JPH08232705A - Method and equimpment for controlling internal combustion engine of car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a traveling comfortability by a simplified adaptation to an internal combustion engine at the time of a transition from an operation state by reducing or increasing a torque due to the internal combustion engine according to a designated time function at the time of a beginning or finishing of an over-running state. SOLUTION: A torque generated by an internal combustion engine is adjusted to an application value by controlling at least one operation parameter of the internal combustion engine. The torque generated by the internal combustion engine is reduced or increased according to a designated time function at the time of beginning or ending of an over-running state. Namely, a bonding torque target value Mkupext is fed to a control unit 10 through a communication system 32. A control of an engine torque at the time of transition from an over-running state and to the over-running state separated to a torque target value specification 100-138 and a calculation 140-144 of a control parameter based on the torque target value determined. Thereby, an adaptation of the transition is simplified and a comfortability in these operation stages is improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to a method and apparatus for controlling an internal combustion engine of a vehicle.

[0002]

2. Description of the Prior Art It is known to stop the supply of fuel when controlling an internal combustion engine during an overrun condition when the engine is driven by a vehicle. At the transition to this so-called overrun stop, or at the transition from this state of fuel supply stop to the normal running mode, the ignition angle of the internal combustion engine is changed in order to improve comfort. Such a control is known, for example, from DE 27 37 886 C2 (US Pat. No. 4,257,363). In this, at the start of the overrun condition, the ignition timing is adjusted in the direction of the delay according to a preselectable function, and the fuel supply is stopped after the ignition timing control has ended. Furthermore, at the end of the overrun condition or when the fuel supply is restarted,
Ignition time is changed from delay to advance. As a result, shocks resulting from stopping or resuming fuel supply are to be avoided. The ignition angle has a non-linear effect on the combustion torque generated by the internal combustion engine or the engine torque output thereby,
Moreover, since it is strongly dependent on the characteristics of the respective internal combustion engine, the known ignition angle control must be newly adapted to each internal combustion engine type in order to achieve the optimum reduction of the impact.

Based on an engine torque setpoint value or a combustion torque setpoint value to be output by the internal combustion engine, a few cylinders to be stopped, an ignition angle correction to be implemented and / or
Alternatively, it is known from DE 42 39 711 A1 to determine a setpoint value for adjusting the air supply to the internal combustion engine. Furthermore, it is known to calculate the actual value of the combustion torque or the engine torque output by the internal combustion engine on the basis of the load of the internal combustion engine and its rotational speed, as well as the corrected ignition angle and the number of stop cylinders.

[0004]

Therefore, during the transition from this operating state to the operating state of fuel shut-off and / or at the restart of the fuel supply, a simplified adaptation to various internal combustion engines is therefore made possible. It is an object of the invention to disclose means for improving the driving comfort.

[0005]

A control means is provided for reducing or increasing the torque produced by an internal combustion engine at the beginning or end of an overrun condition in accordance with a designated time function.

[0006]

The invention will now be described in more detail with reference to the embodiments shown in the drawings.

FIG. 1 shows a control unit 10 with at least one microcomputer 11 for controlling an internal combustion engine (not shown). The control unit 10 supplies the fuel to the cylinders of the internal combustion engine via the output line 12, the ignition angle via the output line 16, and in a preferred embodiment via the output line 20 to the internal combustion engine. Actuator 2 for controlling the intake flow rate
Control 2 The actuator 22 is preferably here an electrically actuable main throttle valve, which is regulated during normal operation as a function of the driver's demands. In another advantageous embodiment, the actuator may be for regulating the idling air or a supplementary throttle valve mounted in series with the (mechanically operable) main throttle valve. The operating variables of the internal combustion engine and / or the vehicle, which are detected by the corresponding measuring devices 28 to 30, are supplied to the control unit 10 via lines 24 to 26. The control unit 10 for controlling the internal combustion engine is provided with a further control unit 34, preferably AB via a communication system, for example a CAN bus system.
It is connected to the S / TCS controller and / or the transmission control unit.

