System for the electronic open-loop and/or closed-loop control of the power of an internal combustion engine of a motor vehicle

A system is suggested for the electronic open-loop control and/or closed-loop control of the power of an internal combustion engine of a motor vehicle in which the open-loop control or closed-loop control of the power is dependent on a parameter which represents the driver's wish, the open-loop control or closed-loop control being carried out in pregiven operating conditions independently of this parameter and occurring in these operating conditions, which are characterized by a reduction or an increase of the fuel supply due to an active drive slip control or engine drag torque control. For a faster response of the control system, the preset values which support the reduction or increase requirement, are dynamically amplified in their effect.

FIELD OF THE INVENTION 
The invention relates to a system for the electronic open-loop and/or 
closed-loop control of the power of an internal combustion engine. 
BACKGROUND OF THE INVENTION 
Such a system is known from DE-OS 37 43 471. There, a system is suggested 
for the open-loop and/or closed-loop control of the power of the internal 
combustion engine, which reduces the power of the engine in certain 
operating conditions, characterized essentially by slip occurring on one 
of the driving wheels. In this system, the throttle flap, which is 
controlled outside the described operating condition and dependent on the 
driver's wish, is triggered independently of the driver to effect a 
reduction of power, that is, the throttle flap is turned back toward its 
closed position by a specified angle and is subsequently moved in steps, 
up to the point of the slip threshold of the driving wheels, to effect a 
power increase. 
In U.S. Pat. No. 3,802,528, a system for influencing the engine torque is 
suggested, in which in the event of wheel slip during overrun operation, 
the fuel supply to the engine is increased in order to reduce the engine 
braking torque (engine drag torque control MSR). If control is via a 
throttle flap, this means that the throttle flap is opened. In overrun 
operation, this leads in principle to a reduction of the power of the 
internal combustion engine. 
In the following, the discussion therefore will be only of a power 
reduction. In the case of ASR (automatic slip control), this leads to a 
reduction of the fuel supply (throttle flap is moved toward its closed 
position); in the case of MSR, it leads to an increase of fuel supply 
(throttle flap is opened). 
When such systems are operated in conjunction with an electronic engine 
power control, disadvantages in the reaction speed of the closed-loop 
control system of the electronic engine power control will occur. 
The invention is therefore based on the task of improving the reaction 
speed of an electronic open-loop and/or closed-loop control of the power 
of an internal combustion engine. This task is solved by an additional 
amplification of the values, in their effect, which represent the power 
reduction requirement. 
EP-A 104 539 describes an arrangement for the reduction of the braking 
torque of internal combustion engines in overrun operation. Here, the fuel 
supply is increased in the overrun operation for a reduction of the 
braking torque of the engine, that is, the position of the throttle flap 
is changed to effect an increase in the air supply. 
SUMMARY OF THE INVENTION 
The procedure according to the invention has the advantage that, in the 
interplay of an electronic engine power control (EMS) with a drive slip or 
engine drag torque control (ASR or MSR), the reaction capability of the 
system to a requirement for power reduction is improved, without an 
intervention in the structure of the control system of the electronic 
engine power control being required. The structure of the circuit which 
controls the power of the engine can thus remain in the form in which it 
was selected with respect to the power control, idling control or 
after-running control, but the reaction time of the power change to a 
requirement for power reduction occurs with the dynamics necessary for a 
drive slip control or engine drag torque control. 17 description

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
FIG. 1 shows an internal combustion engine 10 with a throttle flap 14, 
arranged in the intake system 12 of the internal combustion engine 10, for 
the control of the air supply to the engine or of the power of the engine. 
The throttle flap 14 is connected to an electrically actuated positioning 
motor 18 via a rigid connection 16. The throttle flap 14, the rigid 
connection 16 and the positioning motor 18 form together with a position 
transducer 20 the power actuator 22 of the engine. The position transducer 
20, which for example is arranged in the embodiment shown in FIG. 1 on the 
rigid connection 16, sends a signal corresponding to the position of the 
power actuator 22 via its output line 24 to an engine control system 26. 
