JP4165664B2 - Method and apparatus for controlling an internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for controlling an internal combustion engine that is configured such that a target torque is set and a torque output by the internal combustion engine is adjusted corresponding to the target torque.
[0002]
[Prior art]
A method and device of this kind are known from German publication DE 42 39 711 A1, in which the engine torque to be output by the internal combustion engine, in particular the engine torque present on the output side of the engine or on the input side of the transmission, is known. Defined as target value. By determining the internal loss and the additional load torque requirements in the internal combustion engine, the target combustion torque is determined by adjusting the intake flow rate, correcting the set ignition angle, and / or Alternatively, it can be made available by shutting off the fuel supply to a predetermined number of cylinders. No means are described for emergency operation in the event of a malfunction of the final control element for adjusting the intake air flow or the final control element for adjusting the idling air flow in the idling state of the internal combustion engine.
[0003]
The German publication DE 42 14 179 C1 discloses an emergency action in the event of a malfunction of the final control element with respect to the intake flow rate. In the event that the function of the final control element is adversely affected, the output of the internal combustion engine can be determined exclusively by intervention in the composition of the mixture and / or by intervention in the ignition and / or the fuel to at least one cylinder. Set to a value corresponding to the current load specification by controlled interruption of the supply. No information is given on emergency operation in a control system operating in a torque manner.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to present means for emergency operation in this type of control system in the event of a malfunction of the final control element for the intake flow.
[0005]
[Means for Solving the Problems]
A target torque is set, and the torque output from the internal combustion engine is adjusted corresponding to the target torque. The torque to be output by the internal combustion engine is related to the internal combustion engine if the air supply to the internal combustion engine cannot be adjusted or can be adjusted incorrectly, at least by adjusting the fuel metering and / or the ignition angle It is controlled in such a way that the operating variable of the internal combustion engine or vehicle is limited to at least one predetermined value.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described in more detail with reference to the embodiments shown in the drawings.
[0007]
FIG. 1 shows a control device 10 for controlling an internal combustion engine (not shown), which is connected via an output line 12 to the cylinder of the internal combustion engine via a final control element 14. Means (control element) 18 for controlling the fuel metering, adjusting the ignition angle of the internal combustion engine (not shown) by means of the output line 16, and at least idling the internal combustion engine by means of the output line 20. Sometimes, the intake flow rate to the internal combustion engine is controlled via the final control element 22. The operating variables of the internal combustion engine and / or the motor vehicle are detected by suitable measuring devices 28 to 30 and supplied to the control device 10 via lines 24 to 26. The control device 10 is connected to another control device 34, preferably an ABS / TCS control device and / or a transmission control device, via a communication system 32, for example a CAN bus system, to control the internal combustion engine.
[0008]
A target torque to be output by the internal combustion engine is transmitted from the control device (s) 34 to the control device 10 via the communication system 32. This is transmitted, for example, from a control device for an automatic transmission to prepare a target output torque at the transmission output, and when at least one of the drive wheels has an excessive slip tendency from the ABS / TCS control device. It can be transmitted to prepare a prescribed output torque, or this may be a target value set by the driver operating the accelerator pedal. The control device 10 takes this target torque value into account, in some cases, operating variables supplied by lines 24 to 26, such as engine speed, engine temperature, load conditions, etc., as is known from the prior art described above. The final adjustment value of the control element 22, the correction value of the ignition angle determined as a function of the engine speed and the air flow rate, and / or the injection of the individual cylinders to be shut off in some cases Convert to the determination of the number. The quantity to be injected is then determined individually for each cylinder as a function of engine speed and air flow.
[0009]
In addition to this type of control system, where the final control element 22 is electrically adjustable over the entire operating range as a function of the driver's desire, in another embodiment, the final control element 22 is simply: The supply of air in an idling state of the internal combustion engine is determined within the range of idling control. In this case, the supply of air to the internal combustion engine is adjusted by the driver through a mechanically connected accelerator pedal, while the target value for the engine torque to be output preferably has a tendency for the drive wheels to rotate. Sometimes transmitted from the ABS / TCS controller through the communication system 32.
[0010]
FIG. 2 shows a schematic block circuit diagram for implementing the procedure according to the invention within the controller 10 by way of example of a “drive-by-wire” system with traction control intervention. Show. In this case, a value related to the target torque MSollASR when the drive wheel tends to spin and a value related to the target torque MSollfa set by the driver are supplied to the control device 10 through the communication system 32. These target values, which are a measure of the torque prepared at the output of the engine, are supplied to connection points 100 and 102, and at these connection points lines 106 and 107 are used to determine the loss torque Mverl. Supplied from the characteristic diagram block 104. Here, the target value is corrected by the loss torque of the engine, that is, by the torque component that the engine has to procure to compensate for the loss. The characteristic block 104 is supplied with signal values relating to the engine temperature Tmot and the engine speed Nist through lines 24 and 26. Means for determining the torque loss from the engine temperature and the engine speed are known from the prior art. The corrected target value indicates the target value (MvSollASR, MvSollfa) for the combustion torque to be generated by the engine.
