Motor vehicle brake pad wear detection system and method

Abstract

This application discloses a method and system for monitoring the wear of brake pads in a motor vehicle. The motor vehicle includes a hydraulic braking device acting on its wheels. The hydraulic braking device has a brake disc that rotates with the wheels and brake pads that are not rotatable relative to the brake disc but can move linearly parallel to the rotation axis of the brake disc. The method includes: recording the time required for the hydraulic braking device to build up brake hydraulic pressure when the motor vehicle is stationary; and comparing the recorded time required to build up brake hydraulic pressure with the time required to build up brake hydraulic pressure of the same hydraulic braking device when the brake pads are newly installed, to determine the wear state of the brake pads.

Description

Technical Field

[0001] This application relates essentially to systems and methods for monitoring wear of brake pads in motor vehicles. Background Technology

[0002] A braking system is a mandatory device on motor vehicles according to road traffic regulations. A braking system mainly includes a brake disc that is rotatably mounted with the wheel rim and friction pads that are immovably mounted relative to the rim. For each brake disc, the friction pads, for example, are two pads installed with a certain gap on opposite sides of the corresponding brake disc. Driven by a drive mechanism, they can move to contact the rotating brake disc and apply a clamping force to it, causing the brake disc to stop moving due to friction braking.

[0003] Typically, brake discs are harder than brake pads. Therefore, the brake pads will wear down and thin with prolonged braking. To ensure sufficient braking force, the brake pads need to be replaced promptly once they have worn down to a certain extent. This necessitates monitoring the wear of the brake pads.

[0004] A traditional method for monitoring brake pad wear involves placing a metal plate on the backing plate of the brake pad. This metal plate has a free end adjacent to the worn surface of the brake pad (the side that contacts the brake disc), and this free end is recessed a certain distance from the worn surface in the thickness direction of the brake pad. Under normal circumstances, the free end of the metal plate is spaced apart from the brake disc when the brake pad contacts the brake disc for wheel braking. However, when the brake pad wears down to a certain extent and wheel braking is applied, the free end of the metal plate will come into contact with the rotating brake disc and produce a sharp noise, thus alerting the driver that the brake pads need to be replaced. The disadvantage of this brake pad wear monitoring method is that the driver cannot perceive the degree of brake pad wear before the sharp noise occurs. Furthermore, the frictional contact between the metal plate and the brake disc can also damage the brake disc.

[0005] Another traditional method for monitoring friction pads is to equip them with corresponding sensors to monitor their wear condition as needed. However, this increases the complexity of the overall suspension structure design and wiring due to the sensor installation, and also leads to an increase in component costs as well as design and assembly costs. Summary of the Invention

[0006] To address the above issues, this application aims to propose a simple and easy-to-implement brake friction pad wear monitoring method, which can conveniently monitor the wear of brake friction pads without significantly increasing costs or modifying the existing vehicle suspension design, thereby providing corresponding protection for safe driving of motor vehicles.

[0007] According to one aspect of this application, a brake pad wear monitoring system for a motor vehicle is provided, wherein the motor vehicle includes a hydraulic braking device acting on its wheels, the hydraulic braking device having a brake disc that rotates with the wheels and brake pads that are non-rotatable relative to the brake disc but capable of linear movement parallel to the rotation axis of the brake disc, characterized in that the brake pad wear monitoring system includes:

[0008] A recording module is used to record the time required for the hydraulic braking device to build up brake hydraulic pressure when the vehicle has come to a complete stop.

[0009] A central electronic control unit, which is connected to the recording module, compares the time required to establish brake hydraulic pressure with the time required to establish brake hydraulic pressure of the same hydraulic braking device when the brake friction pads are newly installed to determine the wear status of the brake friction pads.

[0010] Optionally, while the recording module is recording the hydraulic braking device of one wheel of the motor vehicle, the central electronic control unit generates a command to disable the hydraulic braking devices of the other wheels of the motor vehicle.

[0011] Optionally, the recorded time required to establish the brake hydraulic pressure is the average of multiple recordings of the corresponding hydraulic braking device.

[0012] Optionally, the time required to establish the braking hydraulic pressure of the same hydraulic braking device when the brake friction pads are newly installed is the average value of multiple recordings of the hydraulic braking device.

[0013] Optionally, the recording module operates after the vehicle has traveled a certain distance and when the vehicle has come to a complete stop, to record the time required for the hydraulic braking device to establish braking hydraulic pressure.

[0014] Optionally, the motor vehicle includes a brake fluid drive circuit and a brake fluid reservoir fluidly connected to the brake fluid drive circuit. The brake fluid drive circuit includes a hydraulic master pump and a fluid network. The fluid network has a hydraulic circuit portion that only fluidly connects the hydraulic braking device to the hydraulic master pump when it is necessary to record the time required to build up brake hydraulic pressure for a hydraulic braking device.

[0015] Optionally, a pressure sensor is installed in the fluid pipeline to measure the brake fluid pressure in the hydraulic circuit section, thereby determining whether brake hydraulic pressure has been established.

[0016] According to another aspect of this application, a brake pad wear monitoring system for a motor vehicle is also provided, wherein the motor vehicle includes a hydraulic braking device acting on its wheels, the hydraulic braking device having a brake disc that rotates with the wheels and brake pads that are non-rotatable relative to the brake disc but capable of linear movement parallel to the rotation axis of the brake disc, the brake pads being driven to move by a hydraulic brake cylinder assembly, characterized in that the brake pad wear monitoring system includes:

[0017] A recording module is used to record the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly to establish brake hydraulic pressure when the vehicle is stationary.

