Brake control unit for a towing vehicle and a trailer that can be coupled to it.

Abstract

Control unit (1) for a towing vehicle with hydraulically actuated brakes (12a, 12b) and a trailer coupling thereto having a two-line compressed air brake system, comprising a hydraulic sensor (10) of the towing vehicle, a trailer control valve (3) on the towing vehicle which can be pressurized with hydraulic pressure by the hydraulic sensor (10) of the towing vehicle, a brake pressure regulating valve (24) integrated into the trailer control valve (3) for compressed air supplied to the trailer control valve (3) from a compressed air source (7), and a first electromagnetic venting arrangement (5) for controlled compressed air supply and venting of a pilot piston (25) in the trailer control valve (3) which actuates the brake pressure regulating valve (24), wherein the first electromagnetic venting arrangement (5) is arranged and configured such that in a first switching position it establishes a pneumatic connection (19,20) between a pressure relief valve (4) for compressed air supplied to the pressure relief valve (4) from the compressed air source (7) and the pilot piston (25) in the trailer control valve (3), that in the first switching position it closes a connection (20, 22) between the pilot piston (25) in the trailer control valve (3) and a venting device (55), and that in a second switching position it closes the pneumatic connection (19, 20) from the pressure relief valve (4) to the pilot piston (25) in the trailer control valve (3) and opens the pneumatic connection (20, 22) from the pilot piston (25) in the trailer control valve (3) to the venting device (55), wherein the electromagnetic venting arrangement (5), controlled by an electrical sensor (13) on the hydraulic sensor (10) of the towing vehicle, assumes the first switching position as soon as the hydraulic sensor (10) is activated is, and assumes the second switching position,when the hydraulic sensor (10) is deactivated, characterized in that the first electromagnetic venting and aeration arrangement (5) assumes the first switching position when the towing vehicle's readiness to drive is deactivated and assumes the second switching position when the towing vehicle's readiness to drive is activated.

Description

[0001] The invention relates to a control unit for a towing vehicle with hydraulically actuated brakes and a trailer coupling thereto having a two-line compressed air brake system, with a hydraulic sensor of the towing vehicle, with a trailer control valve on the towing vehicle which can be pressurized with hydraulic pressure by the hydraulic sensor of the towing vehicle, with a brake pressure regulating valve integrated into the trailer control valve for compressed air supplied to the trailer control valve from a compressed air source, and with a first electromagnetic ventilation and venting arrangement for a controlled compressed air supply and compressed air venting of a pilot piston in the trailer control valve which actuates the brake pressure regulating valve.

[0002] Such a control unit is known from DE 10 2008 048 208 A1. It comprises a brake actuation element, a brake cylinder for generating hydraulic pressure corresponding to the actuation of the brake actuation element, and a service brake that can be actuated according to the hydraulic pressure. In this known control unit, an electro-pneumatic actuation path for a trailer braking system is provided, in which a measuring element is arranged that generates an electrical signal corresponding to the actuation of the brake actuation element. Furthermore, a pressure control module is arranged in the electro-pneumatic actuation path, by means of which a pneumatic output pressure can be generated depending on the electrical signal, which is used to generate pneumatic brake pressure for the trailer.

[0003] Furthermore, DE 10 2009 045 191 A1 discloses a method for operating a brake device for a hydraulically braked towing vehicle, in particular a tractor, which can be coupled with a pneumatically braked trailer.

[0004] Furthermore, DE 197 52 147 A1 discloses a braking system for a motor vehicle which is intended for coupling a trailer with a pressure-medium-operated, in particular pneumatically operated, trailer braking system installed therein.

[0005] Furthermore, this control unit also includes a hydraulic-pneumatic actuation path for the trailer's braking system, in which the hydraulic pressure is supplied to a trailer control valve and, by means of the trailer control valve, a pneumatic output pressure can be controlled according to the supplied hydraulic pressure, which is used to generate a pneumatic brake pressure for the trailer.

