Brake-by-wire system for a vehicle with an adjustable brake pedal simulation assembly
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- GM GLOBAL TECHNOLOGY OPERATIONS LLC
- Filing Date
- 2017-06-23
- Publication Date
- 2026-07-23
AI Technical Summary
Conventional brake systems fail to tailor the 'brake feel' to a driver's preferences and simulate the resistance experienced in traditional hydraulic braking systems, limiting customization and compatibility with brake-by-wire systems.
A brake pedal simulation assembly with an adjustment mechanism that adjusts the axial translation and firmness of the brake pedal, incorporating a damping device and force induction mechanism to mimic traditional braking sensations, allowing customization through a human-machine interface.
Enables personalized brake pedal firmness adjustment and simulates conventional braking sensations, enhancing driver experience while ensuring compatibility with brake-by-wire systems, and providing automated alerts for vehicle conditions.
Smart Images
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Abstract
Description
AREA OF INVENTION
[0001] The subject matter of the invention relates to a brake-by-wire (BBW) system for a vehicle and in particular an adjustable brake pedal simulation assembly of the BBW system. BACKGROUND
[0002] Conventional automotive braking systems typically rely on hydraulics, activated when the driver presses the brake pedal, which usually actuates a master cylinder. The master cylinder, in turn, pressurizes the hydraulic fluid in various hydraulic lines that lead to corresponding actuators on the brakes located next to each wheel. Such a hydraulic braking system can be augmented by a hydraulic modulator assembly, which supports anti-lock braking systems (ABS), traction control (TCS), and systems for enhanced vehicle stability. The wheel brakes are primarily operated by the manually actuated master cylinder, while supplementary pressure gradients for ABS, traction control, and stability enhancement are provided by the hydraulic modulator assembly.
[0003] When the driver presses the brake pedal, which in turn actuates a piston in the master cylinder to activate the wheel brakes, they encounter pedal resistance. This resistance is caused by a combination of factors, such as the actual braking forces at the wheels, hydraulic pressure, mechanical resistance in the brake booster / master cylinder, the force of a return spring acting on the brake pedal, and others. Therefore, a driver becomes accustomed to this feeling of resistance as a normal occurrence while driving. Unfortunately, the feel of conventional brake pedals cannot be adjusted to a driver's preferences.
[0004] Recent advances in braking technology include brake-by-wire (BBW) systems, which actuate the vehicle's braking system via an electrical signal, typically triggered by an onboard controller. Braking force or torque can be applied to the wheel brakes without a direct hydraulic connection to the brake pedal. The BBW system can be used as a supplementary system (i.e., replacing part of the more conventional hydraulic braking system) or can replace a hydraulic braking system entirely (i.e., a pure BBW system). In either case, the "brake feel" to which the driver is accustomed must be replicated or simulated.
[0005] Accordingly, it is desirable to provide a brake pedal simulator that mimics the "braking feel" of a more conventional braking system while also being compatible with a way to adjust a driver's "braking feel". SUMMARY OF THE INVENTION
[0006] In an exemplary embodiment of the invention, a brake pedal assembly of a brake pedal-by-wire (BBW) system comprises a support structure, a brake pedal rotatably mounted on the support structure at a first axis of rotation, and a brake pedal simulation assembly. The brake pedal simulation assembly extends between the brake pedal and the support structure and is rotatably mounted at the corresponding second and third axes of rotation. The brake pedal simulation assembly includes a brake pedal simulator and an adjustment mechanism along a centerline intersecting the second and third axes of rotation. The brake pedal simulation assembly is designed and arranged to displace axially when the brake pedal is actuated, and the adjustment mechanism is designed and arranged to adjust this axial displacement.
[0007] In a further exemplary embodiment of the invention, a brake pedal simulation (BPS) system for a vehicle comprises a support structure, a brake pedal rotatably mounted to the support structure on a first axis of rotation, and a brake pedal simulation assembly rotatably mounted to the brake pedal on a second axis. An adjustment mechanism of the BPS system is operationally connected to the brake pedal simulator and rotatably mounted to the support structure on a third axis of rotation. The adjustment mechanism is configured to set a permissible displacement of the brake pedal simulator for adjusting the brake pedal stiffness.
