Method for accelerating a motor vehicle

Abstract

Method for accelerating a motor vehicle, wherein a driver's desired torque (5) is determined with the aid of a control and regulation system (2) of the motor vehicle as a function of a driver input from a driver operating the motor vehicle, a vehicle mass (4) of the motor vehicle and further components (3) of a drive train of the motor vehicle, characterized in that, in order to accelerate the motor vehicle, a desired torque (6) of a drive unit of the drive train is determined as a function of the driver's desired torque (5), wherein the desired torque (6) includes an acceleration of the drive unit itself, and wherein a speed gradient (7) is determined for determining the desired torque (6), wherein the speed gradient (7) is used to determine an additional torque (9) of the desired torque (6), and wherein the desired torque (6) is determined as the sum of the additional torque (9) and the driver's desired torque (5).

Description

[0001] The invention relates to a method for accelerating a motor vehicle according to the preamble of patent claim 1.

[0002] According to the current state of the art, a torque to be set for a motor vehicle's drive unit is determined based on a driver input from the driver operating the motor vehicle. The driver input is typically provided in the form of the vehicle's accelerator pedal position. However, it can also be generated electronically or in another way, e.g., with a throttle lever mounted on a steering wheel.

[0003] A method for monitoring an increase in speed is known from published patent application DE 10 2011 078 748 A1. A total drive torque consisting of a driver's desired torque and additional torques from the drive unit's auxiliary units is determined. Based on this total drive torque, a so-called driver's desired acceleration is determined in an engine map of a control and regulating device of the motor vehicle, depending on the accelerator pedal position, the currently engaged gear, and the vehicle mass. This acceleration is compared with an acceleration determined from a currently measured speed.

[0004] German Patent Application DE 10 2006 029 044 A1 discloses a method for accelerating a motor vehicle. A control and regulation system of the motor vehicle determines a requested starting torque based on a driver input from the driver operating the motor vehicle and other components of a drive train of the motor vehicle, such as the clutch, gear selector, and brake. A target torque of a drive unit of the drive train is determined for accelerating the motor vehicle based on the requested starting torque. The target torque includes an acceleration of the drive unit itself.

[0005] From the published patent application DE 196 44 881 A1 a method for controlling an output torque of a drive train of a motor vehicle is known, wherein it is proposed to determine a target value for the output torque, which is provided by the setting of a transmission and by controlling an internal combustion engine, on the basis of a driver request signal and a minimum and / or maximum output torque dependent on operating variables.

[0006] The published patent application DE 10 2004 031 030 A1 discloses a method for a motor vehicle, wherein in the event of increased driving resistance, such as a vehicle load or a steep road gradient, an engine speed of an internal combustion engine is to be increased significantly depending on a clutch travel.

[0007] From the subsequent publication DE 10 2014 222 401 A1, a method for determining a target torque for controlling a drive of a motor vehicle is known, wherein a first target torque is determined or received. A dynamic torque loss is determined based on a change in speed or a variable related to the dynamic torque loss as a function of the first target torque. A second target torque, increased by the dynamic torque loss compared to the first target torque, is determined as a function of the first target torque and the dynamic torque loss or the variable characteristic of the torque loss. In the event of a torque gain upon a reduction in speed, the target torque can be reduced by the dynamic torque gain to compensate for this.

[0008] It is the object of the present invention to provide an improved method for accelerating a motor vehicle.

[0009] The object is achieved according to the invention by a method for accelerating a motor vehicle having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the respective subclaims.

[0010] The method according to the invention for accelerating a motor vehicle determines, with the aid of a control and regulation system of the motor vehicle, a driver's desired torque as a function of a driver input from a driver operating the motor vehicle, a vehicle mass of the motor vehicle, and other components of a drive train of the motor vehicle. According to the invention, in order to accelerate the motor vehicle, a target torque of a drive unit of the drive train is determined as a function of the driver's desired torque, wherein the target torque includes an acceleration of the drive unit itself, and wherein a speed gradient is determined to determine the target torque, wherein the speed gradient is used to determine an additional torque of the target torque, and wherein the target torque is determined as the sum of the additional torque and the driver's desired torque.

