Wheel based sensor assembly

A wheel and sensor assembly includes a U-shaped bracket assembly mounting to and moving with a wheel assembly. One or more sensor device(s) such as camber angle and slip angle sensors mount to the bracket assembly for operatively measuring one or more wheel assembly parameter(s) during vehicle use. The bracket assembly mounts to the wheel assembly and turns therewith. The bracket assembly positions the sensor device(s) in operative optimal proximity to the road surface during vehicle use under actual operating conditions.

FIELD OF THE INVENTION

The invention relates generally to sensor assemblies for measuring tire operational parameters and, more specifically, to sensor assemblies for generating tire-specific measurements data during vehicle use at high speed.

BACKGROUND OF THE INVENTION

In the operation of passenger cars and racecars, it is desirable to measure and test tires, wherever practical, in real time and under actual road conditions. For passenger cars, the venues of interest may be carefully selected road conditions while, for racecars, it is the operating conditions on a particular racetrack. The purpose for observing, testing, and measuring tire operating parameters in real time and under actual road conditions is to provide real world feedback on tire performance and to allow for the creation of more accurate tire durability test procedures and methods.

The specific tire parameters to be measured and evaluated may include tire slip and camber angles or tire deflection. Heretofore, the ability of the industry to test, measure, and evaluate tires for such tire parameters while the tire is at high speeds has not been available. Consequently, the tire testing procedures and methods utilized within the industry have been created without benefit of real time measurement of such tires under actual operating conditions.

SUMMARY OF THE INVENTION

An aspect of the invention embodies a wheel-based sensor assembly. The assembly includes a rotational wheel assembly, the wheel assembly including a wheel rim and a tire mounted thereto. One or more sensor device(s) are provided for operatively measuring one or more wheel assembly parameter(s) while the wheel assembly rotates during vehicle use. A bracket assembly mounts to the vehicle and operatively positions the sensor device(s).

In another aspect, the bracket assembly includes a first bracket arm segment extending at least partially along an outer sidewall of the tire in a radial direction and a sensor device adjustably repositionable along the arm segment. The bracket assembly may further include a second bracket segment extending at least partially along a tread region of the tire in an axial direction, preferably to a side of the tire opposite a normatively forward vehicular direction of travel. A secondary sensor device may be mounted to the second bracket arm segment adjacent the tread region of the tire.

In another aspect, the first and second bracket arm segments are relatively disposed at a ninety degree angle and include a channel along a tire-facing bracket side to operatively receive and route electrical wiring along the bracket assembly. The bracket assembly may be constructed in a U-shaped configuration connecting the second bracket member segment to an inner side of the wheel assembly by a third bracket arm segment. The sensor units may include a slip angle sensor mounted to the first bracket arm segment and a camber angle sensor mounted to the second bracket arm segment.

DEFINITIONS

“Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100% for expression as a percentage.

“Asymmetric tread” means a tread that has a tread pattern not symmetrical about the center plane or equatorial plane EP of the tire.

“Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire.

“Camber angle” means the angular tilt of the front wheels of a vehicle. Outwards at the top from perpendicular is positive camber; inwards at the top is negative camber.

“Equatorial Centerplane (CP)” means the plane perpendicular to the tire's axis of rotation and passing through the center of the tread.

“Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure.

“Groove” means an elongated void area in a tread that may extend circumferentially or laterally about the tread in a straight, curved, or zigzag manner. Circumferentially and laterally extending grooves sometimes have common portions. The “groove width” is equal to tread surface area occupied by a groove or groove portion, the width of which is in question, divided by the length of such groove or groove portion; thus, the groove width is its average width over its length. Grooves may be of varying depths in a tire. The depth of a groove may vary around the circumference of the tread, or the depth of one groove may be constant but vary from the depth of another groove in the tire. If such narrow or wide grooves are substantially reduced depth as compared to wide circumferential grooves which the interconnect, they are regarded as forming “tie bars” tending to maintain a rib-like character in tread region involved.

“Inboard side” means the side of the tire nearest the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle.

“Lateral” means an axial direction.

“Lateral edges” means a line tangent to the axially outermost tread contact patch or footprint as measured under normal load and tire inflation, the lines being parallel to the equatorial centerplane.

“Net contact area” means the total area of ground contacting tread elements between the lateral edges around the entire circumference of the tread divided by the gross area of the entire tread between the lateral edges.

“Non-directional tread” means a tread that has no preferred direction of forward travel and is not required to be positioned on a vehicle in a specific wheel position or positions to ensure that the tread pattern is aligned with the preferred direction of travel. Conversely, a directional tread pattern has a preferred direction of travel requiring specific wheel positioning.

