DE10324940A1 - Method and control device for controlling a plurality of fuel valves of an internal combustion engine - Google Patents

Abstract

The invention relates to a method and a control device for controlling a plurality of fuel injection valves (200 ... n) of an internal combustion engine. It is known from the prior art that injection cycles for the individual injection valves are initially specified for such controls, and that the injection valves are then controlled according to these injection cycles with the aid of actuators (210-n). The control of the injection valves is monitored on the basis of measured electrical variables. To avoid uncertainties when assigning measured values to the individual injection valves, only the measured values for a selected injection valve are selected and subsequently evaluated. In addition, to ensure that a complete injection cycle for a specific injection valve is recorded or observed, the corresponding measured values are selected according to the invention exclusively during a predetermined observation time window (B).

Description

The The invention relates to a method and a control device for actuation a plurality of fuel injection valves of an internal combustion engine, the valves are controlled with piezo actuators.

State of technology

From the prior art, in particular from the European patent application EP 1 138 902 A1 such a method and control device is known. According to this application, the control device comprises a control device and an activation device which controls the actuators of the injection valves of the internal combustion engine in response to injection cycles specified by the control device. The actual activation of the actuators or the injection valves is monitored with the aid of a measuring device. The measuring device delivers the measured values to an analog / digital converter, which converts the measured values in response to a trigger signal analog / digital. In order to ensure a clear assignment of the measured values present at the input of the analog / digital converter to selected fuel injection valves or cylinders of the internal combustion engine, the said European application teaches to observe only one selected injection valve at a time by corresponding measurement value acquisition or only one trigger signal for the Generate actuator of the selected injector in order to then convert only the current measured values of the selected injector analog / digital and then evaluate (see paragraph 0072 of the English version of the application).

Next has the advantages mentioned in the said European application described procedure, however, the disadvantage that the detection of the measured values for the selected one Fuel injector is subject to uncertainties. So can for example, not ensured in the procedure described that an injection cycle, which usually includes several injection processes, completely represented by a certain number of measured values becomes.

outgoing from this prior art it is therefore the object of the invention a known method and control device for controlling a plurality to further develop injection valves of an internal combustion engine in such a way that when selecting measured values, which control has taken place of a selected one Represent injection valve, it is ensured that these measured values cover a complete injection cycle represent.

This Object is achieved by the method claimed in claim 1 solved. More specifically, the solution is found in the known method described in the introduction in that the selection of the measured values during of a given observation time window.

The solution just described the above task relates to the case that actually a Injection cycle for the individual injectors is specified. Such a requirement does not take place in all conceivable operating states of the Internal combustion engine. In particular, no such specification is made in the event of a fuel cut-off. In this case it is explicitly stated that the injection valves should not be actuated. If the internal combustion engine or its control is then error-free do not function due to this special requirement Activation of the injection valves and accordingly no measured values measured.

Indeed then still finds a so-called selection of them existing measurements instead. The term "selection" is then in the sense of a review understand whether according to the specification indeed no measured values have been generated. This selection or review takes place then only according to the invention while of the specified observation time window instead. This special solution the above object is achieved by the claim in claim 2 Procedure represents.

The electrical variable for control The actuators of the injection valves can generate an electrical voltage or an electrical current, but preferably an electrical current Be cargo.

Advantages of invention

It applies to both of the solutions described so far that a suitable choice of the starting point in time and the length or duration of this observation time window ensures that all measured values which represent a complete injection cycle are recorded. The observation time window enables the resources for the observation and evaluation of the measurement results for a be correct fuel injection valve, that is to say the resources of the control device, are limited to a minimal expenditure of time, so that these resources are then available within a very short time for the observation, for example, of measured values of other injection valves or cylinders.

Around the start and end time or the duration of the observation window it is advantageous to determine this observation window dependent on from the position or angle of the crankshaft To dimension or position the internal combustion engine.

The The above task is still solved by two control units which the control devices each have an observation time window given while the selection of the measured values for the selected injection valve exclusively he follows. The advantages of the control units designed in this way correspond the advantages mentioned above with reference to the described method.

