Patent Description:
The patent application <CIT> relates to a method for detecting a malfunction of a braking system. The patent application <CIT> relates to a booster and a pressure amplifying device provided to perform a brake assist. The patent application <CIT> relates to a brake control system for a motor vehicle that includes a controller operable in response to a braking request signal. The patent application <CIT> relates to a braking device for a vehicle which includes a power fail-safe mechanism which works to create frictional braking force at a wheel of the vehicle in the event of loss of electric power. The patent application <CIT> relates to a vehicle braking system that generates a braking force in a vehicle. The patent application <CIT> relates to a hydraulic brake system that comprises a first actuator for a regeneration coordination brake control and a second actuator for maintaining the stability of a vehicle in a hydraulic pressure passage between a master cylinder and a wheel cylinder. The patent application <CIT> relates to a coordinated brake control system of a hybrid brake system.

The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed subject matter, and explain various principles and advantages of those embodiments.

The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the invention with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

During a brake system failure, the brake system of the vehicle may require extra braking force in order to stop the vehicle within a certain distance. For example, when the brake booster fails, additional brake force may be required from the driver in order to compensate for the lacking brake force. Less braking force may increase the stopping distance of the vehicle. Some vehicles, for example electric and hybrid vehicles, include regenerative braking systems. Additional braking force may be sourced from the regenerative braking system in order to compensate for the braking force lost due to the brake booster failure.

The invention presented herein includes a braking system as defined by independent claim <NUM>. The braking system includes a friction braking system, a regenerative braking system, and an electronic processor. The electronic processor is communicatively coupled to the friction braking system and the regenerative braking system. The electronic processor is configured to receive a driver brake request and determine a brake failure state. The brake failure state indicates a brake failure. In response to determining the brake failure state, the electronic processor applies a braking force based on the driver brake request. The braking force includes a frictional braking force generated by the friction braking system and a regenerative braking force generated by the regenerative braking system.

The invention provides a method for braking a vehicle as defined by independent claim <NUM>. The method includes receiving a driver brake request, the driver brake request including a mechanical braking force and determining a brake failure state, the brake failure state indicating a brake failure. The method further includes, in response to determining the brake failure state, applying a braking force based on the driver brake request. The braking force includes a hydraulic braking force generated by a friction braking system and a regenerative braking force generated by a regenerative braking system.

Before any embodiments are explained in detail, it is to be understood that the examples presented herein are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. Embodiments may be practiced or carried out in various ways.

It should also be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components may be used to implement the embodiments presented herein. In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects may be implemented in software (for example, stored on non-transitory computer-readable medium) executable by one or more processors. As such, it should be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components may be utilized to implement the embodiments presented. For example, "control units" and "controllers" described in the specification can include one or more processors, one or more memory modules including non-transitory computer-readable medium, one or more input/output interfaces, and various connections (for example, a system bus) connecting the components.

For ease of description, each of the example systems presented herein is illustrated with a single exemplar of each of its component parts. Some examples may not describe or illustrate all components of the systems. Other embodiments may include more or fewer of each of the illustrated components, may combine some components, or may include additional or alternative components.

<FIG> is a block diagram of one exemplary embodiment of a braking system <NUM>. The braking system <NUM> is included in a vehicle <NUM>. In the example illustrated, the braking system <NUM> includes an electronic controller <NUM>, an input/output (I/O) interface <NUM>, a regenerative braking system <NUM>, a friction braking system <NUM>, and other vehicle systems <NUM>. The vehicle <NUM> further includes a front axle <NUM>, a rear axle <NUM>, a front left wheel <NUM>, a front right wheel <NUM>, a rear left wheel <NUM>, a rear right wheel <NUM>. The front left and right wheels <NUM> and <NUM> are coupled to the front axle <NUM>. Likewise, the rear left and right wheels <NUM> and <NUM> are coupled to the rear axle <NUM>. The electronic controller <NUM>, the regenerative braking system <NUM>, the friction braking system <NUM>, and the other vehicle systems <NUM>, as well as other various modules and components of the vehicle <NUM> are coupled to each other by or through one or more control or data buses (for example, a CAN bus), which enable communication therebetween. The use of control and data buses for the interconnection between and exchange of information among the various modules and components would be apparent to a person skilled in the art in view of the description provided herein.

