Reverse deflection load estimation system for tires

Abstract

A reverse deflection load estimation system for a tire is provided. The tire includes a pair of sidewalls extending to a circumferential tread and supporting a vehicle, and the vehicle includes a control area network bus. In the system, a sensor is mounted to the tire and measures a parameter of the tire. A reverse deflection of the tire is determined from the measured parameter, and a linear vehicle speed signal is received over the control area network bus. A processor is in electronic communication with the sensor and in electronic communication with the control area network bus. A load estimation module is in electronic communication with the processor, receives the linear vehicle speed signal and the reverse deflection of the tire, and determines a load on the tire.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to tire monitoring systems. More particularly, the present invention relates to systems that collect tire parameter data. The present invention relates to systems for estimating tire load that employ inverse deflection of a tire to indirectly estimate tire load in an accurate and reliable manner. BACKGROUND

[0002] Load on each tire of a vehicle plays an important role in vehicle factors such as handling, safety, reliability, and performance. Measurement or estimation of load on a tire during operation of a vehicle is often used by vehicle control systems such as braking, traction, stability, and suspension systems. For example, information about individual tire loads enables accurate estimation of load distribution between front and rear axles of a vehicle, which can then be used to optimize a braking control system. Alternatively, knowledge of tire loads and thus vehicle mass can enable more accurate estimation of remaining range of an electric vehicle. As such, it is desirable to estimate load on a tire in an accurate and reliable manner for input or use in such systems.

[0003] Prior art methods involve attempting to directly measure tire load with load or strain sensors. Such direct measurement techniques have drawbacks, particularly during the life of a tire, due to difficulty in achieving sensors with construction and placement on a tire that are capable of accurately consistent measurement of tire load.

[0004] Other prior art methods have been developed that involve estimation of tire load with fixed parameters. Such prior art methods have drawbacks due to the fact that techniques that rely on fixed parameters often result in less good prediction or estimation, which in turn reduces accuracy and / or reliability of tire load prediction.

[0005] Accordingly, there is a need in the art for systems and methods that accurately and reliably estimate tire load. SUMMARY

[0006] According to an aspect of an exemplary embodiment of the present invention, a system for inverse deflection load estimation for a tire is provided. The tire includes a pair of sidewalls extending to a circumferential tread and supporting a vehicle, and the vehicle includes a control area network bus. The system includes a sensor mounted to the tire and measuring a parameter of the tire. An inverse deflection of the tire is determined from the measured parameter, and a linear vehicle speed signal is received over the control area network bus. A processor is in electronic communication with the sensor and in electronic communication with the control area network bus. A load estimation module is in electronic communication with the processor, receives the linear vehicle speed signal and the inverse deflection of the tire, and determines a load on the tire.

[0007] According to another aspect of the exemplary embodiments of this application, there is provided a method for estimating tire load using inverse deflection. The tire includes a pair of sidewalls extending to a circumferential tread and supporting a vehicle. In the method, a sensor is mounted to the tire and a parameter of the tire is measured with the sensor. An inverse deflection of the tire is determined from the measured parameter and a linear vehicle speed signal is received over a control area network bus of the vehicle. A processor is provided in electronic communication with the sensor and in electronic communication with the control area network bus. The linear vehicle speed signal and the inverse deflection of the tire are received in a load estimation module in electronic communication with the processor. A load on the tire is determined with the load estimation module.

[0008] The present application provides the following technical solutions:

[0009] 1. A system for inverse deflection load estimation for a tire, the tire including a pair of sidewalls extending to a circumferential tread and supporting a vehicle, the vehicle including a control area network bus, the system comprising:

[0010] a sensor mounted to the tire, the sensor measuring a parameter of the tire;

[0011] an inverse deflection of the tire determined from the measured parameter;

[0012] a linear vehicle speed signal received over the control area network bus;

[0013] a processor in electronic communication with the sensor and in electronic communication with the control area network bus; and

[0014] a load estimation module in electronic communication with the processor, the load estimation module receiving the linear vehicle speed signal and the inverse deflection of the tire and determining a load on the tire.