[0011]
Line 110 leads from connection point 102 to maximum value selection stage 112, from which line 114 leads to minimum value selection stage 116. Line 118 leads from connection point 100 to minimum value selection stage 116. The output line 120 of the minimum value selection stage 116 leads to the calculation stage 122, which constitutes the lines 12, 16 and 20 of the control device 10. Line 124 leads from connection line 110 to minimum value selection stage 126. Further, line 128 leads from line 120 to minimum value selection stage 126. Line 130 is led from the characteristic diagram block 132 to the maximum value selection stage 112 for the determination of the torque requirement Mll of the idling vehicle. Some of lines 24 through 26 lead to characteristic diagram block 132. The output line 134 of the minimum value selection stage 126 leads to the maximum value selection stage 136, and the output line 138 of the maximum value selection stage leads to the calculation stage 122. Line 140 leads from line 106 to connection point 108. Further, a line 142 is routed from the integration block 144 to this connection point, and an input line 146 of this integration block is routed from a further connection point 148. One of the lines 24 to 26 and the line 150 are led to this connection point, and the line 150 is connected to the characteristic diagram block 152. Next, at least one of the lines 24-26 is led to the characteristic diagram block 152. The output line 154 of the connection point 108 leads to the switching element 156, and a line 158 is further led from the line 130 to this element. The switching element 156 is operated by the control block 160 through a line 162, to which at least one of the lines 24 to 26 is led. The output line 164 of the switching element 156 leads to the maximum value selection stage 136.
[0012]
After the target combustion torques MvSollASR and MvSollfa are determined at connection points 100 and 102, the target combustion torque MvSollASR for TCS operation is compared with the required torque during idling in the maximum value selection stage 112. This torque requirement is determined in the characteristic diagram block 132 in a known manner as a function of load conditions such as an air conditioning system, a transmission power steering system, and the like. The maximum value selection stage 112 sends out the larger one of the two values in order to avoid setting the target torque that leads to the stop of the internal combustion engine. The target combustion torque MvSollASR / LL formed by this method is supplied to the minimum value selection stage 116, and the smaller one of the target torque values supplied here is selected (when the TCS is not operating). The target combustion torque MvSollASR is always greater than the maximum target combustion torque MvSollfa that can be achieved by the driver). The smaller value sent by line 120 corresponds to the target torque MvSollfu for adjusting the charge, i.e. the intake flow to the internal combustion engine. This target value is converted in the calculation stage 122 into an operation signal for controlling the final control element 22 in preparation for the target combustion torque MvSollfu in a manner known from the prior art.
[0013]
In parallel with this control of the air flow (see block means 170 shown in broken lines), fuel metering and / or adjustment of the ignition angle is provided. For this purpose, the target combustion torque MvSollfu is compared with the target combustion torque MvSollASR in TCS operation in a minimum value selection stage 126 similar to the minimum value selection stage 116, and each smaller value is sent through line 134. In the maximum value selection stage 136, this value is compared with the idling required value Mllr, and the larger value is output to the calculation stage 122 as a target torque value for controlling injection and ignition. In this calculation stage 122, this target value is prepared in a known manner, possibly by correcting the ignition angle and by stopping the injection pulse. Maximum value selection stage 136 prevents torque demands below the required torque during idling. The torque requirement is determined by the torque requirement Mll of the characteristic block 132 during idle idle (position of the switching element 156 indicated by the solid line) in the air conditioning element, and ( The position of the switching element 156 indicated by a broken line) is set within the range of the rotational speed limit through the line 154. The idling state with or without a fault is in this case determined by the control block 160 based on the position of the accelerator pedal, the engine speed, etc., and the switching element 156 is controlled accordingly. In this case, when the driver desires idling (idling position of the accelerator pedal), at least a failure is detected when the engine speed increases beyond a predetermined limit speed. In order to limit the engine speed during idling, the target limit value Nbeg is read in block 152, preferably based on operating variables such as the position of the accelerator pedal, and compared to the actual speed at connection point 148; At least when the actual rotational speed is larger than the limit rotational speed, the difference signal dn is supplied to the integration block 144. This integration block integrates the difference between the target value and the actual value to form a torque correction value Mbegkorr for restriction and outputs this value through line 142. This correction value is compared with the loss torque for calculation of the target combustion limit torque Mllbeg at the connection point 108 and supplied to the maximum value selection stage 136. If this value is greater than the smaller value of the minimum value selection stage 126, it is sent as the target combustion value for injection stop and ignition.
