Method, test device and motor vehicle for checking functionality

Abstract

The technology disclosed herein relates, according to the invention, to a method for checking the functionality of a first metering unit (20) for introducing a working medium into pipelines (40, 50) of a motor vehicle (70), wherein the metering system (10) comprises the first metering unit (20) and a second metering unit (30) for introducing the working medium into the pipelines (40, 50), and wherein the method comprises the following steps: sending a control signal for outputting a second quantity to the second metering unit (30); comparing the quantity output by the second metering unit (30) with the second quantity for checking the functionality of the second metering unit (30); sending a control signal for introducing a third quantity to the second metering unit (30); detecting a pressure drop in the metering system (10) by introducing the third quantity; sending a control signal for introducing a first quantity to the first metering unit (20); detecting a pressure drop in the metering system (10) caused by implementing the control signal for introducing the first quantity by the first metering unit (20); and determining that the first metering unit (20) is not operating in compliance when the difference between the pressure drop detected due to implementing the control signal for introducing the first quantity and the pressure drop detected due to implementing the control signal for introducing the third quantity is higher than a limit value.

Description

Technical Field

[0001] The technology disclosed herein relates to a method for checking the functionality of a first metering unit, a checking device, and a motor vehicle. Background Art

[0002] Many motor vehicles have multiple metering units, such as nozzles, for introducing a working medium (such as water or AdBlue®) into the pipelines and / or combustion chambers of the motor. Here, it is often problematic that one of the metering units is installed at a location in the motor compartment of the motor vehicle where the metering unit is difficult to disassemble and check its functionality. Therefore, checking the functionality of the metering unit is technically cumbersome. Summary of the Invention

[0003] A preferred task of the technology disclosed herein is to reduce or eliminate at least one drawback of the known solutions or to propose alternative solutions. In particular, a preferred task of the technology disclosed herein is to provide a method or a checking device by means of which the functionality of the metering unit of a metering system for introducing a working medium into a motor vehicle can be simply checked technically. Further preferred tasks can result from the beneficial effects of the technology disclosed herein.

[0004] This task is solved in particular by a method for checking the functionality of a first metering unit for introducing a working medium into a line and / or a combustion chamber of a motor vehicle engine, in which the exhaust gas of the engine is transported or guided in the line, wherein the first metering unit is part of a metering system, wherein the metering system further comprises a second metering unit for introducing a working medium into a line and / or a combustion chamber of the engine, in which the exhaust gas of the engine is transported or guided in the line, wherein the method comprises the following steps: sending a control signal to the second metering unit for outputting a second preset amount of the working medium; detecting the amount of the working medium actually output by the second metering unit in response to the control signal for outputting the second preset amount of the working medium; comparing the amount of the working medium actually output by the second metering unit with the second preset amount of the working medium for checking the functionality of the second metering unit; sending a control signal to the second metering unit for introducing a third preset amount of the working medium; detecting the pressure drop of the working medium in the metering system caused by introducing the third preset amount of the working medium, and / or detecting the number of pump cycles performed by a pump for supplying the working medium to the second metering unit in association with introducing the third preset amount of the working medium through the second metering unit; sending a control signal to the first metering unit for introducing a first preset amount of the working medium; detecting the pressure drop of the working medium in the metering system caused by implementing the control signal for introducing the first preset amount of the working medium by the first metering unit, and / or detecting the number of pump cycles performed by a pump for supplying the working medium to the first metering unit in association with introducing the first preset amount of the working medium through the first metering unit;Compare: the detected pressure drop caused by the control signal for introducing the first preset amount implemented by the first metering unit and the detected pressure drop caused by the control signal for introducing the third preset amount implemented by the second metering unit, and / or the detected pressure drop relative to the first preset amount caused by the control signal for introducing the first preset amount implemented by the first metering unit and the detected pressure drop relative to the third preset amount caused by the control signal for introducing the third preset amount implemented by the second metering unit, and / or the number of pump cycles executed by the pump for supplying the working medium to the first metering unit in association with introducing the first preset amount of the working medium through the first metering unit and the number of pump cycles executed by the pump for supplying the working medium to the second metering unit in association with introducing the third preset amount of the working medium through the second metering unit, and / or the number of pump cycles related to the first preset amount executed by the pump for supplying the working medium to the first metering unit in association with introducing the first preset amount of the working medium through the first metering unit and the number of pump cycles related to the third preset amount executed by the pump for supplying the working medium to the second metering unit in association with introducing the third preset amount of the working medium through the second metering unit; and when the difference between the compared values is higher than a preset limit value, determine that the first metering unit is not operating in compliance.;