[0018] The central electronic control unit is connected to the recording module to compare the recorded volume of brake fluid injected into the cylinder with the recorded volume of brake fluid injected into the same cylinder when the brake pads are newly installed to determine the wear status of the brake pads.

[0019] Optionally, while the recording module is recording the hydraulic braking device of one wheel of the motor vehicle, the central electronic control unit generates a command to disable the hydraulic braking devices of the other wheels of the motor vehicle.

[0020] According to another aspect of this application, a motor vehicle is also provided, the motor vehicle including any of the aforementioned brake pad wear monitoring systems.

[0021] According to one aspect of this application, a method for monitoring brake pad wear in a motor vehicle is also provided, wherein the motor vehicle includes a hydraulic braking device acting on its wheels, the hydraulic braking device having a brake disc that rotates with the wheels and brake pads that are non-rotatable relative to the brake disc but capable of linearly moving parallel to the rotation axis of the brake disc, the method comprising:

[0022] With the vehicle stationary, record the time required for the hydraulic braking device to establish braking hydraulic pressure.

[0023] The time required to establish brake hydraulic pressure is compared with the time required to establish brake hydraulic pressure of the same hydraulic braking device when the brake friction pads are newly installed, in order to determine the wear condition of the brake friction pads.

[0024] Optionally, while recording the hydraulic braking device of one wheel of the motor vehicle, the hydraulic braking devices of the other wheels of the motor vehicle are prohibited from operating.

[0025] Optionally, the recorded time required to establish the brake hydraulic pressure is the average of multiple recordings of the corresponding hydraulic braking device.

[0026] Optionally, the time required to establish the braking hydraulic pressure of the same hydraulic braking device when the brake friction pads are newly installed is the average value of multiple recordings of the hydraulic braking device.

[0027] Optionally, after the vehicle has traveled a certain distance and come to a complete stop, the time required for the hydraulic braking device to establish braking hydraulic pressure is recorded.

[0028] Optionally, the motor vehicle includes a brake fluid drive circuit and a brake fluid reservoir fluidly connected to the brake fluid drive circuit. The brake fluid drive circuit includes a hydraulic master pump and a fluid network configured to generate a portion of the hydraulic circuit that fluidly connects only the hydraulic braking device to the hydraulic master pump when it is necessary to record the time required to build up brake hydraulic pressure for a hydraulic braking device.

[0029] Optionally, a pressure sensor is installed in the fluid pipeline to measure the brake fluid pressure in the hydraulic circuit section, thereby determining whether brake hydraulic pressure has been established.

[0030] According to another aspect of this application, a method for monitoring brake pad wear in a motor vehicle is provided, wherein the motor vehicle includes a hydraulic braking device acting on its wheels, the hydraulic braking device having a brake disc that rotates with the wheels and brake pads that are non-rotatable relative to the brake disc but capable of linear movement parallel to the rotation axis of the brake disc, the brake pads being driven to move by a hydraulic brake cylinder assembly, the method comprising:

[0031] With the vehicle stationary, record the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly to establish braking hydraulic pressure.

[0032] The volume of brake fluid injected into the cylinder is compared with the volume of brake fluid injected into the same cylinder when the brake pads are newly installed, in order to determine the wear condition of the brake pads.

[0033] Optionally, while recording the hydraulic braking device of one wheel of the motor vehicle, the hydraulic braking devices of the other wheels of the motor vehicle are prohibited from operating.

[0034] According to another aspect of this application, a brake pad wear monitoring system for a motor vehicle is provided, comprising:

[0035] A central electronic control unit, configured to control the hydraulic braking device of the motor vehicle and a brake fluid drive circuit for operating the hydraulic braking device, characterized in that the central electronic control unit is configured to perform the aforementioned method.

[0036] By employing the technical means described in this application, the wear and tear of the friction pads can be reliably monitored without requiring any additional equipment. This provides a favorable basis for motor vehicle users to replace the friction pads, reduces the design, manufacturing, and assembly costs of the braking device, and improves the safety of motor vehicle driving. Attached Figure Description

[0037] A more comprehensive understanding of the principles and aspects of this application will be gained from the detailed description below, in conjunction with the accompanying drawings. It should be noted that the scale of the drawings may vary for clarity, but this will not affect the understanding of this application. In the drawings:

[0038] Figure 1 A simplified schematic diagram of a motor vehicle is shown, wherein the motor vehicle is equipped with a hydraulic braking system;

[0039] Figure 2 A simplified schematic diagram of a hydraulic braking device configured for one wheel is shown;

[0040] Figure 3 This is a simplified diagram illustrating the basic principle of brake friction pad thickness detection in the hydraulic braking device of this application;

[0041] Figure 4 This is a graph showing the change in pressure applied to the brake friction pads over time when a single hydraulic braking device achieves friction braking.

[0042] Figure 5 This is a block diagram, schematically illustrating a vehicle brake pad wear detection system according to one embodiment of this application;

[0043] Figure 6 The brake fluid drive circuit of an example hydraulic braking system according to this application is shown;

[0044] Figure 7A , Figure 7B , Figure 7C , Figure 7D The operation modes of the brake fluid in the brake fluid drive circuit are shown respectively when the hydraulic braking devices of different wheels need to be activated;

[0045] Figure 8 A flowchart illustrating a brake friction pad wear monitoring method according to an embodiment of this application is shown schematically.

