Compressed air brake device, and motor vehicle comprising such a compressed air brake device

Abstract

The invention relates to a compressed air brake device (1) for a motor vehicle, in particular a utility vehicle, comprising a pneumatic front axle brake circuit (3) and at least one pneumatic rear axle brake circuit (5). A first valve device (7.1) is arranged fluidically between the front-axle brake circuit (3) and the rear-axle brake circuit (5), said valve device being designed to be switched from a normal state, in which the rear-axle brake circuit (5) is fluidically separated from the front-axle brake circuit (3), into a failure state in response to a trigger signal, wherein in the failure state, the rear-axle brake circuit (5) is fluidically connected to the front-axle brake circuit (3) such that the rear-axle brake circuit (5) can be supplied with supply air, which is supplied from the front-axle brake circuit (5), as failure brake air in order to pneumatically brake at least one rear axle.

Description

[0001] Daimler Truck AG Lierheimer

[0002] April 29, 2024

[0003] Compressed air braking device and motor vehicle with such a compressed air braking device

[0004] The invention relates to a compressed air braking device and a motor vehicle with such a compressed air braking device.

[0005] It is known that motor vehicles, especially commercial vehicles, have at least two brake circuits, with a front-axle brake circuit assigned to a front axle and a rear-axle brake circuit assigned to a rear axle. Even if one brake circuit fails, it is necessary that the motor vehicle can be braked reliably and safely using the other brake circuit. In particular, commercial vehicles must always have a minimum deceleration of 2.2 m / s. 2be guaranteed. In the event of a brake circuit failure, the remaining brake circuit is in most cases insufficient to achieve the minimum deceleration and thus ensure safe and reliable braking. To achieve the minimum deceleration in the event of a brake circuit failure, the parking brake is used to generate additional deceleration, particularly by venting a spring-loaded brake cylinder.

[0006] The disadvantage is that the additional deceleration can only be adjusted and / or dosed imprecisely using the parking brake, resulting in either too little additional deceleration, or too slow or too fast additional deceleration. If the additional deceleration is too little, or too slow, braking cannot be achieved safely and quickly. If the additional deceleration is applied too quickly, the braked wheels will lock, and safe braking is also impossible.

[0007] The invention is therefore based on the object of creating a compressed air braking device and a motor vehicle with such a compressed air braking device, wherein the aforementioned disadvantages are at least partially remedied, preferably avoided.

[0008] The problem is solved by providing the present technical teaching, in particular the teaching of the independent claims and the embodiments disclosed in the dependent claims and the description. The problem is solved in particular by creating a compressed air brake device for a motor vehicle, in particular a commercial vehicle, with a pneumatic front-axle brake circuit and at least one pneumatic rear-axle brake circuit. A first valve device is fluidically arranged between the front-axle brake circuit and the rear-axle brake circuit. The first valve device is configured to be switched from a normal state, in which the rear-axle brake circuit is fluidically separated from the front-axle brake circuit, to a failure state in response to a trigger signal.In the failure state, the rear axle brake circuit is fluidically connected to the front axle brake circuit in such a way that the rear axle brake circuit can be supplied with supply air supplied from the front axle brake circuit as failure brake air for the pneumatic braking of at least one rear axle.

[0009] In the event of a malfunction of the rear axle brake circuit, the front axle brake circuit is advantageously used to use the lost brake air to ensure safe, particularly well-dosed or dosed and reliable braking.

[0010] In one embodiment, the trigger signal is a pressure difference and / or a change in the pressure difference between a failure brake air pressure of the failure brake air and a rear axle brake air pressure of the rear axle brake air.

[0011] The first valve device is preferably a shuttle valve. In particular, a first inlet of the shuttle valve is fluidly connected to the front axle brake circuit. In addition, in particular, a second inlet of the shuttle valve is fluidly connected to the rear axle brake circuit. Furthermore, in particular, an outlet of the shuttle valve is fluidly connected to at least one brake cylinder of the at least one rear axle of the motor vehicle. In particular, the shuttle valve has a switching device configured to fluidly connect the second inlet to the outlet in the normal state and to fluidly connect the first inlet to the outlet in the failure state.

[0012] Particularly preferably, the first valve device, in particular the shuttle valve, in particular the switching device of the shuttle valve, is prestressed, in particular in the direction of the first inlet, so that the first valve device, in particular the shuttle valve, is in the normal state by default, in particular when the inlets are not pressurized. In particular, the first valve device, in particular the shuttle valve, is configured such that the first valve device, in particular the first shuttle valve, switches from the normal state to the failure state when the pressure difference is greater than zero, in particular greater than a first predetermined pressure difference threshold—defined in particular by the prestress.Alternatively or additionally, the first valve device, in particular the shuttle valve, is configured such that the first valve device, in particular the shuttle valve, switches from the failure state to the normal state when the pressure difference is less than zero, in particular less than a second predetermined pressure difference threshold. Particularly preferably, the first predetermined pressure difference threshold and the second predetermined pressure difference threshold are identical. In particular, the first predetermined pressure difference threshold and the second predetermined pressure difference threshold are defined by the bias voltage of the switching device.

