DE102005018889A1 - Multi-circuit safety valve has electromechanical valve arrangement which has shut-off valve which opens above predetermined pressure at common outlet junction of relief valves - Google Patents

Abstract

The multi-circuit safety valve includes relief valves (3,6) which have a common outlet junction (10) which is connected to a third compressed air outlet (28) via an electromechanical valve arrangement (2) which has a shut-off valve (2a) which opens above a predetermined pressure at the common outlet junction of the relief valves. The electromechanical valve arrangement has an electromagnetic actuating component (2b), by the influence of which the shut-off valve can be opened below the predetermined pressure at the common outlet junction of the relief valves. An independent claim is included for an air preparation plant including the aforesaid multi-circuit safety valve.

Description

The The invention relates to a multi-circuit protection valve for supplying pneumatic components of a Commercial vehicle, with at least one compressed air inlet, at least a first compressed air outlet for supplying a first service brake circuit via a first overflow valve, at least one second compressed air outlet for supplying a second Service brake circuit via a second overflow valve and at least one third compressed air outlet for supplying a Trailer.

The The invention further relates to an air treatment plant with a Multi-circuit protection valve.

Generic multi-circuit protection valves and air treatment plants are for example from the DE 44 21 575 C2 as well as the EP 0 776 807 B1 known. These systems have centrally ventilated multi-circuit protection devices. These are equipped with control electronics that can influence the circuit breaker valves. In addition to the service brake circuits and other consumers, the trailer and the parking brake system are supplied with compressed air in particular by the air treatment systems. In this context, it should be noted that the generic compressed air treatment systems make a compressed air tank in the trailer or parking brake circuit required. This is especially true, since with intact system a Nachversorgung the trailer or parking brake system circuit below a predetermined mechanical security pressure is not possible. With regard to the parking brake system is also to be noted that said compressed air conditioning systems can not ensure that the parking brake is only solvable when the service brake of the vehicle is operational or allows a minimum braking.

Another example of a multi-circuit protection valve in which the circuit control functions can be improved, in particular with regard to the trailer supply and the parking brake system is in the DE 29 50 904 C2 specified.

Of the Invention is based on the object, a multi-circuit protection valve or a compressed air treatment plant available so that it makes possible is the compressed air system of a commercial vehicle in terms of weight and to improve costs while ensuring safe operation of the vehicle even in the de-energized state of the multi-circuit protection valve or the air treatment plant ensures should be.

These The object is achieved by the features of the independent claims.

advantageous embodiments of the invention are in the dependent claims specified.

The Invention builds on the generic multi-circuit protection valve thereby on that the overflow valves have a common output node that the common Output node of the overflow valves via a Electromechanical valve arrangement with the third compressed air outlet is connected, wherein the electromechanical valve unit is a closing valve having, above a predetermined pressure at the common Output node of the overflow valves opens, and that the electromechanical valve arrangement is an electromagnetic Actuator, by whose influence the closing valve below the predetermined pressure at the common output node the overflow valves open can be. In this way, it is possible for one in a unit realized multi-circuit protection valves supply the trailer and the parking brake system takes over from a common output node. This common output node is preferably via a check valve with the outlet side of the overflow valves in connection. This makes it possible, the trailer circle, which preferably directly to the trailer supply connection connected with an intelligent electromechanical circuit fuse To ensure that in the currentless case, a mechanical minimum backup pressure exists while in the energized case, also below this pressure, an additional supply of the trailer is allowed. Advantageously, the common output node the overflow valves more circles for the Supply of additional auxiliary consumers downstream. This allows further overflow valves and Pressure limiters are integrated into the multi-circuit protection valve, thereby further installation costs can be saved. It is also from Benefit, an overflow valve for the Integrate air suspension. For the case that the supply pressure at the compressed air inlet of the multi-circuit protection valve too big for the service brake is, a pressure limiter is integrated in the multi-circuit protection valve. Furthermore, it is advantageous, the overflow valves on a common Connect input node. Parallel to the overflow valves can be at the common input node respectively parallel to the overflow valves a bypass may be provided, each bypass being a check valve and has a throttle point for limiting the flow rate. hereby can be a more uniform opening of the overflow valves be achieved.

The Invention is in more useful Way further developed, that the closing valve by means of a spring is adjustable to the predetermined pressure. The opening pressure of the closing valve let yourself thus in a simple way to the special conditions in the commercial vehicle to adjust.

