DE102016225356A1 - Method and apparatus for monitoring a pressure sensor and exhaust aftertreatment device for a vehicle - Google Patents

Abstract

The invention relates to a method for monitoring a pressure sensor (104) for monitoring a pressure provided by a pump (102). The method comprises a step of reading a pressure signal (112) via an interface to the pressure sensor (104), a filtering step the pressure signal (112) using a bandpass filter (119) having a frequency range adapted to an operating frequency of a pressure influencing device (102) to obtain a filtered pressure signal (124), a step of making a comparison between a characteristic of the filtered pressure signal ( 124) and a threshold value, and a step of providing (917) a monitor signal (116) indicative of a function of the pressure sensor (104) depending on a result of the comparison.

Description

State of the art

The invention is based on a device or a method according to the preamble of the independent claims. The subject of the present invention is also a computer program.

Pressure sensors play an important role in the context of an exhaust aftertreatment device for after-treatment of exhaust gas of an internal combustion engine of a vehicle.

The DE 10 2012 204 353 A1 describes a monitoring of gas sensors.

Disclosure of the invention

Against this background, a method and a device for monitoring a pressure sensor, a pump device and an exhaust gas aftertreatment device for a vehicle, and finally a corresponding computer program according to the main claims are presented with the approach presented here. The measures listed in the dependent claims advantageous refinements and improvements of the independent claim device are possible.

For example, the pump speed of a pump may be advantageously used to monitor a pressure sensor that detects a pressure provided by the pump. In this way, the pressure sensor can also be monitored during operation of the pump. This also allows a quantitative plausibility monitoring of pressure sensors. Alternatively or in addition to the pump speed, for example, a metering frequency of a metering device can also be used.

• Einlesen eines Drucksignals über eine Schnittstelle zu dem Drucksensor;
• Filtern des Drucksignals unter Verwendung eines Bandpassfilters mit einem an eine Betriebsfrequenz einer den Druck beeinflussenden Einrichtung angepassten Frequenzbereich, um ein gefiltertes Drucksignal zu erhalten;
• Durchführen eines Vergleichs zwischen einer Charakteristik des gefilterten Drucksignals und einem Schwellenwert; und
• Bereitstellen eines eine Funktion des Drucksensors anzeigenden Überwachungssignals abhängig von einem Ergebnis des Vergleichs.

A method of monitoring a pressure sensor to monitor a pressure provided by a pump includes the following steps:

• Reading a pressure signal via an interface to the pressure sensor;
• Filtering the pressure signal using a bandpass filter having a frequency range adjusted to an operating frequency of a pressure-influencing device to obtain a filtered pressure signal;
• Performing a comparison between a characteristic of the filtered pressure signal and a threshold value; and
• Providing a monitoring signal indicative of a function of the pressure sensor depending on a result of the comparison.

The pump may be a conveyor for conveying a fluid. For example, when the fluid is pumped into a pressure line using the pump, pressure is built up in the pressure line. The pressure can be detected using the pressure sensor. The pressure signal may represent the sensed pressure. For example, the pressure signal may be an electrical signal. The frequency range of the bandpass filter may define a frequency interval that includes frequencies that can pass the bandpass filter. Out of frequency range frequencies may be filtered out by the bandpass filter. The pressure-influencing device may be a device by which the pressure is increased, or a device by which the pressure is lowered. A device for increasing the pressure may, for example, be the pump which is designed to convey the fluid into the pressure line. A device for lowering the pressure may, for example, be a metering device which is designed to convey the fluid out of the pressure line. The operating frequency may be a current or a preset speed. The characteristic of the filtered pressure signal may relate to a waveform of the filtered pressure signal. The monitoring signal may be suitable for indicating as a function of a correct and / or erroneous operation of the pressure sensor.

According to one embodiment, the frequency range of the bandpass filter may be adapted to a minimum and a maximum operating frequency of the device. In this way it can be ensured that, for example, all frequencies of the sensor signal, which are caused by the rotation of the pump, or caused by a function of the metering device, the bandpass filter can happen.

