Electronic braking system for commercial vehicles, method for monitoring the functionality of valves in an electronic braking system, and commercial vehicle

Abstract

The invention relates to an electronic braking system for commercial vehicles with pneumatically actuated wheel brakes via valves, wherein the current functionality 33 of the valves is monitored. The invention further relates to a method for monitoring the current functionality 33 of valves in an electronic braking system and to a commercial vehicle with an electronic braking system. In order to enable an assessment of the current functionality of the electronically controlled valves in an electronic braking system of a commercial vehicle using the simplest possible means, the invention provides for counting the actuations 21 of the valves, relating the counted number of actuations 22 to a reference value 38, and thus determining a monitoring value 28. The monitoring value 28 is then compared with at least one predetermined reference value 24 30, and the current functionality 33 of the valves is assessed based on this comparison 30.

Description

[0001] According to claim 1, the invention relates to an electronic braking system for commercial vehicles with wheel brakes pneumatically actuated via valves, wherein the valves are electrically controlled during a braking operation, with a monitoring device for evaluating the functionality of the valves. According to claim 5, the invention also relates to a method for monitoring the functionality of valves in an electronic braking system for commercial vehicles with wheel brakes pneumatically actuated via the valves. Furthermore, according to claim 9, the invention relates to a commercial vehicle with an electronic braking system.

[0002] With an electronic braking system (EBS), faster and more precise response of the wheel brakes in commercial vehicles with pneumatic braking systems is achieved through electronic control. Depending on the configuration of the electronic braking system, the braking pressure of individual axles can be controlled or regulated independently of one another, or the braking pressure in the brake cylinders of individual wheel brakes can be individually adjusted. In an electronic braking system for commercial vehicles, an axle modulator usually regulates the brake cylinder pressure on both sides of one or two axles. An axle modulator has two pneumatically independent pressure control channels per axle, each with an inlet valve and a vent valve, each with a pressure sensor and control electronics. During braking, the inlet valves are controlled multiple times during venting and the outlet valves during venting in order to create a gradient with small pressure steps of e.g. 0.1 bar.If a leak occurs in the device, for example directly in the axle modulator or in the connecting devices or brake cylinders, more inlet valve operations are necessary to compensate for the pressure loss or fewer outlet valve operations are necessary when bleeding.

[0003] As a commercial vehicle's service life increases, the electronically controlled brake valves, particularly those in axle modulators, can wear out. While electrical wear and faults such as short circuits to ground or voltage interruptions can be detected, mechanical faults remain undetected. Mechanical defects include, for example, worn valve seats on solenoid valves, leaks in the device, and faulty piston response due to seal wear or contamination. Such mechanical defects have so far been detected during careful manual inspections. However, since manual inspections are only performed regularly at relatively long intervals, the commercial vehicle is often driven with a defect for a relatively long time. Valve defects, in particular, are only detected through visual or leak inspections; often only during the legally required general inspection (HU) or safety inspection (SP).This can lead to potentially critical situations in which the brake pressure cannot be reliably controlled by the axle modulator's brake electronics or an electric brake control unit. It will also be crucial for future autonomous vehicles to detect component defects in a timely manner and replace them.

[0004] The present invention is based on the object of enabling an evaluation of the current functionality of the electronically controlled valves in an electronic braking system of a commercial vehicle using the simplest possible means. This object is achieved according to the invention by an electronic braking system having the features of claim 1.

[0005] The problem is also solved by a method for monitoring the functionality of valves in an electronic braking system for commercial vehicles with the features of claim 5. Furthermore, this problem is solved by a commercial vehicle with the features of claim 9.

[0006] According to the invention, the valve actuations are counted, the counted number of actuations is related to a reference value, and thus a monitoring value is determined. The monitoring value determined in this way is compared with predetermined reference values, and the current functionality of the valves is assessed based on the comparison of the monitoring value with the reference values. Based on the number of actuations and their standardization via a reference value, a monitoring device according to the invention obtains a monitoring value with content information about the change in the functionality of the valves. This allows an evaluation of the current functionality by comparing it with reference values ​​for fault-free valve functionality.

