Device and method for quality assurance of exhaust gas behavior in a motor vehicle

Abstract

Device for quality assurance of the exhaust gas behavior in a motor vehicle with an internal combustion engine (1), comprising a control element (2) for specifying a desired drive torque (M) by the driver and comprising at least one electronic control unit (3): - an on-board diagnostic module (4) for performing an on-board diagnostic function for on-board diagnosis of the functionality of an exhaust-related component of the motor vehicle, - a memory module (5), - a control module (6) which is connected to the control element (2) for detecting the desired drive torque (M), to the on-board diagnostic module (4) for detecting the start of an on-board diagnostic function, to the storage module (5) and to the actuators of the internal combustion engine (1) for controlling the air mass (L) and the ignition (Z), and is designed such that the target air mass (L) corresponding to the desired drive torque (M) is stored when the on-board diagnostic function is started, and that if the desired drive torque (M) is reduced, this reduction is carried out by retarding the ignition (Z) while maintaining the stored target air mass (L), until the on-board diagnostic function is completed or aborted.

Description

[0001] The present invention relates to a device and a method for quality assurance of exhaust gas behavior in a motor vehicle, in particular within the framework of a legally prescribed on-board diagnosis. The diagnostic process and thus, at least indirectly, the exhaust gas behavior are improved.

[0002] In motor vehicles with combustion engines, so-called on-board diagnostics (OBD) are carried out in order to monitor exhaust-relevant components or devices.

[0003] For example, for vehicles registered in the USA, there is a legal requirement that a certain diagnostic frequency (also known as the "ratio" or "IUMPR: in-use monitor performance ratio") be guaranteed. These values ​​are verified in the field and must exceed defined thresholds. The diagnostic frequency has been increased in terms of the number of driving cycles. Thus, for the same customer driving behavior, OBD functions must be performed more than three times as often as before.

[0004] For example, DE 10 2017 200 994 A1 discloses a method comprising the following steps: - Monitors an on-board diagnostic function of the motor vehicle, whereby the on-board diagnostic function is relevant to the exhaust emissions of the motor vehicle. - Maintaining a trip counter, which is indicative of the number of journeys made by the motor vehicle. - Provision of a diagnostic counter for the on-board diagnostic function of the motor vehicle affected by the monitoring. - Maintaining a diagnostic frequency target value. Incrementing the trip counter after the start of a vehicle driving cycle and a predetermined driving duration. - Formation of an actual diagnostic frequency value by means of a suitable combination of the diagnostic counter with the trip counter. - Forming a difference between the diagnostic frequency target value and the diagnostic frequency actual value.

[0005] If the difference between the diagnostic frequency target value and the diagnostic frequency actual value falls below a difference threshold: - Selecting a control method from a control method group, wherein each control method of the control method group is indicative of a corresponding motor control of a drive motor of the motor vehicle. - The selected control method is suitable for successfully completing a currently running on-board diagnosis of the on-board diagnostic function or for successfully initiating and completing a non-running on-board diagnosis of the on-board diagnostic function.

[0006] And the procedure further includes, after completion of the on-board diagnostic function, the following: - Incrementing the diagnostic counter of the on-board diagnostic function. - And reset the motor control to an original motor control, according to a state before the control method was selected.

[0007] The process steps can be carried out automatically.

[0008] An on-board diagnostic function within the meaning of this teaching can comprise a process that performs a diagnosis of an emissions-related device in order to check and / or log the functioning of the emissions-related device. For example, at least one corresponding on-board diagnostic function can be provided for each emissions-related device of the motor vehicle.

[0009] A diagnostic frequency target value within the meaning of this theory can be a value that determines how often a corresponding diagnosis should be successfully performed. The diagnostic frequency target value can be different for each diagnostic function. The diagnostic frequency target value can be the same for each diagnostic function.

[0010] The diagnostic frequency target value can be specified by a regulatory authority.

[0011] The diagnostic frequency target value can be a fixed value.

[0012] A diagnosis frequency actual value in the sense of this theory can be a value that records how often a corresponding diagnosis was successfully carried out.

[0013] The corresponding frequency of performing the corresponding diagnosis can be specified in relation to the number of driving cycles of the motor vehicle.

[0014] A predetermined driving duration of the motor vehicle within the meaning of the invention can be a period of time which must have passed in order for a driving cycle to be considered as such.

[0015] For further prior art, reference is made to US 2010 / 0 163 008 A1, US 8 478 501 B1, DE 44 02 850 A1 and GB 2 410 560 A.

[0016] The object of the invention is to provide an improved possibility by which the highest possible ratio of diagnoses for exhaust gas-relevant devices can be achieved.

[0017] This object is achieved by the features of the independent claims. Advantageous developments of the invention are the subject matter of the dependent patent claims.

[0018] The invention essentially relates to a device and a method for quality assurance of exhaust gas behavior in a motor vehicle with an internal combustion engine, with an operating element for specifying a desired drive torque by the driver and with at least one electronic control unit, wherein - an on-board diagnostic function for on-board diagnosis of the functionality of an exhaust-relevant component of the motor vehicle is carried out by means of an on-board diagnostic module and - the desired drive torque is recorded by means of a control module, the start of an on-board diagnostic function is determined, the corresponding target air mass is stored when the on-board diagnostic function is started and, if the desired drive torque is reduced, this reduction is carried out by retarding the ignition while maintaining the stored target air mass until the on-board diagnostic function is completed or aborted. Preferably, the mass flow can also be compensated by maintaining a torque reserve when accelerating by improving the ignition angle efficiency.

