Braking system with adjustable brake pedal characteristics

Abstract

Braking system with an electronic control unit (1) and with a brake pedal, the pedal travel (s Pedal ) and / or pedal force (F Pedal ) can be detected by the control unit (1), wherein the control unit (1) is designed such that, depending on manually or automatically generated parameters, one brake pedal characteristic from a plurality of predetermined brake pedal characteristics (C1 to C5) can be activated, wherein the brake pedal characteristics (C1 to C5) can be predetermined via vehicle deceleration-brake pedal travel characteristics (K1) and at least in defined sections between a first extreme with a comparatively short pedal travel (s Pedal ) with a comparatively high deceleration (a) and a second extremum with a comparatively long pedal travel (s pedal ) at a comparatively low delay (a), • where a special driving situation, “Chauffeur” mode, which can be selected manually or automatically detected via the seat occupancy and in which at least one passenger is detected, a corresponding “Chauffeur” brake pedal characteristic (C3) can be activated, • and / or wherein, in the case of a special driving situation which can only be detected automatically, a corresponding “creaking prevention” brake pedal characteristic (C5) can be activated, by means of which a comparatively high deceleration change can be carried out for a predetermined number of braking operations when a brake disc moisture risk is detected only in a lower deceleration range with only a small change in the brake pedal force.

Description

State of the art

[0001] Modern vehicles contain systems that can adapt vehicle characteristics to the driver's wishes. One such system is described in the published patent application DE 103 35 057 A1. This describes various vehicle components that can be used to vary the perceived vehicle characteristics. The decisive factors for this are the chassis and drivetrain components. In the chassis area, for example, the characteristics of the shock absorbers, the roll stabilization, and the steering can be influenced. In the drivetrain area, in particular the characteristic curve of the accelerator pedal and the shift characteristics of automatic transmissions are varied. Each of these components is intended to have different characteristics (e.g. sporty or economical) in order to be able to represent a virtually continuously variable variation. The control of the systems is implemented by the driver.The driver has the option of controlling various components in a kind of “equalizer” and adapting them to the individual driver’s wishes.

[0002] A similar system is described in published patent application EP 1 355 209 A1. This system adapts various subsystems based on the current driving situation. These subsystems include, among others, the spring-damper system, the steering system, and the braking system. The current driving situation is defined by the driver. Two control elements are provided for this purpose. The first control element defines the current road surface.

[0003] A distinction is made, for example, between different modes such as motorway, country road, city driving, snow / ice, grass or sand. The second control element can be used to set the driving mode, which defines the current type of use. For example, a distinction can be made between “Normal”, “Sport” and “Economy”. The characteristics of the above-mentioned subsystems are influenced depending on the respective setting selected. For example, the braking force applied by the driver can be varied using a brake booster. A distinction is made here between a higher brake pedal force with a linear build-up of deceleration, which is desired, for example, for comfortable city driving, and a lower brake pedal force with a dynamic response, which is advantageous on winding country roads.If a sporty driving style were to be set in addition, the necessary brake pedal force could be combined with an even more pronounced response.

[0004] German Patent Application DE 10 2011 001 365 A1 describes a braking system with a variable force-displacement pedal characteristic curve. This characteristic curve is modified by a control device operated by the driver. This device automatically selects the desired characteristic curve from a set of stored curves, depending on the type of brake application.

[0005] DE 10 2013 221 124 A1 discloses a brake control system with an electronic control unit, a brake pedal, which, when actuated, allows the driver to specify a braking command in the form of a pedal travel and / or a pilot pressure and / or a pedal force, and auxiliary brake circuit components that can be controlled independently of the brake pedal for adjusting pressure values ​​in the wheel brake cylinders of a motor vehicle wheel. The brake pedal characteristics can be variably specified depending on defined conditions.

