EP0937886B1 - Method for controlling the power of a vehicle - Google Patents

Description

The invention relates to a method for adjusting the drive power of a motor vehicle with a spark-ignited internal combustion engine according to the preamble of patent claim 1.

A generic method for adjusting the drive power of a motor vehicle is known from DE 44 07 475 A1. In this case, the firing angle and the air / fuel ratio are influenced on the basis of a desired value for the torque to be output by the drive unit in addition to the load.

It is the object of the invention to improve a method for adjusting the drive power of a motor vehicle with a spark-ignited internal combustion engine such that a centrally predetermined desired torque can be adjusted easily and reliably with different dynamic requirements.

This object is achieved by a device having the features of patent claim 1

By the method according to the invention, the coordination of the various requirements for the vehicle drive is decoupled from the functions for adjusting the internal combustion engine in the engine control. The torque interface is only a target torque and information about the dynamics with which this torque request is to be set, to the control of the internal combustion engine. Here it is It is completely irrelevant how many subsystems are involved in the momentum slice and how the actual coordination is accomplished. By setting up three operating states in which the requirements are fulfilled with different dynamics and with different objectives, the different requirements of all subsystems can nevertheless be taken into account.

The establishment of a transitional operating state with an associated threshold for a Zündwinkelkorrekturfaktor can be a sudden withdrawal of a large Zündwinkelverstellung and thus a noticeable torque change, which could be caused by a jump directly from an operating condition with Zündwinkelverstellung in an operating condition without Zündwinkelverstellung.

Fig. 1

einen Strukturplan eines Ausführungsbeispiels des erfindungsgemäßen Verfahrens und

Fig. 2

eine Prinzipdarstellung der möglichen Übergänge zwischen den einzelnen Betriebszuständen zeigt.

Further advantages and embodiments of the invention will become apparent from the dependent claims and the description. The invention is described below with reference to a drawing, wherein

Fig. 1

a structural plan of an embodiment of the method according to the invention and

Fig. 2

shows a schematic diagram of the possible transitions between the individual operating states.

The starting point for the method described in the drawing is a desired setpoint torque M_setpoint and information about how the desired setpoint torque M_setpoint is set. For this purpose, in block 1, a driver desired torque determined from a driver specification and optionally further desired torque M_i is processed to a resulting target torque M_soll. This is preferably a so-called torque interface, in which the driver's desired torque with other desired moments M_i, which are passed, for example, from the transmission control, from a vehicle dynamics control or other subsystems of the drive control to a resulting target torque M_soll is processed. Such a torque interface is known in principle from the prior art and is therefore not explained here in detail.

In addition, information about the dynamics with which the torque adjustment should take place is provided by the torque interface in block 1 in the form of two so-called dynamic bits MDYN0, MDYN1. In gasoline engines, torque requests can be realized in a known manner via the air path and / or via an ignition intervention. The respectively desired type of torque adjustment is defined by operating states Z1 to Z3 via the two dynamic bits MDYN0, MDYN1: torque adjustment MDYN1 MDYN0 Status Efficiency optimal torque adjustment via the air path 0 0 Z1 Fastest possible torque adjustment via ignition angle adjustment and air path 0 1 Z2 Torque setpoint for the air path is frozen, torque reduction takes place via ignition angle adjustment 1 0 Z3 Invalid combination 1 1 -

If, for example, the setpoint torque M_setpoint is to be achieved by an optimum torque setting efficiency, that is to say the operating state Z1 is present, the following dynamic bits are transferred from block 1 to block 2: $$\mathrm{mdyn}0\mathrm{}:=0\mathrm{mdyn}1\mathrm{}:=0$$

If the desired moments M_i of several subsystems are coordinated in the torque interface 1, then the different dynamic requirements of the subsystems must also be coordinated there. In normal operation of an adaptive cruise control, an optimum torque adjustment efficiency is also predetermined. In certain operating conditions, however, can for The adaptive cruise control can be switched to a fastest possible setpoint torque setting. In the driving dynamics control systems, a fastest possible setpoint torque setting is specified during normal operation. In certain operating conditions, however, can be switched to a torque setting with Vorhalt. The transmission control also usually wishes a fastest possible torque setting. Of course, the above specifications only show examples. The processing of the individual torque specifications M_i and the associated dynamic requirements to a desired torque M_soll and a dynamic request MDYN0, MDYN1 is not the subject of this patent application and is therefore not further explained. Subject of this application is a method by which you can effectively set a predetermined target torque M_soll at different dynamic requirements.

