Air Treatment Unit for a Brake System of a Utility Vehicle, Brake System and Method for Operating an Air Treatment Unit

Abstract

An air treatment unit for a brake system of a utility vehicle includes a control valve connection for pneumatically coupling the air treatment system to at least one control valve connected upstream of a wheel brake cylinder of the brake system that is configured to alter a brake pressure in the wheel brake cylinder, a supply valve for supplying the control valve connection with a required pressure, and a control device for controlling the supply valve.

Claims

1. An air control unit for a brake system of a commercial vehicle, comprising: a control valve connector configured to pneumatically couple the air control unit to a control valve upstream of a wheel brake cylinder of the brake system; a loading valve configured to load the control valve connector with a setpoint pressure; and a control unit configured to actuate the loading valve to change a brake pressure in the wheel brake cylinder.

2. The air control unit as claimed in claim 1, wherein the control unit is configured to be coupled to at least one wheel speed sensor of the commercial vehicle, and actuate either or both of the loading valve and the control valve based at least in part on a wheel speed sensor signal generated by the wheel speed sensor to brake one side of the commercial vehicle.

3. The air control unit as claimed in claim 2, further comprising: a distributor unit configured to distribute air from the air control unit to a brake circuit of a service brake of the brake system; a connecting line configured to connect the distributor unit to the control valve connector; and a shuttle valve having a first shuttle valve inlet and a second shuttle valve inlet, wherein the connecting line is part of the brake circuit, the loading valve is arranged in the connecting line and upstream of the first shuttle valve inlet such that the loading valve is capable of actuating the service brake via the shuttle valve to control one or both of an outlet control pressure of a front or rear axle valve module and an outlet control pressure of the foot brake module at the second shuttle valve inlet.

4. The air control unit as claimed in claim 3, wherein the control unit is configured to actuate one or both of the loading valve and the control valve in response to a failure of an electronic brake system of the commercial vehicle.

5. A brake system, comprising: an air control unit including a control valve connector configured to pneumatically couple the air control unit to a control valve upstream of a wheel brake cylinder of the brake system; a loading valve configured to load the control valve connector with a setpoint pressure; and a control unit configured to actuate the loading valve to change a brake pressure in the wheel brake cylinder; a control valve configured to change a brake pressure in a wheel brake cylinder of the brake system; and a shuttle valve having a first shuttle valve inlet, a second shuttle valve inlet (144) and a shuttle valve outlet, the first shuttle valve inlet being connected to the control valve connector of the air control unit, the second shuttle valve inlet being connected to a brake circuit of a service brake of the brake system, and the shuttle valve outlet being connected to the control valve.

6. The brake system claimed in claim 5, further comprising: a relay valve having an operating pressure inlet, an operating pressure outlet and a control inlet, wherein the relay valve is configured to control a throughflow between the operating pressure inlet and the operating pressure outlet at a setpoint pressure, the air control unit has a relay valve connector configured to provide an operating pressure for operating the brake system, the relay valve operating pressure inlet is connected to the relay valve connector, the relay valve operating pressure outlet is connected to the first shuttle valve inlet, and the relay valve control inlet being connected to the control valve connector.

7. The brake system as claimed in claim 5, further comprising: a relay valve having an operating pressure inlet, an operating pressure outlet and a control inlet, wherein the relay valve is configured to control a throughflow between the operating pressure inlet and the operating pressure outlet at a pressure at the shuttle valve outlet, the air control unit has a relay valve connector configured to provide an operating pressure for operating the brake system, the relay valve operating pressure inlet is connected to the relay valve connector, the relay valve operating pressure outlet is connected to the control valve, and the relay valve control inlet being connected to the shuttle valve outlet.

8. The brake system as claimed in claim 5, wherein the loading valve is one of a plurality of loading valves, each loading valve being associated with a respective axle, and the system is configured to actuate the plurality of loading valves on a per axle basis.

