The invention relates generally to tire monitoring systems. More particularly, the invention relates to systems that monitor conditions in a tire, such as tire pressure. Specifically, the invention is directed to a modular system that determines when a leak of tire pressure occurs and when to issue an alert regarding the leak.
Vehicles include two or more axles that are supported by pneumatic tires. Typically, at least one tire is mounted on each end of each axle. Such tires typically have certain conditions or parameters that are beneficial to monitor during vehicle operation. For example, monitoring the pressure of a pneumatic tire may be helpful in assessing the condition and/or performance of the tire, as a low pressure may indicate that there is an issue with the tire.
To monitor tire pressure, Tire Pressure Monitoring Systems (TPMS) have been developed. A TPMS measures the pressure inside the tire cavity using sensors that are attached to the tire, and typically obtains pressure data in real time from the sensors. Such sensors may be attached to the interior of the tire or to the valve stem of the tire, which is in fluid communication with the tire cavity.
The pressure that is measured by the TPMS may be correlated to a specific tire and transmitted to an electronic control system of the vehicle. The measured tire pressure data may then be employed to improve the function of vehicle systems, such as an anti-lock brake system (ABS), electronic stability control system (ECS), and the like. The measured tire pressure data may also be sent to an operator of the vehicle.
In addition, for fleets of commercial vehicles or passenger vehicles, it is desirable for a manager of the fleet to be informed of tire pressure to make informed decisions about the tires and the vehicle. For example, in the event that a pressure measurement is below a threshold value, an alert may be sent to the fleet manager. The fleet manager may then instruct the vehicle operator to reduce the vehicle speed, direct the vehicle to a service center, and/or schedule an inspection of the tire.
It is desirable to improve the accuracy of pressure measurements in a TPMS, and to determine optimum conditions for the TPMS to generate an alert.
As a result, there is a need in the art for a leak detection system that determines with precision if an air pressure leak in tire is present, and when to issue an alert.
According to an aspect of an exemplary embodiment of the invention, a modular tire pressure leak detection system is provided. The system includes a tire that supports a vehicle and a sensor unit mounted on the tire. The sensor unit detects real-time tire parameters inside the tire and transmits the parameters to a processor. A plurality of modules are in electronic communication with the processor. The plurality of modules include a pre-processing module that receives the parameters and applies a set of operations to generate pressure time series data. The plurality of modules also include a leak detection module that receives the pressure time series data and determines a leak rate of the tire. The plurality of modules further includes a post-processing module that receives the leak rate of the tire and analyzes the leak rate of the tire with determinations from a plurality of conditions. A leak alert is issued by the post-processing module based upon the analysis of the leak rate of the tire and the determinations from the plurality of conditions.
The invention will be described by way of example and with reference to the accompanying drawings, in which:
Similar numerals refer to similar parts throughout the drawings.
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A valve stem 26 is in fluid communication with the cavity 24 and controls air flow into the cavity, as known to those skilled in the art. A sensor unit 30 is mounted on each tire 12 and includes one or more sensors for detecting certain real-time tire parameters inside the tire, such as tire pressure 36 (
Each TPMS sensor 30 preferably also includes electronic memory capacity for storing identification (ID) information for each tire 12, known as tire ID information. The tire ID information may include a position 42 of the tire 12 on the vehicle 14, tire type, tire construction, and the like. Alternatively, tire ID information may be included in another sensor unit, or in a separate tire ID storage medium, such as a tire ID tag (not shown). With additional reference to
The processor 34 may be mounted on the vehicle 14 as shown in
Aspects of the modular tire pressure leak detection system 10 preferably are executed on the processor 34 or on another processor that is accessible through the vehicle CAN bus, which enables input of data from the TMPS sensor 30, as well as input of data from other sensors that are in electronic communication with the CAN bus. In this manner, the modular tire pressure leak detection system 10 enables direct measurement of tire pressure 36 with the TPMS sensor 30, which preferably is transmitted to the processor 34.