[0006] DE 10 2012 215 627 A1 discloses a braking system for motor vehicles, which can be controlled in a "brake-by-wire" operating mode both by the driver and independently of the driver, comprising a master brake cylinder actuated by means of a brake pedal, having at least one piston and at least one pressure chamber, to which a brake circuit with wheel brakes is connected, an electrically controllable pressure supply device for actuating the wheel brakes, and a simulation device having at least one elastic element, which in the "brake-by-wire" operating mode provides the driver with a pleasant brake pedal feel, wherein the simulation device comprises a hydraulic simulator chamber, which is hydraulically connected to the pressure chamber of the master brake cylinder via a first hydraulic connection and which is separably connected to a pressure fluid reservoir at atmospheric pressure by means of an electrically actuated isolating valve,wherein a media separating means is arranged in the connection between the simulator chamber and the isolation valve.,

[0007] DE 10 2011 077 354 A1 discloses a motor vehicle with a brake force generator for a hydraulic brake system, in which a force application device, in particular amplified by a servo device, displaces a brake piston displaceably guided in a master brake cylinder housing to generate brake pressure in a master brake cylinder. The brake piston is designed to be at least split in two in its displacement direction. Alternative brake force generation options are available, allowing the braking characteristics of the wheel brakes to be varied, in particular depending on the driving condition of the motor vehicle.

[0008] The invention is based on the object of creating an even further enhanced driving experience based on the aforementioned and known systems.

[0009] According to the invention, this object is achieved by the features of the independent claims, while preferred developments of the invention are specified in the dependent claims.

[0010] The invention relates to a braking system with an electronic control unit or an electronic control unit for a braking system and a software function module for an electronic control unit for a braking system. The braking system according to the invention comprises a brake pedal whose pedal travel and / or pedal force can be detected by the control unit. The control unit is designed such that one of several predetermined brake pedal characteristics can be activated manually or automatically. These brake pedal characteristics can be specified via vehicle deceleration-brake pedal travel characteristic curves and are defined at least in defined sections between a first extreme with a comparatively short pedal travel at a comparatively high deceleration and a second extreme with a comparatively long pedal travel at a comparatively low deceleration.

[0011] According to the invention, a brake pedal is used that can provide an individually adjustable brake pedal feel. The adjustment of the brake pedal characteristics is primarily achieved via a vehicle deceleration-brake pedal travel characteristic curve and / or, analogously, a vehicle deceleration-brake pedal force characteristic curve. When adjusting the brake pedal characteristics, a distinction is generally made between the two extremes of short pedal travel and high deceleration, and long pedal travel and low deceleration. In addition, the assignment of pedal force to pedal travel can be varied, particularly in brake-by-wire braking systems.

[0012] Analogous to the vehicle deceleration, the wheel brake pressure or the brake line pressure or any other proportional value can also be used.

[0013] Setting a comparatively short pedal travel with comparatively high pedal force and / or deceleration results in a comparatively sporty brake pedal feel. The following parameters, in particular, define this brake pedal feel or characteristic: - pronounced pressure point - predominantly power-dosed - comparatively short response time - pronounced indentation - comparatively high dynamics

[0014] Setting a comparatively long pedal travel with comparatively low pedal force and / or deceleration results in a comparatively comfortable brake pedal feel. The following parameters, in particular, define this brake pedal feel or characteristic: - soft pressure point - mainly dosed away - better dosing in the low deceleration range - lower acoustics - comparatively muted response

[0015] In vehicle brakes, the pressure point is defined as the point on the pedal travel at which the pedal position correlates with the driver's desired deceleration.

[0016] The brake pedal characteristic curve and thus the brake pedal characteristics can be varied within these extremes. This variation makes it possible to adapt the braking feel to different vehicle classes and vehicle characteristics. A particularly advantageous feature is that one or more additional variants can be offered within a vehicle class. Likewise, the previously known function of the driving experience switch can be expanded to include such adjustability or selection of the brake pedal characteristics. As described in the aforementioned previously published document, various active systems in the vehicle can be adapted to change the vehicle characteristics and thus offer the driver different driving experiences. As an extension of these systems, the brake pedal characteristics should also be adapted to the driver's wishes.The vehicle's characteristics can be adjusted via a switch in the interior, which is operated by the driver. This switch can be used to distinguish between sporty, comfortable, or economical driving modes, for example. In an advantageous further development or alternative, the brake pedal characteristics are automatically adjusted depending on the given driving situation, for example, depending on the location, which can be determined using the navigation system.

