DE102009013142A1 - Crankshaft's uneven running determining method for internal combustion engine of vehicle drive of car, involves evaluating speed of crankshaft, and evaluating periodic time of variations of speed of crankshaft - Google Patents

Abstract

The method involves evaluating speed of a crankshaft (5), and evaluating periodic time of variations of speed of the crankshaft. Amplitude of variations of the speed of the crankshaft is evaluated, and a half periodic time between two extremes of maximum and minimum variations of the speed. Ignition failure is detected. A number at an intermediate storage (16) is added to a value stored in a misfire counter (17) during detection of the ignition failure at a viewing time space. A value of the intermediate storage is rejected during detection of drive train oscillations. An independent claim is also included for a device for detecting and signaling ignition failure of an internal combustion engine.

Description

The The invention relates to a method for distinguishing misfiring or caused by driveline oscillations Laufunruhe one Crankshaft of an internal combustion engine, wherein the speed of the crankshaft is evaluated.

The The invention further relates to a device directed thereto.

Modern internal combustion engines are monitored for misfiring. For example, due to legal requirements in the context of the OBD on-board diagnosis, such misfire monitoring is provided and a monitoring result from a fault memory of the engine control unit can be read out. Usually this is a donor of a tachometer, which is non-rotatably connected to a crankshaft of the internal combustion engine, divided into so-called segments, wherein the size of the segments of the number of degrees for a working process divided by the number of cylinders corresponds, in a four-stroke engine so 720 ° / number of cylinders. Each of these segments is assigned the expansion / working phase of a particular cylinder, that is, the period of time during which the cylinder delivers and drives work to the crankshaft. For the detection of misfires now the time is measured, which passes until such a segment has passed the speed sensor. The time required for this is compared with a stored average time and formed from the deviation of a rough running or a rough running value. If a cylinder has a misfire, it will not deliver power to the crankshaft during its expansion phase and the segment time will be extended. This is evident in the so-recognized uneven running. This is compared with a threshold value, and when the threshold value is exceeded, a misfire is counted. These misfires are summed over a certain number of crankshaft revolutions (so-called totalizer). If during this number of crankshaft revolutions a certain number of misfires is exceeded (predefinable threshold for the totalizer), an error memory entry in the engine control unit and / or a warning display for the driver takes place. Such methods are for example from DE 196 27 540 . DE 41 18 580 and the DE 199 45 811 known. A disadvantage of this method is that in engines with higher engine power, especially in conjunction with manual transmissions, increasingly stronger or stiffer clutches are used in which rapid engagement processes stimulate the entire drive train and / or essential parts thereof, such as the dual mass flywheel, to vibrate. In particular, drive trains of rear or all-wheel drive vehicles are particularly susceptible to this because of the large mass of their drive trains. These vibrations are detected by the speed sensor and incorrectly counted as a misfire due to the thus caused increased uneven running, which exceeds the predetermined threshold for the relevant uneven running. This leads to an unprompted counting up of the misfire counter. This leads to an unnecessary and undesirable erroneous response of an error message and the incorrect storage of misfires in the error memory of the controller.

task the invention is to provide a method and a device, the on due to driveline vibrations caused uneven running Crankshaft down tests for an erroneous entry of misfires to avoid in a multi-error memory of the engine control unit.

According to the invention this task by means of a method for the distinction of misfiring or caused by driveline oscillations Laufunruhe one Crankshaft of an internal combustion engine solved, the Speed of the crankshaft is evaluated. It is provided that the period T of fluctuations in the speed of the crankshaft is evaluated for the distinction. This evaluation makes use of the fact that uneven running caused by misfiring is caused by a relatively short period T, whereas the period T of a drive train vibration much longer is. Further, the period T of such rough running, the caused by misfiring, of the speed (namely the ignition frequency).

In an equally suitable training for distinction from misfires or driveline vibrations caused uneven running of a crankshaft of an internal combustion engine, wherein the rotational speed of the crankshaft is evaluated, for example As described above, it is provided that the amplitude A of fluctuations in the speed of the crankshaft for differentiation is evaluated. The rough running, as caused by misfiring is caused differs also in their amplitude A of such rough running, as caused by driveline vibrations. The amplitude A of a rough running caused by misfiring is relatively small, whereas the amplitude A of a rough running, such as It is caused by driveline vibrations, relatively large and is non-uniform. Especially after a coupling the amplitude A is quite high, to decrease on it.