In some embodiments, the electronic controller <NUM> includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the electronic controller <NUM>. The electronic controller <NUM> includes, among other things, an electronic processor (for example, an electronic microprocessor, microcontroller, or other suitable programmable device), and a memory (not shown). The electronic controller <NUM> is also connected to the input/output interface <NUM>. The electronic processor, the memory, and the input/output interface <NUM>, as well as the other various modules are connected by one or more control or data buses. In some embodiments, the electronic controller <NUM> is implemented partially or entirely in hardware (for example, using a fieldprogrammable gate array ("FPGA"), an application specific integrated circuit ("ASIC"), or other devices.

The memory can include one or more non-transitory computer-readable media, and includes a program storage area and a data storage area. As used in the present application, "non-transitory computer-readable media" comprises all computer-readable media but does not consist of a transitory, propagating signal. The program storage area and the data storage area can include combinations of different types of memory, for example, read-only memory ("ROM"), random access memory ("RAM"), electrically erasable programmable read-only memory ("EEPROM"), flash memory, or other suitable digital memory devices. The electronic processor is connected to the memory and executes software, including firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The electronic processor retrieves from the memory and executes, among other things, instructions related to the control processes and methods described herein. In other embodiments, the electronic controller <NUM> may include additional, fewer, or different components.

The regenerative braking system <NUM> is coupled to an electric motor (e-motor) <NUM>. The regenerative braking system <NUM> is configured to perform regenerative braking during braking maneuvers of the vehicle <NUM>. Specifically, the regenerative braking system <NUM>, during a braking maneuver, causes the e-motor <NUM> to act as a generator and stores or redistributes the power generated by the e-motor <NUM>. The act of generating power creates a braking torque on the e-motor <NUM> that is transmitted to one or more of the wheels <NUM>, <NUM>, <NUM>, and <NUM> that the e-motor <NUM> is coupled to to slow and/or stabalize the vehicle <NUM>. In some embodiments, the regenerative braking system <NUM> include more than one e-motor <NUM> each coupled or connected to at least one of the wheels <NUM>, <NUM>, <NUM>, and <NUM>. For example, one e-motor may be connected to the front left wheel <NUM> and a second e-motor may be connected to the front right wheel <NUM>. It should be understood any number of connections with any number of motors connected to any number of tires is possible in further embodiments.

The friction braking system <NUM> is a braking system that utilizes a frictional braking force to inhibit the motion of one or more of the wheels <NUM>, <NUM>, <NUM>, and <NUM> in order to slow and/or stop the vehicle <NUM>. For example, some or all of the wheels <NUM>, <NUM>, <NUM>, and <NUM> are fitted with brake pads which apply a frictional braking force that inhibits the motion of the wheels <NUM>, <NUM>, <NUM>, and <NUM>. In some embodiments, the friction braking system <NUM> is a conventional hydraulic braking system. The friction braking system <NUM> may include a brake booster <NUM>. The brake booster <NUM> is configured to increase the force the brake pedal <NUM> exerts on the wheel <NUM>, <NUM>, <NUM>, <NUM> of the vehicle <NUM>.

The vehicle <NUM> is a vehicle that includes a regenerative braking system <NUM>, for example a hybrid or electric vehicle. In such an embodiment, the vehicle <NUM> may further include a battery <NUM>. The battery <NUM> provides power to the e-motor <NUM> of the system <NUM>. In some embodiments, the vehicle <NUM> is an autonomous or self-driving car. In other embodiments, the vehicle <NUM> requires human input to drive. In such embodiments, the system <NUM> includes a brake pedal <NUM>. The brake pedal <NUM> may be connected to the friction braking system <NUM>. The vehicle <NUM> may be a two wheel or four wheel drive system.

The other vehicle systems <NUM> include controllers, sensors, actuators, and the like for controlling aspects of the operation of the vehicle <NUM> (for example, acceleration, braking, shifting gears, and the like). The other vehicle systems <NUM> are configured to send and receive data relating to the operation of the vehicle <NUM> to and from the electronic controller <NUM>.