[0007] In one embodiment of the invention, in addition to the actuation counter for counting valve actuations, the monitoring device is assigned a braking counter for counting braking operations. The number of braking operations is the reference value to which the number of valve actuations is related. The monitored value is the ratio of the number of valve actuations per braking operation. According to the method according to the invention for monitoring the current functionality of the valves, braking operations are counted as a reference value, and a ratio of the number of valve actuations per braking operation is determined as the monitored value. In this way, a standardized monitoring value with high informative value regarding the functionality of the valves during a braking operation is obtained, which can be easily compared with established reference values ​​and reference values ​​determined empirically over the vehicle's service life.

[0008] Advantageously, a deviation of the monitored variable from the reference value is evaluated based on a predefined limit value, and if deviations exceed the limit value, defect information is output. If, when comparing the monitored variable—in particular the ratio of valve actuations per braking operation—with the reference value, deviations greater than the predefined limit are detected, corresponding warning information is output. This can, for example, be the activation of the warning lamp or transmission to an infotainment system installed on the vehicle (e.g., SmartBoard or OptiLink) and / or a telematics system for remote monitoring of the vehicle. In a further embodiment, the control unit starts a test routine upon receipt of warning information and evaluates the pneumatic response in the electronic braking system.If irregularities are confirmed, a warning message may be displayed, for example via the warning light, infotainment system or similar.

[0009] If the monitoring device is assigned to the valves of an axle modulator, the number of valve actuations can be taken from an actuation counter of the axle modulator. Actuation counters are usually integrated into an axle modulator, so that a monitoring device according to the invention only requires a braking counter to count the braking operations, and a separate actuation counter is dispensed with by accessing the actuation number stored in the axle modulator's memory.

[0010] In a further advantageous embodiment of the invention, the axle modulator and the braking counter are connected to a telematics unit of the commercial vehicle, which is designed to communicate a memory image of the axle modulator and the number of braking operations for the purpose of external monitoring of the valve functionality. A telematics unit is a device for communicating driving data to a telematics portal for external evaluation. For the purposes of the invention, the memory image and the number of braking operations are communicated via the telematics, with the monitoring unit for the valves in the electronic braking system recording information during the journey and sending it for evaluation. Therefore, the memory of the EBS control unit of the commercial vehicle, which is often limited, is not required, and the calculations for the monitoring according to the invention can be performed on an external server.This has the additional advantage that different time periods can be compared. Ultimately, the valve actuation and brake actuation counters are available for each day, making it easier to identify deviations. Furthermore, seasonal factors that may have an influence can be compensated for, such as an increased number of anti-lock braking system interventions in winter when friction coefficients are low, which could distort the calculation.

[0011] Embodiments of the invention are explained in more detail below with reference to the drawings. They show: Fig. 1 a pneumatic and electrical diagram of a first embodiment of an electronic braking system, Fig. 2 a pneumatic and electrical diagram of a second embodiment of an electronic braking system, Fig. 3 a flow chart of an embodiment of a method for monitoring the functionality of valves of an axle modulator of the brake system according to Fig. 1 or Fig. 2.

[0012] Fig. Figure 1 shows the pneumatic and electrical diagram of an electronic braking system 1 of a commercial vehicle 2, namely a truck or bus. Electrical lines are shown with solid lines and pneumatic lines with dotted lines. To brake the wheels 3, each wheel 3 is assigned a wheel brake 4, which can be actuated pneumatically via brake cylinders 5. The brakes 4 exert a braking force on the rotating wheel 3 according to the pneumatic brake pressure present in the brake cylinder 5. In the exemplary embodiment shown, the wheel brakes 4 of the front axle are assigned to a common first brake circuit 6, while the wheel brakes 4 of the rear axle can be actuated via a second brake circuit 7. A first pressure fluid reservoir 8 is assigned to the first brake circuit 6 and connected to the brake cylinders 5 of the brakes 4 of the front axle. The second brake circuit 7 of the rear axle is supplied with pressure fluid via a second pressure fluid reservoir 9.

[0013] To adjust the brake pressure at the wheel brakes 4, the electronic braking system 1 has a brake control unit 11. Upon detecting a braking request 16, the brake control unit 11 sets the appropriate brake pressure at the wheel brakes 4 by controlling valves with corresponding control signals. The braking request 16 can be communicated by the driver of the commercial vehicle 2 via the brake signal transmitter 17 of the brake pedal 18, or it can be the braking request of a virtual driver, for example, during autonomous driving, or an external braking request from a driver assistance or stability system of the commercial vehicle 2.