[0013] In particular, the first valve device is configured such that, when the rear axle brake air pressure drops due to a malfunction, in particular a leak, and thus braking of the rear axle is no longer reliably possible, the device switches from the normal state to the failure state, whereby at least one brake cylinder of the at least one rear axle is supplied with supply air supplied from the front axle brake circuit as failure brake air for pneumatic braking.

[0014] According to a further development of the invention, the compressed air brake device has a front-axle air supply. The front-axle air supply is fluidly connected to the first valve device such that, in the failure state, the supply air from the front-axle air supply is supplied to the rear-axle brake circuit.

[0015] Preferably, the front axle air supply is fluidically connected to the first inlet of the shuttle valve.

[0016] In particular, the compressed air brake device has a rear-axle air supply. The rear-axle air supply is fluidically connected to the first valve device such that, in the normal state, the rear-axle brake air is supplied to the rear-axle brake circuit from the rear-axle air supply. Preferably, the rear-axle air supply is fluidly connected to the second inlet of the shuttle valve.

[0017] According to a further development of the invention, a second valve device is arranged fluidically between the front axle brake circuit and the first valve device. The second valve device is configured to adjust the fail-over brake air pressure of the fail-over brake air for pneumatic braking between the first valve device and the second valve device as a function of a control pressure. Advantageously, this makes it possible to suitably adjust the fail-over brake air pressure so that locking of the rear axle is avoided.

[0018] In particular, the second valve device is configured to adjust the failure brake air pressure of the failure brake air for pneumatic braking between the first valve device and the second valve device as a function of the front axle brake air pressure of the front axle brake air for pneumatic braking in the front axle brake circuit.

[0019] The second valve device is preferably a first pressure regulating valve. In particular, an inlet of the first pressure regulating valve is fluidly connected to the front axle air supply. In addition, in particular, a control inlet of the first pressure regulating valve is fluidly connected to the front axle brake circuit. Furthermore, an outlet of the first pressure regulating valve is fluidly connected to the first valve device, in particular to the first inlet of the shuttle valve. In particular, the front axle air supply has supply air with a supply air pressure, wherein the supply air pressure is greater than the front axle brake air pressure. In particular, the first pressure regulating valve is thus configured to adjust, in particular to regulate, the failure brake air pressure of the failure brake air to the front axle brake air pressure.

[0020] According to a further development of the invention, a third valve device is arranged fluidically between the front axle brake circuit and the first valve device. The third valve device is configured to limit a limited fail-over brake air pressure of the fail-over brake air for pneumatic braking between the first valve device and the third valve device to a predetermined limit pressure value. In particular, the third valve device generates a delayed pressure build-up of the fail-over brake air, so that the rear axle is advantageously not braked abruptly and / or locking of the rear axle is avoided.

[0021] In particular, the third valve device is arranged fluidically between the first valve device and the second valve device.

[0022] In particular, the predetermined limit pressure value is from at least 3.5 bar to at most 3.7 bar. Preferably, the third valve device is a pressure relief valve. In particular, an output of the pressure relief valve is fluidly connected to the first valve device, in particular to the first input of the shuttle valve. Furthermore, an input of the pressure relief valve, particularly in the absence of the second valve device, is fluidly connected to the front axle brake circuit or to the front axle air supply. Alternatively, the input of the pressure relief valve is fluidly connected to the second valve device, in particular to the output of the first pressure control valve.

[0023] According to a further development of the invention, a fourth valve device is arranged fluidically between the front axle brake circuit and the first valve device. The fourth valve device is operatively connected to a weight detection device. The weight detection device is configured to detect a weight bearing on the at least one rear axle and, depending thereon, to transmit a weight signal to the fourth valve device. The fourth valve device is configured to set a weight-adjusted fail-over brake air pressure of the fail-over brake air for pneumatic braking between the fourth valve device and the first valve device depending on the weight signal. Advantageously, this makes it possible, in particular, to reduce and / or prevent overbraking of the rear axle.

[0024] In particular, the fourth valve device is arranged fluidically between the first valve device and the second valve device, in particular between the first valve device and the third valve device.

[0025] Preferably, the fourth valve device is a second pressure control valve. In particular, an output of the second pressure control valve is fluidly connected to the first valve device, in particular to the first input of the shuttle valve. Furthermore, an input of the second pressure control valve is fluidly connected to the front axle brake circuit or the front axle air supply, in particular in the absence of the second valve device and the third valve device. Alternatively, the input of the second pressure control valve is fluidly connected to the second valve device, in particular to the output of the first pressure control valve, in particular in the absence of the third valve device. Alternatively, the input of the second pressure control valve is fluidly connected to the third valve device, in particular to the output of the pressure relief valve.In particular, the second pressure control valve is configured to adjust, in particular regulate, the weight-adjusted brake air pressure of the brake air supply as a function of the weight signal. In particular, the weight signal is a bellows pressure of an air suspension of at least one rear axle.

[0026] In particular, a control input of the second pressure control valve is subjected to the bellows pressure, wherein optionally - in particular by selecting suitable valve surfaces - an over- or under-ratio is provided, so that the weight-adjusted failure brake air pressure is not necessarily regulated directly to the bellows pressure, but can deviate from it upwards or downwards.

[0027] According to a further development of the invention, a switching device is arranged fluidically between the front-axle brake circuit and the second valve device. The switching device is configured to apply the front-axle brake air pressure of the front-axle brake air as the control pressure to the second valve device, in particular the control input of the first pressure control valve, in response to a malfunction signal.