In block 2, the setpoint torque M_setpoint is then divided into a filling moment M_filling and a resulting moment M_zünd depending on the current operating state Z1 to Z3. The filling moment M_Füll is set via the load control, while the resulting torque M_Zünd is contributed by a Zündwinkelverstellung. In addition, in block 2, another control bit MDYN_MK, the function of which is explained in more detail below, is provided according to the following table: operating condition M filling M ignition MDYN MK Z1 : = M shall M shall 0 Z2 : = M shall M shall 1 Z3 : = Max (M fill (k-1), M soll) M shall 1 Z4 : = M shall M shall 1

When operating state Z4 is a transitional state, which will be explained below with reference to FIG. 2. In operating state Z3, the filling moment M_Füll is fixed. This means that when entering the operating state Z3 is the Filling moment M_Füll set to the momentary setpoint torque M_soll. Subsequently, for each determination, the current setpoint torque M_setpoint is compared with the filling momentum M_filling (k-1) of the last pass, and the larger of the two values is stored and passed on as the actual filling moment M_fill. This means that in the operating state Z3, the filling torque M_Füll not decrease, but can only increase.

In block 3, a residual torque M_Rest is determined, which is composed of the friction torque and the torque required for the drive of auxiliary units. The friction torque can be determined from the current engine speed, the oil temperature and possibly other operating parameters. This residual moment M_Rest is added in blocks 4 and 5 to determine the indicated filling moment M_Füll_Ind and the indicated resultant moment M_Zünd_Ind to the effective filling moment M_Füll or to the effective resulting moment M_Zünd.

Furthermore, an idling torque M_Leer is determined in block 6 for idle control and compared in block 7 with the indexed filling torque M_Füll-Ind, wherein in each case the larger of the two values is passed as indicated torque M_Ind to the load control. The load control is known ansich and therefore will be explained here only briefly. In the load control, a load reference value TL_setpoint is determined from the indicated torque M_Ind on the basis of the current engine speed and possibly further operating parameters. At the same time, the actual load value TL_act is determined, for example with the aid of an air mass meter, continuously compared with the load setpoint TL_soll and a difference value is calculated. This difference value is then regulated by a control of the throttle as possible to zero.

In block 8, a first ignition angle correction factor η _{dyn is} determined from the quotient of indexed resulting moment M_initial_ind and indicated filling moment M_fill_ind, and in block 9 multiplied by a second ignition angle correction factor η _MK for calculating the resulting ignition angle correction factor η. From the resulting ignition angle correction factor η, a retard angle for the ignition angle calculation can then be determined with the aid of a characteristic diagram.

The calculation of the second ignition angle correction factor η _MK takes place starting from block 10. There, a correction factor η _{TL is} calculated from the quotient of the load setpoint TL_setpoint and the actual load value TL_ist and limited to the maximum value 1 in block 11 by a MIN comparison. This limited correction factor η _TL is passed both to block 2 and to block 12. In block 12, the second ignition angle correction factor η _MK is subsequently determined as a function of the control bit MDYN_MK, which is transferred from block 2 to block 12, and the limited correction factor η _TL . Namely, the second firing angle correction factor η _MK = 1, if the control bit MDYN_MK = O, or η _MK = η _TL , if the control bit MDYN_MK = 1. As already described above, the second ignition angle correction factor η _MK is then multiplied in block 9 by the first ignition angle correction factor η _dyn for calculating the resulting ignition angle correction factor η.

As can be seen from the first table, in the first operating state Z1 the filling moment M_Full = M_setpoint and also the resulting moment M_start = M_setpoint are set. Thus, in the quotient formation in block 8, a first ignition angle correction _factor η _dyn = 1 results. In addition, since the control bit MDYN_MK = 0, the second firing angle correction factor η _{MK is} also set to the value 1 in block 12. This results in a resulting ignition angle correction factor η = 1, that is, the ignition angle is not corrected. Thus, the entire torque setting efficiency is optimally made on the filling torque M_Füll = M_soll, that is on the load control.

In the second operating state, as in the first operating state Z1 also, the filling moment M_Füll = M_soll and the resulting moment M_zünd = M_soll set. This results in the quotient formation in block 8, in turn, a first ignition angle correction _factor η _dyn = 1. In contrast to the operating state Z1, however, the control bit MDYN_MK = 1. Thus, in block 12, the limited correction factor η _{TL is passed} from block 11 as second ignition angle correction factor η _MK to block 9. The calculation of the correction factor η _TL takes place, as already described above, in block 10 by quotient formation from the load setpoint TL_soll and the actual load value TL_ist. If in this case the load setpoint is greater than the actual load value TL_set> TL_act, the result is a correction factor η _TL 1>. This is then limited in block 11 to the value η _TL = 1. This takes into account the fact that the actual load value can be reduced, but not increased, by an ignition retard adjustment. If, in contrast, the load setpoint is smaller than the actual load value TL_set <TL_ist in block 10, a correction factor η _TL <1 results. This is then used as the second ignition angle correction factor η _MK at block 9 and after the multiplication by the first ignition angle correction factor η _dyn = 1 as the resulting ignition angle correction factor η to the ignition angle calculation. In this case, a fastest possible torque reduction is therefore triggered in addition to the load control via a Zündspätverstellung.

