EP2728205B1 - Compressed air maintenance unit, and consumer control device equipped with the same - Google Patents

Description

• ein elektrisch betätigbares Schaltventil, das einen mit einer Druckluftquelle verbindbaren Speiseeingang und einen Arbeitsausgang aufweist und das in eine den Arbeitsausgang mit dem Speiseeingang verbindende Offenstellung sowie in eine den Arbeitsausgang von dem Speiseeingang abtrennende Absperrstellung schaltbar ist,
• einen mit einer externen Verbrauchereinrichtung verbindbaren Geräteauslass, der über einen Auslasskanal mit dem Arbeitsausgang des Schaltventils verbunden ist,
• Sensormittel zumindest in Gestalt eines zur Messung des in dem Auslasskanal auftretenden Auslassdurchflusses dienenden Durchflusssensor,
• und eine interne elektronische Steuereinheit, die mit dem Schaltventil und mit dem Durchflusssensor signaltechnisch verbunden ist und die ausgebildet ist, um in Abhängigkeit von dem seitens des Durchflusssensors gemessenen Auslassdurchfluss ein elektrisches Umschaltsignal zu generieren, das das Schaltventil aus der Offenstellung in die Absperrstellung umschaltet.

The invention relates to a compressed air maintenance device which has the following components:

• an electrically actuated switching valve which has a feed inlet that can be connected to a compressed air source and a work outlet and which can be switched into an open position that connects the work outlet with the feed inlet and into a shut-off position that separates the work outlet from the feed inlet,
• a device outlet which can be connected to an external consumer device and which is connected to the working outlet of the switching valve via an outlet channel,
• Sensor means at least in the form of a flow sensor serving to measure the outlet flow occurring in the outlet channel,
• and an internal electronic control unit which is signal-connected to the switching valve and to the flow sensor and which is designed to generate an electrical switching signal depending on the outlet flow measured by the flow sensor, which switches the switching valve from the open position to the shut-off position.

The invention also relates to a consumer control device which is suitable for controlling a consumer device and which is equipped with at least one compressed air maintenance device of the aforementioned type and an electronic control device connected or connectable thereto.

A prior art developed in the aforementioned sense is from DE 10 2011 012 558 B3 known. This is a compressed air maintenance device that can be fluidically connected to a consumer device to be supplied with compressed air. The compressed air maintenance device is equipped with a switching valve which is designed as a 3/3-way valve and which allows three switching positions in which the consumer device can either be connected to a compressed air source or can be separated from the compressed air source, whereby it is disconnected in the two switching positions is either fluidically shut off or vented to atmosphere. An outlet channel connecting the switching valve to the consumer device is connected, among other things, to a flow sensor which enables monitoring of the outlet flow rate, that is to say the flow rate of the compressed air flowing through the outlet channel to the consumer device. The flow sensor is connected to an internal electronic control unit which can operate the 3/3-way valve and which is also able to output diagnostic signals that can be used further.

With the aid of the known compressed air maintenance device, a consumer device can be supplied very efficiently with compressed air. However, problematic situations can arise on the part of the connected consumer device if the switching valve switches into the shut-off position due to an unforeseen power failure or some other loss of the electrical energy supply. The consumer device is then decoupled from the compressed air supplying it, so that components relying on the compressed air may perform uncontrolled movements that result in damage or even dangerous situations.

From the DE 10 2009 016 069 B3 a method is known which enables compressed air to be saved in pneumatic devices. The method provides for the compressed air supply to a pneumatic device to be interrupted by means of a 2/2-way valve if the pneumatic device is not operated for a long time. The 2/2-way valve is equipped with two pilot valves with which it can be switched to an open position or a shut-off position.

The object of the present invention is to take measures which, in conjunction with a compressed air maintenance device, enable an energetically favorable operation of consumer devices operated with compressed air and at the same time ensure high availability of connected consumer devices with regard to the supply of compressed air.

