EP1228300B1 - Control system for protecting an internal combustion engine from overloading - Google Patents

Description

The invention relates to a control system for protecting an internal combustion engine against overload, their performance, depending on a performance request characterizing Input signal is set via a power-determining signal (see DE-A-19739564).

Such a control system is known from DE 195 15 481 A1. In this system a desired performance is specified via a selector lever. This will become one Motor speed setpoint for a speed loop and a pitch angle setpoint for calculated a load control level. The engine speed controller calculates from the Control deviation an injection quantity and its difference to the maximum possible Injection quantity. This difference is passed to the load control stage. The load control level controls a variable pitch propeller depending on the pitch angle setpoint, the Injection quantity difference and the engine speed gradient. At the output of the Engine adjusting moment remains with this system, however unconsidered. Changed boundary conditions, for example higher fuel quality, or rapid load increases on the output, cause high engine torque. these can above the values specified by the engine manufacturer and causing damage to the Cause internal combustion engine.

Based on the previously described prior art, the invention is the task based, this in terms of safe protection of the internal combustion engine further.

The object is achieved by a control system in which a difference torque is calculated from the current and a maximum allowable engine torque. The difference moment determines decisively a second signal. The second signal and a first signal determined from the power request are routed to a selection means. About the selection means, the first or second signal is set as a power-determining signal. For the purposes of the invention, a power-determining signal is to be understood as meaning an injection quantity or a control path of a control rod. In an embodiment, it is proposed that the selection means contains a minimum value selection. By means of the minimum value selection, the signal is set as the power-determining signal whose valency is the lowest.
In one embodiment, it is provided that the first signal is determined by means of a first controller or alternatively by means of a function block. The second signal in turn is determined by a second controller. Further embodiments are listed in the subclaims.

The control system according to the invention is designed in such a way that in normal operation, the first signal represents the power-determining signal. The power of the internal combustion engine is determined by the first controller or by a function block depending on the desired performance, ie it is in the speed mode. If the moment at the output of the internal combustion engine exceeds the maximum permissible engine torque, the value of the second signal drops below the value of the first signal. About the selection means is then a change in the dominance to the second controller. The second controller determines the power of the internal combustion engine via the second signal, ie it is in the torque limiting controller mode, hereinafter referred to as MBR mode. Due to the control deviation, the second controller will reduce the torque at the output by reducing the power-determining signal until it falls below the maximum permissible motor torque. Thereafter, a change back to the first controller takes place.
In order to avoid sudden changes in the power-determining signal during a change in the dominance, the two control circuits are coupled together, wherein the integrating portion of the second controller is set or limited depending on the difference torque either to the value of the first signal.

The solution according to the invention and its embodiment offer the advantage that a a rapidly increasing moment on the downforce, for example when re-immersing one Waterjet drive, is specifically responded by the power-determining signal is reduced. As a result, the internal combustion engine is effectively protected against overload.

Another advantage is that the internal combustion engine is easier to tune. As is known, for each internal combustion engine at a test run the individual characteristic values of the internal combustion engine determined, for example, the limit line (DBR curve) of the maximum allowable fuel injection quantity. These applied However, data values are from internal combustion engine to internal combustion engine of the same type different and apply only to the given boundary conditions. In contrast, The invention opens up the possibility that identical data values are used in such a way that the maximum engine torque among all possible Boundary conditions is given. If the measured engine torque is greater than that maximum permissible motor torque, then the second controller performs a correction in the sense of a Reduction of the power-determining signal by.

The control system shown in the invention is in internal combustion engines in common rail Construction, PLD construction (pump-line-nozzle) or conventional construction used.

Figur 1

Ein Systemschaubild

Figur 2

Blockschaltbild erster und zweiter Regler

Figur 3

Blockschaltbild Funktionsblock und zweiter Regler

Figur 4

Blockschaltbild zweiter Regler

Figur 5

Tabelle

Figur 6

Blockschaltbild Berechnung I-Anteil

Figur 7

Blockschaltbild erster Regler

Figur 8

Zeitdiagramm

Figur 9

Programmablaufplan

In the figures, a preferred embodiment is shown. Show it:

