CN216789068U - Motor vehicle and brake friction plate loss monitoring system thereof - Google Patents
Motor vehicle and brake friction plate loss monitoring system thereof Download PDFInfo
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- CN216789068U CN216789068U CN202123049560.0U CN202123049560U CN216789068U CN 216789068 U CN216789068 U CN 216789068U CN 202123049560 U CN202123049560 U CN 202123049560U CN 216789068 U CN216789068 U CN 216789068U
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Abstract
The application discloses motor vehicle and brake lining loss monitoring system thereof, wherein, the motor vehicle includes the hydraulic braking device who acts on its wheel, hydraulic braking device has the brake disc that rotates with the wheel and for the brake disc is nonrotatable but can be on a parallel with the brake disc's rotation axis rectilinear movement's brake lining, utilize the system: recording the time required by the hydraulic brake device to establish a braking hydraulic pressure in the event of a stationary motor vehicle; the recorded time required to establish the brake hydraulic pressure is compared with the recorded time required to establish the brake hydraulic pressure of the same hydraulic brake device in the case where the brake lining is newly installed, to determine the worn state of the brake lining.
Description
Technical Field
The present application relates generally to a system and method for brake pad wear monitoring of a motor vehicle.
Background
The braking device is a mandatory device on motor vehicles according to the requirements of road traffic regulations. The brake device essentially comprises a brake disc mounted so as to be rotatable with the rim of the wheel and a friction lining mounted so as to be immovable relative to the rim. For each brake disc, the friction plates are, for example, two friction plates, which are mounted with a certain clearance on opposite sides of the corresponding brake disc, and which are driven by a drive mechanism so as to be able to move in contact with the rotating brake disc and apply a clamping force thereto, so that the brake disc stops moving due to friction braking.
Generally, the hardness of the brake disc is higher than that of the friction plate. Therefore, the thickness of the friction plate is worn and reduced with long-term braking. In order to ensure that sufficient frictional braking force can be generated, it is necessary to replace the friction plates with new ones in time after the friction plate wear has been reduced to a certain extent. Thus, wear of the friction plates needs to be monitored.
One conventional friction lining monitoring measure is to provide a metal plate on the back plate of the friction lining, the metal plate having a free end adjacent to the wear surface of the friction lining (i.e., the surface that contacts the brake disc), with the free end being set back from the wear surface by a distance in the thickness direction of the friction lining. Under normal circumstances, the free end of the metal plate is spaced from the brake disc when the friction plate is in contact with the brake disc for wheel braking. However, when the wear of the friction plate is reduced to a certain extent and then the wheel is braked, the free end of the metal plate will contact with the rotating brake disc and generate sharp noise, thereby reminding the driver of needing to replace the new friction plate. The disadvantage of this type of wear monitoring of the friction lining is that the driver cannot detect the degree of wear of the friction lining before the occurrence of a sharp noise. Furthermore, the frictional contact of the metal sheet with the brake disc can also lead to damage of the brake disc.
Another conventional friction lining monitoring measure is to provide the friction lining with a corresponding sensor, so as to monitor the wear state of the friction lining as required. However, on one hand, the difficulty of designing the overall structure of the suspension and the difficulty of wiring are increased due to the arrangement of the sensor, and on the other hand, the cost of parts and the cost of design and assembly are increased correspondingly.
SUMMERY OF THE UTILITY MODEL
In view of the above problems, the present application aims to provide a simple and easy brake friction plate loss monitoring measure, so that the loss condition of the brake friction plate can be conveniently monitored on the premise of not increasing significant cost or changing the existing motor vehicle suspension design, and a corresponding guarantee is provided for safe driving of the motor vehicle.
According to one aspect of the present application, there is provided a brake pad loss monitoring system for a motor vehicle, wherein the motor vehicle comprises a hydraulic brake device acting on a wheel thereof, the hydraulic brake device having a brake disc rotating with the wheel and a brake pad non-rotatable with respect to the brake disc but linearly movable parallel to an axis of rotation of the brake disc, characterized in that the brake pad loss monitoring system comprises:
a recording module to record a time required for the hydraulic brake device to establish a braking hydraulic pressure in a case where the motor vehicle is stationary;
a central electronic control unit in data connection with the recording module for comparing the recorded time required for establishing the brake hydraulic pressure with the recorded time required for establishing the brake hydraulic pressure of the same hydraulic brake device in the case of a new installed brake lining for determining the wear state of the brake lining.
Optionally, when the recording module records a hydraulic brake device of one wheel of the motor vehicle, the central electronic control unit generates a command for disabling the hydraulic brake devices of the other wheels of the motor vehicle.
Alternatively, the recorded time required for establishing the brake hydraulic pressure is an average of the results of a plurality of recordings made to the respective hydraulic brake device.
Alternatively, the time required for the same hydraulic brake device to establish the braking hydraulic pressure recorded in the case where the brake lining is newly installed is an average value of the results of the plurality of times of recording performed by the hydraulic brake device.
