DE10358462A1 - Determining degree of fouling of air filter unit for internal combustion engine, by using boost-pressure sensor to measure pressure of filtered air before entering combustion chamber - Google Patents

Abstract

The method involves using a boost-pressure sensor (4) to determine the pressure of the filtered air in at least one idle phase of the engine (2), after it has passed through a compressor unit (7) and before it flows into a combustion chamber of the engine. When an operating current for the engine is switched on, the ambient pressure from an ambient pressure sensor (3) is compared with the boost-pressure from the boost-pressure sensor. An independent claim is included for an apparatus for determining the degree of fouling of an air filter unit.

Description

The The invention relates to a device and a method for determining a degree of contamination of an air filter unit for cleaning of air, that of an internal combustion engine, in particular of a Automotive internal combustion engine, is sucked, in which an atmospheric pressure and a pressure of the filtered air detected from the atmospheric pressure and the pressure of the filtered air determines a pressure difference and in which in an evaluation unit of the degree of pollution under Based on a comparison between the determined pressure difference and a pollution-specific reference pressure difference becomes.

The Contains ambient air a variety of impurities that are an internal combustion engine sometimes cause considerable damage can. For this reason, dispose For example, motor vehicles via Air filters, which are the for the combustion in the engine needed Clean the air. At the air filter here are two main requirements posed. On the one hand, the intake air should be cleaned without the air passage essential is hampered. On the other hand, the air filter should be designed in this way be that the sometimes very strong intake noise of the air are effectively attenuated.

Depending on the landscape, soil and road conditions or intended use of a vehicle, the amount of dust contained in the ambient air varies between 0.001 and 1 g / m ³ [Bohner, M. et al. ; Expertise Automotive Technology; 25th edition; 1994; Publisher Europa-Lehrmittel; P. 250]. Dust that enters the engine via the intake air forms, with the lubricating oil of the engine, a grinding mass that can lead to considerable wear, especially on cylinder liners, pistons and valve guides. Careful cleaning of the intake air therefore significantly determines the life of an engine.

at the known filter systems is the dust entrained by the intake air by means of close-meshed sieves, narrow-pored filter cloths, oil-wetted surfaces or filtered out of the air using the centrifugal force in the filter. This pollutes the filter material contained in the filter sometimes considerably. If a filter is not renewed in time or cleaned, the flow resistance increases of the filter and it gets less air than needed in the engine, so that ultimately a richer fuel-air mixture, a worse filling as well a lower engine power resulting from a filter contamination can be.

For this reason, systems are known with which the degree of contamination of an air filter can be determined. The DE 197 10 981 A1 describes, for example, a method for determining the degree of contamination of a provided in the intake of an internal combustion engine, in particular a motor vehicle air filter. The pressure difference between the inlet and the outlet and thus the flow resistance of the air filter, which is a measure of the degree of contamination of the filter is determined from the atmospheric pressure before the air filter and the pressure prevailing in the intake manifold directly behind the air filter pressure. In the device described in this document is thus the degree of contamination of an air filter with the help of a non-arranged in the intake manifold ambient pressure sensor, which is needed for the operation of an air conditioner or for the height correction of the injection quantity on the engine, and with a pressure sensor for regulating the injection quantity is provided in dependence on the boost pressure in the intake manifold, determined.

outgoing from the known prior art, the invention has the object as a basis, a method and a device for determining the Specify the degree of contamination of an air filter, in which in the area of the suction pipe directly behind the filter no mounting place for one Sensor must be provided. The desired solution should over it also inexpensive be and in particular also used in internal combustion engines with turbocharging could be.

The The object underlying the invention is achieved with a method according to claim 1 or a device according to claim 7 solved. Advantageous developments of the inventive concept are the subject of the dependent claims and the following description text with reference to the embodiment refer to.

According to the invention, a method for determining a degree of soiling of an air filter unit for purifying air sucked by an internal combustion engine, in particular an automotive internal combustion engine, in which an atmospheric pressure and a pressure of the filtered air are detected, from the atmospheric pressure and the pressure of the filtered Air determines a pressure difference and in which in an evaluation of the pollution degree Ver on the basis of a comparison between the determined pressure difference and a pollution-specific reference pressure difference is determined, further developed such that in at least one idling phase of the internal combustion engine, the pressure of the filtered air after flowing through a compressor unit and before at least partial inflow into at least one combustion chamber of the internal combustion engine as boost pressure is detected with a boost pressure sensor.

