SENSOR TEST SYSTEM

Abstract

A sensor test system for a pressure sensor in an electronic parking brake (EPB) of a vehicle. The pressure sensor is configured to measure a pressure in a pressure chamber or in a pressure line of the EPB. The sensor test system includes a pressure setting module configured to set the pressure; and by a detection module configured to detect, based on pressure set by the pressure setting module and based on a measured pressure from the pressure sensor, a potential malfunction of the pressure sensor, and to issue a warning signal if the potential malfunction is detected.

Claims

1-13. (canceled)

14. A sensor test system for a pressure sensor in an electronic parking brake (EPB) of a vehicle, the pressure sensor being configured to measure a pressure in a pressure chamber or in a pressure line of the EPB, comprising: a pressure setting module to set the pressure; and a detection module to detect, based on pressure set by the pressure setting module and based on a measured pressure from the pressure sensor, a potential malfunction of the pressure sensor, and to issue a warning signal if the potential malfunction is detected.

15. The sensor test system of claim 14, wherein the pressure setting module is configured to set the pressure when the vehicle is at standstill.

16. The sensor test system of claim 14, wherein the vehicle includes a further brake, and wherein the pressure setting module is configured to apply the further brake, and/or to receive a signal indicating an actuation of the further brake, and/or check that the further brake is applied, while setting the pressure.

17. The sensor test system of claim 14, wherein the pressure setting module is configured to set the pressure to at least one of the following: a value which is proportional to a value for releasing a brake, and/or more than one value in a predetermined sequence, and/or more than one value in a continuous manner with a specific gradient, and/or a sequence of values in a periodic manner.

18. The sensor test system of claim 14, wherein the pressure setting module is configured to set the pressure depending on a parking and/or driving status of the vehicle.

19. The sensor test system of claim 14, wherein the EPB includes a plurality of valves for setting the pressure, and wherein the pressure setting module is configured to set the pressure by one or more particular valves of the plurality of valves.

20. The sensor test system of claim 14, wherein the detection module is configured to trigger the pressure setting module to set the pressure.

21. The sensor test system of claim 14, wherein the detection module is configured to detect a potential malfunction of the pressure sensor based on at least one of the following: a nominal output of the pressure sensor, and/or a recorded previous output of the pressure sensor, and/or a supply brake pressure, and/or a vehicle weight, and/or a driving or parking status of the vehicle, and/or a force exerted by a brake of the vehicle, and/or a motion and/or movement of a brake, and/or a temperature, and/or an air humidity.

22. The sensor test system of claim 14, wherein the detection module is configured to issue the warning signal to at least one of: a driver, and/or surroundings of the vehicle, and/or a further component of the vehicle.

23. A brake unit, comprising: a pressure chamber or a pressure line; and a pressure sensor to measure, by a sensor test system for the pressure sensor, a pressure in the pressure chamber or the pressure line; wherein the sensor test system is for the pressure sensor in an electronic parking brake (EPB) of a vehicle, wherein the pressure sensor is configured to measure a pressure in the pressure chamber or in the pressure line of the EPB, and wherein the sensor test system includes: a pressure setting module to set the pressure; and a detection module to detect, based on pressure set by the pressure setting module and based on a measured pressure from the pressure sensor, a potential malfunction of the pressure sensor, and to issue a warning signal if the potential malfunction is detected.

24. A vehicle, comprising: a brake unit, including: a pressure chamber or a pressure line; and a pressure sensor to measure, by a sensor test system for the pressure sensor, a pressure in the pressure chamber or the pressure line; wherein the sensor test system is for the pressure sensor in an electronic parking brake (EPB) of a vehicle, wherein the pressure sensor is configured to measure a pressure in the pressure chamber or in the pressure line of the EPB, and wherein the sensor test system includes: a pressure setting module to set the pressure; and a detection module to detect, based on pressure set by the pressure setting module and based on a measured pressure from the pressure sensor, a potential malfunction of the pressure sensor, and to issue a warning signal if the potential malfunction is detected.

25. A method for testing a pressure sensor in a brake unit of a vehicle, the pressure sensor being configured to measure a pressure in a pressure chamber or in a pressure line, the method comprising: setting the pressure to provide a set pressure; measuring, by the pressure sensor, the pressure to obtain a measured pressure; detecting, based on the set pressure and the measured pressure, a potential malfunction of the pressure sensor; and issuing a warning signal if the potential malfunction is detected.

