EP1412630B1 - Method and device for operating a drive engine of a vehicle - Google Patents

Abstract

A method and a device for operating a drive engine of a vehicle are disclosed, in which a resultant set torque, for controlling the drive engine, is determined, dependent on the driver command torque and further set torque parameters. In order to limit the resulting set torque a minimum engine torque is provided, derived from the lost torques and which is dependent on the engine speed.

Description

State of the art

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

To drive drive motors for vehicles are electronic control systems used, with the help of which or the adjustable performance parameters of the drive motor be determined depending on input variables. Some of these electronic Control systems operate on the basis of a torque structure, i. H. from the driver and other control systems, such as cruise controls, electronic stability programs, Transmission controls, etc. are used as setpoints for the control system Torque values given by the control system under consideration Further operating variables in settings for the or the performance parameters of the drive motor be implemented. An example of such a torque structure is from DE 42 39 711 A1 (US Pat. No. 5,558,178).

From DE 196 12455 A1 a method for determining a target torque at the Clutch of a vehicle is known in which a setpoint torque consists of a torque factor, a maximum torque and a minimum torque is determined. The torque factor is derived from a pedal value and the speed. The maximum and the minimum torque will be dependent on the speed, a loss torque and the operating variables. The loss torque becomes dependent on the speed and the operating variables. In a block 81 of Figure 2, the torque factor also in response to a vehicle speed control by means of a maximum selection certainly. The maximum selection compares torque reduction excluded from the driver's request. The resulting target torque is multiplied the torque factor with the available torque range and subsequent addition of the minimum torque is formed.

From DE 197 39567 A 1 it is known, the output signal of the idle controller directly to the aufzuschalten as indicated motor torque predetermined driver request torque, the Driver request torque in addition the loss moments from internal engine friction and demand torque contains the ancillaries. The driver's request torque can not be this way be less than zero. If a torque reduction takes place by other control systems (eg gearbox, Stability control), a stalling of the engine is avoided because of this external intervention in the following linkage of the setpoint moments (torque coordination) because of the high driver's request torque finds no penetration. In its place, that comes along Loss torque and idle controller share increased driver torque required. In which Speed-dependent drag torque is a default size, which is a motor drag torque control given and with the remaining default size in the maximum selection 202 is coordinated. A limitation of the resulting target moment down as described above not necessary because instead of the driver's request torque the with loss torque and idle controller share increased driver torque comes to fruition.

The subject matter of DE 196 12455 A1, the formation of the driver's desired torque and the subsequent moment coordination on the level of the indexed moment, ie on the input side or motor output side. Thus, in the subject of DE 196 12455 A1 a moment coordination on different physical levels not possible. The same thing also applies to DE 197 39567 A1, in which the output signal of the idle controller directly is switched to the driver requested torque specified as the indicated engine torque, wherein the driver request torque in addition to the loss moments of internal engine friction and Demanding moments of the ancillaries contains. These from DE 196 12455 A1 and DE 197 39567 A 1 known solutions are specific to the circumstances in the control of a gasoline engine adapted and can be applied neither to other drive types nor to other moment structures, which represent the driver's request on Radmomentenebene map.

For example, as described in this prior art, the external interventions act torque reducing. In extreme cases, such an external intervention the rotation speed reduce the drive motor so far that the drive motor is strangled. An example of a solution that one Prevents stalling, there is DE 197 39 567 A1. There the output signal of the idle controller is directly to the ala indicated engine torque given driver request torque switched on, the driver's request torque additionally the Loss moments from internal engine friction and demand torque contains the ancillaries. The driver request torque can be up not be less than zero in this way. Is a torque reduction from other control systems (eg transmissions, Stability control), stalling the engine is avoided because of this external intervention in the subsequent Linking the set moments (torque coordination) because of the high Fahxerwunschmoments finds no penetration. At its place comes with loss moment and idle controller share increased driver torque required to carry. This solution is specific to the conditions in the control adapted to a gasoline engine and can not be applied to others Drive types still on other torque structures, for example on structures that require the driver to wheel torque level form in a simple way.

Advantages of the invention

By the specification of a motor minimum torque, which in the frame the moment coordination is taken into account, can be a common (identical) basic structure for coordination torque-influencing interventions for different drive types, For example, for gasoline engines, diesel engines or electric motors.

Advantageously, the idle controller is in such common basic structure as connection to the in the coordination formed resulting target moment, whereby different idle control concepts can be integrated are. For example, a typical for a gasoline engine Idle controller concept, which is a pilot control, a limited positioning time dynamics and a limited adjustment range has, as integrable, as an idle controller concept in a diesel engine without pilot control, with a short Positioning time and unlimited adjustment range.

