Brake creep chatter countermeasure system and method

Abstract

Methods and systems are provided for controlling braking to avoid chatter noise in a braking system. The system has a brake actuator configured to apply frictional force to a moving member, a piping system coupled with the brake actuator, an inlet valve in the piping system configured to control fluid pressure delivered to the brake actuator, and an outlet valve in the piping system configured to control fluid pressure released from the brake actuator. The system includes a controller to monitor an upper target pressure condition in the braking system, where the upper target pressure condition is associated with a noise zone; and when the upper target pressure is detected and in a noise zone avoidance mode, operating the inlet valve and the outlet valve to avoid brake pressure of brake noise generated by the friction force.

Description

Technical Field

[0001] The present disclosure relates generally to control of brake systems, and more particularly to methods and systems for controlling a vehicle brake system using countermeasures to avoid creating brake creep groan noise. Background Art

[0002] Braking systems are typically included in a mechanical system with moving parts that are preferably slowed and / or brought to a controlled stop when desired. Braking typically involves the use of friction to prevent movement. Depending on the application, a variety of friction material options may be employed. Brake creep judder is the sound produced by braking when pressure is applied between the brake friction pads and mating braking surfaces as the vehicle begins to move from a stopped condition. For example, the sound may be produced by vibrations created when the vehicle moves with the brakes in an applied state, and may be transmitted and amplified by propagation through the vehicle structure. The sound may be undesirable and may be classified as noise. Brake creep judder noise may be perceived by vehicle occupants both audibly and by feel during brake release and / or application.

[0003] The generation of brake creep shudder noise can be detected during vehicle development and can be addressed by changing design parameters such as the friction material used in the brake pads. When the development of a vehicle is at an advanced stage or is complete, it is generally not desirable to change the design parameters.

[0004] Therefore, it is desirable to provide systems and methods for addressing brake creep shudder noise without changing the physical elements of the vehicle. Such systems and methods can be desirably generally applicable to a variety of braking applications. Moreover, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing introduction. Summary of the invention

[0005] A system and method for controlling braking to avoid chatter noise in a brake system is provided. The system may have a brake actuator for applying friction to a moving member, a piping system coupled to the brake actuator, an inlet valve in the piping system for controlling fluid pressure delivered to the brake actuator, and an outlet valve in the piping system for controlling fluid pressure released from the brake actuator. The system includes a controller for monitoring an upper target pressure condition in the brake system, wherein the upper target pressure condition is associated with a noise zone. When the upper target pressure is detected and in a noise zone avoidance mode, the system may operate the inlet valve and the outlet valve to avoid a brake pressure that generates brake noise due to friction.

[0006] In additional embodiments, the controller monitors for a vehicle start event and, after the vehicle start event, monitors for an upper target pressure condition in the system.

[0007] In additional embodiments, the controller counts the number of brake applications after a vehicle start event and skips monitoring of the upper target pressure when the number of brake applications exceeds a threshold.

[0008] In an additional embodiment, the controller determines whether there is a slope that affects the brake noise by means of a slope sensor. When the slope is present and when an upper target pressure is detected, the inlet valve and the outlet valve are controlled in a ramp mode.

[0009] In additional embodiments, the controller determines via the brake apply actuator whether a pressure increase is applied. When the pressure increase is applied, the noise zone avoidance mode is exited.

[0010] In an additional embodiment, the system is included in a vehicle, and the controller determines whether the vehicle is operating on a slope. When the vehicle is not operating on a slope and an upper target pressure is detected, the inlet valve and the outlet valve are controlled in a normal mode. When the vehicle is operating on a slope and an upper target pressure is detected, the inlet valve and the outlet valve are controlled in a slope mode that is different from the normal mode and customized for the slope.

[0011] In additional embodiments, the controller determines whether a lower pressure target is detected and exits the noise zone avoidance mode when the lower pressure target is detected.

[0012] In additional embodiments, the controller determines whether a lower pressure target is detected and continues to operate in the noise zone avoidance mode when the lower pressure target is not detected.

[0013] In an additional embodiment, the system is included in a vehicle, and the controller determines the speed of the vehicle via a speed sensor. When the speed exceeds a threshold, monitoring of the upper target pressure is skipped.

[0014] In additional embodiments, the controller controls the supercharger to adjust the deceleration rate.

[0015] In a number of other embodiments, a method for controlling braking includes applying a friction force to a moving member by a brake actuator. A piping system is coupled to the brake actuator. An inlet valve in the piping system controls a fluid pressure delivered to the brake actuator. An outlet valve in the piping system controls a fluid pressure released from the brake actuator. A controller monitors an upper target pressure condition in the system, wherein the upper target pressure condition is associated with a noise zone. When the upper target pressure is detected, the controller operates in a noise zone avoidance mode, controlling the inlet valve and the outlet valve to avoid a brake pressure that would generate brake noise due to the friction force.

[0016] In additional embodiments, the controller monitors a vehicle start event. After the vehicle start event, the controller monitors an upper target pressure condition in the system.

[0017] In an additional embodiment, the controller counts the number of brake applications after a vehicle start event.When the number of brake applications exceeds a threshold, the controller skips monitoring the upper target pressure.

[0018] In an additional embodiment, the controller references a ramp sensor and determines whether there is a ramp that affects the brake noise. When the ramp is present and when an upper target pressure is detected, the inlet valve and the outlet valve are operated in a ramp mode.

[0019] In additional embodiments, the controller references the brake apply actuator and determines whether a pressure increase is applied. When a pressure increase is applied, the controller exits the noise zone avoidance mode.

[0020] In an additional embodiment, the system is included in a vehicle. The controller determines whether the vehicle is operating on a slope. When the vehicle is not operating on a slope and an upper target pressure is detected, the inlet valve and the outlet valve are controlled in a normal mode. When the vehicle is operating on a slope and an upper target pressure is detected, the inlet valve and the outlet valve are controlled in a slope mode that is different from the normal mode and customized for the slope.

