EP1979599A1

EP1979599A1 - Method and device for controlling an internal combustion engine

Info

Publication number: EP1979599A1
Application number: EP07703581A
Authority: EP
Inventors: Jochen Walther; Michael Schueller; Roger Busch; Daniel Heitz; Matthias Siedentopf
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2006-01-20
Filing date: 2007-01-02
Publication date: 2008-10-15
Also published as: CN101375046A; US20120004822A1; DE102006002738A1; CN101375046B; JP2009523945A; WO2007085501A1

Abstract

Described are a method and a device for controlling an internal combustion engine. At least one injector meters a certain fuel quantity at a certain time on the basis of a first signal and/or a second signal of the internal combustion engine. At least the first and/or the second signal is corrected with a corrective value. The corrective value is adapted on the basis of at least one information value which is provided by at least one alignment process.

Description

description

title

Method and device for controlling an internal combustion engine

State of the art

The invention relates to a method and a device for controlling an internal combustion engine according to the preamble of the independent claims. The present invention also relates to a computer program product.

From DE 102 15 610 an apparatus and a method for correcting the injection behavior of injectors is known, in which an injector quantity comparison is carried out in several test points to increase the yield. For this purpose, the quantity deviation is measured at various test points, stored on the injector and read into the control unit during initial commissioning. In the control unit, based on these checkpoints, a correction map is calculated that is used in the control of the injectors. This so-called injector quantity adjustment is necessary because injectors have different quantity maps due to their mechanical manufacturing tolerances. A quantity map is to be understood as meaning the relationship between the injection quantity, the rail pressure and the drive time of the injector. As a result, despite electrically defined control, each individual injector fills the combustion chamber with different amounts of fuel. These tolerances can be compensated by injector balancing.

The disadvantage here is that the injectors measured at the end of the tape and the data must be read into the controller. If the assignment between injection quantity and activation time changes during operation of the internal combustion engine, these tolerances can not be taken into account with this method. A further method and a further device for controlling a fuel metering system of an internal combustion engine is known from DE 199 45 618. In this method, sets the driving time of at least one electrically operated valve, the fuel quantity to be injected. In certain operating states, the minimum actuation duration is determined at which fuel is being injected. Respectively. It determines the amount of fuel that is metered at the Mindestansteuerdauer. This method is also called zero-quantity calibration. The aim of such a zero-quantity calibration is to obtain an accurate metering of small injection quantities, which is particularly important for a

Pre-injection are metered, perform precisely. This method is carried out during operation, but has the disadvantage that only a certain operating point is considered. Ie. this method only provides a correction value for very small injection quantities. Whereby these correction values for small correction quantities can not easily be transferred to large actuation durations and / or large injection quantities.

Disclosure of the invention

Advantages of the invention

The inventive device and the method according to the invention with the features of the independent claims has the advantage that the injection system by this method over the entire life and all operating ranges of the engine and the combustion process a defined

Behavior shows. This method has several advantages over today each limited acting individual methods. Due to the applicability in the entire map range of the engine, no transition states with respect to the adaptation arise, ie there are no transient states or the like. The track behavior of the injection system, in particular of the injector, remains constant over the entire product life. This results in advantages in the design of the controller, such as the idle controller, since the system gain remains constant or in communication with other controllers, which in turn z. B. interrogate the engine load. The interactions in the injection system do not change over the lifetime, which is both quantity be corrected as injection timing. Changing the engine mode does not affect the use of the method. Ie. the method can also be used in homogeneous and / or in partial homogeneous operation. The method works individually for each cylinder and can be combined with the currently known methods for total quantity control. It is particularly advantageous that no additional sensors or actuators compared to today's systems is required.

These advantages are essentially achieved in that at least a first signal that determines the duration or the end of the injection and / or a second signal that determines the beginning of the injection is corrected with a correction value. This correction value is adapted on the basis of at least one information value provided by at least one adjustment method.

In a simple embodiment, this means that the correction values are stored in a characteristic map and the map values are adapted on the basis of at least one information value. The information values are provided, in particular, by a zero-quantity correction, by a quantity balancing regulation or by another balancing method. It can be provided that both the duration and the beginning of the fuel injection quantity is corrected. In simplified embodiments, in each case only the duration or only the beginning is corrected accordingly. It is particularly advantageous if the duration is corrected accordingly. Also particularly advantageous is an embodiment which stores the first signal and / or the second signal that determine the duration or the start of the fuel injection in a characteristic map and directly adapts these characteristic field values.