[0028] This advantageously ensures that the front axle brake air pressure, as the control pressure, is only applied to the second valve device, in particular at the control input, in the event of a malfunction. This further makes it possible to protect the other valve devices, and in particular the first valve device, from wear caused by high pressures. Furthermore, faulty switching of the first valve device due to short-term pressure fluctuations, in particular faulty switching from a normal state to a failure state, is advantageously avoided.

[0029] In particular, when the malfunction signal is present, the first valve device switches from the normal state to the failure state, in particular triggered by the pressure difference applied to the first valve device.

[0030] In particular, the switching device comprises an electric switching valve and a control device, wherein the control device is operatively connected to a pressure sensor. The pressure sensor is in particular configured to determine the rear axle brake air pressure in the rear axle brake circuit. In particular, a pressure determined by the pressure sensor is used as a malfunction signal if the rear axle brake air pressure determined by the pressure sensor is less than a predetermined malfunction pressure threshold, wherein the predetermined malfunction pressure threshold is particularly preferably 0.5 bar. Alternatively, the malfunction signal is generated in particular if the rear axle brake air pressure is less than the predetermined malfunction pressure threshold. In this case, the control device switches the front axle brake air pressure to the control input of the first pressure control valve via the electric switching valve.In particular, in the absence of the malfunction signal, the ambient pressure is applied as control pressure to the second valve device, in particular to the control input of the first pressure control valve, in particular via the electrical switching valve.

[0031] According to a further development of the invention, the pneumatic brake device has a display device. The display device is connected to the switching device, in particular to the control device, and is configured to indicate a malfunction, particularly visually. Advantageously, this makes it possible to monitor the functioning of the rear axle brake circuit and quickly detect a malfunction.

[0032] In particular, the display device has an LED, wherein the LED lights up in the event of a malfunction, in particular in the presence of the malfunction signal.

[0033] According to a further development of the invention, the pneumatic brake device comprises the first valve device as the first left valve device. The first left valve device is configured to fluidly connect the front axle brake circuit to a left brake cylinder of the at least one rear axle in the failure state, so that the left brake cylinder can be supplied with supply air supplied from the front axle brake circuit as backup brake air for pneumatic braking from the front axle brake circuit. In addition, the pneumatic brake device comprises a similarly designed and arranged first right valve device.The first right valve device is configured to fluidically connect the front axle brake circuit to a right brake cylinder of at least one rear axle in the failure state, so that the right brake cylinder can be supplied with supply air from the front axle brake circuit as backup brake air for pneumatic braking from the front axle brake circuit. Advantageously, the left and right brake cylinders are thus decoupled. This enables safe and reliable braking even if one of the brake cylinders is defective and / or causes the rear axle brake circuit to malfunction.

[0034] In one embodiment, the compressed air brake device additionally has a second right-hand valve device and the second valve device as a second left-hand valve device. The second right-hand valve device is fluidically arranged between the front axle brake circuit—in particular the front axle air supply—and the first right-hand valve device and is configured to adjust a fail-over brake air pressure of the fail-over brake air between the first right-hand valve device and the second right-hand valve device as a function of the control pressure. The second left-hand valve device is fluidically arranged between the front axle brake circuit—in particular the front axle air supply—and the first left-hand valve device and is configured to adjust a fail-over brake air pressure of the fail-over brake air between the first left-hand valve device and the second left-hand valve device as a function of the control pressure.In particular, the second right-hand valve device and the second left-hand valve device are configured and arranged analogously. Alternatively or additionally, the pneumatic brake device comprises a third right-hand valve device and the third valve device as a third left-hand valve device. The third right-hand valve device is fluidically arranged between the front-axle brake circuit—in particular the front-axle air supply—and the first right-hand valve device, in particular between the first right-hand valve device and the second right-hand valve device, and is configured to limit the limited fail-over brake air pressure of the fail-over brake air between the first right-hand valve device and the third right-hand valve device to the predetermined limit pressure value.The third left valve device is fluidically arranged between the front axle brake circuit—in particular the front axle air supply—and the first left valve device, in particular between the first left valve device and the second left valve device, and is configured to limit the limited failure brake air pressure of the failure brake air between the first left valve device and the third left valve device to the predetermined limit pressure value. In particular, the third right valve device and the third left valve device are designed and arranged analogously. Alternatively or additionally, the pneumatic brake device has a fourth right valve device and the fourth valve device as a fourth left valve device.The fourth right valve device is fluidically arranged between the front axle brake circuit—in particular the front axle air supply—and the first right valve device, in particular between the first right valve device and the third right valve device, and is operatively connected to a right weight detection device. The right weight detection device is configured to detect a weight bearing on a right side of the at least one rear axle and, depending thereon, to transmit a right weight signal to the fourth right valve device. The fourth right valve device is configured to set a weight-adjusted failure brake air pressure of the failure brake air between the fourth right valve device and the first right valve device depending on the right weight signal.The fourth left valve device is fluidically arranged between the front axle brake circuit—in particular the front axle air supply—and the first left valve device, in particular between the first left valve device and the third left valve device, and is operatively connected to a left weight detection device. The left weight detection device is configured to detect a weight bearing on a left side of the at least one rear axle and, depending thereon, to transmit a left weight signal to the fourth left valve device. The fourth left valve device is configured to set a weight-adjusted failure brake air pressure of the failure brake air between the fourth left valve device and the first left valve device depending on the left weight signal.In particular, the fourth right valve device and the fourth left valve device are designed and arranged analogously. In particular, the right weight detection device and the left weight detection device are also designed and configured analogously. Alternatively or additionally, the pneumatic brake device has the switching device, wherein the switching device is fluidically connected to the front axle brake circuit, the second right valve device, and the second left valve device. The switching device is configured to apply the front axle brake air pressure of the front axle brake air as the control pressure to the second right valve device and the second left valve device in response to the malfunction signal.

