Systems and methods for detecting wear of brake pads

The disclosure includes a system for indicating wear of a brake pad attached to a vehicle. The system can include a pad holder, a brake pad mechanically coupled to the pad holder, and a sensing device coupled to the brake pad and located at least partially within the cavity. The sensing device can include a first electrode and a second electrode embedded within the sensing device. The first electrode and the second electrode can measure electrical resistivity of an electrically conductive material located within the sensing device. The electrical resistivity can indicate a thickness of the internal portion of the brake pad after the internal portion has been eroded by the rotating portion of the wheel.

CROSS-REFERENCE TO RELATED APPLICATIONS

The entire contents of the following application are incorporated by reference herein: U.S. Provisional Patent Application No. 62/178,660; filed Apr. 17, 2015; and entitled BRAKE WEAR INDICATOR SYSTEM.

The entire contents of the following application are incorporated by reference herein: U.S. Provisional Patent Application No. 62/230,732; filed Jun. 15, 2015; and entitled BRAKE WEAR INDICATOR DEVICE.

The entire contents of the following application are incorporated by reference herein: U.S. Provisional Patent Application No. 62/231,607; filed Jul. 11, 2015; and entitled SYSTEM AND METHOD TO DETECT THE WEARING STATUS OF A VEHICLE'S BRAKE PAD.

The entire contents of the following application are incorporated by reference herein: U.S. Provisional patent application Ser. No. 14/829,283; filed Aug. 18, 2015; entitled SYSTEMS AND METHODS FOR DETECTING WEAR OF BRAKE PADS.

The entire contents of the following application are incorporated by reference herein: U.S. Provisional patent application Ser. No. 15/138,904; filed Apr. 26, 2016; entitled SYSTEMS AND METHODS FOR DETECTING WEAR OF BRAKE PADS.

The entire contents of the following application are incorporated by reference herein: U.S. Provisional patent application Ser. No. 15/132,757; filed Apr. 19, 2016; entitled SYSTEMS AND METHODS FOR DETECTING WEAR OF BRAKE PADS.

The entire contents of the following application are incorporated by reference herein: U.S. Provisional patent application Ser. No. 15/156,036; filed May 16, 2016; entitled SYSTEMS AND METHODS FOR DETECTING WEAR OF BRAKE PADS.

The entire contents of the following application are incorporated by reference herein: PCT Patent Application No. PCT/US16/27998; filed Apr. 16, 2016; entitled SYSTEMS AND METHODS FOR DETECTING WEAR OF BRAKE PADS.

BACKGROUND

Field

The invention is directed in general to vehicle brake pads, and more specifically, to brake pad wear sensors to measure the actual amount of wear of a brake pad.

Description of Related Art

Vehicle maintenance requires periodic inspection of brake pads in order to assess the deterioration of the brake pads and ultimately determine when the brake pads need to be replaced. Failure to periodically perform this inspection can result in accidents due to brake malfunctions, which can result in danger to vehicle occupants and costly repairs to the vehicle.

Accordingly, brake inspections are required for various types of braking systems, such as drum-based brakes, in which a padded “shoe” presses against the wall of the wheel's drum, and disk brakes, in which two pads press against opposing sides of the rotating wheel disk (rotor). In the disk brake system, the rotor is a hard metal rotating disk, which is attached to the rotating wheel. Two brake pads made of relatively soft material are located on both sides of the rotor at close proximity. When the brake pedal is depressed, the two pads are forced towards the rotor to provide friction force that slows the wheel's rotation. As time progresses, the brake pads can become thinner and may need to be replaced. In most vehicles, it is not obvious to the vehicle operator as to when the brake pads need to be replaced because each wheel often has to be removed to inspect the brake pads. Consequently, the brake pad can totally wear out and the hard metal pad holders can come in contact with the rotor causing substantial damage and creating dangerous and inefficient braking of the vehicle.

