Patent Description:
Mechanical issues or malfunctions can occur while driving. For example, a truck's brakes may not be fully released, there may be remaining pressure in the brake chamber and/or there can be pure mechanical issues such as locked mechanics. Examples of mechanical issues in the wheel endZ brakes include, for example, stiff pistons, stiff lever/shaft bearing, and broken or fatigued springs. Such issues or malfunctions occurring on an axle while driving can, for example, cause the brakes to overheat, cause the tires to suddenly deflate or initiate a thermal incident on the truck and/or the trailer. From <CIT> a method for monitoring a brake component is known.

Thermal incidents on the trailer and other brake system failures as described above can result in trucks and/or trailers being put out of service which, in turn, can cause shipping delays, repair costs, increased shipping costs and the like. Further, disabled trailers and trucks can further result in serious traffic incidents and safety issues.

The current Anti-lock Braking System (ABS)/Electronic Braking System (EBS) brake systems use wheel speed sensors (WSS) to determine the speed of the wheel and have no ability to detect wheel end specific malfunctions such as locked mechanics, a remaining pressure in the brake chamber, etc..

It is an object of the present invention to provide a method for monitoring a wheel end brake temperature in a truck and trailer.

The aforementioned object is achieved via a method for monitoring a brake component temperature of a brake of a vehicle according to claim <NUM>.

The method includes measuring a wheel end temperature at a wheel end of a vehicle via a temperature sensor at the wheel end; determining whether the measured wheel end temperature is above a threshold representative of a critical temperature of the brake component; and, outputting a warning signal when the determined wheel end temperature is above the threshold.

According to the invention the determining whether the measured wheel end temperature is above the threshold includes: determining via a control unit a temperature value of a brake component on a basis of the measured temperature at the wheel end and at least one of a distance of the temperature sensor to the corresponding brake component, and environmental conditions.

Preferred embodiments of the present invention are laid down in the dependent claims.

According to a preferred embodiment, the operating state of the brake is taken into consideration when determining the temperature value of the brake component.

According to a preferred embodiment, the temperature sensor is integrated into a wheel speed sensor unit or an active wheel speed sensor.

According to a preferred embodiment, the brake component monitored by the method is a brake drum or a brake disc.

It is also an object of the present invention to provide a system for monitoring a wheel end brake temperature in a truck and trailer.

The aforementioned object is achieved via a wheel end brake temperature monitoring system according to claim <NUM>.

The system includes a temperature sensor arranged at a wheel end of a vehicle configured to measure a measured wheel end temperature; an electronic control unit configured to receive the measured wheel end temperature from the temperature sensor; the electronic control unit being configured to compare the measured wheel end temperature to a threshold value and output a warning signal when the measured wheel end temperature is above the threshold value.

According to the invention the wheel end brake temperature monitoring system includes an electronic control unit having a temperature modeling unit.

According to the invention the wheel end brake temperature monitoring system includes a temperature modeling unit which is configured to calculate a brake component temperature taking into consideration the measured wheel end temperature, and a distance of said temperature sensor to the brake component.

According to a preferred embodiment, the wheel end brake temperature monitoring system includes a temperature modeling unit configured to further take environmental conditions into account when calculating the brake component temperature.

According to a preferred embodiment, the temperature sensor is integrated in a wheel speed sensor unit or an active wheel speed sensor.

According to a preferred embodiment, the brake component monitored by the system is a brake drum or a brake disc.

Monitoring the wheel end temperature according to the present invention increases the safety of the vehicle itself and the safety of other traffic participants. Further, via temperature monitoring, downtime of the vehicle and costs related thereto such as repair, idle and unproductive driver time, potential delivery delays or inability to keep made commitments and associated lost business opportunities can be avoided.

The invention will now be described with reference to the drawings wherein:.

<FIG> shows a vehicle <NUM> having anti-lock braking system (ABS) <NUM>. The description below also applies to an electronic braking system (EBS). In the shown embodiment, the front axle <NUM> has a first front wheel <NUM> and a second front wheel <NUM> mounted on either side or end of the front axle <NUM>. The rear axle <NUM> has a first rear wheel pair <NUM> and a second rear wheel pair <NUM> mounted on either side or end thereof. The wheel configuration is used as an example, other wheel configurations, for example, with single wheels on the rear axle, multiple rear axles, et cetera, are also possible. Various trailer configurations are also possible. A brake chamber <NUM> is provided for each front wheel <NUM>, <NUM> and each rear wheel pair <NUM>, <NUM>. The brake chambers <NUM> are each activated via a corresponding brake valve <NUM> which can be actuated by an operator, for example, via a brake pedal <NUM>. A compressor <NUM> acts as a pressure source for activating brake chambers <NUM>. In the embodiment shown in <FIG>, the brake chambers <NUM> associated with the rear wheel pairs <NUM>, <NUM> of the rear axle <NUM> are configured as tristop cylinders. The anti-lock braking system of the shown embodiment further includes a hand brake valve <NUM> which can also activate the brake chambers <NUM> of the wheel pairings <NUM>, <NUM>.