26. A non-transitory computer readable medium having a computer program, which is executable by a processor, comprising: a program code arrangement having program code for testing a pressure sensor in a brake unit of a vehicle, the pressure sensor being configured to measure a pressure in a pressure chamber or in a pressure line, by performing the following: setting the pressure to provide a set pressure; measuring, by the pressure sensor, the pressure to obtain a measured pressure; detecting, based on the set pressure and the measured pressure, a potential malfunction of the pressure sensor; and issuing a warning signal when the potential malfunction is detected.

27. The computer readable medium of claim 26, wherein there is a sensor test system for the pressure sensor in an electronic parking brake (EPB) of a vehicle, wherein the pressure sensor is configured to measure the pressure in the pressure chamber or in the pressure line of the EPB, and wherein the sensor test system includes: a pressure setting module to set the pressure; and a detection module to detect, based on the pressure set by the pressure setting module and based on the measured pressure from the pressure sensor, the potential malfunction of the pressure sensor, and to issue the warning signal when the potential malfunction is detected.

28. The method of claim 25, wherein there is a sensor test system for the pressure sensor in an electronic parking brake (EPB) of the vehicle, wherein the pressure sensor is configured to measure the pressure in the pressure chamber or in the pressure line of the EPB, and wherein the sensor test system includes: a pressure setting module to set the pressure; and a detection module to detect, based on the pressure set by the pressure setting module and based on the measured pressure from the pressure sensor, the potential malfunction of the pressure sensor, and to issue the warning signal when the potential malfunction is detected.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0045] FIG. 1 illustrates an embodiment of the sensor test system in an electronic parking brake.

[0046] FIG. 2 illustrates an operation of the sensor test system.

[0047] FIG. 3 displays steps of a method for testing a pressure sensor.

DETAILED DESCRIPTION

[0048] FIG. 1 illustrates an embodiment of the sensor test system 100 together with some parts of an exemplary electronic parking brake, EPB, 200 of a vehicle. The EPB 200 exhibits a pressure supply connection 210, equipped with a check valve 213, to receive pressurized air for a pressure chamber 225 of a spring brake actuator 220. In the present example, the pressurized air is provided to the pressure chamber 225 by a supply line 215 via a parking brake relay valve, PBRV, 230. The PBRV 230 is configured to set a plurality of different pressure values in the pressure chamber 225. In order to control the pressure in the pressure chamber 225, two control valves 241, 242 operate the PBRV 230 by regulating pressure through a control line 218. The diagram displays two pressure sensors: a first pressure sensor 251 is configured to measure a pressure in the control line 218, and a second pressure sensor 252 is configured to measure a pressure in the pressure chamber 225. The control valves 241, 242 and the pressure sensors 251, 252 are operated by an electronic control unit, ECU, 260 of the EPB 200. In this embodiment, the sensor test system is a part of the ECU 260. In the ECU 260, only the sensor test system 100 and some (dashed) electric lines connecting to it are displayed in this diagram, but it is understood that further modules of the ECU 260 may exist to control the EPB 200. The sensor test system 100 comprises a pressure setting module 110, configured, in this embodiment, to set both a pressure in the control line 218 as well as a pressure in the pressure chamber 225, by the control valves 241, 242. The sensor test system 100 furthermore comprises a detection module 120 which is configured to detect, based on pressure set by the pressure setting module 110, and based on a measured pressure from the pressure sensors 251, 252, a potential malfunction of the pressure sensors 251, 252. The detection module 120 is further configured to issue a warning signal if the potential malfunction is detected. The pressure setting module 110 or the detection module 120 may exhibit data communication connections to other components of the vehicle, in particular to other brake units.

[0049] In this embodiment, the sensor test system 100 is configured to deliberately open the first control valve 241 and the second control valve 242 individually, in particular in order to increase and then decrease the pressure in the pressure chamber 225. If the measured pressure in the pressure chamber 225 is in correlation with the expected change, the second pressure sensor 252 is considered to be adequately operational. The order of the opening of the control valves 241, 242, a timing, and the desired pressure change depend primarily on the actual output of the respective pressure sensor 251, 252. However, other factors, such as e.g. vehicle data or previous pressure sensor outputs during actuations, might also be taken into account.

[0050] Regarding a test schedule, a simple two-way change of the pressure may be applied. This may be followed by more sophisticated modulations (e.g. a pressure change with a certain gradient, or a periodic change of the pressure). By these methods, a status of the pressure sensor 252 can be determined more precisely.

[0051] The sensor test system 100 may be configured to perform similar tests also for the first pressure sensor 251, both together with the tests of the second pressure sensor, or individually.

