Method and device for adjusting the accelerator pedal characteristics of a motor vehicle

Abstract

Method for adapting the accelerator pedal characteristics of a motor vehicle in which an accelerator pedal characteristic curve (1) describing the relationship between accelerator pedal position (P) and engine torque demand of the driver is modified, wherein It is determined whether a situation of increased driving resistance exists; and in the event of increased driving resistance, the accelerator pedal characteristic curve (1) is modified such that a modified characteristic curve (2) requests an increased engine torque (D) at least in a middle range (M) of an accelerator pedal position (P); characterized in that (a) that an upper limit (3) is specified for the deviation of the modified characteristic curve (2) from the original characteristic curve (1); and (b) that a course of the modified characteristic curve (2) is determined in compliance with the upper limit (3) such that at least in the middle range (M) the deviation of the modified characteristic curve (2) from the original characteristic curve (1) is determined as a function of a driving resistance or as a function of a quantity influencing the driving resistance.

Description

[0001] The invention relates to a method and a device for adjusting the accelerator pedal characteristics of a motor vehicle.

[0002] Accelerator pedals typically use electronic systems to control the response to acceleration requests. These pedals control the torque demand on the engine using an accelerator pedal characteristic curve, which describes the relationship between the accelerator pedal position and the driver's engine torque demand.

[0003] Where applicable, the term "engine torque" is used interchangeably with "engine torque" in this document. Both terms are to be considered synonymous within the scope of the present invention. The same applies to the terms "torque requirement" and "moment requirement".

[0004] German patent application DE 10 2004 061 263 B4 discloses a method for influencing the accelerator pedal behavior in a motor vehicle. This method determines whether a potentially hazardous driving situation exists and then adjusts the accelerator pedal behavior accordingly. The potentially hazardous situation is identified using sensor data from an environmental sensor system or a navigation system. The accelerator pedal characteristic is modified by altering the characteristic curve that describes the relationship between the driver's engine torque demand and the accelerator pedal position. To account for the potentially hazardous situation, the engine torque demand for the current accelerator pedal position is reduced, resulting in a lower engine torque demand than would correspond to the accelerator pedal position in a normal driving situation.

[0005] Furthermore, it is known from practical experience that the accelerator pedal response curve is highly progressive. This means that the gradient of the accelerator pedal response curve increases with increasing accelerator pedal position, and the response curve is comparatively flat, particularly in the initial range of the accelerator pedal response curve, for example, from 0% to 20% of the maximum depressible accelerator pedal position. This allows for better maneuverability of the vehicle.

[0006] A disadvantage of this known accelerator pedal characteristic curve is that in situations requiring high starting torque due to high driving resistance, e.g., on an incline or due to a heavy load on a commercial vehicle, the accelerator pedal must be pressed hard. However, in this range, the ability to precisely control the torque demand is very limited due to the highly progressive characteristic curve. This makes a controlled and safe starting process more difficult.

[0007] German patent application DE 10 2004 014 102 A1 discloses an operating procedure for a motor vehicle in which the accelerator pedal position is first determined using an accelerator pedal position sensor. After recording the vehicle speed and, if applicable, operating parameters of the vehicle drive, a decision is made as to which of two operating modes the vehicle drive is in. If the vehicle drive is in the first operating mode, a fixed target speed, independent of the accelerator pedal position, is specified. Subsequently, a target torque is determined based on the target speed and the accelerator pedal position. The dependence of the target torque on the accelerator pedal position is linear, at least in a range, between a minimum and a maximum target torque. If the vehicle drive is in the second operating mode, a monotonically increasing speed is specified, and a target torque is determined based on the target speed and the accelerator pedal position.

[0008] German patent application DE 100 49 138 A1 relates to a method for supporting driving situations of a vehicle during HDC operation, in which operating parameters of the vehicle are changed or adjusted via a pedal. In order to improve the control of a vehicle in HDC operation (HDC = Hill Descent Control), driving situations such as starting or driving downhill are carried out with a modified pedal characteristic adapted to these driving situations.

[0009] German patent application DE 10 2008 011 607 A1 discloses a method for adapting the accelerator pedal characteristics in a vehicle to the situation based on information describing the environment. The change in engine torque is implemented progressively or degressively compared to a linear relationship between accelerator pedal position and requested engine torque.