Further advantageous embodiments of the invention are the subject of the dependent claims.

drawings

The The invention is described below with reference to two exemplary embodiments on the attached five figures described in more detail in which

1 the control unit and the injectors connected to it;

2 a typical injection cycle;

3 an actuator circuit with a measuring device;

4 a first embodiment of the invention; and

5 shows a second embodiment of the invention.

description of the embodiments

In 1 can be seen that the control unit 100 essentially from a control device 110 and an activation device 120 consists. The control device 110 is preferably designed as a microcontroller. It gives the injection times for individual injection cycles for all fuel injectors 200-1 ... in front of an internal combustion engine.

A typical injection cycle is in 2 shown. In addition to a main stroke H1, it can also have several secondary strokes H2 and H3. The control device is used to implement such an injection cycle 110 for example, before when applying a charge to an actuator for a particular injector, for example 200-1 , must be started, time t _AL , and when loading must be ended in 2 at the time t _EL . Furthermore, the control device 110 how long the applied charge should be kept at the level thus obtained, in order to then initiate discharging of the actuator at a time t _AE , which must be ended again at a time t _EE . This specification of the charging and discharging time intervals for an actuator also defines, depending on the charge applied to the actuator per unit of time, the needle stroke associated therewith and thus the respective fuel quantity to be injected during the stroke. To define a complete injection cycle, this information is provided not only by the control device for the main stroke H1 but also for all the secondary strokes H2, H3 110 specified.

Because the control device 110 these specifications for the injection cycle not only for one, but for n fuel injection valves 200-1 ... n specifies where these injection cycles can overlap in time are in 1 l parallel lines are provided to this information to control the injection cycles from the controller 110 to the activation device 120 transferred to. The activation device 120 sets these specifications from the control device 110 to give specific commands to control the respective injection valves 200-1 ... n assigned actuators.

The Represents parameter n a specific cylinder of the internal combustion engine or a injector associated with this cylinder or one this injector associated actuator.

3 shows that the injectors 200-n not directly, but via actuators assigned to them 210-n can be controlled. As already mentioned, the control takes place by applying an electrical charge to these actuators.

The control of an injection valve 200-n or from its actuator 210-n is monitored by observing suitable measured values. Suitable measurements are, for example, those above the respective actuator 210-n Tapped voltage Sn or a predefined part thereof or the one activated by the respective actuator 210-n flowing current I, which over a measuring resistor 220-n can be tapped. By definition, the current provides information about the change in the amount of charge applied to the actuator per unit of time.

In practice it is common, as in 2 to recognize that measure the charge on the actuator at the end of a charging process, for example by evaluating said current. The corresponding measurement times are in 2 each indicated by downward-pointing arrows on the plateau levels of the strokes. At these times, the charge quantities L1 _t3 , L1 _t2 and L1 _{t1 are} measured there. Similarly, shortly before the end of an unloading process, it is common for each stroke of a cycle to be above the actuator 210-n to measure falling voltage Sn. In 2 The measurement voltages S1 _t3 , S1 _t2 and S1 _t1 result in this way.

4 shows a first embodiment of the invention. In the middle of 4 it can first be seen that on the basis of a control device 110 generated selection signal S _A first a selection of a specific injection valve 200-1 . 200-2 or 200-n with hoofs of a designated selector switch 124 is hit. For the injection valve selected in this way, in which 4 shown example, the injection valve 200-1 with n = 1, a selection of the desired electrical measured variables is then made. The electrical measured variables, such as the charge L or the voltage S or another electrical variable X, are selected with the aid of a multiplexer 122 which is just like the selector switch 124 preferably the activation device 120 assigned. In response to another from the control device 110 or from the activation device 120 The multiplexer then selects self-generated control signal S _B 122 for the previously selected injection valve 200-1 in a sequence predetermined by the second control signal S _B, the electrical variables present at its input as measured values. This also results in the output of the multiplexer in 4 shown alternating order of on the actuator of the injection valve 200-1 measured charges L1 and voltages S1. In their chronological order t1, t2, t3, these measured values represent the activation of the first injection valve that actually took place 200-1 or the injection cycle actually implemented for it, as shown in 2 is shown as an example. The time t1 is earlier than the time t2 and the time t2 earlier than t3.