The torque target value to be output by the internal combustion engine is transmitted from the control unit (s) 34 to the control unit 10 via the communication system 32. For example, the output torque target value at the transmission output can also be changed by the control unit for an automatic transmission to the ABS / T
An output torque setpoint in case of excessive slip tendency on at least one drive wheel is calculated and transmitted by the CS control unit. Furthermore, in a preferred embodiment, the setpoint value may be set by the driver via the degree of actuation of the control element. As is known from the state of the art mentioned at the outset, the control unit 10 uses this torque setpoint as a function of operating variables, for example engine speed, engine temperature, load conditions, possibly supplied via lines 24-26. And the like, to the correction of the ignition angle determined as a function of engine speed and load (eg air flow rate), to the number of injections to be suppressed in the individual cylinders and / or
Alternatively, it is converted to the position of the actuator 22 to be adjusted. In the preferred embodiment, the amount of fuel to be injected is then determined for each individual cylinder as a function of engine speed and load (eg air flow rate).

If the air supply to the internal combustion engine is regulated by the driver via a mechanical connection via the accelerator pedal, the engine torque regulated by the driver is dependent on the engine load (air flow rate, throttle valve position) and Calculated from engine speed.

Shown in FIG. 2 is a control unit 10.
FIG. 3 is a detailed block diagram showing the transition from the operating state to the operating state accompanied by the fuel stoppage in the overrun state and from the operating state when the fuel supply is restarted. The coupling torque target value Mk is transmitted to the control unit 10 via the communication system 32.
upext is supplied. Coupling torque target value Mkupe
xt is led to the logical connection point 100, where the loss torque Mverl is added. As a result, an externally specified combustion torque setpoint value Mipex is obtained, which is led from the logic connection point 100 via the line 102 to the minimum value evaluation stage 104. The loss torque Mverl here represents the losses that occur in the internal combustion engine and the torque requirements of the secondary assembly, for example the air conditioning unit. The loss torque is determined based on the engine speed, the engine temperature, and the load condition using a predetermined characteristic diagram.
The torque setpoint, which is guided by the line 102 to the minimum evaluation stage 104, is in this case determined by a function such as a traction control system, an engine drag torque control system, a transmission control system or by the driver.
According to the known prior art, this torque setpoint is converted into suppression of the injection process, ignition angle correction and / or adjustment of the air supply. If an intervention in the air supply of the above-mentioned functions is prepared, the combustion torque Mipfu made available by adjusting the air supply is calculated, as is known from the prior art mentioned at the beginning. If no intervention is provided in the air supply or no intervention is performed, this value corresponds to the torque value specified by the driver by operating the throttle valve.

The torque value Mipfu is supplied to the counting means 106 via the line 33. This counting means also has a line 10
8 through the characteristic means 110 from the actual combustion torque Mipi
st is supplied. The output of the counting unit 106 represents the profile of the combustion torque target value Mipwe when the fuel supply is restarted, and passes through the line 112, the switching unit 114, and the line 116 to the minimum value evaluation (selection) stage 104. Supplied. The illustrated position of the switching means 114 corresponds in this case to the position outside the overrun condition. Switching means 1
14 operates via line 120 as a function of overrun condition detection block 118. At least a line 112 for supplying a signal LL representing the released accelerator pedal and a line 124 for supplying a measure Nmot of the engine speed are connected to the overrun state detection block 118. In addition, the overrun condition detection block 118 activates the counting means 106 via line 126 and the further counting means 130 via line 128. This further counting means 130 is supplied via line 132 with a measure for the actual combustion torque Mipist and via line 134 with a value for the minimum torque Mipug, which in the preferred embodiment is zero. is there. The minimum torque Mipug is now read from the memory element 126 and the actual combustion torque is based on the characteristic means 110 as known from the engine speed and engine load, and possibly also the corrected ignition angle and the suppressed cylinder. Calculated based on the number (indicated by the dashed line). The output of the counting means 130 is the combustion torque target value profile Mip at the transition to the fuel stop.
represents sa. This value is line 136, switching means 114.
And the line 116 to the minimum selection stage 104.
In this minimum value selection stage 104, the supplied variable M
The minimum torque value in the absolute terms of ipext and Mipwe or Mipsa is formed as the combustion torque target value Mipsoll for intervention in injection and ignition. This target value is calculated via line 138 in the calculation unit 140.
Be led to. The calculation unit 140 converts the combustion torque target value into an ignition angle correction value and / or into the number of cylinders to be suppressed in a manner known from the prior art. In the process, the combustion torque setpoint is compared with the actual value estimated by the model, and in the case of a relatively small combustion torque setpoint, cylinder suppression and / or ignition angle intervention is calculated. The corresponding result is output via lines 142 and 144. The effects of fuel metering and ignition angle adjustment are outlined by correction blocks 146 and 148 and output lines 12 and 16.