The engine control system 26, which comprises the electronic engine power 
control 27 (shown in dashed lines) and an ASR and/or MSR unit 28 shown in 
dot-dash outline is connected to the power actuator 22 via a trigger line 
30 which is connected to the positioning motor 18. The part of the engine 
control system 26 outlined in dash line comprises a unit 32 for the 
forming of a preset value for the actuator position, which is connected 
via a connection line 34 to a unit 36 for the processing of the ASR/MSR 
signal. With a second connection line 38, the unit 36 is further connected 
to the ASR/MSR unit 28. Output line 40 of unit 36 is connected to a first 
input of the positioning control 42, the second input of which has the 
connection line 24 applied to it. The output 44 of the positioning control 
connects the control to a drive stage 46, the output of which represents 
the connection line 30. 
The unit 32 for the forming of the preset value is connected to further 
arrangements of the engine and/or the vehicle via its input lines 48, 50 
and 52. The input line 48, for example, connects the unit 32 to a 
road-speed control 54, the input line 50 connects the unit 32 to an 
accelerator pedal 56 operated by the driver. Finally, the input line 52, 
symbolically shown as a single line, links the unit 32 to engine control 
functions 58, which have an influence on the power actuator position. 
Here, it is especially thought of a knock control, speed and/or revolution 
limitation or a catalyzer protection function. 
In addition to the shown throttle flap control functions, the system 
described in FIG. 1 can be applied to a power actuator which controls the 
fuel supply to a Diesel engine. 
In dependence upon its input signals, the unit 32 for forming the preset 
values generates a value for the position of the actuator, the value being 
the so-called throttle flap preset value (DKV) and corresponding to the 
input variables. The input values include a position signal indicative of 
the position of the accelerator pedal or a signal value representing the 
further engine control functions shown summarized in block 58. The forming 
of the preset value is calculated, for example, from a pregiven 
characteristic field. The DKV thus formed is sent to the unit 36 via the 
line 34. 
By means of the unit 36, he determined DKV is combined with a value 
supplied via line 38 from the ASR and/or MSR unit 28 for reducing the 
engine power in accordance with the method shown further below. The 
generation of the preset value for the reduction (DKR) and increase (DKE) 
of the fuel supply, which takes place in the unit 28, is known, for 
example, from the initially mentioned state of technology, DE-OS 37 43 471 
(ASR) and the U.S. Pat. No. 3,802,528 (MSR) and is therefore not further 
described. 
The set value (DKS) formed from DKV and DKE/R for the position of the 
actuator is transmitted to the position controller 42 via the line 40 from 
the unit 36. The position controller 42 compares the calculated set-point 
value to the actual value (DKI) of the actuator position supplied via the 
line 24, and via the line 44 and the drive stage 46, the position 
controller 42 supplies a drive signal, which shows the difference between 
set-point value and actual value, to the actuator 22. The drive signal is 
transmitted via line 30 to the positioning motor 18, which, in accordance 
with the drive signal, changes the position of the actuator 22 so that the 
difference between desired value and actual value is reduced. 
FIG. 2 shows, by means of a flowchart, the general run of the logic 
operation taking place within the unit 36 between position preset value 
(DKV) and ASR-preset value or MSR-preset value (DKR/E). At the start of 
the illustrated program part of the engine control system at the beginning 
of an operating cycle of the motor vehicle, a decision as to the execution 
of the ASR or MSR function is made in step 100. This requires at least the 
inquiry whether or not a preset value (DKE, DKR) from the ASR or MSR unit 
is available which lies within a pregiven value range, and, in the case of 
the ASR, whether the preset value is less than the DKV value of the unit 
32, and in the case of the MSR, whether the overrun operation has been 
detected. If this is not the case, then in accordance with block 102, the 
preset value calculated by the unit 32 for the actuator position is 
supplied to the position controller 42 as the desired value (DKS), for 
setting the appropriate actuator position. 
