DE102017223639B3 - Method and device for determining the degree of soiling of an air filter of an internal combustion engine - Google Patents

Abstract

The invention relates to a method and a device for determining the degree of soiling of an air filter (11) arranged in an intake tract (1) of an internal combustion engine (VKM) upstream of an electrically driven compressor (19), comprising the following steps:
a) Determining whether the internal combustion engine (VKM) is in an off state, b) closing a throttle valve (11) arranged in the intake tract (1) downstream of the electrically driven compressor (19) and closing all the other, from the intake tract (1) to an exhaust tract (4) of the internal combustion engine (VKM) leading to the internal combustion engine bypassing bypass lines (193, 195), if the internal combustion engine (VKM) is in an off state, c) switching on the electrically driven compressor (19) for the purpose of pressure build-up in the intake tract (1), d) detecting the temporal pressure buildup behavior by means of a in the intake tract (1) between the throttle valve (12) and the air filter (11) arranged pressure sensor (17), e) comparing the temporal pressure build-up behavior with a predetermined time pressure build-up behavior and f) determining the degree of contamination of the air filter (11) on the basis of the result sses of the comparison in step e).

Description

The invention relates to a method and a device for determining the degree of contamination of an air filter of an internal combustion engine according to the features of the independent claims.

Intake air filters in motor vehicles, usually referred to simply as air filters, in addition to the function of Ansauggeräuschdämpfung have the task to remove impurities from the intake air. As a result, the wear and disturbances during operation of the internal combustion engine are prevented.

Since the air filter is arranged in the intake tract of the internal combustion engine, this also has an influence on the flow resistance of the intake air. The flow resistance in turn has a significant impact on the performance, exhaust emissions and fuel consumption of the internal combustion engine. By a dirty or clogged air filter, the flow resistance increases, which the o.g. Disadvantages result. As a rule, air filters are changed as part of the regular inspection of the motor vehicle. If the motor vehicle is moved for a long time in an environment in which very dusty ambient air prevails, such as in unpaved roads or construction sites, it may happen that the separation efficiency requirements of the air filter are no longer present before the next, routinely scheduled workshop date is due. On the other hand, it is possible that after an inspection interval, the contamination of the air filter has not progressed so far that a change would be necessary.

In the DE 10 2008 005 369 B4 For example, a method of monitoring airflow restriction in an air intake of an internal combustion engine is described. A predetermined number of upstream pressure estimates of a throttle are recorded, a predetermined number of mass airflow readings respectively corresponding to the upstream pressure estimates of the throttle valve are recorded and based on the estimated upstream pressure of the throttle and the mass airflow measurements determines the slope of a linear regression line. Based on the slope value, it is determined whether an air filter causes excessive throttling of the air flow.

From the DE 197 10 981 C2 is described a method for determining a degree of contamination of the intake tract of an internal combustion engine, in particular a vehicle upstream air filter, wherein a pressure difference from the atmospheric pressure in front of the air filter and the prevailing pressure behind the air filter is a measure of the degree of pollution. The atmospheric pressure is detected by a not arranged in the intake and already existing in the vehicle pressure sensor.

1. (a) Bestimmen des Drucks nach dem Verdichter, wobei der Druck nach dem Verdichter in Abhängigkeit von dem Druck vor der Drosselklappe und dem Druckabfall über den Ladeluftkühler bestimmt wird, (b) Bestimmen eines Druckverhältnisses aus dem Druck nach dem Verdichter geteilt durch den Druck vor dem Verdichter anhand der Drehzahl des Turboladers und einem Luftmassenstrom, (c) Berechnen des Drucks vor dem Verdichter aus dem Druckverhältnis und dem Druck nach dem Verdichter, (d) Bestimmen eines Druckabfalls an einem Luftfilter, wobei der Druckabfall an dem Luftfilter aus der Differenz zwischen dem Umgebungsdruck und dem