[0014] In the first brake circuit 6 of the front axle, an electrically controllable pressure control valve 10 is connected upstream of each brake cylinder 5 of a wheel brake 4. To receive control signals, the pressure control valves 10 are connected to the brake control unit 11. The pressure control valves 10 are each a combination of at least two solenoid valves, namely an inlet valve and an outlet valve. The inlet valve essentially serves to increase or maintain the pressure in the respective brake cylinder 5, while the outlet valve is opened to reduce the brake pressure and vent the wheel brake 4, specifically the connected brake cylinder 5. During a braking operation, the inlet and outlet valves are regularly actuated several times to regulate the requested brake pressure.

[0015] In the second brake circuit 7, an axle modulator 12 regulates the brake pressure on both sides of the rear axle. The axle modulator 12 has two pneumatically independent pressure control channels 13, 14 with valves 15 for adjusting the brake pressure in the respective pressure control channel 13, 14 and the respective wheel brake 4. The axle modulator 12 implements braking requests 27 from the central brake control unit 11 via the pressure control channels 13, 14 and by controlling the respective valves 15 and regulates a corresponding brake pressure. For this purpose, it has a pressure sensor and control electronics 19, which are also designed to implement anti-lock interventions when individual wheels are inclined to lock and to regulate the brake pressure along the slip limit. To regulate the brake pressure, the axle modulator 12 controls its valves 15, i.e., the inlet valves and the outlet valves of the respective pressure control channel 13, 14.

[0016] For the purpose of detecting mechanical defects, in particular wear, the electronic braking system 1 has a monitoring device 20 for evaluating the current functionality of the valves 15. To evaluate and monitor the current functionality, the actuations 21 of the valves 15 are counted and a monitoring variable 28 is determined based on the number of actuations 22. The monitoring variable 28 is calculated taking into account reference values ​​24 ( Fig. 3) are evaluated, which are specified for a desired functionality. The monitoring device 20 accesses an actuation counter 23 to record the actuation number 22. In the illustrated embodiment, the actuation number 22 is provided by the brake electronics 19 of the axle modulator 12, into which an actuation counter 23 is integrated. In a further embodiment, the monitoring device 20 has a separate actuation counter 23.

[0017] To enable a qualitative assessment of the valves' functionality, the number of actuations 22 of the valves 15 is related to a reference value representing the effect of the valve actuations, thus determining the monitoring value. Braking requests 27, and thus ultimately the requested braking operations, are counted as the reference value. Therefore, in addition to recording the actuations 21 of the valves 15 by an actuation counter 23, the monitoring device 20 includes a braking counter 25 for counting the braking requests 27.

[0018] The procedure for monitoring the functionality of the valves is described in more detail below using the flow chart according to Fig. 3, which starts with the continuous recording of the number of valve actuations 22 of the valve actuations 21 by an actuation counter 23 and the recording of the number of braking actions 26 by a braking counter 25, i.e., the counting of the braking requests 27 to the axle modulator. The number of valve actuations 22 is related to the number of braking actions 26 to determine a meaningful monitoring variable 28, so that a statement is available about the number of valve actuations that occurred to implement the recorded number of braking requests. In the exemplary embodiment, the ratio 29 of the valve actuations 21 per braking request 27 is determined as the monitoring variable 28.

[0019] A comparison 30 of the monitoring variable 28, i.e. the ratio 29 of the actuations 21 of the valves per brake request 27, with predetermined reference values ​​24 for defect-free functionality enables a subsequent evaluation 32 of the current functionality 33. A deviation 31 of the monitoring variable 28 from the reference value 24 indicates a deviation of the current functionality 33 from fault-free functionality.

[0020] When evaluating 32 the deviation 31 of monitoring variable 28 from reference value 24, a limit value 34 is taken into account. If the deviation 31 exceeds the limit value 34, defect information 39 is output. The defect information 39 can be used to inform the driver, for example, by activating a warning light. In the illustrated embodiment, the defect information 39 is communicated to the central brake control unit 11, which initiates a more detailed check of the valves' functionality.