In the shown embodiment of <FIG>, the vehicle <NUM> is a towing vehicle. The compressor can be operatively connected to brake chambers of a trailer vehicle via a trailer control valve <NUM> and a coupling head <NUM>. The anti-lock braking system <NUM> provides power for trailer anti-lock braking system via the standardized trailer plug connection <NUM>. An actuation of the brakes caused by the operator actuating the brake pedal <NUM> is conveyed to the trailer vehicle via the trailer control valve <NUM> and the coupling head <NUM>.

The anti-lock braking system <NUM> can monitor the speed of a wheel via a wheel speed sensor unit <NUM>. In the embodiment shown in <FIG>, each of the front wheels has a wheel speed sensor unit <NUM> to detect the wheel speed of the corresponding wheel. Further, each of the rear wheel pairs has a wheel speed sensor unit <NUM> to detect the wheel speed of the corresponding wheel pair. The wheel speed sensor units <NUM> output the detected wheel speed to a control device, for example, an ABS electronic control unit <NUM>. Wheel speed sensor units <NUM> associated with wheels or wheel pairs of a trailer vehicle can, for example, be received by the control unit <NUM> via a trailer plug connection <NUM>.

The control unit <NUM> uses the signals received from the wheel speed sensor units <NUM> to calculate the vehicle speed based on the single wheel speeds. Additionally, the control unit <NUM> can calculate wheel deceleration and acceleration values and, if necessary, can actuate a solenoid control valve <NUM> to prevent a locking of the vehicle wheels. The control unit <NUM> can also alert the driver to any faults in the anti-lock braking system <NUM>, for example via a warning sound, a warning light, or other visual warning on a display and/or screen.

In an embodiment of the wheel speed sensor unit <NUM>, the wheel speed sensor unit <NUM> can be configured as a rod sensor and a pole wheel for picking up the rotational movement of the wheel. The wheel speed sensor units <NUM> can, for example, be clamped in a hole in the axle or clamped thereto via a bracket. The rod sensor operates inductively and includes a magnet, a round pole pin, and a coil. A rotation of the pole wheel connected to a wheel hub produces a change in the magnetic flux picked up by the sensor coil and thereby generates an alternating voltage. The frequency of this alternating voltage is proportional to the wheel speed. The wheel speed sensor units <NUM> can be connected to the control unit <NUM> via wiring <NUM>.

According to an embodiment of the present invention, the wheel speed sensor unit <NUM> of an ABS system <NUM> further includes a temperature sensor <NUM>.

The number of wheel speed sensor units <NUM> used in the anti-lock braking system <NUM> depends on the vehicle and the configuration of the anti-lock braking system <NUM>. The anti-lock braking system <NUM> can control the pressure in a corresponding brake chamber <NUM> when the control unit <NUM> detects a tendency to lock on the corresponding specific wheel where the friction might be lower compared with other monitored wheels based on a calculated reference speed which is an average from all available individual wheel speed values.

The anti-lock braking system has the capability to keep all wheels rolling and helps to increase the active safety. Only rolling wheels can transfer brake force and cornering force to the road properly and ensure the vehicle's steerability while the driver is able to maintain full control over the vehicle under all circumstances.

According to an embodiment, the temperature at each individual wheel end is monitored via a temperature sensor <NUM> while the vehicle <NUM> is in operation. If the wheel end temperature at any of the wheels <NUM>, <NUM>, <NUM>, <NUM> exceeds a threshold value, a warning signal <NUM> can be outputted by the control unit <NUM>. The warning signal <NUM> can, for example, cause a warning light in the dashboard to become active or otherwise inform the driver of the warning. A temperature measured by the temperature sensor <NUM> at the wheel end can be representative of a temperature of a brake component <NUM> or can be used to determine the temperature of the brake component <NUM> based on factors including the temperature sensor installation position. The brake component <NUM> can, for example, be the brake disc of a disc brake or a brake drum of a drum brake.

According to an embodiment, the temperature sensor <NUM> is integrated into the wheel speed sensor unit <NUM>. The integrated temperature sensor <NUM> is connected to control unit <NUM> and provides the control unit <NUM> with the local temperature for each wheel end. Depending on the distance between the temperature sensor <NUM> and the brake component <NUM>, the temperature detected at the temperature sensor <NUM> may not reflect the actual temperature at the brake component <NUM>.