Optionally, the recording module is operated after a certain distance of travel of the motor vehicle and in the event of a stationary motor vehicle to record the time required for the hydraulic brake device to build up a braking hydraulic pressure.
Optionally, the motor vehicle comprises a brake fluid drive circuit comprising a hydraulic main pump and a fluid pipe network having a hydraulic circuit portion which, when the time required for establishing a brake hydraulic pressure needs to be recorded for a hydraulic brake device, only connects the hydraulic brake device in fluid connection with the hydraulic main pump, and a brake fluid tank in fluid connection with the brake fluid drive circuit.
Optionally, a pressure sensor is provided within the fluid line network to measure brake fluid pressure within the hydraulic circuit portion to determine whether brake fluid pressure is established.
According to another aspect of the present application, there is also provided a brake lining wear monitoring system for a motor vehicle, wherein the motor vehicle comprises a hydraulic brake device acting on a wheel of the motor vehicle, the hydraulic brake device having a brake disc rotating with the wheel and a brake lining non-rotatable with respect to the brake disc but linearly displaceable parallel to an axis of rotation of the brake disc, the brake lining being displaceable by actuation of a hydraulic brake cylinder assembly, characterized in that the brake lining wear monitoring system comprises:
a recording module for recording the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly by the hydraulic brake device for establishing a braking hydraulic pressure when the motor vehicle is stationary;
a central electronic control unit in data connection with the recording module to compare the recorded volume of brake fluid injected into a cylinder with the recorded volume of brake fluid injected into the same cylinder in the event of a new brake pad installation to determine the wear state of the brake pad.
Optionally, when the recording module records a hydraulic brake device of one wheel of the motor vehicle, the central electronic control unit generates a command for disabling the hydraulic brake devices of the other wheels of the motor vehicle.
According to another aspect of the application, there is also provided a motor vehicle comprising a brake pad wear monitoring system as described in any one of the preceding.
According to an aspect of the present application, there is also provided a brake pad wear monitoring method for a motor vehicle, wherein the motor vehicle comprises a hydraulic brake device acting on a wheel thereof, the hydraulic brake device having a brake disc rotating with the wheel and a brake pad non-rotatable with respect to the brake disc but linearly movable parallel to an axis of rotation of the brake disc, the method comprising:
recording the time required by the hydraulic brake device to establish a braking hydraulic pressure in the event of a stationary motor vehicle;
the recorded time required to build up the braking hydraulic pressure is compared with the recorded time required to build up the braking hydraulic pressure of the same hydraulic brake device in the case of a newly installed brake pad to determine the wear state of the brake pad.
Optionally, the hydraulic braking devices of the other wheels of the motor vehicle are inhibited from operating while the recording is being made for the hydraulic braking device of one wheel of the motor vehicle.
Alternatively, the recorded time required for establishing the brake hydraulic pressure is an average of the results of a plurality of recordings made to the respective hydraulic brake device.
Alternatively, the time required for the same hydraulic brake device to establish the braking hydraulic pressure recorded in the case where the brake lining is newly installed is an average value of the results of the plurality of times of recording performed by the hydraulic brake device.
Optionally, after a certain distance of travel of the motor vehicle, the time required for the hydraulic brake device to build up the brake hydraulic pressure is recorded in the event of a stationary motor vehicle.
Optionally, the motor vehicle comprises a brake fluid drive circuit comprising a hydraulic main pump and a fluid pipe network configured to generate a hydraulic circuit portion fluidly connecting only one hydraulic brake device with the hydraulic main pump when the time required to establish a brake hydraulic pressure needs to be recorded for that hydraulic brake device, and a brake fluid tank fluidly connected to the brake fluid drive circuit.
Optionally, a pressure sensor is provided within the fluid line network to measure brake fluid pressure within the hydraulic circuit portion to determine whether brake fluid pressure is established.
According to another aspect of the present application, there is provided a brake lining wear monitoring method for a motor vehicle, wherein the motor vehicle comprises a hydraulic brake device acting on a wheel thereof, the hydraulic brake device having a brake disc rotating with the wheel and a brake lining non-rotatable with respect to the brake disc but linearly displaceable parallel to an axis of rotation of the brake disc, the brake lining being displaceable by actuation of a hydraulic brake cylinder assembly, the method comprising:
recording the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly by the hydraulic brake device to build up a braking hydraulic pressure when the vehicle is stationary;
the recorded volume of brake fluid injected into the cylinder is compared with the recorded volume of brake fluid injected into the same cylinder with the brake pads newly installed to determine the wear state of the brake pads.
Optionally, the hydraulic braking devices of the other wheels of the motor vehicle are inhibited from operating while a record is made for the hydraulic braking device of one wheel of the motor vehicle.
According to another aspect of the present application, there is provided a brake pad wear monitoring system for a motor vehicle, comprising:
a central electronic control unit configured to control a hydraulic braking device of the motor vehicle and a brake hydraulic drive circuit for operating the hydraulic braking device, characterized in that it is configured to carry out the aforementioned method.
