TRAILER CONTROL VALVE OF A TOWING VEHICLE

Description

[0001] The invention relates to a trailer control valve of a towing vehicle for controlling a hydraulic dual-line brake system of a trailer, with a supply pressure inlet for connecting a hydraulic supply line of the towing vehicle, with a tank outlet for connecting a pressureless return line of the towing vehicle, with a brake pressure outlet for connecting a brake line of the trailer, and with an additional pressure outlet for connecting an additional line of the trailer, in which the brake pressure outlet can be connected in stages to the supply pressure inlet or to the tank outlet by means of an electronically controllable brake control valve, and in which the additional pressure outlet can be connected via a valve arrangement with at least one electronically controllable valve either to the supply pressure inlet or to the tank outlet by reducing an output pressure of the supply pressure to an additional pressure.

[0002] According to EU Regulation No. 2015 / 68, which applies to braking systems on vehicles and trailers primarily intended for use in agriculture and forestry, only vehicles and trailers with dual-line braking systems can be newly registered from the dates specified therein. This applies to both vehicles and trailers equipped with compressed air braking systems and vehicles and trailers with hydraulic braking systems.

[0003] In the case of trailers with dual-line compressed air brake systems, a supply line, which is under high supply pressure during operation, for transmitting compressed air as an energy source and a brake control line for transmitting a variable brake control pressure for controlling a brake control valve in the trailer are provided between the towing vehicle and the trailer, in analogy to trailers primarily intended for road traffic.

[0004] In contrast, in the case of trailers with a hydraulic braking system, a brake line is provided between the towing vehicle and the trailer for transmitting pressurised oil as an energy carrier and a variable brake pressure between 0 and 150 × 10 5< Pa for actuating the service brakes of the trailer, as well as an additional line for transmitting a constant additional pressure between 15 × 10 5< Pa and 35 × 10 5< Pa for controlling safety functions of the braking system of the trailer.The safety functions are as follows: the triggering of an emergency brake on the trailer in the event of a break in the brake line and / or the additional line, the triggering of an emergency brake on the trailer in the event of an emergency stop switch in the towing vehicle being operated, the triggering of an auxiliary brake on the trailer via a pressure accumulator in the trailer in the event of a sharp actuation of the brake pedal in the towing vehicle and, if the trailer is equipped with spring brake cylinders, the engagement and disengagement of the parking brake on the trailer.

[0005] EP 3 266 661 B1 discloses a hydraulic braking system for a trailer vehicle, which is intended for operating a hydraulic dual-line braking system of the trailer vehicle, but is also compatible with a trailer control valve of a towing vehicle for a single-line braking system of a trailer vehicle. The braking system comprises a coupling assembly, a valve assembly, and a pressure control group. The coupling assembly has a connecting coupling for connecting a brake line connectable to a brake line coupling of the towing vehicle, a connecting coupling for connecting an additional line connectable to an additional line coupling of the towing vehicle, and a short-circuit coupling. In a trailer control valve of the towing vehicle designed for a hydraulic dual-line braking system of the trailer vehicle, the brake line and the additional line are connected to the corresponding couplings of the towing vehicle.In the case of a trailer control valve designed for a hydraulic single-line braking system of the trailer vehicle, the brake line is connected to the brake line coupling of the towing vehicle and the towing vehicle-side end of the additional line is connected to the short-circuit coupling of the trailer vehicle or the coupling assembly.

[0006] The valve assembly comprises a pressure-controlled 3 / 2-way switching valve and a manually operated 2 / 2-way switching valve. The 3 / 2-way switching valve is largely controlled by the auxiliary pressure present in the auxiliary line. At low auxiliary pressure, the 3 / 2-way switching valve is in its rest position, in which the brake line is connected to a pressure accumulator and an inlet of the pressure control group via a check valve that blocks the reverse flow direction. At high auxiliary pressure, the 3 / 2-way switching valve is in its switching position, in which the brake line connection coupling is directly connected to the inlet of the pressure control group and to the pressure accumulator via a check valve that blocks the reverse flow direction. Using the 2 / 2-way switching valve, the pressure accumulator can be emptied as needed when the brake line is depressurized. The pressure control group has a pressure control valve which is designed as a 2 / 2-way proportional solenoid valve.The proportional valve, whose output pressure port is connected to the trailer's wheel brake cylinders, serves to modulate the brake pressure acting in the wheel brake cylinders depending on the trailer's load. Further properties and the functionality of this well-known hydraulic braking system in specific operating situations can be found in a detailed description in EP 3 266 661 B1.

[0007] Furthermore, EP 3 353 027 B1 describes a hydraulic braking system for a trailer vehicle, which comprises a trailer control valve arranged in a towing vehicle and a valve module arranged in the trailer vehicle, which are connected to one another via a brake line and an auxiliary line. The trailer control valve has a supply pressure inlet for connecting a hydraulic supply line of the towing vehicle carrying a supply pressure, a tank outlet for connecting a pressureless return line of the towing vehicle, a brake pressure outlet for connecting the brake line, and an auxiliary pressure outlet for connecting the auxiliary line. The brake pressure outlet can be connected in stages to the supply pressure inlet or the tank outlet via a brake control valve designed as a proportional solenoid valve.The auxiliary pressure output can also be connected to the supply pressure inlet or the tank outlet via an auxiliary control valve designed as a proportional solenoid valve. To detect the brake pressure present at the brake pressure outlet, a pressure sensor is connected between the working outlet of the brake control valve and the brake pressure outlet. To measure the auxiliary pressure present at the auxiliary pressure outlet, a pressure sensor is connected between the working outlet of the auxiliary control valve and the control pressure outlet.

