EP1277940B1 - Method and device for the operation of a drive engine - Google Patents

Description

State of the art

The invention relates to a method and a device for operating a drive motor of a motor vehicle.

In order to operate drive motors for vehicles, electronic control systems are used with the aid of which the performance parameter (s) that can be set on the drive motor are determined as a function of input variables. Some of these electronic control systems operate on the basis of a torque structure, ie by the driver and possibly additional systems, such as cruise control, electronic stability programs, transmission controls, etc., are set as setpoints for the control system torque values, by the control system, taking into account other variables in settings for the or the performance parameters of the drive motor to be implemented. An example of such a torque structure is from the DE 42 39 711 A1 ( U.S. Patent 5,558,178 ) known.

From the EP 1 052 390 A2 is a switching between a torque controller and an idle controller by correcting the output of the torque controller known in such a way that the switching takes place as gently as possible. The correction adjusts the output of the torque controller to the output of the idle controller. The correction takes place only when the accelerator pedal is released.

From the US 5,901,682 is the transition between two different operating modes with different calculation of the injection quantity known. In the transition region, a weighted calculation of the injection amount is performed according to the two modes.

From the EP 0 494 337 A2 It is known to control electromotive control of the actuator-side actuator from the occupied idle position with a control of the accelerator pedal-side actuator during its adjustment by means of the accelerator pedal, wherein the opening characteristic of the actuator-side actuator is designed so that it runs in a steadily decreasing distance in front of the accelerator pedal actuator , wherein the distance between the accelerator pedal-side actuator and the throttle-side actuator is at the latest in a position LL _max equal to zero.

From the US 4,509,478 a fuel control system for an internal combustion engine is known in which the idle fuel amount is set to maintain a predetermined desired idle speed and in which the transition between the idle fuel amount and a map-based Nichtleerlaufkraftstoffmenge is designed in the sense of a smooth engine operation.

To maintain engine operation, in known control systems with non-pedaling accelerator pedal and low rotational speeds, an idle controller takes over the task of keeping the engine speed at a safe level for engine operation to stabilize. However, this idle controller should not affect the moment of the drive motor when the accelerator pedal and higher speeds, the engine torque should be adjusted according to the driver's request. The transition between these two operating states is to be realized so that the operation of the engine control and ride comfort are influenced as little as possible. Furthermore, an optimized integration of this transition function in a torque structure, which is independent of the respective engine type (gasoline engine, diesel engine), to strive for.

Advantages of the invention

By connecting the idle controller portion on the resulting target torque after completion of the coordination of driver command torque and target torque other control systems and by the operating variable dependent controlled replacement of the idle controller contribution, it is possible to optimally fit the idle control in a torque structure that can be used regardless of the engine. Torque structure and the replacement or resumption of the idle controller in the transition from idle mode and non-idle mode can thus be carried out the same for all engine types.

Advantageously, it is possible for gasoline and diesel engines to allow the same (identical) structure for the moment coordination including the connection of the idle control. The contribution of the idle controller is influenced in the same way for gasoline and diesel engines in the transition from idle to non-idle operation and / or vice versa.

Particularly advantageous is a time-controlled replacement of the contribution of the idle controller on actuation of the accelerator pedal. This is because no change or influence of the engine torque by idle controller takes place after expiration of a temporary transition process. In particular, torque jumps that affect the ride comfort and caused by different physical translation of the idle control torque on the transmission, avoided.

Further, the fact that no additional idler control part is generated while driving supports the requirement for constant gear ratio changes, i. E. that before and after a gear change, the same Radmomentenwert is set.

Advantageously, as part of an alternative solution, the engine speed-dependent replacement of the idle controller contribution. In a defined speed range above a speed threshold, the desired property of wheel torque constant gear changes is achieved here as well.