By adopting the technical means, the wear condition of the friction plate can be reliably monitored under the condition that no additional equipment is required to be arranged on the friction plate, a favorable basis is provided for a user of the motor vehicle to replace the friction plate, the design, manufacture and assembly costs of the braking device are reduced, and the driving safety of the motor vehicle is improved.
Drawings
The principles and aspects of the present application will be more fully understood from the following detailed description, taken in conjunction with the accompanying drawings. It is noted that the drawings may not be to scale for clarity of illustration and will not detract from the understanding of the present application. In the drawings:
fig. 1 shows a simplified frame diagram of a motor vehicle, wherein the motor vehicle is equipped with a hydraulic brake system;
fig. 2 shows a simplified schematic diagram of a hydraulic brake device configured for one wheel;
FIG. 3 is a simplified diagram illustrating the basic principle of brake pad thickness detection of the hydraulic brake device of the present application;
FIG. 4 is a graph of pressure applied by brake pads over time when friction braking is achieved by a single hydraulic brake device;
FIG. 5 is a block diagram schematically illustrating a vehicle brake pad wear detection system according to one embodiment of the present application;
FIG. 6 illustrates a brake fluid drive circuit of a hydraulic brake system according to one example of the present application;
fig. 7A, 7B, 7C, and 7D show brake fluid operation modes in the brake fluid drive circuit when the hydraulic brakes of different wheels need to be actuated, respectively;
FIG. 8 schematically illustrates a flow chart of a brake pad wear monitoring method according to one embodiment of the present application;
FIG. 9 schematically illustrates a flow chart of a brake pad wear monitoring method according to another embodiment of the present application;
fig. 10A and 10B are graphs of experimental results, schematically illustrating the results of detecting the wear of the brake pads of the motor vehicle using the system and method for detecting the wear of the brake pads of the motor vehicle of the present application.
Detailed Description
In the various figures of the present application, features that are structurally identical or functionally similar are denoted by the same reference numerals.
Fig. 1 shows a simplified frame schematic of a motor vehicle 100 having four wheels, namely a front left wheel FL, a front right wheel FR, a rear left wheel RL and a rear right wheel RR. The left front wheel FL, the right front wheel FR, the left rear wheel RL and the right rear wheel RR are respectively provided with a hydraulic brake device FLB, FRB, RLB or RRB. These hydraulic braking devices may be part of a hydraulic braking system of the motor vehicle 100. For example, the hydraulic brake system may further include a brake fluid drive circuit 210 fluidly connected to the brake fluid tank 300, wherein the brake fluid drive circuit 210 is fluidly connected to each of the hydraulic brake devices FLB, FRB, RLB, or RRB to drive the hydraulic brake devices FLB, FRB, RLB, or RRB to perform a braking action.
Fig. 2 shows a simplified frame diagram of the hydraulic brake device FLB only as an example. It should be clear to a person skilled in the art that the other hydraulic brakes FRB, RLB, RRB are constructed in a similar principle and/or work as shown in fig. 2. The hydraulic brake device FLB comprises a brake disc 500, said brake disc 500 being mounted non-rotatable with respect to the wheel FL and having a common central rotation axis O. That is, as the wheel FL rotates, the brake disc 500 is also correspondingly driven to rotate about the center rotational axis O along with the wheel FL (fig. 1). The hydraulic brake device FLB further includes a brake caliper 600. The brake caliper 600 is mounted to a portion of a suspension (not shown) of the motor vehicle in a non-rotatable manner with respect 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 axially opposite sides of the brake disc 500, respectively. In addition, a hydraulic brake cylinder assembly 800 is also fixedly mounted to the brake caliper 600. For example, the hydraulic brake cylinder assembly 800 includes a cylinder block 810 fixedly mounted relative to the brake caliper 600 and a brake piston 820 axially movable back and forth within the cylinder block 810. The brake piston 820 can be brought into a working relationship with one brake pad 700 so that the pair of brake pads 700 can come close to each other and contact the axially opposite surfaces of the brake disc 500 by the brake caliper 600 when the brake piston 820 is pressed against the brake pad 700 by hydraulic pressure. Since the brake caliper 600 and each brake pad 700 are installed in a non-rotatable manner with respect to the brake disc 500, the brake pad 700 contacting the brake disc 500 will exert a frictional braking force on the brake disc 500, and as the hydraulic pressure driving the brake piston 820 reaches a certain degree, it is finally ensured that the brake disc 500 stops rotating or the rotational speed is reduced and thus braking of the wheel FL is achieved. When the wheel brake is not required, the respective brake pads 700 are separated from each other by the brake disc 500 by the return springs (not shown) installed in the brake caliper 600 as the hydraulic pressure is unloaded from the brake piston 820, so that the wheel FL will be able to freely rotate without receiving the frictional braking force. Since the hydraulic brake device FLB is fluidly connected to the brake fluid driving circuit 210, the hydraulic pressure for driving the brake piston 820 is provided by the brake fluid driving circuit 210.