To solve this problem, a compressed air maintenance device of the type mentioned at the beginning provides that the switching valve is designed as a 2/2-way valve of the "normally open" type and is biased into the open position by spring means, so that it is always in the absence of an electrical switching signal takes the open position.

The object is also achieved with a consumer control device that has a compressed air maintenance device configured in the aforementioned sense and a connected thereto or connectable external electronic control device.

The compressed air maintenance device has a switching valve designed as a 2/2-way valve of the "normally open" type, which can be switched from the open position assumed in normal operation to the shut-off position on the basis of measured values of the flow sensor in order to reduce air consumption in the downstream external consumer device and in the duct system leading to this consumer device. For example, the switching valve can be switched to the shut-off position if the connected consumer device is not operated for a longer period of time. With the switching valve remaining in the open position, a certain amount of air consumption would have to be expected due to leakage on the part of the consumer device even during its operational standstill, which would have a negative effect on the energy balance. In addition, the compressed air maintenance device according to the invention offers the advantage that the air supply to the connected consumer device is not interrupted in the event of a power failure or any other loss of the electrical energy supply required to operate the switching valve. Because the switching valve is biased into the open position by spring means and an electrical switching signal is only required for switching and maintaining the shut-off position, the failure of the electrical switching signal does not affect the switching position of the switching valve in the open position.

In the present description and in the claims, the term "flow" is used as a representative and for the sake of simplicity for the terms that are correct in themselves, such as "volume flow", "Flow rate" or "flow rate" is used and means an amount of flow per unit of time.

Advantageous further developments of the invention emerge from the subclaims.

The compressed air maintenance device is expediently designed in such a way that the internal electronic control unit switches the switching valve from the open position assumed up to that point to the shut-off position if the flow sensor, during the open position of the switching valve, has a lower flow limit value than a given or predeterminable over a given or predefinable period of time lying flow rate detected. In this way, an automatic shut-off function can be implemented if the flow rate falls below a minimum value in the outlet channel for a long time. In this way, it is possible to prevent a loss of compressed air during system downtimes, which can occur due to leaks in the connected consumer device if it is constantly exposed to a high pressure potential.

The sensor means preferably also contain a pressure sensor, referred to as an outlet pressure sensor, which is connected to the outlet channel and can measure the outlet pressure prevailing therein. With the aid of such an outlet pressure sensor, for example, when the switching valve is in the shut-off position, the pressure drop occurring in the outlet channel per unit of time and consequently a possible leakage problem can be determined. Overall, the outlet pressure sensor offers the possibility of monitoring the pressure drop behavior or pressure increase behavior occurring on the consumer side when the switching valve is closed.

It is also advantageous if the compressed air maintenance device is equipped with a pressure sensor, referred to as an inlet pressure sensor, which is connected to an inlet duct connected to the inlet of the switching valve and measures the inlet pressure therein. In this way, in particular, constant monitoring is possible to determine whether the desired system pressure is present at the correct level on the inlet side.

The internal electronic control unit is expediently not only able to generate the electrical switching signal for the switching valve as required, but is in particular designed in such a way that it can output at least one electrical diagnostic signal which, with the assistance of the sensor means, i.e. on the basis of the measured values recorded by the sensor means can be generated. For example, a diagnostic signal can be output when the flow sensor and / or a possibly existing pressure sensor of the compressed air maintenance device determines compressed air states which deviate from the values expected or tolerable in normal operation. Different operating states can be based, for example, on leakage or on malfunctions of components of the connected external consumer device. At least one electrical diagnostic signal can expediently be generated in addition to the electrical switchover signal. Alternatively, however, it can also be provided that the electrical switchover signal itself is used directly as a diagnostic signal.

The compressed air maintenance device is expediently directly equipped with optical display means and / or with acoustic warning means, which are generated on the basis of an output means of the internal electronic control unit electrical diagnostic signal can be actuated to indicate problematic operating conditions directly on site.