For reasons of clarity, the regulation of the air supply is omitted in the illustration according to FIG. It is obtained by applying the procedure disclosed in the prior art.

The basic idea of the invention illustrated in FIG. 2 is that the control of the engine torque during transitions to and from the overrun state is controlled by the torque target value specification (100).
To 138) and calculation of the control variable according to the determined torque target value (140 to 144).

During the transition to the overrun state, the torque specification value Mipsa is calculated by the counting means 1 according to a designated time function.
The instant actual combustion torque Mipist is reduced by 30 to a predetermined lower limit value Mipug. When the lower limit value is reached, the combustion torque setpoint value Mipsoll resulting from the minimum selection stage is so small that all cylinders and thus all fuel supplies are stopped. Upon restarting, the torque value is increased according to the torque specification value Mipwe from the instantaneous actual torque value Mipist as a starting value to the torque value Mipfu essentially specified by the driver by the counting means 106 according to a specified time function. It
When the torque specification value Mipwe reaches the limit value Mipfu, the torque increase for restarting is terminated.

In the preferred embodiment, suppression of individual cylinders can be prohibited while torque is being increased or decreased. In this case, only ignition angle adjustment for rapid torque intervention is allowed.

The time functions specified in the counting means 106 and 130 can be implemented in various ways.
For example, the counting means can be realized as first-order, second-order or higher-order delay elements. In one embodiment, it has been found suitable to achieve a stepped profile. The time constant or rate of change is in this case freely selected and can be adapted according to the comfort requirements.
However, when the impact changes the sign of the torque output by the internal combustion engine during the transition to and from the overrun state with fuel stop,
That is, it is most likely to occur when the internal combustion engine changes from a driven state to a driven state and vice versa.
Therefore, it is advantageous to separate the torque specification into two regions. In the first region, when the torque target value to be adjusted is between 0 and the absolute value of the loss torque (negative output torque, overrun state), it is preferable to select a large time constant or a small change rate. It is advantageous. In the second region, when the torque target value to be adjusted is larger than the loss torque, that is, the output torque is positive,
It has proven advantageous to choose a small time constant or a large rate of change. The engine torque can therefore meet the driver's demands quickly and without impact and can be reduced to the lower limit. According to another procedure, it is advantageous to slow down the change of the torque specification when the actual combustion torque Mipist is in the region of the absolute loss torque Mverl.

The present invention is preferably implemented within the scope of a computer program. This is explained by way of example with reference to the flow charts shown in FIGS.

After the program portion shown in FIG. 3 is started at a predetermined time point, a signal LL indicating the engine speed Nmot and the idling position of the accelerator pedal is read in a first step (step 200). Next question step 20
2, the accelerator pedal is released and the engine speed N
mot is the designated restart speed Nwe, for example, 1000 rpm
, Is checked to see if it is above. If this is the case, the marker Schu is followed according to step 204.
If b is set to the value 1 and is negative then this marker has the value 0
(Step 206). After this, this program part is terminated.

The marker Schub here indicates the presence of an overrun condition (value 1) and therefore the switching means 114.
Is represented. This is used to control the torque specification. If the value of the marker Schub changes from 0 to 1, i.e. if the internal combustion engine enters the overrun state, the program part according to FIG. 4 is started.

In a first step 201, the specified lower limit value Mipug and the calculated actual combustion torque Mipi
st is read. In addition, the start value Mip of the torque specification
sa (O) is set to the value of the actual combustion torque. In the next step 202, the current torque specification value Mipsa (K)
Is calculated from the difference Δ between the specification value Mipsa (K−1) determined in the preceding programming process and the specified value. Then, in a query step 204, the current value Mips
It is checked whether a (K) is below the lower limit value Mipug. If this is affirmative, the engine torque reduction is ended and all cylinders are stopped (no injection), so this program part is ended. If the lower limit value has not yet been reached, the program part is repeated from step 202.