[0008] The valve module features a pressure-controlled 3 / 2-way switching valve and a pressure-controlled 3 / 3-way proportional valve. The 3 / 2-way switching valve, which is connected to the brake line on the inlet side and controlled by the pressure difference between the brake pressure and the accumulator pressure of a connected pressure accumulator, fills the pressure accumulator with a pressure medium, provided the accumulator pressure is lower than the brake pressure.The 3 / 3-way proportional valve, which is connected on the inlet side via the 3 / 2-way switching valve to the brake line and directly to the pressure accumulator, and which is controlled by the pressure difference between the brake pressure in a main brake line connected on the outlet side for actuating the trailer's service brakes and the brake pressure and the auxiliary pressure, connects the main brake line either to the brake line and the accumulator reservoir, or only to the brake line, or only to the accumulator reservoir. The auxiliary line, on the other hand, is only connected via a connecting line to a parking brake line for engaging and disengaging the trailer's parking brakes, which are actuated by spring-loaded brake cylinders.

[0009] EP 3 353 027 B1 relates to a system and method for operating a hydraulic vehicle trailer brake using a hydraulic fluid supply provided on a vehicle, wherein a control line and an additional line are arranged between the vehicle and a vehicle trailer for supplying hydraulic fluid to and from the trailer.

[0010] Against this background, the object of the invention is to present a trailer control valve of a towing vehicle for controlling a hydraulic dual-line brake system of a trailer vehicle of the type mentioned above, which is constructed as simply and cost-effectively as possible and meets the requirements for controlling the brake system of the trailer vehicle according to the EU Regulation 2015 / 68 mentioned above.

[0011] This object is achieved with a trailer control valve having the features of claim 1. The same applies to a trailer control valve having the features of independent claim 2, in which two valves are interchanged in their arrangement. The dependent claims define advantageous embodiments of these trailer control valves.

[0012] Accordingly, the invention, according to the first variant defined in claim 1, relates to a trailer control valve of a towing vehicle for controlling a hydraulic dual-line brake system of a trailer. This trailer control valve has a supply pressure inlet for connecting a hydraulic supply line of the towing vehicle, a tank outlet for connecting a pressureless return line of the towing vehicle, a brake pressure outlet for connecting a brake line of the trailer, and an auxiliary pressure outlet for connecting an auxiliary line of the trailer. The brake pressure outlet can be connected in stages to the supply pressure inlet or to the tank outlet by means of an electronically controllable brake control valve.In addition, the additional pressure output can be connected to the supply pressure inlet or to the tank outlet via a valve arrangement with at least one electronically controllable valve, either by reducing an output pressure of the supply pressure to an additional pressure.

[0013] In this trailer control valve, in order to achieve the stated object, it is provided that the valve arrangement has a pressure relief valve and a shut-off valve, that the pressure relief valve and the shut-off valve are arranged in series one after the other, wherein the shut-off valve is arranged downstream of the pressure relief valve in terms of flow technology, that the output pressure of the valve arrangement can be reduced to the additional pressure by means of the pressure relief valve, and that the shut-off valve is designed as a 3 / 2-way solenoid switching valve, via which the additional pressure output is connected to the tank output in its de-energized state and to the working output of the pressure relief valve in its energized state.

[0014] According to the second variant defined in claim 2, the invention relates to the same trailer control valve of a towing vehicle for controlling a hydraulic dual-line brake system of a trailer. This trailer control valve also has a supply pressure inlet for connecting a hydraulic supply line of the towing vehicle, a tank outlet for connecting a pressureless return line of the towing vehicle, a brake pressure outlet for connecting a brake line of the trailer, and an auxiliary pressure outlet for connecting an auxiliary line of the trailer. The brake pressure outlet can also be connected to the supply pressure inlet or to the tank outlet in a graduated manner using an electronically controllable brake control valve.In addition, the additional pressure output can be connected to the supply pressure inlet or to the tank outlet via a valve arrangement with at least one electronically controllable valve, either by reducing an output pressure of the supply pressure to an additional pressure.

[0015] In this second variant of the trailer control valve according to the invention, the object is achieved by providing that the valve arrangement has a pressure relief valve and a shut-off valve, that the pressure relief valve and the shut-off valve are arranged in series one behind the other, wherein the shut-off valve is arranged fluidically upstream of the pressure relief valve, that the output pressure of the valve arrangement can be reduced to the additional pressure by means of the pressure relief valve, and that the shut-off valve is designed as a 3 / 2-way solenoid valve, via which the additional pressure outlet is connected to the tank outlet in its de-energized state and to the supply pressure inlet in its energized state.

[0016] By using the pressure relief valve and the shut-off valve, the valve arrangement with the features of the invention is easier to control and less susceptible to failure than a proportional solenoid valve. By means of the pressure relief valve, the supply pressure applied on the input side is automatically reduced to the additional pressure, i.e., without active control. Only the shut-off valve must be actively controlled or energized via a control unit if, depending on the arrangement of the valves, the additional pressure or the supply pressure is to be forwarded to the additional pressure output S or the pressure relief valve. When the shut-off valve is de-energized, the additional pressure output S is pressurized or depressurized, which automatically brakes the trailer.

[0017] To detect the additional pressure present at the additional pressure output S, it is advantageous to have an electro-hydraulic pressure sensor or an electro-hydraulic pressure switch connected to the additional line inside or outside the trailer control valve close to the additional pressure output S. Based on the pressure signal from the pressure sensor or the switching signal from the pressure switch, which is actuated at a pressure slightly below the intended additional pressure, it can be determined whether or not the intended additional pressure is present at the additional pressure output S when the shut-off valve is energized. If the pressure present at the additional pressure output S is too low, it is assumed that there is a leak in the additional line or a malfunction in the trailer's braking system, which then leads to at least the shut-off valve being switched off and thus to emergency braking of the trailer.