[0005] The advantage is that the metering units of the metering system, in particular the first metering unit, can be simply tested for their functionality technically. Thus, it is possible to test whether the amount of the working medium output by the first metering unit is the amount of the working medium that should be output by the control signal without removing the first metering unit from the engine compartment. When introducing, the pressure drop and / or the number of pump cycles of the pump can be checked for credibility on the first metering unit. In this way, the pressure drop at the first metering unit can be correlated with or normalized to the actually output amount of the working medium. Thus, the first metering unit can be simply tested for its functionality technically. Therefore, it can be determined whether the first metering unit or the second metering unit has a fault, that is, does not work in compliance with the regulations, when there is a large difference between the pressure drops on the first metering unit and the second metering unit or between the pressure drops relative to the first preset amount and the third preset amount and / or between the number of pump cycles of the pump or between the number of pump cycles relative to the first preset amount and the third preset amount. The second metering unit can be subjected to a metering quantity test. When the difference between the measured or detected pressure drops or the normalized pressure drops (pressure drops relative to the preset amount) and / or the difference between the number of pump cycles or the normalized number of pump cycles (number of pump cycles relative to the preset amount of pump cycles) is greater than the preset value, it can be determined that the first metering unit does not work in compliance with the regulations because the proper working mode of the second metering unit has been tested and the second metering unit can thus be used as a reference. In this case, the first metering unit can be replaced or repaired or can be adapted accordingly to the control signal for the first metering unit so that the desired amount of the working medium is also actually output by the first metering unit. The first metering unit can be mounted on the engine closer to the engine, in particular closer than the second metering unit. The second metering unit can be mounted in the area under the engine base plate. The second metering unit can generally be disassembled more simply than the first metering unit. Typically, the first metering unit and the second metering unit are connected to a common pump in the metering system.

[0006] In particular, this task is also solved by an inspection device for checking the functionality of a first metering unit of a metering system, wherein the metering system is configured to introduce a working medium into a pipeline and / or a combustion chamber of a motor vehicle engine, wherein the metering system further includes a second metering unit for introducing the working medium, and wherein the inspection device is configured to: send a control signal for introducing a third preset amount of the working medium to the second metering unit; send a control signal for introducing a second preset amount of the working medium to the second metering unit; detect the amount of the working medium actually output by the second metering unit in response to a signal for outputting the second preset amount; detect the pressure drop of the working medium in the metering system caused by the implementation of the control signal for introducing the third preset amount of the working medium by the second metering unit, and / or detect the number of pump cycles performed by a pump for supplying the working medium to the second metering unit in association with the introduction of the third preset amount of the working medium by the second metering unit; send a control signal for introducing a first preset amount of the working medium to the first metering unit; detect the pressure drop of the working medium in the metering system caused by the implementation of the control signal for introducing the first preset amount of the working medium by the first metering unit, and / or detect the number of pump cycles performed by a pump for supplying the working medium to the first metering unit in association with the introduction of the first preset amount of the working medium by the first metering unit; compare: the detected pressure drop caused by the implementation of the control signal for introducing the first preset amount by the first metering unit and the detected pressure drop caused by the implementation of the control signal for introducing the third preset amount by the second metering unit, or the detected pressure drop relative to the first preset amount caused by the implementation of the control signal for introducing the first preset amount by the first metering unit and the detected pressure drop relative to the third preset amount caused by the implementation of the control signal for introducing the third preset amount by the second metering unit, and / or the number of pump cycles performed by a pump for supplying the working medium to the first metering unit in association with the introduction of the first preset amount of the working medium by the first metering unit and the number of pump cycles performed by a pump for supplying the working medium to the second metering unit in association with the introduction of the third preset amount of the working medium by the second metering unit, or the number of pump cycles related to the first preset amount performed by a pump for supplying the working medium to the first metering unit in association with the introduction of the first preset amount of the working medium by the first metering unit and the number of pump cycles related to the third preset amount performed by a pump for supplying the working medium to the second metering unit in association with the introduction of the third preset amount of the working medium by the second metering unit, and determine that the first metering unit is not operating in compliance when the difference between the compared values is higher than a preset limit value.