[0046] Figure 9 A flowchart illustrating a brake friction pad wear monitoring method according to another embodiment of this application is shown schematically;

[0047] Figure 10A and Figure 10B The figure shows the experimental results, illustrating the results of detecting the wear of motor vehicle brake friction pads using the motor vehicle brake friction pad wear detection system and method of this application. Detailed Implementation

[0048] In the accompanying drawings of this application, features with the same structure or similar function are indicated by the same reference numerals.

[0049] Figure 1 A simplified schematic diagram of a motor vehicle 100 is shown, wherein the motor vehicle has four wheels: a left front wheel FL, a right front wheel FR, a left rear wheel RL, and a right rear wheel RR. A hydraulic braking device FLB, FRB, RLB, or RRB is provided for each of the left front wheel FL, right front wheel FR, left rear wheel RL, and right rear wheel RR. These hydraulic braking devices may be part of the hydraulic braking system of the motor vehicle 100. For example, the hydraulic braking system may also include a brake fluid reservoir 300 and a brake fluid drive circuit 210 fluidly connected to the brake fluid reservoir 300, wherein the brake fluid drive circuit 210 is fluidly connected to each hydraulic braking device FLB, FRB, RLB, or RRB to drive the hydraulic braking device FLB, FRB, RLB, or RRB to perform braking action.

[0050] Figure 2 A simplified schematic diagram of the hydraulic braking device FLB is shown here, using only one example. Those skilled in the art will understand that the construction principles and / or operating methods of other hydraulic braking devices FRB, RLB, and RRB are similar. Figure 2 Similar to the example shown. The hydraulic braking device FLB includes a brake disc 500, which is mounted so as not to rotate relative to the wheel FL, and both have a common central axis of rotation O. That is, as the wheel FL rotates, the brake disc 500 is correspondingly driven along with the wheel FL. Figure 1The brakes rotate together about a central axis of rotation O. The hydraulic braking system FLB also includes a brake caliper 600. The brake caliper 600 is mounted on a portion of the vehicle's suspension (not shown) in a manner that prevents it from rotating relative to the wheel FL or the brake disc 500, and at least partially surrounds the brake disc 500. A pair of brake pads 700 are mounted on the brake caliper 600 and are located on opposite axial sides of the brake disc 500. In addition, a hydraulic brake cylinder assembly 800 is fixedly mounted on the brake caliper 600. For example, the hydraulic brake cylinder assembly 800 includes a cylinder body 810 fixedly mounted relative to the brake caliper 600 and a brake piston 820 axially movable within the cylinder body 810. The brake piston 820 can interact with one of the brake pads 700, such that when the brake piston 820 is subjected to hydraulic pressure and pushes the brake pad 700, the pair of brake pads 700 can approach each other and contact opposite axial surfaces of the brake disc 500 under the action of the brake caliper 600. Because the brake caliper 600 and each brake friction pad 700 are mounted in a manner that prevents them from rotating relative to the brake disc 500, the brake friction pads 700 in contact with the brake disc 500 will apply a frictional braking force to the brake disc 500. As the hydraulic pressure driving the brake piston 820 reaches a certain level, it ultimately ensures that the brake disc 500 stops rotating or reduces its speed, thus achieving braking of the wheel FL. When wheel braking is not required, as the hydraulic pressure is unloaded from the brake piston 820, the brake friction pads 700 move away from each other under the action of a return spring (not shown in the figure) installed in the brake caliper 600, allowing the wheel FL to rotate freely without the frictional braking force. Because the hydraulic braking device FLB is fluidly connected to the brake fluid drive circuit 210, the hydraulic pressure driving the brake piston 820 is provided by the brake fluid drive circuit 210.

[0051] Because the hardness of the friction material on brake pads is less than that of the brake disc 500 or the surface hardness of the brake disc 500, the friction material on the brake pads will wear down and become thinner with increased vehicle usage time and frequency. Once the friction material on the brake pads is worn away, it will no longer be able to provide sufficient frictional braking force to the brake disc when the wheels need to brake. Therefore, after installing new brake pads, it is necessary to measure the thickness of the brake pads regularly to understand the wear condition of the friction material.

[0052] Figure 3 This is a simplified diagram showing the interaction between a brand new friction pad and a friction pad that has been worn down to a certain thickness, and the brake disc. For clarity, in... Figure 3Only the brake friction pads 700 located on one side of the brake disc 500 are shown, with the upper brake friction pad 700 in its brand-new condition and the lower brake friction pad 700 in its condition after a certain period of use. Figure 3 This diagram illustrates the positions of a brand-new brake pad 700 (upper part) and a brake pad 700 with a certain degree of wear (lower part) when the same frictional braking force is applied to the brake disc 500. For example, suppose a motor vehicle's hydraulic braking system (FLB) has newly installed brake pads 700. Figure 3 The top view in the diagram can represent the position of the brake friction pad 700 when a braking force is applied to the brake disc 500, while Figure 3 The lower view in the image can represent the position of the brake friction pad 700 when the same braking force is applied to the brake disc via the brake friction pad 700 after the vehicle has traveled a certain distance (e.g., 50,000 kilometers).

[0053] If we ignore the volume deformation of the brake friction pad 700 itself under pressure, then when the same braking force is applied to the brake disc 500 through the brake friction pad 700, the thickness h0 of a brand new brake friction pad 700 and the thickness h of a brake friction pad 700 with a certain degree of wear will be different. p The following relationship exists between them:

[0054] h p =h0-H w

[0055] Among them, H w This represents the amount of thickness reduction for the same brake friction pad.