[0021] In additional embodiments, the controller determines whether a lower pressure target is detected and exits the noise zone avoidance mode when the lower pressure target is detected.

[0022] In an additional embodiment, the controller determines whether a lower pressure target is detected. When the lower pressure target is not detected, the controller continues to operate the system in the noise zone avoidance mode.

[0023] In an additional embodiment, the system is included in a vehicle. The controller references the speed sensor and determines the speed of the vehicle. When the speed exceeds a threshold, the controller skips monitoring the upper target pressure.

[0024] In a number of additional embodiments, a vehicle includes a system for controlling braking. The function of a brake actuator is to apply friction to a moving member. A piping system is coupled to the brake actuator. An inlet valve is disposed in the piping system to control a fluid pressure delivered to the brake actuator. An outlet valve is disposed in the piping system to control a fluid pressure released from the brake actuator. A controller monitors an upper target pressure condition in the system. When the upper target pressure is detected, the system is controlled in a noise zone avoidance mode, wherein the inlet valve and the outlet valve are controlled to avoid a brake pressure that would generate brake noise due to friction. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments will be described below with reference to the following drawings, wherein like numerals represent like elements, and wherein:

[0026] Figure 1 is a functional diagram of a vehicle including a braking system and a control system capable of judder control according to an exemplary embodiment;

[0027] Figure 2 is a diagram showing a method according to an exemplary embodiment Figure 1 Functional diagram of the vehicle's braking system;

[0028] Figure 3 According to an exemplary embodiment Figure 1 Vehicles and Figure 2 Pedal force and deceleration versus time for a braking system;

[0029] Figure 4 According to an exemplary embodiment Figure 1 Vehicles and Figure 2 A graph of the brake system pressure and the brake pedal position;

[0030] Figure 5 According to an exemplary embodiment Figure 1 Vehicle and control systems and Figure 2 A flowchart of a process for brake system control in the case of an initial cycle with ignition in conjunction with a brake system of the present invention; and

[0031] Figure 6 According to an exemplary embodiment Figure 1 Vehicle and control systems and Figure 2 Flowchart of a process for braking system control after driving in combination with an engine system. DETAILED DESCRIPTION

[0032] The following detailed description is merely exemplary in nature and is not intended to limit application and use. In addition, there is no intention to be bound by any express or implied theory presented in the aforementioned technical field, background technology, invention content or the following detailed description. As used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic and / or processor device, alone or in any combination, including but not limited to: application-specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated or groups) and memories that execute one or more software or firmware programs, combinational logic circuits and / or other suitable components that provide the described functions.

[0033] Embodiments of the present disclosure may be described herein in terms of functional and / or logical block components and various processing steps. It should be understood that such block components may be implemented by any number of hardware, software, and / or firmware components configured to perform a specified function. For example, embodiments of the present disclosure may employ various integrated circuit components, such as memory elements, digital signal processing elements, logic elements, lookup tables, etc., which may perform various functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any number of systems, and the systems described herein are merely exemplary embodiments of the present disclosure.

[0034] For the sake of brevity, conventional techniques related to other functional aspects of signal processing, data transmission, signaling, control, and systems (and the various operating components of the systems) may not be described in detail herein. In addition, the connecting lines shown in the various figures included herein are intended to represent example functional relationships and / or physical couplings between various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the embodiments of the present disclosure.

[0035] refer to Figure 1 , a vehicle 100 with a powertrain system 102 according to an exemplary embodiment is shown. In various embodiments, the powertrain system 102 includes a prime mover, which can be an engine and / or a motor. Based on a requested load that can be commanded by a driver or by autonomous input for torque and / or speed, the prime mover operates to propel the vehicle 100. In some embodiments, the vehicle 100 includes a car. As will be appreciated, the vehicle 100 can be any of a variety of different types of cars, such as, for example, a sedan, a van, a truck, or a sports utility vehicle (SUV), and in some embodiments can be a two-wheel drive (2WD) (i.e., rear-wheel drive or front-wheel drive), a four-wheel drive (4WD) or an all-wheel drive (AWD) and / or various other types of vehicles. In some embodiments, the vehicle 100 may also include a truck, a boat, an airplane, and / or one or more other types of vehicles. In addition, in various embodiments, it will also be appreciated that the vehicle 100 may include any number of other types of mobile platforms with a propulsion system (such as the powertrain system 102).

[0036] In the depicted embodiment, the vehicle 100 includes a body that substantially surrounds the other components of the vehicle 100. Also in the depicted embodiment, the vehicle 100 includes multiple axles and wheels. The wheels are each rotationally coupled to one or more axles about respective corners of the body, such as through a suspension, to facilitate movement of the vehicle 100. In one embodiment, the vehicle 100 includes four wheels, although this may vary in other embodiments (e.g., for trucks and certain other vehicles).

[0037] The vehicle 100 includes a powertrain system 102 for propelling the vehicle 100. The powertrain system 102 drives the wheels to rotate in a forward direction or a rearward direction. The powertrain system 102 generally includes multiple components and subsystems that operate in coordination to provide power to the vehicle 100, and includes an actuator system 106 to implement various control actions. The vehicle 100 includes a braking system 104 associated with one or more of the wheels, which is configured to apply friction to decelerate the vehicle 100. The braking system 104 includes multiple components and subsystems that operate in coordination to brake the vehicle 100, and includes an actuator system 108 to implement various control actions.

[0038] The vehicle 100 further includes a control system 114 associated with various systems of the vehicle 100, including the powertrain system 102 and the brake system 104. In various embodiments, the control system 114 provides instructions for controlling various aspects of the vehicle 100, including through the actuator systems 106, 108. In various embodiments, the control system 114 includes an engine control unit (ECU) for the powertrain system 102 and an electronic brake control module (EBCM) for the brake system 104. In other embodiments, the control system 114 may include any number of separate controllers. In various embodiments, the control system 114 selectively controls the operation of the actuator systems 106, 108, among other functions. In various embodiments, the control system 114 operates in accordance with the following in combination with the control system 114. Figure 5 and Figure 6 The steps of the method described further provide these functions.