In a particularly advantageous manner, it is possible to avoid a double compensation of torque losses, which are not available for the drive of the vehicle, by an existing pilot control of these torque loss and the idle controller. This is achieved by activating the loss torque feed forward by weighting with the complement of the weighting factor of the idle speed control. In other words, in the replacement of the contribution of the idle control a corresponding (speed or time-dependent) adjustment of the loss torque feedforward control is made.

Advantageously, the influencing function of the idle controller depends on further operating variables, eg engine temperature, outside temperature, air pressure, etc.

Further advantages will become apparent from the following description of exemplary embodiments or from the dependent claims.

drawing

The invention will be explained in more detail below with reference to the embodiments shown in the drawing. FIG. 1 shows an overview image of a control device for operating a drive motor, while in FIG. 2 a preferred embodiment of a torque structure in connection with the control of a drive motor is shown with reference to a flowchart, if it is relevant in view of the described approach. The FIGS. 3 and 4 show two preferred embodiments for forming a correction factor, with the help of the idle controller is influenced in the transition between idle and non-idle.

Description of exemplary embodiments

FIG. 1 shows a block diagram of a control device for controlling a drive motor, in particular an internal combustion engine. A control unit 10 is provided, which has as components an input circuit 14, at least one computer unit 16 and an output circuit 18. A communication system 20 connects these components for mutual data exchange. The input circuit 14 of the control unit 10 are supplied to input lines 22 to 26, which are designed in a preferred embodiment as a bus system and via which the control unit 10 signals are supplied, which represent to be evaluated for controlling the drive motor operating variables. These signals are detected by measuring devices 28 to 32. Such operating variables are in the example of an internal combustion engine accelerator pedal position, engine speed, engine load, exhaust gas composition, engine temperature, etc. About the output circuit 18, the control unit 10 controls the power of the drive motor. This is in FIG. 1 symbolized by the output lines 34, 36 and 38, via which the fuel mass to be injected, the ignition angle and at least one electrically actuable throttle to adjust the air supply are operated. The air supply to the internal combustion engine, the firing angle of the individual cylinders, the fuel mass to be injected, the injection time point and / or the air / fuel ratio, etc., are set via the illustrated adjusting paths. Furthermore, further control systems of the vehicle may be provided, which transmit input variables 14, for example torque setpoints, to the input circuit 14. Such control systems are, for example, traction control systems, vehicle dynamics controls, transmission controls, engine drag torque control, speed controller, speed limiter, etc. In addition to these external setpoint specifications, which may include a setpoint input by the driver in the form of a driving desire or a maximum speed limit, internal specifications for the drive motor are provided , Eg the output signal of an idle speed control, a speed limit, a torque limit, etc ..

Similarly, with adjusted output and input variables, the control system will also work with alternative drive concepts, e.g. Electric motors, used.

To maintain the engine operation when accelerator pedal nichtgetretenem and low speeds, an idle controller is provided. This determines, for example, depending on the speed deviation between a target and an actual speed by means of a predetermined control strategy (eg proportional, integral and / or differential component) a contribution (eg torque change quantity or desired torque) which is applied to the resulting setpoint torque value for the drive motor. In the preferred embodiment, this connection is performed as an addition. In other embodiments, the idle contribution, for example, will be normalized, so that the connection takes place by means of multiplication. The connection of the idle controller takes place to the resulting target torque, which is formed by coordination of driver command torque and the desired torque of other control systems, external and possibly internal default variables. As a result, an influencing of the wheel torque by the idle controller is avoided, as mentioned above, so that gear torque constant transmission changes are achieved.

When the accelerator pedal is actuated, a time-limited process is started in the preferred embodiment, during which time the idle controller contribution is continuously reduced to zero. In the preferred embodiment, a factor is formed depending on the time, which assumes the value zero starting at one after a predetermined period of time and with which the idle controller contribution is weighted (multiplied). After the predetermined period of time, the idle controller contribution is zero. Upon release of the accelerator pedal when it assumes its idle position, this factor is abruptly set to one in the preferred embodiment to allow the idle controller to immediately intervene to maintain engine operation. In other embodiments, a time-dependent control of the idle controller contribution is also applied here, wherein the factor increases from zero to one. The time periods for detachment and switching on the idle controller are preferably different, wherein when the controller is turned on a shorter time period is selected than at the replacement.

