Systems and methods for sensing a brake component with an acoustic sensor

A brake actuator with a pushrod configured to actuate a brake of a vehicle. The pushrod is movable between a retracted position and an extended position to actuate the brake. A brake actuator component is operatively coupled to the pushrod. A sensor is configured to emit a signal directed toward the brake actuator component and to receive the signal after the signal bounces off the brake actuator component and is reflected back to the sensor. A disc brake with a disc brake component and a sensor configured to emit a signal directed toward the disc brake component. The sensor is configured to receive the signal after the signal bounces off the disc brake component and is reflected back to the sensor. The sensor may be an acoustic sensor.

1. FIELD OF THE INVENTION

The present invention is directed generally to sensing the position of brake mechanisms, and more specifically to sensing a brake component with an acoustic sensor.

2. DESCRIPTION OF RELATED ART

A pneumatic brake system for a large, heavy-duty vehicle such as a bus, truck, semi-tractor, or trailer may include a disc brake which is actuated by an actuator that is operated by the selective application of compressed air. Conventional pneumatic spring brake actuators have both a service brake actuator for actuating the brakes under normal driving conditions by the application of compressed air and a spring-type emergency brake actuator which actuates the brakes when air pressure has been released from a pressure chamber. The emergency brake actuator, or spring brake, includes a strong compression spring which applies the brake when air is released.

There are two main types of pneumatic brake actuators, piston type actuators and diaphragm type actuators. In the diaphragm type brake actuator, two pneumatic diaphragm brake actuators are typically arranged in a tandem configuration, which includes a pneumatic service brake actuator for applying the normal operating brakes of the vehicle, and a spring brake actuator for applying the parking or emergency brakes of the vehicle. Both the service brake actuator and the spring brake actuator include a housing having an elastomeric diaphragm dividing the interior of the housing into two distinct fluid chambers. The piston type brake actuator is substantially similar to the diaphragm type, except that instead of a diaphragm, a piston reciprocates in a cylinder for applying the normal and/or parking brakes of the vehicle.

In a typical service brake actuator, the service brake housing is divided into a pressure chamber and a pushrod chamber. The pressure chamber is fluidly connected to a source of pressurized air and the pushrod chamber mounts a pushrod that is coupled to the brake assembly. The introduction and exhaustion of pressurized air in to and out of the pressurized chamber reciprocates the pushrod in to and out of the housing to apply and release the operating brakes.

In a typical spring brake actuator, the spring brake section is divided into a pressure chamber and a spring chamber by a diaphragm. A pressure plate is positioned in the spring chamber between the diaphragm and a strong compression spring, whose opposing end abuts the housing of the section.

When applying the parking brakes, the spring brake actuator pressure is discharged from the pressure chamber and the large force compression spring pushes the pressure plate and the diaphragm toward the dividing wall between the spring brake actuator and the service brake actuator. In this position, an actuator rod or tube connected to the pressure plate is pushed for applying the parking or emergency brakes and thus immobilizing the vehicle. To release the parking brake, pressurized air is introduced into the pressure chamber of the spring brake actuator to expand the pressure chamber, move the diaphragm and pressure plate toward the opposing end of the spring brake actuator housing, and compress the compression spring.

Disc brakes, in particular for heavy load trucks, are known with different configurations. For example, disc brakes may include either a sliding caliper or a fixed caliper, which overlap one or more brake discs of a vehicle, such as a truck. Disc brakes are operatively connected to the brake actuator such that actuation of the brake actuator moves the brake pads into engagement with the brake disc to brake the vehicle.

Different methods are known for detecting the stroke position of a brake actuator, including the use of string potentiometers, hall-effect sensors, optical sensors, rotary dial visual indicators, and magnetic sensors. While these sensors may generally work for their intended purposes, drawbacks include the following: hall-effect sensors and magnetic sensors require isolation from metal components in the brake system except for the component whose position is being sensed, which must be metal and in close proximity to the sensor; string potentiometers require physical attachment to the component being measured; rotary dial visual indicators must be viewed for inspection; and optical sensors are relatively expensive and sensitive to changes in optical reflectivity.

BRIEF SUMMARY OF THE INVENTION

One embodiment of the invention described herein is directed toward a brake actuator comprising a pushrod configured to actuate a brake of a vehicle. The pushrod is movable between a retracted position and an extended position to actuate the brake. A brake actuator component is operatively coupled to the pushrod. A sensor is configured to emit a signal directed toward the brake actuator component and to receive the signal after the signal bounces off the brake actuator component and is reflected back to the sensor.

