EP2122143B1 - Indicating arrangement and method for determining an engine parameter - Google Patents

Abstract

The aim of the invention is to reduce the complexity of an indicating arrangement (6) on an internal combustion engine in order to determine a parameter. Said aim is achieved by calculating crank angle data from a measured variable in a computing unit (8) of the indicating arrangement (6) and determining a parameter from said calculated crank angle data and said measured variable.

Description

The subject invention relates to an indexing device for determining at least one of the knowledge of a crank angle information assuming engine characteristic of the performance of an internal combustion engine, with a sensor unit that receives a measured variable with a crank angle-dependent portion, and with a computing unit, which is connected via an input to the sensor unit, and an associated method for determining such a characteristic value and an application in a motor control.

On engine test benches, a complex sensor and indexing technology can be used to obtain or eliminate all desired engine characteristics - including parameters and parameters of the internal combustion engine to be tested (eg diesel or gasoline engine) or its operating behavior (eg during a work cycle) To calculate measurements. The indexing arrangement generally also includes a signal amplifier, which further processes a sensor signal for further use, eg amplifies, conditions, filters and / or digitizes. In certain sensors, such as the piezoelectric cylinder pressure transducers, which are particularly important for the indexing technique, a charge amplifier is generally used as signal amplifier. However, it is also possible to use, for example, strain gauges, piezoresisitive pressure sensors, structure-borne knock sensors, sensors for sonic and ultrasonic emission analysis, ion current probes, flame light sensors, sensors for needle lift, valve lift or piston stroke, etc., with the respective signal amplifiers. Often then in downstream separate processing units, the required engine parameters from the measured variables, such as cylinder pressure, crank angle, etc., calculated, or measured variables, such as the cylinder pressure, on a time basis or based on the measured crank angle to determine the engine characteristics are evaluated , where the calculations and evaluations on-line, ie during engine operation, or off-line, so in hindsight, can be performed. The processing units consequently require a separate input for a crank angle signal, eg from an angle transmitter. Nevertheless, some parameters can be determined without the crank angle information. For example, characteristic values such as, for example, peak pressure, combustion noise, knock intensity, frequency components, time differences between significant signal characteristics, etc., can be determined from the measured time curve of the cylinder pressure even without crank angle information. But important other parameters, such as the indicated mean pressure, mass conversion points, combustion curve, center of gravity combustion, components of the order analysis, ignition delay in degrees crank angle, etc., need for their albeit only approximate determination in addition to the cylinder pressure necessarily also a crank angle information, such as a Speed, the duration of one revolution of the crankshaft, the instantaneous angular velocity, the duration of a work cycle, the duration of a work cycle divided by the number of cylinders or an instantaneous rotation angle in any angular resolution. The measurement of the crank angle information naturally increases the effort for the sensors. On engine test benches, this effort is often justified, since usually the most accurate possible determination of certain characteristics and the most accurate evaluation of engine operation is desired, but also in this application for cost reasons, the cost is to be kept as low as possible. Another problem is, of course, the space required for a complex sensor and indexing technology and the fact that the required sensors can be installed in retrospect usually only with great effort on the engine.

In principle, it is of course also known from a substantially periodic measurement signal, such. B. from a Zylinderdruckaufnehmer to derive a crank angle information. In the AT 388 830 B For example, it is described that the drift compensation device of a charge amplifier circuit is triggered in accordance with the period of a measurement signal. The periodic trigger signals for the tripping device (that is to say essentially crankshaft angle information) can be obtained internally from the measuring signal or externally from a connected signal generator on a crankshaft.

From the article " Simulation Models of Internal Combustion Engines for Real Time Applications ", Gheorghiu V., Haus der Technik eV, Conference No. E-30-202-056-8, 1998 shows how a crank angle information can be calculated from a measured pressure curve, wherein a nonuniformity of the crankshaft revolutions is taken into account.

Of course, these methods for determining a crank angle information from a substantially periodic measurement signal only provide approximations for the required crank angle information. The error caused thereby depends essentially on the method used to determine the crank angle information. For the application in the field of engine test benches such approximation methods are usually unsuitable and therefore have not been considered so far. For use in the field of vehicle onboard measurement or indexing technology or in the low end indexing market, however, such complex indexing techniques are too costly and too complicated.