[0018] The brake control valve is preferably designed as a 3 / 3-way proportional solenoid valve or as a 3 / 2-way proportional solenoid valve with a valve spring-side feedback of the applied brake pressure to the valve piston. Via this valve spring, the brake pressure output is connected unthrottled to the tank outlet in the de-energized state and unthrottled to the reservoir pressure inlet in the maximum energized state. Due to the feedback of the brake pressure to the valve piston, the brake control valve can be controlled solely via an electrical control current based on a characteristic curve stored in the control unit.

[0019] However, an electro-hydraulic pressure sensor inside or outside the trailer control valve near the brake pressure output C can be connected to the brake line to detect the brake pressure present at the brake pressure output C. However, this pressure sensor only serves to detect a leak in the brake line or a malfunction in the trailer's braking system, which leads to the deactivation of the brake control valve and the shut-off valve, thus resulting in emergency braking of the trailer.

[0020] A varying supply pressure applied to the supply pressure input P can lead to slight changes in the control characteristic of the brake control valve. Therefore, according to another development of the invention, it is advantageous if, to detect the supply pressure applied to the supply pressure input P, an electro-hydraulic pressure sensor is connected to the supply line inside or outside the trailer control valve near the supply pressure input P. Thus, depending on the current supply pressure, the optimal characteristic for controlling the brake control valve can be selected and used.

[0021] To detect the coupling status of a trailer, i.e., to determine whether a trailer is coupled or not, according to another embodiment, an electrical signal line is connected directly or via the trailer control valve to an associated electronic control unit. This signal line is typically connected to the 7-pin or 13-pin socket for the trailer's connector plug. If a coupled trailer is detected when the towing vehicle is started up, this can be used to automatically fill a pressure accumulator in the trailer by applying maximum current to the brake control valve for a few seconds, thereby pumping pressurized oil into the trailer's brake line.In contrast, the shut-off valve and the brake control valve will not be switched if it is detected that no trailer is coupled, so that the additional pressure output and the brake pressure output will then remain depressurized.

[0022] To enable the control of brake pressure for the trailer vehicle even in the event of a defect in the brake control valve or its control, a brake pressure input PB, PB' connected to a brake line of the towing vehicle and a redundant control branch with a pressure-controlled relay valve for brake pressure-controlled control of brake pressure and a redundancy valve for activating and deactivating the redundant control branch are advantageously provided. The redundancy valve activates the relay valve as needed, whereby the brake pressure applied at the brake pressure output C is adjusted via the relay valve, controlled by the brake pressure, instead of via an electronic control via the brake control valve.

[0023] For this purpose, the relay valve is connected to the supply pressure inlet P, to the tank outlet T and, via a shuttle valve, to the brake pressure outlet C, and is provided with a control inlet. The redundancy valve is preferably designed as a 3 / 2-way solenoid valve, by means of which, in the de-energized state, the control inlet of the relay valve is connected to the brake pressure inlet PB, PB' and, in the energized state, depending on the design of the towing vehicle's braking system (pneumatic or hydraulic), to a vent outlet or to the tank outlet T.

[0024] If the shut-off valve is arranged upstream of the pressure relief valve, the relay valve can be connected via a connecting line to the connecting line between the shut-off valve and the pressure relief valve instead of being connected to the supply pressure inlet P. The supply pressure is present when the shut-off valve is energized. Thus, when the shut-off valve is switched off, both the auxiliary pressure outlet S and the supply inlet of the relay valve are vented via the shut-off valve, thus depressurizing them.

[0025] In order to avoid an unintentional switching off of the shut-off valve and thus the deactivation of the redundant control branch in this embodiment, the shut-off valve is preferably protected against a failure due to a fault by a control within the associated electronic control unit that maintains the last switching state.

[0026] Alternatively or additionally, a second shut-off valve can be connected in parallel to the shut-off valve for this purpose. The working outputs of the two shut-off valves are connected to the connecting line leading to the pressure relief valve via a shuttle valve. This allows the supply of pressurized oil at the reservoir pressure to the connecting line via the other shut-off valve in the event of a failure in one of the two shut-off valves. For cost reasons, the second shut-off valve is preferably of the same design as the first shut-off valve.

[0027] Another way to prevent unintentional deactivation of the shut-off valve is to install a check valve in the connecting line between the shut-off valve and the connection of the connecting line leading to the relay valve. This check valve has a control input that blocks the shut-off valve and can be released by an applied control pressure. It has a control input to which an electronically controllable pilot valve is connected. This pilot valve is designed as a 3 / 2-way solenoid valve, by means of which the control input of the check valve is connected to the tank outlet T when de-energized and to the supply pressure inlet P when energized.Due to the pilot-operated check valve in the connecting line mentioned, the inlet of the pressure relief valve and the supply inlet of the relay valve can only be ventilated and thus depressurized by active control, i.e. by energizing the pilot valve, when the shut-off valve is not energized.

[0028] At least the brake control valve, the pressure relief valve, the shut-off valve, the relay valve, the redundancy valve, and the shuttle valve are connected to each other via plug-in connections and / or screw connections, thus forming the trailer control valve, which can thus be easily installed in the towing vehicle and removed for maintenance and repair work, as well as for replacement. If necessary, the pressure sensors and / or the aforementioned pressure switch can also be connected to the aforementioned valves via plug-in connections and / or screw connections.