The compressed air maintenance device is preferably designed in the form of a modular assembly. The functional components of the device are expediently combined in individual modules, which can be put together in different combinations depending on the desired degree of equipment. The switching valve is expediently part of a valve module which, if present, preferably also contains the inlet pressure sensor. The flow sensor is expediently part of a sensor module which, if present, preferably also contains the outlet pressure sensor. Finally, the internal electronic control unit is expediently part of a control module. At least one further module can be equipped as a communication module which has at least one communication interface connected to the internal electronic control unit, which enables electrical communication with at least one external electronic device. Even with a non-modular structure, the compressed air maintenance device is expediently equipped with at least one communication interface for electrical communication with at least one external electronic device.

The compressed air maintenance device is preferably equipped with one or more communication interfaces to which an external electronic control device, in particular acting as a higher-level controller, and / or an electronic information readout device and / or an electronic information input device and / or at least one further external electronic device can or can be connected .

At least one communication interface is expediently used to integrate the compressed air maintenance device into a modular, internally electrically networked system with a local bus system.

For example, there is at least one communication interface which is designed as a bus interface for, in particular, serial data transfer. The electronic control unit of the compressed air maintenance device can be networked with other electronic devices via a field bus via such a bus interface.

At least one communication interface is expediently designed as a digital or analog input or as a digital or analog output.

The compressed air maintenance device is preferably also equipped with a communication interface which is used for communication between the electronic control unit and one or more further compressed air maintenance devices of the same or a different compressed air processing device 4.

Communication with external devices takes place in particular in a wired manner, but can also be implemented wirelessly via appropriately designed communication interfaces. Any bus standards can be implemented in bus communication.

At least one communication interface is expediently suitable for bidirectional signal transmission. In addition, at least one communication interface is expediently designed for inputting and / or outputting binary and / or analog signals. Such a communication interface is expediently in addition to one as a bus interface trained communication interface available.

In order to influence the operating behavior of the internal electronic control unit and / or the sensor means, the compressed air maintenance device is expediently equipped with suitable input means. Such input means consist, for example, of at least one button and / or at least one switch which are arranged easily accessible on the outside. In addition or as an alternative, input means can also be present in order to be able to carry out purely electrical data and / or signal input, for example via a special operating device or via an external electronic control device that usually communicates with the compressed air maintenance device. Such input means consist in particular of at least one electrical communication interface.

The equipment of the compressed air maintenance device expediently enables extensive monitoring and diagnostic functions such as comparison measurements, limit value monitoring, automatic and / or user-controlled consumption measurements, the recording of the ventilation volume and the ventilation time of the connected consumer device and / or the determination of the pressure drop time and the pressure drop rate in the Shut-off position of the switching valve.

Functions for measured value compression and data reduction are expediently integrated into the compressed air maintenance device, as well as functions for measured value analysis or statistical functions.

The internal electronic control unit is expediently equipped with storage means in which data of various types, in particular measurement, control, diagnosis and / or analysis data, can be stored in a volatile and / or retentive manner, ie permanently even in the event of a power failure.

The integration of the internal electronic control unit in the compressed air maintenance device has the advantage that the compressed air maintenance device can be operated autonomously without having to rely on constant signal communication with networked devices or with an external electronic control device, which considerably reduces the susceptibility to failure. Nevertheless, bus networking and / or the connection to an external electronic control device is of course advantageous in order to be able to adapt the operating behavior to other components of a system.

The expedient local signal processing in the internal electronic control unit allows a very high signal sampling rate and a relatively short response time for the measurement and control functions, since the transfer times via a connected field bus and computing times in an external electronic control device are eliminated. For the transfer of measurement, status, control and parameterization data, the compressed air maintenance device can be equipped with bus interfaces of all common fieldbus protocols.

By selecting the appropriate scope of equipment, the compressed air maintenance device can be designed as a fieldbus-compatible system with an electrical interface for system parameterization and for the transmission of measurement and control data. Optional measures for local operation and visualization, for example via an optionally integrated display or via a display and control device that can be connected on site, are also possible.