The adaptation can be designed such that the output signals of the respective characteristic field are corrected additively and / or multiplicatively or the

Map values are changed immediately.

The information values used usually represent one or more correction values for each one operating point. This is how the information value represents, for example, given by zero-quantity calibration - A -

, the correction value for small injection quantities. Other information values, on the other hand, may characterize the correction value for the same and / or other operating points. The information value preferably indicates the deviation of the actually injected fuel quantity from the desired fuel quantity. If such fuel quantity signals are not available, it is also possible to use other signals which use quantities which characterize the quantities of fuel.

It can also be provided that signals are evaluated that determine the deviation of the actually injected fuel quantity from the desired one

Characterize fuel quantity. A corresponding signal can be determined on the basis of the rail pressure progression. Preferably, based on the rail pressure curve over the time or over the angular position of the crankshaft or the camshaft during an injection, in particular a partial injection, a variable is determined which corresponds to the actually injected fuel quantity. It is particularly advantageous here that this information value can be determined almost at all operating points. This considerably simplifies the evaluation since only an interpolation between stored values and no calculation of values via a correlation is required.

According to the invention, the correction values of the remaining operating points of the correction map or pump map are now concluded on the basis of this one or more correction values which are provided by an information value. It can be provided that, starting from the information value, all operating points or only a part of the operating points are closed. Thus, it can certainly be provided that the correction values of the zero-quantity calibration are taken into account only up to a certain quantity value. Ie. the information values are used at least for certain map areas.

It is particularly advantageous that, after adaptation, the adjustment methods only act on the first and / or second signal via the correction map. This means, for example, if a balancing control is used as the balancing method, then these values are used to adapt the correction characteristic field. Once this adaptation has been completed, the adjustment Do not proceed directly to the activation time or the start of the activation. This is possible since corresponding errors and tolerances are already taken into account by the correction according to the invention. Furthermore, it is advantageous that in certain operating states the adaptation is prevented, ie, for example, the adaptation is inhibited for diagnosis. This is necessary because the adaptation also compensates for deviations and tolerances based on errors. An error detection would thus be difficult. On the other hand, the adaptation values can be evaluated for error detection. For example, it may be provided that errors are detected when the adaptation values assume such a large amount.

According to the invention, the correction takes place in such a way that there is a fixed known association between the first signal and the fuel quantity and between the second signal and the time at which the injection begins. This means that the correction takes place in such a way that with the same drive signal AD or AE the injector always meters the same quantity of fuel at the same time. Regardless of tolerances and signs of aging, the same drive signals can always be used.

The measures listed in the dependent claims further advantageous refinements and improvements of the device and method specified in the independent claims are possible.

drawing

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it:

Figure 1 is a block diagram of an apparatus for injecting fuel an an internal combustion engine and

FIG. 2 is a block diagram of the procedure according to the invention. Description of the embodiments

FIG. 1 shows a block diagram of a method and a device for controlling fuel in an internal combustion engine. With 100, an injector is called, the fuel supply into a combustion chamber of a non-illustrated

Internal combustion engine 100 controls. Usually, an injector is provided for each cylinder of the internal combustion engine. The injector 100 is acted upon by a power amplifier 105 with certain voltage values and / or specific current values, so that it releases the fuel metering at a certain point in time and ends the fuel metering at a further second time. The

Amplifier 105 in turn is supplied with a first signal AD and a second signal AE.

The first signal AE determines the beginning of the fuel metering and the signal AD the duration and thus the end of the fuel metering. Each of the first and second signals is provided by a map 110, hereinafter referred to as the drive map 110. In this is essentially dependent on the injected fuel quantity QK and other operating parameters such as the fuel pressure P, the control duration AD deposited. Accordingly, in a control map 110, the second signal AE is stored as a function of the desired start of delivery FB and further operating parameters. These input variables with regard to the injected fuel quantity QK and the start of delivery FB are provided by a quantity specification 115 or a delivery start specification 120.

The quantity specification 115 or the delivery start specification 120 calculates the fuel quantity QK to be injected or the start of delivery FB from output signals N, FP from various sensors 125. These signals preferably characterize the operating state of the internal combustion engine and / or the driver's request. In particular, the driver's request FP essentially determines the amount of fuel QK to be injected.