[0007] The advantages of the inspection device basically correspond to the above advantages of the above method.

[0008] In particular, this task is also solved by a motor vehicle having such a checking device.

[0009] The advantages of the motor vehicle essentially correspond to the above advantages of the above method.

[0010] The values to be compared with each other can in particular be:

[0011] The detected pressure drop caused by the control signal for introducing the first preset amount implemented by the first metering unit compared to the detected pressure drop caused by the control signal for introducing the third preset amount implemented by the second metering unit,

[0012] The detected pressure drop relative to the first preset amount caused by the control signal for introducing the first preset amount implemented by the first metering unit compared to the detected pressure drop relative to the third preset amount caused by the control signal for introducing the third preset amount implemented by the second metering unit,

[0013] The number of pump cycles executed by the pump for supplying the working medium to the first metering unit in association with introducing the first preset amount of the working medium through the first metering unit and the number of pump cycles executed by the pump for supplying the working medium to the second metering unit in association with introducing the third preset amount of the working medium through the second metering unit,

[0014] and / or

[0015] The number of pump cycles related to the first preset amount executed by the pump for supplying the working medium to the first metering unit in association with introducing the first preset amount of the working medium through the first metering unit and the number of pump cycles related to the third preset amount executed by the pump for supplying the working medium to the second metering unit in association with introducing the third preset amount of the working medium through the second metering unit.

[0016] According to one embodiment, the working medium comprises a liquid for exhaust gas aftertreatment by means of selective catalytic reduction (SCR), in particular the working medium is a liquid for exhaust gas aftertreatment by means of selective catalytic reduction (SCR), wherein the two metering units introduce the working medium into the line for guiding the engine exhaust gas, respectively. Here, it is advantageous that a functional check of the metering unit can be carried out technically simply in the event of a fault in the exhaust gas aftertreatment.

[0017] According to one embodiment, the working medium comprises water, in particular the working medium is water, wherein the two metering units introduce the working medium into a pipeline for supplying fuel to a motor vehicle engine. The advantage is that in the case of water injection for cooling the air for combustion in the engine, it can be technically simply checked whether the preset quantity is also actually output by the first metering unit. This improves the performance of the engine. It is also possible that the working medium comprises alcohol, such as ethanol and / or methanol, alternatively or additionally to water.

[0018] According to one embodiment, during the step of sending a control signal for introducing a second preset quantity of the working medium to the second metering unit, the second metering unit is removed from the motor vehicle engine. The advantage is that the functionality of the second metering unit can be checked technically particularly simply and reliably. Thus, the functionality of the metering system can be checked particularly reliably.

[0019] According to one embodiment, the step of detecting the quantity of the working medium actually output by the second metering unit is performed by directly or indirectly measuring the quantity of the working medium output by the second metering unit. The advantage is that the quantity of the working medium actually output can be detected or determined particularly accurately. Thus, the second metering unit can be checked particularly reliably. In particular, the quantity of the working medium actually output by the second metering unit can be determined by collecting and measuring the quantity of the working medium introduced by the second metering unit.

[0020] According to one embodiment, the method is performed when there is a fault indication of the metering system. The advantage is that the first metering unit is only checked when a fault occurs. Thus, unnecessary checks are prevented.

