Electronically controllable pneumatic brake system with Anti-compound function

Abstract

The invention relates to an electronically controllable pneumatic brake system (1) for a utility vehicle, comprising a service brake cylinder (12) and a spring brake cylinder (18); a first brake pressure modulator (2) for modulating a first service brake pressure (pSB1) at the service brake cylinder (12); a parking brake module (4) for modulating a parking brake pressure (pB) at the first spring brake cylinder (18), the parking brake module (4) having an anti-compound connection (21) which is connected to the brake pressure modulator (2) for receiving the first service brake pressure (pSB1); and an electronic control unit (26) which is connected to the brake pressure modulator (2) and the parking brake module (4). The electronic control unit (26) has an anti-compound unit (28), comprising a precondition checking unit (30) for checking one or more preconditions; and a parking brake pressure checking unit (32) for determining the parking brake pressure (pB), which parking brake pressure checking unit, in the event that the preconditions are met and the parking brake pressure (pB) is below a first parking brake pressure threshold value (pB1), is designed to prevent implementing a first service brake pressure (pSB1) modulated for the anti-compound connection (21).

Description

[0001] Electronically controlled pneumatic braking system with anti-compound function

[0002] The invention relates to an electronically controlled pneumatic braking system for a commercial vehicle, comprising at least one first service brake cylinder and one first spring-applied brake cylinder on a first axle; an electropneumatic first brake pressure modulator on the first axle for controlling a first service brake pressure at the first service brake cylinder; an electropneumatic parking brake module for controlling a parking brake pressure at the first spring-applied brake cylinder, wherein the parking brake module has an anti-compound connection that is connected to the first brake pressure modulator for receiving the first service brake pressure; and an electronic control unit that is connected to the first brake pressure modulator and the parking brake module.The invention further relates to a method for implementing an anti-compound function in an electronically controlled pneumatic braking system, as well as a commercial vehicle with an electronically controlled pneumatic braking system.

[0003] Modern commercial vehicles are equipped with electronically controlled pneumatic braking systems that use compressed air to generate a braking force at the brake actuators. Both service brake actuators and parking brake actuators are typically pneumatically operated. Parking brake actuators are typically designed as spring-applied brake cylinders. While service brake actuators close when pressure is applied and are open when depressurized or vented, spring-applied brake cylinders operate in reverse. That is, when pressurized, spring-applied brake cylinders are open, while when vented, they close due to preload from a spring force, thus locking the vehicle. Often, service brake actuators and spring-applied brake cylinders are combined in a so-called combination cylinder or tristop cylinder and act on the same brake disc with the same brake pad.

[0004] Overloading of the brakes can occur when both the service brake actuator and the spring brake cylinder are activated simultaneously. In such cases, the force on the mechanical components can add up, potentially leading to failure due to overload. This can happen particularly when, for example, the parking brake function of the commercial vehicle is activated while stationary, meaning the spring brake cylinder(s) are vented and compressed, and then a driver activates the service brake in this state, especially by pressing a brake pedal, thus applying an additional force to the brake disc from the service brake. To prevent this, a so-called anti-compound function is used.An anti-compound function generally means that as the service brake actuator is compressed, the spring brake cylinder is simultaneously vented to release it. Thus, if an operator applies the service brake while the vehicle is stationary and the parking brake is engaged, the service brake pressure, controlled by the brake pedal, is applied to the service brake actuator. However, the spring brake cylinder is simultaneously vented and released to prevent overloading. Typically, a so-called anti-compound pressure from the pneumatic brake pedal is used as a control pressure to supply an anti-compound port on a parking brake module, which is generally used to pressurize and vent the spring brake cylinders.The control pressure controlled by the pneumatic brake pressure sensor is then fed to a relay valve via this anti-compound connection of the parking brake module. This relay valve then amplifies the control pressure by volume and feeds the amplified pressure to the spring brake cylinder to release it.

[0005] A disadvantage of this is the sometimes high air consumption.

[0006] In addition to purely pneumatic anti-compound functions, software-based functions are also known, such as those disclosed in EP 4 043 305 B1. This patent discloses a pneumatic braking system for one axle of a vehicle, comprising: a service brake actuator configured to apply a braking force to one axle of the vehicle, and an electropneumatic modulator unit configured to: receive an initial air control pressure representing a braking request from a driver, receive an air supply pressure and deliver an initial modulated air pressure to a service brake chamber to control the applied braking force, with the initial modulated air pressure being delivered via a control unit.The system further comprises a parking brake actuator configured to exert a braking force by means of an elastic spring and a pneumatic chamber, wherein the pneumatic chamber is configured to exert a force opposing the force exerted by the spring, the total braking force being the sum of the service brake actuator force and the parking brake actuator force. The pneumatic braking system further comprises a parking brake unit configured to supply a second air pressure to the pneumatic chamber of the parking brake to control the force exerted by the parking brake actuator.An isolating device configured to do the following: in a first mode, when the isolating device is electrically energized, prevent the first air control pressure from being supplied to the control unit; and in a second mode, when the isolating device is not electrically energized, allow the first air control pressure to be supplied to the control unit so that a braking force is exerted by the service brake actuator when the pressure in the parking brake chamber is greater than a first predetermined threshold, and prevent the first air control pressure from being supplied to the control unit when the pressure in the parking brake chamber is less than or equal to the first predetermined threshold.

