DE3615547A1 - Device for detecting a defectively operating cylinder of a multicylinder internal combustion engine, and method for operating the device - Google Patents

Abstract

In a multicylinder internal combustion engine, such as a motor vehicle engine, for example, the speed of the engine is sampled in order to detect in the region of the power stroke of each cylinder a maximum and a minimum speed, in accordance with which a difference is calculated between the maximum and minimum speed data as a speed fluctuation. In this way, a fluctuation in the engine speed is obtained for each cylinder and the fluctuation data are intercompared in order to detect a cylinder which is operating defectively and producing less torque. If a defective cylinder is detected, an alarm device is activated in order to alert the driver that engine failure (breakdown) is at hand. In addition, the fuel supply to a defectively operating cylinder is interrupted, in order to prevent undesirable escape of unburned fuel. <IMAGE>

Description

Device for detecting a malfunctioning cylinder of a multi-cylinder internal combustion engine, as well as a method for operating the device

The invention relates to a device for detecting a malfunctioning cylinder of a multi-cylinder internal combustion engine, according to the preamble of claim 1, as well as a method for operating this device, according to the preamble of claim 6.

Each cylinder of a multi-cylinder internal combustion engine, for example a motor vehicle or the like, has various peripheral parts for supplying fuel into the cylinder and igniting the fuel / Air mixture on. More specifically, in the case of a diesel engine, a glow plug is a fuel injector or the like and, in the case of an Otto engine, a spark plug etc. are provided. These parts can loosen, get lost or cease to function so that, for example, the air / fuel mixture supplied in the cylinder no longer ignited, burned and

Postgiroamt Munich 1360 52-802 (bank code 700 100 80) Deutsche Bank AG Freising 93 020 50 (bank code 700 700 10) StadtsparKasse Freismg 6007 (bank code 700 510 03) Dresdner Bank Freising 7 828 500 00 (bank code 700 800 00)

05/07/1986. 5 '' - "'**

L f can be encountered. In the case of a single-cylinder engine, such a malfunction in the combustion chamber is easy to detect because the torque generated drops sharply or the engine stops. In multi-cylinder engines, such as those from US Pat. Nos. 4,475,507 and

4,503,821 are known, however, it is difficult to find one to discover such a fault, since the engine by the Combustion processes in the remaining cylinders continue. This has the consequence that in a motor vehicle - ^ q with a multi-cylinder engine the driver of the vehicle continues because he is not aware of the incident in a certain cylinder.

However, continuing to operate an internal combustion engine with such a fault condition is disadvantageous because Not only does the torque generated decrease, but also the dangerous situation can arise that the fuel is expelled from the engine without being burned. To avoid such a dangerous situation, it is desirable to warn the driver of the motor vehicle or the fuel supply to the faulty one Stop cylinder if this is an error condition specific cylinder is recognized.

/ jl · It is therefore an object of the present invention to provide a The ability to identify a faulty cylinder in a multi-cylinder engine to avoid dangerous situations to avoid, whereby the driver of a motor vehicle is still given the opportunity to use his vehicle

_ ₀ to drive to a safe place, such as a parking lot, or to reach the nearest workshop.

The solution to this task is carried out by the characterizing Features of claim 1 or 6.

According to the invention, the engine speed is monitored to a

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Maximum speed and a minimum speed in the range of the Recognize the power stroke of each cylinder, and these are recognized maximum and minimum speeds used to obtain a differential speed which corresponds to changes in speed, this change being is compared with other change data from the other cylinders to determine whether the one in question Cylinder is working properly or not.

■ jQ According to the invention it is also provided that not only the driver is informed of a faulty condition, but also the fuel supply to a faulty one Cylinder or several cylinders is interrupted to prevent fuel leakage.

Advantageous further developments of the invention emerge from the respective subclaims.

More details, features and advantages of the present-2Q The invention will become apparent from the following description with reference to the drawing.

It shows:

2g Fig.l the schematic structure of an embodiment of the present invention;

FIG. 2 shows the various sensors and a control unit according to FIG. 1 in a block diagram; FIG.