[0008] In a further embodiment of the invention, a method for operating a BBW system includes the detection of a condition by a computer-based control system. As soon as the condition is detected, an adjustment mechanism of a brake pedal simulation assembly is initiated to change the brake pedal stiffness and thereby alert the driver to the condition.
[0009] The aforementioned features and advantages, as well as further features and advantages of the invention, are readily apparent from the following detailed description of the invention in conjunction with the associated drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Other features, advantages and details appear only as examples in the following detailed description of the embodiments and the detailed description which refers to the following drawings:
[0011] Fig. Figure 1 is a schematic top view of a vehicle with a BBW system as a non-limiting example in accordance with the present invention;
[0012] Fig. Figure 2 is a schematic view of a brake pedal simulator assembly of the BBW system;
[0013] Fig. Figure 3 is a schematic view of a brake pedal simulator within the brake pedal simulator assembly;
[0014] Fig. Figure 4 is a schematic view of the BBW system;
[0015] Fig. Figure 5 is a diagram of a force profile of a force application device of the BBW system as a function of the brake pedal travel;
[0016] Fig. Figure 6 is a diagram of a damping coefficient profile of a damping device of the BBW system as a function of the brake pedal travel; and
[0017] Fig. Figure 7 is a flowchart for a procedure for operating the BBW system. DESCRIPTION OF THE EXECUTION FORMS
[0018] The following description is merely exemplary and is not intended to limit the present disclosure in its applications or uses. It should be noted that in all drawings, the same reference numerals refer to the same or corresponding parts and features. The terms "module" and "controller" as used herein refer to a processing circuit that may include an application-specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or grouped), and memory executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components providing the described functionality.
[0019] According to one embodiment of the invention Fig. 1. A schematic view of a vehicle 20, which is a drivetrain 22 (i.e., engine, transmission and differential), several rotating wheels 24 (i.e., four depicted) and a braking system 26 This may include a BBW system, but this is to be understood as a non-limiting example. The BBW system 26 can a brake assembly 28 per wheel 24 , a brake pedal assembly 30 and a control system 32 include powertrain 22 is set up so that at least one of the wheels 24 is powered so that the vehicle 20 is moved on a surface (e.g., road). The BBW system 26 is configured to generally determine the speed of the vehicle 20 slows down and / or stops the vehicle's movement. 20can be a car, a truck, a van, an SUV or any other self-propelled or towed conveying device suitable for transporting a load.
[0020] Each brake assembly 28 of the BBW system 26 can a brake 34 and an actuator 36 include, configured to actuate the brake. The brake 34 It can include a brake caliper and be any type of brake, including disc brakes, drum brakes, and others. As a non-restrictive example, the actuator could be... 36 an electro-hydraulic brake actuator (EHBA) or another actuator that controls the brake 34 can be operated using an electrical input signal that it receives from the controller. 32 receives. More precisely, the actuator can 36any type of motor that responds to a received electrical signal and converts energy into motion, which acts as a brake. 34 controls the actuator. 36 a DC motor configured to generate electro-hydraulic pressure, which is supplied, for example, to the brake calipers of the brake. 34 is being managed.
[0021] The control 32 It can include a computer-based processor (e.g., a microprocessor) and a computer-readable and writable storage medium. During operation, the control system can... 32 one or more electrical signals from the brake pedal assembly 30 via a path (see arrow) 38 ) are obtained, from which the driver's braking intention can be inferred. The control 32 It can, in turn, process such signals and, at least partially based on these signals, generate an electrical control signal via a path (see arrow).40 ) to the actuators 36 Output. Depending on the different vehicle conditions, the command signals for each wheel can be displayed. 24 they may be the same, or they can be for each wheel 24 Different signals are output. The paths 38 , 40 These can be wired or wireless paths, or a combination of both.
[0022] Non-restrictive examples of control 32 They can include an arithmetic processing unit and logical operations, an electronic control module that queries, decodes, and executes instructions from memory, and a module unit that uses multiple parallel processing elements. Other examples of control 32 They may include an engine control unit and an application-specific integrated circuit. It is further intended and expected that the control system will... 32may include redundant controls, and / or the system may include other redundancies to improve the reliability of the BBW system. 26 to improve.