[0007] The object of the invention is therefore to provide an electronically controllable pneumatic braking system, a method and a commercial vehicle of the type mentioned above, which have an improved anti-compound function.

[0008] In a first aspect, the problem is solved by an electronically controlled pneumatic braking system for a commercial vehicle of the type mentioned above, wherein the electronic control unit has an anti-compound unit, comprising: a preconditions test unit for checking one or more preconditions; and a parking brake pressure test unit for determining the parking brake pressure, wherein the parking brake pressure test unit is further configured to prevent the application of a first service brake pressure controlled for the anti-compound connection if the one or more preconditions are met and the parking brake pressure is below a first parking brake pressure threshold.

[0009] The invention is based on the finding that, depending on one or more preconditions, which may include, for example, a vehicle standstill, an engine ignition switched off, the activation of a parking brake switch, a venting state of spring brake cylinders or other preconditions, and the finding that the parking brake pressure is below a first parking brake pressure threshold, i.e., the spring brake cylinder is compressed to a certain degree, preferably completely, the first service brake pressure, which can be understood here as anti-compound pressure, is not implemented in an anti-compound function of the parking brake module.In other words, if the precondition(s) are met and the parking brake pressure is below the first parking brake pressure threshold, the service brake actuator is not engaged when the driver presses the brake pedal; instead, the spring brake cylinder remains engaged. This has the same effect as if the service brake cylinder were engaged and the spring brake cylinder were vented. In both cases, the vehicle remains braked, with the difference being that different brake actuators are used. The invention thus achieves a reduction in air consumption and also a reduction in wear of safety-relevant components of the braking system.

[0010] Furthermore, the invention provides that the anti-compound pressure is not the pressure controlled by the brake force sensor, but rather the first service brake pressure controlled by an electropneumatic first brake pressure modulator. This electropneumatic first brake pressure modulator could, for example, be a rear axle modulator or a front axle modulator. This has the advantage that it is not necessary to interfere with the control pressure between the pneumatic brake force sensor and the first brake pressure modulator; instead, a pressure downstream of the first brake pressure modulator is used to activate or deactivate the anti-compound function. This makes the system less prone to failure overall. The system according to the invention can be implemented in the existing brake system, particularly without additional structural components, and is therefore cost-effective.

[0011] In the present application, "preventing the implementation of a first service brake pressure controlled for the anti-compound port" means that the first service brake pressure, which is to be controlled at the anti-compound port to implement the anti-compound function, is not provided, not controlled at the anti-compound port, or not further processed by the parking brake module after being received at the anti-compound port. In addition to the aforementioned preconditions, further preconditions may be included, such as preferably a health state of the parking brake (preferably obtainable from a control unit of the brake system or vehicle, such as a health gateway control unit), the pressure level in one or more compressed air reservoirs, a request signal for the parking brake (release request), for example via a parking brake switch, and / or the status of an air preparation unit.

[0012] The anti-compound unit can be implemented as a software unit within the electronic control unit and / or include pneumatic or electropneumatic elements. The electronic control unit can be a separate control unit integrated into the braking system, and in particular, it can be designed as a central module. In this case, the anti-compound unit would preferably be implemented as a software component within the central module. The electronic control unit can also be partially or completely integrated into one or more other modules of the electronically controlled pneumatic braking system, such as, in particular, the first brake pressure modulator or the parking brake module.

[0013] In a preferred further development, the anti-compound unit is designed to allow the conversion of the first service brake pressure, which is controlled for the anti-compound connection, if one or more preconditions are met and the parking brake pressure is above a second parking brake pressure threshold, where the second parking brake pressure threshold is greater than the first parking brake pressure threshold. In other words, if the parking brake pressure is above the second parking brake pressure threshold, i.e., if the spring-applied brake cylinder is partially or fully released, the anti-compound function is activated, and the first service brake pressure is controlled as anti-compound pressure at the parking brake module, which then converts this pressure and further releases the spring-applied brake cylinder while the service brake cylinder(s) are applied.