[0006] The pressure control module is connected downstream of the trailer control valve. According to one embodiment, which includes the arrangement of the trailer control valve with the pressure control module and two solenoid valves for controlling the electro-pneumatic actuation path in a single housing, two solenoid valves designed as 2 / 2-way valves are provided to actuate the pilot piston in the electro-pneumatic actuation path. These solenoid valves can either both open or close, and can be switched so that either both close, both open, or alternately close and open.Depending on the position of these solenoid valves, which are controlled by an electronic control unit, compressed air from a compressed air reservoir flows via the trailer control valve and the pressure control module to a coupling head for the "brake," or the set pressure is maintained, or the coupling head for the "brake" is vented, thus releasing the trailer brakes. Additionally, hydraulic pressure from the brake cylinder can act on the trailer control valve via the hydraulic-pneumatic supply path and, according to the supplied hydraulic pressure, control a pneumatic output pressure, which is used to generate the pneumatic brake pressure for the trailer brakes. Since the signals reach the trailer control valve faster via the electro-pneumatic supply path than via the hydraulic-pneumatic supply path, this improves the response of the braking system.

[0007] Against this background, the invention is based on the objective of further developing a control unit of the type mentioned at the outset in such a way that the response behavior of the braking system is improved with minimal structural effort by generating and providing an adjustable pneumatic trailer brake pressure via an electro-pneumatic pilot control even before the hydraulic-pneumatic control of the towing vehicle brakes becomes effective.

[0008] The invention therefore comprises a control unit for a towing vehicle with hydraulically actuated brakes and a trailer that can be coupled to it and has a two-line compressed air brake system, with a hydraulic sensor of the towing vehicle, with a trailer control valve on the towing vehicle that can be pressurized with hydraulic pressure by the hydraulic sensor of the towing vehicle, with a brake pressure regulating valve integrated into the trailer control valve for compressed air supplied to the trailer control valve from a compressed air source, and with a first electromagnetic ventilation and venting arrangement for controlled compressed air supply and compressed air venting of a pilot piston in the trailer control valve that actuates the brake pressure regulating valve.

[0009] The problem is solved by the venting and aeration arrangement opening a pneumatic connection between a pressure relief valve for compressed air supplied from the compressed air source and the pilot piston in the trailer control valve in a first switching position; by the venting and aeration arrangement closing a connection between the pilot piston in the trailer control valve and a venting device in a first switching position; and by the venting and aeration arrangement closing the pneumatic connection from the pressure relief valve to the pilot piston in the trailer control valve and opening the pneumatic connection from the pilot piston in the trailer control valve to the venting device in a second switching position, wherein the first electromagnetic venting and aeration arrangement, controlled by an electrical sensor on the hydraulic transmitter of the towing vehicle, assumes the first switching position.as soon as the hydraulic sensor is activated, and assumes the second switching position when the hydraulic sensor is deactivated.

[0010] The braking system's rapid response is achieved by the first electromagnetic venting and purging circuit assuming its initial switching position as soon as the hydraulic master cylinder is activated, even before the hydraulic master cylinder has built up hydraulic brake pressure acting on the vehicle brakes and the trailer control valve. This is because the electrical sensor on the towing vehicle's hydraulic master cylinder reacts immediately after activation. The pressure relief valve, which provides the response pressure to the trailer control valve in response to the activation of the towing vehicle's hydraulic master cylinder, ensures the rapid application of the trailer brakes, even before the towing vehicle brakes become effective. Subsequently, the trailer brake pressure is modulated by the hydraulic pressure from the towing vehicle's hydraulic master cylinder via the trailer control valve on the towing vehicle.

[0011] Preferably, the electrical sensor can consist of an electrical switching element on a brake pedal for actuating the hydraulic master cylinder of the towing vehicle. This triggers an electrical signal from the sensor as soon as the driver touches the brake pedal, i.e., before hydraulic brake pressure builds up in the hydraulic master cylinder of the towing vehicle, which is usually the master cylinder of the towing vehicle's hydraulic brake system. However, it is advisable that the brake pedal must travel a short distance before actuating the electrical sensor to prevent accidental activation.

[0012] The function of this control unit can be easily extended with knowledge of the invention if a second electromagnetic venting and purging arrangement is arranged and configured such that, in a first switching position, it opens a connection between the compressed air source and an actuating piston of the brake pressure regulating valve and closes a connection to a purging arrangement, and in a second switching position, it closes the connection to the compressed air source and opens the connection to the actuating piston of the purging arrangement. The second electromagnetic venting and purging arrangement, controlled by a second electrical sensor on a parking brake actuator, assumes the first switching position when the parking brake actuator is activated and assumes the second switching position when the parking brake actuator is deactivated.

[0013] For this purpose, the second electrical sensor can consist of a switching element on a handbrake lever or on a parking brake activation switch. As soon as the handbrake lever of the towing vehicle is actuated or a parking brake activation switch is moved to the position for locking the towing vehicle, the trailer brakes are simultaneously pressurized with pneumatic pressure from the compressed air source and also locked.