9. The brake system as claimed in claim 8, wherein the plurality of loading valves are arranged outside or inside the air control unit, and are actuable by the air control unit.

10. The brake system as claimed in claim 5, wherein the relay valve is one of a plurality of relay valves, each relay valve being associated with a respective axle, and the system is configured to actuate in the plurality of relay valves on a per axle basis.

11. The brake system as claimed in claim 10, wherein the plurality of relay valves are arranged outside or inside the air control unit, and are actuable by the air control unit.

12. The brake system as claimed in claim 8, wherein the plurality of loading valves are configured to be bistable.

13. The brake system as claimed in claim 10, wherein the plurality of relay valves are configured to be bistable.

14. The brake system as claimed in claim 5, wherein the brake system is configured to control a braking operation in a stepped manner.

15. The brake system as claimed in claim 5, wherein at least two electric redundancy systems are provided for controlling the service brake.

16. The brake system as claimed in claim 5, wherein the brake system is configured to actuate the service brake in a stepped manner, both independent of a driver request and in a manner which dominates the driver request.

17. The brake system as claimed in claim 5, wherein the control unit is configured to calculate the setpoint pressure for a service brake system based at least in part of information from a driver assistance system.

18. The brake system as claimed in claim 5, wherein the air control unit is configured to additionally carry out a pneumatic, redundant control of the service brake in a manner which is dependent on a driver brake request via a foot brake module.

19. A method for operating an air control unit having a control valve connector configured to pneumatically couple the air control unit to a control valve upstream of a wheel brake cylinder of the brake system, a loading valve configured to load the control valve connector with a setpoint pressure, and a control unit configured to actuate the loading valve to change a brake pressure in the wheel brake cylinder, the method comprising the act of: generating a control signal to actuate the loading valve to load the control valve connector with the setpoint pressure.

20. A machine-readable storage medium, on which a computer program configured to carry out and/or actuate the method as claimed in claim 19 is stored.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 shows a diagrammatic illustration of a brake system with an air control unit in accordance with one embodiment of the present invention.

[0039] FIG. 2 shows a diagrammatic illustration of a brake system with an air control unit in accordance with one embodiment of the present invention.

[0040] FIG. 3 shows a diagrammatic illustration of a brake system with an air control unit in accordance with one embodiment of the present invention.

[0041] FIG. 4 shows a diagrammatic illustration of a control unit in accordance with one embodiment of the present invention.

[0042] FIG. 5 shows a flow chart of a method in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0043] In the following description of favorable embodiments of the present invention, identical or similar designations are used for the similarly acting elements which are shown in the various figures, a repeated description of said elements being dispensed with.

[0044] FIGS. 1 to 3 which are described in the following text indicate lines for electric signal transmission by way of dotted lines, pneumatic lines by way of continuous lines, and lines for the transmission of electric energy by way of arrow-shaped lines. Optional connections are indicated by way of lines which are partially dashed and partially dotted.

[0045] FIG. 1 shows a diagrammatic illustration of a brake system 100 for a commercial vehicle with an air control unit 102 in accordance with one exemplary embodiment. The air control unit 102 comprises a filter cartridge 106 which is connected to a compressor 104 for filtering and drying the compressed air which is provided by the compressor 104. The filter cartridge 106 is arranged on a housing 108 of the air control unit 102, and is connected pneumatically via a filter cartridge line 110 to the housing 108. A loading valve 112 is arranged in the housing 108. In accordance with said embodiment, the loading valve 112 is connected via a distributor unit 114 to the filter cartridge line 110. A connecting line 116 connects the distributor unit 114 to a control valve connector 118 of the housing 108. Here, the loading valve 112 is arranged in the connecting line 116. The pressure tapping point can also be arranged upstream of the distributor unit 114 for advantageous functioning. It is important in accordance with one embodiment that the supply pressure for the loading valve is stable, that is to say does not drop to zero in the case of an absent compressor delivery. Therefore, the pressure tapping point in said embodiment can also still lie between the distributor unit and the check valve. By way of example, the connecting line 116 is part of a brake circuit which is assigned to a service brake of the brake system 100. The air control unit 102 is coupled pneumatically via the control valve connector 118 by way of example to two control valves 120 which are connected upstream of in each case one of two front wheel brake cylinders 122 of a front axle of the commercial vehicle. In accordance with a further embodiment, the control valve connector 118 is coupled, as an alternative or in addition, to control valves which are assigned to a rear wheel brake of the commercial vehicle.