Fig. 3 is a flowchart of a program for detecting

a defective cylinder;

Fig. 4 is a partial flow chart of a program for Untergg interruption of the fuel supply to an error

stick cylinder, which was determined by the program according to Figure 3;

«Β 5> S *« ■

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Fig. 5 is a timing diagram showing the angle of rotation signal and

Shows engine speed with a normal engine; and

Fig. 6 is a timing diagram showing the rotation angle signal

and the engine speed in the event of a faulty engine condition shows.

-J ^ q The same or corresponding parts are in the drawing provided with the same reference numerals.

1 shows, in a schematically simplified manner, an embodiment of the present invention. The described embodiment is assigned to a four-cylinder diesel engine and capable of one or more faulty cylinders to identify and fuel supply to the affected Cylinders or the affected cylinder.

2Q Referring to Fig. 1, an injector 10 is of the cam face manifold type provided to supply fuel to the above-mentioned four-cylinder diesel engine. These Injection device 10 is known and operates such that the fuel via an intake line 16 into a

2c compression chamber 18 is performed, and there by a Piston 14, which is rotated and reciprocated by the cam surface 12, is compressed. As a result is pressurized fuel via manifolds 20 and supply valves 22, which are for each cylinder

_on the motor not shown in the drawing are provided. The injection device 10 is also able to discharge fuel under high pressure from the compression chamber 18 via an overflow valve 26a into a low pressure chamber, where-

"P. arranged at the valve 26a at an overflow outlet 24 and is operated by a solenoid valve 26. This

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• ^ Solenoid valve 26 is controlled so that the overflow outlet 24 is opened or closed so that the amount of fuel supplied to the individual cylinders is regulated will.

According to FIG. 1, a control unit 30 is also provided, which controls the solenoid valve 26. The control unit 30 receives various information signals from various sensors, such as a speed sensor 32, a

- ^ q nem accelerator pedal sensor 34, which works as a variable resistor and the degree of depression of the accelerator pedal, a rotation angle sensor 36 for detecting a reference angle with regard to the stroke of the piston 14, temperature sensors 38 for detecting the cooling water temperature, 5 intake air temperature and the like and pressure sensors

for recording air pressure, intake air pressure and the like. The rotation angle sensor 36 has projections 36a on a rotating shaft, i.e. the piston 14 of the injector 10, as well as an associated electrical

2Q tromagnetic pickup 36b to a cylinder at To detect fuel injection process. The number of projections 36a corresponds to the number of cylinders of the Motor, so that with one full revolution of the piston 14 the electromagnetic pick-up 3 6b generates 4 pulses.

oc Although here an electromagnetic pick-up for detection the angle of rotation of the piston 14 is shown, other sensors are also possible, for example Hall sensors, optical sensors or the like.

"Q Fig. 2 shows a schematic block diagram for explanation the structure of the control unit 30 according to FIG. 1. The control unit 30 essentially has an input connection 50, a CPU 52 (central control unit), a ROM 54 (read-only memory), a RAM 56 (memory with random

gg access), a power circuit 62 for power supply of the above-mentioned components and a data bus

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! between the individual circuits for data transmission on. The input terminal 50 receives the aforementioned various information signals from the sensors 32 to 32 on, and an output port 58 is used to provide a control or drive signal to solenoid valve 26 of the injector 10 feed. The CPU 52 controls the fuel injection using various sensor signals, so that it is optimal for the current operating status and continues to recognize malfunctions

2Q of one or more cylinders, with changes in speed of the engine, which are output by a speed signal from the speed sensor 32. Fixed Control programs and given data are stored in the ROM 54, whereas various data that

, c are required during the control process, temporarily can be stored in the RAM 56.

The control unit 30 detects a malfunction of one or more cylinders by means of a program sequence, _on the reference to the flowchart of Fig. 3

is described. In the flow chart of FIG. 3, means the letter K is a counting status of a counter and corresponds to the cylinder number during combustion or the power stroke. Since the described execution

“C form concerns a four-cylinder engine, K die Numbers 1 to 4 used. In addition, the reference symbols C (K), i.e. C (I), C (2), C (3) and C (4) are counting states, which correspond to the number of detected faults in the corresponding cylinders. In this embodiment an error status is assumed for each cylinder if the number of error statuses detected 20 reached. The reference symbols F (K), i.e. F (I), F (2), F (3) and F (4) are flags that are used to indicate fuel injection interrupt in the cylinder, at

"Ρ- when an error function was detected. With others Words, the flags F (K) are fuel injection prevention flags, in a not shown burning

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A fuel injection control routine also performed by the control unit 30 can be used.