[0014] The first parking brake pressure threshold is preferably selected such that the spring brake cylinder is securely engaged below this threshold. For example, the first parking brake pressure threshold is in the range of 0.3 to 0.7 bar, approximately 0.5 bar. Precise values ​​can be selected depending on the design of the spring brake cylinder and may be stored, for example, in the electronic control unit. The second parking brake pressure threshold is preferably selected such that the spring brake cylinder is essentially released above this threshold. The second parking brake pressure threshold can, for example, be in the range of 3 to 8 bar, preferably in the range of 3.5 to 5 bar, preferably approximately 4 bar.Here too, the second parking brake pressure threshold can depend on the exact design of the spring-applied brake cylinder and may be stored as a parameter in the electronic control unit. Furthermore, the second parking brake pressure threshold can also depend on other parameters, such as the vehicle's load or the incline.

[0015] In a further preferred embodiment, the anti-compound unit includes a service brake pressure test unit for determining the initial service brake pressure. The service brake pressure test unit is preferably implemented partially or completely as a software component within the anti-compound unit. The service brake pressure test unit preferably receives a sensor signal from a pressure sensor arranged to determine the service brake pressure.

[0016] Furthermore, it is preferred that the anti-compound unit is configured to allow the conversion of a first service brake pressure controlled for the anti-compound connection if one or more preconditions are met and the first service brake pressure is below a service brake pressure threshold. The service brake pressure threshold is preferably between the first and second parking brake pressure thresholds.

[0017] Preferably, the anti-compound unit is further designed to prevent the activation of a first service brake pressure controlled for the anti-compound connection if one or more preconditions are met and the first service brake pressure is above the service brake pressure threshold. The check to determine whether the first service brake pressure is above or below the service brake pressure threshold is provided, in particular, for the intermediate range between the first and second parking brake pressure thresholds. In this intermediate range, the parking brake pressure is such that the spring-applied brake cylinder is only partially engaged or released, and therefore the decision as to whether or not the anti-compound function should be activated depends on the level of the service brake pressure. If, for example, this pressure is rather low, the service brake would also only engage to a limited extent.This would mean that only minimal ventilation of the spring brake cylinder would occur, reducing the risk of overloading. The anti-compound function can then be activated. However, if the service brake pressure is rather high, i.e., above the threshold, it is advantageous not to activate the anti-compound function, but instead to use the spring brake cylinders to hold the vehicle in place. This reduces air consumption.

[0018] The service brake pressure threshold is preferably calculated based on the determined parking brake pressure. In this way, the service brake pressure threshold is dependent on the level of the determined parking brake pressure. This allows for a better distinction as to whether the anti-compound function should be implemented or not.

[0019] Preferably, the service brake pressure threshold is calculated from the formula: pSW = pB + K1.

[0020] Here, K1 is a constant that includes an offset value OW and / or a tolerance value TW. The tolerance can be, for example, -0.5 bar. The offset value is preferably predefined based on a desired additional safety margin, but can also be 0 [bar or MPa]. Preferably, however, the offset value is chosen to be > 0 [bar or MPa]. Alternatively, the service brake pressure threshold can also be calculated according to the following formula: pSW = pV3 + K2 - pB, where K2 is again a constant that includes a K2 offset value OW2 and / or a K2 tolerance value TW2, and pV3 is the level of the supply pressure of the compressed air reservoir provided for the parking brake module. The tolerance value can again be, for example, -0.5 bar. In this case, the service brake pressure threshold also depends on the level of the supply pressure in the compressed air reservoir provided for the spring brake cylinder.If the pressure in the reservoir is high, complete ventilation and thus complete release of the spring brake cylinder can be achieved. However, if the reservoir pressure is rather low, it may be that the spring brake cylinder can only be partially released or not at all. In this case, an anti-compound function should not be activated, as this can lead to overloading.

[0021] Alternatively, the service brake pressure threshold can also be calculated using the following formula: pSW = (pB + K3) * (pV3_actual) / (pV3_target) where K3 is a constant that includes an offset value and / or a tolerance value, pV3_actual is the current supply pressure of the compressed air reservoir intended for the parking brake module, and pV3_target is the target supply pressure of the compressed air reservoir intended for the parking brake module. pV3_actual can be determined using a suitable pressure sensor, and pV3_target can be stored as a parameter in a control unit.

[0022] According to a preferred embodiment, the electronically controlled pneumatic brake system includes a decoupling unit that connects the first brake pressure modulator to the anti-compound port for controlling the first service brake pressure. The anti-compound unit prevents the first service brake pressure controlled for the anti-compound port from being applied. The decoupling unit is preferably pneumatically connected between the first brake pressure modulator and the anti-compound port of the parking brake module. This means that the first service brake pressure is supplied to the anti-compound port of the parking brake module via the decoupling unit from the first service brake pressure modulator.The decoupling unit is preferably electronically connected to the anti-compound unit, and the anti-compound unit provides a signal to the decoupling unit which causes the decoupling unit to block or not block the control signal.

