"method for managing the braking of a motor vehicle, and related brake-by-wire braking

Abstract

Method for managing the braking of a motor vehicle, equipped with a brake-by- wire braking system including a brake actuation device (1) configured to move along a direction of actuation and release, wherein the vehicle deceleration depends on: - the stroke of the actuation device (1), if a vehicle deceleration lower than a determined value of deceleration corresponding to a condition of low deceleration is requested, and - the force exerted by the driver on the actuation device (1), if a vehicle deceleration higher than said determined value of deceleration is requested.

Description

[0001] DE SCRIPTION of the industrial invention titled:

[0002] "Method for managing the braking of a motor vehicle, and related brake-by-wire braking system", by: Stellantis Europe S.p.A., Italian nationality, corso Giovanni Agnelli 200, 10135 Turin. Designated inventor: IELUZZI Michele.

[0003] Filed on:

[0004] ****

[0005] TEXT OF THE DESCRIPTION

[0006] Field of the invention

[0007] The present invention relates to a method for managing the braking of a motor vehicle, equipped with a brake-by-wire braking system comprising:

[0008] - a brake actuation device configured to move along a direction of actuation and release,

[0009] -at least one stroke sensor configured to detect an input signal related to a stroke value of the brake actuation device, and generate a corresponding signal.

[0010] Prior art

[0011] As known, brake-by-wire systems involve a brake actuation device - typically a brake pedal - electrically connected to the rest of the braking system, eliminating mechanical and / or hydraulic connections between the actuation device and the braking devices associated with the wheels. This means that the action exerted by the driver on the pedal is transformed into an electrical signal processed by an onboard electronic unit that sends corresponding control signals to the braking devices.

[0012] According to a known solution, the actuation device is a brake pedal, commonly referred to as "e-brake pedal", which has a general configuration substantially similar to traditional hydraulic systems. In such solutions, the pedal is connected at the top to a part of the vehicle frame, to ensure a total stroke of about 140 mm. The aforementioned e- brake pedal can be defined as "stroke-based", as it is configured to achieve vehicle deceleration based on pedal stroke.

[0013] Other brake actuation device solutions can be defined as "force-based", as they are configured to achieve vehicle deceleration based on the force exerted by the driver on the actuation device.

[0014] In this perspective, the present invention stems from the desire to propose a brake- by-wire braking system for motor vehicles, which is particularly advantageous, both from the point of view of operational reliability and in terms of meeting the preferences of drivers accustomed to traditional hydraulic braking systems.

[0015] Object and summary of the invention

[0016] One or more embodiments aim to meet the needs outlined above.

[0017] A further object is to realize a brake-by-wire braking system that is relatively simple to implement and with sustainable costs for mass production.

[0018] According to the solutions described herein, such objects are achieved thanks to a system having the features referred to in the following claims.

[0019] The solutions described herein may also concern a corresponding vehicle.

[0020] The claims form an integral part of the teachings provided herein in relation to the embodiments of the solutions described. Brief description of the accompanying figures

[0021] One or more embodiments will now be described, by way of non-limiting example, with reference to the accompanying drawings, in which:

[0022] - Figure l is a perspective view of a brake actuation device of a brake-by-wire braking system for a motor vehicle, according to possible embodiments,

[0023] - Figure 2 is a schematic view illustrating the operation of a brake actuation device, according to possible embodiments, and

[0024] - Figure 3 illustrates a diagram representing aspects of the invention, in which the operation of the braking system is illustrated, according to possible embodiments.

[0025] Detailed description of multiple embodiments

[0026] In the following description, various specific details are illustrated to provide a thorough understanding of various examples of embodiments according to the description.

[0027] The embodiments can be obtained without one or more of the specific details, or with other methods, components, materials, etc.

[0028] In other cases, known structures, materials, or operations are not illustrated or described in detail so that the various aspects of the embodiments are not obscured.

[0029] A reference to "an embodiment" or "a solution" within the context of this description indicates that a particular configuration, structure, or feature described in relation to the embodiment is included in at least one embodiment or solution.

[0030] Phrases such as "in an embodiment" or "in a solution" that may be present at various points in this description do not necessarily refer to the exact same embodiment or solutions.

[0031] Furthermore, particular configurations, structures, or features may be combined in any suitable manner in one or more embodiments or solutions.

[0032] The references used herein are provided simply for convenience and therefore do not define the scope of protection or the extent of the embodiments.

[0033] Furthermore, in the various figures, similar references are used to indicate analogous parts or elements, without repeating the related description for each figure for the sake of brevity.