Accordingly, the frequency range of the bandpass filter may be adjusted to a pump speed or pump frequency of the pump. Additionally or alternatively, the frequency range may be adjusted to a metering frequency of the metering device or be.

In the step of performing the comparison, an amplitude of the filtered pressure signal and the threshold value may be performed become. Such a comparison can be done very easily.

Additionally or alternatively, in the step of performing the comparison between a slope of the filtered pressure signal and the threshold value may be performed. As a result, the filtered pressure signal can be reliably evaluated even if the filtered pressure signal has a small amplitude.

The method may include a step of reading in a pump speed value representing the pump speed. Further, the method may include a step of adjusting the frequency range of the bandpass filter using the pump speed value. In this way, the bandpass filter can be matched to the pump used. Advantageously, the frequency range of the bandpass filter and a changing speed of the pump can be tracked.

The method may include a step of making a further comparison between the one or more characteristics of the filtered pressure signal and another threshold. Further, the method may include a step of providing a diagnostic signal indicative of a function of the pump depending on a result of the further comparison. In this way, in addition to the pressure sensor and a correct function of the pump can be monitored.

This method can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit.

The approach presented here also creates a device that is designed to perform the steps of a variant of a method presented here in appropriate facilities to drive or implement. Also by this embodiment of the invention in the form of a device, the object underlying the invention can be solved quickly and efficiently.

For this purpose, the device may comprise at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading sensor signals from the sensor or for outputting data or control signals to the sensor Actuator and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The arithmetic unit may be, for example, a signal processor, a microcontroller or the like, wherein the memory unit may be a flash memory, an EEPROM or a magnetic memory unit. The communication interface can be designed to read or output data wirelessly and / or by line, wherein a communication interface that can read or output line-bound data, for example, electrically or optically read this data from a corresponding data transmission line or output in a corresponding data transmission line.

In the present case, a device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The device may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based embodiment, the interfaces can be part of a so-called system ASIC, for example, which contains a wide variety of functions of the device. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules.

An apparatus for monitoring a pressure sensor for monitoring a pressure provided by a pump is arranged to perform steps of said method in respective units.

• eine Pumpe zum Pumpen eines Fluids in eine Druckleitung;
• einen Drucksensor zum Sensieren eines in der Druckleitung herrschenden Drucks; und
• eine genannte Vorrichtung zum Überwachen des Drucksensors.

The device can be used for example in connection with a pumping device. A corresponding pumping device for a vehicle has the following features:

• a pump for pumping a fluid into a pressure line;
• a pressure sensor for sensing a pressure prevailing in the pressure line; and
• a said device for monitoring the pressure sensor.

Advantageously, a corresponding pumping device for an exhaust aftertreatment device for post-treatment of exhaust gas of an internal combustion engine for a vehicle can be used. Such an exhaust aftertreatment device comprises a metering device for metering an exhaust aftertreatment agent from a pressure line into an exhaust pipe for guiding the exhaust gas and a said pumping device, wherein the pump of the pumping device is designed to pump the exhaust gas aftertreatment agent into the pressure line.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is used, especially when the program product or program is executed on a computer or a device.

• 1 ein Blockschaltbild einer Pumpvorrichtung für ein Fahrzeug gemäß einem Ausführungsbeispiel;
• 2 ein Blockschaltbild einer Abgasnachbehandlungsvorrichtung zum Nachbehandeln von Abgas eines Verbrennungsmotors für ein Fahrzeug gemäß einem Ausführungsbeispiel;
• 3 ein Verlauf eines gefilterten Drucksignals gemäß einem Ausführungsbeispiel;
• 4 ein Verlauf eines gefilterten Drucksignals gemäß einem Ausführungsbeispiel;
• 5 ein Verlauf eines gefilterten Drucksignals gemäß einem Ausführungsbeispiel;
• 6 Verläufe eines Drucksignals und eines gefilterten Drucksignals gemäß einem Ausführungsbeispiel;
• 7 Verläufe eines Drucksignals und eines gefilterten Drucksignals gemäß einem Ausführungsbeispiel;
• 8 eine Darstellung einer Sensorsignalauswertung gemäß einem Ausführungsbeispiel; und
• 9 ein Ablaufdiagramm eines Verfahrens gemäß einem Ausführungsbeispiel.