[0029] Alternatively, at least the brake control valve, the pressure relief valve, the shut-off valve, the relay valve, the redundancy valve, and the shuttle valve can be arranged in a common valve housing for the same purpose, thus forming the trailer control valve. Here, too, the pressure sensors and / or the pressure switch can be arranged inside the valve housing or on the outside of the valve housing, as required.

[0030] The trailer control valve with the features of the invention is explained in more detail below with reference to exemplary embodiments shown in the accompanying drawings. The drawing shows schematic illustrations Fig. 1 a basic version of the trailer control valve according to the invention in a braking system of a towing vehicle, Fig. 2 an alternative basic version of the trailer control valve, Fig. 3 an extension of the trailer control valve according to Fig. 1 , Fig. 4 an alternative extension of the trailer control valve according to Fig. 1 , Fig. 5 an extension of the trailer control valve according to Fig. 3 , Fig. 6 an extension of the trailer control valve according to Fig. 2 , Fig. 7 a first development of the trailer control valve according to Fig. 6 , and Fig. 8 an alternative second development of the trailer control valve according to Fig. 6 .

[0031] In the Fig. 1 A braking system 2 of a towing vehicle, a trailer control valve 4 arranged in the towing vehicle and an electronic control unit 6 associated therewith are shown. The trailer control valve 4 serves to control a hydraulic dual-line braking system of a coupled trailer vehicle. Fig. 1 The braking system 2 of the towing vehicle, which is only partially shown, is in this case an example of a compressed air braking system which has a compressor 8 and a processing unit 10. From the processing unit 10, a first pneumatic supply line 12 for a first service brake circuit and a second pneumatic supply line 14 for a second service brake circuit are led to a foot brake valve 16. By means of the foot brake valve 16, a brake pressure can be controlled into a brake line 18 of the first service brake circuit and into a brake line 20 of the second service brake circuit. To measure the brake pressures controlled there, an electropneumatic pressure sensor 22, 24 acting as a brake value transmitter is connected to the brake lines 18, 20 and to the control unit 6 via sensor lines shown with dashed lines.In addition, a further pneumatic supply line 26 is led from the processing unit 10 to a parking brake valve 28, by means of which a parking release pressure can be applied to a connected parking brake line 30. To measure the parking release pressure, an electropneumatic pressure sensor 32 acting as a parking brake sensor is connected to the parking brake line 30 and to the control unit 6 via a sensor line.

[0032] The trailer control valve 4 has a supply pressure inlet P, a tank outlet T, a brake pressure outlet C and an additional pressure outlet S and comprises a brake control valve 34, a pressure relief valve 36 and a shut-off valve 38. A hydraulic supply line 44 is connected to the supply pressure inlet P and is fed by an oil pump 40 and a treatment unit 42 arranged downstream of the latter. A return line 46 is connected to the tank outlet T and leads to a collecting tank 48. A brake line 50 is connected to the brake pressure outlet C and leads to a brake coupling 52 for connecting a trailer-side brake line. An additional line 54 is connected to the additional pressure outlet S and leads to an additional coupling 56 for connecting an additional trailer line.In addition, a signal line 58 is routed from the control unit 6 via the trailer control valve 4 to a connector socket 60 for connecting a trailer-side signal line. The trailer control valve 4 can be formed by mechanically and hydraulically connecting the aforementioned valves 34, 36, 38 via plug connections and / or screw connections, or by arranging them in a common valve housing 62.

[0033] The brake control valve 34 is designed as a 3 / 3-way proportional solenoid valve with a valve spring-side feedback of the applied brake pressure to the valve piston and is connected to the control unit 6 via an electrical control line. It should be noted here that all electrical control lines are shown with a dashed line. The brake control valve 34 serves to control a brake pressure at the brake pressure output C between 0 Pa and 150 × 10 5< Pa depending on a braking value measured by at least one of the pressure sensors 22, 24. Via the brake control valve 34, the brake pressure output C is connected unthrottled to the tank outlet T (0 Pa) in the de-energized state and unthrottled to the reservoir pressure inlet P at a pressure there of, for example, 150 × 10 5< Pa.

[0034] When the towing vehicle is put into operation, the brake pressure output C can be subjected to the maximum brake pressure (150 × 10 5< Pa) for a few seconds by applying maximum current to the brake control valve 34 in order to fill a pressure accumulator of the trailer with hydraulic oil under high pressure, provided that a coupled trailer has previously been detected via the signal line 58 (with the trailer plug connected).

[0035] By means of the pressure relief valve 36, the supply pressure applied on the inlet side is reduced on the outlet side to a constant additional pressure between 15 × 10 5< Pa to 35 × 10 5< Pa. The shut-off valve 38, which in this case is arranged pneumatically downstream of the pressure relief valve 36, is designed as a 3 / 2-way solenoid valve and is connected to the control unit 6 via an electrical control line. By means of this shut-off valve 38, the additional pressure output S is connected to the tank output T (0 Pa) in the de-energized state and to the working output of the pressure relief valve 36 in the energized state, which can have a hydraulic pressure of 15 × 10 5< Pa to 35 × 10 5< Pa.

[0036] After the relevant towing vehicle has been put into operation, the additional pressure output S is pressurized with the intended additional pressure (15 × 10 5< Pa to 35 × 10 5< Pa) by energizing the cut-off valve 38 when the parking brake is released, which is detected by the parking brake sensor 32, provided that a coupled trailer was previously detected via the signal line 58. If a fault is subsequently detected in the braking system of the trailer vehicle 4 or an emergency stop switch is actuated in the towing vehicle or the parking brake of the towing vehicle is engaged by actuating the parking brake valve 28, the additional pressure output S is depressurized by switching off the cut-off valve 38, thereby triggering emergency braking or auxiliary braking of the trailer vehicle. The described basic design of the trailer control valve 4 is advantageously effective without a pressure sensor connected to the brake line 50 and / or the additional line 54.