[0034] As a general premise, the features of the invention will be illustrated with reference to a brake-by-wire braking system for a motor vehicle, comprising a brake actuation device 1, for example a pedal or a lever or a button, operable by a driver to request vehicle braking.

[0035] In accordance with a technique known per se, the braking systems of the type indicated above may include at least one stroke sensor 2, configured to detect an input signal related to a stroke value of the brake actuation device 1, and generate a corresponding signal sent to an onboard electronic control unit, configured to control the braking devices associated with the vehicle's wheels, based on said signal and a braking development law underlying the system's operation.

[0036] In one or more embodiments, as illustrated in Figures 1,2 the brake actuation device 1 is a button configured to move along a direction of actuation and release. As shown in Figure 1, the button can be positioned like a classic pedal set operable by the driver, in association with an acceleration button 3. Figure 2 is a schematic view illustrating the operation of the brake actuation device 1 in association with other components of the system, in accordance with possible embodiments.

[0037] In one or more embodiments, the brake actuated device 1 is carried by a support structure 4 configured to be connected to a portion of the vehicle floor, in a position similar to that of a traditional pedal set.

[0038] As will become evident from the following description, the operation of the system according to the invention is based on a vehicle deceleration law dependent on both the stroke of the actuation device 1 and the force exerted on the actuation device 1.

[0039] More specifically, the operation of the system is set based on a determined value of vehicle deceleration, corresponding to a condition of low deceleration, in which, the vehicle deceleration law depends on:

[0040] - the stroke of the actuation device 1, if a vehicle deceleration lower than said determined value of deceleration is requested, the force exerted by the driver on the actuation device 1, if a vehicle deceleration higher than said determined value of deceleration is requested.

[0041] In one or more embodiments, said determined value of deceleration is between 0.2 - 0.3 g.

[0042] In one or more embodiments, the determined value of deceleration corresponds to 0.2 g.

[0043] Figure 2 shows, in a purely schematic manner, some features of the system according to the invention, created to achieve the aforementioned vehicle deceleration law.

[0044] As already indicated above, the brake actuated device 1 is carried by a support structure 4, possibly configured to be connected to a portion of the vehicle floor, in a position similar to that of a traditional pedal set.

[0045] In one or more embodiments, the brake actuation device 1 is a reduced stroke device, preferably a button, configured to move along a direction of actuation and release.

[0046] The brake actuation device 1 includes an outer main surface 1’, configured to be pressed by the driver, and an opposite inner main surface 1”, possibly extended inside the support structure 4.

[0047] According to a further feature, the system includes a base wall 5, extended at a distance from the inner main surface 1”, configured to move integrally with the actuation device 1, between a raised position and a lowered position.

[0048] According to a further feature, the system includes at least one stroke sensor 2, configured to detect an input signal related to a stroke value of the actuation device 1, and generate a corresponding signal.

[0049] According to a further feature, the system includes at least one force sensor 6 interposed between the base wall 5 and the inner main surface 1” of the brake actuation device 1 (preferably a button). The force sensor 6 is configured to detect an input signal related to a value of force exerted by the driver on the actuation device 1, and generate a corresponding signal.

[0050] It will therefore be appreciated that the system according to the invention provides for a braking request phase based on a stroke value of the device 1 - "stroke-based" phase - and a braking request phase based on a force value exerted on the device 1 - "forcebased" phase. Still referring to Figure 2, the system includes a feedback element 7 configured to move between an extended condition (illustrated in Figure 2) and a retracted condition. The feedback element 7 is configured to be extended both in a rest condition and in a braking request condition that does not require the activation of an ABS safety system; following a certain activation signal sent when the braking action requires the activation of the ABS system, the feedback element 7 moves to the retracted position.

[0051] Preferably, the feedback element 7 is a magnetic anchor associated with a solenoid predisposed to generate a magnetic field in the presence of electric current and move the anchor to the retracted position.

[0052] In the extended position, illustrated in Figure 2, the feedback element 7 is spaced from the base wall 5 when raised (i.e., when the device 1 is not pressed), allowing for a reduced stroke Cl of the device 1 and the base wall 5 integral with the device 1. In one or more embodiments, the reduced stroke Cl is between 5-10 mm.

[0053] This reduced stroke is available precisely to control a first "stroke based" braking phase, at low deceleration (for example, during vehicle parking maneuvers), corresponding to a request for vehicle deceleration lower than said determined value of deceleration (preferably between 0.2 - 0.3 g).