In a particularly advantageous manner, the minimum torque, on which the resulting target torque is limited, speed dependent. This will be a touchdown point of the connected Idling torque specified, which takes into account whether in respective speed-dependent operating point of the idle controller Priority over the other interventions or not. So has in the lower speed range of the idle controller always Penetration, allowing for active external intervention thereby Stalling is avoided.

In a particularly advantageous manner, the resulting Target torque, which formed in the moment coordination is limited to a defined lower value that the which can be realized without stalling at the current operating point is. If the minimum moment is chosen to be the driver's request on Radmomentenebene with released pedal and the current speed is also in advantageously avoided a free path in the pedal.

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

drawing

The invention will be described below with reference to the drawing illustrated embodiments illustrated. FIG. 1 shows an overview image of a control device for Operating a drive motor, while in Figure 2 based a flowchart, a preferred embodiment of a torque structure in conjunction with the control of a drive motor is shown, provided they are facing the described procedure is of concern. Figure 3 shows a preferred embodiment for the formation of the motor minimum torque value.

Description of exemplary embodiments

FIG. 1 shows a block diagram of a control device for controlling a drive motor, in particular a Internal combustion engine. A control unit 10 is provided, which as components an input circuit 14, at least a computer unit 16 and an output circuit 18 has. A communication system 20 connects these components for mutual data exchange. The input circuit 14 of the control unit 10 are input lines 22 to 26th fed, which in a preferred embodiment are designed as a bus system and via the control unit 10 signals are supplied, which for controlling the drive motor represent operating variables to be evaluated. These signals are detected by measuring devices 28 to 32. Such operating variables are in the example one 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 shown in FIG. 1 on the basis of the output lines 34, 36 and 38 symbolizes over which the fuel mass to be injected, the ignition angle and at least an electrically operated throttle for adjustment the air supply are actuated. About the illustrated Stellpfade become the air supply to the engine, the ignition angle of the individual cylinders to be injected Fuel mass, the injection timing and / or the air / fuel ratio, etc. are set. In addition to the described input variables are further control systems of Provided to the input circuit 14 default variables, For example, torque setpoints transmit. Such control systems are for example traction control systems, Vehicle dynamics regulations, transmission controls, engine drag torque regulations, Cruise control, Speed limiter, etc. In addition to these external setpoint specifications, to which also a setpoint specification by the Driver in the form of a driving desire or a maximum speed limit are internal specifications provided for the drive motor, e.g. the output signal an idling control, a speed limitation, a Torque limitation, etc.

In moment coordination, the different torque default values, as driver request torque, target torque of a Stability regulator, nominal torque of a transmission control, as well if necessary, internal setpoint torques etc. coordinated with each other and a resulting target torque selected. Idle controller and loss moment are then switched on by on the coordination resulting target torque considered. Depending on the controller concept, the torque loss can be activated Idling controller in the nominal torque or modifying torque of the Idle controller may be included or will be active Idle speed controller added as own addition size.

As shown above, especially in the lower speed range, in the safe idle operation or avoidance of stalling is of great importance, the resulting Target torque down by a motor minimum torque, the a clutch torque is preferred at the motor output and in this speed range is zero, limited. So also with external interventions the same touchdown point for the idle controller and / or the connection of the loss moments, such as he in case of missing driver request (released pedal) occurs. This even if the external intervention Request torque, which is smaller than the loss torque and / or the idle correction is. This has the advantage that losses can be fully compensated and the Idle controller has priority over other interventions, so that effective stalling is avoided.

In the upper speed mode is push mode, that is it is a partial compensation of the losses and an injection suppression allowed. In this case, the required Idle controller no penetration or is inactive. In one preferred embodiment is the minimum engine torque the proportion of lost torque that does not compensate in the push must become. Less than the negative, total loss moment can not be the torque limit. If in this Range is required by the minimum torque Connection of the total loss torque achieved, the losses only partially or not compensated. To one To avoid free travel, the minimum torque preferably corresponds the moment when the driver request torque (wheel torque or Transmission output torque) with released pedal and possibly the current speed is calculated.

The flowchart shown in Figure 2 describes a Program of a microcomputer of the control unit 10, wherein the individual blocks programs, program parts or program steps while the connecting lines represent the signal flow represent. The first part can be up to the vertical, dotted line in a separate Control unit, there also in a microcomputer, expire as the part after this line.

