JPH08246914A - Method and equipment for controlling car driving unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the maximum rotation speed of an engine by deciding the setback of the output set of an engine just before the operation variable of a vehicular drive unit reaches the maximum threshold value and restricting the operation variable. SOLUTION: A measuring device 14 detects the operation degree βof the operation element set by a driver and inputs in a driver desired decision unit 20. While, a measuring device 18 detects an engine rotation speed and inputs to a restriction controller 28. The unit 20 calculates a driver desired target value while considering the operation variable such as an engine rotation speed and throw in gear step running speed by the operation degree β. The restriction controller 28 finds out the restriction target value for the operation variable to be restricted based on the gradient of the engine rotation speed and the desired target value from the unit 20. The restriction target value is compared with the desired target value by the minimum value selction step 24 and either smaller value is given to an adjust unit 34. An output decision element 38, namely throttle valve position is adjusted following to the target value so that the engine rotation speed is varied in a step shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for controlling a vehicle drive unit.

[0002]

2. Description of the Prior Art A method of this kind and a device of this kind are known from DE-A 36 18 844. In that patent, a method for limiting the rotational speed of a drive unit is described in the example of an internal combustion engine. A rotation speed threshold value is provided to limit the rotation speed, and when the rotation speed of the drive unit exceeds this threshold, the threshold value for controlling the drive unit is the maximum allowable rotation speed per unit time. Limited to not exceed change. In this case, the maximum rotational speed change per unit time is preferably linearly controlled from the maximum value given by the dynamic behavior of the drive unit below the rotational speed threshold value to a value 0 at a given maximum rotational speed. It In one use case, the known method results in unsatisfactory results, due to the fact that the predetermined maximum rotational speed change is a function of the gear stage or road speed input and also of the vehicle load and the road grade. Is known to show. In a particularly known way, in order to ensure that the maximum rotational speed is limited, the starting or starting rotational speed threshold of the control is
It is necessary to set it well before reaching the maximum rotation speed. This means that the rotational speed limitation takes place well below the maximum engine rotational speed.

[0003]

SUMMARY OF THE INVENTION It is therefore an object of the invention to provide a drive unit rotational speed limiting means which avoids the disadvantages of the known methods existing in certain applications.

[0004]

The method for limiting the operating variables of a vehicle drive unit according to the invention avoids the above-mentioned drawbacks.

The basic idea of the limitation according to the invention is that the setback of the output setting of the drive unit is determined immediately before the maximum threshold is reached, which setback limits the operating variables. Therefore, the limitation before the maximum threshold is reached and thus far before the engine output is avoided.

By using a controller with at least one proportional part and at least one integral part, a stable and steady hold of the maximum operating variable is achieved after the maximum threshold is reached.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings.

In FIG. 1, a control unit for controlling the drive unit of the vehicle is shown at 10. In a preferred embodiment, the control unit 10 has at least one
It consists of two microcomputers and controls the output of an internal combustion engine (not shown). However, the advantages of rotational speed limitation described below are achieved in combination with other drive units, especially electric motors.

The control unit 10 is supplied with an input line 12 from a measuring device 14 for detecting the degree of operation of an operating element for setting an output operable by a driver, as well as for detecting the rotational speed of the drive unit. The input line 16 is supplied from the measuring device 18 of FIG. In this case, the input line 12 communicates with the driver desire determining unit 20, and the operation degree β detected in the driver desire determining unit 20 may be the engine rotation speed, the applied gear stage,
It is converted into a driver desired target value NF Fahrer for setting the output of the drive unit in consideration of driving variables such as traveling speed. In a preferred embodiment, this is done using a predetermined characteristic curve or a predetermined set of characteristic curves. In this case, in the preferred embodiment, the driver desired setpoint indicates the setpoint for the position of the throttle valve of the internal combustion engine. In another preferred embodiment, the driver setpoint value is a measure for the torque provided by the drive unit or the output to be generated or the engine load (air quantity) to be adjusted. The desired driver target value is provided via line 22 to a minimum value selection stage 24. The minimum value selection stage 24 is further supplied by a line 26 from a limiting controller 28. A limit controller 28, the function of which will be described later, is supplied with an input line 16 and, in the preferred embodiment, a line 30 out of line 22. The output line 32 of the minimum selection stage 24 leads to a regulating unit 34, which via its output line 36 influences the output of the drive unit 38, a throttle valve of the internal combustion engine in a preferred embodiment. Adjust.

