consumer device A is restarted after a break in operation, the internal control unit 26 switches the consumer control device 1 back from the standby operating phase SBP to the normal operating phase NBP. This means that the shut-off valve 8 continues to be held in the release position V1, but the proportional pressure control valve 14 is switched back from the holding mode HM to the working mode AM. This supplies the consumer device A with compressed air again, the outlet pressure P2 of which corresponds to the regulated working pressure value P2A. The initial pressure increase when switching from the holding mode HM to the working mode AM is shown in the upper section of the diagram of the Fig. 2 is visualized by a rising characteristic curve branch 54.

[0100] The switchover from the standby operating phase SBP to the normal operating phase NBP is triggered, for example, by a corresponding electrical switchover signal that the external electronic control device 23 transmits to the internal control unit 26 via the first communication interface 28 based on the operating situation of the consumer device A connected to it. The consumer control device 1 can also be designed for manual input of the corresponding switchover signal.

[0101] Additionally or alternatively, the consumer control device 1 can also be designed such that, in the event of an increased air demand from the connected external consumer device A, a purely flow-dependent switchover from the standby operating phase SBP to the normal operating phase NBP is initiated. For this purpose, during the standby operating phase SBP, a constant comparison of the air flow Q measured by the flow sensor 25 with the switch-on flow limit value EW stored as a reference value takes place. If the measured air flow Q increases to the switch-on flow limit value EW, this is interpreted as meaning that the consumer device A has resumed normal operation, so that the internal control unit 26 automatically and without an external switchover signal initiates the switchover from the standby operating phase SBP to the normal operating phase NBP. This mode of operation is shown in the diagram of the Fig. 2 illustrated.

[0102] In the upper section of the Fig. In Figure 2, a dashed horizontal characteristic curve branch 55 illustrates an operating mode that occurs when no pressure drop occurs on the part of the outlet pressure P2 during the standby operating phase. The internal control unit 26 then has no reason to switch the shut-off valve 8 to the release position V1 during the standby operating phase SBP. The latter then occurs according to the diagram in the middle section of the Fig. 2 dashed characteristic branch 57 only when the consumer control device 1 is switched back to the normal operating phase NBP.

[0103] In such an operating sequence, it is advantageous if the proportional pressure control valve 14 constantly remains in the AM operating mode, so that during the transition from the stand-by operating phase SBP to the normal operating phase NBP, no increase in the outlet pressure P2 is required.

[0104] Preferably, the threshold period tG, which specifies a switching delay between the normal operating phase (NBP) and the standby operating phase (SBP), can be set externally. This allows the switching sensitivity to be adjusted as needed.

[0105] The compressed air maintenance device 2 is preferably equipped with input means 42 which enable activation and / or influencing and / or parameterization of the operating behavior of the internal electronic control unit 26 and preferably also of the sensor means 20.

[0106] The input means 42 are designed, for example, in the form of an arrangement of keys and / or switches 42a and / or for electronic input. In the exemplary embodiment, the electrical interface formed by the first communication interface 28 can be used for electronic input; this interface is a bus interface, with the external electronic control device 23 being usable as an information input device. The bus interface can, for example, conform to the I / O-Link standard.

[0107] By way of example, the compressed air maintenance device 2 is equipped with a further, second communication interface 29, which can be used as a diagnostic interface and to which, for example, an electronic information reader 46 of the consumer control device 1 can be connected at least temporarily. Such an information reader 46 enables, for example, the reading of measured actual information, in particular in conjunction with the associated reference information. The second communication interface 29 is, for example, an Ethernet interface or another digital output. It is located in particular on the preferably present control module 26a.

[0108] As a further input means 42 for electronic data input for system configuration, the compressed air maintenance device 2 includes, by way of example, a third communication interface 30, to which an operating device and / or a personal computer (PC) or another information input device 47 can be conveniently connected. The at least one third communication interface 30 is preferably an Ethernet interface or another digital input. The third communication interface 30 is preferably located on a communication module 30a of the compressed air maintenance device 2.

[0109] Preferably, the compressed air maintenance device 2 is also equipped with a communication interface, referred to as a fourth communication interface 39 for ease of differentiation, which serves for communication between the internal control unit 26 and one or more other independent compressed air maintenance devices, which are not shown further. By way of example, the fourth communication interface 39 is also a component of the communication module 30a.

[0110] It is understood that the compressed air maintenance device 2 can be equipped with any additional electrical interfaces for the input and / or output of data and / or electrical signals.

[0111] The preferred consumer control device 1 illustrated by way of example enables, among other things, external input of the outlet pressure P2, which is to be regulated by the proportional pressure control valve 14, with the aid of the input means 42. The compressed air maintenance device 2 communicates directly with the external electronic control device 23 and can thus immediately implement a changed pressure value.