FIG. 1

A system diagram

FIG. 2

Block diagram of first and second controller

FIG. 3

Block diagram function block and second controller

FIG. 4

Block diagram second controller

FIG. 5

table

FIG. 6

Block diagram calculation I-component

FIG. 7

Block diagram of the first controller

FIG. 8

time chart

FIG. 9

Program flow chart

1 shows a block diagram of an internal combustion engine with storage injection system (common rail) is shown. This shows an internal combustion engine 1 with a turbocharger and intercooler 2, an electronic engine control unit 11, a first pump 4, a second pump 6, a high-pressure accumulator (rail) 7, injectors 8 connected thereto and a throttle valve 5. The first pump 4 delivers from a fuel tank 3, the fuel via the throttle valve 5 to the second pump 6. This in turn promotes the fuel under high pressure in the high pressure accumulator 7. The pressure level of the high pressure accumulator 7 is detected by a rail pressure sensor 10. From the high pressure accumulator 7 branches lines with connected injectors 8 for each cylinder of the internal combustion engine 1 from.
The electronic engine control unit 11 controls and regulates the state of the internal combustion engine 1. This has the usual components of a microcomputer system, such as microprocessor, I / O devices, buffers and memory devices (EEPROM, RAM). in the memory modules relevant for the operation of the internal combustion engine 1 operating data in maps / curves are applied. The input variables of the electronic engine control unit 11 illustrated in FIG. 1 are: pressure of the cylinder chamber pIST (i), which is measured by means of pressure sensors 9, pressure pCR of the high-pressure accumulator 7, desired power FW, and further input variables, which are designated by the collective reference symbol E. The output variables A of the electronic engine control unit 11 are the drive signals for the injectors 8, corresponding to the start of injection SB and the injection quantity ve, and the drive signal ADV for the throttle valve 5. About the throttle valve 5, the inlet to the second pump 6 is set.

FIG. 2 shows a block diagram of the closed-loop control system. Shown are: a first controller 14, a second controller 15, a selection means 16 and the Internal combustion engine 1 with the injection system. The internal combustion engine 1 drives via a Clutch 13 an engine load 12, for example, a waterjet drive. The tooth angle Phi1 and Phi2 of the clutch 13 are detected by speed sensors 22. From the Tooth angle Phi 1 is the engine speed via the function block Detect / Filter 18 nMOT calculated. This signal is sent to a subtraction point with the reference variable, the engine speed setpoint nMOT (SW), compared. The setpoint nMOT (SW) is set here the input signal indicative of the desired performance.

The function block Capture / Filter 17 turns Phi 1 and 2 from the two tooth angles Phi2 the engine torque MK determined at the output of the internal combustion engine 1. The engine moment MK is compared with a maximum allowable engine torque MK (Max). The Maximum permissible motor torque MK (Max) is determined from the input variables E, eg. B. Engine speed nMOT, supercharger speed, charge air pressure pLL, fuel, exhaust and Cooling water temperature.

As an alternative to the measured engine torque MK this can also by means of a mathematical model can be calculated. For example, the mathematical Model containing a thermodynamic image of the internal combustion engine.

The input variables of the first controller 14 are: the speed difference dnMOT, the engine speed nMOT and a signal ve2 (F). The signal ve2 (F) arises from a second signal ve2 by modifying the second signal ve2 via a delay element 20 and filter 21. In a simpler embodiment, the second signal ve2 may also be routed directly to the first controller 14 or may be guided only via the delay element 20 or the filter 21. The output of the first regulator 14 is the first signal ve 1. This is fed to the selection means 16 and the second regulator 15.
The input variables of the second controller 15 are: the difference torque MK (Diff), the first signal ve 1 and a modified controller mode RM (ver). The signal of the modified regulator mode RM (ver) corresponds in turn to a regulator mode RM delayed by one sampling period. The time delay is effected by means of the delay element 19. The output signal of the second regulator 15 is the second signal ve2. This is performed on the selection means 16 and the delay element 20.
The selection means 16 contains a minimum value selection. By way of the minimum value selection, the first signal ve1 is set as the power-determining signal ve if the first signal ve 1 is less than or equal to the second signal ve2. In this case, the controller mode RM is set to a first value. This corresponds to an operation of the internal combustion engine in the speed mode. As the power-determining signal ve, the second signal ve2 is set when the second signal ve2 is smaller than the first signal ve1. In this case, the controller mode RM is set to a second value. This corresponds to an operation of the internal combustion engine in MBR mode. The output signals of the selection means 16 are the power-determining signal ve and the regulator mode RM. The power-determining signal ve is fed to the injector of the internal combustion engine 1. Under power-determining signal according to the invention, the injection quantity or the control path of a control rod to understand.
The structure of the first regulator 14 will be explained in conjunction with FIG. The structure of the second regulator 15 will be explained in conjunction with FIGS. 4 to 6.