The flowchart according to FIG. 3, which is used as a recognition program can be designated for a defective cylinder is started when the engine is and is started as long as the engine is running repeatedly executed. After the start of the program, the initialization takes place in a step 101 various dates and flags carried out;

^ q the counter readings K are reset to "1" and the counting states C (I), C (2), C (3) and C (4) as well as the flags F (I) to F (4) are reset to "0". In one following step 102, a minimum value NL (K) and a maximum value NH (K) of the engine speed NE, each

^ g is then calculated when from the speed sensor 32, a speed signal is output in a program not shown, read. These values NL (K) and NH (K) are referred to below as minimum speed and maximum speed. The minimum speed

2Q speed NL (K) can be used directly at the top dead center position can be obtained before the power stroke, while the maximum speed NH (K) can be obtained at the middle of the power stroke.

2 = More precisely, the values NH (K) and NL (K) can go through Comparison of a plurality of speed data obtained during a period of time, respectively a quarter turn of the piston 14 were determined.

ο Such a rotation of the piston 14 by 90 can under

ο «Use of the output signal of the transducer 36b recognized while the speed data by counting the number of clock pulses between two consecutive Pulse signals from the speed sensor 32 are determined.

In a following step 103, it is determined whether the rotation angle signal is input from the rotation angle sensor 36

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will or not. When the decision is YES, i.e. when the rotation angle signal has been input, a following step 104 K is incremented by 1 (K - ^ - K + 1).

In a following step 105 it is determined whether the incremented Value of K is 5 or not. When the decision is YES, a following step 106 the count value K is set to "1". On the other hand, when the count value has not yet reached 5 or after K im ^ q Step 106 is set to "1", becomes a following Step 107 carried out, in which minimum speed NL (K) and maximum speed NH (K) during the power stroke of a next cylinder can be entered.

, g In a following step 108, a ratio Δ. N (K) between the fluctuation of a previous speed and a fluctuation in the present speed of each Cylinder calculated. More specifically, the foregoing fluctuation in the rotational speed is determined first

2Q the difference between the maximum speed NH (K-I) and the minimum speed NL (K-I) in the power stroke of a cylinder and the present fluctuation in the speed is determined by determining the difference between the maximum speed NH (K) and the minimum speed NL (K) calculated. Thereafter, the ratio between these two fluctuations is expressed as Δ N (K) calculated. In a following step 109 it is checked whether the value of Δ N (K) is below a specified value such as 0.5. This comparison between

₃ Q see ΔΝ (Κ) and the specified value is carried out in order to be able to determine whether the currently affected cylinder is malfunctioning or not.

If it is determined in step 109 that ά N (K) ^ 0.5, this means that the cylinder is working properly and in a following step 110 the count value C (K) is set to "0". After step 110, a

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j, 3815547

Step 111 is carried out, in which the flags F (K) are reset to "0". After completing the step 111 the program flow goes back to step 103 in order to carry out this and the following steps again.

However, if it is determined in step 109 that the ratio Δ N (K) is less than 0.5, a Step 120 is carried out, in which the count value C (K) is incremented by 1. In a following step 121

- ^ q checks whether the count value C (K) has reached 20 or not. If C (K) <2 0, step 111 is carried out. When C (K) ^ 20, it is determined that the The cylinder is no longer working properly and an alarm is issued in a step 122 in order to prevent the

I £ Warn the driver of the vehicle.

The alarm is to warn the driver that engine damage present and request that they have an inspection or repair carried out. The alarm 2Q can for example by means of a buzzer or a Flashing light.

After step 122, a step 123 is carried out in which the fuel injection is carried out in one or more

2g reren defective cylinders is prevented. More accurate said, the injection inhibition flag F (K) is set to "1" in this step so that this flag is set in a injection control, not shown, which is performed by the CPU 52, is used. Preferably

Q ₃ is, as stopped in this embodiment, the fuel supply to malfunctioning cylinders, since the further operating an engine can be dangerous with faulty running cylinders. After the fuel supply to malfunctioning cylinders is interrupted

gg has been, the engine can continue to operate safely so that the driver can bring his vehicle to a safe place without any dangerous situations

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to have to fear actions.