[0010] German patent application DE 40 29 976 A1 relates to a method for controlling the operating characteristics of a vehicle with an automatic transmission, wherein, depending on the detection of a driving condition for the vehicle, an operating characteristic is selected and, when a signal to change the current operating characteristic to a target operating characteristic is present, e.g. by changing the transmission shift state, a temporary intermediate operating characteristic is first set, the driver's reaction to this is detected and only then is the vehicle switched to the target operating characteristic, held in the intermediate state of the temporary operating characteristic or switched back to the original operating characteristic.

[0011] The patent application DE 40 29 976 A1 discloses a method for influencing the drive torque of a vehicle during a starting process in the sense of positive vehicle acceleration, in which a measure for the drive torque requested by the driver is specified via at least one accelerator pedal position and the drive torque of the vehicle is increased beyond the measure desired by the driver, independent of the driver.

[0012] It is therefore an object of the invention to provide an improved method for adapting the accelerator pedal characteristics of a motor vehicle, thereby avoiding the disadvantages of conventional techniques. In particular, the object of the invention is to provide an improved method for adapting the accelerator pedal characteristics of a motor vehicle, thereby enabling improved maneuverability of the vehicle. A further object is to provide a device for adapting the accelerator pedal characteristics of a motor vehicle, thereby avoiding the disadvantages of conventional devices.

[0013] These problems are solved by a method with the features of the main claim and by a device with the features of the dependent claim. Advantageous embodiments and applications of the invention are the subject of the dependent claims and are explained in more detail in the following description with partial reference to the figures.

[0014] The invention relates to a method for adapting the accelerator pedal characteristics of a motor vehicle, in which an accelerator pedal characteristic curve describing the relationship between accelerator pedal position and the driver's engine torque demand is modified. According to the method, it is determined whether a situation of increased driving resistance exists. If such a situation exists, the accelerator pedal characteristic curve is modified such that a modified characteristic curve demands increased engine torque, at least in a mid-range of the accelerator pedal position. By modifying the accelerator pedal characteristic curve in this way, for example in a control unit, the response behavior of the accelerator pedal can be specifically altered so that, in the case of increased driving resistance, the necessary starting torque is achieved even at a lower accelerator pedal position, thus also improving the modulation.By means of the modified accelerator pedal characteristic curve, the accelerator pedal position is thus reinterpreted accordingly and adapted to the increased driving resistance.

[0015] One possible implementation according to the invention provides that the deviation of the modified characteristic curve from the original characteristic curve is higher in a middle range of an accelerator pedal position than in an initial and an end range of the accelerator pedal position. This offers the advantage that, on the one hand, dangerously high torques at very small accelerator pedal values ​​can be avoided, and on the other hand, the driving behavior in the end range of the characteristic curve approximates normal driving behavior.

[0016] It is particularly advantageous to define the modified characteristic curve such that, in a middle range of the accelerator pedal characteristic, the average slope of the modified characteristic curve is lower than the slope of the original characteristic curve. This allows for particularly precise control of the vehicle's starting behavior under increased driving resistance, thus enabling safe maneuvering on inclines and / or starting with a heavy load.

[0017] According to the invention, an upper limit is further specified for the deviation of the modified characteristic curve from the original characteristic curve. Such an upper limit can serve as a safety limit to avoid dangerously high torque requirements.

[0018] Furthermore, the modified characteristic curve is defined within the upper limit, such that, at least in the middle range, the deviation of the modified characteristic curve from the original characteristic curve is determined as a function of driving resistance or as a function of a factor influencing driving resistance, such as vehicle mass and / or road gradient. A particular advantage of this design is that the modified characteristic curve can be dynamically adapted to the level of the detected driving resistance, allowing, for example, the curve to be specifically adjusted to the current vehicle load and / or the current road gradient. At the same time, the upper limit ensures that the deviation from the original characteristic curve remains within predefined safety limits.

[0019] According to another variant, a driving resistance can be determined, and if this resistance exceeds a predetermined threshold, the modified characteristic curve is set so that the driving resistance is only partially compensated. Complete, i.e., 100%, compensation would mean that the same accelerator pedal travel would be required to achieve the necessary starting torque regardless of the driving resistance. However, if only partial compensation is applied in situations of increased driving resistance, for example, compensation of 50% of the driving resistance, this offers the advantage that the driver is alerted to the increased driving resistance by the at least partially altered response of the accelerator pedal, thus prompting more attentive maneuvering and increasing safety.This allows for an optimal compromise between improved maneuverability due to the adjustment of the accelerator pedal characteristic and, at the same time, a driving behavior of the driver adapted to the driving situation with increased driving resistance.