[0035] The object is also achieved in particular by providing a motor vehicle, in particular a commercial vehicle, with a compressed air braking device according to the invention or a compressed air braking device according to one or more of the previously described embodiments. In connection with the motor vehicle, the advantages already explained in connection with the compressed air braking device are particularly evident.

[0036] The invention is explained in more detail below with reference to the drawing.

[0037] Showing:

[0038] Fig. 1 is a schematic representation of a first embodiment of a compressed air braking device,

[0039] Fig. 2 is a schematic representation of a second embodiment of the pneumatic braking device,

[0040] Fig. 3 is a schematic representation of a third embodiment of the pneumatic braking device,

[0041] Fig. 4 is a schematic representation of a fourth embodiment of the pneumatic braking device,

[0042] Fig. 5 is a schematic representation of a fifth embodiment of the pneumatic brake device, and

[0043] Fig. 6 is a schematic representation of a sixth exemplary embodiment of the compressed air braking device. In all subsequent figures, a viewing direction of a compressed air braking device 1 is selected such that a front axle brake circuit 3 assigned to a front axle of a motor vehicle is shown on the left side, and a rear axle brake circuit 5 assigned to a rear axle of the motor vehicle is shown on the right side. Furthermore, the viewing direction is selected such that, in a real world, the motor vehicle having the compressed air braking device 1 is viewed from above, so that in the figures, a right side of the compressed air braking device 1 is shown at the top and a left side of the compressed air braking device 1 is shown at the bottom.

[0044] Figure 1 shows a schematic representation of a first embodiment of the compressed air braking device 1 for the motor vehicle, in particular a commercial vehicle, with the pneumatic front axle brake circuit 3 and the at least one pneumatic rear axle brake circuit 5.

[0045] A first valve device 7.1 is fluidically arranged between the front axle brake circuit 3 and the rear axle brake circuit 5. The first valve device 7.1 is configured to switch from a normal state, in which the rear axle brake circuit 5 is fluidically separated from the front axle brake circuit 3, to a failure state in response to a trigger signal. In the failure state, the rear axle brake circuit 5 is fluidically connected to the front axle brake circuit 3 such that the rear axle brake circuit 5 can be supplied with supply air supplied from the front axle brake circuit 3 as failure brake air for the pneumatic braking of at least one rear axle.

[0046] Preferably, the first valve device 7.1 is a shuttle valve 9. In particular, a first inlet 11.1 of the shuttle valve 9 is fluidly connected to the front axle brake circuit 3. In addition, in particular, a second inlet 11.2 of the shuttle valve 9 is fluidly connected to the rear axle brake circuit 5. Furthermore, in particular, an outlet 13 of the shuttle valve 9 is fluidly connected to at least one brake cylinder 15 of the at least one rear axle of the motor vehicle - in particular a left brake cylinder 15' and a right brake cylinder 15". In particular, the shuttle valve 9 has a switching device that is configured to fluidly connect the second inlet 11.2 to the outlet 13 in the normal state and to fluidly connect the first inlet 11.1 to the outlet 13 in the failure state.

[0047] In addition, the compressed air braking device 1 has at least one brake cylinder 16 of a front axle, wherein the at least one brake cylinder 16 of the front axle - in particular a left brake cylinder 16' and a right brake cylinder 16" - is supplied with brake air from the front axle brake circuit 3.

[0048] Optionally, the front axle brake circuit 3 has, in particular, a front axle air supply 17, wherein the at least one brake cylinder 16 of the front axle is fluidly connected to the front axle air supply 17. In particular, the first valve device 7.1, in particular the shuttle valve 9, in particular the first inlet 11.1 of the shuttle valve 9, is fluidly connected to the front axle air supply 17. Alternatively or additionally, the rear axle brake circuit 5 has, in particular, a rear axle air supply 19, wherein the first valve device 7.1, in particular the shuttle valve 9, in particular the second inlet 11.2 of the shuttle valve 9, is fluidly connected to the rear axle air supply 19.

