Method and device for improved switching between accelerator pedal characteristics

Abstract

Method for specifying a torque output of a motor vehicle drive motor, comprising the following steps: - Detecting accelerator pedal position (S1); - Output of an initial drive output as target drive output to the vehicle drive motor depending on the accelerator pedal position and a selected initial pedal characteristic curve (S2); - Detecting the switch from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve (S3); - Determining a second drive output depending on the accelerator pedal position and the second accelerator pedal characteristic curve (S4); and - Changing the target drive output by a differential output per predetermined time interval from the first drive output to the second drive output (S8, S9); characterized by the following steps: - Determining a target acceleration change that should occur when switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve (S5); - Determining a change in torque as a function of the estimated vehicle mass and the target change in acceleration (S6); and - Determining the differential output from the change in torque (S7).

Description

[0001] The present invention relates to an improved method and an improved device for switching between accelerator pedal characteristics in a motor vehicle. The method and device according to the invention ensure that the acceleration and / or deceleration behavior when switching between accelerator pedal characteristics is reproducible and remains within manageable limits.

[0002] State-of-the-art motor vehicles feature multiple accelerator pedal characteristics that define the relationship between accelerator pedal angle and engine torque and / or drive torque. This makes it possible to impart different driving behavior to the vehicle, for example, economical or sporty. Switching between the accelerator pedal characteristics is usually done via a switch that can be operated by the driver.

[0003] As soon as a new accelerator pedal characteristic is selected, a different drive torque is assigned to the current accelerator pedal angle, even though the accelerator pedal angle hasn't changed. This can cause the vehicle to accelerate sharply even though the driver hasn't changed the accelerator pedal position.

[0004] To avoid abrupt acceleration and / or deceleration, the prior art provides a constant time period within which the drive torque is changed from the value assigned to the original accelerator pedal characteristic curve to the drive torque assigned to the newly selected accelerator pedal characteristic curve. This can lead to the vehicle accelerating unexpectedly sharply if switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve results in a large change in drive torque. On the other hand, the difference between two accelerator pedal characteristic curves may no longer be detectable by the driver if switching between two accelerator pedal characteristic curves with a constant accelerator pedal position results in only a small change in drive torque.

[0005] Further methods for controlling the propulsion of a vehicle are known from the documents DE 10 2004 022 554 B3, DE 10 2007 016 621 A1 and DE 102 10 795 A1.

[0006] The object of the invention is to provide an improved method and an improved device for switching accelerator pedal characteristics.

[0007] The object of the invention is achieved by a method for specifying a torque output of a motor vehicle drive engine, which method detects an accelerator pedal position and outputs a first drive output as the target drive output to the motor vehicle drive engine depending on the accelerator pedal position and a selected first pedal characteristic curve. The switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve is detected, for example, when the accelerator pedal characteristic curve switch is pressed by the driver. A second drive output is determined depending on the accelerator pedal position and the second accelerator pedal characteristic curve. If, for example, a switch is made from an accelerator pedal characteristic curve for an economical driving mode to an accelerator pedal characteristic curve with a sporty driving mode, the second drive output can be higher than the first drive output and the motor vehicle drive engine must provide a higher torque.The target drive output is changed by a differential output per predetermined time interval from the first drive output to the second drive output. The target drive output is changed in at least one step from the first drive output to the second drive output.

[0008] The predetermined time interval can be the period between two calculation steps of an accelerator pedal characteristic switching device and / or the time quantization interval of the accelerator pedal characteristic switching device for outputting the desired drive output.

[0009] The motor vehicle's drive motor can be an internal combustion engine or an electric motor. It is also possible for the motor vehicle's drive motor to be a combination of an internal combustion engine and an electric motor, for example, a hybrid drive.

[0010] The target drive output is changed in at least one step, for example by a ramp with steps.

[0011] According to the invention, a target acceleration change is determined that is to occur when switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve. The target acceleration change can be selected such that, on the one hand, the driver of the motor vehicle perceives a change in acceleration, but, on the other hand, the acceleration change is not so strong that an undesirably strong acceleration occurs. The target acceleration change can, for example, be stored in a database. The target acceleration device can depend on several parameters.

[0012] A torque change is determined as a function of the vehicle mass and the target acceleration change. The target drive output is determined from the torque change.

[0013] The desired drive output may be a torque value, a fuel-air mixture, the fuel ratio in a fuel-air mixture, the current for an electric motor, and the like. The desired drive output may be passed to an engine controller, which determines the optimal fuel-air mixture and the optimal fuel quantity in the fuel-air mixture for the vehicle drive engine to produce the desired torque.

