SE520808C2 - Method and apparatus for controlling an internal combustion engine in a vehicle - Google Patents

Abstract

The control method uses the required output torque of the engine for calculating the quantity of air to be supplied to the engine, with corresponding adjustment of the engine ignition angle, the mixture ratio and/or the number of engine cylinders brought into operation. Base values for the engine ignition angle, the mixture ratio and the number of operative engine cylinders are determined from the actual operating point of the engine when no external controls or restrictions are in use.

Description

520 808, Tjf? ¶F;:} jIï * i 2 basic ignition angle and basic mixing setting and / or the number of combustion cylinders in the respective operating point of the internal combustion engine.

It is further particularly advantageous that the characteristic used for calculating the setpoint value from the setpoint value is the inverted characteristic already used for calculating the torque from measured quantities. Therefore, the additional assembly is very small in the preparation of characteristic data and their generation.

It is particularly advantageous to take into account the basic efficiency of the ignition angle, the mixing setting and / or the number of combustion cylinders when calculating the set-top filling.

Additional advantages appear from the following description of embodiments and from the dependent claims, respectively.

Drawings The invention will be described in more detail below in connection with the embodiments shown in the drawings, whereby. G. 1 shows in block diagram representation the control of the internal combustion engine on the basis of a burst torque value while fi g. 2 shows, also in block diagram form, details of this control for determining the setpoint and fi g. 3 shows a fl fate diagram outlining a program for determining the setpoint value.

Description of embodiments I fi g. 1 shows a control unit 10, which via the symbolically represented output conductors 12, 14 and 16 controls the air supply to the internal combustion engine (throttle valve 17), the fuel supply (mixture composition and / or extraction) and the ignition angle. The control unit 10 is further fed by the input conductors 18, 20 and 22-24, which in a preferred embodiment are combined in a bus system (for example. F, v 1 520 808 3 CAN). Thereby, the input conductor 18 leads from at least one further control unit 26, for example a control unit for drive slip control, for engine torque lag control, for gearbox control, etc., to the control unit 10 and transmits a child torque formed by these control units for a torque to be emitted by the internal combustion engine. An additional input conductor 20 leads from an operating element 28 actuated by the driver, preferably from an accelerator pedal, to the control unit 10 and transmits the degree of influence ß of the operating element. or the vehicle, such as the engine speed, engine load (air mass, air volume, throttle valve position, inlet pipe pressure, etc.), engine temperature, travel speed, etc., to the control unit 10. In the preferred embodiment, the control unit 10 comprises at least one microcomputer implementing the program described below. solution. In Fig. 1, for the sake of clarity, this program, implemented in the microcomputer which is to implement the solution according to the invention, has been summarized in three blocks.

A first program block 34 is fed in addition to the degree of influence ß and the torque value from the at least one control unit 26 with additional operating variables, such as engine speed, vehicle speed, etc. (compare conductors 22a - 24a). In the programs coordinated with this program block in the microcomputer, a load torque value for the driver is generated from the predetermined characteristics of the accelerator ß for the accelerator pedal, taking into account the additional operating variables (at least the engine speed). Furthermore, functions are performed, such as speed and / or travel speed limits, which likewise generate a setpoint for the torque. From the generated or supplied setpoint torque values, the current is generated by maximum and / or minimum value selection and fed to a second program block 36.

This is fed with basic quantities regarding the ignition angle zwbas, the mixing setting lambas and / or the number of cylinders that are coldly removed redbas. Depending on these quantities and additional operating quantities, which are supplied via the conductors 22b - 24b, the setpoint value Nllbö generated in the program block 34 is converted, in a known manner 520 808 4, into control quantities for the fuel measurement and / or ignition angle and via the provision of a setpoint value to a control variable for the air intake to the internal combustion engine.

The basic quantities with respect to the ignition angle, the mixing composition and the number of cylinders removed are formed in predetermined characteristics 38.

These quantities represent the predetermined setting of the internal combustion engine at a current operating point. External interventions of the drive slimming control, limiting functions, etc. are not taken into account at these values. The basic quantities are thus the quantities that would occur if no interventions were made from outside or through limiting functions.