[0046] The loading valve 112 is configured to load the control valve connector 118 with a setpoint pressure. A control unit 124 which is likewise arranged on the housing 108 is configured to actuate the loading valve 112 by way of the output of a corresponding control signal 126. The control valves 120 are configured to change a respective brake pressure in the front wheel brake cylinders 122. The actuation of the control valves 120 by way of the air control unit 102 takes place, for example, in such a way that locking of the wheels during braking is prevented or the commercial vehicle is braked on one side.

[0047] In accordance with said embodiment, the loading valve 112 is configured to load the control valve connector 118 with a setpoint pressure which can be modulated such that it can be stepped between the ambient pressure and the operating pressure, it being possible, for example, for said setpoint pressure to be removed in part directly from the solenoid valve and in part from a relay valve in a manner with a boosted air quantity. As an alternative, the loading valve 112 can be configured to load the control valve connector 118 with a control pressure (as the setpoint pressure) for pneumatically actuating a valve or valve module, connected upstream of the two control valves 120, of the brake system 100, such as a relay valve, as described in greater detail, for example, in the following text using FIG. 2.

[0048] By way of example, the commercial vehicle is equipped with a total of four optional wheel speed sensors 128 for detecting a rotational speed of in each case one wheel on the front and rear axle. The wheel speed sensors 128 send in each case one wheel speed sensor signal 130 which represents the respective rotational speed of a wheel to the control unit 124, the control unit 124 being configured to actuate the loading valve 112 with the use of the wheel speed sensor signals 130, that is to say in a manner which is dependent on the respective rotational speed of the wheels. The control unit 124 optionally uses the wheel speed sensor signals 130 to directly electrically actuate the two control valves 120, in addition or as an alternative to the loading valve 112, in particular in such a way that, during braking of the commercial vehicle, locking of the front wheels is avoided or the commercial vehicle is additionally braked on one side.

[0049] In accordance with the embodiment which is shown in FIG. 1, the loading valve 112 is realized as a valve module comprising a plurality of individual valves, here comprising a solenoid valve 132 with (by way of example) two solenoid valve units, and a relay valve 134. The relay valve 134 comprises an operating pressure inlet 1, an operating pressure outlet 2 and a control inlet 4 for controlling a throughflow between the operating pressure inlet 1 and the operating pressure outlet 2. Here, the operating pressure inlet 1 is connected via the connecting line 116 to the distributor unit 114, with the result that the setpoint pressure prevails in the form of the operating pressure at the operating pressure inlet 1. The operating pressure outlet 2 is connected to the control valve connector 118. The control inlet 4 is connected to an outlet 2 of the solenoid valve unit 132. Said solenoid valve arrangement has, for example, two solenoid valves which are required to realize pressure maintaining, pressure build-up and pressure dissipation. An illustration of this type is not shown explicitly in the figures for the sake of clarity. The solenoid valve unit 132 is configured to load the control inlet 4, using the setpoint pressure (here, the operating pressure), with a control pressure which is, for example, considerably lower for opening the relay valve 134, with the result that the setpoint pressure prevails at the control valve connector 118. The electric actuation of the solenoid valve 132 takes place by way of the control unit 124.