Since the hardness of the friction material on the brake pads is less than the hardness of the surface of the brake rotor 500 or the brake rotor 500. Therefore, as the time and number of uses of the vehicle increase, the friction material on the brake pads will wear down and become thinner. When the friction material on the brake lining is worn out, it will not be able to provide enough friction braking force for the brake disc when the wheel needs to brake. Therefore, after a new brake pad is installed in a motor vehicle, the thickness of the brake pad needs to be measured at any time to know the wear condition of the friction material on the brake pad.
Fig. 3 is a simplified diagram showing the operation of a new friction plate and a brake disc whose thicknesses are reduced to a certain extent by wear. For clarity of description, only the brake linings 700 on one side of the brake disk 500 are shown in fig. 3, wherein the brake lining 700 located above is in its new condition and the brake lining 700 located below is in its condition after it has been in use for a certain time. Fig. 3 shows the positions of an upper, entirely new brake pad 700 and a lower, worn brake pad 700 when the same frictional braking force is applied to the brake disc 500. For example, assuming that a brake pad 700 is newly installed in a hydraulic brake device FLB of a vehicle, the upper view in fig. 3 may represent a position showing when the brake pad 700 applies a braking force on the brake disc 500, and the lower view in fig. 3 may represent a position of the brake pad 700 worn to some extent when the same braking force is applied to the brake disc via the brake pad 700 after the vehicle has traveled a certain distance (e.g., 5 kilometers).
If the volumetric deformation of the brake pad 700 itself when pressed is neglected, the thickness h of the new brake pad 700 is the same in the case where the same braking force is applied to the brake disc 500 via the brake pad 7000Thickness h of brake pad 700 that is worn to some extentpSatisfies the following relationship:
hp＝h0-Hw
wherein HwRepresenting the amount of thickness reduction of the same brake pad.
The process of establishing brake fluid pressure (i.e., the fluid pressure that drives the brake piston 820 described above) by the hydraulic brake cylinder assembly 800 and ultimately the brake fluid pressure to a level that provides wheel braking criteria must be experienced while wheel braking is being performed. In this process, as the brake piston 820 drives the brake pads 700 into contact with the brake disc 500, the brake piston 820 will undergo a process in which the hydraulic pressure it provides gradually increases. The hydraulic pressure in the portion of the hydraulic circuit associated with the brake piston 820 will gradually increase from the perspective of the brake fluid drive circuit 210. Fig. 4 shows such a hydraulic pressure increasing process for an entirely new brake pad 700 and a brake pad 700 after a certain time, respectively, line 1 representing the hydraulic pressure increasing process corresponding to the entirely new brake pad 700, and line 2 representing the hydraulic pressure increasing process corresponding to the brake pad 700 after a certain time.
The brake piston 820 always moves from the same position measured in the cylinder 810 each time wheel braking is performed, due to the action of a return spring (not shown). At the beginning of the movement of the brake piston 820, the brake fluid is pumped in the brake fluid driving circuit 210The brake piston 820 drives the brake pad 700 to move toward the brake disc 500 by the brake fluid. If the brake pad 700 has not yet contacted the brake disc 500, the hydraulic pressure in the relevant hydraulic circuit portion is almost zero. Since the brake piston 820 is blocked by the brake pad 700 not being able to move again from the moment the brake pad 700 comes into contact with the brake disc 500, the hydraulic pressure in the relevant hydraulic circuit portion is gradually increased as the pumping action is enhanced, and accordingly the frictional braking force exerted by the brake pad 700 on the brake disc 500 is increased. When such hydraulic pressure increases to a certain extent, it can be considered that the frictional braking force exerted by the brake pad 700 on the brake disc 500 reaches a desired value (for example, the desired value is consistent with the braking intention of the vehicle driver such as braking the vehicle or decelerating without triggering the anti-lock function of the vehicle), and then the pumping action of the brake fluid can be stopped to maintain such hydraulic pressure and to maintain the braking of the brake pad 700 on the brake disc 500. Therefore, each line in fig. 4 corresponds to a time when the brake pad 700 just contacts the brake disc 500 at t-0. In FIG. 4, when the hydraulic pressure reaches the same P0(e.g. P)050 bar), line 1 and line 2 respectively require time t1And t2And t is1<t2. This difference in time is apparently due to the reduced thickness of the brake disk 700. P is above0May be embodied to represent the same braking force applied to the brake disc 500 when explaining fig. 3.
Turning to fig. 3, it should be first apparent that the upper brake pad 700 and the lower brake pad 700 are both in a state in which the same braking force is applied to the brake disc 500 via their respective brake pads. It is apparent that the amount of wear H is due to the thickness of the brake pad 700wThe axial position of the brake piston 820 within the cylinder 810 varies in order to achieve the same braking force.