[0056] When applying wheel braking, the hydraulic brake cylinder assembly 800 must build up brake fluid pressure (i.e., the hydraulic pressure driving the brake piston 820) until the brake fluid pressure reaches a level sufficient to provide wheel braking. During this process, as the brake piston 820 drives the brake friction pads 700 to contact the brake disc 500, the brake piston 820 experiences a gradual increase in the hydraulic pressure it provides. Viewed from the perspective of the brake fluid drive circuit 210, the hydraulic pressure within the hydraulic circuit connected to the brake piston 820 gradually increases. Figure 4 The process of increasing hydraulic pressure is shown for both brand-new brake friction pads 700 and brake friction pads 700 after a certain period of time. Line 1 represents the process of increasing hydraulic pressure corresponding to brand-new brake friction pads 700, and line 2 represents the process of increasing hydraulic pressure corresponding to brake friction pads 700 after a certain period of time.

[0057] Due to the action of a return spring (not shown), during each wheel braking operation, the brake piston 820 always starts to move from the same position measured within the cylinder block 810. In the initial stage of the movement of the brake piston 820, under the action of the brake fluid pumped within the brake fluid drive circuit 210, the brake piston 820 drives the brake friction pad 700 to move towards the brake disc 500. If the brake friction pad 700 has not yet contacted the brake disc 500, the hydraulic pressure within the relevant hydraulic circuit portion is almost zero. From the moment the brake friction pad 700 contacts the brake disc 500, since the brake piston 820 will be blocked because the brake friction pad 700 cannot move further, as the pumping action intensifies, the hydraulic pressure within the relevant hydraulic circuit portion will gradually increase, correspondingly causing the frictional braking force exerted by the brake friction pad 700 on the brake disc 500 to also increase. When this hydraulic pressure increases to a certain extent, it can be considered that the frictional braking force exerted by the brake friction pad 700 on the brake disc 500 has reached an expected value (for example, this expected value is consistent with the braking intention of the motor vehicle driver, such as stopping or decelerating the motor vehicle, without triggering the anti-lock function of the motor vehicle). At this time, the pumping action of the brake fluid can be stopped to maintain this hydraulic pressure and maintain the braking of the brake friction pad 700 on the brake disc 500. Therefore, in Figure 4 each line at t = 0 corresponds to the moment when the brake friction pad 700 just contacts the brake disc �00. In Figure 4 when the hydraulic pressure reaches the same P0 (for example, P0 = 50 bar), lines 1 and 2 respectively require times t1 and t2, and t1 < t2. This difference in time is obviously due to the reduction in the thickness of the brake friction pad 700. The above P0 can be represented as the same braking force exerted on the brake disc 500 when interpreting Figure 3 .

[0058] Turning to observe Figure 3 , it should first be clear that both the upper brake friction pad 700 and the lower brake friction pad 700 are in the state when the same braking force is exerted on the brake disc 500 through them respectively. Obviously, due to the existence of the thickness wear amount H w of the brake friction pad 700, in order to achieve the same braking force, the axial position of the brake piston 820 within the cylinder block 810 changes.

[0059] Assuming that for a brand-new brake friction pad 700 (top), when the same braking force is applied to the brake disc 500, the axial distance H0 of the brake piston 820 relative to the cylinder 810 at the initial braking position (this position is a reference position and is fixed for each hydraulic brake cylinder assembly 800); and for a brake friction pad 700 (bottom) with a certain degree of wear, when the same braking force is applied to the brake disc 500, the axial distance H of the brake piston 820 relative to the cylinder 810 at the initial braking position is... cyl .

[0060] Since the axial dimension of the brake piston 820 itself can be considered constant, the two axial distances of the brake piston 820 mentioned above should satisfy the following relationship:

[0061] H cyl = H0+H w

[0062] Among them, H w This refers to the wear amount of the 700mm thickness of the brake friction pad. It should be clear that the above H... w This can precisely reflect the difference between the volume of brake fluid contained in the cylinder 810 for a brand new brake friction pad and the volume of brake fluid contained in the cylinder 810 for a brake friction pad that has been worn to a certain extent, when the same braking force is applied to the brake disc 500 via the brake friction pad.

[0063] Further reference Figure 4 Assuming the same braking force reflecting P0 should be applied to Figure 3 On the brake disc 500 shown, the volume of brake fluid injected into the cylinder 810 should be: (This is applicable to both brand new brake pads and brake pads that have undergone some wear.)

[0064] ΔV = A•Q•t,

[0065] Where A refers to the cross-sectional area of ​​the valve orifice of the inlet valve (not shown) that supplies hydraulic brake fluid to the relevant hydraulic circuit section, Q refers to the brake fluid flow rate (i.e., the volume of brake fluid flowing through a unit area per unit time), and t represents, for example... Figure 4 The time shown is from time 0 to the time represented by P0. Here, A and Q can be determined in advance, and t can be measured by the corresponding sensor.

[0066] If the inner wall of cylinder 810 is considered to be an ideal cylinder, then the brake piston 820 moves from the initial braking position to... Figure 3 The change in internal volume of cylinder 810 at the position shown is V = ¼•πD 2 • H and D are the inner diameters of cylinder 810, and H is the distance the brake piston 820 moves from its initial braking position to its final position. Figure 3 The axial distance at the position shown.

[0067] For brake friction pad 700 that has undergone a certain degree of wear, the aforementioned H is replaced by H. cyl Then V = ¼•πD 2 •H cyl Where D is the inner diameter of cylinder 810.

[0068] The compressibility coefficient of brake fluid is β=ΔV / (p•V), where p is the hydraulic pressure.

