DE102009048815A1 - Method for controlling drive system in motor vehicle, involves recording accelerator pedal position in form of accelerator pedal value, where ground characteristic is determined from driver desired target torque - Google Patents

Abstract

The method involves recording accelerator pedal position in the form of an accelerator pedal value. A ground characteristic is determined from the driver desired target torque. A defined accelerator pedal position is less than the maximum accelerator pedal position, where the accelerator pedal positions assign a mode of maximum attainable torque.

Description

The invention relates to a method for controlling a drive system in a motor vehicle according to the preamble of patent claim 1.

Such a method is for example from the EP 1 802 483 B1 known. This is a power reduction in the event of a wheel slip by a modified accelerator characteristic in the foreground.

It is an object of the invention to develop the possibilities of a drive control depending on changed accelerator characteristics.

This object is achieved by the subject of claim 1. The dependent claims are advantageous developments of the invention.

The invention is based on the following finding:
By a performance-reducing accelerator characteristic, for example, a better metering of the relatively low drive power in the purely electrical operation of so-called fully hybrid vehicles in the operating mode "electric driving", in which only a small (er) part of the total driving power is available, can be achieved. Under characteristic curve or accelerator characteristic here is the specification of a target torque (power, engine torque or Radmomentvorgabe) in function of the predetermined by the driver performance (gas pedal value) understood.

In particular, in a transition from the electric drive mode (first mode) to a mode using an internal combustion engine drive (eg, internal combustion engine or hydrogen engine) (second mode), a change of the conventional accelerator characteristic (s) (basic characteristics) makes sense. In this case, a sudden change in the setpoint torque in response to the switching of the operating modes is to be avoided.

Therefore, according to the invention, in a first operating mode "electrically driving", the maximum torque attainable in this operating mode (eg wheel torque or driving power) is assigned a specific defined accelerator pedal value from the accelerator pedal position for which the gradient of the accelerator pedal position is explicitly set by the accelerator pedal changed accelerator characteristic above the accelerator pedal value for the electrical operation gives (special characteristic).

The switchover from the second operating mode to the first operating mode preferably takes place below this maximum torque which can be achieved in the first operating mode, so that no discontinuity in the power demand is to be expected during the state transition into "electric driving".

When switching from the second mode to the first mode, the accelerator characteristic for the case of request increase (increase of the accelerator pedal value) from the current target torque as linearly as possible to the maximum corner point for electric driving, d. H. to the maximum nominal torque of the special characteristic, extrapolated. The resulting interpolated straight line is referred to here as an intermediate characteristic.

In the case of the gas or accelerator pedal return (reducing the accelerator pedal value) is either the basic characteristic or if the intermediate characteristic has already been interpolated from the respective last valid torque linear or after any other function to the desired torque for a pedal pedal not pressed (accelerator pedal zero position ) is extrapolated from the basic characteristic curve or the intermediate characteristic curve. This means that the special characteristic curve for purely electrical operation can only be achieved via its corner points.

The basic characteristic can under certain conditions exceptionally, especially in manual driver interventions, also be controlled directly, z. B. when changing the terminal (ignition off / on) or when changing the driving program by the driver (via gear selector switch). Optionally, a time behavior could also be underlined, which activates the respective predetermined value of the basic characteristic curve with an adjustable dynamic, for example, with changing accelerator pedal specification. The basic characteristic can also be selected from a parameter-dependent basic characteristic family and can thus be variable.

In the event that the internal combustion engine drive switches on, while the request remains in the adjustment range of the wheel torque for electrical operation, ie the accelerator pedal position is substantially constant, the system is treated as if electric operation were still required.

In the drawing, an embodiment of the invention is shown. It schematically shows the different accelerator pedal characteristics resulting from the invention.

The drawing shows on the abscissa the accelerator pedal position in the form of an accelerator pedal value FP and on the ordinate the desired torque M _soll , which respectively results from the accelerator pedal value FP. The desired torque M _soll may preferably be the target wheel torque which is proportional to the desired power output of the driver.

Shown is in particular a basic characteristic DC (solid line) selected from a dependent on the vehicle speed Grundkennlinienschar (dash-dotted lines from D to C). The characteristic curve DB represents the special characteristic curve. The characteristic curve AB (bold-dotted) represents an intermediate characteristic which is formed by interpolation of an instantaneous setpoint torque to the upper vertex B of the special characteristic curve in a transition from the second to the first mode of operation. Examples of return characteristics are the interpolated lines ED and FD (bold dots). The characteristic curve BC is provided for the second operating mode out of the first operating mode. The thin dashed curves starting from D to the characteristic BC show transition characteristics for the second mode of operation from the first mode.