The DE 10 2008 034 323 B4 discloses a method and apparatus for determining the pressure upstream of the compressor of a turbocharger to determine the degree of fouling of an air filter disposed in front of the compressor of the turbocharger, the method comprising the steps of:

1. (a) determining the pressure downstream of the compressor, wherein the pressure downstream of the compressor is determined as a function of the pressure before the throttle and the pressure drop across the charge air cooler, (b) determining a pressure ratio from the pressure after the compressor divided by the pressure before (c) calculating the pressure before the compressor from the pressure ratio and the pressure after the compressor, (d) determining a pressure drop across an air filter, wherein the pressure drop across the air filter from the difference between the ambient pressure and the

Pressure before the compressor is determined, (e) determining the degree of contamination of the air filter from the pressure drop.

The JP 2012-122 336 A shows an internal combustion engine, which sucks air through an air filter and wherein the internal combustion engine has a boost pressure sensor which detects a boost pressure. Based on a comparison between the detected boost pressure and a predetermined boost pressure value, the presence or absence of a clogged air filter is detected.

In the JP 2016-61 178 A shows a method of how a arranged in the air intake tract of an internal combustion engine polluted air filter can be cleaned. For this purpose, an electrically driven compressor located in the intake tract is operated in reverse mode, so that dust is removed from the air filter and the dust is discharged outside an intake duct.

These known methods assume that the internal combustion engine must be in operation for checking the air filter.

The invention has for its object to provide a method and an apparatus with which or with which it is possible in a simple manner, a arranged in the intake of an internal combustion engine air filter terms to check its cleaning effect during the stoppage of the internal combustion engine.

The object is solved by the features of the independent claims. Advantageous embodiments and further developments of the invention are characterized in the subclaims.

1. a) Ermitteln, ob sich die Verbrennungskraftmaschine in einem ausgeschalteten Zustand befindet, b) Schließen einer im Ansaugtrakt stromabwärts des elektrisch angetriebenen Verdichters angeordneten Drosselklappe und Schließen aller weiteren, von dem Ansaugtrakt zu einem Abgastrakt der Verbrennungskraftmaschine führenden, die Verbrennungskraftmaschine umgehenden Bypassleitungen, falls sich die Verbrennungskraftmaschine in einem ausgeschalteten Zustand befindet, c) Einschalten des elektrisch angetriebenen Verdichters zum Zwecke eines Druckaufbaues in dem Ansaugtrakt, d) Erfassen des zeitlichen Druckaufbauverhaltens mittels eines im Ansaugtrakt zwischen der Drosselklappe und dem Luftfilter angeordneten Drucksensors, e) Vergleichen des zeitlichen Druckaufbauverhaltens mit einem vorgegebenen zeitlichen Druckaufbauverhalten und f) Bestimmung des Verschmutzungsgrades des Luftfilters auf der Basis des Ergebnisses des Vergleiches im Schritt e).

The invention is characterized by a method and a corresponding device for determining the degree of soiling of an air filter arranged in an intake tract of an internal combustion engine upstream of an electrically driven compressor, having the following steps:

1. a) determining whether the internal combustion engine is in an off state, b) closing a throttle located in the intake downstream of the electrically driven compressor and closing all other, leading from the intake manifold to an exhaust tract of the internal combustion engine, bypassing the internal combustion engine bypass lines, if the C) switching on the electrically driven compressor for the purpose of pressure build-up in the intake tract, d) detecting the time pressure build-up behavior by means of a arranged in the intake manifold between the throttle valve and the air filter pressure sensor, e) comparing the temporal pressure build-up behavior with a predetermined temporal pressure build-up behavior and f) determination of the degree of soiling of the air filter on the basis of the result of the comparison in step e).

With the aid of the method or the device according to the invention, the degree of contamination of an air filter arranged in the intake tract of an internal combustion engine can be determined in a simple and cost-effective manner, without the internal combustion engine having to be in operation. The check can therefore be carried out in particular before a start of the internal combustion engine or after switching off the internal combustion engine during the so-called Steuergerätenachlaufs.