In order to improve the inspection process, some vehicles can include embedded sensors to indicate excessive pad wear. As shown inFIG. 1, some systems can include a contact sensor attached in parallel to the internal wall of the pad holder or embedded in the pad at a specific distance from the pad holder. When the pad is worn to a point where it needs to be replaced, the sensor can establish electrical contact with the rotor. An electrical wire can convey the information to the vehicle's dashboard to generate a visual alarm indication for the vehicle operator. As further shown inFIG. 1, some vehicles may employ a distance sensor, which can continuously measure the distance between the two pad holders and thereby provide the information via electrical wires to the vehicle's dashboard.

There are several disadvantages of these systems, namely, undue false positives indicating to the vehicle operator to replace the brake pads. Car manufacturers may incur substantial liability for any false negative occurrences. In other words, if the brake pad is in need of replacement and the system does not generate an alarm, and a consequent accident occurs, the manufacturer may be responsible due to the fact that no alarm was generated. Consequently, the sensors and associated alarm indications may be designed to be overly sensitive to avoid the false negative scenario. Even still, a rupture in the wires connecting the sensor to the dashboard can also produce an alarm not related to the actual condition of the brake pad. This false positive indication can become so frequent and so disturbing to vehicle operators, that many operators deactivate the system entirely, thereby defeating the whole purpose of the system.

Another disadvantage to the “dashboard approach” is that it does not typically provide specific information about which brake pad needs to be replaced. Since brake pads may wear at different rates, the operator has to remove all the wheels to determine which pad is in need of maintenance. For vehicles, such as large trucks with many wheels, in which removal of wheels is costly and labor intensive, the dashboard approach can provide little value. Thus, there is a need for devices and methods to allow reliable inspection of brake pads without removing the wheels.

SUMMARY

The present disclosure includes systems for indicating wear of a brake pad attached to a vehicle. The system can include a pad holder and a brake pad mechanically coupled to the pad holder. The brake pad can have a braking surface arranged and configured to contact a rotating portion of a wheel, such as a rotor or a drum, an internal portion, and a cavity that extends from the braking surface into the internal portion. The system can include a sensing device coupled to the brake pad and located at least partially within the cavity. The sensing device can include a first electrode and a second electrode embedded within the sensing device. The first electrode and the second electrode can measure electrical resistivity of an electrically conductive material located within the sensing device. The electrical resistivity can indicate a thickness of the internal portion of the brake pad after the internal portion has been eroded by the rotating portion of the wheel. Additionally, the electrical resistivity can be proportional or inversely proportional to the thickness, and the electrically conductive material can be partially electrically conductive. The sensing device can be entirely located within the cavity.

The electrically conductive material can be located between the first electrode and the second electrode. In some embodiments, the sensing device comprises a capsule defining an inner portion that encapsulates the first electrode, the second electrode, and the electrically conductive material. The inner portion can comprise a filling material that at least partially surrounds the first electrode, the second electrode, and the electrically conductive material. As well, the electrically conductive material can comprise material used in the fabrication of commercial resistors.

The braking surface can extend along a first direction and a second direction that is perpendicular to the first direction. The cavity can extend from the braking surface into the internal portion along a third direction that is perpendicular to both the first direction and the second direction. Additionally, the first electrode and the second electrode can be elongate along the third direction. Moreover, a top surface of the first electrode and a top surface of the second electrode can be initially offset from the braking surface by a predetermined distance along the third direction.

In some embodiments, the system includes an on-board electronic module communicatively coupled to the sensing device and mechanically coupled to the vehicle. The on-board electronic module can be arranged and configured to receive data associated with the thickness of the brake pad. The on-board electronic module can include an alarm to indicate that the brake pad needs to be replaced. The sensing device can be electrically coupled to the on-board electronic module via at least two electrical wires. The at least two electrical wires extend from the sensing device through the pad holder.

In some embodiments, the on-board electronic module comprises memory. The memory can store data associated with the brake pad comprising at least one of initial brake pad thickness information, initial measured electrical resistivity, calculated current brake pad thickness, brake pad installation information comprising at least one of a date and a location, and wheel identification information comprising a location of the wheel with respect to the vehicle. A present thickness of the internal portion of the brake pad can be calculated by a formula relating a present measured electrical resistivity to the initial measured electrical resistivity.