[0014] In the prior art, the time in which the target drive output changes when switching between two accelerator pedal characteristics is constant. This can lead to the target acceleration change being too high or too low. According to the invention, the target acceleration change is specified and the period over which the target acceleration change is applied is kept variable. Thus, the driver perceives a reproducible acceleration change, which is applied for different lengths of time depending on the difference between the first drive output based on the first accelerator pedal characteristic and the second drive output based on the second accelerator pedal characteristic. Consequently, switching between the accelerator pedal characteristics is kept reproducible for the driver and does not lead to undesirably low or undesirably high accelerations.

[0015] The method can also determine a target acceleration that should occur by switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve. It is understood that the target acceleration is the integral of the target acceleration change, and the term "target acceleration change" also includes the target acceleration. The torque change can be determined as a function of the vehicle mass and the target acceleration. The target drive output can be determined from the torque change. Determining the target acceleration change and / or the target acceleration can take into account a plurality of parameters, which include, for example, the speed of the motor vehicle drive engine, the currently engaged gear, the first accelerator pedal characteristic curve, the current speed, the second accelerator pedal characteristic curve, the current accelerator pedal angle, and / or the maximum torque of the motor vehicle drive engine.The target acceleration change and / or the target acceleration may vary depending on the first and / or second accelerator pedal characteristic curve. The target acceleration change and / or the target acceleration when switching between two accelerator pedal characteristic curves may also vary due to the current accelerator pedal angle, the currently engaged gear, the current speed, the speed of the vehicle's drive engine, and / or the maximum torque of the vehicle's drive engine.

[0016] The object of the invention is also achieved by an accelerator pedal characteristic curve switching device. The accelerator pedal characteristic curve switching device can be designed and developed as previously described with regard to the method. Furthermore, the previously described method can be designed as described below with regard to the accelerator pedal characteristic curve switching device.

[0017] The accelerator pedal characteristic curve switching device comprises an accelerator pedal position detection device configured to receive a signal concerning the position of an accelerator pedal, and a target drive output device configured to output a target drive output to a motor vehicle drive engine. Furthermore, the accelerator pedal characteristic curve switching device comprises a control device configured to output a first drive output as a target drive output to the target drive output device depending on the accelerator pedal position and a selected first pedal characteristic curve. The control device detects the switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve. The control device determines a second drive output depending on the accelerator pedal position and the second accelerator pedal characteristic curve.The control device changes the target drive output by a differential output per predetermined time interval from the first drive output to the second drive output. According to the invention, the control device determines a target acceleration change that should occur when switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve. Furthermore, the control device determines a torque change as a function of the vehicle mass and the target acceleration change. The control device determines the target drive output from the torque change.

[0018] The control device can be constructed from a discrete module or component, or it can extend across multiple modules or components. The accelerator pedal detection device can be an electrical interface or a network interface. The desired drive output device can in any case be a specially configured electrical interface or a general network interface.

[0019] The control device can further be configured to determine a target acceleration that is to occur by switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve. The control device can determine the torque change as a function of the vehicle mass and the target acceleration. The target drive output can be determined from the torque change. When determining the target acceleration change and / or the target acceleration, the control device can take into account the speed of the motor vehicle drive engine, the currently engaged gear, the current speed, the first accelerator pedal characteristic curve, the second accelerator pedal characteristic curve, the current accelerator pedal angle, and / or the maximum torque of the motor vehicle drive engine.

[0020] The time interval can be the period between two calculation steps of the accelerator pedal characteristic switching device and / or the time quantization interval of the accelerator pedal characteristic switching device for outputting the desired drive output.

[0021] The invention will be explained in detail below with reference to the figures, which show representations of non-limiting embodiments of the invention and serve to better understand them. They show: Fig. 1 an accelerator pedal characteristic map for a sporty driving mode; Fig. 2 an accelerator pedal characteristic map for a normal driving mode; Fig. 3 an accelerator pedal characteristic map for an economical driving mode; Fig. 4 is a block diagram of the present invention; and Fig. 5 is a flowchart of the present invention.

[0022] Fig. 1 to 3 show exemplary accelerator pedal characteristic curves, where Fig. 1 an accelerator pedal map for a sporty mode, Fig. 2 a characteristic map for a normal driving mode and Fig. 3 corresponds to a characteristic map for an economical driving mode. The X-axis shows the speed in km / h. The Y-axis shows the relative accelerator pedal position. The Z-axis shows the torque delivered by the engine.

[0023] One can see that in Fig. 1 The engine delivers a comparatively high torque even with a relatively small amount of pressure on the accelerator pedal. This allows for a sporty driving mode, as high torque is available even with a slight pressure on the accelerator pedal.