Assuming that the same braking force is applied to the disc 500 for an entirely new brake pad 700 (above), the initial braking position of the brake piston 820 with respect to the cylinder 810 (this position is used as a reference)Position, fixed for each hydraulic brake cylinder assembly 800) has an axial distance H0(ii) a For a brake lining 700 (below) that is worn to some extent, the axial distance of the brake piston 820 with respect to the braking initial position of the cylinder 810 when the same braking force is applied to the brake disc 500 is Hcyl。
Since the axial dimension of the brake piston 820 itself can be regarded as being constant, the two axial distances of the brake piston 820 should satisfy the following relationship:
Hcyl＝H0+Hw
wherein HwThe amount of thickness wear of the brake pad 700. It should be clear that H is as defined abovewIt is possible to reflect the difference between the volume of brake fluid contained in cylinder 810 for a completely new brake pad and the volume of brake fluid contained in cylinder 810 for a brake pad worn to some extent, even if the same braking force is applied to brake disc 500 via the brake pad.
With further reference to FIG. 4, assume that P is reflected0Should be applied to the brake disc 500 shown in fig. 3, the volume of brake fluid injected in the cylinder 810 should be, whether for a completely new brake pad or for a brake pad that is worn to some extent:
ΔV＝A·Q·t，
where a denotes a cross-sectional area of a port of a fluid inlet valve (not shown) for inputting hydraulic brake fluid into the relevant hydraulic circuit portion, Q denotes a flow rate of the brake fluid (i.e., a volume of the brake fluid flowing per unit area per unit time), and t denotes a time period from time 0 to P as shown in fig. 4, for example0The time between the represented time instants. Here, A, Q may be determined in advance and t may be measured from the corresponding sensor.
If the inner wall of the cylinder 810 is considered to be an ideal cylindrical shape, the brake piston 820 moves from the braking initial position to the position shown in fig. 3, the change V of the inner volume of the cylinder 810 is 1/4 · pi D2 · H, D is the inner diameter of the cylinder 810, and H is the axial distance that the brake piston 820 moves from the braking initial position to the position shown in fig. 3.
For a brake pad 700 that is worn to some extent, H is replaced by HcylThen V is 1/4. pi.D2·HcylWhere D is the inner diameter of the cylinder 810.
The compression coefficient of the brake fluid is β ═ Δ V/(p · V), where p is the hydraulic pressure.
Therefore, the thickness of the brake disk 700 that wears to some extent should be:
hp＝H0+h0-(4AQ/πD2·β·p)·t (1)
it can be seen that the actual thickness of the final brake pad 700 after a period of use is primarily related to the variable t, according to equation (1). That is, if the hydraulic brake devices associated with each wheel can be independently controlled and the time required to establish the braking force is measured with the same braking force applied to the brake disc, the actual thickness of the brake pads can be determined accordingly. To put it back, even if the actual thickness of the brake pad is not accurately determined, it is possible to estimate accordingly whether or not a new brake pad needs to be replaced, only with respect to the difference between the time required for an entirely new brake pad to establish a braking force and the time required for a brake pad to establish the same braking force after a certain period of use in the case where the same braking force is applied to the brake disc. It will be clear to those skilled in the art that h in equation (1) is shown in FIG. 3pRefers to the thickness of the brake pad 700 adjacent the brake piston 820 of the hydraulic brake cylinder assembly 800; in the brake caliper 600, another brake pad 700 is mounted to the brake pad 700 via the brake disc 500, and the two brake pads 700 are considered to be worn by the same amount, i.e., have the same thickness wear amount. Thus, h in equation (1)pMay also be used to refer to the thickness of the other brake pad 700.
FIG. 5 schematically illustrates a vehicle brake pad wear detection system according to one embodiment of the present application. As shown, the motor vehicle brake pad wear detection system generally includes a central electronic control unit 1000 and a hydraulic brake system as mentioned above, wherein the hydraulic brake system includes a brake fluid tank 300, a brake fluid drive circuit 210 fluidly connected to the brake fluid tank 300, and a hydraulic brake device FLB, FRB, RLB, or RRB fluidly connected to and driven by the brake fluid drive circuit 210. Alternatively and/or additionally, the motor vehicle brake pad wear detection system may include a recording module. For example, the recording module can be associated with the central electronic control unit 1000. The recording module may be configured to record the time required for the hydraulic brake device to build up the braking hydraulic pressure, in particular in the event of a stationary motor vehicle. In this way, the central electronic control unit 1000 may be configured to compare the recorded time required to establish the brake hydraulic pressure with the recorded time required to establish the brake hydraulic pressure of the same hydraulic brake device in the case where the brake pads are newly installed, to determine the worn state of the brake pads.
In addition, the brake fluid drive circuit 210 is also fluidly connected to the brake pedal 400. In the context of the present application, the term "fluidly connected" means that the two features are connected in such a way that they are able to transfer fluid to each other, either directly or via a conduit for transferring fluid. The term "data connection" means that the two features are connected in such a way that they are able to transfer electronic data or signal data to each other, which may be connected via any suitable connection means, such as a cable. The brake fluid driving circuit 210 can drive the respective hydraulic brake devices FLB, FRB, RLB, and RRB to brake all the wheels in accordance with an operation input of the brake pedal 400.