In a further embodiment, the compressed air maintenance device is a stand-alone system that has at least one digital input and / or at least one digital output, so that local operation and visualization can be carried out using locally available means. Thanks to a modular system structure, the following application variants can preferably be implemented: as an autonomous single device (stand-alone variant), as an independently operating single device that can be networked via fieldbus and as a function module that can be integrated into maintenance devices with or without a fieldbus connection.

The invention is explained in more detail below with reference to the accompanying drawing. The only figure ( Figure 1 ) shows a schematic representation of a preferred structure of the consumer control device according to the invention with a compressed air maintenance device according to the invention of a particularly useful structure integrated therein.

The consumer control device, designated in its entirety by reference number 1, contains as the main component at least one compressed air maintenance device 2, preferably designed in the form of a self-supporting structural unit. This compressed air maintenance device 2 is expediently of modular construction and, if required, can also be combined with other maintenance modules, one of which is at 3 Is indicated by dash-dotted lines, can be combined to form a compressed air processing device 4. For example, a pressure control module and / or a filter module and / or an air drying module are present as at least one further maintenance module.

The compressed air maintenance device 2 has a device housing 5, which is illustrated in a simplified manner as a frame and which carries and / or the other components of the compressed air maintenance device 2 contains. The device housing is expediently of modular design.

On the outside of the device housing 5 there is a device inlet 6 and a device outlet 7, each of which is suitable for establishing a fluid connection. The device inlet 6 is designed to be connected to a compressed air source P via a fluid line designated as the feed line 12. The state of such a compressed air source P connected to the device inlet 6 is shown.

The device outlet 7 is designed to be able to connect a fluid line which leads to an external consumer device A and is referred to as a working line 13. A state is shown in which a consumer device A - for example a machine that has several fluid-operated working components - is connected to the device outlet 7.

The compressed air maintenance device 2 has an electrically actuated switching valve 14. This is expediently housed in the interior of the device housing 5 and is preferably part of a valve module 14a of the modular compressed air maintenance device 2. The switching valve 14 has a 2/2 valve functionality, so has two paths or connections and two possible switch positions. In other words, it is a 2/2-way valve. It is preferably of the electro-pneumatically pilot-operated type, but it could also be designed as a directly electrically operated valve.

The switching valve 14 has a first switching position which can be seen from the drawing and which is the basic position of the switching valve 14, which is always then is present when there is no electrical switchover signal at the switching valve 14. Starting from this, it can be temporarily switched to a second switch position by activating a valve drive 15a by means of an electrical switchover signal. The second switching position remains as long as the associated valve drive 15a is electrically activated. The electric valve drive 15a is in particular an electromagnetic device, although other types of electric drive means can also be used.

The switching valve 14 contains spring means 19 by which it is constantly preloaded in the direction of the basic position. If the electrical switchover signal is removed while the switching valve 14 is in the second switching position, the spring means 19 switch the switching valve 14 back to the first switching position or basic position. The spring means 19 are preferably of a mechanical type, but can also be implemented in the form of an air spring.

The two connections of the switching valve 14 form a feed inlet 16 and a work outlet 17. The feed inlet 16 is continuously connected to the device inlet 6 via an internal inlet channel 11 of the compressed air maintenance device 2. The work outlet 17 is connected to the device outlet 7 via an internal outlet channel 22 of the compressed air maintenance device 2. The inlet channel 11 and the outlet channel 22 expediently run in the interior of the device housing 5.

The first switching position and consequently the basic position of the switching valve 14 is an open position. In the open position, the work outlet 17 is fluidically connected to the feed inlet 16 and the outlet channel 22 and with it the connected consumer device A is switched off with compressed air the compressed air source P is supplied. The second switching position of the switching valve 14 is a shut-off position. In the shut-off position, the work outlet 17 is separated from the feed inlet 16, so that the outlet channel 22 is shut off and the fluid volume located therein and in the working line 13 and the adjoining channel system of the consumer device A is locked.