The function of the control system is as follows:

As long as the engine torque MK is significantly smaller than the maximum allowable engine torque MK (Max), the second controller 15 does not intervene in the first controller 14. this will thereby ensuring that the integrating component (I component) of the second regulator 15 the value of the first signal ve1 calculated by the first controller 14 is set. Since that Difference torque MK (Diff) is positive, becomes the integrating portion of the second regulator 15, z. When using a PI controller, with a positive proportional component (P component) added. The second signal ve2 calculated by the second controller 15 is thus larger than that first signal ve 1. Consequently, the internal combustion engine remains in the speed mode. Only when that Engine torque MK continues to increase and the maximum allowable engine torque MK (Max), the integrating operation of the I component of the second regulator 15 becomes started. This allows a smooth transition from the first controller 14 to the second controller 15, since the I-part of the second regulator 15 can now run freely and not more is set. If the second signal ve2 is smaller than the first signal ve 1, it changes the engine from the speed mode to the MBR mode.

The second signal ve2 calculated by the second controller 15 is used to limit the I portion of the first regulator 14 is used. The limitation of the I component of the first regulator 14 takes place but offset in time because of the delay element 20 and the filter 21. It Thus, there is no feedback of the first signal ve1 to the I component of the first controller 14 ago. In this respect, the output of the first regulator 14 and the I component of the first Regulator 14 dynamically decoupled. This will cause unwanted amplification of the Control dynamics effectively prevented. For example, with a quick relief of Internal combustion engine, reduces the output signal of the first controller 14, so the First signal ve 1. Insofar also reduce the I component of the second regulator 15 and the second signal ve2. Without the retarding effect of the filter 21, under some circumstances Also, the I-portion of the first regulator 14 are reduced, resulting in another Reduction of the first signal could lead to ve 1.

Figure 3 shows an alternative embodiment of the block diagram of Figure 2. In difference 2, in this block diagram, the first signal ve 1 via a function block 23 as a function of a desired performance, here accelerator pedal FP calculated. Of the Function block 23 includes the conversion of the accelerator pedal position into the first signal ve 1. Corresponding characteristics including a limitation are provided for this purpose.

The input variables required for the conversion are represented by the reference symbol E, for example engine speed nMOT, charge air pressure pLL, etc.
Another difference is that the second signal ve2 in the block diagram according to FIG. 3 is guided exclusively to the selection means 16. Compared to the figure 2 eliminates the target / actual comparison of the engine speed, since the desired performance is set via an accelerator pedal. The further structure corresponds to that of Figure 2, so that what is said there applies.

Figure 4 shows the block diagram of the second regulator 15. This has an integrating Share on and is exemplified as a PI controller in discrete-time form. In practice The second controller 15 can also be realized as a PID controller or as a PI (DT1) controller. The input variables of the second regulator 15 are: the modified regulator mode RM (ver), the first signal ve 1 and the difference torque MK (Diff). The output of the second Regulator 15 is the second signal ve2. The second regulator 15 has as components one Multiplication 25, a function block calculation I-share 24 and a summation 26th on. Multiplication 25 is used to calculate the P component ve2 (P). On the Function block 24, the I-share ve2 (I) is calculated. The structure and functioning of the function block calculation I-portion 24 will be explained in connection with Figure 5 and 6. The P-component ve2 (P) is calculated from the difference moment MK (Diff) and a Proportional coefficient kp. The proportional coefficient kp can either be set constant or, depending on the engine torque MK and the one sampling period previously calculated value of the second signal ve2, are calculated. Alternatively, too be provided that the proportional coefficient kp as a function of the engine torque MK and the I-portion ve2 (I) previously calculated one sampling period. By the Calculation of the proportional coefficient kp can be the transmission behavior of the second Regulator 15 to different operating conditions, such as different Fuel density or operating point dependent changes in engine efficiency, be adjusted. The dynamic behavior of the second regulator 15 can be optimized if, in the calculation of the kp value, the difference torque MK (Diff) is additionally is taken into account.

ve2   zweites Signal

ve2(P)   Proportional-Anteil (P-Anteil)

ve2(I)   Integral-Anteil (I-Anteil)

As shown in FIG. 4, the second signal ve2 results from the sum of the P component and the I component, summation 26. The following therefore holds for the calculation: ve2 = ve2 (P) + ve2 (I) With:

ve2 second signal

ve2 (P) Proportional component (P component)

ve2 (I) Integral component (I component)

1. Wenn der verzögerte Reglermodus RM(ver) größer oder gleich dem Wert L2 ist, dann ist der Eingang C aktiv. Der Wert L2 ist hierbei konstant auf 1 gesetzt. Der verzögerte Reglermodus RM(ver) ist 1 im Drehzahl-Modus, d. h. im Normalbetrieb der Brennkraftmaschine.