In the US 2002/0092499 A1 For example, a method of maintaining engine control when a crank angle sensor fails is described. In this case, from a substitute quantity (here, the signal of a knock sensor that measures pressure surges), crank angle information is calculated, and engine control (in particular, control of ignition and injection timings) is performed on the basis of this calculated crank angle information. Thus, the engine can be operated even if the crank angle sensor fails. Charge boosters with integrated peak value determination from the measurement signal have already become known. However, such charge amplifiers can only be used to a limited extent since only a single motor characteristic value can be determined and no flexibility is available. For a sensible application but usually different engine characteristics are needed.

It is now an object of the subject invention, an indexing, which is particularly simple and compact, low, easy to install and put into operation is and still can determine essential engine characteristics, and to provide an associated method.

This object is achieved for the indexing and the associated method according to the invention that is calculated with the calculation unit for determining the engine characteristic as an input exclusively from the recorded with the sensor unit measured value, a crank angle information and determined exclusively from the measured variable and the calculated crank angle information at least one engine characteristic and is output as an output signal at an output.

In contrast to an application of the high end indexing technology in the field of engine test stands, for use in the low end indexing market, eg for very cost effective test benches, or for example in the onboard measurement technology for production vehicles, for parameterization, calibration, diagnostics, monitoring, control, etc of an internal combustion engine, the expense and the costs for the indexing technique desirably be rather low. This can not be achieved with a conventional indexing arrangement or sensor system for the reasons mentioned above. Until now, it was necessary to record measured values with known indexing devices, such as a cylinder pressure sensor, and to supply an engine control unit (ECU) or a processing unit, where the measured values are evaluated, often taking into account other measured values, such as measured crank angles, and optionally by means of stored characteristic maps , Of course, the necessary sensor technology increases the costs and the effort for installation, commissioning, maintenance and parameterization of the sensors and the engine control unit or the processing unit. These disadvantages are now avoided by an indexing device according to the invention, in that the required characteristic values without additional crank angle input (which would mean additional expensive sensor technology and additionally required signal inputs) are integrated in the indexing device, since it has been recognized that the accuracy thus achieved is determined in the determination of the characteristic values is sufficient for use in the field of vehicle onboard metrology or in the low end indexing market, but also in other applications that require less accuracy. In particular, low investment costs, a simpler installation, are achieved with an indexing arrangement according to the invention in the vehicle, a simpler parameter setting, a time advantage during commissioning and measurement, the possibility of transmitting to third-party systems and an increase in quality while at the same time saving time (by avoiding iteration loops) in engine development. Furthermore, no profound expert knowledge of the operation is necessary for such an indexing arrangement. Also, a targeted search of a malfunction (the components or software structure of the engine control) by this application is possible. In addition, such an indexing arrangement offers very flexible application possibilities due to the almost arbitrary determination of characteristic values.

For certain sensor units, it is advantageous if a signal amplifier, in particular a charge amplifier, is provided in the indexing arrangement between the sensor unit and the calculation unit, which conditionally processes the sensor signal, e.g. amplified, conditioned, filtered and / or digitized.

The flexibility and utility of an indexing arrangement according to the invention is further increased when provided in the calculation unit, additional characteristics such as e.g. Peak pressure, combustion noise or knock strength, from the measured variable alone, so without the use of a crank angle information to determine.

Furthermore, it can be advantageous for an evaluation unit to be equipped with a plurality of inputs for different measurement channels and for each measurement channel or group of measurement channels having at least one measurement channel a separate calculation unit to be provided. It can be provided that these multiple calculation units also communicate with each other and so can exchange data with each other. Advantageously, however, this can also be a single calculation unit for all measurement channels.

Several measurement channels are e.g. When indexing on a multi-cylinder engine of great importance: Each cylinder is equipped with its own cylinder pressure sensor and the multiple cylinder pressure curves are to be evaluated based on the common for all valid crank angle information. In this case, it is of course particularly advantageous for the determination of the crank angle information that not only one but several signals with crank angle-dependent signal component are present, in addition usually a-priori knowledge of the geometry of the engine and thus the between the individual signals existing time or crank angle offset can be used.

If all the units of the indexing arrangement are arranged in a common housing, one obtains a particularly compact device, which is easy to use and in particular also reduces the wiring effort required outside of the device. Such a device can be seen as an "intelligent sensor" because it already provides the required signals or data and engine characteristics and no longer needs any downstream evaluation.

If a filter unit and / or a signal conditioning device and / or an amplifier is provided in the indexing arrangement, the expense of the downstream units can be further reduced since the indexing arrangement already supplies the signal in the required preparation.

A further integration stage can be achieved if an engine control unit is integrated into the indexing arrangement, whereby the outlay for the necessary hardware can be further reduced.