[0050] In accordance with one embodiment, the loading unit 112 is of bistable configuration. This can ensure that the setpoint pressure prevails at the control valve connector 118 even in the case of an interrupted power supply. The bistable valves can be bistable, for example, at maximum pressure or zero pressure. In this way, they are suitable for maintaining the two pressure states of a parking brake without power. Therefore, any desired setpoint pressure cannot be maintained without power. The bistable valve unit will regulate, for example, into one of the pressure end positions.

[0051] The two front wheel brake cylinders 122 are connected via a front axle valve module 136 to a foot brake module 138 of the brake system 100. The two control valves 120 are arranged between the front wheel brake cylinders 122 and the front axle valve module 136. In a line section which connects the two control valves 120 to the front axle valve module 136, a shuttle valve 140 is arranged with a first shuttle valve inlet 142, a second shuttle valve inlet 144 and a shuttle valve outlet 146. Here, the first shuttle valve inlet 142 is connected to the control valve connector 118, the second shuttle valve inlet 144 is connected to an outlet of the front axle valve module 136 and therefore to a brake circuit which is assigned to a service brake of the brake system 100, and the shuttle valve outlet 146 is connected to the two control valves 120. The shuttle valve 140 can ensure that the two control valves 120 are loaded in each case with the higher one of the pressures which prevail at the two shuttle valve inlets 142, 144.

[0052] The brake system 100 which is shown in FIG. 1 can be actuated by way of example by an EBS control unit 148 of an electronic brake system of the commercial vehicle. To this end, the EBS control unit 148 is connected, for example, to the wheel speed sensors 128, the foot brake module 138 and the front axle valve module 136 for electric signal transmission. In accordance with one embodiment, the control unit 124 of the air control unit 102 is configured to actuate the loading valve 112 in the case of failure of the electronic brake system, with the result that sufficient braking performance can still be ensured at the front axle of the commercial vehicle.

[0053] Furthermore, the foot brake module 138 is connected via a rear axle valve module 150 to two rear wheel brake cylinders 152 of the rear axle of the commercial vehicle. Merely by way of example, no ABS control valves are arranged between the rear axle valve module 150 and the rear wheel brake cylinders 152 in contrast to the front axle. In accordance with said embodiment, the two rear wheel brake cylinders 152 are configured to lock the rear wheels of the commercial vehicle by spring force in the ventilated state. The rear wheel brake cylinders 152 therefore act as a park or parking brake.

[0054] FIG. 2 shows a diagrammatic illustration of a brake system 100 for a commercial vehicle with the air control unit 102 in accordance with one embodiment. The brake system 100 corresponds substantially to the brake system described in the preceding text using FIG. 1. In contrast to FIG. 1, the brake system 100 in FIG. 2 is shown without a front and rear axle valve module. Instead, the foot brake module 138 is coupled to the two rear wheel brake cylinders 152 via two further control valves 200 which are connected upstream of the two rear wheel brake cylinders 152. Just like the two control valves 120 of the front axle, the two further control valves 200 of the rear axle act as ABS pressure control valves. In the normal case, the electric actuation of the four control valves 120, 200 takes place by way of an ABS control unit 202. As an alternative, in the case of the failure of the ABS control unit 202, the four control valves 120, 200 can be actuated by the control unit 124 of the air control unit 102. As an alternative or in addition to the visible relay valve of the parking brake, a relay valve might also be used at the rear axle, in order for it to be possible for a redundant pressure specification for the service brake cylinders of the rear axle to be modulated at the rear axle via a further valve 144 upstream of the control valves in an analogous manner to the pressure at the front axle (maximum upgrade).