“Outboard side” means the side of the tire farthest away from the vehicle when the tire is mounted on a wheel and the wheel is mounted on the vehicle.

“Radial” and “radially” means directions radially toward or away from the axis of rotation of the tire.

“Rib” means a circumferentially extending strip of rubber on the tread which is defined by at least one circumferential groove and either a second such groove or a lateral edge, the strip being laterally undivided by full-depth grooves.

“Sipe” means small slots molded into the tread elements of the tire that subdivide the tread surface and improve traction, sipes are generally narrow in width and close in the tires footprint as opposed to grooves that remain open in the tire's footprint.

“Slip angle” means the angle of deviation between the plane of rotation and the direction of travel of a tire.

“Tread element” or “traction element” means a rib or a block element defined by having a shape adjacent grooves.

“Tread Arc Width” means the arc length of the tread as measured between the lateral edges of the tread.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1-4, the subject wheel and sensor assembly10is shown to include a wheel assembly12in which a tire16is mounted to a rim14in conventional fashion. The assembly10is a component of a vehicle (not shown) such as a passenger car or truck. However, as will be explained, the invention has particular utility in conjunction with measuring tire set-up and performance on a race car. The tire16mounted to rim14is, accordingly, intended to be of a general depiction without regard to vehicle type or use. The tire16is of conventional construction having a sidewall18extending to a tread region20.

The assembly10further includes a bracket assembly22mounted as shown to the wheel assembly12. The bracket assembly22generally is of U-shape defined by a first bracket arm segment24, a second bracket arm segment26forming the bight of the assembly22, and a third bracket arm segment26. Each of the segments24,28has a connector coupling at a remote end, the coupling of segment24being in the form of a sized C-clamp30. The segments forming bracket assembly22are formed from suitably sturdy material such as steel. The first segment24has an elongate narrow body32through which a longitudinal, medially located, slot33extends. Extending into an upper edge of the body32is a channel34. The channel34extends the length of the body32and is sized to admit electrical wiring (not shown) used for power transmission to sensor units mounted to the bracket assembly22as well as data transmission from the sensor units as will be explained.

The end segment36of the first segment24opposite the C-clamp20end angles inwardly to a remote flange38through which an assembly aperture40extends. The second segment26of the bracket assembly22attaches to the flange38. The second segment26is of elongate construction, generally L-shaped in transverse sectional configuration. The bracket segment26is formed by a horizontal elongate side42intersecting at a right angle along a longitudinal edge with a vertical side44. The sides42,44extend between opposite triangular end flanges46through which assembly apertures48pass. Suitable assembly hardware is provided to affix the segment26to the first and third segments24,28such as coupling screws and nuts49A, B respectively. Spaced apart apertures50extend through the side44and serve as mounting locations for sensor device(s) attaching to the side44as will be explained. Assembly hardware such as pins51are provided for the attachment of sensor units to the side44.

A mounting plate52is included within the bracket assembly22and attaches to the body32of the arm segment24. The plate52includes a vertical coupling tongue projection53having spaced apart elongate mounting slots54extending therethrough. A rectangular plate body56has appropriately located mounting through apertures58sized for attachment hardware such as pins60. A sensor device62mounts to the plate body56by means of extension of the pins60through the apertures58. The sensor device62is preferably but not necessarily of the type used to measure slip angle of a tire, such as the commercial unit sold by Corrsys-Datron Co. The slip angle sensor device62mounts to the mounting plate52. The plate52attaches by set screws55extending through plate slots54and through the slot33along the arm body32. So attached, the plate52and slip angle sensor device62affixed thereto depend from the arm body32and are repositionable along the arm slot33into an optimal location relative to the ground surface for tire slip angle measurement.