[0014] Since the towing vehicle is usually equipped with a switching element for activating and deactivating the vehicle's readiness to drive, for example with an ignition lock that can be operated by means of an ignition key to supply power to an on-board electrical system, the first and / or the second electromagnetic ventilation arrangement can be switched so that they assume the first switching position when the vehicle's readiness to drive is deactivated and the second switching position when the vehicle's readiness to drive is activated.

[0015] It is preferably provided that the two electromagnetic ventilation and aeration arrangements are configured to assume the first switching position in the de-energized state, i.e., when the train's readiness to drive is deactivated, and the second switching position in the energized state.

[0016] This ensures that when the towing vehicle is deactivated, no current flows through the electromagnetic ventilation devices, and that the voltage source required to activate the towing vehicle's readiness to drive and to operate the electromagnetic ventilation devices, in the form of a vehicle battery, is not discharged by the electromagnetic ventilation devices when the towing vehicle is deactivated.

[0017] An advantageous embodiment of the electromagnetic venting arrangements is provided by a design as 3 / 2-way valves, which are simple in construction, can be operated with little electrical energy and fall into the first switching position by spring action in the de-energized state.

[0018] The response pressure of the control unit due to activation of the first electromagnetic venting arrangement can preferably be adjusted by means of an externally operable adjusting device on the pressure relief valve, preferably in the simplest way by means of an adjusting screw.

[0019] Given that the trailer control valve already has at least one relay piston that actuates the brake pressure regulating valve and is pressurized by hydraulic pressure from the hydraulic sensor of the towing vehicle, it is advantageous to design the pilot piston that actuates the brake pressure regulating valve in the trailer control valve as a stepped piston in tandem with the relay piston(s), whereby the brake pressure regulating valve can be actuated via a valve tappet solely by the stepped piston and / or together with the relay piston(s).

[0020] The actuating piston of the brake pressure regulating valve, arranged on the valve tappet, can advantageously be supplied with compressed air from the compressed air source via the second electromagnetic venting arrangement on the side facing the pilot piston, and supplied with regulated brake pressure on the side facing the brake pressure regulating valve.

[0021] Particularly preferred is an embodiment of the brake pressure regulating valve which has an actuating piston consisting of a fan piston with a diaphragm having an effective surface that can be changed by means of a fan disc, wherein the fan piston is attached to the valve tappet by means of a thread and the effective surface of the fan piston can be changed by rotating the valve tappet relative to the fan piston.

[0022] The trailer control valve can be arranged in a single housing together with the brake pressure regulating valve, the pressure limiting valve and at least the first electromagnetic venting arrangement, preferably with both electromagnetic venting arrangements, so that the pneumatic connections between these functional elements are formed by correspondingly designed channels in the housing, which may be left clear or drilled in a casting process for manufacturing the housing.

[0023] The invention is further explained below with reference to an embodiment illustrated in the drawing. The drawing shows Fig. 1 a schematic circuit diagram of a control unit designed according to the invention, and Fig. 2 a schematic longitudinal sectional view of the control unit according to the invention.

[0024] A control unit designated by reference numeral 1 comprises, within a single housing 2, a trailer control valve 3, a pressure relief valve 4, a first electromagnetic venting arrangement 5 in the form of a 3 / 2-way valve, and a second electromagnetic venting arrangement 6, also in the form of a 3 / 2-way valve. The housing 2 consists of two housing halves 2a and 2b. A compressed air source 7, which may be configured as a compressor and / or a compressed air reservoir and may be arranged on a towing vehicle and / or trailer (not shown), is connected to the trailer control valve 3 and the pressure relief valve 4 via a pneumatic connection 17. This pneumatic connection 17 and / or other pneumatic connections may be configured as a line or bore.

[0025] The pneumatic connection 17 is connected to a coupling head designated "Supply" 8, through which compressed air can be supplied from the compressed air source 7 to the trailer. The pneumatic brake pressure can be supplied to trailer brakes (not shown) via another coupling head designated "Brake" 9, which is connected to the trailer control valve 3 by a pneumatic connection 23. A pneumatic connection 19 carries regulated pneumatic pressure of a gaseous working medium, controlled by the pressure relief valve 4, to the first electromagnetic venting arrangement 5 and from there via a pneumatic connection 20 to the trailer control valve 3.