[0015] 2. The system for inverse deflection load estimation for a tire according to solution 1, wherein the measured parameter includes a radial acceleration of the tire.

[0016] 3. The system for inverse deflection load estimation for a tire according to solution 2, wherein the inverse deflection is determined from an intermediate region between radial acceleration minima.

[0017] 4. The system for inverse deflection load estimation for a tire according to solution 3, wherein the inverse deflection is determined from an average of the radial acceleration in the intermediate region.

[0018] 5. The system for inverse deflection load estimation for a tire according to solution 2, wherein the load estimation module receives a spin time of the tire measured by the sensor.

[0019] 6. The reverse deflection load estimation system for a tire according to Scheme 2, wherein the load estimation module receives an inflation pressure of the tire and a temperature of the tire measured by the sensor.

[0020] 7. The reverse deflection load estimation system for a tire according to Scheme 2, wherein the load estimation module receives at least one of a tire identification information and an identification code of the sensor.

[0021] 8. The reverse deflection load estimation system for a tire according to Scheme 1, wherein the load estimation module receives a linear vehicle speed from the control area network bus.

[0022] 9. The reverse deflection load estimation system for a tire according to Scheme 1, wherein the load estimation module employs a regression model.

[0023] 10. The reverse deflection load estimation system for a tire according to Scheme 9, wherein the regression model comprises a linear regression model.

[0024] 11. The reverse deflection load estimation system for a tire according to Scheme 1, further comprising a vehicle control system in electronic communication with the processor, the vehicle control system receiving the determined load on the tire.

[0025] 12. The reverse deflection load estimation system for a tire according to Scheme 1, wherein the processor comprises at least one of an on-board processor and a processor in a cloud-based computing system.

[0026] 13. A method for estimating a load of a tire, the tire comprising a pair of sidewalls extending to a circumferential tread and supporting a vehicle, the method comprising the steps of:

[0027] mounting a sensor to the tire;

[0028] measuring a parameter of the tire with the sensor;

[0029] determining a reverse deflection of the tire from the measured parameter;

[0030] receiving a linear vehicle speed signal through a control area network bus of the vehicle;

[0031] providing a processor in electronic communication with the sensor and in electronic communication with the control area network bus;

[0032] receiving the linear vehicle speed signal and the reverse deflection of the tire in a load estimation module in electronic communication with the processor; and

[0033] determining a load on the tire with the load estimation module.

[0034] 14. The method for estimating a load of a tire according to Scheme 13, wherein the step of measuring a parameter of the tire comprises measuring a radial acceleration of the tire.

[0035] 15. The method for estimating a load of a tire according to Scheme 14, wherein the step of determining a reverse deflection of the tire comprises determining the reverse deflection from an intermediate region between radial acceleration minima.

[0036] 16. The method for estimating a load of a tire according to Scheme 15, wherein the step of determining a reverse deflection of the tire comprises determining the reverse deflection from an average of the radial acceleration in the intermediate region.

[0037] 17. The method for estimating a load of a tire according to Scheme 14, further comprising the step of receiving in the load estimation module at least one of a spin time of the tire measured by the sensor and an inflation pressure of the tire and a temperature of the tire measured by the sensor.

[0038] 18. The method for estimating a load of a tire according to Scheme 14, further comprising the step of receiving in the load estimation module at least one of tire identification information and an identification code of the sensor.

[0039] 19. The method for estimating a load of a tire according to Scheme 13, wherein the step of determining a load on the tire with the load estimation module comprises employing a linear regression model.