Farther is it useful that the common output node of the overflow valves via the closing valve with a fourth compressed air outlet for supplying a parking brake system connected is. As with conventional Systems, become the trailer circle and the parking brake system from a common node within supplied the multi-circuit protection valve. By the upstream of the electromechanical Valve arrangement it is possible the ventilation only allow the spring-loaded cylinder of the parking brake system to if sufficient pressure for the service brake available stands.

In In this sense, it is advantageous that an electronic control is provided, which ensures that the electromagnetic actuator only with intact brake system, the closing valve below the predetermined Open the print can. In case of a defect in the brake system becomes the electromagnetic Actuator switched off or deactivated. Furthermore is it useful, a warning lamp on a display in the cab via a preferably digital Activate data line. In such a defect case is the trailer supply only up to the mechanical closing pressure sichergestallt. The error case, however, allows a continuation of the Vehicle until the next Repair workshop, so that high towing costs can be omitted.

According to one preferred embodiment provided that the closing valve and the electromagnetic actuator of the electro-mechanical valve assembly executed separately are. Leave the elements of the electromagnetic valve assembly thus separately in the housing realize the multi-circuit protection valve, so that a conventional construction the elements can be used.

Also Is it possible, that the closing valve and the electromagnetic actuator of the electro-mechanical valve assembly are designed as an electromagnetic valve unit, wherein the closing valve and the electromagnetic actuator concentrically nested are arranged.

In In this context, it is particularly useful that a coil of the electromagnetic actuator is surrounded by a yoke, so that When the coil is energized, a force is generated which is the spring force of the closing valve is opposite. The electromagnetic valve unit can under Use of a tie rod magnet be realized, wherein in energized Coil the magnetic circuit over the core and the yoke is closed. Thus, a force against the spring are induced so that the core is lifted off the valve seat. It is also possible a push magnet too use. In the case of energizing the coil in turn becomes a magnetic Circle over a core and a yoke closed, so against the force of the spring the core repelled from the valve seat can be. Due to the concentric arrangement of the valve piston and the coil eliminates many holes and seals. The spring support in the valve piston can also serve as a core for the tie rod magnets, which pulled up when energizing against the yoke surrounding the coil is and the spring force is thus reduced.

The Invention builds on a generic air treatment plant due to the fact that the overflow valves have a common output node that the common Output node of the overflow valves via a Electromechanical valve arrangement with the third compressed air outlet is connected, wherein the electromechanical valve unit is a closing valve having, above a predetermined pressure at the common Output node of the overflow valves opens and that the electromechanical valve arrangement is an electromagnetic Actuator, by whose influence the closing valve below the predetermined pressure at the common output node the overflow valves open can be. The air treatment plant with the multi-circuit protection valve according to the invention and a common control electronics for air treatment plant and Multi-circuit protection valve realizes a high degree of integration. in the Air dryers are in particular an electromagnetic drain valve unit and an electromagnetic regeneration unit driven.

Farther is more useful Way provided that the air dryer, the electronic control and the multi-circuit protection valve are interchangeable. For this purpose are the components of the air treatment plant preferably flanged together and bolted to the common control electronics. Especially in the case of a defect, the items are easily replaceable.

Of the The invention is based on the finding that a multi-circuit protection valve by simple measures with regard to the supply of the trailer and the parking brake system can be configured in an advantageous manner, which in particular the Weight of the utility vehicle, the cost of installation and repairs and safety during operation of the commercial vehicle concerns.

The Invention will now be described with reference to the accompanying drawings preferred embodiments exemplified.

there shows:

1 a circuit diagram of a first embodiment of a multi-circuit protection valve according to the invention;

2 a circuit diagram of a second embodiment of a multi-circuit protection valve according to the invention;

3 a circuit diagram of an air treatment plant according to the invention;

4 a sectional view of a portion of a multi-circuit protection valve according to the invention with a first embodiment of an electromechanical valve assembly; and

5 a sectional view of a portion of a multi-circuit protection valve according to the invention with a second embodiment of an electromechanical valve assembly.

at the following description of the drawings denote the same Reference signs the same or similar components.