[0069] Therefore, the thickness of the brake friction pad 700 after a certain degree of wear should be:

[0070] h p = H0 + h0 - (4AQ / πD) 2 •β•p)•t (1)

[0071] It can be seen that, according to formula (1), the actual thickness of the final brake friction pad 700 after a period of use is mainly related to the variable t. That is, if the hydraulic braking device associated with each wheel can be controlled independently, and the time required to build up the braking force when the same braking force is applied to the brake disc can be measured, the actual thickness of the brake friction pad can be determined accordingly. Furthermore, even without precisely determining the actual thickness of the brake friction pad, the difference between the time required for a brand-new brake friction pad to build up the braking force and the time required for a brake friction pad to build up the same braking force after a certain period of use, when the same braking force is applied to the brake disc, can be used to estimate whether a new brake friction pad needs to be replaced. Those skilled in the art should understand that, according to... Figure 3 As shown, h in formula (1) p This refers to the thickness of the brake friction pad 700 located near the brake piston 820 of the hydraulic brake cylinder assembly 800. Within the brake caliper 600, another brake friction pad 700 is installed across the brake disc 500 from this brake friction pad 700. These two brake friction pads 700 are considered to have the same wear condition, i.e., the same thickness of wear. Therefore, h in formula (1) p It can also be used to refer to the thickness of the other brake friction pad 700.

[0072] Figure 5A vehicle brake pad wear detection system according to an embodiment of this application is illustrated schematically. As shown, the vehicle brake pad wear detection system generally includes a central electronic control unit 1000 and a hydraulic braking system as mentioned above, wherein the hydraulic braking system includes a brake fluid reservoir 300, a brake fluid drive circuit 210 fluidly connected to the brake fluid reservoir 300, and a hydraulic braking device FLB, FRB, RLB, or RRB fluidly connected to and driven by the brake fluid drive circuit 210. Alternatively and / or additionally, the vehicle brake pad wear detection system may include a recording module. For example, the recording module can be connected to the central electronic control unit 1000. The recording module can be configured to record the time required for the hydraulic braking device to build up brake hydraulic pressure, particularly when the vehicle is stationary. Thus, the central electronic control unit 1000 can be configured to compare the recorded time required to build up brake hydraulic pressure with the time required to build up brake hydraulic pressure of the same hydraulic braking device when the brake pads are newly installed, to determine the wear state of the brake pads.

[0073] Furthermore, the brake fluid drive circuit 210 is also fluidly connected to the brake pedal 400. In the context of this application, the term "fluid connection" means that two features are connected in a manner capable of transmitting fluid to each other, which can be a direct connection or a connection via a conduit for transmitting fluid. The term "data connection" means that two features are connected in a manner capable of transmitting electronic data or signal data to each other, for example, via any suitable connection device such as a cable. Based on the actuation input of the brake pedal 400, the brake fluid drive circuit 210 can drive the various hydraulic braking devices FLB, FRB, RLB, and RRB to brake all wheels.

[0074] The central electronic control unit 1000 is configured to generate signals for independently controlling the operation of the brake fluid drive circuit 210. Figure 6 A simplified example of a brake fluid drive circuit 210 is shown. Those skilled in the art will understand that this simplified example of the brake fluid drive circuit 210 is given for illustrative purposes only, and the brake fluid drive circuit of this application should not be limited to such a simplified example. Figure 6 The configuration shown is as follows. As shown in the figure, the brake fluid drive circuit 210 generally includes a hydraulic master pump 211, a fluid network, and other related components. The fluid network fluidly connects the hydraulic master pump 211 and the valve control device. Simultaneously, each hydraulic braking device (FLB, FRB, RLB, and RRB) is also fluidly connected to the fluid network.

[0075] Furthermore, the brake fluid reservoir 300 is connected to a fluid piping network. In the context of this application, the term "operational connection" refers to a connection where the action of one of two interconnected features causes a specific operation of the corresponding other feature. Here, when the brake pedal 400 is pressed, the brake fluid in the brake fluid drive circuit 210 flows in a controlled manner, thereby driving the hydraulic braking devices FLB, FRB, RLB, and RRB via the fluid piping network. Specifically, multiple solenoid valves are installed where necessary within the fluid piping network. Figure 6 The symbol EV is used to represent them. The aforementioned central electronic control unit 1000 can be data-connected to these solenoid valves EV respectively, and can control the on / off state of one or more of them as needed, thereby creating a relevant hydraulic circuit section in the fluid network of the brake fluid drive circuit 210 that establishes a fluid connection between only one of the hydraulic braking devices FLB, FRB, RLB and RRB and the hydraulic master pump 211 as needed.

[0076] Figure 7A , 7B Figures 7C and 7D show different hydraulic circuit portions defined in the fluid network of the brake fluid drive circuit 210, respectively, which are configured such that the hydraulic master pump 211 establishes a fluid connection only with the hydraulic braking devices FLB, FRB, RLB, or RRB, wherein... Figure 7A The hydraulic circuit portion that establishes a fluid connection between the hydraulic master pump 211 and the hydraulic brake unit FLB is shown. Figure 7B The hydraulic circuit portion that establishes a fluid connection between the hydraulic master pump 211 and the hydraulic braking device FRB is shown. Figure 7C The hydraulic circuit portion that establishes a fluid connection between the hydraulic master pump 211 and the hydraulic braking device RLB is shown. Figure 7D The diagram shows the hydraulic circuit portion that establishes a fluid connection between the hydraulic master pump 211 and the hydraulic brake unit RRB. The bold lines in each figure represent these hydraulic circuit portions. It can be seen that a pressure sensor 213 is installed within the fluid network of the brake fluid drive circuit 210. The pressure sensor 213 is configured to measure the hydraulic pressure within any hydraulic circuit portion, regardless of which portion is being measured. Simultaneously, the pressure sensor 213 is connected to the central electronic control unit 1000, enabling the transmission of measurement results to the central electronic control unit 1000 for processing.