[0023] With reference to Fig. 2. The brake pedal assembly 30 the braking system 26 a brake pedal 42 include, which is configured to be operated by a driver to control the brake assemblies 28 to activate, as well as a brake pedal simulation module 41 , which is set up to provide and simulate a conventional "braking feel" for the driver. The brake pedal 42 can be supported by a permanently installed or stationary support structure 46 are supported and are in a movable relationship with it. As a non-restrictive example, consider the brake pedal. 42 rotatable with the fixed structure 46 about a first axis of rotation 48be connected around it. The brake pedal simulation assembly 41 runs between the brake pedal 42 and the supporting structure 46 on the second axis of rotation 50 and third axis of rotation 52 The axes of rotation 48 , 50 , 52 They can essentially run parallel to each other and at a distance from each other.
[0024] The brake pedal simulation assembly 41 can have an adjustment mechanism 43 and a brake pedal simulator 44 include, generally aligned along a centerline C, which defines the second and third axes of rotation 50 , 52 cuts. The adjustment mechanism 43 is set up to adjust the "firmness" of the "brake feeling" and can switch between the stationary structure 46 on the third axis of rotation 52 and the brake pedal simulator 44 The brake pedal simulator. 44It is set up to simulate the braking behavior or "brake feel" of a more conventional hydraulic brake system. It can be set using the adjustment mechanism. 43 and the brake pedal 42 on the second axis of rotation 50 get lost.
[0025] With reference to Fig. 2 and Fig. 3 is the brake pedal simulator 44 the brake pedal simulator assembly 41 It is configured to simulate the behavior and / or "feel" of a more conventional hydraulic braking system. It can incorporate a damping device. 54 , a force induction device 56 , a connecting element 58 and a case 60 include the damping device. 54 It is designed and arranged in such a way that it generally produces a damping force which is a function of the speed at which a driver applies the brake pedal. 42 actuated. The force induction device 56It generates an induced force (e.g., spring force) that is a function of the brake pedal travel. The connecting element can be attached to an end section. 58 directly with the brake pedal 42 on the second axis of rotation 50 be rotatably connected. An opposite end section 62 of the connecting element 58 can be enlarged and applied directly to the damping and force induction devices 54 , 56 act. The force induction device 56 This can also include returning the brake pedal. 42 to ease the braking process after the driver has applied and released the brake pedal.
[0026] The case 60 of the brake pedal simulator 44 can a base plate 64 , a stop or a top plate 66 and a wall 68 include those connected to the base plate 64 and the attack 66is connected and runs axially between them. The base plate 62 of the brake pedal simulator 44 can be axially opposite the enlarged end section 62 of the connecting element 58 lie. The damping and force induction devices 54 , 56 are axially between the base plate 62 and the enlarged end section 62 of the connecting element 58 arranged to perform axial compression when the brake pedal is pressed 42 is operated by a driver. The enlarged end section 62 is axially between the stop 66 of the case 60 and the devices 54 , 56 arranged. If the devices 54 , 56 are fully axially extended (i.e., the brake pedal) 42 (is in a non-activated state), the enlarged head area 62 against the attack 66of the case 60 be pre-tensioned, for example, by an axial force applied by the force induction device 56 is exercised. The wall 68 can be continuous around the center line C, and thus one or both of the devices 54 , 56 wrap and encapsulate. Alternatively, the devices can 54 , 56 their own housings, and the wall 68 It can generally work by having the base plate 64 constantly from the counterattack 66 axially spaced. The stop or upper plate 66 Generally, one or both devices can be used. 54 , 56 cover and can create an opening 70 contained through which the connecting element 58 runs (i.e. in a moving and sealable relationship with the upper plate) 66It is intended and assumed that the spring and the damping device can also be housed in a coaxial manner and in a single casing.