[0024] In contrast, one can see in Fig. 3, which means that even with comparatively strong application of the accelerator pedal, a relatively low torque is delivered by the engine. This allows for an economical driving mode optimized for low fuel consumption. Fig. 2 shows an accelerator pedal characteristic map for a normal driving mode in which the engine response varies between the Fig. 1 and Fig. 3 shown characteristic curve fields.

[0025] Fig. 4 shows an accelerator pedal characteristic curve switching device 1 according to the invention, which comprises an accelerator pedal position detection device 4, a desired drive output device 6, a control device 14, and a memory 16. An accelerator pedal 2 is connected to the accelerator pedal position detection device 4. An engine control unit 8, which is connected to an engine 10, is connected to the desired drive output device 6. The engine 10 outputs torque via a shaft 12. The accelerator pedal position detection device 2 receives the position of the accelerator pedal 2 and transmits the current position of the accelerator pedal 2 to the control device 14. The control device 14 outputs a desired drive output to the desired drive output device 6. The desired drive output is transmitted to the engine control unit 8, which determines a fuel-air mixture and, in particular, the amount of fuel supplied to the engine 10.The fuel is burned in the engine 10 to generate drive torque on the shaft 12. The accelerator pedal characteristic is selected using the accelerator pedal switch 18. The engine 10 can be an internal combustion engine or an electric motor. It is also possible for the engine 10 to be a combination of an internal combustion engine and an electric motor, for example, a hybrid engine.

[0026] Target acceleration changes are stored in memory 16. The target acceleration changes can depend on several parameters, for example, the engine speed, the currently engaged gear, the current speed, the current accelerator pedal characteristic, the previously used accelerator pedal characteristic, the current accelerator pedal angle, and / or the maximum torque of the vehicle's drive engine.

[0027] With reference to Fig.5, the method according to the invention and the operation of the accelerator pedal characteristic curve switching device 1 are explained. In step S1, the accelerator pedal position detection device 4 checks the position of the accelerator pedal, which the driver can change by actuating the accelerator pedal. In step S2, a first drive output is output as a target drive output to the engine 10, depending on the accelerator pedal position and a selected first pedal characteristic curve, by means of the target drive output output device 6.

[0028] In step S3, a check is made to determine whether the driver has changed the accelerator pedal characteristic curve by operating an accelerator pedal characteristic curve switch 18. If the accelerator pedal characteristic curve has not been changed, the process returns to step S1. If the accelerator pedal characteristic curve switching device 1 detects that the accelerator pedal characteristic curve has been changed by pressing the accelerator pedal characteristic curve switch 18, the method and the accelerator pedal characteristic curve switching device 1 continue with step S4. In step S4, a second drive output is determined as a function of the accelerator pedal position and the second accelerator pedal characteristic curve.

[0029] In step S5, a target acceleration change is determined that is to occur by switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve, for example, by retrieving a value from memory 16. In step S6, a torque change is determined as a function of the estimated vehicle mass and the target acceleration change. In step S7, a differential output is then determined from the torque change. The differential output indicates the amount by which the target drive output is to change per unit of time. In one embodiment, the differential output can have the unit sec. -3 , have.

[0030] Estimating the mass of the vehicle may also include determining the mass with sufficient accuracy. Step S6 for determining the torque change may also take into account driving resistance, wind conditions, a gradient, and the like.

[0031] In step S8, the target drive output can be increased by the differential output per predetermined time interval from the first drive output, which is assigned to the first accelerator pedal characteristic curve, to the second drive output, which is assigned to the second accelerator pedal characteristic curve. The time interval can be the period between two calculation steps of the accelerator pedal characteristic curve switching device. The period can also be the time quantization interval of the accelerator pedal characteristic curve switching device 1 for outputting the target drive output via the target drive output output device 6.

[0032] In step S9, a check is made to determine whether the target drive output is less than the second drive output. If the target drive output is less than the second drive output, the engine 10 is not yet providing the torque that should be delivered based on the current accelerator pedal position and the second accelerator pedal characteristic curve. Therefore, the method returns to step S8 and again increases the target drive output by the difference output.

[0033] It is understood that the accelerator pedal position is checked (cyclically) during the execution of steps S4 to S9. As soon as the accelerator pedal position has been changed, the second drive output, the target acceleration change, the differential output, and / or the target drive output are recalculated based on the changed accelerator pedal position. This allows a change in the accelerator pedal position, which represents an acceleration or deceleration desired by the driver, to be taken into account even during the switching of the accelerator pedal characteristic curve.

[0034] If the target drive output is not less than the drive output, the method returns to step S1. This completes the switching from the first accelerator pedal characteristic curve to the second accelerator pedal characteristic curve.