[0077] Figure 8A flowchart illustrating a brake pad wear monitoring method according to an embodiment of this application is shown schematically. Those skilled in the art will understand that any method or process described herein can be encoded as program code executable by a computer or computer and stored in the memory of the central electronic control unit 1000, so that it can be conveniently invoked and executed by the computing unit of the central electronic control unit 1000 or the vehicle computer.

[0078] like Figure 8 As shown, in step S10, it is first confirmed whether the vehicle is equipped with brand new brake pads. For example, this can be automatically confirmed before the new vehicle leaves the factory, or manually confirmed by inputting a command to the central electronic control unit 1000 after the new brake pads are manually installed later in the vehicle. Furthermore, in step S10, the thickness of the new brake pads can be automatically recorded when the new vehicle leaves the factory, or manually inputted and recorded into the central electronic control unit 1000 during the manual installation of the new brake pads.

[0079] In step S20, after the vehicle has been safely and reliably parked, the fluid network of the brake fluid drive circuit 210 is connected to the fluid lines as follows: Figure 7A , 7B The hydraulic circuit portion of the master pump 211 is individually switched on in a manner similar to 7C or 7D, such that it establishes a fluid connection only with the hydraulic braking devices FLB, FRB, RLB, or RRB. Then, the time required for each hydraulic braking device to build up brake hydraulic pressure is recorded separately. In the context of this application, the term "time required to build up brake hydraulic pressure" refers to the time elapsed for a given hydraulic braking device, from the moment the brake pads begin to contact the brake disc until the brake pads have applied a specified braking friction force (corresponding to the hydraulic pressure of the piston driving the brake pads) on the brake disc. This time can be measured using any existing sensing device configured in the motor vehicle. For example, "time required to build up brake hydraulic pressure" in... Figure 4 The values ​​can be represented as t1 and t2.

[0080] In step S30, using the time required to establish the braking hydraulic pressure obtained in step S20, the current thickness (i.e., h) of the brake friction pads of the corresponding hydraulic braking device is calculated using formula (1). p ( ) or the wear amount of the brake friction pad thickness. Those skilled in the art should understand that steps S20 and S30 can be performed only after the vehicle has traveled a certain mileage, such as 5000-20000 kilometers, thus reducing the computational burden on the central electronic control unit 1000. Furthermore, in the technical solution of this application, the current thickness of the brake friction pad (i.e., h) pAlternatively, the thickness and wear of the brake friction pads can be determined by performing steps S20 and S30 multiple times after stopping the vehicle and averaging the results. This ensures that the accuracy of the final calculation result meets the appropriate requirements.

[0081] Next, in step S40, the current thickness (i.e., h) of the brake friction pad obtained in step S30 is... p The thickness of the brake pads is compared with the thickness of the new brake pads recorded in step S10. If the difference between them is greater than a predetermined value, the corresponding brake pads are considered to need to be replaced. In this case, the driver can be reminded to replace the brake pads, for example, through an in-vehicle display and / or an audible alarm. Alternatively or supplementarily, in step S40, it can also be determined whether the wear of the brake pad thickness is greater than a predetermined value. If so, the driver can also be reminded to replace the brake pads, for example, through an in-vehicle display and / or an audible alarm.

[0082] Although the above method embodiment utilizes formula (1) to solve for the current thickness (i.e., h) of the brake friction pad. p The wear condition of brake friction pads can be judged by the thickness of the wear pads. However, those skilled in the art should know that the difference in the time required to build up brake hydraulic pressure between brand new brake friction pads and brake friction pads that have been used for a certain period of time can also be used to determine whether the brake friction pads need to be replaced.

[0083] For example, Figure 9 A flowchart illustrating a brake pad wear monitoring method according to another embodiment of this application is shown. In step S11, it is first confirmed whether the vehicle is equipped with brand new brake pads, for example, this can be achieved by manually inputting commands to the central electronic control unit 1000 through a suitable in-vehicle display interface or input device.

[0084] In step S21, assuming the vehicle is equipped with brand-new brake pads, the hydraulic circuit portion established in the fluid network of the brake fluid drive circuit 210, fluidly connected to the hydraulic master pump 211, for each individual hydraulic braking device (FLB, FRB, RLB, or RRB) in a manner similar to that described in step S20, is recorded, and the time required for each hydraulic braking device to establish brake hydraulic pressure is recorded. For example, the "time required to establish brake hydraulic pressure" can be obtained by recording the results after the vehicle has stopped multiple times or a specific number of times consecutively, and then taking the average, thereby improving the accuracy of the time required to establish brake hydraulic pressure.

[0085] In step S31, it is determined whether the vehicle has traveled a certain mileage, for example, whether it has traveled 5,000 to 20,000 kilometers since step S21. If the result of step S31 is no, the process continues to wait. If the result of step S31 is yes, the process proceeds to step S41. In step S31, the time required for each individual hydraulic braking device to build up brake hydraulic pressure is recorded in a manner similar to step S21. Here, the record mentioned in step S31 can be the average of the results recorded after the vehicle has stopped multiple times within a certain period or a short distance (e.g., 100 to 300 kilometers).