In the preferred embodiment shown in phantom in FIG. 4, various rates of reduction are also specified as a function of torque specification. For this purpose, in a query step 206 it is checked whether the current specification value Mipsa (K) lies between the value 0 and the value of the absolute loss torque Mverl. If this is the case, the value Δ1 is specified in step 208, and if not, the value Δ2 for reduction is specified according to step 202 (step 21).
0). The values Δ1 and Δ2 are selected in this case so that the rate of change with negative output torque in the region defined in step 206 is small. In this way, possible torque impacts in the event of a fuel outage are effectively prevented.

The corresponding procedure for restarting the fuel supply after the end of the overrun condition is shown in FIG.
The engine torque is increased when the overrun condition marker changes from the value 1 to the value 0. To this end, step 22
At 0, the starting value Mipw of the torque specification for restarting
e (O) is set to the read value of the actual combustion torque Mipist. Then, according to step 222, the torque specification is increased, thus allowing a shock-free restart. The current torque specification value Mipwe (K) is likewise determined by adding the value Δ to the value Mipwe (K-1) determined in the preceding programming process. Then step 22
In step 4, the torque value Mipfu is read, and in the next interrogation step 226 it is checked whether the torque specification value determined in step 222 is essentially above the driver specified value Mipfu. If this is affirmative, the program part is terminated, and if not, a further increase in the torque specification is made as a result of the iteration from step 222 of the program part.

Again, various rates of change are provided in one embodiment. For this purpose, in the program part indicated by the dashed line, it is checked in a query step 228 whether the specification value Mipwe (K) lies between the value 0 and the value of the loss torque Mverl. If this is the case, then according to step 230 the value Δ1 is used to increase the torque in step 222, and outside this range the value Δ2 is used according to step 232. Again, the value Δ1 is smaller than the value Δ2 in absolute terms, so that a low rate of change of torque is generated in the region with negative output torque.

The specification values determined by this method are converted into cylinder suppression, ignition angle correction and the air flow rate to be supplied according to FIG. For this purpose, according to step 250 of the program part shown in FIG.
we, Mipsa and Mipex are read, and in step 252 the combustion torque target value Mipsoll
Is set to the minimum of these values in absolute terms. Subsequently, in step 254, the number X of cylinders to be suppressed, the correction amount ZW for the ignition angle, and possibly the correction value αsoll for the adjustment of the air supply are determined at least based on the combustion torque target value and the actual combustion torque. It After this, this program part is terminated.

FIG. 7 presents the mode of operation of the invention in a time diagram. Here, FIG. 7a shows the profile of the overrun state marker, FIG. 7b shows the profile of the combustion torque target value Mipsoll, FIG. 7c shows the profile of the torque Mkup output by the internal combustion engine, and FIG. 7d shows the profile of the cylinder to be suppressed. A profile for a time of several X is shown.

It is assumed that the overrun condition occurs at time T0. Overrun status marker is value 0 to value 1
Changes to Therefore, in order to cut off the fuel supply, time T
Starting from 0, the torque specification target value is reduced to a value of 0. This takes place essentially according to FIG. 7b at two rates of change, one change in the rate of change occurring when the torque output by the internal combustion engine changes its sign.
This is illustrated by FIG. 7c, which shows the change in torque output corresponding to the specified torque. At time T2, it is assumed that the combustion torque target value is 0 and the output torque is negative, that is, the internal combustion engine is being driven by the vehicle. Correspondingly, FIG. 7d
At t0, the number of cylinders to be suppressed increases incrementally with a decreasing rate of change,
At 2, all cylinders are suppressed, ie the fuel supply is cut off. It is assumed that at time T1 the overrun condition is terminated and the overrun condition marker changes to the value 0 again. This means that the combustion torque setpoint is increased according to FIG. 7b, starting from time T1. Again, two rates of change are selected in a manner similar to reduction. At time point T3, it is assumed that the combustion torque target value specified by the driver is achieved. Time point T1
A corresponding increase in torque starting from 0 can also be seen in the case of actual torque according to FIG. 7c. In the preferred embodiment, this torque increase is achieved by restarting the fuel supply to the specified number of cylinders according to FIG. 7d. At time T3, all cylinders are refueled.

The rate of change during the reduction and the increase can be differently specified depending on the requirements of the vehicle and the requirements of the internal combustion engine.