[0026] From pneumatic connection 17, a further pneumatic connection 18 branches off, which is connected to the second venting arrangement 6. The second venting arrangement 6 is connected to the trailer control valve 3 via a pneumatic connection 21.

[0027] A hydraulic master cylinder 10 of the towing vehicle, represented as a dual-circuit master brake cylinder of the towing vehicle, is connected via hydraulic connections 26, 28 to wheel brake cylinders 12a, 12b of the towing vehicle. Other hydraulic connections 27, 29 branch off from these hydraulic connections 26, 28 and are connected to the trailer control valve 3. The hydraulic master cylinder 10 of the towing vehicle can be actuated by means of a brake pedal 11, whereby hydraulic pressure, corresponding to the force with which the brake pedal 11 is actuated, is supplied to the wheel brake cylinders 12a, 12b and to the trailer control valve 3.An electrical sensor 13, for example in the form of an electrical proximity switch, is arranged on the brake pedal 11. This sensor is connected via an electrical connection 50, a vehicle readiness activation switch 15, for example in the form of a key-operated ignition lock, and an electrical connection 51 to one pole of a voltage source 16, for example a battery in the towing vehicle. An output of the electrical sensor 13 is connected via an electrical connection 52 to the first electromagnetic ventilation arrangement 5.

[0028] A second electrical sensor 14 serves to activate a parking brake and can accordingly be arranged on a handbrake lever of the towing vehicle (not shown) or be designed as a directly actuated parking brake activation switch and have a parking brake actuation element 14a.

[0029] This electrical sensor 14 is connected on one side to the voltage source 16 via the electrical connection 51 and the drive-ready activation switch 15, and on the other side to the second ventilation arrangement 6 via an electrical connection 53. From this second ventilation arrangement 6, an electrical connection 49 leads to one pole of a voltage source 16. Another electrical connection 56 leads from the drive-ready activation switch 15 to an on-board electrical system of the towing vehicle (not shown). In the Fig. In the position shown in Figure 1, the two electromagnetic venting and aeration devices 5 and 6 are de-energized and held in this position by associated compression springs 54. Compressed air from the compressed air source 7 flows via the pneumatic connections 17, 18, and 21 to the trailer control valve 3 and further via the pressure relief valve 4, the pneumatic connection 19, the first electromagnetic venting and aeration device 5, and the pneumatic connection 20 also to the trailer control valve 3, thereby opening it and allowing compressed air to flow via the pneumatic connection 23 and the coupling head "brake" 9 to the trailer brakes, thus locking them.This switching position occurs automatically when the towing vehicle's readiness to drive is not activated, namely when the readiness to drive activation switch 15 interrupts the connection between the electrical connections 50 and 51, regardless of whether the electrical sensors 13, 14 for the electromagnetic ventilation devices 5, 6 are energized at that moment or not. This is the switching position of the two electromagnetic ventilation devices 5, 6 when the vehicle, consisting of the towing vehicle and trailer, is parked and the ignition key is removed.

[0030] When the ignition key is turned on or the vehicle readiness activation switch 15 is switched to energized, the voltage from the voltage source 16 is applied to the two electrical sensors 13 and 14. If the brake pedal 11 and the second electrical sensor 14 are not pressed, the parking brake actuator 14a energizes the two electromagnetic venting assemblies 5 and 6. In this situation, the two electromagnetic venting assemblies 5 and 6 assume their second switching position, in which the trailer control valve 3 is vented to the outside air via the pneumatic connections 20 and 22 through a venting device 55.Likewise, the pneumatic connection 21 is vented to the ambient atmosphere via the second venting arrangement 6 and the pneumatic connection 22 via the venting device 55, so that only atmospheric pressure is present at the coupling head “brake” 9 and the trailer brake is released.

[0031] When the driver deflects the brake pedal 11 to a predetermined degree, the current flow to the first electromagnetic venting arrangement 5 is interrupted and the first electromagnetic venting arrangement 5 returns to the switching position shown, so that an adjustable pneumatic pilot pressure is supplied to the trailer control valve 3 via the pressure limiting valve 4 and the control of a brake pressure to the trailer via the coupling head “brake” 9 causes, without hydraulic pressure from the hydraulic sensor 10 of the towing vehicle being applied to the trailer control valve 3 and thus the trailer brakes becoming effective before the wheel brake cylinders 12a, 12b of the towing vehicle respond.This has the advantage that the trailer's compressed air brake system responds at least as quickly as the towing vehicle's hydraulic brake system, since the pneumatic pressure build-up is very rapid due to the electrical control via the first electromagnetic venting and de-energizing arrangement 5, thus compensating for the delays inevitably caused in a compressed air brake system by the slower pneumatic pressure build-up compared to the hydraulic pressure build-up.