[0020] Furthermore, it is possible to define the shape of the modified characteristic curve such that the deviation from the original characteristic curve increases continuously or stepwise with increasing driving resistance. For example, the modified characteristic curve can be increased proportionally with increasing driving resistance to provide a continuous range of characteristic curves. Alternatively, it is possible to assign a modified characteristic curve to each predefined driving resistance range, so that several different accelerator pedal characteristics are used, one of which is selected depending on the specific driving resistance. Furthermore, the invention allows a modified characteristic curve to be determined directly as a function of the vehicle mass and / or an increasing road gradient.

[0021] According to a further preferred embodiment, the deviation of the upper limit from the original characteristic curve is higher in the middle range of an accelerator pedal position than in the initial and final ranges of the accelerator pedal position. As mentioned above, this ensures that dangerously high torque demands at very small accelerator pedal positions can be avoided. In the event of a fault, for example, if an incline is incorrectly detected when the vehicle is on level ground, safe maneuverability can still be guaranteed in this way.

[0022] In the initial range of the accelerator pedal position, the upper limit can also be identical to the original characteristic curve, so that no adjustment of the accelerator pedal characteristic curve takes place in this range.

[0023] Furthermore, in the initial range, the modified characteristic curve can be set such that, for a given accelerator pedal position, the increased engine torque according to the modified characteristic curve does not deviate by more than 10% from the original engine torque according to the original characteristic curve with respect to the maximum engine reference torque that can be requested by the accelerator pedal. This prevents jerky acceleration of the vehicle in the event of an incorrect determination of the driving resistance.

[0024] Advantageously, the modified characteristic curve in the middle range can be set so that it is essentially linear. This allows the accelerator pedal response to be specifically altered in such a way that the driver experiences familiar and easily controllable maneuvering behavior in situations of increased driving resistance.

[0025] The middle range can be defined such that it contains at least a range of 40% to 60% of the accelerator pedal position. More preferably, the middle range can contain at least a range of 35% to 65% of the accelerator pedal position. Within the scope of the invention, it has been found that by adapting the accelerator pedal characteristic curve according to the invention in these ranges, particularly good maneuverability can be achieved in situations of increased driving resistance.

[0026] Furthermore, the initial range can correspond to a range of 0% to at least 10% of the accelerator pedal position. More preferably, the initial range can correspond to a range of 0% to at least 15% or a range of 0% to at least 20% of the accelerator pedal position.

[0027] An increased driving resistance situation can be identified when a calculated driving resistance exceeds a predefined threshold. This increased driving resistance can be recognized particularly in relation to road gradient and / or vehicle mass.

[0028] The invention further relates to a device for adapting the accelerator pedal characteristics of a motor vehicle, comprising detection means for detecting the presence of a situation of increased driving resistance and accelerator pedal adaptation means, which are designed to modify an accelerator pedal characteristic curve describing the relationship between accelerator pedal position and engine torque demand of the driver when a situation of increased driving resistance is present, such that a modified characteristic curve demands increased engine torque at least in a middle range of an accelerator pedal position.

[0029] To avoid repetition, features disclosed purely by procedure should also be deemed disclosed by device and be claimable.

[0030] The invention further relates to a motor vehicle, preferably a commercial vehicle, with the device for adjusting the accelerator pedal characteristics of a motor vehicle.

[0031] Further details and advantages of the invention are described below with reference to the accompanying drawing. Fig. Figure 1 illustrates the adaptation of the accelerator pedal characteristics in a motor vehicle, in particular in a commercial vehicle, according to an embodiment of the invention.

[0032] This shows Fig. 1. The course of a modified characteristic curve 2 compared to the original characteristic curve 1. Characteristic curves 1 and 2 each define the relationship between the accelerator pedal position and the driver's engine torque demand. Characteristic curve 1 is an accelerator pedal characteristic curve known from the prior art, which, according to the invention, is further used as the basis for demanding engine torque in situations of non-increased driving resistance. Fig. Figure 1 shows the strongly progressive curve of the accelerator pedal response curve, the slope of which increases gradually with increasing accelerator pedal position. The abscissa shows the accelerator pedal position P as a percentage of the maximum possible accelerator pedal travel, where 0% corresponds to an unactuated accelerator pedal and 100% to a fully depressed accelerator pedal. The ordinate indicates the driver's engine torque demand as a percentage of a reference engine torque D. The reference engine torque is the maximum engine torque that the engine can deliver. As in Fig. As can be seen in Figure 1, it is common in commercial vehicles that 100% of the engine reference torque D is requested even at 90% of the accelerator pedal travel, i.e., when the accelerator pedal is not fully depressed, since the fully depressed position is used for the so-called kick-down function.