[0021] According to one embodiment, during the operation of a motor vehicle, in particular during driving operation, the steps are carried out of: sending a control signal to a second metering unit for introducing a third predetermined amount of working medium; detecting the pressure drop of the working medium in the metering system caused by introducing the third predetermined amount of working medium and / or detecting the number of pump cycles performed by a pump for supplying the working medium to the second metering unit in association with introducing the third predetermined amount of working medium through the second metering unit; sending a control signal to the second metering unit for introducing a second predetermined amount of working medium; detecting the pressure drop of the working medium in the metering system caused by implementing the control signal for introducing a first predetermined amount of working medium through a first metering unit, and / or detecting the number of pump cycles performed by the pump for supplying the working medium to the first metering unit in association with introducing the first predetermined amount of working medium through the first metering unit; and comparing the pressure drops, or comparing the pressure drops related to the respective predetermined amounts, and / or comparing the number of pump cycles, and / or comparing the number of pump cycles related to the respective predetermined amounts. The advantage is that the motor is hot during these inspection steps, so that in particular when the working medium comprises a liquid for exhaust gas aftertreatment by means of selective catalytic reduction (SCR), possible damage to the catalytic converter is reliably prevented. Therefore, the method can be carried out particularly reliably.

[0022] According to one embodiment, a first metering unit conveys or introduces the working medium into a pipeline upstream of a first catalytic converter, and a second metering unit conveys or introduces the working medium into a pipeline upstream of a second catalytic converter. The advantage is that the metering units are thus in a particularly favorable position for exhaust gas aftertreatment. In this way, it is thus possible to check whether a sufficient amount, i.e. a predetermined amount, of working medium is actually supplied to the respective catalytic converter via the respective metering unit.

[0023] A preferred working medium is fuel. It is also conceivable that the technology disclosed herein is used for storing other liquids (such as water or aqueous solutions) in a motor vehicle. Even if the terms "working medium container", "working medium pump", etc. are mentioned here, the terms "fuel container" or "fuel pump" should be considered to be disclosed as it were.

[0024] The metering unit may comprise an injection nozzle or may be an injection nozzle. The metering system may comprise an injection system or may be an injection system.

[0025] The technology disclosed herein furthermore relates to a working medium container which is configured for a storage volume for storing a working medium. The working medium container thus forms a substantially fluid-tight outer casing of the storage volume and delimits the storage volume with respect to the installation space. In the case of a plastic container, a vesicle is for example meant. In the case of a steel container, the working medium container can for example be constructed from two metal shells. The working medium container can advantageously have a saddle shape which has a main chamber and a secondary chamber, the main chamber and the secondary chamber being interconnected via a connecting region.

[0026] In other words, the technology disclosed herein relates to a method in which conclusions about the characteristics of a second metering unit (second injector) can be drawn by comparing the pressure levels or the number of pump cycles of two metering units of a hydraulically connected metering system when measuring one of the two metering units (injectors).

[0027] The number of metering units can also be more than two, for example three metering units, four metering units or six metering units. Description of the Drawings

[0028] The technology disclosed herein will now be explained with the aid of the drawings. Shown are:

[0029] Figure 1 A schematic view of a motor vehicle having an inspection device according to the technology disclosed herein; and

[0030] Figure 2 A schematic view of a further motor vehicle having an inspection device according to the technology disclosed herein. Detailed Description

[0031] Figure 1 A schematic view of a motor vehicle 70 having an inspection device 80 according to the technology disclosed herein is shown.

[0032] The motor vehicle 70 has a metering system 10, wherein the metering system 10 has a first metering unit 20 (for example a first injector or a first injection nozzle) and a second metering unit 30 (second injector or second injection nozzle). The metering units 20, 30 are configured for injecting or introducing a working medium. The injection nozzle can inject the working medium into the lines of the motor vehicle 70 and / or into the combustion chamber of the motor vehicle engine. The working medium is arranged or stored in a working medium container 90 in the motor vehicle 70.

[0033] The working medium can include a liquid for exhaust gas aftertreatment by means of selective catalytic reduction (SCR). The working medium can in particular include AdBlue® or an aqueous urea solution. The working medium container 90 can for example comprise an HDPE injection molding or consist of an HDPE injection molding.

[0034] The motor vehicle 70 has a test device 80 for testing the functionality of the metering system 10 or the first metering unit 20.

[0035] The first metering unit 20 is arranged near the motor 60 of the motor vehicle 70. The first metering unit 20 is arranged between the motor 60 and the first catalytic converter 45. The second metering unit 30 is arranged between the first catalytic converter 45 and the second catalytic converter 55. The second metering unit 30 can be arranged in the motor 60 or in the underfloor area of the engine compartment.