2. Wenn der verzögerte Reglermodus RM(ver) kleiner als der Wert L2 ist, dann ist der Eingang D aktiv. Der verzögerte Reglermodus RM(ver) ist Null im MBR-Modus.

FIG. 6 shows a block diagram for the calculation of the I component ve 2 (I) from FIG. 4. This figure includes the table of FIG. 5. The input variables of the block diagram of FIG. 6 are: the first signal ve 1, the modified controller mode RM (ver) and the difference torque MK (Diff). The output is the I-share ve2 (I) of the second signal ve2. The function block calculation integral portion 24 includes a first software switch 33 and a second software switch 34. The following relationships apply to the switch positions of the first software switch 33:

1. If the delayed controller mode RM (ver) is greater than or equal to L2, input C is active. The value L2 is set constant to 1 here. The delayed controller mode RM (ver) is 1 in the speed mode, ie during normal operation of the internal combustion engine.

2. If the delayed controller mode RM (ver) is less than the value L2, then input D is active. Delayed controller mode RM (ver) is zero in MBR mode.

1. Wenn der Ausgangswert des ersten Softwareschalters 33 größer oder gleich dem Wert L1 ist, so ist der Eingang A aktiv. Der Wert L1 ist positiv. Dieser kann entweder aus dem maximal zulässigen Motor-Moment MK(Max) berechnet werden oder konstant sein, z. B. 150 Nm.

2. Wenn der Ausgangswert des ersten Softwareschalters 33 kleiner als der Wert L1 ist, so ist der Eingang B aktiv.

The following relationships apply to the second software switch 34:

1. If the output value of the first software switch 33 is greater than or equal to the value L1, the input A is active. The value L1 is positive. This can either be calculated from the maximum permissible engine torque MK (Max) or be constant, z. B. 150 Nm.

2. If the output value of the first software switch 33 is less than the value L1, then the input B is active.

The switching positions of the first 33 and second software switch shown in Figure 6 34 correspond to the first row of the table in FIG. 5. In this case, d. H. the first Controller 14 is dominant and the difference torque MK (Diff) is greater than the value L1, are the switch positions C / A active. In these switching positions, the I component corresponds to ve2 (I) of the second signal ve2 the first signal ve1. In other words: the I-share ve2 (I) of the second signal ve2 is set to the value of the first signal ve1. Due to the positive differential torque MK (Diff) also results in a positive P-component ve2 (P). Overall, this results in a second signal ve2 whose value is greater than the first Signal ve 1. About the minimum value selection of the selection means 16 is thus the first Signal ve 1 is set as the power-determining signal ve.

If the difference torque MK (Diff) now drops below the value L1, ie the engine torque of the internal combustion engine develops in the direction of the maximum permissible engine torque MK (Max), then the second software switch 34 changes its switching position, the input B becomes active. This case corresponds to the second row of the table in FIG. 5. In this switching position, the I component ve2 (I) of the second signal ve2 is no longer set to the value of the first signal ve 1 but limited to it by means of the function block minimum value 31. In other words, the I component of the second signal ve2 starts to run freely. On the second input of the function block minimum value 31, the result of a summation 30 is performed. In this case, the first summand corresponds to the value (delay element 32) of the I component ve2 (I) of the second signal ve2 previously determined one sampling period. The second summand arises from the multiplication 29 of a factor F with the sum of the difference moment MK (Diff) at the present and at the preceding time, reference numerals 27 and 28. The factor F becomes dependent on the previously described proportional coefficient kp, a sampling time TA and an integral time TN calculated. The reset time, in turn, is either constant or represents a function of the engine speed nMOT. The following relationships thus apply: F = f (kp, TA, TN) and TN = f (nMOT); TN = constant

From the above, it follows that the transition from the speed mode to MBR mode always takes place with free-running integrating portion of the second regulator 15. As a result, a smooth transition from the first 14 to the second controller 15, without sudden change of the power-determining signal ve guaranteed.

