Method for operating a motor vehicle and control device

Abstract

Method for operating a motor vehicle (1, 11), wherein an operation of at least one assembly of the motor vehicle (1, 11) is controlled and / or regulated depending on a current road gradient of a road on which the motor vehicle is currently operated, wherein the current road gradient is determined depending on a current acceleration and current speed of the motor vehicle, characterized in that the determined, current road gradient is saved, when a defined operating state of the motor vehicle (1, 11) exists in which the current road gradient cannot be determined or cannot be determined with sufficient reliability, namely a locking braking operation with a blocked output (3, 13) and / or a state with a slip on the output (3, 13) that is greater than a slip limit value, and / or cornering with a curve radius that is smaller than a curve limit value, and / or a rocking-free operation, stored road gradients are used to regulate and / or control the operation of the at least one component of the motor vehicle (1, 11) instead of the current road gradient, which were previously determined and stored a respective defined period of time or a respective defined travel distance, in such a way that for the regulation and / or control of the operation of the at least one component of the motor vehicle (1,11) an average value calculated from the several stored road gradients is used, when the defined operating state of the motor vehicle, in which the current road gradient cannot be determined or cannot be determined with sufficient reliability, no longer exists, a transition filter is used to change from the road gradient used when the defined operating state exists to the current road gradient.

Description

[0001] The invention relates to a method for operating a motor vehicle. Furthermore, the invention relates to a control unit for operating a motor vehicle.

[0002] The drivetrain of an electric vehicle has at least a drive unit and an output. In an electric vehicle, a transmission can optionally be connected between the drive unit and the output. In a combustion engine-powered vehicle, a transmission is always connected between the drive unit and the output. A transmission converts speeds and torques and provides the drive unit's tractive power to the output.

[0003] A transmission has several shifting elements, which can be designed as frictional shifting elements and / or as positive shifting elements. A frictional shifting element is, in particular, a clutch or brake. A positive shifting element is, in particular, a claw. In each engaged gear of a transmission, a first number of the shifting elements of the transmission are closed and a second number of the shifting elements of the transmission are open. To perform a gear change, at least one previously closed shifting element is opened and at least one previously open shifting element is closed.

[0004] A motor vehicle may further comprise a separating element. In an electric vehicle, such a separating element may be connected between the electric motor serving as the drive unit and the output. In a motor vehicle powered by an internal combustion engine, such a separating element may be connected between the drive unit and the transmission. Such a separating element is, in particular, a frictional clutch that can be used as a starting element.

[0005] It is known from practice that the operation of at least one component of the motor vehicle is controlled and / or regulated depending on the current road gradient of a road on which the motor vehicle is currently operated.

[0006] DE 10 2014 201 769 A1 discloses a method for determining a road gradient, wherein the road gradient is determined depending on the current speed of the motor vehicle and its current acceleration. According to DE 10 2014 201 769 A1, a Kalman filter is used. The current speed is preferably measured. The current acceleration can be measured or calculated.

[0007] DE 198 02 630 A1 discloses a method for operating a motor vehicle, wherein the operation of at least one component of the motor vehicle is controlled and / or regulated depending on a current vehicle mass and a current road gradient of a road on which the motor vehicle is currently being operated. The current vehicle mass is determined depending on a current acceleration of the motor vehicle. The road gradient is determined depending on the previously determined vehicle mass.

[0008] DE 10 2017 209 747 A1 discloses a method for determining the gradient of a roadway. The gradient of the roadway is determined using stochastic filtering as a function of the vehicle's speed in the direction of travel and its inertial acceleration.

[0009] DE 102 21 835 A1, DE 10 2017 127 369 B3, DE 10 2010 030 346 A1 and DE 10 2006 030 352 A1 disclose further prior art.