[0011] The advantage is that the acceleration of the drive unit itself is taken into account when determining the operating parameters of the drive unit that depend on the target torque. When a vehicle is accelerating, the speed of the drive unit must also accelerate. In other words, this means that the torque generated, for example, by combustion in a drive unit designed as an internal combustion engine or by electrical interactions in a drive unit designed as an electric motor must also serve to increase the speed of the drive unit itself, in particular of the components it moves. If the determined target torque also includes the acceleration of the drive unit itself, the corresponding operating parameters, e.g.In the case of a drive unit designed as an internal combustion engine, a fuel quantity, an ignition timing and necessary other operating parameters are determined in such a way that the drive unit can compensate for its own acceleration, so that ultimately the motor vehicle has the acceleration actually desired by the driver.

[0012] When determining the target torque, a speed gradient of the drive unit is used. The advantage is that the acceleration of the drive unit is directly taken into account when determining the target torque. The speed of the drive unit must also be accelerated in the vehicle being accelerated. In other words, this means that the torque generated, for example, by combustion in a drive unit designed as an internal combustion engine or by electrical interactions in a drive unit designed as an electric motor, must be large enough to be used to increase the speed of the drive unit itself. This is achieved when determining the target torque using the speed gradient.

[0013] The speed gradient is used to determine the additional torque. This offers the advantage that different influencing factors of the target torque can be considered separately. The torques determined from the individual influencing factors, depending on the speed gradient, can be summed to form a single torque, the additional torque.

[0014] This means that with the method according to the invention, a continuous tractive force or acceleration of the motor vehicle is achieved with a constant driver input, in other words, in particular, a constant accelerator pedal position. This specifically includes maintaining the tractive force during starting and during gearshifts of a transmission in the drivetrain.

[0015] If the speed gradient is used to determine a target torque, the speed gradient must be used as a theoretical speed gradient to avoid an unstable feedback loop. The theoretical speed gradient is a theoretically determined, and thus calculated, speed gradient. Since the current vehicle acceleration and thus a measured speed gradient are directly dependent on the current torque of the drive unit, determining the additional torque using the measured speed gradient could result in a potentially unstable feedback loop.

[0016] Advantageously, the speed gradient is determined as a function of the driver's desired torque, so that this is taken into account as a reference value.

[0017] When calculating the target torque, it is necessary to consider feedback-free influencing variables. In other words, this means that vehicle-specific constants, such as the vehicle mass or the driving resistance of the vehicle, or operating location-specific constants, such as the road gradient, must be used. These are non-influenceable variables when determining the target torque. If, for example, the target torque were determined based on measured variables that are dependent on the acceleration itself, such as a so-called actual speed gradient, this would lead to unstable feedback in the system with a tendency to oscillate, which would adversely affect the determination of the target torque. In other words, continuous tractive force or acceleration of the vehicle could not be ensured.

[0018] In one embodiment, the additional torque of the target torque is determined as a function of the feedback-free influencing variables. This additional torque thus takes into account the requirement of being determined from feedback-free influencing variables, so that a stable feedback loop is formed when calculating the target torque.

[0019] Preferably, the feedback-free influencing variables are a drive ratio and / or a driving resistance and / or a vehicle mass and / or a road gradient. This allows both vehicle-specific variables and operating location-specific variables to be taken into account when determining the required target torque.

[0020] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and feature combinations mentioned above in the description, as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. The single figure shows a schematic representation of a method according to the invention for accelerating a motor vehicle.

[0021] The method 1 according to the invention serves a motor vehicle (not shown in detail), which has a drive train (not shown in detail) with a drive unit (not shown in detail). In the present exemplary embodiment, the drive unit is an internal combustion engine, but it could also be an electric motor or a hybrid engine composed of these drive units, or the like. The drive train has a control and regulation system 2, with the aid of which it is operated. In the present exemplary embodiment, the drive train comprises, in addition to the drive unit, further components, in particular a clutch and a transmission. The method 1 according to the invention is implemented in the control and regulation system 2.