If the current engine torque MK exceeds the maximum permissible engine torque MK (Max), the second signal ve2 becomes due to the negative differential torque MK (Diff) smaller than the first signal ve1. As a consequence, the selection means 16 sets the second signal ve2 as the power-determining signal ve and sets the controller mode RM to the second value, here zero. The change of the modified controller mode RM (ver) causes the first software switch 33 to change position, the input D is now active. This switching position corresponds to the third line of the table in FIG Return to speed mode occurs when the second signal ve2 is greater or less becomes equal to the first signal ve1.

FIG. 7 shows the first regulator 14. This has an integral part and is exemplified as a PID controller in discrete-time form. In practice, the first controller may also be designed as a PI or PI (DT1) controller.
The input variables of the first regulator 14 are: the rotational speed difference dnMOT, the engine rotational speed nMOT and the modified second signal ve2 (F).
The illustrated first controller includes three functional blocks for calculating the P, I and D components, corresponding to reference numerals 37 to 39. About the function block 37 is determined from an input variable EP and the speed difference dnMOT the P-component ve1 (P). From the speed difference dnMOT, a first input signal ve (M) and a second input signal EI, the I-component ve1 (I) is calculated via the function block 38. Here, the I component ve1 (I) is limited to the first input signal ve (M). Function block 39 is used to calculate the D component ve1 (D) from the rotational speed difference dnMOT and an input variable ED. The first input signal ve (M) corresponds to either the signal ve2 (F) or a signal ve1 (KF), depending on which signal has the lower significance. For this purpose, a first function block minimum value 36 is provided. The signal ve1 (KF) in turn is determined from the engine speed nMOT and other input variables via maps 35. The other input variables are shown as Sammetbezugszeichen E. The input quantities E can be, for example, the charge air pressure pLL, etc. All three components are summed via a summation 40 into a common signal ve1 (S). Via the second function block minimum value 41, the signal which has the lowest significance is then selected from this signal ve1 (S) and from the signal ve1 (KF). This signal corresponds to the first signal ve1.

The second signal ve2 calculated by the second controller 15 influences the calculation of the integrating portion ve1 (I) of the first regulator 14. However, due to the filter 21 is the Signal ve2 (F) with respect to the second signal ve2 delayed in time. It is therefore not direct feedback of the output of the first regulator 14 to the integrating component ve1 (I) of the first regulator 14. The output ve1 of the first regulator 14 and the integrating portion ve1 (I) of the first regulator 14 are dynamically decoupled. hereby an undesirable gain of the controller dynamics is effectively prevented. For example, with a quick discharge of the internal combustion engine, the reduced Output signal of the first controller 14, that is, the first signal ve1. In that sense decrease also the I-part of the second regulator 15 and the second signal ve2. Without the delaying The effect of the filter 21 would under some circumstances also be the I component of the first regulator 14 be reduced, which lead to a further reduction of the first signal ve 1 could.

FIG. 8 consists of the subfigures 8A to 8E. Shown are each over time: the modified regulator mode RM (ver) (FIG. 8A), the engine torque MK (FIG. 8C), the first ve1 and second signal ve2 (FIG. 8D) and the power-determining signal ve (FIG 8E). In FIG. 8B, the switching positions of the first 33 and second software switches 34 are shown shown at the respective times. In Fig. 8C, two are parallel to the abscissa Boundary lines MK (Max) and GW shown. The difference between these two Boundary lines corresponds to the value L1. The difference torque MK (Diff) results from the respective difference of the curve with the points A to F to the maximum permissible engine torque MK (Max). In FIG. 8D, the solid line is the curve of the second signal ve2. The first signal ve 1 is shown as a dashed line shown.

ve2   zweites Signal

ve1   erstes Signal

ve2(P)   P-Anteil zweites Signal

The procedure of the method is as follows: at time t1 it is assumed that the internal combustion engine is operated in the speed mode. In this mode, the first signal ve1 calculated by the first controller 14 is set by the selection means 16 as a power-determining signal ve. The level shown in FIG. 8E and the profile of the power-determining signal ve thus corresponds to the value of the first signal ve 1. The controller mode RM is set by the selection means 16 to a first value, here one. The two software switches 33 and 34 are in the C / A position. In this switching position, the I component ve2 (I) of the second signal ve2 corresponds to the value of the first signal ve1. In other words, the I component ve2 (I) of the second signal is set to the value of the first signal ve1. At time t1 there is a positive difference torque MK (Diff). This also results in a positive P component ve2 (P) of the second regulator 15. The second signal ve2 is calculated as follows: ve2 = ve1 + ve2 (P) With:

ve2 second signal

First signal

ve2 (P) P component second signal

As shown in FIG. 8D, the value of the second signal ve2, point J, is above the Value of the first signal ve1, point G. For the further course it is assumed that the first signal ve 1 remains constant.