[0023] Preferably, the decoupling unit comprises an electromagnetically switchable decoupling valve. The electromagnetically switchable decoupling valve can, for example, be a 2 / 2-way valve, which is preferably open when de-energized and closed when energized. In this embodiment, to prevent the first service brake pressure, controlled for the anti-compound connection, from being applied, the electromagnetically switchable decoupling valve must be energized and moved into a closed position.

[0024] In a second aspect, the aforementioned problem is solved by a method for implementing an anti-compound function in an electronically controlled pneumatic braking system, wherein the electronically controlled pneumatic braking system is preferably an electronically controlled pneumatic braking system according to one of the preferred embodiments of an electronically controlled pneumatic braking system described above according to the first aspect of the invention. It should be understood that the electronically controlled pneumatic braking system according to the first aspect of the invention and the method according to the second aspect of the invention have the same and similar sub-aspects, as set out in particular in the dependent claims.

[0025] The method preferably comprises the steps of: checking one or more preconditions; determining a parking brake pressure controlled by a parking brake module at a first spring-applied brake cylinder; comparing the determined parking brake pressure with a first parking brake pressure threshold; and, if the one or more preconditions are met and the parking brake pressure is below the first parking brake pressure threshold: preventing the application of a first service brake pressure controlled for the anti-compound connection.

[0026] In a preferred embodiment, the method comprises the following steps: if one or more preconditions are met and the parking brake pressure is above a second parking brake pressure threshold that is greater than the first parking brake pressure threshold: converting a service brake pressure controlled at the anti-compound port to perform the anti-compound function.

[0027] Furthermore, the method preferably comprises the following steps: if one or more preconditions are met and a first service brake pressure is below a service brake pressure threshold: converting a service brake pressure controlled at the anti-compound port to perform the anti-compound function.

[0028] In a preferred further development, the procedure comprises the following steps: if one or more preconditions are met and the first service brake pressure is above the service brake pressure threshold: preventing the conversion of a service brake pressure controlled at the anti-compound port.

[0029] In a third aspect, the aforementioned problem is solved by a commercial vehicle with a front axle, at least one rear axle, and an electronically controlled pneumatic braking system according to one of the preferred embodiments of an electronically controlled braking system described above, as described in the first aspect of the invention. It should be understood that the commercial vehicle with the electronically controlled pneumatic braking system thus formed can also implement or incorporate the method according to the second aspect of the invention. Preferably, the first brake pressure modulator is a rear axle modulator on a rear axle of the commercial vehicle, and a first spring-applied brake cylinder and preferably a second spring-applied brake cylinder are also provided on this rear axle.Preferably, the first brake pressure modulator is a two-channel modulator and, in addition to the first service brake pressure, which is intended for, for example, a right side of the vehicle, controls a second service brake pressure, which is then intended for the left side of the vehicle.

[0030] Embodiments of the invention are now described below with reference to the drawings. These drawings are not necessarily intended to represent the embodiments to scale; rather, where this is helpful for clarification, the drawings are presented in a schematic and / or slightly distorted form. With regard to additions to the teachings directly apparent from the drawings, reference is made to the relevant prior art. It should be noted that numerous modifications and changes concerning the form and details of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, the drawings, and the claims can be essential for the further development of the invention, both individually and in any combination.Furthermore, the invention encompasses all combinations of at least two of the features disclosed in the description, the drawings, and / or the claims. The general idea of ​​the invention is not limited to the exact shape or detail of the preferred embodiments shown and described below, nor is it limited to an object that would be restricted compared to the object claimed in the claims. Where specified dimensioning ranges are given, values ​​lying within the stated limits are also disclosed as limit values ​​and may be used and claimed as desired. For the sake of simplicity, identical or similar parts, or parts with identical or similar functions, are used below as reference numerals.

[0031] Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiments and from the drawings; these show in:

[0032] Fig. 1 shows a schematic overview of part of an electronically controlled pneumatic braking system for a commercial vehicle;

[0033] Fig. 2 shows another view of the schematic view according to Fig. 1 with additional elements;

[0034] Fig. 3 shows a flowchart of a method for implementing an anti-combustion function in an electronically controlled pneumatic braking system; and in

[0035] Fig. 4 shows a commercial vehicle.

[0036] An electronically controlled pneumatic braking system 1 comprises at least one first brake pressure modulator 2 and an electropneumatic parking brake module 4. The first brake pressure modulator 2 is preferably configured as a rear axle modulator, but it can also be configured as a front axle modulator or as an axle modulator for another axle, such as an auxiliary axle. The brake pressure modulator 2 will be shown in detail in Fig. 2, but can be configured as known in the prior art. The first brake pressure modulator 2 is configured as a single-channel modulator and is supplied by a first compressed air reservoir 6 with a reservoir pressure pV. The first brake pressure modulator 2 has a working port 8. At the working port 8, the first brake pressure modulator 2 provides a first service brake pressure pSB1.The working port 8 is shown schematically here connected via a first brake pressure line 10 to a first service brake cylinder 12, which is closed when the first service brake pressure pSB1 is applied and open when depressurized. Furthermore, a second brake pressure line 11 is connected to the working port 8, leading to a second service brake cylinder (not shown) located on the same axis as the first service brake cylinder.