[0027] An example of the force induction device 56 can be an elastically compressible, coiled spring (as shown), with opposite ends attached to the opposite base plate 64 and the attack 66 of the case 60 lies. Other, non-limiting examples of a force induction device 56 These include an elastomeric foam, a wave spring, and any other device for generating a variable force in general, as a function of the brake pedal travel. An example of a damping device is... 54It can be a hydraulic cylinder with at least one internal opening for the flow and exchange of hydraulic fluid between chambers. Such a damping device (and others) can be designed to exert a constant force when a constant velocity is applied to the brake pedal throughout its travel. An example of such a damping device 54 A hydraulic cylinder with a single orifice can operate with constant force. Another non-restrictive example of a damping device is... 54 can be a device designed to apply a force as the pedal travel increases and when the brake pedal is pressed 42 to increase the damping force when the brake pedal is applied at a constant speed. Such variable-force damping devices can be passive and depend solely on the position and / or displacement of the brake pedal, or they can be active and controlled by the vehicle's electronics. 32be controlled. An example of a damping device with passive variable force might include a hydraulic cylinder with multiple perforations that are individually exposed depending on the brake pedal position. Other non-restrictive examples of a damping device 54 These devices may include a friction damper, an active ball screw driven by a controller that also detects pedal position and speed (i.e., the ball screw acts as a damping device), and generally any other device for generating a variable force as a function of pedal actuation speed. Although shown parallel (i.e., side by side) to each other, it is further conceivable and to be assumed that the orientation of the devices 54 , 56 can take many different forms in relation to each other. The devices 54 , 56 They can, for example, lie concentrically around a common midline C.
[0028] The adjustment mechanism 43 the brake pedal simulator assembly 41 It is configured to adjust the firmness of the "brake feel" to the driver's preference. The firmness setting can be considered an indirect adjustment of the force induction device's effect. 56 to be understood. The adjustment mechanism 43 It can be a ball screw and can have a base body 72 , an electric motor 74 , a threaded rod 76 and a sled 78 including, which may contain a female thread. The base body 72 can be directly swivelled with the support structure 46 on the third axis of rotation 52 be connected. The electric motor 74 can through the base body 72 be supported and connected to it. The threaded rod 76 is operational with the electric motor 74connected, for rotation about an axis of rotation (not shown) that can coincide with the center line C. The sled 78 is applied to the threaded rod 76 screwed, for axial movement with respect to the axis of rotation (i.e. centerline C), when the electric motor 74 the threaded rod 76 turns. The sled 78 is mechanical with the brake pedal simulator 44 connected to prevent or limit rotation around the axis of rotation when the threaded rod 76 rotates. More precisely, the sled can 78 rigidly attached to one side of the base plate 64 of the case 60 be attached opposite one side of the base plate 64 , on which the devices are located 54 , 56 condition.
[0029] With reference to Fig. 4 can the brake pedal simulator assembly 41 the brake pedal assembly 30at least one distance sensor 80 include a device configured to control the displacement (e.g., linear, angular, and other) of, for example, the brake pedal. 42 (i.e. near the axis of rotation) 48 ) measures. The brake pedal simulator assembly 41 can still have at least one pressure sensor (i.e. force sensor) 82 include, which is located on one or both sides of the simulator 44 near the axes of rotation 50 , 52 It is suitable for measuring pressure. To optimize system safety, the brake pedal simulator assembly can be used. 41 include more than one distance sensor, attached to various points on the brake pedal assembly 30 Similarly, the brake pedal simulator assembly 41 include more than one pressure sensor (i.e. force sensor), configured to, for example, send redundant signals to more than one controller to optimize sensor robustness.
[0030] The control system is in operation 32 configured to send a displacement signal (see arrow) 84 ) and a pressure signal (see arrow) 86 ) via path 38 and from the respective sensors 80 , 82 to receive when the brake pedal 42 is operated by a driver. The control 32 processes the displacement and pressure signals 84 , 86 and then sends via the path 40 one or more corresponding command signals 88 to the brake actuators 36 the brake assemblies 28 .