[0040] 20. The method for estimating a load of a tire according to Scheme 13, further comprising the step of transmitting the determined load on the tire to a vehicle control system in electronic communication with the processor. BRIEF DESCRIPTION OF DRAWINGS

[0041] The present application will be described by way of example, and with reference to the accompanying drawings, in which:

[0042] Figure 1 is a perspective view of a vehicle and sensor-equipped tire employing an exemplary embodiment of the reverse deflection tire load estimation system of the present application;

[0043] Figure 2 is a schematic illustration showing Figure 1 a reverse deflection of the tire shown;

[0044] Figure 3 is a graphical illustration of a radial acceleration of the tire shown; Figure 2 ​

[0045] Figure 4 is a schematic illustration of an exemplary embodiment of the present invention reverse deflection tire load estimation system; and

[0046] Figure 5 is a representation of data transfer to a cloud-based server and to a user device Figure 1 is a schematic illustration of a vehicle shown.

[0047] Like reference numerals refer to like parts throughout the several views of the drawings.

[0048] Definitions

[0049] "axial" and "axially" mean a line or direction parallel to the axis of rotation of the tire.

[0050] "CAN bus" is an abbreviation for Controller Area Network, which is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within vehicles, without a host computer. CAN bus is a message-based protocol designed specifically for vehicle applications.

[0051] "circumferential" means a line or direction parallel to the circumference of the tire.

[0052] "equatorial center plane" means a plane perpendicular to the axis of rotation of the tire and passing through the center of the tread.

[0053] "footprint" means the contact patch or contact area made by the tire tread with a flat surface such as the ground when the tire is rotating or rolling.

[0054] "inside face" means the tire side closest to the vehicle when the tire is mounted on a wheel and the wheel is mounted on a vehicle.

[0055] "lateral" means an axial direction.

[0056] "lateral edge" means a line tangent to the axially outermost tread contact patch or footprint, measured under standard load and tire inflation conditions, these lines being parallel to the equatorial center plane.

[0057] "net contact area" means the total area of the ground contacting tread elements between the lateral edges around the entire circumference of the tread divided by the total area of the entire tread between the lateral edges.

[0058] "outside face" means the tire side farthest from the vehicle when the tire is mounted on a wheel and the wheel is mounted on a vehicle.

[0059] "radial" and "radially" mean directions radially toward or away from the axis of rotation of the tire.

[0060] "Tread element" or "traction element" refers to a rib or block element defined by a shape having adjacent grooves. Detailed Implementation

[0061] exist Figures 1 to 5 Exemplary embodiments of the reverse deflection tire load estimation system of the present invention are illustrated in 10 places. System 10 and the accompanying method attempt to overcome the aforementioned challenges posed by prior art systems and methods that seek to measure tire load through direct sensor measurements. Therefore, the systems and methods of this subject are referred to herein as “indirect” load estimation systems and methods.

[0062] Special Reference Figure 1 System 10 estimates the load on each tire 12 supporting vehicle 14 based on the reverse deflection of the tires, as will be described in more detail below. Although vehicle 14 is depicted as a passenger car, the invention is not so limited. The principles of the invention apply to situations where a vehicle can be constructed by a vehicle with a different configuration than a passenger car. Figure 1 Other vehicle types, such as commercial trucks, are shown with more or fewer tires supporting their components. For convenience, except as specifically described below, an analysis will be performed on a single tire 12; it should be understood that a similar analysis is envisioned for each tire supporting the vehicle 14.

[0063] Tire 12 has a conventional construction and is mounted on a corresponding wheel 16. Tire 12 includes a pair of sidewalls 18 extending to a circumferential tread 20 that contacts the ground during vehicle operation. Tire 12 is preferably equipped with a sensor 26 mounted to the tire for the purpose of detecting certain real-time tire parameters. For example, sensor 26 may be a commercially available tire pressure monitoring system (TPMS) module or sensor that can be attached to the inner liner 22 of tire 12 by a suitable method such as adhesive. Sensor 26 preferably includes a pressure sensor to sense the inflation pressure 58 within the cavity 24 of tire 12. Figure 4 The sensor 26 also includes a temperature sensor to sense the temperature 60 of the tire and / or the temperature in the cavity. The sensor 26 preferably also senses the rotation time of the tire 12 and also senses the reverse deflection of the tire, as will be described in more detail below.