[0036] The metering units 20, 30 thus respectively convey or introduce the working medium into the pipelines 40, 50 in which the exhaust gas of the motor 60 is transported or guided. The pipelines 40, 50 can extend transversely to the driving direction of the motor vehicle 70. The motor 60 can be installed transversely to the driving direction.

[0037] The test device 80 can control the respective metering units 20, 30 with a control signal in order to respectively convey or introduce or output a preset amount of the working medium. The control signal can for example specify how long the metering units 20, 30 or the injection nozzles are open.

[0038] The first metering unit 20 and the second metering unit 30 are typically fluidly connected to each other.

[0039] The first metering unit 20 is mostly in a position from which it is difficult or troublesome to disassemble the first metering unit. Therefore, the first metering unit 20 is tested with the aid of the second metering unit 30. This can be done in an invasive manner, that is, when there are corresponding faults or fault entries. For example, when the difference in the pressure drop during the conveyance or introduction or injection in the two metering units 20, 30 is higher than a preset value, there may be a fault in the metering system 10. Then although it can be determined that the cause of the fault indication may be that one of the metering units 20, 30 is not working properly, it is not clear whether this is the cause of the fault indication or which metering unit 20, 30 may be defective.

[0040] First, the second metering unit 30 is disassembled from the motor 60. A control signal is issued for outputting a second preset amount of the working medium or liquid to the second metering unit 30. The amount of the working medium actually output by the second metering unit 30 is detected or measured here. This can be achieved for example by collecting the working medium conveyed or output by the second metering unit 30 and measuring the amount of the collected working medium.

[0041] Now, the second preset quantity and the quantity of the working medium actually conveyed or output are compared with each other in order to determine whether the second metering unit 30 is operating in compliance. If the difference between the second preset quantity and the quantity of the working medium actually conveyed or output by the second metering unit 30 is below a preset value (for example, below 10% of the first preset quantity, especially below 8%, preferably below 5% or 2%), then the second metering unit 30 is operating in compliance.

[0042] However, it is also conceivable to perform these steps while the second metering unit 30 remains installed in the motor 60.

[0043] Now, the second metering unit 30 is reinstalled at the original location in the motor vehicle 70. Then, control signals are respectively output to the first metering unit 20 and the second metering unit 30 for conveying or introducing or outputting a first preset quantity or a third preset quantity of the working medium into the pipelines 40, 50.

[0044] The second preset quantity can be the same as the first preset quantity. However, it is conceivable that the second preset quantity can be greater than the first preset quantity or less than the first preset quantity.

[0045] The third preset quantity can be the same as the second preset quantity. However, it is possible that the second preset quantity is different from the third preset quantity.

[0046] During the conveying or introducing, the pressure drop or pressure difference in the metering system 10 at the first metering unit 20 and the second metering unit 30 is respectively detected.

[0047] By comparing the pressure drop or the pressure drop relative to the first preset quantity or the third preset quantity in the metering system 10 or on the two metering units 20, 30, it can be determined whether the quantity actually introduced by the first metering unit 20 corresponds to the quantity that should be introduced by means of the control signal from the first metering unit 20 (which is the first preset quantity).

[0048] If the difference between the pressure drops is below a preset value (for example, below 10%, 8%, 3% or 1.5% of the higher value), it is determined that the first metering unit 20 is operating in compliance. If the difference is equal to the preset value or higher than the preset value, it is determined that the first metering unit 20 is not operating in compliance. This can be displayed by a warning prompt and / or a fault prompt. Then, the first metering unit 20 can be replaced or repaired.

[0049] The steps after reinstalling the second metering unit 30 can be performed during the normal driving operation of the motor vehicle 70, especially when the motor 60 is hot or the temperature of the motor 60 has exceeded a preset minimum temperature.

[0050] The inspection device 80 is configured to implement the above method.

[0051] The pressure drop across the two metering devices 20, 30 can be carried out alternately (i.e., the metering devices 20, 30 are alternately actuated) or can occur or be detected in a cumulative manner for each metering device 20, 30 over a preset time period.