[0037] The Fig. 2 The trailer control valve 4' shown differs from the trailer control valve 4 according to Fig. 1 Essentially, in the valve arrangement 39', the shut-off valve 38 is now hydraulically arranged downstream of the pressure relief valve 36. As a result, the inlet of the pressure relief valve 36 is now connected via the shut-off valve 38 to the tank outlet T (0 Pa) in the de-energized state and to the reservoir pressure inlet P (150 × 10 5 < Pa) in the energized state.

[0038] In this embodiment, the brake control valve 34' is designed as a 3 / 2-way proportional solenoid valve with a valve spring-side feedback of the applied brake pressure to the valve piston, which is controlled by the control unit 6. In the de-energized state of the brake control valve 34', the brake pressure output C of the trailer control valve 4' is connected unthrottled to the tank outlet T, and in the maximum energized state, it is connected unthrottled to the hydraulic reservoir pressure input P.

[0039] In addition, in the embodiment according to Fig. 2 The brake system 2' of the towing vehicle is designed as a hydraulic brake system. Accordingly, the relevant supply lines 12', 14', 26' are now connected to the treatment unit 42' downstream of the oil pump 40, and the supply pressure input P of the trailer control valve 4' is connected to the supply line 12' of the first service brake circuit. A travel sensor 64 is provided as a brake value transmitter, for example. This travel sensor is arranged on the foot brake valve 16' and is connected to the control unit 6 via a sensor line. The switching state of the parking brake valve 28' is now detected by a switching sensor 66 acting as a parking brake sensor, which is connected to the control unit 6 via a sensor line.

[0040] In Fig. 3 A trailer control valve 68 having the features of the invention is shown, which in comparison with the trailer control valve 4 according to Fig. 1 by means of three electro-hydraulic pressure sensors 70, 72, 74. The first pressure sensor 70 is connected to the aforementioned hydraulic supply line 44 and via a sensor line to the control unit 6. By measuring the supply pressure present at the supply pressure inlet P, a more precise adjustment of the brake pressure present at the brake pressure outlet C via the brake control valve 34 is possible, since, depending on the supply pressure on the input side, slight changes to the control characteristic curve for the brake control valve 34 stored in the control unit 6 can occur. Thus, depending on the current supply pressure, the optimal characteristic curve for controlling the brake control valve 34 can be selected and used.

[0041] The second pressure sensor 72 is connected to the brake line 50 and linked to the control unit 6 via a sensor line. By measuring the brake pressure present at the brake pressure output C, a deviation from the brake pressure to be set via the brake control valve 34 can be detected, which may indicate a defect in the trailer-side braking system or a leak in the brake line 50. Accordingly, a visual or acoustic warning signal can be issued in the driver's cab of the towing vehicle and / or an emergency braking of the trailer can be triggered by deactivating the brake control valve 34 and the shut-off valve 38, and the escape of pressurized oil into the environment can be prevented.

[0042] The third pressure sensor 74 is connected to the auxiliary line 54 and linked to the control unit 6 via a sensor line. By measuring the auxiliary pressure present at the auxiliary pressure output S, a deviation from the auxiliary pressure set via the pressure relief valve 36 can be detected, which indicates a defect in the trailer-side braking system or a leak in the auxiliary line 58. Accordingly, a visual or acoustic warning signal can be issued in the driver's cab of the towing vehicle and / or an emergency braking of the trailer can be triggered by deactivating at least the shut-off valve 38, preventing the escape of pressurized oil into the environment.

[0043] In the illustration of the Fig. 3 The three aforementioned pressure sensors 70, 72, 74 are arranged within the trailer control valve 68. This is intended to illustrate that the pressure sensors 70, 72, 74 can be connected to the respective lines or valves 34, 36, 38 via plug connections and / or screw connections, and can thus form the trailer control valve 68. It is also clarified that these pressure sensors 70, 72, 74 can be arranged together with the respective valves 34, 36, 38 and lines in a common valve housing 76. However, it is also possible for the pressure sensors 70, 72, 74 to be connected outside the trailer control valve 68 to the respective pressure line 44, 50, 54.

[0044] The Fig. 4 The further embodiment of a trailer control valve 68' having the features of the invention shown differs from the trailer control valve 68 according to Fig. 3 in that, instead of the pressure sensor 74 between the shut-off valve 38 and the auxiliary pressure output S, an electro-hydraulic pressure switch 78 is now connected to the auxiliary line 54 and via a signal line to the control unit 6. Based on the switching signal of the pressure switch 78, which is actuated at a pressure slightly below the intended auxiliary pressure, the control unit 6 can detect whether the intended auxiliary pressure is present at the auxiliary pressure output S when the shut-off valve 38 is energized or not. If the pressure at the auxiliary pressure output S is too low, a malfunction in the trailer's braking system or a leak in the auxiliary line 58 is assumed, which leads to the shutdown of at least the shut-off valve 38 and thus to emergency braking of the trailer. Fig. 4 It is also made clear that even if the brake system 2 of the towing vehicle is designed as a compressed air brake system, instead of the Fig. 1 and Fig. 3 arranged pressure sensors 22, 24, 32, an actuating travel sensor 64' arranged on the foot brake valve 16 can be used as a brake value transmitter and a switching sensor 66' arranged on the parking brake valve 28 can be used as a parking brake sensor.

