DE10227279A1 - Operating internal combustion engine involves verifying agreement of detected combustion chamber pressure with combustion chamber pressure derived from secondary parameter detected by auxiliary sensor - Google Patents

Abstract

The method involves verifying the agreement of the detected combustion chamber pressure for a control cylinder with a combustion chamber pressure derived from a secondary parameter detected by an auxiliary sensor or the agreement of a primary operating parameter derived from the detected combustion chamber pressure with a primary parameter derived from the secondary parameter. The method involves detecting (14) the combustion chamber pressure of at least one cylinder (12a), deriving at least one primary operating parameter for the engine and detecting at least one secondary operating parameter with at least one auxiliary sensor (16,18). The agreement of the detected combustion chamber pressure with a combustion chamber pressure derived from the secondary parameter for a control cylinder or the agreement of the primary operating parameter derived from the pressure with a primary parameter derived from the secondary parameter is verified. Independent claims are also included for the following: (a) a computer program for implementing the inventive method (b) a control and/or regulating device for operating an internal combustion engine (c) and an internal combustion engine with an inventive control and/or regulating device.

Description

State of the art

The invention initially relates to a Method for operating an internal combustion engine with several cylinders, in which the combustion chamber pressure of at least one cylinder by means of a Pressure sensor, which is assigned to the cylinder, detected and from the recorded combustion chamber pressure at least one individual for this cylinder primary Operating size of the internal combustion engine is determined, and in which at least one different from the combustion chamber pressure secondary Operating size of the internal combustion engine is detected by means of at least one auxiliary sensor.

The combustion chamber pressure of a cylinder provides important information in the operation of an internal combustion engine, with which the combustion in the cylinder in terms of emissions, Fuel consumption, performance, smoothness and noise can be optimized. To the primary Operation sizes count the start of burning, the center of combustion, the gas torque, maximum pressure, and indexed work. Because of the differences in the behavior of the cylinders with each other due to manufacturing tolerances etc. the Combustion chamber pressure for to know each cylinder individually.

A corresponding procedure is from the DE 197 49 817 A1 known. In the internal combustion engine disclosed there, a combustion chamber pressure sensor is assigned to each cylinder. In addition, a sensor is used that detects the current angular position of a crankshaft of the internal combustion engine and delivers a corresponding output signal. Both signals are evaluated together by the control unit of the internal combustion engine in order to determine the start of injection and the combustion position for each cylinder in a crank angle-related coordinate system.

From the DE 44 45 684 A1 A method is known which determines the course of the gas torque from the instantaneous rotational speed of the crankshaft and uses it to determine various primary cylinder-specific operating variables of the internal combustion engine.

The EP 0 517 774 B1 again discloses a method for determining the course of the internal pressure of a cylinder from a measured structure-borne sound course.

The present invention has the Task to improve the known method so that operational safety the internal combustion engine as high as possible is.

• – aus dieser sekundären Betriebsgröße für mindestens einen Zylinder, dessen Brennraumdruck mittels Drucksensor erfasst wird ("Leitzylinder"), der Brennraumdruck und/oder jene primäre Betriebsgröße gewonnen wird, welche auch aus dem erfassten Brennraumdruck dieses Leitzylinders ermittelt wird, und
• – dass für den Leitzylinder die Übereinstimmung des erfassten Brennraumdrucks mit dem aus der sekundären Betriebsgröße gewonnenen Brennraumdruck oder die Übereinstimmung der aus dem erfassten Brennraumdruck ermittelten primären Betriebsgröße mit der aus der sekundären Betriebsgröße gewonnenen primären Betriebsgröße verifiziert wird.

This object is achieved in a method of the type mentioned in the introduction in that

• - from this secondary operating variable for at least one cylinder, the combustion chamber pressure of which is detected by means of a pressure sensor (“guide cylinder”), the combustion chamber pressure and / or that primary operating variable which is also determined from the recorded combustion chamber pressure of this guide cylinder, and
• - That for the master cylinder the correspondence of the detected combustion chamber pressure with the combustion chamber pressure obtained from the secondary operating variable or the correspondence of the primary operating variable determined from the detected combustion chamber pressure with the primary operating variable obtained from the secondary operating variable is verified.