At time t1 it is now assumed that the engine torque MK at the output the internal combustion engine increases, d. H. the curve in Figure 8C changes in the Point A in the direction of point C. Due to the decreasing differential torque MK (Diff), the P component ve2 (P) of the second signal ve2 will also decrease. The 1 share ve2 (I) of the second signal ve2 is still at the value of the first signal ve 1 set. The calculated value of the second signal ve2 is therefore above the first one Signal ve1, d. H. at a greater value. At point B of FIG. 8C, this is Difference torque MK (Diff) is equal to the value L 1. When this line is exceeded, it changes Software switch 34 its switching position. In FIG. 8B this is with the change of Switch positions of C / A and C / B are shown. From this point on, the I component ve2 (I) of the second signal ve2 is no longer set to the value of the first signal ve 1, but instead limited only to the value of the first signal ve 1. The integrating part of the second Regulator 15 thus begins to run free from this time.

At time t2, a difference torque MK (Diff) results from zero. It follows that the P component ve2 (P) of the second signal ve2 is also zero. At this time corresponds to the value of the second signal ve2, the value of the first signal ve1, point K in Figure 8D. If the difference torque MK (Diff) exceeds the maximum permissible motor torque MK (Max), this causes a sign change of the differential torque MK (Diff). It follows that the second signal ve2 now has a smaller value as the first signal ve 1. In response, the selection means 16 changes the Regulator mode RM from 1 to 0 and sets as the power-determining signal ve the second Signal ve2. In addition, the two software switches 33 and 34 change their switching position to D / B. In the period t2 to t4 results due to the assumed course of the Differential torque MK (Diff) a corresponding course of the second signal ve2, according to the curve K to N. Since the engine now in MBR mode is operated, corresponds to the course of the power-determining signal ve the Course of the second signal ve2.

At time t4, it is now assumed that the value of the second signal ve2 corresponds to the value of the first signal ve1. The selection means 16, due to the selection of the minimum value, sets the regulator mode RM back to the first value, here one, and sets the first signal ve1 as the power-determining signal ve. From time t4, the course of the power-determining signal ve thus corresponds to the course of the first signal ve1, ie ve remains constant, as shown in FIG. 8E. Due to the change of the controller mode RM, the switching positions of the two software switches 33 and 34 change to C / B.
In point E, the difference torque MK (Diff) again corresponds to the value L1. As a result, the switching position of the second software switch 34 changes, ie the two software switches 33 and 34 now assume the switching position C / A. In this shaft position, the I-component ve2 (I) of the second signal ve2 is set to the value of the first signal ve 1. Corresponding to the further course of the difference torque MK (Diff), a curve according to the curve N to O results for the second signal ve2. At time t5, the time period considered is ended.

FIG. 9 shows a program flow chart of the method according to the invention. In step S1, the controller mode RM is initialized to 1, since there is no engine torque at the start of the internal combustion engine. In the initial state, the internal combustion engine is operated in the speed mode. In step S2, the first controller is set as dominant, ie the first signal ve1 is set as the power-determining signal ve. In step S3 and S4, the first signal ve 1 is calculated and the current engine torque MK is read. Thereafter, at step S5, a difference torque MK (Diff) is calculated from the current engine torque MK and a maximum allowable engine torque MK (Max). In step S6, it is checked whether the regulator mode RM is 1, that is, whether the internal combustion engine is still in the rotational speed mode. If this is not the case, ie the internal combustion engine is in MBR mode, the steps S 16 to S22 are run through. If the test shows that the internal combustion engine is operated in the rotational speed mode, the query is made at step S7 as to whether the differential torque MK (Diff) is greater than the value L1.
If the test result is positive, the I-component ve2 (I) of the second signal ve2 is set to the value of the first signal ve1, step S8. If the test result is negative in step S7, the calculation of the I-component ve2 (I) of the second signal ve2 is activated, step S9. In step S 10, the I-component ve 2 (I) of the second signal ve 2 is limited to the value of the first signal ve 1. At step S 11, the P component ve 2 (P) of the second signal ve 2 is calculated as a function of the difference torque MK (Diff) and a proportional coefficient kp. In step S12, the second signal ve2 is determined via the addition of the P and I components. Thereafter, at step S13, it is checked whether the second signal ve2 is smaller than the first signal ve1. If this is not the case, then the program branches to point A. If it is determined in step S 13 that the value of the second signal ve 2 is smaller than the value of the first signal ve 1, then via the selection means 16, the regulator mode RM to a second Value, here zero, set. By means of the selection means 16, the second signal ve2 is now set as the power-determining signal ve, ie the second controller 15 is dominant. Thereafter, the program flow branches to the point A with the recalculation of the first signal ve1.