In one embodiment, the brake actuator includes a controller communicatively coupled to the sensor and configured to determine a position of the brake actuator component based on data received from the sensor. The sensor may be configured to transmit the data to the controller, the data representative of the time difference between when the sensor emitted the signal and when the sensor received the signal.

In one embodiment, the sensor is an acoustic sensor. The signal emitted by the acoustic sensor is one of an infrasonic signal, a sonic signal, or an ultrasonic signal.

In one embodiment, the sensor includes an emitter configured to emit the signal and a receiver configured to receive the signal. The emitter and receiver may be disposed at generally the same location.

In one embodiment, the brake actuator includes a spring brake actuator including at least one of a diaphragm or a plate, wherein the brake actuator component is one of the diaphragm of the spring brake actuator or the plate of the spring brake actuator.

In one embodiment, the brake actuator includes a service brake actuator including at least one of a diaphragm or a plate, wherein the brake actuator component is one of the diaphragm of the service brake actuator or the plate of the service brake actuator. The brake actuator may also include a spring brake actuator and a second sensor that is configured to emit a second signal toward a portion of the spring brake actuator and receive the second signal after the second signal bounces off the portion of the spring brake actuator and is reflected back to the second sensor.

Another embodiment of the present invention is directed toward a disc brake comprising opposing first and second brake pads configured to move toward one another to engage a brake disc of a vehicle. The disc brake also comprises a disc brake component and a sensor configured to emit a signal directed toward the disc brake component. The sensor is configured to receive the signal after the signal bounces off the disc brake component and is reflected back to the sensor. At least one of the disc brake component and the sensor are configured to move relative to the other as the first and second brake pads move.

In one embodiment, the disc brake includes a controller communicatively coupled to the sensor and configured to determine a position of the disc brake component based on data received from the sensor. The sensor may be configured to transmit the data to the controller, the data representative of the time difference between when the sensor emitted the signal and when the sensor received the signal.

In one embodiment, the sensor is an acoustic sensor. The signal emitted by the acoustic sensor is one of an infrasonic signal, a sonic signal, or an ultrasonic signal.

In one embodiment, the sensor includes an emitter configured to emit the signal and a receiver configured to receive the signal. The emitter and receiver may be disposed at generally the same location.

In one embodiment, the disc brake component is one of a lever of a brake actuation mechanism, a slide pin of a brake carrier or a brake pad retainer configured to support at least one of the first or second brake pads.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

First Embodiment of Brake Actuator

FIGS. 1-4show a tandem-type pneumatic brake actuator, generally indicated at reference numeral10, comprising a service brake actuator12in combination with a spring brake actuator14. The service brake actuator12applies and releases the service or operating brakes of a vehicle. The spring brake actuator14is used to apply the emergency or parking brakes of the vehicle. It is understood that the pneumatic brake actuator10is illustrative and that types of brake actuators other than pneumatic are within the scope of the present invention.

The service brake actuator12includes a housing16having first and second end walls16aand16band a side wall16cthat is joined with and extends between the end walls16aand16b. The spring brake actuator14includes a housing18having first and second end walls18aand18band a side wall18cthat is joined with and extends between the end walls18aand18b. The housings16and18are formed by an adapter housing20that is coupled with a service brake cover22and a spring brake cover24. The adapter housing20and service brake cover22are clamped together with a clamp25to secure the service brake cover22to the adapter housing20. Similarly, the adapter housing20and spring brake cover24are clamped together with another clamp25to secure the spring brake cover24to the adapter housing20. The adapter housing20defines a common dividing wall separating the service brake housing16from the spring brake housing18while forming a portion of each housing16and18such that the second end walls16band18bare integral. Other configurations are within the scope of the present invention.

Movable members, which in this embodiment include elastomeric diaphragms30and32, span the interior of the service and spring brake housings16and18, respectively. A peripheral edge of the diaphragm30is sealingly clamped between the adapter housing20and service brake cover22via the clamp25. A peripheral edge of the diaphragm32is sealingly clamped between the adapter housing20and the spring brake cover24via the clamp25. A piston-type brake actuator, which has a piston that spans the interior of a cylindrical spring brake housing instead of a diaphragm, is also within the scope of the present invention.