Advantages of invention

The essence of the invention lies in joint evaluation of the pressure signal of at least one master cylinder and at least one replacement signal. This has the advantage that the Combustion chamber pressure and / or the primary (n) Company size (s) of Internal combustion engine for the master cylinder or cylinders are determined redundantly and so the Operational reliability of the internal combustion engine is increased.

Assuming that the pressure sensor is the The combustion chamber pressure in the master cylinder can be reproduced correctly variation over time of the detected combustion chamber pressure from which the secondary Company size gained Combustion chamber pressure or that determined from the recorded combustion chamber pressure primary Company size from the from the secondary Company size gained primary company size on the Aging condition and component tolerances of the internal combustion engine getting closed. This makes it possible to carry out any required maintenance work to perform in time. This also ensures the operational reliability of the devices operated according to the invention Internal combustion engine improved.

Advantageous further developments of Invention are in subclaims specified.

• – der Brennraumdruck einer Anzahl von Leitzylindern erfasst wird, welche kleiner ist als die Gesamtanzahl der Zylinder der Brennkraftmaschine, und
• – aus der mittels Hilfssensor erfassten sekundären Betriebsgröße für mindestens einen der Zylinder, dessen Brennraumdruck nicht mittels Drucksensor erfasst wird, der Brennraumdruck und/oder jene primäre Betriebsgröße gewonnen wird, welche auch aus dem erfassten Brennraumdruck des mindestens einen. Leitzylinders ermittelt wird.

In a first, particularly advantageous development of the method according to the invention, it is proposed that

• - The combustion chamber pressure of a number of master cylinders is detected, which is smaller than the total number of cylinders of the internal combustion engine, and
• - The combustion chamber pressure and / or that primary operation variable, which is also obtained from the detected combustion chamber pressure of the at least one, for at least one of the cylinders, the combustion chamber pressure of which is not detected by means of a pressure sensor, is obtained from the secondary operating variable. Guide cylinder is determined.

With this training there are costs saved because not all cylinders are equipped with a pressure sensor are. Still, one is more precise and safe operation of the internal combustion engine possible because of the verification of agreement the one for the or the guide cylinders are detected or determined by means of a pressure sensor Sizes with the quantities obtained by means of the auxiliary sensor ensure that a state is recognized in which the operating parameters obtained are the real state of the internal combustion engine no longer with the necessary precision represent. This training therefore offers an improvement in the estimate of the primary Company sizes of cylinder not equipped with a pressure sensor due to the verification option on the master cylinder.

In further training, it is proposed that the combustion chamber pressure of only a single cylinder of the internal combustion engine is detected by means of a pressure sensor. With this training is the cost saving in the manufacture of the internal combustion engine maximum.

That is also particularly preferred Development of the method according to the invention, in which on the basis of the verification of the conformity of the means Pressure sensor detected combustion chamber pressure with that obtained from the secondary operating variable Combustion chamber pressure or based on the verification of compliance the primary operating variable determined from the recorded combustion chamber pressure with the from the secondary Company size gained primary Company size a transfer function, which are used to obtain the combustion chamber pressure and / or the primary operating size from the secondary Company size serves is adjusted at least from time to time.

This causes aging effects the internal combustion engine as well as so-called "specimen scatter", that is, differences from an internal combustion engine secondly due to manufacturing tolerances, compensated without that for Each combustion chamber requires its own pressure sensor. The operation the engine is over their entire term possible with high precision and security, what about the entire term a favorable Fuel consumption and good emissions behavior enables.

It is also proposed that if the combustion chamber pressure detected by the pressure sensor differs from the corresponding one from the secondary Company size gained Combustion chamber pressure or the one determined from the recorded combustion chamber pressure primary Company size from the corresponding from the secondary Company size gained primary farm size at least deviates by a certain value, a message is issued. hereby becomes a simple wear indicator created that enables timely maintenance intervention, before damage occur on the internal combustion engine. Also unacceptable copy variations from one internal combustion engine to another, for example during the final inspection the internal combustion engine, in this training in a simple manner and ways are recognized.

The precision of the wear indicator is increased again if then if the deviation within a certain time interval occurs, a message is issued.

The processing of the least a pressure sensor and from the at least one auxiliary sensor Signals is simplified in that these signals are synchronized in a common crank angle Time slots are processed.