[0032] When the brake pedal 11 is pressed further, hydraulic pressure from the hydraulic sensor 10 of the towing vehicle is transferred via the hydraulic connections 26, 27 and 28, 29 to the trailer control valve 3 and causes the actual pneumatic brake pressure to build up, which correlates with the hydraulic pressure of the hydraulic sensor 10.

[0033] By actuating the second electrical sensor 14 by means of the parking brake actuating element 14a, the electrical current in the electrical connection 51 and the electrical connection 53 to the second ventilation arrangement 6 is interrupted, which is thereby routed to the Fig. The switching position shown in Figure 1 is returned by the pressure of spring 54, so that compressed air from the compressed air source 7 reaches the trailer control valve 3 via the pneumatic connections 17, 18, 21 and ultimately applies the trailer brake. The parking brake of the towing vehicle can also be activated by actuating the second electrical sensor 14 as described.

[0034] From the sectional drawing according to Fig. Figure 2 details the construction of the control unit 1. The trailer control valve 3, the pressure relief valve 4, the first electromagnetic venting and purging arrangement 5, and the second electromagnetic venting and purging arrangement 6 are arranged in the housing 2. The second electromagnetic venting and purging arrangement 6 is schematically shown in Figure 2. Fig. 1 shown because it is located in the housing 2 next to the first electromagnetic ventilation arrangement 5 outside the section plane of the Fig. 2 is located.

[0035] A brake pressure regulating valve 24 is formed by a pressure regulating valve plunger 33 with a valve seat 35 and a valve body 37, wherein the pressure regulating valve plunger 33 is acted upon by a compression spring 36, and the valve body 37 is in the Fig. In the position shown in section 2, the valve stem rests on a valve seat 57 of the housing 2. The compression spring 36 presses the pressure regulating valve stem 33 into the position shown in the diagram. Fig. Figure 2 shows the position in which the valve seat 35 does not rest on the valve body 37, but the valve body 37 rests axially against the valve seat 57 in the housing 2 under the action of a compression spring 38. In this position, the pressure from the compressed air source 7 is applied to the valve body 37 via the pneumatic connection 17. However, the pressure is prevented from reaching the pneumatic connection 23 because the valve body 37 rests on the valve seat 57 in the housing 2.

[0036] An actuating piston, consisting of a fan piston 30 and a diaphragm 31, is screwed onto the pressure regulating valve tappet 33. A fan disc 32 extends through the fan piston 30, thus enabling the effective area of ​​the actuating piston 30, 31 to be changed in a known manner. This is achieved by screwing the fan piston 30 more or less far onto the pressure regulating valve tappet 33, whereby the fan piston 30 is held in the selected position on the pressure regulating valve tappet 33 by means of a self-locking thread 34 in a known manner. The fan disc 32, together with the diaphragm 31, is clamped firmly and sealingly in the housing 2.

[0037] The valve body 37 is connected to the venting device 55 via a venting channel 39, so that in the Fig. In the position of the pressure control valve plunger 33 shown in Figure 2, there is an open flow path from the pneumatic connection 23 to the atmosphere, and the trailer brake system is therefore depressurized. In addition to the actuating piston, consisting of the fan piston 30 and the diaphragm 31, a pilot piston 25 acts on the pressure control valve plunger 33 in tandem with two relay pistons 40a and 40b. The first relay piston 40a is connected to a first brake circuit of the hydraulic master cylinder 10 via the hydraulic connections 27 and 26, and the other relay piston 40b is connected to a second brake circuit of the hydraulic master cylinder 10 of the towing vehicle via the hydraulic connections 29 and 28.

[0038] It is therefore a stepped piston arrangement consisting of the relay piston 40a with the smallest diameter, the relay piston 40b with a larger diameter and the control piston 25 with an even larger diameter.

[0039] The pneumatic connection 17 extends from the brake pressure regulating valve 24 to the pressure relief valve 4, which, in a known manner, has a piston 43 that is axially acted upon by a compression spring 45. A diaphragm 44 seals the pressure relief valve 4 against atmospheric pressure, which prevails in the area of ​​the compression spring 45. A pressure relief valve plunger 46 is attached to the piston 43. This plunger interacts with a valve plate 47 and generates an adjustable pilot pressure that is lower than the pneumatic pressure applied to the pneumatic connection 17. This pilot pressure can be adjusted by means of an adjusting device 48 in the form of an adjusting screw by increasing or decreasing the preload of the compression spring 45 through rotation of the adjusting device 48.