[0049] In particular, a fail-over brake air with a fail-over brake air pressure, in particular from the front axle air reservoir 17, is applied to the first valve device 7.1, in particular to the first inlet 11.1 of the shuttle valve 9. Furthermore, a rear axle brake air, in particular from the rear axle air reservoir 19, with a rear axle brake air pressure is applied to the first valve device 7.1, in particular to the second inlet 11.2 of the shuttle valve 9. If a pressure difference between the failure brake air pressure of the failure brake air and the rear axle brake air pressure of the rear axle brake air is less than zero, in particular less than a first predetermined pressure difference threshold, the first valve device 7.1, in particular the first shuttle valve 9, is in the normal state, so that the at least one brake cylinder 15 of the rear axle is supplied with the rear axle brake air for pneumatic braking of the at least one rear axle.If the pressure difference between the failure brake air pressure of the failure brake air and the rear axle brake air pressure of the rear axle brake air rises above zero - in particular due to a leak in the rear axle brake circuit 5 - and in particular becomes greater than the first predetermined pressure difference threshold, the first valve device 7.1, in particular the first shuttle valve 9, switches to the failure state, so that the at least one brake cylinder 15 of the rear axle is supplied with the failure brake air for pneumatic braking of the at least one rear axle.

[0050] Figure 2 shows a schematic representation of a second embodiment of the compressed air braking device 1.

[0051] Identical and functionally identical elements are provided with the same reference numerals in all figures, so reference is made to the previous description. In addition to the pneumatic brake device 1 shown in Figure 1, the pneumatic brake device 1 shown in Figure 2 has a second valve device 7.2, in particular a first pressure control valve 21.1.

[0052] The second valve device 7.2, in particular the first pressure control valve 21.1, is fluidically arranged between the front axle brake circuit 3, in particular the front axle air reservoir 17, and the first valve device 7.1, in particular the shuttle valve 9. The second valve device 7.2, in particular the first pressure control valve 21.1, is configured to adjust the fail-over brake air pressure of the fail-over brake air for pneumatic braking between the first valve device 7.1, in particular the shuttle valve 9, and the second valve device 7.2, in particular the first pressure control valve 21.1, as a function of a control pressure, in particular the front axle brake air pressure of the front axle brake air for pneumatic braking in the front axle brake circuit 3.

[0053] In particular, an inlet 23 of the first pressure control valve 21.1 is fluidly connected to the front axle air reservoir 17. Additionally, a control inlet 25 of the first pressure control valve 21.1 is fluidly connected to the front axle brake circuit 3. Furthermore, an outlet 27 of the first pressure control valve 21.1 is fluidly connected to the first valve device 7.1, in particular the first inlet 11.1 of the shuttle valve 9.

[0054] In particular, supply air from the front axle air reservoir 17 is present at the inlet 23 of the pressure regulating valve 21.1 at a supply air pressure. In addition, the front axle brake air is present at the control inlet 25 of the first pressure regulating valve 21.1 at the front axle brake air pressure, wherein the supply air pressure is greater than the front axle brake air pressure - particularly due to additional pneumatic valve devices not shown here. In particular, the fail-safe brake air is present at the fail-safe brake air pressure between the outlet 27 of the first pressure regulating valve 21.1 and the first valve device 7.1, in particular the shuttle valve 9. In particular, the first pressure regulating valve 21.1 is configured to adjust, in particular to regulate, the fail-safe brake air pressure of the fail-safe brake air to the front axle brake air pressure.

[0055] Figure 3 shows a schematic representation of a third embodiment of the compressed air braking device 1.

[0056] The compressed air braking device 1 according to Figure 3 has, in addition to the compressed air braking device 1 according to Figure 2, at least one further valve device selected from a third valve device 7.3, in particular a pressure relief valve 29, and a fourth valve device 7.4, in particular a second pressure control valve 21.2.

[0057] The third valve device 7.3, in particular the pressure relief valve 29, is fluidically arranged between the front axle brake circuit 3, in particular the second valve device 7.2, in particular the first pressure control valve 21.1, and the first valve device 7.1, in particular the shuttle valve 9. The third valve device 7.3, in particular the pressure relief valve 29, is configured to limit a limited fail-over brake air pressure of the fail-over brake air for pneumatic braking between the first valve device 7.1, in particular the shuttle valve 9, and the third valve device 7.3, in particular the pressure relief valve 29, to a predetermined limit pressure value, preferably 3.7 bar, particularly preferably 3.5 bar.

[0058] The fourth valve device 7.4, in particular the second pressure control valve 21.2, is fluidically arranged between the front axle brake circuit 3, in particular the second valve device 7.2 or the third valve device 7.3, in particular the pressure relief valve 29, and the first valve device 7.1, in particular the shuttle valve 9. The fourth valve device 7.4, in particular the second pressure control valve 21.2, is operatively connected to a weight detection device 31. The weight detection device 31, in particular an air suspension of the rear axle, is configured to detect a weight bearing on the at least one rear axle and, depending thereon, to transmit a weight signal, in particular a bellows pressure of the air suspension, to the fourth valve device 7.4, in particular the second pressure control valve 21.2. The fourth valve device 7.4, in particular the second pressure control valve 21.2, is configured to set a weight-adjusted failure brake air pressure of the failure brake air for pneumatic braking between the fourth valve device 7.4, in particular the second pressure control valve 21.2, and the first valve device 7.1, in particular the shuttle valve 9, depending on the weight signal.