Due to the above-mentioned spring means 19, the switching valve 14 is of the "normally open" type. If there is no electrical switchover signal, the switching valve 14 always assumes the open position.

The switching valve 14 is held in the open position during the operating times of the connected consumer device A by constantly applying the electrical switchover signal. During these operating times, the consumer device A processes a predetermined operating cycle, for example, once or periodically. The sequence of this operating cycle is expediently controlled by an external electronic control device 23 which communicates with the consumer device A in terms of control technology by means of schematically indicated communication means 23a, for example a field bus.

If the consumer device A is not to be operated, for example during breaks in operation, the switching valve 14 can be switched to the shut-off position. In the case of longer breaks in operation, this means that there is no unnecessary air consumption, possibly caused by leakage at the consumer device A. During only brief pauses in operation of the consumer device A, a positioning of the switching valve 14 in the shut-off position has the effect that the air volume present in the consumer device A is maintained and is available again for restarting operations. There is thus no need to completely fill the consumer device A again with compressed air, which enables the consumer device A to be operated very efficiently in terms of energy.

The compressed air maintenance device 2 is equipped with sensor means 20 for detecting at least one state variable of the compressed air in the system. These sensor means 20 contain a flow sensor 25 connected to the outlet channel 22 and preferably also a pressure sensor also connected to the outlet channel 22 and therefore referred to as the outlet pressure sensor 24.

Optionally and preferably, the sensor means 20 also contain a further pressure sensor connected to the inlet channel 11 and therefore referred to as inlet pressure sensor 31.

All sensor means 20 are expediently located inside the device housing 5. The flow sensor 25 and the optionally available outlet pressure sensor 24 are expediently part of a sensor module 25a of the compressed air maintenance device 2. The optionally available inlet pressure sensor 31 is expediently part of the switching valve 14 containing valve module 14a.

The flow sensor 25 is able to determine the current flow rate of the compressed air flowing through the outlet channel 22, that is to say the flow rate of this compressed air. In the following, this measured flow rate will also be referred to as the outlet flow rate. The outlet pressure sensor 24 is able to measure the pressure prevailing in the outlet channel 22, this pressure also being referred to below as the outlet pressure. The inlet pressure sensor 31 is able to to measure the pressure prevailing in the inlet channel 11, this pressure also being referred to below as the inlet pressure.

The compressed air maintenance device 2 contains an internal electronic control unit 26 which is preferably accommodated in the interior of the device housing 5 and which is equipped with at least one microprocessor or microcontroller. For the sake of simplicity, it will also be referred to below as “internal control unit 26”. The internal control unit 26 is preferably part of a control module 26a of the compressed air maintenance device 2.

The internal control unit 26 is signal-connected via internal electrical signal lines 27 of the compressed air maintenance device 2 to the valve drive 15a of the switching valve 14, to the flow sensor 25 and, if available, to the outlet pressure sensor 24 and the inlet pressure sensor 31. The internal control unit 26 can receive electrical pressure measurement values and flow measurement values from the sensor means 20 and can output an electrical switchover signal from the switching valve 14 and, preferably, electrical diagnostic signals as well.

The compressed air maintenance device 2 is equipped with an electrical interface, referred to below as the first communication interface 28 for better differentiation, which enables signaling communication between the internal control unit 26 and the external electronic control device 23. The first communication interface 28 is arranged in particular on an outside of the device housing 5 and is expediently connected to the internal control unit 26 via internal electrical conductors 32. Preferably, the first communication interface 28 is from electromechanical type and in particular designed as a plug-in interface or plug-in connection device, so that an external signal cable 33, only indicated schematically, can be connected, in particular detachably, which enables a connection to the external electronic control device 23.

The first communication interface 28 is preferably a bus interface which is 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.