Embodiments of the approach presented here are shown in the drawings and explained in more detail in the following description. It shows:

• 1 a block diagram of a pumping device for a vehicle according to an embodiment;
• 2 a block diagram of an exhaust aftertreatment device for post-treating exhaust gas of an internal combustion engine for a vehicle according to an embodiment;
• 3 a profile of a filtered pressure signal according to an embodiment;
• 4 a profile of a filtered pressure signal according to an embodiment;
• 5 a profile of a filtered pressure signal according to an embodiment;
• 6 Curves of a pressure signal and a filtered pressure signal according to an embodiment;
• 7 Curves of a pressure signal and a filtered pressure signal according to an embodiment;
• 8th an illustration of a sensor signal evaluation according to an embodiment; and
• 9 a flowchart of a method according to an embodiment.

In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and similar acting, with a repeated description of these elements is omitted.

1 shows a block diagram of a pumping device 100 , which can be used for example in a vehicle, according to one embodiment. The pumping device 100 has a pump 102 , a pressure sensor 104 and a device 106 to monitor the pressure sensor 104 on. The pump 102 is configured to be a fluid during operation 108 , For example, a liquid or a gas in a pressure line 110 to pump and thereby pressurize. This is indicated by the pump 102 a on the operation of the pump 102 with a pump speed moving conveyor. The pressure sensor 104 is with the pressure line 110 coupled and trained to the in the pressure line 110 to detect prevailing pressure and a pressure signal representing the detected pressure 112 provide.

The device 106 is designed to handle the pressure signal 112 via an input interface 114 and using the pressure signal and a pump speed of the pump 102 value representing a function of the pressure sensor 104 to monitor. Furthermore, the device 106 designed to perform the function of the pressure sensor 104 representing monitoring signal 116 provide. For example, the monitoring signal 116 show that the pressure sensor 104 works correctly or alternatively has a fault.

For this purpose, the device 106 According to one embodiment, a read-in device in the form of the input interface 114 , a filter device 118, a passage device 120 and a provisioning device 122 , For example, in the form of an output interface for outputting the monitoring signal. The filter device 118 includes a bandpass filter 119 with an example here to the pump speed or pump frequency of the pump 102 adjusted frequency range or is considered such a bandpass filter 119 executed. The pump speed may be a predetermined or currently determined pump speed.

Accordingly, the frequency range can be preset to the predetermined pump speed or be adaptable to the current specific pump speed. Alternatively to the pump speed of the pump 102 can also be the operating frequency of another pressure-influencing device used, such as the operating frequency of in 2 shown metering device.

The filter device 118 is designed to handle the pressure signal 112 filtering using the bandpass filter and filtering filtered signal resulting from the filtering 124 provide. The execution facility 120 is configured to at least one characteristic of the filtered pressure signal 124 For example, to compare an amplitude or slope of the filtered pressure signal 124 to a threshold. From a result of the at least one comparison can be concluded that the function of the pressure sensor. According to this embodiment the execution unit 120 is configured to determine the result of the comparison or a signal determined using the result as the monitoring signal 116 issue. According to one embodiment, the passage device 120 configured to be an amplitude of the filtered pressure signal 124 with a first threshold and additionally or alternatively a slope of the filtered pressure signal 124 to compare with a second threshold. The threshold (s) may be predetermined or to a current pump speed or to adjust the frequency range of the bandpass filter 119 used pump speed be customizable.