1 shows a circuit diagram of a first embodiment of a multi-circuit protection valve according to the invention. The multi-circuit protection valve 37 is with an electronic control 18 In particular, for acquiring measured values and other data and for controlling the switching functions of the multi-circuit protection valve 37 is provided. The electronic control 18 has a central plug 19 on, over which a power supply from the vehicle battery 60 via supply lines 43 he follows. Furthermore, a data line 40 to the central plug 19 connected. This data line 40 For example, it serves to transfer digital data to a display 39 , which is preferably arranged in the cab of the commercial vehicle. The data line 40 can be bidirectional. Next to the data line 40 Additional data cables can be connected to the central connector 19 be connected via the data from the control unit 18 be delivered to other components of the commercial vehicle or via the control unit 18 Data from other components can be provided. At the electronic control 18 is still a redundancy plug 19a intended. This can be the central plug 19 replace, especially in the case of a defect of the central plug.

In the periphery of the multi-circuit protection valve 37 Furthermore, two compressed air tank K ₁ and K ₂ are arranged, via the multi-circuit protection valve 37 be filled. The containers K ₁ and K ₂ are at the compressed air outputs 7 respectively 4 of the multi-circuit protection valve 37 connected.

Furthermore, a parking brake system by the symbolic representation of a parking brake valve 44 and a spring-loaded cylinder 45 shown. This parking brake system is at an exit 23 of the multi-circuit protection valve 37 connected.

In addition to the mentioned outputs 4 . 7 . 23 of the multi-circuit protection valve 37 is another exit 28 provided, which serves to supply a trailer with compressed air.

There is also a compressed air inlet 1 provided, the compressed air from a compressor 52 (please refer 3 ) or a foreign filling input 69 (please refer 3 ) can be supplied.

The multi-circuit protection valve input 1 is via a common entrance node 5 with a first overflow valve 6 connected, which on the output side with the compressed air outlet 7 is coupled. At the common entrance node 5 is still a second overflow valve 3 connected, the output with the second compressed air outlet 4 is coupled. At the outlet side of the first overflow valve 6 is at a connection 8th a check valve associated with the compressed air tank K ₁ 9 connected. Similarly, on the output side of the second spill valve 3 a check valve 11 via a connection 12 coupled, this check valve 11 the second compressed air tank K _{2 is} assigned. Both check valves 9 . 11 lead to a common parent node 10 the overflow valves 3 . 6 ,

At the common exit node 10 is over a line branch 48 an electromechanical valve arrangement 2 connected. About this electromechanical valve assembly 2 are the compressed air outlets 23 and 28 over a common node 21 at the common exit node 10 the overflow valves 3 . 6 connected, with the output side of the electromechanical valve assembly 2 a trailer supply line 28a and one at the node 21 Beginning line branch 49 with check valve disposed therein 22 are provided for the parking brake.

The multi-circuit protection valve 37 also includes several pressure sensors 13 . 15 . 26 , The pressure sensor 13 measures over a line branch 13a the pressure at the compressed air outlet 7 , In an analogous way, the pressure sensor measures 15 over a line branch 15a the pressure at the compressed air outlet 4 , The pressure sensor 26 measures the pressure at the compressed air outlet 28 , The pressure sensor 13 is via an electrical line 14 with the electronic control 18 connected. The pressure sensor 15 is via an electrical line 16 with the electronic control 18 connected. The pressure sensor 26 is via an electrical line 14 with the electronic control 18 connected.

The electromechanical valve arrangement 2 includes a mechanical closing valve 2a and an electromagnetic actuator 2 B , By means of a pilot and bypass line 2c can the electromagnetic actuator 2 B be designed as a pneumatically piloted electromagnetic actuator. The electromagnetic actuator 2 B is via an electrical line 17 with the electronic control 18 connected.

The multi-circuit protection valve 37 according to 1 works especially with regard to the electromechanical valve arrangement 2 as follows. In the pressureless state of the system, air flows from the multi-circuit protection valve input 1 to the common input node 5 , At this point, the air pressure rises to the opening pressure of the overflow valves 3 or 6 which then open and allow an air flow to the first containers K ₁ and K ₂ . The air then flows over the check valves 9 . 11 to the common root node 10 and from there to the electromechanical valve assembly 2 , The electromechanical valve assembly is initially over the spring 59 kept closed because the predetermined by the spring opening pressure is not reached. Only when the pressure in at least one of the containers K ₁ or K _2, the opening pressure of the electromechanical valve assembly 2 exceeds, the air can to the node 21 flow, so only now with the parking brake valve open 44 the spring-loaded cylinder 45 can be vented to release the parking brake.