[0033] Furthermore, in Fig. Figure 1 designates an initial range A, a middle range M, and an end range of the accelerator pedal position. In the present embodiment, the initial range comprises 0% to 20% of the accelerator pedal travel, the middle range 35% to approximately 65% ​​of the accelerator pedal travel, and the end range the remaining range of the accelerator pedal travel up to 90%. It is emphasized that the aforementioned percentages are only exemplary and that the definition of the ranges can be determined differently for different applications.

[0034] In situations where there is no increased driving resistance, for example when driving on level ground or with an unloaded vehicle, the original characteristic curve 1 is used as the basis for controlling the motor torque.

[0035] However, if the vehicle control unit detects a situation of increased driving resistance, the original characteristic curve 1 is modified depending on the detected driving resistance, and the modified characteristic curve 2 is used as the basis for controlling the engine torque. Fig. Figure 1 shows that the modified characteristic curve 2 requires a higher engine torque for the same accelerator pedal position, with the deviation from the original characteristic curve being greatest in the mid-range M. This is indicated by the vertical dashed arrows, which represent the deviation of the modified characteristic curve 2 from the original characteristic curve 1.

[0036] In the initial region A, the possible deviation of the modified characteristic curve 2 from the original characteristic curve 1 is very small, with the corresponding sections of these characteristic curves in the initial region being marked with the reference symbols 2_a and 1_a. As mentioned above, this ensures that in the event of a fault, e.g., a false detection of an incline when the vehicle is actually on a level surface, safe acceleration on level ground is still possible, as a dangerously high torque requirement for this situation is avoided.

[0037] In Fig. Furthermore, line 3 indicates an upper limit that specifies the deviation of the modified characteristic curve 2 from the original characteristic curve, which the modified characteristic curve 2 must always adhere to. In other words, the deviation of the modified characteristic curve 2 may not exceed the deviation of the upper limit 3. Fig. Figure 1 shows only a single modified characteristic curve 2, however, within the scope of the invention it is possible to vary the modified characteristic curve 2 in the range between the original characteristic curve 1 and the upper limit 3 depending on the determined driving resistance, so that modified characteristic curves 2 are shifted upwards with increasing driving resistance.

[0038] In Fig.Figure 1 further shows that the modified characteristic curve exhibits a substantially linear profile 2_m in the central region, enabling smooth and consistent maneuvering in situations of increased driving resistance. The horizontal arrow 4 illustrates that a significantly smaller accelerator pedal input is required for the same resulting torque based on the modified characteristic curve 2 compared to the original characteristic curve 1. This makes maneuvering on an incline more comparable to maneuvering on level ground for the driver, as more accelerator pedal travel is available for modulation. This is made possible, in particular, by the fact that the slope of the central section 2_m of the modified characteristic curve is less steep than the comparable central region 1_m of the original characteristic curve in this region M.

[0039] An increased driving resistance situation can be detected when a calculated driving resistance exceeds a predefined threshold. The calculation of driving resistance is known from the prior art and is a parameter typically available in the known control units of commercial vehicles. It is determined using a vehicle model that calculates or estimates parameters relevant to driving resistance, such as air resistance, rolling resistance, gradient resistance, and acceleration resistance. Parameters such as road gradient are calculated, for example, using an acceleration sensor, while the vehicle mass can be estimated from engine torque and the resulting vehicle acceleration. Reference symbol list 1 Original characteristic curve 1_a Initial region of the original characteristic curve 1_m Middle range of the original characteristic curve 2 Modified characteristic curve 2_a 2_m Initial region of the modified characteristic curve Middle region of the modified characteristic curve 3 Upper limit 4 Reduced accelerator pedal travel A starting area M Middle range E End range D Motor torque P Accelerator pedal position