According to different embodiments, it is one for filtering the pressure signal 112 used pump speed value 126 by a preset value, for example, in the device 106 stored or a currently determined or received value. According to the in 1 shown embodiment, the pump speed value 126 via an interface to the pump 102 read in and from an adjustment 128 the device 106 used to determine the frequency range of the bandpass filter 119 of the filter device 118 adjust. Alternatively, the pump speed value 126 also by a control device for controlling the pump 102 or determining means for determining the pump speed value 126 be received. Such a determination device can also be part of the device 106 be. According to one embodiment, the adjustment device 128 designed to adjust the cutoff frequencies of the bandpass filter frequency range so that an interval is represented by a pump frequency corresponding to the pump speed. A size of the interval can be preset, adjustable or to the current pump speed value 126 be customizable.

According to one embodiment, the device is 106 alternatively or additionally formed to a diagnostic signal 130 to provide that a function of the pump 102 , so for example, a correct function or a malfunction of the pump 102 displays. This is the implementation facility 120 designed to provide a further comparison between the also for determining the monitoring signal 116 used characteristic or another characteristic of the filtered pressure signal 124 and also for determining the monitoring signal 116 used or another threshold. From a result of the further comparison can be on the function of the pump 102 shut down. According to this embodiment, the passage device 120 configured to determine the result of the further comparison or a signal determined using the result as the diagnostic signal 130 issue.

2 shows a block diagram of an exhaust aftertreatment device for post-treatment of exhaust gas of an internal combustion engine 240 a vehicle 242 according to an embodiment. The exhaust aftertreatment device comprises a pumping device 100 , as shown for example by 1 is described.

The pumping device 100 includes a pump 102 in the form of a delivery module for delivering an exhaust aftertreatment agent in a pressure line 110 , a pressure sensor 106 for detecting the pressure in the pressure line 110 and a device 106 to monitor the pressure sensor 106 , For example only, the device is realized as part of a dosing control device.

The exhaust aftertreatment device comprises an exhaust pipe 244 for draining the from the engine 240 generated exhaust gas. In the exhaust pipe 244 is a catalyst 246 , For example, a so-called SCR catalyst arranged. At the exhaust pipe 244 are temperature sensors 248 and NOx sensors 250 are arranged. Furthermore, a metering module 252 provided, which is adapted to the exhaust aftertreatment agent from the pressure line 110 in the exhaust pipe 244 inject. The dosing module 252 is with engine cooling water 254 provided.

The pump 102 is adapted to the exhaust aftertreatment agent from a tank 256 to promote storage of the exhaust aftertreatment agent. This is the pump 102 via a return line 258 and a suction line 260 with the tank 256 coupled. There is another temperature sensor on the tank 248 and a level sensor 262 arranged. The pump 102 is further formed by cooling water through a cooling water pipe 264 to promote.

In the in 1 shown embodiment in which the device 106 Part of a dosing control unit, the dosing control unit has an input 266 for sensor signals and an output 268 for actuator control signals on. There are also connections for a motor CAN bus 270 and a diagnostic CAN bus 272 intended.

In connection with future legal requirements is a reduction of nitrogen oxide emissions from internal combustion engines 240 required to meet and comply with the specified emission limits. To meet and comply with these legal limits come downstream of the engine 240 Aftertreatment systems are used whose aim is to reduce the particle and nitrogen oxide concentration in the exhaust gas. The filters and catalysts used for this purpose 246 require that certain oxidizing / reducing agents be introduced into the exhaust line. Such agents are typically hydrocarbons (diesel fuel) and, secondly, urea-water solutions for selective catalytic reduction in the catalyst 246 , The hydrocarbons are used for exothermic chemical reaction in an oxidation catalyst with the aim of regenerating a diesel particulate filter (DPF). Further, the hydrocarbons are used for so-called enrichment of the exhaust gas with the aim of NOx storage catalyst regeneration.

For the introduction of the oxidation / reducing agent come mounted on the exhaust line injectors 252 for use. The required hydraulic pressure is often provided by separate pumps 102 provided.