[0010] If the current road gradient is determined as a function of the acceleration and the current speed of the motor vehicle, it may be that the road gradient cannot be determined at all or not with sufficient reliability under certain operating conditions of the motor vehicle. In this case, the operation of the motor vehicle component that is to be controlled and / or regulated as a function of the current road gradient can no longer be carried out reliably. There is therefore a need for a method for operating a motor vehicle and for a control unit for operating a motor vehicle that enable reliable operation of the motor vehicle even if the current road gradient can no longer be reliably determined on the basis of the current speed and the current acceleration.

[0011] Based on this, the invention is based on the object of creating a novel method and control device for operating a motor vehicle. This object is achieved by a method according to claim 1 and a control device according to claim 6.

[0012] According to the invention, the determined, current road gradient is stored. If a defined operating state of the motor vehicle exists in which the current road gradient cannot be determined, or cannot be determined with sufficient reliability, depending on the current acceleration and current speed of the motor vehicle, stored road gradients, which were previously determined and stored a respective defined time period or a respective defined travel distance, are used to regulate and / or control the operation of the at least one component of the motor vehicle instead of the current road gradient.

[0013] The invention proposes that if, in a defined operating state of the motor vehicle, the current road gradient cannot be determined or cannot be determined with sufficient reliability, namely based on the current acceleration and the current speed of the motor vehicle, stored road gradients be used instead of the current road gradient to regulate and / or control the operation of at least one component of the motor vehicle. The respective stored road gradient was previously determined and stored a defined respective time period or a defined respective travel distance.

[0014] The regulation and / or control of the operation of the at least one component of the motor vehicle, the operation of which is to be controlled and / or regulated on the basis of the road gradient, takes place in those operating states in which the current road gradient cannot be determined or cannot be determined with sufficient reliability on the basis of the current speed and current acceleration of the motor vehicle, on the basis of historical, previously determined and stored road gradients.

[0015] The defined operating state of the motor vehicle in which the current road gradient cannot be determined or cannot be determined with sufficient reliability depending on the current acceleration and current speed of the motor vehicle is a locked braking operation with blocked output and / or a condition with slip at the output that is greater than a slip limit and / or cornering with a curve radius that is smaller than a curve limit and / or rocking operation. In all of these operating states, the road gradient cannot be determined or cannot be determined with sufficient reliability based on the speed and acceleration of the motor vehicle. Information about a locked braking operation can be provided, for example, by an ABS system and information about slip at the output via an ASR system of the motor vehicle.Cornering can be determined based on a steering angle sensor or based on wheel speeds at the output. The use of rocking mode as an operating state is also known on the control side.

[0016] If such a defined operating state exists, the control and / or regulation of a component of the motor vehicle, the operation of which is to be controlled and / or regulated on the basis of the road gradient, is not carried out on the basis of a currently calculated road gradient, but rather on the basis of historical road gradients previously determined and stored for a respective defined period of time or a respective defined route.

[0017] When the defined operating state of the motor vehicle is present, an average value calculated from the multiple stored road gradients is used to regulate and / or control the operation of at least one component of the motor vehicle. This allows the operation of the component, which is to be controlled and / or regulated based on the road gradient, to be carried out particularly advantageously.

[0018] When the defined operating state of the motor vehicle no longer exists, a transition filter, preferably a weighted mean filter, is used to switch from the road gradient used when the defined operating state was present to the current road gradient. This also allows for advantageous operation of the module that is controlled and / or regulated based on the road gradient.

[0019] Preferably, the operation of an electric motor is controlled and / or regulated as a component of the motor vehicle depending on the gradient of the roadway on which the motor vehicle is operated. Alternatively or additionally, the operation of at least one internal transmission shifting element and / or at least one external transmission separating element is controlled and / or regulated as a component of the motor vehicle depending on the gradient of the roadway on which the motor vehicle is operated.

[0020] The invention can be used in a purely electrically powered vehicle, a purely combustion engine powered vehicle, or a hybrid vehicle.