[0021] Fig. 2 shows a further embodiment of an electronic braking system 1', in which, in contrast to the braking system 1 according to Fig.1, a monitoring device 20' is provided, which enables external monitoring of the functionality of the valves via a telematics portal 35. The axle modulator 12 and the braking counter 25 are connected to a telematics unit 36 ​​of the commercial vehicle 2', which is designed to communicate a memory image 37 of the axle modulator 12 and the number of braking operations 26 for the purpose of external monitoring and evaluation 32' of the functionality of the valves. The number of actuations 22 of the actuations 21 of the valves of the axle modulator 12 is also transmitted with the memory image 37. List of reference symbols (part of the description) 1.1' Electronic braking system 2.2' commercial vehicle 3 wheel 4 wheel brake 5 brake cylinders 6 First brake circuit 7 Second brake circuit 8 First pressure medium supply 9 Second pressure medium supply 10 Pressure control valve 11 Brake control unit 12 axis modulator 13 Pressure control channel 14. Pressure control channel 15 Valve 16 Brake request 17 brake signal generator 18 Brake pedal 19 Control electronics 20.20' monitoring device 21 valve operations 22 number of operations 23 operation counters 24 Reference value 25 braking counters 26 braking times 27 Brake request 28 Monitoring size 29 ratio 30 Comparison 31 Deviation 32, 32' Rating 33 Current functionality 34 Limit 35 Telematics portal 36 Telematics unit 37 Memory dump 38 Reference value 39 Defect information

Claims

[1] Electronic braking system (1, 1') for commercial vehicles (2, 2') with wheel brakes (4) which can be actuated pneumatically via valves (15), wherein the valves (15) are electrically controlled in the event of a braking request (27), with a monitoring device (20, 20') for evaluating (32, 32') a current functionality (33) of the valves (15), which monitoring device has an actuation counter (23) for counting actuations (21) of the valves (15) and is designed to relate a number of actuations (22) counted by the actuation counter (23) to a reference value (38) and thus to determine a monitoring value (28), to compare (30) the monitoring value (28) with at least one predetermined reference value (24) and to determine a current functionality (33) of the Valves (15) to be evaluated. [2] Electronic braking system (1, 1') according to claim 1, characterized bythat the monitoring device (20, 20') is assigned, in addition to the actuation counter (23) for counting the actuations (21) of the valves (15), a braking counter (25) for counting the braking requests (27), wherein a braking number (26) of the braking requests (27) is the reference variable (38) and the monitoring variable (28) is the ratio (29) of the actuation number (22) of the actuations (21) of the valves (15) per braking request (27). [3] Electronic braking system (1, 1') according to one of the preceding claims, characterized by that the monitoring device (20, 20') is assigned to the valves (15) of an axle modulator (12) and takes the number of actuations (22) of the actuations (21) of the valves (15) from an actuation counter (23) of the axle modulator (12). [4] Electronic braking system (1') according to claim 3, characterized bythat the axle modulator (12) and the braking counter (25) are connected to a telematics unit (36) of the commercial vehicle (2'), which is designed to communicate a memory image (37) of the axle modulator (12) and the number of braking operations (26) for the purpose of external monitoring of the current functionality (33) of the valves (15). [5] Method for monitoring the current functionality (33) of valves (15) in an electronic braking system (1, 1') for commercial vehicles (2, 2') with wheel brakes (4) actuated pneumatically via the valves (15), wherein actuations (21) of the valves (15) are counted, a counted number of actuations (22) of the actuations (21) of the valves (15) is related to a reference variable (38) and a monitoring variable (28) is thus determined, wherein the monitoring variable (28) is compared (30) with at least one predetermined reference value (24) and a current functionality (33) of the valves (15) is evaluated (32, 32') on the basis of the comparison (30) of the monitoring variable (28) with the reference value (24). [6] Method according to claim 5, characterized bythat braking requests (27) are counted and a braking number (26) of the braking requests (27) is determined as a reference variable (38) and thus a ratio (29) of the number of actuations (22) of the actuations (21) of the valves (15) per braking request (27) is determined as a monitoring variable (28). [7] Method according to claim 5 or 6, characterized by that a deviation (31) of the monitoring variable (28) from the reference value (24) is evaluated with a limit value (34) and in the case of deviations (31) above the limit value (34) defect information (39) is output. [8] Method according to one of claims 5 to 7, characterized by that the current functionality (33) of the valves (15) of an axis modulator (12) is monitored and the number of actuations (22) of the actuations (21) of the valves (15) is taken from an actuation counter (23) of the axis modulator (12). [9] Commercial vehicle (2, 2') with an electronic braking system (1, 1') according to one of claims 1 to 4, in particular for carrying out a method according to one of claims 4 to 8.

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