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The input data 52 further preferably includes a pressure threshold 62. The pressure threshold 62 may include a placard pressure 138, which is the tire inflation pressure value denoted by a vehicle manufacturer and is typically included on a placard mounted on the vehicle 14 in a location that is visible to a user. The pressure threshold 62 may be stored in an electronic memory 64 that is in electronic communication with the processor 34 or which may be included in the tire ID information. The input data 52 preferably also includes a temperature threshold 66 that is stored in the electronic memory 64. The input data 52 preferably further includes a tire configuration 68 for the vehicle 14 that is stored in the electronic memory 64, and a TPMS sensor type 70 that is stored in the electronic memory or which may be available from the TPMS sensor 30.
The modular tire pressure leak detection system 10 includes three (3) modules that are stored on or are in electronic communication with the processor 34, including a pre-processing module 72, a leak detection module 74, and a post-processing module 76. The pre-processing module 72 receives the input data 52 and applies a set of configurable operations 80 to isolate the most recent trend in measured pressure 36 and generate pressure time series data 78.
The operations 80 may include a low pressure dropper 82, which drops measured pressure values 36 when the sensor 30 is removed from or not mounted in the tire 12. The operations 80 may also include a spike dropper 84, which removes sudden spikes 86 (
The operations 80 may include a flatline dropper 144, which detects and filters out a flatline in the input data 52. Because a flatline in data typically corresponds to a malfunction of a sensor, the flatline dropper 144 enables the system 10 to refrain from employing input data 52 from a malfunctioning sensor. The operations 80 may also include a GPS annotator 100, which employs data from the GPS 58 to extract values of measured pressure 36 when the speed of the vehicle 14 is excessive or insufficient, when the acceleration of the vehicle is excessive or insufficient, and/or when the amount of time the vehicle is in motion is insufficient. The GPS annotator 100 may also filter out pressure measurements 36 taken when the vehicle 14 travels outside of a predetermined geographic region, which is known in the art as geofencing, and/or when the vehicle travels at an excessive speed. The operations 80 may also include a resampler 102, which resamples measured data from the TPMS sensor 30 to a uniform cadence, thereby improving the accuracy of the data sets.
The operations 80 may include an inflation detector 104. With additional reference to
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Once the pre-processing module 72 has applied the configurable operations 80 to isolate the most recent trend in pressure 36, the pre-processing module outputs or generates pressure time series data 78 in which sources of changes in tire pressure, other than tire leaks, have been removed as much as possible.
The pressure time series data 78 input into the leak detection module 74. The leak detection module 74 preferably determines a leak rate 114 of the tire 12 by estimating the slope of the pressure time series data 78. Preferably, the leak detection module 74 includes a robust regressor that is employed as a timeseries model, which extracts the slope of the pressure time series data 78 as the leak rate 114. The leak rate 114 may include both a single-value point estimate of the slope of the pressure time series data 78 and a confidence range. The leak detection module 114 may also report a start and end of a period of time 90 for the input data 52.
The leak rate 114 is input into the post-processing module 76. The post-processing module 76 analyzes the leak rate 114 along with supplementary information, such as information about the state of the vehicle 14, to determine if an alert 132 should be issued. The post-processing module 76 includes a condition evaluator 116 that reviews multiple conditions through the use of sub-modules.
For example, the condition evaluator 116 may include a leak rate threshold sub-module 118 that compares the leak rate 114 to a predetermined low pressure threshold 134. If the leak rate 114 is significantly above the threshold 134, the leak rate threshold sub-module 118 may classify the leak rate as a fast leak. If the leak rate 114 is slightly above the threshold 134, the leak rate threshold sub-module 118 may classify the leak rate as a slow leak. If the leak rate 114 is at or below the threshold 134, the leak rate threshold sub-module 118 may classify the leak rate as no leak.
The condition evaluator 116 may also include a vehicle rate comparison sub-module 120, which compares the leak rate 114 to a median leak rate 136 in a group of tires 12. The median leak rate 136 preferably is a median value of the leak rates 114 for each tire 12 in a selected group of tires, which may be among all of the tires on a specific vehicle 14, among all of the tires on a specific axle of the vehicle, or among tires having the same position on separate vehicles in a fleet. The vehicle rate comparison sub-module 120 compiles the median leak rate 136 and suppresses the alert 132 if the leak rate 114 is similar to the median leak rate, as a pressure drop is likely due to driving or temperature conditions rather than a leak.