[0039] like Figure 1 As depicted in , in various embodiments, the control system 114 includes a sensor array 110 and a controller 130. In some embodiments, the actuator systems 106, 108 can be considered part of the control system 114. In various embodiments, the sensor array 110 includes sensors for measuring observable conditions (including observable conditions of the powertrain system 102 and the brake system 104) and generating sensor data based thereon. Figure 1, in various embodiments, the sensor array 110 includes one or more prime mover sensors 116. In various embodiments, the prime mover sensor 116 is attached to the powertrain system 102, disposed within the powertrain system, or otherwise disposed near the powertrain system to measure various temperatures, positions, speeds, and other observable parameters. In various embodiments, the sensor array 110 includes one or more brake sensors 118. In various embodiments, the brake sensor 118 is attached to the brake system 104, disposed within the brake system, or otherwise disposed near the brake system to measure various positions, pressures, speeds, and other observable parameters. In certain embodiments, the sensor array 110 may also include one or more other sensors 120, such as for operation of the powertrain system 102, the brake system 104, and / or other systems and devices of the vehicle 100. For example, in some embodiments, the other sensors 120 may include one or more sensors for detecting when the powertrain system 102 is turned on and / or running, one or more load sensors (such as a throttle position sensor) for detecting a load request of the powertrain system 102, one or more wheel speed sensors for detecting wheel speed, and other sensors as desired.

[0040] In various embodiments, the controller 130 is coupled to the sensor array 110 and provides instructions for controlling the powertrain system 102 and / or the brake system 104, such as via commands based on the sensor data through the actuator systems 106, 108. Figure 1 As depicted in FIG. 1 , the controller 130 includes a computer system. In certain embodiments, the controller 130 may also include the sensor array 110 and / or one or more other vehicle components, such as the actuator systems 106, 108. In addition, it should be understood that the controller 130 may be different from Figure 1 For example, controller 130 may be coupled to or may otherwise utilize one or more remote computer systems and / or other control systems, such as as part of one or more of the above-described vehicle devices and systems.

[0041] In the depicted embodiment, the computer system of controller 130 includes a processor 132, a memory 134, an interface 136, a storage device 138, and a bus 140. Processor 132 performs computational and control functions of controller 130 and may include any type of processor or multiple processors, a single integrated circuit such as a microprocessor, or any suitable number of integrated circuit devices and / or circuit boards that work in conjunction to implement the functionality of a processing unit. During operation, processor 132 executes one or more programs 142 contained within memory 134 and, therefore, controls the general operation of controller 130 and the computer system of controller 130, typically in performing the processes described herein, such as those described below in conjunction with Figure 5 and Figure 6 Further discussion process.

[0042] The memory 134 can be any type of suitable memory. For example, the memory 134 can include various types of dynamic random access memory (DRAM), such as SDRAM, various types of static RAM (SRAM), and various types of non-volatile memory (PROM, EPROM, and flash memory). In some examples, the memory 134 is located and / or co-located on the same computer chip as the processor 132. In the depicted embodiment, the memory 134 stores the above-described program 142 and one or more stored values ​​144 (e.g., including predetermined thresholds for controlling particulate matter emissions in various embodiments).

[0043] The bus 140 is used to transfer programs, data, status and other information or signals between the various components of the computer system of the controller 130. The interface 136 allows communication with the computer system of the controller 130, for example, from a system driver and / or another computer system, and is implemented using any suitable method and device. In one embodiment, the interface 136 obtains various data from the sensor array 110, the powertrain system 102, the braking system 104 and / or one or more other components and / or systems of the vehicle 100. The interface 136 may include one or more network interfaces to communicate with other systems or components. The interface 136 may also include one or more network interfaces for communicating with technicians, and / or one or more storage interfaces connected to a storage device (such as a storage device 138).

[0044] Storage device 138 may be any suitable type of storage device, including various types of direct access storage and / or other memory devices. In an exemplary embodiment, storage device 138 includes a program product from which memory 134 receives a program 142 that performs one or more embodiments of one or more processes of the present disclosure, such as described below in conjunction with Figure 5 and Figure 6The steps of the process are further discussed. In another exemplary embodiment, the program product may be directly stored in and / or otherwise accessed by memory 134 and / or storage device 138 and / or other memory devices.

[0045] The bus 140 may be any suitable physical or logical means of connecting computer systems and components. This includes, but is not limited to, direct hardwired connections, optical fiber, infrared, and wireless bus technologies. During operation, the program 142 is stored in the memory 134 and executed by the processor 132.

[0046] It should be understood that while the exemplary embodiment is described in the context of a fully functional computer system, those skilled in the art will recognize that the mechanisms of the present disclosure can be distributed as a program product in conjunction with one or more types of non-transitory computer-readable signal-bearing media for storing the program and its instructions and performing its distribution, such as a non-transitory computer-readable medium that carries the program and contains computer instructions stored therein for causing a computer processor (such as processor 132) to execute and implement the program. Such a program product can take a variety of forms, and the present disclosure applies equally regardless of the specific type of computer-readable signal-bearing medium used to perform the distribution. Examples of signal-bearing media include recordable media such as floppy disks, hard drives, memory cards, and optical disks, and transmission media such as digital and analog communication links. It should be understood that cloud-based storage and / or other technologies may also be utilized in certain embodiments. Similarly, it should be understood that the computer system of controller 130 may also differ in other ways. Figure 1 In the embodiments depicted in FIG. 1 , for example, the computer system of controller 130 may be coupled to or may otherwise utilize one or more remote computer systems and / or other control systems.

[0047] refer to Figure 2 , schematically illustrating a braking system 104. In various embodiments, the braking system 104 may be specifically associated with the vehicle 100, however, the current disclosure is not limited to vehicle applications. Generally, the braking system 104 includes a fluid source 141, an application system 143, a boost system 145, an actuator system 108, a piping system 146, and includes or is associated with a control system 114. The braking system 104 also includes a brake application actuator 148 and wheel brake actuators 151-154, which may be part of the actuator system 108. For example, in some embodiments, such as for autonomous control, the brake application actuator 148 may be operated by the control system 114.