[0059] In particular, an inlet 33 of the pressure relief valve 29 is fluidly connected to the second valve device 7.2, in particular the outlet 27 of the first pressure control valve 21.1. Additionally, an outlet 35 of the pressure relief valve 29 is fluidly connected to the first valve device 7.1. Particularly preferably, the outlet 35 of the pressure relief valve 29 is fluidly connected to the fourth valve device 7.4, in particular an inlet 37 of the second pressure control valve 21.2. In particular, the fail-over brake air is present at the fail-over brake air pressure at the inlet 33 of the pressure relief valve 29, with the fail-over brake air pressure being adjusted to the front axle brake air pressure. In particular, the failure brake air is provided with a failure brake air pressure limited in particular to 3.7 bar, preferably to 3.5 bar, between the outlet 35 of the pressure relief valve 29 and the first valve device 7.1, in particular the shuttle valve 9.

[0060] In particular, the inlet 37 of the second pressure control valve 21.2 is fluidly connected to the second valve device 7.2, in particular the outlet 27 of the first pressure control valve 21.1. Particularly preferably, the inlet 37 of the second pressure control valve 21.2 is fluidly connected to the third valve device 7.3, in particular the outlet 35 of the pressure limiting valve 29. In addition, an outlet 39 of the second pressure control valve 21.1 is fluidly connected to the first valve device 7.1, in particular the first inlet 11.1 of the shuttle valve 9. Furthermore, a control inlet 41 of the second pressure control valve 21.2 is fluidly connected to the weight detection device 31. In particular, the failure brake air with the limited failure brake air pressure is present at the inlet 37 of the second pressure control valve 21.2. In addition, the weight signal is present at the control input 41 of the second pressure control valve 21.2.In particular, the failure brake air with the weight-adjusted failure brake air pressure is present between the output 39 of the second pressure control valve 21.2 and the first valve device 7.1, in particular the first input 11.1 of the shuttle valve 9.

[0061] Figure 4 shows a schematic representation of a fourth embodiment of the compressed air braking device 1.

[0062] The compressed air braking device 1 according to Figure 4 has, in addition to the compressed air braking device 1 according to Figure 3, a switching device 43.

[0063] The switching device 43 is fluidically arranged between the front-axle brake circuit 3 and the second valve device 7.2, in particular the first pressure control valve 21.1. The switching device 43 is configured to apply the front-axle brake air pressure of the front-axle brake air as the control pressure to the second valve device 7.2, in particular to the control input 25 of the first pressure control valve 21.1, in response to a malfunction signal. In particular, the ambient pressure is applied as the control pressure to the control input 25 of the first pressure control valve 21.1 when no malfunction signal is present at the switching device 43.

[0064] In particular, the malfunction signal is generated when the rear axle brake air pressure is lower than a predetermined malfunction pressure threshold, wherein the predetermined malfunction pressure threshold is particularly preferably 0.5 bar. Preferably, the switching device 43 comprises an electric switching valve 45 and a control device 47, wherein the control device 47 is operatively connected to a pressure sensor (not shown here). The pressure sensor is particularly configured to determine the rear axle brake air pressure in the rear axle brake circuit 5.

[0065] Optionally, the pneumatic brake device 1 additionally has a display device. The display device is connected to the switching device 43 and is configured to indicate a malfunction, particularly visually.

[0066] Figure 5 shows a schematic representation of a fifth embodiment of the compressed air braking device 1.

[0067] The compressed air braking device 1 according to Figure 5 has the first valve device 7.1 of the compressed air braking device 1 according to Figure 1 as a first left valve device 7.1' and a first right valve device 7.1".

[0068] For clarity, the inputs and outputs of the valve devices 7 are not provided with reference symbols.

[0069] The first left valve device 7.1' is configured to fluidically connect the front axle brake circuit to a left brake cylinder 15' of the at least one rear axle in the failure state, such that the left brake cylinder 15' can be supplied with supply air supplied from the front axle brake circuit 3 as failure brake air for pneumatic braking from the front axle brake circuit 3. The first right valve device 7.1" is configured to fluidically connect the front axle brake circuit 3 to a right brake cylinder 15" of the at least one rear axle in the failure state, such that the right brake cylinder 15" can be supplied with supply air supplied from the front axle brake circuit 3 as failure brake air for pneumatic braking from the front axle brake circuit 3.

[0070] Figure 6 shows a schematic representation of a sixth embodiment of the compressed air braking device 1.

[0071] The compressed air brake device 1 has the front axle brake circuit 3 with at least one brake cylinder 16 of the front axle. The compressed air brake device 1 also has the rear axle brake circuit 5. The rear axle brake circuit 5 is designed to brake a first rear axle, a second rear axle, and a third rear axle. In particular, the first rear axle and the second rear axle are driven, and the third rear axle is not driven. The rear axle brake circuit has a first left brake cylinder 15.1' of the first rear axle, a first right brake cylinder 15.1" of the first rear axle, a second left brake cylinder 15.2' of the second rear axle, a second right brake cylinder 15.2" of the second rear axle, a third left brake cylinder 15.3' of the third rear axle, and a third right brake cylinder 15.3" of the third rear axle.

[0072] The compressed air braking device 1 has the first left valve device 7.1' and the first right valve device 7.1" according to Figure 5. In addition, the compressed air braking device 1 has, in particular, a second left valve device 7.2' and a second right valve device 7.2". Alternatively or additionally, the compressed air braking device 1 has, in particular, a third left valve device 7.3' and a third right valve device 7.3". Alternatively or additionally, the compressed air braking device 1 has, in particular, a fourth left valve device 7.4', a fourth right valve device 7.4", a left weight detection device 31', and a right weight detection device 31". Alternatively or additionally, the compressed air braking device 1 has, in particular, the switching device 43 according to Figure 4 and, optionally, the display device.