<FIG> is a flowchart of a method <NUM> for the braking system <NUM>. At block <NUM>, the electronic controller <NUM> receives, as illustrated in <FIG>, a driver brake request <NUM>. <FIG> is a block diagram <NUM> illustrating a total braking force <NUM> applied to a wheel (for example, the front left wheel <NUM>) of the braking system <NUM> according to the method <NUM> of <FIG>. As illustrated in <FIG>, the driver brake request <NUM> produces a mechanical force <NUM>. The mechanical force <NUM> is used by the brake booster <NUM> to produce an amplified braking force <NUM>. The amount of amplified braking force <NUM> may be the resultant force from the brake booster <NUM> (<FIG>) in response and/or proportional to the mechanical force <NUM>. The mechanical force <NUM> may be produced by a driver of the vehicle <NUM> that applies force to the brake pedal <NUM>. In other frictional brake systems, the brake pedal is not directly linked to a hydraulic system, but instead is simply an input device where movement of the brake pedal is converted to an electric signal that may be used to generate the driver brake request <NUM> to control the braking system. For example, in some instances the signal may be provided to a hydraulic pump to increase a brake pressure or in other instances the signal is provided to electric motors that cause a caliper to open and close with respect to a brake rotor. In some embodiments, the driver brake request <NUM> is automatically generated by the vehicle <NUM> and the mechanical braking force <NUM> is applied automatically, for example, using an automated braking system (not shown).

Additionally, in response to the driver brake request, the electronic controller <NUM> provides a command <NUM> to the regenerative braking system <NUM> to generate a regenerative braking force <NUM>. Thus, during normal operation of the braking system <NUM>, the total force <NUM> includes the regenerative braking force <NUM> from the regenerative braking system <NUM> and the frictional braking force <NUM> from the frictional braking system <NUM>. During normal operation the frictional braking force <NUM> includes both the mechanical force <NUM> and the amplified braking force <NUM>. However, as explained in more detail below, the frictional braking force <NUM> may include only the mechanical force <NUM> or the amplified braking force <NUM>.

It should be understood that although the total braking force <NUM> and its components are illustrated in <FIG> as being applied to one wheel, it should be understood that the total braking force <NUM> may also refer to overall braking force produced for all the wheels of the vehicle <NUM> and that the frictional braking force <NUM> and the regenerative braking force <NUM> may also refer to the sum of the braking force produced for all the wheels of the vehicle <NUM> by the braking systems <NUM> and <NUM> respectively.

<FIG> illustrates a no brake failure state <NUM>. In a no brake failure state, the regenerative braking system <NUM> produces the regenerative braking force <NUM> and the friction braking system <NUM> produces a frictional braking force <NUM> including both the mechanical force <NUM> and the amplified brake force <NUM>.

Returning to <FIG>, at block <NUM>, the electronic controller <NUM> determines a brake failure state (described in more detail in regard to <FIG>). The brake failure state is a failure in the braking system <NUM>. In some embodiments, the determining the brake failure state may include determining a failure of functionality of the brake booster <NUM>. In response to determining the brake failure state, at block <NUM>, the electronic controller <NUM> applies a braking force <NUM> (see <FIG>) to one or more of the wheels (for example <NUM>, <NUM>, <NUM>, and/or <NUM>) based on the drive brake request <NUM>.

<FIG> each illustrate a different kind of brake failure state. In some embodiments, determining the brake failure state include determining whether the brake failure state is a single brake circuit failure or a brake boost system failure (for example, a failure within the frictional braking system <NUM>). As illustrated in <FIG>, in the case of a brake boost system failure, when the brake failure state is a brake boost system failure state <NUM>, the amplified brake force <NUM> may be unavailable or, if available, may not be of sufficient magnitude to slow the vehicle <NUM>. In this case, the regenerative braking force <NUM> is applied to the tires of a single axle (for example, either the front axle <NUM> or the rear axle <NUM>) of the vehicle <NUM> and the mechanical force <NUM> is applied to all the tires <NUM>, <NUM>,<NUM>, and <NUM>.

In the case of a single brake circuit failure, the frictional braking force <NUM> for one or more of the tires <NUM>, <NUM>, <NUM>, and <NUM> may be unavailable or, if available, may not be of sufficient magnitude to slow the vehicle <NUM>. In such a case, the regenerative braking force <NUM> is applied to a single axle (for example, either the front axle <NUM> or the rear axle <NUM>) while the frictional braking force <NUM> (including both the mechanical braking force <NUM> and the amplified braking force is applied to the tires <NUM>, <NUM>, <NUM>, and <NUM> so long as the single circuit failure has not affected the circuit between the particular tire and the frictional braking system <NUM>. In some embodiments, the friction braking system <NUM> may be a vertical split brake system or a diagonal split system. In a vertical split brake system (also called a front and rear split system), the tires <NUM> and <NUM> on the front axle <NUM> are coupled to one brake circuit while the tires <NUM> and <NUM> are coupled to a second brake circuit. In a diagonal split brake system, the tires <NUM> and <NUM> are coupled to one brake circuit while the tires <NUM> and <NUM> are coupled to a second brake circuit. In either case, a failure in one of the circuits results in a loss of braking force applied on two tires.