[0045] In Fig. 5 A trailer control valve 80 is shown, which in comparison with the trailer control valve according to Fig. 3 by means of a pneumatic brake pressure input PB and a redundant control branch 82. The pneumatic brake pressure input PB is connected to the brake line 20 of the second brake circuit of the towing vehicle via a connecting line 84. The redundant control branch 82 comprises a pneumatically pressure-controlled relay valve 86, a redundancy valve 88 and a shuttle valve 90. The relay valve 86 is connected to the supply pressure inlet P, the tank outlet T and via the shuttle valve 90. The working outlet of the brake control valve 34 and the brake pressure outlet C are also connected to the shuttle valve 90. The control input of the relay valve 86 can be connected to the brake pressure inlet PB via the redundancy valve 88. The redundancy valve 88 is designed as a 3 / 2-way solenoid valve and is connected to the control unit 6 via an electrical control line.

[0046] The control input of relay valve 86 is connected to the brake pressure input PB via the redundancy valve 88 when de-energized and to a venting output when energized. Thus, relay valve 86 and thus the redundant control branch 82 are activated when the redundancy valve 88 is de-energized and deactivated when the redundancy valve 88 is energized. In the event of a failure of control unit 6, the brake control valve 34 is automatically deactivated and the redundant control branch 82 is activated, ensuring the application of brake pressure to the brake pressure output C under all circumstances during driving.

[0047] The trailer control valve 80 can be formed by connecting the aforementioned valves 34, 36, 38, 86, 88, 90 to one another via plug-in and / or screw connections or by arranging them in a common valve housing 92. In the present case, the three aforementioned pressure sensors 70, 72, 74 are also arranged within the trailer control valve 80. This illustrates that the pressure sensors 70, 72, 74 can be connected to the respective valves 34, 36, 38, 86, 88, 90 via plug-in and / or screw connections and thus form the trailer control valve 80, or that the pressure sensors 70, 72, 74 can be arranged together with the respective valves 34, 36, 38, 86, 88, 90 in a common valve housing 92. However, it is also possible that the pressure sensors 70, 72, 74 are connected outside the trailer control valve 80 to the respective associated pressure line 44, 50, 54.

[0048] In Fig. 6 A trailer control valve 94 according to the invention is shown, which is largely based on the trailer control valve 4' according to Fig. 2 based, but as in the embodiments according to the Figuren 3 , 4 and 5 is provided with pressure sensors 70, 72, 74 and has a hydraulic brake pressure input PB' and a redundant control branch 82'. In addition, the hydraulic brake system 2' of the towing vehicle is equipped, for example, with pressure sensors 22', 24', 32' for measuring the brake pressures in the associated brake lines 18', 20' and the brake release pressure in the parking brake line 30'.

[0049] The brake pressure input PB' is connected via a connecting line 84' to the brake line 20' of the second hydraulic brake circuit of the towing vehicle. The redundant control branch 82' is similar to that according to Fig. 5 constructed and comprises a hydraulically pressure-controlled relay valve 86', a redundancy valve 88' and a shuttle valve 90. However, instead of being connected to the supply pressure inlet P, the supply inlet of the relay valve 86' is now connected via a connecting line 98 to a connecting line 96 between the shut-off valve 38 and the pressure relief valve 36. In addition, the relay valve 86' is connected to the tank outlet T and via the shuttle valve 90 to the brake pressure outlet C. The control inlet of the relay valve 86' can be connected to the brake pressure inlet PB' via the redundancy valve 88'. The redundancy valve 88' is designed as a 3 / 2-way solenoid valve and is connected to the control unit 6 via an electrical control line. Via the redundancy valve 88', the control input of the relay valve 86' is connected to the brake pressure input PB' in the de-energized state and to the tank outlet T in the energized state.

[0050] Since the supply input of the relay valve 86' is only connected to the supply pressure input P via the connecting line 96 and the connecting line 98 when the shutoff valve 38 is energized and is then subject to the supply pressure, special measures are provided to prevent unintentional shutdown of the shutoff valve 38 and thus deactivation of the redundant control branch 82'. Thus, in the present case, the shutoff valve 38 is protected against malfunction-related failure by a control within the electronic control unit 6 that maintains the last switching state.

[0051] In the trailer control valve 94' according to the invention Fig. 7 For this purpose, with otherwise identical design, a second shut-off valve 38' is provided alternatively or additionally, which is arranged in parallel with the first shut-off valve 38 and is preferably of identical construction. The working outputs of the two shut-off valves 38, 38' are connected via a shuttle valve 102 to the connecting line 96 leading to the pressure relief valve 36. In the event of a defect in one of the two shut-off valves 38, 38', the supply of pressurized oil at the reservoir pressure into the connecting line 96 can thus take place via the other shut-off valve (38 or 38').

[0052] In the trailer control valve 94" according to the invention Fig. 8 is otherwise the same design as the trailer control valve 94 according to Fig. 6A further possibility for preventing unintentional deactivation of the shut-off valve 38 is shown. This consists in arranging in the connecting line 96 between the shut-off valve 38 and the connection of the connecting line 98 leading to the relay valve 86' a check valve 104 which blocks in the direction of the shut-off valve 38 and can be unlocked by means of an applied control pressure and which has a control inlet to which an electronically controllable pilot control valve 106 is connected. The pilot control valve 106 is designed as a 3 / 2-way solenoid switching valve, by means of which the control inlet of the check valve 104 is connected to the tank outlet T in the de-energized state and to the supply pressure inlet P in the energized state.Due to the pilot-operated check valve 104 in the connecting line 96, the inlet of the pressure relief valve 36 and the supply inlet of the relay valve 96' can only be ventilated and thus depressurized by an active control, i.e. the energization of the pilot valve 106, when the shut-off valve 38 is not energized.