[0021] Preferred developments emerge from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail, without being limited thereto, with reference to the drawing. Herein: Fig. 1 shows a first drive train diagram of a motor vehicle; Fig. 2 a second drive train diagram of a motor vehicle.

[0022] Fig. 1 shows a drive train of a motor vehicle 1 designed as an electric vehicle. The drive train has a drive unit 2 and an output 3. The drive unit 2 is an electric machine that provides drive torque to the output 3. The operation of the electric machine and thus of the drive unit 2 is controlled and / or regulated by a control unit 4, with the control unit 4 exchanging data with the electric machine 2 for this purpose.

[0023] Fig. 2 shows a drive train 11 of a motor vehicle, which can be designed as a purely electrically powered vehicle or as a purely internal combustion engine-powered vehicle. A drive unit 12 of the motor vehicle can therefore be designed as an electric machine or an internal combustion engine. A transmission 15 is connected between the drive unit 12 and an output 13, which converts torques and speeds and provides the tractive force of the drive unit 12 to the output 13. While the operation of the drive unit 12 is controlled and / or regulated by an engine control unit 14, the operation of the transmission 15 is controlled and / or regulated by a transmission control unit 16. Fig. Figure 2 further shows a transmission-internal shifting element 17, which can be opened or closed, in particular, to perform gear changes. Typically, a transmission 15 contains several such shifting elements 17, which can be designed as positive-locking shifting elements and / or friction-locking shifting elements. Furthermore, Fig. 2, a separating element 18, which is connected between the drive unit 12 and the transmission 15. This separating element 18 can be a separating clutch that can be used as a starting clutch. The separating element 18 can also be omitted, in which case a transmission-internal shifting element 17 is used as the starting element.

[0024] The invention can also be used in a hybrid vehicle having multiple drive units, namely an internal combustion engine as the first drive unit and an electric motor as the second drive unit. Typically, the electric motor is connected between the internal combustion engine and the transmission, with a separating element designed as a clutch being connected between the internal combustion engine and the electric motor to decouple the internal combustion engine from the output, particularly when the engine is shut down.

[0025] It is known to control and / or regulate the operation of at least one component of the motor vehicle 1, 11 depending on a current road gradient of a road on which the motor vehicle 1, 11 is currently operated, i.e. is currently driving.

[0026] It is thus possible that the control unit 4 of the motor vehicle 1 of the Fig. 1 controls and / or regulates the operation of the drive unit 2 designed as an electric machine on the basis of the current road gradient.

[0027] In motor vehicle 11 of the Fig. 2, it is possible for the engine control unit 14 to control and / or regulate the operation of the drive unit 12 and / or the control unit 16 to control and / or regulate the operation of the transmission 15, for example a transmission-internal shift element 17, on the basis of the current road gradient.

[0028] It is also known from practice how the current road gradient can be determined. DE 10 2014 201 769 A1 discloses a method for determining the current road gradient depending on the current speed of the motor vehicle and the current acceleration of the motor vehicle.

[0029] The invention now relates to details which allow the motor vehicle to be operated reliably even when the current road gradient cannot be determined or cannot be determined with sufficient reliability, namely that component of the motor vehicle whose operation is controlled and / or regulated as a function of the road gradient.

[0030] In the sense of the present invention, it is proposed that when a defined operating state of the motor vehicle exists in which the current road gradient cannot be determined or cannot be determined with sufficient reliability depending on the current speed of the motor vehicle 1, 11 and depending on the current acceleration of the motor vehicle 1, 11, stored road gradients are used instead of the current road gradient to regulate and / or control the operation of the respective component of the motor vehicle.

[0031] Whenever a road gradient can be reliably determined based on the current speed of the motor vehicle 1, 11 and based on the current acceleration of the motor vehicle 1, 11, the determined road gradient is saved so that it is subsequently available. If the road gradient cannot be determined, or cannot be determined with sufficient reliability, based on the current speed of the motor vehicle 1, 11 and based on the current acceleration of the motor vehicle 1, 11, road gradients that were previously determined and saved for a respective defined period of time or a respective defined distance are used to regulate and / or control the operation of the respective module.