Such an indexing arrangement can now be integrated particularly advantageously in a motor control, since the motor control can already be supplied with the required characteristic values directly, which reduces the effort in the motor control and, on the other hand, the outlay for the sensors for the motor control can be reduced.

Fig. 1

eine Anordnung der erfindungsgemäßen Indizieranordnung am Motor,

Fig. 2

eine schematische Darstellung verschiedener Indizieranordnungen und

Fig. 3 und 4

je ein weiteres Beispiel einer erfindungsgemäßen Indizieranordnung.

The subject invention is based on the schematic, non-limiting FIGS. 1 to 4 , which illustrate advantageous embodiments of the invention, explained in more detail. It shows

Fig. 1

an arrangement of the indexing device according to the invention on the engine,

Fig. 2

a schematic representation of various indexing and

3 and 4

each a further example of an indexing arrangement according to the invention.

In FIG. 1 is a detail of a cylinder 1 of an internal combustion engine shown. In the cylinder cavity 3, a piston 2 is moved and the cylinder 1 are arranged in a known manner valves 4 and in the case of a gasoline engine, a spark plug 5, the invention is of course applicable to internal combustion engines with other combustion process. In addition, an indexing arrangement 6 consisting of a sensor unit 10 and an evaluation unit 8 is arranged on the cylinder 1, which in this case, for example, measures and evaluates the cylinder pressure. An indexing arrangement is generally understood in a known manner to be an arrangement which measures and / or evaluates engine measured variables, in particular but not exclusively combustion, during operation, for example during a work cycle, with high resolution of the dependence on time or crank angle. The indexing arrangement 6 or the evaluation unit 8 of the indexing arrangement 6 can, as in this example, be connected to an engine control unit 7 of a motor control or to another processing unit.

The indexing arrangement 6 comprises - as shown in detail in FIG Fig. 2a a sensor unit 10 for detecting a measured variable, for example a piezoelectric pressure transducer, a strain gauge, piezoresisitive pressure transducer, structure-borne knock sensors, sensors for sonic and ultrasonic emission analysis, ion current probes, flame light sensors, sensors for Nadelhub, valve lift or piston stroke, etc., and a Evaluation unit 8. The sensor unit 10 and the evaluation unit 8 are connected to one another via a suitable line and the signal of the sensor unit 10 is supplied to the evaluation unit 8 via an input 14. In the evaluation unit 8, a calculation unit 12, such as a microprocessor or a DSP (Digital Signal Processor), arranged by means of the measured variable, here, for example, the pressure in the cylinder 1, is further processed to a motor characteristic. The possibly required analog-to-digital conversion of the measurement signal can be done directly in the calculation unit 12 or even before. The signal processed by the calculation unit 12 of the evaluation unit 8 becomes analog at an output 13 or digitally output. Of course, in the simplest embodiment, the evaluation unit 8 and the calculation unit 12 can also be designed as a single unit.

Also, a display device 15 may be arranged at the evaluation unit 8, at which a calculated engine characteristic value can be displayed.

Between the sensor unit 10 and the calculation unit 12, a signal amplifier, in particular a charge amplifier 11 for a piezoelectric sensor, may be arranged in a known manner, as in FIG Fig. 2b shown. Depending on the type of sensors, the various known signal amplifier circuits can be used. For piezoelectric sensors, which are used among other things for the measurement of pressure, force, torque, and acceleration, the principle of the charge amplifier (in the narrower sense) compared to electrometer amplifiers and transimpedance amplifiers (eg voltage-current or charge-current converter) has largely enforced. Also for charge amplifiers in the narrower sense, various circuits have become known.

In addition, in the indexing arrangement 6, e.g. in the evaluation unit 8 or between the sensor unit 10 and the evaluation unit 8, also not shown here filter units and / or signal conditioning, be provided.

The calculation unit 12 calculates from the measured measured value a crank angle information, such as a rotational speed, the duration of a revolution of the crankshaft, the instantaneous angular velocity, the duration of a working cycle, the duration of a working cycle divided by the number of cylinders or a current angle of rotation at arbitrary angular resolution, and determined from the measured measured variable and the calculated crank angle information, an engine characteristic or an indexing characteristic, such as the indicated mean pressure, mass conversion points, combustion curve, center of gravity of combustion, components of the order analysis, ignition delay in degrees crank angle, etc .. The indexing 6 and the evaluation unit 8 thus requires No separate crank angle input, which is why the requirements for the required sensors are very low. The thus determined and output at the output 13 engine characteristic can, for. B. as in Fig. 1 indicated to be fed via a suitable line to an engine control unit 7 or other processing unit for further processing. The output signal can be output by the evaluation unit 8 both analog and digital.