[0035] The present invention provides the advantage that switching from one accelerator pedal characteristic curve to another results in a reproducible torque change. This can increase driving comfort and safety, as unexpected accelerations and decelerations cannot occur.

Claims

[1] Method for specifying a torque output of a motor vehicle drive engine, comprising the following steps: - Detecting an accelerator pedal position (S1); - outputting a first drive output as a target drive output to the motor vehicle drive engine as a function of the accelerator pedal position and a selected first pedal characteristic curve (S2); - detecting the switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve (S3); - determining a second drive output as a function of the accelerator pedal position and the second accelerator pedal characteristic curve (S4); and - changing the target drive output by a differential output per predetermined time interval from the first drive output to the second drive output (S8, S9); characterized by following steps: - determining a target acceleration change which is to occur by switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve (S5); - Determining a torque change as a function of the estimated vehicle mass and the target acceleration change (S6); and - Determine the differential output from the torque change (S7). [2] Method according to claim 1, characterized by the following steps: - Determining a target acceleration that is to occur by switching from the first accelerator pedal characteristic curve to the second accelerator pedal characteristic curve as an integral of the target acceleration change; - Determining the torque change as a function of the vehicle mass and the target acceleration; and - Determine the target drive output from the torque change. [3] Method according to claim 1, wherein the step of determining the desired acceleration change takes into account at least one of the following variables: - the speed of the motor vehicle engine, - the currently engaged gear, - the current speed, - the first accelerator pedal characteristic curve, - the second accelerator pedal characteristic curve, - the current accelerator pedal angle and - the maximum torque of the vehicle's engine. [4] Method according to claim 2, wherein the step of determining the target acceleration takes into account at least one of the following variables: - the speed of the motor vehicle engine, - the currently engaged gear, - the current speed, - the first accelerator pedal characteristic curve, - the second accelerator pedal characteristic curve, - the current accelerator pedal angle and - the maximum torque of the vehicle's engine. [5] Method according to one of the preceding claims, characterized by that the time interval is at least one of the following: - the period between two calculation steps of an accelerator pedal characteristic switching device; and - the time quantization interval of the accelerator pedal characteristic switching device for outputting the target drive output. [6] Accelerator pedal characteristic switching device (1), with - an accelerator pedal position detection device (4) which is designed to receive a signal about the position of an accelerator pedal (2); - a target drive output device (6) designed to output a target drive output to a motor vehicle drive engine (10); and - a control device (14) which is designed to - to output a first drive output as a target drive output to the target drive output device depending on the accelerator pedal position and a selected first pedal characteristic curve; - to detect the switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve; - to determine a second drive output depending on the accelerator pedal position and the second accelerator pedal characteristic curve; and - to change the target drive output by a differential output per predetermined time interval from the first drive output to the second drive output; characterized by that the control device (14) is further designed to - to determine a target acceleration change that is to occur when switching from a first accelerator pedal characteristic curve to a second accelerator pedal characteristic curve; - to determine a torque change as a function of the estimated vehicle mass and the target acceleration change; and - to determine the differential output from the torque change. [7] Accelerator pedal characteristic switching device (1) according to claim 6, characterized by that the control device (14) is further designed to - to determine a target acceleration which is to occur by switching from the first accelerator pedal characteristic curve to the second accelerator pedal characteristic curve, as an integral of the target acceleration change; - to determine a torque change as a function of the vehicle mass and the target acceleration; and - to determine the target drive output from the torque change. [8] Accelerator pedal characteristic switching device (1) according to claim 6, characterized bythat the control device (14) is designed to take into account at least one of the following variables when determining the desired acceleration change: - the speed of the motor vehicle drive engine (10), - the currently engaged gear, - the current speed, - the first accelerator pedal characteristic curve, - the second accelerator pedal characteristic curve, - the current accelerator pedal angle (2), and - the maximum torque of the vehicle's engine. [9] Accelerator pedal characteristic switching device (1) according to claim 7, characterized by that the control device (14) is designed to take into account at least one of the following variables when determining the target acceleration: - the speed of the motor vehicle drive engine (10), - the currently engaged gear, - the current speed, - the first accelerator pedal characteristic curve, - the second accelerator pedal characteristic curve, - the current accelerator pedal angle (2), and - the maximum torque of the vehicle's engine. [10] Accelerator pedal characteristic switching device (1) according to one of claims 7 to 9, characterized by that the time interval is at least one of the following: - the period between two calculation steps of the accelerator pedal characteristic switching device; and - the time quantization interval of the accelerator pedal characteristic switching device for outputting the target drive output.

Images