By using the already existing for increasing the charge electric compressor, for example in the form of an electric compressor, no additional components for checking the air filter are needed, which contributes to a cost-effective solution.

Also, to hermetically seal the intake tract downstream of the air filter and the electric compressor to regenerate a reproducible pressure build-up behavior used to check the air filter, no additional components are needed. Only by closing the throttle and all bypass lines, which connect the intake tract with the exhaust tract, by means of valves already present in these lines, this can be achieved.

The method is particularly simple if it is checked whether, within a predetermined period of time, the pressure generated by the activation of the electric compressor exceeds a predetermined reference value or not.

• 1 in schematischer Darstellung eine Verbrennungskraftmaschine mit einer Aufladeeinrichtung und zugehöriger Steuerungseinrichtung und
• 2 ein Ablaufschema eines Verfahrens zum Bestimmen des Verschmutzungsgrades eines Luftfilters der Verbrennungskraftmaschine

Further advantages and embodiments of the invention will become apparent from the following description and drawings of an embodiment. Show it:

• 1 a schematic representation of an internal combustion engine with a charging device and associated control device and
• 2 a flowchart of a method for determining the degree of contamination of an air filter of the internal combustion engine

An internal combustion engine VKM includes an intake tract 1 , an engine block 2 , a cylinder head 3 and an exhaust tract 4 ,

The intake tract 1 includes, inter alia, an air filter 11 , a throttle 12 and a suction tube 13 that's going to a cylinder 28 via an inlet channel in the engine block 2 is guided. Upstream of the throttle 12 are an air mass meter serving as a load sensor 14 , an intake air temperature sensor 15 and a pressure sensor 17 intended. Alternatively or in addition to the air mass meter 14 as a load sensor can also be downstream of the throttle 12 one in the intake manifold 13 built-in intake manifold pressure sensor 16 be installed. If both of these sensors are present, the corresponding signals can be made plausible. It is also possible that the intake air temperature sensor 15 and the pressure sensor 17 to a structural unit (sensor module) are summarized. At the throttle 12 it is a so-called electronic throttle, the degree of opening next to the signals that correspond to a driver's request, regardless of electrical signals of the internal combustion engine VKM controlling and regulating control device 6 is adjustable.

The engine block 2 includes a crankshaft 21 , which has a connecting rod 25 with a piston 24 of the cylinder 28 is coupled. The cylinder 28 and the piston 24 limit one dependent on the piston position variable combustion chamber 27 , In the 1 is for clarity only a single cylinder 28 shown the internal combustion engine VKM but can have any number of cylinders.

The cylinder head 3 includes a valvetrain with a gas inlet valve 30 , a gas outlet valve 31 and corresponding, unspecified valve actuators. The cylinder head 3 further includes a spark plug 35 and a fuel injection valve 34 , Alternatively, the fuel injection valve 34 also in the intake manifold 13 be arranged as it is in the 1 shown with dashed lines.

The exhaust tract 4 includes an exhaust gas catalyst 40 , which is preferably designed as a three-way catalyst and optionally a particle filter 41 , Upstream of the catalytic converter 40 is an exhaust gas sensor in the form of a lambda probe 42 arranged. The lambda probe 42 can be designed as a so-called jump probe (binary probe), or designed as a broadband probe (linear probe), with which determines the oxygen concentration in the exhaust gas in a large area and thus the air-fuel ratio in the combustion chamber 27 can be closed.

To increase the cylinder filling and thus to increase the performance of the internal combustion engine VKM an exhaust gas turbocharger is provided, whose turbine 43 in the exhaust tract 4 is arranged and via a shaft, not shown, mechanically in operative connection with a in the intake 1 arranged compressor 18 stands. Thus, the exhaust gases drive the internal combustion engine VKM the turbine 43 and this in turn the compressor 18 , The compressor 18 provides the internal combustion engine VKM a pre-compressed fresh charge. A usually the compressor 18 Downstream intercooler is not shown here. For larger exhaust gas mass flows at high speeds of the internal combustion engine VKM can occur, the exhaust gas turbocharger the internal combustion engine VKM does not overload, a partial flow is in this load range via a bypass line 44 (waste gate), in which a bypass valve 45 is on, at the turbine 43 past upstream of the catalytic converter 40 dissipated. The bypass valve 45 is designed in this example as an electromagnetic valve.