[0017] Additionally, a brake pedal characteristic can also be activated in a special "off-road" driving situation. This can be manually selected by the driver or automatically detected and activated based on corresponding sensor data. An "off-road" brake pedal characteristic preferably enables extremely sensitive, particularly distance- and force-controlled braking on rough terrain, especially at low vehicle speeds and with little deceleration. Automatic detection, if necessary, can also be implemented via the navigation system, for example.

[0018] According to the invention, a so-called "chauffeur" mode can also be activated manually via a button or automatically, for example, through seat occupancy detection for the front passenger and / or rear seats. This can provide a more sporty brake pedal feel, for example, at higher decelerations when the driver is traveling alone, while at the same time providing a smooth, comfortable response for passengers at lower decelerations.

[0019] According to the invention, a so-called "creak" prevention mode can be automatically activated, which, for the benefit of acoustics, implements a comparatively significant deceleration change at least for a predetermined number of braking operations and / or at outside temperatures below a predetermined, comparatively low threshold (approximately 10°C) and / or during a comparatively long standstill period (e.g., over 24 hours), preferably during braking before a standstill and / or on a constant downhill gradient with only a slight change in the brake pedal force. This function is preferably used only in a lower deceleration range.

[0020] The invention results in an increased perception of the vehicle characteristics through the adjustable brake pedal feel.

[0021] The drawing illustrates exemplary embodiments of the invention, which are described in more detail below. It shows Fig. 1 schematically shows an overview of the most important components of the braking system according to the invention, Fig. 2 a set of possible first brake pedal characteristics (K1) in the form of vehicle deceleration-brake pedal travel characteristics (deceleration is directly proportional to the brake pressure) and Fig. 3 a family of possible second brake pedal characteristics (K2) in the form of brake pedal force-brake pedal travel characteristics.

[0022] The different brake pedal characteristics K1 and K2 can be used alternatively or superimposed to determine the brake pedal feel (Ci, here with i=1, 2, 3, 4, 5).

[0023] In Fig. Figure 1 schematically shows an electronic control unit 1 of a conventional or brake-by-wire braking system (not shown in detail). The control unit 1 can be connected to a display / operating unit 2 that can be adjusted by the driver. Using this display / operating unit 2 or manually operated buttons, the driver can select a brake pedal characteristic provided in the control unit 1. In the illustrated embodiment, these are: C1: a comfort mode C2: a sport mode C3: a chauffeur mode and C4: an off-road mode

[0024] These four modes could also be activated automatically by control unit 1 depending on recorded input data. In addition, there is a brake pedal characteristic C5, in this case a "creak" prevention mode, which can preferably only be activated automatically. This is intended in particular to prevent acoustic disturbances that can occur depending on various parameters such as the type of rim and moisture, standstill time, outside temperature, and low speed. Mode C5 is automatically activated at least when moisture is expected. Moisture can be suspected if the standstill time of a parked vehicle is greater than a first predetermined threshold and the outside temperature is below a second predetermined, comparatively low threshold. In this case, mode C5 can be activated, at least for a certain number of braking applications.

[0025] The modes C1 to C5 are each controlled by a brake pedal characteristic curve from the family of brake pedal characteristics K1 according to Fig. 2 and / or via a brake pedal characteristic curve from the family of brake pedal characteristics K2 according to Fig. 3 determined.

[0026] Fig. Figure 2 shows a set of brake pedal characteristic curves K1 for determining a corresponding brake feel or a corresponding brake pedal characteristic for the characteristics C1 to C5 that can be selected and activated here in the form of deceleration (or wheel brake pressure) brake pedal travel curves. The brake pedal travel s is shown on the x-axis. Pedal and on the y-axis is the wheel brake pressure p B , which is proportional to the delay a.