According to the invention, it is now provided that the output signal AD of the control characteristic field 110 reaches the output stage 105 via a connection point 130. Accordingly, the second signal AE passes through a node 140 to the output stage 105. A first correction value KD provided by a first correction 132 passes via a switching means 134 to the second input of the first node 130. A second correction value KE passes from a second correction 142 via a node 144 and a second one Switching means 146 to the second node 140. The two

Switching means 134 and 146 are driven by a controller 150. At the second node 144, the signal KD is present.

Both the first correction 132 and the second correction 142 are supplied with different signals which characterize different operating parameters. In particular, it is the quantity of fuel QK to be injected, which is preferably provided by the quantity specification 115, and the output signal P of a pressure sensor 160, which provides a signal which characterizes the pressure of the fuel during the injection. Instead of the output signal of a pressure sensor, another variable which characterizes the fuel pressure can also be used. In particular, a pressure variable can be used, which is calculated on the basis of other operating parameters. If the procedure according to the invention is used in a so-called common-rail system, the pressure variable P is preferably the so-called rail pressure.

Based on various operating parameters such as the amount of fuel to be injected, the start of delivery and other operating parameters such as the fuel pressure P calculates the Ansteuerkennfeld the first signal that characterizes the drive time and the second signal AE that characterizes the start of control. In the nodes 130 and 140, a correction value is superimposed on these signals. In the illustrated embodiment, an additive correction takes place, ie the correction value KD or KE is simply added to the output value of the control characteristic field. However, the procedure according to the invention is not limited to such an additive correction, it is also possible to provide a multiplicative or another type of correction such as an additive and a multiplicative correction, ie in this case the correction 132 or 142 gives an additive and a multiplicative correction value. In an embodiment of the procedure according to the invention, it can also be provided that the values in the control map 110 are changed directly with the correction value KD or KE.

Both the first correction 132 and the second correction 142 each determine a correction value KD or KE, which are used to correct the first or the second signal. In this case, the first correction or the second correction in each case determines a correction value for each operating point of the injector 100. The operating point of the injector is defined in the illustrated embodiment by the amount of fuel to be injected and the fuel pressure P. According to the invention, it may also be provided that other variables which define the operating point are used here. In particular, it can also be provided that even more variables are used to define the operating point, ie. H. in addition to the amount of fuel to be injected and the rail pressure other variables, such as enter the temperature. Furthermore, it can be provided that, instead of the quantity of fuel to be injected, substitute quantities which characterize these variables are used.

The output signal KD of the first correction 132 is used to correct the output signal AD of the control map. The correction value KE is used to correct the second signal AE, which characterizes the start of injection, and is calculated from the node 144 on the basis of the first correction value KD and the output of the second correction 142. The two values are preferably multiplied in the connection point 144 in order to determine the second correction value KE.

In a particularly advantageous embodiment, it is provided that the correction values respectively arrive at the first or second connection point via a first switching means 134 or a second switching means 146. This is done against the background that the adaptation of the first and the second signal is switched off in certain operating states. This shutdown is carried out by the controller 150. In a shutdown, instead of the first correction value or the second correction value, the value zero is transmitted in an additive correction and the value one in a multiplicative correction. Thus, it can be provided that the method described in certain operating states and / or in the presence of certain combustion processes, such as in homogeneous and / or partially homogeneous operation, is deactivated or comes only to a limited extent to the effect.

In FIG. 2, the first correction 132 is shown in detail

Elements are designated in Figure 2 with corresponding reference numerals. In the following, the first correction 132 is shown in detail in FIG. According to the invention, it is provided that the second correction 142 is constructed the same or at least similar. A correction map is labeled 200. At the two inputs is on the one hand, the fuel quantity signal QK and on the other hand, the pressure signal P on. In this map, the correction values are stored depending on the operating point, which is defined in particular by these two variables. These two sizes are chosen only by way of example. For other types of injectors or other types of internal combustion engine, other characteristics may be used. Furthermore, it can be provided that, in addition to these variables, further input variables are used to define the operating point. In particular, temperature values can still be used here. Depending on these input variables, a correction value KDO is stored in the correction map 200 for each operating point. This passes through a node 205 to the switching means 134. At the second input of the

Switching means 134, the output signal is a zero value 210 default. The controller 150 selects either the output of the zero setpoint 210 or the output of the node 205 for propagation to the node 130.