[0040] From the pressure relief valve 4, the set pilot pressure passes via the pneumatic connection 19, designed as a housing bore, to the first electromagnetic venting arrangement 5 in the form of a solenoid valve, and from there, in the de-energized state of the first electromagnetic venting arrangement 5, via the pneumatic connection 20 to an effective surface 25a of the pilot piston 25.

[0041] Furthermore, the full pressure from the compressed air source 7 is transferred via the pneumatic connections 17 and 18, the second venting arrangement 6 and the pneumatic connection 21 to the side 41 of the actuating piston facing the pilot piston 25, consisting of the fan piston 30 and the diaphragm 31, provided that the second venting arrangement 6 is in the position shown in Fig. 2 is in the unpowered position shown.

[0042] The same applies to the first electromagnetic venting and aeration arrangement 5, which is also de-energized, so that on the one hand the working surface 25a of the pilot piston 25 is pressurized with the set pilot pressure and on the other hand the actuating piston, consisting of the fan piston 30 and the diaphragm 31, is pressurized with the full pressure from the compressed air source 7 and the pressure regulating valve plunger 33 with its valve seat 35 is moved against the valve body 37 and lifts this valve body 37 from the valve seat 57, whereby compressed air from the pneumatic connection 17 via the brake pressure regulating valve 24 into the pneumatic connection 23 and from there to the coupling head “brake” 9. The trailer brakes are then locked, as already described with reference to the Fig. 1 was described.

[0043] When the readiness activation switch 15 is switched on, the two electromagnetic venting and purging devices 5, 6 are energized and open a flow path from the pneumatic connection 20 via the pneumatic connection 22 to the purging device 55, as well as a flow path from the pneumatic connection 21 to the pneumatic connection 22 and further also to the purging device 55. Accordingly, no pilot pressure acts on the working surface 25a of the pilot piston 25, and no pressure from the compressed air source 7 acts on the side 41 of the actuating piston facing the pilot piston 25, consisting of the fan piston 30 and the diaphragm 31. Therefore, the brake pressure regulating valve 24 accepts the pressure in Fig. 2 position shown, in which the pneumatic connection 23 is also vented and the trailer brakes are released.

[0044] When the brake pedal 11 is actuated, the first electromagnetic venting arrangement 5 is de-energized by the electrical sensor 13, and initially only the pilot pressure controlled by the pressure limiting valve 4 is directed via the pneumatic connections 19, 20 to the working surface 25a of the pilot piston 25, so that the pressure regulating valve plunger 33 is moved and, by means of its valve seat 35, lifts the valve body 37 from the valve seat 57 in the housing, so that compressed air passes from the pneumatic connection 17 to the pneumatic connection 23.This pressure acts on the side 42 of the actuating piston 30, 31 facing the brake pressure regulating valve 24 and moves it together with the pressure regulating valve plunger 33 against the pilot pressure acting on the working surface 25a of the pilot piston 25, until the valve body 37 rests again on the valve seat 57 in the housing 2 and closes the flow path between the pneumatic connection 17 and the pneumatic connection 23, thereby maintaining a brake pressure in the pneumatic connection 23 that correlates with the pilot pressure.

[0045] If the brake pedal 11 is pressed harder, hydraulic pressure from the hydraulic sensor 10 passes via the hydraulic lines 26, 27, 28, 29 to the relay pistons 40a and 40b, which move the pressure regulating valve plunger 33 again, so that the valve body 37 lifts off the valve seat 57 in the housing 2 again and a pressure increase occurs again in the pneumatic connection 23, which correlates with the hydraulic pressure acting on the wheel brake cylinders 12a, 12b of the towing vehicle and actuates the trailer brakes accordingly to a greater or lesser degree.

[0046] If the brake pedal 11 is no longer actuated, the hydraulic pressure in front of the relay piston 40a, 40b and the pneumatic pressure on the working surface 25a of the pilot piston 25 decrease, so that the pneumatic connection 23 becomes pressureless and the trailer brakes, as well as the brakes of the towing vehicle, are released again.