If it is determined in step S6 that the internal combustion engine is in MBR mode, thus, at step S16, the calculation of the I-term ve2 (I) of the second signal ve2 activated. The I component is limited to the value of the first signal ve1, step S 17. Thereafter, the P-content is calculated as described above, step S 18. From the P and I component, the second signal ve2 is determined in step S19. In step S20 becomes checks whether the value of the second signal ve2 is smaller than the value of the first signal ve 1. If this is the case, the program flowchart branches to point A. If negative Test result, d. H. the second signal ve2 is not smaller than the first signal ve1 becomes the Regulator mode RM to a first value, here 1, set. Thereafter, at step S22, as power-determining signal ve the first signal ve 1 set, d. H. the first regulator 14 is dominant.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

turbocharger

3

Fuel tank

4

first pump

5

throttle valve

6

second pump

7

High-pressure accumulator (rail)

8th

injector

9

pressure sensor

10

Rail pressure sensor

11

Electronic engine control unit

12

engine load

13

clutch

14

first controller (speed)

15

second controller (moment)

16

selection means

17

Function block Capture / Filter

18

Function block Capture / Filter

19

delay

20

delay

21

filter

22

Speed sensors

23

function block

24

Function block calculation I-share

25

multiplication

26

summation

27

delay

28

summation

29

multiplication

30

summation

31

Function block minimum value

32

delay

33

first software switch

34

second software switch

35

maps

36

first function block minimum value

37

Function block Calculation P-component

38

Function block calculation I-share

39

Function block calculation D-component

40

summation

41

second function block minimum value

Claims (29)