In the fuel injection control program mentioned above, the solenoid valve 26 of the injector 10 remains at the time of fuel injection into a cylinder designated by the injection prevention flag F (K) was kept open. As a result, there is no fuel in this designated defective cylinder can be injected.

Fig. 4 shows part of the fuel injection control program, in which the fuel supply to a malfunctioning cylinder is interrupted. The steps according to FIG. 4 can be carried out with a known combustion

jg fuel injection control program can be combined like it for example, in Fig. 7 of U.S. Patent 4,475,507. In FIG. 4, in a step 300, which corresponds to the step 241 in Fig. 7 of said US-PS corresponds, a cylinder is determined in the power stroke. In a following step

2Q 302 it is checked whether the injection prevention flag F (K) Is "1" or not. It should be noted here that this determination is made in step 302 in connection with a cylinder takes place, which was determined in step 300. In other words, if recognized in step 300, for example

2g is that cylinder # 3 has just finished the power stroke executes, it is checked whether or not F (3) is "1". If the flag F (K) is "0", it becomes so in a step 304 Solenoid valve 2 6 for injecting fuel is closed. When the flag F (K) is "1", in a step

oQ 306 the solenoid valve 26 opened and the fuel supply interrupted to a faulty cylinder.

Referring to FIGS. 5 and 6, the detection of one or more malfunctioning cylinders will be discussed in more detail gg are explained.

Fig. 5 is a timing chart showing the rotation angle signal and

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Shows engine speed signal when the engine is in normal working condition. In the event that all cylinders are working normally, takes the variation in the speed, i.e. the difference between maximum speed NH (K) and minimum speed NL (K) has essentially the same value for all cylinders. It is thus found that none of the cylinders is malfunctioning.

Fig. 6 is a timing diagram similar to that of Fig. 5, aliQ However, it is assumed here that the engine is faulty

is working. Assume that the No. 2 cylinder is malfunctioning due to some failure such as loosening or loss of the glow plug or fuel injector. The consequence of this is that the air / fuel mixture supplied to cylinder no. 2 cannot be compressed sufficiently to ignite and ^; to burn. Thus it becomes the minimum speed

NL (2) greater than that of the other cylinders, whereas the maximum speed NH (2) is less than that of the 2Q remaining cylinder is. Thus, the fluctuation of the Speed resulting from NH (2) - NL (2), comparatively lower than the fluctuation in speed NH (I) NL (I), resulting from the combustion in the No. 1 cylinder.

Using this difference between the speed changes, the ratio iN (K) is found to be see if this ratio is greater than a constant value such as 0.5. This constant value is used in

"Q Regarding possible differences between variation data, obtained when all cylinders are determined operate normally so that only one fault condition is detected.

gc As in connection with step 121 in the flow chart 3 has been described, it is determined only that a certain cylinder is defective

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works when the number of detections that the rate of change of the rotational speed Δ N (K) a certain number exceeds 20. That is, in this embodiment 20. The reason for this, i.e. the reason why a defective cylinder is only determined if the rate AN (K) is the constant value exceeds a certain number of times, is that there is a possibility that 4N (K) only some can be faulty a few times without real engine damage.

When finally finalized in step 121

is that a particular cylinder is malfunctioning, steps 122 and 123 are carried out to the driver to warn and the injection prevention flag F (K) to "1" ■ ever to put. ·

^; As a result, as shown in FIG. 6, no fuel injection is performed for cylinder # 2 because the solenoid valve drive signal is from the

2Q control unit 30 opens the solenoid valve 26 so that no Fuel is supplied to the No. 2 cylinder. This eliminates the undesirable leakage of unburned fuel effectively prevented from the faulty cylinder. The engine can therefore continue to operate without stopping.

2c th, although the torque generated decreases.

An essential feature of the present invention that are used to identify a faulty cylinder speed and angle of rotation sensors that normally ₃ Q will be used in existing fuel injection systems, so that no new or additional sensors are necessary. Thus, the present invention can be realized by changing the control program of the CPU 52 in the control unit 30, for example.