As will be explained below, the limit controller 28 determines a limit value for the operating variable to be limited, preferably a target value NFBEG when or just before the maximum rotational speed of the drive unit is reached. Target value NF
BEG has a maximum value of 100% when the limit control is not performed. The limit target value indicates a value like the driver's desired target value. Both values are compared with each other in the minimum selection stage 24 and the smaller value is given to the adjusting unit 34 via the line 32. The adjusting unit 34 then adjusts the output determining element 38 according to the setpoint value provided within the open-loop or closed-loop control circuit.
In the preferred embodiment, the throttle valve position is controlled in the adjusting unit 34. In addition to this preferred mode of use, the adjustment unit 34 may perform torque control, rotational speed control, power control or just adjustment of any of these variables.

A preferred embodiment of the limit controller 28 is shown in FIG.
Is shown in the block circuit diagram of FIG. The limit controller 28 has a controller 100 with at least one proportional portion 102 and at least one integral portion 104. Both parts are supplied via line 16 with a variable to be limited, in a preferred embodiment a measure for the engine speed. Furthermore, both parts have input lines 106 and 108, which combine the proportional and integral parts with the memory unit 110,
Stored in the memory unit 110 is a set maximum value for the variable to be limited, in the preferred embodiment the maximum rotational speed value Nmax. The output line 112 of the proportional part 102 and the output line 114 of the integrating part 104 are supplied to the adding stage 116. The output line 118 of the summing stage 116 leads to the maximum limiting unit 122 via a switching element 120, the output line of the maximum limiting unit 122 being shown by line 26. Switch element 120
Is switched between line 118 and line 126 in response to a signal provided on line 124. The line 126 is supplied from another memory element 128, and the maximum value of the limit target value when the limit control is not performed is stored in the memory element 128. Line 124 leads from threshold stage 130 to switch element 120. Threshold stage 130 is supplied via line 16 with the variable to be controlled, namely the engine speed. In the preferred embodiment, shown in phantom in FIG. 2, the threshold of threshold stage 130 is set by calculation unit 134 via line 132. A limit value, that is, the maximum rotation speed Nma
x is provided and via line 138 the variable to be limited, namely the gradient of the engine speed, is provided. Integral part 1 of controller 100 in addition to lines 16 and 108
A line 140 is supplied to 04 from the calculation unit 142. The initial value of the integrator 104 is determined in this calculation unit. To advantageously supplement the limitations of the present invention,
As shown by the broken line, the driver desired target value NF Fahrer is supplied to the calculation unit 142 via the line 30, and the line 144 is supplied from another calculation unit 146. The calculation unit 146 is supplied on the one hand with the line 30 and on the other hand with the line 148 from the differentiation stage 150. The differential stage 150 forms the gradient of the engine speed that is supplied to the differential stage 150 via the variable or line 16 to be limited.

The basic idea of the limitation according to the present invention is that the allowable limit value of the variable to be limited, that is, the maximum rotation speed Nma.
When the engine load, engine torque or engine output is stepped or quasi-stepped when the engine load, engine torque or engine output reaches or approaches x, preferably when the engagement value NStart, which lies just below the limit value, is reached. It is to be set to a specific value depending on the direction. This particular value forms the initial value of the limit control that prevents the limit value from being exceeded. In order to change the engine load, the engine torque or the engine output in steps, it is particularly advantageous to change the setpoint value essentially provided by the driver in a quasi-step or step-wise limiting purpose. Depending on the embodiment, this set value indicates a torque target value, a throttle valve position target value, an air amount target value, an output target value, and the like.