[0112] A soft-start function (not further illustrated) is preferably integrated into the consumer control device 1 to prevent sudden pressure increases. The user can define the speed at which the connected consumer device A is to be filled with compressed air by entering the appropriate parameters.

Claims

[1] Consumer control device (1), with a compressed air maintenance device (2) having the following components: - a proportional pressure control valve (14) having a feed inlet (16) and a working outlet (17) and which can be electrically controlled for its operation, - a device inlet (6) designed for connection to an external compressed air source (P), which is connected via an inlet channel (11) to the feed inlet (16) of the proportional pressure control valve (14), - a device outlet (7) designed for connection to an external consumer device (A), which is connected via an outlet channel (22) to the working outlet (17) of the proportional pressure control valve (14), - sensor means (20) at least in the form of a flow sensor (25) serving to measure the air flow occurring in the inlet channel (11) and / or outlet channel (22) and an outlet pressure sensor (24) serving to measure the outlet pressure (P2) prevailing in the outlet channel (22), - an internal electronic control unit (26) which is signal-connected both to the proportional pressure control valve (14) and to the sensor means (20), which is designed to generate an electrical pressure control signal for the proportional pressure control valve (14) depending on the state values ​​of the compressed air measured by the sensor means (20), - wherein the proportional pressure control valve (14) can regulate the outlet pressure (P2) prevailing in the outlet channel (22) to different outlet pressure values ​​depending on the electrical pressure control signal applied to it, wherein it can be operated both in a working mode (AM) regulating the outlet pressure (P2) to a working pressure value (P2A) and in a holding mode (HM) regulating the outlet pressure (P2) to a holding pressure value (P2H) that is lower than the working pressure value (P2A), characterized by , - that a shut-off valve (8) is connected in the outlet channel (22) between the proportional pressure control valve (14) and the outlet pressure sensor (24), which shut-off valve is signal-connected to the internal electronic control unit (26), and which can be switched by an electrical valve control signal of the internal electronic control unit (26) either into a release position (V1) releasing the outlet channel (22) for air passage or into a shut-off position (V0) blocking the outlet channel (22), - wherein the internal electronic control unit (26) is designed such that it can automatically switch the shut-off valve (8) from the release position (V1) to the shut-off position (V0) during the operating mode (AM) of the proportional pressure control valve (14) if the flow sensor (25) detects an air flow (Q) corresponding to or below a predetermined or predeterminable cut-off flow limit value (AW) over a predetermined or predeterminable limit period (tG), - and wherein the internal electronic control unit (26) is further designed such that it can also automatically switch the shut-off valve (8) back from the shut-off position (V0) into the release position (V1) and put the proportional pressure control valve (14) into the holding mode (HM) if the outlet pressure sensor (24) detects an outlet pressure (P2) which is lower than the working pressure value (P2A) and corresponds to a predetermined or predeterminable limit pressure value (P2G) during the shut-off position (V0) of the shut-off valve (8). [2] Consumer control device (1) according to claim 1, characterized by that the shut-off valve (8) is designed as a 2 / 2-way valve of the “normally open” type and is preloaded into the release position by spring means (10). [3] Consumer control device (1) according to claim 1 or 2, characterized bythat the internal electronic control unit (26) is designed in such a way that, when the connected external consumer device (A) again requires increased air, it can switch the proportional pressure control valve (14) from the holding mode (HM) to the working mode (AM) while leaving the shut-off valve (8) unchanged in the release position (V1). [4] Consumer control device (1) according to one of claims 1 to 3, characterized by that the outlet pressure sensor (24) is formed separately from the proportional pressure control valve (14) or is integrated into the proportional pressure control valve (14). [5] Consumer control device (1) according to one of claims 1 to 4, characterized by that the sensor means (20) also comprise an inlet pressure sensor (31) serving to measure the inlet pressure prevailing in the inlet channel (11), which is signal-connected to the internal electronic control unit (26). [6] Consumer control device (1) according to one of claims 1 to 5, characterized by that the internal electronic control unit (26) has output means (36) which are capable of outputting at least one electrical diagnostic signal generated with the cooperation of the sensor means (20) in addition to the electrical pressure control signal intended for the proportional pressure control valve (14) and the electrical valve control signal intended for the shut-off valve (8). [7] Consumer control device (1) according to claim 6, characterized by that the compressed air maintenance device (2) has at least one communication interface (28, 29) for tapping the generated electrical diagnostic signal and / or that the compressed air maintenance device (2) is equipped with optical display means (37) and / or acoustic warning means (38) which can be activated on the basis of electrical diagnostic signals. [8] Consumer control device (1) according to one of claims 1 to 7, characterized by that the internal electronic control unit (26) has comparator means (35) in which actual information supplied by the sensor means (20) can be compared with reference information stored in storage means (34) of the internal electronic control unit (26), wherein the internal electronic control unit (26) also has output means (36) which are