[0052] In the following description of the Figure 2 alternative embodiments shown, the same reference numerals are used for features that are identical and / or at least similar in their configuration and / or mode of operation compared to the Figure 1 first embodiment shown. As long as it is not explained in detail again, their configuration and / or mode of operation correspond to those of the features already described above.

[0053] Figure 2 Schematic illustration of a further motor vehicle 70 having an inspection device 80 according to the technology disclosed herein. Figure 2 The embodiment shown in Figure 1 differs from the first embodiment of

[0054] in that the working medium in the second embodiment comprises or is water and / or methanol and / or ethanol, and the metering units 20, 30 are arranged such that the working medium is conveyed or introduced into the first line 40 by means of the first metering unit 20 and into the second line 50 by means of the second metering unit 30, where the two lines 40, 50 supply fuel to the motor 60 respectively.

[0055] It is also conceivable that the metering units 20, 30 inject or introduce the working medium directly into the combustion chamber of the motor 60 of the motor vehicle 70. It is also possible that one or both metering units 20, 30 add the working medium to the fuel (DWI).

[0056] It is also possible to compare the pump cycle numbers or standardized pump cycles or standardized pump cycle numbers instead of or in addition to the pressure drop or standardized pressure drop.

[0057] After checking the functionality of the second metering unit 30 as described above, the pump cycle numbers when introducing the first preset amount and the third preset amount are detected. Typically, one pump supplies the first metering unit 20 and the second metering unit 30.

[0058] A control signal for introducing the first preset amount through the first metering unit 20 is sent to the first metering unit 20. The pump cycle number during the introduction of the first preset amount is detected or counted.

[0059] Now, a control signal for conveying the third preset amount is sent to the second metering unit 30. The pump cycle number during the introduction of the third preset amount is detected or counted.

[0060] Now, compare the number of pump cycles when introducing a first preset amount through the first metering unit 20 and when introducing a third preset amount through the second metering unit 30. This can be carried out especially when the first preset amount is equal to the third preset amount.

[0061] When the difference between the values being compared with each other corresponds at least to a preset value, that is to say, is greater than or equal to the preset value, it is determined that the first metering unit 20 is not fully functional. When the difference is below the preset value, it is determined that the first metering unit 20 is fully functional.

[0062] It is also possible to compare the number of pump cycles with the corresponding preset amount (so-called normalized number of pump cycles). When the first preset amount is different from the third preset amount, typically the number of pump cycles is not directly compared, but rather the ratio of the number of pump cycles to the corresponding preset amount is compared. When the difference between the number of pump cycles and the corresponding preset amount corresponds at least to a preset value, it is determined that the first metering unit 20 is not fully functional. When the difference between the number of pump cycles and the corresponding preset amount is below the preset value, it is determined that the first metering unit 20 is fully functional. For example, the third preset amount can be twice the first preset amount. When the pump requires or performs twice the number of pump cycles when introducing the third preset amount as when introducing the first preset amount, the first metering unit 20 is fully functional.

[0063] The pumps can be pressure-controlled respectively, that is to say, when the pressure drops, the pumps convey the working medium, more precisely, convey the working medium until the preset pressure is restored in the metering system.

[0064] The control unit can be implemented or configured in the control device of the motor vehicle 70 by means of a software function.

[0065] For the sake of readability, the expression "at least one" has been partially omitted in a simplified manner. If the features of the technology disclosed herein are described in the singular or in an indefinite manner (such as the inspection device 80 / inspection device, the metering system 10 / metering system, the working medium container 90 / working medium container, etc.), then multiple (such as at least one inspection device 80, at least one metering system 10, at least one working medium container 90, etc.) should also be disclosed at the same time.

[0066] The term "substantially" (such as "substantially vertical axis") in the context of the technology disclosed herein includes respectively the exact characteristic or exact value (such as "vertical axis") as well as deviations that are not significant for the function of the characteristic / value (such as "tolerable deviation from the vertical axis").

[0067] The above description of the present invention is for illustrative purposes only and is not intended to limit the present invention. Within the scope of the present invention, various changes and modifications are possible without departing from the scope of the present invention and its equivalents.