[0032] The defined operating state of the motor vehicle 1, 11, in which the current road gradient cannot be determined or cannot be determined with sufficient reliability depending on the current speed of the motor vehicle 1, 11 and depending on the current acceleration of the motor vehicle 1, 11, is a locking braking operation with blocked output 3, 13 and / or a state with a slip at the output 3, 13 that is greater than a slip limit value, and / or cornering with a curve radius that is smaller than a curve limit value, and / or rocking-free operation of the motor vehicle 1, 11.

[0033] Information about the above operating states is available on the control side.

[0034] In this way, data on the presence of a locking brake can be provided by an ABS system.

[0035] The presence of slip at the output 3, 13 that is greater than a slip limit value can be provided by an ASR system.

[0036] ABS and ASR systems are components of an ESP system.

[0037] A curve radius can be determined from a steering angle, which can be provided, for example, by a steering angle sensor or determined depending on wheel speeds.

[0038] Rocking-free operation is typically triggered by the driver.

[0039] As already explained, the component of the motor vehicle which is controlled and / or regulated in the manner according to the invention on the basis of stored road gradients can be a drive unit 2, 12 designed as an electric machine or a transmission 15, namely at least one switching element 17 thereof, and / or the separating element 18.

[0040] When the defined operating state of the motor vehicle 1, 11 is present, in which the road gradient cannot be determined or cannot be determined with sufficient reliability, an average value formed from several stored road gradients is used to regulate and / or control the operation of the respective component of the motor vehicle, which is to be controlled and / or regulated on the basis of the road gradient, for example a weighted average value of several stored road gradients.

[0041] A currently determined road gradient is preferably stored in a ring buffer. In such a ring buffer, the oldest stored road gradient is deleted when a newly determined current road gradient is stored.

[0042] Then, if the defined operating state of the motor vehicle is initially present, in which the road gradient cannot be determined or cannot be determined with sufficient reliability depending on the current speed of the motor vehicle 1, 11 and depending on the current acceleration of the motor vehicle 1, 11, and if this defined operating state is subsequently no longer present, i.e. the current road gradient can subsequently be determined again with sufficient reliability depending on the current speed and depending on the current acceleration, a transition filter is used to transfer or change from the road gradient used when the operating state is present, which is dependent on stored road gradients, to the currently determined road gradient.A mean value filter can be used as transition filtering, for example a weighted mean value or a moving mean value.

[0043] The invention further relates to a control unit configured to automatically execute the method described above on the control side. Thus, the control unit stores determined, current road gradients. If a defined operating state of the motor vehicle exists in which the current road gradient cannot be determined, or cannot be determined with sufficient reliability, depending on the current speed and the current acceleration of the motor vehicle 1, 11, the control unit uses, in the manner described above, stored road gradients, instead of the current road gradient, to regulate and / or control the operation of at least one component of the motor vehicle. These stored road gradients were previously determined and stored a respective defined period of time or a respective defined distance traveled.

[0044] The control unit can be the engine control unit 4, 14, or the transmission control unit 16. The control unit is designed as an electronic control unit and has hardware and software means for implementing the method according to the invention. The hardware means include a memory for data storage, a processor for data processing, and at least one data interface for exchanging data with the modules involved in executing the method according to the invention. The software means include program modules implemented in the control unit for implementing the method according to the invention.