Alternatively, the first communication interface 28 can also be designed as a wireless interface in order to be able to communicate with the external electronic control device 23, in particular via radio signals.

The first communication interface 28 is preferably located on the control module 26a.

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 and the inlet pressure measured by the inlet pressure sensor 31 as well as flow values of the flow sensor can be stored 25 relevant outlet flow rate as reference information and preferably also as actual information. The comparator means 35 are able to compare stored reference information with, in particular, also temporarily stored or also with directly measured actual information. The output means 36 are in able to output at least one electrical signal as a function of the comparison result determined by the comparator means 35. As an example, the output means 36 are designed to output both an electrical switchover signal intended for the switching valve 14 and at least one electrical diagnostic signal that can be used elsewhere.

The output means 36 of the internal control unit 26 preferably 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.

At least one electrical diagnostic signal can also be fed to optical display means 37 of compressed air maintenance device 2 in order to visualize it in any way.

It is also possible that the compressed air maintenance device 2 is equipped with acoustic warning means 38 only indicated by dashed lines, for example a buzzer, so that an acoustic warning signal can be output when a corresponding electrical signal is received on site.

During its operation, the internal control unit 26 can receive and process measurement signals originating from the flow sensor 25 and optionally also from the outlet pressure sensor 24 and / or from the inlet pressure sensor 31 as actual information. In this way, the internal control unit 26 receives current values of the outlet flow rate as a function of time and possibly also of the outlet pressure and / or the inlet pressure as actual information. The internal control unit 26 can be designed to output this actual information electrically or visually at the first communication interface 28 and / or at the optical display means 37.

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

The compressed air maintenance device 2 offers, for example, the possibility of carrying out leakage monitoring when the switching valve 14 is in the shut-off position. For this purpose, the internal control unit 26 records actual information supplied by the outlet pressure sensor 24 during the shut-off position of the switching valve 14 and compares it with stored reference information. The internal control unit 26 then initiates the output of a diagnostic signal via the output means 36, for example, when the determined pressure drop in the outlet pressure falls below a predetermined tolerance value.

As with the monitoring of the outlet pressure, the monitoring of the outlet flow can also only record the actual information once or multiple times, whereby the actual information can be recorded more than once, in particular at regular intervals.

The compressed air maintenance device 2 enables particularly advantageous flow monitoring of the outlet flow. This takes place when the switching valve 14 is in the open position. In this open position, compressed air normally flows from the compressed air source P to the consumer device A and there actuates one or more working components of the consumer device A that can be activated by means of fluid power. One or more of these working components are, for example pneumatic drives. By comparing the recorded actual outlet flow rate information with stored reference values, it is very easy to monitor whether an increased air consumption occurs during the operating cycle or during certain phases or partial cycles of the operating cycle, which is an indication of malfunctions or faulty work components.

In the case of flow monitoring, too, the internal control unit 26 is preferably designed in such a way that it outputs an electrical diagnostic signal if the actual information determined deviates from the assigned reference information by a predetermined tolerance value, in particular if air consumption deviates significantly from a reference value.

A particular advantage of the switching valve 14 designed as a “normally open” valve is that it assumes the open position regardless of whether the electrical switchover signal is intentional or unintentional. An unintentional lack of the electrical switchover signal is due, for example, to an unintentional power failure in the electrical energy supply of the compressed air maintenance device 2. An intentional lack of the electrical switchover signal can be traced back, for example, to an emergency stop situation that is deliberately caused by the user of the system, or to an intentional shutdown of the power supply during commissioning or during service or repair work where an automatic locking function is undesirable is. In all of these situations, the compressed air supply to the connected consumer device A remains unaffected, so that there are no dangerous situations due to uncontrollable movements of components of the consumer device A. Only when the power supply is back on or when If an electrical switchover signal is otherwise deliberately fed in or the switching valve 14 is switched manually, a shut-off situation that uncouples the consumer device from the compressed air supply can be established.