The condition evaluator 116 may include a placard pressure comparison sub-module 122. As described above, the placard pressure 138 is the tire inflation pressure value denoted by a vehicle manufacturer, which is typically included on a placard mounted on the vehicle 14 in a location that is visible to a user. Because the placard pressure 138 may be lower than the low pressure threshold 134, the placard pressure comparison sub-module 122 compares the measured pressure 36 for the tire 12 to the placard pressure and suppresses the alert 132 if the measured pressure is similar to the placard pressure.
The condition evaluator 116 may also include a robustness check sub-module 124. The robustness check sub-module 124 reviews the measured pressure data 36 to determine whether the leak rate 114 determined by the leak detection module 74 module may be disproportionately influenced by a small number of individual observations that sit outside the main trend, which may be referred to as outliers 140. When the outliers 140 exceed a predetermined amount or threshold, the robustness check sub-module 124 suppresses the alert 132.
The condition evaluator 116 may include a vehicle motion context sub-module 126. The vehicle motion context sub-module 126 checks a motion history 142 of the vehicle 14 to determine if the leak rate 114 is consistent with the vehicle motion history. For example, if the motion history 142 indicates typical movement of the vehicle 14, an alert 132 may not be suppressed. Alternatively, if there is a sudden change in the leak rate 114 for a vehicle 14 that has been stationary for a long period of time, the leak may be inconsistent with the motion history 142 of the vehicle, and the vehicle motion context sub-module 126 suppresses the alert 132.
Determinations 128 from the sub-modules of the condition evaluator 116 are input into a postprocessor 130 of the post-processing module 76. The postprocessor 130 compares the determinations 128 from each sub-module 118, 120, 122, 124, and 126 to determine if the alert 132 should be issued. For example, if the leak rate threshold sub-module 118 classifies the leak rate 114 as a fast leak or a slow leak, one determination 128 is to issue a corresponding fast or slow leak alert 132. However, if the leak rate 114 is similar to the median leak rate 136, a determination 128 from the vehicle rate comparison sub-module 120 may be to suppress the alert 132.
In addition, if the measured pressure 36 for the tire 12 is similar to the placard pressure 138, a determination 128 from the placard pressure comparison sub-module 122 may be to suppress the alert 132. Moreover, if the outliers 140 exceed a predetermined amount or threshold, a determination 128 from the robustness check sub-module 124 may be to suppress the alert 132. Also, if the leak rate 114 is inconsistent with the motion history 142 of the vehicle 14, a determination 128 from the vehicle motion context sub-module 126 may be to suppress the alert 132.
Once the postprocessor 130 compares the determinations 128 and finds that an alert should not be suppressed, a fast or slow leak alert 132 that corresponds to the leak rate 114 is issued by the post-processing module 76. Returning to
In this manner, the modular tire pressure leak detection system 10 of the present invention employs the pre-processing module 72, the leak detection module 74, and the post-processing module 76 to determine when a leak of pneumatic pressure from a tire 12 occurs and when to issue an alert 132 regarding the leak.
The present invention also includes a method of detecting a tire pressure leak. The method includes steps in accordance with the description that is presented above and shown in
It is to be understood that the structure of the above-described modular tire pressure leak detection system 10 may be altered or rearranged, or components or steps known to those skilled in the art omitted or added, without affecting the overall concept or operation of the invention. For example, the system 10 has been described with reference to valve stem mounted TPMS sensors, but finds application in other types of TPMS sensors that are known to those skilled in the art. In addition, the system 10 may be applied to the detection of a pressure leak in each tire 12 mounted on one vehicle 14, or to tires that are mounted on multiple vehicles in a fleet.
The invention has been described with reference to a preferred embodiment. Potential modifications and alterations will occur to others upon a reading and understanding of this description. It is to be understood that all such modifications and alterations are included in the scope of the invention as set forth in the appended claims, or the equivalents thereof.
Number | Date | Country | |
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63377736 | Sep 2022 | US |