[0031] With reference to Fig. 2. The adjustment mechanism can 43 by a driver using a human-machine user interface (HMI) 90 be initiated. The HMI 90It can be configured to provide the driver with the option of a softer or firmer brake feel and can be any type of interface, including buttons and interactive touchscreens. If a driver desires a firmer brake feel while driving, they can adjust it using the HMI. 90 interact, and the HMI 90 A command signal can be sent accordingly (see arrow). 92 ) to the control system 32 send. In response, the control system can 32 an initiation signal (see arrow) 94 ) to the engine 74 send, causing the motor to rotate in a first direction, causing the carriage 78 away from the axis of rotation 52 is moved and thereby reduces a permissible displacement distance that the devices 54 , 56can be moved. By reducing the permissible displacement distance (and increasing the spring preload and changing the position-dependent damping characteristics), the firmness of the brake feel is increased; the brake pedal travel can decrease or generally remain constant. If, on the other hand, a driver desires a softer brake feel while driving, they can adjust this using the HMI. 90 interact, and the HMI 90 A command signal can be sent accordingly (see arrow). 96 ) to the control system 32 send. In response, the control system can 32 an initiation signal (see arrow) 98 ) to the engine 74 send, causing the motor to rotate in the opposite, second direction, causing the carriage 78 in the direction of the axis of rotation 52 is moved, thereby increasing the permissible displacement distance of the devices 54 , 56The permissible displacement is increased (and the spring preload is reduced and the position-dependent damping characteristics are changed). By increasing the permissible displacement (and increasing the spring preload and changing the position-dependent damping characteristics), the firmness of the brake feel is reduced; the brake pedal travel may increase or generally remain constant.
[0032] With reference to Fig. Section 5 will be an example of a force profile of the force induction device. 56 Generally represented as a function of brake pedal travel T, shown in the graph as pedal force F applied by the driver versus brake pedal travel T. The solid arc-shaped or curved line 71 represents the target profile, and the dashed lines 73 represent the outer limits (i.e., the tolerance) of the target profile. The force induction device 56 can be used for all target profiles 71 be laid out.
[0033] With reference to Fig. Figure 6 presents an example of a damping coefficient profile, generally as a function of the brake pedal travel T, shown in the graph as the brake pedal travel T versus a damping coefficient D. The solid arc-shaped or curved line 75 represents the target profile, and the dashed lines 77 These represent the outer limits (i.e., the tolerance) of the target profile. Similar to the force induction device. 56 can the damping device 54 The system is designed to accommodate all target profiles. It is intended and expected that the data for the target force and damping force profiles, along with the predefined target tolerances (i.e., limit values) for various processing functions, will be integrated into the control system. 32can be programmed. Although not explicitly shown, it is further intended and can be assumed that to some extent one or both devices 54 , 56 They can be adjustable, with this adjustability depending on the control system. 32 is done in such a way that, for example, the pre-programmed profiles of the Fig. 5 and Fig. 6. It should also be noted that the damping coefficient D is a function of the pedal position and that the damping force is a function of the pedal actuation rate and the pedal position.
[0034] In addition to providing an adjustable, desired brake feel, the adjustment mechanism can 43 the brake pedal simulator assembly 41be adapted to provide an automated braking feel that warns the driver of various vehicle conditions and / or simulates a braking system failure typically expected in more conventional, hydraulic braking systems. With reference to Fig. 7 will be an operating procedure of the BBW system 26 displayed. For example, and via block. 100 can the system 26 Perform fault monitoring (e.g., faulty brake actuator). Per block 102 can the control 32 , if an error is detected, the adjustment mechanism 43 initiate to preload the simulator 44 to reduce it to a minimum value and thereby create a soft pedal feel.
[0035] Per block 104 can the system 26 If a fault is not detected, check for rotor thickness variation. Per block 106 can the control32 , when a rotor thickness variation is detected, the adjustment mechanism 43 initiate to modulate the motor position at a frequency based on the oscillation frequency of the deceleration.
[0036] Per block 108 can the system 26 If a rotor thickness variation is not detected, monitor for boiling brake fluid (i.e., high temperature and a damaging pressure-volume (PV) curve). Per block 110 can the control 32 , when boiling brake fluid is detected, the adjustment mechanism 43 initiate to preload the simulator 44 to reduce it to a minimum value and thereby create a soft pedal feel.