In a preferred embodiment it is provided that the method is used in internal combustion engines of vehicle drives. Vehicle drives, especially those of power Vehicles, ie cars or commercial vehicles, are subject to strict legal regulations with regard to their emissions, which is why misfiring must be monitored. Especially here, the undesired entry of incorrect misfire identifications in the error memory can be avoided in a very advantageous manner. This saves on customer complaints, workshop stays that have no real causes, as well as recalls, which are prescribed for a model in some markets after a certain number of cases.

In In a method training, the period T is determined such that that half a period T / 2 between two extremes, about a consecutive Maximum and a minimum, the fluctuations of the speed is determined. A determination of the period T is due to the nonuniformity the unrest difficult, since a determination of the passage through the middle position of the resulting oscillation is mathematically problematic is because the middle layer is unknown. Therefore, each half Period T / 2 between a maximum and a minimum or redirected, ie between two extremes of the course of the Uneven running. These extremes are mathematically very easy to determine namely where the first derivative of the speed dn / dt has its zero crossing. This can be done by doubling half the period T / 2 determine the period T.

In In another embodiment of the method, the amplitude A of the fluctuations becomes the speed determined so that the speed difference between a maximum and a minimum or vice versa. The amplitude A of the speed fluctuations is therefore as a speed difference between a maximum and a minimum of the speed fluctuations determined, with the determination of minimum and maximum as explained above by finding the zero crossing of the first derivative of the speed dn / dt takes place.

• a) Die Abweichung der Periodendauern T untereinander sind kleiner als eine vorgebbare Schwelle;
• b) die Amplituden A sind über die Zeit fallend;
• c) die erste und/oder die erste und zweite Amplitude A liegt/liegen oberhalb eines vorgebbaren Schwellwertes;
• d) die mittlere Amplitude A und die mittlere Periodendauer T liegen jeweils oberhalb vorgebbarer Grenzwerte.

In a preferred method training, driveline vibrations are detected if, within a predefinable observation period, the following criteria are fulfilled for differentiation:

• a) The deviation of the periods T among themselves are smaller than a predefinable threshold;
• b) the amplitudes A are decreasing over time;
• c) the first and / or the first and second amplitudes A are / are above a predefinable threshold value;
• d) the average amplitude A and the average period T are in each case above predefinable limit values.

This Process step describes the preparation of the amplitude A and Period T, which determines as explained above their verification and assessment of a given Period, with the observation period not only being Time specification, but also as a default of a certain number can be done by crankshaft revolutions. Here, it is decisive that considers a certain number of crankshaft revolutions can be. The criterion a), namely deviations of Periods T are smaller than a predefinable threshold, resulting from the observation that powertrain vibrations in terms of their Periods are quite regular, so between the individual period lengths T, which were determined as described above, no significant differences are recorded. The criterion b) according to which the amplitudes A are decreasing over time, takes into account the fact that a drivetrain vibration after an excitation, for example by engaging, and over the time dies out. Have the amplitudes of such vibrations as envelope (envelope) typically one exponential function. For a very short period of observation, it is possible that the amplitudes A according to criterion b) have a constant or have approximately the same value; for this reason the period under consideration should not be too short. Criterion c), according to which the first and / or the first and second amplitudes A is above a predetermined threshold or lie, carries different operating conditions the internal combustion engine bill, after which the amplitudes A only then be recognized as a drive train vibration, if they have a have a certain minimum size. Criterion d), according to which average amplitude A and average period T each above given limits, also carries different Operating conditions of the internal combustion engine bill, taking into account is that the drivetrain vibrations a much longer Period duration and have a significantly higher amplitude A. as such, riots due to misfiring are.

In a preferred embodiment of the method considered the predefinable threshold and / or the predetermined limit Characteristic map of the internal combustion engine over speed and load. This takes into account the fact that at high speed the internal combustion engine and the frequency of misfires is high, whereas it is low at low speed.

In a further process training detected misfires are detected in a misfire counter. Consequently, if, as described above, misfires are detected, such misfires are registered in the misfire counter; For example, per registered misfire, the misfire counter is incremented by one. Of course, here are other design sizes and intervals possible. The misfire counter can in this case be provided with a predefinable threshold, for example by data transmission, upon reaching an error message issued and / or an error entry is set in the engine control unit.

In a preferred method training is the number recognized possible misfiring / Laufunruhen in a cache read in until a sufficiently reliable distinction is made could, whether a detected uneven running of the crankshaft on a misfire or due to driveline vibration is. As a result, a certain amount of suspicion is acted upon detected running turmoil be recorded in the cache, and such recognized run disorder as described above with respect to to the period T and / or amplitude A are evaluated. In particular, it is possible to refer to a specific predefinable number of crankshaft revolutions and / or recognized To review riots for relevance assessment.