[0022] The control and regulation system 2 is connected to an accelerator pedal or gas pedal of the motor vehicle (not shown in detail). The position of the accelerator pedal represents the driver's desired operation of the vehicle and, depending on the driver's position and other parameters, e.g., the current engine speed, the current gear ratio of the transmission 3 (hereinafter referred to as the drive ratio), and the vehicle mass 4 of the motor vehicle, produces a so-called driver desired torque 5. In other words, this means that the control and regulation system 2 provides a specific driver desired torque depending on the accelerator pedal position and the other parameters. This can be done using corresponding functional equations and / or, as in the present exemplary embodiment, taken from a characteristic map stored in the control and regulation system 2.

[0023] Depending on the driver's desired torque 5, a target torque 6 of the drive unit is calculated, wherein this target torque 6 is transferred equivalently to control variables of the drive unit to be set, in the present embodiment of the internal combustion engine, for example throttle valve, ignition timing, injection quantity, etc., and these are adjusted accordingly with the aid of the control and regulation system 2 so that the determined target torque 6 is realized.

[0024] To determine uniform acceleration of the motor vehicle, particularly during starting and gear shifting, a speed gradient 7 of the drive unit is determined using the method 1 according to the invention. The speed gradient 7, which is a theoretical speed gradient, in other words not a measured speed gradient 7, is calculated based on fundamental physical laws as a function of the driver's desired torque 5, the drive ratio 3, a vehicle-dependent wheel diameter 8, and the vehicle mass 4, with the aid of which the acceleration of the motor vehicle required to achieve the driver's desired torque 5 is determined. Based on this acceleration, the desired speed gradient 7 of the drive unit is calculated.

[0025] Using this calculated speed gradient 7, an additional torque 9 to be applied by the drive unit is determined. The additional torque 9 results from the theoretical speed gradient, which is determined from the vehicle acceleration and the axle ratio. The vehicle acceleration results from the driver's input, the driving resistance 10, the road gradient 11, and the vehicle mass 4.

[0026] The sum of the driver's desired torque 5 and the additional torque 9 ultimately results in the target torque 6, which must be applied by the drive unit. Depending on this target torque 6, the operating parameters of the drive unit, e.g., ignition timing, injection timing, injection quantity, etc., are adjusted using the control and regulation system 2.

[0027] The method 1 according to the invention thus includes an additional torque to be applied by the drive unit, which takes into account the acceleration of the drive unit itself. This has the advantage that, with a constant accelerator pedal position, which is set by the driver of the motor vehicle, a change, for example, in the drive ratio 3 during a gear shift, no longer has any influence on the acceleration perceived by the driver.

Claims

[1] Method for accelerating a motor vehicle, wherein a driver request torque (5) is determined with the aid of a control and regulation system (2) of the motor vehicle as a function of a driver specification of a driver operating the motor vehicle, a vehicle mass (4) of the motor vehicle and further components (3) of a drive train of the motor vehicle, characterized by in that, in order to accelerate the motor vehicle, a target torque (6) of a drive unit of the drive train is determined as a function of the driver's desired torque (5), the target torque (6) including an acceleration of the drive unit itself, and a speed gradient (7) is determined to determine the target torque (6), the speed gradient (7) being used to determine an additional torque (9) of the target torque (6), and the target torque (6) being determined as the sum of the additional torque (9) and the driver's desired torque (5). [2] Method according to claim 1, characterized bythat the speed gradient (7) is a theoretical speed gradient. [3] Method according to claim 1 or 2, characterized by that the speed gradient (7) is determined as a function of the driver's desired torque (5). [4] Method according to one of the preceding claims, characterized by that the target torque (6) is determined as a function of feedback-free influencing variables (3, 4, 10, 11). [5] Method according to claim 4, characterized by that an additional torque (9) of the target torque (6) is determined as a function of the feedback-free influencing variables (3, 4, 10, 11). [6] Method according to claim 4 or 5, characterized by that the feedback-free influencing variables are a drive ratio (3) of the motor vehicle and / or the vehicle mass (4) and / or a driving resistance (10) of the motor vehicle and / or a road gradient (11).

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