[0047] With the readiness activation switch 15 switched on and the foot brake lever 11 not actuated, the second electrical sensor 14 can be actuated by means of the parking brake actuating element 14a to de-energize the second venting assembly 6. In this state, the full pressure of the compressed air source 7 acts in the pneumatic connection 17 via the pneumatic connection 18, the second venting assembly 6, and the pneumatic connection 21 on the actuating piston consisting of the fan piston 30 and the diaphragm 31, so that the trailer brakes are applied and act as a parking brake. This second electrical sensor 14 can be arranged on a handbrake lever in the towing vehicle or act as a directly actuated parking brake activation switch, which also applies the parking brake of the towing vehicle.

[0048] Since the two electromagnetic ventilation arrangements 5, 6 are unpowered when the readiness activation switch 15 is not activated, the voltage source 16 is not loaded when the vehicle is stationary and therefore cannot discharge even if the vehicle is left standing for a longer period of time.

[0049] The in Fig. The pneumatic connections 17, 18, 19, 20, 21, 22, 23 shown can be provided as simple bores in the housing 2 or can also be cast into the housing 2.

[0050] By combining the functional elements in the single housing 2, screws and cables are eliminated, resulting in a very compact control unit 1. The integrated electric handbrake control eliminates the need for a mechanical handbrake linkage in the vehicle, thus also freeing up the fixed installation location. The installation location is therefore much more flexible, taking the mounting position into account.

[0051] All features mentioned in the aforementioned figure description, claims, and introduction can be used individually or in any combination. The invention is therefore not limited to the described and claimed combinations of features. Rather, all combinations of features are to be considered disclosed. Reference symbol list (part of the description) 1 control unit 2 cases 3 Trailer control valve 4 Pressure relief valve 5 First electromagnetic ventilation arrangement 6 Second electromagnetic ventilation arrangement 7 Compressed air source 8 Coupling head “Supply” 9 Coupling head “brake” 10 Hydraulic sensor of the towing vehicle 11 Brake pedal 12a Wheel brake cylinder of the towing vehicle 12b Wheel brake cylinder of the towing vehicle 13 Electrical sensor on the brake pedal 11, first sensor 14 Electric parking brake sensor, second sensor 14a Parking brake actuation element 15 Drive readiness activation switches 16 Voltage source 17 Pneumatic connection 18 Pneumatic connection 19 Pneumatic connection 20 Pneumatic connection 21 Pneumatic connection 22 Pneumatic connection 23 Pneumatic connection 24 Brake pressure regulating valve 25 pilot pistons 25a Effective area of ​​the pilot piston 25 26 Hydraulic connection 27 Hydraulic connection 28 Hydraulic connection 29 Hydraulic connection 30 fan pistons, part of the actuating piston of the brake pressure regulating valve 31 Membrane, component of the actuating piston of the brake pressure regulating valve 32 flap disc 33 valve tappets 34 threads 35 Valve seat on the valve tappet 33 36 Compression spring on the valve tappet 33 37 Valve bodies 38 Compression spring on the valve body 37 39 Ventilation duct 40a Relay piston 40b relay piston 41 Side of the actuating piston 30, 31 facing the pilot piston 25 42 Side of the actuating piston 30, 31 facing the brake pressure regulating valve 24 43 Pistons of the pressure relief valve 4 44 Diaphragm of the pressure relief valve 4 45 Compression spring of the piston 43 46 Pressure relief valve plunger 47 Valve plate 48 Adjustment device 49 Electrical connection 50 Electrical connection 51 Electrical connection 52 Electrical connection 53 Electrical connection 54 Compression spring 55 Venting device 56 Electrical connection to the vehicle electrical system 57 Valve seat in housing 2