Referring to the service brake actuator12, the diaphragm30fluidly divides the service brake actuator12into a pushrod chamber36and a service brake pressure chamber38. A pushrod40has a first end40athat is positioned within the pushrod chamber36and a second end40bpositioned outside of the service brake housing16. A pressure plate42is joined to the first end40aof the pushrod40and abuts diaphragm30. The pushrod40extends from its first end40ato its second end40bthrough an opening46in the service brake cover22. An expandable/condensable sleeve47extends between the opening46and pushrod40to form a fluid tight seal there-between. A return spring48is positioned between the first end wall16aand the pressure plate42to aid in biasing the pressure plate42and pushrod40toward the second end wall16bof the service brake housing16. As explained in more detail below, the pushrod40is configured to actuate a brake (e.g., disc brake) of a vehicle. The pushrod40is movable between a retracted position (FIG. 1) and an extended position (FIG. 3) to actuate the brake. Although not shown, in a brake assembly, the end40bof the pushrod40is operatively coupled to the brake whereby the reciprocation of the pushrod40relative to the service brake housing16results in the application and release of the brake.

The service brake pressure chamber38is fluidly connected to a source of pressurized air through an inlet port (not shown). As the operator of the vehicle applies the brake pedal, pressurized air is introduced into the service brake pressure chamber38through the inlet port to reciprocate or move the pushrod40from the retracted position to the extended position. The addition of pressurized air into the service brake pressure chamber38moves the diaphragm30, pressure plate42and pushrod40away from the second end wall16btoward the first end wall16ato apply the brakes. As the operator of the vehicle releases the brake pedal, the pressurized air is exhausted from the service brake pressure chamber38through the inlet port and the return spring48returns the pushrod40back to the retracted position shown inFIG. 1.

Referring to the spring brake actuator14, the diaphragm32fluidly divides the spring brake housing18into a spring brake pressure chamber56and spring chamber58. A secondary pushrod82has a first end82athat is positioned within the spring brake pressure chamber56and a second end82bpositioned in the service brake pressure chamber38. A first pressure plate84is joined to the first end82aof the secondary pushrod82and abuts the diaphragm32. A second pressure plate86is joined to the second end82bof the secondary pushrod82and abuts the diaphragm30. The secondary pushrod82extends from its first end82ato its second end82bthrough a bearing90defining an opening in the second end wall18bof the adapter housing20. A return spring88is positioned between the second end wall18band the first pressure plate84to aid in biasing the first pressure plate84and secondary pushrod82toward the first end wall18aof the spring brake housing18. The spring brake pressure chamber56is fluidly connected to a source of pressurized air through a port85. A pressure plate60is positioned in the spring chamber58adjacent to the diaphragm32. A large force compression spring62is placed between the pressure plate60and the spring brake cover24.

The brake actuator10further comprises a caging bolt assembly118(FIG. 1) that is operable to mechanically retract and hold the large force compression spring62in a compressed state (as shown inFIG. 1). The caging bolt assembly118includes an adjustment nut120threaded onto a caging bolt122from one end of the caging bolt122. An opposite end of the caging bolt122includes a caging bolt head124that is configured to be releasably coupled to the pressure plate60. To use the caging bolt assembly118, the caging bolt head124is inserted through the opening126in housing18and through the central opening of pressure plate60. The caging bolt122is then rotated to the position shown inFIG. 1, in which it engages the pressure plate60. A washer92is placed on caging bolt122and the adjustment nut120is threaded down the caging bolt122until the washer92engages the housing18. The adjustment nut120is rotated to move the caging bolt head124toward the end wall18aof housing18. As the caging bolt head124moves, it moves the pressure plate60toward end wall18aand compresses or cages the compression spring62between the pressure plate60and end wall18a. When the brake actuator10is in active use on a moving vehicle, the caging bolt122is withdrawn through the opening126, and the cap128is used to cover the opening126, as shown inFIG. 2.

To actuate the brake of a vehicle with the service brake actuator12, pressurized air is directed into the service brake pressure chamber38to push the diaphragm30and pressure plate42toward the first end wall16aof the housing16. This moves the pushrod40from the retracted position to the extended position to operate the brake of the vehicle. When the pressurized air is exhausted from the service brake pressure chamber38, the return spring48pushes the pressure plate42and diaphragm30toward the second end wall16bof the housing16. This moves the pushrod from the extended position back to the retracted position. Similarly, to actuate the brake of a vehicle with the spring brake actuator14, pressurized air is exhausted from the spring brake pressure chamber56. As a result, the compression spring62pushes the diaphragm32, secondary pushrod82, and first and second pressure plates84,86toward the first end wall16aof the housing16. As the second pressure plate86moves, the second pressure plate86pushes against the diaphragm30and the pressure plate42to move the pushrod40from the retracted position to the extended position. To disengage the brake, pressurized air is forced into the spring brake pressure chamber56to push the diaphragm32and pressure plate60toward the first end wall18aof the housing18. The force of the pressurized air is sufficient to overcome the force of the compression spring62. As the pressurized air moves the diaphragm32toward the first end wall18aof the housing18, the return springs48and88move the respective pushrod40and secondary pushrod82toward the first end wall18aas well. Further details on brake actuators may be found in U.S. Pat. No. 8,978,839, the entirety of which is hereby incorporated by reference.