[0064] Sensor 26 preferably also includes a processor and a memory for storing tire identification (tire ID) information 66 of tire 12. Figure 4). For example, the tire ID can include manufacturing information for the tire 12, including: the tire's position on the vehicle 14; the tire model; size information, such as rim size, width, and outside diameter; manufacturing location; manufacturing date; a tread crown code, which includes or is related to a compound identification; and a mold code, which includes or is related to a tread pattern identification. The tire ID can also include repair history or other information to identify specific characteristics and parameters of the tire 12. The sensor 26 preferably also includes an antenna for transmitting measured parameters and tire ID data to a remote processor 28, which can be a processor integrated into the vehicle CAN bus 30, for analysis.

[0065] Aspects of the tire load estimation system 10 are preferably executed on a processor 28 accessible through the vehicle CAN bus 30 ( Figure 4 ). The processor 28 can be an on-board vehicle processor, or can be a remote internet or cloud-based processor ( Figure 5 ). The use of such a processor 28 and accompanying methods enables data from the tire-based sensors 26 and from certain vehicle-based sensors, as well as data from databases that can be stored in suitable storage media in electronic communication with the processor, to be input into the system 10. The CAN bus 30 enables the tire load estimation system 10 to interact with other electronic components and systems of the vehicle 14.

[0066] Turning Figure 2 As the tire 12 rotates or rolls on a surface 32, such as the ground, the tread 20 creates a contact patch 34 with the surface, also referred to as a footprint. In the contact patch 34, the tire 12 experiences deflection 36. As a result of the deflection 36, the surface 38 of the tire 12 outside of the contact patch 34 experiences counter-deflection 40. More specifically, the counter-deflection 40 is an increase in the radius of the tire 12 away from the contact patch 34, and is proportional to the deflection 36 that occurs in the contact patch.

[0067] With additional reference to Figure 3When the tire 12 is rotating, it has a radial acceleration 42. The radial acceleration 42 of the tire 12 can be plotted over time 44, and when the vehicle 14 is traveling at a constant speed, the mid region 46 between the minimums 48 of the radial acceleration corresponds to the inverse deflection 40 of the tire. An average 50 of the mid region 46 of the radial acceleration can be determined, which corresponds to a specific value of the inverse deflection 40, as will be described in greater detail below. In this example, the average 50 of the mid region 46 of the radial acceleration is approximately 62 g, where g is the equivalent of gravity. The average 50 of the radial acceleration at a speed of 50 kilometers per hour (kph) under a load of 4000 Newtons (N) corresponds to an inverse deflection 40 or inverse deflection radius of approximately 0.317 meters (M) of the tire 12.

[0068] The sensor 26 Figure 1 may include a radial accelerometer to sense the radial acceleration 42 of the tire 12, from which the inverse deflection 40 can be determined. The determination of the inverse deflection 40 of the tire 12 from the radial acceleration 42 can be performed within the sensor 26, or in the processor 28 when the processor is in electronic communication with the sensor. It should be understood that other measuring devices that measure the deformation of the tire 12 can be used to determine the inverse deflection 40.

[0069] Turning Figure 4 The inverse deflection tire load estimation system 10 includes a load estimation module 52 that is stored on or in electronic communication with the processor 28. The load estimation module 52 receives the linear vehicle speed 54 and tire data 56 from the sensor 26 through the vehicle CAN bus 30. The tire data 56 preferably includes the radial acceleration 42 of the tire 12 from which the inverse deflection 40 can be determined, or another tire parameter that enables the determination of the inverse deflection. The tire data 56 preferably also includes the spin-up time 62 of the tire 12 to enable the determination of the mid region 46 of the radial acceleration and thus the inverse deflection 40. The tire data 56 preferably also includes the tire inflation pressure 58, the tire temperature 60, the tire ID information 66, and / or the identification code 64 of the sensor 26.