As illustrated in <FIG>, when the friction braking system <NUM> is a vertical split brake system (when the brake failure state is a vertical split brake failure state <NUM>), the regenerative braking force <NUM> is applied on a single axle (for example, either the front axle <NUM> or the rear axle <NUM>) of the vehicle <NUM>, compensating for the lost frictional braking force <NUM> on the tires <NUM> and <NUM> due to the failure of the corresponding single braking circuit. The frictional braking force <NUM> resulting from the functional brake circuit (including both the mechanical braking force <NUM> and the amplified braking force <NUM>) is applied to the tires <NUM> and <NUM> on the rear axle <NUM>.

As illustrated in <FIG>, when the friction braking system <NUM> is a diagonal split brake system (when the brake failure state is a diagonal split brake failure state <NUM>), the mechanical force <NUM> is unavailable. The regenerative braking force <NUM> is applied to a single axle (for example, either the front axle <NUM> or the rear axle <NUM>) of the vehicle <NUM> while the frictional force <NUM> (including both the mechanical braking force <NUM> and the amplified braking force <NUM>) is applied to the tires perpendicular to each other depending on the circuit failure (in this case, tires <NUM> and <NUM>).

In some embodiments, the electronic controller <NUM> is further configured to determine a battery capacity of the battery <NUM> of the regenerative braking system <NUM> and apply the regenerative braking force <NUM> when the battery capacity exceeds a predetermined charge level.

Thus, embodiments provide, among other things, a braking system and method for a vehicle in case of a braking failure. Various features and advantages of the invention are set forth in the following claims.

However, one of ordinary skill in the art appreciates that various modifications and changes may be made without departing from the scope of the invention as set forth in the claims below.

The invention is defined solely by the appended claims including any amendments made during the pendency of this application.

Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises," "comprising," "has," "having," "includes," "including," "contains," "containing" or any other variation thereof, are intended to cover a nonexclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises. a," "includes. a," or "contains. a" does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms "a" and "an" are defined as one or more unless explicitly stated otherwise herein. The terms "substantially," "essentially," "approximately," "about" or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within <NUM>%, in another embodiment within <NUM>%, in another embodiment within <NUM>% and in another embodiment within <NUM>%. The term "coupled" as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is "configured" in a certain way is configured in at least that way, but may also be configured in ways that are not listed.

It will be appreciated that some embodiments may be comprised of one or more generic or specialized electronic processors (or "processing devices") such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more electronic processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the method and/or apparatus described herein.

Moreover, an embodiment may be implemented as a computer-readable storage medium having computer readable code stored thereon for programming a computer (for example, comprising an electronic processor) to perform a method as described and claimed herein. Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory) and a Flash memory. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation.

Claim 1:
A braking system for a vehicle comprising:
a friction braking system (<NUM>);
a regenerative braking system (<NUM>); and
an electronic processor communicatively coupled to the friction braking system (<NUM>) and the regenerative braking system (<NUM>), the electronic processor configured to:
receive a driver brake request;
determine a brake failure state, the brake failure state indicating a brake failure; and
in response to determining the brake failure state, apply a braking force based on the driver brake request, wherein a total braking force applied to a plurality of wheels includes a ratio of the regenerative braking force and of the frictional braking force, the ratio being determined based on a type of brake failure, wherein the regenerative braking system (<NUM>) includes more than one e-motor (<NUM>) each coupled or connected to at least one of the wheels (<NUM>, <NUM>, <NUM>, <NUM>) of the vehicle, wherein in the case of a brake boost system failure, the regenerative braking force (<NUM>) is applied to the wheels of a single axle of the vehicle (<NUM>) and a mechanical force (<NUM>) is applied to all the wheels (<NUM>, <NUM>,<NUM>, <NUM>), and wherein in the case of a single brake circuit failure the regenerative braking force (<NUM>) is applied to a single axle while the frictional braking force (<NUM>) is applied to all the wheels (<NUM>, <NUM>, <NUM>, <NUM>), wherein the frictional braking force (<NUM>) includes both the mechanical braking force (<NUM>) and an amplified braking force.