designed to output the electrical pressure control signal for the proportional pressure control valve (14) and the electrical valve control signal for the shut-off valve (8) depending on the comparison result of the comparator means (35). [9] Consumer control device (1) according to one of claims 1 to 8, characterized bythat the internal electronic control unit (26) has storage means (34) in which data of various types, in particular measurement, control, diagnostic and / or analysis data, can be stored volatilely and / or remanently. [10] Consumer control device (1) according to one of claims 1 to 9, characterized byin that the compressed air maintenance device (2) is designed in the form of a modular assembly, wherein the proportional pressure control valve (14) is a component of a first valve module (14a), the shut-off valve (8) is a component of a second valve module (8a), the outlet pressure sensor (24) is a component of a first sensor module (24a), and the internal electronic control unit (26) is a component of a control module (26a), wherein the compressed air maintenance device (2) expediently also has at least one communication module (30a) which is equipped with at least one communication interface (30, 39) connected to the internal electronic control unit (26). [11] Consumer control device (1) according to one of claims 1 to 10, characterized bythat the compressed air maintenance device (2) has at least one communication interface (28, 29, 30, 39) connected to the internal electronic control unit (26), to which an internal and / or external electronic device can be connected for communication with the internal electronic control unit (26), in particular an external electronic control device (23) and / or an electronic information reading device (46) and / or an electronic information input device (47) and / or at least one other electronic device. [12] Consumer control device (1) according to claim 11, characterized bythat at least one communication interface (28) is designed as a bus interface and / or that at least one communication interface (30) is designed as a digital or analogue input or as a digital or analogue output, wherein expediently at least one communication interface (28, 29, 30) is designed as an electromechanical plug-in interface and / or for wireless signal transmission. [13] Consumer control device (1) according to one of claims 1 to 12, characterized by that the compressed air maintenance device (2) is equipped with input means (42) for activating and / or influencing and / or parameterizing the operating behavior of the internal electronic control unit (26) and / or the sensor means (20), wherein these input means (42) expediently contain at least one button and / or at least one switch (42a) and / or at least one electrical communication interface (28, 30). [14] Consumer control device (1) according to one of claims 1 to 13, characterized by that it has an external electronic control device (23) which is or can be connected in terms of control technology to the internal electronic control unit (26) of the compressed air maintenance device (2). [15] Method for controlling the compressed air supply of a consumer device (A) by means of a consumer control device (1), characterized by that the following procedural steps are carried out: - the consumer device (A) is supplied with compressed air at an outlet pressure (P2) through an electrically controllable proportional pressure control valve (14) and an electrically controllable shut-off valve (8) connected in series downstream of it, - the air flow (Q) flowing through the proportional pressure control valve (14) and the shut-off valve (8) to the consumer device (A) is measured, - furthermore, an outlet pressure (P2) of the compressed air to be supplied to the consumer device (A) is measured downstream of the shut-off valve (8), - during a normal operating phase (NBP) of the consumer control device (1), in which the measured air flow (Q) is above a predetermined cut-off flow limit value (AW), the proportional pressure control valve (14) is operated in a working mode (AM) and the shut-off valve (8) is operated in a release position (V1) allowing the air to pass to the consumer device (A), wherein the proportional pressure control valve (14) delivers compressed air regulated to a predetermined working pressure value (P2A) to the shut-off valve (8) during the working mode (AM), - during the normal operating phase (NBP), the shut-off valve (8) is switched from the release position (V1) to a shut-off position (V0) preventing air passage if the measured air flow (Q) is not higher than a predetermined switch-off flow limit value (AW) during a predetermined limit period (tG), whereby the consumer control device (1) is then operated in a stand-by operating phase (SBP), - during the stand-by operating phase (SBP), the shut-off valve (8) is switched back to the release position (V1) and the proportional pressure control valve (14) is operated in a holding mode (HM) if the measured outlet pressure (P2) drops to a predetermined limit pressure value (P2G) during the shut-off position (V0) of the shut-off valve (8) which is lower than the working pressure value (P2A), wherein the proportional pressure control valve (14) outputs compressed air to the shut-off valve (8) during the holding mode (HM) at a holding pressure value (P2H) which is lower than the working pressure value (P2A). [16] Method according to claim 15, characterized by that the holding pressure value (P2H) of the outlet pressure (P2) corresponds in height to the limit pressure value (P2G). [17] Method according to claim 15 or 16, characterized bythat when an increased air requirement occurs on the part of the connected external consumer device (A), the proportional pressure control valve (14) is switched from the holding mode (HM) back into the working mode (AM) with the shut-off valve (8) left unchanged in the release position (V1). [18] Method according to one of claims 15 to 17, characterized by that it is carried out by means of a consumer control device (1) designed according to one of claims 1 to 14.

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