The central electronic control unit 1000 is configured to generate signals for independently controlling the operation of the brake fluid drive circuit 210. Fig. 6 shows a simplified example of the brake fluid drive circuit 210. It should be clear to those skilled in the art that this simplified example of the brake fluid drive circuit 210 is given for explanatory purposes only, and the brake fluid drive circuit of the present application should not be limited to the configuration shown in fig. 6. As shown, the brake fluid drive circuit 210 generally includes a hydraulic main pump 211, a fluid network, and other associated components. The fluid network fluidly connects the hydraulic main pump 211 and the valve control device 212. At the same time, each of the hydraulic brakes FLB, FRB, RLB, and RRB is also fluidly connected to the fluid network.
Further, the brake fluid tank 300 is connected to a fluid pipe network. In the context of the present application, the term "operatively connected" means that an action performed by one of two features connected to each other causes a specific action to be performed by the respective other feature. Here, when the brake pedal 400 is pressed, the brake fluid in the brake fluid driving circuit 210 is controlled to flow, and the respective hydraulic brake devices FLB, FRB, RLB, and RRB are driven through the fluid network to perform braking. In particular, a plurality of solenoid valves, which are indicated by the symbol EV in fig. 6, are provided in the fluid network where necessary. The aforementioned central electronic control unit 1000 is capable of being in data connection with these solenoid valves EV, respectively, and controlling the on-off of one or more of them as required, so that it is possible to create, within the fluid pipe network of the brake fluid drive circuit 210, the relevant hydraulic circuit portion that fluidly connects only one of the hydraulic brake devices FLB, FRB, RLB, and RRB with the hydraulic main pump 211 as required.
Fig. 7A, 7B, 7C, 7D each show different hydraulic circuit portions defined in the fluid network of the brake fluid drive circuit 210, which are each configured such that the hydraulic main pump 211 is in fluid connection only with the hydraulic brake device FLB, FRB, RLB or RRB, wherein fig. 7A shows the hydraulic circuit portion in which the hydraulic main pump 211 is in fluid connection with the hydraulic brake device FLB, fig. 7B shows the hydraulic circuit portion in which the hydraulic main pump 211 is in fluid connection with the hydraulic brake device FRB, fig. 7C shows the hydraulic circuit portion in which the hydraulic main pump 211 is in fluid connection with the hydraulic brake device RLB, fig. 7D shows the hydraulic circuit portion in which the hydraulic main pump 211 is in fluid connection with the hydraulic brake device RRB, and the thick lines in the respective figures represent the hydraulic circuit portions. It can be seen that a pressure sensor 213 is provided within the fluid line network of the brake fluid drive circuit 210, the pressure sensor 213 being configured to measure the hydraulic pressure within the hydraulic circuit portion accordingly, regardless of which hydraulic circuit portion. At the same time, the pressure sensor 213 is in data connection with the central electronic control unit 1000, so that the measurement results can be transmitted to the central electronic control unit 1000 for processing.
FIG. 8 schematically illustrates a flow chart of a brake pad wear monitoring method according to one embodiment of the present application. It will be clear to those skilled in the art that any of the methods or processes described herein can be encoded as program code executable by a computer or computers and stored in the memory of the central electronic control unit 1000 so as to be invoked for execution by the computing unit or the vehicle computer of the central electronic control unit 1000 at a convenient time.
As shown in fig. 8, in step S10, it is first confirmed whether a new brake pad is installed in the vehicle. This may be done, for example, by manually entering commands into the central electronic control unit 1000 via a suitable in-vehicle display interface or input device, either after a new vehicle has been shipped, or after a new brake pad has been manually installed at a later stage of the vehicle. In step S10, when a new vehicle leaves the factory, a new brake pad thickness may be automatically recorded, or when a new brake pad is manually installed at a later stage, a new brake pad thickness may be manually input and recorded to the central electronic control unit 1000.
In step S20, after the motor vehicle has been parked safely and reliably in place, the fluid line network of the brake fluid drive circuit 210 is individually switched on in a manner similar to that shown in fig. 7A, 7B, 7C or 7D, respectively, such that the hydraulic main pump 211 establishes a fluid connection only with the hydraulic brake device FLB, FRB, RLB or RRB. Then, the time required for each hydraulic brake device to establish the braking hydraulic pressure is recorded separately. In the context of the present application, the term "time required for establishing the braking hydraulic pressure" refers to the time that elapses for a respective one of the hydraulic braking devices for which the brake pads thereof are just coming into contact with the brake disc until the brake pads have exerted a defined braking friction force on the brake disc, which corresponds to the hydraulic pressure of the piston driving the brake pads. This time can be measured by any existing sensing device provided in the vehicle.For example, the "time required to establish the braking hydraulic pressure" may be represented as t in fig. 41、t2。
At step S30, the current thickness (i.e., h) of the brake pad of the corresponding hydraulic brake device is calculated and solved through the formula (1) using the time required to establish the brake hydraulic pressure obtained at step S20p) Or the thickness wear amount of the brake pads. It should be clear to those skilled in the art that steps S20 and S30 can be performed after the vehicle has traveled a certain distance, for example, 5000-20000 km, so that the calculation load of the central electronic control unit 1000 can be reduced. Furthermore, in the solution of the present application, the current thickness (i.e. h) of the brake liningsp) Or the thickness wear amount of the brake pads may be determined by performing steps S20 and S30 after a plurality of stops and averaging the results. This ensures that the accuracy of the final calculation results meets the appropriate requirements.