[0019] The invention is based on the following considerations: Stable operating points are a prerequisite for many diagnostics. Since driving with the accelerator pedal "pumping" is common practice in some countries, this condition is rarely met.

[0020] In other words, according to the invention, the operating point is stabilized by keeping the filling of the combustion engine as constant as possible during a diagnosis and by prioritizing the driver's request over the ignition angle efficiency.

[0021] The invention is explained by the following exemplary embodiment: If a diagnosis begins with a torque request of 100 Nm, for example, a charge of 70% could be required for this request. If the driver subsequently eases off the accelerator and then requests, for example, 80 Nm, the target charge is maintained at 70% according to the invention, and the 80 Nm is adjusted via ignition retard.

[0022] The invention is described in more detail below with reference to the single figure ( Fig. 1). It shows a schematic representation of the essential components of the device according to the invention according to a further exemplary embodiment of the invention.

[0023] In Fig. 1 shows an internal combustion engine 1 of a motor vehicle not otherwise shown in detail, the exhaust gas-relevant components of which are to be diagnosed.

[0024] Furthermore, an operating element 2, in particular a throttle lever or an accelerator pedal, is shown for specifying a desired drive torque M (also called load request) by the driver.

[0025] Finally, an electronic control unit 3 is shown, which comprises the following functional modules: - an on-board diagnostic module 4 for executing an on-board diagnostic function for on-board diagnosis of the functionality of an exhaust-relevant component of the motor vehicle, - a memory module 5 and - a control module 6.

[0026] The control module 6 is connected to the control element 2 for detecting the desired drive torque M, to the on-board diagnostic module 4 for detecting the start of an on-board diagnostic function, to the memory module 5 and to the actuators of the combustion engine 1 for controlling the air mass L (also called filling) and the ignition Z.

[0027] In particular, by appropriate programming (computer program product), the control module 6 is designed such that the desired air mass L corresponding to the desired drive torque M when the on-board diagnostic function is started is stored in the memory module 5 and that when the desired drive torque M is reduced, this reduction is carried out by retarding the ignition while maintaining the stored desired air mass L until the on-board diagnostic function is completed or aborted.

[0028] Preferably, the control module 6 is further configured such that the on-board diagnostic function is aborted if a desired drive torque M is specified below a predetermined minimum threshold, particularly during overrun cutoff. The diagnostic function is generally aborted if the air mass fluctuates too significantly.

[0029] Since the function doesn't change the driver's input, it's still possible to enter overrun cutoff. This overrun cutoff aborts the diagnosis and thus the function. It's not the function that is aborted, which enables overrun cutoff.

[0030] The invention makes it possible to carry out particularly problematic diagnostic functions, such as lambda probe diagnosis or oxygen measurement for catalyst diagnosis, which are only possible in a relatively narrow speed window and / or engine load window.

Claims

[1] Device for quality assurance of exhaust gas behaviour in a motor vehicle with an internal combustion engine (1), with an operating element (2) for specifying a desired drive torque (M) by the driver and with at least one electronic control unit (3) comprising: - an on-board diagnostic module (4) for executing an on-board diagnostic function for on-board diagnosis of the functionality of an exhaust-relevant component of the motor vehicle, - a memory module (5), - a control module (6) which is connected to the control element (2) for detecting the desired drive torque (M), to the on-board diagnostic module (4) for determining the start of an on-board diagnostic function, to the memory module (5) and to the actuators of the internal combustion engine (1) for controlling the air mass (L) and the ignition (Z), and is designed such that the target air mass (L) corresponding to the desired drive torque (M) is stored when the on-board diagnostic function is started, and that when the desired drive torque (M) is reduced, this reduction is carried out by retarding the ignition (Z) while maintaining the stored target air mass (L) until the on-board diagnostic function is completed or aborted. [2] Device according to claim 1, characterized bythat the control module (6) is further designed such that the on-board diagnostic function is aborted if a desired drive torque (M) is specified below a predetermined minimum threshold. [3] Method for quality assurance of exhaust gas behaviour in a motor vehicle with an internal combustion engine (1), with an operating element (2) for specifying a desired drive torque (M) by the driver and with at least one electronic control unit (3), wherein - an on-board diagnostic function for on-board diagnosis of the functionality of an exhaust-relevant component of the motor vehicle is carried out by means of an on-board diagnostic module (4), and - the desired drive torque (M) is detected by means of a control module (6), the start of an on-board diagnostic function is determined, the corresponding target air mass (L) is stored when the on-board diagnostic function (L) is started and, if the desired drive torque (M) is reduced, this reduction is carried out by retarding the ignition while maintaining the stored target air mass (L) until the on-board diagnostic function is completed or aborted. [4] Method according to claim 3, characterized by that the on-board diagnostic function is aborted by means of the control module (6) if a desired drive torque (M) is specified below a predetermined minimum threshold.

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