[0070] The load estimation module 52 preferably includes a regression model, which can be a linear regression model or a non-linear regression model, to estimate the tire load 68 from the linear vehicle speed 54 and the tire data 56, which includes the inverse deflection 40. Preferably, a linear regression model is employed. However, if higher accuracy in the load estimation model 52 is desired, a non-linear regression model can be employed.

[0071] As an example, the tire 12 includes a vertical stiffness Kf, which is a proportional constant between the deflection 36 (also identified as f) and the normal load F on the tire:

[0072] F = Kf * f

[0073] The inverse deflection stiffness Kλ of the tire 12 is a proportional constant between the inverse deflection 40 (also identified as λ) and the normal load F:

[0074] F = Kλ*λ

[0075] The inverse deflection stiffness Kλ is proportional to the vertical stiffness of the tire 12. The inverse deflection stiffness Kλ can be described as a regression model with a first variable identified as m, which is proportional to the inflation pressure 58 (also identified as p), and a second variable identified as b, which represents structural characteristics of the tire 12 identified from the tire ID information 66, such as the sidewall shear stiffness and dimensions of the tire:

[0076] Kλ = m*p + b

[0077] The inverse deflection 40 (λ) can be determined by subtracting the unloaded tire radius r0 from the inverse deflection radius r of the tire 12:

[0078] λ = r - r0

[0079] The radius r is equal to the square of the linear vehicle speed 54 (also identified as v) divided by the radial acceleration as obtained from the measured radial acceleration 42 (also identified as a):

[0080]

[0081] The inverse deflection 40 (λ) is thus determined as:

[0082]

[0083] From this, the tire load 68 (also identified as F) is determined:

[0084]

[0085] which can also be expressed generally as F = f(p, r0, v, a).

[0086] In this way, the load estimation module 52 estimates the tire load 68 from the linear vehicle speed 54 and the tire data 56. The estimated load 68 on the tire 12 can be communicated from the inverse deflection tire load estimation system 10 over the vehicle CAN bus system 30 for use by vehicle control systems such as braking, traction, stability, and / or suspension systems.

[0087] Turning Figure 5The inverse deflection tire load estimation system 10 preferably executes on a processor 28 accessible through the vehicle CAN bus 30, which can be installed on the vehicle 14, or it can be in an internet or cloud-based computing system 70, referred to herein as a cloud-based computing system. The inverse deflection tire load estimation system 10 preferably employs wireless data transmission 72 between the vehicle 14 and the cloud-based computing system 70. The inverse deflection tire load estimation system 10 can also employ wireless data transmission 74 between the cloud-based computing system 70 and a display device 76 accessible to a user of the vehicle 14, such as a smartphone, or to a fleet manager. Alternatively, the system 10 can also employ wireless data transmission 78 between the vehicle CAN bus 30 and the display device 76.

[0088] Thus, the inverse deflection tire load estimation system 10 of the present invention utilizes the inverse deflection 40 of the tire 12 to indirectly estimate the tire load 68 in an accurate and reliable manner. The inverse deflection tire load estimation system 10 utilizes the linear vehicle velocity 54 and the tire data 56 for real-time estimation of the tire load 68.

[0089] The present invention also includes a method for estimating the load of a tire 12. The method includes the steps according to the description above and shown in Figures 1 to 5

[0090] It should be understood that the structure and method of the inverse deflection tire load estimation system described above can be changed or rearranged, or components or steps can be omitted or added, without affecting the overall concept or operation of the present invention, as would be known to those skilled in the art.