Even still, in some embodiments, the system can include a remote computing device communicatively coupled to the sensing device. The remote computing device can be arranged and configured to display a visual indication of the thickness of the internal portion of the brake pad. The remote computing device can comprise a wireless receiver with a display showing the visual indication.

The disclosure can also include another system for indicating wear of a brake pad attached to a vehicle. The system can include a pad holder and a brake pad mechanically coupled to the pad holder. The brake pad can have an internal portion and a braking surface arranged and configured to contact a rotating portion of a wheel, such as a rotor or a drum. The system can include a sensor holder mechanically coupled to the pad holder. In some embodiments, the sensor holder is located external to the brake pad. The system can include a sensing device coupled to the sensor holder. The sensing device can include a pair of electrodes embedded within the sensing device. The pair of electrodes can measure electrical resistivity of an electrically partially conductive material located within the sensing device. The electrical resistivity can indicate a thickness of the internal portion of the brake pad after the internal portion has been eroded by the rotating portion of the wheel. The electrical resistivity can be proportional or inversely proportional to the thickness, and the electrically conductive material can be partially electrically conductive.

In some embodiments, the sensor holder physically contacts a first side surface of the brake pad. As well, in some embodiments, the sensor holder is referred to as a first sensor holder, the sensing device is a first sensing device, and the pair of electrodes is a first pair of electrodes. In this regard, the system can include a second sensor holder mechanically coupled to the pad holder. The second sensor holder can be located external to the brake pad. The second sensor holder can physically contact a second side surface of the brake pad whereby the second side surface is opposite the first side surface. Accordingly, the system can include a second sensing device coupled to the second sensor holder. The second sensing device can comprise a second pair of electrodes embedded within the second sensing device. The second pair of electrodes can measure electrical resistivity of an electrically partially conductive material located within the second sensing device. The second pair of electrodes can be elongate along the third direction. The multiplicity of sensors enable accurate assessment of any uneven wearing which by itself requires earlier replacement of the pad.

The disclosure also includes a method of using a system for indicating wear of a brake pad attached to a vehicle. The system can include a brake pad having a braking surface arranged and configured to contact a rotating portion of a wheel, an internal portion, and a cavity that extends from the braking surface into the internal portion. The system can include a sensing device coupled to the brake pad and located within the cavity. The sensing device can include a first electrode and a second electrode embedded within an inner portion of the sensing device. The first electrode and the second electrode measure electrical resistivity of an electrically conductive material located between the first electrode and the second electrode. Methods can include determining, via the first electrode and the second electrode, electrical resistivity of the electrically conductive material.

In some embodiments, the method includes determining a thickness of the internal portion of the brake pad after the internal portion has been eroded by the rotating portion of the wheel. Methods can also include receiving, via an on-board electronic module that is communicatively coupled to the sensing device, an indication of the thickness of the internal portion of the brake pad.

Even still, in some embodiments, the method includes displaying, by a dashboard of the vehicle, an indication of real-time thickness of the internal portion of the brake pad. Methods can include displaying, by a remote computing device communicatively coupled to the sensing device, an indication of real-time thickness of the internal portion of the brake pad. The remote computing device can include at least one of a smart phone, a tablet, a personal computer, and a microprocessor based circuitry.

Methods can even include emitting an alert, via an alarm communicatively coupled to the sensing device, that the thickness of the internal portion of the brake pad meets a predetermined thickness indicating that the brake pad needs to be replaced. The embodiments described above include many optional features and aspects. Features and aspects of the embodiments can be combined.