Further training is also advantageous in which by means of at least two different auxiliary sensors at least two different from one another and from the combustion chamber pressure secondary farm sizes recorded are, and from which the combustion chamber pressure and / or a primary Company size for at least a master cylinder is obtained and based on which the plausibility the signals from the sensors are checked. this makes possible the detection of aging or a failure of one of the sensors, which also benefits the operational safety of the internal combustion engine comes.

A structure-borne noise and / or a crank angle curve are advantageously used as secondary operating variables. A crank angle sensor is already present in conventional internal combustion engines, so that this does not result in any additional costs. A structure-borne noise sensor is robust, inexpensive, can be placed at a comparatively large number of locations on the housing of the internal combustion engine and delivers signals from which the cylinder-specific combustion chamber pressure can be obtained in a simple manner, for example by means of at least one corresponding transfer function. In detail, this is based on the DE 44 45 634 A1 and the EP 0 517 774 B1 as well as the DE 197 41 884 C2 referenced, the teaching of which is hereby expressly made the subject of the present invention.

The invention also relates to a computer program, which to carry out of the above method is suitable when it is executed on a computer. It is particularly preferred if the computer program on a Memory, in particular on a flash memory, is stored.

The invention also relates to a control and / or regulating device for operating an internal combustion engine. With such a tax and / or control device is particularly preferred if it includes a memory on which a computer program of the above type is stored.

There is also an internal combustion engine Subject of the present invention. It advantageously points a control and / or regulating device of the above type.

drawing

Below is a particularly preferred one embodiment of the present invention with reference to the accompanying Drawing explained. Their only figure is a block diagram an internal combustion engine and a method for detecting and Obtaining and verifying certain company sizes Internal combustion engine.

In the single figure, an internal combustion engine is symbolically represented by its engine block, which is the reference symbol 10 wearing. It comprises four cylinders 12a . 12b . 12c and 12d , The combustion chamber (without reference number) of the cylinder 12a is a pressure sensor 14 assigned which is the pressure in this combustion chamber 12a detected. The combustion chambers of the other cylinders 12b to 12d no such pressure sensor is assigned. The cylinder 12a is therefore also referred to as the "master cylinder". On the engine block 10 is a structure-borne noise sensor 16 appropriate. A crank angle sensor 18 detects the current angle of a crankshaft (not shown).

In order to optimize the operation of the internal combustion engine with regard to emissions, fuel consumption, performance, smooth running and noise, it is advantageous if for each cylinder 12a to 12d the beginning of the combustion process, the focus of combustion, the gas torque, the pressure maximum, the indicated work and other variables for the current combustion are known. The sizes listed are also referred to as "primary farm sizes". The current combustion is usually the combustion cycle of a work cycle of the respective cylinder 12a to 12d Roger that.

Various methods are available for determining the primary farm sizes. The starting point of numerous methods is the course of the combustion chamber pressure in the combustion chamber of the respective one. cylinder 12a to 12d , This can, in a manner to be shown, either directly from the pressure sensor 14 detected or by means of a transfer function from the signal of the structure-borne noise sensor 16 be won. However, the primary operating variables can also be processed by processing the signal of the crank angle sensor 18 be won. This is explained in detail below (the corresponding method is a computer program on a memory of a control and regulating device 22 ) Filed:
The pressure sensor 14 delivers a pressure signal U2, which with an analog / digital converter 22 is sampled and digitized synchronously with the crank angle. This is done in the analog / digital converter 22 also a signal U3 of the crank angle sensor 18 fed in and processed according to the desired angular resolution. The digitized and crankshaft synchronous pressure signal is from the analog / digital converter 22 an analysis unit 24 fed. In it, the pressure signal for the combustion chamber of the master cylinder 12a A number of primary operating variables are determined, such as the start of combustion, the corresponding combustion focus, the gas torque, the pressure maximum and the indicated work.

The signal U3 from the crank angle sensor 16 but is also in a processing block 26 fed in and filtered and differentiated there. Knowing the moments of inertia of the rotating and oscillating masses of the internal combustion engine (from these values are constants that result from the design of the internal combustion engine; the moments of inertia are, of course, dependent on the angle), the low-pass filtered value and the differentiated value become the temporal profile the so-called alternating components of the gas torque. The alternating components of the gas torque are understood to mean the components of the torque fluctuating within one camshaft revolution.