[0055] A further difference from FIG. 1 consists in that the relay valve 134 is arranged outside the housing 108 here. Here, the operating pressure inlet 1 is connected to a relay valve connector 204 of the housing 108, which relay valve connector 204 is connected to the distributor unit 114, with the result that the operating pressure inlet 1 is loaded with the operating pressure via the relay valve connector 204. The operating pressure outlet 2 is connected to the first shuttle valve inlet 142, whereas the control inlet 4 is connected to the control valve connector 118. The first shuttle valve inlet 122 is therefore connected via the relay valve 134 to the control valve connector 118. The outlet 2 of the solenoid valve 132 which is situated in the housing 108 is likewise connected to the control valve connector 118 and is configured to load the control inlet 4 via the control valve connector 118 with the control pressure which is required for the pneumatic control of the relay valve 134 as the setpoint pressure. The second shuttle valve inlet 144 is connected to the foot brake module 138 and therefore to a service brake circuit of the brake system 100. As in FIG. 1, the shuttle valve outlet 146 is connected to the two control valves 120 of the front axle.

[0056] FIG. 3 shows a diagrammatic illustration of a brake system 100 for a commercial vehicle with an air control unit 102 in accordance with one embodiment. The brake system 100 which is shown in FIG. 3 corresponds for the most part to the brake system which is described in the preceding text using FIG. 2, with the difference that the relay valve 134 is arranged here between the shuttle valve 140 and the two control valves 120 instead of between the control valve connector 118 and the shuttle valve 140 as in FIG. 2. Here, as in FIG. 1, the first shuttle valve inlet 142 is connected directly to the control valve connector 118, whereas the second shuttle valve inlet 144 is connected to the foot brake module 138. The control inlet 4 of the relay valve 134 is connected to the shuttle valve outlet 146. The pneumatic actuation of the relay valve 134 therefore takes place indirectly via the shuttle valve 140. Here, the operating pressure inlet 1 is connected to the relay valve connector 204, and the operating pressure outlet 2 is connected to the two control valves 120.

[0057] FIG. 4 shows a diagrammatic illustration of a control unit 124 in accordance with one embodiment, for instance of a control unit which is described in the preceding text using FIGS. 1 to 3. The control unit 124 comprises a generating unit 410 for generating the control signal 126. The control unit 124 optionally comprises a reading unit 420 for reading the wheel speed sensor signals 130 and forwarding the wheel speed sensor signals 130 to the generating unit 410. Here, the generating unit 410 is configured to generate the control signal 126 with the use of the wheel speed sensor signals 130.

[0058] FIG. 5 shows a flow chart of a method 500 for operating an air control unit in accordance with one embodiment. The method 500 can be carried out, for example, in conjunction with a control unit which is described in the preceding text using FIGS. 1 to 4. The method 500 comprises a step 510, in which the control signal for actuating the loading valve of the air control unit is generated.

[0059] In the following text, different embodiments of the approach which is proposed here are summarized once again in other words.

[0060] The setpoint pressure of the brake system 100 is as a rule transmitted via the foot brake module 138 to the two brake circuits of the front and rear axle. Here, the pressure ratio of the front axle to the rear axle is fixed pneumatically via the foot brake module 138. That is to say, the two axles cannot be modulated at the same time in an optimum manner to the slip in some circumstances. Even in the ABS case, the pilot pressure upstream of the ABS pressure control valves (also called control valves for short in the preceding text) can be sub-optimally high, for instance, on one of the two axles.

[0061] Using the approach which is proposed here, it is then possible, during autonomous driving, to modulate the setpoint pressure which is provided by the air control unit 102 in parallel with the electronic brake system upstream of the ABS pressure control valves per axle in the case of a failure of the electronic brake system. In this way, an optimum distribution of the brake forces to the axles, which brake forces can vary greatly in a manner which is dependent on a load-induced contact force, and therefore as short a braking distance as possible can be ensured.

[0062] The control unit 124 is optionally configured to read the wheel speed sensor signals 130, for instance pole wheel signals, in parallel with the electronic brake system. With a knowledge of the wheel slip, the control unit 124 then modulates to a maximum permissible slip of the wheel with a lower coefficient of friction at least per axle, in a similar manner to an anti-lock brake system.