In a first correlation map 220, correlation values are also stored as a function of the operating point of the injector. These are linked in a node 222 with a first information value Il. The first information value Il is provided by a first matching function 224. The link in the node 222 is multiplicative, for example. But it can also be additive or additive and multiplicative. The output signal of the node 222 passes via a node 228 to the node 205. In the node 228 is preferably an additive link, but it can also be a multiplicative or an additive and multiplicative link provided. In the link tion point 205 is preferably a multiplicative combination of the two signals.

A second correlation map is denoted by 230, in which are also stored, dependent on various input variables which define the operating point of the injector, correlation values which at the node 232 link to an information value 12 provided by a second adjustment method 234. The output signal of the node 232, which preferably performs a multiplicative link, passes through the node 228 to the node 205. in a simplified

Embodiment can also be provided that the second correlation map and the corresponding connection points omitted. In an improved embodiment it can be provided that even more correlation maps and further information values of further matching methods are provided.

In the correction map 200, base values for the correction of the activation period AD are stored. These correction values, which are stored as a function of the operating state and in which a correction value is stored for each operating state in the correction map, represent basic values, which are subsequently based on the contents of the correlation maps 220 and / or 230 and the first and / or second information value II, 12 are adapted. On the one hand, the adaptation can take place in such a way that, starting from the values stored in the correlation map, the information value is determined by adaptation values with which the output signal of the correction map 200 is changed multiplicatively or additively or multiplicatively and additively. Alternatively it can be provided that, based on the content of the correlation map and the information value, the content of the correction map is changed accordingly.

The base values stored in the correction map 200 are preferably determined once and stored in the map. They are then modified by adaptation in which in one embodiment, the output signal of the map for each operating point is multiplicatively, additively or multiplicatively and additive corrected or changed in the map values accordingly. The values stored for the first time are used in the application of the driving detected and read. Alternatively, it can also be provided that these values are read in during initial startup. Alternatively, it can also be provided that these values are calculated on the basis of a few essential base values.

Various methods and procedures provide information, i. H. Informationswerte llund / or 12. These methods usually provide for at least one operating point of the injector a balancing value with which the control period is to be corrected so that the injectors with a corresponding on-control signal metering a corresponding amount of fuel. Usually, these information values only apply at one operating point. In the correlation map 220, correlation values are now stored for all operating points, which indicate the relationship between the one information value to an operating point and the correction values at the remaining operating points. Ie. Based on the correlation map for all operating points stored in an information value and in the correlation map 220, the correction value for all operating points can be calculated at the node 222. This correction value calculated in this way is superposed in the node 205 on the output signal of the correction map. Accordingly, the procedure also takes place in the case of the second information value 12.

According to the invention, it can also be provided that the correlation map only covers specific map areas. For example, it may be provided that the information value provided by the zero-quantity calibration is used only for small amounts of fuel. In addition to the so-called zero-quantity calibration, the values of the injector equalization, as known, for example, from DE 102 15 610, can also be used as information values. This so-called injector quantity calibration provides several information values for several operating points.

However, it can also be provided that the values of the injector counterbalance are used to form the correction characteristic map 200 and that only adjustment methods are carried out for the current operation provide an information value Il or I 2. As values of information, all quantities can be used which characterize the deviation of the actually injected fuel quantity from the desired fuel quantity. The results of different calibration procedures can be used. Such adjustment methods use, for example, the speed as an input variable. However, the balancing methods may also evaluate signals that characterize the exhaust gas composition, such as the oxygen content, or the combustion process, such as the combustion chamber pressure.

Furthermore, it is possible that by evaluating suitable signals, a variable is determined which characterizes the actually injected fuel quantity. Thus, for example, based on the pressure curve of the fuel pressure, the injected fuel quantity can be calculated. For this purpose, for example, the rail pressure of a common rail system can be evaluated. Alternatively, a corresponding pressure signal can also be determined by means of sensors which are in the

Supply lines between the rail and the injector or are arranged directly in the injector. This means, starting from the course of the rail pressure, the end of injection or the end of injection and the start of injection are detected. Based on this, the actually injected fuel quantity is determined. Alternatively, it can also be provided that starting from the pressure curve over the

Time or via the crankshaft position, the actual injected fuel quantity is determined.