Still referring toFIGS. 1-4, the brake actuator10includes a sensor150used to determine the position of a brake actuator component (e.g., the diaphragm32and/or pressure plate60), which in turn may be used to determine whether the emergency/parking brakes are engaged or disengaged. The sensor150is configured to emit a signal directed toward a brake actuator component and to receive the signal after the signal bounces off the brake actuator component and is reflected back to the sensor. Broadly, the brake actuator component is any component or element of the brake actuator10that reflects the signal from the sensor150. By determining the length of time it takes between when the signal is emitted and received by the sensor150, the distance between the sensor150and the brake actuator component can be determined. In the illustrated embodiments (FIGS. 1-7), the brake actuator component is operatively coupled to the pushrod40and is configured to move the pushrod40from the retracted position to the extended position. Thus, movement of the brake actuator component corresponds to movement of the pushrod40and actuation of the brake of the vehicle assuming that all aspects of the brake system are operating as intended. In these embodiments, where the sensor150is mounted at a stationary location on the brake actuator10, the brake actuator component is any component or element of the brake actuator10capable of moving as the pushrod40moves to actuate the brake of a vehicle (including the pushrod40). In the illustrated embodiment shown inFIGS. 1-4, the brake actuator component the position of which is being sensed is the pressure plate60. The sensor150is mounted on the first end wall18aof the housing18and directs the signal toward the pressure plate60. In other embodiments, the brake actuator component may be any one of the diaphragm30, diaphragm32, pressure plate42, first pressure plate84, second pressure plate86, etc.

Referring toFIG. 13, the sensor150includes an emitter154configured to emit the signal and a receiver156configured to receive the signal. The emitter154emits the signal toward the brake actuator component158and the receiver156receives the signal after the signal bounces off the brake actuator component158and returns to the sensor150. The emitter154and receiver156are both part of the sensor150and, therefore, are disposed at generally the same location on and/or within the brake actuator10. For example, the sensor150can have a wide variety of different configurations such as a printed circuit board (PCB) base with the emitter and receiver mounted thereon. Preferably, the sensor150is an acoustic sensor. In this case, the signal emitted by the acoustic sensor150can be one of an infrasonic signal, a sonic signal or an ultrasonic signal. Other configurations of the sensor are within the scope of the present invention.

In one embodiment, the sensor150is communicatively coupled (either wired or wirelessly) to a controller152(FIG. 12), such as an onboard-computer of the vehicle. The sensor150is configured to transmit data to the controller152. In one embodiment, the transmitted data is representative of the time difference between when the sensor150emitted the signal and when the sensor150received the signal. The controller152can then take this information (e.g., time difference) and determine the distance between the sensor150and the brake actuator component (e.g., pressure plate60) by multiplying the time difference by the speed of the signal in the fluid medium (e.g., air) between the sensor150and brake actuator component. By knowing the distance between the sensor150and brake actuator component, a determination can be made by the controller152of the position of the brake actuator component. Specifically, the controller152can determine a position of the brake actuator component based on the data transmitted by the sensor150. For example, in the illustrated embodiment where pressure plate60is the brake actuator component, one distance measured by the sensor150corresponds to the pressure plate60being in the retracted position shown inFIGS. 1-3, and a second, larger distance measured by the sensor150corresponds to the pressure plate60being in the extended position shown inFIG. 4. As described above, when pressure plate60is in the extended position, pushrod40is also in the extended position. Knowing the position of the pushrod40, via the position of the brake actuator component, enables a determination to be made by the controller152on whether or not the pushrod40has actuated the brake of the vehicle. The data transmitted by the sensor150may include the times the signal was sent and received and/or the length of time between when the signal was sent and received. In other embodiments, the sensor150may determine the distance between the sensor and the brake actuator component and transmit this information to the controller152.

The controller152may compare the distance recorded by the sensor150with a reference distance stored in the controller (e.g., the reference distance may be the distance between the sensor150and brake actuator component when the brake actuator component is in the retracted position). By comparing the distance recorded by the sensor with a reference distance, the controller152may then determine the position of the brake actuator component relative to the reference distance. For example, the controller152may determine how far the brake actuator component has advanced from the retracted position to the extended position. Based on this, the controller152may then further determine how far the pushrod40has extended from the end wall16aof the brake actuator10.