[0086] In step S41, the hydraulic circuit portion established in the fluid network of the brake fluid drive circuit 210 for each individual hydraulic braking device (FLB, FRB, RLB, or RRB) in a manner similar to that described in step S20 is recorded, connecting it to the hydraulic master pump 211. The time required for each hydraulic braking device to establish brake hydraulic pressure is also recorded. Here, the records mentioned in step S41 can be the average of the results recorded after the vehicle has stopped multiple times over a period of time or a short distance (e.g., 100-300 km).

[0087] In step S51, the time required to establish brake hydraulic pressure recorded in step S21 is compared with the time required to establish brake hydraulic pressure recorded in step S41. If the difference between the two exceeds a specific value, it is considered that the wear of the pair of brake pads corresponding to the excessive difference has exceeded the standard and needs to be replaced. At this time, the driver can be reminded to replace the brake pads, for example, through an in-vehicle display interface and / or an audible alarm. If the comparison result of step S51 indicates that the difference is not excessive, the process proceeds to step S31 to restart monitoring of each brake pad of the hydraulic braking system FLB, FRB, RLB, or RRB. For example, when restarting monitoring in step S31, it can be specified that monitoring will be performed after the vehicle has traveled 1000-2000 kilometers.

[0088] Those skilled in the art should understand that the steps of the above-mentioned method embodiments can be used in combination with each other, and they are given for illustrative purposes only and do not constitute any limitation on the scope of this application. Furthermore, those skilled in the art should also understand that in the method process explained above, after step S40 or S51, the fluid network of the brake fluid drive circuit 210 should be reset to its factory state, thereby ensuring that the motor vehicle can be driven normally as usual.

[0089] Figure 10A and 10B The diagram shows the results of monitoring the brake friction pads of a motor vehicle using the method or system described above in this application, thereby illustrating the feasibility of the technical solution of this application. Figure 10A and 10B The four columns represent the brake fluid volume within cylinder 810 when the same P0 (=50 bar) is achieved, calculated using the previously mentioned formula. Specifically, for Figure 10A The process involves first replacing all the brake pads of the hydraulic braking devices corresponding to the four wheels with brand new brake pads, and then determining the brake fluid volume in the cylinder 810 for each wheel's brake disc when the same braking force is applied; then replacing the brake pads of the hydraulic braking device FRB with brake pads that have been worn by 5mm, and then determining the brake fluid volume in the cylinder 810 for each wheel's brake disc when the same braking force is applied. Figure 10A The darker sections in each column represent the calculated volume difference values, which are indicated above each dark section. For Figure 10B The process involves first replacing all the brake pads of the hydraulic braking devices corresponding to the four wheels with brand new brake pads, and then determining the brake fluid volume in the cylinder 810 for each wheel's brake disc when the same braking force is applied; then replacing the brake pads of the hydraulic braking device RRB with brake pads that have been worn by 5mm, and then determining the brake fluid volume in the cylinder 810 for each wheel's brake disc when the same braking force is applied. Figure 10B The darker areas in each column represent the calculated volume difference values.

[0090] from Figure 10A and 10B It can be seen that, for hydraulic braking systems FRB and RRB with altered worn brake pads, the determined difference in brake fluid volume is very significant and sufficient to distinguish them. Therefore, this demonstrates that the method or system of this application is reliable and feasible for monitoring the brake pads of motor vehicles. It should be noted that, in Figure 10A and 10B In the case of hydraulic braking devices where brake pads have not been replaced, although there are differences in brake fluid volume, this is only due to the overlap of different hydraulic circuits established in the fluid pipeline network and does not affect the monitoring results of the system and method of this application for worn brake pads.

[0091] Although specific embodiments of this application are described in detail herein, they are provided for illustrative purposes only and should not be construed as limiting the scope of this application. Furthermore, those skilled in the art will understand that the various embodiments described herein can be used in combination with each other. Various substitutions, modifications, and alterations can be conceived without departing from the spirit and scope of this application.

Claims

1. A system for monitoring the wear of a brake friction plate of a motor vehicle, wherein, The motor vehicle comprises hydraulic braking devices acting on its wheels, said hydraulic braking devices having a braking disc rotating with the wheel and a braking friction sheet not rotatable with respect to the braking disc but linearly movable parallel to the rotation axis of the braking disc, characterized in that the braking friction sheet wear monitoring system comprises: - a recording module to record the time needed to establish the braking hydraulic pressure of the hydraulic braking device in the case of the motor vehicle at standstill; - a central electronic control unit in data connection with the recording module to compare the recorded time needed to establish the braking hydraulic pressure with the recorded time needed to establish the braking hydraulic pressure of the same hydraulic braking device in the case of new braking friction sheet to determine the wear state of the braking friction sheet.

2. The brake pad wear monitoring system of claim 1, wherein, The central electronic control unit generates an instruction to inhibit the operation of the hydraulic braking devices of the other wheels of the motor vehicle when the recording module records for the hydraulic braking device of one wheel of the motor vehicle.

3. A brake pad wear monitoring system according to claim 1 or 2, characterised in that, The recorded time needed to establish the braking hydraulic pressure is the average of the results of several recordings of the corresponding hydraulic braking device.

4. A brake pad wear monitoring system according to claim 3, characterised in that, The recorded time needed to establish the braking hydraulic pressure of the same hydraulic braking device in the case of new braking friction sheet is the average of the results of several recordings of this hydraulic braking device.