[0048] In the current embodiment, fluid source 141 includes brake fluid reservoir 156, which stores and supplies fluid used in brake system 104. Brake fluid reservoir 156 holds fluid 158 and includes a shared volume 160 and three separate volumes, including a booster volume 162, a primary volume 164, and a secondary volume 166.

[0049] The application system 143 includes a master cylinder 168 that is connected to the brake fluid reservoir 156 and the brake application actuator 148. The master cylinder 168 is configured to receive inputs from the brake application actuator 148 and transmit those brake application inputs to the conduit system 146 through the primary circuit 147 and the secondary circuit 149. The inputs may be manual, such as from a driver of the vehicle 100, and / or may be automatic, such as controlled by the control system 114 in an autonomous mode. The master cylinder 168 delivers pressure to separate branches of the conduit system 146 (primary circuit 147 and secondary circuit 149) through the primary cylinder 170 and the secondary cylinder 172. The primary cylinder 170 is fluidly connected to the primary volume 164, and the secondary cylinder 172 is fluidly connected to the secondary volume 166.

[0050] The boost system 145 includes a booster 174 and an actuator 176. In the current embodiment, the boost system 145 may be an electronic boost system having an electric hydraulic booster that interprets the brake command input at the brake application actuator 148 and uses the actuator 176 (such as a motor) to move a plunger 181 to displace the brake fluid in the pipe system 146 to one or more of the wheel brake actuators 151-154 (which may be referred to as brake corners, or which may be disposed at brake corners) of the vehicle 100.

[0051] The piping system 146 includes various fluid conduits, such as pipes, hoses, channels, etc., that transmit fluid pressure, including through the primary circuit 147 and the secondary circuit 149. Various valves are provided in the piping system 146 and coupled to the control system 114 to control how and when pressure is transmitted. This includes a primary master cylinder valve 180 in the primary circuit 147, which is operable to open and close to allow or prevent / control fluid pressure communication between the wheel brake actuators 151, 152 and the primary cylinder 170. The primary master cylinder valve 180 can be a normally open valve so that in the absence of power, the primary cylinder 170 is in open communication with the wheel brake actuators 151, 152. The primary master cylinder valve 180 can be controlled to be closed to inhibit feedback from the booster 174 to the brake apply actuator 148. Similarly, the secondary master cylinder valve 182 in the secondary circuit 149 is operable to open and close to allow or prevent or regulate fluid pressure communication between the wheel brake actuators 153, 154 and the secondary cylinder 172. The secondary master cylinder valve 182 may be a normally open valve such that in the absence of power, the secondary cylinder 172 is in open communication with the wheel brake actuators 153, 154. The secondary master cylinder valve 182 may be controlled to close to disable feedback from the booster 174 to the brake apply actuator 148. In an embodiment, the primary master cylinder valve 180 and the secondary master cylinder valve 182 may be variably controlled to allow partial pressure communication, such as for tuning feedback.

[0052] The valves also include a primary boost isolating valve 184 and a secondary boost isolating valve 186. The primary boost isolating valve 184 is operable to allow or prevent or regulate fluid / pressure communication between the booster 174 and the primary circuit 147. The secondary boost isolating valve 186 is operable to allow or prevent or regulate fluid / pressure communication between the booster 174 and the secondary circuit 149. For example, during an unboosted brake application by the brake apply actuator 148, the primary boost isolating valve 184 and the secondary boost isolating valve 186 may be closed to direct pressure to the wheel brake actuators 151-154.

[0053] In addition, each of the wheel brake actuators 151-154 includes a pair of valves to control the pressure at each corner (specifically, at the corresponding wheel brake actuator 151-154). The wheel brake actuator 151-154 may include a cylinder with a piston, which brakes the vehicle 100 through friction pads 191-194 in response to fluid pressure, and the friction pads engage a moving member, such as a rotating element designated as a rotor 201-204. In other embodiments, the rotating element can be a drum, an axle, a plate, etc. The paired valves for the wheel brake actuators 151-154 each include a corresponding inlet valve 211-214 and a corresponding outlet valve 221-224. Each inlet valve 211-214 is individually controlled to allow pressure to enter the corresponding wheel brake actuator 151-154 from the booster 174 and / or the master cylinder 168. Each outlet valve 221-224 is individually controlled to release pressure from the corresponding wheel brake actuator 151-154 to the brake fluid reservoir 156. Thus, the pressure at each corner through the wheel brake actuator 151-154 is individually controlled by the control system 114.

[0054] In the current embodiment, there are four corners 281-284 for the vehicle 100. The right front corner 281 includes the wheel brake actuator 151, and is associated with the friction pad 191, the rotor 201, the inlet valve 211, and the outlet valve 221. The left rear corner 282 includes the wheel brake actuator 152, and is associated with the friction pad 192, the rotor 202, the inlet valve 212, and the outlet valve 222. The right rear corner 283 includes the wheel brake actuator 153, and is associated with the friction pad 193, the rotor 203, the inlet valve 213, and the outlet valve 223. The left front corner 284 includes the wheel brake actuator 154, and is associated with the friction pad 194, the rotor 204, the inlet valve 214, and the outlet valve 224. The brake pressure circuit is separated, wherein the right front corner 281 and the left rear corner 282 are connected in the primary circuit 147 , while the left front corner 284 and the right rear corner 283 are connected in the secondary circuit 149 .

[0055] The various valves also include a test valve 226 that can be operated for diagnostic purposes, such as by the control system 114. It should be understood that each of the valves 180, 182, 184, 186, 211-214, 221-224, and 226 is coupled to the controller 130 and is responsive to the processor 132 to precisely control the fluid / pressure entering through the corresponding valve.