[0053] The described trailer control valves 94, 94', 94" can each be formed by the valves 34, 36, 38, 86', 88', 90 or additionally the valves 38' or 102, 104 being connected to one another via plug connections and / or screw connections or by being arranged in a common valve housing 100, 100', 100". In the present case, the three pressure sensors 70, 72, 74 are also arranged within the respective trailer control valve 94, 94', 94". This illustrates that these pressure sensors 70, 72, 74 can be connected to the associated valves 34, 36, 38, 86', 90 via plug connections and / or screw connections and thus form the respective trailer control valve 94, 94', 94", or that the pressure sensors 70, 72, 74 can be arranged together with the associated valves 34, 36, 38, 86', 88', 90 or additionally with the valves 38' or 102, 104 in a common valve housing 100, 100', 100".However, it is also possible that the aforementioned pressure sensors 70, 72, 74 are connected outside the respective trailer control valve 100, 100', 100" to the respective associated pressure line 12', 50, 54. List of reference symbols (part of the description)

[0054] 2Brake system, compressed air brake system 2'Brake system (hydraulic) 4, 4'Trailer control valve (first or second embodiment) 6Electronic control unit 8Compressor 10Preparation unit 12, 12'First pneumatic supply line 14, 14'Second pneumatic supply line 16, 16'Foot brake valve (first or second embodiment) 18, 18'Brake line of the first service brake circuit 20, 20'Brake line of the second service brake circuit 22, 22'Pressure sensor on the brake line 18, 18', brake value transmitter 24, 24'Pressure sensor on the brake line 20, 20', brake value transmitter 26, 26'Further pneumatic supply line 28, 28'Parking brake valve (first orsecond embodiment) 30, 30'Parking brake line 32, 32'Pressure sensor on the parking brake line 30, 30', Parking brake sensor 34Brake control valve (designed as a 3 / 3-way proportional solenoid valve) 34'Brake control valve (designed as a 3 / 2-way proportional solenoid valve) 36Pressure relief valve 38First shut-off valve, 3 / 2-way solenoid switching valve 38'Second shut-off valve, 3 / 2-way solenoid switching valve 39Valve arrangement (first embodiment) 39'Valve arrangement (second embodiment) 40Oil pump 42, 42'Preparation unit (first or second embodiment) 44Hydraulic supply line 46Return line 48Collecting tank 50Brake line 52Brake clutch 54Auxiliary line 56Additional coupling 58Signal line 60Connector socket 62, 62'Valve housing (first or second embodiment) 64, 64'Actuator travel sensor, brake signal transmitter (first or second embodiment) 66, 66'Shift sensor, parking brake sensor (first orsecond embodiment) 68 Trailer control valve (third embodiment) 68' Trailer control valve (fourth embodiment) 70 Pressure sensor 72 Pressure sensor 74 Pressure sensor 76, 76' Valve housing (third or fourth embodiment) 78 Pressure switch 80 Trailer control valve (fifth embodiment) 82, 82' Redundant control branch (first or second embodiment) 84, 84' Connecting line (first or second embodiment) 86, 86' Relay valve (first or second embodiment) 88, 88' Redundancy valve, 3 / 2-way solenoid switching valve (first or second embodiment) 90 First shuttle valve 92 Valve housing (fifth embodiment) 94 Trailer control valve (sixth embodiment) 94' Trailer control valve (seventh embodiment) 94' Trailer control valve (eighth embodiment) 96 Connecting line 98 Connecting line 100Valve body (4th embodiment) 100', 100"Valve body (5thDesign) 102Second shuttle valve 104Check valve 106Pilot valve, 3 / 2-way solenoid valve CBrake pressure output PSupply pressure inlet PB, PB'Brake pressure inlet SAdditional pressure outlet TTank outlet.

Claims

1. Trailer control valve (4) of a tractor vehicle for controlling a hydraulic two-line brake system of a trailer vehicle, having a reservoir pressure input (P) for connecting a hydraulic reservoir line (12', 44) of the tractor vehicle, having a tank output (T) for connecting an unpressurized return line (46) of the tractor vehicle, having a brake pressure output (C) for connecting a brake line (50) of the trailer vehicle, and having an additional pressure output (S) for connecting an additional line (54) of the trailer vehicle, in which the brake pressure output (C) can be connected in a stepped manner to the reservoir pressure input (P) or to the tank output (T) by means of an electronically controllable brake control valve (34), and in which the additional pressure output (S) can be connected either to the reservoir pressure input (P), with a reduction in an output pressure of the reservoir pressure to an additional pressure, or to the tank output (T) via a valve arrangement (39) having at least one electronically controllable valve (38), wherein the valve arrangement (39) has a pressure-limiting valve (36) and a shut-off valve (38), wherein the pressure-limiting valve (36) and the shut-off valve (38) are arranged one behind the other in series, wherein the shut-off valve (38) is arranged connected downstream of the pressure-limiting valve (36) in terms of flow, and wherein the output pressure of the valve arrangement (39) can be lowered to the additional pressure by means of the pressure-limiting valve (36), characterized in that the shut-off valve (38) is designed as a 3 / 2-way solenoid switching valve, via which the additional pressure output (S) is connected to the tank output (T) in its deenergized state and to the working output of the pressure-limiting valve (36) in its energized state.