First, signals are supplied which the vehicle speed VFZG and the accelerator pedal position PWG correspond. These variables are in a map 100 in a moment request implemented by the driver. This driver request moment, which is a default size for a moment on the output side represents the transmission or for a wheel torque is one Correction stage 102 is supplied. This correction is preferable an addition or subtraction. The driver's desire moment is determined by a weighted loss moment MKORR corrected, which formed in the link 104 has been. In this is fed, by means of translation Ü the drivetrain and possibly further translations in Drive train on the output side of the transmission to a moment after the transmission, preferably a wheel torque converted Loss torque MVER weighted by a factor F3. The weighting is preferably done as a multiplication. The factor F3 becomes the quantity representing the accelerator pedal position and in one embodiment, the engine speed representing size or is alone dependent from the accelerator pedal position.

In this way driver request MFA becomes the moment coordination to form a resulting default moment MSOLLRES supplied. In the example shown is in a first Maximum value selection stage 108, the maximum value from the driver's desired torque MFA and default torque MFGR of a cruise control selected. This maximum value becomes one subsequent minimum value stage 110, in which the smaller value from this value and the setpoint torque value MESP an electronic stability program is selected. The output of the minimum value stage 110 represents a magnitude of torque output side of the transmission or a Radmomentengröße by taking into account the gear ratio Ü and possibly further translations in the powertrain on the output side of the gearbox converted into a torque quantity which is input side or output side the drive motor is present. This moment size is in one another coordinator 112 with the target torque MGETR a Transmission control coordinated. The nominal torque of the transmission control is formed according to the needs of the switching operation. In the subsequent maximum value selection stage 114 Then the resulting target torque MSOLLRES than the larger the torque values motor minimum torque MMIN and the output torque the coordination stage 112 formed.

This torque coordination is exemplary. In other versions is the one or the other default moment not to Coordination used or are other default moments provided, for example a moment of maximum speed limit, an engine speed limit, a Torque limitation, etc.

The resulting in the manner described above resulting Target torque MSOLLRES is fed to a correction stage 116, in which the target torque with the applied by the engine, non-drive loss torques is corrected. The loss moments MVER are thereby possibly in a weighting stage 118 weighted by a factor F2. This is constant or operating variable dependent, e.g. engine speed-dependent. The loss moments MVER itself will be in the addition stage 120 from the torque requirement MNA of ancillaries and the engine lost torque MVERL. The Determination of these quantities is known from the prior art, where the torque requirement depends on the operating status of the relevant ancillary equipment in accordance with characteristic curves or Similarly, the engine torque loss depending on engine speed and engine temperature determined according to characteristic curves becomes. The loss moment formed in this way MVER is then provided to the correction stage 104, where a conversion of the loss torque with the help the known gear ratio Ü and possibly other translations in the drive train on the output side of the transmission the plane of the transmission output or wheel torques takes place.

The output of the correction stage 116, which in the preferred Embodiment is an addition, is a default size for the torque to be generated by the drive unit for the drive (indicated engine torque), for overcoming the internal losses and the operation of ancillary equipment (eg air conditioning compressor). This default moment is in a further correction stage 122 with that in a correction stage 124 weighted output DMLLR of the idle controller corrected (preferably added). The weighting factor F1, with 124 in the output of the idle controller is weighted, it is speed and / or time dependent, wherein when leaving the idle range of Factor in time or with increasing engine speed to zero decreases. The default size MISOLL then becomes 126 in FIG the prior art known in manipulated variables for adjustment the performance parameter of the drive unit implemented in Trap of an Otto engine in air supply, fuel injection and ignition angle, in the case of a diesel engine in fuel quantity, etc.

The procedure described above has been mentioned above shown with the application in internal combustion engines. In analogously, it is also used in electric motors, where the indicated moment there is the applied by the drive motor Moment for the drive, the operation of ancillaries and overcoming the internal friction is.

In the maximum value selection stage 114, the larger one is supplied Values, namely the desired torque value, which in 112 is formed and the motor minimum torque MMIN, as a result Target torque selected. An intervention, a moment specifies which is smaller than the motor minimum torque has thus no effect or its effect is limited the motor minimum torque. In the idle control area in which a Connection of the driver deceleration request to the driver's request not taking place in 102, is the motor minimum torque preferably zero, so that on this, according to the driver's request Moment value in 116 and 122 loss moments and Idle control torques are switched on unhindered. in the Thrust, on the other hand, is the loss moment, which in 116 on the resulting target torque is switched on, by switching in 102 on the driver's request depending on the operating condition partially or completely compensated. In this case, the motor minimum torque the negative loss torque value given so that in the following in 116 the positive loss moment value is switched on. It is thus a target torque set, which due to the idle controller portion Stalling avoids or providing the full Drag torque (e.g., by injection blanking) allowed.

The determination of the motor minimum torque preferably takes place in 128 depending on engine speed NMOT and torque loss MVER instead. There are different alternatives.