DETAILED DESCRIPTION

LIST OF REFERENCE NUMERALS

The brake system10, as disclosed, can address the disadvantages as previously described. For example, embodiments of the brake system10can wirelessly provide information regarding wear of a brake pad12of a vehicle. In this regard, a technician performing an inspection of the brake pad12may interrogate the brake system10, via an external wireless transmitter (e.g. a smart phone, tablet, personal computer, and any device having a microprocessor based circuitry), and thereby determine the wear of the brake pad12. The technician may thereby perform the inspection without having to remove the individual wheel from the vehicle. In this regard, once the technician determines which brake pads12are in need of being replaced, only the wheels of worn or defective brake pads12may be removed to thereby replace the respective brake pads12. Even still, some embodiments may include an electronic module70located on a dashboard of a vehicle to thereby provide brake pad thickness information for the vehicle user. These are just a few benefits and the person of ordinary skill in the art may appreciate additional benefits.

Sensing Device Embodiments

FIGS. 2 and 3illustrate a system10afor indicating wear of a brake pad12attached to a vehicle. The braking system10aincludes a pad holder14and a brake pad12mechanically coupled to the pad holder14. It should be appreciated that the brake pad12has a braking surface16arranged and configured to contact and impede a rotating portion of a wheel, such as a rotor18. As shown inFIG. 4, the braking surface16extends along a first direction X and a second direction Y that is perpendicular to the first direction X.

As shown inFIG. 3, the brake pad12can have an internal portion20and a cavity22that extends from the braking surface16into the internal portion20. Stated differently, and as illustrated inFIG. 4, the cavity22can extend from the braking surface16into the internal portion20along a third direction Z that is perpendicular to both the first direction X and the second direction Y.

The system10acan indicate wear of the brake pad12by a sensing device30coupled to the brake pad12and located at least partially within the cavity22. In some embodiments, the sensing device30is entirely located within the cavity22.

As shown inFIGS. 5 and 6, the sensing device30can include a first electrode32aand a second electrode32bembedded within the sensing device30whereby the first electrode32aand second electrode32bare elongate along the third direction Z. As illustrated, the electrically conductive material34can be located between the first electrode32aand the second electrode32b. Described differently, the sensing device30can be a surface mount resistor with electrodes on each side and partially conductive material located between the electrodes.

It should also be appreciated that the illustrations inFIGS. 2 and 3only depict a first brake pad12. In reality, most vehicle braking systems include at least a second brake pad12blocated on the opposite side of the first brake pad12. Accordingly, the system10can include a second sensing device30bcoupled to the second brake pad12b.

To determine brake pad wear, the first electrode32aand the second electrode32bcan measure electrical resistivity of an electrically conductive material34located within the sensing device30. It should be appreciated that the electrically conductive material34is at least partially electrically conductive. In some embodiments, the electrically conductive material34can comprise at least one of metallic particulate matter, conductive carbon particulate matter, and a combination of metallic particulate matter and conductive carbon particulate matter.

The electrical resistivity can indicate a thickness of the internal portion20of the brake pad12after the internal portion20has been eroded by the rotor18. In other words, as the internal portion20is worn by the rotor18, the sensing device30and the electrically conductive material34are also worn along with the internal portion20. Accordingly, the electrical resistivity of the electrically conductive material34can thereby indicate the thickness of the internal portion20of the brake pad12. It should be appreciated that the electrical resistivity can be proportional or inversely proportional to the thickness.

As further illustrated inFIG. 5, the sensing device30can include a capsule36defining an inner portion38that encapsulates the first electrode32a, the second electrode32b, and the electrically conductive material34. The capsule36can be press-fitted into the cavity22and/or coupled to the cavity22via epoxy. The inner portion38of the capsule can include a filling material40that at least partially surrounds the first electrode32a, the second electrode32b, and the electrically conductive material34. The capsule36can include any type of neutral material, such as a soft metal, plastic, or ceramic. The filling material40can comprise any type of material, such as epoxy, adhesive material, and/or potting material (e.g. ceramic potting material).

As shown inFIG. 6, the sensing device30bcan be devoid of a capsule36, and thereby an inner portion38and filling material40. In this regard, the first electrode32aand the second electrode32bcan define the outer surface of the sensing device30. The sensing device30bcan be placed within the cavity22and secured in place via any type of filling or potting material, such as epoxy.