In Another, preferred method training is in recognition misfiring during the period under consideration in the cache stored number of the stored in the misfire counter Added value. As a result, gives the test for amplitude A and / or period T, that is actually misfiring So the unruliness is not driveline vibrations caused, are the registered in the buffer dropouts added to the misfire counter because it is considered significant were detected.

Vice versa it is provided in a procedural training that in recognizing of driveline oscillations in the period under consideration the value of the cache is discarded. Is therefore due to of recognized running turmoil over a period of observation a number of such detected disturbances in the cache, and will based on the evaluation according to amplitude A and / or period T found that the rough running actually does not occur Misfiring, but are due to driveline vibrations, the value stored in the buffer (the number of Recognized running turmoil in the period under consideration or part of such) discarded, so not added to the misfire counter. On This way is very beneficial in avoiding that not on misfiring, but on powertrain vibrations based riots on false entries in the misfire counter to lead.

Further a device is proposed for detection and signaling misfiring an internal combustion engine, at the one Speed sensor is connected, which has a speed and a running noise a crankshaft of the internal combustion engine monitors, and wherein a detected uneven running in a misfire counter is stored. It is envisaged that a cache for Storage of still to be distinguished in a period of observation Run riots after misfires or driveline vibrations upstream of the misfire counter. Be detected runaways therefore not immediately written to the misfire counter, especially, as long as it is not clear whether such a rough running actually misfiring or yet on powertrain vibrations is due, but in the misfire counter upstream buffer. Therein the value of the recognized Running turmoil is incremented, as long as in the period under review such unrest be recognized further. The value stored in the cache during the viewing period is reached is discarded if the criteria as above described for the detection of driveline vibrations available. If only one of the criteria is not available, it is assumed that that it is actually due to misfiring caused run riots, with the result that in the cache stored value in the period of observation the misfire counter is added.

In A preferred embodiment is the misfire counter preceded by several intermediate storage. This makes it possible in multiple buffers independently parallel or sequentially to record running turmoil, with several (also different long) observation periods independently can be chosen to, for example, after Resetting an error to misfiring, that is, when running noise due to driveline vibrations is detected, in another buffer for verifying this result another observation period also examinations to make driveline vibrations and / or misfires. In particular, it is possible here, the latches mutually according to criteria to be selected, for example recognized as exceeding a certain threshold, possible misfires, to initialize to to start a new check interval. The accuracy of the overall system can be very advantageous in this way be improved.

Further advantageous embodiments will become apparent from the dependent claims and combinations thereof.

The Invention will be described below with reference to an embodiment explained in more detail, but without limitation to be.

It demonstrate

1 a device for detecting and signaling misfiring of an internal combustion engine;

2 a schematic representation of the misfire detection on a rough running over a period of observation;

3 a representation of the difference of amplitudes A and period T of misfires and driveline vibrations and

4 the determination of the period T and the amplitude A during operation of the device.

1 shows an internal combustion engine 1 for a motor vehicle, not shown. The internal combustion engine 1 has four cylinders 2 on, in a row of cylinders 3 are arranged; in the internal combustion engine is therefore a four-cylinder inline engine 4 , The internal combustion engine 1 has a crankshaft 5 on, in a known manner with in the cylinders 2 guided piston is operatively connected via connecting rods, not shown. The crankshaft 5 has an end here an example and schematically illustrated encoder wheel 6 on top of that, from a sensor 7 as a speed sensor 8th being scanned in its rotation, being on the sender wheel 6 arranged segments 9 that extend in extent over a circumference of the encoder wheel 6 the number of degrees for a work process divided by the number of cylinders 2 equivalent. The speed sensor 8th is a Mo torsteuergerät 10 via suitable electrical connections 11 that also have signal connections 12 such as a bus system 13 can be connected. The engine control unit 10 points to the evaluation of one of the speed sensor 8th supplied speed signal 14 an evaluation unit 15 on, a cache 16 and a misfire counter 17 is downstream. The misfire counter 17 acts with other control systems in the engine control unit 10 together, in particular a fault memory 18 , wherein for signaling error conditions, in particular misfiring of the internal combustion engine 1 or single cylinder 2 the internal combustion engine 1 , a signaling device 23 is downstream, which allows such signaling to a driver, not shown, of the vehicle. Misfiring of a cylinder 2 now lead to that on the crankshaft 5 during the expansion cycle of the suspending cylinder 2 no power is applied, so the rotation of the encoder wheel 6 in the corresponding segment 9 slightly lengthened, so it takes a marginal amount of time to get the associated segment 9 at the speed sensor 8th has moved past. This small temporal change can be considered a rough ride 19 from the evaluation unit 15 be recorded.