If in the inquiry block 100, the decision is made for the execution of the 
ASR or MSR function, then a determination is made in accordance with block 
104 as to whether an ASR intervention is present and this is executed in 
accordance with block 106 by the process shown in FIG. 3. A corresponding 
procedure is represented by block 108 which is activated with an MSR 
intervention. To conclude the program part, a stored preset value DKR/EALT 
is overwritten in block 110 with the preset value DKR/E present in this 
program run, and the program run is ended. 
The flowchart of FIG. 2 is based on a combined ASR/MSR system. The 
procedure in accordance with the invention, however, is not restricted to 
such a system, but can also be applied to systems which have only ASR or 
MSR functions. In such cases, the blocks 104 and 108 or 106 are dispensed 
with. 
FIG. 3 shows, with reference to a flowchart, an embodiment of the procedure 
in accordance with the invention for the example of the ASR function. The 
implementation of an MSR function occurs in a corresponding manner with 
the requirement for a reduction being replaced by a requirement for an 
increase in the fuel supply. 
The program part shown in FIG. 3 is started after the decision has been 
made for the implementation of the reduction or increase. The difference 
formed from the currently existing preset value (DKR) and the preset value 
(DKRALT) stored from the previous program run is then checked in block 200 
for a pregiven preset value range. If this difference is other than 0, 
then at least two time functions which describe predetermined time 
intervals, are reset in block 202. Through this check for "other than 0", 
both a reduction and an increase of the requirement for power reduction 
will lead to the dynamic preset amplification described further below. 
Accordingly, the so-called dynamic preset amplification value DKRDYN is 
calculated in block 204 as a function of the following: the time interval, 
the preset value (DKRALT) stored from the previous program run, and the 
instantaneous value (DKR). The particular time interval is taken into 
consideration by a factor. Through DKRDYN, the preset values supplied by 
the ASR/MSR unit will be amplified in their effect. The factor which is 
allocated to the first time interval T.sub.d1 which occurs earlier, is 
applied in block 204 at the start of the ASR intervention. This dynamic 
preset amplification value is hereafter, as required, limited in block 206 
and the desired value, which is supplied to the position controller for 
the actuator position, is reduced to the instantaneous preset value DKR, 
reduced by the dynamic preset amplification value. By executing the 
control, the position of the actuator is adjusted to the desired position 
calculated in block 208. 
If it is determined in inquiry step 200 that the difference from the stored 
and the instantaneous preset value equals zero, then the second time 
interval T.sub.d2 which occurs later, is checked in step 212 to ascertain 
whether this has already elapsed. If this is so, then the instantaneous 
prevailing preset value DKR is read in (step 214) and limited (216) as 
required. The desired position of the actuator is formed in step 218 by 
the instantaneously prevailing preset value DKR. 
If on the contrary the time interval T.sub.d2 has not elapsed, then the 
earlier occurring first time interval T.sub.d1 is interrogated in step 220 
as to its time sequence. If it has elapsed, that is, if the current time 
point lies in the specified time interval T.sub.d2, then the preset 
amplification value is calculated from the factor ascertained in block 204 
as a function of the instantaneous preset value, of the stored preset 
value DKRALT, and of the factor (222) assigned to the time interval 
T.sub.d2, and the present amplificator value is limited, as required, in 
step 224. In step 226, the desired value representing the desired position 
of the actuator is determined as the difference between the instantaneous 
preset value and the dynamic preset amplification value. The control then 
leads the position of the actuator to the desired value determined in step 
226. 
If the current time point is at the beginning or lies in the predetermined 
interval T.sub.d1 (block 220), then the dynamic preset amplification value 
is ascertained in block 228 in accordance with block 204. Following the 
limitation, which may have been applied in appropriate circumstances, of 
the preset amplification value (230), the desired position of the actuator 
is determined in block 232 as the difference between the instantaneous 
preset value DKR and the dynamic preset amplification value determined in 
block 228. After blocks 208/218/226/232, the program part is ended and 
carried out in accordance with FIG. 2. 