[0037] Per block 112 can the system 26 If boiling brake fluid is not detected, monitor for active ABS. Per block 114 can the control 32When an active ABS is detected, the adjustment mechanism for modulating the motor position is initiated (i.e., frequency based on the ABS clocking frequency), thereby modulating the brake feel. Other examples that can modulate the motor position include a force based on an estimate of the instantaneous system volume (i.e., pressure) or on the calibrated frequency for haptic pedal feedback.
[0038] Per block 116 can the system 26 If active ABS is not detected, monitor for driver mode changes (e.g., pre-programmed braking feel for specific drivers, etc.). Per block 118 can the control 32 , when a driver mode change is detected, initiate the adjustment mechanism to preload the simulator. 44 for example, setting it to pre-programmed values (e.g. Sport / firm, Tour / soft, etc.).
[0039] It is further planned and to be assumed that the conditions will be incorporated into the control system. 32 can be pre-programmed, and that the system 26 All the pre-programmed conditions described above are monitored in the same and / or a different order than provided. It can also be assumed that the system... 26 It can monitor conditions that are not directly related to the braking system, and yet still the firmness of the brake pedal. 42 can be set to warn the driver of a detected condition.
[0040] Advantages of the present invention include the ability for a driver to select the firmness and aggressiveness of the brake pedal. Further advantages include the ability to relate such selected brake pedal firmness to a brake pedal simulator of a brake-by-wire (BBW) system, which includes the ability to simulate brake pedal damping and other forces similar to a more conventional braking system. Additional advantages may include the ability to warn a motor vehicle driver by automatically changing the brake feel. Furthermore, the present invention enables a compact mechanical component housing, which simplifies the design and physical integration of a pedal module, along with simplifying the diagnosis and maintenance of the module.
[0041] While the invention has been described with reference to exemplary embodiments, those skilled in the field will understand that various modifications can be made and individual parts can be replaced by corresponding other parts without deviating from the scope of the invention. Furthermore, many modifications can be made to adapt a particular material situation to the teachings of the invention without deviating from its essential scope. Therefore, it is intended that the invention is not limited to the disclosed specific embodiments, but also includes all embodiments that fall within the scope of the application.
Claims
[1] Brake pedal assembly comprising the following: a supporting structure; a brake pedal rotatably attached to the support structure on a first axis of rotation; and a brake pedal simulator assembly extending between the brake pedal and the support structure at the respective second and third axes of rotation and rotatably connected to them, the brake pedal simulator assembly comprising a brake pedal simulator and an adjustment mechanism along a centerline intersecting the second and third axes of rotation, wherein the brake pedal simulator is installed and arranged to move axially when the brake pedal is actuated, and the adjustment mechanism is designed and arranged to adjust the axial displacement. [2] Brake pedal assembly according to claim 1, wherein the adjustment mechanism includes a threaded rod which is designed and arranged to rotate about the center line, and a slide is rotatably connected to the threaded rod so that axial movement along the center line is possible and which is connected to the brake pedal simulator. [3] Brake pedal assembly according to claim 2, wherein the adjusting mechanism includes a base element rotatably attached to the support structure on the third axis of rotation, and an electric motor connected to the base element and configured to rotate the threaded rod. [4] Brake pedal assembly according to claim 3, wherein the brake pedal simulator includes a force induction device designed and arranged such that a first force is applied to the brake pedal which varies as a function of the brake pedal travel. [5] Brake pedal assembly according to claim 4, wherein the force induction device is elastically compressed between the slide and a connecting element of the brake pedal simulator assembly, which is connected to the brake pedal at the second axis of rotation. [6] Brake pedal assembly according to claim 5, wherein the force induction device is a compressible wound spring. [7] Brake pedal assembly according to claim 5, wherein the brake pedal simulator includes a damping device designed and arranged such that a second force is applied to the connecting element which varies as a function of the lowest brake pedal speed. [8] Brake pedal assembly according to claim 7, wherein the second force is exerted between the connecting element and the slide. [9] Brake pedal assembly according to claim 8, wherein the damping device is a hydraulic cylinder. [10] Brake pedal assembly according to claim 1, wherein the adjustment mechanism is a ball screw device.