The basic ignition angle is then determined on the basis of the engine speed and the current filling from a characteristic. Correspondingly, there are characteristics or calculation steps at which the basic values are formed for the mixture composition and / or disconnection of individual cylinders. For example, in stationary drive states, the mixture composition can be shifted towards "stomachs" to improve fuel consumption and / or the harmful gases and / or in selected drive states (for example in stationary partial load) not all cylinders can be ignited. Thus, it is possible to arrange so that all the cylinders are only connected to the driver's corresponding power requirements, while in stationary or within the lower load range only a predetermined number of cylinders are allowed to be active in the internal combustion engine.

The corresponding basic values are used by the programs in the program block 36 for determining the control quantities for the setpoint value. Examples are known from the known technique mentioned in the introduction for calculating the setting of the fuel supply and the setting of the ignition angle.

The basis for these calculations is a torque model, which can be reproduced as follows: M1- = Klimpmmot, T1)> 520 808 5 The M activated depending on speed and load is the so-called optimal torque (high pressure torque at optimal (characteristic)), etazw is the ignition angle efficiency depending on the ignition angle distance from the optimal ignition angle, etalem is the lambda efficiency depending on the exhaust composition (= 1 for k = l) and etared is the efficiency of the active cylinders (= 1 when all cylinders are activated). Based on the basic quantities, the corresponding efficiency is referred to as etazwbas, etalambas and etaredbas.

The determination of the setpoint filling value of the internal combustion engine and thus of air supply from the setpoint value Mlbö, according to the solution according to the invention, is shown in fi g. 2.

This shows in detail a block 36 according to fi g. 1 with regard to the determination of the filling setpoint. The program block 36 is then fed with the setpoint value Nllbor, the basic quantities for the ignition angle (zwbas), for the mixing composition (Äbas) and / or for the number of disconnected cylinders (redbas) and at least with the engine speed as additional operating variable. The basic quantities are then fed to the characteristics 100, 102 and 104. These so-called efficiency characteristics convert these deviations of the basic values from optimal values (optimal ignition angle, stoichiometric mixture and all cylinders active) to a torque correction value (efficiency), so that the torque deviates from the optimum torque (highest efficiency) at the corresponding basic value. These efficiency characteristics are then determined experimentally and calculated for the individual quantities and the internal combustion engines. The torque correction values etazwbas, etalambase and / or etaredbas thus formed are taken into account in successive dividers 106, 108 and 110 when converting the torque to a fill setpoint. Thus, in a first divider 106, the ratio between the input torque and the torque correction value etazwbas is formed, which ratio in the divider 108 is divided by the torque correction value etalambase and the result is divided in the divider 110 by the correction ... =. | 520 eos ÛTffí fl Jšïïf “” 6 value etaredbas. The child torque NIIWK corrected in this way is input to a characteristic 112. This characteristic is further fed at least with the motor speed.

It is the inverted characteristic by means of which the optimum torque for the internal combustion engine is generated from the engine speed and sensed filling. From the entered quantities, a setpoint rlbö fl is read from the characteristic, which represents the setpoint derived from the setpoint moment. When setting this set-top filling by means of the throttle valve, the combustion engine generates the set-off torque Mlbör.

The formula used for determining the setpoint value is thus in summary: rlbm = f 'I [(MibÖ / etazivbas> The fill setpoint rlbm is entered at a maximum value selector step 114. This is further fed with a minimum fill value rlmm, which depending on the operating condition is determined from 116 different characteristics. 118 minimum depending on the engine speed This minimum fill value is in the case of freewheel with fuel disconnection designed with respect to the largest possible engine braking torque, while in normal operation without fuel disconnection it is designed with respect to maintaining the internal combustion engine drive fi at a lower speed. the values rlmm and rlbo fl are further fed as setpoint filling value rlbór This setpoint is converted within the framework of a control unit 116 to a setpoint control value for the throttle valve, which is set via the control unit's output conductor by corresponding control 12. Reproduction according to fi g. nningen is va fixed to the order of consideration of the correction values or to the concrete mathematical division operation. The characteristic f, which forms the basis for the determination of the set-top filling in inverted form, was also used in the determination of the torque of the internal combustion engine according to known technology (compare equation 1, KFWQPI).