The determination of the dynamic preset amplification value as a function 
of the instantaneous (DKR) and the stored preset value DKRALT as preset 
prior to an occurring difference between DKRALT and DKR (200), and of the 
time (T.sub.d1,2), can be determined in accordance with a pregiven formula 
or by reading from a table. The dynamic preset amplification value will 
depend preferably on the difference between DKRALT and the instantaneous 
preset value DKR, which is supplied by the ASR/MSR unit during the 
specific operating condition. This difference is weighted with a 
predetermined factor which takes the different time intervals into 
account. The factor is preferably selected so that it assumes a high value 
during the interval T.sub.d1 which occurs earlier in time, and assumes a 
lower value during the interval T.sub.d2 which occurs later in time. This 
produces a stepwise progression of the desired value which determines the 
desired position of the actuator. The two time intervals T.sub.d1 and 
T.sub.d2 are then a pregiven multiple of the program run time. The 
inventive concept is by no means limited to only two time intervals and it 
is certainly possible for several of these time intervals to be provided 
which will lead to a multi-step progression. 
FIG. 4 illustrates the process according to the invention and its effects 
on the position of the actuator with respect to the time progression of 
the occurring signals as a function of time, and therewith on the engine 
output in the example of an ASR intervention. Analogous relationships are 
obtained for the MSR case, in which the dynamic preset value is added to 
the preset value of the MSR unit (DKE). The signal progression shown as a 
broken line in FIG. 4 signifies the preset value (DKV), which is 
determined in dependence upon the accelerator pedal, for the position of 
the actuator. The solid signal line represents the instant position of the 
actuator (DKI), while the dot-dash line represents the signal progression 
of the preset value (DKR) which reduces the engine output, this signal 
being emitted by the ASR unit. The dotted progression corresponds to the 
progression of the preset value reducing the power with the preset value 
being determined on the basis of the method of the invention while taking 
into account the dynamic preset amplification value (DKRDYN). The 
horizontal axis represents a time axis while the vertical axis indicates a 
parameter which represents the values addressed. 
In a time range below the time TO, FIG. 4 shows an acceleration operation 
which is characterized by the continuous increase of the preset value 
(DKV) and therefore by the instantaneous position of the actuator. Since 
in the ASR case, the driving wheels show no spinning tendency at this 
instant, the preset value produced by the ASR unit is fixed to a static 
level DKRALT. At the instant TO, a spinning tendency of the driving wheels 
is established. In accordance with the function of the ASR unit, a preset 
value which reduces the engine power is established and passed to the 
engine power control. This function is shown in FIG. 4 by the jump-like 
progression of the dot-dash line at the instant TO. The preset value which 
represents the accelerator pedal position, for example, is continued 
unchanged. The dot-dash progression of the preset value given by the ASR 
unit is brought to its value, which it had assumed prior to the instant 
TO, in accordance with the state of technology to DE-OS 37 43 471 stated 
in the opening paragraph. The method in accordance with the invention is 
now shown in that at the instant TO, a dynamic preset amplification 
occurs, which is formed in accordance with the calculation rule explained 
by means of FIG. 3. The dynamic preset amplification then increases the 
effect of the preset value supplied by the ASR unit for the reduction of 
the actuator position or the engine power. According to the method of the 
invention, as shown by FIG. 3, the preset value corrected by the dynamic 
preset amplification is increased at specified intervals (for example, at 
instants T1 and T2), which represent the time elapsed since the occurrence 
of the slip tendency, by a specified value, from the instantaneous value 
and the preset value prior to instant TO, and a time factor, until the 
value specified by the ASR unit is reached. The progression of time, the 
desired value representing the desired position of the actuator, is shown 
by the dashed line, at the instant TO by the dot-dash line and the dotted 
line, between the instants TO and T2 by the dotted line, after the instant 
T2 by the dot-dash line. 
The progression of the actual position of the actuator is described with 
reference to the solid line. The response time to a request for reduction 
(in the MSR case to a request for an increase) of the fuel supply is then 
considerably improved. 
To summarize, it may be noted that the described procedure acts as a fast 
acting precontrol for the actuator position, with the values corresponding 
to the additional amplification of the precontrol values.