By analyzing the components of the gas torque by analyzing the components up to the ignition frequency, it is possible to derive those operating quantities that are proportional to the DC component of the gas torque and the torque differences between the individual cylinders 12a to 12d are. The direct component of the gas torque is understood to mean the torque which compensates for the friction torques and the load acting on the crankshaft of the internal combustion engine (it is understood that the friction torque also has an alternating component which is dependent on the crank angle).

In a computer unit 28 from this, along with those in the analysis unit 24 for the master cylinder 12a determined primary operating variables, the corresponding primary operating variables for the cylinders not provided with a pressure sensor 12b . 12c and 12d won. This is done in the computer unit 28 for example the gas torque of the master cylinder 12a as an absolute variable and from the speed signal of the sensor 18 observed differences in gas torques in the individual cylinders 12a-12d fed in as relative quantities. This results in the absolute gas torques of the other cylinders on the basis of model ideas 12b-12d determined. The primary operating sizes for the cylinders 12a to 12d are then sent to an engine control unit 30 forwarded, which provides the cylinder-specific manipulated variables required for optimal operation of the internal combustion engine (ignition timing, injection quantity, injection start, injection end, etc.).

In the computing unit 28 the model parameters of the transfer functions are also checked, by means of which the signal U3 of the crank angle sensor is used 18 the primary farm sizes the cylinder not equipped with a pressure sensor 12b . 12c and 12d be won. For this purpose, in the computer unit 28 starting from those in the processing block 26 provided values also primary operating variables for the master cylinder 12a won (a primary company size would basically suffice for the comparison). The one in the analysis unit 24 for the master cylinder 12a The primary operating variables determined are now compared with those in the computer unit 28 for the master cylinder 12a obtained primary farm sizes compared. Exceeds the deviation in different ways and based on different sensors 16 and 18 for the master cylinder 12a If a primary measure is obtained from the primary operating parameters, the model parameters of the corresponding transfer functions are adjusted.

As already explained above, the structure-borne noise sensor is also used 16 used to provide primary operating variables, which are used for the control or regulation of the internal combustion engine. The structure-borne noise sensor provides this 16 a signal U1, which, analogous to the pressure signal U2 of the pressure sensor 14 , with a digital / analog converter 32 is sampled and digitized synchronously with the crank angle. The digital / analog converter 32 is also the signal U3 of the crank angle sensor 18 fed.

A stored transfer function is used in a processing block 34 from the digitized structure-borne noise signal for the master cylinder 12a and the other cylinders 12b to 12d the cylinder-specific combustion chamber pressure is obtained in each case. In the processing block 34 but also the digitized pressure signals of the analog / digital converter 22 fed, which on the pressure signals of the pressure sensor 14 of the master cylinder 12a based. By comparing the pressure sensor 14 determined pressure values with those for the master cylinder 12a by means of structure-borne noise sensor 16 obtained pressure values can be the parameters of the transfer function of the processing block 34 checked and can be adapted to possible changes during the running time of the internal combustion engine.

In the computing unit 28 are from the cylinder-specific combustion chamber pressures, which are in the processing block 34 were determined, the primary operating parameters were obtained, which were already in the analysis unit 24 based on the pressure signals from the pressure sensor 14 or also in the computer unit 28 based on the signals of the processing block 26 won.

In the present exemplary embodiment, the primary operating variables of the internal combustion engine for the master cylinder 12a So generated in three different ways: Firstly, by means of a pressure sensor 14 recorded combustion chamber pressure values, on the other hand on the basis of the signals of the crank angle sensor 18 , and finally based on the signals from the structure-borne noise sensor 16 , This redundancy can be in the computer unit 28 to compensate for possible offset and amplifier errors of the pressure sensor 14 be used.

In the computing unit 28 is for the master cylinder 12a the course of the deviations between the primary operating variables obtained in different ways is also monitored. They give way on the basis of the pressure sensor 14 determined primary operating variables from the other operating variables within a certain period of time by more than a certain value, an error message is issued which informs the user of the internal combustion engine of a certain state of wear. In the case of a new internal combustion engine, such a reference can be used to record impermissible scatter of specimens from one internal combustion engine to another.