An alternative solution shows a corresponding replacement of the idle controller depending on the speed instead of the time. It is driven with increasing speed, the Leerlaufreglerbeitrag to zero, in the preferred embodiment, the above-mentioned factor is formed according to a speed-dependent characteristic. Here again, when the engine speed drops, a speed-dependent regulation of the idling controller contribution is provided in accordance with the same or a different characteristic, the above-mentioned factor being formed accordingly.

Another alternative is to associate with the idle controller output signal maximum and minimum value limits to which the signal is limited. The release or control is then realized by manipulating these limits, wherein at the replacement of e.g. the maximum value is preferably reduced to zero depending on the time or speed, and / or the minimum value is set to zero. The control is reversed.

This in FIG. 2 The flow chart shown describes a program of a microcomputer of the control unit 10, wherein the individual blocks of the representation of FIG. 2 Programs, program parts or program steps, while the connecting lines represent the signal flow. In this case, the first part up to the vertical dashed line in a first control unit, there also in a microcomputer, run while the part runs after this line in a second control unit.

First, signals are supplied which correspond to the vehicle speed VFZG and the accelerator pedal position PWG. These variables are converted in a map 100 into a torque request of the driver. This driver command torque, which represents a default value for a torque on the output side of the transmission or for a wheel torque, is fed to a correction stage 102. This correction is preferably an addition or subtraction. The driver's desired torque is corrected by a weighted loss torque MKORR, which was formed in the connection point 104. In this is the supplied, by means of the translation Ü in the drive train and possibly other translations in the drive train output side of the transmission to a moment after the transmission, preferably a wheel torque converted loss moment MVER weighted by a factor F3. The weighting is preferably done as a multiplication. The factor F3 is formed in 106 from the value PWG representing the accelerator pedal position and, if appropriate, additionally a variable NMOT representing the engine speed.

The driver's request MFA in this way is supplied to the moment coordination to form a resulting default torque MSOLLRES. In the example shown, in a first maximum value selection stage 108, the maximum value of driver desired torque MFA and the default torque MFGR of a vehicle speed controller is selected. This maximum value is applied to a subsequent minimum value stage 110, in which the smaller of this value and the setpoint torque value MESP of an electronic stability program is selected. The output quantity of the minimum value stage 110 represents a torque magnitude on the output side of the transmission or a wheel torque quantity which is converted into a torque magnitude on the output side of the transmission by taking into account the transmission ratio Ü and, if applicable, further transmissions in the drive train on the output side or on the output side the drive motor is present. This torque magnitude is coordinated in a further coordinator 112 with the target torque MGETR a transmission control. The target torque of the transmission control is formed according to the needs of the switching operation. In the subsequent maximum value selection stage 114, the resulting target torque MSOLLRES is then formed as the larger of the torque values minimum torque MMIN and the output torque of the coordination stage 112. The minimum torque is derived in a preferred embodiment of the loss moment.

The moment coordination is shown above by way of example only. In other embodiments, one or the other default torque is not used for coordination or further default torques are provided, for example a moment of a maximum speed limit, an engine speed limit, etc.

The resultant setpoint torque formed in the manner described above is supplied to a correction stage 116, in which the setpoint torque is corrected with the loss torques to be applied by the engine and not available to the drive. If necessary, the loss moments MVER are weighted in a weighting stage 118 with a factor F2. Depending on the version, this is constant (also 1) or depends on the operating variable, eg motor speed dependent. The torque losses MVER itself are formed in the addition stage 120 from the torque requirement MNA of ancillary units and the engine lost torque MVERL. The determination of these variables is known from the prior art, wherein the torque requirement depends on the operating status of the respective auxiliary unit in accordance with characteristics or the like, the engine torque loss is determined depending on engine speed and engine temperature. The loss moment MVER formed in this way is then provided to the correction stage 104, wherein a conversion of the torque loss using the known gear ratio Ü and possibly further translations in the drive train on the output side of the transmission to the level of getriebeausgangs- or Radmomente done.