[0054] During a driver's pressure on the device 1, which requires a vehicle deceleration higher than said determined value of deceleration, once the reduced stroke Cl is completed (as the base wall 5 and the feedback element 7 are in mutual contact), a second "force-based" braking phase is realized to achieve vehicle deceleration based on the force exerted by the driver on the actuation device 1.

[0055] It will therefore be appreciated that in light of the aforementioned features, the system according to the invention is based on a vehicle deceleration law that provides for:

[0056] - a first "stroke based" braking phase, at low deceleration (for example, during vehicle parking maneuvers), corresponding to a request for vehicle deceleration lower than said determined value of deceleration (preferably between 0.2 - 0.3 g),

[0057] - a second "force-based" braking phase aimed at achieving vehicle deceleration based on the force exerted by the driver on the actuation device 1.

[0058] As previously indicated, the feedback element 7 can be moved to the retracted position, when the braking action requires the activation of an ABS system.

[0059] In the retracted position, the device 1 and the base wall 5 can be further lowered (following the pressure exerted by the driver) corresponding to an extra stroke C2 (additional to the reduced stroke Cl).

[0060] In this regard, the system includes a fixed platform 8, possibly spaced within the support structure 4, spaced at a distance from the base wall 5, with the feedback element 7 in the extended position protruding between the base wall 5 and the fixed platform 8. The base wall 5 is elastically connected to the fixed platform 8 by at least one compression-resistant spring 9, which tends to return the base wall 5 to a rest position elevated above the feedback element 7. On the fixed platform 8, a force actuator 10, preferably piezoelectric, can also be positioned, configured to provide haptic feedback to the driver pressing the device 1 during the activation of the ABS system. Under such conditions, the base wall 5 is moved along the entire available stroke (reduced stroke Cl plus additional stroke C2) until it comes into contact with the force actuator.

[0061] In light of the features described above, Figure 3 illustrates a representative diagram of aspects of the invention, in which the operation of the braking system is illustrated, according to possible embodiments. The x-axis indicates the vehicle deceleration, showing a determined value of low deceleration, between 0.2 - 0.3 g, which is discriminant for obtaining vehicle deceleration based on the stroke of the device 1 or the force exerted on the device 1. Also on the x- axis is indicated a value A of deceleration that requires the activation of the ABS system.

[0062] The ordinates show the stroke of the device 1 and the force exerted on the device 1.

[0063] Reference Z indicates a curve representative of the vehicle deceleration law based on a first "stroke based" braking phase (indicated with reference B) and a second "forcebased" braking phase (indicated with reference D).

[0064] In relation to the stroke of the device 1, the diagram shows the reduced stroke Cl and the additional stroke C2 obtained by pressing the device 1 and the consequent activation of the ABS system.

[0065] In relation to the force exerted on the device 1, the diagram shows a minimum force value Fmin and a maximum force value Fmax between which all possible force values exerted on the device 1 during the second "force-based" braking phase are included, without activation of the ABS system.

[0066] Reference E indicates a phase of vehicle deceleration in which haptic feedback is activated to the driver during the activation of the ABS system.

[0067] Of course, the details of realization and the forms of execution can be widely varied with respect to what has been described and illustrated, without thereby departing from the scope of the present invention as defined by the attached claims.

Claims

CLAIMS1. Method for managing the braking of a motor vehicle equipped with a brake-by- wire braking system including a brake actuation device (1) movable along a direction of actuation and release, wherein the vehicle deceleration, during braking, depends on:- a stroke value of the actuation device (1), if a vehicle deceleration lower than a determined value of deceleration corresponding to a condition of low deceleration is requested, and- a force value imparted by the driver on the actuation device (1), if a vehicle deceleration higher than said determined value of deceleration is requested.

2. Method according to claim 1, wherein:- the device (1) is configured to achieve a reduced stroke (Cl) when the driver presses the device (1),- said reduced stroke (Cl) is available to control a first phase of braking based on a determined stroke value,- when an end-of-stroke condition is reached, a second phase of braking is realized to achieve vehicle deceleration based on the force exerted by the driver on the actuation device (1).

3. Method according to claim 1, wherein said determined value of deceleration is between 0.2 - 0.3 g.

4. Method according to claim 1, comprising the phase of activating an extra stroke condition (C2) following a specific activation signal sent when the braking action requires the intervention of an ABS system.

5. Method according to claim 4, comprising the phase of providing haptic feedback to the driver when pressing the device (1) during activation of the ABS system.

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