In the method shown in the figure, it is therefore possible to determine cylinder-specific primary operating variables with high precision, taking into account the aging effects of the internal combustion engine, without having to do this for each cylinder 12a to 12d a separate pressure sensor is required.

Claims (13)

Method for operating an internal combustion engine with several cylinders ( 12 ), in which the combustion chamber pressure of at least one cylinder ( 12a ) by means of a pressure sensor ( 14 ) which the cylinder ( 12a ) is assigned, and from the recorded combustion chamber pressure at least one for this cylinder ( 12a ) individual primary operating variable of the internal combustion engine is determined ( 24 ), and in which at least one secondary operating variable of the internal combustion engine that differs from the combustion chamber pressure by means of at least one auxiliary sensor ( 16 . 18 ) is recorded, characterized in that - from this secondary operating variable for at least one cylinder ( 12a ), the combustion chamber pressure of which is recorded by means of a pressure sensor ("master cylinder"), the combustion chamber pressure and / or that primary operating variable which is also obtained from the recorded combustion chamber pressure of this master cylinder ( 12a ) is determined ( 26 . 34 ), and - that for the master cylinder ( 12a ) the correspondence of the detected combustion chamber pressure with the combustion chamber pressure obtained from the secondary operating variable or the correspondence of the primary operating variable determined from the recorded combustion chamber pressure with the primary operating variable obtained from the secondary operating variable is verified ( 28 ). A method according to claim 1, characterized in that - the combustion chamber pressure of a number of guide cylinders ( 12a ) is recorded, which is smaller than the total number of cylinders ( 12a-12d ) the internal combustion engine machine, and - from the auxiliary sensor ( 16 . 18 ) recorded secondary operating variable for at least one of the cylinders ( 12b-12d ) whose combustion chamber pressure is not recorded by means of a pressure sensor, the combustion chamber pressure and / or that primary operating variable is obtained ( 28 ), which also results from the detected combustion chamber pressure of the at least one guide cylinder ( 12a ) is determined ( 24 ). Method according to claim 2, that the combustion chamber pressure of only a single cylinder ( 12a ) the internal combustion engine by means of a pressure sensor ( 14 ) is recorded. Method according to one of the preceding claims, characterized in that on the bass of the verification of the correspondence of the pressure sensor ( 14 ) recorded combustion chamber pressure with the combustion chamber pressure obtained from the secondary operating variable or the correspondence of the primary operating variable determined from the recorded combustion chamber pressure with the primary operating variable obtained from the secondary operating variable, a transfer function which serves to obtain the combustion chamber pressure and / or the primary operating variable from the secondary operating variable , is adjusted at least from time to time. Method according to one of the preceding claims, characterized in that when the pressure sensor ( 12a ) detected combustion chamber pressure from the corresponding combustion chamber pressure obtained from the secondary operating variable or the primary operating variable determined from the recorded combustion chamber pressure deviates by at least a certain value from the corresponding primary operating variable obtained from the secondary operating variable, a message is issued. A method according to claim 5, characterized in that then if the deviation occurs within a certain time interval, a message is issued. Method according to one of the preceding claims, characterized in that the signals of the at least one pressure sensor ( 14 ) and the signals of the at least one auxiliary sensor ( 16 . 18 ) are processed in a common crank angle synchronous time grid ( 22 . 32 ). Method according to one of the preceding claims, characterized in that by means of at least two different auxiliary sensors ( 16 . 18 ) at least two secondary operating variables which differ from one another and from the combustion chamber pressure are recorded, so that the combustion chamber pressure and / or a primary operating variable for at least one guide cylinder is obtained from these ( 28 ), and based on this, the plausibility of the signals from the sensors is checked ( 28 ). Method according to one of the preceding claims, characterized characterized that as a secondary Company size a structure-borne noise and / or a crank angle curve is / will be used. Computer program, characterized in that it is used to carry out the Method according to one of the preceding claims is suitable if it is based on running on a computer becomes. Computer program according to claim 10, characterized in that it is stored on a memory, in particular on a flash memory is. Control and / or regulating device ( 20 ) for operating an internal combustion engine, characterized in that it comprises a memory on which a computer program according to one of claims 10 or 11 is stored. Internal combustion engine, characterized in that it is a control and / or regulating device ( 20 ) according to claim 12.