[0063] In accordance with a further embodiment, the ABS pressure control valves are connected electrically to the control unit 124 for actuation in the case of a failure of the electronic brake system. As a result, it is possible to modulate to the slip in a wheel-individual manner, which can shorten the braking distance, in particular in the case of friction conditions which fluctuate from side to side. The air control unit 102 is likewise given the option as a result to perform steering/braking operations by way of one-sided breaking of the steered axle.

[0064] In accordance with one embodiment, the loading valve 112 comprises a solenoid valve unit 132 with at least two solenoid valves which are additionally integrated into the air control unit 102 and are configured to feed the control air via the relay valve 134 in a manner with a boosted air quantity via a select high valve into a line branch upstream of the ABS pressure control valves. Depending on the embodiment, the relay valve 134 is integrated into the air control unit 102 or is arranged outside the air control unit 102.

[0065] In the case of an anti-lock brake system, an anti-slip control valve (equivalent to proportional valves or differential pressure valves with the same function) can be saved by way of an extension of this type of the air control unit 102 if the air control unit 102 can transmit the supply pressure via the anti-slip control valves to the drive wheels during the anti-slip control operation, even in the normal case.

[0066] A functional extension for increasing the stability of the commercial vehicle consists, for example, in that the loading valve 112 for actuating the front axle is of bistable configuration, with the result that the brake pressure is maintained at the front axle even in the case of a power failure or after the ignition is switched off. This might still hold the vehicle at a standstill in an emergency situation if the rear axle has come to a standstill merely at a low level.

[0067] Depending on the embodiment, the actuation of the brake system 100 via the air control unit 102 is realized on one or more axles of the commercial vehicle. It is advantageous here if, instead of a dual channel pressure control module, a single channel pressure control module with downstream ABS pressure control valves is installed at the rear axle, with the result that side-individual brake intervention via the air control unit 102 can take place even at the rear axle in the case of a failure of the electronic brake system.

[0068] In the case of an extension of the actuation to the axles of the commercial vehicle which are equipped with parking brake cylinders, the brake actuation shown here of the rear axle via a parking brake can then be dispensed with. In this way, the parking brake can be decoupled from the redundancy function for autonomous driving.

[0069] The embodiment which is shown in FIG. 3 is advantageous with regard to clear spans to be designed and robustness in so far as only control flows are conducted via the select high valve.

[0070] If an embodiment comprises an and/or combination between a first feature and a second feature, this is to be interpreted such that the exemplary embodiment has both the first feature and the second feature in accordance with one embodiment, and has either only the first feature or only the second feature in accordance with a further embodiment.

LIST OF DESIGNATIONS

[0071] 1 Operating pressure inlet [0072] 2 Operating pressure outlet [0073] 4 Control inlet [0074] 100 Brake system [0075] 102 Air control unit [0076] 104 Compressor [0077] 106 Filter cartridge [0078] 108 Housing [0079] 110 Filter cartridge line [0080] 112 Loading valve [0081] 114 Distributor unit [0082] 116 Connecting line [0083] 118 Control valve connector [0084] 120 Control valve [0085] 122 Front wheel brake cylinder [0086] 124 Control unit [0087] 126 Control signal [0088] 128 Wheel speed sensor [0089] 130 Wheel speed sensor signal [0090] 132 Solenoid valve [0091] 134 Relay valve [0092] 136 Front axle valve module [0093] 138 Foot brake module [0094] 140 Shuttle valve [0095] 142 First shuttle valve inlet [0096] 144 Second shuttle valve inlet [0097] 146 Shuttle valve outlet [0098] 148 EBS control unit [0099] 150 Rear axle valve module [0100] 152 Rear wheel brake cylinder [0101] 200 Further control valve [0102] 202 ABS control unit [0103] 204 Relay valve connector [0104] 410 Generating unit [0105] 420 Reading unit [0106] 500 Method for operating an air control unit [0107] 510 Generating step

[0108] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.