For controlling the system pressure and for calculating the activation time of the injector 252 Typically, the pressure in the system is determined via a pressure sensor 104. The pressure sensor 104 is also used to monitor the system, for example, to detect critical conditions such as leaks or overpressure conditions and thus to be able to bring the system to a safe state. Because the pressure sensor 104 a central function in the system, it is necessary to possible error conditions of the pressure sensor 104 sure to recognize. The usual diagnostics allow monitoring of simple electrical faults such as open-load, short-circuit ground and short-circuit battery or sensor supply as well as the monitoring of the physical possible value range of the pressure sensor 104 , In the event that the pressure sensor 104 In the event of a fault, a signal within the electrical and physical possible range of values is supplied, in addition, a plausibility check is required. In the simplest case, in the case of a pressureless system, this is a comparison of the measured pressure information with the ambient pressure sensor signal. Since this works only in a pressureless system, ie at the beginning or end of a driving cycle with stationary engine, this type of monitoring is severely limited and it can not be reliably detected during normal system operation errors within the electrical and physical value range, ie In the event of an error, too high a pressure can be generated in the system due to the wrong pressure information which is not recognized. This can lead to the system being damaged or destroyed.

The approach described makes it possible to diagnose the plausibility monitoring of the pressure sensor 104 in the system, by not only being able to monitor in a non-pressurized system, but also to allow monitoring during operation, without requiring the use of an additional pressure sensor as reference signal for monitoring.

This becomes a plausibility check of the pressure sensor 104 possible without the pressure sensor signal is compared with a second pressure sensor signal, for example, the ambient pressure, whereby the plausibility check is not only possible in a pressureless system. To expand the diagnostic range, the pressure pulsations are controlled by the pump 102 be generated, filtered and monitored. Thus, with the superimposed frequency, by the excitation of the pump 102 a plausibility monitoring of the pressure sensor 104 be realized during operation of the system, without a second pressure sensor is to be used as a reference signal in the system. In addition to the comparison of the pressure signal against ambient pressure in a pressureless system can plausibility error of the pressure sensor 104 detected during operation and appropriate system responses are triggered to bring the system in a safe state.

For this purpose, the pressure signal provided as an analog sensor signal is not evaluated directly, but instead a system-specific frequency range is applied to a speed range of the pump 102 adapted, filtered pressure signal is evaluated and monitored.

As already in 1 executed, instead of the pump speed, the control of one of the metering device 252 metering valve used to define the frequency range of the bandpass filter. The metering frequency of the metering device 252 is also usable as a characteristic feature and can be selectively analyzed via the bandpass filter. Here then a plausibility of the injection is possible, ie it can be detected whether the valve of the metering device 252 has opened and whether an injection has occurred. This makes it possible to detect whether the holes on the valve tip are free or blocked, eg by crystals or deposits.

Thus, the bandpass filter can additionally or alternatively be adapted to the metering frequency. The evaluation of the pressure signal is based on the fact that a signal disturbance known in the system is detected. This could be the speed of the pump 102 or the control of the metering valve 252 be.

3 shows a course of a filtered pressure signal 124 according to an embodiment. On the abscissa is the time and on the Ordinate a signal size, here the signal voltage plotted. The filtered pressure signal 124 is in an electrical and physical workspace 370 of the pressure sensor. To the workspace 370 limit error margins 372 and error detection areas 374 at. To delimit the error margins 372 from the error detection areas 374 becomes a lower diagnostic threshold 376 and an upper diagnostic threshold 378 used.

At the in 3 shown course of the filtered pressure signal 124 the pressure sensor is recognized as "ok". In this case, the monitoring signal can indicate a faultless function.

4 shows a course of a filtered pressure signal 124 according to a further embodiment. Unlike the in 3 In the embodiment shown, the filtered pressure signal increases 124 jump up to the upper fault detection area 374 on, so exceeds the upper diagnostic threshold 378 , By comparing the amplitude of the filtered pressure signal 124 with one through the upper diagnostic threshold 378 threshold formed, the pressure sensor is detected as defective. In this case, the monitoring signal may indicate a malfunctioning function.