Second Embodiment of Brake Actuator

An alternative embodiment of a brake actuator, generally indicated by reference numeral200, where the diaphragm32is the brake actuator component is shown inFIG. 5. In this embodiment, the sensor150is disposed on the second end wall18bof the housing18. The brake actuator200is generally identical to brake actuator10except that the sensor150is mounted on the second end wall18bof the housing18and emits a signal toward the diaphragm32, which is the brake actuator component in this case. In this embodiment, the distance between the sensor150and diaphragm32is used to determine the position of the diaphragm32, which as described above in connection with the embodiment shown inFIGS. 1-4may be used to determine whether the emergency/parking brakes are engaged or disengaged. It is understood that the distance between the sensor150and diaphragm32decreases when the diaphragm32and pushrod40are moved from the retracted position to the extended position in this embodiment. Controller152may be used with brake actuator200in substantially the same manner as described above with respect to brake actuator10.

Third Embodiment of Brake Actuator

Another alternative embodiment of a brake actuator, generally indicated by reference numeral300, where the diaphragm30is the brake actuator component is shown inFIG. 6. In this embodiment, the sensor150is disposed on the second end wall16bof the housing16. The brake actuator300is generally identical to brake actuator10except that the sensor150is mounted on the second end wall16bof the housing16and emits a signal toward the diaphragm30, which is the brake actuator component in this case. In this embodiment, the distance between the sensor150and diaphragm30is used to determine the position of the diaphragm30, which also corresponds with the position of pushrod40. Controller152may be used with brake actuator300in substantially the same manner as described above with respect to brake actuator10.

Fourth Embodiment of Brake Actuator

Another alternative embodiment of a brake actuator, generally indicated by reference numeral400, where the diaphragm30or pressure plate42is the brake actuator component is shown inFIG. 7. In this embodiment, the sensor150is disposed on the first end wall16aof the housing16. The brake actuator400is generally identical to brake actuator300except that the sensor150is mounted on the first end wall16aof the housing16and emits a signal toward the diaphragm30or pressure plate42, which is the brake actuator component in this case. In this embodiment, the distance between the sensor150and diaphragm30or pressure plate42is used to determine the position of the diaphragm30or pressure plate42, which corresponds with the position of pushrod40. It is understood that the distance between the sensor150and diaphragm30decreases when the pushrod40is moved from the retracted position to the extended position in this embodiment. Controller152may be used with brake actuator400in substantially the same manner as described above with respect to brake actuator10.

Additional Embodiments of Brake Actuator

Other configurations of the sensor150and brake actuator component are within the scope of the present invention. The sensor150and brake actuator component may both move as the pushrod40moves or the sensor150may move relative to the brake actuator component (e.g., the brake actuator component is stationary) as the pushrod40moves. For example, in one embodiment the sensor150may be mounted on a component (e.g., diaphragm30, diaphragm32, pressure plate42, first pressure plate84, second pressure plate86, etc.) that moves with the pushrod40and the brake actuator component is stationary relative to the pushrod40. In one such example, the sensor150may be mounted on pressure plate60and be configured to emit a signal toward the first end wall18aof the housing18, which is the brake actuator component in this case. Thus, other configurations are possible where the sensor150and brake actuator component are configured to move relative to one another as the pushrod40moves between the retracted and extended positions.

Further, multiple sensors150may be used with brake actuators10,200,300, and400. For example, brake actuator10may include a first sensor150that is positioned in the spring brake housing18and configured to sense the position of the diaphragm32or pressure plate60(e.g., as shown inFIGS. 1-5and described above) and a second sensor150that is positioned in the service brake housing16and configured to sense the position of the diaphragm30or pressure plate42(e.g., as shown inFIGS. 1-6and described above). Multiple sensors150may be used with brake actuator10in this manner to both determine whether the emergency/parking brakes of the brake actuator10are actuated (as shown inFIG. 4) and to determine whether the service brakes of the brake actuator10are actuated when the emergency/parking brake are not actuated (as shown inFIG. 3). In addition, brake actuator10may include multiple sensors150to sense the position of the diaphragm32or pressure plate60. For example, a first sensor150may be placed in the location shown inFIGS. 1-4and a second sensor150may be placed in the location shown inFIG. 5. Multiple sensor150may be used with brake actuator10in this manner for redundancy purposes. Likewise, brake actuator10may include multiple sensors150to sense the position of the diaphragm30or pressure plate42. For example, a first sensor150may be placed in the location shown inFIG. 6and a second sensor150may be placed in the location shown inFIG. 7for redundancy.FIG. 12shows one example of a multiple sensor system, in which controller152may be communicatively coupled to any number of sensors150, including a first sensor150a, a second sensor150b, and an nth sensor150c.