[0037] The electropneumatic parking brake module 4 is connected to a second compressed air reservoir 14 and receives pressure pV from this reservoir. The parking brake module 4 can also be designed as known in the prior art, but is also shown in detail in Fig. 2. It has a spring brake port 16, at which the parking brake module 4 controls a parking brake pressure pB. A first spring brake cylinder 18 is connected to the spring brake port 16. The first service brake cylinder 12 and the first spring brake cylinder 18 are combined here in a so-called combination cylinder or tristop cylinder. In addition to the spring brake port 16, the electropneumatic parking brake module 4 has an auxiliary port 17, which can be connected, for example, to a trailer control module (not shown here) or other units. The parking brake pressure pB or an inverse pressure can also be controlled at the auxiliary port 17.

[0038] The electropneumatic parking brake module 4 is configured to receive the first service brake pressure pSB1 from the first brake pressure modulator 2 via an anti-compound line 20. The anti-compound line 20 branches off from the first brake pressure line 10, but could also be connected directly to the working port 8, or to a separate port on the first brake pressure modulator. Via the anti-compound line 20, the first brake pressure modulator 2 can supply the electropneumatic parking brake module 4 with the first service brake pressure pSB1, and the electropneumatic parking brake module 4 is then configured to control the parking brake pressure pB at a corresponding level, so that the spring brake cylinder 18 is released to the same extent as the service brake cylinder 12 is closed.This process, known as anti-compound, serves to prevent overload due to doubling of the braking forces by the first service brake cylinder 12 and the first spring-applied brake cylinder 18, by releasing the spring-applied brake cylinder 18 to the same extent as the first service brake cylinder 12 is compressed.

[0039] However, within the scope of the invention described herein, this anti-compound function 19 is only carried out if certain criteria are met, which are described in more detail below with reference to Figs. 2 and 3.

[0040] Figure 1 further shows that the first brake pressure modulator 2 is connected to a pneumatic brake pressure sensor 22, via which a pneumatic brake pressure sensor pressure pBST can be controlled. The brake pressure sensor 22 can also have one, two, or more electrical lines via which the driver's braking request can also be controlled electrically, in particular to a central module, or directly to the first brake pressure modulator 2. The brake pressure sensor pressure pBST is typically used as a redundancy pressure and is implemented particularly in the event of a fault in the electronically controlled pneumatic braking system, for example, if it is de-energized. Figure 1 shows in particular that, unlike in the prior art, the brake pressure sensor pressure pBST is not used to control the anti-compound function, but rather the first service brake pressure pSB1 controlled by the first brake pressure modulator 2. This is shown in Figure 1.The layout shown in Fig. 1 is particularly advantageous because, according to the layout shown in Fig. 1, a decoupling unit 24 is provided in the anti-compound line 2, which, depending on its status and other conditions, can block or release the control of the first service brake pressure pSB1 at the electro-pneumatic parking brake module 4, more precisely at the anti-compound connection 21 of the electro-pneumatic parking brake module 4. Fig. 2 shows a somewhat more detailed representation of the electronically controlled pneumatic brake system 1, in which identical and similar elements are provided with the same reference numerals as in Fig. 1, and thus full reference is made to the description of Fig. 1. In the following, differences and details not shown in Fig. 1 are highlighted in particular.

[0041] Figure 2 shows the electronic control unit 26, which is connected to both the first brake pressure modulator 2 and the electropneumatic parking brake module 4. The electronic control unit 26 has an anti-compound unit 28, which includes a preconditions test unit 30 and a parking brake pressure test unit 32. The electronic control unit 26 is also connected to the brake pressure sensor 22 and receives an electronic brake pressure sensor signal SBST from it. In the embodiment shown here, the first brake pressure modulator 2 also has an electronic brake pressure modulator control unit 34. The electropneumatic parking brake module 4 also has an electronic parking brake module control unit 36.Preferably, the brake pressure modulator control unit 34 and the parking brake module control unit 36 ​​are connected to the electronic control unit 26 via a CAN bus connection and receive signals from it, such as a brake request signal SA, which specifies a desired brake pressure for axle 201, 202, on which the first brake pressure modulator 2 is effective, as well as a parking brake signal SF, which the electronic control unit 26 provides to the parking brake module 4 for actuating or releasing the parking brake. Furthermore, other signals can be exchanged, such as, in particular, a parking brake pressure signal SDF, which is detected by a parking brake pressure sensor 38 of the parking brake module 4 and indicates the value of the parking brake pressure pB controlled at the spring brake connection 16.Furthermore, the electronic control unit 26 receives at least one first service brake pressure signal SSB1 from the first brake pressure modulator 2, which is detected by a first service brake pressure sensor 40 and indicates the level of the first service brake pressure pSB1. The first brake pressure modulator 2 is designed here as a two-channel axis modulator and comprises, in a known manner, an electropneumatic inlet-outlet valve unit 42 with three electropneumatic valves per channel, which are electrically controlled by the brake pressure modulator control unit 34. Each channel is also assigned a relay valve, namely a first relay valve 43.1 for the first channel and a second relay valve 43.2 for the second channel, which, in a known manner, amplify the control pressure provided by the inlet-outlet valve unit 42 and control it at the first channel, here at the first working port 8, or at the second working port 9, which is provided for the second channel.A second service brake pressure pSB2 is therefore controlled at the second working port 9. It can be provided that the first working port 8 is for the right side of the vehicle and the second working port 9 for the left side, preferably on the same axle, or for different axles, such as working port 8 for a rear axle (HA) and working port 9 for a front axle (VA). A second service brake pressure sensor 41 is assigned to the second channel, which detects the second service brake pressure pSB2 and provides a corresponding second service brake pressure signal SSB2 to the electronic control unit 26.