The output of the correction stage 116, which in the preferred embodiment is an addition, is a default value for the torque to be generated by the drive unit for the drive, taking into account the internal losses and the torque required to operate ancillary units (eg air conditioning compressor) motor torque). This default torque is corrected (preferably added) in a further correction stage 122 with the output variable DMLLR of the idle controller weighted in a correction stage 124. The weighting factor F1, with which the output variable of the idle controller is weighted in 124, is speed-dependent and / or time-dependent, wherein when leaving the idling range, the factor decreases with time or with increasing engine speed to zero. The default variable MISOLL is then implemented in 126 as known from the prior art in manipulated variables for adjusting the performance parameters of the drive motor, in the case of an Otto internal combustion engine in air supply, fuel injection and ignition angle, in the case of a diesel engine in fuel quantity.

In one embodiment, in addition to time or speed, further operational quantities are taken into account in determining the deceleration of the idle control portion, e.g. Motor temperature, outside temperature, outside pressure, etc.

The idle controller engages with its contribution DMLLR in the direction of action after the torque coordination (108 to 114) in the torque input, in which it corrects the resulting target torque MSOLLRES according to its output signal. In the idle control area, the correction is complete. In the transition from idle to non-idle, the idle controller output is weighted at 124 by a factor of F1, which decreases from one to zero with time after actuation of the accelerator pedal or speed dependent. If the factor is zero, no idle controller part is switched on. Depending on the design, the idle controller itself can continue to be active and run at its limit in accordance with the speed ratios or can be stopped partially or completely by timing down the integral component, setting the proportional and differential component to zero or setting the integral component to the current value. In the embodiment of FIG. 2 the idle controller is also pre-controlled by the connection of the loss torque MVER in 116. This means that the idle controller only corrects the deviations between pilot values and the actual torque ratios. In other embodiments, this pre-control of the loss moments is missing, so that the idle controller corrects the total loss moments and the need of ancillary units. One intermediate solution is to weight in 118 the lost torque feedforward control with a factor F2 which is compensated in a complementary manner for the reduction of the open loop controller contribution. That is, as the weighting of the idle control contribution decreases in 124, it increases by incremental weighting of the feedforward control in step 118.

Essential for the operation of this arrangement is the formation of the factor F1, which causes the replacement and possibly in an analogous manner, the Aufsteuerung the idle controller contribution. A first solution is in FIG. 3 shown. There, the factor F1 is triggered in time by the operation of the accelerator pedal (signal PWG> 0) reduced from its value one to zero. An example is in FIG. 3 shown, in which the reduction is made linearly. In other embodiments, other time functions, such as exponential, step-shaped time functions, etc. are used. The pedal is actuated at time T0, after expiration of a certain predetermined time period at time T1, the factor F1 is then reduced to the value zero. This means a complete disappearance of the effect of the idle controller in the context of torque control. If the pedal is released, that is, the drive motor returns to idle mode, the idle controller portion is controlled in one embodiment time-dependent again to its full value.

Instead of the accelerator pedal position alone, a combination of accelerator pedal position and speed or driving speed is crucial in determining the transition in other embodiments. Another embodiment initiates the procedure shown when operating the pedal beyond a certain extent.