According to an embodiment, the individually measured brake component <NUM> temperatures are inputted into a temperature modelling unit <NUM>, for example, embodied in the control unit <NUM>. The temperature modeling unit <NUM> calculates a brake component temperature based on factors which can include the temperature measured by the temperature sensor <NUM>, the distance of the temperature sensor <NUM> to the brake component <NUM>, environmental conditions, braking status, speed of the vehicle <NUM>, et cetera. If the calculated brake component <NUM> temperature exceeds a defined threshold (Th_critical), a warning signal is outputted by the control unit <NUM>. The threshold Th_critical for a brake disc can be significantly different from a threshold Th_critical for a brake drum. The temperature modeling unit can be integrated in the control unit <NUM>.

According to an embodiment, the control unit <NUM> is configured to monitor a temperature gradient of the measured wheel end temperature or the brake component <NUM> temperature. The monitored temperature gradient is compared to a temperature gradient threshold.

According to an embodiment, an average wheel end temperature is determined from the individually measured wheel end temperatures. The control unit <NUM> receives the individudal wheel end termperatures measured by the corresponding temperature sensors <NUM> and determines an average therefrom. The threshold can be a defined difference from the determined average wheel end tempterature. Alternatively, the control unit <NUM> may convert the measured wheel end temperatures to brake component temperatures and subsequently determine an average brake component temperature.

Mechanical or pneumatic issues such as a mechanical blockage that may keep the wheel ends active or cause a residual pressure to remain in the brake chambers can cause an overheating of brake component <NUM>. For example, stiff pistons, stiff lever/shaft bearings, broken or fatigued springs and the like can keep the wheel end brake active. Such overheating of the wheel can cause sudden tire deflation and/or a thermal incident in the truck and/or trailer.

The temperature sensor <NUM> in the wheel speed sensor unit <NUM> enables the measuring of the brake component <NUM> temperature based on factors including, for example, the installation position of the temperature sensor <NUM> and the environmental conditions. Active wheel speed sensors (AWSS) may already have temperature sensors integrated therein. The AWSSs of existing anti-lock braking systems are typically not installed close enough to the disc/drum so that the measured temperature does not reflect the real wheel end (disc/drum) temperature. If the temperature measured at the wheel end does not adequately represent a brake disc/drum temperature, a temperature model can consider the installation position and the environmental conditions and calculate a disc/drum temperature.

According to an embodiment, when a calculated disc/drum temperature exceeds a first threshold (Th_wo) without braking or a second threshold (Th_wb) with braking, the control unit outputs a warning signal.

According to an embodiment, the status of the brakes, including the duration in which they were engaged, is monitored and considered in calculating the temperature of the brake component <NUM>.

Unlike typical wheel speed sensors, active wheel speed sensors can include temperature sensors. Existing ABS/EBS systems which use active wheel speed sensors which include temperature sensors can have their control unit updated such that additional control software for temperature monitoring is installed and run thereon. The additional control software can further include a temperature modeling software. Existing ABS/EBS systems which support AWSS can also be supplemented with an additional control unit1.

According to an embodiment, the wheel speed sensor unit or active wheel speed sensor has two pins connected with the electronic control unit (ECU). The number of WSS/AWSS installed in the vehicle can depend on the vehicle/system configuration. The available ECUs are designed for each required use case with the respective number of pins and connectors.

In an embodiment for monitoring the temperature of a brake component, the wheel end temperatures of a vehicle <NUM> are measured via a temperature sensor <NUM>. The measured values are outputted to a control unit <NUM>. The control unit <NUM> may be a separate control unit or can be a control unit <NUM> for the system <NUM>. In configurations where the temperature sensor <NUM> is disposed in close proximity to the brake component which is to be monitored, the measured temperature at the wheel end corresponds or correlates to the temperature of a brake component <NUM>.

In an embodiment, where the temperature sensor <NUM> is integrated into a wheel speed sensor unit <NUM> disposed at a distance to the brake component <NUM>, a temperature modeling unit <NUM> is provided. The temperature modeling unit <NUM> calculates a temperature of a brake component <NUM> or a value representative thereof. Factors used in calculating the brake component temperature can include, for example, distance of the temperature sensor <NUM> to the brake component <NUM>, an outside temperature, status of the brakes, the speed at which the vehicle <NUM> is traveling and the like. If the calculated temperature is above the threshold value, a warning signal is outputted.

In an embodiment, the calculated temperature is compared to a first threshold (Th_wb) if the vehicle's brakes are engaged and a second threshold (Th_wo) if the brakes are not engaged.