The electromechanical valve assembly is also capable of airflow to the node 21 and from there in particular to allow the trailer when the opening pressure of the closing valve 2a not yet reached. The closing valve 2a can namely by the electromagnetic actuator 2 B , which may be formed for example as a push magnet or tie rod magnet, are opened. For this purpose, the electromagnetic actuator 2 B over the line 17 through the electronic control 18 excited. This is useful if the pressure in the trailer circle has fallen so low that the mechanical closing valve 2a is already closed due to the undershooting of the mechanically predetermined closing pressure, but the trailer still requires compressed air. In that thus also below the opening pressure of the closing valve 2a a follow-up supply of the trailer can take place, a separate compressed air tank for the trailer is unnecessary.

A condition for a follow-up supply of the trailer is that the control electronics has detected no circuit, equipment or system defect. The control unit is used as data for the defect analysis 18 digital data transmitted via the central plug 19 or the redundancy connector 19a to provide. Other values to be considered with regard to defect detection are provided by the pressure sensors 13 . 15 . 26 delivered. The outside of the multi-circuit protection valve 37 detected and to be considered for the defect detection data may for example come from external sensors or electro-pneumatic valves of the towing vehicle or the trailer vehicle, for example, in connection with EBS, ABS, ESP, electric air suspension systems or the parking brake systems. If there is a defect, the electromagnetic actuator is switched off and a warning lamp on the display 39 via the digital data line 40 activated. The trailer supply is then ensured only up to the mechanical closing pressure. Driving on the vehicle to the nearest repair shop is still possible.

2 shows a circuit diagram of a second embodiment of a multi-circuit protection valve according to the invention. In the periphery of the multi-circuit protection valve shown here 37 In addition, a container k _{5 is provided} for an air spring circuit. This is via a multi-circuit protection valve 37 provided overflow valve 50 provided. The pressure in the circle 5 is via a pressure sensor 62 detected, which via an electrical line 62a with the electronic control 18 connected is. Between the multi-circuit protection valve input 1 and the common input node 5 is a pressure limit 51 integrated, which limits the pressure for the circles K ₁ and K ₂ . This is necessary if the pressure of the air suspension system can be greater than the permissible service brake pressure for the service brake. Furthermore, in this embodiment, parallel to the overflow valves 3 respectively 6 Bypass check valves 42 respectively 41 installed with assigned throttle. Through this, the air can be parallel to the overflow valves 3 and 6 flow into the containers K ₁ and K ₂ . This has the advantage that an adjustment error caused by mass production of the opening pressure of the overflow valves 3 . 6 is balanced, whereby a simultaneous opening of the overflow valves 3 . 6 is possible.

Furthermore, a pressure limit 46 for the trailer circle at the exit 28 and the parking brake system at the exit 23 integrated. The line branch 48 into which the pressure limiter 46 inte is branched from the common parent node 10 the overflow valves 3 . 6 from. At the common exit node 10 can be over a line branch 61 another pressure limiter 46a be connected via the overflow valve 47 is supplied for secondary consumers. In addition to the overflow valve 47 can more overflow valves via the pressure limiter 46a be supplied, for example, the spill valve shown 47a ,

3 shows a circuit diagram of an air treatment plant according to the invention. The air dryer unit 36 is preferably via a flange connection 70 with the multi-circuit protection valve 37 coupled, so that the multi-circuit protection valve, the air dryer unit 36 and the common electronic control device can each be separated, in particular for the purpose of replacement in case of defects.

The air dryer unit 36 has an air dryer entrance 34 , to the over a conveyor line 53 a compressor 52 connected. Furthermore, the air dryer unit 36 a foreign filling input 69 on. Inside the air dryer unit 36 are an electromagnetic regeneration unit 32 , an electromagnetic drain valve unit 33 and a dryer cartridge 33a intended. The electromagnetic regeneration unit 32 is parallel to one of the dryer cartridge 33 downstream check valve 42 arranged and from the electronic control 18 via an electrical line 32a controllable. The electromagnetic drain valve unit 33 is in a lead 35 arranged, one between the air dryer entrance 34 and the dryer cartridge 33a lying nodes 34 with a leading outward shock absorber 68 combines. The electromagnetic drain valve unit 33 is via an electrical line 33b with the electronic control 18 connected. At the mentioned node 34 is still the foreign filling input 69 over a line 71 connected.