[0052] During a variation of the pressure 252 in the pressure chamber 225, the vehicle may have to be prevented from moving. This may be achieved either by only applying a limited variation of the pressure in the pressure chamber 225 (leading only to a small change in a brake force), or by constantly applying another brake of the vehicle. The other brake may e.g. be a service brake provided by the same brake actuator, or it may be located in a different brake unit. The application of the other brake may be performed either by the driver, or by the sensor test system 100 in an automatic way.

[0053] FIG. 2 illustrates the operation of the sensor test system 100 by a curve of pressure versus time in a pressure chamber 225 of a brake 220. The diagram displays a curve of pressure sensor data 10, and a sequence of pressure demand values 20 set by the pressure setting module 110.

[0054] The vehicle may initially be at standstill, i.e. before a time T0, the parking brake 220 may be applied, such that the pressure in the pressure chamber 225 is low, with the pressure sensor 252 reporting a pressure of about 2 bar. At time T0, the pressure setting module 110 sets a pressure of about 4.5 bar, which is reflectedwith a time lagin the pressure sensor data 10. At time T1, the pressure setting module 110 sets a lower pressure of about 3 bar in the pressure chamber 225, which is again measured in due time by the pressure sensor 252. At time T2, the pressure setting module 110 increases the target pressure to 8.5 bar, which may release the brake 220. Again, the pressure sensor 252 indicates that the set pressure is attained in the pressure chamber 225 shortly afterwards.

[0055] This example may e.g. occur in a situation where the vehicle is about to drive off. At time TO, a signal for releasing the parking brake 220 may reach the EPB 200, prompting the sensor test system 100 to initiate the test of the pressure sensor 252. The first two pressure values set by the pressure setting module 110in this case, 4.5 bar and 3 barmay be well below a threshold pressure necessary to release the parking brake 220. Eventually, after the check in this relatively limited pressure range, the pressure in the pressure chamber 225 is set to 8.5 bar, which may be enough for releasing the brake 220.

[0056] The test may also be performed shortly after the vehicle has been parked, and e.g. after another system has declared that the vehicle has performed a successful parking. Also in this case, the pressure may be raised to a full release of the brake 220 (before the parking brake is eventually applied again). The full release has the advantage that the expected pressure is close to the supply pressure. Since the supply pressure is typically known, this provides an additional cross-check for the functionality of the pressure sensor 252. In this case, however, it is especially important to avoid the movement of the vehicle.

[0057] The test of the pressure sensor 252 may also be performed in parking situations other than those just described. It may also extend, with suitable adaptations, to a test of a service brake or a brake booster. Furthermore, even though the present description only relates to tests for a pressure sensor, the concept may be extended to other sensors as well.

[0058] FIG. 3 displays steps of a method for testing a pressure sensor 251, 252 in a brake unit 200 of a vehicle. The pressure sensor 251, 252 is configured to measure a pressure in a pressure chamber 225 or in a pressure line 218 of the brake unit 200. The method comprises a step of setting S110 the pressure in the pressure chamber 225 or pressure line 218. A further step comprises measuring S120, by the pressure sensor 251, 252, the pressure. The method further comprises detecting S130, based on the set pressure and based on the measured pressure, a potential malfunction of the pressure sensor 251, 252. A further step of the method comprises issuing S140 a warning signal if the potential malfunction is detected. Each step may occur only once, or repeatedly, and the order of the steps may vary.

[0059] This method may also be a computer-implemented method. A person of skill in the art will readily recognize that steps of the method may be performed by programmed computers. Embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine or computer readable and encode machine-executable or computer-executable programs of instructions, wherein the instructions perform some or all of the acts of the above-described method, when executed on the computer or processor.

[0060] The description and drawings merely illustrate the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its scope.

[0061] Furthermore, while each embodiment may stand on its own as a separate example, it is to be noted that in other embodiments the defined features can be combined differently, i.e. a particular feature described in one embodiment may also be realized in other embodiments. Such combinations are covered by the disclosure herein, unless it is stated that a specific combination is not intended.

THE LIST OF REFERENCE SIGNS IS AS FOLLOWS

[0062] 10 pressure sensor data [0063] 20 set pressure demand [0064] 100 sensor test system [0065] 110 pressure setting module [0066] 120 detection module [0067] 200 electronic parking brake [0068] 210 pressure supply connection [0069] 213 check valve [0070] 215 supply line [0071] 218 control line [0072] 220 brake actuator [0073] 225 pressure chamber [0074] 230 parking brake relay valve [0075] 241, 242 control valves [0076] 251 first pressure sensor [0077] 252 second pressure sensor [0078] 260 electronic control unit [0079] S110, S120, S130, S140 steps of a method