Claims

[1] Method for adapting the accelerator pedal characteristics of a motor vehicle in which an accelerator pedal characteristic curve (1) describing the relationship between accelerator pedal position (P) and engine torque demand of the driver is modified, wherein It is determined whether a situation of increased driving resistance exists; and in the event of increased driving resistance, the accelerator pedal characteristic curve (1) is modified such that a modified characteristic curve (2) requests an increased engine torque (D) at least in a middle range (M) of an accelerator pedal position (P); characterized by , (a) that an upper limit (3) is specified for the deviation of the modified characteristic curve (2) from the original characteristic curve (1); and (b) that a course of the modified characteristic curve (2) is determined in compliance with the upper limit (3) such that at least in the middle range (M) the deviation of the modified characteristic curve (2) from the original characteristic curve (1) is determined as a function of a driving resistance or as a function of a quantity influencing the driving resistance. [2] Method according to claim 1, characterized by , that a deviation of the modified characteristic curve (2) from the original characteristic curve (1) in a middle range (M) of an accelerator pedal position (P) is higher than in an initial (A) and an end range (E) of the accelerator pedal position (P). [3] Method according to claim 1 or 2, characterized by , that in a middle range (M) of the accelerator pedal characteristic curve, the average slope of the modified characteristic curve (2) is lower than the slope of the original characteristic curve (1). [4] Method according to any one of the preceding claims, characterized bythat the quantity influencing driving resistance is the vehicle mass and / or the road gradient. [5] Method according to any one of the preceding claims, characterized by , that a driving resistance is determined and, if the determined driving resistance exceeds a predetermined threshold, that the modified characteristic curve (2) is set such that the driving resistance is only partially compensated by the modified characteristic curve (2). [6] Method according to any one of the preceding claims, characterized by , that the course of the modified characteristic curve (2) is determined such that the deviation from the original characteristic curve (1) increases continuously or gradually with increasing driving resistance. [7] Method according to any one of claims 3 to 6, characterized by , (a) that a deviation of the upper limit (3) from the original characteristic curve (1) in a middle range (M) of an accelerator pedal position (P) is higher than in the initial (A) and final ranges (E) of the accelerator pedal position (P); and / or (b) that the upper limit (3) in the initial range (A) of the accelerator pedal position (P) is identical to the original characteristic curve (1) or for a given accelerator pedal position (P) the increased engine torque (D) according to the modified characteristic curve (2) does not deviate by more than 10% from the original engine torque according to the original characteristic curve (1) with respect to a maximum engine reference torque that can be requested by the accelerator pedal. [8] Method according to any one of the preceding claims, characterized by , that the course of the modified characteristic curve (2) in the middle range (M) is essentially linear. [9] Method according to any one of the preceding claims, characterized by , (a) that the middle range (M) includes at least a range of 40% to 60% of the accelerator pedal position (P); and / or (b) that the middle range (M) includes at least a range of 35% to 65% of the accelerator pedal position (P). [10] Method according to any one of the preceding claims, characterized by , (a) that the initial range (A) corresponds to a range from 0% to at least 10% of the accelerator pedal position (P); and / or (b) that the initial range (A) corresponds to a range from 0% to at least 15% of the accelerator pedal position (P). [11] Method according to any one of the preceding claims, characterized by , (a) that the presence of a situation of increased driving resistance is detected when a calculated driving resistance is greater than a predetermined threshold; and / or (b) that the presence of a situation of increased driving resistance is recognized depending on a road gradient and / or vehicle mass. [12] Device for adjusting the accelerator pedal characteristics in a motor vehicle, comprising Investigative tools for determining the existence of a situation of increased driving resistance; and Accelerator pedal adaptation means designed to modify, in the presence of a situation of increased driving resistance, an accelerator pedal characteristic curve describing the relationship between accelerator pedal position (P) and the driver's engine torque demand, such that a modified characteristic curve (2) demands an increased engine torque (D) at least in a middle range (M) of an accelerator pedal position (P), characterized by , (a) that an upper limit (3) is specified for the deviation of the modified characteristic curve (2) from the original characteristic curve (1); and (b) that a course of the modified characteristic curve (2) is determined in compliance with the upper limit (3) such that at least in the middle range (M) the deviation of the modified characteristic curve (2) from the original characteristic curve (1) is determined as a function of a driving resistance or as a function of a quantity influencing the driving resistance. [13] Motor vehicle, preferably commercial vehicle, with a device according to claim 12.

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