Next, in step S40, the current thickness (i.e., h) of the brake pad obtained in step S30 is setp) If the difference between the thicknesses of the completely new brake pads recorded in step S10 is greater than a predetermined value, the corresponding brake pads are deemed to have to be replaced, and the driver may be alerted to the need to replace the brake pads, for example, by an in-vehicle display interface prompt and/or an audible alert. Alternatively or additionally, in step S40, it may be determined whether the thickness wear amount of the brake pad is greater than a predetermined value, and if so, the driver may be prompted to replace the brake pad, for example, by an in-vehicle display interface prompt and/or an alarm sound.
Although the above-described method embodiment utilizes equation (1) to solve for the current thickness (i.e., h) of the brake padsp) Or the thickness abrasion amount of the brake pad, but it should be clear to those skilled in the art that the difference between the time required for establishing the brake hydraulic pressure between a brand-new brake pad and a brake pad used for a certain period of time may be directly used to determine whether the brake pad needs to be replaced.
For example, FIG. 9 schematically illustrates a flow chart of a brake pad wear monitoring method according to another embodiment of the present application. In step S11, it is first determined whether the motor vehicle is equipped with a completely new brake lining, for example, by manually inputting a command to the central electronic control unit 1000 via a suitable in-vehicle display interface or input device.
In step S21, in the case where it has been confirmed that the motor vehicle is equipped with an entirely new brake pad, a hydraulic circuit portion that is fluidly connected to the hydraulic main pump 211 in the fluid pipe network of the brake fluid drive circuit 210 is established for a single one of the hydraulic brake devices FLB, FRB, RLB, or RRB, and the time required for each hydraulic brake device to establish the brake hydraulic pressure is recorded, respectively, in a manner similar to that described in step S20. For example, here "the time required for establishing the braking hydraulic pressure" may be obtained by recording the results after the motor vehicle stops for a plurality of times or a certain number of times in succession, respectively, and finally averaging, thereby improving the accuracy of the result of the time required for establishing the braking hydraulic pressure.
In step S31, it is determined whether the vehicle has traveled a certain distance, for example, 5000 to 20000 km from step S21. If the judgment result of the step S31 is NO, the waiting is continued. If the judgment in the step S31 is YES, the process goes to a step S41. In step S31, the time required for each individual hydraulic brake device to establish the braking hydraulic pressure is recorded in a similar manner to step S21. Here, the record referred to in step S31 may be an average value of the recorded results of the motor vehicle after stopping for a plurality of times within a period of time or a short distance (e.g., 100 to 300 km).
In step S41, the time required for each of the hydraulic brake devices FLB, FRB, RLB, or RRB to establish the hydraulic circuit portion in the fluid network of the brake fluid drive circuit 210 that is fluidly connected to the hydraulic main pump 211 is recorded in a manner similar to that described in step S20, and the time required for each of the hydraulic brake devices to establish the brake hydraulic pressure is recorded. Here, the record referred to in step S41 may be an average value of the recorded results of the motor vehicle after stopping for a plurality of times within a period of time or a short distance (e.g., 100 to 300 km).
In step S51, the time required to establish the brake hydraulic pressure recorded in step S21 is compared with the time required to establish the brake hydraulic pressure recorded in step S41, and if the difference between the two exceeds a specific value, it is determined that the wear of the pair of brake pads corresponding to the excessive difference has exceeded the standard and needs to be replaced, and at this time, the driver may be alerted to the need to replace the brake pads, for example, by means of an in-vehicle display interface prompt and/or a prompt sound alarm. If the comparison result in the step S51 shows that the difference is not too large, the process goes to a step S31 to resume monitoring of the brake pads of the hydraulic brake devices FLB, FRB, RLB, or RRB. For example, when the monitoring is resumed in step S31, the monitoring may be performed after the vehicle travels 1000 to 2000 km.
It will be clear to a person skilled in the art that the steps of the above-mentioned method embodiments can be used in combination with each other and that they have been given for illustrative purposes only and are not intended to impose any scope of restriction on the application. Further, it should be clear to those skilled in the art that, during the above explained method, after the step S40 or S51, the fluid pipe network of the brake fluid driving circuit 210 should be reset to the factory state, so as to ensure that the vehicle is normally driven without any difference from the daily driving.