[0056] The brake system 104 also includes various sensors, such as those of the brake sensors 118. For example, the brake apply sensor 230 senses the amount of brake actuation by the operator at the brake apply actuator 148. In embodiments, such as in autonomous control, the brake apply may be such as sensed by the brake apply sensor 230, or may be a value retrieved from the memory 134 for controlled brake application. The brake sensors 118 may also include a boost pressure sensor 232 that monitors boost pressure. Boost pressure may also be referred to as plunger pressure because it is generated by the plunger 181. In some embodiments, a pressure sensor may be included at each of the brake corners 281-284, such as to monitor the pressure at each of the wheel brake actuators 151-154. In other embodiments, during calibration, control parameters may be determined and stored, such that feedback control is not required.

[0057] In various embodiments, the controller 130 may receive information in signals from the various sensors of the sensor array 110, process the information, and send control signals / commands to the various actuators of the actuator systems 106, 108 to operate the powertrain system 102 and the brake system 104. The sensor array 110 senses observable conditions, including observable conditions of the brake system 104. In various embodiments, the sensed values ​​include data associated with braking force, such as requested by the brake apply actuator 148, and data associated with pressure at each corner 281-284, such as from the boost pressure sensor 232.

[0058] During operation of the brake system 104, in response to controlled pressure delivery, the friction pads 191-194 act on rotating elements, such as rotors 201-204, thereby applying frictional forces. The changes in pressure applied between the two components result in various dynamic responses, such as vibrations, some of which result in the generation of perceptible sounds. Under certain conditions, vibration spikes may occur, which may be particularly conducive to the generation of sounds, which may be objectionable noises, such as chatter. For example, there may be pressure bands where detectable and unwanted noises are generated. Reference Figure 3 ,exist Figure 3 2. Curve 240 shows brake application force in Newtons, such as applied by brake application actuator 148, as depicted on left vertical axis 241. Brake application force is converted to a request for pressure from boost system 145. Curve 242 shows deceleration in gravitational units (g), as depicted on right vertical axis 243, resulting from pressure delivered to corners 281-284, such as by wheel brake actuators 151-154. Time in seconds is depicted on horizontal axis 245. Figure 3The graph of 242 shows that when the brake application force is released (as depicted by curve 240), there is a noise zone 250 (shudder noise zone) where a vibration spike occurs on curve 242. This may be an identifiable noise zone 250 and may be referred to as a shudder noise generated by the brake system 104. In various embodiments described below, avoiding this noise zone 250 may be achieved by controlling the inlet valves 211-214 and the outlet valves 221-224 to avoid shudder-generating pressures at the corners 281-284 in a shudder noise zone avoidance mode.

[0059] refer to Figure 4 , the graph illustrates boost pressure in bars of the brake system 104 on a vertical axis 256 (such as may be received from the boost pressure sensor 232 ). Figure 4 The graph of also depicts pedal release (such as sensed by brake apply sensor 230) on horizontal axis 258 in Newtons. Within these parameters, a noise zone 250 may exist as a function of pressure and pedal release, where chatter is generated. The noise zone 250 may be identified by characterization testing and / or modeling of the brake system 104 in the vehicle 100 and may be stored in memory 134. A brake corner pressure curve 260 is schematically shown for the front brake corners 281, 284, and a brake corner pressure curve 262 is shown for the rear brake corners 282, 283. The corner pressure curve 260 and the corner pressure curve 262 each include a respective segment 264, 266 during which the brake apply actuator 148 is gradually released along a common profile and the boost pressure is gradually reduced. Along the segments 264, 266, the respective inlet valves 211-214 move in an opening direction and the respective outlet valves 221-224 move in a closing direction. If the trend of segments 264, 266 continues, corner pressure curves 260, 262 will intersect noise zone 250. To avoid noise zone 250, starting at point 271, inlet valves 211-214 and / or outlet valves 221-224 are actuated to change the pressure at each wheel brake actuator 151-154.

[0060] For the plunger pressure applied to the front corners 281, 284 after point 271, the result of the control action is depicted by segment 270, where the inlet valves 211, 214 move in the closing direction and the outlet valves 221, 224 move in the opening direction to increase the rate of pressure reduction at the front corners 281, 284, avoiding the noise zone 250. When the pressure reaches point 272, which is defined below the noise zone 250, the inlet valves 211, 214 remain in the closing direction and the outlet valves 221, 224 move in the closing direction, and the curve 260 follows segment 274 to maintain a predetermined front brake pressure, such as approximately 5 bar, while the corner pressure curve 260 moves to point 275. As a result, the pressure generated by the wheel brake actuators 151, 154 at the corners 281, 284 avoids the noise zone 250 and avoids chatter.

[0061] For the plunger pressure applied to the rear corners 282, 283 from point 271, the result of the control action is depicted by segment 276, where the inlet valves 212, 213 move in the closing direction and the outlet valves 222, 223 move in the closing direction to maintain the rear brake pressure, such as about 10 bar, for compensating the total braking torque to avoid the noise zone 250 at the rear corners 282, 283, and the pressure moves to point 273. When the plunger pressure reaches a predetermined pressure below the noise zone 250, the inlet valves 212, 213 move in the closing direction and the outlet valves 222, 223 move in the opening direction through segment 277 to increase the rate of pressure reduction at the rear corners 282, 283, and the rear corner pressure curve 262 moves to point 275.

[0062] Starting from point 275, the front corner pressure curve 260 and the rear corner pressure curve 262 include corresponding segments 278, 279, which in the exit control include moving the inlet valve 211-214 in the opening direction and the outlet valve in the closing direction with the same profile in this embodiment. Through the control action, the pressure in the brake system 104 avoids the noise zone 250 and does not generate a chattering noise.

[0063] refer to Figure 5 , a flow chart showing a method for controlling Figure 1 and Figure 2 The process 300 of the operation of the braking system 104. It will be understood from the present disclosure that the order of operations within the process 300 is not limited to the following. Figure 5 The steps of process 300 are performed in the order shown in FIG. 3 and may be performed in one or more altered orders where applicable and in accordance with the present disclosure. In additional embodiments, additional steps may be included in process 300 and / or some steps may be omitted from process 300.