The internal control unit 26 is designed or at least programmable or programmed in such a way that it switches the switching valve 14 from the open position to the shut-off position and into the shut-off position, in addition or as an alternative to the output of at least one electrical diagnostic signal, depending on the comparison result determined by the comparator means 35 can generate sustaining electrical switching signal. The internal control unit 26 generates such an electrical switchover signal in particular when the outlet flow value detected in the outlet channel 22 is below a predetermined lower flow limit value during a predetermined period of time, which can be freely parameterized in particular by input means 42 of the compressed air maintenance device 2. The lower flow limit value can also expediently be freely parameterized by input means 42 of compressed air maintenance device 2

It goes without saying that the electrical switching signal itself can also be used directly as a diagnostic signal.

The tolerance values to be taken into account when generating a diagnostic signal or electrical switchover signal can preferably be entered individually into the internal control unit 26. The user of the compressed air maintenance device 2 can thus adapt the tolerance values and thus the signal output individually to his needs. In particular, the already mentioned input means 42 can be used to input the tolerance values.

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, which is a bus interface here, the external electronic control device 23 being usable as an information input device. The bus interface can, for example, correspond to the I / O link standard.

In the exemplary embodiment, 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 in particular an electronic information readout device 46 of the consumer control device 1 can be connected at least temporarily. Such an information readout device 46 enables, for example, measured actual information to be read out, in particular in connection with the assigned reference information, so that, for example, in connection with the flow monitoring, it can be verified at the same time or later at which point in the recorded reference profile an irregularity has occurred. The second communication interface 29 is in particular an Ethernet interface or another digital output. It is located in particular on the control module 26a that may be present.

As a further input means 42 for electronic data input for the purpose of configuring the system, the compressed air maintenance device 2 of the exemplary embodiment contains at least one communication interface, which is referred to as third communication interface 30 for better differentiation and to which an operating device and / or a personal computer (PC) can be conveniently connected . The at least one Third communication interface 30 is in particular an Ethernet interface or some other digital input. The third communication interface 30 is preferably located on a communication module 30a of the compressed air maintenance device 2.

The compressed air maintenance device 2 is preferably also equipped with a communication interface which is used for communication between the electronic control unit 26 and one or more other neighboring compressed air maintenance devices of the same or a different compressed air processing device 4. This can be an additional communication interface not shown in the drawing or one of the communication interfaces present in the exemplary embodiment.

It goes without saying that the compressed air maintenance device 2 can be equipped with any further electrical interfaces for inputting and / or outputting data and / or electrical signals.

If the compressed air maintenance device 2 is implemented as a modular unit, it has compact dimensions and can be equipped with the desired functionality in a small space. The existing modules 14a, 25a, 26a and 30a can easily be assembled as required.

Claims (15)

1. Compressed air maintenance unit which has the following constituent parts:

   - an electrically actuable switching valve (14) comprising a feed inlet (16) connectable to a compressed air source (P) and an operating outlet (17) and able to be switched into an open position connecting the operating outlet (17) to the feed inlet (16) and also into a shut-off position separating the operating outlet (17) from the feed inlet (16),

   - a unit outlet (7) which may be connected to an external consumer device (A) and which is connected via an outlet passage (22) to the operating outlet (17) of the switching valve (14),

   - sensor means (20) at least in the form of a flow sensor (25) used to measure the outlet flow occurring in the outlet passage (22),

   - and an internal electronic control unit (26) which is connected for signalling to the switching valve (14) and the flow sensor (25) and which is designed, on the basis of an outlet flow measured by the flow sensor (25), to generate an electrical changeover signal which switches the switching valve (14) from the open position into the shut-off position, characterised in that