[0014]
This ensures emergency operation according to the invention. If the final control element 22 is in the open throttle position due to a malfunction, a torque greater than the engine torque set by the driver is set due to the malfunction even when not idling. Corresponding correction of the torque output by the engine is ensured by changing injection and ignition to achieve safe emergency operation. Therefore, in the event of a malfunction of the final control element 22, the actual engine torque is limited in a comfortable and safe manner to a predetermined value depending on the driver's wishes.
[0015]
If the control system is not a “drive-by-wire” system, the block means 170 enclosed by the broken line is omitted. The target engine torque for adjusting the charging supplied to the minimum value selection stage 126 then corresponds to the driver setting MvSollfa.
[0016]
FIG. 3 shows a flow diagram outlining the implementation of the procedure according to the invention as a computer program.
[0017]
After the program component starts at a given time or as a function of crankshaft angle, the operating variables necessary for the next calculation are read in a first step 200. These variables include the target engine torque MSollASR when there is a tendency to slip, the target torque MSollfa set by the driver, the engine temperature Tmot, the actual rotational speed Nist, and in some cases the position of the accelerator pedal, gear position, There are additional operating variables such as the state of the load. In the next step 202, based on the characteristic diagram, characteristic curve or table, the loss torque Mverl is determined as a function of the actual speed and the engine temperature, and the required torque Mll during idling is preferably the gear position and load conditions etc. And the target speed limit Nbeg is determined as a function of operating variables such as load state, accelerator pedal position, travel speed, and the like. In the next step 204, adjustment is made for filling based on the target torque MSollfa set by the driver, the target torque MSollASR set when there is a slip tendency, the loss torque, and the torque requirement during idling. The power target combustion torque MvSollfu is calculated. The target combustion torque for this filling is then compared with the target torque MvSollASR set when there is a tendency to slip in the next step 206, with the smaller value respectively being the target combustion torque MvSollEZA for injection and ignition. As determined. In the next interrogation stage 208, it is checked whether the internal combustion engine is in the idling range without malfunction. As stated above, this check is based on the accelerator pedal position or throttle valve position and the engine speed. If the engine is idling without failure, the idling torque requirement Mll is determined as the torque requirement Mllr during idling in step 210 and the target combustion to be adjusted for injection and ignition in the next step 212 The torque MvSollEZ is determined from the target combustion torque MvSollEZA and the required torque amount Mllr during idling. At this time, the larger one of the two values is determined as the target combustion torque MvSollEZ for injection and ignition. In the next step 214, the throttle valve position DK, the ignition angle Z and / or the injection stop E are adjusted in a known manner on the basis of the target combustion torque MvSollEZ for injection and ignition and the target torque MvSollfu for filling. The program component is then terminated and repeated at a given time or given angle. If in step 208 it is found that the engine is idling with a malfunction, in step 216 a difference delta (Δ) between the target speed limit Nbeg and the actual speed Nist is formed, This difference is then converted to a torque correction value Mbegkorr by integration in the next step 218, possibly in order to bring the actual value closer to the target value. As a result, in step 220, the torque requirement Mllr during idling is calculated from the sum of the torque correction value Mbegkorr and the loss torque Mverl from step 218, and the procedure continues to step 212 and targets for injection and ignition. Torque is determined.
[0018]
If the limit value is dependent on the driver's wishes, in general when there is a malfunction, the speed is also limited to outside the idling state to ensure emergency operation.
[0019]
As described above, when there is a malfunction of the final control element 22, the emergency operation is ensured by these means, but at least the engine speed is limited to a predetermined limit value. Or, in some cases, it is guaranteed to be limited as a function of the driver's wish, in which a comfortable and safe limitation is made possible based on the torque calculation. There is no need for large-scale means to detect dysfunction.
[0020]
As an alternative to a suitable limit on engine speed, in other embodiments the output torque or engine output or travel speed is limited in a similar manner.
[0021]
In addition to or as an alternative to the torque reduction when there is a drive wheel slip tendency as described in the preferred embodiment, the target torque value is included by engine drag torque control in a corresponding manner, This target torque value, along with the combustion torque set by the driver, is used to set the limit torque for the load value, the maximum speed, and the minimum selection fill along with the target combustion torque of the traction control system by filling. Together with the starting torque to be selected.
[0022]
In yet another advantageous embodiment, the target engine torque set by transmission control is a target combustion torque for intervening in injection and ignition by subjecting the target torque of the traction control system to a minimum value selection. Can be used in connection with the determination of
[0023]
Furthermore, in an advantageous embodiment, in addition to limiting the engine speed during emergency operation according to the procedure according to the invention, the maximum speed or maximum speed limit is determined by the maximum speed and the actual speed. Torque correction, which would be given by forming the difference signal in an analog fashion from the difference between the two, is integrated and connected to the determined target combustion torque for injection and ignition intervention Configure the value.