According to an embodiment, the active brake times of the brakes are monitored. The active brake times are used for determining the threshold(s). Active use of the brakes increases the temperature of the brake component and factoring the amount of active braking into the determination of the threshold can ascertain if the temperature of the brake component is resulting from active braking or from a mechanical malfunction and the like.

<FIG> shows an embodiment of a method according to the present invention. In a first step <NUM>, the temperature at a wheel end is measured. It is, in a second step <NUM>, then determined whether the measured wheel end temperature exceeds a threshold value. If the temperature measured in step <NUM> exceeds the threshold as determined in step <NUM>, a warning signal is outputted in step <NUM>.

<FIG> shows a further embodiment of a method according to the present invention. The status of the brakes is determined (<NUM>), the temperature at a wheel end is measured (<NUM>), and environmental conditions such as outside temperature, humidity, et cetera, are determined (<NUM>) and outputted to a control unit <NUM>. The control unit <NUM> calculates the temperature of a brake component <NUM> or a value representative thereof (<NUM>). It is then determined whether the calculated temperature value (<NUM>) by the control unit <NUM> is above a threshold. If the temperature calculated (<NUM>) is determined to be above the threshold (<NUM>), a warning signal <NUM> can be outputted (<NUM>).

<FIG> shows an alternate embodiment of the method shown in <FIG>, wherein an average brake component temperature is determined in step <NUM>. The individual brake component temperatures calculated in step <NUM> are then compared to the determined average brake component temperature in step <NUM>. In step <NUM>, a warning signal is outputted when an individual brake component deviates from the average by more than a predefined threshold value.

According to an embodiment, the threshold is a fixed value based on a parameter. According to a further embodiment, the threshold can be a rate of temperature increase. The control unit <NUM> can be configured to output a warning signal, for example, if the control unit <NUM> determines a temperature gradient above a predetermined threshold over a defined time period. Accordingly, a sudden increase in temperature at the wheel end caused by a mechanical issue at the brake can be detected by the temperature monitoring system according to the present invention. This detection can cause an operator to stop and avoid further damage to the vehicle, prevent an accident and the like.

According to an embodiment, the control unit <NUM> detecting a progressive temperature increase above a predetermined threshold at one wheel end via the corresponding temperature sensor <NUM> causes the control unit <NUM> to output a warning signal. The control unit <NUM> can consider environmental factors, brake status and the like to determine if a temperature increase at a wheel end is unexplained, that is, not caused for example by active braking, high environmental temperatures and the like.

<FIG> shows a control unit <NUM> having a temperature modeling unit <NUM>. The program code can be configured to perform methods according to the present invention when executed by a processor. The control unit <NUM> receives wheel end temperatures measured by temperature sensors <NUM>. The control unit <NUM> can further receive environmental data from environmental sensors <NUM> or via a communications link. The control unit <NUM> can include the processor and a non-transitory computer readable storage medium having program code stored thereon. When the control unit <NUM> is the ABS control unit, the status of the brakes <NUM> can also be considered. If the control unit <NUM> is embodied separately from the ABS control unit, the ABS control unit can provide the brake status to the control unit <NUM>. When the control unit <NUM> receives the wheel end temperatures, the temperature modeling unit calculates the temperature of the brake component <NUM>. The control unit <NUM> outputs a warning signal <NUM> if the calculated temperature of the brake component <NUM> exceeds a threshold. The threshold Th_critical can be a parameterizable value. According to an embodiment, the measured wheel end temperature is multiplied by a predetermined factor to be considered can be a distance from the brake component being monitored. Further, a multiplier can be used to account for the outside temperature and the like. The factors to account for the distance between temperature sensor <NUM> and the brake component <NUM>, environmental conditions, brake status and the like and can be predetermined for an individual vehicle, a model type, a vehicle type, etc. The factors can also be updated after the fact, for example, via software updates to the control unit <NUM>.

Claim 1:
A method for monitoring a brake component (<NUM>) temperature of a brake of a vehicle (<NUM>), the method comprising:
measuring (<NUM>; <NUM>) a wheel end temperature at a wheel end of a vehicle (<NUM>)_via a temperature sensor (<NUM>) at the wheel end;
determining (<NUM>) whether said measured wheel end temperature is above a threshold representative of a critical temperature of the brake component (<NUM>); and,
outputting a warning signal (<NUM>) when said determined wheel end temperature is above the threshold, wherein said determining whether the measured wheel end temperature is above the threshold includes:
determining via a control unit (<NUM>) a temperature value of a brake component (<NUM>) on a basis of the measured temperature at the wheel end and at least one of a distance of the temperature sensor (<NUM>) to the corresponding brake component (<NUM>), and environmental conditions.