1. Control system for protecting an internal combustion engine (1) against overloading, the power of which internal combustion engine (1) is set by means of a power-determining signal (ve) as a function of an input signal (FW) which characterizes the power request, characterized in that a differential torque (MK(Diff)) is calculated from the current engine torque (MK) and a maximum permissible engine torque (MK(Max)), the differential torque (MK(Diff)) decisively determining a second signal (ve2) (ve2=f(MK(Diff))) , a first signal (ve1) being determined from the input signal (FW) which characterizes the power request and the first signal (ve1) or second signal (ve2) being set as a power-determining signal (ve) using a selector means (16).
2. Control system according to Claim 1, characterized in that the selector means (16) contains a minimum value selection, the first signal (ve1) is set as a power-determining signal (ve) (ve=ve1) if the first signal (ve1) is less than or equal to the second signal (ve1=ve2), and the second signal (ve2) is set as a power-determining signal (ve) (ve=ve2) if the second signal (ve2) is smaller than the first signal (ve1) (ve2<ve1).
3. Control system according to Claim 2, characterized in that a controller mode (RM) is set to a first value (RM=1) by means of the selector means (16) if the first signal (ve1) is dominant (ve=ve1), and is set to a second value (RM=0) if the second signal (ve2) is dominant (ve=ve2).
4. Control system according to Claim 1, characterized in that the first signal (ve1) is determined from an engine speed (nMOT), a rotational speed difference (dnMOT) and the second signal (ve2) by means of a first controller (14).
5. Control system according to Claim 1, characterized in that the first signal (ve1) is determined from an accelerator pedal value (FP), and further input variables, in particular a charge air pressure (pLL), by means of a functional block (23).
6. Control system according to Claim 1, characterized in that the second signal (ve2) is additionally determined from the controller mode (RM) and the first signal (ve1) by means of a second controller (15) .
7. Control system according to Claim 4 or 5, characterized in that the first signal (ve1) is fed to the second controller (15).
8. Control system according to Claim 6, characterized in that the output of the second controller (15) is fed to the first controller (14) and to the selector means (16).
9. Control system according to Claim 8, characterized in that a delay element (20) and/or a filter (21) are arranged in the signal path from the second controller (15) to the first controller (14).
10. Control system according to Claims 4 and 9, characterized in that a modified second signal (ve2(F)) which is derived from the second signal (ve2) by means of the delay element (20) and/or filter (21) constitutes an input variable of the first controller (14).
11. Control system according to one of the preceding claims, characterized in that the output of the selector means (16) is fed to the second controller (15).
12. Control system according to Claim 11, characterized in that a delay element (19) is arranged in the signal path from the selector means (16) to the second controller (15).
13. Control system according to Claims 6 and 12, characterized in that a modified controller mode (RM(ver)), which is determined by means of the delay element (19), constitutes an input variable of the second controller (15).
14. Control system according to one of the preceding claims, characterized in that the second controller (15) is embodied at least as an I controller, said controller calculating an I component (ve2(I)), and the second signal (ve2) being calculated from the I component (ve2(I)) (ve2=f(ve2(I)).
15. Control system according to Claim 14, characterized in that the I component (ve2(I)) is set to the value of the first signal (ve1) (ve2(I)=ve1) if the differential torque (MK(Diff)) is greater than or equal to a value (L1) (MK(Diff)=L1) and the controller mode (RM) or the modified controller mode (RM(ver)) corresponds to the first value (RM=1, RM(ver)=1).
16. Control system according to Claim 14, characterized in that the I component (ve2(I)) is limited to the value of the first signal (ve1) if the differential torque (MK(Diff)) is smaller than the value (L1) (MK(Diff)<L1) or the controller mode (RM) or the delayed controller mode (RM(ver)) corresponds to the second value (RM=0, RM(ver)=0).
17. Control system according to Claim 15 or 16, characterized in that a readjustment time (TN) is included in the calculation of the I component (ve2 (I) ) , and the readjustment time (TN) is either constant (TN=const.) or constitutes a function of the engine speed (nMOT) of the internal combustion engine (1) (TN=f(nMOT)).
18. Control system according to Claim 15 or 16, characterized in that the value (L1) is calculated as a function of the maximum permissible engine torque (MK(Max)) (L1=f(MK(Max))).
19. Control system according to Claim 15 or 16, characterized in that the value (L1) is calculated as a function of the engine speed (nMOT) (L1=f(nMOT)).
20. Control system according to Claim 14, characterized in that the second controller (15). is additionally embodied as a P controller, said P controller calculates a P component (ve2(P)), and the second signal (ve2) is additionally calculated from the P component (ve2(P)) (ve2=f(ve2(P)).
21. Control system according to Claim 20, characterized in that the P component (ve2(P)) is calculated as a function of the differential torque (MK(Diff)) and a proportional coefficient (kp) (ve2(P)=f(MK(Diff), kp)).
22. Control system according to Claim 21, characterized in that the proportional coefficient (kp) is constant (kp=const.) or is calculated as a function at least of the engine torque (MK) or as a function at least of the differential torque (MK(Diff)).
23. Control system according to Claim 21, characterized in that the proportional coefficient (kp) is calculated at least as a function of the second signal (ve2) or as a function of the I component (ve2(I)).
24. Control system according to Claim 4, characterized in that the first controller (14) is embodied at least as an I controller, the latter calculating an I component (ve1(I)) as a function of a first input signal (ve(M)), a second input signal (EI) and the rotational speed difference (dnMOT).
25. Control system according to Claims 4 and 24, characterized in that the second controller (14) additionally has a first function block minimum value (36), a second function block minimum value (41) and characteristic diagrams (35).
26. Control system according to Claims 24 and 25, characterized in that the first input signal (ve(M)) is determined by means of the first function block minimum value (36) from the second signal (ve2) or from the modified second signal (ve2(F)) and a characteristic diagram signal (ve1(KF)) calculated by means of the characteristic diagrams (35).
27. Control system according to Claim 26, characterized in that the characteristic diagram signal (ve1(KF)) is calculated as a function of the engine speed (nMOT) and further input variables (E), in particular charge air pressure (pLL) .
28. Control system according to Claim 27, characterized in that the first signal (ve1) is determined by means of the second function block minimum value (41) from the characteristic diagram signal (ve1(KF)) and at least from the I component (ve1(I)).
29. Control system according to one of the preceding claims, characterized in that the engine torque (MK) is calculated from measured input variables by means of a mathematical model.

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