Claims

Control unit (1) for a towing vehicle with hydraulically actuated brakes (12a, 12b) and a trailer coupling thereto having a two-line compressed air brake system, comprising a hydraulic sensor (10) of the towing vehicle, a trailer control valve (3) on the towing vehicle which can be pressurized with hydraulic pressure by the hydraulic sensor (10) of the towing vehicle, a brake pressure regulating valve (24) integrated into the trailer control valve (3) for compressed air supplied to the trailer control valve (3) from a compressed air source (7), and a first electromagnetic venting arrangement (5) for controlled compressed air supply and venting of a pilot piston (25) in the trailer control valve (3) which actuates the brake pressure regulating valve (24), wherein the first electromagnetic venting arrangement (5) is arranged and configured such that in a first switching position it establishes a pneumatic connection (19,20) between a pressure relief valve (4) for compressed air supplied to the pressure relief valve (4) from the compressed air source (7) and the pilot piston (25) in the trailer control valve (3), that in the first switching position it closes a connection (20, 22) between the pilot piston (25) in the trailer control valve (3) and a venting device (55), and that in a second switching position it closes the pneumatic connection (19, 20) from the pressure relief valve (4) to the pilot piston (25) in the trailer control valve (3) and opens the pneumatic connection (20, 22) from the pilot piston (25) in the trailer control valve (3) to the venting device (55), wherein the electromagnetic venting arrangement (5), controlled by an electrical sensor (13) on the hydraulic sensor (10) of the towing vehicle, assumes the first switching position as soon as the hydraulic sensor (10) is activated is, and assumes the second switching position,when the hydraulic sensor (10) is deactivated, characterized in that the first electromagnetic venting and aeration arrangement (5) assumes the first switching position when the towing vehicle's readiness to drive is deactivated and assumes the second switching position when the towing vehicle's readiness to drive is activated. Control unit according to claim 1, characterized in that the electrical sensor (13) consists of a switching element on a brake pedal (11) for actuating the hydraulic sensor (10). Control unit according to claim 1 or 2, characterized in that a second electromagnetic venting arrangement (6) is arranged and configured to open a pneumatic connection (17, 18, 21) between the compressed air source (7) and an actuating piston (30, 31) of the brake pressure regulating valve (24) in a first switching position and to close a pneumatic connection (22) to a venting device (55), and in a second switching position to close the pneumatic connections (17, 18) to the compressed air source (7) and to open the pneumatic connection (21) from the actuating piston (30, 31) to the venting device (55), wherein the second electromagnetic venting arrangement (6), controlled by a second electrical sensor (14) on a parking brake actuating element (14a), assumes the first switching position when the parking brake actuating element (14a) is activated, and assumes the second switch position,when the parking brake actuation element (14a) is deactivated. Control unit according to claim 3, characterized in that the second electrical sensor (14) consists of a switching element on a handbrake lever or on a parking brake activation switch. Control unit according to one of claims 1 to 4, characterized in that alternatively or additionally the second electromagnetic ventilation arrangement (6) assumes the first switching position when the driving readiness of the towing vehicle is deactivated and assumes the second switching position when the driving readiness of the towing vehicle is activated. Control unit according to one of claims 1 to 5, characterized in that the electromagnetic ventilation arrangements (5, 6) are configured to assume the first switching position in the de-energized state and the second switching position in the energized state. Control unit according to one of claims 1 to 6, characterized in that the electromagnetic venting and aeration arrangements (5, 6) are designed as 3 / 2-way valves. Control unit according to one of claims 1 to 7, characterized in that the pressure limiting valve (4) is adjustable from the outside by means of an adjusting device (48). Control unit according to one of claims 1 to 8, characterized in that the pilot piston (25) is designed as a stepped piston in tandem with relay pistons (40a, 40b) in the trailer control valve (3) which can be actuated by hydraulic pressure from the hydraulic sensor (10) of the towing vehicle, and that the pilot piston (25) actuates the brake pressure control valve (24) via a pressure control valve plunger (33). Control unit according to claim 9, characterized in that the actuating piston (30) of the brake pressure control valve (24) is arranged on the pressure control valve plunger (33) and can be supplied with compressed air from the compressed air source (7) via the second electromagnetic venting arrangement (6) on the side (41) facing the pilot piston (25) and can be supplied with regulated brake pressure on the side (42) facing the brake pressure control valve (24). Control unit according to claim 10, characterized in that the actuating piston of the brake pressure regulating valve (24) consists of a fan piston (30) with a diaphragm (31) having an effective surface that can be changed by means of a fan disc (32), that the fan piston (30) is attached to the pressure regulating valve tappet (33) by means of a thread (34), and that the effective surface of the fan piston (30) can be changed by rotating the pressure regulating valve tappet (33) relative to the fan piston (30). Control unit according to one of claims 1 to 11, characterized in that the trailer control valve (3) with the brake pressure regulating valve (24), the pressure limiting valve (4) and at least the first electromagnetic venting and aeration arrangement (5) are arranged in a single housing (2; 2a, 2b), and that the pneumatic connections (17, 18, 19, 20, 21, 22) between these functional elements (3, 4, 5, 24) are formed by correspondingly extending channels in the housing (2; 2a, 2b). Control unit according to claim 12, characterized in that the second electromagnetic ventilation arrangement (6) is also arranged in the unified housing (2; 2a, 2b).

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