In some embodiments, the first electrode32aand the second electrode32bare vertically offset with respect to the braking surface16. As shown in greater detail inFIG. 7, a top surface60aof the first electrode32aand a top surface60bof the second electrode32bare initially offset from the braking surface16by a predetermined distance62along the third direction Z. Accordingly, the first and second electrodes32a,32bcan indicate that the internal portion38of the brake pad12has no wear until the rotor18has worn the internal portion38of the brake pad12by a thickness that is at least equal to the predetermined distance62.

As shown in various figures, includingFIGS. 2, 5, 6, 8, and 9, the system10can include an electronic module70communicatively coupled to the sensing device30. In some embodiments, the electronic module70is wirelessly coupled to the sensing device30. However, the electronic module70can be electrically coupled to the sensing device30via at least two electrical wires72. The at least two electrical wires72can extend from the sensing device30through the pad holder14and to the electronic module70.

In some embodiments, the electronic module70is an on-board electronic module70that is mechanically coupled to the vehicle. Furthermore, the electronic module70can be arranged and configured to receive data associated with the thickness of the brake pad12. In some embodiments, the electronic module70includes an alarm74that can indicate when the brake pad12needs to be replaced. The alarm74can be any type of visual or audible alarm that can indicate the thickness of the brake pad12. In some embodiments, the alarm74includes a percentage of the remaining brake pad12thickness. Even still, in some embodiments, the alarm74can include a colored icon, such as a green icon to indicate that the brake pad12has an acceptable thickness of pad remaining. Accordingly, the alarm74can include a red icon to indicate that the brake pad12needs to be replaced. As such, when the brake pad12is “good” (i.e. not in need of replacement) the green icon can be illuminated, and when the brake pad12is “bad” (i.e. in need of replacement) the red icon can be illuminated. These are just a few of the many examples of alarms74that can be implemented.

As further shown inFIG. 9, the electronic module70can include memory76. The memory76can store data associated with the brake pad12comprising initial brake pad thickness information, initial measured electrical resistivity, calculated current brake pad thickness, brake pad installation information comprising at least one of a date and a location, and/or wheel identification information comprising a location of the wheel with respect to the vehicle. In some embodiments, a present thickness of the internal portion20of the brake pad12is calculated by a formula relating a present measured electrical resistivity to the initial measured electrical resistivity.

Now with reference toFIG. 10, the system10can include a remote computing device80communicatively coupled to the sensing device30. The remote computing device80can be a smart phone, tablet, personal computer, and/or any type of microprocessor based circuitry. Furthermore, the remote computing device80can be arranged and configured to display a visual indication of the thickness of the internal portion of the brake pad. In some embodiments, the remote computing device80can execute software, such as a mobile application, arranged and configured to communicate with the sensing device30and thereby retrieve the data and display the visual indication of the brake pad thickness.

As illustrated inFIG. 11, the system10bcan be devoid of a cavity22, as previously disclosed. In this regard, the system10bcan be retrofitted to existing braking systems. For example, the system10bcan include a pad holder14, a brake pad12mechanically coupled to the pad holder14, and a sensor holder33mechanically coupled to the pad holder14. In some embodiments, the sensor holder33is located external to the brake pad12. Specifically, the sensor holder33can physically contact a side surface64,66of the brake pad12. Additionally, the system10bcan include a sensing device30coupled to the sensor holder33. As shown inFIG. 11, the system10bcan include two or more sensor holders33and sensing devices30.

As shown inFIG. 13, the disclosure also includes methods of using a system for indicating wear of a brake pad attached to a vehicle. The method can include determining, via the first electrode32aand the second electrode32b, electrical resistivity of the electrically conductive material (at step1300). As well, methods can include determining a thickness of the internal portion20of the brake pad12after the internal portion20has been eroded by the rotor18(at step1302). Methods can also include receiving, via an on-board electronic module70that is communicatively coupled to the sensing device30, an indication of the thickness of the internal portion20of the brake pad12(at step1304).