   - the switching valve (14) is a 2/2-way valve of the "Normally Open" type and is biased towards the open position by spring means (19) so that, in the absence of an electrical changeover signal, it always adopts the open position.
2. Compressed air maintenance unit according to claim 1, characterised in that the internal electronic control unit (26) is designed to generate a changeover of the switching valve (14) from the open position into the shut-off position, when the flow sensor (25) detects, during the open position of the switching valve (14) and over a preset or presettable period of time, a flow value lying below a preset or presettable flow limit value.
3. Compressed air maintenance unit according to claim 1 or 2, characterised in that the sensor means (20) also have an outlet pressure sensor (24) used for measuring the outlet pressure prevailing in the outlet passage (22) and connected for signalling purposes to the internal electronic control unit (26).
4. Compressed air maintenance unit according to any of claims 1 to 3, characterised in that it has a unit inlet (6) connectable to an external compressed air source and which is connected via an inlet passage (11) to the feed inlet (16) of the switching valve (14), wherein the sensor means (20) also have an inlet pressure sensor (31) serving to measure the inlet pressure prevailing in the inlet passage (11) and connected for signalling purposes to the internal electronic control unit (26).
5. Compressed air maintenance unit according to any of claims 1 to 4, characterised in that the internal electronic control unit (26) has output means (36) which are able to output, in addition to the electrical changeover signal intended for the switching valve (14), at least one electrical diagnostic signal generated with the help of the sensor means (20), wherein the compressed air maintenance unit (2) expediently has at least one communications interface (28, 29) for pickup of the generated electrical diagnostic signal.
6. Compressed air maintenance unit according to claim 5, characterised in that it is equipped with optical display means (37) and/or audible warning means (38) which may be activated on the basis of an electrical diagnostic signal.
7. Compressed air maintenance unit according to any of claims 1 to 6, characterised in that the internal electronic control unit (26) has comparison means (35) in which actual information supplied by the sensor means (20) may be compared with reference information stored in memory means (34), wherein the internal electronic control unit (26) also has output means (36) which are designed, on the basis of the comparison result from the comparison means (35), to output the electrical changeover signal for the switching valve (14) and/or an electrical diagnostic signal which may be used for other purposes.
8. Compressed air maintenance unit according to any of claims 1 to 7, characterised in that the internal electronic control unit (26) has memory means (34) in which a variety of data, in particular measurement, control, diagnostic and/or analysis data, may be stored on a temporary or permanent basis.
9. Compressed air maintenance unit according to any of the preceding claims 1 to 8, characterised in that it is designed in the form of a modular unit, in which the switching valve (14) is part of a valve module (14a), the flow sensor (25) is part of a sensor module (25a), and the internal electronic control unit (26) is part of a control module (26a).
10. Compressed air maintenance unit according to claim 9, characterised in that it has at least one communications module (30a) which is equipped with at least one communications interface (30) connected to the internal electronic control unit (26).
11. Compressed air maintenance unit according to any of claims 1 to 10, characterised in that it has at least one communications interface (28, 29, 30) connected to the internal electronic control unit (26) and to which may be connected for communication with the internal electronic control unit (26) an internal and/or external electronic device, in particular an external electronic control device (23) and/or an electronic information reader (46) and/or an electronic information input device (47) and/or at least one other electronic device.
12. Compressed air maintenance unit according to claim 11, characterised in that at least one communications interface (28) is conceived as a bus interface and/or at least one communications interface (30) as a digital or analog input or as a digital or analog output.
13. Compressed air maintenance unit according to claim 12, characterised in that at least one communications interface (28, 29, 30) is in the form of an electromechanical plug-in interface and/or that at least one communications interface (28, 29) is designed for wireless signal transmission.
14. Compressed air maintenance unit according to any of claims 1 to 13, characterised in that it is equipped with input means (42) for the activation and/or influencing and/or parameterisation of the operating behaviour of the internal electronic control unit (26) and/or the sensor means (20), wherein the input means (42) expediently contain at least one key (42a) and/or at least one switch (42a) and/or at least one communications interface (28, 30).
15. Consumer control device with at least one compressed air maintenance unit (2) according to any of claims 1 to 14 and an external electronic control device (23) which is or may be connected thereto.

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