2 shows in a torn off over the time t in seconds diagram the rough running 19 as fluctuations in the speed n, which in the in 1 illustrated engine control unit 10 namely, the evaluation unit 15 , with a predefinable anti-roll threshold 20 is compared (as far as constructive features of the in 1 illustrated internal combustion engine 1 or such constructive features are mentioned, these are the 1 refer to). Misfiring of a cylinder 2 are in trouble 19 as a deviation of an actual time recognizable, which is a segment 9 the donor wheel 6 needed to for the corresponding cylinder 2 at the speed sensor 8th to rush by, compared to a mean time. From this comparison of the actually required time with the middle time becomes the uneven running 19 formed, the exact algorithm depending on the software used the engine control unit 10 can vary. In the running disorder 19 is such an extension of the segment time for the corresponding cylinder 2 recognizable. The rough running 19 comes with the running alarm threshold 20 on transgressions 21 tested (exemplified). Exceeds the rough running 19 the running alarm threshold 20 , so is a misfire value 22 increments. Exceeds the dropout value 22 during a predetermined observation period t _B a predeterminable maximum value n _max , so it is done via the signaling device 23 the signaling of a fault via the evaluation device 15 into the error memory 18 is registered. The misfire value 22 is preferably not directly in the misfire counter 17 of the engine control unit 10 a worn, but in a cache 16 , The values in the cache 16 can, as described below, their relevance to misfiring of individual cylinders 2 be checked before going into the skip counter 17 increasing the dropout value 22 be registered. In the cache 16 registered running riots 19 , so transgressions 21 of unrest 19 the running alarm threshold 20 , are from the evaluation device 15 or from the engine control unit 10 To check whether they are actually misfiring one or more cylinders 2 are due, or to others, the internal combustion engine 1 attributable circumstances, such as powertrain vibrations.

3 shows to distinguish whether rough running 19 the internal combustion engine 1 on misfiring of individual cylinders 2 or due to driveline vibrations, two graphs 24 , where a first graph 25 a rough ride 19.1 by misfiring and a second graph 26 a rough ride 19.2 by driveline oscillations in the time course of the rotational speed n, thus removed over the time t, shows. It becomes clear that the running mischief caused by misfiring 19.1 has a relatively small amplitude A and a relatively low period T _19.1 . The opposite is the rough running due to driveline vibrations 19.2 characterized in that it has a relatively long period T _19.2 and a relatively large amplitude A _19.2 , wherein the amplitude A _19.2 in the time course of rough running due to driveline vibrations 19.2 decreases; the envelope 27 the uneven running due to driveline vibrations 19.2 forms an e-function in the vast majority of cases. This makes it possible, uneven running 19 to distinguish in such Laufunruhen, by misfiring individual cylinders 2 the internal combustion engine 1 are caused, so in running troubles by misfiring 19.1 , and in for the misfire counter 17 non-relevant rough running due to driveline vibrations 19.2 ,

4 shows an example of a distinction in the evaluation 15 between running riots due to misfiring 19.1 and running riot due to driveline vibrations 19.2 (see 3 ) required determination of the amplitude A and the period T for running disturbances by driveline vibrations 19.2 , Shown is the rough running due to driveline vibrations 19.2 as well as the first derivative 28 the speed (dn / dt). To determine the period duration, a determination of a passage through a central position of the oscillation is generally required; this is with such uneven vibrations as occur as powertrain vibrations and the rough running due to driveline vibrations 19.2 training, very difficult, since just this middle position is unknown. Therefore, each half a period T / 2 between two extremes 31 , about a maximum 29 and a minimum 30 , the engine trouble due to driveline vibrations 19.2 that is, between two consecutive extremes 31 , The amplitude A then results as a speed difference between just these two extremes 31 , These extremes 31 are mathematically very easily determinable, namely where the first derivative 28 the speed (dn / dt) has its zero crossing. In the evaluation device 15 is now with respect to the periods T and amplitude A of the uneven running 19 Checks whether the deviations of the period T among each other are smaller than a predefinable threshold (driveline vibrations are very regular, the deviations therefore rather low); whether all amplitudes A are decreasing over time t (the amplitudes A of impulsive ripples due to driveline oscillations 19.2 assign as envelope / envelope 27 typically an e-function); whether a first and second amplitude A are above a predefinable threshold value (preferably taking into account the characteristic diagram over speed and load) and whether an average amplitude A and a mean period T lie above predefinable limit values (likewise preferably in the characteristic diagram via speed and load). If only one of these criteria is not available, to ensure a reliable misfire detection, not from powertrain vibrations, but from misfires that the rough running 19 cause and that in the cache 16 stored value in the misfire counter 17 transfer. If the criteria just described before, it is assumed that the rough running 19 a rough running due to driveline vibrations 19.2 is and not a rough running due to misfiring 19.1 so that's in the cache 16 stored value for the number of observed, relevant rotational nonuniformities (the uneven running 19 form) and not in the misfire counter 17 is transmitted. In this way it is possible to avoid an incorrect misfire count.