[0045] The invention enables reliable operation of a respective assembly that is to be controlled and / or regulated based on a current road gradient, even if the current road gradient cannot be determined, or cannot be determined with sufficient reliability, as a function of the current speed of the motor vehicle 1, 11 and as a function of the current acceleration of the motor vehicle 1, 11, namely in a respective defined operating state of the motor vehicle. In this case, stored road gradients are used instead of the current road gradient for the control and / or regulation of the operation of the respective assembly, wherein the respective stored road gradient was previously determined and stored a respective defined period of time or a respective defined distance traveled. Reference symbol 1 drivetrain 2 drive unit 3 downforce 4 Control unit 11 Drivetrain 12 drive unit 13 Downforce 14 Control unit 15 gearboxes 16 Control unit 17 Switching element 18 Separator

Claims

[1] Method for operating a motor vehicle (1, 11), wherein an operation of at least one component of the motor vehicle (1, 11) is controlled and / or regulated depending on a current road gradient of a road on which the motor vehicle is currently operated, wherein the current road gradient is determined depending on a current acceleration and current speed of the motor vehicle, characterized by , that the determined, current road gradient is saved, when a defined operating state of the motor vehicle (1, 11) exists in which the current road gradient cannot be determined or cannot be determined with sufficient reliability, namely a locking braking operation with a blocked output (3, 13) and / or a state with a slip on the output (3, 13) that is greater than a slip limit value, and / or cornering with a curve radius that is smaller than a curve limit value, and / or a rocking-free operation, stored road gradients are used to regulate and / or control the operation of the at least one component of the motor vehicle (1, 11) instead of the current road gradient, which were previously determined and stored a respective defined period of time or a respective defined travel distance, in such a way that for the regulation and / or control of the operation of the at least one component of the motor vehicle (1,11) an average value calculated from the several stored road gradients is used, when the defined operating state of the motor vehicle, in which the current road gradient cannot be determined or cannot be determined with sufficient reliability, no longer exists, a transition filter is used to change from the road gradient used when the defined operating state exists to the current road gradient. [2] Method according to claim 1, characterized by that, as a component of the motor vehicle (1, 11), the operation of an electrical machine (2, 12) is controlled and / or regulated depending on the road gradient of the road on which the motor vehicle is operated. [3] Method according to claim 1 or 2, characterized bythat, as a subassembly of the motor vehicle (1, 11), the operation of at least one transmission-internal shifting element (17) and / or at least one transmission-external separating element (18) is controlled and / or regulated depending on the road gradient of the road on which the motor vehicle is operated. [4] Method according to one of claims 1 to 3, characterized by that the determined current road gradient is stored in a ring buffer, in which the oldest stored road gradient is deleted when a new determined current road gradient is stored. [5] Method according to one of claims 1 to 4, characterized by that mean value filtering is used as transition filtering. [6] Control device for operating a motor vehicle (1, 11), wherein the control unit controls and / or regulates the operation of at least one assembly depending on a current road gradient of a road on which the motor vehicle is currently operated, wherein the control unit determines the current road gradient depending on a current acceleration and current speed of the motor vehicle, characterized by , that the control unit stores the determined, current road gradient, the control unit, when a defined operating state of the motor vehicle (1, 11) exists in which the current road gradient cannot be determined or cannot be determined with sufficient reliability, namely a locking braking with a blocked output (3, 13) and / or a state with a slip on the output (3, 13) that is greater than a slip limit value, and / or cornering with a curve radius that is smaller than a curve limit value, and / or a rocking-free operation, uses stored road gradients for regulating and / or controlling the operation of the at least one component of the motor vehicle (1, 11) instead of the current road gradient, which were previously determined and stored a respective defined period of time or a respective defined route, such thatthat the control unit calculates an average value from the plurality of stored road gradients and uses the calculated average value to regulate and / or control the operation of the at least one component of the motor vehicle (1, 11), When the defined operating state of the motor vehicle, in which the current road gradient cannot be determined or cannot be determined with sufficient reliability, no longer exists, the control unit switches from the road gradient used when the defined operating state exists to the current road gradient with the aid of transition filtering. [7] Control device according to claim 6, characterized by that the control device is set up to carry out the method according to one of claims 1 to 5 on the control side.

Images