[0068] List of Reference Numerals

[0069] 10 Metering system

[0070] 20 First metering unit

[0071] 30 Second metering unit

[0072] 40 First pipeline

[0073] 45 First catalytic converter

[0074] 50 Second pipeline

[0075] 55 Second catalytic converter

[0076] 60 Motor

[0077] 70 Motor vehicle

[0078] 80 Inspection device

[0079] 90 Working medium container

Claims

1. A method for checking the functionality of a first metering unit (20) for introducing a working medium into a line (40, 50) and / or a combustion chamber of a motor (60) of a motor vehicle (70), wherein the exhaust gas of the motor (60) is transported or guided in the line, wherein, The first metering unit (20) is part of a metering system (10), wherein the metering system (10) further includes a second metering unit (30) for introducing the working medium into a pipeline (40, 50) and / or a combustion chamber of a motor (60), and the exhaust gas of the motor (60) is transported or guided in the pipeline, and wherein the method includes the following steps: Sending a control signal for outputting a second preset amount of the working medium to the second metering unit (30); Detecting the amount of the working medium actually output by the second metering unit (30) in response to the control signal for outputting the second preset amount of the working medium; Comparing the amount of the working medium actually output by the second metering unit (30) with the second preset amount of the working medium for checking the functionality of the second metering unit (30); Sending a control signal for introducing a third preset amount of the working medium to the second metering unit (30); Detecting the pressure drop of the working medium in the metering system (10) caused by introducing the third preset amount of the working medium, and / or detecting the number of pump cycles performed by a pump for supplying the working medium to the second metering unit (30) in association with introducing the third preset amount of the working medium through the second metering unit (30); Sending a control signal for introducing a first preset amount of the working medium to the first metering unit (20); Detecting the pressure drop of the working medium in the metering system (10) caused by implementing the control signal for introducing the first preset amount of the working medium by the first metering unit (20), and / or detecting the number of pump cycles performed by a pump for supplying the working medium to the first metering unit (20) in association with introducing the first preset amount of the working medium through the first metering unit (20); Comparing: The detected pressure drop caused by implementing the control signal for introducing the first preset amount by the first metering unit (20) and the detected pressure drop caused by implementing the control signal for introducing the third preset amount by the second metering unit (30), and / or, The detected pressure drop relative to the first preset amount caused by implementing the control signal for introducing the first preset amount by the first metering unit (20) and the detected pressure drop relative to the third preset amount caused by implementing the control signal for introducing the third preset amount by the second metering unit (30), and / or, The number of pump cycles performed by the pump for supplying the working medium to the first metering unit (20) in association with introducing the first preset amount of the working medium through the first metering unit (20) and the number of pump cycles performed by the pump for supplying the working medium to the second metering unit (30) in association with introducing the third preset amount of the working medium through the second metering unit (30), and / or, The pump performs a number of pump cycles related to the first preset quantity associated with introducing a first preset quantity of the working medium into the first metering unit (20) in order to supply the working medium to the first metering unit (20), and a number of pump cycles related to the third preset quantity associated with introducing a third preset quantity of the working medium into the second metering unit (30) in order to supply the working medium to the second metering unit (30); and When the difference between the compared values is higher than a preset limit value, it is determined that the first metering unit (20) is not operating in compliance.

2. The method according to claim 1, wherein, The working medium includes a liquid for post-treatment of exhaust gas by means of selective catalytic reduction (SCR), wherein the first metering unit (20) and the second metering unit (30) introduce the working medium into pipelines (40, 50) for guiding the exhaust gas of the motor (60) respectively.

3. The method according to claim 1 or 2, wherein, The working medium includes water, wherein the first metering unit (20) and the second metering unit (30) introduce the working medium into pipelines (40, 50) for supplying fuel to the motor (60) of the motor vehicle (70).

4. The method according to claim 1 or 2, wherein, During the step of sending a control signal for introducing a second preset quantity of the working medium to the second metering unit (30), the second metering unit (30) is detached from the motor (60) of the motor vehicle (70).

5. The method according to claim 1 or 2, wherein, Perform the step of detecting the quantity of the working medium actually output by the second metering unit (30) by directly measuring the quantity of the working medium output by the second metering unit (30).

6. The method according to claim 1 or 2, wherein, When there is a fault indication of the metering system (10), perform the method.