A camber angle sensor device is assembled to include a pair of spaced apart laser units66,68that attach through the spaced apart apertures50in the second arm segment26. The sensor device66,68measures camber angle of the tire16and are of a commercially available type such as the product sold by Corrsys-Datron Co. The laser units66,68are provided with assembly holes70to facilitate attachment to the second arm segment26. The attachment of the slip angle sensor62and camber angle sensors66,68to respective arm segments is preferably effected after the arm segments24,26,28are mutually assembled into the U-shaped configuration shown inFIGS. 1-3. To attach the completed bracket assembly22with the sensor units62and66,68to the wheel assembly12, the U-shaped bracket assembly22is positioned in straddling relationship with the tire16. The ends of the segments24,28attach to components of the wheel assembly12on opposite respective sides of the tire16. In the assembled position, the arm segments24,28extend in a radial direction along opposite sidewalls18of the tire16and the arm segment26extends in an axial direction opposite the tread region20of the tire16. The spacing of the arm segments24,28from respective sidewalls18is preferably closely adjacent to position the slip angle sensor62as close as possible to the tire sidewall. The close relationship of the sensor62with the tire sidewall18serves to enhance the accuracy of the slip angle measurement as well as reduce the extent to which the sensor62protrudes from the tire. Minimizing the protrusion of the sensor62acts to minimize the potential for damaging contact between the sensor62and surrounding objects. The sensor62includes a downwardly directed laser element that measures the angle of the tire16relative to the ground surface during vehicle operation and thereby provides data for the calculation of the slip angle of the tire.

The location of the second arm segment26and the camber angle sensor66,68is as shown to be closely adjacent the tread region20of the tire16. Such proximity enhances the accuracy of the camber angle measurement. The mounting of the arm segment26is preferable to the side of the wheel assembly12opposite the direction of forward vehicle travel78in order to protect the arm segment26and sensor66,68from damaging contact with surrounding objects. The through passages60through the arm segment26provide air flow pathways from the rotating tire through the arm segment26, whereby reducing drag, reducing stresses on the segment26and sensor66,68, and reducing vibration in the bracket assembly. The sensor units66,68include downwardly directed laser elements that measure to the ground surface and the angular cant of the tire during vehicle operation, whereby providing data for the calculation of the camber angle of the tire.

While the subject bracket assembly22and sensor units mounted thereto can effect measurement from tires used in myriad vehicle applications, the assembly is particularly useful and effective in determining the wheel and tire set up in a race car in preparation for a race. The coupling C-clamp30of the assembly22may be affixed to the stator74of a load cell72within the wheel assembly12as shown. A load cell such as shown at72is commercially available from SDI Manufacturing. The opposite arm segment28of the bracket assembly22may attach to the brake assembly76on the opposite side of the wheel. So located and attached, the sensors62and66,68are located close to the tire16to generate accurate camber and slip angle data as well as to minimize the degree to which bracket and sensors protrude. Vehicles may be, in the course of normal operation, particularly in race cars, driven close to outside obstructions and other vehicles. The close proximity and location of the bracket and sensors of the invention to the tire minimizes the risk of contact with such outside influences. Location of the second arm segment and sensor behind the tire, on the opposite side of normatively forward direction of travel78, likewise protects the bracket and sensor assembly.

While the attach points of the bracket assembly to the wheel assembly12are preferably as shown, other means and locations of attachment of the bracket may be employed if desired. In addition, while slip angle and camber angle sensor units62and66,68are described above, other types of sensors may be deployed through utilization of the bracket assembly22and deployment scheme. For example, without intent to delimit the invention, a tire deflection detector or camera may be mounted to the bracket arm segments224,26,28and utilized to detect and measure the existence, location, and geometry of tire anomalies during vehicle use. A thermal detector may also be mounted to the bracket assembly22to detect the thermal properties of a tire during vehicle use. Power to and data communication from such devices may be wired along the channel34of the arm segment24. The bracket assembly and deployment scheme described above allows for the measurement of the tire16while in actual use on a road surface. Such real time evaluation under actual working conditions results in a more thorough and accurate evaluation than laboratory testing. The bracket and sensors measure the tire under actual working conditions to provide not only information on tire performance but also tire response and reaction to a specific track or roadway. For a racecar, for example, specifically correlating tire response and conditional parameters to a particular racetrack is extremely important to the racecar setup.

In addition, mounting the bracket assembly22and sensor units to a steer wheel assembly12allows for tire evaluation through turns since the bracket assembly22and sensor units will turn with the tire. Such capability effects a more thorough and accurate evaluation of the tire and roadway surface than could otherwise be made by the mounting of slip angle and camber angle sensors on the body of the vehicle adjacent to a tire. The subject bracket and sensor assembly turns with the wheel to which it is mounted and measure the slip angle directly as opposed vehicle based sensors that measure the slip angle base on the entire car chassis. Improved accuracy therefore is achieved by the invention assembly.

The channel34formed within the arm segment24extends the length of the body32and is sized to admit electrical wiring (not shown) used for power transmission to sensor units62and66,68as well as data transmission from the sensor units to a data storage or collection device. The electrical wiring is thus protected from interfering with the operation of the wheel assembly and from potential damage from contact with foreign objects.