[0027] The characteristic curve for mode C1 from K1 is characterized by a comparatively medium-length brake pedal travel s Pedal at medium delay a.

[0028] The characteristic curve for mode C2 from K1 is characterized by a comparatively short brake pedal travel s Pedal at high deceleration a.

[0029] The characteristic curve for mode C3 from K1 is characterized by a comparatively long brake pedal travel s Pedal in the lower deceleration range and by a medium-long brake pedal travel s Pedal in the upper delay range.

[0030] The characteristic curve for mode C4 from K1 is characterized by a comparatively long brake pedal travel s Pedal in the lower deceleration range. In off-road operation, a large deceleration a is not expected; rather, very precise control is required here.

[0031] The characteristic curve for mode C5 from K1 is, as already indicated above, characterized by a strong deceleration a in the lower deceleration range with a comparatively short brake pedal travel s Pedal characterized.

[0032] Fig.Figure 3 shows a set of brake pedal characteristic curves K2 for determining a corresponding braking feel or a corresponding brake pedal characteristic for the characteristics C1 to C5 that can be selected and activated here in the form of brake pedal force-pedal travel curves. The brake pedal travel s is shown on the x-axis. Pedal and on the y-axis the brake pedal force F Pedal applied.

[0033] The modes C1, C3 and C5 can be assigned a characteristic curve with a rather long pedal travel. Pedal and low pedal force F Pedal The modes C2 and C5 can be assigned a characteristic curve with a rather short pedal travel s Pedal and high pedal force F Pedal be assigned.

[0034] The pedal force-pedal travel characteristics from K2 and the deceleration-pedal travel characteristics from K1 can be used alternatively or superimposed.

Claims

[1] Braking system with an electronic control unit (1) and with a brake pedal, the pedal travel (s Pedal ) and / or pedal force (F Pedal ) can be detected by the control unit (1), wherein the control unit (1) is designed such that, depending on manually or automatically generated parameters, one brake pedal characteristic from a plurality of predetermined brake pedal characteristics (C1 to C5) can be activated, wherein the brake pedal characteristics (C1 to C5) can be predetermined via vehicle deceleration-brake pedal travel characteristics (K1) and at least in defined sections between a first extreme with a comparatively short pedal travel (s Pedal ) with a comparatively high deceleration (a) and a second extremum with a comparatively long pedal travel (s pedal ) at a comparatively low delay (a), • where a special driving situation, “Chauffeur” mode, which can be selected manually or automatically detected via the seat occupancy and in which at least one passenger is detected, a corresponding “Chauffeur” brake pedal characteristic (C3) can be activated, • and / or wherein, in the case of a special driving situation which can only be recognised automatically, a corresponding “creaking prevention” brake pedal characteristic (C5) can be activated, by means of which a comparatively high deceleration change can be carried out for a predetermined number of braking operations when a risk of brake disc moisture is detected, only in a lower deceleration range with only a small change in the brake pedal force. [2] Braking system according to claim 1, characterized by that the vehicle deceleration-brake pedal travel characteristics (K1) can be varied within these extremes. [3] Braking system according to one of the preceding claims, characterized bythat when a special manually selectable or automatically detectable driving situation “Offroad” mode occurs, a corresponding “Offroad” brake pedal characteristic (C4) can be activated. [4] Braking system according to one of the preceding claims, characterized by that the vehicle deceleration-brake pedal travel characteristic curve to the “chauffeur” brake pedal characteristic (C3) is due to a comparatively long brake pedal travel (s Pedal ) in a certain lower deceleration range and by a comparatively short brake pedal travel (s Pedal ) is defined in a certain upper delay range. [5] Braking system according to claim 3, characterized by that the vehicle deceleration-brake pedal travel characteristics (K1) are related to the “off-road” brake pedal characteristic (C4) by a comparatively long brake pedal travel (s Pedal ) is defined in a certain lower delay range. [6] Electronic control unit (1) for a braking system according to one of the preceding claims. [7] Software function module for the electronic control unit (1) of the braking system according to one of the preceding claims.

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