In the embodiment described below, the setback of the output setting of the drive unit is performed by setting the initial value of the integrator of the limiting controller. In another advantageous embodiment, this setback is suitably performed by directly affecting the controller output signal, the setting signal supplied to the adjusting unit, the driver desired setpoint or the output signal of the adjusting unit. I know.

In the preferred embodiment shown in FIG.
A proportional-integral controller 100 is used to limit the speed of rotation. The engine speed is the engagement threshold NStar
When t exceeds, the output signal of the threshold stage 130 causes the switching element 120 and the output of the controller 100 to be the limiting controller 2.
8 output line 26 to switch. The proportional portion 102 generates an output signal NFP proportional to the difference between the maximum rotation speed Nmax and the engine rotation speed Nmot. The integral part 104 of the controller 100 produces an output signal NFI, which in the preferred embodiment has an initial value NFIStart and a maximum rotational speed Nmax.
And the sum of the difference in engine speed Nmot and the time integral. In the summing stage 106, the sum of both output signals NFI and NFP is formed and the limiting unit 12
2 is limited to a maximum value of 100% and is fed to the minimum value selection stage 24. This engagement rotation speed threshold NSt
When it is below art or below this rotational speed threshold, the switch element 120 is in the position indicated by the dashed line. In this case, the controller 100 is disconnected from the output line 26. In this case, the output line 26 is supplied with the signal from the memory element 128, which is 100%.
Shows the maximum signal value of. This is because the limit controller 28 is at 10 as long as the engine speed is below the engagement threshold.
This means that an output signal of 0% is given. At this time, there are no restrictions. When the engine speed reaches the engagement threshold, the integral part 104 of the controller 100 is set to an initial value NFISStart. This initial value is set to a fixed value (eg 30%) in the preferred embodiment and is stored in the calculation unit 142. By this means, there is a reduction in the engine power that acts immediately via the integral part and thus a limitation on the rotational speed that acts immediately. When the initial value NFISstart is correctly selected, the engine load, torque or output setback obtained thereby is sufficient to keep the maximum rotational speed Nmax constant. In this case, the limiter 10
It is necessary to make a finer correction for 0, and the value of the amplification factor of the controller (the proportional constant of the proportional portion 102 and the integral constant of the integral portion 104) is selected to be relatively small, so that the controller vibrates. There is nothing to do.

Since the output of the drive unit required to keep the maximum rotational speed constant depends on the load on the drive unit and thus especially on the engaged gears, in an advantageous supplementary form the integral part in all operating conditions is used. The integral part is calculated from the rotational speed gradient and the driver desired setpoint to obtain the correct initial value of This is done by the following equation.

NFIStart = NFFahrer-K
2 * dN / dt (K2: constant, N: rotation speed) NFISstart is calculated in the calculation unit 146. The calculated value is sent to unit 1 via line 144.
42.

Another advantageous supplementary aspect of the basic idea of the rotational speed limitation according to the invention is that the setback is carried out in several stages rather than in one stage. When the output provided by the drive unit at the beginning of the control is set back in one stage, and therefore the output is changed abruptly, there is an abrupt release of tension in the drive train, which causes mechanical vibrations and corresponding It appears as a reduction in driving comfort. This effect can be avoided when reducing in multiple stages. For this purpose, according to the present invention, the actual desired driving target value NF Fahrer is set in the calculation unit 142.
It is designed to lead the initial value NFISstart of the integration part to the initial value calculated from the calculation unit 146 in a short time (hundreds of milliseconds to several seconds) in at least two stages.