A preferred alternative is shown in FIG. There First, a characteristic 130 is shown in which a between 0 and -1 moving factor F4 depending the engine speed is shown. Up to idling speed NLL is the factor 0. From the reset speed or the Injection suppression speed in thrust NWE is the factor-1. Between these two values a characteristic is given, in the embodiment shown, a linear characteristic, where the factor F4 changes from 0 to -1. Of the formed in this way depending on the engine speed NMOT Factor F4 is then in a node 132 with the loss moment MVER, which is formed in 120, preferably multiplied. The result is the motor minimum torque NMIN, which takes into account the moment coordination becomes. Thus, at low speeds below the idling speed of the factor F4 zero, so that as Minimal moment the moment zero is given. In the push area is the factor -1, so that as a minimum moment the full negative loss moment is given. In between is that Minimal moment a fraction of the loss moment, so that at the specification of such a minimum torque by the following Connection of the loss torque with specification of the minimum torque as a resulting moment a partial compensation the negative loss moment takes place.

An alternative to the procedure shown in FIG is that the variable idle speed and thrust suppression speed in the determination of the factor is taken into account. In this case, no characteristic curve is but a calculation of the factor made in which the current idle speed and the currently selected thrust skip speed is used.

Another alternative is the use of the for the driver's request, speed-dependent lower Limit, which as a correction torque in 102 the driver's request is switched on. This is in the preferred embodiment speed and pedal position dependent and represented the moment value that occurs when the pedal is released should result. If this torque value as motor minimum value used, free paths are avoided on the pedal, as the resulting moment not smaller than the correction torque can be.

Furthermore, in one embodiment, the determination of the factor F4 not the engine speed but one, e.g. used to the idling target speed, normalized size. This is advantageous when using an operating state-dependent (normalized) speed threshold for the stalling protection or the idle control, whose activation falls below this speed threshold by the (normalized) engine speed he follows.

FIG. 2 shows the consideration of the minimum engine torque in the moment coordination at the end of the coordination as maximum value selection stage shown. In another advantageous Embodiment is alternatively before each Coordination block (108, 110, 112) the respective target torque individually with the minimum torque in the context of a maximum value selection coordinated so that already for coordination and limited to the formation of the resulting target torque moments available.

In other embodiments, the minimum torque MMIN specified as an absolute value independent of the loss moment. In this case, the minimum limit is in the operating state "Thrust" (inner moment zero) not effective.

Claims (10)

1. Method for operating a drive engine of a vehicle, a predefined value for a torque of the drive engine being determined as a function of the driver's requirements and further predefined values, the predefined value for the driver's requirement and the further predefined values being logically linked to one another to form the resulting predefined value, characterized in that the predefined value for the driver's requirement is formed at the gear box output end or at the wheel torque level, in that a minimum engine torque is predefined at the gear box input end or at the output end of the drive engine, which minimum engine torque limits the resulting predefined value to a lower limiting value.
2. Method according to Claim 1, characterized in that the resulting predefined value is logically linked to the minimum engine torque within the scope of a selection of a maximum value, or in that each predefined value is individually logically linked to the minimum engine torque before being logically linked to another predefined value within the scope of a selection of a maximum value.
3. Method according to one of the preceding claims, characterized in that the minimum engine torque is predefined as a function of the rotational speed.
4. Method according to one of the preceding claims, characterized in that the minimum engine torque is dependent on the engine lost torque, which represents the torque of the drive engine which is required to overcome the engine losses and/or to operate secondary assemblies.
5. Method according to one of the preceding claims, characterized in that in a first rotational speed range the minimum engine torque is zero, in a second rotational speed range the minimum engine value constitutes the negative value of the engine losses, and the minimum engine torque is changed between these rotational speed ranges as a function of the rotational speed.
6. Method according to one of the preceding claims, characterized in that the first rotational speed range is the range below the idling speed, and the second rotational speed range is the rotational speed range above a thrust cut-off rotational speed.
7. Method according to one of the preceding claims, characterized in that the minimum engine torque constitutes the torque which is predefined as the driver's required torque when the accelerator pedal is released.
8. Device for operating a drive engine of a vehicle, having an electronic control unit which predefines a resulting predefined value for a torque of the drive engine as a function of the driver's requirement and further predefined values, the value for the driver's requirement and the further predefined values being logically linked to form the resulting predefined value, characterized in that the electronic control unit has means which form the predefined value for the driver's requirement at the gear box output end or at the wheel torque level, in that the electronic control unit has means which predefine a minimum engine torque at the gear box input end or at the output end of the drive engine, which minimum engine torque limits the resulting predefined value to a lower limit.
9. Computer program having program code means for carrying out all the steps of any of Claims 1 to 7 if the program is executed on a computer.
10. Computer program product having program code means which are stored on a computer-readable data carrier in order to carry out the method according to any of Claims 1 to 7 if the program product is executed on a computer.

Images