[0042] The electropneumatic parking brake module 4 can also be designed in principle as known in the prior art and comprises a parking brake pilot control unit 44, which here is formed from a bistable valve and a monostable valve, as well as a parking brake relay valve 46, which in turn amplifies the pilot pressure controlled by the parking brake pilot control unit 44 in a known manner and provides it as parking brake pressure pB at the spring accumulator port 16 and the auxiliary port 17.

[0043] It should be understood that the invention is not limited to the fact that the electropneumatic parking brake module 4 and the first brake pressure modulator 2 have their own control units 34, 36, but rather the invention can also be implemented with a parking brake module and a brake modulator that do not have their own intelligence, but directly controlled electropneumatic valves.

[0044] The electronic control unit 26 is also connected to the decoupling unit 24, which, according to the embodiment shown here, has an electropneumatically switchable decoupling valve 25, more precisely designed here as a monostable 2 / 2-way valve. The decoupling valve 25 has a first decoupling valve port 25.1 and a second decoupling valve port 25.2. The first decoupling valve port 25.1 is connected to the first working port 8, and the second decoupling valve port 25.2 is connected to the anti-compound port 21. The decoupling valve 25 is de-energized in the open switching position shown in Fig. 2, while it is energized in the closed switching position (not shown in Fig. 2). To close the valve, the electronic control unit 26 provides a decoupling signal SE to the decoupling unit 24.This then closes the decoupling valve 25, so that the first service brake pressure pSB1 cannot be provided at the anti-combustion port 21.

[0045] Fig. 3 shows the sequence of a method for carrying out an anti-compound function in an electronically controlled pneumatic braking system 1, in particular one as shown in Figs. 1 and 2.

[0046] The procedure is preferably carried out using the electronic control unit 26, and in particular the anti-compound unit 28. In step S1, a service brake request is first received, for example via the brake force sensor 22, and in particular via the electronic brake force sensor signal SBST. Alternatively, a brake request signal can also be received from an autonomous driving unit 48, which is also connected to the electronic control unit 26. Such a brake request signal typically triggers the application of the first and second service brake pressures pSB1 and pSB2, so it should then be checked whether an anti-compound function should be implemented.

[0047] In step S2, it is checked whether one or more preconditions PK are met. This is preferably carried out using the precondition check unit 30 of the anti-compound unit 28. Such preconditions PK can be, for example, vehicle standstill PK1, which can be determined, for example, using wheel speed sensors. Other preconditions PK are, for example: engine ignition switched off PK2; parking brake switch activated PK3; spring brake cylinder vented PK4. If these preconditions PK, PK1, PK2, PK3, PK4 are not met, step S3 follows, namely, the service brake request is implemented and the first or second service brake pressure pSB1, pSB3 is controlled and can also be provided at the anti-compound connection 21.If the preconditions are not met, for example because the vehicle is in a moving state, the spring brake cylinders are already released and the first service brake pressure pSB1 can be provided as anti-compound pressure at the anti-compound port 21, which merely ensures that the spring brake cylinders remain released.

[0048] However, if it is determined that the preconditions are not met, a check of the parking brake pressure pB follows in step S4. This is preferably carried out using the parking brake pressure test unit 32. For this purpose, the parking brake pressure test unit 32 receives the parking brake pressure signal SDF from the parking brake pressure sensor 38. If the parking brake pressure pB is below a predetermined first parking brake pressure threshold pB1, the application of the first service brake pressure pSB1 is prevented, preferably by switching the decoupling valve 25. At the same time, the electronic control unit 26 or the anti-combustion unit 28 can provide a signal to the first brake pressure modulator 2 indicating that the first or second service brake pressure pSB1, pSB2, respectively, should not be applied.However, if in step S4 it is determined that the parking brake pressure pB is above the first parking brake pressure threshold pB1 and, in particular, above a second parking brake pressure threshold pB2, the service brake request is implemented and the first and second service brake pressures pSB1 and pSB2 are released. The decoupling unit 24 can remain open during this process. The second parking brake pressure threshold pB2 is selected such that if the parking brake pressure pB exceeds this threshold, the spring brake cylinder(s) 18 are released, and therefore the service brake pressure pSB1 and pSB2 can be released without risk.