The controller152may further receive information from other components of the vehicle's braking system and compare that information to the data transmitted by the sensor150. For example, the controller152may receive a pressure signal that corresponds with a service brake pressure of the braking system (i.e., the pressure of the system connected to service brake pressure chamber38) and/or a pressure signal that corresponds with a spring/emergency brake pressure of the braking system (i.e., the pressure of the system connected to spring brake pressure chamber56). When sensor150is positioned to measure the diaphragm30or pressure plate42of the service brake actuator12, the controller152may compare the actual position of the diaphragm30or pressure plate42as measured by sensor150with an expected position of the diaphragm30or pressure plate42based on the pressure signal corresponding with the service brake pressure. Likewise, when sensor150is positioned to measure the diaphragm32or pressure plate60of the spring brake actuator14, the controller152may compare the actual position of the diaphragm32or pressure plate60as measured by sensor150with an expected position of the diaphragm32or pressure plate60based on the pressure signal corresponding with the spring brake pressure. If the actual position is different from the expected position by more than a predetermined amount, the controller152may generate an error signal. The controller152may be communicatively coupled to a visual indicator (e.g., a display screen) positioned in a cab of the vehicle. The controller152may send the error signal to the visual indicator to alert a driver of a potential issue with the braking system. The controller152may further be communicatively coupled to an external computer system with the capability to log the error signal and alert personnel of a potential issue with the vehicle's braking system. The controller152may also be communicatively coupled to an ABS system of the vehicle, a roll stability system of the vehicle, and/or an electronic suspension control system of the vehicle for receiving data from the various vehicle systems and comparing such data to the data from sensors150.

Sensor150provides many advantages over conventional position sensing systems. Conventional hall-effect sensors and magnetic sensors require isolation from the metal components in the brake actuator except for the component being detected or measured which must itself comprise metal and must be in close proximity to the component being detected. Sensor150does not have these limitations, allowing the sensor150to be placed at generally any position on the brake actuator. Further, sensor150has the ability to measure the movement of components composed of materials other than metal. Conventional string potentiometers require physical attachment to the component being measured, which is not required by sensor150. Conventional contact sensors and sensors utilizing mechanical rotation also rely on mechanical interfaces which can fail and generally have lower reliability and accuracy. Sensor150is a non-contact sensor without mechanical interfaces, resulting in more reliability and better accuracy. Sensor150is also generally a more cost-effective solution compared to conventional optical sensors, which are also sensitive to changes in optical reflectivity.

First Embodiment of Disc Brake

Referring toFIGS. 8-11, alternative embodiments are shown with the sensor150mounted on a disc brake, generally indicated at reference numeral500. As will be explained in more detail below, in these embodiments the sensor150is used to measure a distance between itself and a disc brake component to determine the position of the disc brake component and likewise determine whether or not the disc brake500has engaged a brake disc (not shown) of the vehicle.

The disc brake500includes a brake caliper502which is slideably guided on a carrier504by slide pins506(FIG. 10). The slide pins506are fixed to the carrier504by bolts508and received in openings510in the housing of the brake caliper502. Bushings512are provided between the slide pins506and the inner wall of the openings510. End caps514sealingly close the openings510to protect the slide pins506and bushings512.

The brake caliper502overlaps and surrounds brake pads516(e.g., first and second brake pads) which are mounted on brake pad retainers518. Each brake pad retainer518is configured to support one of the brake pads516. A holding bracket520overlaps the brake pads516and brake pad retainers518and secures the brake pads516and brake pad retainers518in the disc brake500. Releasing the holding bracket520enables the brake pads516and brake pad retainers518to be inserted and removed from the disc brake500. The opposing brake pads516are positioned on opposite sides of a brake disc (not shown), which is operatively fixed to a hub of a wheel axle. The disc brake500is configured to move the brake pads516toward one another to engage the brake disc, thereby braking the vehicle.

The disc brake500includes a brake actuation mechanism522that, when actuated, moves the brake pads516toward one another to engage the brake disc and brake the vehicle. The brake actuation mechanism522is housed within the caliper502. The brake actuation mechanism522includes a lever524, which has an upper end that is positioned adjacent an opening in the caliper502and is operatively coupled to the brake actuator10. Specifically, the lever524has a recess525that receives an end of the pushrod40of the brake actuator10such that movement of the pushrod40moves the lever524to actuate the disc brake500. The lever524is pivotably supported by the caliper502against two rollers526. As the lever524is pivoted or rotated around the rollers526by the pushrod40from the brake actuator10, the structure of the lever524causes an eccentric displacement or offset of the lever524toward the brake pads516, which moves the brake pads516into engagement with the brake disc as the caliper502slides on the slide pins506to the right when viewed as shown inFIGS. 8 and 9. Further details on the construction and operation of the disc brake500may be found in U.S. Pat. No. 9,803,711, the entirety of which is hereby incorporated by reference.