In the third operating state Z3, a torque adjustment is performed with Vorhalt. This means that when the setpoint torque M_setpoint is reduced, the filling momentum M_fill is retained at the original value M_fill (k-1). The torque reduction takes place in this case exclusively via the ignition timing. With an increase of the setpoint torque M_soll, however, the filling moment M_Füll is correspondingly increased and thus the load control is carried out accordingly. The determination of the second Zündwinkelkorrekturf actuator η _MK is analogous to the method according to operating condition Z2. In addition, however, in block 8, the resulting moment M_Zünd can differ from the filling moment M_Füll, so that one of 1 different first Zündwinkelkorrekturfaktors η _dyn results. Since the resulting torque M_Zünd = M_soll is set and the filling torque can only assume values M_Füll> = M_soll, this results in a first ignition angle correction factor of η _dyn <= 1. In this operating state Z3, both ignition angle correction _factors η _dyn , η _MK can thus contribute to the ignition angle adjustment.

Finally, it will now be explained briefly with reference to FIG. 2 how the transition between the individual operating states Z1 to Z4 takes place. In addition to the operating states Z1 to Z3 already described above, an additional transitional operating state Z4 is provided here, the function of which will be described below. The method for determining the indicated torque M_Ind and the resulting ignition angle correction factor η in this case corresponds completely to the method in the operating state Z2.

When starting, the operating state Z1 is selected as part of an initialization. Depending on the dynamic demand MDYN0, MDYN1 respectively currently determined in block 1, a new operating state Zi is then selected. The possible transitions between the operating states Zi are each shown as arrows with associated conditions. As can be seen from FIG. 2, starting from the operating state Z1, only a transition to the operating states Z2 or Z3 is possible. A direct transition from the operating state Z1 to the transitional operating state Z4 is not provided. Accordingly, although any changes between the operating conditions Z2, Z3 and Z4 are possible, a direct change from the operating conditions Z2 or Z3 to the operating state Z1 is again not provided. Back to the operating state Z1 can only be reached via the transitional operating state Z4, if in addition the limited correction factor η _{TL is} greater than a predetermined threshold value s. By this condition, a sudden retraction of a large ignition angle and thus a noticeable change in torque, as could occur by a direct jump from the operating state Z2 or Z3 in Z1, prevented.

Claims (5)

1. Method of adjusting the driving power of a motor vehicle having an internal combustion engine with spark ignition, comprising means for pre-setting a desired torque on the basis of a driver's desired torque and optionally other desired torques and means for adjusting this desired torque by influencing the load and/or the ignition angle, whereby a distinction is made between three states (Z1, Z2, Z3) associated with the operating conditions,
   characterised in that

   - the torque adjustment is implemented at optimum efficiency on the basis of a load regulation in a first operating state (Z1),

   - the torque adjustment is implemented as quickly as possible on the basis of an additional ignition angle adjustment in a second operating state (Z2) and

   - the torque setting is fixed for the load control and the residual torque adjustment is effected on the basis of an additional ignition angle adjustment in a third operating state (Z3),

   - the desired torque (M_desired) is divided into a charging torque (M_charge) and a resultant torque (M_ign) depending on the instantaneous state (Z1, Z2, Z3),

   - a load desired value (TL_desired) is determined from the charging torque (M_charge).
2. Method as claimed in claim 1,
   characterised in that

   - the load actual value (TL_actual) is set to this load desired value (TL_desired) with the aid of a load control system,

   - a first ignition angle correction factor (η_dyn) is determined from the quotient of the resultant torque (M_ign) and the charging torque (M_charge),

   - a second ignition angle correction factor (η_MK) is determined from the quotient of the load desired value (TL_desired) and the load actual value (TL_desired)

   - the second ignition angle correction factor (η_MK) is set at 1 in the first state (Z1) and

   - a resultant ignition angle correction factor (η) is determined from the product of the first and second ignition angle correction factors (η_dyn*η_MK,) from which a delay adjustment angle is determined for the ignition angle calculation.
3. Method as claimed in claim 2,
   characterised in that
   the second ignition angle correction factor (η_MK) is limited to values smaller than or equal to 1.
4. Method as claimed in claim 1 or 2,
   characterised in that
   the charging torque (M_charge) is limited to values greater than or equal to an idling torque (M_LLR).
5. Method as claimed in claim 2,
   characterised in that
   a transition from the second state (Z2) respectively the third state (Z3) to the first state (Z1) does not take place unless the second ignition angle correction factor (η_MK) exceeds a pre-set threshold value (s).

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