The calculation unit 12 can also be programmed as desired, so that the user can enable any evaluations of the measured variable. This includes both the manner of determining the crank angle information and also determining which engine characteristic value (s) is (are) determined. Of course, several different crank angle informations can also be derived from one measured variable, for example in different approximate accuracies, which can be evaluated together with the measured variable to different engine characteristics.

In principle, any variable which contains a crank angle-dependent component, that is to say a variable which depends on the time or on the crank angle and from which, as a result, crank angle information can be derived, is considered as the measured variable. Of particular interest are variables which have a periodicity in the cycle period (in the 4-stroke 720 °, in the 2-stroke 360 °) or at least have such a signal component. Other signal components, in particular those resulting from transient operating conditions of the engine or from outside influences, are unsuitable for the determination of the crank angle information. For example, the following variables are possible: cylinder pressure, flame light in the cylinder, ion current in the cylinder, ignition voltage, ignition current, injection pressure, mechanical vibrations, structure-borne noise, airborne sound eg on the cylinder head or near the fire deck, pressure pulsations of intake air or exhaust gas. For detecting these variables, there are known sensors. These quantities are essentially periodic signals in stationary operation of the engine. In actual operation of an engine, the operating states of the engine change by accelerating or decelerating but continuously. For example, during engine start-up or rapid acceleration, the speed or instantaneous angular velocity changes within a work cycle, which is why conventional FFT analyzes for evaluating the measured variables frequently fail and more advanced methods have to be used, such as that from US Pat AT 001 519 U become known method for determining the speed of an internal combustion engine.

An engine characteristic value determined in this way can be stored in a downstream processing unit as an indexing variable, which may be e.g. the subsequent evaluation of the recorded measurement data and parameters of the engine operation allows. Likewise, use in engine development and engine calibration and engine testing is conceivable, e.g. for the design of the combustion in border areas, such as knocking or full load in diesel engines, or for the improvement of the comfort, e.g. in terms of combustion noise, or just to monitor an endurance run. However, such an engine characteristic value can also be used for vehicle onboard measurement technology and engine control. For example, the engine rating could be used to control the engine or certain aspects of the engine (e.g., combustion) or make adaptations to the engine control (e.g., stored maps) due to changing engine conditions. Similarly, by monitoring certain engine characteristics, a problem in the engine could be detected and displayed.

Of particular importance is the analysis of the energy flow or the creation of an energy or power balance of composite systems with inter alia an internal combustion engine. While it is comparatively easy with electric machines, the on or To determine dissipated power and energy, for example, from the electrically measurable sizes of the electrical connection, for internal combustion engines in general mechanical and / or thermodynamic measuring devices with relatively high temporal resolution is needed, so an indexing device that is capable, the required current or for example via a Combustion cycle averaged values of the yielded power and energy to determine and provide for the evaluation. An indexing device according to the invention can therefore also be used advantageously for such applications.

Obviously, in addition to an engine characteristic value which requires crank angle information for determining, any other engine characteristic values can be determined which manage without crank angle information and can be derived directly from the measured quantity measured. Such engine characteristic values can in turn be transferred via the output 13 to an engine control unit 7 or to another processing device.

But it is also conceivable to integrate the engine control unit 7 in the indexing 6. In this case, the evaluation of the sensor signals from the evaluation unit 8, which can also take over tasks of the engine control, or the evaluation of these signals could directly from the engine control unit 7, which is usually a calculation unit, such as. a microprocessor, done, whereby an additional evaluation unit 8 in the indexing 6 could also be omitted.

In the same way, it is of course possible to provide several measuring channels for different measured variables in the evaluation unit 8, such as in Fig. 3 shown. For this purpose, a separate input 14 can be arranged at the evaluation unit 8 for each measuring channel. It is thus possible with an indexing arrangement 6 or with the evaluation unit 8 to process and evaluate the measured variables of a plurality of sensor units 10. For example, different sensor units 10 can be arranged at different locations of the engine or, for example, a pressure sensor for measuring the cylinder pressure can be arranged on each cylinder. These further measured quantities can in turn be evaluated on the basis of crank angles in the indexing arrangement 6, the required crank angle information in turn being derived from at least one measured variable, or without crank angle information. Of course, it may be sufficient to calculate crank angle information from just one measurand. But of course it is just as possible to calculate your own crank angle information for every measurand.