The measured values described are transmitted via the multiplexer, which has only one channel 122 to an analog / digital converter 112 the control device 110 transfer. In response to a trigger signal, which was generated in accordance with the specified injection cycles, they are converted from this to analog / digital. The trigger signal is preferably at the end of a charging or discharging process, for example in response to one of the activation device 120 generated signal generated. The observation time window B according to the invention for the individual injection valves is in the in 4 shown first embodiment of the invention contained in the above-mentioned signals S _A and S _B. The signal S _A specifies the cylinder to be observed and is used by the control device 110 specified. In addition to the selected injection valve / cylinder, the signal S _{A also} defines the start and end of the observation time window, that is to say the point in time at which measured values at all for the purpose of further evaluation by the control device 110 on their analog / digital converter 112 and when not. The signal S _B specifies the physical measured variable, charge, voltage for the injector to be observed.

An observation time window preferably has a width of 720 ° KW (crankshaft angle); 720 ° KW corresponds to two crankshaft revolutions. With this width, it covers a complete injection cycle that was previously carried out by the control device 110 selected injection valve. The position of the observation time window in relation to the injection cycle is selected such that a certain remaining time still remains between the start of the observation time window and the first injection process of the cycle and between the last injection process of the cycle and the end of the observation time window. In this way, it is ensured as the main advantage of the invention that the complete injection cycle lies within the observation time window and in particular the first injection process of this cycle lies within the observation time window and can therefore be recorded. Between two successive ones Observation time windows preferably have a time pause, which is expressed in crankshaft degrees Δφ = 720 ° / KW Number of cylinders of the internal combustion engine (1). is.

For a 6-cylinder internal combustion engine is the pause between two successive observation time windows therefore 120 ° KW. The following table Tab. 1 shows an example of how the observation time window, in which exactly one cylinder of the internal combustion engine is evaluated will, about the crankshaft revolutions are distributed.

For the first exemplary embodiment of the invention described above, it is important to note that the selection of the injector to be observed or the cylinder to be observed as well as the selection of the measured values assigned to this injector are already outside the control device 110 he follows.

In contrast to this, in the second exemplary embodiment of the invention described below, the measurement data relevant to the selected injection valve is only selected within the control device 110 ,

5 illustrates this second embodiment. It can be seen that measurement data from various injection valves L1, S1 and S2 at any time on the parallel inputs of the analog / digital converter 112 ' on the control device 110 issue. In response to a trigger signal Tr, which is generated in the second exemplary embodiment in exactly the same way as already described above for the first exemplary embodiment, they are in each case in parallel at the input of the analog / digital converter 112 ' The measured values present are read into them and converted into corresponding digital measured values L'1, S'1 and S'2. Only after this analog / digital conversion, according to the second exemplary embodiment, is the selection of the respectively desired measurement values, that is to say characteristic values for the selected injection valve, according to 5 the amount of charge L'1 applied to the first injector. In the second exemplary embodiment too, the selection takes place exclusively within the observation time window described above with reference to the first exemplary embodiment.

If according to 5 the triggering, i.e. the triggering of the analog / digital conversion takes place before the selection, it can nevertheless be assumed that the triggering also takes place within the observation time window.

Independently of, whether the selection of the measured values according to the first or the second embodiment done, can the selected measured values are subsequently evaluated.

However, the selected measured values are only evaluated if these measured values have previously passed a plausibility check. As part of this plausibility check, the actual number of the measured values actually selected during an observation time window is first determined. This actual number is subsequently compared with a predetermined target number of measurements for the same observation time window. In the case of both proposed solutions according to the invention, that is to say for the case that a specification for the control of the injection valves is made, as well as for the case that a specification is made in the sense that no control should take place, the control device knows 110 the expected target number of measured values before the respective observation time window becomes active for a specific cylinder; in the latter case, in which no control is to take place, the target number is of course zero. In the latter case, the target / actual value comparison serves to confirm the torque reduction in the internal combustion engine. This information is important for monitoring purposes that want to avoid unwanted acceleration of a vehicle in which the internal combustion engine is installed.