The inventive system is characterized by the fact that the monitoring of the degree of pollution an air filter using an ambient pressure and a boost pressure sensor takes place. Both sensors are particularly useful in conventional diesel engines, such as they are used in the commercial vehicle sector already exists. So the ambient pressure sensor realizes the height adjustment for the engine, while the boost pressure sensor for the regulation of the pressure of the intake air of the internal combustion engine required is. In this way, even with diesel engines with turbocharging a reliable monitoring the degree of contamination of an air filter can be ensured without that for this additional Sensors or additional Mounting space in the region of the suction pipe behind the air filter are needed.

The Pollution-specific reference pressure values are preferably already in the run-up to a standard use the air filter on a test stand and / or during test drives determined. In such experiments are for different levels of pollution an air filter determines the flow resistance, which has the filter at the corresponding pollution.

The Measurement of the ambient pressure and the charge pressure takes place while the system is running Engine. For the determination of the between the inlet and the outlet However, the differential pressure prevailing in the air filter only becomes Takes into account values of the ambient pressure or the charge pressure, the while an idle phase of the internal combustion engine have been recorded. Flowed through at idling the filtered air the compressor unit without being compacted so that the boost pressure sensor in this Beriebszustand the intake vacuum relative to ambient pressure.

In a particular embodiment the method according to the invention the measured values recorded by the ambient and boost pressure sensor are adjusted, as soon as the for the operation of the internal combustion engine required operating current is turned on. As a rule, this switching on of the operating current is carried out by Turn the ignition key. Preferably in this case both measured values set to zero, so while the operation of the internal combustion engine a difference of the detected pressures relatively easy is to be made and measurement error be excluded from zero drift.

A Further training provides that the degree of contamination of the air filter to a central control and control unit, in particular a vehicle computer, transmitted becomes. For this reason, those of the ambient pressure sensor or The measured values acquired by the boost pressure sensor are first converted into electrical signals converted over a data line, such as a CAN or a VAN bus, the other Data processing available be put. Preferably, the pressure sensors have data interfaces up, over the corresponding measuring signals be fed into the data line and so a networking of Pressure sensors with at least one control unit is made possible. Here it is irrelevant how the controller, in particular a vehicle computer, arranged relative to the pressure sensors is.

A further, special embodiment the method according to the invention provides that corresponding to certain levels of contamination Difterential pressure values also in the central control unit be deposited. Preferably, at the same time, a contamination characteristic value is also obtained deposited, which sets a limit for just permissible pollution represents an air filter. In this context it is advantageous when transmitted to the central control unit Pollution degree with the permissible Pollution index is compared and as soon as the pollution degree exceeds the permissible contamination index generates a corresponding electrical warning signal and to a Transfer output unit becomes. Since the pollution usually increases continuously, are / on the one hand Forecasts for the change date possible for other plausibility checks Meßwertsprüngen.

Preferably the output unit generates an acoustic, visual and / or haptic warning signal, for example, by a driver during the Drive is noticeable. However, it is also conceivable that simultaneously or alternatively a corresponding warning in a Data storage is deposited, the at an inspection of the internal combustion engine and / or a vehicle using an external diagnostic system, in a workshop, for example.

In In any case, it makes sense that the warning signal is generated before the final Capacity of the Filter is reached to absorb dirt. Much more the warning signal should be generated at a time when still ensures a sufficiently long service life of the vehicle is without causing damage the engine is coming. In this preferred way, a consumption-based or pollution-independent Changing the air filter or the air filter cartridge possible.

Furthermore, the object of the invention is based on a device for determining a degree of contamination of an air filter in accordance with the preamble of patent claim 7, which is characterized in that the pressure sensor is designed as a boost pressure sensor, with which the charge pressure which the filtered air has after flowing through a compressor unit and before at least partial inflow into at least one combustion chamber of the internal combustion engine.

In a particular embodiment the device according to the invention an input unit is provided, via which at least one permissible contamination characteristic value can be entered into the evaluation unit.