[0073] The first left valve device 7.1' is fluidically connected to the rear axle air supply 19 and the third left brake cylinder 15.3'. The first right valve device 7.1" is fluidically connected to the rear axle air supply 19 and the third right brake cylinder 15.3". Furthermore, the first left valve device 7.1' and the first right valve device 7.1" are configured identically to the first valve device 7.1 according to Figures 1 to 4.

[0074] The second left valve device 7.2' and the second right valve device 7.2" are fluidically connected to the switching device 43. Furthermore, the second left valve device 7.2' and the second right valve device 7.2" are designed identically to the second valve device 7.2 according to Figures 2 to 4.

[0075] The third left valve device 7.3' is fluidically arranged between the second left valve device 7.2' and the fourth left valve device 7.4'. The third right valve device 7.3" is fluidically arranged between the second right valve device 7.2" and the fourth right valve device 7.4". Furthermore, the third left valve device 7.3' and the third right valve device 7.3" are identical to the third valve device 7.3 according to Figures 3 and 4. The fourth left valve device 7.4' is fluidically arranged between the third left valve device 7.3' and the first left valve device 7.1'. The fourth right valve device 7.4" is fluidically arranged between the third right valve device 7.3" and the first right valve device 7.1". In addition, the fourth left valve device 7.4' is operatively connected to the left weight detection device 31'.

[0076] Furthermore, the fourth right valve device 7.4" is operatively connected to the right weight detection device 31". The fourth left valve device 7.4' and the fourth right valve device 7.4" are configured identically to the fourth valve device 7.4 according to Figures 3 and 4. Furthermore, the left weight detection device 31' is configured to detect a weight bearing on a left side of the at least one rear axle and, depending thereon, to transmit a left weight signal to the fourth left valve device 7.4'. In addition, the right weight detection device 31" is configured to detect a weight bearing on a right side of the at least one rear axle and, depending thereon, to transmit a right weight signal to the fourth right valve device 7.4".

[0077] In particular, the front axle brake air in the front axle brake circuit 3 has the front axle brake air pressure pv Furthermore, the supply air in the front axle air reservoir 17 has the supply air pressure p w The rear axle brake air in the rear axle brake circuit 5 has the rear axle brake air pressure p H Thus, the front axle brake air pressure pv is applied to the switching device 43. Furthermore, the rear axle brake air pressure p is applied to the second input 11.2 of the first left valve device 7.1' and to the second input 11.2 of the first right valve device 7.1". H Furthermore, the switching device 43 indicates the malfunction pressure threshold p F where in particular PF=0.5 bar applies.

[0078] In a first operating state of the compressed air brake device 1, the rear axle brake circuit functions without problems and p H> PF- This means that no malfunction signal is generated, and the switching device 43 does not forward the front-axle brake air to the control inputs 25 of the second valve devices 7.2. Thus, the ambient pressure pu is present at the control inputs 25. The supply air is forwarded by the second valve devices 7.2 as backup brake air, with the backup brake air pressure p A corresponds to the ambient pressure pu. The third valve devices 7.3 and fourth valve devices 7.4 forward the fail-over brake air at the ambient pressure to the first inlets 11.1 of the first valve devices 7.1. pu = PA PH + Ap D , where Ap D is the predetermined pressure difference threshold and Ap D> 0, the first valve devices 7.1 are in the normal state, wherein the second inlet 25 of the first left valve device 7.1' is fluidically connected to the third left brake cylinder 15.3' and the second inlet 25 of the first right valve device 7.1" is fluidically connected to the third right brake cylinder 15.3", so that the rear axle brake air is used for braking with the third brake cylinders 15.3' and 15.3". pu = PA > PH + Ap D, the first valve devices 7.1 are in the failure state, wherein the first inlet 25 of the first left valve device 7.1' is fluidically connected to the third left brake cylinder 15.3' and the first inlet 25 of the first right valve device 7.1" is fluidically connected to the third right brake cylinder 15.3", so that the failure brake air is used for braking with the third brake cylinders 15.3' and 15.3". In particular, if the rear axle brake circuit is functioning properly, the rear axle brake air pressure p H greater than the ambient pressure pu, so that the first valve devices 7.1 are operated in the normal state.