[0064] In various embodiments, it is possible to combine Figure 1 The process 300 is implemented with a vehicle 100 and its braking system 104, including its control system 114 and controller 130. Judder, which may be referred to as brake creep judder, is a noise that may be observed when the vehicle 100 begins to move from a stopped condition with brake pressure applied. Movement occurs when brake pressure is reduced while there is a motive force (such as an idling engine through an automatic transmission of the powertrain system 102, or such as due to gravity of the vehicle 100 on a slope). The vibration that causes the sound may be caused by changes in friction in a stick-slip mode. The generation of judder may also depend on various parameters in addition to the design of the braking system 104 itself. For example, the suspension structure of the vehicle 100 may contribute to the generation of judder. Therefore, simple changes to the braking system 104 (such as using different friction materials) may not stop the generation of judder. Therefore, the process 300 provides a solution to avoid the generation of judder without physical system changes.

[0065] like Figure 5 , such as when operation of the vehicle 100 begins. In certain embodiments, the process 300 begins 302 when one or more events occur to indicate that operation of the vehicle 100 is occurring or is about to occur, such as a driver, operator, or passenger entering the vehicle 100, a brake apply actuator 148 (pedal) is operated 304, an ignition (such as may be part of other sensors 120) is turned on 306, and a transmission (such as of the powertrain system 102) is switched 308 to a "drive" mode, etc. In various embodiments, based on information from Figure 1 The event that triggers the start of process 300 is determined by using sensor data from one or more of other sensors 120 (e.g., from an ignition sensor in some embodiments). Also in some embodiments, as part of start step 302, control system 114 is turned on or "woken up," or brake apply actuator 148 is operated 304.

[0066] The process 300 then monitors the sensor array 110 and specifically includes a release monitoring 310 of the brake apply actuator 148. During the release monitoring 310 of the brake apply actuator 148, the controller 130, via the processor 132, operates the brake system 104 including the booster 174 via the actuator 176, the inlet valves 211-214 and the outlet valves 221-224 to reduce the pressure at the corners 281-284 (wheel brake actuators 151-154). As described above, the release of the brake actuator causes the pressure in the brake system 104 to decrease and at some point causes the vehicle 100 to move as the rotors 201-204 rotate. The movement of the rotors 201-204 while the friction pads 191-194 still apply some force thereto results in the possibility of brake judder due to the intrusion of the noise zone 250.

[0067] Process 300 continues with a determination 312, such as by processor 132 of controller 130, as to whether the upper target pressure has been reached. For example, the upper target pressure may be as indicated by boost pressure sensor 232. Figure 4 312 . When the determination 312 is negative, meaning that the boost pressure is above and has not yet been reduced to the upper target pressure, the process 300 returns to the release monitoring 310 . When the release monitoring 310 results in the determination 312 that the upper target pressure is reached, the process 300 is approaching the flutter avoidance control, but first determines 314 whether the vehicle 100 is on a sloped road, such as by the processor 132 using inputs from other sensors 120 . For example, the other sensors 120 may include an inertial measurement unit (IMU). The inertial measurement unit may include accelerometers and gyroscopes, which may be in electronic form to provide motion, position, and navigation sensing in multiple degrees of freedom. For example, a micro-electromechanical system (MEMS) device may be used to sense translations such as surges, heaves, sways, and rotations such as roll, pitch, and yaw. In other examples, another type of sensor may be used to detect the slope of the road. The road slope is determined 314 because the noise zone 250 may be different for different road slopes, and the control parameters may be different. Thus, the memory 134 may have a lookup table or other stored values ​​144 calibrated for different ramp values, providing different control points for the inlet valves 211 - 214 and the outlet valves 221 - 224 .

[0068] When the determination 314 is negative, meaning that the road is not tilted, at least not above a threshold that would affect the noise zone 250, the process 300 proceeds to control 316 any number of the inlet valves 211-214 and any number of the outlet valves 221-224 using calibration values ​​for normal (non-tilted) roads that may be obtained from the memory 134 to avoid the noise zone 250. For example, the calibration values ​​may be as described with respect to Figure 4Inlet valves 211-214 and outlet valves 221-224 are controlled as described to avoid noise zone 250. In some embodiments, boost actuator 176 may also be controlled to adjust deceleration of vehicle 100 and / or avoid judder.

[0069] The process 300 continues with determining 318 whether there is a pressure increase at the brake apply actuator 148. For example, during brake release, the operator may reapply the brakes due to operating conditions. When the determination 318 is affirmative, and the pressure increase at the brake apply actuator 148 is such that the noise zone 250 will not be entered, the process 300 proceeds to exit 320 judder avoidance, and the inlet valves 211-214 and the outlet valves 221-224 are controlled in normal operation, and the vehicle 100 moves 322 when friction drops below a threshold level. In some embodiments, the process 300 may return to the control 316 step to avoid judder and may proceed from there, rather than moving to the exit 320 step.

[0070] When determination 318 is negative, meaning that the pressure at brake apply actuator 148 has not increased, process 300 proceeds to determination 324 whether the pressure at boost pressure sensor 232 has reached the lower target pressure. For example, the lower target pressure may be as indicated by boost pressure sensor 232. Figure 4 When the determination 324 is negative, meaning that the boost pressure has not yet been reduced to the lower target pressure, the process 300 returns to the control 316 step to control the shudder and can proceed from there. When the determination 324 is positive, meaning that the boost pressure has been reduced to the lower target pressure, the process 300 proceeds to the exit 320 shudder avoidance and controls the inlet valves 211-214 and the outlet valves 221-224 in normal operation and the vehicle 100 moves 322 when friction drops below a threshold level. For example, control can be along the Figure 4 Sections 278 and 279 of

[0071] Returning to determination 314, when the result is positive, meaning that the road is inclined, at least above a threshold that will affect noise zone 250, process 300 proceeds to control 326 any number of inlet valves 211-214 and any number of outlet valves 221-224 using calibration values ​​for the degree of road inclination, such as may be obtained from memory 134, to avoid noise zone 250. For example, similar to the description of Figure 4 Controlling 326 the inlet valves 211-214 and the outlet valves 221-224 is described to avoid the noise region 250. In some embodiments, the boost actuator 176 may also be controlled to avoid chatter.