[0049] If the determined parking brake pressure pB lies between the first parking brake pressure threshold pB1 and the second parking brake pressure threshold pB2, the process continues to step S7. In step S7, the service brake pressure is then checked, preferably using the service brake pressure test unit 31 of the anti-compound unit 28. This can preferably be done using the first service brake pressure sensor 40, which provides a corresponding first service brake pressure signal SSB1 to the electronic control unit 26, so that the anti-compound unit 28 can receive and process this signal. If this determined service brake pressure pSB1 is less than a service brake pressure threshold pSW, the brake request is executed in step S8 and the first or second service brake pressure pSB1, pSB2 is applied. The anti-compound connection 21 is also enabled and the decoupling unit 24 is switched to the open position shown in Fig. 2.However, if the requested service brake pressure pSB1, pSB2 is above the service brake pressure threshold pSW, the implementation of the service brake pressure pSB1 is prevented in step S9 and, in particular, the decoupling unit 24 is switched to the closed position.

[0050] The service brake pressure threshold pSW can be calculated depending on the parking brake pressure pB, as described above.

[0051] Figure 4 clearly shows a commercial vehicle 200 with a first axle 201, which here is a rear axle HA, and a second axle 202, which here is a front axle VA. The commercial vehicle 200 has an electronically controlled pneumatic braking system 1, as described above.

[0052] Reference mark (part of the description)

[0053] Electronically controlled pneumatic braking system, first brake pressure modulator, electropneumatic parking brake module, first compressed air reservoir

[0054] (first) working port second working port first brake pressure line first brake pressure line first service brake cylinder second compressed air reservoir

[0055] Spring storage connection

[0056] Auxiliary connection first spring brake cylinder

[0057] Anti-compound function

[0058] Anti-compound line

[0059] Anti-compound connector

[0060] Brake sensor

[0061] Decoupling unit, electromagnetically switchable decoupling valve, first decoupling valve connection, second decoupling valve connection, electronic control unit

[0062] Anti-compound unit

[0063] Preconditions check unit

[0064] Service brake pressure test unit

[0065] Parking brake pressure test unit

[0066] Brake pressure modulator control unit

[0067] Parking brake module control unit

[0068] Parking brake pressure sensor, first service brake pressure sensor, second service brake pressure sensor

[0069] Inlet-outlet valve unit first relay valve 43.2 second relay valve

[0070] 44 Parking brake pilot unit

[0071] 46 Parking brake relay valve

[0072] 48 units for autonomous driving

[0073] 200 commercial vehicles

[0074] 201 first axis

[0075] 202 second axis

[0076] Rear axle

[0077] OW offset value pB parking brake pressure pB1 first parking brake pressure threshold pB2 second parking brake pressure threshold pBST brake pressure sensor

[0078] PK, PK1-PK4 Preconditions pSB1 First service brake pressure pSB2 Second service brake pressure pSW Service brake pressure threshold pV Storage pressure

[0079] SBST electronic brake force sensor signal

[0080] SDF parking brake pressure signal

[0081] SE decoupling signal

[0082] SF parking brake signal

[0083] SSB1 first service brake pressure signal

[0084] SSB2 second service brake pressure signal

[0085] S1-S9 Step 1 to Step 9

[0086] TW tolerance value

[0087] VA front axle

Claims

Patent claims 1. Electronically controlled pneumatic braking system (1) for a commercial vehicle (200), with - at least one first service brake cylinder (12) and one first spring brake cylinder (18) on a first axle (201); - an electropneumatic first brake pressure modulator (2) on the first axle (201 ) for controlling a first service brake pressure (pSB1 ) at the first service brake cylinder (12); - an electropneumatic parking brake module (4) for controlling a parking brake pressure (pB) at the first spring brake cylinder (18), wherein the parking brake module (4) has an anti-compound port (21) which is connected to the first brake pressure modulator (2) for receiving the first service brake pressure (pSB1); and - an electronic control unit (26) connected to the first brake pressure modulator (2) and the parking brake module (4); wherein the electronic control unit (26) comprises an anti-compound unit (28) with - a precondition check unit (30) for checking one or more preconditions (PC); and - a parking brake pressure test unit (32) for determining the parking brake pressure (pB), wherein the parking brake pressure test unit (32) is further designed to prevent the conversion of a first service brake pressure (pSB1) controlled for the anti-compound connection (21) in the event that one or more preconditions (PK) are met and the parking brake pressure (pB) is below a first parking brake pressure threshold (pB1).