5 shows a course of a filtered pressure signal 124 according to a further embodiment. Unlike the in 4 the embodiment shown drops the filtered pressure signal 124 abruptly, but remains within the workspace 370 , By comparing the amplitude of the filtered pressure signal 124 with the through the diagnostic thresholds 376 . 378 Therefore, the pressure sensor is not recognized as defective. In this case, the pressure sensor is defective, but is recognized as "ok".

In this case, the malfunction can still be detected, in which the slope of the filtered pressure signal 124 is evaluated. By comparing the slope with another threshold, the abrupt change in the amplitude of the signal can be detected.

6 shows curves of a pressure signal 112 and a filtered pressure signal 124 according to an embodiment. At the pressure signal 112 it is a raw signal of the pressure sensor, which is substantially equal to a PTl-filtered signal of the sensor. At the filtered pressure signal 124 this is the signal according to 1 described bandpass filter. Due to the course of the sensor signal 124 after the bandpass filter, the sensor is recognized as "ok".

7 shows curves of a pressure signal 112 and a filtered pressure signal 124 according to another embodiment. Shown are sensor signals 112, 124 in the event of an error after bandpass filter, which cause the sensor is detected as defective. A sensor error event 780 for doing so to a maximum in the filtered pressure signal 124 , At the pressure signal 112 In turn, it is a raw signal of the pressure sensor, which is substantially equal to a PTI-filtered signal of the sensor.

8th shows a representation of a sensor signal evaluation according to an embodiment. In this case, a method for monitoring a pressure sensor according to an embodiment is implemented.

Shown is a sensor 104 , which is the basis of 1 can act described pressure sensor. From the sensor 104 An analogue pressure signal is provided which is converted to a digital pressure signal using an A / D converter 801 112 is converted. As a result of the sensor signal evaluation, according to this embodiment, a monitor signal 116 provided that can assume the logical states true and false, the correct and disturbed function of the sensor 104 Show.

The sensor signal evaluation furthermore comprises a first PT1 filter 803 and a second PT1 filter 805.

In this case, the analog sensor signal is not evaluated directly, but it is filtered to a system-specific frequency range and monitored. The monitoring is based on the fact that the analog pressure sensor signal has a superimposed frequency, which is caused by the pump of the conveyor module. This frequency depends on the current pump speed and can be used to monitor the measuring function of the pressure sensor 104 be used. The measured raw signal of the pressure sensor is filtered by means of a bandpass filter. The frequency range of the bandpass filter is given by the minimum and maximum pump speed. The filtered signal can be monitored. If the filtered signal is below an adjustable diagnostic threshold 807 , there is a sensor error.

Since smaller amplitudes may be present in the lower signal range, an incorrect error detection may possibly occur. Therefore, another diagnostic option is the monitoring of the signal change, ie the slope of the signal. For this purpose, the filtered signal is derived in the first order and filtered again by means of a PT1 filter. If the filtered signal is almost constant below an adjustable diagnostic threshold 807 there is a sensor error.

To be able to further narrow the frequency range of the bandpass filter, the current pump speed can be used. There are two possible approaches here. In the first case, an expected pump speed is calculated from the current duty cycle control of the pump. In the second variant, the measured pump speed is used directly. With the determined or measured pump speed, the superimposed frequency can thus be determined more accurately and the frequency range of the bandpass filter to be filtered can be adapted dynamically to the pump speed. Thus, any superimposed signal influences can be filtered and eliminated by further external sources of interference, which leads to an increase in the robustness of the diagnosis.

Another possible diagnosis is the plausibility monitoring of the pump speed. In this case, the bandpass filter is set to the calculated speed based on the current duty cycle drive of the pump and the filtered signal is monitored. If the current superimposed frequency is outside the bandpass filter, there is an error in the speed of the pump.

9 FIG. 12 shows a flowchart of a method for monitoring a pressure sensor according to an exemplary embodiment. The method may be, for example, using the basis of 1 be implemented device described.