Likewise, a separate calculation unit 12 can be provided in the evaluation unit 8 for each measurement channel, as in FIG Fig. 3 illustrated, or it can also be provided for one or a group of measuring channels, consisting of at least one measuring channel, only a single calculation unit, such as in Fig. 4 shown. Likewise, of course, a possibly required charge amplifier 11 may also be arranged directly in the sensor unit 10.

Of course, the individual components of the indexing arrangement 6 can also be arranged in a common housing 9 - as in FIG Fig. 2, c ) - and form an "intelligent sensor" that can be handled very easily as a compact device. Of course, such a closed housing 9 also eliminates the need for external cabling between the sensor 10 and the calculation unit 12. The indexing arrangement 6 then already contains all the units that are required to evaluate the measurement signal.

The parameterization of the indexing arrangement 6 or the evaluation unit 8 or the calculation unit 12, e.g. the sensitivity or resolution of the sensor unit 10 may, as is well known, be done in advance by associated software. However, it would also be conceivable to provide an independent parameterization in which the indexing arrangement 6 or parts thereof are parameterized during a learning process itself.

An indexing arrangement as described above may be used with internal combustion engines in virtually any configuration and environment, particularly any test rigs, such as those described in U.S. Pat. on the R & D test bench or on the production test bench, on the internal combustion engine alone, e.g. as a drive, as an auxiliary drive or as a generator, or in conjunction with other components, e.g. with components of the powertrain, with the entire powertrain or in the vehicle. But of course it is also the use in the serial application (on the road or on the water, etc.) or in the workshop, in the dock, etc. conceivable.

Claims (13)

1. An indicating arrangement for determining at least one engine parameter of the operating characteristics of an internal combustion engine which requires knowledge of crank angle information, having a sensor unit (10) which records a measured variable which has a crank-angle-dependent signal component, and having a calculation unit (12) which is connected to the sensor unit (10) by means of an input (14), characterized in that, in order to determine the engine parameter, the calculation unit (12) receives only the measured variable recorded by the sensor unit (10) as an input variable and calculates crank angle information therefrom and determines the at least one engine parameter exclusively from this measured variable and the calculated crank angle information and outputs this as an output signal at an output (13).
2. The indicating arrangement as claimed in claim 1, characterized in that a signal amplifier (11), in particular a charge amplifier, is provided in the indicating arrangement (6) between the sensor unit (10) and the calculation unit (12).
3. The indicating arrangement as claimed in claim 1 or 2, characterized in that an additional parameter can be determined in the calculation unit (12) from the measured variable alone.
4. The indicating arrangement as claimed in one of claims 1 to 3, characterized in that an evaluation unit (8) having a plurality of inputs (14) for different measuring channels is provided, and that a dedicated calculation unit (12) is provided for each measuring channel.
5. The indicating arrangement as claimed in one of claims 1 to 3, characterized in that an evaluation unit (8) having a plurality of inputs for different measuring channels is provided, and that a single calculation unit (12) is provided for the measuring channels or for a group of measuring channels.
6. The indicating arrangement as claimed in one of claims 1 to 5, characterized in that a filter unit and/or a signal conditioning device and/or an amplifier is provided in the indicating arrangement (6).
7. The indicating arrangement as claimed in one of claims 1 to 6, characterized in that the indicating arrangement (6) is arranged in a common housing (9).
8. The indicating arrangement as claimed in one of claims 1 to 7, characterized in that the indicating arrangement (6) comprises an engine control device (7).
9. The indicating arrangement as claimed in claim 8, characterized in that a calculation unit of the engine control device (7) is provided as the evaluation unit.
10. An engine controller having an indicating arrangement as claimed in one of claims 1 to 7, characterized in that the indicating arrangement (6) is connected to an engine control device (7) and supplies at least one parameter of the engine to the engine control device (7), which parameter is used in the engine control device (7) for controlling the engine.
11. A method for determining at least one engine parameter of the operating characteristics of an internal combustion engine which requires knowledge of crank angle information, in which an indicating arrangement (6) is attached to the internal combustion engine or to an unit of the internal combustion engine, and a measured variable with a crank-angle-dependent signal component is measured by means of a sensor unit (10) of the indicating arrangement (6), characterized in that a calculation unit (8) of the indicating arrangement (6) for determining the engine parameter calculates crank angle information exclusively from the measured variable, and determines the engine parameter exclusively from the measured variable and the calculated crank angle information.
12. The method as claimed in claim 11, characterized in that an additional parameter, which can be determined from the measured variable alone, is determined.
13. The method as claimed in claim 11 or 12, characterized in that the engine parameter is used in an engine control device (7) of an engine controller for controlling the engine.

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