7. The method according to claim 1 or 2, wherein, During the operation of the motor vehicle (70), perform the following steps: Send a control signal for introducing a third preset quantity of the working medium to the second metering unit (30); Detect the pressure drop of the working medium in the metering system (10) caused by introducing the third preset quantity of the working medium, and / or detect the number of pump cycles performed by the pump in order to supply the working medium to the second metering unit (30) associated with introducing the third preset quantity of the working medium through the second metering unit (30); Send a control signal for introducing a second preset quantity of the working medium to the second metering unit (30); Detect the pressure drop of the working medium in the metering system (10) caused by implementing the control signal for introducing the first preset quantity of the working medium by the first metering unit (20), and / or detect the number of pump cycles performed by the pump in order to supply the working medium to the first metering unit (20) associated with introducing the first preset quantity of the working medium through the first metering unit (20); And Compare the pressure drops, or compare the pressure drops related to the respective preset quantities, and / or compare the pump cycle numbers, and / or compare the pump cycle numbers related to the respective preset quantities.

8. The method according to claim 1 or 2, wherein, The first metering unit (20) introduces the working medium into the pipelines (40, 50) upstream of the first catalytic converter (45), and the second metering unit (30) introduces the working medium into the pipelines (40, 50) upstream of the second catalytic converter (55).

9. An inspection device (80) for inspecting the functionality of a first metering unit (20) of a metering system (10), wherein, The metering system (10) further includes a second metering unit (30) for introducing the working medium. The first metering unit (20) and the second metering unit (30) are configured to introduce the working medium into the pipelines (40, 50) and / or the combustion chamber of the motor (60) of a motor vehicle (70), and the exhaust gas of the motor (60) is transported or guided in the pipelines. wherein the inspection device (80) is configured to send a control signal for introducing a third preset amount of the working medium to the second metering unit (30); send a control signal for introducing a second preset amount of the working medium to the second metering unit (30); detect the amount of the working medium actually output by the second metering unit (30) in response to the signal for outputting the second preset amount; compare the amount of the working medium actually output by the second metering unit (30) with the second preset amount of the working medium to check the functionality of the second metering unit (30); detect the pressure drop of the working medium in the metering system (10) caused by the implementation of the control signal for introducing a third preset amount of the working medium by the second metering unit (30), and / or detect the number of pump cycles performed by the pump for supplying the working medium to the second metering unit (30) in association with the introduction of a third preset amount of the working medium by the second metering unit (30); send a control signal for introducing a first preset amount of the working medium to the first metering unit (20); detect the pressure drop of the working medium in the metering system (10) caused by the implementation of the control signal for introducing a first preset amount of the working medium by the first metering unit (20), and / or detect the number of pump cycles performed by the pump for supplying the working medium to the first metering unit (20) in association with the introduction of a first preset amount of the working medium by the first metering unit (20); for comparing the detected pressure drop caused by the implementation of the control signal for introducing the first preset amount by the first metering unit (20) and the detected pressure drop caused by the implementation of the control signal for introducing the third preset amount by the second metering unit (30), and / or, the detected pressure drop relative to the first preset amount caused by the implementation of the control signal for introducing the first preset amount by the first metering unit (20) and the detected pressure drop relative to the third preset amount caused by the implementation of the control signal for introducing the third preset amount by the second metering unit (30), and / or, The number of pump cycles that the pump performs in connection with introducing a first preset amount of the working medium into the first metering unit (20) for supplying the working medium to the first metering unit (20), and the number of pump cycles that the pump performs in connection with introducing a third preset amount of the working medium into the second metering unit (30) for supplying the working medium to the second metering unit (30), and / or, The number of pump cycles related to the first preset amount that the pump performs in connection with introducing the first preset amount of the working medium into the first metering unit (20) for supplying the working medium to the first metering unit (20), and the number of pump cycles related to the third preset amount that the pump performs in connection with introducing the third preset amount of the working medium into the second metering unit (30) for supplying the working medium to the second metering unit (30); and For determining that the first metering unit (20) is not operating in compliance when the difference between the values being compared is higher than a preset limit value.

10. A motor vehicle (70) having the inspection device (80) according to claim 9.

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