The inventive method accelerator described the functional method as follows: An electronic control unit not shown here detects, inter alia, as the input signal the accelerator pedal value FP and determines it according to the basic characteristic DC desired by the driver target torque M _soll . In particular, in a hybrid motor vehicle with electric and internal combustion engine drive is in a first mode in which is driven exclusively with electric drive, instead of the basic characteristic DC, the power limiting continuously increasing special characteristic DB between the accelerator pedal zero position FP _0% and the defined accelerator pedal position FP _B , which is smaller than the maximum possible accelerator pedal value FP _100% , given. This defined accelerator pedal position FP _B is the maximum achievable with the first mode target torque M _{soll_max_el} assigned.

A transition from a second operating mode, in which also or exclusively with internal combustion engine drive is driven, into the first operating mode is permitted only below the maximum torque attainable in the first operating mode M _{soll_max_el} . In this case, starting from the current setpoint torque M _soll of the basic characteristic curve to point B DC preferably linear interpolated (z. B. dotted line AB). The resulting interpolated straight line is called the intermediate characteristic here. Each further increase in the accelerator pedal value FP predetermines a setpoint torque M _{soll in} accordance with this interpolation or intermediate characteristic curve.

In the case of at least partial retraction of the accelerator pedal position or reduction of the accelerator pedal value FP, starting from a current desired torque M _soll on the interpolated straight line AB (eg points E or F) - preferably linear or according to any other characteristic - interpolated to point D (dotted lines ED or FD). The resulting interpolated straight lines are called return curves here.

In the case of a change from the first operating mode to the second operating mode to the basic characteristic curve D-C, basically only the minimum vertex D or the maximum vertex C thereof is transited. For the basic characteristic DC is not exceptionally passed over their vertices C or D, if due to a change in the operating parameter-dependent basic characteristic DC (shown here in broken lines) another intersection G of the basic characteristic DC with a return characteristic ED or FD, an intermediate characteristic AB (as shown in FIG Case) or the special characteristic DB already earlier. In this case, the transition to the basic characteristic curve D-C takes place at the intersection point G.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1802483 B1 [0002]

Claims (6)

Method for controlling a drive system in a motor vehicle with at least one electronic control unit that detects the accelerator pedal position in the form of an accelerator pedal value (FP) and determines therefrom a desired torque (M _soll ) desired by the driver according to a basic characteristic curve (DC), characterized in that in a motor vehicle with electric and internal combustion engine drive in a first operating mode, in which exclusively driven by electric drive, instead of the basic characteristic (DC) a power-limiting continuously increasing special characteristic (DB) between the accelerator pedal zero position (FP _0% ) and a Defined accelerator pedal position (FP _B ), which is smaller than the maximum possible accelerator pedal position (FP _100% ), is given, and that this defined accelerator pedal position (FP _B ) is the maximum achievable with the first mode target torque (M _{soll_max_el} ) is assigned. Method according to Patent Claim 1, characterized in that a transition from a second operating mode, in which also or exclusively with internal combustion engine drive is driven, into the first operating mode is permitted only below the maximum torque attainable with the first operating mode (M _{soll_max_el} ). A method according to claim 2, characterized in that in a transition from the second mode to the first mode in the case of a subsequent increase in the accelerator pedal value (FP) starting from the basic characteristic (DC) a - preferably linear - intermediate characteristic (AB) is given by Interpolation of the current setpoint torque from the basic characteristic (DC) to the maximum vertex (B) of the special characteristic (DB) is formed. Method according to claim 3, characterized in that in the case of the subsequent at least partial withdrawal of the accelerator pedal value (FP) starting from a current desired torque on the intermediate characteristic (AB) a - preferably linear - return characteristic (ED, FD) by interpolation to the lower corner (D) of the special characteristic (DB) is specified. Method according to one of the preceding claims, characterized in that in case of a change from the first mode to the second mode to the basic characteristic (D-C) basically only over the minimum vertex (D) or over the maximum vertex (C) is passed. Method according to the preceding claim, characterized in that the basic characteristic (DC) exceptionally not on the minimum vertex (D) or over the maximum vertex (C) is passed, if due to a change in the operating parameter-dependent basic characteristic (DC) another intersection (G) the basic characteristic (DC) with a return characteristic (ED, FD), an intermediate characteristic (AB) or the special characteristic (DB) results earlier.

Images