As mentioned above, the disc brake500includes the sensor150used to measure a distance between itself and a disc brake component to determine the position of the disc brake component and whether or not the disc brake500has engaged the brake disc of the vehicle. The operation of the sensor150when included as part of the disc brake500is generally the same as the operation of the sensor150when included as part of the brake actuator10. Accordingly, it is understood the teachings of the sensor150set forth in relation to the brake actuator10apply equally to the sensor's150application with the disc brake500and vice versa.

The sensor150is configured to emit the signal toward the disc brake component and to receive the signal after the signal bounces off the disc brake component and is reflected back to the sensor150. Broadly, the disc brake component is any component or element of the disc brake500that reflects the signal from the sensor150. By determining the length of time it takes between when the signal is emitted and received by the sensor150, the distance between the sensor150and the disc brake component can be determined. The disc brake component and sensor150move relative to one another as the brake pads516are moved. Thus, as the brake pads516are moved into and out of engagement with the brake disc, the distance between the sensor150and disc brake component changes. As mentioned above, the sensor150can be communicatively coupled to a controller152, which can be configured to determine the position of the disc brake component based on the data received from the sensor150. This information (e.g., the position of the disc brake component) can then be used to determine whether or not the disc brake500is braking the vehicle (e.g., whether or not the brake pads516are engaging the brake disc). For example, similar to as described above with respect to the brake actuator10, the controller152may compare the distance recorded by the sensor150with a reference distance stored in the controller (e.g., a distance between the sensor150and disc brake component when the disc brake500is not actuated). By comparing the distance recorded by the sensor150with the reference distance, the controller152may then determine the position of the disc brake component relative to the reference distance. For example, the controller152may determine how far the disc brake component has advanced from the unactuated position to the actuated position. Based on the distance of movement of the disc brake component, the controller152may further be capable of determining how far the brake pads516have moved toward the brake disc.

In the illustrated embodiments (FIGS. 8-11), the disc brake component is operatively coupled to the brake pads516and is configured to move as the brake pads516are moved toward each other (e.g., the disc brake component moves relative to the sensor150as the brake pads516move). Thus, movement of the disc brake component corresponds to movement of the brake pads516and actuation of the disc brake500. In these embodiments, the disc brake component can be any component or element of the disc brake500that moves as the brake pads516move. Further, the sensor150may be mounted at a stationary location (e.g., on the carrier504or slide pins506) or on a component that moves relative to the disc brake component (e.g., on the caliper502). In addition, both the sensor150and disc brake component may move as the disc brake500is actuated (e.g., as described below in connection withFIG. 11). In the illustrated embodiment shown inFIGS. 8 and 9, the disc brake component is the lever524. The sensor150is mounted on the caliper502and directs the signal toward the lever524, specifically the upper end thereof. In other embodiments, the disc brake component may be any one of the slide pins506, brake pad retainers518, brake pads516, another component of the brake actuation mechanism522, etc.

Second Embodiment of Disc Brake

An alternative embodiment of a disc brake, generally indicated by reference numeral600, where the slide pin506is the disc brake component is shown inFIG. 10. In this embodiment, the sensor150is disposed on the end cap514. The disc brake600is generally identical to disc brake500except that the sensor150is mounted on one of the end caps514and emits a signal toward the corresponding slide pin506, which is the disc brake component in this case. In this embodiment, the distance between the sensor150and slide pin506is used to determine whether or not the disc brake500is braking the vehicle. In this case, the sensor150moves with movement of the caliper502and the slide pin506remains stationary. The distance between the sensor150and the end of the slide pin506increases as the brakes are applied. Controller152may be used with disc brake600in substantially the same manner as described above with respect to disc brake500.

Third Embodiment of Disc Brake

Another alternative embodiment of a disc brake, generally indicated by reference numeral700, where the brake pad retainer518is the disc brake component is shown inFIG. 11. In this embodiment, the sensor150is disposed on a side wall of the caliper502facing the brake pad retainer518. The disc brake700is generally identical to disc brake500except that the sensor150is mounted at a different position on the caliper502and emits a signal toward one of the brake pad retainers518, which is the disc brake component in this case. In this embodiment, the distance between the sensor150and brake pad retainer518is used to determine whether or not the disc brake500is braking the vehicle. The sensor150moves with movement of the caliper502in one direction and the brake pad retainer518moves in an opposite direction toward the brake disc. The distance between the sensor150and the brake pad retainer518increases as the brakes are applied. Controller152may be used with disc brake700in substantially the same manner as described above with respect to disc brake500.