Especially when utilizing the rotational speed limitation according to the invention, when controlling the air supply to the internal combustion engine via the position of the throttle valve, the final engagement speed of the throttle valve and the cumulative effect of the intake pipe make a control engagement. There is a time between the start of the engine and the engagement of the power setting of the internal combustion engine. Therefore,
It is advantageous to start the control engagement before reaching the maximum rotational speed Nmax in order to avoid overshoot. For this purpose, a predetermined engagement rotational speed NStart is used, which controls the start of the controlled engagement in the threshold stage 130. This starting rotational speed may be set to a fixed value or, in a preferred embodiment, may be determined according to the actual operating conditions. It has been found suitable to determine the starting rotational speed from the maximum rotational speed and the engine rotational speed gradient by the following equation.

NStart = Nmax-K3 * dN / dt (K3: constant, N: rotational speed)

In addition, hysteresis is provided in order to avoid frequent activation and deactivation of the restriction. As a result, the maximum rotation speed limit is set to a predetermined rotation speed (for example, 2
(00 rpm) and the final rotation speed is not reached.

Another embodiment, represented as a computer program for limiting the rotational speed according to the invention, is shown in the flow chart of FIGS.

The program part shown in FIG. 3 shows the determination of the set value for the output control of the internal combustion engine. Thus, after the program portion has started at a predetermined time, in a first step 200 at least the degree of operation β of the accelerator pedal and possibly other variables such as engine speed, running speed, gear position etc. are read out, which follow. In step 202, a target value NFFahrer is determined using a predetermined characteristic curve or a predetermined characteristic curve group, based on the degree of operation β and possibly other operating variables. This target value is indicative of driver preference and, in some embodiments, a variable that determines engine load, such as a throttle valve target position or air amount target value. In step 204 after step 202, the setpoint value NFBEG formed by the limiting controller is read and the following step 2
At 06, the target value NFS supplied to the adjusting unit
ol is formed. This is the driver's desired target value NFF
This is performed by selecting the minimum value from the ahrer and the target limit value NFBEG. Subsequently, in step 208, the setting element for determining the engine load within the control circuit is adjusted on the basis of the desired value NFSoll and the actual value NFist. After step 208, the program portion ends and after a predetermined amount of time the program portion is repeated.

The determination of the limit control setpoint NFBEG is shown in the flow charts of FIGS.

In the first step 300 after the start of the program portion shown in FIG. 4, in the engine speed Nmo
t, the maximum rotational speed Nmax and, in a preferred embodiment, the driver desired setpoint value NF Fahrer is read. Subsequently, in step 302, a gradient dNmot / dt of the engine speed is formed from the actual measured value and the measured value determined in the previous program run. Subsequently, in step 304, the engagement rotational speed NStart is the maximum rotational speed Nmax and the rotational speed gradient dNmot / determined in step 302.
It is determined from dt. In the preferred embodiment, this is determined by the above equation. In the subsequent determination step 306, it is determined whether the actual engine rotation speed Nmot is equal to or higher than the engagement start rotation speed NStart. Within steps 304 and 306, it is not necessary to use an advantageously set hysteresis and use conventional filter means to prevent the limit from being activated by a single disturbance signal. Let's do it. When it is determined in step 306 that the engine rotation speed is equal to or lower than the engagement rotation speed NStart, the limit target value NFBEG is determined in step 308.
Is set to 100% or the maximum value and the program part ends. When the engine speed reaches or exceeds the engagement speed, step 310
The rotation speed limit control is executed by the
BEG is maximum rotation speed Nmax, engine rotation speed Nm
ot, the engine speed gradient dNmot / dt and the driver desired setpoint value NFFahrer are determined as described below with reference to FIG. After the program part is finished, the program part is repeated after a predetermined time elapses.