By the target / actual comparison of the number of measured values per observation time window it is checked whether all Readings actually have been recorded. In this way, possible malfunctions, the during a Measurement occur, are recognized. A use of the selected Readings for An evaluation is therefore only made if the measurement carried out based on the target / actual value comparison was recognized as error-free; otherwise the selected ones Measured values rejected and no evaluation takes place.

A conducted Evaluation primarily serves to a change in time recognizable in the control behavior of the respective injection valves.

such changes can especially from a change of capacity of the actuators of the injection valves result because these and age-dependent change can. Knowledge about such changes can for example for that control parameters, such as those to be applied to the actuators Cargo to the changed capacity adjust so that still or actually one desired Amount of fuel injected from the injectors.

The The invention is preferably implemented by a computer program for the control device. Such a computer program can, if necessary, together with other computer programs for control and / or regulation also from other control units be stored on a computer-readable data carrier. at the disk it can be a floppy disk, a compact disc, a so-called flash memory or act like that. The computer program stored on the data carrier can then be sold as a product to a customer.

Also Is it possible, that the computer program, if necessary, together with other computer programs - without the Using a data carrier - via a electronic communication network, especially the Internet, transferred to a customer and is sold.

Claims (21)

Method for controlling a plurality of fuel injection valves ( 200-1 ... n) an internal combustion engine, comprising the steps: - specifying injection cycles, each with at least one injection event for the individual injection valves ( 200-1 ... n); - control of the injection valves ( 200-1 ... n) assigned actuators ( 210-n ) in response to the requirement; - Measuring values of at least one electrical variable (L1, S1), which indicate the actuation of the actuators ( 210-n ) for the fuel injection valves ( 200-1 ..n) represents; and selecting those measured values which represent the activation of an injection valve selected from the plurality; characterized in that the selection takes place during a predetermined observation time window. Method for controlling a plurality of fuel injection valves ( 200-1 ... n) an internal combustion engine, comprising the steps: - Specify that no injection valve control should take place; and - preferably not selecting a measured value, which represents the failure to control an injection valve selected from the plurality; characterized in that the selection takes place during a predetermined observation time window. Method according to Claim 1 or 2, characterized in that the start time and the end time or the duration of the observation time window ( 8th ) are determined depending on the position of the crankshaft of the internal combustion engine. A method according to claim 3, characterized in that the observation window (B) has a duration or an angular width of 720 ° crankshaft revolutions KW has. A method according to claim 4, characterized in that between two immediately following observation time windows a pause, measured as the angle of crankshaft revolutions, of 720 ° / number of Cylinder of the internal combustion engine is located. Method according to one of the preceding claims, characterized characterized that the start time of the observation window (B) a predetermined amount of time before the first injection event of the injection cycle to be observed. Method according to one of the preceding claims, characterized characterized that all injectors or cylinders the internal combustion engine can be monitored in sequence by selected individually and their respective measured values cyclically or in any other Order can be selected. Method according to one of the preceding claims, characterized characterized that after the end of the observation window the selected measured values are subjected to a plausibility check, whereby the plausibility check follows Steps include: - Determine the actual number of actually while the measured time values selected from the observation time window; - To compare the actual number with a predetermined target number of measurements for the observation time window; and - evaluate the selected measured values if the actual number is equal to the target number is; or - Discard the selected measured values if the actual number does not match the target number. Computer program for a control device for controlling a plurality of fuel injection valves ( 200-1 ... n) an internal combustion engine, characterized by program code which is suitable for carrying out the method according to one of claims 1-8 when it is executed on a computing device, in particular on a microprocessor. Computer program according to claim 9, characterized in that the computer program is stored on a data carrier. Control unit ( 100 ) to control a plurality of injection valves ( 200-1 ... n) actuators