2. Trailer control valve (4') of a tractor vehicle for controlling a hydraulic two-line brake system of a trailer vehicle, having a reservoir pressure input (P) for connecting a hydraulic reservoir line (12', 44) of the tractor vehicle, having a tank output (T) for connecting an unpressurized return line (46) of the tractor vehicle, having a brake pressure output (C) for connecting a brake line (50) of the trailer vehicle, and having an additional pressure output (S) for connecting an additional line (54) of the trailer vehicle, in which the brake pressure output (C) can be connected in a stepped manner to the reservoir pressure input (P) or to the tank output (T) by means of an electronically controllable brake control valve (34'), and in which the additional pressure output (S) can be connected either to the reservoir pressure input (P), with a reduction in an output pressure of the reservoir pressure to an additional pressure, or to the tank output (T) via a valve arrangement (39') having at least one electronically controllable valve (38, 38'), wherein the valve arrangement (39') has a pressure-limiting valve (36) and a shut-off valve (38), wherein the pressure-limiting valve (36) and the shut-off valve (38) are arranged one behind the other in series, and wherein the output pressure of the valve arrangement (39') can be lowered to the additional pressure by means of the pressure-limiting valve (36), characterized in that the shut-off valve (38) is arranged connected upstream of the pressure-limiting valve (36) in terms of flow, and in that the shut-off valve (38) is designed as a 3 / 2-way solenoid switching valve, via which the additional pressure output (S) is connected to the tank output (T) in its deenergized state and to the reservoir pressure input (P) in its energized state.

3. Trailer control valve according to either of Claims 1 and 2, characterized in that, in order to detect the additional pressure prevailing at the additional pressure output (S), an electrohydraulic pressure sensor (74) or an electrohydraulic pressure switch (78) is connected to the additional line (54) inside or outside the trailer control valve (68, 68') close to the additional pressure output (S).

4. Trailer control valve according to one of Claims 1 to 3, characterized in that the brake control valve (34, 34') is designed as a 3 / 3-way proportional solenoid valve or as a 3 / 2-way proportional solenoid valve with valve spring-side return of the injected brake pressure to the valve piston, via which the brake pressure output (C) is connected unthrottled to the tank output (T) in the deenergized state and unthrottled to the reservoir pressure input (P) in the maximum energized state.

5. Trailer control valve according to one of Claims 1 to 4, characterized in that, in order to detect the brake pressure prevailing at the brake pressure output (C), an electrohydraulic pressure sensor (72) is connected to the brake line (50) inside or outside the trailer control valve (68, 68') close to the brake pressure output (C).

6. Trailer control valve according to one of Claims 1 to 5, characterized in that, in order to detect the reservoir pressure prevailing at the reservoir pressure input (P), an electrohydraulic pressure sensor (70) is connected to the reservoir line (12', 44) inside or outside the trailer control valve (68, 68') close to the reservoir pressure input (P).

7. Trailer control valve according to one of Claims 1 to 6, characterized in that, in order to detect the coupling state of a trailer vehicle, an electrical signal line (58) is connected to an associated electronic control device (6) directly or via the trailer control valve (4, 4', 68, 68').

8. Trailer control valve according to one of Claims 1 to 7, characterized in that a brake pressure input (PB, PB') connected to a brake line (20, 20') of the tractor vehicle and a redundant control branch (82, 82') having a pressure-controlled relay valve (86, 86') for the brake pressure-dependent injection of a brake pressure and a redundancy valve (88, 88') for the activation and deactivation of the redundant control branch (82, 82') are provided.

9. Trailer control valve according to Claim 8, characterized in that the relay valve (86, 86') is connected to the reservoir pressure input (P), the tank output (T) and via a shuttle valve (90) to the brake pressure output (C) and is provided with a control input, and in that the redundancy valve (88, 88') is designed as a 3 / 2-way solenoid switching valve, by means of which, in the deenergized state, the control input of the relay valve (86, 86') is connected to the brake pressure input (PB, PB') and, in the energized state, to a ventilation output or to the tank output (T).

10. Trailer control valve according to Claim 8 or 9, characterized in that, in the case of an arrangement of the shut-off valve (38) connected upstream of the pressure-limiting valve (36), the reservoir input of the relay valve (86'), instead of being connected to the reservoir pressure input (P), is connected to the connecting line (96) between the shut-off valve (38) and the pressure-limiting valve (36) via a connection line (98).

11. Trailer control valve according to Claim 10, characterized in that the shut-off valve (38) is protected against fault-induced failure by a controller which maintains the last switching state within the associated electronic control device (6).

12. Trailer control valve according to Claim 10 or 11, characterized in that a second shut-off valve (38') is arranged in parallel with the shut-off valve (38), in that the second shut-off valve (38') is of identical design to the first shut-off valve (38), and in that the working outputs of the two shut-off valves (38, 38') are connected via a shuttle valve (102) to the connecting line (96) leading to the pressure-limiting valve (36).

13. Trailer control valve according to Claim 10 or 11, characterized in that a check valve (102) which blocks in the direction of the shut-off valve (38), is unblockable by means of an injected control pressure and has a control input, to which an electronically controllable pilot control valve (104) is connected, is arranged in the connecting line (96) between the shut-off valve (38) and the connection of the connection line (98) leading to the relay valve (86'), and in that the pilot control valve (104) is designed as a 3 / 2-way solenoid switching valve, by means of which the control input of the check valve (102) is connected to the tank output (T) in the deenergized state and is connected to the reservoir pressure input (P) in the energized state.

14. Trailer control valve according to one of Claims 1 to 13, characterized in that at least the brake control valve (34, 34'), the pressure-limiting valve (36), the shut-off valve (38, 38'), the relay valve (86, 86'), the redundancy valve (88, 88') and the shuttle valve (90) are connected to one another by means of plug-in and / or screw connections.

15. Trailer control valve according to one of Claims 1 to 13, characterized in that at least the brake control valve (34, 34'), the pressure-limiting valve (36), the shut-off valve (38, 38'), the relay valve (86, 86'), the redundancy valve (88, 88') and the shuttle valve (90) are arranged in a common valve housing (62, 62', 76, 76', 92, 100, 100', 100").