Control target value NFBE in step 310
The determination of G is detailed in the flow chart of FIG. In the first step 400 after the program part starts in step 310, the engine speed Nmo
t, maximum rotation speed Nmax, rotation speed gradient dNmot /
dt as well as the driver desired setpoint value NFFahrer are read and according to the mark appropriately set in the following step 402 it is determined whether the limit controller is first called or the control unit is executing limit control. . If the limiting control is first called, step 404 will determine the initial value NFISta of the integrator.
rt is determined. In the preferred embodiment, this is the driver desired setpoint NF Fahrer according to the above equation.
And the rotational speed gradient dNmot / dt. In the following step 406, the output signal NFI of the integrator is set to the initial value determined in step 404. In this case, in an advantageous embodiment, the output signal of the integrator is not set to the initial value in one stage but to the initial value in a plurality of stages. The determined initial value of the integrator forms the limiting target value NFBEG. If the control unit is under rotational speed limitation control, step 410 is executed after step 402. In step 410, the output signal values of the proportional and integral parts are calculated based on the control function. In the following step 408, the limit setpoint value NFBEG is determined from the sum of the proportional value NFP and the integral value NFI and the program part ends.

The operation of limiting the rotational speed according to the invention is shown in a time diagram in FIG. Here, FIG. 6a shows an example of the course of the engine speed, while FIG. 6b shows the course of the set value NFSSoll for adjusting the engine output. Finally, FIG. 6c shows an example of the passage of the throttle valve position α over time. The acceleration process is shown in FIG. When the accelerator pedal is operated, the driver desired target value and thus the set target value NFSoll increases as shown in FIG. 6b as long as the engine speed is within the engagement threshold NStart as shown in FIG. 6a. The throttle valve position α shown in FIG. 6c shows the corresponding course in this operating range. It is assumed that the engine rotation speed Nmot exceeds the engagement threshold value NStart at time T0. At this time, the limit control is started by the present invention, the integral value is set, and thus the set value NFSSoll is reset stepwise to a predetermined value in one step or in multiple steps. The corresponding response at throttle valve position α can be seen from FIG. 6c. A step or quasi-step reset to a lower throttle valve position is performed. The limit control is performed after the time point T0.

In summary, the rotational speed limit according to the present invention allows the engine load to be abruptly or nearly abruptly brought to an initial value which is a function of operating parameters when the engagement rotational speed threshold near the maximum engine rotational speed is reached. Can be said to be limited to. In short, steady-state control of the engine load is carried out as a function of the engine speed and the maximum permissible engine speed, starting from the above initial value.

In addition to limiting the rotational speed, the method according to the invention can also be used for limiting the running speed, torque, engine power, engine load, etc. In these use cases,
Instead of the engine speed, the variables to be respectively limited are also evaluated.

[0029]

According to the present invention, it is particularly significant that the setback of the output setting, that is, the initial value of the limit control is determined as a function of the gradient of the operating variable. This requires only a small number of application parameters.
In particular, the limits are independent of the gears that have been engaged, and also of the load of the vehicle and the uphill or downhill of the road. Furthermore, it is advantageous that this limitation can be implemented even when the gear stage is not engaged.

An advantageous supplementary aspect of the limitation according to the invention is that the setback of the output setting is carried out in multiple stages rather than in one stage. This has the advantageous effect that no mechanical vibrations occur in the drive train of the vehicle at the beginning of the control, and thus the comfort of travel is significantly improved.

It is particularly advantageous that the setting of the initial value at which the limiting engagement must be started at that time is a function of the slope of the operating variable to be limited. This avoids overshoots exceeding the maximum value and takes into account the delay between the change of the setpoint value and the activation of the limit engagement.

In the preferred use of the internal combustion engine, it is particularly advantageous for the limitation according to the invention to be carried out by stepwise control of setting elements which influence the air supply to the internal combustion engine. As a result, it is advantageous that fuel is continuously injected into all cylinders of the internal combustion engine and that the engine output can be continuously controlled. Excessive emissions emissions problems, catalyst damage problems and unpleasant engine operation are thereby avoided.

It is particularly advantageous when the limit according to the invention is used for limiting the rotational speed of internal combustion engines. Furthermore, it is also advantageous to use it for limiting the running speed, torque or engine output.

[Brief description of drawings]

1 is an overall block circuit diagram of a control unit of a vehicle drive unit for a preferred embodiment of rotational speed control.

FIG. 2 is a block circuit diagram of a preferred embodiment of a rotational speed limit controller.