In addition, the adjustment of the ignition angle is shown in broken lines in FIG. 7d. Between T0 and T2, the ignition angle is reduced according to the torque specification (lead to lag), between T1 and T3 is increased (lag to lead), and T
Between 2 and T1 all cylinders are suppressed. This illustration applies only if cylinder suppression is not performed except between T2 and T1. In the case of cylinder suppression, the ignition angle is possibly varied such that the torque profile is continuous, ie the torque increment caused by ignition suppression is compensated as a result of the ignition angle adjustment.

Instead of the specification value for the combustion torque, in another embodiment a specification value for another torque produced by the internal combustion engine, for example the output torque, is determined and the procedure according to the invention is correspondingly implemented. It

[0030]

The procedure according to the invention simplifies the adaptation of the transition to an operating state with a fuel outage or from this operating state to a normal running mode under resumption of fuel supply. In particular, the costs associated with adapting various types of internal combustion engines are considerably reduced.

The procedure according to the invention leads to an improvement in comfort during these operating phases. At the same time, shocks during transitions are avoided as much as possible.

[Brief description of drawings]

FIG. 1 is a schematic block circuit diagram of a control device for an internal combustion engine.

FIG. 2 is a detailed block circuit diagram of the control unit of the present invention.

FIG. 3 is a flowchart showing a procedure according to the present invention.

FIG. 4 is a flow chart showing a procedure according to the present invention.

FIG. 5 is a flowchart showing a procedure according to the present invention.

FIG. 6 is a flowchart showing a procedure according to the present invention.

FIG. 7 is a time chart of the essential variables of an internal combustion engine showing the effect of the present invention.

[Explanation of symbols]

10: control unit, 28 to 30: measuring device, 3
2: communication system, 34: further control unit, 104: minimum value evaluation (selection) stage, 106, 130: counting device, 11
0: characteristic means (characteristic diagram), 126: storage element, 118:
Overrun state detection block, 140: calculation unit,
146, 148: correction block.

Claims (10)

[Claims] 1. A fuel supply is cut off during an overrun condition and fuel is reinjected at the end of the overrun condition.
A method for controlling an internal combustion engine of a vehicle, wherein the torque generated by the internal combustion engine is adjusted to a specified value by control of at least one operating variable of the internal combustion engine, said specified value and thus generated by the internal combustion engine A method for controlling an internal combustion engine of a vehicle, wherein torque is reduced or increased at the beginning of an overrun condition or at the end of an overrun condition according to at least one specified time function. 2. The method according to claim 1, wherein the torque is increased or decreased by correction of the ignition angle, suppression of individual injections and / or adjustment of the air supply to the internal combustion engine. the method of. 3. The torque to be output by the internal combustion engine, at the beginning of the overrun condition, starts at a starting value representing the torque currently generated by the internal combustion engine and extends at least to a specified lower limit value, preferably 0. Method according to claim 1 or 2, wherein the method is reduced according to a time function. 4. At the end of the overrun condition, the torque generated by the internal combustion engine starts from a starting value representing the torque generated at the end of the overrun condition, to at least one value specified by the driver. Method according to any one of claims 1 to 3, wherein the method is increased according to a specified time function. 5. The method according to claim 1, wherein the determination of the specification value for the torque, in particular its increase or decrease, is separate from the calculation of the control variable for at least one operating variable. the method of. 6. The method according to claim 1, wherein the torque output by the internal combustion engine to the drive train is increased or decreased slowly in the region of sign change. 7. A large change rate of the torque is designated in a region having a positive sign of the torque output to the drive train by the internal combustion engine, and a small change rate is designated in a region having a negative torque. Claims 1 to 6
The method described in any one of. 8. The determined specification value is converted into a number of cylinders to be suppressed, an ignition angle correction value, and / or a change amount of air supply, independently of a driver's request. A method according to any one of claims 1 to 7. 9. After completion of the reduction or increase of the torque,
9. The method according to claim 1, wherein the fuel supply is cut off or restarted. 10. An internal combustion engine of a vehicle, comprising a control unit for detecting an overrun condition of the internal combustion engine, interrupting the fuel supply to the internal combustion engine during the overrun condition, and restarting the fuel supply at the end of the overrun condition. A device for controlling a control unit, wherein the control unit influences the torque generated by the internal combustion engine by controlling at least one operating variable of the internal combustion engine according to a specification value for the torque, which is determined thereby. For controlling an internal combustion engine of a vehicle, the specification value being adapted to be reduced or increased according to at least one time function at the beginning or the end of an overrun condition. Equipment.