A second embodiment is disclosed in FIG. 4 shown. There is a characteristic 150 is provided, which is supplied to the engine speed NMOT. In this characteristic, the factor F1 is plotted against the engine speed. For speeds below the speed N1 the factor is 1, for speeds greater than N2 it is zero. In the area between the rotational speeds N1 and N2, a course of the factor F1 is given, whereby it declines with increasing rotational speed in the direction of zero. The illustrated linear dependence between factor F1 and speed is exemplary. In other versions, other dependencies are chosen. In the preferred embodiment, N1 is a speed that is just above the idle speed (eg, 900 rpm), while the second speed N2 is a larger speed, eg, 1500 rpm. Depending on the engine speed From the characteristic curve 150, the value of the factor F1 is read out, which is then weighted according to its size, the effect of the idle controller in the context of the torque control shown. If the rotational speed returns to the range of rotational speeds N1 and N2, the idling-control component is, in one embodiment, driven up to its full value as a function of rotational speed.

The above embodiment in which the release of the idle controller contribution is via weighting factors is exemplary. In other embodiments, this is done by appropriate weighting of the controller parameters, e.g. of the integral part (whereby proportional and derivative parts can be set to zero). Another possibility of implementation is to subtract moment contributions from the current idle controller contribution as a function of the rotational speed or the time until the resulting idling controller contribution is zero.

The illustrated procedure is used in an analogous manner in connection with the control of electric motors.

Furthermore, in one embodiment, to determine the speed-dependent variation of the idle controller signal, not the engine speed but a, e.g. used to the idling target speed, normalized size. This is advantageous when using an operating state-dependent (normalized) speed threshold for the idling control, the activation of which falls below this speed threshold by the (normalized) engine speed.

Claims (12)

1. Method for operating a drive engine, wherein as a function of the driver's request and further predefined variables a resulting predefined variable for controlling the drive motor is acquired, wherein in addition an idling controller forms a correction variable as a function of the engine speed, characterized in that the correction variable of the idling controller is connected to the resulting predefined variable, wherein when there is a changeover from the idling mode into the non-idling mode or vice versa, the correction variable of the idling controller is changed as a function of the engine speed or as a function of time.
2. Method according to Claim 1, characterized in that predefined variables and the correction variable are torque variables which represent wheel torques, engine output torques or indexed engine torques.
3. Method according to one of the preceding claims, characterized in that time-dependent decreasing or increasing of the correction variable of the idling controller occurs when the accelerator pedal is activated.
4. Method according to one of the preceding claims, characterized in that, when the accelerator pedal is activated, a factor with which the correction variable of the idling controller is weighted is changed as a function of time.
5. Method according to Claim 4, characterized in that the factor is changed from one to zero, or vice versa, as a function of time.
6. Method according to one of the preceding claims, characterized in that a factor with which the correction variable of the idling controller is weighted is formed as a function of the engine speed, wherein the factor drops if the engine speed rises.
7. Method according to Claim 6, characterized in that the factor changes from one to zero as the engine speed rises.
8. Method according to one of the preceding claims, characterized in that torque losses are formed which represent the torque requirement of secondary loads and/or the torque which is to be applied as a result of internal friction of the drive motor, wherein this torque loss value is applied to the resulting predefined variable and the torque loss variable which is applied is weighted in the opposite direction to the correction variable of the idling controller.
9. Method according to one of the preceding claims, characterized in that the correction variable of the idling controller is limited to a maximum value and/or a minimum value, wherein, at the transition from the idling mode into the non-idling mode or vice versa, the maximum value and/or the minimum value are changed as a function of the engine speed or as a function of time.
10. Device for operating a drive motor, having a control unit which forms, from a driver's request variable and predefined variables of further control systems, a resulting predefined variable for controlling the drive engine, which device comprises an idling controller which forms a correction variable, characterized in that the electronic control unit has means which apply the correction variable of the idling controller to the resulting predefined variable, wherein at the changeover from the idling mode into the non-idling mode or vice versa, the correction variable of the idling controller is changed as a function of the engine speed or as a function of time.
11. Computer program with program code means for carrying out all the steps of any of Claims 1 to 8 when the program is executed on a computer.
12. Computer program product with program code means which are stored on a computer-readable data carrier in order to carry out the method according to any one of Claims 1 to 8 when the program product is executed on a computer.

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