By means of a pressure sensor mounted on the rail (alternatively on the injector supply line), the end of each individual partial injection of each injector is identified on the basis of the characteristic curve of the pressure signal and compared with an expected end of injection at the respective operating point. Due to the well-known behavior of the injector, the injection end can now be mapped to the expected value via a targeted change in the activation timing, which results in a set equalization. The correction values are preferably stored as pre-control values for the following drive cycle.

This makes it possible, regardless of the operating point of the engine as the current combustion method, to determine the desired part injection quantity. An adaptation (eg via storage of the correction values in a suitable form) the Injektorkennfeldes is also possible. This means that the determined actual injection quantity or a quantity derived from the actual injection quantity is used as information value I. Since the injection quantity can be determined at all operating points, no correlation map is required.

The determination of the end of injection from the rail pressure signal represents only one possible variant. In one embodiment, it may also be provided that the end of injection is determined on the basis of other variables. For example, a suitable means, in particular a sensor, may be arranged in the region of the injector, which provides a corresponding signal. In particular, it can be provided that a chip with a corresponding evaluation of the signals is provided in the region of the injector.

Particularly advantageous in this embodiment is: The control circuit does not require special states of the engine or vehicle, and can thus be applied under all situations. In particular, an application in a stationary engine is possible. Due to the well-known injector behavior at any operating point, quantity changes can be eliminated by influences of previous injections, the interactions in the system and thus the complexity are reduced. No additional sensors are required in systems with a rail because the existing sensors are used. Respectively. Sensors are used, which are then also available for other applications. There is no need for a correlation behavior of the injector over the volume or pressure ranges. This means that the correlation maps 220 and 230 may be omitted if necessary. Changing the engine operating mode does not affect the use of the method. The track behavior of the injection system remains constant over the entire product life. This results in advantages in the controller design of eg idle control, since the system gain remains constant or n communication to other control devices, in turn, for example, query the engine load. The method works cylinder individually, and can be used to replace the known today methods for total amount control partially or combined. The individual correction values can be used for diagnostic purposes. It is particularly advantageous if a threshold value query takes place. If the injection end detected from the rail pressure deviates by more than a threshold from the expected value, then an error is detected. In particular, this will detect a defective injector.

Furthermore, it can also be provided that in certain operating states in which the injected fuel quantity is known, for example in idle mode and / or in full load operation. The actually injected fuel quantity is detected by means of suitable sensors or by evaluation of suitable signals and, based on the detected fuel quantity, an information value is determined and used to correct the correction characteristic field.

To form the correction value for the start of injection, it is provided that the correction value KD, which is also used to correct the activation duration, is weighted by the correction 142 over the operating point, which is defined by the fuel quantity and the rail pressure, by the necessary correction value KE to determine the correction of the start of control. In such a simplified embodiment, the second correction 142 only includes a corresponding rating map for each operating point.

Claims

claims

A method for controlling an internal combustion engine, wherein at least one injector, starting from a first signal and / or a second signal of the internal combustion engine, meters a certain amount of fuel at a certain time that at least the first and / or the second signal is corrected with a correction value , characterized in that, starting from at least one information value provided by at least one matching method, the correction value is adapted.

2. The method according to claim 1, characterized in that correction values for a control period and / or a control start depending on the operating point are stored in a correction map.

3. The method according to claim 1, characterized in that the information value characterizes at least one correction value of an operating point.

4. The method according to claim 2, characterized in that, starting from the at least one correction value is closed to the correction values of the remaining operating points of the correction map.

5. The method according to claim 4, characterized in that after adaptation, the adjustment method acts only on the correction map on the first and or second signal.

6. The method according to claim 1, characterized in that in certain states, the adaptation is inhibited.

7. The method according to claim 1, characterized in that the correction takes place such that a fixed known association between the first signal and the Amount of fuel that is metered, and / or between the second signal and the time at which the injection begins, there is.

8. The method according to claim 1, characterized in that the at least one information value is determined based on the pressure profile during an injection.

9. An apparatus for controlling an internal combustion engine, in which at least one injector, starting from a first signal and / or a second signal of the internal combustion engine meters a certain amount of fuel at a specific time, with means that at least the first and / or the second signal with a correction value, characterized in that means are provided which adapt the correction value based on at least one information value provided by at least one adjustment method.