Downstream of the compressor 18 the exhaust gas turbocharger is in the intake tract 1 an electrically driven compressor 19 , For example, an electrically driven compressor is turned on. This serves inter alia to bridge the so-called exhaust gas turbocharger, which describes the poor response of the exhaust gas turbocharger at certain operating point changes. The electrically driven compressor 19 is in each case then switched on when a charge by a request, usually by the driver of the internal combustion engine 1 driven vehicle by the inertia and the physical conditions on the conventional exhaust gas turbocharger can not be implemented sufficiently quickly according to the desired comfort.

The electrically driven compressor 19 Alternatively, it can also be upstream of the compressor 18 be arranged of the exhaust gas turbocharger.

The compressor 18 the exhaust gas turbocharger has a bypass line 181 on, by means of an electrically controllable diverter valve 182 can be closed. The electric powered compressor 19 has a bypass line 191 on, by means of an electrically controllable diverter valve 192 can be closed.

The electrically driven compressor 19 can also for a secondary air injection in the first minutes after a cold start of the internal combustion engine VKM be used. For this purpose, a secondary air line 193 provided downstream of the electrically driven compressor 19 and upstream of the throttle 12 from the intake tract 1 branches off and to a point downstream of the turbine 43 in the exhaust tract 4 in front of the catalytic converter 40 empties. In the secondary air line 193 is an electrically controllable secondary air valve 194 provided after cold start and after reaching a specified minimum temperature for the internal combustion engine VKM is closed.

Further, for returning a part of the exhaust gases is an exhaust gas recirculation line 195 provided, which the exhaust tract 4 with the intake tract 1 such that the exhaust gas downstream of the exhaust aftertreatment system 40 . 41 branched off and at a point upstream of the compressor 18 back to the intake system 1 is returned. Such an arrangement is referred to as low pressure exhaust gas recirculation. With the help of one in the exhaust gas recirculation line 195 built-in, electrically controllable exhaust gas recirculation valve 196 a return of the exhaust gas can be released or prevented.

An electronic control device 6 is provided, the sensors are assigned, which detect different measured variables and determine the measured values of the measured variables. Operating variables include not only the measured variables but also derived from these variables. The control device 6 controls the actuators, that of the internal combustion engine depending on at least one of the operating variables VKM are assigned, and each associated with corresponding actuators, by generating actuating signals for the actuators. The control device 6 can also as Device for operating the internal combustion engine, or simply referred to as engine control unit.

The sensors, their signals to the control device 6 to be supplied include the air mass meter 14 , which is an air mass flow upstream of the throttle 12 detected, the temperature sensor 15 , which detects an intake air temperature, the pressure sensor 16 , which detects an intake manifold pressure, the pressure sensor 17 , An unillustrated throttle position sensor, the opening angle of the throttle 12 detected, a temperature sensor 26 , which is a coolant temperature of the internal combustion engine VKM detected, a crankshaft angle sensor 22 , which is a position of the crankshaft 21 captured and the exhaust probe 42 , which detects a residual oxygen content of the exhaust gas and whose signal is characteristic of the air-fuel ratio in the cylinder 28 during the combustion of the air-fuel mixture.

Depending on the configuration of the internal combustion engine VKM and the periphery of which may be a subset of said sensors, or additional sensors may be present.