FIG. 3 is a flow chart of a computer program for implementing the preferred embodiment of the rotational speed limit controller.

FIG. 4 is a detailed flow chart of the steps of determining a limit control target value NFBEG in a computer program for carrying out the preferred embodiment of the rotational speed limit controller.

FIG. 5 is a detailed flow chart of the rotational speed limit control steps in a computer program for implementing the preferred embodiment of the rotational speed limit controller.

6 is a time diagram of the actuation of the essential operating variables of the drive or control unit in the rotational speed limitation according to the invention, FIG. 6a showing the time course of the rotational speed of the engine, FIG. 6b the setpoint NFSoll. FIG. 6b shows the time course of the throttle valve position, and FIG. 6b shows the time course of the throttle valve position.

[Explanation of symbols]

10 control units 12, 16, 22, 26, 30, 32, 36; 106,
108, 112, 114, 118, 124, 126, 1
32, 136, 138, 140, 144 Line 14 Manipulation degree measuring device 18 Rotational speed measurement value 20 Driver desire determination unit 24 Minimum value selection stage 28 Limiting controller 34 Adjusting unit 38 Setting element 100 Controller 102 Proportional part 104 Integral part 110 Memory unit 116 Addition stage 122 Maximum limit unit 128 Memory element 130 Threshold stage 134 Calculation element 142, 146 Calculation unit 150 Differentiation stage N Rotational speed NFBEG Rotational speed limit control target value NFFaher driver desired target value NFI Integral partial output signal NFirst rotation speed Actual value NFIStart Integral partial initial value NFSSoll rotational speed target value NFP Proportional partial output signal Nmax Maximum rotational speed Nmot Engine rotational speed NStart Rotational speed engagement threshold α Throttle valve Location β operation degree

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Thomas Messner, Federal Republic of Germany 75179 Pforzheim, Allinger Strasse 115 (72) Inventor Detlef Fuchs, Federal Republic of Germany 71640 Ludwigsburg, Schottenberger Wek 12

Claims (11)

[Claims] 1. A method of controlling a vehicle drive unit in which a driving variable of a driving unit or a vehicle is limited to a maximum allowable value, in which a stepwise change in an output provided by the driving unit limits a driving variable to a maximum allowable value. And the stepwise change being a function of the slope of the driving variable to be limited. 2. The method according to claim 1, wherein the output of the drive unit is controlled as a function of the set value via a setting element that influences the output. 3. The method of claim 2, wherein the setpoint value is a measure for engine load, engine torque, engine output, throttle valve position, air amount, and the like. 4. The method according to claim 1, wherein at the start of the limit, the set value is reduced stepwise so as not to exceed the maximum permissible value of the operating variable. 5. The method as claimed in claim 1, wherein a pulsed change occurs when the operating variable to be limited exceeds an engagement value. 6. The method of claim 5, wherein the engagement value is a function of the slope of the operating variable to be limited. 7. At least one controller for said limit
7. A method as claimed in any one of the preceding claims, characterized in that three integrating parts are provided and the value of the controller is set to a predetermined initial value at the beginning of the limit. 8. The method according to claim 6, wherein the initial value is a function of the slope of the operating variable to be limited and the set value provided by the driver via the operating element. 9. The method according to claim 1, wherein the stepwise change is performed not in one stage but in a plurality of stages with a time spread. 10. The operating variable is an engine speed,
10. The method according to claim 1, wherein the driving speed, the engine torque, the engine output, the engine load, the supply air amount, etc. are used. 11. A control device for a vehicle drive unit, comprising a limiter for limiting an operating variable of a drive unit or a vehicle to a maximum allowable value, wherein when the operating variable reaches the maximum allowable value or limiting the operating variable. When the engagement value for is reached, the limiter stepwise changes the output provided by the drive unit in a direction to limit the operating variable to the maximum allowable value, where the step change value is limited. Control device for a vehicle drive unit, characterized in that it is a function of the gradient of said driving variable to be performed.