In this embodiment, the electromechanical air dryer 36 without laying external lines in one to the multi-circuit protection valve 37 flanged valve block can be accommodated. It is also possible to provide the air dryer in the same valve block, as well as the multi-circuit protection valve 37 ,

4 shows a sectional view of a portion of a multi-circuit protection valve according to the invention with a first embodiment of an electromechanical valve assembly. The mechanical part of the electromagnetic valve assembly 2 is used as a closing valve 2a designated. Furthermore, the electromagnetic actuator 2 B shown. The line branch 48 guides air under the valve piston 63 , which by the spring 39 on the valve seat 64 is pressed. This will vent the trailer supply line 28a and the line branch 49 to supply the connection 23 prevented for the parking brake system. The check valve 22 prevents the parking brake from being accidentally engaged in the event of a fault in the wiring connected to the trailer. At the connection 23 Thus, in the currentless operation of the system is only air when the force resulting from the product of the pressure in the line 48 and the associated annular surface, is greater than that with the adjusting screw 66 preset force of the spring 59 ,

The wires 48 and 28a can also be reversed, so that there is a centrally vented closing valve.

The pressure in the pipe 48 , which is supplied by the common output node of the spill valves, also stands, reduced by the hysteresis of the check valves 9 . 11 , in the service brake circuits K ₁ and K ₂ . Thus, a minimum braking effect of the service brake is ensured. If the pressure continues to rise, the valve piston moves 63 against the spring force in the direction of the adjusting screw 66 , The air now flows over the knot 21 , The administration 49 and the check valve 22 the parking brake system for connection 23 for the parking brake system. Only now is it possible to release the parking brake.

During operation of the train, consisting of towing vehicle and trailer, the pressure in the lines drops 48 and 28a again below the closing pressure of the mechanical closing valve, so does the piston 63 again in closed position, blocking the way of lead 48 after line 28a , This pressure drop is from the sensors 13 . 15 . 26 detected and from the common control unit 18 compared with preset software parameters. Has the controller 18 detected by a plausibility check no defect, so the electrical line 17 The braking is energized for a certain period of time, and the air can now be over the line 2c to the trailer connection 28 stream. This is the one of a yoke 57 surrounded coil 58 of the electromagnetic actuator 2 B energized. Consequently, the core can 56 of the solenoid valve under compression of the tension magnet spring 59a from the valve seat 55 be lifted off, leaving air over the pipe 2c can additionally apply pressure to the valve piston of the closing valve. Thus, a subsequent supply of the trailer is ensured. The complete train can then be selectively braked again.

5 shows a sectional view of a portion of a Mehrkreisschutzven invention Tils with a second embodiment of an electromechanical valve assembly. In this embodiment of the electromagnetic valve assembly 2 For example, the closing valve and the electromagnetic actuator are arranged concentrically in one another. The tension magnet spring 59 is right at the core 56 arranged, which with the yoke 57 with energized coil 58 forms a magnetic circuit. Thus, the spring force of the Zugmagnetfeder 59 when energizing the coil 58 be reduced so far that the valve seat 53 before reaching through the spring 59 set closing pressure in the direction of the adjusting screw 66 can be moved. It can be exerted a force against the spring force, so that even below the mechanical closing pressure of the closing valve of the trailer connection 28 can be supplied with compressed air. The spring chamber of the electromagnetic valve arrangement shown here is via a vent 67 connected to the atmosphere. Particularly advantageous in the embodiment shown here is that the core 55 as a tie rod directly into the valve piston 63 is integrated, so that additional holes and seals can be omitted.

The in the above description, in the drawing and in the claims disclosed features of the invention can both individually and also in any combination for the realization of the invention be essential.