Since, as described, fuel is prevented from being supplied to the defective cylinder or cylinders

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the driver can drive his vehicle without any dangerous side effects proceed as fuel leakage. This is particularly advantageous when a Engine failure occurs when driving on an expressway or freeway as it is difficult on such roads is to stop the vehicle.

The present invention has been described in terms of a diesel engine; faulty cylinders on gasoline engines can but can also be recognized in the same way. Furthermore, although in the embodiment described above a ratio Δ N (K) between speed fluctuations was detected, the determination of an erroneous Cylinder take place in that only the difference between maximum and minimum speed data is detected and an error condition is detected if such a difference is greater than a specified value.

Claims (11)

Kühnen Wacker & partner PATENT AND LAWYERS NIPPONDENSO CO., LTD. Aichi-ken, Japan PATENTANWÄLTE EUROPEAN PATENT ATTORNEYS RAINER A. KÜHNEN - Dipi.-ing. PAUL-ALEXANDER WACKER - Dipl.-Ing .. Dipl.-Wirtsch.-Ing. PETER FÜRNISS Dr. Dipl.-Chem. LAWYER GÜNTER FRHR. v. GRAVENREUTH - Dipi.-ing. (FH) Approval: LG Munich I and Il Telephone: O 81 61/62 09-1 ■ Telex: 526 547 pawa d Telefax: 0 81 61/62 09-6Datex-P: 45-8 161-30 Teletex: 8 161 800-pawaMUC D-8050 FREISING 1, SCHNEGGSTRASSE 3-5 16ND01643-02 05/07/1986 Patent claims 1. Device for detecting a defective cylinder in a multi-cylinder internal combustion engine / characterized by: (a) first means for detecting the speed of the engine; (b) second facilities, which interact with the first facilities and changes to the Detect the speed of the engine in the range of the power stroke of each cylinder; and (c) third devices responsive to the second devices and using them the speed fluctuation detect the faulty cylinder. Postgiroamt Munich 1360 52-802 (bank code 700 100 80) Deutsche Bank AG Freising 93 020 50 (bank code 700 700 10) Stadtsparkasse Freising 6007 (bank code 700 510 03) Dresdner Bank Freising 7 828 500 00 (bank code 700 800 00) 05/07/1986 KW&B: 16ΊΝ £ 02.643-02 :: - 2. Apparatus according to claim 1, characterized in that the second devices are designed in such a way that they the speed fluctuations by calculating the difference between a maximum speed and a minimum speed of the engine over a given angle of rotation of the engine crankshaft to calculate. 3. Apparatus according to claim 1, characterized in that Q that the third devices are designed in such a way that they detect the defective cylinder when there is a relationship between the fluctuation due to the power stroke of a cylinder and another fluctuation due to the power stroke of another cylinder which is smaller than a specified value. 4. Apparatus according to claim 1, characterized in that devices are provided to the fuel supply to interrupt the cylinder recognized as working defective. 5. Apparatus according to claim 1, characterized in that devices are provided which warn against that engine failure has occurred. 6. Procedure for detecting a malfunctioning Cylinder in a multi-cylinder internal combustion engine, characterized by: ₃ Q (a) detecting the speed of the engine; (b) Detecting fluctuations in the speed of the engine in the range of the power stroke of each cylinder using the detected speed of the _oc motors; and (c) Detection of the defective cylinder under 05/07/1986 KVi & P: 16NL) 016 43-0 2, / Turn of the fluctuation. 7. The method according to claim 6, characterized in that the detection of the speed fluctuation Difference between a maximum speed and a minimum speed of the motor over a given angle of rotation of the engine crankshaft is calculated. iQ 8. The method according to claim 6, characterized in that that when the defective cylinder is detected, it is detected that a relationship between the speed fluctuation due to the power stroke of a cylinder and another speed fluctuation due to the Le i ■ ig stungshubes of another cylinder is smaller than a fixed value. 9. The method of claim 6, further characterized by interrupting the supply of fuel to a 2Q cylinder that was detected as defective. 10. The method of claim 6, further characterized by warning that engine damage has occurred is. 11. The method of claim 8, further characterized by determining that a particular cylinder is malfunctioning whenever the number of times to which the ratio is smaller than the specified OQ value, exceeds a certain number.