The method comprises a step 911 in which a pressure signal is read, one step 913 in which the pressure signal is filtered using a bandpass filter set to an actual or expected pump speed, one step 915 in which a comparison between a characteristic of one from the step 913 resulted filtered filtered pressure signal and a threshold and a step 917 in which a monitoring signal is provided which indicates a function of the pressure sensor depending on a result of the comparison.

According to one embodiment, in step 913 a bandpass filter is used whose frequency range is adapted to a minimum and a maximum pump speed of the pump.

If the process is performed using a current pump speed, then in an optional step 919 reading in a pump speed value representing the current pump speed, and in step 921 adjusting the frequency range of the bandpass filter using the pump speed value.

According to an embodiment in which a function of the pump is monitored, the method further comprises a step 923 in which at least one characteristic of the filtered pressure signal is compared with at least one threshold value. In one step 925 Then a diagnostic signal is provided which indicates a function of the pump.

Through the steps 911 . 913 . 915 . 917 of the method, for example, based on 8th described sensor signal evaluation can be implemented.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012204353 A1 [0003]

Claims (13)

A method of monitoring a pressure sensor (104) to monitor a pressure provided by a pump (102), the method comprising the steps of: Reading (911) a pressure signal (112) via an interface to the pressure sensor (104); Filtering (913) the pressure signal (112) using a bandpass filter (119) having a frequency range adjusted to an operating frequency of a pressure influencing device (102; 252) to obtain a filtered pressure signal (124); Performing (915) a comparison between a characteristic of the filtered pressure signal (124) and a threshold (376, 378; 807); and Providing (917) a monitor signal (116) indicative of a function of the pressure sensor (104) depending on a result of the comparison. Method according to Claim 1 in which the frequency range of the bandpass filter (119) is adapted to a minimum and a maximum operating frequency of the device (102; 252). A bandpass filter (119) according to any one of the preceding claims, wherein the frequency range is matched to a pump speed of the pump (102). Bandpass filter (119) according to one of the preceding claims, in which the frequency range is adapted to a metering frequency of a metering device (252) which is designed to deliver a fluid from the pressure line (11) conveyed into a pressure line (110) using the pump (102). 110). A method according to any one of the preceding claims, wherein in the step (915) of performing the comparison between an amplitude of the filtered pressure signal (124) and the threshold value (376, 378; 807). A method according to any one of the preceding claims, wherein in the step (915) of performing the comparison between a slope of the filtered pressure signal (124) and the threshold (376, 378; 807) is performed. A method according to any one of the preceding claims including a step (919) of reading in an operating frequency value (126) representing the operating frequency and a step (921) of adjusting the frequency range of the bandpass filter (119) using the operating frequency value (126). Method according to one of the preceding claims, comprising a step (923) of carrying out a further comparison between the or a further characteristic of the filtered pressure signal (124) and a further threshold value, and a step (925) of providing a function of the pump ( 102) indicating diagnostic signal (130) depending on a result of the further comparison. Apparatus (106) for monitoring a pressure sensor (104) for monitoring a pressure provided by a pump (102), the apparatus (106) being arranged to perform steps of the method according to any one of the preceding claims in respective units. A pump device (100) for a vehicle (242), the pump device (100) comprising: a pump (102) for pumping a fluid into a pressure line (110); a pressure sensor (104) for sensing a pressure prevailing in the pressure line (110); and a device (106) according to Claim 9 for monitoring the pressure sensor (104). An exhaust after-treatment device for after-treatment of exhaust gas of an internal combustion engine (240) for a vehicle (242), the exhaust after-treatment device comprising: a metering device (252) for metering an exhaust aftertreatment agent from a pressure line (110) into an exhaust line (244) for carrying the exhaust gas ; and a pumping device (100) according to Claim 10 wherein the pump (102) of the pumping device (100) is configured to pump the exhaust aftertreatment agent into the pressure line (110). Computer program adapted to carry out the method according to one of the preceding claims. Machine-readable storage medium on which the computer program is based Claim 12 is stored.

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