The torque Mi constitutes the high-pressure torque, that is to say the torque «-. -. . . 520 808 7 generated by the internal combustion engine at the high pressure phase of combustion.

In an advantageous embodiment, the internal combustion engine is always driven during activation of all cylinders or even with stoichiometric mixing. In these cases, the corresponding correction value is waived.

In the preferred embodiment, the control unit 10 comprises at least one microcomputer, which performs the calculations described above within the framework of the programs. As an example of the realization of such a program, a fl island scheme is given in fi g. 3.

This is started at predetermined time intervals, for example a few milliseconds. At the first stage 200, the quantities NHW, Nmm, the motor load rl and any additional operating quantities are loaded. In the subsequent step 202, the basic ignition angle wzbas is formed from a predetermined characteristic according to the information on engine speed and load, while the basic value for the mixture composition and / or the number of cylinders to be disconnected is determined according to operating condition and driver behavior. Thereafter, in step 204, the torque correction values etazwbas, etalambase and / or etaredbas are determined from the predetermined efficiency characteristics. In the subsequent question step 206, it is tested whether the fuel supply is disconnected when idling. If so, according to step 208, the minimum filling rlmm is determined on the basis of a first characteristic f1 independent of the engine speed, otherwise according to step 210 on the basis of a second characteristic f2. During the step 212 following step 208 or 210, the product P is formed by the torque correction values. In the next step 214, the ratio between the burst moment and the product is determined by the correction values. This ratio is converted in the subsequent step 216 together with the engine speed by means of the predetermined characteristic to a fill setpoint rlbml. In the subsequent step 218, the maximum value is then generated from the fill setpoint and the minimum fill value and is determined as setpoint filling. In the subsequent step 220, from this setpoint filling value and additional operating quantities on the basis of at least one control circuit, a control signal t for the throttle valve is calculated, which control signal is emitted.

Claims (10)

.. t ... 520 808 P A T E N T K R A V A method of controlling an internal combustion engine in a vehicle, wherein a setpoint value is predetermined for the torque of the internal combustion engine, which setpoint is converted to a setpoint value for the combustion engine filling and this setpoint filling value is set by influencing the air supply to the internal combustion engine. , wherein at least one ignition angle setting for the internal combustion engine is taken into account when calculating the filling setpoint from the set torque value, characterized in that when setting the setpoint filling value from the setpoint value, a setting of the mixture composition and / or the number of cylinders to be disconnected is further considered. Method according to claim 1, characterized in that the basic quantities are formed for the ignition angle, the mixing composition and / or the number of combustion cylinders, these basic quantities constituting quantities which would be set at the actual operating point of the internal combustion engine when no extreme interventions or restrictions are active. Method according to one of the preceding claims, characterized in that from the deviation between the basic quantities and optimal quantities, at which the internal combustion engine has the greatest efficiency, correction values for the child torque are determined in proportion to predetermined efficiency characteristics. Method according to one of the preceding claims, characterized in that torque correction values and their efficiency are formed from the basic quantities, and with these values the torque is corrected. Method according to one of the preceding claims, characterized in that the setpoint filling value is determined from a predetermined characteristic in dependence on the corrected setpoint torque value and the engine speed. Method according to one of the preceding claims, characterized in that a minimum filling value is determined in dependence on the engine speed. Method according to one of the preceding claims, characterized in that in the case of disconnected fuel supply in neutral, a different fi / filling value is predetermined than outside this operating condition. Method according to one of the preceding claims, characterized in that the selection of the set-top filling value takes place between the minimum filling-in value and the calculated set-top filling value. in Method according to one of the preceding claims, characterized in that the air supply to the internal combustion engine is set in proportion to the setpoint filling value. 10. Device for controlling an internal combustion engine in a vehicle, with a control unit which generates a setpoint for a torque for the internal combustion engine, which setpoint is converted to a setpoint value taking into account at least one ignition angle setting of the internal combustion engine and this setpoint impact value the air supply for setting the setpoint torque value, characterized in that the control unit further considers a setting of the mixture and / or the number of cylinders to be disconnected when calculating the setpoint filling value.