2. Electronically controlled pneumatic braking system (1) according to claim 1, wherein the one or more preconditions (PK) are selected from: vehicle stationary (PK1); engine ignition switched off (PK2); parking brake switch activated (PK3); spring brake cylinder vented (PK4).

3. Electronically controlled pneumatic braking system (1) according to claim 1 or 2, wherein the anti-compound unit (28) is configured to, in the event that one or more preconditions (PK) are met, and the parking brake pressure (pB) Above a second parking brake pressure threshold (pB2) that is greater than the first parking brake pressure threshold (pB1), a conversion of a first service brake pressure (pSB1) controlled for the anti-compound connection (21) is permitted.

4. Electronically controllable pneumatic braking system (1) according to one of the preceding claims, wherein the anti-compound unit (28) comprises a service brake pressure test unit (31) for determining the first service brake pressure (pSB1 ).

5. Electronically controlled pneumatic braking system (1) according to claims 3 and 4, wherein the anti-compound unit (28) is configured to allow, in the event that one or more preconditions (PK) are met and the first service brake pressure (pSB1) is below a service brake pressure threshold (pSW), a conversion of a first service brake pressure (pSB1) controlled for the anti-compound connection (21).

6. Electronically controlled pneumatic braking system (1) according to claim 3 and 4 or claim 5, wherein the anti-compound unit (28) is configured to prevent the conversion of a first service brake pressure (pSB1) controlled for the anti-compound connection (21) in the event that one or more preconditions (PK) are met and the first service brake pressure (pSB1) is above the service brake pressure threshold (pSW).

7. Electronically controllable pneumatic braking system (1) according to claim 5 or 6, wherein the service brake pressure threshold (pSW) is calculated based on the determined parking brake pressure (pB).

8. Electronically controlled pneumatic braking system (1) according to claim 7, wherein the service brake pressure threshold (pSW) is calculated according to the following formula: pSW = pB + K1 ; where K1 is a constant comprising an offset value (OW) and / or a tolerance value (TW).

9. Electronically controlled pneumatic braking system (1) according to claim 7, wherein the service brake pressure threshold (pSW) is calculated according to the following formula: pSW = pV3 + K2 - pB where K2 is a constant comprising a K2 offset value (OW2) and / or a K2 tolerance value (TW2), and pV3 is the supply pressure (pV) for the electropneumatic parking brake module (4).

10. Electronically controllable pneumatic braking system (1) according to one of the preceding claims, comprising a decoupling unit (24) which connects the first brake pressure modulator (2) to the anti-compound port (21) for controlling the first service brake pressure (pSB1), wherein the anti-compound unit (28) blocks the first service brake pressure (pSB1) controlled for the anti-compound port (21) from being converted.

11. Electronically controllable pneumatic braking system (1) according to claim 9, wherein the decoupling unit (24) has an electromagnetically switchable decoupling valve (25).

12. Method for implementing an anti-compound function (19) in an electronically controlled pneumatic braking system (1), preferably an electronically controlled pneumatic braking system (1) according to one of the preceding claims, comprising the steps: - Checking (S2) one or more preconditions (PK); - Determining (S4) a parking brake pressure (pB) controlled by a parking brake module (4) at a first spring brake cylinder (18); - Comparing the determined parking brake pressure (pB) with a first parking brake pressure threshold value (pB1); and - if one or more preconditions (PK) are met, and the parking brake pressure (pB) is below the first parking brake pressure threshold (pB1 ): Prevent (S5) a first service brake pressure (pSB1) controlled for the anti-compound connection (21 ) from being implemented.

13. The method of claim 11, comprising the steps of: - if one or more preconditions (PK) are met, and the parking brake pressure (pB) is above a second parking brake pressure threshold (pB2) that is greater than the first parking brake pressure threshold (pB1): Converting a service brake pressure (pSB) controlled at the anti-compound port (21) to perform the anti-compound function (19).

14. The method of claim 11 or 12, comprising the steps of: - if one or more preconditions (PK) are met, and a first service brake pressure (pSB1 ) is below a service brake pressure threshold (pSW): Converting a service brake pressure (pSB) controlled at the anti-compound port (21 ) to perform the anti-compound function (19).

15. Method according to any one of claims 11 to 13, comprising the steps: - if one or more preconditions (PK) are met, and the first service brake pressure (pSB1 ) is above the service brake pressure threshold (pSW): Preventing the conversion of a service brake pressure (pSB) controlled at the anti-compound port (21 ).

16. Commercial vehicle (200) with a front axle (VA), at least one rear axle (HA) and an electronically controlled pneumatic braking system (1) according to one of claims 1 to 10.

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