K1

Container circle 1 of the service brake

K2

Container circle 2 of the service brake

K3

Container Luftfederkreis

1

Multi-circuit protection valve inlet

2

electromechanical valve unit

2a

mechanical closing valve

2 B

electromagnetic actuator

2c

pilot and bypass line

3

second overflow valve

4

Compressed air outlet

5

common input node

6

first overflow valve

7

Compressed air outlet

8th

connection

9

check valve

10

common output node

11

check valve

12

connection

13

pressure sensor

13a

leg

14

electrical management

15a

leg

15

pressure sensor

16

electrical management

17

electrical management

18

electronic control

19

central plug

19a

redundancy plug

21

node

22

check valve for parking brake system

23

connection for parking brake system, Compressed air outlet

26

Air pressure sensor

28

Trailer supply port Compressed air outlet

28a

Trailer supply line

29

Pressure regulator check valve

32

electromagnetic regeneration unit

32a

electrical management

33

electromagnetic Drain valve unit

33a

dryer cartridge

33b

electrical management

34

node

35

drain line

36

electromechanical air dryer

37

electromechanical Multi-circuit protection valve

39

display

40

data line for digital dates

41

Bypass check valves

42

Bypass check valves

43

supply lines

44

Parking brake valve

45

Spring Brake

46

pressure limiter

46a

pressure limiter

47

overflow

47a

overflow

48

leg

49

leg

50

overflow

51

pressure limiter for service brake

52

compressor

53

delivery line

54

Air dryer input

55

valve seat

56

core

57

yoke

58

Kitchen sink

59

Zugmagnetfeder

59a

Zugmagnetfeder

60

vehicle battery

61

leg

62

pressure sensor

62a

electrical management

63

plunger

64

valve seat

66

adjustment

67

vent

68

silencer

69

External filling input

70

flange

71

management

Claims (9)

Multi-circuit protection valve for supplying pneumatic components of a commercial vehicle, with - at least one compressed air inlet ( 1 ), - at least one first compressed air outlet ( 7 ) for supplying a first service brake circuit via a first overflow valve ( 6 ), - at least one second compressed-air outlet ( 4 ) for supplying a second service brake circuit via a second overflow valve ( 3 ) and - at least one third compressed air outlet ( 28 ) for supplying a trailer, characterized in that - the overflow valves ( 3 . 6 ) a common parent node ( 10 ), - that the common output node ( 10 ) of the overflow valves via an electromechanical valve arrangement ( 2 ) with the third compressed air outlet ( 28 ), wherein the electromechanical valve unit is a closing valve ( 2a ), which opens above a predetermined pressure at the common output node of the overflow valves, and - that the electromechanical valve arrangement ( 2 ) an electromagnetic actuator ( 2 B ), by whose influence the closing valve ( 2a ) can be opened below the predetermined pressure at the common output node of the overflow valves. Multi-circuit protection valve according to claim 1, characterized in that the closing valve ( 2a ) by means of a spring ( 59 ) is adjustable to the predetermined pressure. Multi-circuit protection valve according to claim 1 or 2, characterized in that the common output node ( 10 ) of the overflow valves via the closing valve ( 2a ) with a fourth compressed air outlet ( 23 ) is connected to supply a parking brake system. Multi-circuit protection valve according to one of the preceding claims, characterized in that an electronic control ( 18 ) which ensures that the electromagnetic actuator ( 2 B ) only when the brake system is intact, the closing valve ( 2a ) can open below the predetermined pressure. Multi-circuit protection valve according to one of the preceding claims, characterized in that the closing valve ( 2a ) and the electromagnetic actuator ( 2 B ) of the electromechanical valve arrangement ( 2 ) are carried out separately. Multi-circuit protection valve according to one of the preceding claims, characterized in that the closing valve and the electromagnetic actuator of the electromechanical valve arrangement as an electromagnetic valve unit ( 2 ) are executed, wherein the closing valve and the electromagnetic actuator are arranged concentrically in one another. Multi-circuit protection valve according to claim 6, characterized in that a coil ( 58 ) of the electromagnetic actuator from a yoke ( 57 ) is surrounded, so that upon energization of the coil, a force is generated, which is opposite to the spring force of the closing valve. Air treatment plant with an air dryer ( 36 ), an electronic control ( 18 ) and a multi-circuit protection valve ( 37 ), wherein the multi-circuit protection valve comprises: - at least one compressed air inlet ( 1 ), - at least one first compressed air outlet ( 7 ) for supplying a first service brake circuit via a first overflow valve ( 6 ), - at least one second compressed air outlet ( 4 ) for supplying a second service brake circuit via a second overflow valve ( 3 ) and - at least one third compressed air outlet ( 28 ) for supplying a trailer, characterized in that - the overflow valves ( 3 . 6 ) a common parent node ( 10 ), - that the common output node ( 10 ) of the overflow valves via an electromechanical valve arrangement ( 2 ) with the third compressed air outlet ( 28 ), wherein the electromechanical valve unit is a closing valve ( 2a ), which opens above a predetermined pressure at the common output node of the overflow valves, and - that the electromechanical valve arrangement ( 2 ) an electromagnetic actuator ( 2 B ), by whose influence the closing valve ( 2a ) can be opened below the predetermined pressure at the common output node of the overflow valves. Air treatment plant according to claim 8, characterized in that the air dryer ( 36 ), the electronic control ( 18 ) and the multi-circuit protection valve ( 37 ) are interchangeable.