5. The brake pad wear monitoring system of claim 1 or 2, wherein The recording module operates after a certain mileage of the motor vehicle and in the case of the motor vehicle at standstill to record the time needed to establish the braking hydraulic pressure of the hydraulic braking device.

6. The brake pad wear monitoring system of claim 1 or 2, wherein The motor vehicle comprises a brake fluid drive circuit (210) and a brake fluid tank (300) in fluid connection with the brake fluid drive circuit (210), the brake fluid drive circuit (210) comprising a hydraulic main pump (211) and a fluid pipe network having a hydraulic circuit portion which only brings the hydraulic braking device in question into fluid connection with the hydraulic main pump (211) when the time needed to establish the braking hydraulic pressure is to be recorded for this hydraulic braking device.

7. A brake pad wear monitoring system according to claim 6, wherein A pressure sensor (213) is provided in the fluid pipe network to measure the brake fluid pressure in the hydraulic circuit portion to determine whether the braking hydraulic pressure is established.

8. A brake pad wear monitoring system for a motor vehicle, wherein, The motor vehicle comprises hydraulic braking devices acting on its wheels, said hydraulic braking devices having a braking disc rotating with the wheel and a braking friction sheet not rotatable with respect to the braking disc but linearly movable parallel to the rotation axis of the braking disc, said braking friction sheet being moved by a hydraulic brake cylinder assembly driven by a hydraulic brake cylinder assembly, characterized in that the braking friction sheet wear monitoring system comprises: - a recording module to record the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly for establishing the braking hydraulic pressure of the hydraulic braking device in the case of the motor vehicle at standstill; - a central electronic control unit in data connection with the recording module to compare the recorded volume of brake fluid injected into the cylinder with the recorded volume of brake fluid injected into the same cylinder in the case of new braking friction sheet to determine the wear state of the braking friction sheet.

9. The brake pad wear monitoring system of claim 8, wherein, The central electronic control unit generates an instruction to disable the hydraulic brake devices of the other wheels of the motor vehicle when the recording module is recording the hydraulic brake device of one wheel of the motor vehicle.

10. A motor vehicle, characterized in that The motor vehicle comprises a brake pad wear monitoring system according to any one of claims 1 to 9.

11. A method of monitoring the wear of a brake friction plate of a motor vehicle, wherein, The motor vehicle comprises hydraulic brake devices acting on its wheels, the hydraulic brake devices having a brake disc rotating with the wheel and a brake pad that is not rotatable with respect to the brake disc but is linearly movable parallel to the rotation axis of the brake disc, the method comprising: - recording the time required to establish the brake hydraulic pressure of the hydraulic brake device when the motor vehicle is stationary; - comparing the recorded time required to establish the brake hydraulic pressure with the time required to establish the brake hydraulic pressure of the same hydraulic brake device recorded when the brake pad is new, to determine the wear state of the brake pad.

12. The method of claim 11, wherein, The hydraulic brake devices of the other wheels of the motor vehicle are disabled when recording the hydraulic brake device of one wheel of the motor vehicle.

13. The method according to claim 11 or 12, characterized in that, The recorded time required to establish the brake hydraulic pressure is the average of the results of several recordings of the corresponding hydraulic brake device.

14. The method of claim 13, wherein, The recorded time required to establish the brake hydraulic pressure of the same hydraulic brake device when the brake pad is new is the average of the results of several recordings of the hydraulic brake device.

15. The method of claim 11 or 12, wherein, The motor vehicle comprises hydraulic brake devices acting on its wheels, the hydraulic brake devices having a brake disc rotating with the wheel and a brake pad that is not rotatable with respect to the brake disc but is linearly movable parallel to the rotation axis of the brake disc, the method comprising:

16. The method of claim 11 or 12, wherein, - recording the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly for establishing the brake hydraulic pressure of the hydraulic brake device when the motor vehicle is stationary; 17. The method of claim 16, wherein, - comparing the recorded volume of brake fluid injected into the cylinder with the volume of brake fluid injected into the same cylinder recorded when the brake pad is new, to determine the wear state of the brake pad.

18. A method of monitoring the wear of a brake friction plate of a motor vehicle, wherein, The hydraulic brake devices of the other wheels of the motor vehicle are disabled when recording the hydraulic brake device of one wheel of the motor vehicle. The recorded volume of brake fluid injected into the cylinder is the average of the results of several recordings of the corresponding hydraulic brake cylinder assembly. The recorded volume of brake fluid injected into the same cylinder when the brake pad is new is the average of the results of several recordings of the hydraulic brake cylinder assembly.

19. The method of claim 18, wherein, The motor vehicle comprises hydraulic brake devices acting on its wheels, the hydraulic brake devices having a brake disc rotating with the wheel and a brake pad that is not rotatable with respect to the brake disc but is linearly movable parallel to the rotation axis of the brake disc, the method comprising: - recording the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly for establishing the brake hydraulic pressure of the hydraulic brake device when the motor vehicle is stationary; - comparing the recorded volume of brake fluid injected into the cylinder with the volume of brake fluid injected into the same cylinder recorded when the brake pad is new, to determine the wear state of the brake pad. The hydraulic brake devices of the other wheels of the motor vehicle are disabled when recording the hydraulic brake device of one wheel of the motor vehicle.

20. A brake pad wear monitoring system for a motor vehicle, comprising: a central electronic control unit configured to control a hydraulic brake device of the motor vehicle and a brake fluid driven circuit for operating the hydraulic brake device, characterized in that the central electronic control unit is configured to perform the method according to any one of claims 11 to 19.

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