1

Internal combustion engine

2

cylinder

3

cylinder bank

4

Four-cylinder engine

5

crankshaft

6

sensor wheel

7

sensor

8th

Tachometer

9

segment

10

Engine control unit

11

electrical connection

12

signal connection

13

bus system

14

Speed signal

15

evaluation

16

cache

17

dropouts counter

18

error memory

19

runningirregularity

19.1

runningirregularity by misfiring

19.2

runningirregularity by driveline vibrations

20

Uneven running threshold

21

transgression

22

dropouts value

23

signaling device

24

graph

25

first graph

26

second graph

27

envelope

28

1. derivation

29

maximum

30

minimum

31

extremum

t

Time

t _B

The period

n _max

maximum value

A

amplitude

T

period

A _19.1

amplitude the rough running due to misfiring

A _19.2

amplitude the uneven running due to driveline vibrations

T _19.1

period the rough running due to misfiring

T _19.2

period the uneven running due to driveline vibrations

n

rotation speed

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 19627540 [0003]
• - DE 4118580 [0003]
• - DE 19945811 [0003]

Claims (13)

A method for distinguishing from misfires or by driveline vibrations caused turbulence of a crankshaft of an internal combustion engine, wherein the rotational speed of the crankshaft is evaluated, characterized in that the period T of fluctuations in the rotational speed of the crankshaft for the distinction is evaluated. Method of distinguishing from misfiring or caused by driveline oscillations Laufunruhe one Crankshaft of an internal combustion engine, wherein the speed of the crankshaft is evaluated, in particular according to claim 1, characterized that the amplitude A of fluctuations in the speed of the crankshaft is evaluated for the distinction. Method according to one of the preceding claims, characterized in that it is in internal combustion engines of vehicles is evaluated. Method according to one of the preceding claims, characterized in that the period T determined in such a way is that half a period T / 2 between two extremes, about a successive maximum and a minimum, the fluctuations the speed is determined. Method according to one of the preceding claims, characterized in that the amplitude A of the variations of Speed is determined so that the speed difference between a Maximum and a minimum or vice versa. Method according to one of the preceding claims, characterized in that detected on powertrain vibrations if differentiated within a predefined period of observation the following criteria are fulfilled: a) the deviations the periods T among each other are smaller than a predetermined Threshold; b) the amplitudes A are decreasing over time; c) the first and / or the first and second amplitudes A lie / lie above a predefinable threshold value; d) the mean amplitude A and the average period T are each above specifiable Limits. Method according to one of the preceding claims, characterized in that the predetermined threshold and / or the definable limit value a map of the internal combustion engine via Speed and load were taken into account. Method according to one of the preceding claims, characterized in that recognized in a misfire counter Misfires are detected. Method according to one of the preceding claims, characterized in that until the discrimination as to whether a recognized Turbulence of the crankshaft on a misfire or due to a driveline vibration is the number of possible misfires detected be read into a buffer. Method according to one of the preceding claims, characterized in that upon detection for misfiring in the observation period, the number in the buffer in the misfire counter stored value is added. Method according to one of the preceding claims, characterized in that upon detection of driveline vibrations discarded the value of the cache during the period under consideration becomes. Device for detecting and signaling misfiring of an internal combustion engine, to which a speed sensor is connected, which monitors a speed and a running noise of a crankshaft of the internal combustion engine, and wherein a detected running noise is stored in a misfire counter, characterized in that a buffer memory ( 16 ) for storing in a period of observation (t _B ) still to be distinguished Laufunruhen ( 19 ) after misfires or driveline vibrations ( 19.1 . 19.2 ) the misfire counter ( 17 ) is connected upstream. Apparatus according to claim 12, characterized in that the misfire counter ( 17 ) several buffers ( 16 ) are connected upstream.