Farther has the evaluation unit preferably via at least one data interface, via the the degree of contamination and / or exceeding a permissible contamination index a warning signal to a central control and control unit, in particular a vehicle computer, and / or transferable to an external data processing unit is. A particularly suitable embodiment further provides that the evaluation unit into a central control unit, in particular a vehicle computer, is integrated.

in the The invention will be described below with reference to an embodiment without limitation of the general In the spirit of the invention described with reference to the figure.

figure flowsheet the intake air and the exhaust gases of an internal combustion engine

The figure shows schematically the use of a device for determining the degree of contamination of an air filter unit 1 for an internal combustion engine 2 a commercial vehicle, which consists of an ambient pressure sensor 3 and a boost pressure sensor 4 is formed. Both with the ambient pressure sensor 3 as well as the boost pressure sensor 4 These are sensors that are needed at the same time to implement additional functions in the vehicle.

The ones for combustion in the engine 2 required air is through a suction 5 sucked from the environment. The air here has the ambient pressure p _amb . The sucked fresh air first flows through an air filter 1 in which it is cleaned, in the suction line 18 , Subsequently, the cleaned fresh air through the designed as a so-called exhaust gas turbocharger compressor unit 7 via pressure line 6 , Exhaust gas recirculation control valve 8th and air distributor 9 the internal combustion engine 2 fed. The exhaust gas recirculation control valve (Dossel flap) 8th is additionally via an exhaust gas recirculation line 20 with the manifold 10 connected.

The exhaust gas flow of the internal combustion engine 2 is via the manifold 10 to the turbine 11 the compressor unit 7 and to the muffler 12 the exhaust system 13 directed. To the compression in the compressor unit to the requirements of the engine 2 adjust, the boost pressure, with which the air is the engine 2 is supplied, regulated. About that in the exhaust system 13 provided, designed as a bypass valve boost pressure valve 14 the boost pressure is regulated by a data line 15 the measured values to the vehicle computer 16 be transferred and depending on the supercharging pressure, the boost pressure valve 14 is opened. When opening the charge pressure valve 14 Part of the exhaust gas flow bypasses the turbine 11 directly to the muffler 12 ,

In order to detect the respective charge pressure is in the flow direction of the air behind the compressor unit 7 a boost pressure sensor 4 provided that detects a measured value for the boost pressure and to a vehicle computer 16 forwards. For engine control takes place in the vehicle computer 16 finally, a data processing of the boost pressure values. Depending on the operating state of the internal combustion engine is also the pressure relief valve 19 controlled in order to be able to regulate the amount of air to be compressed in this way.

In addition, the ambient pressure sensor detects 3 during operation of the internal combustion engine 2 the ambient pressure p _amb to in the vehicle _computer 16 to make a height adjustment for the engine control.

To with the help of the ambient pressure sensor 3 and the boost pressure sensor 4 the degree of contamination of the air filter 1 be detected when starting the engine 2 from the ambient 3 as well as the boost pressure sensor 4 recorded measured values to a in the vehicle computer 16 integrated evaluation unit 20 transmitted and adjusted by first setting both measured values to zero. As soon as the engine 2 is in an idling phase, the engine 2 So is not charged with a load, the intake air of the engine 2 in the compressor unit 7 not compacted. A pressure difference arising in this operating condition of the engine 2 between adjusts the ambient pressure and the boost pressure is due solely to flow resistance of the intake before the boost pressure sensor 4 due. Since the pipe friction losses in the intake pipe compared to the flow resistance of the air filter 1 are negligible, the measured pressure difference between the ambient pressure and the boost pressure corresponds to the flow resistance of the air filter 1 ,

For determining the degree of soiling of the air filter 1 , in the idling phase of the internal combustion engine, the 3 and boost pressure sensor detected pressure difference between ambient and boost pressure measured and the measured value to the in the vehicle computer 16 integrated evaluation unit 20 forwarded. In the evaluation unit 20 or in the vehicle computer 16 Reference data are stored, each on the air filter 1 adjoining pressure difference to a degree of contamination. In this way with the evaluation unit 20 in the vehicle computer 16 determined pollution level is the driver in a vehicle display 17 displayed and / or read during the inspection of the vehicle in a workshop with an external data processing unit from the vehicle computer. Exceeds the degree of contamination of the air filter 1 between the inspections a permissible value, this is the driver in the vehicle display 17 displayed. The limit for the permissible degree of contamination of the air filter 1 In any case, it will be chosen so that even after the air filter is displayed 1 or the air filter cartridge must be changed, an operation of the engine 2 is possible for a certain amount of time without causing engine damage.