Some methods can include displaying, by a dashboard of the vehicle, an indication of real-time thickness of the internal portion20of the brake pad12(at step1306). Methods can also include displaying, by a remote computing device80communicatively coupled to the sensing device30, an indication of real-time thickness of the internal portion20of the brake pad12(at step1308).

Even still, methods can include emitting an alert, via an alarm74communicatively coupled to the sensing device30, that the thickness of the internal portion20of the brake pad12meets a predetermined thickness indicating that the brake pad12needs to be replaced (at step1310). The predetermined thickness can be any thickness determined by a brake pad and/or vehicle manufacturer. In some embodiments, a user can input their own predetermined thickness. In this regard, the predetermined thickness can be preprogrammed by the manufacturer or customized by the user.

Interpretation

The phrase “data associated with the brake pad”, as used in the disclosure, can be interpreted to mean any type of data that is related to the vehicle, including digital computerized instructions to process brake pad information and/or data.

The phrase “the electrical resistivity is proportional to the thickness” used in the disclosure, can be interpreted to mean any mathematical relationship between the electrical resistivity and the pad's thickness including mathematical formulas and algorithms, such as adaptive algorithms. In this regard, proportional can be interpreted to mean directly proportional or inversely proportional.

The phrase “rotating portion of the wheel”, can be interpreted as either a wheel rotor used for disk brakes, or a drum used for shoe type brakes usually embedded in some rear wheel brakes of passenger cars or in heavy trucks

None of the steps described herein is essential or indispensable. Any of the steps can be adjusted or modified. Other or additional steps can be used. Any portion of any of the steps, processes, structures, and/or devices disclosed or illustrated in one embodiment, flowchart, or example in this specification can be combined or used with or instead of any other portion of any of the steps, processes, structures, and/or devices disclosed or illustrated in a different embodiment, flowchart, or example. The embodiments and examples provided herein are not intended to be discrete and separate from each other.

The section headings and subheadings provided herein are nonlimiting. The section headings and subheadings do not represent or limit the full scope of the embodiments described in the sections to which the headings and subheadings pertain. For example, a section titled “Topic 1” may include embodiments that do not pertain to Topic 1 and embodiments described in other sections may apply to and be combined with embodiments described within the “Topic 1” section.

Some of the devices, systems, embodiments, and processes use computers. Each of the routines, processes, methods, and algorithms described in the preceding sections may be embodied in, and fully or partially automated by, code modules executed by one or more computers, computer processors, or machines configured to execute computer instructions. The code modules may be stored on any type of non-transitory computer-readable storage medium or tangible computer storage device, such as hard drives, solid state memory, flash memory, optical disc, and/or the like. The processes and algorithms may be implemented partially or wholly in application-specific circuitry. The results of the disclosed processes and process steps may be stored, persistently or otherwise, in any type of non-transitory computer storage such as, e.g., volatile or non-volatile storage.

The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and subcombinations are intended to fall within the scope of this disclosure. In addition, certain method, event, state, or process blocks may be omitted in some implementations. The methods, steps, and processes described herein are also not limited to any particular sequence, and the blocks, steps, or states relating thereto can be performed in other sequences that are appropriate. For example, described tasks or events may be performed in an order other than the order specifically disclosed. Multiple steps may be combined in a single block or state. The example tasks or events may be performed in serial, in parallel, or in some other manner. Tasks or events may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example embodiments.

The term “and/or” means that “and” applies to some embodiments and “or” applies to some embodiments. Thus, A, B, and/or C can be replaced with A, B, and C written in one sentence and A, B, or C written in another sentence. A, B, and/or C means that some embodiments can include A and B, some embodiments can include A and C, some embodiments can include B and C, some embodiments can only include A, some embodiments can include only B, some embodiments can include only C, and some embodiments include A, B, and C. The term “and/or” is used to avoid unnecessary redundancy.