[0072] The process 300 continues with determining 328 whether there is a pressure increase at the brake apply actuator 148. For example, during brake release, the operator may reapply the brakes due to operating conditions. When the determination 328 is affirmative, and the pressure is increasing and will not enter the noise zone 250, the process 300 proceeds to exit 330 shudder avoidance and controls the inlet valves 211-214 and the outlet valves 221-224 in normal operation, and when friction drops below a threshold level, the vehicle 100 moves 322. In some embodiments, the process 300 may return to the control 326 step and proceed from there, rather than moving to the exit 330 step.

[0073] When determination 328 is negative, meaning that the pressure at brake apply actuator 148 has not increased, process 300 continues with judder avoidance control and proceeds to determination 332 whether the pressure at boost pressure sensor 232 has reached the lower target pressure. For example, the lower target pressure may be as indicated by boost pressure sensor 232. Figure 4 When the determination 332 is negative, meaning that the boost pressure has not yet been reduced to the lower target pressure, the process 300 returns to the control 326 step and can proceed from there. When the determination 332 is positive, meaning that the boost pressure has been reduced to the lower target pressure, the noise zone 250 is avoided, and the process 300 proceeds to the exit 330 flutter avoidance, and the inlet valves 211-214 and the outlet valves 221-224 are controlled in normal operation, and the vehicle 100 moves 322 when the friction drops below the threshold level. For example, the control may follow Figure 4 Sections 278 and 279.

[0074] refer to Figure 6 , a process 400 suitable for continued operation of the vehicle 100 and the brake system 104 after an initial start is shown. The process 400 starts 402 and monitors 404 the application of the brake apply actuator 148, such as by the controller 130 based on input from the brake apply sensor 230, followed by a release 406 action of the brake apply actuator 148. The process 400 proceeds to determine 408, such as by the processor 132, whether the number of brake applications since the initial start of the vehicle exceeds a threshold value, or whether the speed of the vehicle 100 exceeds a threshold speed value. For example, the controller 130 may monitor and count the brake applications via the brake apply sensor 230, and store the counted value in the memory 134 for recall in the determination 408. In addition, for example, the other sensors 120 may include a vehicle speed sensor that may be monitored by the controller 130. The determination 408 is made because after a threshold number of brake applications, the risk of generating a chattering noise subsides, such as because the brake temperature has increased. The determination 408 is also made because above a threshold speed of the vehicle 100, the risk of generating a chattering noise dissipates.

[0075] When determined to be positive, meaning at least one of the following: the number of brake applications since initial start of vehicle 100 exceeds a threshold number value or the speed of vehicle 100 exceeds a threshold speed value, process 400 proceeds to exit 410 judder avoidance, and inlet valves 211-214 and outlet valves 221-224 are controlled in normal operation without judder avoidance mode, and vehicle 100 moves 412 when friction drops below a threshold level.

[0076] Returning to determination 408, when the result is negative, meaning that the number of brake applications since the initial start of the vehicle has not exceeded the threshold value and the speed of the vehicle 100 has not exceeded the threshold speed value, process 400 continues to determination 414. Determination 414 as to whether the upper target pressure has been reached may be performed by processor 132 of controller 130. For example, the upper target pressure may be as indicated by boost pressure sensor 232. Figure 4 The pressure at point 271 of the vehicle 100 is determined. When determination 414 is negative, meaning that the boost pressure has not yet been reduced to the upper target pressure, process 400 returns to release 406 monitoring and proceeds from there. When determination 414 is positive, and it is concluded that the upper target pressure has been reached, process 400 proceeds to determine 416 whether the vehicle 100 is on a sloped road, such as by the processor 132 using inputs from other sensors 120. For example, other sensors 120 may include an IMU. In other examples, another type of sensor may be used to detect the slope of the road. Determine the road slope 416 because the noise zone 250 may be different for different road slopes, and the control parameters may be different. Therefore, the memory 134 may have a lookup table or other stored value 144 calibrated for slope values ​​to provide different control points for the inlet valves 211-214 and the outlet valves 221-224.

[0077] When determination 416 is negative, meaning the road is not tilted, at least not above a threshold that would affect noise zone 250, process 400 proceeds to control 418 any number of inlet valves 211-214 and any number of outlet valves 221-224 using calibration values ​​for a normal (non-tilted) road to avoid noise zone 250. For example, the Figure 4 Inlet valves 211-214 and outlet valves 221-224 are controlled as described to avoid noise region 250. In some embodiments, boost actuator 176 may also be controlled to avoid chatter.

[0078] Process 400 continues with determining 420 whether there is a pressure increase at brake apply actuator 148. For example, during brake release, the operator may reapply the brakes due to operating conditions. When determination 420 is affirmative, and pressure is increasing and will not enter noise zone 250, process 400 proceeds to exit 410 shudder avoidance and controls inlet valves 211-214 and outlet valves 221-224 in normal operation, and when friction drops below a threshold level, vehicle 100 moves 412. In some embodiments, process 400 may return to control 418 step and proceed from there, rather than moving to exit 410 step.

[0079] When determination 420 is negative, meaning that the pressure at brake apply actuator 148 has not increased, process 400 proceeds to determination 422 whether the pressure at boost pressure sensor 232 has reached a lower target pressure. For example, the lower target pressure may be as indicated by boost pressure sensor 232. Figure 4 When determination 422 is negative, meaning that the boost pressure has not yet been reduced to the lower target pressure, process 400 returns to step 418 of control in the flutter avoidance mode and may proceed from there. When determination 422 is positive, meaning that the boost pressure has been reduced to the lower target pressure, process 400 proceeds to exit 410 flutter avoidance and controls inlet valves 211-214 and outlet valves 221-224 in normal operation, such as along Figure 4 segments 278 , 279 , and when friction drops below a threshold level, the vehicle 100 moves 412 .