Fig. 10A and 10B are graphs of experimental results showing the results of monitoring the brake pads of the motor vehicle by using the above method or system of the present application, thereby illustrating the feasibility of the technical solution of the present application. The four bars of FIGS. 10A and 10B represent the same P being reached as calculated using the formula previously mentioned0(50 bar) the volume of brake fluid in cylinder 810. Specifically, with respect to fig. 10A, the brake pads of all the hydraulic brake devices corresponding to the four wheels are first replaced with completely new ones, and then the brake fluid volume in the cylinder 810 is determined for the brake disk of each wheel when the same braking force is applied; then the brake friction plate of the hydraulic brake device FRB is replaced by a brake friction plate with the thickness worn by 5mm, and the brake friction plate is aimed at each wheelThe brake disc determines the volume of brake fluid within the cylinder 810 when the same braking force is applied. The dark portions in each column in fig. 10A represent the calculated volume difference values, which are indicated above each dark portion. In fig. 10B, the brake pads of all the hydraulic brake devices corresponding to the four wheels are replaced with completely new brake pads, and the brake fluid volume in the cylinder 810 is determined for the brake disk of each wheel when the same braking force is applied; the brake pads of the hydraulic brake device RRB are then replaced by brake pads which have worn out by 5mm in thickness, and the volume of brake fluid in the cylinder 810 is determined for the brake discs of each wheel when the same braking force is applied. The dark portion in each column in fig. 10B represents the calculated volume difference value.
As can be seen from fig. 10A and 10B, the determined volume difference of the brake fluid is very clear and sufficiently distinguishable for the hydraulic braking devices FRB, RRB in which the worn brake linings have been modified, thus indicating that the method or system of the present application is reliable and feasible for monitoring the brake linings of a motor vehicle. It should be noted that in fig. 10A and 10B, although there is a difference in the volume of brake fluid for a hydraulic brake device without replacing a brake pad, this is only caused by the overlap of different hydraulic circuit portions established in the fluid network, and does not affect the monitoring result of the system and method of the present application on a worn brake pad.
Although specific embodiments of the present application have been described herein in detail, they have been presented for purposes of illustration only and are not to be construed as limiting the scope of the application. Further, it should be clear to those skilled in the art that the various embodiments described in this specification can be used in combination with each other. Various substitutions, alterations, and modifications may be conceived without departing from the spirit and scope of the present application.
Claims (8)
1. A brake pad wear monitoring system for a motor vehicle, wherein the motor vehicle comprises a hydraulic brake device acting on a wheel of the motor vehicle, the hydraulic brake device having a brake disc rotating with the wheel and a brake pad non-rotatable with respect to the brake disc but linearly movable parallel to an axis of rotation of the brake disc, the brake pad wear monitoring system comprising:
a recording module to record a time required for the hydraulic brake device to establish a braking hydraulic pressure in a case where the motor vehicle is stationary;
a central electronic control unit in data connection with the recording module for comparing the recorded time required for establishing the brake hydraulic pressure with the recorded time required for establishing the brake hydraulic pressure of the same hydraulic brake device in the case of a new installed brake lining for determining the wear state of the brake lining.
2. The brake friction lining wear monitoring system of claim 1 wherein, when the recording module records hydraulic brakes of one wheel of the motor vehicle, the central electronic control unit generates a command to disable hydraulic brakes of other wheels of the motor vehicle.
3. A brake friction plate wear monitoring system according to claim 1 or 2 wherein the recording module is operable after a certain distance of travel of the vehicle and with the vehicle stationary to record the time required for the hydraulic brake device to build up brake hydraulic pressure.
4. A brake lining wear monitoring system according to 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 fluidly connects one hydraulic brake device with the hydraulic main pump (211) when the time required for establishing a brake hydraulic pressure needs to be recorded for that hydraulic brake device.
5. A brake friction lining wear monitoring system according to claim 4 wherein a pressure sensor (213) is provided in the fluid line network to measure brake fluid pressure within the hydraulic circuit portion to determine whether brake fluid pressure is established.
6. A brake pad wear monitoring system for a motor vehicle, wherein the motor vehicle includes a hydraulic brake device acting on a wheel of the motor vehicle, the hydraulic brake device having a brake disc rotating with the wheel and a brake pad non-rotatable with respect to the brake disc but linearly displaceable parallel to an axis of rotation of the brake disc, the brake pad being displaceable by actuation of a hydraulic brake cylinder assembly, the brake pad wear monitoring system comprising:
a recording module for recording the volume of brake fluid injected into the cylinder of the hydraulic brake cylinder assembly by the hydraulic brake device for establishing a braking hydraulic pressure when the motor vehicle is stationary;
a central electronic control unit in data connection with the recording module to compare the recorded volume of brake fluid injected into a cylinder with the recorded volume of brake fluid injected into the same cylinder in the event of a new brake pad installation to determine the wear state of the brake pad.
7. The brake friction lining wear monitoring system of claim 6 wherein, when the recording module records hydraulic brakes of one wheel of the motor vehicle, the central electronic control unit generates a command to disable hydraulic brakes of other wheels of the motor vehicle.
8. A motor vehicle comprising a brake pad wear monitoring system according to any one of claims 1 to 7.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115076269A (en) * | 2022-06-28 | 2022-09-20 | 中国第一汽车股份有限公司 | Friction plate abrasion alarm control method and system, vehicle and storage medium |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115076269A (en) * | 2022-06-28 | 2022-09-20 | 中国第一汽车股份有限公司 | Friction plate abrasion alarm control method and system, vehicle and storage medium |
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