Additional Embodiments of Disc Brake

Other configurations of the sensor150and disc brake component are within the scope of the present disclosure. The sensor150and disc brake component may both move as the brake pads516move, the sensor150may move relative to the disc brake component (e.g., the disc brake component is stationary) as the brake pads516move, or the disc brake component may move relative to the sensor (e.g., the sensor is stationary). For example, in one embodiment the sensor150may be mounted on a component (e.g., carrier504or slide pins506) that does not move with the brake pads516while the disc brake component moves with the brake pads516(e.g., the disc brake component is operatively coupled to the brake pads516and moves relative to the sensor150as the brake pads516move). In one such example, the sensor150may be mounted on the slide pin506and be configured to emit a signal toward the end cap514, which is the disc brake component in this case.

Similar to as described above with respect to brake actuator10, multiple sensors150may be used with disc brakes500,600, and700. For example, disc brake500may include any combination of a first sensor150that is positioned to sense the position of lever524, as shown inFIG. 9, a second sensor150that is positioned to sense the position of brake pad retainer518, as shown inFIG. 11, and a third sensor150that is positioned to sense the position of slide pin506, as shown inFIG. 10. Multiple sensors150may be used with disc brake500in this manner for redundancy purposes or to detect whether there is a potential error with operation of disc brake500. For example, the controller152may compare the data received from the sensors150to determine if there is a discrepancy between an actual reading received from a sensor and an expected reading based on data received from another sensor. If the sensor150sensing the position of lever524indicates that lever524is actuated, while the sensor150sensing the position of brake pad retainer518indicates that the brake pad retainer518has not moved an expected distance based on actuation of lever524, the controller152may generate an error signal indicating that there is a potential error in operation of disc brake500. The controller152when used with the disc brake500may further receive information from other components of the vehicle's braking system (e.g., service brake pneumatic system, spring brake pneumatic system, ABS system, roll stability system, and/or electronic suspension control system) and compare that information to the data transmitted by the sensor150, as described above in connection with brake actuator10.

Example issues that may be detected by the controller152include a dragging brake (i.e., brake pads516engage a brake disc at an undesired time and/or with an undesired amount of pressure), a broken parking brake compression spring62, and a chamber over stroke condition (i.e., the second end40bof the pushrod40is extended farther away from the end wall16athan desired). A dragging brake may be detected, for example, by determining that the brake pad retainer518and brake pad516are at a greater distance than desired from sensor150(seeFIG. 11) at a particular time. A broken parking brake compression spring62may be detected, for example, by determining that the diaphragm32, pressure plate60, diaphragm32, and/or pressure plate42are not in a position consistent with actuation of the brakes (i.e., they have not moved an expected distance toward end wall16a) when pressure is released from the spring brake pressure chamber56. A chamber over stroke condition may be detected, for example, by determining that the diaphragm30and/or pressure plate42have moved more than an expected distance toward end wall16awhen the brakes are actuated.

Brake System

A brake system that includes both at least one of brake actuators10,200,300or400and at least one of disc brakes500,600, or700is also within the scope of the present invention. In such a system, one or more sensors150may sense the position of components of the brake actuator10,200,300, or400, as described above, and one or more sensors150may sense the position of components of the disc brake500,600, or700, as described above. The controller152may be communicatively coupled to all of the sensors, as shown inFIG. 12, and receive the data from the sensors150of both the brake actuator10,200,300, or400and disc brake500,600, or700. The controller152may determine positions of components of the brake actuator10,200,300, or400and/or disc brake500,600, or700in the same manner as described above with respect to brake actuator10and disc brake500. The controller152may further compare the data received from the various sensors150to determine if there is a potential error with operation of either the brake actuator10,200,300, or400or the disc brake500,600, or700. For example, if a sensor150associated with the brake actuator10indicates that the brake actuator10is not actuated, while a sensor150associated with the disc brake500indicates that the disc brake500is actuated, the controller152may generate an error signal indicating a potential error in operation of the disc brake500(e.g., the disc brake500has not reset to its unactuated position).

The specific arrangements of the sensor150described in this application are exemplary only as other types of arrangements are contemplated by and fall within the scope of the present invention.

From the foregoing it will be seen that this invention is one well adapted to attain all ends and objectives herein-above set forth, together with the other advantages which are obvious and which are inherent to the invention.

Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative, and not in a limiting sense.

While specific embodiments have been shown and discussed, various modifications may of course be made, and the invention is not limited to the specific forms or arrangement of parts and steps described herein, except insofar as such limitations are included in the following claims. Further, it will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.