[0080] Returning to determination 416, when the result is positive, meaning that the road is inclined, at least above a threshold that will affect noise zone 250, process 400 proceeds to control 424 any number of inlet valves 211-214 and any number of outlet valves 221-224 using calibration values ​​for the degree of road inclination to avoid noise zone 250. For example, similar to the description of Figure 4 Controlling 424 the inlet valves 211-214 and the outlet valves 221-224 is described to avoid the noise zone 250 using the stored value for the road slope from the memory 134. In some embodiments, the boost actuator 176 may also be controlled to avoid shudder vibrations.

[0081] Process 400 continues with determining 426 whether there is a pressure increase at brake apply actuator 148. For example, during brake release, the operator may reapply the brakes due to operating conditions. When determination 426 is affirmative, and pressure is increasing and will not enter noise zone 250, process 400 proceeds to exit 430 shudder avoidance and controls inlet valves 211-214 and outlet valves 221-224 in normal operation, and when friction drops below a threshold level, vehicle 100 moves 412. In some embodiments, process 400 may return to control 424 step and proceed from there, rather than moving to exit 430 step.

[0082] When determination 426 is negative, meaning that the pressure at brake apply actuator 148 has not increased, process 400 proceeds to determination 428 whether the pressure at boost pressure sensor 232 has reached the lower target pressure. For example, the lower target pressure may be as indicated by boost pressure sensor 232. Figure 4 When determination 428 is negative, meaning that boost pressure has not yet been reduced to the lower target pressure, process 400 returns to control 424 step with control in judder avoidance mode and may proceed from there. When determination 428 is positive, meaning that boost pressure has been reduced to the lower target pressure, process 400 proceeds to exit 430 judder avoidance and inlet valves 211-214 and outlet valves 221-224 are controlled in normal operation and vehicle 100 moves 412 when friction drops below a threshold level.

[0083] Therefore, the system and method provide brake system control to avoid trembling conditions, thereby avoiding undesirable noise. The front and rear wheel brake actuators of the vehicle are selectively operated by controlling the inlet valves and outlet valves of the front and rear wheel brake actuators of the vehicle to avoid brake pressure classified as being in the trembling zone. The individual control of the brake pressure at each vehicle corner avoids the pressure that produces trembling noise without physically changing the vehicle (such as its brake system or its suspension system). Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that there are a large number of variations. It should also be understood that the exemplary embodiment or multiple exemplary embodiments are merely examples and are not intended to limit the scope, applicability or configuration of the present disclosure in any way. On the contrary, the foregoing detailed description will provide a convenient roadmap for those skilled in the art to implement the exemplary embodiment or multiple exemplary embodiments. It should be understood that various changes can be made to the functions and arrangements of the elements without departing from the scope of the present disclosure as set forth in the attached claims and their legal equivalents.

Claims

1. A system for controlling braking, the system having a brake actuator configured to apply friction to a moving member, a piping system coupled to the brake actuator, an inlet valve in the piping system configured to control fluid pressure delivered to the brake actuator, and an outlet valve in the piping system configured to control fluid pressure released from the brake actuator, the system comprising: A controller configured to: monitoring an upper target pressure condition in the system, wherein the upper target pressure condition is associated with a noise zone; and When the upper target pressure is detected and in the noise zone avoidance mode, the inlet valve and the outlet valve are operated to avoid a brake pressure at which brake noise is generated by the friction force.

2. The system according to claim 1, wherein: The controller is configured to monitor for a vehicle start event, and after the vehicle start event, the controller is configured to perform said monitoring for the upper target pressure condition in the system.

3. The system according to claim 1, wherein: The controller is configured to count a number of brake applications after a vehicle start event and to skip the monitoring of the upper target pressure when the number of brake applications exceeds a threshold.

4. The system according to claim 1, wherein: The controller is configured to determine whether there is a slope that affects the brake noise through a slope sensor, and when the slope exists, operate the inlet valve and the outlet valve in a ramp mode when the upper target pressure is detected.

5. The system according to claim 1, wherein: The controller is configured to: determining whether a pressure increase is applied via a brake apply actuator; and When the pressure increase is applied, the noise zone avoidance mode is exited.

6. The system of claim 1, comprising a vehicle, the vehicle comprising the system, wherein: The controller is configured to: determining whether the vehicle is operating on a slope; when the vehicle is not operating on the slope, operating the inlet valve and the outlet valve in a normal mode when the upper target pressure is detected; as well as When the vehicle is operating on the slope, when the upper target pressure is detected, the inlet valve and the outlet valve are operated in a slope mode that is different from the normal mode and customized for the slope.

7. The system of claim 1, comprising a vehicle, the vehicle comprising the system, wherein: The controller is configured to: determining the speed of the vehicle by a speed sensor; and When the speed exceeds a threshold, the monitoring of the upper target pressure is skipped.

8. A method for controlling a braking system, the method comprising: applying a friction force to the moving member by a brake actuator; coupling a conduit system to the brake actuator; controlling the pressure of the fluid delivered to the brake actuator by an inlet valve in the conduit system; controlling the fluid pressure released from the brake actuator by an outlet valve in the conduit system; monitoring, by a controller, an upper target pressure condition in the system, the upper target pressure condition being associated with a noise zone; as well as When the upper target pressure is detected and in the noise zone avoidance mode, the inlet valve and the outlet valve are operated by the controller to avoid a brake pressure at which brake noise is generated by the friction force.

9. The method according to claim 8, comprising: The controller monitors a vehicle start event; as well as The monitoring of the upper target pressure condition in the system is performed after the vehicle start event.

10. The method according to claim 8, comprising: counting, by the controller, a number of brake applications after a vehicle start event; as well as The monitoring of the upper target pressure is skipped by the controller when the number of brake applications exceeds a threshold.

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