The actuators are, for example, the throttle 12 , the injection valve 34 , the spark plug 35 , the diverter valves 182 . 192 , the secondary air valve 194 , the bypass valve 45 , the exhaust gas recirculation valve 196 and the electric compressor 19 ,

The control device 6 preferably comprises a computing unit (processor) 61 that with a program memory 62 and a value memory (data memory) 63 is coupled. The arithmetic unit 61 , the program memory 62 and the value memory 63 may each comprise one or more microelectronic components. Alternatively, these components may be partially or fully integrated in a single microelectronic device. In the program memory 61 or the value memory programs or values are stored, which are for the operation of the internal combustion engine VKM are necessary. In particular, a function FKT_DIAG _LF implemented for the diagnosis of the air filter during the stoppage of the internal combustion engine VKM is processed, as described by the description of the 2 will be explained in more detail. In the value memory 63 is, inter alia, a reference pressure value REF P for the electric compressor 19 in the case of a non-polluted or clogged air filter 11 can be generated superimposed boost pressure, whose meaning also still based on the description of 2 is explained in more detail.

Further, in the control device 6 a time counter 66 (Timer) and a fault memory 64 for storing and evaluating various diagnostic results, in particular results of the function FKT_DIAG_LF for diagnosis of the air filter 11 intended. Negative diagnostic results can be the driver of the internal combustion engine VKM driven vehicle in addition to the storage in the fault memory 64 also acoustically and / or optically with the help of a preferably arranged in the instrument cluster of the vehicle error display device 65 be transmitted.

The following is based on the 2 in the form of a flow chart, the procedure for the diagnosis of the air filter 11 explained.

In one step S0 becomes the function FKT_DIAG_LF for determining the degree of soiling of an air filter of the internal combustion engine VKM started, in which, if necessary, variables are initialized and counter readings are reset.

In one step S1 is queried whether the internal combustion engine VKM is off. This state can be detected by one of the known methods, for example by evaluating signals of an ignition starter lock or state of a start-stop button or by evaluating signals within the internal combustion engine VKM controlling and / or regulating control device 6 respectively.

The query in step S1 if necessary after a short waiting period T_WAIT repeated until the query gives a positive result, so the internal combustion engine VKM not in operation.

Subsequently, in the step S2 by means of control signals of the control device 6 the throttle 12 completely closed. Indicates the internal combustion engine VKM a secondary air line 193 on, so this is also by controlling the existing in this line secondary air valve 194 completely closed. Is in addition still an exhaust gas recirculation line 196 This is also present by controlling the exhaust gas recirculation valve present in this line 196 completely closed. At the same time the two diverting air valves 182 . 192 in the bypasses of the two compressors 18 . 19 by means of control signals of the control device 6 open.

Are the above valves 182 . 192 . 193 . 196 and the throttle 12 in the described switching states, so in a subsequent step S3 the electric one driven compressors 19 switched on. This creates a pressure p in the hermetically sealed intake tract 1 built up. Simultaneously with the activation of the electrically driven compressor 19 becomes the time counter 66 started.

During a given time interval, the resulting pressure p in the intake tract 1 by means of the pressure sensor 17 continuously recorded and to the control device 6 forwarded. In the illustration according to the 1 is the pressure sensor 17 in the intake tract 1 between the throttle 12 and the electrically driven compressor 19 arranged, but it is also possible that this pressure sensor 17 in another place in the exhaust gas department 4 between the throttle 12 and the air filter 11 is installed.

In one step S5 a query is made as to whether the predetermined time interval has expired. If this is the case, then in a subsequent step S6 the electric compressor 19 turned off and the now present value of the pressure p in one step S7 with a reference pressure value REF_P compared. This reference pressure value REF_P becomes experimental for a given air filter 11 determined with known degree of separation and is in the value memory 63 the control device 6 stored.

If the pressure value p exceeds the reference pressure value REF P , so in one step S8 on a clogged air filter 11 recognized. The opposite to the reference pressure value REF_P higher pressure may be caused by clogging due to long-term intake of very dusty air or the air filter may be clogged by ice formation due to extreme low outside air temperature.