[0091] The present invention has been described with reference to the preferred embodiments. Persons of ordinary skill in the art will readily conceive of potential variations and modifications upon reading and understanding the above description. It is understood that all such variations and modifications are included within the scope of the present invention or the equivalent thereof as set forth in the appended claims.​

Claims

1. A reverse deflection load estimation system for a tire, the tire comprising a pair of sidewalls extending to a circumferential tread and supporting a vehicle, the vehicle comprising a control area network bus, the system comprising: a sensor mounted to the tire, the sensor measuring a parameter of the tire; a reverse deflection of the tire determined from the measured parameter; a linear vehicle velocity signal received over the control area network bus; a processor in electronic communication with the sensor and in electronic communication with the control area network bus; and a load estimation module in electronic communication with the processor, the load estimation module receiving the linear vehicle velocity signal and the reverse deflection of the tire and determining a load on the tire; wherein the reverse deflection is determined from an intermediate region between radial acceleration minima of the tire. The measured parameter comprises a radial acceleration of the tire.

2. The reverse deflection load estimation system for tires according to claim 1, wherein, The reverse deflection is determined from an average of the radial acceleration in the intermediate region.

3. The reverse deflection load estimation system for tires of claim 1, wherein, The load estimation module receives a spin time of the tire measured by the sensor.

4. The reverse deflection load estimation system for tires of claim 2, wherein, The load estimation module receives an inflation pressure of the tire measured by the sensor and a temperature of the tire.

5. The reverse deflection load estimation system for a tire of claim 2, wherein, The load estimation module receives at least one of a tire identification information and an identification code of the sensor.

6. The reverse deflection load estimation system for a tire of claim 2, wherein, The load estimation module receives a linear vehicle velocity from the control area network bus.

7. The reverse deflection load estimation system for tires of claim 1, wherein, The load estimation module employs a regression model.

8. The reverse deflection load estimation system for tires of claim 1, wherein, The regression model comprises a linear regression model.

9. The reverse deflection load estimation system for a tire of claim 8, wherein, 10. The reverse deflection load estimation system for a tire of claim 1, further comprising a vehicle control system in electronic communication with the processor, the vehicle control system receiving the determined load on the tire. The processor comprises at least one of an on-board processor and a processor of a cloud-based computing system.

11. The reverse deflection load estimation system for tires of claim 1, wherein, 12. A method for estimating a load of a tire, the tire comprising a pair of sidewalls extending to a circumferential tread and supporting a vehicle, the method comprising the steps of: mounting a sensor to the tire; measuring a parameter of the tire with the sensor; determining a reverse deflection of the tire from the measured parameter; receiving a linear vehicle velocity signal over a control area network bus of the vehicle; providing a processor in electronic communication with the sensor and in electronic communication with the control area network bus; receiving the linear vehicle velocity signal and the reverse deflection of the tire in a load estimation module in electronic communication with the processor; and determining a load on the tire with the load estimation module; wherein the step of determining a reverse deflection of the tire comprises determining the reverse deflection from an intermediate region between radial acceleration minima of the tire. The step of measuring a parameter of the tire comprises measuring a radial acceleration of the tire. The step of determining a reverse deflection of the tire comprises determining the reverse deflection from an average of the radial acceleration in the intermediate region.

13. The method for estimating the load of a tire according to claim 12, wherein, ​ 14. The method for estimating the load of a tire according to claim 12, wherein, ​ 15. The method for estimating the load of a tire of claim 13, further comprising the step of receiving in the load estimation module at least one of a spin time of the tire measured by the sensor and an inflation pressure of the tire and a temperature of the tire measured by the sensor.

16. The method for estimating the load of a tire of claim 13, further comprising the step of receiving in the load estimation module at least one of tire identification information and an identification code of the sensor.

17. The method for estimating the load of a tire according to claim 12, wherein, The step of determining the load on the tire with the load estimation module comprises employing a linear regression model.

18. The method for estimating the load of a tire of claim 12, further comprising the step of transmitting the determined load on the tire to a vehicle control system in electronic communication with the processor.

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