assigned to an internal combustion engine via the injection valves ( 210-n ), comprising: - a control device ( 110 ) for specifying injection cycles with at least one injection event each for the individual injection valves ( 200-1 ... n); - an activation device ( 120 ) to control the injection valves via their actuators ( 210-n ) in response to the specified injection cycles; and - a measuring device ( 220-n ) for recording and providing at least one electrical variable (L1, S1) as a measured value, which indicates the actuation of the actuators ( 210-n ) represents; the control device ( 110 ) is designed, in particular in cooperation with the activation device ( 120 ) to select those measured values which represent the activation of a selected injection valve, characterized in that the control device ( 110 ) specifies an observation time window (B) during which the measurement values for the selected injector are selected exclusively. Control unit ( 100 ) to control a plurality of injection valves ( 200-1 ... n) an internal combustion engine, comprising - a control device ( 110 ) to specify that the injection valves should not be actuated, and in this case for selecting preferably no measured value, which represents the failure of the injection valves to be activated, characterized in that the control device ( 110 ) is designed to specify an observation time window (B) during which the selection takes place exclusively. Control unit ( 100 ) according to claim 11 or 12, characterized in that the start time and the end time or the duration of the observation time window (B) is dependent on the position of the crankshaft of the internal combustion engine. Control device according to one of claims 11-13, characterized by a multiplexer ( 122 ), which has at least one of the measuring devices at its signal inputs at the same time ( 220-n ) recorded measured value of an electrical variable (L1, S1, X1) for at least one. Injection valve ( 200-1 ... n) receives and which is configured, each one of these measured values in response to a preferably from the control device ( 110 ) to select the generated control signal in order to then output the measured value at its output. Control unit according to claim 14, characterized in that when at the signal inputs of the multiplexer ( 122 ) at the same time at least one measured value for different injection valves ( 200-1 ...) is present, the control signal includes information about which of the injectors the measured values are to be selected in which observation time window (B). Control unit according to claim 14 or 15, characterized in that when at the signal inputs of the multiplexer ( 122 ) at the same time there are different measured values, in particular charge or voltage values, for an injection valve, the control signal includes information about which of the different measured values should be selected in which observation time window (B). Control device according to one of claims 14-16, characterized in that the output of the multiplexer ( 122 ) with one of the control devices ( 110 ) assigned analog / digital converter ( 122 ) is connected, the analog / digital converter ( 122 ) converts the selected measured values in response to a trigger signal (Tr) analog / digital, and the trigger signal (Tr) is generated in accordance with the specified injection cycles. Control device according to one of claims 11-13, characterized by one of the control device ( 110 ) assigned multiple analog / digital converter ( 112 ' ) for the sequential conversion of several adjacent measuring devices ( 220-n ) provided measured values in response to a trigger signal (Tr); - whereby each of the n inputs of the analog / digital converter ( 112 ' ) a specific electrical measurement variable from a previously determined injection valve is permanently assigned; and - the control device ( 110 ) is designed to select from the analog / digitally converted measured values during the observation time window (B) which it itself specifies, those measured values which represent the activation of the selected injection valve. Control unit according to claim 17 or 18, characterized in that the activation device ( 120 ) the trigger signal (Tr) at the end of a charging or discharging process of the actuator ( 210-n ) of the selected injection valve with electrical charge. Control device according to one of the preceding claims, characterized in that the control device ( 110 ) has: - a counting device for determining the actual number of values actually selected during the observation time window; and a comparison device for comparing the actual number with a predetermined target number of measurements for the observation time window (B); the control device ( 110 ) is designed to evaluate the selected measured values if the actual number corresponds to the target number and to be rejected in the other case. Control device according to claim 20, characterized in that the control device ( 110 ) is designed to evaluate the non-rejected measured values with regard to changes in the behavior of the injection valves and setpoint information for the actuation of the actuators ( 210-n ) for the injection cycles to be adjusted in accordance with these determined changes.