As a clogged or iced air filter 11 has no or at least a very limited cleaning effect and also the performance of the internal combustion engine VKM decreases, or the fuel consumption increases, takes place in one step S10 an entry in the error memory 64 , Optionally also an error indicator 65 be activated for the driver of the vehicle, which should cause him, before the date of the next workshop inspection the air filter 11 to swap or exchange.

Returns the query in step S7 in that the pressure value p is below the reference pressure value REF_P lies, so will in one step S9 found that the air filter 11 in terms of its flowability in order. In one step S11 the process is finished.

LIST OF REFERENCE NUMBERS

1

intake system

11

air filter

12

throttle

13

suction tube

14

Air flow sensor

15

Temperature sensor for intake air

16

intake manifold pressure sensor

17

pressure sensor

18

compressor

19

electrically driven compressor

181

bypass line

182

Diverter valve

191

bypass line

192

Diverter valve

193

Secondary air line

194

Secondary air valve

195

Exhaust gas recirculation line

196

Exhaust gas recirculation valve

2

block

21

crankshaft

22

Crank angle sensor

24

piston

25

connecting rod

26

Coolant temperature sensor

27

combustion chamber

28

cylinder

3

cylinder head

30

Gas inlet valve

31

gas outlet

34

Fuel injection valve

35

spark plug

4

exhaust tract

40

catalytic converter

41

particulate Filter

42

Exhaust probe, lambda probe

43

Turbine, turbocharger

44

Bypass line, wastegate

45

bypass valve

6

control device

61

Arithmetic unit, processor

62

program memory

63

Value memory, data memory

64

error memory

65

Error display device

66

Time counter, timer

VKM

Internal combustion engine

FKT_DIAG_LF

Function for checking the air filter

P

pressure value

REF_P

Reference pressure value

Claims (8)

Method for determining the degree of soiling of an air filter (11) arranged in an intake tract (1) of an internal combustion engine (VKM) upstream of an electrically driven compressor (19), characterized by the following steps: a) determining whether the internal combustion engine (VKM) is in an off state b) closing a in the intake tract (1) downstream of the electrically driven compressor (19) arranged throttle valve (11) and closing all other, from the intake tract (1) to an exhaust tract (4) of the internal combustion engine (VKM) leading the internal combustion engine bypassing the bypass line (193, 195) if the internal combustion engine (VKM) is in an off state, c) turning on the electrically driven compressor (19) to build up pressure in the intake tract (1), d) detecting the pressure build - up over time in the intake tract (1) between the throttle valve (12) u e) comparing the time pressure build-up behavior with a predetermined time pressure build-up behavior and f) determining the degree of soiling of the air filter (11) on the basis of the result of the comparison in step e). Method according to Claim 1 , characterized in that one of the intake tract (1) to the exhaust tract (4) leading secondary air line (193) is closed. Method according to Claim 1 or 2 , characterized in that one of the exhaust tract (1) to the intake tract (4) leading exhaust gas recirculation line (195) is closed. Method according to Claim 1 , characterized in that a bypass line (191) which bypasses the electrically driven compressor (19) is opened. Method according to Claim 1 , characterized in that a bypass line (181) of a in the intake tract (1) of the internal combustion engine (VKM) arranged compressor (18) of an exhaust gas turbocharger is opened. Method according to one of the preceding claims, characterized in that in step c) a time counter (66) is started and after a predetermined period of time in the intake tract (1) prevailing pressure value (p) with a predetermined reference pressure value (REF_p) is compared and at Exceeding this reference pressure value (REF_p) is detected on a clogged or iced air filter (11), otherwise the air filter (11) is classified as functioning properly Method according to Claim 6 , characterized in that when the reference pressure value (REF_p) is exceeded, a corresponding error entry into an error memory (64) of a control device (6) controlling and / or regulating the internal combustion engine (VKM) takes place. Device for determining the degree of soiling of an air filter (11) arranged in an intake tract (1) of an internal combustion engine (VKM) upstream of an electrically driven compressor (19), which is designed to carry out a method according to one of Claims 1 - 7 ,

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