[0024]
Therefore, in summary, when there is a malfunction in the final control element that regulates the air supply or in the mechanical connection from the accelerator pedal to the throttle valve, the target torque set to control the internal combustion engine is It should be appreciated that operating variable setting limits related to engine power are corrected in such a way that they are protected within and / or outside of internal combustion engine idling. Torque correction is performed by stopping a predetermined number of injections and / or by correcting the set ignition angle.
[0025]
【The invention's effect】
The procedure according to the invention enables emergency operation in the event of a malfunction of the final control element that influences the intake flow to the internal combustion engine, in which comfort and reliability of operation are ensured.
[0026]
In particular, a substantial increase in comfort is possible due to the continuous change of the target engine torque with respect to emergency operation.
[0027]
Furthermore, the procedure according to the invention enables an emergency operation in a control method or control device for controlling an internal combustion engine based on a target engine torque to be output by the internal combustion engine.
[0028]
A further advantage is that expensive means for fault detection in the final control element can be abandoned.
[Brief description of the drawings]
FIG. 1 shows a schematic block circuit diagram of a control device for an internal combustion engine.
FIG. 2 shows a schematic block circuit diagram of a control device for performing an emergency action in the event of a malfunction of the final control element with respect to the intake flow rate.
FIG. 3 shows the implementation of the procedure according to the invention as a computer program on the basis of a flow diagram.
[Explanation of symbols]
10: Control device, 14, 18, 22: Final control element,
28 to 30: measuring device, 32: communication system, 34: another control device.

Claims (9)

In a method for controlling an internal combustion engine configured such that a target torque is preset and torque output by the internal combustion engine is adjusted according to the target torque,
The target torque preset for controlling the internal combustion engine is related to the output of the internal combustion engine if the air supply to the internal combustion engine cannot be adjusted or can be adjusted incorrectly Alternatively, when the actual value of the operating variable is larger than the predetermined limit value in order to correct the predetermined limit value of the vehicle operating variable, the difference between the actual value and the predetermined limit value is calculated. The target torque is corrected by a correction value formed by integrating with an integrator,
The corrected target torque is controlled by adjusting the fuel metering and / or the ignition angle,
A method for controlling an internal combustion engine, characterized in that a final control element is provided for regulating the air supply to the internal combustion engine.   The method according to claim 1, wherein the operating variable is engine speed, engine torque, engine output, or traveling speed.   The method according to claim 1, wherein the limit value is set in at least one of an idling state and a non-idling state.   Intervening in fuel metering and ignition angle may be either by correcting the ignition angle in preparation for the target torque and / or by stopping a predetermined number of injections into individual cylinders in preparation for the target torque. The method according to claim 1, wherein the method is performed by:   Maintains the target torque preset by the driver, the target torque preset by functions such as transmission control and traction force control, the required torque when idling in the idling state of the internal combustion engine, and the limit rotational speed The method according to any one of claims 1 to 4, wherein a target combustion torque for injection intervention and ignition intervention is set based on all of the correction torque amounts for performing.   6. The method according to claim 1, wherein the target combustion torque for injection intervention and ignition intervention is corrected to obtain a maximum speed limit or a maximum speed limit. . The final control element for adjusting the air supply to the internal combustion engine is a final control element for adjusting the air supply over the entire travel range, and the final control element prepares a target combustion torque for filling Being tuned for,
The target combustion torque is a target torque preset by the driver, a target combustion torque for charging set by a function such as traction force control and engine drag torque control, a load value limit, a maximum engine speed limit, and 7. The method according to claim 1, wherein the engine is formed on the basis of a function such as a starting torque limit and a target combustion torque for air filling set by a torque requirement during idling. The method according to one.   The method according to claim 1, wherein the limit value depends on a driver's desire or the position of an accelerator pedal. A final control element for at least partial adjustment of the air supply to the internal combustion engine,
Means for metering fuel and for adjusting the ignition angle of the internal combustion engine;
Means for adjusting at least one preset target torque;
In an apparatus for controlling an internal combustion engine comprising:
The internal combustion engine associated with the output of the internal combustion engine when there is a malfunction of the final control element that at least partially adjusts the air supply to a preset target torque for controlling the internal combustion engine Or a means for correcting a predetermined limit value of the operating variable of the vehicle so that the actual value and the predetermined limit value when the actual value of the operating variable is greater than the predetermined limit value; Means for integrating the difference between the two by an integrator to form a correction value for the target torque,
Means for controlling the target torque configured to control the target torque corrected by adjustment of one or both of fuel metering and ignition angle, for controlling the internal combustion engine Equipment.

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