Of course it is It is also conceivable in this context that an impermissible degree of pollution already during the operation of a vehicle automatically forwarded to a workshop so that appropriate replacement parts can be prepared in good time can.

The above-described detection of the degree of contamination of the air filter 1 based on the detection of the air filter 1 applied pressure difference with anyway required for the operation of the vehicle sensors. This highly relevant for the operation of an internal combustion engine measurement is very reliable and without that in the range of the intake manifold in this way 18 that attach to the air filter 1 Connects a sensor element must be provided carried out.

1

air filter

2

internal combustion engine

3

Atmospheric pressure sensor

4

Boost pressure sensor

5

suction

6

pressure line

7

compressor unit

8th

Exhaust gas recirculation control valve (Throttle)

9

air distributor

10

manifold

11

turbine

12

silencer

13

exhaust system

14

Boost Valve

15

data line

16

vehicle computer

17

vehicle display

18

suction tube

19

Pressure relief valve

20

Exhaust gas recirculation line

Claims (12)

Method for determining a degree of soiling of an air filter unit ( 1 ) for the purification of air from an internal combustion engine ( 2 ), in particular by a motor vehicle internal combustion engine is sucked, in which detects an atmospheric pressure and a pressure of the filtered air, from the atmospheric pressure and the pressure of the filtered air determines a pressure difference and in which in an evaluation unit ( 20 ) the degree of contamination is determined on the basis of a comparison between the determined pressure difference and a pollution-specific reference pressure difference, characterized in that in at least one idling phase of the internal combustion engine ( 2 ) the pressure of the filtered air after flowing through a compressor unit ( 7 ) and before an at least partial inflow into at least one combustion chamber of the internal combustion engine ( 2 ) as boost pressure with a boost pressure sensor ( 4 ) is detected. A method according to claim 1, characterized in that when switching an operating current of the internal combustion engine ( 2 ) of an ambient pressure sensor ( 3 ) and ambient pressure from the boost pressure sensor ( 4 ) detected boost pressure to be adjusted. A method according to claim 1 or 2, characterized in that the degree of contamination to a central control and control unit ( 16 ), in particular a vehicle computer, is transmitted. A method according to claim 3, characterized in that the degree of contamination in the central control and control unit ( 16 ) is compared with a permissible contamination characteristic value and as soon as the degree of contamination exceeds the permissible contamination characteristic value a signal to an output unit ( 17 ) is transmitted. Method according to claim 4, characterized in that the output unit ( 17 ) generates an acoustic, visual and / or haptic warning signal. A method according to claim 4 or 5, characterized in that the degree of contamination and / or the exceeding of the contamination characteristic value to an external data processing is transferred. Device for determining a degree of contamination of an air filter unit ( 1 ) for the purification of air from an internal combustion engine ( 2 ), in particular of a motor vehicle internal combustion engine is sucked, with a sensor unit, which via an ambient pressure sensor ( 3 ), with which an atmospheric pressure can be detected and via a pressure sensor ( 4 ), with which the pressure of the filtered air behind the air filter unit ( 1 ) and has an evaluation unit ( 20 ), in which from the atmospheric pressure and the pressure of the filtered air, a pressure difference can be determined and on the basis of a comparison between the pressure difference and a pollution-specific reference pressure difference, the degree of contamination can be determined, characterized in that the pressure sensor ( 4 ) as a boost pressure sensor, with which the boost pressure, the filtered air after flowing through a compressor unit ( 7 ) and at least partially inflow into at least one combustion chamber of the internal combustion engine ( 2 ) is executed. Apparatus according to claim 7, characterized in that an input unit is provided, via which at least one permissible contamination characteristic value in the evaluation unit ( 20 ) can be entered. Apparatus according to claim 7 or 8, characterized in that the evaluation unit ( 20 ) has at least one data interface. Apparatus according to claim 8 or 9, characterized in that at least one output unit ( 17 ) is provided, with the basis of the pollution index and the degree of contamination, a signal is generated as soon as the degree of pollution assumes a higher value than the contamination index. Apparatus according to claim 9, characterized in that the evaluation unit ( 20 ) has at least one data interface via which the degree of contamination and / or the signal to a central control and control unit ( 16 ), in particular a vehicle computer, and / or can be transmitted to an external data processing unit. Device according to one of claims 7 to 11, characterized in that the evaluation unit ( 20 ) into a central control and control unit ( 16 ), in particular a vehicle computer, is integrated.