[0079] In a second operating state of the compressed air brake device 1, p H< PF, particularly due to a leak in the rear axle brake circuit. This generates a malfunction signal, and the switching device 43 forwards the front axle brake air to the control inputs 25 of the second valve devices 7.2. Thus, the front axle brake air pressure p is present at the control inputs 25. v The supply air is forwarded by the second valve devices 7.2 as failure brake air, whereby the failure brake air pressure p A is adjusted to the front axle brake air pressure pv, so that between the second valve devices 7.2 and the third valve devices 7.3 p A =Pv- The third valve devices 7.3 limit the failure brake air pressure p A to 3.7 bar, in particular to 3.5 bar, so that between the third valve devices 7.3 and the fourth valve devices 7.4 p A = 3.7 bar, especially p A= 3.5 bar. The fourth valve devices 7.4 regulate the failure brake air pressure p A depending on the weight signals of the weight detection devices 31, so that at the first inputs 11.1 of the first valve devices 7.1 the failure brake air with p A < 3.7 bar, especially p A < 3.5 bar. In particular, the fourth valve devices 7.4 regulate the failure brake air pressure in such a way that p A > p F applies. Applies 3.7 bar > p A < p H + Ap D , especially 3.5 bar > p A < p H + Ap D, the first valve devices 7.1 are in the normal state, wherein the second inlet 25 of the first left valve device 7.1' is fluidically connected to the third left brake cylinder 15.3' and the second inlet 25 of the first right valve device 7.1" is fluidically connected to the third right brake cylinder 15.3", so that the rear axle brake air is used for braking with the third brake cylinders 15.3' and 15.3". Applies 3.7 bar > p A > p H + Ap D , especially 3.5 bar > p A > p H + Ap D, the first valve devices 7.1 are in the failure state, wherein the first inlet 25 of the first left valve device 7.1' is fluidically connected to the third left brake cylinder 15.3' and the first inlet 25 of the first right valve device 7.1" is fluidically connected to the third right brake cylinder 15.3", so that the failure brake air is used for braking with the third brake cylinders 15.3' and 15.3". In particular, the malfunction pressure threshold p F / the predetermined pressure difference threshold Ap D and a maximum reduction of the failure brake air pressure by means of the fourth valve devices 7.4 coordinated such that when a malfunction signal is generated, the first valve devices 7.1 are in the failure state.

Claims

Daimler Truck AG Lierheimer April 29, 2024 Patent claims 1. Compressed air brake device (1) for a motor vehicle, in particular a commercial vehicle, with a pneumatic front axle brake circuit (3) and at least one pneumatic rear axle brake circuit (5), wherein - a first valve device (7.1) is arranged fluidically between the front axle brake circuit (3) and the rear axle brake circuit (5), which first valve device is designed to be switched from a normal state, in which the rear axle brake circuit (5) is fluidically separated from the front axle brake circuit (3), to a failure state in response to a trigger signal, wherein in the failure state the rear axle brake circuit (5) is fluidically connected to the front axle brake circuit (3) in such a way that the rear axle brake circuit (5) can be supplied with supply air supplied from the front axle brake circuit (5) as failure brake air for the pneumatic braking of at least one rear axle.

2. Compressed air brake device (1) according to claim 1, with a front axle air supply (17), wherein the front axle air supply (17) is fluidically connected to the first valve device (7.1) in such a way that in the failure state the supply air from the front axle air supply (17) is supplied to the rear axle brake circuit (5).

3. Compressed air brake device (1) according to one of the preceding claims, wherein a second valve device (7.2) is arranged fluidically between the front axle brake circuit (3) and the first valve device (7.1), which second valve device is designed to control a failure brake air pressure of the failure brake air between the first valve device (7.1) and the second valve device (7.2) depending on a Control pressure, in particular a front axle brake air pressure of the front axle brake air in the front axle brake circuit (3).

4. Compressed air brake device (1) according to one of the preceding claims, wherein a third valve device (7.3) is arranged fluidically between the front axle brake circuit (3) and the first valve device (7.1), in particular between the first valve device (7.1) and the second valve device (7.2), which third valve device is designed to limit a limited failure brake air pressure of the failure brake air between the first valve device (7.1) and the third valve device (7.3) to a predetermined limit pressure value.

5. Pneumatic brake device (1) according to one of the preceding claims, wherein - a fourth valve device (7.4) is arranged fluidically between the front axle brake circuit (3) and the first valve device (7.1), in particular between the first valve device (7.1) and the third valve device (7.3), wherein - the fourth valve device (7.4) is operatively connected to a weight detection device (31), wherein - the weight detection device (31) is configured to detect a weight on the at least one rear axle and, depending thereon, to transmit a weight signal to the fourth valve device (7.4), and wherein - the fourth valve device (7.4) is configured to set a weight-adjusted failure brake air pressure of the failure brake air between the fourth valve device (7.4) and the first valve device (7.1) as a function of the weight signal.

6. Compressed air brake device (1) according to one of the preceding claims, wherein a switching device (43) is arranged fluidically between the front axle brake circuit (3) and the second valve device (7.2), which switching device is designed to apply the front axle brake air pressure of the front axle brake air as control pressure to the second valve device (7.2) in response to a malfunction signal.

7. Compressed air brake device (1) according to one of the preceding claims with a display device, wherein the display device is connected to the switching device (43), and wherein the display device is designed to display a malfunction, in particular visually.

8. Pneumatic brake device (1) according to one of the preceding claims with - the first valve device (7.1) as a first left valve device (7.1'), which is designed to fluidically connect the front axle brake circuit (3) to a left brake cylinder (15') of the at least one rear axle in the failure state, so that the left brake cylinder (15') can be supplied with supply air supplied from the front axle brake circuit (3) as failure brake air for pneumatic braking, - a first right valve device (7.1") which is designed to fluidically connect the front axle brake circuit (3) to a right brake cylinder (15") of the at least one rear axle in the failure state, so that the right brake cylinder (15") can be supplied with supply air supplied from the front axle brake circuit (3) as failure brake air for pneumatic braking.

9. Motor vehicle with a compressed air braking device (1) according to one of the preceding claims.

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