Not Applicable.
The present invention is related generally to vehicle wheel end assemblies, and in particular, to a wheel end assembly which incorporate sensors for measuring wheel end characteristics which vary in response to drive torque applied to the wheel end assembly.
In many automotive vehicles of current manufacture the road wheels are coupled to the suspension system of the vehicle through conventional bearing assemblies commonly referred to as wheel ends. Conventional wheel ends, such as shown in
Some wheel ends 100 have speed sensors attached to their housings and target wheels carried by the associated rotating hubs. The speed sensors monitor the rotation of the target wheels coupled to the rotating hub 102—and hence the rotation of the attached road wheels—and thus provide signals reflecting angular velocity of the road wheels which may be utilized by various anti-lock braking systems (ABS) and traction control systems (TCS) onboard the vehicle.
To maintain even more control over vehicle performance, some vehicles have electronic dynamic or stability control systems (ECS) which operate to maintain vehicle stability. These systems may manage drive train power, braking, steering, and even suspension system components, and hence enhance vehicle safety and performance. These types of systems will function best when provided with reliable information associated with the loads at the so-called tire patches for a vehicle, that is, where the tires of the road wheels contact the road surface, and these loads are essentially loads transmitted through the wheel ends 100 for the vehicle. For example, maneuvering through a turn will create thrust loads at the wheel ends 100 and laterally directed forces at the tire patches, and these represent the most critical aspects of dynamic control.
The advancement from anti-lock brake system (ABS) and traction control systems (TCS) to electronic stability control systems (ECS) has required additional vehicle condition sensing capabilities. All of these systems can benefit from knowledge of the driving torque acting at each wheel of a vehicle.
Traditional systems for measuring drive torque applied to a vehicle wheel utilize sensors which are external to the wheel end antifriction bearing assembly. For example, some systems sense torque on an interconnecting drive shaft that leads into a constant velocity (CV) joint coupling the wheel end assembly 100 to a main drive shaft. Torque sensors in this location are subject to the harsh environmental conditions experienced by the vehicle, and require additional assembly steps to be carried out either during vehicle assembly or during the manufacture of the CV joint components.
Accordingly, it would be advantageous to provide a sensor for measuring characteristics representative of the drive torque applied to a wheel end 100 which is not external to the wheel end assembly 100, and which does not require additional time or labor to install during vehicle manufacture or assembly.
Briefly stated, the present disclosure provides a system for sensing the drive torque applied to a vehicle wheel end assembly internally within the wheel end. The sensor system is integrated into the internal spaces of the antifriction bearing within vehicle wheel end assembly, and is protected from environmental conditions. The sensor system incorporates a pair of sensing elements disposed on a stationary member of the vehicle wheel end assembly, and a target element disposed in proximity thereto on a rotating member of the vehicle wheel end assembly. Each sensing element generates a signal which is responsive to the passage of the target element, at a frequency which is proportional to the rotational speed of the wheel speed. Torsional twist of the wheel end hub member resulting from the application of a drive torque is registered as a phase shift between the signal output from each of the sensing elements, enabling the sensor system monitors the phase shift of the output signals as a measure of the drive torque applied to the vehicle wheel end assembly.
The foregoing features, and advantages set forth in the present disclosure as well as presently preferred embodiments will become more apparent from the reading of the following description in connection with the accompanying drawings.
In the accompanying drawings which form part of the specification:
Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. It is to be understood that the drawings are for illustrating the concepts set forth in the present disclosure and are not to scale. Further, the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings.
The following detailed description illustrates the invention by way of example and not by way of limitation. The description enables one skilled in the art to make and use the present disclosure, and describes several embodiments, adaptations, variations, alternatives, and uses of the present disclosure, including what is presently believed to be the best mode of carrying out the present disclosure.
Turning to the figures, and to
Torsional twist in the hub 102 can be measured using a sensor 200 with two sensing elements 202a and 202b spaced apart along the rotational axis of the bearing assembly 103 by a set distance. As is seen in
During rotation of the wheel end hub 102, each sensing element 202a and 202b produces a signal with a frequency which is proportional to the speed at which the magnetic encoders 204a and 204b rotate, i.e. the wheel speed. The torsional twist exerted on the wheel end hub 100 by the application of a drive torque will cause a phase shift to occur between the signals produced at each sensing element 202a and 202b, which are spaced in a known configuration aligned with the rotational axis of the wheel end hub 100. The relationship between the drive torque, torsional twist, and the observed phase shift is experimentally determined for each type of wheel end assembly 100 to enable the drive torque to be measured within the sealed environment of the hub and bearing assembly 100.
Turning to
As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
The present application is related to, and claims priority from, U.S. Provisional Patent Application Ser. No. 60/981,612 filed on Oct. 22, 2007, which is herein incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US08/80451 | 10/20/2008 | WO | 00 | 4/8/2010 |
Number | Date | Country | |
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60981612 | Oct 2007 | US |